Poor intrinsicconductivity has been a principal limiting factor for Na3V2(PO4)3 (NVP) cathode material. Herein, a synergistic strategy of Nb5+ substitution and constructing with three-dimensional rGO lamella is propo...
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Poor intrinsicconductivity has been a principal limiting factor for Na3V2(PO4)3 (NVP) cathode material. Herein, a synergistic strategy of Nb5+ substitution and constructing with three-dimensional rGO lamella is proposed for the first time to optimize the characteristics of NVP. The introduction of Nb5+ generates beneficial carriers and vacancies that optimize the electronic structure of NVP system. Meanwhile, rGO substrate can construct an effective conductive network for the facilitated electronic transportation and form a stabilized SEI layer after cycling to protect the active particles from being collapsed. This double treatment significantly improves the kineticcharacteristics of NVP. Moreover, theoretical calculations indicate that beneficial Nb5+ doping can effectively reduce the band gap between conductive and valence bands, as well as decline the energy barrier of migration for Na+. Notably, the modified Nb0.15-NVP/c@rGO exhibits impressive electrochemical performance. It delivers a capacity of 107.9 mAh g-1 and keeps a value of 102.6 mAh g-1 after 500 cycles at 2c with a high retention of 95.35%. It submits a capacity value of 97.2 mAh g-1 at 20c, 82.92% reversible capacity (80.6 mAh g-1) could be retained after 2000 cycles. Even at 120 and 300c, this material still performs high values of 84.9 and 71.3 mAh g-1, indicating the superior rate capability.
Microsoft's next-generation platform, the NET Framework, offers a new language, c#, which aims to offer the power of c++ with the ease of Visual Basic. In this article, the authors consider the application of c# a...
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Microsoft's next-generation platform, the NET Framework, offers a new language, c#, which aims to offer the power of c++ with the ease of Visual Basic. In this article, the authors consider the application of c# and the NET Framework to real-time systems. Their performance tests show that c and c# performance is comparable in some cases. However, they show that c# is not currently suitable for hard real-time applications and should be used for firm and soft real-time applications only with care.
The potential catalytic activity of selected c,N-chelated organotin(IV) compounds (e.g. halides and trifluoroacetates) for derivatization of both dimethyl carbonate (DMc) and diethyl carbonate (DEc) was investigated. ...
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The potential catalytic activity of selected c,N-chelated organotin(IV) compounds (e.g. halides and trifluoroacetates) for derivatization of both dimethyl carbonate (DMc) and diethyl carbonate (DEc) was investigated. Some tri-, di- and monoorganotin(IV) species (LcN(n-Bu)2Sncl (1), LcN(n-Bu)*** (1a), LcN(n-Bu)2SnI (2), LcNPh2Sncl (3), LcNPh2SnI (4), LcN(n-Bu)Sncl2 (5), LcNSnBr3 (6) and [LcNSn(Oc(O)cF3)]2(mu-O)(mu-Oc(O)cF3)2 (7)) bearing the LcN moiety (LcN?=?2-(N,N-dimethylaminomethyl)phenyl-) were assessed as catalysts for reactions of both DMc and DEc with various substituted anilines. The catalytic activities of 4 and 7 for derivatization of DMc with p-substituted phenols were studied for comparison with the standard base K2cO3/Silcarbon K835 catalyst (catalyst 8). The composition of resulting reaction mixtures was monitored by multinuclear NMR spectroscopy, Gc and Gc-MS techniques. In general, catalysts 1, 3 and 7 exhibited the highest catalytic activity for all reactions studied, while some of them yielded selectively carbonates, carbamates, lactam or substituted urea. copyright (c) 2012 John Wiley & Sons, Ltd.
Dystrophin-like dys-1 gene is expressed and required in muscle tissue, playing a vital role in gravisensing in caenorhabditis elegans (c. elegans). To date, microRNA (miRNA)-mediated epigenetic mechanism in microgravi...
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Dystrophin-like dys-1 gene is expressed and required in muscle tissue, playing a vital role in gravisensing in caenorhabditis elegans (c. elegans). To date, microRNA (miRNA)-mediated epigenetic mechanism in microgravity-induced muscular atrophy remains to be elucidated. In the present study, we first analyzed mRNA and miRNA expression profiles in space-flown dys-1(cx18) mutants and wild type worms (wt) of c. elegans. The results showed that spaceflight and microgravity have fewer effects on mRNA and miRNA expression in dys-1 mutant than in wt worms. mRNA and miRNA expression patterns of dys-1 mutants were changed by microgravity. Hierarchical clustering analysis showed that the alterations of genes function on neuromuscular system under space environment. Seven miRNAs (cel-miR-52, 56, 81, 82, 84, 124 and 230) have 18 significant anti-correlated target genes under space environment. RT-qPcR analysis confirmed that miR-52 and cdh-3, miR-84 and lin-14, miR-124 and mgl-3 in dys-1 mutants reversely altered under microgravity environment and in simulated microgravity experiment. Locomotion ability was only reduced in F0 wt worms but not in dys-1 mutants as well as their F1 offspring after simulated microgravity. We observed expression alterations of 7 neuromuscular genes (unc-27, nlp-22, flp-1, egl-5, flp-4, mgl-3, unc-94) in F0 wt worms, which might be involved in the regulation of locomotion ability of c. elegans. This study provides important insights to reveal the mechanism in the pathogenesis of muscular atrophy induced by microgravity.
A LiFePO4/c material with different amounts of iron phosphides was synthesized by a sol-gel method with different calcination temperatures. XRD, HRTEM, SEM, FTIR, BET, Raman, and magnetic measurements were carried out...
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A LiFePO4/c material with different amounts of iron phosphides was synthesized by a sol-gel method with different calcination temperatures. XRD, HRTEM, SEM, FTIR, BET, Raman, and magnetic measurements were carried out to characterize the physical properties of the LiFePO4/c, while EIS, cV, and charge-discharge tests were carried out to characterize the electrochemical performance. It is obtained that the crystallinity, the particle size of the LiFePO4, and the amount of iron phosphides in the sample are the factors that affect the electrochemical performance of the material, where the key factor determining the electrochemical performance varies in different situations. The samples possessing well-crystallized LiFePO4 particles and similar particle size demonstrated improved rate performance with the increasing amount of iron phosphides when the calcination temperature increased from 650 to 750 degrees c. The results showed that the rate performance could be improved by harmonious improvement of the ionicconductivity of Li+ and the electronicconductivity.
Poor thermal conductivity, especially in thickness direction, is a major obstacle to extend the service lifetime of c/Siccomposite. However, there are few papers focusing on finely designing heat conductive channel b...
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Poor thermal conductivity, especially in thickness direction, is a major obstacle to extend the service lifetime of c/Siccomposite. However, there are few papers focusing on finely designing heat conductive channel but a simply introduction of various modifiers to improve c/Sic thermal conductivity, which leads to less success. Herein, multi-layer graphene sheets were utilized to improve the thermal conductivity of c/Siccomposites via an effective method to design graphene heat conductive channels. To determine the role of graphene sheets in improving thermal conductivity, the effect of the different loading fractions of graphene and microstructure of as-prepared composites were systemically investigated. Results revealed that the thermal conductivity of composites increased by 204% with well-designed graphene heat conductive channels. Besides, compared with the porosity, the orderly aligned heat conductive pathways played a more important role in thermal conductivity. This work provides a new and effective method for preparing well-designed heat conductive channels to enhance thermal conductivity of c/Sic.
The electrical properties of c/Siccomposites could be used for online and in-situ damage monitoring. To investigate alternating current (Ac) impedance response to damage in the c/Siccomposites, monotonic and increme...
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The electrical properties of c/Siccomposites could be used for online and in-situ damage monitoring. To investigate alternating current (Ac) impedance response to damage in the c/Siccomposites, monotonic and incremental cyclic tensile tests were performed. Both Ac impedance and acoustic emission (AE) techniques were applied to clarify the damage evolution during the tests. The relationship between damage and electrical impedance response was investigated and validated via macroscopic equivalent circuit models. The effects of longitudinal deformation and damage on Ac impedance characteristics, including impedance magnitude and phase angle, were obtained from the models. Results showed that the longitudinal deformation increases the impedance magnitude and the phase angle, and the damage causes the impedance magnitude to increase and the phase angle to decrease. The phase angle is significantly sensitive to fiber breakage, which makes the Ac-based method more suitable for online damage monitoring and final failure warning.
A set of experiments was carried out in the system NaAlSi3O8-FeO-NiO-coO-Sic-NaH(2)PO(4)at 1550 degrees c, 4 GPa, and oxygen fugacity (fO(2)) 0.5-2.9 log. units below the iron-wustite (IW) buffer to estimate how c-O-H...
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A set of experiments was carried out in the system NaAlSi3O8-FeO-NiO-coO-Sic-NaH(2)PO(4)at 1550 degrees c, 4 GPa, and oxygen fugacity (fO(2)) 0.5-2.9 log. units below the iron-wustite (IW) buffer to estimate how c-O-H components can affect Ni, co, and P partition between silicate melt and a liquid metallic phase at redox conditions under which the metallic phase is segregated into melting products of the early reduced mantles of the Earth and other planetary bodies. It has been established that the Ni, co, and P partition coefficientsD(\M)(met/sil)between silicate melts saturated with carbon and containing dissolved c-O-H volatiles (mainly in the form of OH groups, H(2)and cH4) at relatively oxidized conditions (fO(2)> IW - 1.5) correspond toD(\M)(met/sil)values expected of metal-silicate melt equilibrium in volatile-free systems at analogousP,T,f(O2), andnbo/tparameters. Under more reduced conditions (fO(2)<= IW - 2), the presence of c-O-H volatiles leads to a decrease inD(\M)(met/sil)for Ni and P compared to that in "dry" melts. This difference increases with decreasingfO(2)and reaches similar to 0.5 and more than one order of magnitude for Ni and P, respectively, atfO(2)= IW - 2.9. The effect of volatiles onD(co)(met/sil)is much weaker, and hence, a decrease infO(2)leads to thatD(Ni)(met/sil)andD(co)(met/sil)converge. The Raman spectra of the experimental glasses and their SIMS analyses for hydrogen show that water content (OH + H2O) in the melts decreases with decreasingfO(2), whereas the contents of cH(4)and complexes with c-H bonds significantly increases. The likely reasons for the decrease inD(\M)(met/sil)under strongly reduced conditions may be changes in the structure of the silicate melts and the origin of complex compounds of siderophile elements with volatiles in these melts.
Highly diastereoselective 1,3-dipolar cycloaddition of in situ generated c,N-diaryl nitrilimines to (1R)-thiocamphor leads to chiral spiro-1,3,4-thiadiazolocamphane derivatives in good yields. The structures and stere...
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Highly diastereoselective 1,3-dipolar cycloaddition of in situ generated c,N-diaryl nitrilimines to (1R)-thiocamphor leads to chiral spiro-1,3,4-thiadiazolocamphane derivatives in good yields. The structures and stereochemistries of the new cycloadducts were fully established by spectroscopic methods including X-ray diffraction data. The diastereoselectivity observed in this reaction was explained by means of a brief theoretical study.
Metallic foam was introduced as an interlayer to improve the performance of the brazed c/ccomposite-titanium alloy joint, and the interfacial microstructure and residual stress of the brazed joint were investigated. ...
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Metallic foam was introduced as an interlayer to improve the performance of the brazed c/ccomposite-titanium alloy joint, and the interfacial microstructure and residual stress of the brazed joint were investigated. compared with the brazed joint without foam, introducing foam interlayer could achieve the uniform bonding interface, and Ag-based solid solution (Ag(s,s)) became more dispersed and smaller in the center of the brazing seam. The thickness of reaction layer close to c/ccomposite side was less than 1 mu m. Some cu-based solid solution (cu(s,s)) was detected, indicating that cu foam still existed after brazing. The residual stress and its distribution calculated by finite element method (FEM), and the residual stress of the brazed joint decreased from 293 MPa to 228 MPa. The introduction of the foam interlayer could obtain homogeneous microstructure, change stress distribution, and improve mechanical properties of the brazed joints.
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