排序方式: 共有101条查询结果,搜索用时 15 毫秒
61.
62.
The paper investigates the effects of heat transfer in MHD flow of viscoelastic stratified fluid in porous medium on a parallel plate channel inclined at an angle θ. A laminar convection flow for incompressible conducting fluid is considered. It is assumed that the plates are kept at different temperatures which decay with time. The partial differential equations governing the flow are solved by perturbation technique. Expressions for the velocity of fluid and particle phases, temperature field, Nusselt number, skin friction and flow flux are obtained within the channel. The effects of various parameters like stratification factor, magnetic field parameter, Prandtl number on temperature field, heat transfer, skin friction, flow flux, velocity for both the fluid and particle phases are displayed through graphs and discussed numerically. 相似文献
63.
64.
Uribe-Romo FJ Doonan CJ Furukawa H Oisaki K Yaghi OM 《Journal of the American Chemical Society》2011,133(30):11478-11481
Condensation of 2,5-diethoxyterephthalohydrazide with 1,3,5-triformylbenzene or 1,3,5-tris(4-formylphenyl)benzene yields two new covalent organic frameworks, COF-42 and COF-43, in which the organic building units are linked through hydrazone bonds to form extended two-dimensional porous frameworks. Both materials are highly crystalline, display excellent chemical and thermal stability, and are permanently porous. These new COFs expand the scope of possibilities for this emerging class of porous materials. 相似文献
65.
A multiunit catalyst with synergistic stability and reactivity: a polyoxometalate-metal organic framework for aerobic decontamination 总被引:1,自引:0,他引:1
Song J Luo Z Britt DK Furukawa H Yaghi OM Hardcastle KI Hill CL 《Journal of the American Chemical Society》2011,133(42):16839-16846
A combination of polyanion size and charge allows the Keggin-type polyoxometalate (POM), [CuPW(11)O(39)](5-), a catalyst for some air-based organic oxidations, to fit snuggly in the pores of MOF-199 (HKUST-1), a metal-organic framework (MOF) with the POM countercations residing in alternative pores. This close matching of POM diameter and MOF pore size in this POM-MOF material, [Cu(3)(C(9)H(3)O(6))(2)](4)[{(CH(3))(4)N}(4)CuPW(11)O(39)H] (1), results in a substantial synergistic stabilization of both the MOF and the POM. In addition, this heretofore undocumented POM-MOF interaction results in a dramatic increase in the catalytic turnover rate of the POM for air-based oxidations. While 1 catalyzes the rapid chemo- and shape-selective oxidation of thiols to disulfides and, more significantly, the rapid and sustained removal of toxic H(2)S via H(2)S + 1/2 O(2) → 1/8 S(8) + H(2)O (4000 turnovers in <20 h), the POM or the MOF alone is catalytically slow or inactive. Three arguments are consistent with the catalytic reactions taking place inside the pores. POM activation by encapsulation in the MOF likely involves electrostatic interactions between the two components resulting in a higher reduction potential of the POM. 相似文献
66.
Cover Picture: Metal–Organic Frameworks from Edible Natural Products (Angew. Chem. Int. Ed. 46/2010)
67.
Selective Capture of Carbon Dioxide under Humid Conditions by Hydrophobic Chabazite‐Type Zeolitic Imidazolate Frameworks 下载免费PDF全文
Nhung T. T. Nguyen Dr. Hiroyasu Furukawa Dr. Felipe Gándara Dr. Hoang T. Nguyen Kyle E. Cordova Prof. Omar M. Yaghi 《Angewandte Chemie (International ed. in English)》2014,53(40):10645-10648
Hydrophobic zeolitic imidazolate frameworks (ZIFs) with the chabazite ( CHA ) topology are synthesized by incorporating two distinct imidazolate links. Zn(2‐mIm)0.86(bbIm)1.14 (ZIF‐300), Zn(2‐mIm)0.94(cbIm)1.06 (ZIF‐301), and Zn(2‐mIm)0.67(mbIm)1.33 (ZIF‐302), where 2‐mIm=2‐methylimidazolate, bbIm=5(6)‐bromobenzimidazolate, cbIm=5(6)‐chlorobenzimidazolate, and mbIm=5(6)‐methylbenzimidazolate, were prepared by reacting zinc nitrate tetrahydrate and 2‐mIm with the respective bIm link in a mixture of N,N‐dimethylformamide (DMF) and water. Their structures were determined by single‐crystal X‐ray diffraction and their permanent porosity shown. All of these structures are hydrophobic as confirmed by water adsorption isotherms. All three ZIFs are equally effective at the dynamic separation of CO2 from N2 under both dry and humid conditions without any loss of performance over three cycles and can be regenerated simply by using a N2 flow at ambient temperature. 相似文献
68.
69.
70.