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951.
On the System Zn/Mo/O. I. Phases and Properties of Ternary Zinc Molybdates; Crystal Structure of Zn3Mo2O9 Several ternary compounds are known in the Zn/Mo/O-system. The phases ZnMoO4, Zn2Mo3O8 and Zn3Mo2O9 are stable at 900°C. The coexistence ranges are shown in the ternary phase diagram. The structure of Zn3Mo2O9 has been determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic space group P21/m (a = 7,757(1) Å, b = 7,132(1) Å, c = 8,370(2) Å, β = 117,40(1)º, Z = 2). 相似文献
952.
The single crystal x-ray structures of (E)-(2-arylethenyl)cyclooctatetraenes 1 and 2 have been determined. The nitro group in 2 does not influence the geometry of the COT ring relative to that of 1. The influence of various substituents on several structural parameters of the COT ring are analyzed in terms of steric/electrostatic and electronegativity effects of the substituent. 相似文献
953.
Comparative Calorimetric Study of ICP Generator with Forward-Vortex and Reverse-Vortex Stabilization
Different methods of ICP stabilization are discussed, including the Reverse Vortex Stabilization, for which no previous well-described implementation is in science literature. Comparative calorimetric study was performed for two methods of stabilization: the Forward Vortex and the Reverse Vortex ones. Experiments were made for the ICP torch of invariable geometry with the power supply plate power up to 50 kW. Experimental technique is described and the tables with experimental data are presented. The efficiency of two studied methods is discussed primarily from the standpoint of plasma jet generation. It is demonstrated that the reverse-vortex stabilization is more efficient for almost all possible applications of ICP. 相似文献
954.
955.
TlFe3Te3 is hexagonal, space groupP63/m–C
2h
6
,a=9.350(2) Å,c=4.2230 (7) Å,Z=2. Iron and tellurium atoms occupy the positions 6 (h) withx=0.170,y=0.149 andx=0.046,y=0.357 respectively. Thallium atoms are situated in 2 (d). The structure was determined on the basis of single crystal data obtained form a four circle diffractometer. Refinement yielded andR-value of 4.8% for an asymmetric set of 267 reflections. TlFe3Te3 is a new structure type. The structure and its relations to the Mn5Si3–, the Nb3Te4-and the Tl
x
V6S8-type are discussed. 相似文献
956.
The structural properties and Angiotensin-I converting enzyme (ACE) inhibition activities of a polysaccharide (PGE) extracted from Gastrodia elata Blume were investigated. PGE was extracted using hot water and purified by Sephadex G-200 followed by ultra-filtration. The structural characterisation of PGE was analysed by FT–IR, NMR spectroscopy, specific rotation determination, periodate oxidation-smith degradation, methylation analysis, GC–MS and Congo red test. The results revealed that PGE was composed by glucose, with an average molecular weight of 1.54 × 103 kDa. The structure of PGE was 1→3 and 1→4,6-branched-glucopyranose that had a linear backbone of (1 → 4)-linked-d-glucopyranose (Glcp). ACE-inhibitory activity results showed that PGE was efficient to inhibit ACE and the IC50 value was 0.66 mg/mL. 相似文献
957.
Several novel aromatic liquid crystalline copolyesters with regular sequence structure were prepared by melt Sehotten-Baumann polycondensation via complex monomer. Polarizing microscope with hot stage, thermal analysis and X-ray diffraction were used to investigate the structure and properties of the copolyesters. The effects of structural units, such as flexible spacer, noncolinear meta-linked phenylene unit, crankshaft unit, kink with flexible bridging unit and various substituted benzene rings on melting temperature of aromatic copolyesters were studied and discussed on the basis of crystalline structure of the polymers. 相似文献
958.
Titanium isopropoxide, zirconium propoxide and niobium ethoxide have been studied in reaction with 2-methoxyethanol (moe),
acetylacetone (acac) and water. Structural information has been obtained using FTIR and 1H, 13C FT NMR spectroscopies. The number of interchanged alkoxy groups increased with increasing excess of 2-methoxyethanol and
reaction temperature. The exchange reaction between Nb(OEt)5 and 2-methoxyethanol was the least effective. Reaction with acetylacetone proved to be very efficient, but dilution with
an excess of solvent quenched this reaction. A solid phase of Zr(acac)4 was formed for more than 2 modes of acac added. The appearance of multiplets in NMR spectra due to CH, CO centers of acac
ring in Zr monoacetylacetonate indicated non-symmetric bonding of the bidentate acac group and more than one magnetically
non-equivalent species. Conversely, a modified Nb(OEt)4 (acac) precursor proved to be monomeric with a symmetrically bound acac group. During the interchange reaction the symmetry
of the Nb(OEt)
x
(Omoe)4−x
(acac) species was reduced. Alkoxy groups were first hydrolyzed followed by very slow removal of the acac ring. Zirconium
and niobium modified precursors, respectively, were the least and the most susceptible to gelation. Addition of strong acid
further increased the stability of acetylacetonates against condensation. 相似文献
959.
用新的合成途径,以Na_2WO_4·2H_2O为原料,Zn粉为还原剂,合成了三个簇合物(1)[W_3O_2(CH_3CO_2)_6(H_2O)_3]ZnBr_4·8H_2O,(2)H(W_3O_2(CH_3CO_2)_9]·5H_2O,(3)H_2Na_3[W_3O(CCH)_3(CH_3CO_2)_6(H_2)O][H_2W_(12)O_(40)]·13.5H_2O。在测定晶体结构和综合有关文献基础上,说明了反应过程,并进行了EHMO量化计算,探讨了该类型化合物的簇骼成键性质和相关的物理,化学性质。 相似文献
960.
A new nickel(Ⅱ) coordination complex [Ni(phen)3]·(m-nitrobenzoic acid)2·(H2O) was synthesized by self-assembly of m-nitrobenzoic acid, 1,10-phenanthroline and nickelous perchlorate. It crystallizes in the monoclinic system, space group C2/c, with a = 2.4596(6), b = 1.2124(3), c = 1.9824(5) nm, β = 97.088(5)°, V = 5.866(3) nm3, Dc = 1.474 g/cm3, Z = 4, Mr = 1301.82, μ(MoKα) = 0.417 mm-1 F(000) = 2688, R = 0.0493 and wR = 0.1025. Structural determination indicates that the nickel(Ⅱ) ion is coordinated with six nitrogen atoms from three phens, giving a distorted octahedral coordination geometry. The cyclic voltametric analysis shows that the electron transfer in the electrode reaction is irreversible. 相似文献