Materials Literature
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Recent high pressure x-ray experiments show that, contrary to traditional expectations, the NaCl structure is not present in covalent semiconductors, and the diatomic $\ensuremath{\beta}\ensuremath{-}\mathrm{Sn}$ structure is absent in all compound semiconductors. We explain these systematic absences in terms of dynam…
An optically addressed ultraviolet light modulator has been demonstrated which exploits the optical anisotropy in a ZnO film epitaxially grown on (011̄2) sapphire. This device achieves both high contrast and high speed by exploiting the anisotropic bleaching of the anisotropic absorption and concomitant ultrafast pola…
Nearly a 50% decrease of resistivity ρ(T,x) due to just 4% Cu doping on the Mn site of La(2/3)Ca(1/3)Mn(1-x)Cu(x)O(3) is observed. Attributing the observed phenomenon to the substitution induced decrease of the spin polaron energy E_s(x) below the Curie point T_C(x)=T_C(0)(1-x), all data are found to be well fitted by…
We propose a first principles computation of the equilibrium thermodynamics of simple fragile glasses starting from the two body interatomic potential. A replica formulation translates this problem into that of a gas of interacting molecules, each molecule being built of $m$ atoms, and having a gyration radius (relate…
The thermal conductivity of polycrystalline semiconductors with type-I clathrate hydrate crystal structure is reported. Ge clathrates (doped with Sr and/or Eu) exhibit lattice thermal conductivities typical of amorphous materials. Remarkably, this behavior occurs in spite of the well-defined crystalline structure and…
Short jute fiber-reinforced polypropylene (PP) composites were prepared using a high-speed thermokinetic mixer. A compatibilizer was used to improve the molecular interaction between jute and PP. Both the percent weight fraction of the jute fiber and compatibilizer were varied to study the dynamic mechanical thermal (…
The mechanical properties of tossa jute fibers were improved by using NaOH treatment process to improve the mechanical properties of composites materials. Shrinkage of fibers during this process has significant effects to the fiber structure, as well as to the mechanical fiber properties, such as tensile strength and…
Polymerization of 4,4′-bismaleimidediphenyl methane and N-phenylmaleimide was conducted in dimethyl formamide, catalyzed by nanocrystalline titania. The monomers and polymers involved were characterized with infrared spectroscopy, 1H-NMR, and 13C-NMR, respectively. The mechanism of the catalyzed polymerization was dis…
Neodymium chloride tripentanolate catalysts of the general formula NdCl3 × nL with n = 3, L = 1-pentanol (II), 2-pentanol (III), and 3-pentanol (IV) were prepared by an alcohol interchange reaction between neodymium chloride n isopropanolate (I) with pentanols. These NdCl3 tripentanolates (II–IV) were characterized by…
Cellulose dinitrate (CDN), cellulose diacetate (CDA), and cellulose triacetate (CTA) were subjected to high-resolution thermogravimetry (TG) at a variable heating rate in air. The TG curves, the derivative TG curves, the second derivative TG curves, and heating rate curves are discussed. The thermal degradation temper…
In an attempt to produce surfaces that show low levels of adsorption of protein and adhesion of platelets, different molecular weights of polyethylene glycol methacrylate (PEG-MA) were grafted onto polyethylene film by a preirradiation grafting process. The extent of grafting was found to be dependent on the storage c…
To suppress steel corrosion at elevated temperature and in humid condition, silane coupling agents N-β-aminoethyl aminopropyltrimethoxysilane (AAPS), γ-glycidoxypropyltrimethoxysilane (GPS), and bis[3-(trimethoxysilyl)-1-phenylpropyl]tetrasulfide (RC-2) were introduced as primers into an epoxy/steel system. Silane cou…
Stability, including thermal stability, conductivity stability in air and after thermal treatment (100–200°C), of the polyaniline (PANI) films synthesized by a doping–dedoping–redoping method was investigated. It was found that thermogravimetric analysis (TGA) curves undergo three steps: loss of water or solvent, dedo…
Crystal growth rate data based on the kinetic nucleation theory of chain folding and the effect of reptation, have been used to predict the rate of crystal growth at moderate to high supercoolings in iPP molecular weight fractions. Growth rate data obtained for the fractions seem to be in agreement with the theoretica…
Short jute fiber-reinforced polypropylene (PP) composites were prepared using a high-speed thermokinetic mixer. A compatibilizer was used to improve the molecular interaction between jute and PP. Both the percent weight fraction of the jute fiber and compatibilizer were varied to study the dynamic mechanical thermal (…
Second neighbor dominated exchange coupling in CaV4O9 has been obtained from ab initio density functional (DF) calculations. A DF-based self-consistent atomic deformation model reveals that the nearest neighbor coupling is small due to strong cancellation among the various superexchange processes. Exact diagonalizatio…
The mechanical properties of tossa jute fibers were improved by using NaOH treatment process to improve the mechanical properties of composites materials. Shrinkage of fibers during this process has significant effects to the fiber structure, as well as to the mechanical fiber properties, such as tensile strength and…
The conductivity of the Na 2 S 2 O 7 −NaHSO 4 binary system has been measured for 15 different compositions in the full composition range, and in the temperature range 400−700 K. Phase transition temperatures were obtained, and the phase diagram was constructed. It is of the simple eutectic type, where the eutectic is…
Sideroxylonal C (3), a new phloroglucinol dimer, was isolated from the flowers of Eucalyptus albens through bioassay-guided fractionation. The structure elucidation was based on 1D and 2D NMR experiments, MS analysis, and comparison with sideroxylonals A (1) and B (2). Sideroxylonal C inhibited human plasminogen activ…
Colloidal gold nanocrystal superlattices (NCSs) were formed by ligand modification of the nanocrystal surface. The effect of different ligands was compared and it was found that dodecanethiol was most effective in forming NCSs. TEM showed that the superlattice formation from a slightly polydisperse system was a self-s…