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排序方式: 共有1172条查询结果,搜索用时 15 毫秒
41.
Heinz Buschatz Birgit Dagefrde Kai Jakoby Klaus‐Viktor Peinemann Dieter Paul 《化学,工程师,技术》2001,73(4):297-303
Membrane processes are able to separate liquid mixtures as well as mixtures of gases or vapours according to the sizes, solubilities, rates of diffusion or charges of the components. A separation is also possible using membranes in which the transport is coupled to a specific chemical reaction between the permeand and the membrane (facilitated or carrier mediated transport). This paper discusses aspects related to carrier‐mediated separation processes such as the transport mechanisms, the choice of appropriate carriers, the incorporation of carriers in the polymeric membrane material, the coating of porous support membranes with thin selective layers of the carrier‐polymer and, finally, the choice of appropriate parameters for the separation process. The separation of gas mixtures by carrier‐membranes appears very promising from a technical point of view. Experimental membrane samples often show excellent separation factors, but they have not met the permeability requirements for an economic use so far. 相似文献
42.
43.
Konstantin Efimov Mirko Arnold Julia Martynczuk Armin Feldhoff 《Journal of the American Ceramic Society》2009,92(4):876-880
X-ray diffraction and transmission electron microscopy were applied to investigate a sol–gel synthetic process for the mixed oxygen ion and electron conductor La2 NiO4+δ with a K2 NiF4 structure type. The development of the La2 NiO4+δ is elucidated considering the influence of calcination temperatures and dwell times. Following the thermal decomposition of nitrate and organic precursors in an intermediate step, the lanthanum nickel oxide is obtained after a short dwell time above 750°C. This occurs by the transformation of an ultrafinely dispersed powder consisting of lanthanum oxycarbonate, lanthanum oxide, and nickel oxide. The pure La2 NiO4+δ phase was obtained by similar solid-state reactions between nanocrystalline powder particles at just 950°C. 相似文献
44.
William P. Boshoff Viktor Mechtcherine Gideon P.A.G. van Zijl 《Cement and Concrete Research》2009,39(9):787-797
This paper is the second part of a two paper series about the time-dependant behaviour of Strain Hardening Cement-based Composite (SHCC) on the single fibre level. Having dealt with mechanisms of creep in SHCC in the first part, this paper reports single fibre pull-out tests that were done to investigate the effect of the pull-out rate on the mechanical response of the interface between the fibre and the matrix. It was found that not only the pull-out resistance increased with an increase of the pull-out rate but the probability of fibre rupture during pull-out as well. Another important finding was that the interfacial shear resistance and slip-hardening coefficient are not only dependant on the pull-out rate, but also the embedment length. 相似文献
45.
Partial polarization curves were plotted and the current efficiency of chromium was measured to show that addition of methanesulfonic acid to a chromium-plating electrolyte accelerates the deposition of chromium and increases its current efficiency because of a higher hydrogen overpotential. 相似文献
46.
Tool life testing in gundrilling: an application of the group method of data handling (GMDH) 总被引:1,自引:0,他引:1
Viktor P. Astakhov Vasily V. Galitsky 《International Journal of Machine Tools and Manufacture》2005,45(4-5):509-517
Although the known techniques of the design of experiments (DOE) allows significant improvements in the methodology of machining tests, their use in metal cutting is restricted by limited number of variables included into consideration, pre-set model, subjective pre-process decisions and uncertainties in the machining data collected experimentally. This paper introduces an application of a new powerful technique of DOE known as the group method of data handling (GMDH) to the design of tool life experiments that allows avoiding the above-mentioned disadvantages of traditional DOE. As a result of such an application, a mathematical model that correlates tool life in gundrilling of cast iron with various regime and design parameters was obtained. Special care was taken to avoid the influence of the dynamic phenomenon of the gundrilling process on the obtained experimental results. The obtained mathematical model reveals that tool life in gundrilling is a complex function of various regime and design parameters. 相似文献
47.
Pavel Diko Renáta Pagáčová Katarína Zmorayová Veronika Kuchárová Liudmila Vojtková Vitaliy Antal Viktor Kavečanský 《Journal of the American Ceramic Society》2021,104(2):740-752
Barium cerate (BaCeO3) is one of the possible additions to bulk YBa2Cu3O7 single-grain superconductors to suppress the growth of Y2BaCuO5 (Y211) particles. This paper investigates the synthesis of barium cerate powder and its use in YBa2Cu3O7 bulk superconductors. Crystalline barium cerate was synthesized by solid-state reaction, by co-precipitation of oxalates and by sol-gel method. Final calcination was held in air or in vacuum. It is shown that the most efficient in refining Y211 is nanocrystalline barium cerate prepared by sol-gel method calcined in vacuum. The effective refinement of Y211 particles occurred over the entire interval of nanocrystalline BaCeO3 addition from 0.38 to 1.90 wt%. The optimal concentration of nanosize barium cerate was determined, microstructure and superconducting properties were characterized. The effect of Y211 content on trapped field in YBCO bulks with addition of nanocrystalline barium cerate is shown. 相似文献
48.
Didem Ag Seleci Viktor Maurer Firat Baris Barlas Julian Cedric Porsiel Bilal Temel Elcin Ceylan Suna Timur Frank Stahl Thomas Scheper Georg Garnweitner 《International journal of molecular sciences》2021,22(9)
The development of multifunctional nanoscale systems that can mediate efficient tumor targeting, together with high cellular internalization, is crucial for the diagnosis of glioma. The combination of imaging agents into one platform provides dual imaging and allows further surface modification with targeting ligands for specific glioma detection. Herein, transferrin (Tf)-decorated niosomes with integrated magnetic iron oxide nanoparticles (MIONs) and quantum dots (QDs) were formulated (PEGNIO/QDs/MIONs/Tf) for efficient imaging of glioma, supported by magnetic and active targeting. Transmission electron microscopy confirmed the complete co-encapsulation of MIONs and QDs in the niosomes. Flow cytometry analysis demonstrated enhanced cellular uptake of the niosomal formulation by glioma cells. In vitro imaging studies showed that PEGNIO/QDs/MIONs/Tf produces an obvious negative-contrast enhancement effect on glioma cells by magnetic resonance imaging (MRI) and also improved fluorescence intensity under fluorescence microscopy. This novel platform represents the first niosome-based system which combines magnetic nanoparticles and QDs, and has application potential in dual-targeted imaging of glioma. 相似文献
49.
50.
A. G. Vikhman M. A. Kharichko V. Ya. Kievskii V. A. Efimov I. Yu. Enukova S. V. Osipov M. I. Aminev B. G. Levchenko 《Chemistry and Technology of Fuels and Oils》2005,41(5):370-379
Refining of heavy crudes and to an even greater degree, stiffening of the environmental requirements for the sulfur content
in petroleum products and sulfur compounds in gaseous emissions into the atmosphere make the problem of process and technical
improvement in active elemental sulfur production units (ESU) in oil refineries very pressing. These units are in the first
10 of the 30 environmentally most hazardous basic processes in refining of hydrocarbon feedstock [1].
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Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 5, pp. 27 – 31, September – October, 2005. 相似文献