Filtern
Erscheinungsjahr
Dokumenttyp
Sprache
- Englisch (20) (entfernen)
Schlagworte
- Acoustic levitation (2)
- Mass spectrometry (2)
- 16S amplicons (1)
- Adhesion (1)
- Adhesives and adhesive tapes (1)
- Aeolian (1)
- Amorphization (1)
- Bodélé Depression (1)
- Bonding strength (1)
- Certified reference material (1)
- Chad (1)
- Collision induced dissociation (CID) (1)
- Crystallization (1)
- Cyclic voltammetry (1)
- Desert soil (1)
- Deserts (1)
- Double strands (1)
- Electrochromic device (1)
- Electrochromism (1)
- Electrospray (1)
- Eukaryota (1)
- Femtosecond laser (1)
- High throughput sequencing (1)
- Intercontinental dust (1)
- Ion mobility spectrometry (1)
- Laser ablation (1)
- Locked nucleic acids (1)
- Metagenomics (1)
- Metallo-supramolecular polyelectrolytes (1)
- Multiple-sample bonding (1)
- Multiple-sample testing (1)
- Ni-base superalloy (1)
- Nitrides (1)
- Oligonucleotide fragmentation (1)
- Optical properties (1)
- Physical vapour desposition (1)
- Protein analysis (1)
- Republic of Chad (1)
- Scratch test (1)
- Silicon (1)
- Spectroscopic imaging ellipsometry (1)
- Standardisation (1)
- Structural properties (1)
- Test methods (1)
- Thermo-mechanical fatigue (1)
- Vanadium oxide (1)
- Wind erosion (1)
- XAFS (1)
Organisationseinheit der BAM
Paper des Monats
- ja (1)
Adhesion and other mechanical behaviour of coatings is at present routinely tested in industry and research organisations using the scratch test. The test has been the subject of a European Standard prEN 1071-3:2000 established by the European Standards Committee CEN TC184 WG5. A previous European project on the development and validation of test methods for thin hard coatings—FASTE—revealed that uncertainties in the Rockwell C stylus tip shape represent a major source of error for the scratch-test method. Therefore a follow-up project—REMAST—was started to develop and certify a reference material as a quality control tool for the testing and qualification of scratch-test instruments. In addition, a considerable effort was devoted to improve the scratch stylus manufacturing process. This paper presents the results of the REMAST project. During a feasibility study, two candidate materials—titanium nitride (TiN) and diamond-like carbon (DLC) coatings both on high speed steel substrates—were evaluated. Because of the lower sensitivity to styli tip shape variations and higher data scatter observed for the TiN coating, DLC was chosen as the reference material to be certified. One thousand samples were produced, as well as qualified styli to carry out the certification campaign, including homogeneity and stability testing. Nine independent laboratories were involved in the certification exercise, and the data were statistically analysed to obtain the certified critical load values and their uncertainty ranges. A certified reference material BCR-692 is available for verification purposes. This presents three repeatable failure events at certified critical load intervals and can provide a good indication of overall scratch-test instrument performance, including stylus condition and calibration. It is also useful as a diagnostic tool, providing a means of sensitive monitoring of machine and stylus performance over extended periods. Considerable improvement of the quality of scratch styli was achieved by the strict control of all manufacturing steps.
DNA and locked nucleic acid (LNA) were characterized as single strands, as well as double stranded DNA-DNA duplexes and DNA-LNA hybrids using tandem mass spectrometry with collision-induced dissociation. Additionally, ion mobility spectrometry was carried out on selected species. Oligonucleotide duplexes of different sequences – bearing mismatch positions and abasic sites of complementary DNA 15-mers – were investigated to unravel general trends in their stability in the gas phase. Single stranded LNA oligonucleotides were also investigated with respect to their gas phase behavior and fragmentation upon collision-induced dissociation. In contrast to the collision-induced dissociation of DNA, almost no base loss was observed for LNAs. Here, backbone cleavages were the dominant dissociation pathways. This finding was further underlined by the need for higher activation energies. Base losses from the LNA strand were also absent in fragmentation experiments of the investigated DNA-LNA hybrid duplexes. While DNA-DNA duplexes dissociated easily into single stranded fragments, the high stability of DNA-LNA hybrids resulted in predominant fragmentation of the DNA part rather than the LNA, while base losses were only observed from the DNA single strand of the hybrid.
Decorative hard coatings: interdependence of optical, stoichiometric and structural properties
(1993)
Decorative optical coatings
(1994)
Three effects have been observed in wet-thermally grown structures under bombardement with energetic 15N ions: (1) Out-diffusion of H from the SiO2/Si system through the surface, (2) Accumulation of H at the SiO2/Si interface, (3) Changes in the optical fingerprint spectra of Ψ and Δ in dependence on λ (wavelength) obtained by ellipsometric measurements.
Flexible electrochromic devices (ECDs) based on Fe(II)-metallo-supramolecular polyelectrolytes (Fe-MEPE) and vanadium oxide are studied in operando by means of x-ray absorption fine structure (XAFS) spectroscopy. The ECDs are blue-purple in the colored state at 0.0 V and become light yellow when a voltage of 1.6 V is applied. The XAFS studies at the K-edge of Fe(II) reveals that the absorption edge is shifted toward higher energies by 1.8 eV in the transparent state. Comparison of two different ECDs and different charge cycles demonstrates the reversibility and repeatability of the process. We attribute the shift to a charge transfer and a change of oxidation state of the ions from Fe2+ to Fe3+. The transition is not accompanied by a noticeable structural change of the octahedral coordination geometry as confirmed by analysis of the extended x-ray absorption fine structure (EXAFS) data. (C) 2015 Elsevier B.V. All rights reserved.
The composition of acoustically levitated droplets was probed by a novel combination of mid-IR laser evaporation and subsequent postionization via secondary electrospray ionization. The combination of microliter samples and subnanoliter sampling provided time-resolved interrogation of droplets and allowed for a kinetic investigation of the laser-induced release of the analyte, which was found to strongly depend on the analytes. The observed substancespecific delayed release of the analytes permitted baseline-separated discrimination of the analytes, ideal for the study of complex samples.
The additionally applied postionization scheme was found to enable efficient detection of small volatile compounds as well as peptides. The detection of small molecules and peptides occurred under very different sampling geometries, pointing to two distinct underlying ionization mechanisms. Overall, our results suggest that the experimental setup presented in this study can serve as a widely applicable platform to study chemical reactions in acoustically levitated droplets as model reactors.