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221.
The construction of two-dimensional (2D) copper halide networks within a variety of perovskite hosts by a low-temperature topochemical method is demonstrated. Ion exchange between some layered perovskite oxides of the type A'[An - 1(M,M')nO3n + 1] (A' = alkali metal, H, NH4; A = alkaline earth, rare earth, or Bi; M,M' = Nb, Ta, Ti; n = 2, 3) with CuX2 (X = Cl, Br) results in the oxyhalides (CuX)[An - 1(M,M')nO3n + 1]. Rietveld refinements from X-ray powder diffraction data show that the structures of these new copper oxyhalides contain edge-sharing CuO2X4 octahedra sandwiched between the M/M'O6 octahedra of the perovskite slabs. The compounds are low-temperature phases that decompose well below 700 degrees C. The copper oxyhalides exhibit antiferromagnetic ordering resulting from the magnetic exchange interactions within the planar Cu-X networks. 相似文献
222.
Don Solooki John D. Bradshaw Claire A. Tessier Wiley J. YoungsRonald F. See Melvyn ChurchillJoseph D. Ferrara 《Journal of organometallic chemistry》1994,470(1-2):231-236
1,2:5,6:9,10:13,14-Tetrabenzo-3,7,11,15-tetradehydro[16]annulene, or tetrabenzocyclyne (QBC) and 1,2:5,6:9,10:13,14:17,18:21,22-hexabenzo-3,7,11,15,19,23-hexadehydro[24]annulene (HBC) have been structurally characterized by X-ray. crystallography. QBC crystallizes in two different space groups; P21/c with a = 10.652(3) Å, b = 10.624(2) Å, c = 19.549(4) Å, β = 93.83(2)°, V = 2207.4(8) Å3, and Z = 4 and P41212 with a = 9.330(1) Å, c = 25.497(8) Å, V = 2219.6(12) Å, and Z = 4. HBC crystallizes in monoclinic P21/n with a = 14.763(3) Å, b = 10.296(2) Å, c = 22.057(4) Å, β = 108.61(3), V = 3177.4(11) Å3, T = 133 K, and Z = 4. Reaction of QBC with dicobaltoctacarbonyl has produced a tetracobalt complex which has been characterized by X-ray crystallography. This complex crystallizes in monoclinic P21/c with a = 14.699(3) Å, b = 17.188(3) Å, c = 17.254(3) Å, β = 112.63(3)°, V = 4023.5(13) Å3, and Z = 4. Only two of the four C---C triple bonds of QBC bind to dicobalthexacarbonyl moieties even when excess dicobaltoctacarbonyl is used. 相似文献
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Kevin W.K. Yee Alessio Alexiadis Jie Bao Dianne E. Wiley 《Journal of membrane science》2008,320(1-2):280-291
There is limited information from literature on the dynamic operability of membrane processes with multiple stages or loops. Such information is useful for assessing the performance achievable by an automatic controller proposed for a process design before the actual controller is implemented. Based on dynamic modeling of an industrial whey ultrafiltration process with an increasing number of stages up to a maximum of 12, the dynamic responses of the flowrate and concentration of the retentate were obtained. Features of the dynamic responses were used to determine the performance, in terms of quality and speed, that can be achieved by automatic controllers. In particular, limitations on the performance are indicated by features of dynamic responses such as effective time delay and inverse responses. Changes in effective time delay and inverse responses with the number of stages in the whey ultrafiltration process demonstrate a trade-off between process performance and control performance. This trade-off should be considered during process and controller design to maximize the economic return from the production of whey protein concentrates. 相似文献
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H. W. Wiley 《Fresenius' Journal of Analytical Chemistry》1882,21(1):269
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