Materials Literature
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Chitosan [a (1----4) 2-amino-2-deoxy-beta-D-Glucan] is a unique polysaccharide derived from chitin. Several attempts have been made to use this biopolymer in biomedical field. The use of this material in the development of hemodialysis membranes, artificial skin, drug targetting and other applications are discussed. I…
Abstract A finite‐field method for the calculation of polarizabilities and hyperpolarizabilities is developed based on both an energy expansion and a dipole moment expansion. This procedure is implemented in the MOPAC semiempirical program. Values and components of the dipole moment (μ), polarizability (α), first hype…
ABSTRACT: Depending on the spinning and drawing conditions, two crystal structures for solution-spun poly(L-lactide) are obtained. The pseudoorthorhombic a structure (a = 10.6, b = 6.1, and c = 28.8 A) contains two chains in the unit cell and is found at relatively low drawing temperatures and/or low hot-draw ratios.…
Volume 1 addresses the selection and application of ferrous metals and alloys, including cast irons, carbon and low-alloy steels, tool steels, stainless steels, and nickel and cobalt-base superalloys. As the lead volume in the Handbook series, it lays the groundwork for understanding the hierarchical nature of metals…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthetic routes to boron nitrideRobert T. Paine and Chaitanya K. NarulaCite this: Chem. Rev. 1990, 90, 1, 73–91Publication Date (Print):January 1, 1990Publication History Published online1 May 2002Published inissue 1 January 1990https://pubs.acs.org/doi/10.1021/cr00099a004h…
The methods of synthesis, properties, structure, and electronic structure of binuclear molybdenum(III) complexes are reviewed. Dimers without monatomic bridges and dimers with oxygen, sulphur, and halogen bridging atoms are described. The effect of the bridging ligands on the nature of the M–M bond and the dependence…
Cellulose is an old polymer with new industrial applications. The derivatization of cellulose has opened up tremendous production and marketing possibilities for the adhesives industry. Various important adhesives have been derived from cellulose ethers. The structure and molecular size of cellulose and their influenc…
Despite present trends toward use of synthetic polymers developed over the last 10 or 20 years, starches are still being widely used as an adhesive in such applications as the production of paper and paperboard products, warp sizing, and bonding charcoal briquettes. Because of a unique combination of properties and lo…
Volume 20 of Reviews in Mineralogy attempted to: (1) provide examples illustrating the state-of-the-art in powder diffraction, with emphasis on applications to geological materials; (2) describe how to obtain high-quality powder diffraction data; and (3) show how to extract maximum information from available data. In…
The effect of externally applied stresses of eg and t2g symmetry on the cubic Eg(X)eg Jahn-Teller (JT) system Y2+ in SrCl2 is studied. Coupling constants were obtained with the aid of EPR and by relying on a Ham-type cluster JT Hamiltonian, in conjunction with a random strain distribution. This is established from a c…
An ENDOR investigation has confirmed that the OK1 centre is a low-symmetry ( sigma h ) centre, incorporating a single nitrogen atom. The 14 N hyperfine and quadrupole coupling matrices have been determined by fitting the data to an exact solution of the energy matrix. Using this and other new experimental data the aut…
The angular dependences of the time and frequency parameters of a single-crystal collective nuclear resonance were studied in a unified series of measurements and compared with the resonance parameters of an isolated nucleus. It was shown that, when approaching the Bragg angle ( theta B ), the coherent character of ga…
We report measurements of the impurity-concentration and crystal-size dependences of the threshold field ${E}_{T}$ for charge-density-wave (CDW) depinning in ${\mathrm{NbSe}}_{3}$. These measurements establish that CDW's in Ta-doped ${\mathrm{NbSe}}_{3}$ are weakly pinned. Size dependence of ${E}_{T}$ occurs when the…
L-arginine phosphate monohydrate (LAP) and deuterated LAP (DLAP) are new organic nonlinear optical materials useful for higher harmonics of radiation from high-power lasers. We measured the bulk laser damage threshold of these crystals using light from a 1.05 μm laser with 1 and 25 ns pulse widths and 0.53 μm laser li…
Abstract The crystallography and morphology of barium sulphate crystals produced by a range of desmid species have been examined by electron microscopy and electron diffraction. The morphology of the BaSO4 crystals varies between desmid species and water chemistry. Tabular, rhombic crystals are commonly produced by Cl…
Two orthogonally aligned liquid crystal lenses with spherical Fresnel zone plate electrode configurations have been demonstrated to focus an unpolarised broadband object with resulting good quality images. Switch on times of 15ms are reported along with modulation depths of 91.5%.
The sphinx is a non-periodic tiling of the plane made of one type of tile. In order to characterise the type of order found in this tiling, the computation of its diffraction spectrum is considered. The spectrum contains a discrete component, with Bragg peaks located at the vertices of triangular lattices with lattice…
Abstract The thermolysis of vinyl methylterephthalate has been studied as a model of poly(ethylene terephthalate) (PET) thermolysis. Based upon this reaction, a potential mechanism for PET flame retardation is proposed. The assumption is made, based upon firm experimental evidence, that the initial step in PET degrada…
The dynamical behaviour of the alkyl chains in dicopper tetrapalmitate is investigated in the columnar liquid crystal phase, using incoherent quasielastic neutron scattering by several selectively deuterated derivatives. A mathematical model is developed for the evaluation of the scattering function which yields the f…
Lead monohydrogen phosphate (PbHPO 4 ) undergoes a ferroelectric phase transition at T c =310 K at atmospheric pressure. T c falls to room temperature at a pressure of about 0.125 GPa. The crystal structure of PbHPO 4 has been determined by X-ray diffraction at 2.0 and 2.3 GPa and the lattice parameters have been meas…