Materials Literature
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The equation of state of anatase ${\mathrm{TiO}}_{2}$ has been determined experimentally---using polycrystalline as well as single-crystal material---and compared with theoretical calculations using the ab initio perturbed ion model. The results are highly consistent, the zero-pressure bulk modulus being 179(2) GPa fr…
Polycrystalline samples of clathrate compounds Ba8Ga16Si30, Ba8Ga16Ge30, Ba8Ga16Sn30, and Sr8Ga16Ge30 were prepared by direct melting and characterized using X-ray powder diffraction and differential thermal analysis. The Ge- and Si-based clathrates melt congruently, whereas Ba8Ga16Sn30 melts incongruently. At room te…
A series of wholly aromatic hyperbranched polyimides were successfully prepared by condensation polymerization of a triamine monomer, tris(4-aminophenyl)amine (TAPA), and a series of commercially available dianhydride monomers such as 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), 3,3‘,4,4‘-diphenyl…
Electric resistivity, thermoelectric power and thermal conductivity of a polycrystalline sample of the composite crystal [Ca 2 CoO 3.34 ] 0.614 [CoO 2 ], also known as Ca 3 Co 4 O 9 , have been measured below 300 K. Metallic conductivity accompanied by large thermoelectric power has been observed down to 50 K. At 300…
Macroporous metals with strong diffractive properties at visible wavelengths can be synthesized from colloidal crystal templates. The synthesis, characterization, and potential applications of macroporous metals created in this manner are summarized in this article. The Figure shows a macroporous copper film, illustra…
A procedure is described, for an Eulerian or Kappa goniostat, to determine the exact spindle value φ at the moment of impact of a reflection on an area detector; such information is essential for the calculation of accurate reflection vectors and, eventually, the unit-cell and lattice orientation. The method is based…
Submicrometer hollow spheres of CdSare produced here (see Figure) in a one-pot in-situ source–template–interface reaction (ISTIR)—thus named because CS2 plays both the role of sulfur source and template and the main reaction region is at the CS2–water interface. Examination of the photoluminescence spectrum of these s…
The possibility of modifying the electronic properties of nanotubes using gas molecule adsorption is investigated using the first-principles total energy density functional calculations. Detailed analysis of the electronic structures and energetics is performed for the semiconducting (10,0) single-walled carbon nanotu…
This is a report regarding the preparation of nanosized gold/palladium bimetallic particles utilizing a cavitation phenomenon induced by irradiation of high-intensity ultrasound in an aqueous solution of gold(III) and palladium(II) ions. The particles are found to be composed of gold-core and palladium-shell by a tran…
Engineering ceramics in the system Si–O–C–N–B manufactured from preceramic silicon containing polymers gain in significance with increasing availability of advanced precursor materials such as poly(carbosilane), -(silazane), -(siloxane) or -(borosilazane). While high temperature resistant Si–C and Si–N ceramic fibers…
A distribution of crystallite size reduces the width of a powder diffraction line profile, relative to that for a single crystallite, and lengthens its tails. It is shown that estimates of size from the integral breadth or Fourier methods differ from the arithmetic mean of the distribution by an amount which depends o…
For a lamella-forming poly(ethylene oxide)- block -polystyrene (PEO- b -PS) diblock copolymer ( M̄ n PEO = 8.7K and M̄ n PS = 9.2K), the glass transition temperature of the PS blocks is 62 °C, and the melting temperature of the PEO crystals is around 51 °C when the sample is crystallized below 40 °C. The PEO blocks th…
Bio- and chemical sensing, biomaterials, and in vivo electronics are some of the latest advances for porous silicon (p-Si) discussed in this review. p-Si is extremely versatile owing largely to its well-known luminescence properties (the Figure shows photoluminescence from patterned p-Si), high surface area, and facil…
Hundreds of acetyltransferases exist. All use a common acetyl donor--acetyl coenzyme A--and each exhibits remarkable specificity for acetyl acceptors, which include small molecules and proteins. Analysis of the primary sequences of these enzymes indicates that they can be sorted into several superfamilies. This review…
Techniques and methods to facilitate the solution of structures by simulated annealing have been developed from the starting point of a space group and lattice parameters. The simulated-annealing control parameters have been systematically investigated and optimum values characterized and determined. Most significant…
Polymers filled with low amounts of layered silicate dispersed at nanoscale level are most promising materials characterized by a combination of chemical, physical and mechanical properties that cannot be obtained with macro- or microscopic dispersions of inorganic fillers. Polymer layered silicate nanocomposites can…
Ordered nanoporous films have been generated via selective degradation of self-assembled block copolymer films of polystyrene (PS) and poly(methylmethacrylate) (PMMA), which contain oriented cylindrical microdomains. Deep UV irradiation degrades the PMMA, which can be rinsed away, leaving an ordered array of circular…
Functionalizing the termini of low-molecular-weight telechelic polymers with strongly associating hydrogen bonding units (see Figure) results in a new set of supramolecular materials, as reported here. These materials possess the unique combination of polymer-like properties at room temperature and monomer-like proper…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTStrong Luminescence of Solubilized Carbon NanotubesJason E. Riggs, Zhixin Guo, David L. Carroll, and Ya-Ping SunView Author Information Department of Chemistry and Center for Advanced Engineering Fibers and Films Howard L. Hunter Chemistry Laboratory Department of Phys…
Abstract Summary: DaliLite is a program for pairwise structure comparison and for structure database searching. It is a standalone version of the search engine of the popular Dali server. A web interface is provided to view the results, multiple alignments and 3D superimpositions of structures. Availability: DaliLite…