Materials Literature
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The perfect quenching of spin tunneling that has previously been discussed in terms of interfering instantons, and has recently been observed in the magnetic molecule ${\mathrm{Fe}}_{8},$ is treated using a discrete phase integral (or Wentzel-Kramers-Brillouin) method. The simplest model Hamiltonian for the phenomenon…
The perfect quenching of spin tunneling first predicted for a model with biaxial symmetry, and recently observed in the magnetic molecule ${\mathrm{Fe}}_{8},$ is further studied using the discrete phase integral or WKB (Wentzel-Kramers-Brillouin) method. The analysis of the previous paper is extended to the case where…
Temperature dependence of electrical conductivity \ensuremath{\sigma} is investigated for a set of icosahedral $(i\ensuremath{-}){\mathrm{Al}}_{70.5}{\mathrm{Pd}}_{21}{\mathrm{Re}}_{8.5}$ samples. We focus on ribbon samples with resistance ratios $R=\ensuremath{\rho}(4 \mathrm{K})/\ensuremath{\rho}(300 \mathrm{K})$ be…
The phase structure and biodegradability were investigated for amorphous blends of chemosynthetic fully amorphous atactic poly(R,S-3-hydroxybutyrate) (a-PHB) with atactic poly(methyl methacrylate) (PMMA) and atactic poly(R,S-lactide) (a-PLA). The differential scanning calorimetry thermal analysis indicated that a-PHB/…
Helices IV and V in the lactose permease of Escherichia coli contain the major determinants for substrate binding [Glu126 (helix IV), Arg144 (helix V), and Cys148 (helix V)]. Structural and dynamic features of this region were studied by using site-directed sulfhydryl modification of 48 single-Cys replacement mutants…
The effects of copper deposition on the $\mathrm{ZnO}(0001\ifmmode\bar\else\textasciimacron\fi{})$ O-terminated surface at 300 K have been studied by surface x-ray diffraction (SXRD). Terraces about 550 \AA{} wide, presenting a $(1\ifmmode\times\else\texttimes\fi{}1)$ bulk-derived order, were obtained on the clean sur…
We study the potential energy surface (PES) sampled by a liquid modeled via the widely studied extended simple point charge (SPC/E) model for water. We characterize the curvature of the PES by calculating the instantaneous normal mode (INM) spectrum for a wide range of densities and temperatures. We discuss the inform…
Abstract Maleic anhydride (MAH) was photografted onto low‐density polyethylene (LDPE) films with a grafting efficiency of about 70% in the absence of a photoinitiator. The self‐initiating performance was attributed to a mechanism of abstracting hydrogen atoms from LDPE chains by excited MAH dimers. The supporting expe…
1,4,8,11,15,18,22,25-octabutoxyphthalocyanines ((OBu)8Pcs) having eight 2-thienyl (1) and [2,2'-bithiophene]-5-yl (2) groups at beta positions and their zinc(II) and cobalt(II) derivatives were prepared from 2-thienyl- (3) or [2,2'-bithiophene]-5-yl (4)-substituted phthalonitriles in moderate to good yields. The elect…
Cavities or packing defects in proteins may generally be related with the dynamics and function of a protein. In the c-Myb R2 subdomain, its single cavity has been shown to be crucial for its DNA recognition. Cavities are also considered important in determining the pressure stability of a protein. In the present work…
In order to facilitate the large-scale preparation of active class II polyhydroxyalkanoate (PHA) synthase, we constructed a vector pT7-7 derivative that contains a modified phaC1 gene encoding a PHA synthase from Pseudomonas aeruginosa possessing six N-terminally fused histidine residues. Overexpression of this phaC1…
The orbital free ab initio molecular dynamics method is applied to study the static and dynamic structure of liquid Al near the triple point. The method uses a new kinetic energy functional, along with a local pseudopotential constructed within the same kinetic energy functional. The results obtained for the dynamic s…
Resonant behavior of the Raman process is predicted when the laser frequency is close to the orbital excitation energy of ${\mathrm{LaMnO}}_{3}$ at 2 eV. The incident photon creates a vibrationally excited self-trapped ``orbiton'' state from the orbitally ordered Jahn-Teller (JT) ground state. Trapping occurs by local…
Using first-principles total energy calculations, we found that the doping of Li into (6,0) nanotubes has no insertion barrier if the tube mouth is passivated. The diffusion barrier is extremely small inside the nanotube, and Li atoms prefer to reside along the tube axis. The reaction is strongly exothermic. The Li-Li…
We explored the effect of the ratio of bond length to excluded volume bead diameter, l0/d0, of simple bead–spring homopolymer chains on the resulting liquid structure of dense, monodisperse polymer melts. We conducted NVT molecular dynamics simulations of both bulk and planar confined polymer liquids. We find that bot…
The geometries, formation energies, and diffusion barriers of carbon point defects in silica (\ensuremath{\alpha}-quartz) have been calculated using a charge-self-consistent density-functional based nonorthogonal tight-binding method. It is found that bonded interstitial carbon configurations have significantly lower…
${\mathrm{NdNiO}}_{3}$ is studied by electron diffraction and by Raman scattering, and drastic changes are observed at the metal-insulator transition. These features are explained in the framework of a charge disproportionation of nickel, which is at variance from earlier results, but consistent with recent studies on…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPreparing Carbon Nanotubes and Nested Fullerenes from Supercritical CO2 by a Chemical ReactionMenachem Motiei, Yaron Rosenfeld Hacohen, Jose Calderon-Moreno, and Aharon GedankenView Author Information Department of Chemistry, Bar-Ilan University Ramat-Gan, Israel 52900…
Direct evidence for a size effect in self-trapped exciton (STE) photoluminescence (PL) from silica-based nanoscale materials as compared with bulk type-III fused silica is obtained. Two kinds of mesostructures were tested: (1) silica nanoparticle composites with primary particle size of 7 and 15 nm, (2) ordered and di…
The wetting behavior of homopolymer on a chemically identical polymer brush is mathematically equivalent to the interaction between a pair of opposing brushes in a matrix of parent homopolymer. We examine both systems using self-consistent field theory (SCFT) with a new highly efficient and accurate algorithm. Our cal…