Materials Literature
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Disc shaped samples of the glass composition: 0.40Bi 2 O 3 –0.60B 2 O 3 were prepared by a melt quenching technique by keeping the quenching rate constant but gradually increasing the melt annealing or ageing time from 15 to 220 min at a temperature of 850 °C. A total of five glass samples were prepared. Density, ultr…
The ultrastructure and mineralogy of cultured and wild specimens of the green algae Acetabularia acetabulum were studied. Sites of calcification were clarified using TEM and SEM. Minerology was determined via electron diffraction, energy‐dispersive x‐ray microanalysis, and Fourier transform infrared spectral analyses…
The effect of host glass composition on the optical absorption and fluorescence spectra of Nd 3+ has been studied in mixed alkali borate glasses of the type x Na 2 O–(30− x )K 2 O–69.5B 2 O 3 –0.5Nd 2 O 3 ( x = 5, 10, 15, 20 and 25). Various spectroscopic parameters such as Racah ( E 1 , E 2 and E 3 ), spin–orbit ( ξ…
Abstract The ductile–brittle transition temperatures were determined for compatibilized nylon 6/acrylonitrile‐butadiene‐styrene (PA6/ABS) copolymer blends. The compatibilizers used for those blends were methyl methacrylate‐ co ‐maleic anhydride (MMA‐MAH) and MMA‐ co ‐glycidyl methacrylate (MMA‐GMA). The ductile–brittl…
Highly ordered ZnO crystals of 0.15 μm width and 0.5 μm length were grown on silicon wafers coated with a monolayer of SiCl 3 (CH 2 ) 11 −O−C 6 H 5 molecules. Various techniques (contact angle measurements, ellipsometry, ATR-FTIR) were employed for determining the quality of the monolayer coating. In addition, the bar…
A systematic search method that identifies trial crystal structures by manipulating a molecular model in direct-space within a defined unit cell and comparing calculated and experimental powder X-ray data and assessing calculated lattice energies has been extended to allow simulation of crystal structures having two s…
The synthesis of nanostructured polymer gels via polymerization of hydrophilic monomers in lyotropic liquid crystal (LLC) phases has recently been of great interest. This work describes the effects of monomer organization on the photopolymerization kinetics of acrylamide in various LLC phases of surfactant/water syste…
This work deals with the preparation and the surface characterization of biodegradable nanocomposites made of poly(ε-caprolactone) (PCL) and a montmorillonite-type clay. Nanocomposites with different relative compositions of PCL and montmorillonite, either natural or organo-modified by various alkylammonium cations, a…
The lanthanide(III) complexes of three tetraamide DOTA bearing pyridyl, phenolic and hydroxypyridyl substituents have been studied by NMR, luminescence and cyclic voltammetry. The relaxivity profiles of the gadolinium complexes of the pyridyl and phenolic ligands were flat and essentially the same between pH 2 and 8.…
RATIONALE AND OBJECTIVES: Dendrimer-based magnetic resonance imaging (MRI) contrast agents offer many advantages including high levels of amplification. The objective of this research was to test the adequacy and viability of a new family of dendrimers for use as MRI contrast agents in vitro and in vivo. METHODS: Dend…
Condensation of 2,4-bis(phenylhydroxymethyl)furan with pyrrole and p-toluylaldehyde formed, instead of the expected 5,20-diphenyl-10,15-di(p-tolyl)-2-oxa-21-carbaporphyrin, a pyrrole addition product [(H,pyr)OCPH]H(2); this product can formally be considered as an effect of hydrogenation of 3-(2'-pyrrolyl)-5,20-diphen…
The synthesis of a new oxaaza macrocyclic ligand, L, derived from O(1),O(7)-bis(2-formylphenyl)-1,4,7-trioxaheptane and tren containing an amine terminal pendant arm, and its metal complexation with alkaline earth (M = Ca(2+), Sr(2+), Ba(2+)), transition (M = Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+)), post-transition (M…
The temperature behaviour of the optical absorption edge in the range of phase transitions for CuCrP 2 S 6 crystals is studied. The absorption edge is shown to be described by the Urbach rule with different convergence point coordinates in antiferroelectric and paraelectric phases. In the intermediate phase there is n…
Abstract The effect of surface hydrophilicity was induced from the amide units in the polyesteramide. The surface energies and compositions of the polyesteramides were studied by employing contact angle and interfacial tension measurements and ESCA analysis. Biodegradability was evaluated form various methods includin…
In our recent study Xu et al (2002 Chem. Phys. Lett. 364 57–63), a phase transformation from the hexagonal to the tetragonal structure in the annealed ZnO films on silicon was studied by atomic force microscopy. Cathodoluminescence (CL) and glancing-angle x-ray diffraction analysis of the ZnO films indicated that such…
Abstract The swelling of membranes of the polyelectrolyte complex (PEC) between chitosan and alginate shows a similar pattern to that of other PECs. However, if the swelled membranes are dried, a second swelling process is seen which exhibits Fickian behavior. The apparent activation energy was estimated to be 32.8 kJ…
The synthesis, structure, and spectroscopic characterization of a series of phenylacetylenylene rodlike molecules containing dipyrromethene (dipyrrin) ligands are described. The combination of the phenylacetylenylene groups with the porphyrinogenic dipyrrin moieties results in a rich absorption spectroscopy for these…
We report the use of three enantiomerically pure and electronically tuned ruthenium carbonyl porphyrin catalysts for the asymmetric cyclopropanation and epoxidation of a variety of olefinic substrates. The D(4)-symmetric ligands carry a methoxy, a methyl or a trifluoromethyl group at the 10-position of each of the 9-[…
A new strategy to effect photoinduced control over molecular self-assembly is reported. This strategy uses the reversible trans-cis photoisomerization of a novel azobenzene system, where the trans- and cis-forms self-assemble into dramatically different higher-order structures. The trans-azobenzene form of this molecu…
The time evolution of the flow-induced changes in structure of two-dimensional suspensions have been studied by means of video microscopy. The interparticle forces were tailored to produce a two-dimensional (2D) particulate network that could be reversibly broken down by means of a shear flow. Two types of suspensions…