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- Gas sorption (3)
- Molecular modeling (3)
- Neutron diffraction (3)
- Residual stress (3)
- Swelling (3)
- Diffusion (2)
- Dilation (2)
- Poly(ether sulfones) (2)
- Simulation (2)
- Structural health monitoring (2)
Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (8)
- 8.5 Röntgenbildgebung (6)
- 5 Werkstofftechnik (3)
- 5.1 Mikrostruktur Design und Degradation (3)
- 9 Komponentensicherheit (3)
- 6 Materialchemie (2)
- 6.6 Physik und chemische Analytik der Polymere (2)
- 7 Bauwerkssicherheit (2)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (2)
- 9.4 Integrität von Schweißverbindungen (2)
Atomistic packing models have been created, which help to better understand the experimentally observed swelling behavior of glassy polysulfone and poly (ether sulfone), under CO2 gas pressures up to 50 bar at 308 K. The experimental characterization includes the measurement of the time-dependent volume dilation of the polymer samples after a pressure step and the determination of the corresponding gas concentrations by gravimetric gas-sorption measurements. The models obtained by force-field-based molecular mechanics and molecular dynamics methods allow a detailed atomistic analysis of representative swelling states of polymer/gas systems, with respect to the dilation of the matrix. Also, changes of free volume distribution and backbone mobility are accessible. The behavior of gas molecules in unswollen and swollen polymer matrices is characterized in terms of sorption, diffusion, and plasticization.
Mass spectrometry is applied as a tool for the elucidation of molecular structures. This premises that gas-phase structures reflect the original geometry of the analytes, while it requires a thorough understanding and investigation of the forces controlling and affecting the gas-phase structures. However, only little is known about conformational changes of oligonucleotides in the gas phase. In this study, a series of multiply charged DNA oligonucleotides (n¼15–40) has been subjected to a comprehensive tandem mass spectrometric study to unravel transitions between different ionic gas-phase structures. The nucleobase sequence and the chain length were varied to gain insights into their influence on the geometrical oligonucleotide organization. Altogether, 23 oligonucleotides were analyzed using collision-induced fragmentation. All sequences showed comparable correlation regarding the characteristic collision energy. This value that is also a measure for stability, strongly correlates with the net charge density of the precursor ions. With decreasing charge of the oligonucleotides, an increase in the fragmentation energy was observed. At a distinct charge density, a deviation from linearity was observed for all studied species, indicating a structural reorganization. To corroborate the proposed geometrical change, collisional cross-sections of the oligonucleotides at different charge states were determined using ion mobility-mass spectrometry. The results clearly indicate that an increase in charge density and thus Coulomb repulsion results in the transition from a folded, compact form to elongated structures of the precursor ions. Our data show this structural transition to depend mainly on the charge density, whereas sequence and size do not have an influence.
The analysis of the current state of fire statistics and data collection in Europe and other countries is needed to increase awareness of how fire incidents affect buildings and to support pan-European fire prevention and fire mitigation measures.
The terminology and data collected regarding fire incidents in buildings in the EU Member States were mapped to obtain meaningful datasets to determine common terminology, collection methodology, and data interpretation system. An extensive literature review showed that fire data collection systems have been instrumental in informing firefighting strategies, evidence-based planning, prevention, and educational programmes. Differences and similarities between fire data collection systems were also investigated. The amount and quality of the information in fire statistical recording systems appear to be influenced by the complexity and structure with which the data are collected. The analysis also examined the existing fire statistics in the EU Member States and a few other countries. Finally, a detailed investigation of the number of fires, fire deaths, and injuries from 2009 to 2018 in several countries was examined based on data from a report by CTIF. The trends showed differences attributable to the existing fire statistical practices in terms of terminology and data
collection, and interpretation. Part II proposes a common terminology for selected fire statistical variables. The results provide relevant information regarding fire safety at the European level and should be used to guide the development of more uniform fire statistics across Europe.
Despite their immense and rapidly increasing
importance as analytical tools or therapeutic drugs, the detailed
structural features of particular monoclonal antibodies are
widely unknown. Here, an antibody already in use for diagnostic
purposes and for molecular dosimetry studies in cancer therapy
with very high affinity and specificity for cisplatin-induced DNA
modifications was studied extensively. The molecular structure
and modifications as well as the antigen specificity were
investigated mainly by mass spectrometry. Using nano electrospray
ionization mass spectrometry, it was possible to characterize the antibody in its native state. Tandem-MS experiments not
only revealed specific fragments but also gave information on the molecular structure. The detailed primary structure was further
elucidated by proteolytic treatment with a selection of enzymes and high resolution tandem-MS. The data were validated by
comparison with known antibody sequences. Then, the complex glycan structures bound to the antibody were characterized in
all detail. The Fc-bound oligosaccharides were released enzymatically and studied by matrix-assisted laser desorption/ionization
mass spectrometry. Overall 16 different major glycan structures were identified. The binding specificity of the antibody was
investigated by applying synthetic single and double stranded DNA oligomers harboring distinct Pt adducts. The antibody−
antigen complexes were analyzed by mass spectrometry under native conditions. The stability of the complex with double
stranded DNA was also investigated.
According to the objectives of the research group 1498, this paper deals with degradation effects in concrete structures that are caused by cyclic flexural loading. The goal is to determine their influence on the fluid transport processes within the material on the basis of experimental results and numerical simulations. The overall question was, to which extent the ingress of externally supplied alkalis and subsequently an alkali-silica reaction are affected by such modifications in the microstructure. Degradation in the concrete microstructure is characterized by ultrasonic wave measurements as well as by microscopic crack analysis. Furthermore, experiments on the penetration behavior of water into the investigated materials were performed. The penetration behavior into predamaged concrete microstructures was examined by the classical Karsten tube experiment, nuclear magnetic resonance method, and time domain reflectometry techniques. In order to create an appropriate model of the material's degradation on the water transport, the Darcy law was applied to describe the flow in partially saturated concrete. Material degradation is taken into account by an effective permeability that is dependent on the state of degradation. This effective permeability is obtained by the micromechanical homogenisation of the flow in an Representative Elementary Volume (REV) with distributed ellipsoidal microcracks embedded in a porous medium. The data gained in the microscopic crack analysis is used as input for the micromechanical model. Finite element simulations for unsaturated flow using the micromechanical model were compared with the experimental results showing good qualitative and quantitative agreement.
High energy X-ray synchrotron diffraction is used to investigate the elastic anisotropy of the nickel-based superalloy IN718 produced by laser powder bed fusion (PBF-LB). This material is characterized by a columnar grain morphology with some crystallographic texture. The material is subjected to elastic loading to determine the diffraction elastic constants (DECs). Furthermore, the single-crystal elastic constants (SCEC) are refined from these experiments using different micromechanical models. The results show that each micromechanical model predicts a specific set of SCEC that well describes the elastic anisotropy of PBF-LB/IN718.
Explaining Deviatoric Residual Stresses in Aluminum Matrix Composites with Complex Microstructure
(2020)
The residual stresses in multiphase metal Matrix composites with both random planar-oriented short fibers and particles were studied by neutron diffraction and by a model based on the reformulation of classic Maxwell’s homogenization method. Contrary to common understanding and state-of-the-art models, we experimentally observed that randomly oriented phases possess non-hydrostatic residual stress. The recently developed modeling Approach allows calculating the residual stress in all phases of the composites. It rationalizes the presence of deviatoric stresses Accounting for the interaction of random oriented phases with fibers having preferential orientation.
This study provides an analysis on the fire safety of passengers and the fire protection of coaches and buses. A brief review of major bus fire incidents, an overview of current regulations in Europe, and their limitations are presented. The study finds that the current small-scale fire test methods described in UN ECE Reg No. 118 need to be replaced by test methods that can assess the reaction to fire of materials when exposed to ignition sources of varying sizes. To address these shortcomings, the study proposed an expert recommendation to update the material fire safety requirements and testing for buses. Additional measures are proposed, derived from objectives and strategies applied in other transport sectors, and can be tested through existing European and international standards, which are widely used by several industries. These measures aim to extend the time with tenable conditions for a safe evacuation in case of fire, reduce the degree of damage to buses, reduce the risk for fast and excessive thermal exposure on modern energy carriers needed for a more sustainable transport sector.