Materials Literature
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We prepared Ag-glass composites by impregnating porous glass with a ${\mathrm{AgNO}}_{3}$ solution. The samples were then reduced (in a hydrogen atmosphere) and densified before they were characterized by x-ray diffraction and electron microscopy. The growth of the metal particles inside the glass was studied by a tra…
Hardness and softness kernels η(r,r′) and s(r,r′) are defined for the ground state of an atomic or molecular electronic system, and the previously defined local hardness and softness η(r) and s(r) and global hardness and softness η and S are obtained from them. The physical meaning of s(r), as a charge capacitance, is…
Starting from a description of a molecular wave function using bond orbitals a general formula was derived describing the change of an expectation value of a one electron operator with bond polarization. This equation leads to a bond additive scheme for the description of bond polarization effects containing matrix el…
The temperature evolution of the birefringence in sodium nitrate shows a phase transition at 552 K which is continuous within experimental resolution (0.1 K). The excess birefringence is found to relate to the spontaneous strain via a temperature-independent elasto-optic coefficient. This behaviour is discussed micros…
This letter describes the first successful attempt at synthesizing diamond by chemical vapor deposition with the use of a dc plasma jet. A plasma jet, formed by the dc arc discharge of CH4 diluted with H2, was sprayed onto a water-cooled substrate. The growth rate of the diamond film was 80 μm/h. The crystallinity mea…
Abstract Studies on tensile strength of polybutadiene (BR) and ethylene–propylene diene rubber (EPDM) having a wide range of flaw sizes have been carried out under both normal and aging conditions. A similar study has been done for a solid propellant rocket insulator compound, based on EPDM. The morphology of tensile…
Abstract Development of crystalline structure during the tubular film blowing of low‐density polyethylene was investigated, using wide‐angle X‐ray diffraction technique, low‐angle light scattering, and scanning electron microscopy. In the study, commercial grades of both high‐pressure low‐density polyethylene (HP‐LDPE…
Abstract The thickness of matrix ligament is shown to be the single parameter determining whether a polymer/rubber blend will be tough or brittle. The matrix ligament is defined as the region of the matrix between two neighboring rubber particles. Specifically, the ligament thickness is the surface‐to‐surface interpar…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNonanuclear oxide-bridged manganese complex. Preparation, structure, and magnetic properties of [Mn9O4(O2CPh)8(sal)4(salH)2(pyr)4] (salH2 = salicylic acid; pyr = pyridine)Cheryl. Christmas, John B. Vincent, Hsiu Rong. Chang, John C. Huffman, George. Christou, and David N. He…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMagnetic ordering of manganese(II) copper(II) bimetallic chains; design of a molecular based ferromagnetOlivier. Kahn, Yu. Pei, Michel. Verdaguer, Jean Pierre. Renard, and Jorunn. SlettenCite this: J. Am. Chem. Soc. 1988, 110, 3, 782–789Publication Date (Print):February 3, 1…
. The nematic-isotropic (NI) and crystalnematic (KN) transition temperatures were measured from atmospheric pressure to 1 kbar for a homologous series of thermotropic polyesters based on regularly alternating 2,2'-dimethylazoxybenzene mesogen and alkanedicarboxylic acid spacer. The values of (dP/dT) for the NI transit…
Abstract The crystal structure of the title complex, a semiconductor, has been determined. The space group is P21⁄n, with a=8.207(3), b=11.537(4), and c=21.804(12) Å, β=91.88(5)°, and Z=4. The donor cations assume dimer structures with short intermolecular S···S contacts of 3.43, 3.53, and 3.60 Å.
Syncrystallization can be analysed through a new approach: the determination of the `tensor of compositional deformation'. It is a convenient way to take structural anisotropy into account and to point out the directions of strongest and weakest modifications of the intermolecular interactions due to the substitution…
The modification of passive iron electrodes by chromate ion has been studied in three different electrochemical experiments: potentiostatic passivation, open‐circuit passivation, and cyclic potential treatment. XPS surface composition and composition‐depth profiles obtained by argon ion‐sputtering of the modified elec…
The kinetics of olefin epoxidation in a methylene chloride/water biphase containing a phase-transfer agent with hypochlorite as oxygen transfer reagent and manganese(III) tetraphenylporphyrin catalysts has been reinvestigated. The results do not support the accumulation of an intermediate composed of an alkene and a h…
Abstract Dans un complexe de fabrication d'aluminium, le procédé de cuisson des anodes donne lieu à une libération importante de matières volatiles combustibles. Le présent travail vise à mieux comprendre la cinétique de dégagement de ces substances. À cette fin, un dispositif thermogravimétrique de grandes dimensions…
Abstract We have observed that the rate of folding of the enzymatically hydroxylated form of poly(Gly‐Pro‐Pro) into the triple‐helical conformation is considerably higher than that of the unhydroxylated polypeptide [R. K. Chopra and V. S. Ananthanarayanan (1982) Proc. Natl. Acad. Sci. USA 79 , 7180–7184]. In this stud…
We have studied both experimentally and theoretically enhanced optical second-harmonic generation (SHG) from a silver grating due to surface-plasmon excitation with a Nd-glass laser. Reduced Rayleigh equations are employed to calculate the enhancement of the diffracted SHG over that reflected from a smooth surface. Us…
Starting from the free-electron model, we show that the solution of a problem of enhanced second-harmonic generation by metals in nonlinear optics reduces to that of a classical boundary-value problem. Surprisingly, this boundary-value problem has a form that is quite equivalent to that encountered in the classical pr…
Abstract Polarized optical microscopy and small‐angle light scattering (SALS) are used to investigate the cholesteric phase of aqueous hydroxypropylcellulose (HPC) solutions. The results suggest a polygonal focal conic rather than the recently proposed parabolic focal conic morphology. Measurements of the polygonal do…