Materials Literature
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Electro-optic (EO) modulators encode electrical signals onto fiber optic transmissions. High drive voltages limit gain and noise levels. Typical polymeric and lithium niobate modulators operate with halfwave voltages of 5 volts. Sterically modified organic chromophores have been used to reduce the attenuation of elect…
Langmuir−Blodgett (LB) films composed of the mixture of an amphiphilic polymer containing azobenzene (Az) side chain (6Az10-PVA) and 4‘-pentyl-4-cyanobiphenyl (5CB) were prepared to mimic the two-dimensional contacting region of the LC/Az interface of the command surface which photochemically switches the LC alignment…
Specificity of substrate recognition in lactose permease is directed toward the galactosyl moiety of lactose. In this study, binding of 31 structural analogues of D-galactose was examined by site-directed N-[(14)C]ethylmaleimide-labeling of the substrate-protectable Cys148 in the binding site. Alkylation of Cys148 is…
Two series of polyamides and polyesters derived from 2,2‘-bipyridine-5,5‘-dicarboxylic acid have been synthesized. Different types of aliphatic and aromatic diamine and diol monomers with different structure were polymerized with the diacid or diacid chloride by using different polymerization methods. Most of these po…
Co2([N(CN)2]4bpym).H2O (1) and M([N(CN)2]2bpym).H2O [M = Mn (2a), Fe (2b), Co (2c); bpym = 2,2'-bipyrimidine] have been synthesized and characterized structurally and magnetically. All of the compounds crystallize in the orthorhombic space group Pnma. The unit cell parameters for 1 are a = 16.1684(5) A, b = 12.9860(3)…
A redox reaction between an alkaline selenium solution and an aqueous solution of a cupric complex [Cu(edta)]2- produces nanocrystalline Cu2-xSe with an average particle size of 16.6 nm at room temperature under atmospheric pressure.
Several possible mechanisms for the synthesis of small ring systems, (H(OH)SiO) n, ( n = 3 and 4), the three- ( D 3 ) and four- ( D 4 ) membered cyclosiloxanes, respectively, are investigated with ab initio molecular orbital methods including electron correlation effects. It is found that the substantial potential ene…
MCM-48 silicas have been prepared via a high-yield synthesis procedure using mixtures of cationic alkyltrimethylammonium surfactants (alkyl chain length from 12 to 20 carbon atoms) and neutral cosurfactants. This is the first reported successful synthesis of MCM-48 using eicosyltrimethylammonium surfactant. The sample…
To elucidate the dynamics and mechanisms of radiationless transitions from higher excited electronic states as well as the ultrafast intramolecular vibronic relaxation in porphyrin derivatives, we have studied the fluorescence dynamics of Zn-tetraphenylporphyrin (ZnTPP) and Zn-diphenylporphyrin derivatives (ZnDPP) in…
It has been discovered that kinetics of structural changes in Pd and Pd-alloys under the influence of dissolved hydrogen seems to be non-trivial. As a rule, structural changes in these systems include correlation changes of co-existing phases concentration and the defect structure character. These changes have the sta…
Wide band-gap semiconductor zinc oxide nanoclusters have been prepared in the channels of MCM-41 materials by functionalizing the MCM-41 with ethylenediamine groups, absorbing zinc cations, and calcinating at high temperatures. The products have been characterized by XRD, TEM, EDS, nitrogen adsorption and desorption,…
Emerging electrosynthetic techniques such as electrogeneration of base, anodic oxidation, and ac (alternating current) synthesis provide simple and inexpensive alternative routes to the synthesis of ceramic thin films and coatings, nanoparticulate materials, and metastable phases. In this review, we survey illustrativ…
Abstract Iron sulfide scale deposition occurs throughout the Kaybob South field in Central Alberta. The scale typically forms directly on the tubular walls and generally results in corrosion of the metal beneath the scale crystallites. Under normal conditions, iron sulfide is soluble in hydrochloric acid. However, in…
A very reliable and reproducible electrochemical preparative procedure to obtain oxygen-sensitive lithium phthalocyanine (LiPc) microcrystalline powder, a critical material for in vivo application of electron paramagnetic resonance (EPR) oximetry to measure the partial pressure of molecular oxygen p O 2, is described.…
Aging of power plants and competitive pressures to operate and maintain (O&M) these plants at reduced costs have heightened industry interest in life assessment and management technologies. Piping and tubing systems carrying high-pressure steam at temperatures exceeding 1000°F (530°C) have notably been the center…
The dispersity, size, and self-interaction of generation 5 polyamidoamine dendrimeric polymers with different terminal groups (surfaces) were characterized using several physicochemical techniques. Amino-surface dendrimers form oligomeric aggregates in aqueous solution, even in the presence of high salt concentrations…
The molecular organisation of protein aggregates, formed under physiological conditions, has been explored by in vitro trypsin treatment and electron microscopy analysis of bacterially produced inclusion bodies (IBs). The kinetic modelling of protein digestion has revealed variable proteolysis rates during protease ex…
We extend the recently proposed order-N algorithms (cond-mat/9703224) for calculating linear- and nonlinear-response functions in time domain to the systems described by nonorthonormal basis sets.
Despite a large amount of data and numerous theoretical proposals, the microscopic mechanism of transport in thick film resistors remains unclear. However, recent low temperature measurements point toward a possible variable range hopping mechanism of transport. Here we examine how such a mechanism affects the gauge f…
The synthesis of nickel nanoparticles by the reduction of nickel chloride with hydrazine in the cationic water-in-oil microemulsions of water/CTAB (cetyltrimethylammonium bromide)/ n -hexanol at 73 °C has been studied. By the analyses of electron diffraction pattern and X-ray diffraction, the resultant particles were…