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81.
Weirich Sebastian; Hoffmann Ferdinand; Mei?ner Lucia; Heinz Andreas; Bengner Thomas 《Canadian Metallurgical Quarterly》2011,25(6):806
Objective: It has been suggested that women have a better face recognition memory than men. Here we analyzed whether this advantage depends on a better encoding or consolidation of information and if the advantage is visible during short-term memory (STM), only, or whether it also remains evident in long-term memory (LTM). Method: We tested short- and long-term face recognition memory in 36 nonclinical participants (19 women). We varied the duration of item presentation (1, 5, and 10 s), the time of testing (immediately after the study phase, 1 hr, and 24 hr later), and the possibility to reencode items (none, immediately after the study phase, after 1 hr). Results: Women showed better overall face recognition memory than men (ηp2 = .15, p 相似文献
82.
Marcel Müri Bernd Gotsmann Yann Leroux Marius Trouwborst Emanuel Lörtscher Heike Riel Marcel Mayor 《Advanced functional materials》2011,21(19):3706-3714
Due to the increasing importance of modified electrodes for many applications in nanotechnology, including molecular electronics, bioelectronics, and sensors, there is a need to find ways to chemically attach suitable molecular films onto the electrodes. Combining the electroreduction of aryl diazonium salts with the Sonogashira cross‐coupling reaction, a new modular technique to modify electrodes is presented. The new technique allows a wide range of functional groups to be introduced onto electrode surfaces with high surface coverage by the functional subunit. Various organic subunits, including redox chromophores, are successfully attached to platinum electrodes. The corresponding films are characterized using cyclic voltammetry, X‐ray photoelectron spectroscopy, atomic force microscopy, and contact‐angle measurements. The electroreduction of diazonium salts is successfully achieved on a broad variety of conducting and semiconducting surfaces, which shows that the technique is applicable to a broad variety of substrates. 相似文献
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Bernd Oberwinkler 《Materials Science and Engineering: A》2011,528(18):5983-5992
Ti-6Al-4V is a commonly used titanium base alloy in aerospace applications. The increasing demand for damage-tolerant designs of such components necessitates a detailed knowledge of its crack growth behavior. The aim of this research was the characterization and phenomenological modeling of long crack growth behavior with respect to microstructure and stress ratio. Therefore, the long crack propagation was characterized for eight different heat treatment conditions and four stress ratios. For comparison, physically short crack growth tests were also performed. The long crack growth threshold was found to be dominated by roughness-induced crack closure, and the fracture surface roughness is controlled by the primary α-grain size. The reason for this correlation is a near-threshold crack propagation mode, which is dominated by the transcrystalline fracture of α-grains. This correlation was used to model the crack growth threshold with respect to microstructure. A linear relation was determined between the stress ratio and the threshold value, which was also found in this approach. Further presented models cover the crack growth behavior in the near-threshold (Stage I) and mid-growth rate regions (Stage II). 相似文献
86.
Composite materials with vibrations damping qualities can be made of two steel sheets enclosing a viscoelastic plasticcorelayer. These sandwich sheets often need to be formed. Material parameters are determined to describe the forming process. Based on these parameters, pilot studies are carried out in order to develop recommendations for forming this class of material. 相似文献
87.
James E. Hoffmann 《Metallurgical and Materials Transactions B》2012,43(3):431-439
With the continuous reduction in the availability of extractive metallurgical curricula in colleges and universities, the concern has in part been from where will the next generation of extractive metallurgists come? One objective of this article is to emphasize the fact that extractive metallurgy is, in fact, one of many areas of chemical engineering technology. Thus, although the extractive metallurgist may have disappeared in name, its activity is alive and well, subsumed in the field of chemical engineering. One goal of this lecture is to demonstrate the applicability of chemical engineering principles to what is typically considered ??the field of extractive metallurgy.?? Two processes will be described that have supplanted typical pyrometallurgical fire refining of precious metals, particularly silver. The origins of fire refining can be traced back to biblical times. There are numerous references to it in the old testament: Ezekiel 22:20, ??As men gather silver and bronze and iron and lead and tin into a furnace to blow the fire upon it in order melt it??; Jeremiah 6:29, ??The bellows blow fiercely; the lead is consumed by the fire; in vain the refining goes on??; and Malachi 3:2 (The Oxford Annotated Bible with the Apocrypha), ??For he is like a refiners fire.?? Many references to it will also be found in ??De Re Metallurgica?? and as well in Lazarus Ercker??s 1574 Manual ??Treatise on Ores and Refining.?? Today, fire refining has been improved greatly by innovative furnace design, new fluxing technologies, and the improved use of oxygen. However, fundamentally, the process chemistry has not changed much in the last millennium. Illustrations of hydrometallurgical processing of silver-bearing inputs will be provided by the treatment of sulfated silver-bearing materials and chlorinated slimes. The first of these technologies will be described briefly as practiced by the Phelps Dodge Refining Corporation for several years. The second, the treatment of silver chloride-bearing inputs, will be described in detail to demonstrate how typical chemical engineering unit process and unit operations have supplanted classic smelting and fire refining techniques. The Kennecott Copper Company, which has operated a hydrometallurgical circuit successfully for the recovery of high-purity silver from the slimes wet chlorination residue, has permitted me to provide some operation information and results using the technology. Both Phelps Dodge and Kennecott should be recognized for their forward-looking attitude in undertaking the conversion of conceptual chemistry into successful, full-scale plants. The process as employed at Phelps Dodge is discussed at length in reference (J.E. Hoffmann and B. Wesstrom: Hydrometallurgy, 1994, vol. 94, pp. 69?C105). 相似文献
88.
Analysis of the Stakeholder Engagement in the Deployment of Renewables and Smart Grid Technologies 下载免费PDF全文
The implementation of higher shares of renewables in a global energy mix has to be accompanied by simultaneous deployment of enabling smart grid technologies (SGTs). This combination will inevitably lead to a revolutionary change in a conventional energy system, particularly, the shifting role of consumers to prosumers. But resistance may arise from such a dramatic shift, since it is associated with high uncertainty in conjunction with increasing responsibilities of all stakeholders, the urgent need of effective control, and the development of a process. To ensure the positive influence, coherent actions of all players, and appropriate treatment of the spots of resistance, the analysis of the interplay between key stakeholders has been done. The paper introduces the framework for stakeholders' analysis, applies it on the European Union (EU) example, and provides recommendations to reduce the resistance of SGTs deployment. 相似文献
89.
Untersuchungen zur Dauerfestigkeit carbonitrierter Proben aus den Einsatzstählen 18CrNiMo7‐6und 20MnCr5 下载免费PDF全文
C. Stöberl H. Bomas B. Clausen F. Hoffmann H.‐W. Zoch 《Materialwissenschaft und Werkstofftechnik》2015,46(6):533-549
The endurance limit of carbonitrided specimens of 18CrNiMo7‐6 and 20MnCr5 case hardening steels were examined under bending conditions. Four variants were manufactured differing in heat treatment and surface conditions. Besides conventional gas carburised variants, carbonitrided specimens with a low and a raised nitrogen content of 0.2 and 0.45% at the surface as well as a carbonitrided and ground variant were examined. The specimens were tested with stress ratios R = –1 and 0. Depending on the nitrogen content cyclic loading evokes compressive residual stresses at the specimens' surfaces, caused by elastic‐plastic deformation. Specimens of the ground variant show additionally a decrease of the residual austenite content when cycled. The induced compressive residual stresses are substantially responsible for high endurance limits at both stress ratios and are the key for understanding the beneficial effect of carbonitriding in this regard. 相似文献
90.