Materials Literature
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We have studied the ground-state properties of phosphorus-related dia- and paramagnetic point defects in P-doped silica and α-quartz. Density functional theory calculations have been performed to determine the structure, charge and spin distribution of the P1, P2, and P4 centers. P1 consists of a three-coordinated P a…
Yellow layered VOPO 4 ·2H 2 O was found to spontaneously, but slowly, convert to a green phase [H 0.6 (VO) 3 (PO 4 ) 3 (H 2 O) 3 ]·4H 2 O upon standing in air. This phase could be prepared hydrothermally from V 2 O 5 + H 3 PO 4 with a small amount of reducing agent added. Single-crystal X-ray analysis gave a = 7.371(3…
Blends of poly(styrene)- b -poly(isoprene) (PS−PI) and poly(isoprene)- b -poly(ethylene oxide) (PI−PEO) were investigated by small-angle X-ray scattering, photon correlation spectroscopy, light microscopy, and rheology. Blends were prepared in which both diblocks had the same PI composition, f, and were investigated a…
Well-ordered two-dimensional hexagonal arrays of micrometer-sized nematic liquid-crystal droplets are prepared in polymer films. Droplets of uniform sizes and shapes are formed by “prefabricating” the voids in which the liquid crystal is to be entrapped. Void preparation involves deposition of polystyrene microspheres…
Amorphous hydrogenated carbon (a-C:H) films in the thickness range 1−20 nm were deposited at 300 K on a Pt(111) single crystal by means of the ion-beam deposition (IBD) method. The product distribution as well as the temperature and thickness dependence of the hydrogen-atom-induced chemical erosion was investigated by…
Surfactant-enhanced pump-and-treat technologies increase the efficiency of nonaqueous-phase liquids (NAPLs) removal from soils. However, high concentrations of surfactants in groundwater impose severe limitations to water treatment. In this paper, we explore the applicability of ultrasonic irradiation as an alternativ…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXT1,3,5-Tricyano-2,4,6-tris(vinyl)benzene Derivatives with Large Second-Order Nonlinear Optical PropertiesBong Rae Cho, Soon Bong Park, Seung Jae Lee, Kyung Hwa Son, Sang Hae Lee, Myung-Ja Lee, Jun Yoo, Yun Kyong Lee, Geon Joon Lee, Tae Im Kang, Minhaeng Cho, and Seung-J…
Nanoporous metal oxides (TiO 2, Al 2 O 3 ) have been synthesized using activated carbon templates with supercritical fluid solvents by using the nanoscale casting (NC) process. The precursors were dissolved in supercritical CO 2 and attached to activated carbon fibers or powders as templates. After removal of the acti…
The model compound, N -phenyl-4-(9-anthracenylethynyl)phthalimide ( 3 ), was synthesized and the thermal curing behavior analyzed. These results were compared to the curing kinetics of similar model compounds N -phenyl-4-(1-naphthylethynyl)phthalimide ( 1 ) and N -phenyl-4-phenylethynylphthalimide ( 2 ). The cure rate…
We have developed a simple and mild method for the fluorination of polybutadiene based on the addition of perfluoroalkyl iodides (R f I) to carbon−carbon double bonds. Triethylborane (Et 3 B) was utilized to initiate this free radical addition to model polybutadiene (PBD) homopolymers and a polystyrene−polybutadiene b…
This paper reports on the influence of the structural properties of two cationic hydroxyethylecelluloses, polyquaternium-4 (PQ-4; 1.13-1.27% N) and polyquaternium-10 (PQ-10; 1.88-1.95% N), on the rheological behavior of their dispersions and of the dispersions of their blends with Carbopol 974P (60.9% COOH) in water.…
Decaoxyethylene cetyl ether [C 16 (EO) 10 ] has been employed as templating agent for large pore disordered MSU-type mesoporous silicas synthesis. The effect of the hydrothermal treatment (heating time and temperature) on the textural properties, in particular, pore diameter of materials has been investigated. The obt…
The intrinsic viscosity of narrow molecular mass distribution polystyrene standards, poly(benzyl) ether dendrimers, and their hybrid block copolymers was measured in a variety of solvents. The relative change in the intrinsic viscosity for all these polymers was almost equivalent, indicating that poly(benzyl ether) de…
We have proposed an easy method for growth of well-aligned patterned CNTs arrays using 3D cubic ordered mesoporous silica films as the catalyst support combined with the soft-lithography technique. This synthetic approach shows fascinating possibilities for directed growth of CNTs that could be used for large-area, lo…
This paper presents a continuation of our earlier research on the crystallization and solid-state structure of polylactide copolymers. The focus here is on random copolymers containing predominately l -lactide and small amounts (1.5, 3, and 6%) of d -lactide. As expected, degrees of crystallinity and spherulite growth…
Byssal threads provide marine mussels with the tenacity to remain sessile in habitats of high flow. Under uniaxial tension, byssal threads are typical of other biological and synthetic fibers in exhibiting an initial linear region followed by yield. They differ, however, in their capacity to recover or "self-heal" fol…
Study on the molecular packing of the α-form of poly( l -lactide) has been attempted taking into account packing energy calculations, refinement against new electron diffraction data, and Monte Carlo simulations. Packing energy has been evaluated for a fixed 10 7 conformation and an antiparallel arrangement of molecul…
Using the spin-polarized tunneling model and taking into account the basic physics of ferromagnetic semiconductors, we study the temperature dependence of the tunneling magnetoresistance (TMR) in the diluted magnetic semiconductor (DMS) trilayer heterostructure system (Ga,Mn)As/AlAs/(Ga,Mn)As. The experimentally obser…
We present a class of discrete Schrödinger operators, with potentials derived from nonprimitive substitutions, that has purely singular continuous spectrum. We give sufficient conditions on the substitution rule assuring singular continuous spectrum, either for a generic set in the hull of the potential or for a set o…
Abstract A low molecular weight prepolymer with reactive end groups was annealed at temperatures between 200 and 245°C to obtain kinetic parameters for solid‐state polymerization of poly(ethylene naphthalate) (PEN). An equation was developed to describe the relationships among time, temperature, and final molecular we…