Materials Literature
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Two kinds of styrene microemulsion systems were polymerized to prepare polystyrene microspheres (micro-PS), one emulsified by sodium dodecyl sulfate (SDS) and coemulsified by 1-pentanol and the other emulsified by octylphenoxypoly(ethoxyethanol) (OP-10). Micro-PS possessed an essentially atactic configuration from 1 H…
New layered perovskite compounds of RbLaTa2O7 and RbCa2Ta3O10, whose Rb+ ions can be ion-exchanged have been synthesized directly by a solid-state reaction. Lithium ion-exchanged compounds, LiLaTa2O7 and LiCa2Ta3O10, have also been synthesized by ion-exchange reactions of the rubidium compounds with LiNO3 molten salt.…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSyntheses of Trisulfonated Phthalocyanines and Their Derivatives Using Boron(III) Subphthalocyanines as IntermediatesSvetlana V. Kudrevich, Sandra Gilbert, and Johan E. van LierView Author Information MRC Group in the Radiation Sciences, Faculty of Medicine, Université…
Conjugates of oligonucleotides with chlorin-type photosensitizers were prepared. Two chlorin moieties, CPP and CHEVP, characterized by a modified pyrrole unit bearing an aldehyde chain, were photochemically prepared from protoporphyrin and heptaethylvinylporphyrin, respectively. These chlorin moieties were coupled thr…
The anionic polymerization of ( R )-β-butyrolactone initiated with either 18-crown-6 complexes of a potassium alkoxide or a simple carboxylate (reference initiator) proceeded with inversion of configuration. As a result ( R )-β-butyrolactone formed an isotactic poly(( S )-β-hydroxybutyrate) with these initiators at ro…
Mesoporous molecular sieves are generated using primary amine surfactants as the template in thte assembly of aluminosilicate inorganic species; aluminium incorporation is accompanied by charge-balancing protonated amine molecules.
We have analyzed a newly available high resolution and precision repeat of the original Martin and Haseltine experiment which includes the influence of DMSO on the results. The new model includes the production and diffusion of radical species and .OH radical attack on DNA as well as the direct hits. Calculations of s…
We describe the deformation behavior of polymer brushes and mushrooms compressed by finite-sized particles for the cases where the chains are fixed or mobile on the grafting surface. When the size of the particle is large compared to the grafting distance of the chains, the force on the particle is the same to lowest…
The interaction of NO with Cu{110} is complex and is strongly dependent on both coverage and temperature. When Cu{110} is exposed to NO in the temperature range 40−85 K, initial adsorption leads to the presence of molecular NO on the surface. With further exposure this is replaced by the dimeric (NO) 2 species and N 2…
A systematic PWM iron loss study has been carried out. All the loss components can be given as functions of the sum of pulses width in half a period. PWM loss surplus when compared with the sinusoidal supply is more pronounced in the laminations with more important part of dynamic loss in the whole loss outcome. Along…
The dielectric behavior of polybutadiene copolymers with different compositions of 1,2 and 1,4 units is analyzed to study the influence of the microstructure on the relaxation spectrum, especially the β relaxation. The experimental data were obtained between 10 -2 and 10 6 Hz and temperatures above and below T g . Abo…
Conditions for preparing copper–cerium mixed oxides by coprecipitation have been examined. X-Ray diffraction (XRD), electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the oxides calcined at different temperatures up to 1073 K. In all cases, a solid solution is fo…
The kinetics of spiropyran photochromic systems in solution in a stirred batch reactor continuously irradiated with monochromatic light was studied by UV/visible spectrophotometry. The plots of absorbance vs time were analyzed, and the desired parameters (quantum yields, UV/visible spectrum of the unstable photomerocy…
Rapid water exchange and slow rotation are essential for high relaxivity MRI contrast agents. A variable-temperature and -pressure (17)O NMR study at 14.1, 9.4, and 1.4 T has been performed on the dimeric BO(DO3A)(2), 2,11-dihydroxy-4,9-dioxa-1,12-bis[1,4,7,10-tetraaza-4,7,10-tris(carboxymethyl)cyclododecyl]dodecane,…
The contribution of a redox mechanism involving lattice oxygen in the catalytic combustion of methane over PdO/ZrO 2 catalysts, prepared from amorphous Pd−Zr alloys, has been studied by means of gas pulse methods, including a novel technique “pulse thermal analysis”, and using labeled catalysts containing Pd 18 O. Spe…
The free-volume theory for solvent self-diffusion coefficients in polymer−solvent systems is modified to include a more general analysis of the effects of solvent size. The predictions of the theory are compared with self-diffusion data for a diverse set of solvents and four polymers, polystyrene, poly(vinyl acetate),…
A new class of natural antioxidants, chlorophyll a related chlorins 3, 4 (S), 4 (R), 5 (R), 6, 7, 8, and 9, have been synthesized from a chlorophyll a degradation product, pheophorbide a methyl ester ( 1 ). Claisen-type intramolecular condensation of pyropheophorbide a methyl ester ( 2 ) afforded the common intermedia…
A series of mixed-substituent poly(organophosphazenes) with the general structure {NP[OCH 2 CH 2 OCH 2 CH 2 OCH 3 ] x [O(CH 2 ) y CH 3 ] 2- x } n, where x = 1 and y = 2−9 was synthesized. These polymers are candidates for use as solid polymeric, ionic conduction media. The polymers were characterized by 1 H, 13 C, and…
Polymer gels swollen in a good solvent and subjected to a uniaxial deformation have been studied by small-angle neutron scattering (SANS). In all the experiments, the solvent is deuterated; this is equivalent to deuteration of the entire network. The gels were studied at two degrees of swelling, Q: Q = 11, which is ve…
Monte Carlo simulations were performed on star-burst dendrimer molecules having various numbers of spacer bonds P and various numbers of generations g . Each molecule is modeled by connecting freely-rotating rigid bonds in a star-burst architecture and by attaching to each end of the bond a hard-sphere bead of diamete…