Materials Literature
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The refractive indices and densities of six liquid crystals—two alkylcyanobiphenyls, three alkoxycyanobiphenyls and one mixture of two alkylcyanobiphenyls have been reported as a function of temperature. The effective polarizabilities αeand αo in the nematic phase calculated using the methods due to Neugebauer, Vuks a…
A technique is presented whereby compressive surface stresses are introduced into transformation‐toughened ZrO 2 ceramics by removing the stabilizing oxides, such as Y 2 O 3 , from the surface. The advantages of this approach over other techniques are discussed, and experimental data confirming the presence of compres…
Abstract Wood fibers from aspen and spruce have been used for filler and reinforcement of polystyrene. The wood fibers used were in the form of refined wood. In order to improve compatibility of wood fibers with polymeric matrices, fibers have been modified by copolymerization with styrene. The kanthate method of graf…
A method for the isolation and purification of pyridinoline from bone collagen was developed, with the use of sulphonated polystyrene resins. The analytical techniques were used to quantify pyridinoline, for which hydroxyallysine is a known precursor, in a wide range of tissues. The structure of pyridinoline proposed…
Gorsky-effect measurements of the diffusion coefficient of tritium (T) in V, Nb and Ta are reported. The measurements were performed at small T concentrations (less than about 1.4 at.%), and in the temperature range from -140 degrees C to 100 degrees C. Comparison with results obtained for H and D shows an increase of…
Dispersion states of aqueous composite Al 2 O 3 /ZrO 2 colloidal suspensions were studied by measuring particle size distribution as a function of pH. Mutual dispersion was achieved at pH values of 2.0 to 3.5. Consolidated composites formed by colloidal filtration reflected the uniformity of the colloidal state. The m…
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAb initio investigation on the lowest singlet and triplet state of disilyne (Si2H2)Hans Lischka and Hans Joachim KoehlerCite this: J. Am. Chem. Soc. 1983, 105, 22, 6646–6649Publication Date (Print):October 1, 1983Publication History Published online1 May 2002Published inissu…
Semi-infinite systems are considered which undergo a first-order transition. The global phase diagram is discussed within the framework of Landau theory. Several types of phase transitions are found. At some of these transitions, critical surface phenomena occur since a variety of surface exponents may be defined alth…
During oxygen and carbon tetrafluoride plasma etching of silicon nitride, a light blue and water soluble film is deposited upon the surface of the silicon nitride layer. Depending upon the thickness, this film retards or completely inhibits the desired etching process. This film has been identified by infrared spectro…
There is no simple experimental method which allows the separation of the dielectric constant in contributions of the bulk and those of 90°-domain wall motions. The contribution of the bulk is calculated in this paper for the specific domain configuration in large grains which was revealed by etch patterns. The volume…
The blue phases of two cholesteric systems are studied under the influence of an electric field. The wavelength of maximum absorption due to the selective reflection of circularly polarized light of both blue phase I (BP I) and blue phase II (BP II) turns out to be shifted to longer wavelengths with increasing electri…
This study was undertaken in order to analyse the importance of the pumping effect on clothing's thermal insulation. To enhance differences in heat exchanges due to the pumping effect, two sets of condition were fixed, minimizing either the convective or the radiative heat transfers. The results showed that: (i) the c…
Abstract The kinetics of the anionic polymerization of ϵ‐caprolactone, including the kinetics of macrocyclization and the kinetics of macrocycles propagation in THF solution, initiated with (CH 3 ) 3 SiONa, were investigated. Rate constants of propagation ( k p( n ) ) and of back‐biting ( k d( n ) ) involving monomer…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLiquid crystalline solvents as mechanistic probes. 11. The syn .fwdarw. anti thermal isomerization mechanism of some low-bipolarity azobenzenesJoseph P. Ortruba III and Richard G. WeissCite this: J. Org. Chem. 1983, 48, 20, 3448–3453Publication Date (Print):October 1, 1983Pu…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNegative ions: effect of .alpha.- vs. .beta.-silyl substitution on the negative ion states of .pi. systemsJudith C. GiordanCite this: J. Am. Chem. Soc. 1983, 105, 22, 6544–6546Publication Date (Print):October 1, 1983Publication History Published online1 May 2002Published ini…
X-ray analyzer, and 3) the digital scan
The triboluminescent spectra of a variety of glasses and of crystalline quartz were measured while specimens were cut with a rotating diamond-impregnated saw blade. The spectra, which resemble the emission of a blackbody radiator, were recorded using an image-intensifier spectrograph. The data were intensity-corrected…
Abstract Experimental studies of fiber wet‐spinning and solution processing of films of molecular composites are presented. The rigid rod polymer was poly (p‐phenylenebenzobisthiazole) (PPBT) and the flexible polymers were poly (2,5(6′)‐benzimidazole) (ABPBI) and poly (2,5(6′)‐benzothiazole) (ABPBT). Effects of the fl…
Magnetic phase transitions in itinerant electron magnets Hf 1- x Ta x Fe 2 have been studied from measurements of Mössbauer effect, magnetization and X-ray diffraction. The first order magnetic phase transition from ferromagnetic to antiferromagnetic state has been observed with increasing temperature in the Ta concen…