Analytische Chemie
Filtern
Erscheinungsjahr
- 2016 (637) (entfernen)
Dokumenttyp
- Zeitschriftenartikel (214)
- Vortrag (193)
- Posterpräsentation (131)
- Beitrag zu einem Tagungsband (69)
- Sonstiges (10)
- Buchkapitel (6)
- Dissertation (5)
- Beitrag zu einem Sammelband (3)
- Forschungsbericht (3)
- Monografie (1)
Sprache
- Englisch (637) (entfernen)
Schlagworte
- XPS (25)
- Fluorescence (23)
- Concrete (19)
- Nanoparticles (19)
- Synchrotron (18)
- Simulation (16)
- NEXAFS (15)
- BAMline (13)
- LIBS (13)
- Mechanochemistry (13)
- XRF (13)
- Archaeometry (12)
- Imaging (11)
- Monitoring (11)
- Active thermography (10)
- Ultrasound (10)
- Computed tomography (9)
- Cultural heritage (9)
- EDX (9)
- Nanomaterial (9)
- Quantum yield (9)
- Rheology (9)
- SAXS (9)
- ICP-MS (8)
- LA-ICP-MS (8)
- Quantification (8)
- Cement (7)
- Electron microscopy (7)
- Laser ablation (7)
- Metrology (7)
- NIR (7)
- Nanoparticle (7)
- Raman spectroscopy (7)
- SERS (7)
- TiO2 (7)
- XRD (7)
- Calibration (6)
- DMD (6)
- DNA (6)
- Electron backscatter diffraction (6)
- Ferroelectret (6)
- Gas storage areas (6)
- In situ (6)
- Membrane-based gas sensing (6)
- Monte Carlo methods (6)
- Nanomaterials (6)
- Non-destructive testing (6)
- Online NMR spectroscopy (6)
- RFID sensors (6)
- Radiography (6)
- Round robin test (6)
- SIMS (6)
- Subsurface monitoring (6)
- XANES (6)
- AES (5)
- Antibody (5)
- DNA origami (5)
- Electrochemistry (5)
- Ellman (5)
- Flash excitation (5)
- IR (5)
- Integrating sphere spectroscopy (5)
- Magnetic field (5)
- Mass spectrometry (5)
- NDT (5)
- NMR (5)
- Optical spectroscopy (5)
- Pharmaceuticals (5)
- Plasma diagnostics (5)
- Raman (5)
- Reaction monitoring (5)
- SEM (5)
- Self-compacting concrete (5)
- Thin films (5)
- Traceability (5)
- AFM (4)
- Artificial digestion (4)
- CFRP (4)
- Cocrystal (4)
- Data fusion (4)
- Distributed linear sensor (4)
- Dye (4)
- ELISA (4)
- Embedded sensors (4)
- Energy harvesting (4)
- Flash thermography (4)
- Graphene (4)
- Hydrogen embrittlement (4)
- Immunoassay (4)
- Industrie 4.0 (4)
- Inverse analysis (4)
- Isotope dilution analysis (4)
- Laser induced plasma (4)
- Ligand analysis (4)
- MALDI-TOF MS (4)
- Measurements (4)
- Microstructure (4)
- Milling (4)
- Moisture (4)
- Nano (4)
- Paper (4)
- Particle size distribution (4)
- Plasma modeling (4)
- Polymer (4)
- Polymers (4)
- Process analytical technology (4)
- Quality assurance (4)
- RFA (4)
- Raman microscopy (4)
- Reference material (4)
- Rice husk ash (4)
- SAFT (4)
- Sensor (4)
- Silver nanoparticles (4)
- Soil (4)
- Standardization (4)
- Structural health monitoring (4)
- Surface analysis (4)
- TEM (4)
- Thermoacoustic (4)
- ToF-SIMS (4)
- Transmission characteristics (4)
- Ultrasonic transducer (4)
- Wireless sensors (4)
- Agricultural (3)
- Air-coupled (3)
- Aldrithiol (3)
- Ambient mass spectrometry (3)
- Analytical model (3)
- Antibodies (3)
- Assay (3)
- BESSY (3)
- Bio-imaging (3)
- Biocorrosion (3)
- Bioimaging (3)
- CCQM (3)
- CRM (3)
- Castings (3)
- Catalogues (3)
- Cell (3)
- Characterization (3)
- Chemometrics (3)
- Clustering (3)
- Dead Sea Scrolls (3)
- Dead Sea scrolls (3)
- Degradation (3)
- Depth profiling (3)
- Discontinuities (3)
- Dislocation (3)
- EBSD (3)
- EDS (3)
- Ellipsometry (3)
- Fiber bragg grating (3)
- Finite element method (3)
- Gas distribution mapping and gas source localization (3)
- Gas-phase NMR (3)
- Infrared spectroscopy (3)
- Laser (3)
- Least-squares adjustment (3)
- Life sciences (3)
- Magnetostrictive metal coating (3)
- Mass Spectrometry (3)
- Metal (3)
- Metal phosphonate (3)
- Microbiology (3)
- Microwave (3)
- Modeling (3)
- Modelling (3)
- OECD (3)
- Online (3)
- Online NMR (3)
- Online NMR Spectroscopy (3)
- Online monitoring (3)
- Optical assay (3)
- Oxidation (3)
- PEG (3)
- Pore radius (3)
- Process Analytical Technology (3)
- Prozessanalytik (3)
- Purity (3)
- RFID based sensors (3)
- RT (3)
- Relaxation time (3)
- Screed (3)
- Self-diagnostic fiber optical sensor (3)
- Semiconducor nanocrystals (3)
- Semitransparency (3)
- Single particle ICP-MS (3)
- Single-shot XAFS (3)
- Soil test field (3)
- Speciation (3)
- Spectral induced polarization (3)
- Strain (3)
- Sub-Saharan Africa (3)
- Superplasticizer (3)
- Surface protection (3)
- Synthesis (3)
- Thermal waves (3)
- Thermography (3)
- Thickness (3)
- Time resolution (3)
- Toxicity (3)
- UCST (3)
- Ultrasonic testing (3)
- Welding (3)
- Welds (3)
- X-rays (3)
- flow cytometry (3)
- fluorescence (3)
- Acoustic levitation (2)
- Active Thermography (2)
- Active pharmaceutical ingredient (API) (2)
- Adsorbates (2)
- Aerosol (2)
- Airborne (2)
- Analytical centrifuge (2)
- Artificial defect (2)
- Back-scatter techniques (2)
- Biocompatibility (2)
- Biofilms (2)
- Broadband dielectric spectroscopy (2)
- Carbograph 5TD (2)
- Carbopack X (2)
- Casting (2)
- Cement hydration (2)
- Centrifuge technology (2)
- Classification (2)
- Cocain (2)
- Coda wave interferometry (2)
- Composite (2)
- Computertomographie (2)
- Concrete evaluation (2)
- Core@Shell Nanoparticles (2)
- Corresponding relative humidity (2)
- Corrosion (2)
- Creep (2)
- Crystallization (2)
- Cytotoxicity (2)
- DRIFTS (2)
- Degree of purity (2)
- Digital image analysis (2)
- Distributed sensor (2)
- Dual-energy imaging (2)
- DuraBASt (2)
- Dyes (2)
- EC-MS (2)
- EDM (2)
- EPMA (2)
- ESI-TOF-MS (2)
- EXAFS (2)
- Electric discharge machining (2)
- Electron transport (2)
- Embedded (2)
- Embedded sensor (2)
- Energy reserves (2)
- Environmental analysis (2)
- Experiments (2)
- FRET (2)
- Ferrocene (2)
- Fiber Bragg grating (2)
- Fiber Bragg gratings (2)
- Field conditions (2)
- Field-flow fractionation (2)
- Finite Element Method (2)
- Flow cytometry (2)
- Fluorescence spectroscopy (2)
- Fluorescence standard (2)
- Fluorescent and thermoresponsive nanoparticles (2)
- GaP (2)
- Gas analysis (2)
- Geophysics (2)
- Gold nanoparticles (2)
- Grain geometry (2)
- High resolution ultrasonic testing (2)
- High-resolution (2)
- Honeycombing (2)
- Humidity sensors (2)
- Hydrogen assisted cracking (2)
- IR-MALDI (2)
- Immersion tank testing (2)
- Impurities (2)
- In situ analysis (2)
- Inspection (2)
- Inter-laboratory comparison (2)
- Invertebrates (2)
- Ionic liquids (2)
- Isotope dilution (2)
- Jet grouting (2)
- LC-MS/MS (2)
- Laminography (2)
- Leak detection (2)
- Levee (2)
- Lifetime (2)
- Lifetime encoding (2)
- Ligand (2)
- Ligand exchange (2)
- Linear sensor (2)
- Low field NMR spectroscopy (2)
- Machine learning (2)
- Magnetostriction (2)
- Manuscripts (2)
- Mapping (2)
- Membrane-based linear gas sensor (2)
- Mercury intrusion capillary pressure (2)
- Modular production units (2)
- Moisture measurements (2)
- Molecularly imprinted polymers (2)
- Monitoring of chemical reactions (2)
- Monte Carlo method (2)
- Multiplexing (2)
- Nanomaterial classification (2)
- Nanoparticles separation asymetrical flow field flow fractionation (2)
- Nanopartikel (2)
- Nd-sensitizer (2)
- Neutron imaging (2)
- Neutron radiography (2)
- Neutron tomography (2)
- Nondestructive testing (2)
- Oxidative stress (2)
- Oxidative stress biomarkers (2)
- PEG-Maleimide (2)
- Partial least squares regression (2)
- Particle size analysis (2)
- Peptides (2)
- Pesticides (2)
- Phased array (2)
- Photon-electron transport (2)
- Piezoelectric (2)
- Pigments (2)
- Plasma (2)
- Plasma physics (2)
- Platinum (2)
- PnCCD (2)
- Polycarboxylate ether (2)
- Polycrystalline materials (2)
- Polymer particles (2)
- Pore geometry (2)
- Probes (2)
- Process control (2)
- Proficiency testing (2)
- Protein quantification (2)
- Prozess-Sensoren (2)
- Purity assessment (2)
- Quality control (2)
- Quality system (2)
- Quantitative NMR spectroscopy (2)
- Quantitative NMR-Spektroskopie (2)
- Quantum dots (2)
- Radiology (2)
- Ray tracing (2)
- Reaction Monitoring (2)
- Reference defect (2)
- Reference materials (2)
- Reproducibility (2)
- Rock structure (2)
- SEC (2)
- SEP 1927 (2)
- SIP (2)
- SLM (2)
- STM (2)
- Semiconductor quantum dot (2)
- Shape (2)
- Silica support (2)
- Smart Sensors (2)
- Standard (2)
- Standardisation (2)
- Standards (2)
- Strength (2)
- Structure health monitoring (2)
- Substrate (2)
- Sulfamethoxazole (2)
- Superalloy (2)
- Superplasticizers (2)
- Surface chemical analysis (2)
- Surface-enhanced Raman scattering (2)
- Synchrotron radiation (2)
- Tattoo (2)
- Temperature (2)
- Thermal Wave (2)
- Thermal desorption (2)
- Thin film (2)
- Thiols (2)
- Time-of-flight mass spectrometry (2)
- Two photon microscopy (2)
- UCNP (2)
- Upconversion (2)
- Upconversion nanocrystals (2)
- VVOC (2)
- Water (2)
- Workability (2)
- X-Ray diffraction (2)
- X-ray absorption spectroscopy (2)
- X-ray microdiffraction (2)
- X-ray refraction (2)
- X-ray spectroscopy (2)
- ambient mass spectrometry (2)
- chemical sensing (2)
- computed tomography (2)
- emission spectroscopy (2)
- gold nanoparticles (2)
- immunoassay (2)
- life sciences (2)
- lifetime encoding (2)
- mass spectrometry (2)
- metrology (2)
- nanoprobes (2)
- polymer particles (2)
- purity (2)
- quality control (2)
- silver nanoparticles (2)
- standardization (2)
- traceability (2)
- upconversion (2)
- “Click” chemistry (2)
- (HAX)PES (1)
- 19F-NMR (1)
- 1H-NMR (1)
- 2-D electrophoresis (1)
- 29Si-27Al TRAPDOR MAS (1)
- 29Si{27Al} TRAPDOR MAS NMR (1)
- 2D gel electrophoresis (1)
- 2PM Fly Scan (1)
- 3D (1)
- 3D High-temperature shape screening (1)
- 3D reconstruction (1)
- Ab initio calculations (1)
- Accelerated stress testing (1)
- Acoustic actuator (1)
- Activatable probe (1)
- Activation energy (1)
- Active thermal cycling (1)
- Actuators (1)
- Additive Manufacture (1)
- Adhesive tapes (1)
- Adhesives and adhesive tapes (1)
- Admixtures (1)
- Adsorption (1)
- Adulteration detection (1)
- Advanced oxidation processes (1)
- Ag nanoparticles (1)
- Aggregation (1)
- Aggregation-induced emission (1)
- Air purification (1)
- Airport security (1)
- Algorithm (1)
- Aluminium (1)
- Aluminosilicates (1)
- Ambient (1)
- Amides (1)
- Amine derivatives (1)
- Amines (1)
- Amino acid analysis (1)
- Ammonia (1)
- Ammonia in ambient air (1)
- Amorphous materials (1)
- Analysis of lanthanoides (1)
- Analytical approach (1)
- Analytical centrifugation (1)
- Analytical method (1)
- Analytical methods (1)
- Analytics (1)
- Annular space (1)
- Anti-fouling (1)
- Anti-oxidative efficiency (1)
- Antibody ID (1)
- Antibody immobilization (1)
- Antibody labeling (1)
- Antikörper (1)
- Application (1)
- Applications (1)
- Aqueous dispersion (1)
- Aqueous solution (1)
- Ar gas cluster gun (1)
- Archaeology (1)
- Archäologie (1)
- Art (1)
- Artificial photosynthesis (1)
- Arzneistoffe (1)
- Atherosclerotic plaques (1)
- Atmosphärendruck (1)
- Atmosphärendruck-Massenspektrometrie (1)
- Atmosphärendruckmassenspektrometrie (1)
- Atom transfer radical polymerization (1)
- Atomic weight (1)
- Au(111) (1)
- Auger electron spectroscopy (1)
- Automation (1)
- Automotive industry (1)
- Autonomous micro UAV (1)
- Azidation (1)
- Azimuthal temperature field (1)
- Azimuthal well logging (1)
- BAM L200 (1)
- BAM certification body (1)
- BCA assay (1)
- BDS broadband dielectric spectroscopy (1)
- BET specific surface area (1)
- BODIPY (1)
- BRET/CRET (1)
- Back scatter (1)
- Backscatter application (1)
- Bacteria (1)
- Bacterial Extracellular Electron Transfer Mechanisms (1)
- Bacterial biofilms (1)
- Barium titanate nanopowder (1)
- Benzamide (1)
- Benzene sensor (1)
- Berlin Main Station (1)
- Berlin tap water (1)
- Bibliothek ternärer Pd-Legierungen (1)
- Bio imaging (1)
- Bio-Imaging (1)
- Bio-molecular surfaces (1)
- Bioerosion (1)
- Biofilm (1)
- Biolabels (1)
- Biological application (1)
- Biological structure (1)
- Biologically inspired robots (1)
- Biomarker (1)
- Biomarkers (1)
- Bioorganic film (1)
- Biosensor (1)
- Biotin–FITC titration (1)
- Biotoxins - Biotoxine (1)
- Biotransformation (1)
- Bisphenol A (1)
- Bivalves (1)
- Bonding (1)
- Bonding strength (1)
- Borate glasses (1)
- Braunschweig meteorite (1)
- Breath (1)
- Breath alcohol analyser (1)
- Bremsstrahlung (1)
- Brinell (1)
- Broadband Dielectric Spectroscopy (1)
- Broadband Dielectric Spectrscopy (1)
- Brominated carbon nanotubes (1)
- Bruchmechanik (1)
- Building materials (1)
- Bulk chemistry (1)
- CCQM-K101 (1)
- CEFIT (1)
- CFD (1)
- CFD simulation (1)
- CFK (1)
- CIGS (1)
- CIGS thin films (1)
- CMC (1)
- CO adsoprtion (1)
- CO adsorption (1)
- CONSENS (1)
- COOMET.QM-S5 (1)
- CRM producer (1)
- CT (1)
- Caco-2 cells (1)
- Calcium phosphate cement (1)
- Calcium-carbonate (1)
- Calculation (1)
- Calibration-free analysis (1)
- Calibration-free laser-induced breakdown spectroscopy (1)
- Cancer (1)
- Carbamazepine (1)
- Carbon dots (1)
- Carbon nanomembranes (1)
- Carbon nanotubes (1)
- Carbonate substrate (1)
- Carotenoids (1)
- Catalyst (1)
- Catalytic activity (1)
- Cations (1)
- Cell proliferation (1)
- Cell viability (1)
- Cellular internalization (1)
- Cellular polypropylene (1)
- Cellular uptake (1)
- Cement clinker (1)
- Cement paste (1)
- Central Asia (1)
- Ceramic (1)
- Ceramic dispersion (1)
- Ceramic suspension (1)
- Ceramics (1)
- Certification (1)
- Certified reference material (1)
- Certified reference materials (1)
- Channeling (1)
- Characterisation techniques (1)
- Characterization and analytical techniques (1)
- Charakterisierung (1)
- Charge separation (1)
- Charge transfer (1)
- Chemical analysis (1)
- Chemical derivatization (1)
- Chemical imaging (1)
- Chemical imaging analysis (1)
- Chemical modification (1)
- Chemical sensors (1)
- Chemical warfare agents (1)
- Chemische Modifizierung (1)
- Chemometric tool (1)
- Chiral (1)
- Chloride (1)
- Chlorophyll (1)
- Cisplatin (1)
- Clams (1)
- Click chemistry (1)
- Clinoptilolite (1)
- Coal (1)
- Coating (1)
- Coatings (1)
- Cobalt (1)
- Coffee (1)
- Color coding (1)
- Compact NMR (1)
- Comparison of techniques (1)
- Composition (1)
- Computer modeling (1)
- Confinement (1)
- Conformational analysis (1)
- Consolidated materials (1)
- Constitutive relations (1)
- Consume care products (1)
- Control charts (1)
- Copolyester (1)
- Copolymer (1)
- Copolymer sequence (1)
- Copper(II) - phenanthroline - complexe filmss (1)
- Core (1)
- Core / shell / shell / nanoparticles (1)
- Core shell nano particle (1)
- Core-Shell (1)
- Core/shell particles (1)
- Coulometric sensor (1)
- Coverslip seal (1)
- Crack detection (1)
- Creep-resistant steel (1)
- Crisis (1)
- Crystal-growth (1)
- Crystallinity (1)
- Cumin discrimination (1)
- Cusum (1)
- Cyanine (1)
- Cyclic voltammetry (1)
- Cyclization (1)
- Cyclohexane (1)
- Cytometry (1)
- D2XRF (1)
- DFT spectrum simulations (1)
- DLS (1)
- DMD coupled laser (1)
- DNA damage (1)
- DNA origami nanostructures (1)
- DNA radiation damage (1)
- DNA sensor (1)
- DNA-Schädigung (1)
- DNA/RNA (1)
- DPSS laser (1)
- Damage (1)
- Dangerous goods container (1)
- Data processing (1)
- Databases (1)
- Debye-Waller factor (1)
- Deconvolution (1)
- Dedolomite (1)
- Defect detection (1)
- Defects (1)
- Degree of equivalence (1)
- Density (1)
- Density estimation (1)
- Density of states (1)
- Depth-Profiling (1)
- Depth-profiling (1)
- Design of Experiments (1)
- Diabetes mellitus and Alzheimer's disease (1)
- Diagnosis of concrete components (1)
- Diagnostics (1)
- Diameter (1)
- Dielectric barrier discharge (1)
- Dielectric materials (1)
- Differential displacements (1)
- Diffraction contrast (1)
- Diffusion (1)
- Digestion (1)
- Digital detector arrays (1)
- Digital radiography (1)
- Dimensionelle Metrologie (1)
- Diopatra neapolitana (1)
- Direction-oriented image (1)
- Directional interface variance analysis (DIVA) (1)
- Discrimination of multiple gas sources (1)
- Dissociative electron attachment (1)
- Divergent XAFS (1)
- Drop test (1)
- Duplex stainless steel (1)
- Dye bioconjugates (1)
- Dynamic glass transition (1)
- Dynamical theory (1)
- EC definition of nanomaterial (1)
- EDS Geometrical Detection Efficiency (1)
- EDS Solid Angle (1)
- EDS detector (1)
- EDS net active sensor area (1)
- EISA (1)
- EMRP (1)
- EN 196 (1)
- EPTIS (1)
- ESEM (1)
- EU (1)
- Ectoine (1)
- Education of NDT personnel (1)
- Effective area (1)
- Eigenspannungen (1)
- Electrical methods (1)
- Electrochromic device (1)
- Electrochromism (1)
- Electrohydraulic effect (1)
- Electron tomography (1)
- Electronic Nose (1)
- Electronic nose (1)
- Electrons (1)
- Electrspray deposition (1)
- Elektronen (1)
- Element microscopy (1)
- Elevated temperatures (1)
- Eluting stent (1)
- Emerging Pollutants (1)
- Emissionsspektroskopie (1)
- Energetic material (1)
- Energy dissipation (1)
- Energy sensor (1)
- Energy transfer (1)
- Energy-dispersive X-ray spectrometer (EDS) (1)
- Environmental quality standard (EQS) (1)
- Environmentally relevant concentrations (1)
- Enzyme sensor (1)
- Epoxy (1)
- Euramet EMRP (1)
- Europium complex (1)
- Excitation (1)
- Exfoliation (1)
- Explosives (1)
- Expression of uncertainty (1)
- FAME (1)
- FE-EPMA (1)
- FEFF (1)
- FFT periodogram (1)
- FIB (1)
- FRET system (1)
- FT-IR spectroscopy (1)
- Fall reconstruction (1)
- Faujasite-type zeolites (1)
- Fault tree analysis (1)
- Fenton (1)
- Fiber characterization (1)
- Fiber optics sensors (1)
- Fiber-optic sensor (1)
- Fibre optical sensing (1)
- Field Enhancement (1)
- Field flow fractionation (1)
- Figures of merit (1)
- Film thickness determination (1)
- Finite element methods (1)
- Flash lamp (1)
- Flat bottom holes (1)
- Flow Cytometry (1)
- Fludarabine (1)
- Flugzeitmassenspektrometer (1)
- Flugzeitmassenspektrometrie (1)
- Fluorapatite-gelatin nanocomposites (1)
- Fluorescence sensor (1)
- Fluorescence spectroscopy and imaging (1)
- Fluorescent amplification strategies (1)
- Fluorescent nanoreporters (1)
- Fluoresence (1)
- Fluorophore (1)
- Fluorophore tracer (1)
- Focusing (1)
- Foldamers (1)
- Forgery (1)
- Foundations (1)
- Fresh Concrete (1)
- Fresh concrete (1)
- Friction (1)
- Friedel's rule (1)
- Full matrix capture (1)
- Fullerene (1)
- Fullerene C60 (1)
- Functional group analysis (1)
- Functionalization (1)
- Functionalization of fullerenes (1)
- Fungal Volatiles (1)
- Fusarium Mycotoxins (1)
- G quadruplex (1)
- GD-MS (1)
- GDMS (1)
- GIXRF (1)
- GMR (1)
- GTA-Welding (1)
- GaAs (1)
- GaN (1)
- Gadolinium-based contrast agents (1)
- Gadolinium-uptake (1)
- Gas Sensors, Safety (1)
- Gas chromatography (1)
- Gas sensor (1)
- Gas sensors (1)
- Gas source localization (1)
- Gated delivery system (1)
- Gated release systems (1)
- Geographical origins (1)
- Geometrical collection efficiency (1)
- Geopolymer (1)
- Glow discharge (1)
- Glucose and nanoplaque formation (1)
- Glycan microarray (1)
- Gold (1)
- Gold Synchrotron XRF (1)
- Gold surface (1)
- Gold-Nanopartikel (1)
- Grain boundaries (1)
- Granules (1)
- Graphene oxide (1)
- Groundwater observation well (1)
- Grouping (1)
- Guest complexe (1)
- Guided waves (1)
- Gypsum (1)
- HDL protection (1)
- HILIC (1)
- HPLC (1)
- HPLC-MS/MS (1)
- HR-SEM (1)
- HRMS-Identifizierung (1)
- HS-PG flow sensor and lipoprotein receptor (1)
- Hair follicles (1)
- Hardening (1)
- Hardness testing (1)
- Harmful Algal Bloom (HAB) (1)
- Headspace Analysis (1)
- Headspace GC (1)
- Heat shock response (1)
- Heat treatment condition (1)
- Heterogeneity (1)
- Heterogeneous photocatalysis (1)
- High impact testing (1)
- High performance liquid chromatography (1)
- High pressure (1)
- High repetition rate (1)
- High resolution continuum source absorption spectrometry (1)
- High strength concrete (1)
- High strength steels (1)
- High throughput biosensing (1)
- High-pressure NMR (1)
- High-repetition rate laser (1)
- High-resolution ICP-MS (1)
- High-speed biosensor (1)
- Histology (1)
- Homogeneity (1)
- Homogenisation (1)
- Hot crack (1)
- Hot spot (1)
- Humic acid (1)
- Humidity induced annealing (1)
- Hybrid materials (1)
- Hybrid nanoparticles (1)
- Hybrid sensor materials (1)
- Hydrates (1)
- Hydration (1)
- Hydraulic levelling system (1)
- Hydrazinchemie (1)
- Hydroformylation (1)
- Hydrogen (1)
- Hydrogen Sensors (1)
- Hydrogen Technologies (1)
- Hydrogen bonds (1)
- Hydrogen diffusion (1)
- Hydrogen sensor (1)
- Hydrogen trapping (1)
- Hydrolysis (1)
- Hydrophilic interaction chromatography (HILIC) (1)
- IDLapoE3/E3 and IDLapoE4/E4 isoforms (1)
- IDMS (1)
- IHM (1)
- ILC (1)
- IR spectroscopy (1)
- ISO (1)
- ISO standards (1)
- Image Analysis (1)
- Image morphology (1)
- Imaging ToF SIMS (1)
- Imaging ellipsometry (IE) (1)
- Imaging plates (1)
- Imaging technique (1)
- Immuno imaging (1)
- Immuno-assays (1)
- Immunoarrays (1)
- Immunosensor (1)
- In situ measurement (1)
- In situ reactions (1)
- In vitro (1)
- In-situ loading (1)
- Indirect hard modeling (1)
- Indometacin (1)
- Inductively coupled plasmamass spectrometry (ICP-MS) (1)
- Industrial gases (1)
- Infrared Thermography (1)
- Infrared imaging (1)
- Infrared thermography (1)
- Inhibition assay (1)
- Inhibition rate constant (1)
- Ink (1)
- Integrity (1)
- Interface analysis (1)
- Interfaces (1)
- Interlaboratory Study (1)
- Interlaboratory comparison (1)
- Intermediate (1)
- Internal standard (1)
- Internal standardization (1)
- Inverse Analysis (1)
- Iodonium (1)
- Ion Mobility (1)
- Ion mobility (1)
- Ion mobility spectrometry (1)
- Ionenquelle (1)
- Ionic liquid (1)
- Ionisation (1)
- Ionisierung (1)
- Ionization (1)
- Ir (1)
- Iron and steel (1)
- Iron oxide (1)
- Isoelectric point (1)
- Isomerisierung (1)
- Isotope dilution mass spectrometry (1)
- Isotope mixture (1)
- Isotope ratio (1)
- Isotopenstandard (1)
- Iterative reconstruction (1)
- Katalysator (1)
- Key comparison (1)
- Kinematic theory (1)
- Kompositen (1)
- KonSens (1)
- KorroPad (1)
- Kulturelles Erbe (1)
- Kunst (1)
- L chondrite (1)
- LA-ICP-MS based immunoassays (1)
- LA-ICP-MS microscopy (1)
- LEIS (1)
- Lab-on-valve (1)
- Lactide (1)
- Langmuir isotherm (1)
- Lapis Lazuli (1)
- Large animal model (1)
- Laser Ablation (1)
- Laser Induced Breakdown Spectroscopy (LIBS) (1)
- Laser Induced Fluorescence (LIF) (1)
- Laser ablation (LA)-ICP-MS (1)
- Laser ablation ICP-MS (1)
- Laser induced breakdown spectroscopy (LIBS) (1)
- Laser induziertes Plasma (1)
- Laser profilometry (1)
- Laser-based displacement measuring system (1)
- Laser-induced plasma (1)
- Laser-spark (1)
- Lateral resolution (1)
- Lattice parameter determination (1)
- Layer-by-layer deposition (1)
- Lead isotopic composition (1)
- Least-Squares Adjustment (1)
- Legierungen (1)
- Leguminosen (1)
- Library of ternary Pd-alloys (1)
- Ligands (1)
- Light damage (1)
- Light microscopy (1)
- Line scan (1)
- Lipid Nanodiscs (1)
- Liposomes (1)
- Liquefied gases (1)
- Liquefied petroleum gas (1)
- Liquid cell (1)
- Liquid chromatography (1)
- Lithiation (1)
- Ln-MeCAT-Click labeling (1)
- Load (1)
- Load partition (1)
- Lock-in Thermografie (1)
- Lock-in thermography (1)
- Long-life sensor casing (1)
- Long-term exposure (1)
- Long-term exposures (1)
- Low energy (1)
- Low-cost housing (1)
- Luminescent probes (1)
- MALDI (1)
- MALDI-TOF MS/MS (1)
- MALDI-TOF Mass Spectrometry (1)
- MALDI-TOF-MS (1)
- MDFEM (1)
- MOF (1)
- MOFs (1)
- Macrocycles (1)
- Magnesium (1)
- Magnetic nanocomposites (1)
- Magnetische Nanopartikel (1)
- Magnetite nanoparticles (1)
- Magnetron sputtering (1)
- Manual testing (1)
- Manuskripte (1)
- Marker (1)
- Mass cytometry (1)
- Mass deposition (1)
- Material analysis (1)
- Material equations (1)
- Materialanalyse (1)
- Matrix influence (1)
- Measurement and testing (1)
- Measurement techniques (1)
- Medium-resolution NMR (1)
- Membrane (1)
- Membrane polarization (1)
- Mercury (1)
- Mercury intrusion (1)
- Mesoporous Silica (1)
- Metabolic transformation (1)
- Metabolites (1)
- Metal Matrix Composites (1)
- Metal elements (1)
- Metal matrix composites (1)
- Metal nanoparticles (1)
- Metal phosphonates (1)
- Metal staining procedures (1)
- Metallo-supramolecular polyelectrolytes (1)
- Metalloproteins (1)
- Metals (1)
- Method development (1)
- Method validation (1)
- Microbeads (1)
- Microbiological induced corrosion (1)
- Microbiologically induced corrosion (1)
- Microfluidic sensor (1)
- Microfluidics (1)
- Microporous (1)
- Microscopy (1)
- Microspectroscopic imaging (1)
- Microstrain (1)
- Microstrain distribution (1)
- Microstructured fibers (1)
- Mineral additions (1)
- Miniature (1)
- Miniaturization (1)
- Miniaturized AF4 channel (1)
- Minimal-invasive (1)
- Missing wedge (1)
- Mobile robot olfaction (1)
- Modeling and simulation (1)
- Moisture measuring (1)
- Molecular alignment relaxation (1)
- Molecular beacon (1)
- Molecular devices (1)
- Molecular diagnostics (1)
- Molecular machines (1)
- Molecular motor (1)
- Molecular-dynamics (1)
- Monitoring of CO 2 (1)
- Monitoring of dangerous goods (1)
- Monoklonal (1)
- Monolayer (1)
- Monte Carlo simulation (1)
- Mounting medium (1)
- Multi-parameter POD (1)
- Multi-sensor data fusion (1)
- Multi-walled carbon nanotubes (1)
- Multichannel measuring (1)
- Multigas sensor (1)
- Multiple-sample bonding (1)
- Multiple-sample testing (1)
- Multiplexing immunoassay (1)
- Multivariate analysis (1)
- Multivariate statistics (1)
- Mycotoxin (1)
- Mycotoxins (1)
- NDT reliability (1)
- NDT-CE (1)
- NIR spectroscopy (1)
- Nano materials (1)
- Nano particles (1)
- Nano scale (1)
- Nanoclay hybrids (1)
- Nanocomposite (1)
- Nanocomposites (1)
- Nanomaterialien (1)
- Nanometrology (1)
- Nanoparticle coating (1)
- Nanoporous Al2O3 (1)
- Nanorings (1)
- Nanoroughness (1)
- Nanosensor (1)
- Nanostructured Electrodes (1)
- Natural zeolite Clinoptilolite (1)
- Near-infrared laser (1)
- Nephrotoxicity (1)
- Nerve gases (1)
- Net effective sensor area (1)
- Neurons (1)
- Neutron diffraction (1)
- Neutron scattering (1)
- Neutronenbeugung (1)
- Ni-base superalloy (1)
- Nickel RSF (1)
- Nicotinamide (1)
- Nile Red (1)
- Noble gas isotopes (1)
- Non-centrosymmetry (1)
- Non-destructive methods (1)
- Non-ferrous metals (1)
- Nondestructive flaw detection (1)
- Nonlinear rheology (1)
- Normung (1)
- Nuclear (1)
- Nuclear magnetic resonance (1)
- Nucleation (1)
- Nucleic acids (1)
- Number-weighted median size (1)
- Numeric modelling (1)
- Numerical modeling (1)
- Ocean acidification (1)
- Oil diesel fraction (1)
- On-site LIBS (1)
- One-part formulation (1)
- Online Monitoring (1)
- Online-NMR spectroscopy (1)
- Online-Raman spectroscopy (1)
- Optical characterization (1)
- Optical fiber sensor climatic stability (1)
- Optical layer model (1)
- Optical layer reconstruction (1)
- Optical microscopy (OM) (1)
- Optical properties (1)
- Optical sensor (1)
- Optical transfer standard (1)
- Optically pumped plasma lasers (1)
- Organic layers (1)
- Organic matter (1)
- Organic osmolytes (1)
- Organic pollutants (1)
- Orientation description (1)
- Osteoporosis (1)
- Oxide-films (1)
- Oxygen-containing functionalities (1)
- PAMAM dendrimers (1)
- PFOA (1)
- PFOS (1)
- PIM-1 (1)
- PIXE (1)
- PLS-R (1)
- PLSR (1)
- PLasma physics (1)
- PT (1)
- Packing density (1)
- Paper spray ionization (1)
- Papier (1)
- Papierbasiert (1)
- Paracetamol (1)
- Parallel computing (1)
- Parallel seismic (1)
- Passive layer (1)
- Pattern matching (1)
- Peel (1)
- Perfluordecalin (1)
- Peri-implantitis (1)
- Permeability (1)
- Permeation (1)
- Pesticide parathion-methyl (1)
- Petrology and mineralogy (1)
- Pharmaceutical drugs (1)
- Pharmazeutika (1)
- Phase distribution (1)
- Phase identification (1)
- Phase measurement (1)
- Phase transfer (1)
- Phenylalanine (1)
- Phomopsin-Derivate (1)
- Phosphates (1)
- Photocatalysis (1)
- Photochemistry (1)
- Photoelectron spectroscopy (1)
- Photoexcitation (1)
- Photoinduced electron-transfers (1)
- Photoligation (1)
- Photoluminescence quantum yield (1)
- Photon counting detectors (1)
- Photonic baking (1)
- Photonic wire (1)
- Photophysics (1)
- Photopolymer (1)
- Photoswitchable rotaxane (1)
- Phthalocyanines (1)
- Pichia pastoris (1)
- Pigment (1)
- Pigmentanalyse (1)
- Pile integrity testing (1)
- Pile length (1)
- Piles (1)
- Plasma tomography (1)
- Plasma-chemical technique (1)
- Plasmapolymer (1)
- Plasmonic (1)
- Platinum Wavelength dispersive D2XRF (1)
- Polarity probe (1)
- Pollen (1)
- Pollution (1)
- Poly(glycidyl methacrylate) (1)
- Polybrominated diphenylether (1)
- Polycrystalline thin films (1)
- Polycyclic aromatic hydrocarbons (1)
- Polyester (1)
- Polyethylene composites (1)
- Polyethylene glycol (1)
- Polymer adsorption (1)
- Polymer matrix (1)
- Polymer optical fibers (1)
- Polymeric tubes (1)
- Polymorphism (1)
- Polymorphs (1)
- Polysarcosine (1)
- Polystyrene nanoparticles (1)
- Pophycene (1)
- Pore diameter (1)
- Pore throat size (1)
- Pores (1)
- Porosity (1)
- Porous medium (1)
- Porphyrin (1)
- Porphyrins (1)
- Portland cement (1)
- Portland cement Initial hydration (1)
- Post-breakdown laser induced plasma (1)
- Power electronic chips (1)
- Precipitation (1)
- Precision (1)
- Preventive conservation (1)
- Primary method of measurement (1)
- Printed internal standard (1)
- Process Control (1)
- Product certification (1)
- Protein (1)
- Protein analysis (1)
- Protein association (1)
- Protein coating (1)
- Protein corona (1)
- Protein unfolding (1)
- Proteins (1)
- Proteomics (1)
- Provenance studies (1)
- Prozess-Sensoren 4.0 (1)
- Prozess-Spektroskopie (1)
- Précision (1)
- Pt-based drugs (1)
- Pull-out (1)
- Pulse reflection (1)
- Pulse shape analysis (1)
- Purification (1)
- Purity determination (1)
- Pyrroles (1)
- Q4(mAl) sites (1)
- Quality (1)
- Quality infrastructure (1)
- Quantitative NMR (1)
- Quantitative proteomics (1)
- Quantum Yield (1)
- Quantum dot (1)
- Quaternary oxides (1)
- Qumran archaeology (1)
- R package (1)
- RAFT (1)
- REM/EDX (1)
- RFID Sensors systems (1)
- Radionuclides (1)
- Radon transform technique (1)
- Railway (1)
- Raman imaging (1)
- Raman microspectroscopy (1)
- Raman-spectroscopy (1)
- Rate of model oxidation (1)
- Re-XANES (1)
- Reactive plume tracking (1)
- Recombination (1)
- Reconstruction (1)
- Redox-reactions (1)
- Redoxreactions (1)
- Reference (1)
- Reference Material (1)
- Reference gas mixtures (1)
- Reference gas standards (1)
- Reference-free XRF (1)
- Referenced spectroscopic ellipsometry (RSE) (1)
- Referenzmaterialien (1)
- Regenerative capacity (1)
- Registration errors (1)
- Reinforced composites (1)
- Reinforcement (1)
- Relaxation (1)
- Release (1)
- Renewable energy (1)
- Resource Analytics (1)
- Ressourcenanalytik (1)
- Reversibility (1)
- Ribonuclease A (1)
- Ringversuche (1)
- Risk management (1)
- Ru dye sensitizer (1)
- SEIRA Technique (1)
- SHM in civil engineering (1)
- SNR (1)
- SPE-HPLC Automatisierung (1)
- SPME-GC-MS (1)
- SPR effect (1)
- SR-µ-XRF (1)
- STRATAGem (1)
- STXM (1)
- SURMOF (1)
- Safe innovation (1)
- Safety (1)
- Sample changer (1)
- Sample preparation (1)
- Samples (1)
- Scaled Boundary Finite Element Method (1)
- Scanning Transmission Electron Microscopy (1)
- Scanning electron microscopy (1)
- Scanning probe microscopy (1)
- Scanning transmission electron microscopy (1)
- Scattered data (1)
- Schadenstoleranz (1)
- Schadstoffe (1)
- Schweißnähte (1)
- Schwingfestigkeit (1)
- Secondary structure (1)
- Seidenstraßenkultur (1)
- Seismic (1)
- Selective Electron Beam Melting (1)
- Selectivity (1)
- Self assembly (1)
- Self-assembled monolayer (1)
- Self-assembly (1)
- Semiconductor device reliability (1)
- Semtex (1)
- Sensitivity (1)
- Sensor calibration (1)
- Sensor system (1)
- Sensors (1)
- Separation (1)
- Shadowgraphy (1)
- Shear (1)
- Shear exfoliation (1)
- Shear strength (1)
- Shear-horizontal modes (1)
- Sheet resistivity (1)
- Shelf life prediction (1)
- Shell (1)
- Shell nanoparticles (1)
- Shewanella (1)
- Signal amplification (1)
- Signal processing (1)
- Signal-to-noise ratio (1)
- Silanes (1)
- Silicon nitride (1)
- Silicone analysis (1)
- Silk Road (1)
- Silver (1)
- Simple-shear rheometer (1)
- Single cable serial connection (1)
- Single cell analysis (1)
- Sintering (1)
- Skin tissue (1)
- Slabs (1)
- Slippage of weakly linked layers (1)
- Slurry (1)
- Small angle scattering (1)
- Small-angle X-ray scattering (1)
- Small-angle scattering (1)
- Smart sensors (1)
- SnO2 (1)
- SnOx (1)
- Software (1)
- Sol-gel (1)
- Solar-energy (1)
- Solid angle (1)
- Solid phase microextraction (1)
- Solid-state NMR (1)
- Solution plasma (1)
- Solvent polarity (1)
- Sound source (1)
- South Africa (1)
- Spatial light modulation (1)
- Spatial light modulator (1)
- Spatial resolution (1)
- Speciation of Gd-containing MRI contrast agents (1)
- Specific adsorption (1)
- Specific heat (1)
- Specific pore volume (1)
- Specific surface (1)
- Spectra annotation (1)
- Spectral correction (1)
- Spectral induced polarisation (1)
- Spectroelectrochemical Techniques (1)
- Spectrometry (1)
- Spectroscopic ellipsometry (1)
- Spectrum (1)
- Spice (1)
- Spot weld (1)
- Spray drying (1)
- Sputtered thin aluminium film (1)
- Stabilisotopenverdünnungsanalyse (1)
- Stability assessment (1)
- Stabilization of HT-structures at room temperature (1)
- Stabilized dispersions (1)
- Stabilizer (1)
- Stabilty (1)
- Stainless steel (1)
- Standardisierung (1)
- Steel slag (1)
- Stereoscopy (1)
- Strain measurements (1)
- String metal support interaction (1)
- Strong metal support interaction (1)
- Structural characterization (1)
- Structural health (1)
- Subsurface defects (1)
- Sulfur-matrix separatio (1)
- Sulphate-chloride attack (1)
- Super somputing (1)
- Superplasticiser (1)
- Superplaticizers (1)
- Supplementary cementitious materials; (1)
- Supramolecular chemistry (1)
- SurfMOF (1)
- Surface Enhanced Raman Spectroscopy (1)
- Surface analysis; (1)
- Surface chemistry (1)
- Surface enhanced Raman Spectroscopy (1)
- Surface enhanced Raman spectroscopy (1)
- Surface water (1)
- Suspended particulate matter (1)
- Switchable rotaxane (1)
- Symmetry groups (1)
- Synchrotron CT (1)
- Synchrotron radiation X-ray fluorescence (1)
- Synchrotron radiation XPS (1)
- Synthetic aperture focusing (1)
- T-SEM (1)
- TF Material (1)
- TGA (1)
- THz (1)
- THz SAFT Optical layer reconstruction (1)
- THz spectroscopy (1)
- THz time-domain spectroscopy (THz-TDS) (1)
- TNT (1)
- TPA (1)
- TXRF (1)
- TXRF-XANES (1)
- Tandem MS (1)
- Taxonomy (1)
- Temperature sensor (1)
- Tensile (1)
- Tensile strength (1)
- Test gas generation (1)
- Test strip analysis (1)
- Textural controls (1)
- Texture (1)
- The Temple Scroll (1)
- Thermal Waves (1)
- Thermal analyses (1)
- Thermal annealing (1)
- Thermal desorption analysis (TDA) (1)
- Thermal expansion (1)
- Thermal imaging (1)
- Thermal wave (1)
- Thermoacoustics (1)
- Thermomechanical fatigue (1)
- Thermoresponsive polymer (1)
- Thin-film solar cells (1)
- Thiol assay (1)
- Three-dimensional (3D) characterization (1)
- TiO2 coating (1)
- TiO2 films (1)
- Tiered (1)
- Time-of-flight secondary-ion mass spectrometry (1)
- TimeGate (1)
- Tinte (1)
- Tissue (1)
- Titanium (1)
- Titanium dioxide (1)
- ToF (1)
- ToF MS (1)
- ToF SIMS (1)
- Tomography (1)
- Toroids (1)
- Torsional modes (1)
- Total focussing method (1)
- Toxic metals (1)
- Toxicological studies (1)
- Toxicology (1)
- Toxizität (1)
- Trace Humidity (1)
- Trace element (1)
- Trace elements (1)
- Trace humidity (1)
- Transducer (1)
- Transformation products (TPs) (1)
- Transmission (1)
- Transmission electron microscopy (1)
- Tributyltin (1)
- Tributyltin (TBT) (1)
- Trichodiene (1)
- Trinitrotoluene (1)
- Tryptophan (1)
- Turfan Manuskripte (1)
- Turfan manuscripts (1)
- Tyrosine (1)
- UPLC (1)
- UPLC-MS/MS (1)
- UV/VIS spectroscopy (1)
- Ultra-Thin films (1)
- Ultra-thin polymer films (1)
- Ultra-trace analysis (1)
- Ultraschall (1)
- Ultrasonic (1)
- Ultrasonic echo (1)
- Ultrasonic imaging (1)
- Ultrasonic tests (1)
- Uncertainty (1)
- Uncertainty budgets (1)
- Upconversion nanoparticle (1)
- VAMAS (1)
- VCSEL (1)
- VIS-spectrophotometry (1)
- VOC degradation (1)
- VSSA (1)
- Validation and testing infrastructure (1)
- Vanadium oxide (1)
- Vertebroplasty (1)
- Vertical fluid movement (1)
- Vibrations (1)
- Vibrator (1)
- Vickers (1)
- Viscoelastic (1)
- Viscosity (1)
- Void defect (1)
- Volatile organic compounds (1)
- Volatilome (1)
- Voltammetric electronic tongue (1)
- WDX (1)
- Wall paintings (1)
- Wasserstoffsensor (1)
- Waste paper sludge (1)
- Waste-water (1)
- Wastewater (1)
- Water analysis (1)
- Water polluntants (1)
- Water structure (1)
- Water treatment (1)
- Water vapour permeation (1)
- Water-bearing glasses (1)
- Wave propagation (1)
- Weathering (1)
- Well-ordered macrocycle multilayers (1)
- Wheelset (1)
- Wide field (1)
- Writing inks (1)
- X-ray (1)
- X-ray Computed Tomography (1)
- X-ray computed tomography (1)
- X-ray diffraction (1)
- X-ray emission yield (1)
- X-ray fluorescence analysis (1)
- X-ray fluorescence spectroscopy (1)
- X-ray imaging (1)
- X-ray photoelectron spectroscopy (1)
- X-ray radiography (1)
- X-ray spectra (1)
- X-ray spectromicroscopy (1)
- X-ray spectrum (1)
- X-ray tomography (1)
- X-ray yields (1)
- XAFS (1)
- XANES X-ray absorption near edge structure spectroscopy (1)
- XAS (1)
- XRS (1)
- Young’s modulus (1)
- ZIF (1)
- Zearalenon (1)
- Zeolite (1)
- Zerstörungsfreie Prüfung (1)
- Zinc phosphate (1)
- Zinc phthalocyanine (1)
- Zinnoberrot (1)
- absolute measurements (1)
- absorption spectroscopy (1)
- activation energy (1)
- aerodynamics (1)
- affinity chromatography (1)
- aluminum (1)
- analytical approach (1)
- antibodies (1)
- antibody (1)
- atomic force microscopy (1)
- atomic imaging (1)
- atomic weight (1)
- bioanalysis (1)
- bioimaging (1)
- bioisosteric replacement (1)
- ceramics (1)
- cocrystal (1)
- coincidence (1)
- composite (1)
- conductivity (1)
- control chart (1)
- core-shell particles (1)
- cross-reactivity (1)
- cusum (1)
- cyclization (1)
- damage tolerance (1)
- decision-level (1)
- digestion (1)
- dimensional metrology (1)
- dispersity (1)
- dyes (1)
- elastomeric polymer optical fiber POF (1)
- electron backscattering (1)
- electron diffraction (1)
- excitation power density (1)
- explosives (1)
- flash thermography (1)
- fluorescence spectroscopy (1)
- functional PVD coatings (1)
- general fluid mechanics (1)
- geophysics non-destructive testing (1)
- glass fibre paper (1)
- granulation (1)
- graphene (1)
- hapten (1)
- high voltage cable accessories (1)
- holography (1)
- immunoaffinity (1)
- inspection (1)
- ion source (1)
- irreproducibility (1)
- isotope reference material (1)
- k-values (1)
- key comparison (1)
- laser induced plasma (1)
- laser induziertes Plasma (1)
- laser-induced plasma (1)
- laser-spark (1)
- ligand binding assay (1)
- ligands (1)
- liquids material characterization (1)
- mXRF Micro-X-ray fluorescence spectroscopy (1)
- magnesium (1)
- mass spectra (1)
- mechanochemistry (1)
- mercury intrusion capillary pressure (1)
- mesoporous material (1)
- metal phosphonates (1)
- microstructure (1)
- microwave (1)
- milling (1)
- mof (1)
- moisture (1)
- molecular switch (1)
- monitoring (1)
- monoclonal antibody (1)
- multi-sensory (1)
- nanoLC-ESI-MS/MS (1)
- nanocrystals (1)
- nanomaterial (1)
- nerve agent (1)
- non-specific binding (1)
- nuclear magnetic (1)
- numerical uncertainty determination (1)
- numerische Messunsicherheitsbestimmung (1)
- optical excitation (1)
- pH sensing (1)
- paper retraction (1)
- partial discharge (1)
- particle injection (1)
- peer reviewimmunochemistry (1)
- photoemission (1)
- photoluminescence quantum yield (1)
- photovoltaics (1)
- plasma dispersion layers (1)
- plasmonics (1)
- polycondensation (1)
- polyesters (1)
- polyionic liquids (1)
- pore radius (1)
- pore size control (1)
- pore templating (1)
- pores (1)
- porphyrin (1)
- presentation (1)
- probability (1)
- progressive hepatolenticular degeneration (1)
- qNMR (1)
- railway axles (1)
- relaxation time (1)
- replication (1)
- reproducibility crisis (1)
- resonance (1)
- reversible addition fragmentation chain transfer (RAFT) polymerization (1)
- robustness (1)
- sample preparation (1)
- scanning electron microscopy (1)
- screed (1)
- security (1)
- selectivity (1)
- sensing (1)
- sensor (1)
- shell morphology (1)
- shell thicknss and chemistry (1)
- signal-level (1)
- silicone rubber (1)
- simulation (1)
- single cell analysis (1)
- single molecule (1)
- single molecule spectroscopy (1)
- slurry (1)
- small-angle X-ray scattering (1)
- solar cell (1)
- spectral induced polarization (1)
- spray (1)
- spray drying (1)
- stabilizer (1)
- surface enhanced Raman scattering (1)
- surface group quantification (1)
- surface modification (1)
- switching dynamics (1)
- temperature (1)
- terrorism (1)
- thermoresponsive (1)
- ultrasonic excitation (1)
- ultrasonic tests (1)
- vortex shedding (1)
- wave propagation (1)
- zinc oxide (1)
- µXRF (1)
- Éléments traces (1)
- ß-amino-cyclodextrin (1)
- β-amyloid (1–42) (1)
- β-cristobalite structure type (1)
- μ-CT imaging (1)
- μ-CT imaging, (1)
Eingeladener Vortrag
- nein (193)
Coulometric sensors are applied for trace humidity measurements in various technical gases. The use of this sensor type is demanded in some standards by the European Pharmacopoeia for medical gases. Coulometric sensors allow the measurement of water vapour in gases such as e.g. air, Cl2, H2, N2, N2O, CH4 between the concentration ranging from 0.1 to 2,500 µmol∙mol-1 which corresponds to frost point temperature -90 °C to -10 °C, respectively.
The sensing principle is based on Faraday’s law of electrolysis whereby water is decomposed to hydrogen and oxygen. The sensor signal is the measured electrical current which is proportional to the mass of water that is absorbed on the hygroscopic phosphorous pentoxide layer. The signal is dependent on the gas flow at a given voltage, gas pressure and temperature.
The sensors need to be calibrated to measure the accurate signal for humidity in air. However, the signal is dependent on the type of gas matrix. This dependency has not been quantified so far. Therefore, the impact of reactive gases such as hydrogen and nitrous oxide on the calibration curve was investigated. Furthermore, a possible rationale in relation to the interaction of water with the gas matrix and its impact on the electrode reactions is suggested.
The experimental setup consists of a gas supply, dryer, humidifier, test chamber and reference hygrometer. The test gas is generated by mixing the dry and the wet gas flow. First the carrier gas is dried by an activated carbon filter and then split into two flows. One flow is dried again with a molecular sieve. The other flow is humidified by passing it through a bubbler filled with pure water. After this, the rate of both flows is controlled by mass flow controllers and then mixed with the test gas. A calibrated precision chilled mirror dew-point hygrometer is used as a reference instrument.
The coulometric sensors were exposed to different humidified gases and the sensor signal was recorded till a constant value was obtained. Calibration curves were calculated for the frost point temperature in the range of about -70 °C to -10 °C according to the equation, tf = A + B∙ln(I), (I is the electrolysis current and A, B are constants) followed with a linear regression fit.
Comparison of the results of air and nitrogen showed no significant differences. In contrast, there are remarkable differences for humidified hydrogen and nitrous oxide, respectively.
The difference might be due to increased recombination of hydrogen with the produced oxygen to form new water molecules in humidified hydrogen.
In conclusion, coulometric trace humidity sensor is a robust hygrometer for various technical applications. However it needs to be calibrated for the specific gas matrix.
Currently established and projected regulatory frameworks require the classification of materials (whether nano or non-nano) as specified by respective definitions, most of which are based on the size of the constituent particles. This brings up the question if currently available techniques for particle size determination are capable of reliably classifying materials that potentially fall under these definitions.
In this study, a wide variety of characterisation techniques, including counting, fractionating, and spectroscopic techniques, has been applied to the same set of materials under harmonised conditions.
The selected materials comprised well-defined Quality control materials (spherical, monodisperse) as well as industrial materials of complex shapes and considerable polydispersity. As a result, each technique could be evaluated with respect to the determination of the number-weighted median size. Recommendations on the most appropriate and efficient use of techniques for different types of material are given.
Analytical routines for a comprehensive in-depth morphological, structural, and chemical characterization of functionalized TiO2 films by using different state-of-the-art analytical techniques are presented and discussed with the main objective to identify potential reference TiO2 coating parameters able to be certified at a later stage. TiO2 films fabricated by two different synthetic procedures as representative for two main large-scale applications were selected: (i) pulsed d.c. magnetron sputtering for photocatalytic applications and (ii) screen printing from preformed anatase nanoparticles. The screen-printed films were further loaded with a sensitizing dye for application as a dye-sensitized solar cell. Film properties such as microstructure and crystallographic texture of pulsed d.c. magnetron sputtering synthesized films were systematically studied by means of scanning nanobeam electron diffraction in a transmission electron microscope and the surface and inner morphology by scanning electron microscopy. The dye distribution over the depth of screen-printed TiO2 layers was analyzed before and after dye-loading by means of energy dispersive X-ray spectroscopy at scanning electronmicroscope, Auger electron spectroscopy and time-of-flight secondary ion mass spectrometry. The long-term goal of the present study is the improvement of quality of the TiO2 film parameters as measured by using different types of reference TiO2 coatings having specific parameters certified.
In situ investigations using PXRD coupled with Raman spectroscopy permit the evaluation of the formation pathways of milling reactions. The liquid-assisted grinding cocrystallisation of theophylline with benzamide leading to polymorphic compounds was investigated. The dipole moment of the solvent used in the synthesis determines the structure of the polymorphic product. A detailed investigation allows determining the kinetically and thermodynamically favored product. In situ observations of the formation pathway during the grinding process of both polymorphs show that the thermodynamically favored cocrystal is formed in a two-step mechanism with the kinetic cocrystal as intermediate. The evaluation of the mechanochemical formation pathways reveals the importance of in situ investigations for an in depth understanding of mechanochemical synthesis mechanisms. Our study demonstrates that the choice of the solvent in the LAG synthesis is decisive for the controlled formation of a desired polymorphic final product.
A portable device for calibration of trace humidity sensors and an adopted calibration procedure have been developed. The calibration device is based on humidity generation by permeating water through polymeric membrane tubes. Water vapour transmission rates for various polymers were experimentally determined in order to select the most suitable polymeric material. The developed trace humidity generator consists of a gas-flow polymeric hose immersed in a water reservoir thermostated by a sensorcontrolled heater. Mole fractions of water vapour between 1 µmol/ molˉ¹ and 350 µmol/molˉ¹ (equivalent to frost-point temperatures from -76 °C to -31 °C) were generated by varying either the operating temperature or gas flow. The operating temperature can be varied from 20 °C to 60 °C and kept stable within 0.1 K. Uncertainty analysis indicated that the trace humidity generator produces gas flows of constant humidity amounts with a relative expanded uncertainty less than 3.4% (k = 2) of the generated value.
Supernatants from a fermentation process of Pichia pastoris were investigated by Raman spectroscopy. Using partial least squares regression, the principal substrates glycerol and methanol could be predicted, however not the expressed protein. To gain further insight, a priori prepared calibration samples were studied by vibrational-, UV/Vis-, and fluorescence spectroscopy. For the quantification of glycerol and methanol, Raman spectroscopy was identified as the most sensitive technique, and superior to near-infrared spectroscopy, but not for protein contents below 1 g L–1. Both UV/Vis absorption and fluorescence spectroscopy are well suited for the quantification of protein, however, best results were obtained with UV/Vis absorption.
Most ambient sample introduction and ionization techniques for native mass spectrometry are highly selective for polar agents. To achieve a more general sensitivity for a wider range of target analytes, a novel laser ablation dielectric barrier discharge (LA DBD) ionization scheme was developed. The Approach employs a two-step mechanism with subsequent sample desorption and post-ionization. Effective Ablation was achieved by the second harmonic output (λ = 532 nm) of a diode pumped Nd:YVO₄ laser operating at a high-repetition rate of several kHz and pulse energies below 100 μJ. The ejected analytecontaining aerosol was consecutively vaporized and ionized in the afterglow of a DBD plasma jet.
Depending on their proton affinity the superexcited Helium species in this afterglow produced analyte ions as protonated and ammoniated species, as well as radical cations. The optimization procedure could corroborate underlying conceptual consideration on the ablation, desorption and ionization mechanisms.
A successful detection of a variety of target molecules could be shown from the pharmaceutical ibuprofen, urea, the amino acids L-arginine, L-lysine, the polymer polyethylene glycol, the organometallic compound ferrocene and the technical mixture wild mint oil. For a reliable evaluation of the introduced detection procedure spectra from the naturally abundant alkaloid capsaicin in dried capsicum fruits were recorded.
X-ray powder diffraction (XRD) patterns of the high-temperature (HT) cristobalite form of SiO2 and its isoelectronic AlPO4 analogue are essentially influenced by the dynamic disorder of these crystal structures. The nature of this disorder and of the phase transition between the α- and β-form has been the subject of intensive research during the last four decades [1]. By 1989 it became possible to stabilize the HT-form of cristobalite SiO2 at room temperature in laboratory and engineering ceramic industries by applying solid solution forming techniques [2]. However, for the HT-form of cristobalite AlPO4 nothing similar has been known until 2014 when it was discovered that nanocrystalline and stacking-disordered β-cristobalite AlPO4 is the major component of the fly ash of a large incineration facility operated by the waste water treatment authorities of Frankfurt/M. [3]. Previous comprehensive investigations of this fly ash failed to interpret its complex XRD pattern – presumably mainly due to the lack of a matching experimental digital pattern in the Powder Diffraction Database. The present paper reports on a synthesis route that facilitates the crystallization of nanocrystalline and stacking-disordered β-cristobalite AlPO4 that is free of crystalline impurity phases and long-term stable at ambient. Its room temperature XRD pattern is presented with parameters traced back to certified reference materials.
[1] Yuan F. and Huang L., Phys. Rev, B, 2012, 85, 134114. [2] Perrotta J.A., Grubbs D.K., Martin E.S., Dando N.R., McKinstry H.A. and Huang C.-Y., J. Am. Ceram. Soc., 1989, 72, 441. [3] Peplinski B., Adam C., Adamczyk B., Müller R., Michaelis M., Krahl Th. and Emmerling F., Powder Diffraction Journal, 2015, 30, 2, Supp. 1, S31.
Paper-based SERS test strips
(2016)
For the non-destructive chemical analysis of organic compounds, several different methods such as NMR, UV-vis absorption, IR, Raman, or fluorescence spectroscopy are available. However, all available methods have some restrictions such as the necessity of a large sample amount, interferences in the presence of water, or overlapping signals from the analytes or matrix. Surface enhanced Raman scattering (SERS) allows to observe analytes directly without labelling in low concentrations in aqueous solutions and to identify them by their spectral fingerprint. Therefore, in this work we use SERS as a detection method for different analytes in low concentrations in combination with paper-based test strips as SERS substrates and for sample preparation.
We present a spray method for the preparation of SERS test stripes.[1] With this spray method, nanoparticle solution was deposited on cellulose and glass fibre paper as SERS substrate. The prepared paper-based test strips were tested with classical SERS reporter molecules, e.g. rhodamine 6G, 4-aminothiophenol, and adenine. For the quantification of analytes, highly reproducible signal intensities are necessary, which can be realized with the test strips in acceptable quality. Moreover, employing intensity vs concentration calibration for the analytes, data analysis revealed a behaviour that was best described by a Langmuir isotherm, stressing the strong distance dependence of the SERS effect.
For an easier identification of analytes in a mixture of compounds, the paper-based test strips were functionalised with hydrophobic barriers by wax printing. With these microfluidic paper-based analytical devices (µPAD) the sample mixture can be separated by the chromatographic effects of the paper and the different analytes can be separately detected and identified by SERS.
[1] A. Bolz, U. Panne, K. Rurack, M. Buurman, Glass fibre paper-based test strips for sensitive SERS sensing, Anal. Methods, 2016, 8, 1313-1318.
A comprehensive characterization of plasma modified polymer surfaces or plasma-polymerized thin films needs access to parameters as
- concentration of saturated/unsaturated carbon species (e.g. aromaticity) or other double bonds as C=N or C=O,
- branching, and
- losses of crystallinty or other degrees of structural order.
Furthermore the complex ageing phenomena of plasma modified polymers/plasma-polymers and the measurement of an in-depth distribution of chemical species are challenges for the analyst. The talk will display selected examples where such challenges have been met by using advanced methods of surface chemical analyses as Photoelectron Spectroscopy with variable excitation energy (“SyncXPS”), X-ray Absorption Spectroscopy (NEXAFS) at C, N and O K-edges and Time-of-Flight Secondary Mass Spectroscopy (ToF-SIMS) combined with Principal Component analysis (PCA).
In Near Edge X-Ray Absorption Fine Structure (NEXAFS) spectroscopy X-Ray photons are used to excite tightly bound core electrons to low-lying unoccupied orbitals of the system. This technique offers insight into the electronic structure of the system as well as useful structural information. In this work, we apply NEXAFS to two kinds of imidazolium based ionic liquids ([CnC₁im]⁺[NTf₂]⁻ and [C₄C₁im]⁺[I]⁻). A combination of measurements and quantum chemical calculations of C K and N K NEXAFS resonances is presented. The simulations, based on the transition potential density functional theory method (TP-DFT), reproduce all characteristic features observed by the experiment. Furthermore, a detailed assignment of resonance features to excitation centers (carbon or nitrogen atoms) leads to a consistent interpretation of the spectra.
In this study, a new reliable, economic, and environmentally-friendly one-step synthesis is established to obtain carbon nanodots (CNDs) with well-defined and reproducible photoluminescence (PL) properties via the microwave-assisted hydrothermal treatment of starch and Tris-acetate-EDTA (TAE) buffer as carbon sources. Three kinds of CNDs are prepared using different sets of above mentioned starting materials. The as-synthesized CNDs: C-CND (starch only), N-CND 1 (starch in TAE) and N-CND 2 (TAE only) exhibit highly homogenous PL and are ready to use without need for further purification.
The CNDs are stable over a long period of time (>1 year) either in solution or as freeze-dried powder. Depending on starting material, CNDs with PL quantum yield (PLQY) ranging from less than 1% up to 28% are obtained. The influence of the precursor concentration, reaction time and type of additives on the optical properties (UV-Vis absorption, PL emission spectrum and PLQY) is carefully investigated, providing insight into the chemical processes that occur during CND formation. Remarkably, upon freeze-drying the initially brown CND-solution turns into a non-fluorescent white/slightly Brown powder which recovers PL in aqueous solution and can potentially be applied as fluorescent marker in bio-imaging, as a reduction agent or as a photocatalyst.
Novel air-coupled ultrasonic transducer combining the thermoacoustic with the piezoelectric effect
(2016)
In recent years, there has been an increasing industrial demand for one-sided inspection of various structures by means of air-coupled ultrasonic technique. Lightweight structures based on carbon-fibre-reinforced polymers may have very complex shapes, making air-coupled transmission difficult or even impossible. The inspection of concrete structures is another example where one-sided inspection is required.
To address these challenges a new type of transducer for air-coupled pulse-echo inspection was developed, which unites two principles: thermoacoustic emission and piezoelectric reception. The thermoacoustic emitter is a titanium electrode with a thickness of several tens of nanometer. This electrode was deposited onto charged cellular polypropylene, which serves as a piezoelectric receiver. The thermoacoustic transmission is based on a transformation of the thermal energy of an electrically heated electrode into the acoustic energy of an ultrasonic wave. Thermoacoustic emitters provide resonance-free behaviour and thus extremely broadband pulses. Charged cellular polypropylene is piezoelectric due to the polarization of its cells and it is well matched to air, with a Young modulus in the order of magnitude of MPa. In this contribution we present some pulse-echo measurements with the first prototypes of the combined thermoacoustic-piezoelectric transducer.
Novel air-coupled ultrasonic transducer combining the thermoacoustic with the piezoelectric effect
(2016)
In recent years, there has been an increasing industrial demand for one-sided inspection of various structures by means of air-coupled ultrasonic technique. Lightweight structures based on carbon-fibre-reinforced polymers may have very complex shapes, making air-coupled transmission difficult or even impossible. The inspection of concrete structures is another example where one-sided inspection is required.
To address these challenges a new type of transducer for air-coupled pulse-echo inspection was developed, which unites two principles: thermoacoustic emission and piezoelectric reception. The thermoacoustic emitter is a titanium electrode with a thickness of several tens of nanometer. This electrode was deposited onto charged cellular polypropylene, which serves as a piezoelectric receiver. The thermoacoustic transmission is based on a transformation of the thermal energy of an electrically heated electrode into the acoustic energy of an ultrasonic wave. Thermoacoustic emitters provide resonance-free behaviour and thus extremely broadband pulses. Charged cellular polypropylene is piezoelectric due to the polarization of its cells and it is well matched to air, with a Young modulus in the order of magnitude of MPa. In this contribution we present some pulse-echo measurements with the first prototypes of the combined thermoacoustic-piezoelectric transducer.
Immunoassays are analytical methods used to track both clinical and environmental parameters. Antibodies or other proteins with similar recognizing activity, are employed, often immobilized onto a modified surface. Addressable microarrays are based on single-stranded DNA oligonucleotides which are normally used to detect aptamers or relevant gene sequences. The use of antibody-oligonucleotide conjugates allows non-directed antibody immobilization from an immunoassay to be converted into DNA hybridization events on the array. Consequently, the diagnostics platform is multiplexed and addressable. Figure 1 is a model representation of the whole biosensor construct. In brief, a surface is coated with streptavidin, and decorated with biotin-modified oligonucleotides of a controlled size and known sequence. These oligonucleotides on the surface also contain a furan motif, which upon irradiation and in the presence of a photosensitizer, is oxidized via single oxygen to a reactive intermediate which crosslinks the immediate opposing base when hybridized with its complementary strand [1].
Antibody-oligonucleotides conjugates still display several concerns due to their heterogeneicity, difficulty of characterization and high price [2]. The being the case, we aim at developing stable, robust, reproducible and well characterized quimeras for the application on te above described immunoarray. Mild chemical conditions are crucial for the antibody stability, therefore bivalent crosslinkers have been employed [2]. Even though the use of these bilinkers is standard for other substrate conjugation (i.e., enzymes, drug payloads, etc.), there is no literature available on the conjugation of small oligonucleotides (< 30 mer) to antibodies using this method. Several protein-nucleic acid conjugates have been therefore developed, and successfully characterized using MALDI-ToF and gel electrophoresis techniques.
A round robin test on flash thermography was organized within the scope of a standardization research project. This test gives information on reliability, comparability and efficiency of different testing situations. Data recorded on metal and CFRP test specimens with flat bottom holes (FBH) were analysed by evaluating the detectability and by calculating the signal-to-noise ratio (SNR) of the defect signatures as a function of defect parameters. For the investigation of the influence of material properties on the spatial resolution as well as on penetration depth, test specimens made of steel and copper with crossed notches and a notch ramp were constructed and investigated. Here, the minimum resolvable notch distance and the maximum detectable depth of the ramp were analysed.
A round robin test on flash thermography was organized within the scope of a standardization research project. This test gives information on reliability, comparability and efficiency of different testing situations. Data recorded on metal and CFRP test specimens with flat bottom holes (FBH) were analysed by evaluating the detectability and by calculating the signal-to-noise ratio (SNR) of the defect signatures as a function of defect parameters. For the investigation of the influence of material properties on the spatial resolution as well as on penetration depth, test specimens made of steel and copper with crossed notches and a notch ramp were constructed and investigated. Here, the minimum resolvable notch distance and the maximum detectable depth of the ramp were analysed.
Sulfamethoxazol (SMX),a sulfonamide, is a widely used bacteriostatic antibiotic and therefore a promising marker for the entry of anthropogenic Pollution in the environment. SMX is frequently found in wastewater and surface water. This study presents the production of high affinity and selective polyclonal antibodies for SMX and the development and Evaluation of a direct competitive enzyme-linked immunosorbent assay(ELISA)for the quantification of SMX in environmental watersamples. The crystal structures of the cross-reacting compounds sulfamethizole, N4-acetyl-SMX andsuccinimidyl-SMX were determined by x-ray diffraction aiming to explain their high cross-reactivity. These crystal structures are described for the first time. The quantification range of the ELISA is 0.82–63 µg/L. To verify our results, the SMX concentration in 20 environmental samples,including wastewater and surfacewater,was determined by ELISA and tandem mass spectrometry(MS/MS).A good Agreement of the measured SMX concentrations was found with average recoveries of 97–113%for the results of ELISA compared to LC-MS/MS.
We have compared the performance of the typical Darr and CM moisture testing techniques, which are destructive with several non-destructive testing techniques on two types of floor screeds. In case of cement based screeds these destructive tests failed to deliver reliable results. Moreover, our measurements indicate significantly different drying and moisture transport behavior for the investigated cement based and calcium-sulphate based screeds. Whereas we have strong with depth decreasing moisture gradients in the CT material, we observe in the penetrated volumes of our ndt methods basically no clear moisture gradient in the CA samples. The findings with ndt methods could be supported by moisture gradient studies with nuclear magnetic resonance measurements.
A robust and sensitive method for the detection of the explosive trinitrotoluene (TNT) was developed. The detection limit was determined to be around 0.5 µg/L. The fast signal response of less than 1 minute shows that this approach is suitable for security and other time-critcal applications. In addition, the very low cross-reactivity highly reduces the number of false-positives in relation to competing techniques, including sniffer dogs. Due to the multianalyte ability of the SAW system, several explosives might be detected in parallel.
Microstrain distributions were acquired in functional thin films by high-resolution X-ray microdiffraction measurements, using polycrystalline CuInSe2 thin films as a model system. This technique not only provides spatial resolutions at the submicrometre scale but also allows for analysis of thin films buried within a complete solar-cell stack. The microstrain values within individual CuInSe2 grains were determined to be of the order of 10^-4. These values confirmed corresponding microstrain distribution maps obtained on the same CuInSe2 layer by electron backscatter diffraction and Raman microspectroscopy.
Raman microspectroscopic imaging was just recently introduced into the analysis of cement stone. Here, we demonstrate this approach on 19th-century Roman and Portland cement mortars and extend it to gypsum-based samples originating from a medieval stucco sculpture (high-burnt gypsum) and a stucco ornament prefabricated at the beginning of the 20th century (plaster of Paris). Furthermore, the distributions of dolomite and Calcite were mapped in an accessory mineral grain with approx. 500 nm lateral Resolution demonstrating the ability for studying alteration processes such as dedolomitisation. As we would like to make this approach accessible to other researchers, we discuss its present status, advantages, limitations and pitfalls.
Injection of poly(methyl methacrylate) cements, one standard Treatment for osteoporotic vertebral body fractures, may lead to critical loads and subsequent fractures in adjacent vertebral bodies. Biodegradable calcium phosphate cements (CPC) with bioinductive growth factors may be an alternative, since they have a Young’s modulus comparable to that of cancellous bone. Non-destructive tests with μCT and quantitative Image evaluation are used to assess new bone growth and material resorption following intravertebral injection of CPC. Immediate deep-freezing of excised bone prevents shrinkage or tissue disintegration and the samples have to be kept frozen for all following steps, including transport, μCT measurements, and subsequent biomechanical tests. Here we will report on a set-up to preserve the frozen state of the material and allow stable long-term serial μCT measurements. In addition, the image processing technique for the evaluation of bone growth and selected results on subsequently carried out compressive strength tests will be presented.
A model is presented that employs a unified approach for
simulating the photon energy spectra for transmission and direct
beam targets composed of arbitrary homogeneous materials. In order
to achieve this, a detailed model of electron transport within the
target is employed. The validity of the developed model is shown
through comparisons with Monte Carlo simulations as well as
measurements for a number of different configurations.
Modelling becomes more and more important in modern NDE. It is increasingly used to optimize techniques for complex applications, to support the preparation of written procedures, and for education purposes. To describe the complete chain of RT, the model includes simulating all necessary properties of X- or Gamma-ray sources, the interaction of photons with material with special attention to scattered radiation, the detection process, and the complete geometrical RT setup handling arbitrary parts or constructions. Depending on the given inspection problem and the influencing factors that should be addressed by the simulation, an appropriate physical model has to be chosen to describe the underlying interaction mechanisms. The simulator aRTist combines analytical and Monte Carlo methods to efficiently model the radiation transport such that transmission as well as scatter techniques can be modelled. In this contribution we focus on Monte Carlo simulation of scatter contribution within aRTist. Examples for RT/tomographic applications and back-scatter techniques are presented to demonstrate the usability of the presented simulation tool for a broad range of radiological applications.
Aiming at the development of validated protocols
for protein conjugation of nanomaterials and the determination
of protein labeling densities, we systematically assessed
the conjugation of the model protein streptavidin (SAv) to
100-, 500-, and 1000-nm-sized polystyrene and silica nanoparticles
and dye-encoded polymer particles with two
established conjugation chemistries, based upon achievable
coupling efficiencies and labeling densities. Bioconjugation
reactions compared included EDC/sulfo NHS ester chemistry
for direct binding of the SAv to carboxyl groups at the particle
surface and maleimide-thiol chemistry in conjunction with
heterobifunctional PEG linkers and aminated nanoparticles
(NPs). Quantification of the total and functional amounts of
SAv on these nanomaterials and unreacted SAv in solution
was performed with the BCA assay and the biotin–FITC
(BF) titration, relying on different signal generation principles,
which are thus prone to different interferences. Our results
revealed a clear influence of the conjugation chemistry on
the amount of NP crosslinking, yet under optimized reaction
conditions, EDC/sulfo NHS ester chemistry and the attachment
via heterobifunctional PEG linkers led to comparably
efficient SAv coupling and good labeling densities. Particle
size can obviously affect protein labeling densities and
particularly protein functionality, especially for larger
particles. For unstained nanoparticles, direct bioconjugation
seems to be the most efficient strategy, whereas for dyeencoded
nanoparticles, PEG linkers are to be favored for the
prevention of dye–protein interactions which can affect
protein functionality specifically in the case of direct SAv
binding. Moreover, an influence of particle size on achievable
protein labeling densities and protein functionality could be
demonstrated.
Modeling of the photon-electron cascade process in multicomponent objects of complex geometrical structure by use of hybrid supercomputers is considered. An approach to computing the cascade processes is developed. The approach has three key properties allowing the effective use of heterogeneous structure of computers for solving the tasks of radiation transport in complex multi-scale geometries. Firstly, two different discreet geometrical description of an object being under radiation is used: triangulated model for photon transport and voxel model for elec-tron transport. Secondly, small parameter of the problem is explicitly taking into ac-count for modeling surface effects (for instance, electron emission). Thirdly, the ef-fective calculation decomposition between CPU and GPU is developed for signifi-cant increasing the speed of calculations of processes in question. Modeling of ex-periment on researching the bremsstrahlung generated by electron beam in Ta target is carried out. Comparison of computing and experimental results shows satisfactory consent.
In this contribution, we discuss the influence of scattered radiation on materials’ effective attenuation coefficients at higher X-ray energies. The selected X-ray spectra for the dual-energy experiments correspond to 3 MV and 7.5 MV acceleration potential of the used betatron. Experiments were performed on a test phantom containing step wedges of different low- and high-Z materials. We evaluated the ratio between low- and high-energy X-ray attenuation coefficients quantitatively based on simulated poly-energetic high-energy X-ray source spectra and the detector sensitivity using the “analytical Radiographic Testing inspection simulation tool” (aRTist) developed at BAM. Furthermore, the influence of scattered radiation is evaluated using an efficient Monte-Carlo simulation. The simulation results are compared quantitatively with experimental investigations. Finally, important applications of the proposed technique in the context of aviation security are discussed.
X-ray backscatter imaging is a well established NDT technique to inspect complex objects using only a single-sided access. In difference to conventional transmission X-ray radiography, the X-ray backscatter imaging utilizes the scattered radiation caused by the Compton scattering effect. In order to achieve high backscatter intensities from a test object, it is necessary to optimize the backscatter system parameters namely the angle between source and slit camera, the slit collimator system, the shielding between source and scatter camera, and the type of detector. In addition, the scatter phenomena in to the investigated object need to be understood.
In this contribution, we present a Monte Carlo model McRay which considers all relevant single and multiple interactions of photons and electrons. This model can be used to simulate back scatter techniques. It allows not only calculating the scatter image for a given experimental setup but also registering the spectrum of the detected scattered photons. Both aspects are important to understand the imaging process, to interpret the results, and to optimize the backscatter camera investigated here. Additionally experimental results will be presented and compared with simulations.
Electromagnetic waves with frequencies between 0.1 and 10 THz are described as THz-radiation (T-ray). The ability to penetrate dielectric materials makes T-rays attractive to reveal discontinuities in polymer and ceramic materials. THz-Time Domain Spectroscopy Systems (THz-TDS) are available on the market today which operates with THz-pulses transmitted and received by optically pumped semiconductor antennas. In THz-TDS the travelling time (ToF) and shape of the pulse is changed if it interacts with the dielectric material and its inherent disconti-nuities. A tomogram of the object under the test can be reconstructed from time of flight diffraction (ToFD) scans if a synthetic focusing aperture (SAFT) algorithm is applied. Otherwise, planar discontinuities like cracks in plastics or delaminated lay-ers in composites can be abstracted as layers located at any angle in relation to the outer sample surface direction. A tomogram from the scanned sample can then be reconstructed in case the interactions of electromagnetic pulses with the existing in-herent interfaces are detectable and a model is assumed which describes the device under the test as multilayer structure composed of thin layers with different dielec-tric properties.
A short description of both the SAFT – and Optical Layer algorithm for the recon-struction of the inherent structure is initially given. Measurements on representative samples with a variety of artificially produced small and large scale. Reconstructed tomograms are presented to discuss and evaluate the benefits and limits of the two different reconstruction approaches.
For non-destructive testing (NDT) appropriate reference blocks are required in order to verify and calibrate a testing procedure. At BAM a special electric discharge machining (EDM) system has been developed which is able to manufacture artificial defects having a width down to 30 μm.
Especially in the case of austenitic materials conventional EDM leads to a transformation of austenite to martensite. The martensite transformation causes a higher sensitivity of electromagnetic NDT methods (e. g. eddy current testing) at the artificial defects compared to natural defects of same size. The EDM system developed at BAM uses very low energy to avoid this material transformation. A side effect of the low-energy EDM is a lower surface roughness compared to conventional EDM.
The artificial defects manufactured at BAM are measured optically and delivered with a certificate.
A comparison of artificial defects shows the influence of material transformation on NDT and how differently the quality of the artificial defects can be.
For non-destructive testing (NDT) appropriate reference blocks are required in order to verify and calibrate a testing procedure. At BAM a special electric discharge machining (EDM) system has been developed which is able to manufacture artificial defects having a width down to 30 μm.
Especially in the case of austenitic materials conventional EDM leads to a transformation of austenite to martensite. The martensite transformation causes a higher sensitivity of electromagnetic NDT methods (e. g. eddy current testing) at the artificial defects compared to natural defects of same size. The EDM system developed at BAM uses very low energy to avoid this material transformation. A side effect of the low-energy EDM is a lower surface roughness compared to conventional EDM. The artificial defects manufactured at BAM are measured optically and delivered with a certificate. A comparison of artificial defects shows the influence of material transformation on NDT and how differently the quality of the artificial defects can be.
One essential step on the way towards accurate quantitative simulation of radiographic testing is an accurate description of the utilized energy spectrum of X-ray photons. For use in general purpose simulation tools, the spectra of X-ray tubes have to be described by a model covering at least the intended range of applications. This range includes transmission tubes as well as direct beam tubes with varying angles of incidence and emission, for a number of typical target materials. In radiographic testing acceleration voltages frequently reach up to 450 kV for direct beam targets and up to 225 kV for transmission targets, with even higher voltages available or being developed. Currently used models are unable to cover the whole range of configurations.
Here a model is presented that employs a unified approach for simulating the photon energy spectra for transmission and direct beam targets composed of arbi-trary homogeneous materials. In order to achieve this, a detailed model of electron transport within the target is employed. The validity of the developed model is shown through comparisons with Monte Carlo simulations as well as measurements for a number of different configurations.
Modeling of the photon-electron cascade progress in multicomponent objects of complex geometrical structure by use of hybrid supercomputers is considered. An approach to computing the cascade processes is developed. The approach has three key properties allowing the effective use of heterogeneous structure of computers for solving the tasks of radiation transport in complex multi-scale geometries. Firstly, two different discreet geometrical description of an object being under radiation is used: triangulated model for photon transport and voxel model for electron transport. Secondly, small parameter of the problem is explicitly taking into account for modeling surface effects (for instance, electron emission). Thirdly, the effective calculation decomposition between CPU and GPU is developed for significant increasing the speed of calculations of processes in question. Modeling of experiment on researching the bremsstrahlung generated by electron beam in Ta target is carried out. Comparison of computing and experimental results shows satisfactory consent.
In this contribution, we discuss the influence of scattered radiation on materials’ effective attenuation coefficients at higher X-ray energies. The selected X-ray spectra for the dual-energy experiments correspond to 3 MV and 7.5 MV acceleration potential of the used betatron. Experiments were performed on a test phantom containing step wedges of different low- and high-Z materials. We evaluated the ratio between low- and high-energy X-ray attenuation coefficients quantitatively based on simulated poly-energetic high-energy X-ray source spectra and the detector sensitivity using the “analytical Radiographic Testing inspection simulation tool” (aRTist) developed at BAM. Furthermore, the influence of scattered radiation is evaluated using an efficient Monte-Carlo simulation. The simulation results are compared quantitatively with experimental investigations. Finally, important applications of the proposed technique in the context of aviation security are discussed.
X-ray backscatter imaging is a well established NDT technique to inspect complex objects using only a single-sided access. In difference to conventional transmission X-ray radiography, the X-ray backscatter imaging utilizes the scattered radiation caused by the Compton scattering effect. In order to achieve high backscatter intensities from a test object, it is necessary to optimize the backscatter system parameters namely the angle between source and slit camera, the slit collimator system, the shielding between source and scatter camera, and the type of detector. In addition, the scatter phenomena in to the investigated object need to be understood.
In this contribution, we present a Monte Carlo model McRay which considers all relevant single and multiple interactions of photons and electrons. This model can be used to simulate back scatter techniques. It allows not only calculating the scatter image for a given experimental setup but also registering the spectrum of the detected scattered photons. Both aspects are important to understand the imaging process, to interpret the results, and to optimize the backscatter camera investigated here. Additionally experimental results will be presented and compared with simulations.
Electromagnetic waves with frequencies between 0.1 and 10 THz are described as THz-radiation (T-ray). The ability to penetrate dielectric materials makes T-rays attractive to reveal discontinuities in polymer and ceramic materials. THz-Time Domain Spectroscopy Systems (THz-TDS) are available on the market today which operates with THz-pulses transmitted and received by optically pumped semiconductor antennas. In THz-TDS the travelling time (ToF) and shape of the pulse is changed if it interacts with the dielectric material and its inherent discontinuities.
A tomogram of the object under the test can be reconstructed from time of flight diffraction (ToFD) scans if a synthetic focusing aperture (SAFT) algorithm is applied. Otherwise, planar discontinuities like cracks in plastics or delaminated layers in composites can be abstracted as layers located at any angle in relation to the outer sample surface direction. A tomogram from the scanned sample can then be reconstructed in case the interactions of electromagnetic pulses with the existing inherent interfaces are detectable and a model is assumed which describes the device under the test as multilayer structure composed of thin layers with different dielectric properties.
A short description of both the SAFT – and Optical Layer algorithm for the reconstruction of the inherent structure is initially given. Measurements on representative samples with a variety of artificially produced small and large scale. Reconstructed tomograms are presented to discuss and evaluate the benefits and limits of the two different reconstruction approaches.
Modelling becomes more and more important in modern NDE. It is increasingly used to optimize techniques for complex applications, to support the preparation of written procedures, and for education purposes. To describe the complete chain of RT, the model includes simulating all necessary properties of X- or Gamma-ray sources, the interaction of photons with material with special attention to scattered radiation, the detection process, and the complete geometrical RT setup handling arbitrary parts or constructions. Depending on the given inspection problem and the influencing factors that should be addressed by the simulation, an appropriate physical model has to be chosen to describe the underlying interaction mechanisms. The simulator aRTist combines analytical and Monte Carlo methods to efficiently model the radiation transport such that transmission as well as scatter techniques can be modelled. In this contribution we Focus on Monte Carlo Simulation of scatter contribution within aRTist. Examples for RT/tomographic applications and back-scatter techniques are presented to demonstrate the usability of the presented simulation tool for a broad range of radiological applications.
For the last 20 years active thermography has developed into a standard method in non-destructive material testing. It has become possible to detect defects such as cracks, voids, or even material inhomogeneities. Until now, it is still difficult to quantify subsurface or hidden defects in size due to the diffusive nature of heat flow within a solid. Facing this issue, lockin thermography and other photothermal techniques have been established. They are based on exciting a sample periodically (e.g. with a halogen lamp), causing a controlled periodical heat flow and thereby representing strongly damped thermal waves. These techniques make use of interference and reflection of thermal waves which allow enhancing depth resolution.
So far, only the temporal component of the light source was modified to achieve a defined vertical heat flow – In contrast, we propose a novel technique in which we are able to control both: time and space. This technique enables us to exploit the possibilities of coherent thermal wave shaping. We achieve that by combining a spatial light modulator (SLM) with a high power laser. This approach allows us to launch a set of individually controlled and fully coherent high energy thermal waves into the sample volume. That means, we intentionally use wave propagation throughout the sample’s material in both - vertical and lateral direction.
As one possible application, we use a thermal waves’ interference effect of two phase shifted wave patterns to detect the position of hidden defects. The wave patterns are positioned with a certain distance and a 180° phase shift to each other creating an amplitude depletion zone right in the middle of the two patterns. When a defect is brought unsymmetrically into the depletion zone, the lateral heat flow is disturbed. If the sample is now moved through the depletion zone, a defect can be easily characterized. Exciting periodically while controlling simultaneously phase and amplitude enables us to have a defined thermal wave propagation throughout the sample which means thermal waves can be controlled almost like acoustical or optical waves. This offers the opportunity to transfer known technologies from wave shaping techniques to thermography methods.
For the last 20 years active thermography has developed into a standard method in non-destructive material testing. It has become possible to detect defects such as cracks, voids, or even material inhomogeneities. Until now, it is still difficult to quantify subsurface or hidden defects in size due to the diffusive nature of heat flow within a solid. Facing this issue, lockin thermography and other photothermal techniques have been established. They are based on exciting a sample periodically (e.g. with a halogen lamp), causing a controlled periodical heat flow and thereby representing strongly damped thermal waves. These techniques make use of interference and reflection of thermal waves which allow enhancing depth resolution.
So far, only the temporal component of the light source was modified to achieve a defined vertical heat flow – In contrast, we propose a novel technique in which we are able to control both: time and space. This technique enables us to exploit the possibilities of coherent thermal wave shaping. We achieve that by combining a spatial light modulator (SLM) with a high power laser. This approach allows us to launch a set of individually controlled and fully coherent high energy thermal waves into the sample volume. That means, we intentionally use wave propagation throughout the sample’s material in both - vertical and lateral direction. As one possible application, we use a thermal waves’ interference effect of two phase shifted wave patterns to detect the position of hidden defects. The wave patterns are positioned with a certain distance and a 180° phase shift to each other creating an amplitude depletion zone right in the middle of the two patterns. When a defect is brought unsymmetrically into the depletion zone, the lateral heat flow is disturbed. If the sample is now moved through the depletion zone, a defect can be easily characterized. Exciting periodically while controlling simultaneously phase and amplitude enables us to have a defined thermal wave propagation throughout the sample which means thermal waves can be controlled almost like acoustical or optical waves. This offers the opportunity to transfer known technologies from wave shaping techniques to thermography methods.
Applications of fibre reinforced plastic (FRP) composites in modern industries are increasing due to their considerable advantages such as light weight and excellent mechanical properties. Accordingly, importance of operational safety of modern structures made of advanced composites by ensuring the material quality has led to increasing demands for development of non-destructive evaluation (NDE) systems. In the context of a European project entitled “Validated Inspection Techniques for Composites in Energy Applications” (VITCEA), the aim is to develop and validate traceable procedures for novel NDE techniques with contrasting damage detection capabilities in energy related applications such as wind and marine turbine blades, nacelles, oil and gas flexible risers. Accordingly, VITCEA focuses on optimization of ultrasonic tests (UTs) for quantitative defect detection and quality characterization of FRP structures. In this context, the present study describes the ultrasound field in heterogeneous composite materials. The theoretical predictions are compared with simulation results obtained from CIVA a software package dedicated to NDT simulations based on the asymptotic ray theory.
Recent developments in Förster resonance energy transfer (FRET) diagnostics using quantum dots
(2016)
The exceptional photophysical properties and the nanometric dimensions of colloidal semiconductor quantum dots (QD) have strongly attracted the bioanalytical community over the last approximately 20 y. In particular, the integration of QDs in the analysis of biological components and interactions, and the related diagnostics using Förster resonance energy transfer (FRET), have allowed researchers to significantly improve and diversify fluorescence-based biosensing. In this TRENDS article, we review some recent developments in QD-FRET biosensing that have implemented this technology in electronic consumer products, multiplexed analysis, and detection without light excitation for diagnostic applications. In selected examples of smartphone-based imaging, single- and multistep FRET, steady-state and time-resolved spectroscopy, and bio/chemiluminescence detection of QDs used as both FRET donors and acceptors, we highlight the advantages of QD-based FRET biosensing for multiplexed and sensitive diagnostics.
Excelling in brevity but lacking in applicability, the 2011 EU nanomaterial definition has become a source of anguish for scientists and industry alike. Repeated pleas and discussions with our own envoy have demonstrated the strength of their resolve: this definition is unlikely to change. Manufacturers of many materials (cosmetics, pigments, foodstuffs, etc.) will have to characterise and label all their products accordingly, a task still impossible for lack of a clear metrological approach towards this goal. Therefore, the onus has fallen on the scientists to come up with a practicable measurement technique allowing inexpensive classification covering large swathes of the material landscape. Small-angle X-ray Scattering (SAXS) probes the size range in question, and can - with due care - deliver a bulk-averaged volume-weighted size distribution. Like any other real-world measurement method, however, it is not (and can never be) a universal solution. This presentation will clarify the SAXS technique, provide several application examples for nanomaterial characterisation, and will detail the limitations and pitfalls that accompany its abilities. At the end of this presentation, you will have the information to judge whether the technique is amenable to your materials or not.
In recent years, elemental imaging of biological samples using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is gaining in importance. Latest improvements regarding spatial resolution (down to 1 µm) and washout time make LA-ICP-MS particularly interesting for single cell analysis.
Many current nanomaterials can serve as contrast agents in cellular or tissue imaging, drug delivery vehicles or therapeutics, whereas others can cause toxic effects. In order to evaluate nano-bio interactions, the number of nanoparticles (NPs) inside cells as well as their localisation within cellular substructures is of particular interest.
LA-ICP-MS was used to study the NP pathway from uptake, via intracellular processing up to cell division. Fibroblast cells were incubated with different metallic NPs under varying experimental conditions. For LA analysis the cells were fixed with formaldehyde and dried.
Our results show that LA-ICP-MS is able to localise NP aggregates within cellular substructures. The NPs accumulate in the perinuclear region in the course of intracellular processing, e.g. multivesicular fusion and endosomal maturation, but do not enter the nucleus [1, 2]. A strong dependence of NP uptake on concentration and incubation time was found. Additionally, the number of NPs internalized by individual cells was determined and variations within the cell population became visible.
A new laser ablation system providing a short washout time (50 ms) together with small spot sizes (< 4 µm) and high repetition rates allows high spatial resolution applications. First results of cell imaging will be shown.
The findings demonstrate the potential of LA-ICP-MS enabling insight into NP uptake and intracellular distribution dependent on experimental parameters.
Imuno-histochemical staining (IHC) of cancer biomarker on tissue sections is one of the most important analytical techniques for cancer diagnosis although standardization and quality management is tedious and differ significantly from clinic to clinic. Combining established IHC staining strategies with modern quantitative methods would increase it`s potential. We used element mass spectrometry (ICP-MS) and a new ink-jet printed internal standardization approach in combination with IHC staining. The printing strategy was utilized to improve elemental image resolution and reproducibility of paraffin embedded breast cancer tissue sections in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) after conventional IHC staining as a model system to investigate the new capabilities of this technique.
Thermoresponsive polymers have shown great potential in applications such as bioseparation, drug delivery and diagnostic. Only few thermoresponsive polymers that present an upper critical solution temperature (UCST) in a relevant temperature range, i.e. phase separate from solution upon cooling, have been reported so far. Moreover, the most studied UCST type polymers namely polybetaines are difficult to use under physiological conditions, which significantly restricts their potential applications. Therefore, UCST polymers with sharp and robust phase transition in physiological conditions (in the presence of salts, ions etc.) are highly needed in order to extend the range of applications of this class of polymers. Herein, a robust UCST-type copolymer of acrylamide (AAm) and acrylonitrile (AN) (poly(AAm-co-AN)) was prepared by reversible addition fragmentation chain transfer (RAFT) polymerization and its thermo-induced aggregation behavior in aqueous media was studied. At temperature below the UCST, the copolymer chains were aggregated together. The aggregate size was found to be larger with increasing AN contents and became smaller upon dilution of the copolymer solutions. While above the UCST, the copolymer chains were expanded and weekly associated in solution. The association between the copolymer chains formed smaller aggregates with increasing the AN contents or the dilution of the solutions. A model is proposed to explain such aggregation-association behavior of the Fig. 1.
Figure 1. Schematic illustration of the proposed thermos-induced aggregation behavior of the poly(AAm-co-AN) in aqueous solution.
Imuno-histochemical staining (IHC) of cancer biomarker on tissue sections is one of the most important analytical techniques for cancer diagnosis although standardization and quality management is tedious and differ significantly from clinic to clinic. Combining established IHC staining strategies with modern quantitative methods would increase it`s potential. We used element mass spectrometry (ICP-MS) and a new ink-jet printed internal standardization approach in combination with IHC staining. The printing strategy was utilized to improve elemental image resolution and reproducibility of paraffin embedded breast cancer tissue sections in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) after conventional IHC staining as a model system to investigate the new capabilities of this technique.
The laser-induced breakdown spectroscopy (LIBS) is a fast method to provide multi-elemental analysis of any sample. At the Federal Institute for Materials Research and Testing (BAM) the LIBS technique is applied on building materials to measure ingress profiles of harmful species like chloride and alkalis. The ingress depth and the quantitative amount is important for the evaluation of the potential for damage processes like the alkali-silica reaction or chloride-induced corrosion. Concrete as an example is a highly heterogeneous material with 1/7 cement (major component CaO) and 6/7 aggregates (SiO2) with different grain sizes. Due to a scanning procedure a two dimensional element distribution of a concrete surface can be measured. In order to have an automated Separation method to evaluate heterogeneous materials, different cluster algorithm have been tested. Best results have been achieved with the Expectation-Maximization-Algorithm (EM-Algorithm).
The motivation to examine the influence of friction on surfaces of energetic materials (EM) has diverse backgrounds. On the one hand the very old hot spot theory predicts, that the size of such hot spot could be in the range of a molecule. The initiation of an EM could start by mechanical excitation, i.e. friction, and continues driven by an exothermal chemical reaction. Following such phenomena on the molecular scale with an imaging method such as AFM should enable us to separate several steps of ignition, if there are any. The experiments showed that HMX mainly undergoes a plastic deformation without further consequences. TNP however showed self healing in the wear track after scratching and simultaneously the destruction of a crystal edge outside the wear track. Additionally nanoparticles appear, tribologists call this "third body formation", which are proven to have a different chemical composition as the original TNP. The self healing effect on the surface is verified with experiments on self diffusion of TNP molecules to and fro the free edges of the crystal. The conclusion is that the formation of a hot spot can be shown to consist of several subsequent steps, separated temporally and locally. The goal to excite the thermal decomposition of a whole TNP crystal (nanoexplosion) was yet not reached due to unfavourable conditions related to thermal conductivity and build-up of pressure.
qNMR provides the most universally applicable form of direct purity determination without need for reference materials of impurities or the calculation of response factors but only exhibiting suitable NMR properties. The development of CRMs addressing qNMR specific measurement issues will give analysts compounds ideally suited for the analytical method and also provide full characterisation of qNMR related parameters to enable more realistic uncertainty budgets. These materials will give users the tools to exploit qNMR more easily and enable them to speed up analytical method development and reduce the time and financial burden of multiple analytical testing.
The nature of the bound water in solids with hydrogen-bonded networks depends not only on temperature and pressure but also on the nature of the constituents. The collapse and reorientation of these network structures determines the stability of hydrated solids and transitions to other crystalline or amorphous phases. Here, we study the mechanochemically induced loss of bound water in Co₃(PO₄)₂·8H₂O and compare this process to the behavior under hydrostatic pressure.
The associated phase transition and its kinetics were monitored by X-ray powder diffraction with Synchrotron radiation and quantitative IR spectroscopy. High shearing forces are responsible for the degradation of the hydrogen-bonded network and the concomitant crystalline–amorphous transformation. UV/Vis spectroscopy, extended X-ray absorption spectroscopy (EXAFS), and X-ray absorption near-edge spectroscopy (XANES) provided information about the short-range order in the amorphous solid, and thermal analysis revealed its composition and showed that the moderate charge densities of the Co²⁺ and PO₄³⁻ ions, which make the hydration enthalpy comparable to the binding energy of the counteranions, and the Formation of hydrogen-bonded networks favor multistage crystallization processes associated with the release and uptake of coordinated water. The changes of the Co²⁺ coordination induce a color change from pink to blue; therefore, Co₃(PO₄)₂·8H₂O can be used as an overheat temperature indicator.
Self-assembling biomolecules provide attractive templates for the preparation of metallic nanostructures. However, the intuitive transfer of the “outer shape” of the assembled macromolecules to the final metallic particle depends on the intermolecular forces among the biomolecules which compete with interactions between template molecules and the metal during metallization. The shape of the bio-template may thus be more dynamic than generally assumed. Here, we have studied the metallization of phospholipid nanodiscs which are discoidal particles of ~10 nm diameter containing a lipid bilayer ~5 nm thick. Using negatively charged lipids, electrostatic adsorption of amine-coated Au nanoparticles was achieved and followed by electroless gold deposition. Whereas Au nanoparticle adsorption preserves the shape of the bio-template, metallization proceeds via invasion of Au into the hydrophobic core of the nanodisc. Thereby, the lipidic phase induces a lateral growth that increases the diameter but not the original thickness of the template. Infrared spectroscopy reveals lipid expansion and suggests the existence of internal gaps in the metallized nanodiscs, which is confirmed by surface-enhanced Raman scattering from the encapsulated lipids. Interference of metallic growth with non-covalent interactions can thus become itself a shape-determining factor in the metallization of particularly soft and structurally anisotropic biomaterials.
When modeling the propagation of elastic guided waves in plates or cylinders, Finite Element based numerical methods such as the Scaled Boundary Finite Element Method (SBFEM) or the Semi-Analytical Finite Element (SAFE) Method lead to an eigenvalue problem to be solved at each frequency. For the particular case of shear horizontal modes in a homogeneous plate or torsional modes in a homogeneous cylinder, the problem can be drastically simplified. The eigenvalues become simple functions of the frequency, while the eigenvectors are constant. The current contribution discusses how this behavior is represented in the numerical formulation and derives the expressions for the eigenvalues and eigenvectors as well as the dynamic stiffness matrix of infinite elastic waveguides.
We describe a fast and effective synthesis for molecular metal phosphonates. Isomorphic compounds [M(II)(HO₃PPh)₂(H₂O₃PPh)₂(H₂O)₂] (M = Mn (1), Co (2), Ni (3); Ph = C₆H₅) were obtained by grinding. The complexes are mononuclear compounds containing neutral and monodeprotonated phenylphosphonic acid and water as ligands. The crystal structures were determined using powder X-ray diffraction (PXRD) data and validated by extended X-ray absorption fine structure (EXAFS) data. Combined synchrotron XRD measurements and Raman spectroscopy were conducted for investigating the reactions in situ. Based on these data, the intermediates were characterized and the formation mechanism was derived.
Fluorescence imaging microscopy is an essential tool in biomedical research. Meanwhile, various fluorescent probes are available for the staining of cells, cell membranes, and organelles. Though, to monitor intracellular processes and dysfunctions, probes that respond to ubiquitous chemical parameters determining the cellular function such as pH, pO2, and Ca2+ are required. This review is focused on the progress in the design, fabrication, and application of photoluminescent nanoprobes for sensing and imaging of pH in living cells. The advantages of using nanoprobes carrying fluorescent pHindicators compared to single molecule probes are discussed as well as their limitations due to the mostly lysosomal uptake by cells. Particular attention is paid to ratiometric dual wavelength nanosensors that enable intrinsic referenced measurements. Referencing and proper calibration procedures are basic prerequisites to carry out reliable quantitative pH determinations in complex samples such as living cells. A variety of examples will be presented that highlight the diverseness of nanocarrier materials (polymers, micelles, silica, quantum dots, carbon dots, gold, photon upconversion nanocrystals, or bacteriophages), fluorescent pH indicators for the weak acidic range, and referenced sensing mechanisms, that have been applied intracellularly up to now.
Optical constants of harmful and highly energetic liquids for application to THz screening systems
(2016)
The far-infrared (IR) optical constants of a set of hazardous and flammable liquids have been obtained by means of spectroscopic ellipsometry in attenuated total reflection configuration over a broad spectral range. Such liquids recently became of considerable concern for transportation security measures worldwide. Their optical identification at check-in gates can only become possible if the characteristic spectra are already known. The refractive indices and the extinction coefficients reported here contribute to a spectroscopic data base in the far-IR and terahertz (THz) spectral regions and may support modeling the performance of THz screening systems on liquids for airports and other security sensitive areas. Examples of several container material/liquid systems are discussed. From the measured optical constants typical THz waveforms are calculated and discussed.
Silver nanoparticles (Ag NPs) are widely used in consumer products due to their excellent antibacterial properties. Their broad application has led to a variety of recent regulation on their use and labelling. Thus, a highly specific analytical method for their characterization and quantification is needed.
Due to their large separation range, field-flow fractionation (FFF) techniques are repeatedly applied for the analysis of NP. Limitations of FFF include quantification, sample loss and insufficient recovery rates. Another challenge can be non-ideal elution behavior of particles in complex and unknown matrices.
The possible sources for sample losses of Ag NP have been studied using an asymmetric flow FFF (AF4) in combination with inductively coupled plasma mass spectrometry (ICP-MS). The influence of different parameters, for example the sample concentration, on the recovery rates and sample loss has been investigated. Using laser ablation ICP-MS, the Ag deposition on the membrane was located and quantified. Our results identified ionic silver as the main sources of sample loss. These results can be useful for further method improvement.
However, when a Ag NP sample containing an unknown complex matrix is analyzed, FFF method optimization is challenging as the sample might show a shift in the retention times and lower recovery rates. In this case, ICP-MS experiment in the single particle mode (sp-ICP-MS) can be a useful addition to the FFF measurement. Here, upon assumption of spherical particles, the geometric diameters can be calculated. This fast and easy approach can be helpful in order to interpret the FFF fractograms and advice the FFF method optimization process.
A combined analysis of EXAFS and Raman spectra is applied for the study of
InxGa1-xN alloys with 0.3<x<0.5. Alloying causes relaxation of the selection rules resulting in
Raman spectra that resemble the vibrational density of states. On the other hand, theoretical
simulation of the Raman spectra using the Equation of Motion routine of FEFF8 provides the
vibrational component of the Debye-Waller factor (DWF). The static disorder component of
the DWFs was obtained by fitting the Ga and In K-edge EXAFS spectra. The analysis revealed
that the nearest neighbor distances of the 1st and 2nd shell deviate from the values predicted by
the law of Vegard and the virtual crystal approximation. The static disorder in the first nearest
neighboring shell (In-N and Ga-N) is null whereas in the cation-cation neighboring shells the
static component is generally smaller than the vibrational.
Recent technical developments of NMR instruments such as in acquisition electronics and probe design allow detection limits of components in liquid mixtures in the lower ppm range (approx.. 5–10 ppm amount of substance). The major advantage of quantitative NMR spectroscopy (qNMR) is that it is a direct ratio method of analysis without the need of calibration. This means that the signal for a specific NMR-active nucleus (e.g., a proton) in an analyte can be compared and quantified by reference to a different nucleus of a separate compound, comparable to a counting of spins in the active volume of the spectrometer.
Technical mixtures can be investigated online directly next to a process setup by using flow probes. This makes it a promising method for process analytical applications, especially during process development in laboratory and pilot plant scale. With the growing market of Benchtop devices based on permanent magnets nowadays an integration of NMR spectroscopy in an industrial environment becomes reasonable.
A special application of qNMR in technical mixtures is the observation in the gas phase, which is rarely applied compared to liquid and solid NMR studies. Because of the low density it results in a reduced sensitivity, which can be improved by applying pressure. Therefore a high-pressure NMR setup was developed based on a commercially available NMR tube made of zirconia. This is currently tested up to 20 MPa, but can be extended up to 100 MPa with regard to pressure rating of its components. This work shows results of gas-phase application on natural-gas like reference gas mixtures produced at BAM, as well as investigations on liquefied gas mixtures with high accuracy provided in piston cylinders.
Besides that amine gas treatment and hydroformylation in a microemulsion represent two other examples of applications in process analytical technology. These show the potential of combination of online NMR spectroscopy with other spectroscopic methods, especially during model development for data evaluation.
The successful mechanochemical syntheses of three cadmium phenylphosphonates indicates that mechanochemistry is ideally suited for synthesizing metal phosphonates. With this powerful synthesis tool it is possible to synthesize rapidly and efficiently both known and novel phosphonates. The Crystal structures of the two new compounds, and, were solved from PXRD data. They contain monodeprotonated phenylphosphonate and neutral phenylphosphonic acid ligands. The synthesis pathways of all three compounds were investigated in situ. A diffusion mechanism is corroborated by our findings.
Intermediates could be detected and identified. The kinetically favored product (3) could always be detected during the syntheses. The thermodynamic stability of the compounds and the stoichiometric ratio of the starting materials are the two directing factors for the synthesis of the final products.
Online NMR spectroscopy is an excellent tool to study complex reacting multicomponent mixtures and gain process insight and understanding. For online studies under process conditions, flow NMR probes can be used in a wide range of temperature and pressure. This paper compiles the most important aspects towards quantitative process NMR spectroscopy in complex multicomponent mixtures and provides examples. After NMR spectroscopy is introduced as an online method and for technical samples without sample preparation in deuterated solvents, influences of the residence time distribution, pre-magnetization, and cell design are discussed. NMR acquisition and processing parameters as well as data preparation methods are presented and the most practical data analysis strategies are introduced.
The lasing effect is demonstrated in laser plasmas induced on various metal targets and pumped by a laser tuned in resonance with a strong optical transition of a metal. The intense, polarized and lowdivergent radiation is emitted from a longitudinally pumped plasma plume in forward and backward directions with respect to the pump beam. Lasing occurs only within duration of the pumping pulse. The effect is found for elements of 13th and 14th groups and for Ca, Ti, Zr, Fe and Ni. The Einstein coefficients for spontaneous emission of all lasing transitions are higher than 10⁷ s⁻¹. For some elements like Al and In, a three-level lasing scheme is realized. For others, like Tl, both three- and four-level lasing schemes are realized. It is found that the longitudinal pump geometry is more efficient than the transversal one.
A boron dipyrromethene (BDP) unit and its monostyryl derivative (MSBDP) were introduced at the axial positions of a silicon(IV) phthalocyanine (SiPc) core. The absorption spectrum of this compound virtually covered the entire visible region (300-700 nm) and could be interpreted as a superposition of the spectra of individual components. The intramolecular photoinduced energy and charge transfer processes of this triad were studied using steady-state and time-resolved spectroscopic methods in polar and nonpolar solvents. Upon BDP-part excitation, a fast and highly efficient excitation energy transfer (EET) occurred resulting in strong quenching of its fluorescence and the formation of the first excited singlet state of SiPc or MSBDP. It was found that both EET and charge transfer (CT) processes competed with each other in the depopulation of the first excited singlet state of the MSBDP moiety. The former strongly superseded CT in nonpolar toluene, whereas the latter was dominant in a polar environment. Direct or indirect (via EET) excitation of the SiPc-part of the triad was followed by CT yielding the charge-separated (CS) species BDP-SiPc center dot--MSBDP center dot+. The energy gap between the CS state and the S-1-state of the SiPc moiety was found to be only 0.06 eV in toluene, which facilitated the back CT process and resulted in the appearance of thermally activated delayed fluorescence. With increasing solvent polarity, the energy of the CS state reduced resulting in the disappearance of the delayed fluorescence in CHCl3, tetrahydrofuran or N,N-dimethylformamide. The charge recombination rate, k(CR), was very fast in polar DMF (3.3 x 10(10) s(-1)), whereas this process was two-orders of magnitude slower in nonpolar toluene (k(CR) = 4.0 x 10(8) s(-1)).
The folding of single-stranded telomeric DNA into guanine (G) quadruplexes is a conformational change that plays a major role in sensing and drug targeting. The telomeric DNA can be placed on DNA origami nanostructures to make the folding process extremely selective for K+ ions even in the presence of high Na+ concentrations. Here, we demonstrate that the K+-selective G-quadruplex formation is reversible when using a cryptand to remove K+ from the G-quadruplex. We present a full characterization of the reversible switching between single-stranded telomeric DNA and G-quadruplex structures using Förster resonance energy transfer (FRET) between the dyes fluorescein (FAM) and cyanine3 (Cy3). When attached to the DNA origami platform, the G-quadruplex switch can be incorporated into more complex photonic networks, which is demonstrated for a three-color and a four-color FRET cascade from FAM over Cy3 and Cy5 to IRDye700 with G-quadruplex-Cy3 acting as a switchable transmitter.
Typically, mycotoxigenic moulds and consequently small percentages of extremely contaminated portions (“hot spots”) are randomly distributed in a cereal lot. Therefore, an efficient sampling procedure for mycotoxin analysis represents a complex challenge for operators involving invasive and cost intensive steps. Establishing an in situ analysis of mycotoxins from the homogeneous gas-phase above cereal crops instead of analysing random samples could address this difficult issue. During studies for microbial volatile organic compounds (MVOCs) indicating an infection with Fusarium, trichodiene was identified as a unique biosynthesis intermediate of trichothecenes - one of the largest groups of the mycotoxin family. The sesquiterpene trichodiene is the only volatile biogenic precursor of the trichothecenes, thus, early and fast in situ detection of this biomarker might be of interest for a potential trichothecene infestation. However, there is no commercial trichodiene standard available needed for the quantification of trichodiene in cereal grains.
The aim of the current project is to develop a fast, easy-to-handle and non-invasive gas-phase quantification of trichodiene in the field. Therefore, trichodiene was prepared by total synthesis based on a tandem orthoester Claisen rearrangement - oxidation - Robinson annulation strategy providing the racemic natural product in 9 steps and 8 % overall yield. Its structure was fully elucidated by NMR and MS. With the reference standard in hand, a protocol was established for the quantitative headspace analysis of trichodiene above crop spikes by GC/MS in the < 10 µg/kg range. Besides a sample survey and a trichodiene - trichothecene correlation study, it is aimed to transfer the validated analytical method from the laboratory into a field-portable analytical system.
The fast and reliable in situ detection of trichodiene as a volatile biomarker for trichothecene mycotoxins will contribute to a reduction of food production/analysis costs and to an improvement of food safety.
A monitoring method is introduced that creates twodimensional (2D) maps of the soil gas distribution. The method combines linear gas sensing technology for in-situ monitoring of gases in soil with the mapping capabilities of Computed Tomography (CT) to reconstruct spatial and temporal resolved gas distribution maps. A weighted iterative algebraic reconstruction method based on Maximum Likelihood with Expectation Maximization (MLEM) in combination with a source-by-source reconstruction approach is introduced that works with a sparse setup of orthogonally-aligned linear gas sensors. The reconstruction method successfully reduces artifact production, especially when multiple gas sources are present, allowing the discrimination between true and non-existing so-called ghost source locations. Experimental validation by controlled field experiments indicates the high potential of the proposed method for rapid gas leak localization and quantification with respect to Pipeline or underground gas storage issues.
The growing interest in artificial bioorganic Interfaces as a platform for applications in emerging Areas as personalized medicine, clinical diagnostics, biosensing, biofilms, prevention of biofouling, and other fields of bioengineering is the origin of a need for in Detail multitechnique characterizations of such layers and interfaces. The in-depth analysis of biointerfaces is of special interest as the properties of functional bioorganic coatings can be dramatically affected by in-depth variations of composition.
In worst cases, the functionality of a device produced using such coatings can be substantially reduced or even fully lost.
In this book many practical hints are given and analytical problems are discussed by the authors from their own experiences. A critical assessment of the methods is given, which is most important for decision makers to select a good combination of complementary methods to solve practical analytical problems.
Surface-enhanced Raman scattering (SERS) exploits the enhancement of electromagnetic fields in close vicinity of plasmonic nanostructures. The nanometer-scale spatial arrangement of plasmonic metal nanoparticles and analyte molecules has a significant effect on the observed signal enhancements and represents a great challenge in this technique. Especially interesting effects are expected for complex gold nanolenses (AuNLs), consisting of three or more differently-sized AuNPs. We use DNA origami to assemble AuNLs with 10, 20 and 60 nm AuNPs, arranged in three different geometries. Using correlated AFM and Raman spectroscopy, and probing single AuNLs, we systematically examined the SERS properties of the three different assemblies.
The development of iron oxide nanoparticles for biomedical applications requires accurate histological evaluation. Prussian blue iron staining is widely used but may be unspecific when tissues contain substantial endogenous iron. Here we tested whether microscopy by laser ablation coupled to inductively coupled plasma mass spectrometry (LA-ICP-MS) is sensitive enough to analyze accumulation of very small iron oxide particles (VSOP) doped with europium in tissue sections.
Resolution of capacitive sensors can be improved enormously by replacement of the dielectric material between the capacitor plates (e.g. air-dielectric) by a dielectric fluid with high permittivity. High dielectric liquid dispersions of ceramic micro and nano powders should be qualified as dielectric fluid with longtime shelf life.
For this purpose it was necessary to produce stabilized ceramic suspensions with high particle concentration and to investigate sedimentation processes of the particles. Characterization of particles was done by use of zeta potential measurement, gas adsorption measurements (BET), density measurement with gas pycnometer as well as particle sizing by ultrasound spectroscopy and by use of an optical centrifuge.
Shelf life of optimized electrostatic and steric stabilized ceramic suspension was investigated by use of an optical centrifuge, a LUMISizer 651 MW (LUM Ltd.) with STEP technology and front tracking analysis. Two different wave lengths – NIR (865 nm) and blue light (470 nm) were available for examination. Centrifugation measurements with different rotation speed were used to study the rheological behavior and the sedimentation process. By this way it was possible to achieve accelerated stability determination. Measured values could be used to simulate the sedimentation process under gravity acceleration and to predict shelf life for suspensions with different dispersants.
Since the advent of industrial computed tomography (CT), this new analysis method has been used also for the investigation of objects of cultural heritage and art. CT provides the possibility to determine the inner and outer surfaces and to investigate the material structure without causing damage to the valuable objects.
In this talk I will present examples of measurements performed at BAM, which demonstrate what CT can do for objects of diverse materials and for different objectives.
Medium-resolution nuclear magnetic resonance spectroscopy (MR-NMR) currently develops to an important analytical tool for both quality control and processmonitoring. In contrast to high-resolution onlineNMR (HR-NMR),MR-NMRcan be operated under rough environmental conditions. A continuous re-circulating stream of reaction mixture fromthe reaction vessel to the NMR spectrometer enables a non-invasive, volume integrating online analysis of reactants and products. Here, we investigate the esterification of 2,2,2-trifluoroethanol with acetic acid to 2,2,2-trifluoroethyl acetate both by 1H HR-NMR (500MHz) and 1H and 19F MRNMR (43MHz) as amodel system. The parallel online measurement is realised by splitting the flow,which allows the adjustment of quantitative and independent flow rates, both in the HR-NMR probe as well as in the MR-NMR probe, in addition to a fast bypass line back to the reactor. One of the fundamental acceptance criteria for online MR-MNR spectroscopy is a robust data treatment and evaluation strategy with the potential for automation. The MR-NMR spectra are treated by an automated baseline and phase correction using the minimum entropy method. The evaluation strategies comprise (i) direct integration, (ii) automated line fitting, (iii) indirect hard modelling (IHM) and (iv) partial least squares regression (PLS-R). To assess the potential of these evaluation strategies for MR-NMR, prediction results are compared with the line fitting data derived from the quantitative HR-NMR spectroscopy. Although, superior results are obtained from both IHM and PLS-R for 1H MR-NMR, especially the latter demands for elaborate data pretreatment, whereas IHM models needed no previous alignment.
CCQM has established a framework of comparisons to demonstrate the international comparability of chemical measurements. The key point is the establishment of comparable measurements, with traceability to internationally or nationally stated references. The Surface Analysis Working Group (SAWG) has been formally founded in 2003. CCQM ratified the group as a full working group of CCQM in April 2003 with these terms of reference:
- to develop pilot studies and carry out key comparisons of national measurement standards for surface and micro/nano-analysis;
- to assist in identifying and establishing inter-laboratory work to improve the traceability of surface and micro/nano-analysis;
- to establish and update a work plan to be adopted by CCQM;
- to discuss and review the scope of the working group and to liase with other working groups related to nanotechnology.
Following the 2015 meeting of the CCQM, the pilot study CCQM-P130 “WD and ED Electron Probe Micro Analysis on Au-Cu alloys” lead by BAM&NIST has been finalized. The Key Comparison K-129 “Measurement of atomic fractions in Cu(In,Ga)Se2 Films” lead by KRISS has made substantial progress and is about to be finalized. The new Key Comparison K-136 on “BET specific surface of ” lead by UNIIM&BAM has made strong progress in 2015 and will be finished in 2016.
Spray drying is a widely used process step in ceramic technology to
convert fine grained raw powders to free-flowing granules. Type and
amount of the organic additives (dispersants, binders and plasticizers)
define viscosity and stability of the slurry, the granulate structure and
the compaction behaviour.
Alumina and Zirconia powders were characterized with regard to
particle size, shape and specific surface area (BET). Zeta-potential
measurements by Stabino® were used to investigate the effect of
different dispersants on slurry stability. Unfortunately, this method is
restricted to suspensions with less than about 30% by weight of solid
content. The multi-sample analytical centrifuge LUMiSizer® overcomes
this problem. This device enables analysis of the separation behaviour
of suspensions over a wide range of solid content. On the basis of
position and time resolved photometric detection of transmitted light,
it is possible to determine the instability index, the sedimentation
velocity, and the sediment height in dependence of type and amount
of organic additives at various centrifugal accelerations. Additional
information is obtained from the shape of the transmission profiles.
Based on LUMiSizer® measurements, suitable additive concentrations
were derived. Thereby, the number of investigations by viscometry and
spray drying experiments can be significantly reduced.
Finally, it was possible to produce alumina, zirconia and ZTA aqueous
slurries with up to 80 weight-% of solid. The optimized suspensions
were successfully spray dried and the resulted granules show good
compaction behaviour.
The study of the distribution of the cytostatic drugs cisplatin, carboplatin, and oxaliplatin along the kidney may help to understand their different nephrotoxic behavior. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) allows the acquisition of trace element images in biological tissues. However, results obtained are affected by several variations concerning the sample matrix and instrumental drifts. In this work, an internal standardization method based on printing an Ir-spiked ink onto the surface of the sample has been developed to evaluate the different distributions and accumulation levels of the aforementioned drugs along the kidney of a rat model. A conventional ink-jet printer was used to print fresh sagittal kidney tissue slices of 4 μm. A reproducible and homogenous deposition of the ink along the tissue was observed. The ink was partially absorbed on top of the tissue. Thus, this approach provides a pseudo-internal standardization, due to the fact that the ablation sample and internal standard take place subsequently and not simultaneously. A satisfactory normalization of LA-ICP-MS bioimages and therefore a reliable comparison of the kidney treated with different Pt-based drugs were achieved even for tissues analyzed on different days. Due to the complete ablation of the sample, the transport of the ablated internal standard and tissue to the inductively coupled plasma-mass spectrometry (ICP-MS) is practically taking place at the same time. Pt accumulation in the kidney was observed in accordance to the dosages administered for each drug. Although the accumulation rate of cisplatin and oxaliplatin is high in both cases, their Pt distributions differ. The strong nephrotoxicity observed for cisplatin and the absence of such side effect in the case of oxaliplatin could explain these distribution differences. The homogeneous distribution of oxaliplatin in the cortical and medullar areas could be related with its higher affinity for cellular transporters such as MATE2-k.
Development of adapted GMR-probes for automated detection of hidden defects in thin steel sheets
(2016)
Thin steel sheets with a thickness of 0.3 mm and less are the base materials of many everyday life products (cans, batteries, etc.). Potential inhomogeneities such as non-metallic inclusions inside the steel can lead to a rupture of the sheets when it is formed into a product such as a beverage can. Therefore, there is a need to develop automated NDT techniques to detect hidden defects and inclusions in thin sheets during production. For this purpose Tata Steel Europe and BAM, the Federal Institute for Materials Research and Testing (Germany), collaborate in order to develop an automated NDT-system. Defect detection systems have to be robust against external influences, especially when used in an industrial environment. In addition, such a facility has to achieve a high sensitivity and a high spatial resolution in terms of detecting small inclusions in the μm-regime. In a first step, we carried out a feasibility study to determine which testing method is promising for detecting hidden defects and inclusions inside ferrous thin steel sheets. Therefore, two methods were investigated in more detail – magnetic flux leakage testing (MFL) using giant magneto resistance sensor arrays (GMR) as receivers [1,2] and eddy current testing (ET). The capabilities of both methods were tested with 0.2 mm-thick steel samples containing small defects with depths ranging from 5 μm up to 60 μm. Only in case of GMRMFL-testing, we were able to detect parts of the hidden defects with a depth of 10 μm trustworthily with a SNR better than 10 dB. Here, the lift off between sensor and surface was 250 μm. On this basis, we investigated different testing scenarios including velocity tests and different lift offs. In this contribution we present the results of the feasibility study leading to first prototypes of GMR-probes which are now installed as part of a demonstrator inside a production line.
A liver biopsy specimen from a Wilson’s disease (WD) patient was analyzed by means of micro-X-ray fluorescence (mXRF) spectroscopy to determine the elemental distribution. First, bench-top mXRF was utilized for a coarse scan of the sample under laboratory conditions. The resulting distribution maps of copper and iron enabled the determination of a region of interest (ROI) for further analysis. In order to obtain more detailed elemental information, this ROI was analyzed by synchrotron radiation (SR)-based mXRF with a beam size of 4 mm offering a resolution at the cellular level. Distribution maps of additional elements to copper and iron like zinc and manganese were obtained due to a higher sensitivity of SR-mXRF. In addition to this, X-ray absorption near edge structure spectroscopy (XANES) was performed to identify the oxidation states of copper in WD. This speciation analysis indicated a mixture of copper(I) and copper(II) within the WD liver tissue.
Previously on sulfur determination in metal revealed a lack of traceability and inconsistent results. Solving the problems a reference procedure for sulfur measurement in metal are required to build up a reliable reference value. In this study a procedure was developed for quantification of total sulfur at low concentration (in sub ppm level) in metal using inductively coupled plasma-isotope dilution mass spectrometry (ICP-IDMS). The ion exchange method and complexing agent were applied in this procedure to avoid loading large amount of metal into the instrument. Adding ammonia as a complexing agent into sample solution to reduce sulfur-metal co-elute. The procedure shows high performance and it is expressed in % recovery of sulfur (> 90%) and % metal elimination (>99 %). Additionally, relative measurement uncertainties were calculated less than 1.5 % and the results are traceable directly to SI units. This study would establish as reference procedure for sulfur measurement in metal sample which fit for these purpose as follows; for certified reference material and assigned value for inter-laboratory comparison.
Core capability tables list the skills and experiences, which at least partially are needed to successfully carry out a specific analytical task within the IAWG. The required skills and experiences, so-called core capabilities (CC), are identified for each analytical procedure. The summarized CC tables are listed in the appendix of each report on the corresponding key comparison or pilot study. These CC tables enable us to demonstrate that we have the analytical procedure we claim under control by means of other Key Comparison, which do not exactly meet the claimed calibration and measurement capability. This is especially important for: a) fields where no Key Comparison is available, b) Revision of CMC claims or c) when a participation in a Key Comparison was not possible.
CCQM-P149 is an attempt to obtain a snapshot on actual procedures the NMIs and DIs within CCQM-IAWG applied to the purity characterization of their “fit for purpose” elemental Standards. This presentation describes how the results of CCQM-P149 may be used to underpin calibration and measurement capabilities being claimed in the BIPM database.
Protein folding, unfolding and misfolding have become critically important to a range of health and industry applications. Increasing high temperature and high pressure are used to control and speed up reactions. A number of studies have indicated that these parameters can have a large effecton protein structure and function. Here we describe the additive effects of these parameters on the small angle scattering behaviour of ribonuclease A. We find that alternate unfolded structures can be obtained with combined high pressure and temperature treatment of the protein.
Hydroformylation represents an important homogeneous catalyzed process, which is widely used within chemical industry. Usually applied for short-chained alkenes like Propene and Butene aldehydes obtained from alkenes >C6 are relevant intermediates in production of plasticizers, surfactants and polymers. Today the active catalyst species is often based on valuable Rhodium complexes in aqueous solution. This implies the problem of limited water solubility of the reactants, which is acceptable for short chain lengths, but states a problem in case of higher alkenes. Along with that efficient separation and recycling of the catalyst becomes more complicated. There are different approaches tackling this problem, e.g., by using of salt formation in the BASF process or downstream distillation within the Shell process. Another promising approach is the processing within a microemulsion by using a suitable surfactant system. This maintains a large interface between catalyst and reactants, as well as the possibility of catalyst recycling via downstream phase separation in a settler. Optimized processing within the three-phase region in accordance with Kahlweit fish leads to an efficient product separation, while the valuable catalyst and surfactant can be recycled into the process. In this work we present reaction monitoring of Rh-catalyzed hydroformylation of 1 dodecene. Experiments were conducted on a specialized laboratory setup, which allows coupling of different online spectroscopic methods (Raman, HR-NMR, LF-NMR, UV/VIS) under process-similar conditions. The focus of this contribution lies on results of high-resolution Online-NMR obtained during calibration experiments for development of a multivariate model for Raman spectroscopy, which will be part of another contribution.
Resource Analytics with the help of process analytical technology and the use of online methods is becoming increasingly important for mining and processing technologies and for the recovery of raw materials from secondary raw materials. Current online analytical methods like laser-induced breakdown spectroscopy (LIBS), X-ray fluorescence analysis (RFA), or Raman spectroscopy for the characterization of primary and secondary raw materials are increasingly being used in close association with the technologies for exploration and extraction, mechanical and metallurgical processing, as well as for recycling. Because of the complex matrices such methods are a considerable challenge at the same time. The use of reference materials, which are derived from appropriate matrices, can considerably shorten calibration and method development times. As an example, the development of an online process control method for recovery of phosphorus from sewage sludge ashes is discussed. A combination of LIBS and RFA was developed for the determination of element contents in sewage sludge ashes and their products coming from a thermo-chemical reprocessing step, which removes pollutants.
The combination of Radio-frequency identification (RFID) and low energy sensors offers promising chances to implement cost effective, easy to apply, and easy to handle sensor systems for a variety of applications. The RFID technology is already well established in logistics. Enhanced processing and interface capabilities enable the integration of various sensors for control, diagnostics, and monitoring tasks. In the scope of research projects carried out at the Federal Institute for Materials Research and Testing (BAM), RFID sensor systems were developed and validated with regard to two different application scenarios: the Identification and diagnosis of concrete components for road bridges and the monitoring of dangerous goods transportation. This contribution presents selected research results and reflects the practical experiences on future chances and limitations of RFID sensor systems.
Surface enhanced Raman scattering (SERS) is a fast and sensitive spectroscopic method for the identification of analytes. With available portable Raman spectrometers, on-site analysis is possible. However, for on-site analysis, SERS substrates, which are cheap, easy to prepare, and simple in sample handling are necessary. Relevant analytes in the addressable concentration region for SERS are e.g. antibiotics and pesticides. Here, we present paper-based test strips for SERS analysis which are coated with silver nanoparticles. The coating was realized with different deposition methods of nanoparticle solutions. The papers were also functionalised with hydrophobic barriers to create μPADs. The strips were tested with selected analytes (e.g., adenine, rhodamine-6G) over a broad concentration range. The focus of our study lay on reproducibility and optimum SERS signal intensity.
For the quantification of analytes, highly reproducible signal intensities are necessary. We have realized this reproducibility in acceptable quality. Moreover, employing intensity vs concentration calibration for the analytes, data analysis revealed a behaviour that was best described by a Langmuir isotherm, stressing the strong distance dependence of the SERS effect. For a fast and reproducible analysis of the data, a Labview program was finally compiled, which was fed with the calibration data and derived the concentration of analyte unknowns accordingly.
Although aluminium is one of the most common elements in the biosphere, up to now little is known about its impact on human health. aluminium and its chemical derivatives are highly abundant in food, food contact materials and consumer products. Humans are exposed to aluminium via the gastrointestinal tract (GI tract). Exposition can change substantially due to consumer behavior since aluminium is also a compound of numerous food additives. Recently, aluminium exposition is increasingly considered to cohere with cancer and neurodegenerative disorders. Lately, due to an increasing attentiveness on this topic, limiting values for food additives have been tightened by the EFSA. However, cellular effects of aluminium and especially aluminium-containing nanomaterials, that represent a significant part of chemicals found in food products, are widely unknown and in the focus of our research activities, for example in the bilateral SolNanoTOX project. We established an in vitro simulation system of the GI tract, where nanomaterials undergo the different physiological, chemical and proteinbiochemical conditions of saliva, gastric juice and the intestine. The artificially digested nanomaterials, as well as soluble aluminium chloride as ionic control substance, were subjected to several analytical and biochemical methods to characterize their change of appearance and their cytotoxic effects on intestinal cellular models. We observed the fate of the nanomaterials during typical pH-values of saliva, gastric and intestinal juice with Dynamic light scattering measurements and ICP-MS in the single particle mode. After observable disappearance at pH 2 the particles recovered in the simulated intestinal fluid. The simulation of the GI tract, mainly the change of pH settings, can lead to a certain chemical activation of aluminium that can increase bioavailability in the intestine after oral uptake of aluminium-containing food products. In vitro assays like CTB, MTT and cellular impedance measurements showed that there were no acute cytotoxic effects measurable after a period up to 48h after incubation, comparable to undigested particles. In contrast, high amounts of aluminium ions showed synergistic effects on cell viability compared to non-digested aluminium ions. Although toxicological potential of Al ions to healthy tissue appears to be low, increased hazardous potential cannot be ruled out to pre-damaged tissue and can have a relevance in risk assessment for special consumer groups with for example chronical intestinal inflammation or dietary eating behavior combined with high exposure to Al-containing food products.
To understand the metabolic fate of food relevant mycotoxins in vitro systems were mainly used as the method of choice, so far. Yet, in recent years coupling of electrochemistry mass spectrometry (EC-MS) gained increasing importance as promising technique for fast simulation of metabolic processes and was successfully applied in particular for drug metabolism [1].
The aim of our work was to investigate the potential of EC-MS to predict phase I metabolites of priority mycotoxins and to compare the results with in vitro experiments. Hence, the EU-regulated Fusarium mycotoxins zearalenone (ZEN) and patulin as well as dihydroergocristine (DHEC) as model compound of ergot alkaloids were electrochemically oxidized and analyzed by EC MS for the first time.
Electrochemical conditions were set-up individually for each of the three mycotoxins. By using a coulometric flow through cell with a diamond working electrode oxidation of the chosen mycotoxins was observed after applying potentials between 1.7 and 2.0 V vs. Pd/H2. The electrochemically generated reaction products were analyzed online by mass-spectrometric detection.
All of the three chosen mycotoxins were electrochemically converted to mono- and/or dihydroxylated products confirming the results of ZEN related metabolism studies [2, 3] and in case of DHEC own results from in vitro assays. Due to a lack of metabolism studies concerning the oxidative fate of patulin, interpretation of EC-MS data and performing microsomal studies is of particular relevance.
Beside the identified products from electrochemical oxidation of ZEN, patulin and DHEC there is still a number of yet unknown compounds. Additional structural characterization of detected compounds by NMR and X-ray analysis will be facilitated by their large-scale production using preparative EC cells.
Air-coupled ultrasound has been applied increasingly as a non-destructive testing method for lightweight construction in recent years. It is particularly appropriate for composite materials being used in automotive and aviation industry. Air-coupled ultrasound transducers mostly consist of piezoelectric materials and matching layers. However, their fabrication is challenging and their signal-to-noise ratio often not sufficient for many testing requirements. To enhance the efficiency, air-coupled ultrasound transducers made of cellular polypropylene have been developed. Because of its small density and sound velocity, this piezoelectric ferroelectret matches the small acoustic impedance of air much better than matching layers applied in conventional transducers. In our contribution, we present two different methods of spherical focusing of ferroelectret transducers for the further enhancement of their performance in NDT applications. Measurements on carbon-fiber-reinforced polymer (CFRP) samples and on metal adhesive joints performed with commercially available focused air-coupled ultrasound transducers are compared to measurements executed with self-developed focused ferroelectret transducers.
Viscoelastic properties of cellular polypropylene ferroelectrets (PP FEs) were studied at low
frequencies (0.3–33 Hz) by dynamic mechanical analysis and at high frequencies (250 kHz) by laser Doppler vibrometry. Relaxation behavior of the in-plane Young’s modulus (Y´
11~1500 MPa at room temperature) was observed and attributed to the viscoelastic response of polypropylene matrix.
The out-of-plane Young’s modulus is very small (Y´33≈0.1 MPa) at low frequencies, frequency- and stress-dependent, evidencing nonlinear viscoelastic response of PP FEs. The highfrequency mechanical response of PP FEs is shown to be linear viscoelastic with Y´33≈0.8 MPa. It is described by thickness vibration mode and modeled as a damped harmonic oscillator with one degree of freedom. Frequency dependence of Y*33 in the large dynamic strain regime is described by the broad Cole-Cole relaxation with a mean frequency in kHz range attributed to the Dynamics of the air flow between partially closed air-filled voids in PP FEs. Switching-off the relaxation contribution causes dynamic crossover from the nonlinear viscoelastic regime at low frequencies to the linear viscoelastic regime at high frequencies. In the small strain regime, contribution of the air flow seems to be insignificant and the power-law response, attributed to the mechanics of polypropylene cell walls and closed air voids, dominates in a broad frequency range. Mechanical Relaxation caused by the air flow mechanism takes place in the sound and ultrasound frequency range (10 Hz–1MHz) and, therefore, should be taken into account in ultrasonic applications of the PP FEs deal with strong exciting or receiving signals.
Enzyme-activatable optical probes are important for future advances in cancer imaging, but may easily suffer from low signal-to-background ratios unless not optimized. To address this shortcoming, numerous mechanisms to modulate the fluorescence signal have been explored.
We report herein newly synthesized probes based on selfimmolative linkers containing chiral J-aggregate-forming dyes.
Signal modulation by formation of chiral J-aggregates is yet unexplored in optical enzyme probe design. The comprehensive characterization of the probes by absorption, CD, fluorescence, and time-resolved fluorescence spectroscopy revealed dye−dye interactions not observed for the free dyes in solution as well as dye−protein interactions with the enzyme. This suggested
that J-aggregate formation is challenging to achieve with current probe design and that interactions of the dyes with the Enzyme may interfere with achieving high signal-to-background ratios. The detailed understanding of the interactions provided herein provides valuable guidelines for the future design of similar probes.
New fluorinated alkaline earth metal−organic frameworks were successfully synthesized by milling of metal hydroxides M(OH)2 with tetrafluoroterephthalic acid H2 pBDC-F4. Both calcium- and strontium-tetrafluoroterephthalates are tetrahydrated, while the barium tetrafluoroterephthalate is free of coordinating water molecules. The two isomorphic structures Ca(pBDC-F4)·4H2O and Sr(pBDC-F4)·4H2O were solved from the powder diffraction data by ab initio structure determination and subsequent Rietveld refinement. The products were thoroughly characterized by elemental analysis, thermal analysis, magicangle spinning NMR, Fourier transform infrared spectroscopy, scanning electron microscopy imaging, and Brunauer−Emmett−Teller measurements. Our findings suggest that the mechanochemical synthesis route is a promising approach for the preparation of new fluorinated alkaline earth metal−organic frameworks.
The exact mechanisms of the phase transitions caused by a combined sulphate-chloride attack are discussed controversially. The main points concern the mutual influences of sulphate and chloride ions during the secondary binding processes of these anions within cement hydrate phases. We simulated combined sulphate-chloride attack under laboratory conditions using solutions containing NaCl and Na2SO4 in different concentrations. Three sample compositions were used for the preparation of the specimens. In two of them, 30% of Portland cement was replaced by supplementary cementitious materials (fly ash, slag). The phase distribution in the samples was determined using synchrotron X-ray diffraction. The analysis with high spatial resolution allows the localisation of the secondary phase formation in the microstructural profile of the sample. A mechanism of the phase developments under combined sulphate-chloride attack is derived.
In this contribution the particle sizing techniques evaluated in NanoDefine are presented together with recommendations for their application/implementation on real-world materials. The experimental evaluation is discussed based on examples on NanoDefine materials. A systematic study on volume specific surface area as derived from BET measurements versus electron microscopy on powdered materials is also presented.
Polysarcosine (M-n = 3650-20 000 g mol(-1), D similar to 1.1) was synthesized from the air and moisture stable N-phenoxycarbonyl-N-methylglycine. Polymerization was achieved by in situ transformation of the urethane precursor into the corresponding N-methylglycine-N-carboxyanhydride, when in the presence of a non-nucleophilic tertiary amine base and a primary amine initiator.
The organophosphate nerve agents Tabun (GA), Sarin (GB) and Soman (GD) are among the most toxic chemical warfare agents (CWA) known, and exert their biological effects by irreversibly inhibiting acetylcholinesterase enzymes of the human nerve system. The use of these agents in the past century has killed millions of civilians around the world during World Wars I and II, and after that, approximately 40.000 tons of chemical ammunition were dumped into the Baltic Sea, containing ca. 13.000 tons of chemical warfare agents. Since their production, almost all the nations of the world have been strictly avoiding the development and use of CWA, participating in active destruction of CWA stockpiles, especially since the Chemical Weapon Convention (CWC) of 1993. However, CWA have been used in offensive ways against civilian population by terrorists, as for instance in the fatal Tokyo subway terror incident of 1995 or, most recently, against antigovernment demonstrators in Syria in 2013. Due to their higher toxicity and continuous use, it is therefore very important to develop simple and fast detection methods relying on new nerve agent sensing modalities for use in control and inspection.
A practically useful fluorescent probe must possess a rapid response and high sensitivity, and shall be implementable into easy-to-use devices for real time detection by untrained personnel. Taking into account this fact, in this work we have synthesized several mesoporous silica materials containing boron–dipyrromethene (BODIPY) moieties for the detection of nerve agents GA, GB and GD in the gas phase. Development of our system indicated that the most potent materials are able to respond to the presence of nerve agent simulants diethyl cyanophosphonate, diethyl chlorophosphate and diisopropyl fluorophosphate, which have to be used in a laboratory setting, yet also for the real nerve agents Sarin, Soman and Tabun, producing a strong quenching of the fluorescence. Furthermore, a portable device for the detection of GA, GB and GD in the gas phase has been prepared for in situ sensing and rapid screening applications, consisting of strips that are able to indicate the targets down to below 1 mgm-3 which is below the LD50 values.
We aim at preparing, characterising, and applying SURMOFs incorporating electro-active and -switchable mechanically interlocked molecules such as rotaxanes as the basis of functional devices.
Preparation and Positioning
Synthesis, purification and analytical characterization of electro-switchable rotaxanes suitable for SURMOF-formation as well as Layer-by-Layer assembly on surfaces.
Controlled deposition of electro-active SURMOFs and Layer-by-Layer self-assembled multilayers based on these switchable rotaxanes.
Construction of SURMOFs on micro-patterned surfaces.
Structural Characterisation and Physico-Chemical Properties
Electrochemical characterization of these rotaxanes in solution with cyclic voltammetry, chronoamperometry and impedance spectroscopy.
Surface characterization of SURMOFs and multilayers with XPS, NEXAFS, AFM, contact-angle measurements, transmission UV/Vis, ToF-SIMS and – in cooperation with partners from SPP – XRD.
Development of ToF-SIMS (also assisted by Principle Component Analysis of the fragment-ion data) as a method for imaging and depth-profiling.
Development of an appropriate electrochemical cell to perform cyclic voltammetry, chronoamperometry and impedance spectroscopy with SURMOFS and multilayers as working electrodes in a three-electrode cell.
Comparison of the structural and electrochemical properties of the redox-active unit in solution, multilayers and SURMOF focusing on the advantages of SURMOFs.
System Integration and Function Demonstration
Examination of the usability of the electroactive SURMOFS as optoelectronic switch or data storage device with a focus on the robustness of the system.
Usage of the SURMOFs as functional electrodes for electrochemical application.
Selective switching of ordered nanostructures to translate molecular motion to macroscopic property changes.