Materials Literature
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The free-volume distribution in a simulated Lennard-Jones liquid is heterogeneous. Chains of holes, appearing as segments rather than a continuous network, have lifetimes that are brief compared with the mean vibration period of the atoms. Larger isolated holes persist for longer times. If the chains are interpreted a…
Carboxyl content of cellulose half-acid ester derivatives was determined by the calcium acetate method and by the absorption of silver from silver meta-nitrophenolate solutions. Both methods utilize the acidity of the carboxyl proton in an ion-exchange reaction, thereby producing a salt. With both the calcium acetate…
With the use of ESR spectroscopy NO/sub 2/ molecules have been found in minor quantities in a ..gamma..-irridiated single crystal of uridine 5'-phosphate. NO/sub 2/ is produced from the built-in impurities in a single crystal. The concentration of the NO/sub 2/ molecules depends on the commercial source of the compoun…
PMR spectroscopy and lanthanide shift reagents were used to determine sequence distribution of units of poly(dimethyldian-phenolphtalein)terephthalate. The calculated values of degree of randomness confirm the theory that the copolyester obtained at the isokinetic temperature (200°C) has random distribution of comonom…
A direct observation of the influence of an externally applied electrostatic field on the sublimation steps on (100) surfaces of KCl is reported. Typically, round-cornered square spirals were found to be distorted into round-cornered rhombical spirals in the presence of a field. The results are interpreted in terms of…
Abstract The Raman spectrum of pure liquid para ‐nitroaniline ( p ‐NA) was studied between 150 and 220°C, and compared with those of the crystal and solutions. The 1270–1350 cm −1 region is the most significant. The ν line, very weak for the solid, becomes intense in the spectrum of molten p ‐NA. Except for one case,…
Processing of natural rubber , Processing of natural rubber , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
The role of hydroxyl ion concentration in the endwise depolymerization of hydrocellulose has been investigated in sodium hydroxide solution (0.05–18.6N) at 120°C, by determining the amount of degradation and the changes of carboxyl content and degree of polymerization in the solid phase. The extent of degradation incr…
Raman spectra for Ln 2 O 2 S: Eu (Ln=Lu, Y, Gd and La) have been measured at room temperature. The observed four Raman lines are divided into low and high-frequency groups, each consisting of A 1g and E g modes in representations of D 3d crystal point group. The high-frequency lines shift toward low frequency with inc…
An experimental investigation on the aqueous polymerization of acrylamide with potassium persulfate initiator is reported. Molecular weight averages were measured by viscometry. Non-Newtonian effects were accounted for by extrapolation to high shear rates where the polymer solutions approximated Newtonian behavior. Va…
Maximum stable lengths of the floating-liquids zone (lmax) were measured in the small-diameter (d=0.25–1.5 mm) float-zone crystal growth of sapphire and silicon. A 100-W cw CO2 laser was used as power source. The measured ratios of lmax/d for sapphire and silicon are in good agreement with the theoretical analyses by…
It has been postulated that corrosion of photoanodes and its suppression are correlated with the presence of sulfate radicals. This idea was investigated by measuring the effects of light intensity, Co 2+ concentration, and concentration on corrosion rate. Results showed that corrosion rate was proportional to , that…
Abstract Thermal transformation of chrysotile from Uruaçu District, state of Goiás, Brazil, heated in dry conditions at temperatures from 600°C to 1300°C was studied by high resolution electron microscopy and selected area electron diffraction (SAD). Up to 600°C, no morphological or SAD pattern changes were observed.…
The problems of scattering of plane compressional and shear waves by a class of infinite circular cylindrical flaws and inclusions embedded in an infinite isotropic homogeneous elastic medium are solved. The objects considered are an elastic cylinder, an inviscid-fluid-filled cavity, an empty cavity, and a rigid cylin…
Formation of membranes from a binary system, poly(vinyl chloride) and dimethylformamide, was studied. Phase separation during membrane formation was caused by absorption of aqueous vapor from the atmosphere. The membrane structure was closely related to the degree of phase separation. The membrane formation process wa…
Two epipelic diatoms with contrasting chloroplast morphology were found, which on the basis of valve morphology and the limited criteria available for specific determinations, could fall into one species, Navicula scopulorum Bréb. Investigation using electron microscopy revealed a number of structural differences on w…
Epoxidation of styrene–butadiene block polymers considerably improves their resistance to hydrocarbon oils. Use of peroxyformic acid generated in situ appears to be simple and practical. Although no problems exist when the reactions are carried out in toluene, polymer molecular weight and reactant stoichiometry are im…
The single-crystal elastic constants of vanadium and of vanadium with 1.07, 1.85, and 3.46 at.% oxygen have been measured ultrasonically over the temperature range 4.2–300 K. These compositions cover virtually the complete composition range of the terminal solubility at the temperatures of the experiments. Monotonic b…
${\mathrm{Na}}_{2}$C${\mathrm{O}}_{3}$ has an incommensurate phase transition at 619.5 K. The temperature dependence of a satellite reflection and of the length of the modulation wave vector ${\stackrel{\ensuremath{\rightarrow}}{\mathrm{q}}}_{0}$ has been investigated below this temperature using neutron diffraction.…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemical evolution. 33. Photochemical decarboxylation of orotic acid, orotidine, and orotidine 5'-phosphateJ. P. Ferris and P. C. JoshiCite this: J. Org. Chem. 1979, 44, 13, 2133–2137Publication Date (Print):June 1, 1979Publication History Published online1 May 2002Published…