Materials Literature
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Water-soluble polycarbonate having pendent carboxyl groups on the main-chain carbons is reported for the first time. This paper describes synthesis and enzyme-catalyzed ring-opening polymerization of a novel carbonate monomer, 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one ( 1 ). Various commercially available lipases…
The Projected Dynamics method was originally developed to study metastable decay in ferromagnetic discrete spin models. Here, we apply it to a classical, continuous Heisenberg model with anisotropic ferromagnetic interactions, which evolves under a Monte Carlo dynamic. The anisotropy is sufficiently large to allow com…
The synthesis, characterization, and mesomorphic properties of a new type of liquid-crystalline compounds, (3Z,6Z)-3,6-bis(3,4-dialkoxybenzylidene)piperazine-2,5-diones are reported. These compounds were derived from unsaturated piperazine-2,5-dione as the core group, and were prepared by condensation reactions of 1,4…
We present experimental evidence to support a claim of Temperley and Trevena that, in the dynamic stressing of water by tension involving low–frequency ultrasound pulses, no serious discrepancy exists between theory and experiment. Experiments conducted on samples of deionized water suggest that this liquid can sustai…
Photoresponsive liquid crystalline polymer networks with macroscopically uniaxial molecular orientation were prepared by polymerizing mixtures of liquid crystalline mono- and diacrylates and an azobenzene compound in a homogeneous glass cell at a nematic phase. The polymer networks showed an enantiotropic phase transi…
Hyper-Rayleigh scattering (HRS) has been carried out for new azulenic donor–acceptor chromophores using near-infrared laser excitation at wavelengths of 1064 and 1907 nm. Hyperpolarizabilities obtained with the 1064 nm incident excitation are large compared with those obtained using the 1907 nm excitation, due to the…
The structure of a colloidal suspension under shear flow was studied by in situ small angle neutron scattering (SANS). This suspension exhibited shear thinning at low shear rates and shear thickening at high shear rates. Under quiescent conditions, the SANS profiles were azimuthally symmetric and contained a well-defi…
This paper extends the fibre–network theory of Cox to three–dimensional anisotropic fibrewebs. It presents a micromechanical model employing fibre axial deformation as the elemental deformation mechanism giving rise to assembly stress as a result of applied normal and shearing strain field. This model predicts the ela…
Simulations of crystal growth from the melt are performed, using the Lennard-Jones potential. Growth of the (100), (111), and (110) faces of the fcc crystal from its melt are simulated. The measured growth rates show that the kinetic coefficient of the (100) face is about twice as high as that of the (111) and (110) f…
The two known phases of germanium nitride (Ge3N4) have hexagonal and trigonal symmetries and consist of three-dimensional networks of corner-connected Ge–N tetrahedra. A new cubic spinel phase (space-group Fd3m, a0=8.3 Å, Z=8, ρ=6.36 g/cm3) containing Ge–N octahedra and tetrahedra in a 2:1 ratio was synthesized from e…
The electronic structure of the conjugated polymer, polyaniline, has been studied by resonant and nonresonant soft x-ray emission spectroscopy using synchrotron radiation for the excitation. The measurements were made on polyaniline and a few doped (protonated) phases for both the carbon and nitrogen contents. The res…
The theory of a novel bond-order potential, which is based on the block Lanczos algorithm, is presented within an orthogonal tight-binding representation. The block scheme handles automatically the very different character of sigma and pi bonds by introducing block elements, which produces rapid convergence of the ene…
A modified cathodic arc technique has been used to deposit carbon nitride thin films directly on n+ Si substrates. Transmission Electron Microscopy showed that clusters of fullerene-like nanoparticles are embedded in the deposited material. Field emission in vacuum from as-grown films starts at an electric field stren…
The loss of Cu/ZnO/Al 2 O 3 activity for methanol synthesis has been studied over 50 h under a range of synthesis gas compositions. Experiments have been carried out at differential and finite conversions in order to compare deactivation under the pure feed to that in the presence of products. Under differential conve…
The present study provides comprehensive information on the effects of process parameter variations on the corrosion behavior of carbon steel in CO 2 absorption systems using aqueous amine solutions. The process parameters of interest are amine type, concentration of the amine solutions, solution temperature, CO 2 loa…
A metal nanoshell is a composite nanoparticle consisting of a dielectric core coated by a thin metal shell; its peak plasmon resonance wavelength is determined by the ratio of the core diameter to the shell thickness. When p-mercaptoaniline (p-MA) is in solution with gold nanoshells that have their plasmon resonance n…
Thermochromic VO<SUB>2</SUB> thin films have been deposited by reactive RF cathodic sputtering, using a V<SUB>2</SUB>O<SUB>4</SUB> target. They were characterized by XRD, AFM and optical measurements. We show that the microstructure influences the optical response of the material, i.e. its hysteresis cycle as well as…
In PrBa_2Cu_3O_{7-y} (Pr123) single crystals grown by the flux method the kink in the magnetic susceptibility chi_{ab}(T), connected with AFM ordering of Pr, disappears after field cooling (FC) in a field H||ab-plane whereas the kink in chi_c(T) remains unchanged after FC in H||c-axis. This seems to be connected with…
We use the Quantum Hypernetted Chain Approximation (QHNC) to calculate the ion-ion and electron-ion correlations for liquid metallic Li, Be, Na, Mg, Al, K, Ca, and Ga. We discuss trends in electron-ion structure factors and radial distribution functions, and also calculate the free-atom and metallic-atom form-factors,…
Magnetic properties were studied for the high quality Al-free orthorhombic Gd_{1-x}Pr_xBa_2Cu_3O_{7-y} single crystals (0<=x<=1.0) grown by the flux method. An indication on the interaction between the Pr and Cu(2) magnetic sublattices was found for Pr123. Different signs of magnetic anisotropy were established for th…