Materials Literature
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The gene encoding citrate synthase from a novel bacterial isolate (DS2-3R) from Antarctica has been cloned, sequenced and over expressed in Escherichia coli. Both the recombinant enzyme and the native enzyme, purified from DS2-3R, are cold-active, with a temperature optimum of 31 degrees C. In addition the enzymes are…
Abstract Mixtures of nematic 4-cyano-4′-pentylbiphenyl and (R)-2,2′-dihydroxy-1,1′-binaphthyl-condensed fulgide derivatives form stable cholesteric liquid crystalline states. Photochromic reactions of them induced the change of their cholesteric pitch reversibly.
Pyruvate kinase M1, a non-allosteric isozyme, was converted into an allosteric enzyme by replacement of an amino acid in the intersubunit contact. The substitution of Ala-398 with Arg resulted in the pronounced allosteric enzyme. The Hill coefficient and the substrate concentration giving one-half of Vmax for the muta…
Previous studies have shown that both polyester and polyether-based polyurea-urethanes are susceptible to cleavage by hydrolytic enzymes. Furthermore, it has been hypothesized that the degree of hard segment micro-domain formation in polyurethane materials, as well as its structure, influences the ability of enzymes t…
An experimental study is presented of the behavior of a molten contact line under conditions which simulate what happens when a molten droplet touches a subcooled solid, spreads partly over it, and freezes. We restrict our attention to the case where the solid and melt are of the same material and have approximately t…
Ultraviolet-induced densification in fused silica is investigated using birefringence measurements to detect compaction-induced strain. This technique is capable of measuring compaction in the 10 parts per billion range in cm-sized specimens. A universal relation describing ultraviolet-induced compaction is discovered…
A large variety of pure and cobalt‐substituted nickel hydroxides of well‐controlled chemical composition, particle size, and morphology have been prepared and characterized by x‐ray, transmission electron microscopy, electrochemical, and Raman spectrometry studies. The hydroxide particle size and its Co‐substituted co…
Extremely transparent and conductive ZnO:Al thin films were successfully prepared by a photo-assisted metalorganic chemical vapor deposition (photo-MOCVD) technique at a temperature of 140° C using diethylzinc and H 2 O as source materials. The vapor from an aqueous solution of aluminum chloride hydrate ( AlCl 3 (6H 2…
The structures of ${\mathrm{B}}_{12}{\mathrm{As}}_{2},$ ${\mathrm{B}}_{12}{\mathrm{P}}_{2},$ ${\mathrm{B}}_{12}{\mathrm{O}}_{2},$ and ${\mathrm{B}}_{12+x}{\mathrm{C}}_{3\ensuremath{-}x}$ $(0.15<x<1.65)$ may each be viewed as composed of ${\mathrm{B}}_{12}$ or ${\mathrm{B}}_{11}\mathrm{C}$ icosahedra and As-As, P…
Abstract The uniform structure of cellulose, combined with its hydrophilicity, biocompatibility, chirality, and structure‐forming capacity, as well as its broad synthetic potential, make the design of cellulose‐based advanced materials a challenge for polysac‐charide research. The synthesis of new cellulose products w…
A series of chemically modified porous silicas, which can be used in high-performance liquid chromatography (HPLC), were prepared by a two-step modification process. Aminopropyl groups were first attached to the silica surface and subsequently converted to amides via the reaction with appropriate acid chlorides. Chang…
In this paper, the percolation threshold of the carbon black-resin composites is discussed based on the experimental results of the changes in resistivity and relative permittivity for loading carbon black, the electric field dependence of current, and the critical exponent of conductivity. It was found that a formati…
A series of alternating copolymers of 2,5-(3,4-ethylenedioxy)thiophene and 1,2-vinylene with well defined repeat unit ratios were synthesized and characterized electrochemically and spectroscopically. By increasing the vinylene to thiophene ratio from 0:1 to 0.5:1 to 1:1 along the polymer backbone, the bandgap of the…
MCM-48 mesoporous molecular sieves containing iron(III) were obtained using a direct sol−gel route followed by removal of the cetyltrimethylammonium hydroxide template before calcination. UV−visible, ESR, and XANES spectroscopies show that iron mostly occupies tetrahedral sites of the siliceous walls. The formation of…
Using nanoscale atomistic simulations it has been possible to address the problem of cross slip of a dissociated screw dislocation in an fcc metal (Cu) by a method not suffering from the limitations imposed by elasticity theory. The focus has been on different dislocation configurations relevant for cross slip via the…
The materials science of carbon-based materials has enjoyed a tremendous growth in the past half century. Selected highlights are reviewed with emphasis given to future opportunities in this research field.
This paper investigates sintering and phase transitions of La 0.7 CaxCrO 3 (0.25≥x≥0.35), a material useful as electrical interconnections in solid oxide fuel cells. Heating of the quenched, metastable single‐phase chromite resulted in exsolution of CaCrO 4 due to Ca solubility limitations below 1200°C. A transient li…
▪ Abstract Cholesteric liquid crystals possess a helical structure and exhibit two stable states at zero field: the planar texture and the focal conic texture. In the planar texture, they reflect circularly polarized light, whereas in the focal conic texture, they scatter light in forward directions. They can be switc…
We have studied the adsorption of poly(styrene- b -2-vinylpyridine) block copolymers from a selective solvent onto a flat solid substrate, resulting in the formation of laterally ordered microdomains. We address the question whether the lateral domain structure is due to adsorption of entire micelles from the solution…
The hydroxyl or vinyl end-groups of linear or three-arm star-shaped poly(ε-caprolactone) (PCL) chains have been derivatized into triethoxysilane groups reactive in the sol-gel process. New transparent hybrid materials that combine tetraethylorthosilicate (TEOS) and PCL known for biodegradability and biocompatibility h…