Materials Literature
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Abstract Partial segregation of reagents occurs when reaction rates exceed mixing rates and frequently causes product distributions to be mixing‐dependent. A simultaneous temperature segregation, whereby the temperature in a reaction zone differs from that in its surroundings, has rarely been considered when mixing re…
Alpha-Tocopherol concentrations were determined in the CSF of patients with early untreated Parkinson's disease receiving 2,000 IU vitamin E orally per day. After treatment the concentrations increased significantly (p < 0.001) by 76+/-10 (SE)%. The net increases in CSF alpha-tocopherol concentrations after treatment…
Direct evidence of half-metallic density of states is observed by scanning tunneling spectroscopy of ferromagnetic La0.7Ca0.3MnO3 and La1−xSrxMnO3 (x=0.3, 0.33) epitaxial films which exhibit colossal magnetoresistance (CMR). At 77 K, well below the Curie temperatures, the normalized tunneling conductance (dI/dV)/〈I/V〉…
Cold neutron triple-axis measurements have been used to investigate the nature of the long-wavelength spin dynamics in strongly doped La1−xSrxMnO3 single crystals with x=0.2 and 0.3. Both systems behave like isotropic ferromagnets at low T, with a gapless (E0&lt;0.02 meV) quadratic dispersion relation E=E0+Dq2. Th…
An experimental and theoretical analysis of finite size effects in submicron barium titanate particles is presented. The dielectric data show that the dielectric constant (∊ = 734) of small particles (d = 20 nm) remains very similar to that of single crystals provided that the particles are grown from an amorphous pha…
Abstract cis,cis,cis-1,3,5,7-Tetrahydroxy-1,3,5,7-tetraisopropylcyclotetrasiloxane (1) was synthesized. The X-ray crystallography of 1 revealed that four molecules of 1 and four molecules of water compose a cluster in the lattice. Dehydration of 1 with N,N'-dicyclohexylcarbodiimide (DCC) gave octa(isopropylsilsesquiox…
A recombinant hydroxylated fragment of human type III collagen has been produced in Saccharomyces cerevisiae by coordinated coexpression of a collagen gene fragment together with both the alpha- and beta-subunit genes for prolyl-4-hydroxylase (EC 1.14.11.2). The collagen fragment consisted of 255 residues of the helic…
Stark (electroabsorption) spectroscopy can provide quantitative information on the change in dipole moment and polarizability for an electronic transition. In the case of mixed-valence transitions, the change in dipole moment associated with the intervalence charge-transfer band can be used to establish the effective…
Abstract A series of LDPE blends with plasticized (PLST) and granular starch (FILST) were prepared. Ethylene/vinyl acetate (EVA) copolymer was used as a compatibilizer in three different amounts: 10, 25 and 50 wt% based on starch. The blends were studied by Fourier transform infrared spectroscopy (FTIR), differential…
Investigations show that continuous ultrasound produces modulated mass transport in sonovoltammetry. At mass‐transport‐limited potentials, voltammetry in the presence of ultrasound shows near‐steady‐state behavior with large current output that oscillates about a stable, average value. The current signal consists of a…
Adsorption-controlled conditions have been identified and utilized to grow epitaxial bismuth titanate thin films by reactive molecular beam epitaxy. Growth of stoichiometric, phase pure, c-axis oriented, epitaxial films is achieved by supplying a large overabundance of bismuth and ozone continuously to the surface of…
An ultrathin (ca. 5.6 nm thick), closely packed (self‐assembly), tightly interconnected (two‐dimensional polymer), and water‐repellent (>130° of the contact angle with water) film was prepared by modification of an 11‐mercapto‐1‐undecanol self‐assembled monolayer adsorbed on a copper surface with 1,2‐bis(trichlorosily…
[PMo12O40(VO)2]5- is a highly reduced cluster with eight d metal electrons. The localization−delocalization nature of d metal electrons is one of the points of interest in reduced polyoxoanions. We report DFT calculations which suggest that the oxidation state of the V atoms is +4 and that the other six metal electron…
Many known occurrences of the zeolites erionite and offretite have been characterized by electron probe microanalysis, X-ray powder diffraction, and optical microscopy. For the first time, a substantial amount of experimentally consistent and homogeneous chemical and crystallographic data have been evaluated for these…
Polycaprolactone (PCL) was grafted onto starch through introduction of urethane linkages. The grafting reaction was carried out in two steps. The first step was the reaction of hydroxyl-terminated PCL with 2,4-tolylene diisocyanate. The isocyanate terminated PCL was then reacted with starch to obtain starch-graft-poly…
Scanning electrochemical microscopy (SECM) in ferrocyanide and bromide solutions was used to locate active sites (pitting precursors) on polycrystalline Ti where oxidation of Br − and Fe ( CN ) 6 4 − was possible. Analysis of the electroctro‐chemically active sites was done by using electron microscopy (SEM), energy d…
The ferromagnetism of the inhomogeneous crystalline structure arising below the temperature of the martensitic phase transition is considered using a phenomenological expression for the Helmholtz free energy of a cubic crystal. The magnetic anisotropy of the martensitic structure is related to the order parameter of t…
Copolymerization of glycolide (Glyc) and L-lactide (L-Lac) were conducted at 150°C in bulk to prepare random copolyesters. Four resorbable catalysts were used and compared: ZnCl2, ZnI2, Zn stearate (ZnSte2) and Zn lactate (ZnLac2). Separate time-conversion curves were recorded for glycolide and lactide by means of 1H…
New photoisomerizable chiral dopants have been studied. The dopants used were menthone derivatives, a chiral stilbene derivative and a nematic copolymer of a menthone derivative and a benzoyloxybenzonitrile derivative. NMR, HPLC and UV results showed that the E-Z-isomerization of all the compounds indicated proceeded…
The structures of carbonaceous deposits obtained through laser ablations using targets composed of C, Ni, and Co under various Ar gas pressures were studied. The pressure dependence of the target's surface morphology and the structure was also studied. When the pressure was 100 Torr or below, only carbon was evaporate…