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21.
J. Prost J.-B. Manneville R. Bruinsma 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(4):465-480
Membranes in thermal equilibrium are well known to exhibit Brownian motion type shape fluctuations. Membranes containing active
force centers -- such as chemically active membrane proteins -- suffer additional non-equilibrium shape fluctuations due to
the activity of these force centers. We demonstrate, using scaling arguments, that non-equilibrium shape fluctuations are
in general greatly amplified by the presence of a nearby wall or membrane due to the absence of a fluctuation-dissipation
theorem. For adhesive membranes, this fluctuation magnification effect may facilitate the establishment of bonding. For non-adhesive
membranes, fluctuation magnification produces a long-range repulsive pressure which can exceed the well known Helfrich repulsion
due to purely thermal fluctuations.
Received: 1 September 1997 / Accepted: 3 December 1997 相似文献
22.
In production systems of automobile manufacturers, multi-variant products are assembled on paced final assembly lines. The assignment of operations to workplaces and workers deter mines the productivity of the manufacturing process. In research, various exact and heuristic solution procedures have been developed for different versions of the so-called assembly line balancing problem. 相似文献
23.
介绍了反场箍缩KTX装置主机主要构成部件、安装精度要求以及装配方案。通过建立一个独立于装置之外且可永久保存的装配基准网,以及对坐标系控制网的测量数据分析,确保各部件的安装定位和准确测量。 相似文献
24.
《Arabian Journal of Chemistry》2022,15(1):103524
MXene, well-identified as Ti3C2TX, belongs to the family of two-dimensional (2D) materials, which have been currently explored in various applications. Very recently, such materials have been pointed out as potential nanomaterials for advanced solute separations when introduced in membranes, such as ion separation, gas separation, nanofiltration, chiral molecular separation, and solvent separation. This latter separation, generally named Pervaporation (PV), is identified as a highly selective technology for water separations. To date, few pieces of research have been released but providing interesting insights into several solvent (including water) separations. Hence, this brief review aims to analyze and discuss the latest advances for utilizing MXenes for PV membranes. Particular emphasis has been devoted to the relevant outcomes in the field, along with the strategies followed by researchers to tailor membranes. Based on the current findings, the perspectives in the field are also stated. 相似文献
25.
The processes of lactic acid production include two key stages, which are (a) fermentation and (b) product recovery. In this
study, free cell of Bifidobacterium longum was used to produce lactic acid from cheese whey. The produced lactic acid was then separated and purified from the fermentation
broth using combination of nanofiltration and reverse osmosis membranes. Nanofiltration membrane with a molecular weight cutoff
of 100–400 Da was used to separate lactic acid from lactose and cells in the cheese whey fermentation broth in the first step.
The obtained permeate from the above nanofiltration is mainly composed of lactic acid and water, which was then concentrated
with a reverse osmosis membrane in the second step. Among the tested nanofiltration membranes, HL membrane from GE Osmonics
has the highest lactose retention (97 ± 1%). In the reverse osmosis process, the ADF membrane could retain 100% of lactic
acid to obtain permeate with water only. The effect of membrane and pressure on permeate flux and retention of lactose/lactic
acid was also reported in this paper. 相似文献
26.
Charles Y. Cummings Susan J. Stott Michael J. Bonné Karen J. Edler Pauline M. King Roger J. Mortimer Frank Marken 《Journal of Solid State Electrochemistry》2008,12(12):1541-1548
The formation of variable-thickness CeO2 nanoparticle mesoporous films from a colloidal nanoparticle solution (approximately 1–3-nm-diameter CeO2) is demonstrated using a layer-by-layer deposition process with small organic binder molecules such as cyclohexanehexacarboxylate
and phytate. Film growth is characterised by scanning and transmission electron microscopies, X-ray scattering and quartz
crystal microbalance techniques. The surface electrochemistry of CeO2 films before and after calcination at 500 °C in air is investigated. A well-defined Ce(IV/III) redox process confined to
the oxide surface is observed. Beyond a threshold potential, a new phosphate phase, presumably CePO4, is formed during electrochemical reduction of CeO2 in aqueous phosphate buffer solution. The voltammetric signal is sensitive to (1) thermal pre-treatment, (2) film thickness,
(3) phosphate concentration and (4) pH. The reversible ‘underpotential reduction’ of CeO2 is demonstrated at potentials positive of the threshold. A transition occurs from the reversible ‘underpotential region’
in which no phosphate phase is formed to the irreversible ‘overpotential region’ in which the formation of the cerium(III)
phosphate phase is observed. The experimental results are rationalised based on surface reactivity and nucleation effects. 相似文献
27.
Bok Lyeon Lee Yoon Hee Lee Il Yoon Jong Hwa Jung Ki-Min Park Shim Sung Lee 《Microchemical Journal》2001,68(2-3)
Extraction and transport behaviors of isomeric oxathia macrocycles (L2, ortho-; L3, meta- and L4, para-isomer) and their structure related open-chain compound (L1) towards Ag(I) picrate have been examined. From the plot of log (DAg(I)/[pic−]) vs. log [L]0 for all of the ionophores were linear with slope near unity, thereby confirming the 1:1:1 complex formations of Ag(I)/ligand/picrate ion to be extracted into the dichloromethane phase. The extractability of an acyclic ionophore was superior to those of the corresponding cyclic ones. In membrane transport experiments, the slow rate of release of Ag(I) from the membrane into the receiving phase seems to be responsible for lower transport efficiency. Upon addition of sodium thiosulfate as a stripping reagent in receiving phase, the efficiency of transport is significantly enhanced in the order of L1 (acyclic)>L2 (ortho-)>L3 (meta-)>L4 (para-) in accordance with those of log Kex values. It is hypothesized that the ion-pair complexation of L1 in extraction step would be more favorable in extraction and transport of Ag(I). Its structure have been confirmed by X-ray diffraction analysis of [Ag(L1)pic], where L1=1,10-bis(mercaptobenzylyl)-4,7-dioxadecane. 相似文献
28.
The selective enhancement of membrane introduction mass spectrometry for non-polar alkanes, alkenes, and aromatic hydrocarbon
compounds by the application of acetonitrile as a chemical ionization reagent was investigated. Acetonitrile Cl is able to
produce specific fragment ions for many of the compounds test and this can be used to identify and quantify the parent neutrals.
This method provided relatively high detection limits of the test compounds. This method could potentially be useful for analytical
applications such as the detection of non-polar hydrocarbons for environmental studies if CH3CN Cl/MIMS is coupled with a preconcentration method. 相似文献
29.
Obermaier C Jankowski V Schmutzler C Bauer J Wildgruber R Infanger M Köhrle J Krause E Weber G Grimm D 《Electrophoresis》2005,26(11):2109-2116
The method of preparing protein mixtures for electrophoretic analysis of membrane-associated cell proteins was improved. By sonication, about one-half of the proteins of thyroid cells were released into the supernatant, while the other half preferentially comprising membrane proteins still remained in cell fragments, which could be sedimented by centrifugation. After sonication, even those proteins which remained in cell fragments, could completely be dissolved by free-flow isoelectric focusing media. They migrated through the free-flow electrophoresis chamber without forming precipitates. Because of these improvements, it was possible to show that the two thyroid cancer cell lines ML-1 and ONCO-DG1 express cytokeratin 8 at similar rates, but cytokeratins 7 and 18 differently. In addition, the presence of inorganic pyrophosphatase, tubulin-beta-5, and tubulin-beta-1 chains in human thyroid cells was proved for the first time. 相似文献
30.
《Arabian Journal of Chemistry》2020,13(1):404-415
This work describes newly synthesized composite polymeric membranes and their utilization in propane/propylene separation in a gas mixture. The nonporous composite polymers were successfully synthesized by using thermoplastic polyurethane (TPU) and several silver salts/silver salts with ionic liquids (ILs). Our studies showed that silver bis(trifluoromethanesulfonyl)imide (Ag[Tf2N]) containing membranes outperformed other silver salt containing membranes in terms of selectivity. In addition, to this finding, ILs, as additives for the membranes, enhanced the selectivity by facilitating improved coordination of the olefin with the silver ions in the dense composite polymers. 相似文献