Materials Literature
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We report broadening of Raman spectrum and decreasing intensity over a range from 400 to 900 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ for sintered polycrystalline ${\mathrm{La}}_{0.75}{\mathrm{Ca}}_{0.25}{\mathrm{MnO}}_{3}$ in the presence of an external magnetic field. The observation of ``structural changes'' when…
This is one of a series of ten papers reporting aspects of the chemistry of cyclic peptides of marine origin. All reported significant results regarding the binding of metal ions. Here the structural complexity of the peptides by forming cylindrical and conical structures, new classes of molecular receptors, was devel…
The insulator-metal transition in single crystal ${\mathrm{La}}_{5/8\ensuremath{-}y}{\mathrm{Pr}}_{y}{\mathrm{Ca}}_{3/8}{\mathrm{MnO}}_{3}$ with $y\ensuremath{\approx}0.35$ was studied using synchrotron x-ray diffraction, electric resistivity, magnetic susceptibility, and specific heat measurements. Despite the dramat…
We report and analyse x-ray absorption spectroscopy of the Cd K edge of CdS-doped glass during growth and dissolution of CdS nanoparticles. Average particle size is deduced from a combination of x-ray and optical spectroscopies. We propose a simple thermodynamic model in which the limiting reactant is in only two envi…
Electron nuclear double resonance (ENDOR) spectroscopy and electronic structure calculations were combined in order to study the local environment of ${\mathrm{CO}}_{2}^{\mathrm{\ensuremath{-}}}$ radicals in A-type carbonated apatite. At temperatures lower than 20 K, the ENDOR spectra are composed of hyperfine lines c…
The compound GdPd 2 Si, which is reported to order antiferromagnetically at 13 K, has been investigated by heat capacity and electrical resistivity measurement in the presence of external magnetic fields. In contrast to an earlier report, the zero-field heat capacity and resistivity data indicate two magnetic transiti…
We present the monovalent alkali metal substitution effects upon structural, magnetic and electrical properties in La 0.7 Sr 0.3- x Na x MnO 3 for 0⩽ x ⩽0.2. X-ray diffraction patterns show that our powder samples crystallize in a rhombohedral distorted perovskite structure with R c space group. All the samples exhibi…
Nanoscale silver particles embedded in sodium silicate glass were produced by Na/Ag ion exchange and subsequent thermal treatment in a hydrogen atmosphere. Their structure and spatial distribution were studied by conventional and high-resolution electron microscopy (HREM). Two different mechanisms of particle formatio…
Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans the biological, physical, and social sciences.
Upon nitrogen adsorption at low temperature onto the surface of magnesium oxide and calcium oxide containing F S + centers (single electron trapped in a suitable surface vacancy), electron transfer occurs from the solid to the adsorbed molecule. About 90% of the total electron density is localized on the adsorbed mole…
Nonenzymatic pyridoxal phosphate (PLP) catalyzed decarboxylations and transaminations have been revisited experimentally. Metal ions are known to catalyze a variety of PLP-dependent reactions in solution, including transamination. It is demonstrated here that the rate accelerations previously observed are due solely t…
The atomic structure of cristobalite in both its high-temperature β-phase and low-temperature α-phase has been studied using constrained reverse Monte Carlo modelling of neutron total scattering data. The modelling has shown that the disorder of the β-phase involves rotations and displacements of rigid SiO 4 tetrahedr…
Several experimental and theoretical studies have related the peculiar mechanical properties of the macro-defect-free polymer−cement composites with the existence of a cross-link ing of the polymer chains by Al or Ca ions coming from the hydration reactions of the cement. In the present study, the interaction of Ca io…
An amphiphilic polyphosphazene diblock copolymer (MEEP−Ph/MEEP) based on [N P(OCH 2 CH 2 OCH 2 CH 2 OCH 3 ) 2 ] n (MEEP) as a hydrophilic block and [N PPh(OCH 2 CH 2 OCH 2 CH 2 OCH 3 )] m (Ph/MEEP) as a hydrophobic block was synthesized via the controlled cationic block copolymerization of phosphoranimine. The molecul…
This paper examines lateral capillary interactions between millimeter- and sub-millimeter-sized objects floating at the interface between perfluorodecalin (PFD) and water. It describes methods both experimental and computational that allow the shape of the interface to be described for various geometries of the intera…
This article reviews the complex ordered structures induced by chirality in liquid crystals. In general, chirality favours a twist in the orientation of liquid-crystal molecules. In some cases, as in the cholesteric phase, this favoured twist can be achieved without any defects. More often, the favoured twist competes…
The magnetotransport and magnetostructural properties of ${\mathrm{La}}_{0.7}({\mathrm{Ca}}_{1\ensuremath{-}y}{\mathrm{Sr}}_{y}{)}_{0.3}{\mathrm{MnO}}_{3}$ $(0<~y<~1)$ are studied. We investigate the variation in magnetoresistance (MR) with y and the field-induced structural transition at $y\ensuremath{\sim}0.5$…
The digestion of bacterial cellulose ribbons by ternary mixtures of enzymes consisting of recombinant cellulases (two cellobiohydrolases, Cel6A and Cel7A, and the endoglucanase Cel45A) from Humicola insolens was investigated over a wide range of mixture composition. The extent of digestion was followed by soluble suga…
Porous, low dielectric constant polyimide films have been made by a “nanofoam” approach. The pore sizes generated in the polymer films are in the tens of nanometers range, hence the term “nanofoams”. The nanoporous foams are generated by preparing triblock copolymers with the majority phase comprising polyimide and th…
The dynamic growth processes of lamellae and spherulites of a polymer (BA-C8) synthesized by condensation polymerization of bisphenol A and 1,8-dibromooctane were directly observed using an atomic force microscope at 25 ± 1 °C. The phase shift measured at the tip of growing lamellae is lower than the phase shifts of t…