Materials Literature
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Superconducting magnesium diboride films with Tc0 ~ 24 K and sharp transition \~ 1 K were successfully prepared on silicon substrates by pulsed laser deposition from a stoichiometric MgB2 target. Contrary to previous reports, anneals at 630 degree and a background of 2x10^(-4) torr Ar/4%H2 were performed without the r…
Peer reviewed: Yes
Dendrimers are a new class of polymeric materials. They are highly branched, monodisperse macromolecules. The structure of these materials has a great impact on their physical and chemical properties. As a result of their unique behaviour dendrimers are suitable for a wide range of biomedical and industrial applicatio…
Interfacial electron transfer (ET) between semiconductor nanomaterials and molecular adsorbates is an important fundamental process that is relevant to applications of these materials. Using femtosecond midinfrared spectroscopy, we have simultaneously measured the dynamics of injected electrons and adsorbates by direc…
In this feature article, the methods of obtaining various mesostructures made of nanocrystals are described. With silver and silver sulfide, the nanocrystals are able to self organize in 2D and 3D super lattices to form “supra” crystals. With cobalt and ferrites nanocrystals, it has been possible to make ribbons, dots…
Abstract Starlike block copolymers of Nylon‐6 and polyurethane were synthesized using ε‐caprolactam as a monomer, caprolactam magnesium bromide as a catalyst, and a star prepolymer of polyurethane. These copolymers were compared with the linear block copolymers of Nylon‐6 and polyurethane. Such copolymers were obtaine…
Abstract Transesterification of polymer blends containing polyesters is often utilized to improve the interfacial adhesion and mechanical properties of a phase‐separated blend. However, in some circumstances, the transesterification can also modify the morphology (crystallinity or liquid crystallinity) of the blend co…
The new mineral raadeite, Mg 7(PO4)2(OH)8, was found in nodules of apatite + Mg-phosphates within the Tingelstadtjern serpentinite body, Modum district, Norway. It occurs as veinlets, a few tens of µ m wide, crosscutting althausite crystals; also as rare, up to 150 µ m large anhedral inclusions in holtedahlite; and wi…
Abstract The cationic grafting of isobutylene, styrene, α‐methylstyrene, and β‐pinene from a poly(vinyl chloride) (PVC) backbone was investigated. Grafting‐from was induced by Et 2 AlCl in 1,2‐dichloroethane and methylene dichloride solutions from 20 to −70 °C. The effects of temperature and proton trap [2,6‐di‐ tert…
CDP-ribitol synthase is a bifunctional reductase and cytidylyltransferase that catalyzes the transformation of D-ribulose 5-phosphate, NADPH, and CTP to CDP-ribitol, a repeating unit present in the virulence-associated polysaccharide capsules of Haemophilus influenzae types a and b [Follens, A., et al. (1999) J. Bacte…
Abstract A system has been developed for studying the biodegradation of natural and synthetic polymeric material. The system is based on standard methods developed by the European Committee for Standardisation (CEN TC 261) (ISO/DIS 14855) and the American Society of Testing Materials, ‘ASTM Standard Test Method for De…
Abstract An effective quaternary catalyst consisting of trialkyl aluminum, phosphoric acid, electron donor, and water for ring‐opening polymerization of epichlorohydrin (ECH), as well as its copolymerization with ethylene oxide (EO), propylene oxide (PO), and allyl glycidyl ether (AGE) to obtain elastomers, were studi…
Abstract Poly(vinyl chloride) was blended with acrylic rubber over a range of compositions (5–40 wt % of the rubber), using a twin‐screw extruder. Morphological properties of the blends were investigated as a function of rubber content and blending temperature, using a scanning electron microscopy. The mechanical prop…
Abstract The safety of canned foodstuffs should be evaluated not only by recognition of functional foods but also by the presence of toxicants in the human diet. In this study, the anodic dissolution of tin in 3.5% NaCl solution with and without 25–100 m M glycine, serine, methionine, vitamin C and some of their binar…
Abstract The structure, processing, morphology, and property relationships of biaxially drawn isotactic polypropylene (BOPP) film of mixed metallocene isotactic PP (m‐iPP) and Ziegler–Natta iPP (ZN‐iPP) homopolymer compositions are developed. The DSC and film drawing behavior show cocrystallization of the ZN‐iPP and m…
We present momentum-dependent measurements of the loss function of bulk samples of concentric-shell fullerenes using electron-energy-loss spectroscopy in transmission. It is shown that the $\ensuremath{\pi}$ and $\ensuremath{\pi}+\ensuremath{\sigma}$ plasmons of these so-called carbon onions exhibit a significant mome…
Abstract Constitutive equations are derived for the nonlinear viscoelastic behavior of amorphous glassy polymers. The model is based on the theory of cooperative relaxation in a version of the trapping concept. Stress–strain relations are applied to fit experimental data for polycarbonate in the sub‐yield and post‐yie…
Reductive homocoupling of chlorobenzenes to the respective biphenyls affords high yields (93–95%), in the presence of catalytic PEG-400 and 0.4 mol % of a recycleable, heterogeneous trimetallic catalyst (4% Pd, 1% Pt, and 5% Bi on carbon). The competing reduction process is minimized. The catalytic cycle is completed…
We have measured and analyzed optical and x-ray-absorption spectra of CdS nanocrystals grown by solid-state reaction in a borosilicate glass, with average crystallite radii from 1.4 to 5 nm. The first (Cd-S) and second (Cd-Cd) neighbor distances are within 0.2% of the bulk values in all cases. We establish an upper bo…
Transmission electron microscopy (TEM) techniques were employed to in situ study the electron-beam induced dehydration of brucite Mg(OH)2. Under the electron beam, the hexagonal platelets of brucite immediately decompose and show a morphological shrinkage of 5% and 10–20% in the a and c directions, respectively. The v…