Materials Literature
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[reaction: see text] The reaction pathway for peroxide-initiated aldehyde-mediated oxidation of olefins to epoxides by molecular oxygen has been studied. The pathways of reaction via a peroxy acid or an acyl peroxy radical have been differentiated by investigation of the reaction of 4 with oxygen to provide 6 via 8.
Delta 5-3-ketosteroid isomerase (KSI) catalyzes the allylic isomerization of Delta 5-3-ketosteroids at a rate approaching the diffusion limit by an intramolecular transfer of a proton. Despite the extensive studies on the catalytic mechanism, it still remains controversial whether the catalytic residue Asp-99 donates…
The hexamolybdopyrophosphate [(O3POPO3)Mo6O18(H2O)4]4- (1) has been characterized by 31P NMR, IR, elemental analysis, and single-crystal X-ray diffraction. This polyoxoanion consists of a six-membered ring of MoO6 octahedra, which alternate in sharing edges and corners. The (O3POPO3)4- anion is bound with P(1) in the…
The novel, dimeric polyoxometalate [{(P2O7)Mo15O45}2]8- has been characterized by 31P NMR spectroscopy and single-crystal X-ray diffraction. The 30-molybdobispyrophosphate contains two eclipsed diphosphate ions with linear P−O−P bonds (180.0(10)°). The polyanion can be viewed as a fused dimer of two lacunary [(P2O7)Mo…
CVD studies devoted to platinum and palladium deposition on planar substrates for microelectronics have clearly shown that it is possible to reach high-quality deposits at temperatures above 200 °C. Attempts to prepare pure metallic deposits at temperatures around 100 °C and even lower are of general interest, since a…
A series of disklike compounds containing the pyrazabole ring have been prepared by reaction of 3,5-diarylpyrazoles and borane. The aryl groups are benzene rings substituted with one, two, or three hexyloxy, decyloxy, or tetradecyloxy groups. The study of the liquid crystalline properties shows that the optimal chain…
Thin stacks consisting of a single intrinsic Josephson junction on (Bi,Pb)-Sr-Ca-Cu-O thin films are investigated under the influence of external microwave fields. The $I$-$V$-characteristic shows a single resistive branch, a clear superconducting gap edge structure and a pronounced current step in external microwave…
A microscopic theory for the coupling of intrinsic Josephson oscillations and dispersive phonon branches in layered superconductors is developed. Thereby the effect of phonons on the electronic c-axis transport enters through an effective longitudinal dielectric function. This coupling provides an explanation of recen…
We derive a formula, useful for first-principles calculations, which relates the free energy of an oxide/metal interface to the free energies of surfaces and the work of separation of the interface. We distinguish the latter {\it mechanical} quantity from the {\it thermodynamic} work of adhesion, and we describe expli…
A review of the approximations in any time-dependent density functional calculation of excitation energies is given. The single-pole approximation for the susceptibility is used to understand errors in popular approximations for the exchange-correlation kernel. A new hybrid of exact exchange and adiabatic local densit…
In seeking to understand at a microscopic level the response of dislocations to stress we have undertaken to study as completely as possible the simplest case: a single dislocation in a two dimensional crystal. The intention is that results from this study will be used as input parameters in larger length scale simula…
The role of the exchange-correlation potential and the exchange-correlation kernel in the calculation of excitation energues from time-dependent density functional theory is studied. Excitation energies of the He and Be atoms are calculated, both from the exact ground-state Kohn-Sham potential, and from two orbital-de…
A scheme for making ab-initio calculations of the dynamic paramagnetic spin susceptibilities of solids at finite temperatures is described. It is based on Time-Dependent Density Functional Theory and employs an electronic multiple scattering formalism. Incommensurate and commensurate anti-ferromagnetic spin fluctuatio…
A simple description of thermodynamics of DMAAS and DMAGaS ferroelectric crystals by means of Landau expansion is proposed. Conditions of occurrence of phase transitions are established and their temperatures are obtained. The influence of external hydrostatic pressure on phase transitions is described. The temperatur…
This paper demonstrates that, by using oil-in-water micelles, nonstoichiometric zinc ferrite nanoparticles are fabricated. Control in size and composition is obtained. The nanocrystals are characterized by a spinel structure with two sublattices in tetrahedral and octahedral sites. Repartition of Fe 3+ in the two subl…
The elastic moduli of polymerically stabilized suspensions consisting of colloidal silica particles coated with endgrafted PDMS ( M n = 80 000) in heptane, were measured as a function of concentration. And the elastic modulus at high frequency was quantitatively described by model calculations with microscopic paramet…
The intensity maxima of lamellar reflections in small-angle scattering patterns from uniaxially oriented polymers such as fibers do not generally fall on a straight layer line or on a circular arc. The shape of the reflection can be analyzed by measuring the periodicity L φ of the lamellar planes as a function of the…
A combined microcalorimetry and adsorption study has been used to characterize the surface acidity of two series of MCM-41 aluminosilicates (referred to as SiAl x C n, where x is the mole Si:Al ratio and n the chain length of the surfactant template). 29 Si magic angle spinning NMR spectra of a selected sample (SiAl32…
[reaction: see text] The formal synthesis of the ocular age pigment A2-E was achieved by the efficient one-pot preparation of the substituted pyridine, which involves the aza-6pi-electrocyclization of the Schiff base derived from (E)-3-carbonyl-2,4,6-trienal followed by oxidation.
With the help of a Si(Li) detector, incoherent scattering cross sections of Ag, In and Sn were determined from 40°-135° in the case of 59.54 keV gamma rays of Am-241. A new method has been developed to determine differential incoherent scattering cross sections of elements. This method is based on simultaneous measure…