Materials Literature
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A major unsolved problem in cellulose structure is the polarity of adjacent chains of cellulose in the microfibrils, namely, the "parallel or antiparallel" problem.This issue is closely related to the possibility of a folded-chain structure and to the mechanism of cellulose biosynthesis.The prevailing view, based on x…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPrediction of point efficiencies on sieve trays. 1. Binary systemsHong Chan and James R. FairCite this: Ind. Eng. Chem. Process Des. Dev. 1984, 23, 4, 814–819Publication Date (Print):October 1, 1984Publication History Published online1 May 2002Published inissue 1 October 198…
The composition and application of a single, chemically defined medium or growth and sporulation of Bacillus subtilis is described. At 37 degrees C cells grew with a doubling time of about 40 min; cultures attained near-maximal spore formation (70 to 80% by 12 h after the end of exponential growth and produced 1 X 10(…
The alanine racemase encoded by the Salmonella typhimurium dadB gene was purified to 90% homogeneity from an overproducing strain. At 37 degrees C the enzyme has a specific activity of 1400 units/mg (V max, L- to D-alanine). Active enzyme molecules are monomers of Mr 39 000 with one molecule of pyridoxal 5'-phosphate…
The elastic-distortion free-energy density of biaxial nematics is derived with use of the formalism of tensor analysis. The macroscopic description of biaxial nematics involves 12 bulk elastic constants. The appearance of chirality introduces an additional number of 5 twist terms.
Changes in the phase composition and microstructure of yttria‐partially‐stabilized zirconia by low‐temperature annealing were investigated at 100° to 500°C using bodies sintered from coprecipitated fine ZrO 2 ‐Y 2 O 3 powders at varied temperatures. Tetragonal zirconia on the surfaces of bodies sintered at <1500°C…
Abstract This review summarizes the different ideas to breakdown of passivity and localized corrosion. On the basis of experimental results a critical discussion of the main mechanisms is presented. The subdivision into different stages of growth of corrosion pits tries to reduce the controversial opinions and to avoi…
de Gennes gave a three-parameter representation of strain energy in a cholesteric liquid crystal that is second order on the $Q$ tensor, and hence in order parameter. He discarded a term involving an elastic constant ${K}_{24}$ which is relevant at surfaces and disclinations. The splay and bend elastic constants ${K}_…
In situ laser Raman spectra of anodic corrosion films formed on Ni and Co in have been obtained for the first time and the composition of the surface films deduced. The Raman spectrum of the film found on Ni at about 0.6V vs. corresponds closely to that of hydrated . The anodically formed film on Co at about 0.45V app…
Abstract Effects of structural relaxation and the glass‐transition process are clearly manifested in the electrical behavior of glassy‐chalcogenide films. Analysis of the transport and trapping of photoinjected carriers and of the thermal generation of free carriers in the bulk reveal that in chalcogenides each of the…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbon-13 NMR analysis of ethylene-propylene rubbersH. N. ChengCite this: Macromolecules 1984, 17, 10, 1950–1955Publication Date (Print):October 1, 1984Publication History Published online1 May 2002Published inissue 1 October 1984https://doi.org/10.1021/ma00140a012RIGHTS & P…
The work described in this paper was carried out some years ago. It was published as part of a U.S. Air Force report [1] and presented as a Conference Paper [2] at this Conference. Since the latter appeared only as an extended abstract and the former did not receive wide distribution it seemed appropriate to present i…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotochemistry of phosphate esters: an efficient method for the generation of electrophilesRichard S. Givens and Bogdan MatuszewskiCite this: J. Am. Chem. Soc. 1984, 106, 22, 6860–6861Publication Date (Print):October 1, 1984Publication History Published online1 May 2002Publi…
The physical processes occurring during partial discharges in voids in dielectrics have been studied utilizing fast oscilloscopic techniques to observe the buildup and decay of current as a function of time for single discharges. A key parameter is the overvoltage at breakdown, determined for time-dependent voltages b…
Thin films of the phase transition material vanadium dioxide (VO2) were deposited by thermal oxidation of e-beam evaporated vanadium on a variety of bulk materials. Substrate effects on transition temperature are confirmed as being due to a mismatch between film and substrate thermal expansion coefficients. Decreasing…
Abstract Double-chain alkyl amphiphiles with oligo-l-glutamic acid-head group were prepared. These compounds were dispersed in water at pH 8 to 9 to form bilayer aggregates, in which helical and hollow structures were contained. New CD bands were observed in the solution.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolylactones. 1. Copolymerizations of glycolide and iε-caprolactoneHans R. Kricheldorf, Thomas Mang, and J. Michael JonteCite this: Macromolecules 1984, 17, 10, 2173–2181Publication Date (Print):October 1, 1984Publication History Published online1 May 2002Published inissue 1…
The phenomenon of water-tree degradation of polyolefin insulating materials is reviewed with particular emphasis on the materials aspect of the problem. Specific topics include: methods of producing water trees in the laboratory, water-tree morphology, the nature of tree growth curves, and the effects of temperature,…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSodium hypochlorite: a convenient oxygen source for olefin epoxidation catalyzed by (porphyrinato)manganese complexesBernard Meunier, Elisabeth Guilmet, Maria Eliza De Carvalho, and Rene PoilblancCite this: J. Am. Chem. Soc. 1984, 106, 22, 6668–6676Publication Date (Print):O…
Abstract : The book presents a survey and review of relaxation phenomena in many research fields. Contents: Viscous Liquids and Glasses; Relaxation in Polymers; Metallic Glasses; Spin Glasses; Electrical Relaxations in Ionic Conductors; and Theory and Models.