Materials Literature
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Boron carbides fabricated via plasma enhanced chemical vapour deposition from different isomeric source compounds with the same C 2 B 10 H 12 closo-icosahedral structure result in materials with very different direct (optical) band gaps. This provides compelling evidence for the existence of multiple polytypes of C 2…
Quasi-one-dimensional steady-state cavitating nozzle flows with homogeneous bubble nucleation and nonlinear bubble dynamics are considered using a continuum bubbly liquid flow model. The onset of cavitation is modeled using an improved version of the classical theory of homogeneous nucleation, and the nonlinear dynami…
The rotational molecular dynamics of water confined to nanoporous molecular sieves of a regular hexagonal (SBA-15) and of a foamlike pore structure was studied by dielectric spectroscopy in the frequency range from 10(-2) to 10(9) Hz and in a broad temperature interval. Two relaxation processes were observed: the proc…
The toughening mechanism of nanocomposite films comprising ultrahigh molecular weight polyethylene (UHMWPE) and modified carbon nanofiber (MCNF) was investigated by in-situ synchrotron small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) techniques during uniaxial stretching. Surface modificatio…
Electrochemical oxidative carbonylation of methanol was studied over Au supported carbon anode in CO. The major carbonylation products were dimethyl oxalate (DMO) and dimethyl carbonate (DMC). The minor oxidation products were dimethoxy methane (DMM) and methyl formate (MF) from methanol and CO(2). Influences of vario…
▪ Abstract Catalyst life (with activity and selectivity) is one of the three essential properties of a practical catalyst, both in laboratory and industrial usage. For most catalysts in which the active phase is a metal, high activity requires a high metal surface area. In all cases, for long life, the metal surface a…
Sedimentation–diffusion (SD) equilibria from analytical ultracentrifugation of well-characterized charged silica spheres in ethanol deviate strongly from a barometric profile and demonstrate the existence and substantial effects of a recently predicted internal macroscopic electric field (van Roij 2003 J. Phys.: Conde…
Crystalline sodium tantalate thin films with pyrochlore (Na 2 Ta 2 O 6 ) and perovskite (NaTaO 3 ) structures are successfully synthesized on Ta metal substrates by a hydrothermal−electrochemical method at low temperature (≤473 K). The phase, film thickness, and domain size of the synthesized films are shown to be con…
The size of the cooperatively rearranging region (CRR) at T g has been measured for syndiotactic poly(methyl methacrylate) confined between the layers of an organophilic montmorillonite (OMMT) according to the method developed by Donth. The results show that the size of the CRR is constrained by the layers and that it…
We report the preparation of direct hexagonal liquid crystals, constituted of oil-swollen cylinders arranged on a triangular lattice in water. The volume ratio of oil over water, rho can be as large as 3.8. From the lattice parameter measured by small-angle X-ray scattering, we show that all the oil is indeed incorpor…
Photoinduced changes in the mechanical and dielectric properties of azobenzene polymer films were measured utilizing the method of electromechanical spectroscopy. The measurements revealed a strong correlation between the time-dependent behavior of the plate compliance and the dielectric constant under irradiation. Ac…
An investigation of ion beam emission from a low energy plasma focus (PF) device operating with methane is reported. Graphite collectors, operating in the bias ion collector mode, are used to estimate the energy spectrum and ion flux along the PF axis, using the time-of-flight technique. The ion beam signals are time…
Titanium−silica hollow spheres with a mesoporous shell have been synthesized using an inverse multiple oil−water−oil (O/W/O) emulsion. The oil phase consists of kerosene and sorbitan monooleate (Span 80, C 24 H 44 O 6 ); the aqueous phase is a viscous sol solution, prepared from ethanol, Ti−Si species, and HNO 3 solut…
Bacterial surfaces contain proteins, polysaccharides, and other biopolymers that can affect their adhesion to another surface. To better understand the role of proteins in bacterial adhesion, the interactions between two different model colloids (glass beads and carboxylated latex microspheres) and four proteins coval…
Colloidal suspension can be regarded as an ideal model system of emulsions, protein solutions, foods, and inks. When there are strong attractive interactions between colloidal particles, they aggregate, phase separate, and sometimes form gel. The basic understanding of the resulting formation of superstructures is of…
The frequency and temperature dependences of the hysteresis loops in Pb[(Zr 0.52 Ti 0.48 ) 0.95 (Mn 1/3 Nb 2/3 ) 0.05 ]O 3 ceramics have been investigated. The polarization-field hysteresis curves show 'pinched' shapes at room temperature and higher frequencies, whereas they display normal square-like loops at 200°C a…
Homopolymers of azobenzene methacrylates (azo) and their diblock copolymers with 2-(dimethylamino)ethyl metharylate (DMAEMA) were synthesized via atom transfer radical polymerization (ATRP). Polymers of cyano- and butoxy-substituted azobenzenes exhibited liquid crystalline textures. Water-soluble diblock copolymers co…
The maximum entropy and reverse Monte Carlo methods are applied to the computation of the phonon density of states (DOS) from heat capacity data. The approach is introduced and the formalism is described. Simulated data are used to test the method, and its sensitivity to noise. Heat capacity measurements from diamond…
Single particle resonances in quantum wires are generally Fano resonances. In case of Fano resonances, the scattering phase shift in some channels show sharp phase drops and that in the other channels do not. Phase shift in a particular channel can be measured and can yield information about the integrated charge loca…
It was recently demonstrated that the Stillinger-Weber silicon undergoes a liquid-liquid first-order phase transition deep into the supercooled region (Sastry and Angell, Nature Materials 2, 739 (2003)). Here we study the effects of perturbations on this phase transition. We show that the order of the liquid-liquid tr…