粉末化学镀法制备的NiB／TiO2非晶态合金催化剂对环丁烯砜加氢反应的催化性能

 采用诱导沉积法及粉末化学镀法分别制备了纯态NiB及负载型NiB／TiO2非晶态合金催化剂．用XRD，ICP，SEM，TEM和DSC等手段对催化剂的物性及TiO2载体与NiB非晶态合金之间的相互作用进行了表征，考察了非晶态合金的结构、组成、形貌和热稳定性，并将其用于环丁烯砜加氢反应中．结果表明，相对于NiB而言，NiB／TiO2催化剂具有优良的热稳定性和催化活性，这缘于NiB和TiO2载体之间的相互作用及载体的分散作用．     

Metal-Boron Compounds – Problems and Perspectives

“True” metal-boron compounds have been known for about ten years. The bonding between the metal and boron atoms can vary widely in nature: Not only simple covalent bonds are encountered but also coordinate bonds and boron-metal multicenter bonds. Furthermore, π complexes of transition metals with boron-nitrogen systems and metal complexes containing boron(I) compounds as ligands have recently also been prepared.     

Synthesis, stereochemistry confirmation and biological activity evaluation of a constituent from Isodon excisus

A synthesis and stereochemistry confirmation of a constituent recently isolated from the whole plant Isodon excisus is reported. An enantioselective catalytic boron-mediated reduction of an α-bromoketone was utilized in the key synthetic transformation. The methodology described herein was also used for the synthesis of the natural product's enantiomer and several derivatives. In addition, the compounds were evaluated for inhibitory activity in a caspase induction assay. The natural product was found to be devoid of activity, but several derivatives had moderate inhibitory activity (EC₅₀<1 μM).     

非晶态NiP（B）／Al2O3催化一氧化碳，水和氧气合成过氧化氢

Hydrogenperoxideisagreenoxidantwithgreatpotentialformuchapplication .Thepresentproduc tionofhydrogen peroxiderequiressevereconditionsand generates pollutants .AlternativesynthesesarerequiredandthesynthesisofH2 O2 fromCO ,H2 OandO2 isverypromising .AsshowninEq(1) ,thesynthesisisthermodynamicallyfavored :CO +H2 O +O2 H2 O2 +CO2 (1)ΔG02 98=- 134kJ/mol　　ThereactionwasfirstreportedbyZudinetal[1]whousedpalladiumtriphenylphosphaneasacatalyst.Bianchietal[2 ] usedabiphasesystemforthesynthe …     

Derivatives of the closo-dodecaborate anion and their application in medicine

The paper presents a comparative analysis of the possibilities and characteristic features of the application of various polyhedral boron compounds, viz., the closo-decaborate anion [B₁₀H₁₀]^2–, the closo-dodecaborate anion [B₁₂H₁₂]^2–, the carba-closo-dodecaborate anion [CB₁₁H₁₂]^–, carboranes C₂B₁₀H₁₂, and the bis(dicarbollide) complexes [M(C₂B₉H₁₁)₂]^– (M = Fe, Co, or Ni), in boron neutron capture therapy (BNCT) for cancer. The requirements on compounds used in BNCT are formulated and the advantages of the application of the closo-dodecaborate anion are considered. The data on the synthesis of various derivatives of the closo-dodecaborate anion, which either already found use in BNCT or are most promising in this field, are summarized. The possibilities of the application of agents derived from the closo-dodecaborate anion in medical diagnostics are discussed.     

Intracellular fate of hydrocarbons

In previous work, purification procedures and zymogram analysis conducted with supernatants of crude extracts from aerobic mycelium of the YR-1 strain of Mucor circinelloides isolated from petroleum-contaminated soils indicated the existence of only one soluble alcohol oxidase (sAO) activity. In the present work enzymatic activity of alcohol oxidase (AO) was also detected in the mixed membrane fraction (MMF) of a high-speed centrifugation procedure after drastic ballistic cellular homogenization to break the mycelium from strain YR-1. When mycelial cells were gently broken by freezing the mycelium with liquid nitrogen, smashing in a mortar, and submitting the samples to an isopycnic sucrose gradients (10–60% sucrose), AO activity was detected in particular and discrete fractions of the gradient, showing specific density values quite different from the density of peroxisomes. The results suggest that there could be a different intracellular pattern of distribution of the microsomal fraction in aerobically grown mycelium depending on the carbon source used in the culture media, including alcohols and hydrocarbons, but not in glucose. In working with particulate fractions, we found two AO activities: a new membrane alcohol oxidase (mAO) activity and the sAO. Both activities appear to be located in the inner of the cells in specific compartments different from the peroxisomes, so mAO could be in the membrane of these compartments and sAO in the lumen of the vesicles. We also assayed other enzymatic activities involved in hydrocarbon biodegradation to establish its intracellular location and other enzymatic activities such as peroxidase to use them as intracellular markers of different organelles. In the case of monooxygenase, the first enzymatic step in the hydrocarbon biodegradation pathway, its location was in the same fractions where AOs were located, suggesting the existance of a specific organelle that contains the enzymatic activities involved in hydrocarbon biodegradation.     

Spectroscopic study of a magnetically rotating arc between opper electrodes in contaminated argon

The effects of N₂ and CO contaminants in atmospheric-pressure argon on an arc rotating between two concentric copper electrodes has been studied using optical spectroscopy of copper lines. The axial temperature of the magnetically driven arc in Ar + %N₂ was determined to be around 10,000 K for arc currents of SO to 200 A. The diffusion process of the copper vapor from the cathode was also studied. A copper density maximum 1 mm from the cathode along the arc column was found in Ar + %N₂. Removal of the contaminated cathode surface layers by the arc when contaminant injection in the plasma gas was stopped was found to be a slow process with a time scale depending on the type of the gas contaminant. The presence of gas contaminant in the electrode material controls the cathode erosion mechanism and the overall arc behavior in the transition between a contaminated to a pure argon arc.     

A unified orbital model of delocalised and localised currents in monocycles, from annulenes to azabora-heterocycles

Why are some (4n+2)π systems aromatic, and some not? The ipsocentric approach to the calculation of the current density induced in a molecule by an external magnetic field predicts a four‐electron diatropic (aromatic) ring current for (4n+2)π carbocycles and a two‐electron paratropic (antiaromatic) current for (4n)π carbocycles. With the inclusion of an electronegativity parameter, an ipsocentric frontier‐orbital model also predicts the transition from delocalised currents in carbocycles to nitrogen‐localised currents in alternating azabora‐heterocycles, which rationalises the differences in (magnetic) aromaticity between these isoelectronic π‐conjugated systems. Ab initio valence‐bond calculations confirm the localisation predicted by the naïve model, and coupled‐Hartree–Fock calculations give current‐density maps that exhibit the predicted delocalised‐to‐localised/carbocycle–heterocycle transition.     

Crystal structure of boron difluoride 3-phenylthiopentane-2,4-dionate. π stacking interactions and luminescence of boron difluoride acetyl acetonates

The crystal structure of boron difluoride 3-phenylthiopentane-2,4-dionate was determined. The relationship between the structure and luminescent properties is traced in the series of boron difluoride acetyl acetonates (acetyl acetonate, phenylacetyl acetonate, and phenylthioacetyl acetonate). The presence of the π stacking interactions in boron difluoride phenylthioacetyl acetonate crystals leads to increased intensity and bathochromic shift of the fluorescence band.