Materials Literature
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We describe observations made with an optical microscope of the formation of two distinct types of disclinations during the shear of a small molecule nematic, MBBA. Once formed, these disclinations grow and deform in the shear field. We also report observations of the relaxation of these defects after the cessation of…
The influence of oxygen vacancies in PbZrO3 on the dielectric properties and phase transitions between the antiferroelectric, ferroelectric and paraelectric states has been investigated. Marked changes in dielectric parameters and in phase transition temperatures were found for the deficient samples. With increasing n…
Abstract A quantitative model which described the microscopic and macroscopic refractive index properties of uniaxially oriented crystalline polymers has been extended in relation to molecular bond polarizabilities in this work. Application of this extended modeling methodology in analyzing measured refractive index d…
We have examined the interaction of H2O vapor with three structurally different carbon surfaces. The edge and basal surface of crystalline graphite as well as a ‘‘paracrystalline’’ glassy carbon were characterized with LEED, UPS, and AES. Structural characterization by LEED showed the typical ‘‘ring’’ pattern for the…
Electrochemical polarization methods were utilized to study the galvanic corrosion of steel coupled to brass. Polarization of a 70Cu-30Zn brass cathode controlled galvanic corrosion rate (galvanic current) of the steel anode in the couple. The effect of cathode/anode surface area ratio was predicted successfully from…
The magnetic properties of Pb(Fe1/2Nb1/2)O3 have been studied by neutron diffraction on a polydomain single crystal and susceptibility measurements on a single ferroelectric domain. A Néel temperature of $$ 160K was found but no further anomalies were indicated by the susceptibility data. No evidence of a spontaneous…
Bacillus subtilis mutants deficient in the 2-ketoglutarate dehydrogenase enzymatic complex required aspartate for growth at wild-type rates on carbon sources for which synthesis of the degradative enzymes is sensitive to catabolite repression (e.g., poor carbon sources), but did not require aspartate for growth on car…
Abstract Dimethylsilanediol and other water-soluble dimethysiloxanols undergo aqueous photolytic oxidative demethylation with tropospheric ultraviolet radiation in the presence of suitable chromophores, such as nitrogen oxides, to give silicic acid and carbon dioxide. The “biosuitability” of the resulting silicic acid…
A crystal chemical study carried out on phosphate single crystals with the formula AIBIIPO4 (AI=Na, K; BII=Ca, Zn, Sr, Cd, Ba, Pb) has permitted to follow the evolution of the crystal symmetry inside these series. Second harmonic generation (SHG) tests held on powder or small single crystals and hysteresis loops displ…
Abstract The solid reaction products from pyrolysis of polyethylene terephthalate in the presence and absence of red phosphorus were characterized by CP/MAS 13 C‐NMR, FR‐IR, and MAS 31 P‐NMR spectroscopy. Over the temperature range of 300–400°C, polyethylene terephthalate was converted in a sealed vial to a highly cro…
Abstract From analysis of infrared spectra it was found that in syndiotactic ( s ) poly(methyl methacrylate) (PMMA) in solution, long s sequences contain an increased population of diads with a skeletal conformation tt (in the staggered approximation). Self‐aggregation of s ‐PMMA in solution leads to a further increas…
The review of the experimental investigations of the anomalous (bulk) photovoltaic effect in the crystals without a center of symmetry is presented. The linear and circular effects for piezo and ferroelectrics are investigated in the wide range of conditions (the extrinsic and intrinsic absorbtion, different impurity…
Abstract The isothermal melting behavior of poly( L ‐lactic acid) spherulites has been studied in order to understand the mechanism of melting using hot‐stage microscopy. When the periphery of the spherulite melts or shrinks, the central portion undergoes thickening as a result of which the melting or shrinking rate i…
The temperature dependence of the soft mode components in BaTiO3 and KNbO3 and their contribution to the low-frequency dielectric constant are reexamined under the 1ight of recent hyper-Paman and infrared reflectivity data. Correlated fluctuations are less and less dominant with the decrease of critical dimensionality…
Abstract Morphological studies of isotactic polypropylene/low‐density polyethlene blends revealed that the shape, size, and orientation of LDPE occlusions remain undisturbed during the crystallization of IPP spherulites. On the other hand, LDPE occlusions introduce large changes in the internal structure of IPP spheru…
Study of melt rheological properties of the blends of polypropylene (PP) with styrene–ethylene butylene–styrene block copolymer (SEBS), at blending ratios 5–20% SEBS, is reported. Results illustrate the effects of (i) blend composition and (ii) shear rate or shear stress on melt viscosity and melt elasticity and the e…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMixed-metal atom cluster compound containing silver(I) and platinum(II)Rafael Uson, Juan Fornies, Milagros Tomas, F. Albert Cotton, and Larry R. FalvelloCite this: J. Am. Chem. Soc. 1984, 106, 8, 2482–2483Publication Date (Print):April 1, 1984Publication History Published on…
The optical constants of polycrystalline electrochromic (EC) tungsten trioxide films, prepared by rf sputtering, were measured by ellipsometry at three wavelengths: 940, 633, and 546 nm. For each wavelength, the optical constants were measured at various states of coloration. It is shown that these measurements provid…
The Escherichia coli pyrC, pyrD and pyrF genes were cloned on multicopy plasmids derived from pBR322 and analysed by means of restriction endonucleases. It was found that the pyrC gene is destroyed by cutting with the restriction endonuclease BamHI, that the entire pyrD gene can be isolated on a 1300-base pairs DNA fr…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolymer-encased vesiclesSteven L. Regen, Jae Sup Shin, and Kazuo YamaguchiCite this: J. Am. Chem. Soc. 1984, 106, 8, 2446–2447Publication Date (Print):April 1, 1984Publication History Published online1 May 2002Published inissue 1 April 1984https://pubs.acs.org/doi/10.1021/ja…