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111.
A new class of proton exchange composite membranes made by incorporating phosphosilicate gels into SPPO matrix was prepared and characterized. The thermal stability was evaluated by TGA and DSC, and the amorphous structure information was provided from XRD. The experimental results showed that the composite membranes have good stability to oxidation by Fenton's reagent test, and the membrane dimension is hardly changed, even at high temperature. The hydration number values of the persulfonic acid group of composite membranes were lower than that of Nafion 112 at room temperature, but the water uptake of composite membranes at 80°C was higher than that of Nafion 112. With increasing relative humidity and doping amount, the conductivity of the composite membranes increased. Moreover, the conductivities of water-equilibrated composite membranes were higher than that of Nafion 112 (0.0871 S/cm) at room temperature, and the highest conductivity for the composite membrane was 0.216 S/cm. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
112.
A new fluorinated polystyrene bearing a p-sulbstiuted perfluoro[1-(2-fluorosulfonylethoxy)]ethyl group was synthesized via one-electron oxidation of polystyrene by perfluoro[2-(2-fluorosulfonylethoxy)]propionyl peroxide at different peroxide to polystyrene molar ratios.The yield of perfluoroalkylation decreases with the increase of the reactant molar ratio.The modified polymer has been characterized by various techniques:the ring pefluoro[1-(2-fluorosulfonylethoxy)]ethylation has been proved by FT-IR and ^19FNMR;the X-ray photoelectron spectra(XPS) show the maximum binding energy of F18,O18,C18(two kinds of carbon atoms,namely C-H and C-F)and S2p,respectively; desulfonylation of the fluorinated polystyrene appearing at 217℃ has been found by its thermogravimetric analysis (TGA).The determinations of contact angle,refractive index and glass transition temperature of the modified polymer have disclosed that when the contact angle increases with the increase of the molar ratio,the refractive index and glass transition temperature decrease.The polydispersity values indicate that the degradation of the polymer chains did not occur during the reaction. 相似文献
113.
Unsaturated nucleoside analogues 21, 22, 46, and 54, comprising four- and six-membered rings, were synthesized using two different approaches. The 2-benzyloxycycloalkanones 23a and 23b served as starting materials for both methods. Conversion to methylenecyclobutanes 29a and 29b was followed by addition of bromine via pyridinium perbromide to give vicinal dibromides 30a and 30b. Reaction of 29a with Br2 gave a ring-contracted cyclopropane derivative 31. Alkylation-elimination of adenine with 30a gave bromoalkene 32 as the major product and adenine-containing unsaturated derivatives 33, 34, and 35 as minor components. Vicinal dibromide 30b gave the Zaitsev cyclohexene 45 as the only product. Epoxidation of 29a and 29b afforded oxiranes 36a and 36b which were used in alkylation of adenine to furnish hydroxy derivatives 37a, 37b, 38a, and 38b. Beta-elimination via mesylates 39a and 40a using tBuOK/DMF gave Z- and E-methylenecyclobutanes 34 and 35. With an excess of base the E-bis-methylenecyclobutane 41 was obtained. Mesylation of cyclohexane derivatives 37b and 38b gave the Z- and E-N6-mesylated product 48. By contrast, the N6-benzoyl derivatives 49 and 50 afforded O-mesyl intermediates 51 and 52. Beta-elimination gave both Hofmann and Zaitsev products 53 and 45. O-Debenzylation of 34 and 35, 45, and 53 afforded analogues 21, 22, 46, and 54. The E-isomer 22 was also obtained by hydroboration procedure from E-bis-methylenecyclobutane 41. 相似文献
114.
Bei Jin Xiaosong Zhou Jinmin Guan Shanglong Yan Jiayin Xu Jianwen Chen 《Journal of Dispersion Science and Technology》2019,40(6):909-917
There is still the dearth of reports of jackfruit filum pectin-based nanoparticles as the Pickering emulsifiers with respect to the applications in foods, cosmetics and medicines. So we fabricated soy protein-jackfruit filum pectin nanoparticles (SPP) by photocatalysis as Pickering emulsifier. Jackfruit filum pectin exhibited lower yield (17.31%), degree of methoxylation (15.53%), but higher galacuronic acid content (74.22%). A strong linkage between pectin and soy protein was formed by photocatalysis. The conjugated polymer could self-assemble into compact near globular nanoparticle. The mean size of SPP was larger than that of soy protein nanoparticles but smaller than that of soy protein-pectin complex without photocatalysis. Besides, the zeta potential of SPP was ?33.8?mV, significantly lower than that of soy protein nanoparticles but higher than that of control sample, further confirming that SPP surfaces were completely covered with pectin molecules. Compared with control sample, the three-phase contact angle increased from 42.7 to 90.6°, indicated that SPP could be developed as effective Pickering emulsifiers. The emulsions stabilized by SPP exhibited high thermal stability and excellent salt tolerance as well as good freeze-thaw stability in comparison with emulsions covered with control sample. These findings would provide a potential way of producing effective Pickering emulsifier.GRAPHICAL ABSTRACT 相似文献
115.
在石英单晶表面制成矩矩截面毛细管柱中进行电泳实验。由于矩形柱比圆形柱有更大散热侧面积且石英单晶的导热性能远无于熔融石英,所以可施加较高的场强,不仅提高了柱效,而且缩矩了分离时间。两相交的通道之间形成自然连接,可实现二维分离,并消除死体积。 相似文献
116.
Jin Guan Chi Zhang Yang Wang Yiguang Guo Peiting Huang Longshan Zhao 《Analytical and bioanalytical chemistry》2016,408(28):8099-8109
117.
Xiaolong Shi Xiaoru Zhao Libing Duan Huinan Sun Jinming Liu Xiaojun Bai Mengmeng Guan Mengmeng Cao Jinru Liu 《Journal of Sol-Gel Science and Technology》2013,66(2):301-305
Sn-doped ZnO (SZO) thin films are deposited by sol–gel dip-coating method with Sn content at 0 at.% and 1–15 at.% with an increment of 2 at.%. The structure and luminescence of the films are investigated. X-ray diffraction results indicate that all the SZO samples show preferential orientation along the (002) direction, and the scanning electron microscope exhibits that the surface morphology of the films change from nanoparticles to nanorods with increasing Sn concentration. X-ray photoelectron spectroscopy reveals that Sn exists as valence of +4 in the matrix. The photoluminescence peaks at 381 and 398 nm are observed in all the samples. The ratio of intensity of peak at 381 nm to that of peak at 398 nm differed markedly. The intensity of peak at 398 nm might be due to the response for the Sn atoms, while the intensity of peak at 381 nm is probably related to the quantum size effect. 相似文献
118.
The intersection marker method for 3D interface tracking of deformable surfaces in finite volumes 下载免费PDF全文
Currently, the majority of computational fluid dynamics (CFD) codes use the finite volume method to spatially discretise the computational domain, sometimes as an array of cubic control volumes. The Finite volume method works well with single‐phase flow simulations, but two‐phase flow simulations are more challenging because of the need to track the surface interface traversing and deforming within the 3D grid. Surface area and volume fraction details of each interface cell must be accurately accounted for, in order to calculate for the momentum exchange and rates of heat and mass transfer across the interface. To attain a higher accuracy in two‐phase flow CFD calculations, the intersection marker (ISM) method is developed. The ISM method is a hybrid Lagrangian–Eulerian front‐tracking algorithm that can model an arbitrary 3D surface within an array of cubic control volumes. The ISM method has a cell‐by‐cell remeshing capability that is volume conservative and is suitable for the tracking of complex interface deformation in transient two‐phase CFD simulations. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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