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排序方式: 共有97条查询结果,搜索用时 31 毫秒
1.
H. W. Wenz W. J. Lichtenberg H. Katterwe 《Fresenius' Journal of Analytical Chemistry》1991,341(3-4):155-165
Summary When a shot is fired, the projectile and the cartridge case are released from the weapon, as well as components of the priming charge and propellant, the so-called powder-gunshot residues. In order to solve firearm offences, it is therefore very important to determine the topography of trace-bearing areas on the bullet and the cartridge case, as well as the chemical composition of gunshot residue particles. Gunshot residue particles are made visible with the scanning electron microscope (SEM) and are analysed by means of energy-dispersive X-ray spectroscopy (EDXS) and lately also by means of wavelength-dispersive X-ray spectroscopy (WDXS). In addition to this, analyses of these particles are displayed by means of Auger electron spectroscopy (AES) and secondary ion mass spectroscopy (SIMS) and depth profiles are prepared. To determine the local distributions of gunshot residue elements with regard to their quantity, the direct Zeeman atomic absorption spectroscopy (DZ-AAS) is employed. Besides the determination of the chemical composition, the topography of the trace-bearing areas on the bullet and cartridge case plays an important part. For the detection of these surfaces, light optical and electron-optical methods are employed. Moreover, the use of opto-electronical testing systems has been attracting more and more attention recently. 相似文献
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Two-stage Off-Gel isoelectric focusing: protein followed by peptide fractionation and application to proteome analysis of human plasma 总被引:1,自引:0,他引:1
Heller M Michel PE Morier P Crettaz D Wenz C Tissot JD Reymond F Rossier JS 《Electrophoresis》2005,26(6):1174-1188
This paper presents the recently introduced Off-Gel electrophoresis (OGE) technology as a versatile tool to reproducibly fractionate intact proteins and peptides into discrete liquid fractions. The coupling of two stages of OGE, i.e., the separation of intact proteins in a first-stage followed by fractionation of peptides derived from each protein fraction after proteolysis in a second stage, results in an array of 15 x 15 fractions that are directly amenable to additional peptide fractionation like reverse-phase liquid chromatography (RPC). The analysis of all second-stage peptide fractions from only the first-stage protein fraction representing pH 5.0 -5.15 by on-line reverse-phase LC-tandem mass spectrometry resulted in the identification of 53 proteins (337 peptides), of which 10 were on different immunoglobulin (Ig) chains, with an input of only 1.5 mg human blood plasma proteins. Increasing the protein load to approximately 12 mg increased the number of identified proteins in the same protein fraction to 73 proteins (449 peptides), of which 15 were Ig-related. Immunodepletion of six of the most abundant proteins (albumin, transferrin, haptoglobin, IgG, IgA, and alpha-1-antitrypsin) prior to first-stage OGE with an input of 1.5 mg of protein (equivalent to approximately 10 mg nondepleted plasma) resulted in the identification of 81 proteins (660 peptides), of which three were still Ig fragments. The pI-based separation of peptides appears to be nonuniform based on the theoretically determined pI values of identified peptides. This observation specifically accounts for the neutral zone (pI 5-8) and can be accounted for by the physicochemical properties of the peptides given by their amino acid composition. The power of OGE separation of proteins and peptides is discussed with a focus on the use of the knowledge about the pI of proteins and peptides that assist the validation of correct identifications together with the retention time of peptides on RPC. 相似文献
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Dennis Schnfeld Dilip Chalissery Franziska Wenz Marius Specht Chris Eberl Thorsten Pretsch 《Molecules (Basel, Switzerland)》2021,26(3)
For soft robotics and programmable metamaterials, novel approaches are required enabling the design of highly integrated thermoresponsive actuating systems. In the concept presented here, the necessary functional component was obtained by polymer syntheses. First, poly(1,10-decylene adipate) diol (PDA) with a number average molecular weight Mn of 3290 g·mol−1 was synthesized from 1,10-decanediol and adipic acid. Afterward, the PDA was brought to reaction with 4,4′-diphenylmethane diisocyanate and 1,4-butanediol. The resulting polyester urethane (PEU) was processed to the filament, and samples were additively manufactured by fused-filament fabrication. After thermomechanical treatment, the PEU reliably actuated under stress-free conditions by expanding on cooling and shrinking on heating with a maximum thermoreversible strain of 16.1%. Actuation stabilized at 12.2%, as verified in a measurement comprising 100 heating-cooling cycles. By adding an actuator element to a gripper system, a hen’s egg could be picked up, safely transported and deposited. Finally, one actuator element each was built into two types of unit cells for programmable materials, thus enabling the design of temperature-dependent behavior. The approaches are expected to open up new opportunities, e.g., in the fields of soft robotics and shape morphing. 相似文献
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Currently, feature annotation remains one of the main challenges in untargeted metabolomics. In this context, the information provided by high-resolution mass spectrometry (HRMS) in addition to accurate mass can improve the quality of metabolite annotation, and MS/MS fragmentation patterns are widely used. Accurate mass and a separation index, such as retention time or effective mobility (μeff), in chromatographic and electrophoretic approaches, respectively, must be used for unequivocal metabolite identification. The possibility of measuring collision cross-section (CCS) values by using ion mobility (IM) is becoming increasingly popular in metabolomic studies thanks to the new generation of IM mass spectrometers. Based on their similar separation mechanisms involving electric field and the size of the compounds, the complementarity of DTCCSN2 and μeff needs to be evaluated. In this study, a comparison of DTCCSN2 and μeff was achieved in the context of feature identification ability in untargeted metabolomics by capillary zone electrophoresis (CZE) coupled with HRMS. This study confirms the high correlation of DTCCSN2 with the mass of the studied metabolites as well as the orthogonality between accurate mass and μeff, making this combination particularly interesting for the identification of several endogenous metabolites. The use of IM-MS remains of great interest for facilitating the annotation of neutral metabolites present in the electroosmotic flow (EOF) that are poorly or not separated by CZE. 相似文献
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Felix Burkhardt Carl G. Schirmeister Christian Wesemann Massimo Nutini Stefano Pieralli Erik H. Licht Marc Metzger Frederik Wenz Rolf Mülhaupt Benedikt C. Spies 《Molecules (Basel, Switzerland)》2020,25(24)
A polyolefin with certified biocompatibility according to USP class VI was used by our group as feedstock for filament-based 3D printing to meet the highest medical standards in order to print personal protective equipment for our university hospital during the ongoing pandemic. Besides the chemical resistance and durability, as well as the ability to withstand steam sterilization, this polypropylene (PP) copolymer is characterized by its high purity, as achieved by highly efficient and selective catalytic polymerization. As the PP copolymer is suited to be printed with all common printers in fused filament fabrication (FFF), it offers an eco-friendly cost–benefit ratio, even for large-scale production. In addition, a digital workflow was established focusing on common desktop FFF printers in the medical sector. It comprises the simulation-based optimization of personalized print objects, considering the inherent material properties such as warping tendency, through to validation of the process chain by 3D scanning, sterilization, and biocompatibility analysis of the printed part. This combination of digital data processing and 3D printing with a sustainable and medically certified material showed great promise in establishing decentralized additive manufacturing in everyday hospital life to meet peaks in demand, supply bottlenecks, and enhanced personalized patient treatment. 相似文献
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