Materials Literature
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The sodium-cobalt oxide NaxCoO2+d is a promising candidate for thermoelectric applications since it may possess simultaneously large thermoelectric power and low resistivity. It is difficult to understand the simultaneous appearance of the two properties within the framework of conventional one-electron models. It has…
Experimental observations of the change in the polarization charge of pyroelectric crystals of LiNbO3, LiTaO3 and CsNO3, as the temperature of the crystal is changed from about 300K to a lower limit of 4.2K, are described. It was found that the rate of change of the polarization charge slowed down considerably and, pe…
New lanthanide-transition-metal (Ln-M) compounds were prepared and the structural relationships of the metal combinations were discerned. Numerous compounds derived from divalent or trivalent lanthanides and from transition metals in groups 7-11 were isolated. Three different types of interactions were observed: (1).…
In many compounds the broadband emission of Eu 2+ and Yb 2+ is subject to a very large (0.6–1.2 eV) Stokes shift and it behaves peculiarly with temperature change. Conduction band states of the host compound are involved in this ‘anomalous’ emission. Cases of anomalous emission are identified and the conditions for it…
Millimeter-long and well-aligned single-walled carbon nanotubes (SWNTs) have been produced on silica/silicon surfaces using the carbon monoxide chemical vapor deposition (CO-CVD) method. The orientation of the nanotube arrays can be well-controlled by the gas flow during the growth. The majority of the orientated SWNT…
We report a method to make crystalline silver nanowires in water, in the absence of a surfactant or polymer to direct nanoparticle growth, and without externally added seed crystallites. The reaction is one in which silver salt is reduced to silver metal, at 100 °C, by sodium citrate, in the presence of NaOH. Hydroxid…
Noble metal particles have long fascinated scientists because of their intense color, which led to their application in stained glass windows as early as the Middle Ages. The recent resurrection of colloidal and cluster chemistry has brought about the strive for new materials that allow a bottoms-up approach of buildi…
Abstract The decomposition of wood and leaf of eight species in air atmosphere is examined by nonisothermal means with linear temperature programming, and a simple kinetic description is developed based on the experimental results and integral analysis method. The relation between the apparent activation energy E and…
Abstract Waterborne polyurethanes were prepared by polyaddition reaction using isophorone diisocyanate, dimethylol propionic acid, various polyols with a fixed molecular weight ( M n = about 2000), ethylene diamine as a chain extender, and triethylamine as a neutralization agent. Three types of polyols such as (1) sol…
Abstract The graft copolymerization of styrene and methyl methacrylate onto natural rubber latex was studied under various reaction conditions using a cumene hydroperoxide redox initiator. The monomer conversion, graft copolymer compositions, and grafting efficiency were determined. The synthesized graft copolymers we…
Abstract N ‐Trimellitylimido‐ L ‐isoleucine (3) was prepared from the reaction of trimellitic anhydride with L ‐isoleucine [ L ‐2‐amino‐3‐methylvalerianic acid or (2 S ,3 S )‐2‐amino‐3‐methyl‐ n ‐valerinic acid] in an N,N ‐dimethylformamide solution at the refluxing temperature. The direct polycondensation reaction of…
Abstract Three polyester films with different repeating units—poly(lactic acid) (PLA), poly(ethylene terephthalate) (PET), and poly(oxybenzoate‐ co ‐oxynaphthoate) (PBN)—were modified by plasma, and the way in which the chemical compositions of the polymer chains influenced the plasma modification was investigated wit…
Abstract Nylon‐66 nanocomposites were prepared by melt‐compounding nylon‐66 with an alkyl ammonium surfactant pretreated montmorillonite (MMT). The thermal stability of the organic MMT powders was measured by thermogravimetric analysis. The decomposition of the surfactant on the MMT occurred from 200 to 500 °C. The lo…
The structural, electronic, and adhesive properties of Cu/SiO$_2$ interfaces are investigated using first-principles density-functional theory within the local density approximation. Interfaces between fcc Cu and $α$-cristobalite(001) surfaces with different surface stoichiometries are considered. Interfacial properti…
Intramolecular spin alignment in pi-conjugated molecules is studied theoretically in a model of a Peierls-Hubbard chain coupled with two localized spins. By means of the exact diagonalization technique, we demonstrate that a spin singlet (S=0) to quartet (S=3/2) transition can be induced by electronic doping, dependin…
We investigate through molecular dynamics the transition from Knudsen to molecular diffusion transport towards 2d absorbing interfaces with irregular geometry. Our results indicate that the length of the active zone decreases continuously with density from the Knudsen to the molecular diffusion regime. In the limit wh…
The structure of the electron quantum size levels in spherical nanocrystals is studied in the framework of an eight-band effective-mass model at zero and weak magnetic fields. The effect of the nanocrystal surface is modeled through the boundary condition imposed on the envelope wave function at the surface. We show t…
Abstract Various polyblends of poly(vinyl chloride) and polyurethane (PU) dissolved in a mixture of tetrahydrofuran and N , N ‐dimethylformamide were produced by electrospinning, in different ratios, with several electrospinning conditions, and the relationship between morphology and mechanical behavior of the resulti…
Abstract The effect of the incorporation of a bentonite on the vulcanization kinetics of natural rubber was investigated by means of both cure‐meter testing and differential scanning calorimetry (DSC) under dynamic and isothermal conditions. The vulcanization curves showed that the modified clay behaved as an effectiv…
Using results from colloid science we derive interaction potentials for computer simulations of mixtures of soft or hard ellipsoids of arbitrary shape and size. Our results are in many respects reminicent of potentials of the Gay-Berne type but have a well-defined microscopic interpretation and no adjustable parameter…