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121.
122.
Wei Jiang Zheng-Long Yang Ding Weng Jun-Wei Wangb Yun-Feng Lu Min-Juan Zhang Zhen-Zhong Yang 《中国化学快报》2014,25(6):849-853
PbTe/SnTe hybrid nanocrystals with designed shape, chemical composition and narrow size distribution were synthesized by an efficient solvothermal approach. This approach enables mass and economical synthesis of PbTe-based nanocrystals. The organic ligands were completely removed by pretreatment with a super-hydride solution, making it possible to fabricate fully dense and robust thermoelectric devices with increased electrical conductivity. 相似文献
123.
Annealing polyethylene terephthalate (PET)/polycarbonate (PC) blends enhance the transesterification reaction and increase the amount of copolymer at the interface of both polymers. The copolymer enhances the compatibility of PET with PC, because it contains both PET and PC blocks, which causes the interface between PET and PC to become fuzzy. When the PET/PC undergoes batch physical foaming with CO2, the copolymer significantly changes the resulting cell morphology, that is, the annealing time. Before annealing or in the absence of the copolymer, bubble nucleation occurs and dominates growth at the interface. When the PET/PC blends are annealed, the interface impedes bubble nucleation and growth. The polymer is stretched at the interface by bubble growth, forming fibril‐like structures connecting two polymer domains at the interface. Increased annealing time causes the interface to become more homogeneous and makes heterogeneous bubble nucleation difficult. At higher copolymer concentrations, the interface of PET and PC becomes fuzzy and the cell morphology becomes like those of foamed homogeneous polymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
124.
S. J. Jeong 《实验传热》2013,26(3):257-265
Abstract Because carbon dioxide is ozone friendly and has negligible global warming potential, it has received renewed interest in recent years as an important alternative refrigerant. In this article, the heat transfer characteristics of a carbon dioxide-filled two-phase closed thermosyphon were investigated experimentally, and the empirical heat transfer correlations are reported. The heat transfer data were analyzed, and heat transfer coefficients were compared with conventional heat transfer correlations. The results represent that heat transfer correlation of the heated section can be expressed with Kutatelatze's correlation, and heat transfer coefficients of the condenser section are found to be in reasonable agreement with the Nusselt equation. 相似文献
125.
Yanlei Dong Xianhong Wang Xiaojiang Zhao Fosong Wang 《Journal of polymer science. Part A, Polymer chemistry》2012,50(2):362-370
Poly(ether carbonate)s (PPCs) with carbonate unit (CU) content ranging from 57.8 to 97.1% and number average molecular weight (Mn) around 100 kg/mol were conveniently prepared via copolymerization of CO2 and propylene oxide under combinatorial catalyst of rare earth ternary (RET) complex and double metal cyanide (DMC) complex. Enhancement of catalytic activity and reduction of propylene carbonate byproduct were realized due to synergetic effect of the two metal catalysts, where DMC can be activated in the presence of RET. Solubility fractionation confirmed that the obtained PPCs were copolymers, not physical blends of each polymer. Thermal performances of the PPCs were closely related to their CU content, their glass transition temperatures (Tg) were tunable in the range of 6.7–36.3 °C, which decreased with decreasing CU content, while their thermal stabilities were enhanced significantly, an increase of 50.5 °C in 50% weight loss temperature was observed when CU content decreased from 97.1 to 57.8%. Both shear storage modulus and complex viscosity increased with increasing CU content, which became more obvious at lower frequency, featuring well with the CU content in the PPCs. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
126.
Dr. Michael L. Lejkowski Dr. Ronald Lindner Dr. Takeharu Kageyama Dr. Gabriella É. Bódizs Dipl.‐Chem. Philipp N. Plessow Dr. Imke B. Müller Dr. Ansgar Schäfer Dr. Frank Rominger Prof. Dr. Peter Hofmann Dr. Cornelia Futter Dr. Stephan A. Schunk Dr. Michael Limbach 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(44):14017-14025
For more than three decades the catalytic synthesis of acrylates from the cheap and abundantly available C1 building block carbon dioxide and alkenes has been an unsolved problem in catalysis research, both in academia and industry. Herein, we describe a homogeneous catalyst based on nickel that permits the catalytic synthesis of the industrially highly relevant acrylate sodium acrylate from CO2, ethylene, and a base, as demonstrated, at this stage, by a turnover number of greater than 10 with respect to the metal. 相似文献
127.
Mina Sakuragi Naoto Aoyagi Yoshio Furusho Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2014,52(14):2025-2031
In this study, we investigated the CO2‐capture/release behavior of the polystyrene‐bearing cyclic amidine pendant groups, which was synthesized via free radical polymerization of HCl salt of the corresponding styrene monomer followed by neutralization. For comparison, we also prepared the polystyrene bearing N‐formyl‐1,3‐propanediamine pendant groups through the hydrolysis of the cyclic amidine group by treatment with an alkaline solution. First, we examined the CO2‐capture/release behaviors of the amidine and amine monomers in aqueous solution in terms of conductivity. The conductivity of a wet DMSO solution of the amidine monomer increased upon CO2 bubbling at 25 °C and reached a stationary value of about 11 mS/m, which indicated the formation of the bicarbonate salt. Conversely, the conductivity decreased to its original value upon N2 bubbling at 50 °C, reflecting the complete release of the trapped CO2 molecules. Both solutions showed the changes in the conductivity with quick responses, and no appreciable difference was observed between them. We then investigated the CO2‐capture/release behaviors of the amidine and amine polymers, by taking advantage of the binary system with polyethylene glycol, and found that the binary system with the amidine polymer captured and released CO2 more efficiently than that with the amine polymer. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2025–2031 相似文献
128.
The influence of the first-order crystalline transformation at about 60°C on the infrared bands of trans-1,4-polybutadiene yields microscopic information that supports the two-component microcrystalline model of a folded chain having loose and tight end loops at the lamellar surfaces. The temperature dependence of the band parameters of the 908-cm?1 vinyl band indicates that 1,2-(side vinyl) units are not easily taken into the crystalline component, thus forming long loops at the crystal surface that account for the micro-Brownian motion detected in the low-temperature phase. The results argue that infrared band parameters are excellent probes for details of the thermodynamics and morphology of polymers. 相似文献
129.
Mohamed Abass Hassan A. Allimony Heba Hassan 《Phosphorus, sulfur, and silicon and the related elements》2013,188(12):1799-1810
Abstract Oxidation of 3-acetyl-1-alkyl-4-hydroxyquinolin-2(1H)-ones using selenium dioxide under Riley conditions was described. The oxidation reaction produced a mixture of 2 unexpected α-keto acid and its dehydrated dimer derivatives. The oxidation reaction was studied under different reaction conditions in order to maximize the yields and optimize reaction conditions. Also, 1-alkyl-4-hydroxy-3-(2-nitroacetyl)quinolin-2(1H)-one and/or 3-acetyl-1-alkyl-4-diflouro-boryloxyquinolin-2(1H)-one derivatives were subjected to the same oxidation reaction giving rise improved reaction yields and selectivity in case of the boron-complex. Alkaline degradation of the dehydrated dimers led to formation of the 4-hydroxy-2-oxoquinoline-3-carboxylic acids while under the same conditions the α-keto acids underwent deoxalylation. [Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the following free supplemental files: Additional figures]. 相似文献
130.
Ana G. Silva Nenad BundaleskiAugusto M.C. Moutinho Orlando M.N.D. Teodoro 《Applied Surface Science》2012,258(6):2006-2009
Water adsorption dynamics on two TiO2 (1 1 0) rutile surfaces at room temperature has been investigated using the work function (WF) change as a function of time. The first surface was prepared in a standard way using sputtering/annealing cycles, whereas the second one was long term annealed at 620 K in moderate vacuum conditions (the residual gas pressure of about 1 × 10−7 mbar) and cleaned afterwards. The WF change show striking difference as compared to those obtained for highly reduced TiO2 (1 1 0) rutile or the (2 × 1) reconstructed surfaces. For the first kind of surface we show that the observed adsorption dynamics can be qualitatively explained by the present understanding of the water adsorption on non-reconstructed TiO2 (1 1 0) rutile surface according to which the bridging oxygen vacancies and Ti rows are the main adsorption sites. Although generally similar to the former results, water adsorption dynamics on the second kind of the surface has an additional feature that can be only explained by a new adsorption site, which we suggest to be due to (2 × 1) reconstructed regions coexisting with the non-reconstructed TiO2 (1 1 0) surface. 相似文献