Preparation of inside-out vesicles of pig lymphocyte plasma membrane

Between 30 and 50% of pig lymphocyte plasma membrane vesicles were not bound by concanavalin A (Con A)-Sepharose. Various results suggest that the Con A-unretarded fraction represents "inside-out" membrane vesicles. First, an alternative cell surface ligand, anti-lymphocytic serum, gave a similar fractionation to Con A. Second, lack of binding by Con A was not due to lack of carbohydrate or to masking of carbohydrate by extraneous protein, because the unfractionated membrane and the unretarded fraction had similar carbohydrate and polypeptide compositions. Third although the carbohydrate of the unretarded membrane vesicles was accessible to 125I-labelled Con A and to release by soluble trypsin, it was not accessible to ferritin-Con A or trypsin-Sepharose. Fourth, antisera against the external surface of the Con A-unretarded vesicles strongly agglutinated the unretarded membrane, but caused negligible agglutination of whole lymphocytes. When attached to Sepharose these antisera bound all of the Con A-unretarded fraction, but failed to bind the membrane that adhered to Con A-Sepharose.     

Thermo-Chemo-Mechanical Model for Concrete. I: Hydration and Aging

In this work a coupled thermo-chemo-mechanical model for the behavior of concrete at early ages is proposed. The model allows simulation of the observed phenomena of hydration, aging, damage, and creep. It is formulated within an appropriate thermodynamic framework, from which the state equations are derived. In this first part, the formulation and assessment of the thermochemical aspects of the model are presented. It is based on the reactive porous media theory, and it can accurately predict the evolution in time of the hydration degree and the hydration heat production. The evolution of the compressive and tensile strengths and elastic moduli is related to the aging degree, a concept introduced to account for the effect of the curing temperature in the evolution of the mechanical properties. The short- and long-term mechanical behavior is modeled by means of a viscoelastic damage model that accounts for the aging effects. The formulation and assessment of the mechanical part of the model are relegated to a companion paper.     

Multifunctional hybrid materials composed of [60]fullerene-based functionalized-single-walled carbon nanotubes

We report the synthesis and characterization of several hybrid [60]fullerene-SWCNT materials that combine [60]fullerenes with appended photoactive ferrocenyl or porphyrinyl functionalities and SWCNTs into a single multifunctional structure, where the dyads are covalently attached to the exo-surface of SWCNTs. The structural properties of all hybrids have been characterized using a large variety of spectroscopic and HR-TEM techniques. Raman spectra showed how all SWCNTs were functionalized and the presence of functional groups in the nanotube derivatives. Furthermore, these spectra reveal a new electronic activity of the compounds due to the interaction of the functional groups with the SWCNT frameworks. XPS investigations have documented the presence of [60]fullerene derivatives around the exo-surface of the oxidized SWCNT walls, exhibiting a characteristic photoelectron N 1s emission peak at 400.3 eV. Very importantly, by means of HR-TEM investigations we have also observed the presence of the [60]fullerene functions on the SWCNT outer surface by imaging spherical structures. The presence of the porphyrinyl and ferrocenyl fragments, which can act as effective chromophores and electroactive species, makes this class of materials very interesting for applications in optoelectronics and photovoltaics, and bio-applications, for example in the field of diagnosis and treatment.     

Extending the Colloidal Transition Metal Dichalcogenide Library to ReS2 Nanosheets for Application in Gas Sensing and Electrocatalysis

Among the large family of transition metal dichalcogenides, recently ReS₂ has stood out due to its nearly layer‐independent optoelectronic and physicochemical properties related to its 1T distorted octahedral structure. This structure leads to strong in‐plane anisotropy, and the presence of active sites at its surface makes ReS₂ interesting for gas sensing and catalysts applications. However, current fabrication methods use chemical or physical vapor deposition (CVD or PVD) processes that are costly, time‐consuming and complex, therefore limiting its large‐scale production and exploitation. To address this issue, a colloidal synthesis approach is developed, which allows the production of ReS₂ at temperatures below 360 °C and with reaction times shorter than 2h. By combining the solution‐based synthesis with surface functionalization strategies, the feasibility of colloidal ReS₂ nanosheet films for sensing different gases is demonstrated with highly competitive performance in comparison with devices built with CVD‐grown ReS₂ and MoS₂. In addition, the integration of the ReS₂ nanosheet films in assemblies together with carbon nanotubes allows to fabricate electrodes for electrocatalysis for H₂ production in both acid and alkaline conditions. Results from proof‐of‐principle devices show an electrocatalytic overpotential competitive with devices based on ReS₂ produced by CVD, and even with MoS₂, WS₂, and MoSe₂ electrocatalysts.     

Pregnanes that bind to the digitalis receptor

Steroid binding domains of Na,K-ATPase and the nuclear hormone receptors share amino acid sequence homologies. In a ouabain radioligand assay, the potencies of series of planar or bent steroid moieties suggest that the domain in Na,K-ATPase can accommodate compounds with a planar configuration. The A/B -cis, C/D-cis steroid configuration in the cardenolides, in conjunction with appropriate substituents at the 3 and 17 positions, may represent a fortuitous "fit" for the exogenous compounds. It remains to be determined if the putative physiological digitalis-like substance is a member of a hormonal steroid family, an endogenous ouabain-like compound or both.     

催化裂化汽油醚化改质的研究

催化裂化汽油中的 C_4～C_7叔碳烯烃在催化剂的作用下与甲醇进行醚化反应,生成对应的甲基叔烷基醚,可以有效地提高汽油的辛烷值。试验表明在60～80℃,0.8～1.0MPa 及空速为3～5h~(-1)油醇比为16～25(体)条件下,汽油中含醚在3%以上,汽油的辛烷值(RON)可以提高1.5～2.0单位。     

Spectroscopic changes induced by sonication of porphyrin-carbon nanotube composites in chlorinated solvents

We report the spectroscopic changes of tetraphenylporphyrin carbon nanotube composites in a variety of chlorinated solvents such as chloroform, dichloroethane and dichlorobenzene as a result of sonication. Detailed data analysis suggests that protonation of the porphyrin core nitrogen atoms occurs as a result of sonodegradation of the solvent molecules. Extreme care must be taken when working with carbon nanotube composite solutions in chlorinated solvents, as sonication is always employed to disperse the nanotubes. When working with molecules that are capable of acting as a base some amount of protonation is inevitable and this may dramatically change the physicochemical properties of the composite materials.