Materials Literature
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Abstract The structures of the series of oligothienyls (T4‐T5‐T6) have been determined and refined from X‐ray powder diffraction data using the Rietveld full‐profile analysis. Unlike polythiophene, all the molecules in the isomorphous series display no internal symmetry, being only approximately planar within 12°. Pac…
Excited-state decays of the special pair of Rhodobacter capsulatus and 10 mutants as a function of temperature are presented. The mutations are at the symmetry-related sites L181 and M208. All the decays are nonexponential, although the degree of nonexponentially depends strongly on the mutant and the temperature. We…
Due to a dependency on the element in the spacer and its substituents, the extent of the interactions between the ferrocene units of the polymer backbone of 1 and 2 can be varied. The electrochemical behavior of 3 in which the ferrocene units are separated by C2 bridges shows that the cooperative interactions are much…
A thin, brittle layer bonded between tougher substrates is susceptible to cracking under residual and applied stresses. Such a crack initiates from an equi-axed flaw, confined by the substrates, tunneling in the brittle layer. Although tunneling is a three-dimensional process, the energy release rate at the front of a…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectronic structures of active sites on metal oxide surfaces: definition of the copper-zinc oxide methanol synthesis catalyst by photoelectron spectroscopyEdward I. Solomon, Paul M. Jones, and Jennifer A. MayCite this: Chem. Rev. 1993, 93, 8, 2623–2644Publication Date (Prin…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolubilization of some low-polarity organic compounds by hydroxypropyl-.beta.-cyclodextrinXiaojiang Wang and Mark L. BrusseauCite this: Environ. Sci. Technol. 1993, 27, 13, 2821–2825Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Publis…
The synthesis of discotic liquid crystal materials based on the triphenylene core normally involves the preparation of hexahydroxytriphenylene. This has traditionally been accomplished by a chloranil promoted trimerization of 1,2-dimethoxy-benzene followed by demethylation of the hexamethoxytriphenylene produced. Hexa…
We show how the observed transformation behavior of two forms of amorphous solid water can be explained in terms of a first-order phase transition, via a consideration of the limits of metastability associated with this kind of transition. We propose a phase diagram describing amorphous solid water consistent with the…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLuminescence behavior of europium complexes in sol-gel derived host materialsLowell Matthews, R. and Edward T. KnobbeCite this: Chem. Mater. 1993, 5, 12, 1697–1700Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 Decem…
A computational method was devised to explore the relationship of charge separation, geometry, molecular dipole moment (mu), polarizability (alpha), and hyperpolariz-abilities (beta, gamma) in conjugated organic molecules. We show that bond-length alternation (the average difference in length between single and double…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNonlinear optical chromophores with large hyperpolarizabilities and enhanced thermal stabilitiesChristopher R. Moylan, Robert J. Twieg, Victor Y. Lee, Sally A. Swanson, Kathleen M. Betterton, and Robert D. MillerCite this: J. Am. Chem. Soc. 1993, 115, 26, 12599–12600Publicat…
A kinetic study of cement setting process is presented in this paper A new method which allows the microscopic research of the evolution of the cement hydration applied to the study of three P-350 cuban cements is used. The initial and final values of the specific surfaces of the hydration products and cement were obt…
There are numerous mechanisms that can lead to deterioration of portland-cement concrete in service. The best known are corrosion of reinforcement, freezing-thawing expansion, alkali-silica reaction, acid attack, and sulfate-related problems, including delayed ettringite formation. Additionally, concrete can deteriora…
La degradación del hormigón, debida a la reacción expansiva llamada "reacción álcali-árido", ha sido ampliamente estudiada (1) y (2). Este fenómeno es especialmente relevante en países como Estados Unidos, Canadá, Brasil, etc., donde hay una gran cantidad de áridos con sílice reactiva.
SUMMARY In this work we study the weathering resistance of samples of five types of stone used in Andalusian Cathedrals, treated with six water repellent products, by subjecting the samples to a SO2 polluted atmosphere. To evaluate the alteration of the samples, besides visual observation of macroscopic aspect, change…
Limestone filler addition to Portland cement does not only have an impact on the mechanical strength of mortars, but its action also alters their rheological values. Taking a Portland cement as the basic material and incorporating different calcareous filler portions from 0 to 50 %, standard mortars were prepared, det…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure of the tetrahedral sodium Na54+ cluster in zeolite XYang Kim, Young Wook Han, and Karl SeffCite this: J. Phys. Chem. 1993, 97, 49, 12663–12664Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 December 1993htt…
Abstract Dielectric relaxation and pyrocurrent of PVDF were studied by thermostimulated current spectroscopy. The transition spectrum of the material was investigated by differential scanning calorimetry. Two well‐resolved relaxation peaks have been observed in the temperature range [−100–100°C]. The molecular mechani…