Materials Literature
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The addition of tetraalkylammonium cations to aqueous silicate solutions enhances the abundance of symmetric, cagelike, polysilicate anions including the cubic octamer, Si(8)O(20)(8)(-). The equilibrium ratio of tetramethylammonium (TMA) cations to the octameric silicate anion is 8:1 for solutions with a concentration…
Earlier studies involving water-mediated transformations in lysozyme and ribonuclease A have shown that the overall movements in the protein molecule consequent to the reduction in the amount of surrounding water are similar to those that occur during enzyme action, thus highlighting the relationship among hydration,…
Enzymatic ring-opening polymerization and copolymerization of a nine-membered lactone, 8-octanolide (8-OL), was performed in isooctane by using various lipases of different origin as catalyst. The polymerization behavior greatly depended on the lipase origin. Candida antarctica and Pseudomonas cepacia lipases (lipases…
We have used photon correlation spectroscopy and quartz crystal microbalance techniques to examine the relaxation dynamics of ultrathin $(h<400\AA{})$ polystyrene films in both supported and freely standing geometries. These studies probe relaxation dynamics of polymer films in which the glass transition temperatur…
A subdivision of the stability region of decagonal Al-Co-Ni quasicrystals into eight different structural modifications is presented for the temperature against composition section along the maximum extension of the decagonal phase. The only methods identifying this subdivision are transmission electron microscopy tec…
Direct mapping of the interface between parathyroid hormone (PTH) and its receptor (hPTH1-Rc) was carried out by photoaffinity scanning studies. Photoreactive analogs of PTH singularly substituted with a p-benzoylphenylalanine (Bpa) at each of the first six N-terminal positions have been prepared. Among these, the ana…
The inhibition of carbon steel in solutions of mixtures of calcium- and zinc-gluconate with sodium benzoate was investigated in the temperature range from 25° to 60°C, under atmospheric conditions in stagnant solutions prepared with the tap water. The efficiency and the mechanism of inhibition were estimated by potent…
Pergularia daemia (Forsk.) Chiov. (Asclepiadaceae), a wild plant of the arid zone of Rajasthan, hasdemonstrated significant antiinflammatory, antipyretic and analgesic activities including the release of prostaglandin. © 1998 John Wiley & Sons, Ltd.
Direct reactions of nickelocene and manganocene with molten pyrazoles in an inert atmosphere or under vacuum have led to the isolation of the following metal pyrazolate compounds: [Ni(4-Xpz) 2 ] x (where X = H, Cl and pz = pyrazolate); [M(4-Xdmpz) 2 ] x (where X = H, CH 3 , Cl, Br and M = Ni, Mn anddmpz = 3,5-dimethyl…
Surface-enhanced Raman imaging (SERI) has recently been developed as a surface imaging technique that is chemically selective, has monolayer sensitivity and can be used under ambient pressure conditions. At present, the resolution is 1–2 μm. A particularly interesting application is to image patterned self-assembled m…
Abstract Whereas pultrusion with thermoset resins has been widely analyzed, there is a scarcity of knowledge about pultrusion with thermoplastic resins. The aims of this work were to strive towards deeper knowledge of temperature distribution and degree of crystallinity in the composite during processing, to develop a…
In order to reveal the effect of grain boundaries (GBs) on cyclic deformation, the cyclically saturated dislocation patterns within grains and in the vicinity of GBs in a copper bicrystal with a large-angle GB and a copper multicrystal containing small-angle GBs have been observed by the electron channelling contrast…
Abstract One-photon excitation of one of the two porphyrins within porphyrin-tetracyanoanthraquinodimethane-porphyrin triad with picosecond laser pulse leads to single reduction of the acceptor by intramolecular electron transfer, while an additional delayed excitation of the non-excited porphyrin results in double re…
The isothermal problem of a mode I fracture of a shape memory alloy (SMA) plate is considered. Although the plate material is in the austenitic phase at a reference temperature, the martensitic transformation is triggered by high effective stresses at the tip of the crack. The phase transformation is accompanied by a…
Abstract A method is presented for assessment of lifetime of polyethylene pipes undergoing thermal oxidation (Stage III failure) based on oxidation induction time ( OIT ) data obtained by DSC. The method requires pressure testing for limited time periods, sampling from unexposed and exposed pipes, the establishment of…
The structures formed after the implantation of carbon in thermal SiO2 and annealing presented visible photoluminescence (PL) bands at room temperature. The peak and intensity of PL bands depended strongly on the temperature of annealing. In addition, very weak PL bands were observed after the implantation of argon in…
The new quaternary compounds Cs2AgVS4, K2AgVSe4, Rb2AgVSe4, Rb2AgNbS4, and Cs2AgNbSe4 were prepared using the reactive flux method. In this structure type infinite chains of edge-sharing AgQ4- and MVQ4-tetrahedra are running parallel to the crystallographic a-axis. The chains are separated by alkali cations. A linear…
The molten‐salt method has been used for low‐temperature synthesis of ceramic compounds. It has been used in the present work to determine the phase diagram of the TiO 2 ‐SnO 2 system down to 400°C, which is not possible by the conventional solid‐state annealing method. LiCl‐KCl eutectic has been used as the molten sa…
A new family of multi-block copolymers having the structure of poly(ester-carbonate)s was obtained by a chain-extension reaction involving poly(lactic-glycolic acid) oligomers (PLGA) and oligomeric α,ω-bishydroxy-terminated poly(ϵ-caprolactone)s (PCDT). The latter were first transformed into α,ω-bis(chloroformate)s, w…
A new isocyanate monomer was synthesized which contains an azobenzene dye connected to the isocyanate group via a chiral spacer. Copolymers with the achiral hexyl isocyanate were prepared by anionic polymerization with NaCN. CD measurements in solution show that the chiral center in the spacer induces a shift in the e…