Materials Literature
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The temperature dependence of structural properties for infinitely long gold nanowires is studied. The molecular dynamics simulation method and the embedded-atom potential are used. The wires constructed at T=0 K with a face-centered cubic structure and oriented along the (111), (110), and (100) directions are investi…
The wetting behavior of thin films of symmetric poly(styrene- block -methyl methacrylate) was investigated on self-assembled monolayers (SAMs) of octadecyltrichlorosilane (OTS) that were chemically modified by exposure to X-rays in the presence of air. The concentration of aldehyde and hydroxyl groups on the surface o…
We investigate short-range order and local atomic configuration in charge-balanced aluminosilicate glasses as functions of composition, using 17 O and 27 Al MAS and triple-quantum magic angle spinning (3QMAS) NMR spectroscopy. Enhanced resolution in 17 O and 27 Al 3QMAS spectra, compared to MAS NMR, allows the quantif…
We study theoretically using scaling arguments the behavior of polyelectrolyte gels in poor solvents. Following the classical picture of Katchalsky, our approach is based on single chain elasticity but it accounts for the recently proposed pearl-necklace structure of polyelectrolytes in poor solvents. The elasticity b…
A specially designed solid-state deuterium nuclear magnetic resonance probe was used to examine the effect of uniaxial elongation on the chain mobility in the amorphous region of semicrystalline nylon 6. In measurements conducted near the glass transition temperature, there was measurable deformation-induced enhanceme…
Mesoporous molecular sieves of MCM-48 type were prepared by conventional hydrothermal and novel room temperature syntheses. Scanning electron microscopy (SEM) studies have shown that nonagglomerated uniform spheres of size ca. 0.5 μm were obtained by the room temperature method. Internal pore structure was studied by…
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.…