Materials Literature
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We report the synthesis of three sizes of thioglycerol-capped precipitated ZnS nanocrystallites with relatively narrow size distributions, having average sizes of 1.8, 2.5, and 3.5 nm, respectively. These crystallites were extracted as free-standing powders which remain stable under normal atmospheric conditions and c…
We apply an anisotropic version of the polymer reference interaction site model (PRISM) integral equation description of flexible polymers to analyze athermal liquid crystallinity. The polymers are characterized by a statistical segment length, σo, and by a physical hard-core thickness, d, that prevents the overlap of…
A systematic study of nonlinear optical (NLO) properties of inorganic transition metal (TM) thiometalates and metalates is reported. Polarizabilities (α) and second hyperpolarizabilities (γ) are calculated in solution within the polarizable continuum model. It is found that NLO properties of anionic inorganic complexe…
Thermal desorption spectroscopy, ultraviolet photoelectron spectroscopy, low energy electron diffraction (LEED), and the reactive scattering of a CO molecular beam have been applied to determine the relationship between the formation of the subsurface oxygen phase and the growth of oxides during oxidation of Ru(0001).…
The effect of substrate receptor group density on polymer adhesion was investigated. Model substrates with varying −NH 2 density on Al 2 O 3 were prepared by a self-assembly of mixed amine-terminated silanes and methyl-terminated silanes. The model polymer was synthesized through a high-pressure carboxylation of polyb…
The tricontinuous structure of ABC-type triblock copolymer in bulk at equilibrium was studied by both transmission electron microscopy (TEM) and small-angle x-ray scattering (SAXS). Sample is an anionically polymerized isoprene-styrene-2-vinylpyridine triblock copolymer whose volume fraction is 0.22–0.59–0.19 and tota…
Oxygen doping in metallic YBa_2Cu_3O_x induces quadrupolar "alpha-ortho'', and breathing "beta-ortho" deformations of the CuO_2 planes. Breathing beta-ortho deformations favour hybridizations of the pd sigma Cu3d_x^2-y^2 - O2p_x,y with the pd pi Cu3d_x,z, 3d_y,z-O2p_z bands relaxing the confinement of the carriers in…
A new procedure for the modification of gold nanospheres (2−7 nm diameter) with thiolated cyclodextrin receptors is described. The resulting monolayer-protected nanoparticles behave as multisite hosts in aqueous media, engaging in host−guest interactions with guest molecules in the solution.
Enzyme I mutants of the Salmonella typhimurium phosphoenolpyruvate:sugar phosphotransferase system (PTS), which show in vitro intragenic complementation, have been identified as Arg126Cys (strain SB1690 ptsI34), Gly356Ser (strain SB1681 ptsI16), and Arg375Cys (strain SB1476 ptsI17). The mutation Arg126Cys is in the N-…
In this publication the glass transition, melting behavior, cure behavior, and thermal stability of LaRC PETI-5 have been extensively studied utilizing differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The material used here was subjected to different thermal history (cumulative cure and in…
Some major factors of the melt spinning of high-density polyethylene (HDPE) and a liquid paraffin (LP) blend, which affect the water permeability of HDPE hollow-fiber membrane obtained therefrom, were investigated. The water permeability of the membrane was found to increase as the membrane thickness decreases and as…
Site-directed mutagenesis is a powerful tool for identifying active-site residues essential for catalysis; however, this approach has only recently become available for acetate kinase. The enzyme from Methanosarcina thermophila has been cloned and hyper-produced in a highly active form in Escherichia coli (recombinant…
Ketopantoate reductase (EC 1.1.1.169) catalyzes the NADPH-dependent reduction of alpha-ketopantoate to form D-(-)-pantoate in the pantothenate/coenzyme A biosynthetic pathway. The enzyme encoded by the panE gene from E. coli K12 was overexpressed and purified to homogeneity. The native enzyme exists in solution as a m…
Two new three-dimensional open-framework cobalt phosphates, [C2N2H10]2[Co4(PO4)4]H2O, I, and [C4N3H16]3-[Co6(PO4)5(HPO4)3]H2O, II, have been prepared by the reaction of amine phosphates with Co2+ salts. I could also be prepared by the reaction of the cobalt tris amine complex with H3PO4. The crystal data for I and II…
Magnetic circular dichroism (MCD) and absorption spectra are reported for the Q, RV, and IV band regions (6000−19000 cm -1 ) of lutetium bisphthalocyanine in poly(methyl methacrylate) films and Ar matrixes. Weak, temperature-independent MCD of the IV band (∼7500 cm -1 ) is consistent with its assignment to the interva…
A new type of grafted chitosan-crown ether was synthesized using mesocyclic diamine crown ether as the grafting agent. The C2 amino group in chitosan was protected from the reaction between benzaldehyde and chitosan to form N-benzylidene chitosan (CTB). After reaction with mesocyclic diamine crown ether of the epoxy p…
Sediment samples were collected from 77 lakes in the Mackenzie Delta representing a gradient of lakes from those having continual connection with the sediment-laden Mackenzie River to lakes having connection for only a couple of days every few years. Diatom assemblages in all lakes were dominated by a diverse benthic…
Polychlorinated biphenyls (PCBs) are pollutants of environmental concern due to their widespread presence and persistence. The sonolytic destruction of aqueous polychlorinated biphenyls (PCBs) is reported in this article. The kinetics and transformation pathways were investigated at multiple frequencies and with vario…
Blends of poly(vinyl chloride) (PVC) with different copolymers have been studied to obtain a plasticized PVC with improved properties and the absence of plasticizer migration. The copolymers used as plasticizers in the blends were acrylonitrile butadiene rubber, ethylene vinyl acetate (EVA), and ethylene-acrylic copol…
For emulsions containing equal volumes of toluene and water stabilized by nanometer-size silica particles alone, we demonstrate that transitional inversion, from oil-in-water (o/w) to water-in-oil (w/o) and vice versa, can be achieved using mixtures of two particle types of different wettability. Using conductivity, s…