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排序方式: 共有785条查询结果,搜索用时 31 毫秒
81.
Elena Lopez Dorit Linaschke Birte Dresler Dr. Ines Dani Prof. Dr. Christoph Leyens Prof. Dr. Eckhard Beyer 《真空研究与实践》2011,23(6):12-16
Atmospheric pressure plasma‐chemical etching and deposition. Application in crystalline silicon photovoltaics. For industrial processing of wafer based crystalline silicon solar cells a variety of different technologies are applied. The combination of these requires a complex wafer handling; increasing not only investment costs, but also the risk of wafer breakage. Application of plasma technologies offers the possibility to manufacture crystalline silicon solar cells without any wet chemical or vacuum processes. At Fraunhofer IWS all etching steps necessary for the production of solar cells and the deposition of silicon nitride as passivation and anti‐reflection coating were demonstrated successfully using atmospheric pressure plasma technologies. 相似文献
82.
A general approach for the fabrication of nanoporous Pt-based multimetallic alloy nanowires is reported, which involves electrodeposition of corresponding precursor alloys into porous anodic alumina templates, followed by a mild dealloying process. Nanoporous ternary PtCoNi and PtCoAu as well as quaternary PtRuCoNi nanowires were successfully fabricated, and their microstructure and composition were examined by transmission electron microscopy. Electrochemical tests showed that these porous nanowires exhibit higher electrochemically active surface area and much improved durability compared to commercially available Pt black, and may find potential applications in electrocatalysis and electrochemical sensing. 相似文献
83.
Seung‐Mo Lee Vladislav Ischenko Eckhard Pippel Admir Masic Oussama Moutanabbir Peter Fratzl Mato Knez 《Advanced functional materials》2011,21(16):3047-3055
Transition metals incorporated into polymers lead to unusual or improved physical properties that significantly differ from those of purely organic polymers. A simple and practicable incorporation of diverse transition metals into any available polymer would make an important contribution to overcome some of the synthetic difficulties of metal‐polymer hybrid materials. Here, it is demonstrated that atomic layer deposition (ALD) can be a promising means to resolve some of those difficulties. It is found that even polytetrafluoroethylene (PTFE) with its great physical and chemical stability can be easily transformed into a transition metal–PTFE hybrid material simply by applying a metal‐oxide ALD process to PTFE. Upon metal incorporation into the PTFE, the molecular structure as well as mechanical properties (tensile behavior) of PTFE were observed to significantly change. For a better understanding of the changes to the material, experimental investigations using Raman spectroscopy, attenuated‐total‐reflection Fourier‐transform infrared spectroscopy, wide‐angle X‐ray diffraction, and energy‐dispersive X‐ray analysis were performed. In addition, with density functional theory calculations, potential bonding states of the incorporated metal into PTFE were modeled and predicted. The ALD‐based vapor‐phase approach for metal incorporation into a polymer could bring about rapid progress in the research area of metal–polymer hybrid materials. 相似文献
84.
85.
The evolution of the phase of the output radiation of free-electron laser amplifiers is investigated by means of a three-dimensional simulation code. The configuration employed consists of the propagation of a relativistic electron beam through a loss-free cylindrical waveguide in the presence of a helically symmetric wiggler and a uniform axial guide magnetic field. The analysis is fully three dimensional, and a set of model equations is discussed which describes the coupling between an ensemble of electrons and the radiation field of either the TE or TM modes. The model equations are solved numerically, and the output phase is studied with respect to variations in either frequency or electron beam energy. The output phase is found to depend sensitively on the wave frequency within the unstable bandwidth. In addition, the phase stability of the output radiation is discussed as a function of beam energy. Finally, the evolution of the phase for tapered wiggler free-electron lasers is studied. 相似文献
86.
The ring-opening polymerization of ε-caprolactone was investigated by means of the Mettler RC1 reaction calorimeter. In the range of small and medium monomer conversions this method can successfully be used for the determination of the course of the bulk polymerizations. The experimental results obtained by calorimetric and gravimetric method, respectively, are compared and the course of the polymerization is discussed in dependence on the reaction parameters (initiator, temperature). 相似文献
87.
Eckhard Boles Friedrich K. Zimmermann Jürgen Heinisch 《Yeast (Chichester, England)》1993,9(7):761-770
The glycolytic pathway in Saccharomyces cerevisiae is activated by fermentable sugars at several steps. Mutants with deletions of genes coding for enzymes of the upper part of glycolysis were used to characterize the triggering mechanisms. Synthesis of fructose-2,6-bisphophate is catalysed by two 6-phosphofructo-2-kinase isoenzymes, one of which is activated by fermentable sugars while synthesis of the second enzyme is induced (Kretschmer and Fraenkel, 1991). Increase in the level of fructose-2, 6-bisphosphate is demonstrated to depend on an internal metabolite upstream of the phosphoglucose isomerase reaction. The signalling process correlates with distinct temporal changes in the concentration of glucose-6-phosphate but not with its absolute level, indicating an adaptational mechanism. It is independent of the uptake and phosphorylation systems used by different sugars. Interestingly, this increase, although delayed, could also be observed in strains lacking the rapid cAMP increase after sugar addition which is thought to be responsible for the activating process. Synthesis of glucose-6-P and fructose-6-P is needed for the complete induction of pyruvate kinase and inactivation of fructose-1,6-bisphosphatase. On the other hand, induction of pyruvate decarboxylase depends mainly on a signal in the lower part of glycolysis. 相似文献
88.
89.
PR Freund TA Bowdle KL Posner ED Kharasch VD Burkhart 《Canadian Metallurgical Quarterly》1997,87(5):1044-1049
BACKGROUND: Anesthetic drug expenditures have been a focus of cost-containment efforts. The aim of this study was to determine whether expenditures for neuromuscular-blocking agents could be reduced without compromising outcome, and to determine whether such a cost-effective pattern of neuromuscular blocker use could be sustained. METHODS: Education, practice guidelines, and paperwork barriers were used to persuade anesthesiologists to substitute low-cost neuromuscular-blocking drugs (pancuronium or a metocurine-pancuronium combination) for a more costly neuromuscular-blocking drug (vecuronium). Neuromuscular-blocking drug use in all patients during a historical control period (6 months; n = 4,804) was compared with that during two consecutive 1-yr periods of intervention (n = 9,761/n = 10,695). Expenditures for vecuronium and for all neuromuscular-blocking drugs were compared for the control and intervention periods. The rate of complications related to neuromuscular-blocking drugs was determined by an ongoing continuous quality improvement program. RESULTS: Vecuronium use decreased by 76% during the first and second yr of intervention, compared with the historical period (P < 0.01). The cost of neuromuscular-blocking drugs decreased by 31% (P < 0.01) and 47% (P < 0.01) for the first and second yr, respectively. The complication rate related to neuromuscular-blocking drugs was 0.081% in the historical period and 0.11% and 0.093% during the intervention periods (P = 0.29 and 0.41). CONCLUSION: Practice guidelines, education, and paperwork barriers used together substantially reduced the expenditures for neuromuscular-blocking drugs for 2 yr without adversely affecting clinical outcome. 相似文献
90.
L. Zahn R. Freund K. Hoppe K. L. Pisarchuk W. Augustin 《Molecular nutrition & food research》1991,35(6):581-590
Aimed to the construction of a prediction equation for estimations of lipid content from animal water content body composition was determined by whole body analysis of male rats (1) given access, ad libitum, to a commercial standard diet (n = 144; ranging from 60 to 600 g in weight, and from the 4th to the 34th week of age), and (2) showing striking variations with regard to nutritional state, dietary history, enlarged fat deposition, genetic origin, intestinal microbial status, and advanced age (n = 75). It was shown that a unique coefficient of water content in lipid-free body mass does not exist. The results of statistical analysis for the grouped values of percentage body dry matter (x) and percentage body lipid (y) indicate that the latter can be estimated accurately from body water content directly determined by the use of the quadratic regression equation y = ?0.2864×+0.01615 x2 with a standard deviation of the procedure sy = ±1.40. This prediction equation is valid for a wide developmental span even under highly different experimental states. Differences between the calculated body lipid contents vs. analytically determined values are smaller than by using a linear regression equation or coefficient(s) of hydration of lipid-free body mass. 相似文献