Materials Literature
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Abstract Structural transformations of illite-smectite samples of hydrothermal genesis with increasing contents of illite layers were studied by X-ray powder diffraction. The samples were K-saturated and subjected to wetting and drying cycles to increase three-dimensional structural ordering. Diffraction profiles were…
Electrochemistry of Conductive Polymer: XIX. Oxidation of Aniline at Bare and Polyaniline‐Modified Platinum Electrodes Studied by Electrochemical Impedance Spectroscopy, Johnson, Bryan J., Park, Su‐Moon
The structures of six crystalline inclusion complexes of cyclotriveratrylene (1) (CTV) containing water, toluene, bromobenzene, chloroform, acetone and dimethoxyethane have been determined by X-ray crystallography. Four are of the α phase whilst the other two are the first reported structures of the β phase. Based upo…
It is proposed that quasicrystal structure determination should include the calculation of cohesive energies using realistic potentials. A class of atomic decoration models for $i$-AlMn is then presented, adopting the "canonical-cell" tiling geometry, with "Mackay icosahedron" clusters placed on all its nodes. The rem…
The effect of the morphology of second phases in sintered microstructure on the thermal conductivity of AIN ceramics was investigated. When an Y 2 O 3 ‐doped AIN specimen was cooled down slowly at a rate of 3°C/min after sintering at 1850° or 1900°C, the second phases were concentrated in the corners of the AIN grains…
The P13K SH3 domain, residues 1 to 85 of the P1-3 kinase p85 subunit, has been characterized by X-ray diffraction. Crystals belonging to space group P4(3)2(1)2 diffract to 2.0 angstroms resolution and the structure was phased by single isomorphous replacement and anomalous scattering (SIRAS). As expected, the domain i…
The properties of α‐sexithiophene (α‐T 6 ), e.g., the pronounced one‐dimensionality of the molecule (see Figure), the layered crystal packing, and the low exciton binding energy, make it a very interesting material for electronic and optoelectronic applications. Investigations into the origin of its optical gap and co…
Thin polyimide films with dispersed nano-foam morphology have been prepared for the purpose of obtaining low dielectric polymer insulators for microelectronic applications. They were obtained by utilizing micro phase-separated triblock copolymers where the thermally stable polyimide matrix component was derived from p…
It has been reported that the activation of dihydrofolate reductase (DHFR) from L1210 mouse leukaemia cells by KCl or thiol modifiers is accompanied by increased digestibility by proteinases [Duffy, Beckman, Peterson, Vitols and Huennekens (1987) J. Biol. Chem. 262, 7028-7033], suggesting a loosening up of the general…
The N-carbamyl-D-amino-acid amidohydrolase from Agrobacterium radiobacter NRRL B11291, the enzyme used for the industrial production Of D-amino acids, was cloned, sequenced, and expressed in Escherichia coli. The protein, a dimer constituted by two identical subunits of 34,000 Da with five cysteines each, was suscepti…
The nature and degree of damage accumulation beneath Hertzian contacts in silicon nitride‐based laminates are studied. Specimens with alternating homogeneous and heterogeneous layers are fabricated by a tape‐casting route, with strong interlayer bonding. Homogeneous material consisting of relatively pure fine‐grain si…
Since their discovery in the 1960s, shape memory alloys have been developed for a wide range of applications. However, it was not until the 1970s that the use of memory metals in medicine started to receive attention. Since then, a multitude of clinical functions have been looked into, all of which use the Nickel-Tita…
All articles of this category Chiral hyperbranched macromolecules catalyze the enantioselective diethylzinc addition to benzaldehyde. The corresponding secondary alcohol has been obtained in high yield with good enantioselectivity (up to 86% ee ). Hyperbranched Macromolecules - Dendrimers - Asymmetric Catalysis - Enan…
Vibrational frequencies for 11 alkenes and 8 conjugated hydrocarbons have been analyzed with MM4. The root mean square (rms) difference between the experimental and MM4 values is 25 cm−1 for seven alkenes and 31 cm−1 for eight conjugated hydrocarbons, compared to MM3 rms differences of 38 cm−1 for alkenes and 52 cm−1…
In two consecutive one-electron oxidations, oligopyrroles substituted with phenyl capping groups (PhPynPh, n = 2–4) can be oxidized reversibly to give stable cation radicals and dications. Spectroelectrochemical studies give direct evidence that diamagnetic π-dimers of cation radicals are formed in solution. Such dime…
The phase field model in two dimensions is used to calculate numerically the operating states (tip velocity $v$ and tip radius $\ensuremath{\rho}$) of dendrites grown from pure melts. At large supercoolings, a dendrite has a nearly hyperbolic envelope close to its tip, as opposed to being nearly parabolic, as at small…
Jahn-Teller (JT) electron-phonon-coupling effects in the colossal-magnetoresistance perovskite compounds ${\mathrm{La}}_{1\ensuremath{-}x}{A}_{x}\mathrm{Mn}{\mathrm{O}}_{3}$ are investigated. Electron-electron correlations between two degenerate Mn ${e}_{g}$ orbitals are studied in the Gutzwiller approximation. The st…
Coexistence of two phases, having different in-plane dimensions, is found in the planar Sr2−xLaxMnO4 for 0 < x ≤ 0.38 at room temperature. Furthermore, charge ordering with modulation wave vector (π2, π2) is discovered for x=0.5 below ∼ 250 K. Together with transport and magnetic measurements, these results indicate t…
The origin of spurious and irreproducible signals in the measurement of the hyper-Rayleigh scattering (HRS) of solutions is investigated. A new cell design, coupled with continuous solution filtration through a 20 nm filter, is shown to improve the reproducibility of the measurement to ±5%. A transverse cell dimension…
Abstract The polymerization of a bismaleimide‐styrene system was studied by using a model compound, p‐maleimidobenzoic anhydride, that can be split by simple hydrolysis. Compared to known divinyl systems, a decreased reactivity of the pendant double bonds is observed, probably as a result of cyclization and the steric…