Materials Literature
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We present a spectroscopic study of the green fluorescence resulting from pump excited-state absorption in Er-doped silica fibers excited in the 800-nm range. The absorption and emission bands are selectively attributed to the (4)S(3/2) and (2)H(11/2) levels. The fluorescence response at two excitation wavelengths, th…
The microstructures of anisotropic Nd-Fe-Co-B-(Ga, or Zr) magnet powders produced by the hydrogenation-decomposition-desorption-recombination (HDDR) process and the resulting crystallographic c-axis orientation of Nd2(Fe,Co)14B crystals in the powder particles have been studied. It was found that the powder particles…
Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.
A brittle-to-ductile transition via dislocation nucleation is directly observed by molecular-dynamics simulation of the propagation of a sharp crack in a single crystal under mode-I loading. The crack-tip system is modelled using an embedded-atom method (EAM)-type interatomic potential function for alpha -Fe (BCC) and…
Applying the bosonization procedure to weakly coupled Hubbard chains, we discuss the fixed points of the renormalization-group procedure where all spin excitations are gapful and a singlet pairing becomes the dominant instability.
We have investigated intramolecular photoinduced charge separation and recombination in a series of cyclophanebridged porphyrinquinone systems by means of time−resolved fluorescence decay measurements. Rates of charge separation have been determined as a function of the free energy change of the reaction, of the polar…
ABSTRACT Water vapor permeability (WVP), tensile strength (TS), and elongation (E) were investigated in laminated methyl cellulose/corn zein‐fatty acid films. They were prepared by casting corn zein‐fatty acid solutions onto methyl cellulose films. WVP decreased as chain length and concentration of fatty acids increas…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFormation of Interconnected Globular Structure of Silica Phase in Polyimide-Silica Hybrid Films Prepared by the Sol-Gel ProcessAtsushi Morikawa, Hidehiro Yamaguchi, M. Kakimoto, and Yoshio ImaiCite this: Chem. Mater. 1994, 6, 7, 913–917Publication Date (Print):July 1, 1994Pu…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTsynergistic Coordination in Ternary Complexes of Eu3+ with Aromatic .beta.-Diketone Ligands and 1,10-PhenanthrolineSteven T. Frey, Meng Lian Gong, and William D. Horrocks Jr.Cite this: Inorg. Chem. 1994, 33, 15, 3229–3234Publication Date (Print):July 1, 1994Publication Histo…
Low‐temperature phase equilibria ranging from 1000° to 1200°C in the ZrO 2 –CeO 2 system were investigated by annealing compositionally homogeneous ZrO 2 –CeO 2 solid solutions in a Na 2 B 2 O 7 .1 NaF flux. The 5 mol% CeO 2 samples decomposed into monoclinic ( m ) and tetragonal ( t ) phases during annealing at 1100°…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSurface-Induced Ordering in Asymmetric Block CopolymersY. Liu, W. Zhao, X. Zheng, A. King, A. Singh, M. H. Rafailovich, J. Sokolov, K. H. Dai, E. J. Kramer, and Cite this: Macromolecules 1994, 27, 14, 4000–4010Publication Date (Print):July 1, 1994Publication History Publishe…
Solvent-binding sites were compared in 10 different crystal forms of phage T4 lysozyme that were refined using data from 2.6 A to 1.7 A resolution. The sample included 18 crystallographically independent lysozyme molecules. Despite different crystallization conditions, variable crystal contacts, changes due to mutatio…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolyimide-Silica Hybrid Materials Modified by Incorporation of an Organically Substituted AlkoxysilaneShuhong Wang, Z. Ahmad, and J. E. MarkCite this: Chem. Mater. 1994, 6, 7, 943–946Publication Date (Print):July 1, 1994Publication History Published online1 May 2002Published…
Fatigue characteristics of PbZr 0.4 Ti 0.6 O 3 (PZT) thin-film capacitors made by sol-gel spin coating have been evaluated using hysteresis measurement by bipolar continuous pulses. The following three stages were found according to the cumulative polarization switching cycles: (1) slow fatigue stage at the initial sw…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Effect of Structural Modifications on Charge Migration in Mesomorphic PhthalocyaninesPieter G. Schouten, John M. Warman, Matthijs P. de Haas, Cornelus F. van Nostrum, Gerwin H. Gelinck, Roeland J. M. Nolte, Marc J. Copyn, Jan W. Zwikker, Michael K. Engel, and Cite this:…
A study was performed to determine the time-course of oxidative degradation and the extent to which the degradation proceeded through the bulk of ultra-high molecular weight polyethylene joint components that had been irradiated and stored on a shelf. Standardized cylindrical samples, taken from a single batch of extr…
The number of protein structures known in atomic detail has increased from one in 1960 (Kendrew, J.C., Strandberg, B.E., Hart, R.G., Davies, D.R., Phillips, D.C., Shore, V.C. Nature (London) 185:422-427, 1960) to more than 1000 in 1994. The rate at which new structures are being published exceeds one a day as a result…
Almost everybody in the urethanes industry is by now familiar with the different options for the recycling of urethane-based materials. Physical recycling (fillers in the polyol), chemical recycling (glycolysis, hydrolysis) and energy recovery are the main options under development. The actual process, however, is onl…
Abstract The mechanical properties and the high‐temperature behaviour of fibre‐reinforced composites are controlled by both the microstructure and the microchemistry of fibre/matrix interlayers. For a C‐fibre reinforced SiC composite and various SiC (Nicalon)‐fibre reinforced Duran glasses, the composition of the inte…
Abstract Oxygen plasma and ultra violet (UV) ozone treatments have been used to oxidize the surfaces of batches of natural wool fibres and woven cloths. The changes in surface composition and chemistry induced by these treatments have been followed using X‐ray photoelectron spectroscopy (XPS). Oxidation of surface pro…