Materials Literature
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The nature of the possible liquid-crystalline phases that a molecular or colloidal system may exhibit depends sensitively on the shape of the constituent particles. Recent computer simulations on fluids of consisting of non-spherical hard-core molecules suggest that, in order to predict the relative stability of isotr…
1. Volume I-Mechanical Behavior and Properties of Composite Materials 2. Volume 2 -Micromechanical Materials Modeling 3. Volume 3-Processing and Fabrication Technology 4. Volume 4-Failure Analysis of Composite Materials 5. Volume 5-Design Studies 6. Volume 6-Test Methods
Issues related to the design of high-frequency transformers are discussed. An analysis of skin and proximity effects in the conductors and measurements of permeability and hysteresis loss in the magnetic material are combined in a computer-assisted study of the relationships between size, efficiency, and frequency. Ex…
The mechanism of electrical tree initiation in polyethylene subjected at AC, DC, and half-rectified AC voltages is studied by an optical technique which is at least two orders of magnitude more sensitive than partial discharge detection. For DC voltage up to 46 kV, no light emission or tree inception was detected in t…
The esperamicins represent a class of antitumor antibiotics characterized by an unusual chemical core structure and extremely potent cytotoxicity. The mechanism by which these drugs produce cytotoxicity was investigated and found to be related to the formation of single- and double-strand DNA breaks. Using five struct…
An analysis is given of experimental techniques for measuring the anchoring energy, W, of nematic liquid crystals with solid surfaces. Two novel methods for measuring W in homeotropically oriented samples are discussed. The first is based on the stabilization of the flexoelectric distortion by a magnetic field. In the…
A replica trick similar to that used in spin glass theory is implemented to study a structure of large heteropolymeric globule or a heteropolymeric melt with random quenched sequence of monomers of two types (A and B). It is shown that a microphase separation third order phase transition occurs when the system of torn…
Two classes of thermotropic polymers were synthesized containing the trans-azobenzene unit as both a mesogenic and a photochromic group. In the former class (I) the azobenzene unit is incorporated into the main chain of substituted polymalonates, while in the latter class (II) it is appended as a side chain substituen…
The adsorption of aromatic compounds by smectite exchanged with tetramethylammonium (TMA) has been studied. Aromatic compounds adsorbed by TMA–smectite are assumed to adopt a tilted orientation in a face-to-face arrangment with the TMA tetrahedra. The sorptive characteristics of TMA–smectite were influenced strongly b…
Femtosecond differential absorption measurements of the quantum-confined transitions in CdSe microcrystallites are reported. Spectral hole burning is observed, which is accompanied by an induced absorption feature on the high-energy side. The spectral position of the burned hole depends on the excitation wavelength. F…
An automatic procedure for building a protein polyalanine backbone from C alpha positions and 'spare parts' retrieved from a data base of 66 high-resolution protein structures is described. Protein backbones are constructed from overlapping fragments of variable length, which allows the backbone of regular secondary s…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemistry of yttrium triisopropoxide revisited. Characterization and crystal structure of Y5(.mu.5-O)(.mu.3-OPr-iso)4(.mu.2-OPr-iso)4(OPr-iso)5Olivier Poncelet, William J. Sartain, Liliane G. Hubert-Pfalzgraf, Kirsten Folting, and Kenneth G. CaultonCite this: Inorg. Chem. 19…
A detailed description of the method of crystallographic refinement by simulated annealing is presented. To test the method, it has been applied to a 1.5 Å resolution X-ray structure of crambin. The dependence of the success of the simulated annealing protocol with respect to the temperature of the heating stage is di…
Relaxation and diffusion in restricted geometrics excitation energy transfer and photoinduced electron transfer phenomena in some confined systems electron excitation transport in micelles, polymers, and multilayers electron excitation transport on polymer chains polymer structure and downchain electronic energy trans…
Careful experimental techniques, especially with synchrotron radiation, give well-resolved diffraction patterns. Remaining overlapping peaks can be separated by profile analysis and profile fitting. The mathematical formalism is given. The derived parameters are: peak positions for lattice constants, integrated intens…
L'agent de surface a pour role de stabiliser la mousse avant gelification. Influence d'agents de surface sur des proprietes de surface de mousses phenoliques
The wetting by a liquid drop of a model mammalian hair fibre is compared with that of a smooth cylindrical fibre. (B. J. Carroll, J. Collodid Interface Sci., 1976, 57, 488). The model considered has a series of axially symmertrical serrations regularly spaced along the fibre length and these are shown to play an impor…
Thermogravimetric (TG) data on reoxidation behaviour of a particular type of sponge iron (coal based sponge iron) are mainly reported in this paper. While emphasis is on isothermal kinetics, some nonisothermal TG data are also presented. The data have been analysed using the reduced time plot and the activation energy…
Abstract Recent research of the well‐drained cerrados (savanna) soils of Brazil suggests that poor root growth associated with inferior crop production is often caused by subsoil Ca deficiency rather than Al toxicity. The present study was conducted to re‐examine this hypothesis and to compare native soil vegetation p…
The effect of a magnetic field applied perpendicular to the helical axis of a cholesteric liquid crystal mixture with positive diamagnetic anisotropy has been studied by laser diffraction and microscopy. A rapid decrease of the field below a threshold H s generates first a metastable periodically striated texture. A f…