9,90-(2,5-Dibromo-1,4-phenylene)bis[9H-carbazole] (1) crystallizes as a category I order–disorder (OD) structure composed of non-polar layers of one kind with B2/m(1)1 layer symmetry. The crystals are made up of the two polytypes with a maximum degree of order (MDO). The monoclinic MDO1 polytype (B21/d) possesses an orthorhombic B-centered lattice and appears in two orientations, which are rela...

An amino-terminal fragment of human apolipoprotein E3 (residues 1-165) has been expressed and crystallized in three different crystal forms under similar crystallization conditions. One crystal form has nearly identical cell dimensions to the previously reported orthorhombic (P2(1)2(1)2(1)) crystal form of the amino-terminal 22 kDa fragment of apolipoprotein E (residues 1-191). A second orthorh...

We studied temperature dependence of complex capacitance, impedance, and polarized Raman spectra of single crystal Cs2Nb4O11. First, we observed a sharp lambda-shaped peak at 165 degrees C in the complex capacitance, then found drastic changes in the Raman spectra in the same temperature range. Utilizing the pseudosymmetry search of structure space group, we attributed the observed anomalies to...

Different structural chemistries resulting from the Pb2+ lone-pair electrons in the PbMO3 perovskites are reviewed. The Pb2+ lone-pair electrons enhance the ferroelectric transition temperature in PbTiO3, stabilize vanadyl formation in PbVO3, and induce a disproportionation reaction of CrIV in PbCrO3. A Pb2+ + NiIV = Pb4+ + NiII reaction in PbNiO3 stabilizes the LiNbO3 structure at ambient pres...

Effects of water on the catalytic performances of MoVTeNbO catalyst in the oxidation of propane to acrylic acid have been investigated at different reaction temperatures and different steam contents. Obtained results show that both catalytic performances and catalyst structure are very sensitive to the presence of water vapor in the reaction feed. Presence of water induces some structural modif...

In this study, MgxCu3-xV2O8 (0 ≤ x ≤ 3) and MgyCu2-yV2O7 (0 ≤ y ≤ 2) compositions were synthesized by the chemical coprecipitation method and characterized by X-ray diffraction, UV-vis-NIR spectroscopy and CIE L* a* b* parameters measurements. Melting points of compounds Cu3V2O8 and Cu2V2O7 are 780°C and 790°C, respectively. The addition of small amounts of Mg (II), MgxCu3-xV2O8 (x < 1.0) and M...

The structure of metastable, incommensurately modulated Na(2)Si(3)O(7) has been determined from single-crystal X-ray diffraction data. In contrast to previous investigations which stated that the compound crystallizes in an orthorhombic space group, this study shows that the compound is monoclinic with a pseudo-orthorhombic cell and is affected by twinning. The structure is described in the (3 ...