Materials Literature
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The recently discovered incommensurate phase of quartz close to the α-β transition has been investigated using Brillouin scattering. The frequency and the damping of the longitudinal (LA) and transverse (TA) acoustic modes propagating along the X, Y and Z directions have been measured as a function of the temperature…
We extend the wedge technique of Rivière et al. to measure the pretilt angle Φ and the (weak) anchoring energy of a nematic liquid crystal oriented on a suitably treated glass surface. The liquid crystal is placed in a wedge shaped space formed by the plate to be studied and a « standard » plate giving a strong homeot…
The potential impact of oxygen from roots on the source of inorganic nitrogen for Ruppia maritima L. (Potarnogetonales) was investigated in laboratory experiments. Roots released oxygen at a n average rate of 2 to 3 ~g 0, (mg dry wt)-' h-'. A distinctive oxygenated zone with a radius of 0.75 to 1.25mm developed in the…
The crystal structures of two manganoan 1M-phlogopites and kinoshitalite-1M (Ba, Mn brittle mica) have been re-examined to determine if cation ordering patterns in subgroup symmetries exist. In all cases, the X-ray single crystal data are better explained by the ideal symmetry of C2⁄m, which requires only one tetrahed…
Glass formation in the system PbO–PbF2 has been investigated. The structure of these glasses has been studied using X-ray diffraction. Densities, heat capacities, glass-transition and crystallization temperatures and Vicker's microhardnesses have been measured. D.c. conductivities of these glasses have also been measu…
Contrarily to previous expectations, the flat geometry is not the configuration of lowest free energy for the bilayers of SDS in the lamellar phase of SDS/water. Indeed, neutron scattering reveals an unusual pattern of diffuse scattering at small angles, in addition to the regular diffraction spots of a layered mesoph…
Nous avons étudié la structure des deux mésophases d'une molécule discoïde chirale par diffraction des rayons X et par observation optique. La comparaison des deux techniques nous a permis de déterminer quelques-uns des paramètres de la structure. La transition entre les deux mésophases semble être du type ferroélectr…
The oxidation reactions of hindered phenols by molecular oxygen catalysed by monomeric and polymeric cobalt–Schiff base complexes, cobalt and manganese porphyrins, and (pyridine)cobaloxime are described; the rate and selectivity of these reactions are very dependent on the catalyst and on the solvent.A new product has…
Activation and reaction volumes are reported for the interconversion of the 1A and 5T isomers of FeII complexes in several solvents; the reaction volume ΔV° and the activation volume ΔV15‡ are solvent-dependent but ΔV51‡ for the 5T →1A crossover is markedly negative and virtually solvent-dependent and a transition sta…
Abstract Small‐angle neutron scattering, SANS, stands forth as one of the most important of the new tools for evaluating polymer chain conformation and morphology. This paper reviews the SANS literature through 1982, with a few early 1983 references added. The theory of SANS is outlined and compared to light scatterin…
Preoxidised (OX) or prereduced (RED) TiO2(anatase) powder was exposed to N18O at 295 K in the dark. Three phenomena resulted from subsequent ultraviolet illumination: photoadsorption, photoexchange (with a much higher rate than with 18O2) and photodecomposition forming N2O and, to a lesser extent, N2. The initial rate…
We have carried out an extensive high resolution x-ray scattering study of the nematic-smectic A (N-S A) and reentrant nematic-smectic A (RN-SA) phase transition behaviour in mixtures of octyloxycyanobiphenyl (8OCB and hexyloxycyanobiphenyl (60CB). The smectic A phase boundary is found to be parabolic in the temperatu…
A method for determining the tryptophan content of feed and feedstuffs was established. This method involved three steps: alkaline hydrolysis, pretreatment of the hydrolysate for chromatography, and measurement of tryptophan by ion exchange liquid chromatography. With this method, the recovery of tryptophan in egg-whi…
Subsolidus phase equilibria in the system La 2 O 3 ‐P 2 O 5 were established. The system contains six intermediate compounds having molar La 2 O 3 :P 2 O 5 ratios of 3:1,7:3,1:1,1:2,1:3, and 1:5. It was found that the 3:1 compound has a phase transformation at 935°C. The 1:2 compound decomposes to a mixture of 1:1 and…
The collective transport of charge density waves (CDW) converts into an ordinary current at the contacts with a normal metal. In the present work this conversion is proposed to proceed via the process of phase slippage (PS). The CDW in the quasi-one-dimensional system with a nested Fermi surface and impurities is desc…
The crystal structure of the title compound, [Cu(bipy)2][PF6]2(1), has been determined by X-ray crystallographic methods, using diffractometer data collection; the structure was solved by the heavy-atom method and by successive Fourier syntheses. Compound (1) crystallises in the tetragonal space group I41/acd, a= 16.2…
More than 40 protein species including RNA polymerase were found to be phosphorylated in Escherichia coli on analyses of 32P-labeled cell lysates by single and two-dimensional gel electrophoresis and autoradiography. The protein species and the level of phosphorylation varied depending on the cell growth phase. With […
We report high resolution X-ray scattering measurements of the smectic phases and phase transitions in the material N-(4-n-butyloxy-benzylidene)-4-n-heptylaniline (40.7) (I → N → Sm A → Sm C → Sm B). For the nematic to smectic A transition we have measured the critical exponents γ = 1.45 ± 0.03, ν ∥ = 0.78 ± 0.02, and…
A selection of aliphatic alkenes, substituted styrenes, and cis-stilbene has been epoxidised with aqueous NaOCl, employing two different porphyrins, Mn(TPP)OAc and Mn(TMP)Cl, as catalysts. Large increases in reaction rate, product selectivity, and stereoselectivity are found with the bulkier TMP ligand. The results ar…
The adsorption of acridine orange by H-, Na-, Mg-, Al- and Cu-montmorillonite has been studied by visible and infrared spectroscopy and by X-ray diffraction methods. Adsorption of the dye takes place by the mechanism of cation exchange. The maximum amount of adsorbed dye depends on the exchangeable metallic cation, de…