Materials Literature
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We have studied the thickness dependence of the magnetotransport properties of ${\mathrm{La}}_{2/3}{\mathrm{Ca}}_{1/3}{\mathrm{MnO}}_{3}$ thin films epitaxially grown on ${\mathrm{SrTiO}}_{3},$ ${\mathrm{LaAlO}}_{3},$ and ${\mathrm{NdGaO}}_{3}$ single-crystalline substrates. When thickness decreases, a global disrupti…
Abstract The effect of the chain constraint on the glass‐transition temperature of polystyrene (pS) was studied in the context of polymer tethering to curved surfaces. The synthesis and characterization of silica‐ graft ‐polystyrene (SiO 2 ‐ g ‐pS) hybrid nanoparticles is reported. Silica nanoparticles possessing cova…
The approaches that form the basis of automated structure solution in SOLVE and RESOLVE are described. The use of a scoring scheme to convert decision making in macromolecular structure solution to an optimization problem has proven very useful and in many cases a single clear heavy-atom solution can be obtained and u…
Abstract The morphologies and crystalline structures of melt‐crystallized ultrathin isotactic poly(1‐butene) films have been studied with transmission electron microscopy and electron diffraction. It is demonstrated that a bypass of form II crystallization can be achieved with an increase in its crystallization temper…
The magnetization of an ensemble of isolated lead grains of sizes ranging from below 6 nm to 1000 nm is measured. A sharp disappearance of Meissner effect with lowering of the grain size is observed for the smaller grains. This is a direct observation by magnetization measurement of the occurrence of a critical partic…
The World Wide Web (WWW) is a wonderful tool to provide users with documentation and tools that make the preparation and running of an experiment a little easier. We present a set of tools that allow one to estimate the activation of a sample in the neutron beam, or to calculate the absorption of a sample. Ever tried…
MX is a portable beamline control system that has been described at previous NOBUGS meetings. This talk will briefly review MX and then discuss important changes and improvements made since the last meeting in 2000. For materials science, work has focused on extending the support for multichannel analyzers and for fas…
The development of control software for a neutron powder diffraction instrument at the Safari-1 research reactor of South Africa is reported. The software runs under Windows 2000 and incorporates PC-based cards for data acquisition and motion control. It has the capability to collect data from multiple detectors and c…
This new package will provide easy-to-use access to crystallographic structure solution, model building and structure analysis. It will be possible for any developer to integrate scientific software into the system.
A detailed analysis of the formation energies for alkali, earth-alkali, and transition-metal hydrides is presented. The hydriding energies are computed for various crystal structures using density functional theory. The early transition metals are found to have a strong tendency for hydride formation which decreases a…
Abstract Organically modified montmorillonite was synthesized with a novel 1,2‐dimethyl‐3‐ N ‐alkyl imidazolium salt or a typical quaternary ammonium salt as a control. Poly(ethylene terephthalate) montmorillonite clay nanocomposites were compounded via melt‐blending in a corotating mini twin‐screw extruder operating…
The field emission of individual multiwall carbon nanotubes grown by chemical vapor deposition was measured in a scanning electron microscope. By using a sharp anode, we were able to select one nanotube for measurements in carefully controlled conditions. Single nanotubes follow the Fowler-Nordheim law, and the depend…
Structural genomics seeks to expand rapidly the number of protein structures in order to extract the maximum amount of information from genomic sequence databases. The advent of several large-scale projects worldwide leads to many new challenges in the field of crystallographic macromolecular structure determination.…
Transparent sols of crystalline gadolinium doped zirconia particles with the general formula Zr 1 - x Gd x O 2 - x/2 (where x = 0–0.20), were prepared by a hydrothermal sol-gel method using cheap inorganic precursors. The composition, structure, crystallite size and lattice parameters of the crystalline dried sol part…
An urgent worldwide problem in the field of environment protection is the development of energy saving and highly efficient technologies for removal of volatile organic compounds (VOCs) from gas emissions of large volume and emitted at rather low temperatures, such as low concentrated ventilation exhausts at room temp…
The new generation of dedicated Engineering Strain Scanners at neutron facilities such as ENGIN-X at ISIS and SMARTS at LANSCE offer considerable increases in both the throughput of samples and the density of measurements which are feasible within each sample. This trend is set to increase further with new neutron sou…
The NeXus format allows the storage of measured data next to a description of sample and instrument setup in a standardized manner. The NeXus standard itself gives only general rules how an instrument setup is described. A so called instrument definition contains a minimal set of information and the location of that i…
Simultaneous studies on the magnetic and electrotransport properties of Nd_{0.67} Sr_{0.33} Mn_{1-x} Fe_x O_3 polycrystalline bulk and epitaxial thin films (x = 0.00 and 0.05) have been carried out. A magnetoresistance (MR) as high as ~ 33% is observed for Nd_{0.67} Sr_{0.33} MnO_3 bulk at the metal-insulator transiti…
The thermal decomposition of Şaphane alunite from Kütahya, Turkey, has been studied using ambient- and high-temperature X-ray diffraction analysis, differential thermal analysis, and thermogravimetric analysis. The alunite content in the ore was about 47.5%. The first endothermic peak at about 545 °C is due to the deh…
Single crystals of CsCdCl3, CsCdBr3, CsMgBr3, and MgBr2 doped with 0.1/5% Ni2+ were grown by the Bridgman technique and studied by variable-temperature optical absorption and luminescence spectroscopies. At cryogenic temperatures all these systems are dual emitters; i.e., they emit light from two distinct, thermally n…