Wissenschaftliche Artikel der BAM
Filtern
Erscheinungsjahr
- 2019 (136) (entfernen)
Dokumenttyp
Sprache
- Englisch (136)
Referierte Publikation
- ja (136) (entfernen)
Schlagworte
- Fluorescence (8)
- Flame retardant (4)
- Mechanochemistry (4)
- Nanoparticles (4)
- Corrosion (3)
- Energy label (3)
- Quantum yield (3)
- Additive manufacturing (2)
- Atomic force microscopy (2)
- BODIPY (2)
- Boehmite (2)
- Carbon steel (2)
- Cellulose (2)
- Characterization (2)
- Concrete (2)
- DNA origami (2)
- Discotic Liquid Crystals (2)
- Distributed vibration sensing (2)
- Dual sensing (2)
- EPDM (2)
- Electrochemistry (2)
- Energy transfer (2)
- Epoxy (2)
- Ettringite (2)
- Explicit dynamics (2)
- Fatty acid metabolism (2)
- Ferromagnetism (2)
- Gadolinium (2)
- Hyperbranched (2)
- Impact simulation (2)
- In situ (2)
- Indium phosphide (2)
- Interphase (2)
- Isogeometric analysis (2)
- Lifetime (2)
- Lipidomic profile (2)
- MALDI-TOF MS (2)
- Metabolic stress (2)
- Nanomaterial (2)
- Nanostructures (2)
- Polylactide (2)
- Quantum dots (2)
- Raman spectroscopy (2)
- Reinforced concrete (2)
- SAXS (2)
- Scattering (2)
- Sensitization (2)
- Sensor (2)
- Small-angle scattering (2)
- Synthesis (2)
- ToF-SIMS (2)
- Tumor metabolism (2)
- Upconversion nanoparticles (2)
- X-ray diffraction (2)
- 3D inspection (1)
- 3D printing (1)
- AISI 304L (1)
- Adulteration (1)
- Advanced Materials (1)
- Aerial robot olfaction (1)
- Ageing (1)
- Aggregates (1)
- Agriculture (1)
- Air conditioner (1)
- Alexander von Humboldt (1)
- Alkali-activated materials (1)
- Alkali-activated slag (1)
- Alpha (1)
- Altenuene (1)
- Alternaria mycotoxins (1)
- Alumina (1)
- Aluminum diethylphosphinate (1)
- Aluminum trihydroxide (ATH) (1)
- Amorphous carbon (1)
- Analytical methods (1)
- Anisotropic fiber orientation (1)
- Anobium punctatum (1)
- Anomalous Small Angle X-ray Scattering (1)
- Antibacterial (1)
- Antifouling surface (1)
- Array (1)
- Artificial neural network (1)
- Artificial neural networks (1)
- Automated Modal Analysis for Tracking Structural Change during Construction and Operation Phases (1)
- Autophagy (1)
- BODIPYs (1)
- Bacterial adhesion (1)
- Ball milling (1)
- Bead injections (1)
- Bead-based assay (1)
- Bee diseases (1)
- Bee health (1)
- Benz[a]anthracene (BaA) (1)
- Benzin (1)
- Benzo[a]pyrene (BaP) (1)
- Binder (1)
- Bioactive glass (1)
- Biochip (1)
- Bioconjugation (1)
- Biodegradable (1)
- Biofilm (1)
- Biological pest control (1)
- Biomarkers (1)
- Biomaterials (1)
- Biopolymer (1)
- Biosilicification (1)
- Blade (1)
- Blended cement (1)
- Bloch wall (1)
- Boden (1)
- Boehmite nanoparticles (1)
- Brick clay (1)
- Broadband dielectric microscopy (1)
- Bulk temperature (1)
- C-C coupling (1)
- C-OTDR (1)
- CCUS (1)
- CO2 (1)
- CO2 separation membranes (1)
- COK-12 (1)
- CONSENS (1)
- Calcined clay (1)
- Calorimetry (1)
- Carbamazepine (1)
- Carbide (1)
- Carbon capture, utilization and storage technology (1)
- Carriers (1)
- Catalyst (1)
- Catalysts (1)
- Cationic photocuring (1)
- Cell size (1)
- Cement admixtures (1)
- Cement hydration (1)
- Ceramic (1)
- Chemometrics (1)
- Chunky graphite (1)
- Civil engineering (1)
- Cleridae (1)
- Co (1)
- Cobaloxime complex (1)
- Cobalt (1)
- Coda wave interferometry (1)
- Coherent optical time domain reflectometry (1)
- Coleoptera (1)
- Colourants (1)
- Composites (1)
- Compression set (1)
- Compressive strength (1)
- Condensate (1)
- Condition monitoring (1)
- Cone calorimeter (1)
- Continuous processes (1)
- Coputed tomography (1)
- Core-shell nanoparticles (1)
- Core−shell particles (1)
- Corresponding relative humidity (1)
- Corrosion monitoring (1)
- Cr(III) complex (1)
- Cracks (1)
- Cross-linking (1)
- Crosslinking density (1)
- Crystalline cones (1)
- Crystallization (1)
- Cultural heritage (1)
- Curie temperature (1)
- Cyclic (1)
- Cyclic softening (1)
- Cyclization (1)
- Cycloaliphatic epoxy oligosiloxane (1)
- Cytotoxicity (1)
- DFA (1)
- DFG SPP 2005 (1)
- DFT (1)
- DLO (1)
- DMA (1)
- DPA (1)
- DRIFTS (1)
- DTGS (1)
- DVS (1)
- Damage detection (1)
- Dampfdruck (1)
- Damping factor (1)
- Data Fusion (1)
- Dead Sea Scrolls (1)
- Decision support (1)
- Degradation of refrigerants (1)
- Delta value (1)
- Dendritic (1)
- Density Functional Theory (1)
- Deuterium (1)
- Dibenzo[d,f][1,3,2]dioxaphosphepine 6-oxide (1)
- Dielectric breakdown (1)
- Diffraction (1)
- Disposal (1)
- Distributed acoustic sensing (1)
- Distributed acoustic sensing (DAS) (1)
- Distributed fiber optic sensors (1)
- Distributed humidity sensing (1)
- Distributed sensing (1)
- Distributed strain sensing (1)
- Distributed temperature gradient sensing (1)
- Distributed vibrations sensing (DVS) (1)
- Domain wall (1)
- Double complex salts (1)
- Dual phase steel (1)
- Dye (1)
- Dynamic test method (1)
- EC nanomaterial definition (1)
- EC/MS (1)
- ELISA (1)
- EXAFS (1)
- Early oxidation (1)
- Early sulfidation (1)
- Elastin (1)
- Electro-fused zirconia (1)
- Electrochemical characterisation (1)
- Electrochemical impedance spectroscopy (1)
- Electromagnetic stirring (1)
- Electron microscopy (1)
- Electron transfer (1)
- Embedded sensors (1)
- Energetic Materials (1)
- Epoxy conversion degree (1)
- Europium (1)
- Exchange interaction (1)
- Exchange length (1)
- Excimers (1)
- Expert system (1)
- FSDC (1)
- Fatigue (1)
- Fe (1)
- Femtosecond laser (1)
- Fenton’s reagent (1)
- Ferritic spheroidal graphite cast iron (1)
- Ferritic steels (1)
- Ferritic–martensitic steel (1)
- Ferumoxytol (1)
- Fiber optic sensors (1)
- Fiber optics sensors (1)
- Fiber structuring (1)
- Fiber-optic sensing (1)
- Fiber-reinforced concrete (1)
- Fiberoptic sensors (1)
- Finite element analysis (1)
- Fire test (1)
- Flame retardance (1)
- Fluoreszenz (1)
- Fluoroacetic acid (1)
- Foams (1)
- Food (1)
- Food fermentation (1)
- Food safety (1)
- Formation (1)
- Friction (1)
- Fs-inscription (1)
- Full penetration (1)
- Fully aromatic frameworks (1)
- Fungus (1)
- Funtional Groups (1)
- Gamma (1)
- Gas chromatography (GC) (1)
- Gas explosion (1)
- Gas sensing (1)
- Gas tomography (1)
- Gasoline (1)
- Genome (1)
- Genotoxicity testing (1)
- Geology (1)
- Geothermal (1)
- Giant magnetoresistance (1)
- Glass scanning (1)
- Graphene (1)
- Graphene Oxide (1)
- Ground water (1)
- Grout (1)
- HNBR (1)
- HTS (1)
- Hardmetal (1)
- Heat pump (1)
- Herbaspirillum seropedicae (1)
- High-voltage testing (1)
- Hot-electrons (1)
- Hybrid laser-arc welding (1)
- Hydrogel (1)
- Hydrogen (1)
- Hydrolysis (1)
- Hydrothermal fluid (1)
- Icing conditions (1)
- Illite (1)
- Imidazole (1)
- Impurities (1)
- In-situ testing (1)
- In-vivo (1)
- Inconel 718 (1)
- Incremental lifetime models (1)
- Indenter modulus (1)
- Independent test method (1)
- Infrared nano AFM (1)
- Interlaboratory comparison (1)
- Intermodulation (1)
- Intermodulation AFM (1)
- Intermodulation-AFM (1)
- Inverse analysis (1)
- Iron (1)
- Iron oxide (1)
- Isotope dilution (ID) (1)
- Isotope ratio (1)
- Isotope-labeled (1)
- Issues (1)
- Kaolinite (1)
- Kinetics (1)
- Korynetes caeruleus (1)
- LC/HRMS (1)
- LL equation (1)
- LLG (1)
- Lab-on-a-Chip (1)
- Laboratory breeding (1)
- Lache (1)
- Ladder sequencing (1)
- Landau Lifshitz Gilbert equation (1)
- Landau Lifshitz equation (1)
- Lanthanide (1)
- Large-pore (1)
- Laser Powder Bed Fusion (1)
- Laser beam melting (1)
- Laser beam welding (1)
- Laser welding (1)
- Laser-induced X-ray emission (1)
- Laser-induced nanostructures (1)
- Laser-induced periodic surface structures (LIPSS) (1)
- Laser-modified surface (1)
- Layers (1)
- Leak-tightness (1)
- Life history data (1)
- Liquid chromatography (LC) (1)
- Localised corrosion (1)
- Longst luminescence lifetime (1)
- Low cycle fatigue (1)
- Luminescence (1)
- Lysosome (1)
- MALDI (1)
- MOF (1)
- Magnesium (1)
- Magnet coupling (1)
- Magnetic (1)
- Magnetic Nanoparticles (1)
- Magnetic anisotropy (1)
- Magnetic interacion (1)
- Magnetic moment (1)
- Magnetic properties (1)
- Magnetic sensors (1)
- Magnetic thin films (1)
- Magnetization dynamics (1)
- Manuscripts (1)
- Market surveillance (1)
- Martensite (1)
- Mass spectrometry (1)
- Mass spectrometry (MS) (1)
- Mechanical property (1)
- Melamine cyanurate (1)
- Melamine polyphosphate (1)
- Mesofluidics (1)
- Mesoporous Silica (1)
- Metal carbides (1)
- Metal phosphonates (1)
- Metal–organic frameworks (1)
- Metathesis (1)
- Method (1)
- Microbeads (1)
- Microcracking (1)
- Microfine Cement (1)
- Micromagnetism (1)
- Mikroplastik (1)
- Minimum energy performance standards (1)
- Mix-design (1)
- Mixed surface (1)
- Mobile robot olfaction (1)
- Model (1)
- Modified mycotoxins (1)
- Moisture (1)
- Molecular MRI (1)
- Molecular sieves (1)
- Molecule (1)
- Monensin (1)
- Mortar method (1)
- Multiplex (1)
- Multivariate (1)
- Multivariate data analysis (1)
- NIR (1)
- NIR Spectroscopy (1)
- NIR dyes (1)
- NMR (1)
- NMR Spectroscopy (1)
- Nanaoparticles (1)
- Nanocasting (1)
- Nanocomposite (1)
- Nanocomposites (1)
- Nanoconfinement (1)
- Nanolenses (1)
- Nanomechanical properties (1)
- Nanomechanics (1)
- Nanoparticle dimers (1)
- Nanoporous (1)
- Nanosciences (1)
- Nanostructured material (1)
- Natural (1)
- Neel wall (1)
- Ni (1)
- Nickel (1)
- Non-destructiv testing (1)
- Non-invasive analysis (1)
- Nosema ceranae (1)
- OOMMF (1)
- OTDR (1)
- Object oriented micromagnetic framework (1)
- Oligonucleotides (1)
- Optical fiber sensor (1)
- Optical frequency-domain reflectometry (1)
- Organic contaminants (1)
- Organic–inorganic nanostructures (1)
- Origami (1)
- Oscillating magnetic field (1)
- Osmia bicornis (1)
- Oxidative metabolism (1)
- Oxygen permability (1)
- Oxygen sensitive (1)
- P92 (1)
- Parabolic flight (1)
- Paramagnetism (1)
- Pathogen (1)
- Pathogen transmission (1)
- Peptide library (1)
- Performance (1)
- Permeability (1)
- Pesticide (1)
- Pflanzenwachstum (1)
- Pharmaceutical (1)
- Phase transition (1)
- Phase-sensitive (1)
- Phospha-Michael addition (1)
- Phosphinine (1)
- Phosphorus (1)
- Photocatalytic reduction (1)
- Photochemistry (1)
- Photophysics (1)
- Photostability (1)
- Physical relaxation (1)
- Phytoliths (1)
- Pipeline integrity (1)
- Pitting corrosion (1)
- Plant pathogen (1)
- Plasmonic heating (1)
- Plume (1)
- Polyaniline (1)
- Polycarbonate (1)
- Polycyclic aromatic hydrocarbon (PAH) (1)
- Polyethylene (1)
- Polyimide-coated optical fibers (1)
- Polyisocyanurate (1)
- Polymers (1)
- Polyphosphoester (1)
- Pore fluids (1)
- Porous building materials (1)
- Porphyrin (1)
- Portland cement (1)
- Powder X-ray diffraction (1)
- Prediction (1)
- Prevention (1)
- Probe (1)
- Properties (1)
- Ptinidae (1)
- Quality assurance (1)
- Quantitative Analysis (1)
- Quantitative moisture measurement (1)
- Quantum dot (1)
- RFID based sensors (1)
- Radiation protection (1)
- Rainwater (1)
- Raman (1)
- Raman-spectroscopy (1)
- Rapid mass calorimeter (1)
- Real time measurement (1)
- Real use behavior (1)
- Real-time imaging (1)
- Real-time infrared spectroscopy (1)
- Real-time process monitoring (1)
- Real-time quality control (1)
- Relaxation fatigue (1)
- Residual stress (1)
- Resistance spot welding (1)
- Restoration and conservation (1)
- Reverse glass painting (1)
- Reverse microemulsion (1)
- Rhizopus and Aspergillus oryzae (1)
- Rice (1)
- Risk assessment (1)
- Rosin (1)
- Rubber (1)
- SDC (1)
- SEM (1)
- SERS (1)
- SIDA-LC-MS/MS (1)
- Safe by design (1)
- Salicylate (1)
- Salicylic acid (1)
- Salts (1)
- Samarium doped ceria (1)
- Scaffolds (1)
- Scanning electrochemical microscope (SECM) (1)
- Scavenging effect of iron (1)
- Scission (1)
- Screening (1)
- Screening method (1)
- Seal failure (1)
- Seasonal energy efficiency ratio (1)
- Seasonal performance factor (1)
- Selective Laser Melting (1)
- Shrinkage Reducing Admixture (1)
- Silica coating (1)
- Simulation (1)
- Single molecule (1)
- Single-source precursors (1)
- Sintering (1)
- Soil (1)
- Solid state NMR (1)
- Solitary bees (1)
- Sorghum (1)
- Spectral elements (1)
- Spectroscopy (1)
- Spill evaporation (1)
- Spin (1)
- SsNMR (1)
- Stained glass (1)
- Standardization (1)
- Steel (1)
- Stepwise growth (1)
- Stereocomplex (1)
- Stimulated Brillouin scattering (1)
- Stochastic Landau Lifshitz Gilbert equation (1)
- Stochastic Landau Lifshitz equation (1)
- Stretchable electronics (1)
- Structural health monitoring (1)
- Structured light scanning (1)
- Struvite (1)
- Sub-oxide (1)
- Sulfide sensing (1)
- Superparamagnetism (1)
- Superplasticizer (1)
- Supplementary Cementitious Materials (1)
- Surface (1)
- Surface Chemistry (1)
- Surface chemistry (1)
- Surface-enhanced Raman scattering (1)
- Sustainability (1)
- Suzuki coupling (1)
- Suzuki-Miyaura coupling (1)
- Synchrotron FTIR (1)
- Synchrotron X-ray diffraction (1)
- Synchrotron x-ray refraction radiography (SXRR) (1)
- Synergy (1)
- T-SEM (1)
- TDLAS (1)
- TFA (1)
- Target (1)
- Temeprature scaling (1)
- Temperature (1)
- Temperature effects (1)
- Temple Scroll (1)
- Test strips (1)
- Teststreifen (1)
- Thermal expansion (1)
- Thermoplastic polyurethane (1)
- Thermoplastics (1)
- Thick materials (1)
- Thick shells (1)
- Thin film systems (1)
- Thin magnetic films (1)
- Ti-6Al-4V (1)
- Toxicity (1)
- Transformation product (1)
- Transformation products (1)
- Triplet-triplet annihilation (1)
- Tumble dryer (1)
- UV Vis (1)
- Ultrashort laser material interaction (1)
- Ultrashort laser pulses (1)
- Upconverstion (1)
- Validation trial (1)
- Value of action analysis (1)
- Variable frequency drive (1)
- Verdampfung (1)
- Verdunstung (1)
- Veterinary drugs (1)
- Virulence (1)
- Water (1)
- Water transport (1)
- Wear (1)
- Wild bees (1)
- Wind turbine (1)
- Windgeschwindigkeit (1)
- Wood protection (1)
- Work function (1)
- Writing materials (1)
- X-ray Photoelectron Spectroscopy (1)
- X-ray absorption Fine Spectroscopy (1)
- X-ray and electron diffraction (1)
- X-ray computed tomography (CT) (1)
- X-ray computed tomography (XCT) (1)
- X-ray reflectivity (1)
- XPS (1)
- XRD (1)
- XRF (1)
- Yb(III) complex (1)
- Yerba mate tea (1)
- Zearalenone sulfate (1)
- Zellulose (1)
- a-zearalenol (1)
- mortar method (1)
- qPCR (1)
- spectral elements (1)
- temeprature dependent exchange length (1)
- µ-gravity (1)
- γ-H2AX assay (1)
Organisationseinheit der BAM
- 1 Analytische Chemie; Referenzmaterialien (43)
- 6 Materialchemie (34)
- 7 Bauwerkssicherheit (18)
- 8 Zerstörungsfreie Prüfung (17)
- 6.3 Strukturanalytik (13)
- 4 Material und Umwelt (12)
- 5 Werkstofftechnik (12)
- 1.2 Biophotonik (11)
- 1.7 Organische Spuren- und Lebensmittelanalytik (11)
- 6.6 Physik und chemische Analytik der Polymere (9)
The ease with which an energetic material (explosives, propellants, and pyrotechnics) can be initiated is a critical parameter to assess their safety and application. Impact sensitivity parameters are traditionally derived experimentally, at great cost and risk to safety. In this work we explore a fully ab initio Approach based on concepts of vibrational energy transfer to predict impact sensitivities for a series of chemically, structurally and energetically diverse molecular materials. The quality of DFT calculations is assessed for a subset of the materials by comparison with experimental inelastic neutron scattering spectra (INS). A variety of models are considered, including both qualitative and quantitative analysis of the vibrational spectra. Excellent agreement against experimental impact sensitivity is achieved by consideration of a multi-phonon ladder-type up-pumping mechanism that includes both overtone and combination pathways, and is improved further by the added consideration of temperature. This fully ab initio approach not only permits ranking of energetic materials in terms of their impact sensitivity but also provides a tool to guide the targeted design of advanced energetic compounds with tailored properties.
Hybrid laser-arc welding offers many advantages, such as deep penetration, good gap bridge-ability, and low distortion due to reduced heat input. The filler wire which is supplied to the process is used to influence the microstructure and mechanical properties of the weld seam.
A typical problem in deep penetration high-power laser beam welding with filler wire and hybrid laser-arc welding is an insufficient mixing of filler material in the weld pool, leading to a non-uniform element distribution in the seam. In this study, oscillating magnetic fields were used to form a non-conservative component of the Lorentz force in the weld pool to improve the element Distribution over the entire thickness of the material. Full penetration hybrid laser-arc welds were performed on 20-mm-thick S355J2 steel plates with a nickel-based wire for different arrangements of the oscillating magnetic field. The Energy-dispersive X-ray spectroscopy (EDS) data for the distribution of two tracing elements (Ni and Cr) were used to analyze the homogeneity of dilution of the filler wire.
With a 30° turn of the magnetic field to the welding direction, a radical improvement in the filler material distribution was demonstrated. This would lead to an improvement of the mechanical properties with the use of a suitable filler wire.
The advantage of selective laser melting (SLM) is its high accuracy and geometrical flexibility.
Because the maximum size of the components is limited by the process chamber, possibilities must be found to combine several parts manufactured by SLM. An application where this is necessary, is, for example, the components of gas turbines, such as burners or oil return pipes, and inserts, which can be joined by circumferential welds. However, only a few investigations to date have been carried out for the welding of components produced by SLM. The object of this paper is, therefore, to investigate the feasibility of laser beam welding for joining SLM tube connections made of nickel-based alloys.
For this purpose, SLM-manufactured Inconel 625 and Inconel 718 tubes were welded with a Yb:YAG disk laser and subsequently examined for residual stresses and defects. The results showed that the welds had no significant influence on the residual stresses. A good weld quality could be achieved in the seam circumference. However, pores and pore nests were found in the final overlap area, which meant that no continuous good welding quality could be accomplished. Pore formation was presumably caused by capillary instabilities when the laser power was ramped out.
The influence of processing parameters on X‑ray emission during ultra‑short pulse laser machining
(2019)
During ultra-short laser material processing at high laser pulse repetition rates unwanted X-ray radiation can be generated in a quantity that may constitute a potential risk for health. An adequate X-ray radiation protection requires a thoroughly understanding of the influence of the laser processing parameters on the generation of X-ray radiation. In the present work, the generated X-ray dose during laser machining was investigated in air for varying beam scanning conditions at a pulse duration of 925 fs, a center wavelength of 1030 nm and a laser peak intensity of 2.6 × 10^14 W/cm^2. The X-ray radiation dose and the corresponding spectral X-ray emission were investigated in dependence on the laser’s pulse repetition rate and on the beam scanning speed. The results show a strong dependence of the X-ray emission on these laser processing parameters.
Hot-electron-induced reactions are more and more recognized as a critical and ubiquitous reaction in heterogeneous catalysis. However, the kinetics of these reactions is still poorly understood, which is also due to the complexity of plasmonic nanostructures. We determined the reaction rates of the hot-electron-mediated reaction of 4-nitrothiophenol (NTP) on gold nanoparticles (AuNPs) using fractal kinetics as a function of the laser wavelength and compared them with the plasmonic enhancement of the system. The reaction rates can be only partially explained by the plasmonic response of the NPs. Hence, synchrotron X-ray photoelectron spectroscopy (XPS) measurements of isolated NTP-capped AuNP clusters have been performed for the first time. In this way, it was possible to determine the work function and the accessible valence band states of the NP systems. The results show that besides the plasmonic enhancement, the reaction rates are strongly influenced by the local density of the available electronic states of the system.
Background signals from in situ-formed amorphous carbon, despite not being fully understood, are known to be a common issue in few-molecule surface-enhanced Raman scattering (SERS). Here, discrete gold and silver nanoparticle aggregates assembled by DNA origami were used to study the conditions for the formation of amorphous carbon during SERS measurements. Gold and silver dimers were exposed to laser light of varied power densities and wavelengths. Amorphous carbon prevalently formed on silver aggregates and at high power densities. Time-resolved measurements enabled us to follow the formation of amorphous carbon. Silver nanolenses consisting of three differently-sized silver nanoparticles were used to follow the generation of amorphous carbon at the single-nanostructure level. This allowed observation of the many sharp peaks that constitute the broad amorphous carbon signal found in ensemble measurements. In conclusion, we highlight strategies to prevent amorphous carbon formation, especially for DNA-assembled SERS substrates.
The large number of nanomaterial-based applications emerging in the materials and life sciences and the foreseeable increasing use of these materials require methods that evaluate and characterize the toxic potential of these nanomaterials to keep safety risks to people and environment as low as possible. As nanomaterial toxicity is influenced by a variety of parameters like size, shape, chemical composition, and surface chemistry, high throughput screening (HTS) platforms are recommended for assessing cytotoxicity. Such platforms are not yet available for genotoxicity testing. Here, we present first results obtained for application-relevant nanomaterials using an automatable genotoxicity platform that relies on the quantification of the phosphorylated histone H2AX (γ-H2AX) for detecting DNA double strand breaks (DSBs) and the automated microscope system AKLIDES® for measuring integral fluorescence intensities at different excitation wavelengths. This platform is used to test the genotoxic potential of 30 nm-sized citrate-stabilized gold nanoparticles (Au-NPs) as well as micellar encapsulated iron oxide nanoparticles (FeOx-NPs) and different cadmium (Cd)-based semiconductor quantum dots (QDs), thereby also searching for positive and negative controls as reference materials. In addition, the influence of the QD shell composition on the genotoxic potential of these Cd-based QDs was studied, using CdSe cores as well as CdSe/CdS core/shell and CdSe/CdS/ZnS core/shell/shell QDs. Our results clearly revealed the genotoxicity of the Au-NPs and its absence in the FeOx-NPs. The genotoxicity of the Cd-QDs correlates with the shielding of their Cd-containing core, with the core/shell/shell architecture preventing genotoxicity risks. The fact that none of these nanomaterials showed cytotoxicity at the chosen particle concentrations in a conventional cell viability assay underlines the importance of genotoxicity studies to assess the hazardous potential of nanomaterials.
Elastomers are susceptible to chemical ageing, i.e., scission and cross-linking, at high temperatures. This thermally driven ageing process affects their mechanical properties and leads to limited operating time. Continuous and intermittent stress Relaxation measurements were conducted on ethylene propylene diene rubber (EPDM) and hydrogenated nitrile butadiene rubber (HNBR) samples for different ageing times and an ageing temperature of 125 °C. The contributions of chain scission and cross-linking were analysed for both materials at different ageing states, elucidating the respective ageing mechanisms. Furthermore, compression set experiments were performed under various test conditions. Adopting the two-network model, compression set values were calculated and compared to the measured data. The additional effect of physical processes to scission and cross-linking during a long-term thermal exposure is quantified through the compression set analysis. The characteristic times relative to the degradation processes are also determined.
Determining a suitable and reliable end-of-lifetime criterion for O-ring seals is an important issue for long-term seal applications. Therefore, seal failure of ethylene propylene diene rubber (EPDM) and hydrogenated nitrile butadiene rubber (HNBR) O-rings aged in the compressed state at 125 °C and at 150 °C for up to 1.5 years was analyzed and investigated under static conditions, using both non-lubricated and lubricated seals. Changes of the material properties were analyzed with dynamic-mechanical analysis and permeability experiments. Indenter modulus measurements were used to investigate DLO effects. It became clear that O-rings can remain leak-tight under static conditions even when material properties have already degraded considerably, especially when adhesion effects are encountered. As a feasible and reliable end-of-lifetime criterion for O-ring seals under static conditions should include a safety margin for slight dimensional changes, a modified leakage test involving a small and rapid partial decompression of the seal was introduced that enabled determining a more realistic but still conservative end-of-lifetime criterion for an EPDM seal.
The knowledge of transformation pathways and identification of transformation products (TPs) of veterinary drugs is important for animal health, food, and environmental matters. The active agent Monensin (MON) belongs to the ionophore antibiotics and is widely used as a veterinary drug against coccidiosis in broiler farming. However, no electrochemically (EC) generated TPs of MON have been described so far. In this study, the online coupling of EC and mass spectrometry (MS) was used for the generation of oxidative TPs. EC-conditions were optimized with respect to working electrode material, solvent, modifier, and potential polarity. Subsequent LC/HRMS (liquid chromatography/high resolution mass spectrometry) and MS/MS experiments were performed to identify the structures of derived TPs by a suspected target analysis. The obtained EC-results were compared to TPs observed in metabolism tests with microsomes and hydrolysis experiments of MON.
Five previously undescribed TPs of MON were identified in our EC/MS based study and one TP, which was already known from literature and found by a microsomal assay, could be confirmed.
Two and three further TPs were found as products in microsomal tests and following hydrolysis, respectively. We found decarboxylation, O-demethylation and acid-catalyzed ring-opening reactions to be the major mechanisms of MON transformation.