Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTDirect Observation of the "Pac-Man" Effect from Dibenzofuran-Bridged Cofacial BisporphyrinsYongqi Deng, Christopher J. Chang, and Daniel G. NoceraView Author Information Department of Chemistry, 6-335 Massachusetts Institute of Technology 77 Massachusetts Avenue Cambri…
This second paper in this series regarding the relationship between structure and viscoelastic properties of multiblock polyurethane elastomers presents the results of varying segmental incompatibility at fixed segment length and composition. Three series of amorphous polyurethanes with pendant trimethylammonium group…
Energy barriers for different moves of a single Rh adatom in the vicinity of steps on Rh(111) surface are studied with molecular statics. Interatomic interactions are modeled by the semi-empirical many-body Rosato-Guillope-Legrand potential. We calculate systematically barriers for the descent at straight steps, steps…
The structural basis for the aggregation-induced optical properties of colloidal gold nanosphere aggregates is examined by means of electrodynamics calculations. Recently developed methods for calculating the electrodynamic response of aggregates composed of large numbers of small metal nanospheres in a dielectric med…
This Account reviews our laboratory's research in biomaterials. In one area, drug delivery, we discuss the development of materials that are capable of releasing macromolecules such as proteins and peptides, intelligent delivery systems based on magnetism or microchip technology, new degradable materials such as polya…
Dynamics of poly(ethylene oxide)−polystyrene (PEO−PS) brushes with shorter anchoring PEO blocks adsorbed on a flat surface are considered theoretically. Three relaxation modes are identified: a fast cooperative (hydrodynamic) mode, a slower drag mode, and the slowest anchor-sliding mode. It is shown that the anchor mo…
Efficient numerical methods for simulating cloth deformations have been identified as the key to the development of successful Computer-Aided Design systems for clothing products. This paper presents the formulation of a new finite-volume method for the simulation of complex deformations of initially flat woven fabric…
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Manipulation of the defect chemistry in ZnS:Mn and SrS:Cu bulk and thin-film phosphors has resulted in specific and controllable emission colors across the entire visible spectrum. Saturated red emission is observed at exceptionally low threshold voltages in ac thin-film electroluminescent devices, while unsurpassed l…
Evaluation of polymer end-capping reactions with the aid of electrospray ionisation tandem mass spectrometry techniques (ESI-MS(n)) allows characterisation of novel poly[(R, S)-3-hydroxybutanoic acid]-(a-PHB) telechelics, containing primary hydroxyl groups at both polymer chain ends. The chemical structures of individ…
The arrangements of residual water and alkali-metal cations in zeolites Y and X have been determined by Rietveld refinement in combination with Fourier analysis of X-ray powder patterns. The sodium forms NaY and NaX as well as partially cation exchanged forms MNaY and MNaX (M = K, Rb, Cs) were studied. It was shown th…
The thermally-induced phase separation mechanism was investigated for the system isotactic polypropylene and diphenyl ether. Droplet growth was monitored by using a thermo-optical microscope. The degree of supercooling for liquid-liquid phase separation affected the size and growth rate of the droplets. Increasing the…
The optical attenuation induced in two erbium-doped fibers by <SUP>60</SUP>Co (gamma) -ray exposures to 200 krad has been measured at 3 different dose rates, approximately, 35, 1000, and 20,500 rad/min. The growth of the induced loss was measured at 980, 1300, and 1500 nm. In some instances recovery of the loss after…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTSynthesis of Viologens with Extended π−Conjugation and Their Photochromic Behavior on Near-IR AbsorptionMasato Nanasawa, Makio Miwa, Michiko Hirai, and Tetsuo KuwabaraView Author Information Department of Applied Chemistry and Biotechnology, Yamanashi University, Takeda 4, Kofu…
The thermal behavior of 12-molybdophosphoric acid (HPMo) supported on silica and Zr-loaded silica (Zr content from 1.6 to 17.0 wt %) was studied by X-ray diffraction, Fourier-transform infrared, in situ Raman, and X-ray photoelectron spectroscopic techniques. A silica support stabilizes the Keggin unit of HPMo up to 7…
Dielectric relaxation spectroscopy and computer simulations have been used to elaborate on the loops/bridges population ratio in ordered poly(styrene- block - cis- isoprene- block -styrene), PS−PI−PS, triblock copolymer lamellae. The dynamics of the PI blocks are examined dielectrically for a PS−PI−PS copolymer having…
Near-edge X-ray absorption fine structure is used to investigate the temperature dependence of molecular orientation of semifluorinated liquid crystalline (SF-LC) mesogens, which are attached to the modified isoprene backbone of (i) a poly(1,2-isoprene) homopolymer and (ii) a diblock copolymer consisting of polystyren…
An approach to enlarge preformed colloidal Au nanoparticles in solution based on the Au colloidal surface-catalyzed reduction of Au 3+ by NH 2 OH (“seeding”) has been adapted to 12-nm-diameter colloidal Au nanoparticles immobilized in monolayers and multilayers. Bulk characterization of the ensuing films was carried o…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTMonolithic Mesoporous Silica Templated by Microemulsion Liquid CrystalsPingyun Feng, Xianhui Bu, Galen D. Stucky, and David J. PineView Author Information Department of Chemical Engineering and Department of Chemistry, University of California Santa Barbara, California…
Hyperbranched polyglycerol as well as polyglycerol modified with short apolar oligo(propylene oxide) segments (DP n = 23−52; M w / M n = 1.2−1.4) was deprotonated with diphenylmethylpotassium and used as polyfunctional initiators for the anionic polymerization of ethylene oxide to prepare poly(ethylene oxide) (PEO) mu…