Materials Literature
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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…
Synthetic efforts utilizing Cs 2 CO 3, Ag, M 2 S 3 (M = As, Sb), and S 8 in supercritical ammonia (160 °C) have yielded four novel, one-dimensional compounds in the Cs−Ag−M−S system. These members were characterized by single-crystal X-ray diffraction and diffuse reflectance measurements. Cs 3 Ag 2 Sb 3 S 8 ( I ) crys…
The ductility of highly irradiated Zircaloy-4 material was evaluated by conducting tube burst, tube tensile, and ring tensile tests on fuel cladding and guide tubes irradiated in two PWRs. The specimen fluence ranged between 9 and 12.3 × 1021 n/cm2 (E > 1 MeV), and test temperatures ranged from 313 to 673 K. Th…
Mixed monolayers of a water-soluble tetracationic porphyrin (TMPyP) and an insoluble lipid matrix with anionic head groups (DMPA) were formed by the cospreading method. A ratio TMPyP:DMPA = 1:4 was selected by investigation of π−area isotherms and stability of the cospread monolayer. Reflection spectroscopy has been u…
Real-time in situ energy-dispersive X-ray diffraction has been used to study the synthesis of the open-framework sulfide TMA−SnS-1, under hydrothermal conditions. The effects of varying the temperature of reaction, reactant source, and pH of solution on the synthesis have been studied. It is found that temperature is…
Pole figures obtained by wide-angle X-ray diffraction have been used to quantify and characterize the molecular orientations induced in low-density poly(ethylene) films prepared by the tubular film process. Small-angle X-ray scattering was employed to determine the type and orientation of the morphology within the fil…
Ring-opening polymerization of ε-caprolactone catalyzed by rare earth halides and rare earth halide−epoxide has been carried out for the first time. It was found that rare earth halides have low activities for the polymerization of ε-caprolactone, but in the presence of epoxide, rare earth halides are highly active fo…
Hydroxoaluminium tricarboxymonoamidephthalocyanine has been adsorbed on TiO2(Degussa P-25) particles. Water suspensions and solid samples were analysed by SEM and by IR, visible extinction, diffuse reflectance and fluorescence spectroscopy. Visible spectra showed that the dye is not highly aggregated on the surface. F…
A dendritic system based upon a pentaerythritol unit bearing pendant 2,2′:6′,2″-terpyridine metal-binding domains is described; tetranuclear complexes bearing pendant carborane units are reported.
The synthesis of the unprotonated two-electron-reduced isopolytungstate [W 10 O 32 ] 6 - ( 2 ) is reported here. Additionally, full experimental details are given for the acquisition of both high signal-to-noise and integrable natural-abundance 17 O NMR spectra of polyoxometalates. Titration of an acetonitrile solutio…
A technique is presented for generating atomistic models of amorphous polymer structures starting from chain configurations on lattice. The method guarantees Gaussian chain statistics and enables control of chain tacticity and monomer sequence while avoiding severe overlaps between the atoms in the structure. We show…
The effects of cyclic base/acid treatment on electrochemically synthesized polypyrrole−toluenesulfonate (PPY−TSA) and polypyrrole−poly(styrenesulfonate) (PPY−PSSA) films are investigated. The structural modification of the films during the undoping−redoping process is monitored using spectroscopic techniques and eleme…
The lithium form of taeniolite, intercalated with hydroxyaluminum and hydroxyaluminum−zirconium cations, served as the molecular template for carbon−mineral nanocomposites and derived carbons. The inorganic matrixes were saturated by furfuryl alcohol followed by its interlayer polymerization and carbonization. Carbons…
2H-NMR spin-lattice relaxation times T1 of phenyl ring deuterated toluene have been measured as a function of temperature (75–290 K) at Larmor frequencies between 13.8 and 55.8 MHz. The results are interpreted by assuming a Cole–Davidson rotational correlation time distribution for the α process dominating T1 at tempe…
The effect of substrate surface hydrophobicity on fibronectin (Fn) adsorption and endothelial cell adhesion strength was studied. Bovine aortic endothelial cells (BAEC) were plated for 2 h with and without preadsorbed Fn on slides coated with homopolymers and copolymers of hydrophilic polyhydroxyethylmethacrylate (pol…
The Fe III /Fe II and Fe II /Fe I reduction potentials of a series of model hemes have been measured by cyclic voltammetry in dimethylformamide at 25 °C as a function of the concentration of added axial ligands. The six porphyrinate ligands utilized were tetraphenylporphyrin (TPP), tetramesitylporphyrin (TMP), and a s…
Atomic force microscopy (AFM) makes it possible to directly detect morphological changes on the surface of a zeolite that are due to dissolution when the crystal is immersed in either an alkaline (0.1 N NaOH) or acidic (0.2 N H 2 SO 4 ) aqueous solution at room temperature. The AFM images revealed for the first time t…