Materials Literature
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We have cloned and sequenced genes for triosephosphate isomerase (TPI) from the gamma-proteobacterium Francisella tularensis, the green non-sulfur bacterium Chloroflexus aurantiacus, and the alpha-proteobacterium Rhizobium etli and used these in phylogenetic analysis with TPI sequences from other members of the Bacter…
Abstract One of the most common methods of preventing downhole and topside mineral scale formation in oilfields is through the use of chemical scale inhibitors. Several aspects of the brine composition may affect the performance of the various scale inhibitors used in oilfield applications and, in this paper, we will…
Trypsin and chymotrypsin have similar tertiary structures, although very different substrate specificities. Trypsin hydrolyzes peptides at Lys/Arg residues while chymotrypsin recognizes large hydrophobic residues. Recent work has shown that trypsin is not converted into a protease with chymotrypsin-like activity when…
We present a computer simulation study of orientational correlations in a molecular liquid approaching the isotropic-nematic transition, including the first calculation of the direct correlation function $c(1,2)$ in this regime. While the second-rank orientational correlation length diverges, the associated component…
Partially miscible binary liquids containing silica colloids show equilibrium phase boundaries and critical lines. The phase separation is ternary in nature, and measurements allow construction of the ternary phase prism for colloids dispersed in binary fluid mixtures. Comparison with earlier aggregation studies stron…
We report x-ray intensity fluctuation spectroscopy measurements of the equilibrium dynamics of polymer micelle liquids, composed of polystyrene-polyisoprene block copolymer micelles within a polystyrene homopolymer matrix. The equilibrium dynamics were investigated for times between one and several hundred seconds, an…
Combining the use of a UV storage ring free electron laser and of synchrotron radiation, a time resolved core level spectroscopy study has been performed on photoexcited Si(111)2×1 surfaces with subnanosecond resolution. This enabled us to measure band bending fluctuations, caused by surface carrier dynamics, during t…
Magnetic entropy change of La0.75Ca0.25MnO3 with different particle size has been investigated. Magnetic entropy change ∼4.7 J/kg K larger than that of Gd has been observed at 224 K under a magnetic field of 1.5 T in comparatively big particles. This phenomenon of large magnetic entropy change indicates that the perov…
The dynamics of single bubble sonoluminescence (SBSL) strongly depends on the percentage of inert gas within the bubble. We propose a theory for this dependence, based on a combination of principles from sonochemistry and hydrodynamic stability. The nitrogen and oxygen dissociation and subsequent reaction to water sol…
Direct experimental evidence is presented for the existence of localized excitations on fractal supermolecular structures that may serve as photonic antenna systems. For one dendrimer family the electronic spectra show no redshift with system size, indicating that the excitations are localized at the nodes of the Cayl…
The crystal structure of potassium tungsten tetraselenide is based on isolated, slightly distorted WSe4 tetrahedra joined via K+ ions. The compound is isotypic with the previously reported Rb and Cs analogues and crystallizes in the β-K2SO4 structure type.
The atomic structure and tunneling spectra of a cleaved surface of a 2H-NbSe 2 single crystal were studied by scanning tunneling microscopy at 4.2 K. Small domains with \(\sqrt{13} \times \sqrt{13}\) modulation were found adjacent to the flat surface with a 3 ×3 intrinsic charge density wave (CDW). The surface atom ar…
The optical and magnetic properties of the spin-Peierls system, segregated-stack charge-transfer complexes, 1,6-pyrenediamine (DAP)-tetracyanoquinodimethane (TCNQ) and DAP-2,5-dimethyl-TCNQ (DMTCNQ), are investigated to gain insight into the nonlinear excitations in the spin-Peierls system. The band filling of the sys…
The specific heat C of Si:(P,B) with carrier concentration N between 0.8 and 17.8\ifmmode\times\else\texttimes\fi{}${10}^{18}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ and compensation ratio varying from 0.25 to 1 was measured in the temperature range between 0.06 and 3 K and in magnetic fields up to 6 T. Above the…
Equations of motion which describe the nonlinear optical response of conjugated polyenes using a collective electronic-oscillator representation are derived. Specific signatures of electronic correlations which enter as anharmonicities and scattering between oscillators are predicted in ultrafast resonant four-wave mi…
The effective dielectric function, effective absorption coefficient and effective refractive index for a model of porous silicon (PS) are calculated using the volume and surface averaging method. The model consists of periodic Si wires with different surface coverages. This approach allows to obtain analytical results…
Wurtzite-type semiconductors such as GaN and ZnO exhibit intrinsic electric-field gradients at the nuclear sites due to the hexagonal lattice symmetry. We have determined these field gradients ${\mathrm{V}}_{\mathrm{ZZ}}$ for all the nuclear sites by a magnetic double-resonance scheme. Shallow donors, which are presen…
We propose and experimentally demonstrate the use of metal-covered lamellar relief gratings as a polarizing beam splitter operating at a single wavelength near Littrow incidence. We report the characteristics of a grating produced by holography and reactive ion etching that was calculated for operation as beam splitte…
We present low-energy electron-diffraction (LEED) and photoemission measurements of single-crystal surfaces of ${\mathrm{VO}}_{2}$ , made possible using samples oriented and characterized in situ. LEED shows that the (100) surface has a (1\ifmmode\times\else\texttimes\fi{}2) reconstruction, but the (110) and (101) sur…
Nanometer-scale crystal silicon films surrounded by ${\mathrm{SiO}}_{2}$ were prepared by oxidizing silicon-on-insulator substrates prepared from SIMOX (separation by implantation of oxygen) and crystallized hydrogenated amorphous silicon films. Average silicon layer thickness was determined from reflection spectra. W…