Pharmaceutical performance of solid dispersions containing poly(ethylene) glycol 6000 and diazepam or temazepamInfluence of grinding

The effect of grinding on the physical properties and pharmaceutical performance of solid dispersions made of poly(ethylene) glycol 6000 (PEG6000) and temazepam or diazepam was studied using differential scanning calorimetry (DSC), X-ray powder diffraction and dissolution experiments. DSC-analysis of flash-cooled dispersions revealed that amorphous PEG present immediately after grinding crystallised upon aging mainly into the twice folded modification and to a small extent into the extended form. DSC-analysis of dispersions kept in the slab form for 1 month and subsequently ground, revealed that in the abscence of the grinding impulse crystallisation of PEG6000 takes place in the same way as in dispersions ground immediately after preparation and then aged for 1 month. Grinding solid dispersions immediately after preparation resulted in superior dissolution properties compared with solid dispersions kept in the monolith-slab form and subsequently ground. This difference in dissolution properties was found to be attributed to the drug and not to the polymer, more precisely, it was suggested that the drug particle size in ground dispersions was smaller than in dispersions kept in the slab form and subsequently ground. These findings suggest that grinding of solid dispersions immediately after preparation is the preparation method of choice instead of liquid filling of hard gelatin capsules resulting in monoliths. This revised version was published online in July 2006 with corrections to the Cover Date.     

Liquid fluidized bed starter culture ofTrichoderma reesei for cellulase production

A starter culture ofTrichoderma reesei (Rut-C30) prepared in a liquid fluidized bed reactor (LFBR) gave better growth and greater cellulase production in submerged fermentation than a conventional shake flask inoculum. The LFBR starter was prepared by first coatingT. reesei spores to 0.25 mm size corncob (1.0x10⁸g^-1) in a medium containing 1.0% corncob, 0.5 gL^-1 xylose and 0.1 gL^-1 lactose in a balanced salt solution, then fluidizing the particles in the LFBR for 36 h to allow germination of the spores, and covering the particles with an approx 30 μm thick biofilm. This biofilm that developed in constant adherence to the lignocellulosic carrier, apparently became well adapted to grow rapidly on insoluble cellulose substrates (Solca Floc), and had the enzymes of the cellulase complex induced for increased cellulase production. The LFBR starter used in a stirred tank reactor (STR) gave 15 gL^-1 biomass production and 6.5 IU mL^-1 overall cellulase activity with a volumetric productivity of 64 IU L^-1h^-1 in a 5 d fermentation, compared with a 7 d shake flask inoculum that gave 11 gL^-1 biomass and 3.2 IU mL^-1 cellulase activity, with a volumetric productivity of 31IU L^-1h^-1. The LFBR starter culture retained its viability in dry storage for 6–9 mo.     

Catalytic Active Site for NO Decomposition Elucidated by Surface Science and Real Catalyst

Comprehensive studies combining surface science and real catalyst were performed to get further insight into catalytic active site and reaction mechanism for NO decomposition over supported palladium and cobalt oxide-based catalysts. On palladium single-crystal model catalysts, adsorption, dissociation and desorption behavior of NO was found to be closely related to the surface structures, the stepped surface palladium being active for dissociation of NO. In accordance with this result, the activity of powder Pd/Al₂O₃ catalysts for NO decomposition was directly related to the number of step sites exposed on the surface, suggesting that the step sites act as the catalytic active site for NO decomposition on Pd/Al₂O₃. NO decomposition over cobalt oxide was found to be significantly promoted by addition of alkali metals. Surface science study and catalyst characterization led to the same conclusion that the interface between the alkali metal and Co₃O₄ serves as the catalytic active site. From the results of in situ Fourier transform infrared (FT-IR) spectroscopy and isotopic transient kinetic analysis, a reaction mechanism was proposed in which the reaction is initiated by NO adsorption onto alkali metals to form NO₂⁻ species and then NO₂⁻ species react with the adsorbed NO species to form N₂ over the interface between the alkali metal and Co₃O₄.     

The Crystal Structure of Trimethyl Borate by Neutron and X‐ray Powder Diffraction

The crystal structure of one of the simplest organoboron compounds, trimethyl borate does not appear to have been determined hitherto. The compound is of interest for the study of π‐donor ligands and their interaction with the π‐acceptor behavior of trigonal boron and the consequences of such interactions on molecular structure. We used powder neutron (with isotopically labeled material) and X‐ray diffraction to determine the crystal structure of trimethyl borate at 15 K and 200 K (neutron) and 200 K (X‐ray). The material is hexagonal (Z = 2) with a = b = 6.950(8) Å and c = 6.501(3) Å at 15 K. The unit cell volume is 272.00(1) ų. The space group is P6₃/m (SG 176) at 15 K and 200 K. This is the first crystal structure solved on the Neutron Powder Diffractometer (NPDF) at the Lujan Center.     

Synthesis of non-equilibrium PtxOs1−x Solid solutions. Crystal structure of [Pt(NH3)4][OsCl6]

Several non-equilibrium solid solutions belonging to the platinum-osmium systems Os_0.9Pt_0.1, Os_0.8Pt_0.2, Os_0.5Pt_0.5, Os_0.7Pt_0.3, Os_0.75Pt_0.25 are prepared and studied. The thermal decomposition of [Pt(NH₃)₄][OsCl₆] in the hydrogen and helium atmosphere is investigated. It is found that the Pt_0.5Os_0.5 solid solution develops through the formation of (NH₄)₂[OsCl₆] and a metallic phase based on Pt. The crystal structure of a double complex salt [Pt(NH₃)₄][OsCl₆] is studied (X8-APEX Bruker, 1508 independent reflections, R = 2.04%). Crystal data for PtOsN₄Cl₆H₁₂ are: a = 11.6216(5) Å, b = 11.0016(5) Å, c = 10.3819(5) Å, V = 1327.4(1) ų, space group Cmca, Z = 4, d _x = 3.333 g/cm₃. The coordination polyhedron around Os is octahedral: 〈Os-Cl〉 2.357 Å, ∠Cl-Os-Cl 89.5–90.5°, while around Pt it is square-planar: Pt-N 2.046 Å, ∠ N-Pt-N 89.59° and 90.41°.     

纳米级TiO2粉体的制备研究——Ⅱ.絮凝剂及其浓度的影响

采用溶胶-凝胶-超临界流体干燥(SCFD)法制备纳米级TiO₂超细粉，详细考察了不同絮凝剂及其浓度对TiO₂织构和结构性质的影响。结果表明，利用强碱溶液作为絮凝剂，浓度为5 mol·L^-1是制备大孔高比表面TiO₂超细粉较为适宜的条件。     

Untersuchungen im System LaI2/H2: Phasenverhältnisse und Fehlordnung

Investigation of the LaI₂/H₂ System: Phase Relations and Stacking Disorder Heating of LaI₂ under 1 bar hydrogen pressure to 650 °C leads to light gray LaI₂H_0.95(3), accompanied by a structural change from tetragonal to hexagonal. Sharp reflections in the XRD pattern can be indexed in P6₃/mmc with a = 4.2158(7)Å and c = 15.508(3)Å, however, diffuse reflections indicate the presence of stacking faults in the structure, which correspond to a polytypic intergrowth of MoS₂ and NbS₂ type structural fragments. Increasing the reaction temperature to 730 °C results in a better defined diffraction pattern with the peak positions close to those of the 2H‐NbS₂ structure type. An X‐ray powder study of the samples LaI₂H_n proved the miscibility gap between LaI₂ and LaI₂H_n (0 ≤ n ≤ 0.5) in agreement with previous results. With decreasing H‐content of the homogeneous phase the lattice parameters change in opposite direction, a increasing to 4.236(1)Å and c decreasing to 15.39(2)Å for the lower limit.     

固固相反应合成牛磺酸水杨醛钾与锑、铋的配合物

合成了牛磺酸水杨醛钾,并采用室温固固相反应法合成了牛磺酸水杨醛钾与三氯化锑和三氯化铋的配合物,其组成为:K2MC18H20O8N2S2 (M = Sb, Bi)。两种配合物的晶体结构均属于单斜晶系,锑配合物的晶胞参数为:a = 1.2869 nm, b = 1.7636 nm, c = 1.9917 nm, β= 93.79埃活榕浜衔锏木О问篴 = 1.4770 nm, b = 2.0334 nm, c = 2.0149 nm, β= 94.05。红外光谱表明N、Cl原子参与了配位,中心离子的配位数为5。     

Magnesium substitution in Nd0.7Sr0.3MnO3

Magnesium substitution in Nd_0.7Sr_0.3MnO₃ has been studied by neutron powder diffraction. Polycrystalline samples of nominal compositions Nd_0.7Sr_0.3Mn_1−yMg_yO₃ with y=0.0, 0.1, 0.2 and 0.3 were synthesized by the standard solid-state reaction method. Rietveld refinements of the neutron powder diffraction data showed that all samples had distorted perovskite structure of orthorhombic symmetry. Mg initially preferred to substitute for Nd and only at Mg concentration greater than 0.1, a substantial substitution for Mn occurred. Our study also showed that Mg-substitution did not change the crystal structure of Nd_0.7Sr_0.3MnO₃.     

Crystal structures and phase transition in the system SrTiO3-La2/3TiO3

The distribution of A-site cations in the perovskite system La_xSr_1−3x/2TiO₃ depends on the concentration of La³⁺ ions and associated vacancies. For small x (x?0.2), the substitutions are expected to be random. For x?0.55, the cations are ordered in such a way that successive layers of A-sites are occupied to greater and lesser degree, and this ordering drives a tetragonal distortion. For x from about 0.3 to 0.5, the X-ray patterns show diffuse peaks indicative of similar ordering, but this is not long-range order and no tetragonal distortion results. The lower temperature structures also exhibit out-of-phase tilting of the TiO₆ octahedra, setting in at temperatures varying linearly with composition from 105 K for x=0, to about 650 K at x=2/3.