Materials Literature
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The metC gene coding for cystathionine beta-lyase of Escherichia coli has been cloned and used to construct an overproducing E. coli strain. An efficient purification scheme has been developed and the purified enzyme has been crystallized by the hanging drop vapour diffusion method using either ammonium sulfate or pol…
We present a molecular theory of the phenomena of single-chain collapse and phase separation into a polymer-rich and a polymer-poor phase, which occur in polymer solutions below the Θ temperature. The theory extends the Fourier self-consistent approach of Allegra and Ganazzoli from the study of single-chain properties…
A photovoltaic cell with carbonaceous thin film/n-type silicon (C/n-Si) was fabricated. The carbonaceous thin film was deposited on an n-type single-crystal-silicon substrate by chemical-vapor deposition of 2,5-dimethyl-p-benzoquinone at 500 °C. Without light irradiation, the photovoltaic cell displayed an almost perf…
Plasma-deposited, hydrogenated carbon thin films were investigated by infrared analysis and high-energy ion analysis. The absolute quantities of hydrogen in the films, as measured by ion beam analysis, and the strength of the C–H vibrational bands around 3000 cm−1 were compared to determine the average absorption stre…
We describe a modification of conventional dynamic light scattering (DLS) using a CCD camera as optical area detector. Scattered intensity autocorrelation functions are determined using both ensemble- and time-averaging. Therefore, the new setup allows for much shorter measurement times compared to conventional DLS. O…
A physical picture of a conjugated chain as a collection of almost planar segments, separated by large angular breaks arises from a microscopic model which includes conjugation and steric interactions. The conjugation part of the standard phenomenological Hamiltonian for torsional motion is also derived from the model…
The lattice parameter and surface morphology of homoepitaxial SrTiO3 films were found to depend on the ambient oxygen pressure during growth. The homoepitaxial layers were grown by pulsed laser deposition with static ambient oxygen pressures of 100, 10, and 1 mTorr. The surface roughness of the films increased with in…
The binary liquid phase separation of aqueous solutions of γ-crystallins is utilized to gain insight into the microscopic interactions between these proteins. The interactions are modeled by a square-well potential with reduced range λ and depth ε. A comparison is made between the experimentally determined phase diagr…
Methanotrophs have promising applications in the bioremediation of chlorinated hydrocarbons and in the production of a biopolymer, poly-beta-hydroxybutyrate (PHB). Batch bioreactor culture conditions were studied for the accumulation of PHB by methane-grown Methylosinus trichosporium OB3b, and to evaluate the effect o…
Without a doubt, photochemically induced electron transfer in 1 proceeds stepwise. Triad 1 is one of the latest models of the photosynthetic reaction center. The rates of the individual steps in the electron transfer relay have been determined by ultra-fast laser spectroscopy.
Syntheses of a series of conjugated donor-acceptor chromophores, based on a strongly electron-withdrawing heterocyclic acceptor, have led to compounds with large second-order optical nonlinearities. Incorporation of one of these chromophores into polycarbonate at 20 percent weight loading yielded, after poling at 150…
The crosslinking reaction of poly(vinyl alcohol) (PVA) with 3,3′,4,4′-tetracarboxybenzophenone dianhydride, pyromellitic carboxylic acid anhydride, and Epiclon B-4400 as hardeners was studied either in solution or by differential scanning calorimetry. A catalyst agent had to be used in all cases. Depending on the conc…
Several microcrystalline celluloses prepared from viscose staple, bagasse, ramie, and cotton were evaluated by viscosimetry, X-ray diffraction and scanning and transmission electron microscopies. The changes in crystallinity, size of crystallites, grain-size distribution, morphological features, and degree of polymeri…
The conductivity mechanism for a carbon black (CB) filled high-density polyethylene (HDPE) compound was investigated in this work. From the experimental results obtained, it can be seen that the relation between electrical current density (J) and applied voltage across the sample (V) coincides with Simmons's equation…
A novel dry-spinning method for the preparation of zein fiber without using formaldehyde is presented. The fiber thus obtained had good stability to boiling aqueous acetic acid solution with breaking tenacity and elongation of 1.0 g/d and 30%, respectively. Citric acid and butanetetracarboxylic acid were used as nonfo…
Large TlInSe2 single crystals are grown by the Bridgman-Stockbarger method, starting from stoichiometric melts. Current–voltage (I–V) characterstics of symmetric In/p-TlInSe2/In structures exhibit two distinct regions: an ohmic region at low current densities and a non-linear region (S-shaped) having negative differen…
A model describing the excitation of UHF signals by current pulses in a waveguide is developed using dyadic Green's functions. This model relates to UHF signals used for the detection of partial discharge (PD) caused by defects in gas-insulated substations (GIS). Application of the theory is demonstrated by compa…
The structure of disodium bis[μ-oxo-tri-μ3-oxopentakis(μ-propionato-κO:κO′) tris(propionato-κO)-0.5-chromium-0.5-irontrimolybdenum](3 Mo-Mo), Na2[Cr0.5Fe0.5Mo3O4(C3H5O2)8]2, consists of a centrosymmetric cluster anion, [(EtCO2)8Mo3O4CrFeO4Mo3(O2CEt)8]2−, in which two Mo3O4 units are joined by the Fe and Cr atoms to co…
In order to understand the effects of density fluctuations in composite systems, we have studied the effects of compression rate on the final density and density variations in a system of hard spheres. Systems of 900 and 1800 mono-sized spheres are placed in a box with periodic boundary conditions in the x and y direc…
Packing polymorphism and conformational disorder of poly(hexamethylene terephthalate) were analyzed by x-ray diffraction technique. The measurements were performed in the temperature range from 20 to 135°C. At high temperature, several unassignable reflections were found to disappear, and all reflections were satisfac…