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131.
In this research, membrane life-time was evaluated by means of accelerated ageing experiments. A pressure pulse unit was used to perform the ageing experiments in an accelerated way. An experimental design has been set up and four ageing factors were varied at two levels. The four ageing factors studied were: fouling status of the membrane, cleaning agent concentration, magnitude of the back pulse and number of applied back pulses. The integrity of the membrane modules was evaluated by means of permeability testing, pressure decay tests and bubble tests. Also tensile tests were performed to investigate the mechanical properties of the membrane modules. The collected data was used for an analysis of variance to determine which ageing factors and which combination of ageing factors influence membrane life time. The analysis showed that the fouling status in combination with the number of applied pressure pulses were significant ageing factors. Additional tensile tests confirmed these results. 相似文献
132.
133.
David Elbaz Sophia Buhbut Benjamin Zeev Kupfer Arie Zaban Zeev Zalevsky 《Optics Communications》2012,285(10-11):2746-2749
In this paper we present a new type of optical fiber aiming to radially polarize the electrical field. This special device is composed of a tapered fiber having a classical core while on top of its external surface, radially oriented nanorods are disposed. The tails of the propagated wave are interacting with those radially oriented nanorods. This interaction performs the polarization of the propagated mode into a radial polarization. 相似文献
134.
135.
Arenst Andreas Arie Wonyoung Chang Joong Kee Lee 《Journal of Solid State Electrochemistry》2010,14(1):51-56
To improve the electrochemical performances of Si thin film anodes for lithium rechargeable batteries, fullerene thin films
are prepared by plasma-assisted evaporation methods to be used as coating materials. Analyses via Raman and X-ray photoelectron
spectroscopy indicate that amorphous polymeric films originated from fullerene are formed on the surface of the silicon thin
film. The electrochemical performance of these fullerene-coated silicon thin film as an anode material for rechargeable lithium
batteries has been investigated by cyclic voltammetry, charge/discharge tests, and electrochemical impedance spectroscopy.
The fullerene-coated Si thin films demonstrated a high specific capacity of above 3,000 mAh g−1 as well as good capacity retention for 40 cycles. In comparison with bare silicon anodes, the fullerene-coated silicon thin
film showed superior and stable cycle performance which can be attributed to the fullerene coating layer which enhances the
Li-ion kinetic property at the electrode/electrolyte interface. 相似文献
136.
Quantum‐dot‐sensitized solar cells (QDSCs) are a promising low‐cost alternative to existing photovoltaic technologies such as crystalline silicon and thin inorganic films. The absorption spectrum of quantum dots (QDs) can be tailored by controlling their size, and QDs can be produced by low‐cost methods. Nanostructures such as mesoporous films, nanorods, nanowires, nanotubes and nanosheets with high microscopic surface area, redox electrolytes and solid‐state hole conductors are borrowed from standard dye‐sensitized solar cells (DSCs) to fabricate electron conductor/QD monolayer/hole conductor junctions with high optical absorbance. Herein we focus on recent developments in the field of mono‐ and polydisperse QDSCs. Stability issues are adressed, coating methods are presented, performance is reviewed and special emphasis is given to the importance of energy‐level alignment to increase the light to electric power conversion efficiency. 相似文献
137.
We consider the bounded integer knapsack problem (BKP) , subject to: , and xj{0,1,…,mj},j=1,…,n. We use proximity results between the integer and the continuous versions to obtain an O(n3W2) algorithm for BKP, where W=maxj=1,…,nwj. The respective complexity of the unbounded case with mj=∞, for j=1,…,n, is O(n2W2). We use these results to obtain an improved strongly polynomial algorithm for the multicover problem with cyclical 1’s and uniform right-hand side. 相似文献
138.
VU VAN KHUONG 《高校应用数学学报(英文版)》2009,24(1)
The aim of this paper is to show that the following difference equation:xn+1=α+(xn-k/xn-m)p,n=0,1,2…,where α>-1,p>0,k,m ∈ N are fixed, 0≤m<k,x-k,x-k+1,…,x-m,…,x-1,x0 are positive, has positive nonoscillatory solutions which converge to the positive equilibrium x=α+1.It is interesting that the method described in the paper, in some cases can also be applied when the parameter α is variable. 相似文献
139.
Eman MR Regan-Klapisz E Pinkse MW Koop IM Haverkamp J Heck AJ Verkleij AJ Post JA 《Electrophoresis》2006,27(8):1669-1682
Endothelial senescence contributes to endothelium dysfunctionality and is thereby linked to vascular aging. A dynamic proteomic study on human umbilical vein endothelial cells, isolated from three umbilical cords, was performed. The cells were cultured towards replicative senescence and whole cell lysates were subjected to 2-D difference gel electrophoresis (DIGE). Despite the biological variability of the three independent isolations, a set of proteins was found that showed senescence-dependent expression patterns in all isolations. We focused on those proteins that showed significant changes, with a paired analysis of variance (RM-ANOVA) p-value of < or =0.05. Thirty-five proteins were identified with LC-Fourier transform MS, and functional annotation revealed that endothelial replicative senescence is accompanied by increased cellular stress, protein biosynthesis and reduction in DNA repair and maintenance. Nuclear integrity becomes affected and cytoskeletal structure is also changed. Such important changes in the cell infrastructure might accelerate endothelium dysfunctionality. This study provides biological information that will initiate studies to further unravel endothelial senescence and gain more knowledge about the consequences of this process in the in vivo situation. 相似文献
140.
Cazacu A Tong C van der Lee A Fyles TM Barboiu M 《Journal of the American Chemical Society》2006,128(29):9541-9548
The self-assembly of ureido crown-ether derivatives has been examined in homogeneous solution, in the solid state, and in planar bilayer membranes. The self-assembly is driven by head-to-tail hydrogen bonding between the urea functional groups. Dimers and higher oligomers are formed in CDCl3 solution as assessed by the change in the ureido NH chemical shift as a function of concentration. Single-crystal X-ray diffraction shows that an antiparallel association of the ureas produces columnar channels composed of face-to-face crown ethers. Powder X-ray diffraction studies also show the presence of a minor phase based upon a parallel urea association leading to an alternative columnar arrangement of the crown ethers. In bilayer membranes at low concentration of ureido crown ether added, membrane disruption is observed together with rare single-channel openings, but at higher concentration, a rich array of interconverting channel conductance states is observed. The channel results are interpreted as arising from discreet stacks of ureido crown ethers where the transport of cations would occur via the macrocycles, admixed with larger pores formed by association of the crown ether headgroups around a central large pore. 相似文献