Materials Literature
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We comment on the stability analysis of alpha-quartz under pressure by Gregoryanz et al., Phys. Rev. Lett. 84, 3117 (2000). The proper stability criterion for solids under pressure has to be formulated in terms of Birch coefficients rather than in terms of elastic constants. We show that the fictitious (extrapolated)…
A novel protocol for designing a variety of topologically unique multicyclic polymer architectures, such as mono-, bi-, and tricyclic polymers as well as topological isomers, has been proposed on the basis of an electrostatic self-assembly of polymer precursors having five-membered cyclic ammonium salt groups accompan…
The snapping shrimp (Alpheus heterochaelis) produces a loud snapping sound by an extremely rapid closure of its snapper claw. One of the effects of the snapping is to stun or kill prey animals. During the rapid snapper claw closure, a high-velocity water jet is emitted from the claw with a speed exceeding cavitation c…
The Hall-type ion source operated with nitrogen has been used in two ways in the synthesis of carbon nitride films: by ion beam nitridation of a graphite target and by simultaneous deposition on a collector (silicon wafer and nickel foil) of sputtered carbon atoms and nitrogen atoms from the surrounding nitrogen plasm…
The effect of an oriented microphase-separated structure, induced by an applied flow bias field (roll casting), on the crystallization of the polyethylene (PE) block in a semicrystalline polystyrene- block -(polyethylene- alt -propylene)- block -polyethylene terpolymer has been analyzed. The orientation and morphology…
Calculations of crystal field parameters from first principles depend upon a knowledge of the crystal structure in the immediate neighbourhood of the magnetic ion. The calculated crystal field contributions for single ligands (see Chapter 1) can then be combined to estimate values of the crystal field parameters for r…
Batch adsorption experiments in the presence of oxygen were performed to study the interlayer reactions of aniline on Cu(II)-montmorillonite in aqueous solutions. At concentrations below a critical value of C C = 2.6 mmol dm - 3 only a colored Cu(II)−aniline complex is formed, characterized by a stability constant of…
The reaction mechanism and energetics for the conversion of methanol to formaldehyde by an iron−oxo species, FeO +, is investigated. Three competitive reaction pathways for the catalytic reaction are analyzed from DFT computations at the B3LYP level of theory. In Path 1, the H atom of the OH group of methanol is first…
Amine-based donor radicals, such as dimethylamino-, diethylamino- and morpholinonitronyl nitroxides, were synthesized, and their donor abilities were examined by cyclic voltammetry. ESR spectra of the singly oxidized donor radicals showed ground state triplet signals derived from the cation radicals of these donor rad…
Hexanuclear {[Mn(bpy)2]2(μ-NC)2[Mo(CN)6]2(μ-CN)2[Mn(bpy)2]2}· 8H2O is formed in the reaction of the [Mo(CN)8]4- complex with labile cis-[Mn(bpy)2Cl2] in aqueous solution. The X-ray structure of the Mn4Mo2 cluster reveals an octahedral geometry with Mn atoms in a rectangular array. The Mo units located on the axis almo…
Reaction of magnesium sulfate with aqueous ammonia in a hydrothermal condition (150−180 °C) produced a fibrous magnesium hydroxide sulfate hydrate (MHSH) with a composition corresponding to a stoichiometry of 4.34Mg(OH) 2 ·MgSO 4 · x H 2 O. Chemical composition analysis showed that the quantity of x was more likely to…
We report the synthesis of nonaqueous dispersion of CdSe nanoparticles and the layer-by-layer assembly of hybrid poly(vinylpyridine) (PVP)/CdSe multilayer thin films based on hydrogen bonding. The multilayer buildup is monitored by UV−vis spectra, which showed a linear increase of the film absorbance with the number o…
Electrochemically prepared poly(3,4-dimethoxypyrrole), poly(3,4-dimethoxythiophene), poly(3,4-ethylenedioxypyrrole), and poly(3,4-ethylenedioxythiophene) have been characterized by cyclic voltammetry (CV) and ultraviolet−visible (UV−vis) and Fourier transform infrared (FTIR) spectroscopy and were subsequently investig…
Enzymatic phosphorylation and dephosphorylation reactions were used to modify a genetically engineered variant of spider dragline silk. The approximately 25 kDa protein was phosphorylated with cyclic AMP-dependent kinase and dephosphorylated with calf intestinal alkaline phosphatase. Phosphorylation inhibited beta-she…
A new strategy for synthesis of hyperbranched polymers from commercially available A 2 type and BB‘ 2 type monomers has been developed. In the first part of this series, hyperbranched polysulfone−amine with multiamino groups is prepared by polyaddition of 1-(2-aminoethyl)piperazine (BB‘ 2 ) to divinyl sulfone (A 2 ) w…
We investigate the effects of impurity scattering on the conductance of metallic carbon nanotubes as a function of the relative separation of the impurities. First we compute the conductance of a clean (6,6) tube, and the effect of model gold contacts on this conductance. Then, we compute the effect of introducing a s…
133Cs and 13C-NMR have been used to study the electronic properties of the polymerized phase of CsC60 at ambient and under hydrostatic pressure. The salient result of this study is the finding of fluctuations in the local field at 133Cs site which are independent of the applied pressure and due to thermally activated…
The solution structure and dynamics of metal-bound water exchange have been studied in a series of diastereoisomeric gadolinium complexes of tetra(carboxyethyl) derivatives of 1,4,7,10-tetraazacyclodecane. The structures of the ( RRRS ), ( RSRS ), and ( RRSS ) ligands and the Eu, Gd, and Tb complexes of the ( RRRR ) i…
Core/shell semiconductor nanocrystals with InAs cores were synthesized and characterized. III−V semiconductor shells (InP and GaAs), and II−VI semiconductor shells (CdSe, ZnSe, and ZnS) were overgrown on InAs cores with various radii using a two step synthesis. In the first step cores were prepared, and in the second…
A procedure of the template displacement by organosilanes was utilized to prepare pure-silica and cerium-substituted mesoporous materials with tailored surface functionality. These two self-assembled mesostructured systems exhibit hexagonal arrangement of mesopores but they show different reactivity with respect to or…