Materials Literature
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Abstract The oscillations of the current which take place during the anodic dissolution of silicon in fluoride electrolytes have been investigated. These oscillations occur only upon a perturbation in the electrode potential, and are associated with a fluctuation of the thickness of an oxide layer on the electrode sur…
We report a new surface phenomenon in flowing colloidal suspensions of anisotropic particles. It is characterized by a decrease in the probability of presence of the solute particles near the cell walls when the solution is submitted to Poiseuille flows exceeding a minimum shear rate. The effect has been detected on d…
Preparation of potassium niobate from metal alkoxides was investigated. Potassium‐niobium ethoxide, KNb(OC 2 H 5 ) 6 , and potassium‐niobium propoxide, KNb(OC 3 H 7 ) 6 , were synthesized and subsequently hydrolyzed using several water concentrations (0.75 to 6.0 mol of water/(mol of alkoxide)). Rapid precipitation of…
The complexes cis-[MCl(CO)2(n-OPhVPy)](M = Rh, Ir; n-OPhVPy =trans-4-alkyloxy-4′-stilbazole) are mesomorphic showing nematic and smectic A phases at temperatures below 140 °C.
Abstract A series of segmented polyurea urethane and polyurea block copolymers based on a hexane diisocyanate (HDI) modified aminopropyl terminated polydimethylsiloxane soft segment was synthesized. The hard segments consisted of 4,4′‐methylene diphenylene diisocyanate (MDI) which was chain extended with 1,4‐butanedio…
Organically modified ‘Keggin-type’ oxopolymetalates of general chemical formula [R]4[SiW11O40(SiR″)2], (R = H+, K+ or NR′4+; R′= Me or Bu; R″= Et, CHCH2, C10H21 or Ph) have been synthesised by three different procedures. Large quantities were obtained in high purity and good yield. Their structure has been established…
Abstract Reactions of O 2 and H 2 O to from thin oxides on Fe, Ti and Ti‐modified Fe thin films have been studied by XPS, following O 2 and H 2 O exposure in the range 0‐600 L, to form oxides with thicknesses of < 40 Å. XPS Iineshape analysis is used, utilizing a special combination of reflection electron energy‐lo…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrdering at diblock copolymer surfacesPeter F. Green, Thomas M. Christensen, and Thomas P. RussellCite this: Macromolecules 1991, 24, 1, 252–255Publication Date (Print):January 1, 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://pubs.…
The meso-octamethyl porphyrinogen tetraanion has been used to bind iron(III) and oxomolybdenum(V) ions; X-ray analysis revealed the interaction of a square-planar tetracoordinate FeIII and the oxo group in the MoV complex with the meso-methyls.
A series of para-substituted styrylstilbenes I and 9,10-distyrylanthracenes II was synthesized by Wittig or Arbusov–Horner reaction as a key step. Subsequently, systematic investigations were carried out on their absorption and fluorescence spectra, and their chemiluminescence properties. It has become apparent that s…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTime-resolved small-angle neutron scattering in intermediate- and late-stage spinodal decomposition of perdeuterated polybutadiene-protonated polyisoprene blendsHiroshi Jinnai, Hirokazu Hasegawa, Takeji Hashimoto, and Charles C. HanCite this: Macromolecules 1991, 24, 1, 282–…
The stoichiometry and the stability of the complexes formed in the Th(IV)-H 2 O-CO 2 (g) system have been investigated by the EMF technique in a 3.000 M NaClO 4 ionic medium at 25 o C, using coulometry to vary the hydrogen ion concentration
Model experiments have been conducted on a series of alumina samples in which the microstructures have been tailored to conform to the classical configurations depicted in the models of final-stage sintering. Simultaneous measurements of sintered density, grain size, pore number density and pore size distribution were…
Comparison of results obtained from 1,1′- and 1,3-disubstituted ferrocenes clearly demonstrates the influence of structural isomerism on the mesomorphic properties.
In the past two decades, photoelectron spectroscopy has emerged as an indispensable tool for studying the electronic properties of solids and their surfaces. 1'2 This is because it provides the most direct and complete method of measuring all the occupied electronic states in a solid, both core and valence. This revie…
A Mg85Zn12Ce3 amorphous alloy containing finley dispersed hcp-Mg particles was found to form either by melt spinning or by heat treatment of the melt-spun ribbon. The particle size and interparticle distance of the hcp-Mg phase can be controlled in the range of 3 to 20 nm and 5 to 10 nm, respectively. The mixed phase…
This paper discusses the conformational phase change of an isolated polymer chain which is capable of forming physical bonds with solvent molecules. On the basis of the mean-field theory of Flory type, we derive a formula for the temperature dependence of the expansion factor of the chain. Our theory takes account of…
Calcite surface energy and morphological changes observed in the presence of Mg2+ and Li+ ions are predicted using atomistic simulation based on the Born model of solids.
Anodic segregation of selected alloy constituents is found by ESCA analysis to occur as a result of active dissolution and during the passivation of stainless steel in deaerated acid. The resulting surface composition of the steel is radically different from the bulk and conditions seem to favour the formation of surf…
All large spacecraft are susceptible to impacts by meteoroids and orbiting space debris. These impacts occur at extremely high speed and can damage flight-critical systems, which can in turn lead to a catastrophic failure of the spacecraft. Therefore, the design of a spacecraft for a long-duration mission must take in…