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841.
The strength of glass fiber reinforced epoxy resins can be significantly reduced under exposure to moisture. Besides other factors, the interface between fiber and matrix plays an important role. It is responsible for a proper load transfer between fibers and matrix by coupling effects and significantly affects the moisture behavior of the composite. In the present study, glass fibers were treated with different sizes under defined conditions and embedded in three epoxy matrix systems. The composites were exposed to different moisture conditions. The change of the shear and impact behavior due to moisture was determined. It will be shown that the composites with coupling agent treated fibers are significantly more resistant to moisture than composites with poor fiber/matrix adhesion. Furthermore, it will be shown that also the binder plays an important role if the material is subjected to moisture. 相似文献
842.
Ulrich Teipel Hartmut Krber Horst H. Krause 《Propellants, Explosives, Pyrotechnics》2001,26(4):168-173
A new field of applications of compressed gases is the formation of solid particles with well‐defined properties, e.g. the particle size, the particle size distribution, the particle shape, the specific surface area and free of solvent inclusions. It is possible to process moderately solids like energetic materials which are difficult to comminute due to their sensitivity to mechanical or thermal stress. The characteristics of compressed gases allow to vary the morphology of solid particles in a wide range. A pilot plant is presented, which has been built to prepare fine particles by the Rapid Expansion of Supercritical Solutions (RESS process) and Precipitation by a Compressed Fluid Antisolvent (PCA process). In this contribution the micronization of different energetic materials by the RESS and PCA processes will be under investigation. 相似文献
843.
In this paper, we review the application of the electrophoretic deposition (EPD) technique in the fabrication of fibre reinforced composites, with particular emphasis on composites with glass and ceramic matrices containing metallic or ceramic fibre fabric reinforcement. The review covers research published in the last 10 years. EPD has been used to infiltrate preforms with tight fibre weave architectures using different nano‐sized ceramic particles, including silica and boehmite sols, as well as dual‐component sols of mullite composition. The principles of the EPD technique are briefly explained and various factors affecting the EPD behaviour of ceramic sols and their optimisation to obtain high infiltration of the fibre preforms are considered. Overall, the analysis of the published data and our own results demonstrate that EPD, being simple and inexpensive, provides an attractive alternative for ceramic infiltration and coating of fiber fabrics, even if they exhibit tight fibre weave architectures. 相似文献
844.
845.
Specific differences between the acyl composition of lipids on the helminthParatenuisentis ambiguus and its host eel, as shown previously, prompted us to study the lipid metabolism in this intestinal fish parasite. Adults
and larvae ofP. ambiguus were fed various lipid precursors, e.g., fatty acids, long-chain alcohols and 1-O-alkylglycerols, which may occur as common nutrients of intestinal parasites. Incorporation of [1-14C]palmitic acid into neutral and polar lipids was found to be similar under aerobic and near-anaerobic conditions. In adult
parasites maintained in culture medium supplemented with glucose, [1-14C]palmitic acid was incorporated mainly into triacylglycerols and phosphatidylcholines, whereas [1-14C]oleic acid was incorporated preferentially into triacylglycerols. In fasted adults, as well as in larvae, [1-14C]oleic acid was mainly transferred to phosphatidylcholines. Lipolytic activity was detected in adult parasites that had been
incubated with radioactive trioleoylglycerol. [1-14C]Hexadecan-1-ol was oxidized inP. ambiguus at a high rate to labeled palmitic acid, which was incorporated into various lipid classes ofP. ambiguus. Small but significant proportions of radioactivity from hexadecan-1-ol were incorporated into ether glycerolipids of the
parasite. A more direct precursor in ether glycerolipid metabolism, i.e.,rac-1-O-[1′-14C] hexadecylglycerol, was incorporated into alkyl and 1′-alkenyl moieties of choline and etha-nolamine etherglycerophospholipids
ofP. ambiguus in high yield. High proportions of labeled diacylglycerols, triacylglycerols and steryl esters were detected in surface lipids
as well as lipid extracts of the culture media after incubation ofP. ambiguus with [1-14C]palmitic or [1-14C]oleic acids. The results suggest that palmitic acid and oleic acid are incorporated into neutral and polar lipids ofP. ambiguus maintained in glucose medium quite differently with oleic acid showing a strong preference for triacylglycerols. However,
the incorporation of palmitic acid in glucose-fed parasites was similar to that of oleic acid in fasted parasites, as well
as in larvae. This may be explained by partial fatty acid depletion in fasted worms and rapid cell division in larvae, respectively. 相似文献
846.
An analysis method is developed to test the operational performance of a horizontal axis wind turbines. The rotor is constrained to the torque–speed characteristic of the coupled generator. Therefore, the operational conditions are realized by matching the torque generated by the turbine over a selected range of incoming wind velocity to that needed to rotate the generator. The backbone of the analysis method is a combination of Schmitz' and blade element momentum (BEM) theories. The torque matching is achieved by gradient‐based optimization method, which finds correct wind speed at a given rotational speed of the rotor. The combination of Schmitz and BEM serves to exclude the BEM iterations for the calculation of interference factors. Instead, the relative angle is found iteratively along the span. The profile and tip losses, which are empirical, are included in the analysis. Hence, the torque at a given wind speed and rotational speed can be calculated by integrating semi‐analytical equations along the blade span. The torque calculation method is computationally cheap and therefore allows many iterations needed during torque matching. The developed analysis method is verified experimentally by testing the output power and rotational speed of an existing wind turbine model in the wind tunnel. The generator's torque rotational speed characteristic is found by a separate experimental set‐up. Comparison of experiments with the results of the analysis method shows a good agreement. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
847.
Nanocrystalline TiO2 with densities higher than 99% of rutile has been deformed in compression without fracture at temperatures between 600° and 800°C. The total strains exceed 0.6 at strain rates as high as 10−3 s−1 . The original average grain size of 40 nm increases during the creep deformation to final values in the range of 120 to 1000 nm depending on the temperature and total deformation. The stress exponent of the strain rate, n , is approximately 3 and the grain size dependence is d − q with q in the range of 1 to 1.5. It is concluded that the creep deformation occurs by an interface reaction controlled mechanism. 相似文献
848.
Synthetic MUC1 Antitumor Vaccine with Incorporated 2,3‐Sialyl‐T Carbohydrate Antigen Inducing Strong Immune Responses with Isotype Specificity
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David Straßburger Markus Glaffig Natascha Stergiou Sabrina Bialas Prof. Dr. Pol Besenius Prof. Dr. Edgar Schmitt Prof. Dr. Horst Kunz 《Chembiochem : a European journal of chemical biology》2018,19(11):1142-1146
The endothelial glycoprotein MUC1 is known to underlie alterations in cancer by means of aberrant glycosylation accompanied by changes in morphology. The heavily shortened glycans induce a collapse of the peptide backbone and enable accessibility of the latter to immune cells, rendering it a tumor‐associated antigen. Synthetic vaccines based on MUC1 tandem repeat motifs, comprising tumor‐associated 2,3‐sialyl‐T antigen, conjugated to the immunostimulating tetanus toxoid, are reported herein. Immunization with these vaccines in a simple water/oil emulsion produced a strong immune response in mice to which stimulation with complete Freund's adjuvant (CFA) was not superior. In both cases, high levels of IgG1 and IgG2a/b were induced in C57BL/6 mice. Additional glycosylation in the immunodominant PDTRP domain led to improved binding of the induced antisera to MCF‐7 breast tumor cells, compared with that of the monoglycosylated peptide vaccine. 相似文献
849.
Andreas D. Stricker Stephan Mettler Heinrich Wolf Markus Mergens Wolfgang Wilkening Horst Gieser Wolfgang Fichtner 《Microelectronics Reliability》1999,39(11):1563
The design of ESD (electro-static discharge) protection structures can be significantly shortened by using thermo-electrical device simulations. In many cases simulation results predict the performance of new designs enough accurate which makes it unnecessary to go through the whole manufacturing process of test chips. More important, however, they allow the designer to gain additional insight into a problem by examining device-internal parameters that are not obtainable through measurements, such as current densities, the electric field and the lattice temperature. In this article we investigate and optimize a p-base type npn-transistor with a vertical and a lateral operation mode. Based on the TCAD tool chain, we develop a methodology to simulate the transient switching behavior, the avalanche breakdown and the snapback holding voltages of the device. To validate our design methodology we implemented the evaluated devices on a real test chip which has also been used to gain the needed data for the calibration of the simulators. Thus we are able to compare simulation and measurements and found the simulated voltages to closely match values obtained in measurements. In addition we extracted a set of parameters for a compact circuit model describing the device under various ESD stress types. 相似文献
850.
Horst Rempp Oliver Thalau Andrea Scorzoni Gerard Ghilbaudo Emanuel Vincent Sean Minehane 《Microelectronics Reliability》1999,39(5):661
Electromigration and oxide time dependent dielectric breakdown simulations based on library elements of a 0.35 μm CMOS technology have been performed. In the case of hot carrier degradation simulations as well as experiments using 99-stage ring oscillators of the same 0.35 μm CMOS technology have been carried out and compared. The frequency behaviour as a function of supply voltage and temperature has been investigated. Relaxation effects on the ring oscillators have been found. These effects are not covered by the reliability simulation tool. In a certain region of supply voltage and operation time the results of simulations could be confirmed by experiments. In all other cases the measured frequency degradation was smaller than the simulated degradation. 相似文献