Materials Literature
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The nitrogenation of rare-earth--transition-metal compounds $({R}_{2}{M}_{17})$ more than doubles the Curie temperature $({T}_{C})$ of iron-rich compounds but lowers ${T}_{C}$ of cobalt-rich compounds. Self-consistent spin-polarized electronic-structure calculations are carried out to understand this unusual behavior…
Photostimulated luminescence phenomena have been observed in Ce3+-doped alkali borate glasses prepared under a reducing atmosphere. When the x-ray irradiated glasses were excited by a He–Ne laser (633 nm), photostimulated luminescence at about 360 nm due to the 5d–4f transition of Ce3+ ions was observed. The intensity…
Comparisons are made of the translational and rotational diffusion of small-molecule probes in a polymer near its glass transition temperature, ${T}_{g}$. In the rubbery state, ${1.1T}_{g}>T>{T}_{g}$, translational diffusion is much less temperature dependent than rotational reorientation; in a ``quenched'' glas…
We show the importance of the role of strain in La0.7Sr0.3MnO3 films by revealing the dominance of stress anisotropy effects over magnetocrystalline anisotropy effects in the magnetic anisotropy of these films. Magnetic anisotropy measurements of (001) and (110) La0.7Sr0.3MnO3 thin films on SrTiO3 and LaGaO3 substrate…
We demonstrate that elastic anomalies and lattice instabilities in the the A15 compounds are describable in terms of first-principles LDA electronic structure calculations. We show that at T=0 V_3Si, V_3Ge, and Nb_3Sn are intrinsically unstable against shears with elastic moduli C_11-C_12 and C_44, and that the zone c…
We report experimental evidence for an enhancement, due to the hydrodynamic interactions (HI), of the self-diffusion function ${D}_{s}(t)$ of colloidal particles at intermediate and long times. Monolayers of paramagnetic polystyrene spheres confined to an air/water interface are studied using digital videomicroscopy.…
This paper discusses approaches to Mars in-situ resource utilization (ISRU) using the reverse water gas shift (RWGS) reaction, which offers a potential means of producing oxygen on Mars at a significantly lower energy cost than the zirconia-electrolysis system. The RWGS also can be used as the first step in a process…
Measurements have been made to investigate the isothermal decomposition characteristics of hydroxylammonium nitrate (HAN) in the condensed phase over the temperature range from 120 to 180 C. Experiments were conducted at atmospheric pressure in a nitrogen environment using confined rapid thermolysis (CRT)TFTIR spectro…
We examine the validity of the hypothesis of self-similarity in systems coarsening under the driving force of interface energy reduction in which three dimensional particles are intersected by a one or two dimensional diffusion matrix. In both cases, solute fluxes onto the surface of the particles, assumed spherical,…
Migration-generating equipment using a vacuum technique was constructed to measure the migration properties of antidegradants to the surface in compounded rubber in a short time. With this equipment, the migration of antidegradants to the surface is accelerated by the fast evaporation of organic molecules on the surfa…
Several fire-resistant formulations were prepared from a sample of poly(vinyl chloride) (PVC), small variable proportions of chloroorganic adducts [1,2,3,4,7,7-hexachloro-5-carboxy,bicyclo(2,2,1)heptene-2] or [1,2,3,4,7,7-hexachloro-5-carboxy,5-methyl-bicyclo(2,2,1)heptene-2] as fire-retarding modifiers, plasticizers…
The effects of some polymerization conditions on poly(vinyl chloride) (PVC) particles produced by the suspension polymerization process were studied on a laboratory scale. The different stages of vinyl chloride suspension polymerization were investigated experimentally by using an on-line sample withdrawal technique d…
The degree of mechanical reinforcement that could be obtained by the introduction of henequen cellulosic fibers in a low-density polyethylene, LDPE, matrix was assessed experimentally. Composite materials of LDPE-henequen cellulosic fibers were prepared by mechanical mixing. The concentration of randomly oriented fibe…
This article reports the effect of cell structure on oil absorption of highly oil-absorptive polyurethane foam (ON-PUR), which is suitable for on-site foaming. We have developed ON-PUR as an oil absorbing polyurethane foam using a very reactive recipe. ON-PUR was synthesized by mixing polyol, water, additives, and pol…
Transcrystallization of isotactic polypropylene (iPP) on different fibers (carbon fiber, glass fiber, and aramid fiber) was conducted in a temperature gradient. The Ultra-High-Module carbon fiber (UHMCF), the High-Module carbon fiber, and the aramid fiber (Twaron) showed sufficient nucleation ability to form transcrys…
High cell density fed-batch fermentation of Alcaligenes eutrophus was carried out for the production of poly(3-hydroxybutyrate) (PHB) in a 60-L fermentor. During the fermentation, pH was controlled with NH(4)OH solution and PHB accumulation was induced by phosphate limitation instead of nitrogen limitation. The glucos…
An infinite, one-dimensional chelating ligand [P3Se] is present in K3RuP5Se10 (depicted on the right), which was obtained by the reaction of ruthenium with a molten mixture of nominal stoichiometry K3P6Se26.5 at 490°C. K3RuP5Se10 is the first structurally characterized ruthenium chalcophosphate, and features very shor…
Reversible CC bond breaking/making as well as drastic change in color are induced upon electron transfer in the novel redox couples of hexaarylethanes 1 and bis(triarylmethyl) dications 22+. Their hysteretic redox behaviors result from the quite different geometries of 1 and 22+. Ar = p-Me2NC6H4, p-MeOC6H4.
The linear FeOFe bridge in μ-oxo tetraphenylporphyrin iron(III) dimer can be protonated without structural rehybridization at the O atom (the structure of the μ-hydroxo-bridged complex is depicted on the right). Antiferromagnetic coupling between the iron centers is greatly attenuated, and proton self-exchange is sl…
Resonant Raman and nuclear magnetic resonance spectroscopies from single gallium arsenide quantum dots are demonstrated. The nuclei were probed through changes in the optical spectra of the quantum dot exciton arising from exciton-nuclear interactions. This approach allowed the application of optical spectroscopy with…