Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTRole of Cation Size in the Energy of Electron Transfer to 1:1 Polyoxometalate Ion Pairs {(M+)(Xn+VW11O40)}(8-n)- (M = Li, Na, K)Vladimir A. Grigoriev, Craig L. Hill, and Ira A. WeinstockView Author Information Department of Chemistry, Emory University Atlanta, Georgia…
Electronic excitation energies of 16 azobenzene dyes have been calculated by ab initio methods within the second-order polarization propagator approximation (SOPPA). Good agreement with expriment is found for the lowest singlet and triplet states for both the trans - and cis -azobenzene molecules. The differences are…
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The assembled structure of the heptane bolaamphiphile, bis( N -α-amido-glycylglycine)-1,7-heptane dicarboxylate, displays a sensitivity to the acidity of a solution. At pH 4, the heptane bolaamphiphile grows to a crystalline tubule in two weeks. At pH 8, a helical ribbon structure is formed in one week. The degree of…
In order to describe the recently observed effect of current induced magnetization reversal in magnetic nanostructures, the thermokinetic theory is applied to a metallic ferromagnet in contact with a reservoir of spin polarized conduction electrons. The spin flip relaxation of the conduction electrons is described the…
Resonance Raman, ESR, and UV−vis−NIR techniques were used to characterize the secondary doping process in polyaniline (PANI). Experimental results obtained with the first two techniques showed the transformation of diamagnetic quinoid segments into radical semiquinone units while UV−vis−NIR experiments showed the incr…
The catalytic degradation of high-density polyethylene to hydrocarbons was studied over different zeolites. The product range was typically between C 3 and C 15 hydrocarbons. Distinctive patterns of product distribution were found with different zeolitic structures. Over large-pore ultrastable Y, Y, and β zeolites, al…
The non-equilibrium behaviour of concentrated colloidal dispersions is studied using Stokesian Dynamics, a molecular-dynamics-like simulation technique for analysing suspensions of particles immersed in a Newtonian fluid. The simulations are of a monodisperse suspension of Brownian hard spheres in simple shear flow as…
The phase diagram of the blends of a diblock copolymer (A−B) and a random copolymer (ABR) is constructed by the modified confined-chain model developed earlier where the morphology of A−B block copolymer is lamellae and the composition of ABR random copolymer is close to that of A−B. These theoretical results predict…
The phase transitions in two liquid crystalline polyesters have been studied by diffraction techniques employing synchrotron radiation. The two polyesters, derived from p,p ‘ -bibenzoic acid and 3-methyl-1,6-hexanediol, only differ on the optical activity of the chiral spacer: both the active and racemic polymers have…
The response of organic polymers and proteins including poly(methyl methacrylate) (PMMA) and the protein bovine serum albumin (BSA) to a short duration 4.5 GPa shock pulse, termed a “nanoshock”, is studied using ultrafast coherent Raman spectroscopy (CARS) to monitor density-dependent vibrational frequency shifts of a…
The tetra(4-methoxyphenyl)phosphonium iodide C 28 H 28 O 4 PI (MOPPI) is a crystal built up with quasi octupolar tetrahedral chromophores having quadratic nonlinear optical (NLO) properties. The calculated values of the highest tensor component β xyz for the hyperpolarizable chromophore, in its most stable S 4 geometr…
Second- and third-generation alkoxysilyl-terminated carbosilane dendrimers have been used as building blocks for the synthesis of high surface area xerogels, which were characterized by 29 Si CP MAS NMR spectroscopy, nitrogen adsorption/desorption porosimetry, IR spectroscopy, transmission electron microscopy (TEM), a…
Cellulose ethers containing alkyl side chains of varying length were prepared from (2-hydroxypropyl)cellulose and alkyl bromides. Two different synthetic methods were employed. The average degree of alkyl substitution of the product polymers ranges from 1.8 to 2.8, as determined from 1 H NMR spectroscopy. Surface pres…
The competitive adsorption behavior between oxygen- and nitrogen-containing functionality in poly(methyl methacrylate- co -2-vinylpyridine) (MMA2VP) and poly(methyl methacrylate- co -4-vinylpyridine) (MMA4VP) random copolymers onto alumina substrate was investigated. The adhesive strength of both the MMA2VP/alumina an…
The rupture of standing three-dimensional soap foams was examined. A foam of controlled size and water content was produced in a vertical column and the evolution of its liquid fraction under gravitational drainage was followed by electrical conductivity measurements. Using simple models to describe simultaneously foa…
A new regioregular polythiophene derivative bearing side chains with exactly six oxyethylene units has been synthesized. From the thermochromic and ionochromic behavior of this polymer, it is concluded that the hexa(oxyethylene) side chains induce a more planar conformation of the polythiophene backbone than random-le…
The chlorination and regeneration of poly(3-(4-fluorophenyl)thiophene) (PFPT) thin films has been investigated using cyclic voltammetry, energy dispersive analysis by X-ray, and X-ray photoelectron spectroscopy. A complete substitution of all 4-thiophene positions of the electrodeposited polymer is achieved by electro…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPorphyrin-containing [2]-Rotaxanes: Metal Coordination Enhanced Superexchange Electron Transfer between Noncovalently Linked ChromophoresMikael Andersson, Myriam Linke, Jean-Claude Chambron, Jan Davidsson, Valérie Heitz, Jean-Pierre Sauvage, and Leif HammarströmView Au…
In the course of surface defect characterization on MgO nanoparticles three different types of O - species were observed by electron paramagnetic resonance (EPR) spectroscopy. They are a result of UV excitation under high-vacuum conditions/in O 2 atmosphere or of surface color center bleaching by N 2 O, respectively.…