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Porosidad libre en granitos alterados: Comentarios a las normas

In the present paper, the possible relation among some petrophysical properties of five types of granitic materials, whether artificially aged or not, subject to different consolidation and/or water repellent treatments, has been studied. The study indicates a good correlation among imibition values and porosity (free…

Información sobre Congresos y Seminarios. Noticias

A Theoretical and Design Analysis of the Filament-Wound Composite Pressure Vessels

Electrochemical Redox Properties of Polypyrrole/Nafion Composite Film in a Solid Polymer Electrolyte Battery

Nafion ® was introduced into a polypyrrole (PPy) matrix, and the redox performance of the PPy/Nafion electrode was investigated in a poly(ethylene oxide) ( PEO ) ‐ LiClO 4 electrolyte. A rougher interface between polymer cathode and polymer electrolyte is usually needed for an all‐solid battery, however, the PPy/Nafio…

Structure of potassium sulfate at temperatures from 296 K down to 15 K

The crystal structure of potassium sulfate, K 2 SO 4 , was studied at five temperatures from 296 down to 15 K using an off-center four-circle diffractometer. The temperature dependence of lattice constants is well explained by the Gruneisen relation. The crystal structure is confirmed to be orthorhombic, space group P…

Liquid crystal dimers and oligomers: Experiment and theory

Abstract Liquid crystal dimers and trimers exhibit a range of unusual properties which are fascinating in their own right and which also parallel those found for semi‐flexible main‐chain liquid crystal polymers. This close similarity suggests that dimers and oligomers should form good model systems for their polymeric…

Synthesis and properties of cellulose acetoacetates

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and properties of cellulose acetoacetatesK. J. Edgar, K. M. Arnold, W. W. Blount, J. E. Lawniczak, and D. W. LowmanCite this: Macromolecules 1995, 28, 12, 4122–4128Publication Date (Print):June 1, 1995Publication History Published online1 May 2002Published inissue…

Tissue Engineering: Biomedical Applications

This paper discusses a novel approach to tissue engineering involving seeding mammalian cells onto biodegradable polymer scaffolds, growing the cells on these scaffolds in vitro, and then implanting the cell-polymer constructs in vivo. Approaches for in vitro cultivation of cells are first discussed. The types of poly…

Determination of the molecular structures of tungstates by Raman spectroscopy

Abstract An empirical correlation is developed for relating the wavenumbers of (WO) stretching modes to WO bond lengths and bond strengths for tungsten oxide reference compounds. A least‐squares exponential fit of crystallographically determined WO bond lengths to the wavenumbers of their Raman stretching modes is…

EMI shielding plastics: A review

Abstract The objective of this article is to review the use of conductive plastics in the shielding of electromagnetic interference (EMI). The theory of EMI shielding and evaluation methods of EMI materials are discussed. Different approaches in achieving high conductivity of plastics are reviewed. Emphasis is placed…

Carbonaceous clusters in irradiated polymers as revealed by UV-Vis spectrometry

Carbonaceous clusters-supposed to be the carriers of electric conductivity-are formed along latent tracks of energetic ions in polymers. The different experimental techniques for cluster determination are summarized. Here we present some new results which have been derived from UV-Vis spectrometric examinations. Espec…

An overview of the basic aspects of polymer adhesion. Part I: Fundamentals

Abstract Adhesion between two substrates is a complex phenomenon which at present is still not well understood. The important existing adhesion models (electrical, diffusion, thermodynamic adsorption, chemical, etc.) are reviewed in order to try to explain their mechanisms. Thermodynamic adsorption is now believed to…

Composition Factors Affecting the Water Vapor Permeability and Tensile Properties of Hydrophilic Films

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComposition Factors Affecting the Water Vapor Permeability and Tensile Properties of Hydrophilic FilmsNicholas Parris, David R. Coffin, Remon F. Joubran, and Helmut PessenCite this: J. Agric. Food Chem. 1995, 43, 6, 1432–1435Publication Date (Print):June 1, 1995Publication H…

Biodistribution of Radiolabeled, Formulated Gadopentetate, Gadoteridol, Gadoterate, and Gadodiamide in Mice and Rats

RATIONALE AND OBJECTIVES: The authors studied the long-term distribution of gadolinium (Gd) in mice and rats after the administration of four commercially available magnetic resonance imaging contrast media. The goals were to determine any possible product dissociation in vivo and to evaluate the effects that product…

Monte Carlo Simulation of Interlayer Molecular Structure in Swelling Clay Minerals. 2. Monolayer Hydrates

Abstract Monte Carlo (MC) simulations of interlayer molecular structure in monolayer hydrates of Na-saturated Wyoming-type montmorillonites and vermiculite were performed. Detailed comparison of the stimulation results with experimental diffraction and thermodynamic data for these clay-water systems indicated good sem…

New Narrow-Bandgap Polymer Composed of Benzobis(1,2,5-thiadiazole) and Thiophenes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew Narrow-Bandgap Polymer Composed of Benzobis(1,2,5-thiadiazole) and ThiophenesMichinori Karikomi, Chitoshi Kitamura, Shoji Tanaka, and Yoshiro YamashitaCite this: J. Am. Chem. Soc. 1995, 117, 25, 6791–6792Publication Date (Print):June 1, 1995Publication History Published…

Monte Carlo Simulation of Interlayer Molecular Structure in Swelling Clay Minerals. 1. Methodology

Abstract Monte Carlo (MC) simulations of molecular structure in the interlayers of 2:1 Na-saturated clay minerals were performed to address several important simulation methodological issues. Investigation was focused on monolayer hydrates of the clay minerals because these systems provide a severe test of the quality…

Ceramic Composites of Monazite and Alumina

A new family of high‐temperature, oxidation‐resistant, ceramic composites, with (La)‐monazite (LaPO 4 ) serving as a weakly bonded interphase, is proposed. Monazite is stable and phase‐compatible with alumina at temperatures at least as high as 1750°C in air. Especially important for use in high‐toughness composites,…

Structure of Amorphous MoS3

The amorphous compound MoS3 has been investigated by monochromatic X-ray photoemission ( X P S) and vibrational spectroscopy, as well as by chemical extrusion aimed at identifying structural units inside MoS3. XPS shows that all molybdenum in MoS3 occurs in the 4-t oxidation state, while sulfur is present in at least…