Materials Literature
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Six individual amino acid substitutions at separate positions in the tertiary structure of subtilisin BPN' (EC 3.4.21.14) were found to increase the stability of this enzyme, as judged by differential scanning calorimetry and decreased rates of thermal inactivation. These stabilizing changes, N218S, G169A, Y217K, M50F…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChain dynamics, mesh size, and diffusive transport in networks of polymerized actin: a quasielastic light scattering and microfluorescence studyChristoph F. Schmidt, Michael Baermann, Gerhard Isenberg, and Erich SackmannCite this: Macromolecules 1989, 22, 9, 3638–3649Publica…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetically stable complexes of alkali cations with rigidified calix[4]arenes: synthesis, x-ray structures, and complexation of calixcrowns and calixspherandsPieter J. Dijkstra, Jos A. J. Brunink, Kjell Erik Bugge, David N. Reinhoudt, Sybolt Harkema, Rocco Ungaro, Franco Ugo…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDioxygen adsorption on well-outgassed and partially reduced cerium oxide studied by FT-IRCan Li, Kazunari Domen, Kenichi Maruya, and Takaharu OnishiCite this: J. Am. Chem. Soc. 1989, 111, 20, 7683–7687Publication Date (Print):September 1, 1989Publication History Published on…
A nearly symmetric critical mixture (φc=0.486) of perdeuterated and protonated 1,4-polybutadiene exhibiting an upper critical solution temperature Tc=61.5±1.5 °C has been quenched from the homogeneous state (≂75 °C) to various temperatures between 25 and 57.5 °C. Light scattering measurements document the subsequent s…
Synthetic diamonds grown by the temperature-gradient method at temperatures just above the melting point of the solvent-catalyst often have an unattractive dull-green colour. This green colour, which is prominent at room-temperature, disappears if the diamond is cooled to below 120 K and is restored on warming the cry…
The reader should first refer to the summary of the IA(1), IB(2) and IIA(3) parts of this work (published in Materiales de Construcción nos. 209, 211 and 212, respectively) in order to have a clearer idea of the subject being dealt with herein. The use of the larger quantities of gypsum as aggressive agent than the 15…
Polarization Resistance (Rp) has been the electrochemical technique employed to study quantitatively the influence of Cl- and OH- ions on the corrosion of steel reinforcing, in a synthetic aqueous medium of similar composition to those of the concrete pore solution. Ionic strength, resistivity and their variations in…
The rate of water evaporation in the exposed surfaces plays an important part in the development of cracks in fresh concretes and mortars before hardening is completed. This rate of evaporation depends on the drying power of the wind sweeping such surfaces as a function of the relative humidity, temperature and speed…
The application of the zeta potential technique in the area of construction materials and Portland cement is quite recent. The initial research work involved the study of cement suspensions or suspensions of one of the components of cement, such as alite, tricalcium alumínate, in the presence of additives and, more sp…
Precursors to highly conducting polypyrrole (Ppy) are formed in the lipophilic channels of 1 subsequent to a spontaneous, strictly stoichiometric [N(Ppy)/Fe = 1/1] redox reaction. In view of the diameter of the channel (6.8 Å) the entrapped Ppy should be free of cross-linking (thus approximating a “molecular wire”).
Abstract The strength of high-performance filaments is a complex parameter which can not be fully described with a single value. The Weibull model is used to describe the intrinsic statistical nature of the fracture strength. Possibilities and limitations of the Weibull model are illustrated. The relationship between…
Vibrational spectroscopic methods are widely used to characterize semicrystalline polymers in terms of crystallinity. The temperature coefficient of crystallinity, an important and fundamental quantity, is seldom determined for lack of a sensitive method. In this paper, we describe an infrared approach to the measurem…
A neutron powder diffraction investigation confirms that, in tough magnesiapartially‐stabilized zirconia cooled to 30 K, most of the tetragonal zirconia transforms to an orthorhombic phase. This phase is retained on heating to room temperature; the lattice parameters at 295 K are a = 0.5068, b = 0.5260, and c = 0.5077…
Reported studies indicate that the association of potassium monopersulfate with [Mn(TMPyP)](OAc)5, a water-soluble manganese porphyrin complex, leads to an efficient reagent for the oxidative cleavage of DNA. Single-strand breaks (SSBs) are observed on double-stranded DNA at manganese porphyrin concentrations as low a…
The crevice model for heterogeneous nucleation of bubbles in water in response to a decreasing liquid pressure is studied. The model neglects gas-diffusion effects and is therefore more suited for acoustic than for flow cavitation. It is argued that previous work has overlooked the essential requirement of unstable gr…
The poly-beta-hydroxybutyrate biosynthetic thiolase gene from Zoogloea ramigera was used as a hybridization probe to screen restriction digests of Alcaligenes eutrophus H16 DNA. Specific hybridization signals were obtained and two fragments (a 2.3-kilobase PstI fragment and a 15-kilobase EcoRI fragment) cloned in the…
Corrosion behavior of mold-cast Mg alloy AZ91 is investigated in as-cast (F), homogenized (T4), and artificially-aged (T6) conditions in chloride media. Heat treatment influences mainly the distribution of intermetallic β-phase (Mg17Al12) in the alloy. Aging to T6 temper causes precipitation of the phase as a nearly c…