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991.
本文采用描述荷电和中性 pion 介子与核子-反核子强相互作用的同位旋SU(2)不变耦合模型,计算出在 pion0 重整化混合圈链图传播下 p pbar -> p pbar 弹性散射微分截面的“精确”解析结果;并且将此结果与在 pion0 树图传播下的微分截面作了对比分析,得到相应的辐射修正重要信息。本文完成的工作对进一步深入研究 pion 介子与核子-反核子强相互作用的同位旋SU(2)不变耦合模型以及深入理论探讨正反质子对撞实验,都将提供理论研究的参考价值。 相似文献
992.
Morphology‐Controlled Self‐Assembly of an Organic/Inorganic Hybrid Porphyrin Derivative Containing Polyhedral Oligomeric Silsesquioxane (POSS) 下载免费PDF全文
Prof. Feng Liu Yuan Zhang Lei Xu Prof. Weian Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5540-5547
An organic/inorganic hybrid porphyrin derivative, namely, metal‐free tetrakisphenyl porphyrin–polyhedral oligomeric silsesquioxanes (H2TPP‐POSS) was synthesized by azide–alkyne click chemistry. The self‐assembly behavior of H2TPP‐POSS was systematically studied in CHCl3 at different concentrations and in solvents with different polarities. Novel nanovesicles could be obtained through the self‐assembly of H2TPP‐POSS in CHCl3 at a concentration lower than 10?4 m. Diffuse microrods formed at a concentration higher than 10?4 M . Additionally, the polarity of the solvent also greatly influenced the assembled morphologies, and a series of assembled morphologies, including crescent‐shaped micelles, spherical micelles, doughnut‐shaped vesicles, and ordered square sheets, could form in solvents with different polarities. 相似文献
993.
Nanocomposite Made of an Oligo(p‐phenylenevinylene)‐Based Trihybrid Thixotropic Metallo(organo)gel Comprising Nanoscale Metal–Organic Particles,Carbon Nanohorns,and Silver Nanoparticles 下载免费PDF全文
Subham Bhattacharjee Dr. Suman K. Samanta Parikshit Moitra K. Pramoda Ram Kumar Prof. Dr. Santanu Bhattacharya Prof. Dr. C. N. R. Rao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5467-5476
A silver ion (Ag+)‐triggered thixotropic metallo(organo)gel of p‐pyridyl‐appended oligo(p‐phenylenevinylene) derivatives (OPVs) is reported for the first time. Solubilization of single‐walled carbon nanohorns (SWCNHs) in solutions of the pure OPVs as well as in the metallogels mediated by π–π interactions has also been achieved. In situ fabrication of silver nanoparticles (AgNPs) in the SWCNH‐doped dihybrid gel leads to the formation of a trihybrid metallogel. The mechanical strength of the metallogels could be increased stepwise in the order: freshly prepared gel<dihybrid gel<trihybrid gel. Microscopic studies of the trihybrid gel indicate the formation of three distinct morphologies, that is, nanoscale metal–organic particles (NMOPs), flowerlike aggregates of SWCNHs and AgNPs, and also their integration with each other. Detailed studies suggest lamellar organizations of the linear metal–ligand complexes in the NMOPs, which upon association create a three‐dimensional network that eventually immobilizes the solvent molecules. 相似文献
994.
Cover Picture: Dipolar Rotors Orderly Aligned in Mesoporous Fluorinated Organosilica Architectures (Angew. Chem. Int. Ed. 16/2015) 下载免费PDF全文
995.
《应用有机金属化学》2017,31(11)
A series of hybrid hetero bimetallic metal–organic frameworks, as solid metal–organic precursors, have been prepared via a conventional hydrothermal method. Herein, we report a facile approach for the synthesis of novel crystalline organic–inorganic hybrid compounds of diaquabis(acetylacetonato)[nickel(II)/zinc(II)] in the presence of varying mole ratios of Ni(II)/Zn(II) mixed metal ions. C10H18O6Ni0.7Zn0.3 (N0.7Z0.3AA.2H2O) as an instance of the series has been investigated through detailed characterization. The crystal is composed of N0.7Z0.3AA units and two coordinated water molecules to form a monoclinic structure with space group P21/c. All the solid‐state structures have the metals in octahedral environments forming six‐membered chelate rings. The unit cell dimensions were obtained using single‐crystal X‐ray diffraction. Thermogravimetric analysis reveals that the hybrid compounds can be considered as suitable precursors for the synthesis of oxides via metal–organic chemical vapour deposition. At room temperature, all crystals clearly exhibit paramagnetic behaviour. Besides varying molar ratios of hybrid, the transition point of magnetic behaviour occurs at Ni critical concentration of around 10% in the hybrid. In addition, the magnetic susceptibility increases with increasing Ni content in the compounds. 相似文献
996.
Vegetable oils (Ground nut) are being investigated to serve as a possible substitute for non-biodegradable mineral oils, which are currently being used as metal-cutting fluids in machining processes. In this study, thermophysical properties of hybrid nanofluids (vegetable oil) to be used as metalworking cutting fluids are investigated. In-situ synthesis of copper (Cu) and zinc (Zn) combined hybrid particles is performed by mechanical alloying with compositions of 50:50, 75:25, and 25:75 by weight. Characterizations of the synthesized powder were carried out using X-ray diffraction, a particle size analyzer, FE-SEM, and TEM. Hybrid nanofluids with all the three combinations of hybrid nanoparticles were prepared by dispersing them into a base fluid (vegetable oil). The thermophysical properties, such as thermal conductivity and viscosity, were studied for various volume concentrations and at a range of temperatures. Experimental results have shown enhancement in thermal conductivity in all cases and also an increase in viscosity. The enhancement in viscosity is similar in all three combinations, as the particle size and shape are almost identical. The enhancement in thermal conductivity is higher in Cu–Zn (50:50), resulting in better enhancement in thermal conductivity due to the Brownian motion of the particles and higher thermal conductivity of the nanoparticles incorporated. 相似文献
997.
Investigation of the sensitivity of turbulent closures and coupling of hybrid RANS‐LES models for predicting flow fields with separation and reattachment 下载免费PDF全文
Hybrid models have found widespread applications for simulation of wall‐bounded flows at high Reynolds numbers. Typically, these models employ Reynolds‐averaged Navier–Stokes (RANS) and large eddy simulation (LES) in the near‐body and off‐body regions, respectively. A number of coupling strategies between the RANS and LES regions have been proposed, tested, and applied in the literature with varying degree of success. Linear eddy‐viscosity models (LEVM) are often used for the closure of turbulent stress tensor in RANS and LES regions. LEVM incorrectly predicts the anisotropy of Reynolds normal stress at the RANS‐LES interface region. To overcome this issue, use of non‐linear eddy‐viscosity models (NLEVM) have started receiving attention. In this study, a generic non‐linear blended modeling framework for performing hybrid simulations is proposed. Flow over the periodic hills is used as the test case for model evaluation. This case is chosen due to complex flow physics with simplified geometry. Analysis of the simulations suggests that the non‐linear hybrid models show a better performance than linear hybrid models. It is also observed that the non‐linear closures are less sensitive to the RANS‐LES coupling and grid resolution. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
998.
《化学:亚洲杂志》2017,12(7):753-758
Hybrid nanocrystals of PVBA‐b ‐PS/ZIF‐8 were prepared by the growth of ZIF‐8 on the surface of the self‐assembled structures from poly(p ‐vinylbenzoic acid)‐block‐polystyrene. Two different morphologies—micelles and vesicles—were obtained in selective solvents owing to the different ratios of PVBA to PS blocks. The structure and morphology of the PVBA‐b ‐PS/ZIF‐8 composites were characterized by Fourier transform IR spectroscopy, thermogravimetric analysis, X‐ray diffraction, transmission electron microscopy and scanning electron microscopy. PVBA‐b ‐PS/ZIF‐8 showed high catalytic performance in Knoevenagel condensation reactions at room temperature, which were attributed to the more exposed active sites of the small ZIF‐8 nanocrystals grown in a confined space and a high concentration of reactants in the polymeric aggregates. 相似文献
999.
Albert Sung Soo Lee Seung‐Sock Choi He Seung Lee Hyeon Yeol Jeon Kyung‐Youl Baek Seung Sang Hwang 《Journal of polymer science. Part A, Polymer chemistry》2012,50(21):4563-4570
A series of inorganic–organic hybrid block copolymers were synthesized via atom transfer radical polymerization using a fully condensed, ladder‐like structured polyphenylsilsesquioxane end‐functionalized macroinitiator. The inorganic portion, ladder‐like polyphenylsilsesquioxane, was synthesized in a one‐batch, base‐catalyzed system, whereas organic hard and soft monomers, styrene, and n‐butyl acrylate, were polymerized and copolymerized on the ends of the linear, inorganic backbone. Synthesized hybrid diblock, triblock, and random copolymers were characterized by 1H NMR, 29Si NMR, gel permeation chromatography, static light scattering, Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. Hybrid block copolymers were well‐defined with low polydispersity (<1.4) and exhibited enhanced thermal properties in the form of increased glass transition and degradation onset temperatures over their organic analogues.© 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
1000.
A new hybrid scheme is proposed, which combines the improved third‐order weighted essentially non‐oscillatory (WENO) scheme presented in this paper with a fourth‐order central scheme by a novel switch. Two major steps have been gone through for the construction of a high‐performance and stable hybrid scheme. Firstly, to enhance the WENO part of the hybrid scheme, a new reference smoothness indicator has been devised, which, combined with the nonlinear weighting procedure of WENO‐Z, can drive the third‐order WENO toward the optimal linear scheme faster. Secondly, to improve the hybridization with the central scheme, a hyperbolic tangent hybridization switch and its efficient polynomial counterpart are devised, with which we are able to fix the threshold value introduced by the hybridization. The new hybrid scheme is thus formulated, and a set of benchmark problems have been tested to verify the performance enhancement. Numerical results demonstrate that the new hybrid scheme achieves excellent performance in resolving complex flow features, even compared with the fifth‐order classical WENO scheme and WENO‐Z scheme. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献