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KDP crystals were rapidly grown from solution doped with different Ba2concentrations. The effects of Ba2on the growth rate, morphology and quality of KDP crystals were discussed. Significant changes in shapes and volume of the grown crystals have been observed. During the growth process, defect region expands gradually with the increasing Ba2concentration. Samples were cut from different parts of the asgrown crystals for investigating the optical quality, including transmission spectrum, scattering centers. Through comparison, it is found that the nonuniform distribution of Ba2ions causes remarkable difference in optical quality between prismatic and pyramidal sectors. © 2008 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim [ABSTRACT FROM AUTHOR]

Larginine hydrochloride monohydrate LAHCl.H2O has been synthesized and single crystals have been grown from its aqueous solution by slow evaporation and slow cooling methods. The solubility of the material was measured at various temperatures and bulk crystals of size 26×13×11 mm3have been grown by optimizing the growth parameters. The grown crystals have been subjected to single crystal XRD studies to confirm the structure and to estimate the lattice parameters. FTIR analysis indicate the mode of vibrations of different molecular groups present in LAHCl and confirm the protonation of guanidyl, amino groups and deprotonation of COOgroups. UVVis transmission spectrum revealed the linear optical properties of the grown crystals with a transparency of 65 over the entire visible range upto 300 nm. Thermal behavior of the grown crystal was investigated from DTA and TGA measurements. Dielectric studies have been carried out on the grown crystals. Kurtz and Perry powder SHG technique confirms the NLO property of the grown crystal. The SHG efficiency of LAHCl was found to be 0.38 with respect to KDP. © 2008 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim [ABSTRACT FROM AUTHOR]

Vitrification of aqueous cryoprotectant mixtures is essential in cryopreservation of proteins and other biological samples. Systematic measurements of critical cryoprotective agent (CPA) concentrations required for vitrification during plunge-cooling from T = 295 K to T = 77 K in liquid nitrogen are reported. Measurements on fourteen common CPAs, including alcohols (glycerol, methanol, 2-propanol), sugars (sucrose, xylitol, dextrose, trehalose), polyethylene glycols (ethylene glycol, PEG 200, PEG 2000, PEG 20000), glycols [dimethyl sulfoxide (DMSO), 2-methyl-2,4-pentanediol (MPD)], and salt (NaCl), were performed for volumes ranging over four orders of magnitude from ∼1 nl to 20 µl, and covering the range of interest in protein crystallography. X-ray diffraction measurements on aqueous glycerol mixtures confirm that the polycrystalline-to-vitreous transition occurs within a span of less than 2% w/ v in CPA concentration, and that the form of polycrystalline ice (hexagonal or cubic) depends on CPA concentration and cooling rate. For most of the studied cryoprotectants, the critical concentration decreases strongly with volume in the range from ∼5 µl to ∼0.1 µl, typically by a factor of two. By combining measurements of the critical concentration versus volume with cooling time versus volume, the function of greatest intrinsic physical interest is obtained: the critical CPA concentration versus cooling rate during flash-cooling. These results provide a basis for more rational design of cryoprotective protocols, and should yield insight into the physics of glass formation in aqueous mixtures. [ABSTRACT FROM AUTHOR]

Looks into the treatment of PtII and PdII complexes as ideal models for studies of square-planar complexes. Interest in the creation of new antitumor PdII complexes such as [Pd(asme)2]; Synthesis of mixed-ligand PdII complexes of a cis-square-planar coordination geometry with nitrogen and oxygen ligand atoms; Deviations of the central metal atoms from the mean plane.

This paper is a companion to a recent paper on fast rotation functions [Storoni et al. (2004), Acta Cryst. D60, 432-438], which showed how a Taylor-series expansion of the maximumlikelihood rotation function leads to improved likelihoodenhanced fast rotation functions. In a similar manner, it is shown here how linear and quadratic taylor-series expansions and least-squares approximations of the maximum-like-lihood translation function lead to likelihood-enhanced translation functions, which can be calculated by FFTand which are more sensitive to the correct translation than the traditional correlation-coefficient fast translation function. These likelihood-enhanced translation targets for molecularreplacement searches have been implemented in the program Phaser using the Computational Crystallography Toolbox (cctbx) [ABSTRACT FROM AUTHOR]

Presents the 2003 Executive Committee Report on meetings of the International Union of Crystallography. World Directory of Crystalography; List of publications; Work of the Commissions.

The problem of coincidences of planar lattices is analyzed using Clifford algebra. It is shown that an arbitrary coincidence isometry can be decomposed as a product of coincidence reflections and this allows planar coincidence lattices to be characterized algebraically. The cases of square, rectangular and rhombic lattices are worked out in detail. One of the aims of this work is to show the potential usefulness of Clifford algebra in crystallography. The power of Clifford algebra for expressing geometric ideas is exploited here and the procedure presented can be generalized to higher dimensions. [ABSTRACT FROM AUTHOR]

The crystal structures of the flavodoxin from Desulfovibrio desulfuricans ATCC 27774 have been determined and refined for both oxidized and semi-reduced forms to final crystallographic k-factors of 17.9% (0.8 -0.205-nm resolution) and 19.4 % (0.8 -0.2 15-nm resolution) respectively. Native flavodoxin crystals were grown from amnionium sulfate with cell constants a = b = 9.59 nm, c = 3.37 nm (oxidized crystals) and they belong to space group P3,21. Semireduced crystals showed some changes in cell dimensions: a = h = 9.51 nm. e = 3.35 nm. The three-dimensional structures are similar to other known flavodoxins and deviations are found essentially in the isoalloxazine ring environment. Conformational changes are observed between both redox slates and a flip of the Gly61-Met62 peptide bond occurs upon one-electron reduction of the FMN group. These changes influence the redox potential of the oxidized/ semiquinone couple. Modulation of the redox potentials is known to be related to the association constant of the FMN group to the protein. The flavodoxin from D. desulfuricans now studied has a large span between E2 (oxidized → semiquinone) and E1 (semiquinone → hydroquinone) redox potentials. both these values being substantially more positive within known flavodoxins. A comparison of their FMN environment was made in both oxidation states in order to correlate functional and structural differences. [ABSTRACT FROM AUTHOR]

The article presents information on the nomenclature of Iron-sulfur proteins. Recommendations for the nomenclature of iron-sulfur proteins were formulated in 1971 and published in 1973. Since that time. a number of major contributions to the field have reported structure determinations by X-ray crystallography, elaboration of a series of model compounds and the discovery of novel examples of these proteins.

Studies the crystals of the oxyfluorinated gallium phosphate materials of Institut Lavoisier-12 that were synthesized hydrothermally at 453 K under autogenous pressure using propane -1,3-diamine as the structure-directing agent. Reasons why microporous metal phosphates have been studied intensively; Discovery of novel oxyfluorinated extra-large-pore open-framework structures; Consideration of the concentration of the fluoride ions.

Looks into the thiocarbohydrazide (TCH) molecule. Components of the equatorial plane in the study; Observation of cis-cis conformation in TCH dihydrochloride dihydrate and TCH sulfate; Method used to synthesize some compounds.

Discusses the charge density (CD) of a chemical compound, the most information-rich observable that is available for the system Information contained in the CE on the chemical bonding as well as on physical and chemical properties; Diffraction experiments at short wavelength and low temperature; Capability of CD to define the electronic ground state of a system.

The title compound, C18H18O4, lies on crystallographic center of symmetry. Each isovanillin group makes a dihedral angle of 8.0 (4)° with the six C atoms in the central chain. The two aromatic rings are parallel to each other by symmetry. [ABSTRACT FROM AUTHOR]