Materials Literature
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Two strategies to improve the catalytic activity of Ti-MCM-41 materials in the epoxidation of olefins are described; the first approach involves silylation of the surface of Ti-MCM-41 which produces a very hydrophobic catalyst whereas the second approach is based on removal of water from the reaction media; the increa…
The collagens are a large and diverse family of proteins which are found in the extracellular matrix. In common with one another, the 19 known collagen types have triple-helical domains of variable length but they differ with respect to their overall size and the nature and location of their globular domains. Collagen…
Practical procedures are reported for the syntheses of amine and ester-substituted silsesquioxane frameworks with the formula R8Si8O12 with R = CH2CH2CH2NH2 (2), [CH2CH2CH2NH3]Cl (3) and CH2CH2CMe2CH2CO2Me (4); the use of 2 as a core for starburst dendrimers with R = CH2CH2CH2N(CH2CH2CO2Me)2 (5) and CH2CH2CH2N(CH2CH2C…
Heating 4,7-dihydro-4,7-ethano-2H-isoindole at 200 °C induces the retro-Diels–Alder reaction to give isoindole in essentially quantitative yield, which can be applied to a new synthesis of tetrabenzoporphyrins and monobenzoporphyrins.
Monodisperse gold–polypyrrole nanocomposites, consisting of a gold nanocrystal surrounded by a shell of polypyrrole, are shown to be stabilized by diblock copolymer micelles. Annealing thin films of the gold–polypyrrole-loaded micelles above the glass transition temperature yields compact gold particles encapsulated b…
Current topics in elastomers for biomedical applications are reviewed. Elastomeric biomaterials, such as silicones, thermoplastic elastomers, polyolefin and polydiene elastomers, poly(vinyl chloride), natural rubber, heparinized polymers, hydrogels, polypeptides elastomers and others are described. In addition biomedi…
Preface. 1: Introduction. 1.1. What are porous materials? 1.2. Classification of porous materials. 2: Powder compacts and green bodies for porous materials. 2.1 .Sintering as a process for producing porous materials. 2.2. The raw powder. 2.3. Green bodies. 2.4. Pore forming agents. 3: Sintering mechanisms and advanced…
De nouveaux materiaux solides iridescents peuvent etre produits dans l'eau par simple evaporation a partir de suspensions cristallines liquides nematiques, chirales et lyotropiques faites de microcrystallites cellulosiques. Les microcrystallites sont des fragments de microfibrilles colloidalement stables produits par…
A new method of the formation of composite polypyrrole films containing a highly dispersed three‐dimensional array of platinum catalyst particles is presented. PtCl 4 2 − anions were trapped inside the polypyrrole matrix during the electropolymerization of pyrrole. In the next step followed by solution exchange, PtCl…
Monodisperse gold–polypyrrole nanocomposites, consisting of a gold nanocrystal surrounded by a shell of polypyrrole, are shown to be stabilized by diblock copolymer micelles. Annealing thin films of the gold–polypyrrole-loaded micelles above the glass transition temperature yields compact gold particles encapsulated b…
A SiO2 material with the lowest framework density (15.4 SiO2 nm–3) and the largest void volume fraction (nearly 50%) ever reported for crystalline silica polymorphs has been synthesised, and its structure solved by direct methods and fully refined using low-resolution powder X-ray diffraction data.
Chemical schemes for the preparation of direct band-gap semiconductor quantum dots have advanced rapidly over the past few years. It is now possible to prepare a variety of III–V semiconductors with a finite size (InP, InAs, GaAs, etc.) and compare their size-dependent properties with the well studied II–VI class of q…
The field of long-circulating microparticulate drug carriers is reviewed. The protective effect of certain polymers including poly(ethylene glycol) on nanoparticulate carriers (liposomes, nanoparticles, micelles) is considered in terms of statistical behaviour of macromolecules in solution. Using liposomes as an examp…
A polyester polyurethane (PUR)-degrading enzyme, PUR esterase, derived from Comamonas acidovorans TB-35, a bacterium that utilizes polyester PUR as the sole carbon source, was purified until it showed a single band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). This enzyme was bound to the ce…
Tin sulfide-based materials can exist in many forms, ranging from discrete molecular species, to 1D chains, 2D dense and porous sheets and 3D open frameworks. The local coordination geometry around a tin center may vary from trigonal pyramidal, to tetrahedral, trigonal bipyramidal and octahedral, and around sulfur fro…
The deposition of cadmium sulfide by chemical bath methods is straightforward and involves an alkaline solution of a cadmium salt, a complexant and a chalcogen source, often thiourea or thioacetamide. Supersaturation of the bath with respect to ‘Cd(OH) 2 ’ is necessary for the deposition of good quality films under a…
There has been extensive research on drug delivery by biodegradable polymeric devices since bioresorbable surgical sutures entered the market two decades ago. Among the different classes of biodegradable polymers, the thermoplastic aliphatic poly(esters) such as poly(lactide) (PLA), poly(glycolide) (PGA), and especial…
This paper reviews the recent understanding of the initiation mechanisms of electrical trees and the phenomena occurring during the induction period in the discharge free condition. The importance of charge injection in electrical tree initiation is well established, not only under dc or impulse stresses, but also und…
A general class of multipolar molecules is introduced in the context of quadratic nonlinear optics by way of extension of the more specific cases of dipolar and octupolar molecules. An adequate irreducible tensor formalism permits us to define rotationally invariant molecular features that couple to corresponding fiel…
We present molecular-dynamics simulations of the thermal glass transition in a dense model polymer liquid. We performed a comparative study of both constant volume and constant pressure cooling of the polymer melt. Great emphasis was laid on a careful equilibration of the dense polymer melt at all studied temperatures…