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排序方式: 共有173条查询结果,搜索用时 15 毫秒
71.
Doris Pospiech Liane Hußler Kathrin Eckstein Dieter Jehnichen Antje Gottwald Petra Ptschke 《Macromolecular Symposia》2000,149(1):219-224
One mechanism for compatibilization of immiscible polymer blends is adding block copolymers (BCP) that consist of segments chemically comparable to the parent homopolymers in the blend. BCP do both, emulsify the disperse phase to give smaller particles as well as increase the interfacial adhesion between the phases. The influence of segmented BCP in blends of immiscible high‐performance polymers was investigated systematically by variation of the flexibility of the BCP segments. It was shown that the stiffness of the second segment in polysulfone (PSU) block copolymers as well as the PSU segment molecular weight determine the intermixing between the BCP and the PSU matrix. 相似文献
72.
S. Fiechter J. Eckstein W. J. P. Van Enckevort J. J. M. Binsma 《Crystal Research and Technology》1983,18(7):881-887
Single crystals of Cu6PS5Hal (Hal = Cl, Br, I) have been grown by dissociative sublimation and by chemical vapour transport with P, S, Hal, CuHal and combinations thereof as transporting agents in the temperature range 800 to 1000 K. Microscopic observation of the tetrahedral faces revealed several growth features. Macrosteps, closed loop steps and surface protuberances are always accompanied with the presence of liquid CuHal/Cu2S droplets on the growing crystal surface. The phenomena are characteristic for a two-dimensional Vapour-Liquid-Solid growth mechanism. In the absence of CuHal/Cu2S liquid phase, direct growth from the gas phase (VS growth) takes place leading to hillocks and growth spirals with low step heights (∼ 5–10 Å). 相似文献
73.
W. Eckstein E. S. Mashkova V. A. Molchanov A. V. Sidorov Yu. N. Zhukova 《Applied Physics A: Materials Science & Processing》1993,57(3):271-277
The spatial distributions of sputtered particles have been investigated both experimentally and by computer simulation using the TRIM.SP code for 30 keV argon-ion bombardment of tungsten in a wide range of primary-ion incidence angles (0°–80°). Two sets of the targets were used. One of them was prepared from fine-grained polycrystalline ingot, another one from rolled sheet W. It was found that the experimental results for these targets were different. For rolled tungsten a typical Wehner-spot picture, although smeared, is observed. For fine-grained tungsten the sputtered particle spatial distributions are practically cupola-shaped. Some differences between the experimental results and computer-simulation data can be attributed to the effect of surface topography either initial or developed during the ion bombardment. 相似文献
74.
75.
In the past four years, laboratory robotics has emerged as an important subset of automation technology. It offers chemists an approach to tackling the difficult problems that arise when attempting to automate sample preparation procedures. Successful implementations of this technology yield cost and labor savings, improved assay precision, increased data output, improved morale, and improved worker safety. This paper introduces the principles of this growing technology, summarizes the current state of the art, and suggests some of its future possibilities. The principles of laboratory robotics are discussed in the context of a system developed from an in-house technology base. This system has been performing pH and fluoride determinations for the past two years. The current state of laboratory robotics technology is examined by presenting our experiences with an all-commercial immunoassay system from Zymark. The future of this technology is very promising. Recent innovations by a variety of vendors promise to make the technology easier to use. In the next decade, the combination of more powerful microcomputers and software should produce systems that can learn and optimize their own performance. 相似文献
76.
77.
Saija Werner Doris Pospiech Dieter Jehnichen Kathrin Eckstein Hartmut Komber Peter Friedel Andreas Janke Franziskus Näther Uta Reuter Brigitte Voit Rosa Taurino Massimo Messori 《Journal of polymer science. Part A, Polymer chemistry》2011,49(4):926-937
A series of diblock copolymers of n‐pentyl methacrylate and methyl methacrylate (PPMA/PMMA BCP) with one or two terminal functional groups was prepared by sequential anionic polymerization of PMA and MMA using an allyl‐functionalized initiator and/or and end‐capping with allyl bromide. Allyl functional groups were successfully converted into OH groups by hydroboration. The morphology in bulk was examined by temperature‐dependent small‐angle X‐ray measurements (T‐SAXS) and transmission electron microscopy (TEM) showing that functional groups induced a weak change in d‐spacings L0 as well as in the thermal expansion behavior. T‐SAXS proved that the lamellar morphologies were stable over multiple heating/cooling cycles without order‐disorder transition (ODT) until 300 °C. While non‐functionalized BCP formed parallel lamellae morphologies, additional OH‐termination at the PMMA block forced in very thin films (ratio between film thickness and lamellar d‐spacing below 1) the generation of perpendicular lamellae morphology through the whole film thickness, as shown by Grazing‐incidence small‐angle X‐ray scattering experiments (GISAXS) measurements. Functionalized BCP were successfully used in thin films as templates for silica nanoparticles in an in‐situ sol–gel process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
78.
79.
Alexandra Junkes Ioana Pintilie Eckhart Fretwurst Doris Eckstein 《Physica B: Condensed Matter》2012,407(15):3013-3015
Silicon particle detectors in tracking devices for the high luminosity Large Hadron Collider will suffer from an extremely intense radiation field of mainly hadronic particles. The main radiation induced deep defect centres in silicon, responsible for the increase of the dark current and corresponding noise, are the cluster related defect levels E5 and E205a. This work confirms the identification of the E5 level as tri-vacancy (V3). This defect transforms into the tri-vacancy-oxygen complex (V3O) at temperatures above 200 °C. The defect concentrations were obtained by means of Deep Level Transient Spectroscopy (DLTS) and Thermally Stimulated Current technique (TSC) performed on float zone (FZ), epitaxially grown (Epi) and Magnetic Czochralski (MCz) silicon diodes, irradiated with 1 MeV neutrons and 23 GeV protons. 相似文献
80.
Paulo J. S. Silva Jonathan Eckstein 《Computational Optimization and Applications》2006,33(2-3):115-156
We consider the variational inequality problem formed by a general set-valued maximal monotone operator and a possibly unbounded
“box” in
, and study its solution by proximal methods whose distance regularizations are coercive over the box. We prove convergence
for a class of double regularizations generalizing a previously-proposed class of Auslender et al. Using these results, we derive a broadened class of augmented
Lagrangian methods. We point out some connections between these methods and earlier work on “pure penalty” smoothing methods
for complementarity; this connection leads to a new form of augmented Lagrangian based on the “neural” smoothing function.
Finally, we computationally compare this new kind of augmented Lagrangian to three previously-known varieties on the MCPLIB
problem library, and show that the neural approach offers some advantages. In these tests, we also consider primal-dual approaches
that include a primal proximal term. Such a stabilizing term tends to slow down the algorithms, but makes them more robust.
This author was partially supported by CNPq, Grant PQ 304133/2004-3 and PRONEX-Optimization. 相似文献