Mechanism of aromatic hydroxylation *1, , *2, , *3: Properties of a model for pyridine nucleotide-dependent flavoprotein hydroxylases

A model (NADH-phenazine methosulfate-O2) formally similar to pyridine nucleotide-dependent flavoprotein hydroxylases catalyzed the hydroxylation of several aromatic compounds. The hydroxylation was maximal at acid pH and was inhibited by ovine Superoxide dismutase, suggesting that perhydroxyl radicals might be intermediates in this process. The stoichiometry of the reaction indicated that a univalent reduction of oxygen was occurring. The correlation between the concentration of semiquinone and hydroxylation, and the inhibition of hydroxylation by ethanol which inhibited semiquinone oxidation, suggested the involvement of phenazine methosulfate-semiquinone. Activation of hydroxylation by Fe3+ and Cu2+ supported the contention that univalently reduced species of oxygen was involved in hydroxylation. Catalase was without effect on the hydroxylation by the model, ruling out H2O2 as an intermediate. A reaction sequence, involving a two-electron reduction of phenazine methosulfate to reduced phenazine methosulfate followed by disproportionation with phenazine methosulfate to generate the semiquinone, was proposed. The semiquinone could donate an electron to O2 to generate O2 which could be subsequently protonated to form the perhydroxyl radical.

From the {Cu(μ2-S)N}4 butterfly architecture to the {Cu(μ3-S)N}12 double wheel

Copper(I) complexes with {Cu(μ2-S)N}4 and {Cu(μ3-S)N}12 core portions of butterfly-shaped or double wheel architectures have been isolated in the reaction of Cu(I) with the Schiff base ligand C6H4(CHNC6H4S)2, aiso-abtâ, under different conditions. View the MathML source containing the tetranuclear electroneutral complex View the MathML source is formed by the reaction of CuI in acetonitrilic solution and recrystallization from DMF, whereas View the MathML source containing dodecanuclear View the MathML source wheels is accessible starting from CuBF4. Complexes 2 and 4 represent the first examples of cyclic complexes with the same overall stoichiometry but different ring sizes. The ligand induces two different coordination environments around copper(I) by switching between μ2- and μ3-sulfur bridging modes.

H-1 MAS NMR study of protonic conduction in layered HNbWO6 center dot xH(2)O (x=1.5, 0.5)

H-1 Magic Angle Spinning (MAS) NMR of layered HNbWO6 . xH(2)O (x = 1.5, 0.5) is carried out at room temperature and at various spinning speeds (1-12 kHz). Results on the fully hydrated sample (x = 1.5) are consistent with the model of diffusion of H3O+ ions within the layers. In the partially dehydrated sample (x = 0.5) an exchange between the distinctly present cage protons and H3O+ protons leads to protonic conduction.

Raman study of pressure-induced structural transitions in CsIO4 to 12 GPa

High pressure Raman scattering studies have been carried out on cesium periodate (CsIO4) using the diamond anvil cell. Three pressure-induced phase transitions occur in the range 0.1�12 GPa as indicated by abrupt changes in the Raman spectra, and pressure dependence of the phonon frequencies. The transitions are observed at 1.5, 4.5 and 6.2 GPa in the increasing pressure cycle. A large hysteresis is noticed for the reverse transition when releasing the pressure. The high pressure phase is nearly quenchable to ambient pressure. The nature of the pressure-induced transitions are discussed in terms of the sequence of pressure-induced transitions expected for scheelite-pseudoscheelite structure ABO4 compounds from crystal chemical considerations. For the softening of the two high frequency internal modes, a pressure-induced electronic change involving the 5 d states of cesium and 5 p states of iodine is invoked.

Uso de imagens de satélite de alta resolução (GeoEye-1) para estimativa de acúmulo de carbono em alagados de Mata Atlântica em recuperação na Reserva Ecológica Guapiaçu (Cachoeiras de Macacu, Rio de Janeiro)

Áreas alagadas são importantes devido à grande biodiversidade que sustentam e aos serviços ambientais gerados pela sua conservação. Essas áreas, quando dominadas por macrófitas, tendem a suportar grande biodiversidade e assumir grande valor de conservação. Assim, o monitoramento do estabelecimento deste importante componente do ecossistema durante um projeto de recuperação de ecossistemas é importante para avaliar o sucesso da sua recuperação. Este trabalho teve como objetivo estimar aquantidade de biomassa por área acumulada em um ecossistema ao longo de um gradiente de recuperação. Através da classificação não supervisionada gerada a partir de de imagens de satélite de alta resolução (GeoEye-1) e amostragem destrutiva foram estimadas quantidades de biomassa por área em três alagados em recuperação na Reserva Ecológica Guapiaçú. A classificação não supervisionada se mostrou uma ferramenta acurada e eficiente no mapeamento de classes de vegetação. Os alagados estudados apresentam uma taxa de acúmulo de carbono anual estimada em 1,12 MgC.hec-1 atingindo um máximo de 5.55 MgC.hec-1 no terceiro ano. Adicionalmente, foi observada uma correlação negativa entre biomassa e profundidade.

Dibenzocyclooctadiene Lignans from Schisandra wilsoniana and Their Anti-HIV-1 Activities

Twelve new dibenzocyclooctadiene lignans, marlignans A-L (1-12), together with 16 known compounds, were isolated from the leaves and stems of Schisandra wilsoniana. The structures of 1-12 were elucidated by spectroscopic methods including 1D- and 2D-NMR techniques. Compounds 1-12 were evaluated for their anti-HIV activities, of which compounds 3, 6, 8, and 12 showed modest activities with therapeutic index values of 13.2, 15.6, 17.6, and 16.4, respectively.

银额果蝇的B染色体研究 1: 昆明群体的Bs数目和频率

银额果蝇昆明群体有丝分裂中期核型中存在B染色体, 出现频率为69.1%在已 研究过的来自各个地区的银额果蝇中, 昆明群体的B染色体频率最高。B染色体 数目为1—6条。该群体内单雌系间的B染色体数目不同, 个体间和细胞间的B染色 体数目也不同。在核型中, B染色体最小, 形态稳定, 点状, C-带和G-带呈阳性 。 图版1图2表1参12

12 W high efficiency single frequency ring laser

Single-frequency output power of 12 W at 1064 nm is demonstrated. Pumped by a fiber-coupled diode laser, the Nd:YVO4 produces 58.6% of the slope efficiency with respect to absorbed pump power, and 52.7% of the optical-optical efficiency and nearly diffraction-limited output with a beam quality parameter of M-2 approximate to 1.11. To the best of our knowledge, this is the highest slope efficiency and optical-optical efficiency in single-frequency Nd:YVO4 ring laser. The slope efficiency of the single frequency laser is close to the limit of the efficiency. [GRAPHICS] output spectrum of the single-frequency Nd:YVO4 ring laser

12-钼磷酸四丁基铵杂多蓝的光化学合成表征与晶体结构

用450W高压汞灯照射H3PMo12O40·5H2O和（Bu4N）Br（TBA）的DMF（N,N-二甲基甲酰胺）溶液,合成了12-钼磷酸四丁基铵杂多蓝（Bu4N）4[PMo12O40]·2DMF·H2O,用元素分析,IR,固体漫反射电子光谱,ESR,XPS和CV等进行了表征。晶体结构分析表明,标题化合物属单斜晶系,空间群P21/c,晶胞参数a=14.124（3）,b=17.481（4）,c=22.744（5）A,β=101.66（3）°,V=5500（2）A3,C70H160Mo12N6O43P,Mr=2956.29,Z=2,Dc=1.785g/cm3,F（000）=2970,μ（MoKα）=1.412mm-1,R=0.0638,wR=0.1975。标题化合物是由4个四丁基铵阳离子、1个12-钼磷混合价杂多阴离子[PMo12O40]4-、2个DMF分子和1个水分子构成。

橘红色发光的八羟基喹啉锌和1,4-二乙烯基苯的交替共聚物

经由配位聚合反应 ,合成了八羟基喹啉锌和 1 ,4 二乙烯基苯的交替共聚物。所合成的聚合物通过元素分析和红外光谱进行了表征。在 36 5nm的紫外光照射下 ,聚合物呈现强的橘红色发光 ,在乙氰溶液中的最大发光峰位在 5 71nm。热失重分析表明 ,这种含Znq2 的聚合物具有稳定的热力学性质 ,热失重 5 %的温度大于 4 39℃。这种聚合物的电致发光性质正在研究中

杂多酸的固载化Ⅲ．溶剂对H_4SiW_（12）O_（40）·24H_2O在活性

研究了Ｈ＿４ＳｉＷ＿（１２）Ｏ＿（４０）·２４Ｈ＿２Ｏ（ＳｉＷ＿（１２））在水、乙醇、乙酸、乙酸丁酯中在活性炭上的吸附得出，活性炭微孔结构对ＳｉＷ＿（１２）在其表面的吸附起着分子筛作用。水溶剂化的ＳｉＷ＿（１２）分子可顺利进入活性炭１．７ｎｍ左右的微孔，而其它溶剂化的ＳｉＷ＿（１２）分子，则需较大的孔径。提出了ＳｉＷ＿（１２）在活性炭表面吸附的微孔中孔扩散模型。

同多酸和杂多酸修饰微电极的电化学研究——Ⅳ.1:2-磷钼杂多酸薄膜修饰碳纤维微电极的制备和电化性质

本文报道了1:12-磷铜杂多酸(PMo_(12)薄膜修饰碳纤维(CF)微电极的制备及其电化学性质。采用简单,快速的浸渍吸附制备的PMo_(12)薄膜修饰CF电极在酸性介质中具有很高的稳定性和氧化还原活性,电解质溶液的pH值和扫描电位范围对PMo_(12)膜的稳定性和电化学性质产生较大的影响。另一方面,PMo_(12)薄膜修饰CF微电极对酸性水溶液中的PMo_(12)和氯酸根离子(ClO)_3~-)的电催化还原作用也进行了描述。

WASP-26b: a 1-Jupiter-mass planet around an early-G-type star

We report the discovery of WASP-26b, a moderately over-sized Jupiter-mass exoplanet transiting its 11.3-mag early-G-type host star (1SWASP J001824.70-151602.3; TYC 5839-876-1) every 2.7566 days. A simultaneous fit to transit photometry and radial-velocity measurements yields a planetary mass of 1.02 ± 0.03 MJup and radius of 1.32 ± 0.08 RJup. The host star, WASP-26, has a mass of 1.12 ± 0.03 M? and a radius of 1.34 ± 0.06 R? and is in a visual double with a fainter K-type star. The two stars are at least a common-proper motion pair with a common distance of around 250 ± 15 pc and an age of 6 ± 2 Gy.

A Theoretical and Experimental Study of Resonance in a High Performance Engine Intake System: Part 1

The unsteady gas dynamic phenomena in engine intake systems of the type found in racecars have been examined. In particular, the resonant tuning effects, including cylinder-to-cylinder power variations, which can occur as a result of the interaction between an engine and its airbox have been considered. Frequency analysis of the output from a Virtual 4-Stroke 1D engine simulation was used to characterise the forcing function applied by an engine to an airbox. A separate computational frequency sweeping technique, which employed the CFD package FLUENT, was used to determine the natural frequencies of virtual airboxes in isolation from an engine. Using this technique, an airbox with a natural frequency at 75 Hz was designed for a Yamaha R6 4-cylinder motorcycle engine. The existence of an airbox natural frequency at 75 Hz was subsequently confirmed by an experimental frequency sweeping technique carried out on the engine test bed. A coupled 1D/3D analysis which employed the engine simulation package Virtual 4-Stroke and the CFD package FLUENT, was used to model the combined engine and airbox system. The coupled 1D/3D analysis predicted a 75 Hz resonance of the airbox at an engine speed of 9000 rpm. This frequency was the induction frequency for a single cylinder. An airbox was fabricated and tested on the engine. Static pressure was recorded at a grid of points in the airbox as the engine was swept through a speed range of 3000 to 10000 rpm. The measured engine speed corresponding to resonance in the airbox agreed well with the predicted values. There was also good correlation between the amplitude and phase of the pressure traces recorded within the airbox and the 1D/3D predictions.