Cooperative effects in phospholipid monolayers induced by a peptide from HIV-1 capsid protein

The study of interactions between biological molecules and model membranes is essential for the understanding of a number of physiological mechanisms involved in viral infections and dissemination. In this paper, the analysis of the interaction between a peptide from the p24 protein of Human Immunodeficiency Virus type 1 (HIV-1) and a phospholipid monolayer has pointed to a cooperative response in which very small amounts of peptide p24-1 (e.g. 0.05 mol%) can lead to measurable effects. Monolayer surface pressure and surface potential isotherms were affected for peptide concentrations as low as 0.05 mol%, with saturation at 0.5 mol%. The expansion effect from p24-1 is confirmed by changes in morphology of the monolayers using Brewster angle microscopy. Even though p24-1 is disordered in aqueous solutions, the interaction with dipalmitoyl phosphatidylcholine (DPPC) causes it to adopt an alpha-helix structure, as shown by circular dichroism (CD) data for multilamellar vesicles (MLV). The expansion of the phospholipid monolayer in a cooperative way may imply that p24-1 has potential antiviral activity, by participating in the cell rupture, with no need of specific receptors in the membrane.     

Structural properties, conformational stability and oxygen binding properties of Penaeus monodon hemocyanin

Hemocyanin sequences allineament shows the presence of highly invariant regions especially in the active site and in the tight intersubunits interaction sites. Comparing the aminoacids in contact regions between monomers is possible to interpret the stability of hexamers.     

Rapid crack growth in a thermoelastic solid under mixed-mode thermomechanical loading

A two-dimensional steady-sate analysis of semi-infinite brittlecrack growth at a constant subcritical rate in an unboundedfully-coupled thermoelastic solid under mixed-mode thermomechanicalloading is made. The loading consists of normal and shear tractionsand heat fluxes applied as point sources (line loads in theout-of-plane direction). A related problem is solved exactly in an integral transformspace, and robust asymptotic forms used to reduce the originalproblem to a set of integral equations. The equations are partiallycoupled and exhibit operators of both Cauchy and Abel types,yet can be solved analytically. The temperature change field at a distance from the moving crackedge is then constructed, and its dominant term is found tobe controlled by the imposed heat fluxes. The role of this termis, indeed, enhanced if the heat fluxes serve to render thecrack as a net heat source/sink for the solid, as opposed tobeing a transmitter of heat across its plane. More generally,the influence of the thermoelastic coupling on this field, aswell as other functions, is found to increase with crack speed.     

甘油的催化选择氧化

综述了近年来生物柴油主要副产物甘油的催化选择氧化的研究进展。分析了甘油的化学催化选择氧化的反应网络;介绍了催化甘油选择氧化反应主要的催化剂如负载型金属催化剂、多孔催化剂以及有机酰基-TEMPO催化剂的催化性能及其催化机理;评述了甘油催化氧化过程中各反应条件等对产物选择性和反应物转化率的影响;概括了甘油的电催化氧化、甘油催化氧化聚合生成新型聚合物-聚丙酮二酸盐（Polyketomalonate）等新催化反应及其机理,总结了甘油生物催化氧化的产物二羟基丙酮（DHA）的新进展。最后提出了甘油的催化氧化存在的一些问题,并展望了甘油催化氧化的研究和发展方向。     

Coke deposition on naphtha reforming catalysts: I. Influence of the hydrocarbon feed

During hydrocarbons reactions over Pt/Al₂O₃ the catalyst is covered by coke. It is accepted that coke formation occurs on metal and acid sites. During normal heptane and methylcyclopentane reforming it was found that the nature and the rate of coke deposited on the catalyst surface was not same, depending on the structure of the hydrocarbon feed.

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Coke deposition on naphtha reforming catalysts: II. Influence of the addition of a second metal to platinum

The nature and rate of coke deposited on mono-and bimetallic reforming catalysts have been studied for normal heptane reforming. For bimetallic catalysts it has been shown that coke deposition is less extensive than on monometallic catalyst, depending on the degree of polymerization and the type of bimetallic catalyst.

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Synthetic magnetic opals

We present studies of novel nanocomposites of BiNi impregnated into the structure of opals as well as inverse opals. Atomic force microscopy and high resolution elemental analyses show a highly ordered structure and uniform distribution of the BiNi filler in the matrix. These BiNi-based nanocomposites are found to exhibit distinct ferromagnetic-like ordering with transition temperature of about 675 K. As far as we know there exists no report in literature on any BiNi compound which is magnetic.     

Organometallic complexes with biological molecules. I. Diorganotin(IV)chloro protoporphyrin IX complexes: Solid-state and solution-phase characterization

Protoporphyrin IX (H₄PPIX) complexes of diorganotin(IV)chloro moieties with formula (R₂SnCl)₂H₂PPIX (R?Me, Bu and Ph) have been obtained and their solid-state and solution-phase configurations have been studied through spectroscopic investigations. Coordination of the side-chain carboxylates of H₄PPIX to R₂Sn(IV)Cl moieties, with bridging carboxylate (COO^?) has been inferred by comparison of the free and coordinated H₄PPIX IR spectra, while the occurrence of a five-coordinated tin(IV) atom in a cis-R₂ trigonal bipyramidal structure has been deduced, for all of the synthesized complexes, by rationalization of the nuclear quadrupole splitting parameters, according to the point-charge model formalism. Fanally, the solution-phase spectral features of (R₂SnCl)₂^?H₂PPIX are in agreement with the monomeric character of the protoporphyrin IX, under the experimental conditions used.     

Chemoselective catalytic conversion of glycerol as a biorenewable source to valuable commodity chemicals

New opportunities for the conversion of glycerol into value-added chemicals have emerged in recent years as a result of glycerol's unique structure, properties, bioavailability, and renewability. Glycerol is currently produced in large amounts during the transesterification of fatty acids into biodiesel and as such represents a useful by-product. This paper provides a comprehensive review and critical analysis on the different reaction pathways for catalytic conversion of glycerol into commodity chemicals, including selective oxidation, selective hydrogenolysis, selective dehydration, pyrolysis and gasification, steam reforming, thermal reduction into syngas, selective transesterification, selective etherification, oligomerization and polymerization, and conversion of glycerol into glycerol carbonate.     

Catalytic conversion of lignocellulosic biomass to fine chemicals and fuels

Lignocellulosic biomass is the most abundant and bio-renewable resource with great potential for sustainable production of chemicals and fuels. This critical review provides insights into the state-of the-art accomplishments in the chemocatalytic technologies to generate fuels and value-added chemicals from lignocellulosic biomass, with an emphasis on its major component, cellulose. Catalytic hydrolysis, solvolysis, liquefaction, pyrolysis, gasification, hydrogenolysis and hydrogenation are the major processes presently studied. Regarding catalytic hydrolysis, the acid catalysts cover inorganic or organic acids and various solid acids such as sulfonated carbon, zeolites, heteropolyacids and oxides. Liquefaction and fast pyrolysis of cellulose are primarily conducted over catalysts with proper acidity/basicity. Gasification is typically conducted over supported noble metal catalysts. Reaction conditions, solvents and catalysts are the prime factors that affect the yield and composition of the target products. Most of processes yield a complex mixture, leading to problematic upgrading and separation. An emerging technique is to integrate hydrolysis, liquefaction or pyrolysis with hydrogenation over multifunctional solid catalysts to convert lignocellulosic biomass to value-added fine chemicals and bio-hydrocarbon fuels. And the promising catalysts might be supported transition metal catalysts and zeolite-related materials. There still exist technological barriers that need to be overcome (229 references).