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The problem of forced convection in a channel filled with a nanofluidsaturated porous medium is investigated, numerically. A finite difference Computational Fluid Dynamics (CFD) model with structured uniform grid system is employed to solve the momentum and energy equations. In modeling flow in the channel, the effects of flow inertia, variable porosity and Brinkman friction are taken into account. Studies are carried out for different nanoparticles with different volume fractions in the range 0%-4% and different nanoparticle diameters. Comparison made between our numerical and semi analytical Differential Transform Method (DTM) results with those in previous published research is found to be appropriate. Results show that increasing either nanoparticls volume fraction or pressure gradient parameter improves heat transfer. Further, for large quantities of nanoparticle concentration and pressure gradient, the channeling phenomenon is intensified. 相似文献
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J. A. Carlisle L. J. Terminello A. V. Hamza E. A. Hudson E. L. Shirley F. J. Himpsel 《Molecular Crystals and Liquid Crystals》2013,570(1):819-824
Abstract The full spectrum of occupied and unoccupied σ and π orbitals is presented for solid C60, C70, and graphite, using Cls emission and absorption spectroscopy. There are significant diffcrences between C60 and C70, and even larger changes relative to their infinite analog graphite (C∝). A comparison is made with photocmission and inverse photoemission results, along with first principles quasiparticle calculations. 相似文献
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Olesia I. Kucheriv Dr. Sergii I. Shylin Valerii Y. Sirenko Dr. Vadim Ksenofontov Prof. Wolfgang Tremel Dr. Ioan-Andrei Dascălu Dr. Sergiu Shova Dr. Il'ya A. Gural'skiy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(44):e202200924
Spin-crossover complexes with multistep transitions attract much attention due to their potential applications as multi-switches and for data storage. A four-step spin crossover is observed in the new iron(II)-based cyanometallic guest-free framework compound Fe(2-ethoxypyrazine)2{Ag(CN)2}2 during the transition from the low-spin to the high-spin state. A reverse process occurs in three steps. Crystallographic studies reveal an associated stepwise evolution of the crystal structures. Multiple transitions in the reported complex originate from distinct FeII sites which exist due to the packing of the ligand with a bulky substituent. 相似文献
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Facile synthesis of high-molecular-weight acid-labile polypeptides using urethane derivatives
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Shirley Wong Young Jik Kwon 《Journal of polymer science. Part A, Polymer chemistry》2015,53(2):280-286
Polypeptides have received noticeable attention in the biomedical field due to their structural versatility and biomimetic properties. Particularly, polypeptides that are responsive to biological stimuli, such as mildly acidic extracellular and intracellular conditions, have great potential as delivery carriers for therapeutics. However, synthesis of high-molecular-weight acid-labile peptides is often daunting due to highly restrictive polymerization conditions and limitations in preserving acid-degradable functional groups. For instance, the popular N-carboxyanhydride (NCA) ring-opening polymerization (ROP) is efficient, but acid-labile NCA monomers are difficult to synthesize and store. In this study, acid-labile polypeptides with high molecular weights were synthesized under mild, permissive conditions using carboxylated urethane derivative monomers which are stable for ease of handling. The polymerization was successful in various organic solvents at room temperature, and did not require additional energy or initiation to drive the formation of NCA intermediates. The polymerization was also rapid enough to be independent of inert atmosphere. The strategy explored here to synthesize high-molecular-weight acid-labile polypeptides offers significant advantages including facile synthesis of acid-labile urethane derivative monomers that are stable, even in contact with moisture, and fast polymerization under easily achievable conditions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 280–286 相似文献
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