Materials Literature
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Abstract The dynamic mechanical, and physical properties of bromobutyl rubber were investigated to determine the effect of particle size and of the structure of carbon black and silica. Filler loading was so adjusted that all the experimental compositions had the same hardness level. The results indicate that the type…
A series of experiments has been performed on the Sandia Hypervelocity Launcher to determine the performance limits of conventional Whipple shields against representative 0.8 g aluminum orbital debris plate-like fragments with velocities of 7 and 10 km/s. Supporting diagnostics include flash X-rays, high speed photogr…
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” opt…
Measurements of the thermopower in the charge density wave compound (NbSe 4 ) 10 I 3 show a large hysteresis between the cooling and heating cycles below and above the Peierls transition temperature. The magnitude of the observed hysteresis depends on the lowest temperature reached in the cooling regime. This effect i…
In considering the trade-off between second-order nonlinearity and transparency, a new organic molecular crystal 3-methoxy-4-hydroxy-benzaldehyde (MHBA) has been grown from solution by the temperature lowering method for the first time. MHBA belongs to the monoclinic system, and its space group is P21. The unit cell d…
The magnetic-field penetration depth \ensuremath{\lambda} in the organic superconductors \ensuremath{\kappa}-(BEDT-TTF${)}_{2}$ Cu(NCS${)}_{2}$ and \ensuremath{\kappa}-(BEDT-TTF${)}_{2}$ Cu[N(CN${)}_{2}$]Br has been measured over a wide temperature region 20 mK\ensuremath{\le}T\ensuremath{\le}15 K via the muon-spin-re…
First-principles electronic structure calculations have been performed for the intermetallic compound YCo5. This compound is known to have unusually large cobalt orbital magnetic moments and one of the largest magnetocrystalline anisotropies among itinerant ferromagnets. By including spin-orbit coupling and orbital po…
Pyrochlore to perovskite phase transformation in sol-gel derived lead-zirconate-titanate (PZT) films was studied by x-ray diffraction and transmission-electron microscopy (TEM). X-ray diffraction studies of PZT films on sapphire substrates indicated that the pyrochlore to perovskite phase transformation was completed…
We have performed large-scale total-energy electronic-structure calculations within the local-density approximation for the negatively charged vacancy in Si. The obtained Jahn-Teller distortion, the electronic structures, and the hyperfine coupling tensors are in good agreement with the experimental data available, in…
A type IIa natural diamond was irradiated at room temperature with energetic electrons. The threshold energy for displacement of atoms from their lattice sites was determined for three principal crystallographic directions by observing the formation of defect clusters during irradiation in a transmission electron micr…
The force as a function of separation is measured between two mica surfaces coated with adsorbed bilayers of cetyltrimethylammonium bromide (CTAB) and immersed in aqueous ionic micellar solutions of CTAB. At low separations double-layer forces are observed and arise soley from the dissociated counterions and free ${\m…
Molecular dynamics simulations reveal the mechanism of the structural memory effect in alpha-berlinite (AlPO(4)), where a single crystal transforms to an amorphous solid by compression and then reverts to the original crystalline structure upon release of pressure. The enhanced oxygen coordination around the aluminum…
Abstract Ferromagnetism is a well-known phenomenon wherein solids exhibit spontaneous magnetization even in the absence of an external magnetic field. An important characteristic of ferromagnetic materials is the hysteresis loop found in the relationship between magnetization and magnetic field. The electrical analogu…
To investigate the pH dependence of the conformational stability of barnase, urea denaturation curves were determined over the pH range 2-10. The maximum conformational stability of barnase is 9 kcal mol-1 and occurs between pH 5 and 6. The dependence of delta G on urea concentration increases from 1850 cal mol-1 M-1…
Cathodoluminescence (CL) in a transmission electron microscope has been used to investigate impurities and defects in single crystals in diamond films grown by the combustion-flame method and correlate them with the microstructure. Nitrogen was present in a number of different impurity defect forms; band A emission wa…
The Nasicon-type phosphate CuZr 2 (PO 4 ) 3 exhibits two fluorescences occurring in the violet and green regions. They are assigned to two different centres: the violet one to isolated Cu + and the green one to Cu + -Cu + pairs occupying the same site. These assignments are in agreement with previous structural invest…
We describe a new technique for measuring the thickness and optical constants of dielectric, semiconducting, and thin metal films. Beam profile reflectometry provides excellent precision for films as thin as 30 Å and as thick as 20 000 Å. The technique is also capable of simultaneous 2 and 3 parameter measurements and…
We show by scanning tunneling microscopy (STM) imaging that native oxide growth in moist air on hydrogen terminated Si(111) 1×1 surfaces begins by continuing formation of small oxide nuclei, 10–20 Å in diameter, in the topmost Si layer. Their statistical distribution on the flat terraces points to a homogeneous nuclea…
Gadolinium clusters (N=11--92) in a molecular beam exhibit dramatic size dependences in their magnetic properties. Two principal behaviors are observed: rigid rotor precession and nutation when the magnetic moment is tightly locked to the lattice by crystal anisotropy, and superparamagnetism when the moment is approxi…
Unidirectional charge flow was observed in potassium tantalum niobate, ${\mathrm{KTa}}_{0.6}$${\mathrm{Nb}}_{0.4}$${\mathrm{O}}_{3}$, films. These films of relaxor-type diffuse phase transition material were formed by metalorganic deposition and had a polarization gradient normal to the surface of the films. Novel cha…