Materials Literature
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An acoustic attenuation spectroscopy as a powerful technique is used to study the relaxation processes in phosphate glasses containing Cu+ conductive ions of the system CuI-CuBr-Cu2O-P2O5 with respect to ion transport mechanisms. The acoustic attenuation spectra exhibit several distinctive peaks, corresponding to tran…
Photoluminescent fibers with a sheath-core morphology are produced to impart good mechanical properties. Both photoluminescent and mechanical properties are examined for these fibers with respect to photoluminescent pigment concentrations in the core, draw ratios, and polymer types. The photoluminescent pigment concen…
The crystal structure of the beryllium-rich cordierite [(Na0.28Ca0.19)(H2O)0.92](Mg1.86Fe 0.14 22− ) · { Al3.39Be0.61Si5O18} was established by X-ray diffraction analysis (IPDS Stoe diffractometer, λMoKα radiation, graphite monochromator, 2θmax = 65°, R = 0.0186 for 1378 reflections): a = 16.850(3), b = 9.729(2), and…
Abstract The precipitation and deposition of calcium sulfate dihydrate (gypsum) on brass heat exchanger surfaces from aqueous solutions has been studied using a highly reproducible technique. It has been found that gypsum scale formation takes place directly on the surface of the heat exchanger without any bulk or spo…
In this study, we examine, in detail, the synthesis of single wall carbon nanotubes (C-SWNTs) with a plasma torch, using molecular sources for both carbon and catalyst (typically a carbon-containing gas such as ethylene and ferrocene for the metal catalyst). A comparison of the results obtained by Raman spectroscopy,…
Oxygen-deficient La 0.67 Sr 0.33 MnO 3−α solid solutions have been studied. A comparison is made with the results obtained in an earlier study of a similar lanthanum-calcium manganite series. The physical characteristics of both series are accounted for as being due to a change in the Mn 3+ /Mn 4+ ratio caused by oxyg…
Abstract. Small Angle X-ray Scattering (SAXS) experiments together with crystallization experiments have shown the importance of studying macromolecular associations and interactions involved in nucleation and crystal growth mechanisms. In the study by SAXS of Bovine pancreatic trypsin inhibitor (BPTI) and Aspergillus…
Abstract Quasi-one dimensional (1D) conductors of the TTF-TCNQ family of charge transfer salts exhibit a Peierls transition which stabilizes a periodic lattice distortion (PLD), accompanied by a charge density wave (CDW) modulation, with an incommensurate 2 k F (and sometimes 4 k F ) wave vector related to the band fi…
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 water soluble porogen, e.g., poly(amido amine) dendrimer, has been used as a structure-directing agent to introduce porosity of nanometer scale in silica-based nanocomposite materials. Hydrothermal synthesis was carried out at different elevated temperatures (343-413 K) in a closed teflon-lined stainless steel autoc…
The electrical resistivity of single crystal α-MnS in crystallographic directions [111] and [100] was found to be anisotropic in the temperature interval 77–300 K. The change in activation energy below the Néel temperature was determined. Magnetoresistance was revealed, and reversal of its sign in the (111) plane abov…
Oxidation studies of martensitic/ferritic and austenitic steels have been conducted in static lead bismuth eutectic (LBE). Samples were preoxidized in an air/H2O gas mixture prior to immersion in LBE. Preoxidation films grown on HT-9 at 800°C for 48 h had a bilayer structure, an outer Fe-rich layer, and an inner Cr-ri…
Studies of the specific heat and simultaneous AC magnetic susceptibility ( ) and electric resistance of stoichiometric magnetite single crystal are presented. The temperature hysteresis of the Verwey transition is of 0.03 K found from the specific heat data confirming its first-order character. The continuous temporal…
In this work, we studied the electron beam scattering due to the introduction of two gases : water vapour and helium within the specimen chamber of the Environmental Scanning Electron Microscope (ESEM) and the effects of this phenomenon on the image quality and on the microanalysis results. An increase in the pressure…
A chemical investigation of the roots of Cynanchum stauntonii has resulted in the characterization of a new hydroperoxide with a 13,14 : 14,15-disecopregnane-type skeleton, named stauntonine (1), together with three related compounds, anhydrohirundigenin (2), anhydrohirundigenin monothevetoside (3), and glaucogenin-C…
The surface morphology of the {100} face growth hillock of potassium dihydrogen phosphate (KDP) is examined through first-principles calculations and using periodic-bonded-chain (PBC) theory. KDP, or archerite ([K, NH 4 ]H 2 PO 4 ), is used extensively in industry and is an excellent model for more complicated materia…
Different attractive interacting colloidal systems are characterized by means of static light scattering. As most of these samples are rather concentrated, multiple scattering is suppressed by partial contrast match and the use of very a thin sample cell (13 μm). This is possible with the laboratory built flat cell li…
Dynamic light scattering (DLS) is a well-known noninvasive technique for investigating interactions of protein molecules in solution. Unfortunately, DLS is not very sensitive to small size changes because covariables, such as temperature, viscosity, and refractive index, are not precisely known, or they vary as functi…
The effects of gravity on the crystallization of ZrF(4)-BaF(2)-LaF(3)-AlF(3)-NaF glasses have been studied using the NASA KC-135 and a sounding rocket. Fibers and cylinders of ZBLAN glass were heated to the crystallization temperature in unit and reduced gravity. When processed in unit gravity the glass crystallized,…
Transposed-temperature, drop-calorimetry measurements were performed in the systems Na 2 SiO 3 - Fe 2 O 3 -SiO 2 and Na 2 SiO 3 -NaFeSi 2 O 6 at 1373 K to investigate thermodynamic properties of Fe 3+ -bearing silicate liquids. The results confirm previously measured enthalpy of Na 2 SiO 3 and SiO 2 melts. No signific…