Materials Literature
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The synthesis and characterization of a noncentrosymmetric tellurium selenate, Te 2 SeO 7, is reported. In addition, the powder second-harmonic-generating (SHG) properties of TeO 2, Te 2 SeO 7, Te 2 O 5, and TeSeO 4 have been measured, using 1064 nm radiation. Through the powder SHG experiments, we are able to determi…
(Nano)composites based on ethylene vinyl acetate copolymers (EVA) and montmorillonite modified by various alkylammonium cations were processed by mechanical kneading. Polymer intercalation and filler exfoliation were evidenced by X-ray diffraction and transmission electron microscopy, respectively. Nanocomposites tens…
The BAB-type triblock copolymers composed of a central poly(ethylene oxide) (PEO, M̄nPEO = 1 000) block and two poly[(D,L-lactic acid)-co-(glycolic acid)] end blocks with molecular weights between 900 and 1 600 exhibited an interesting phase transition behavior. The copolymer aqueous solution can form micelles with PL…
In this work the use of high quality natural fibres as reinforcements was studied using the resin transfer moulding (RTM) processing technique. The fibres were unidirectional high quality Arctic Flax and the matrix was an epoxy resin. The mechanical properties of the composites were compared to conventional RTM manufa…
Spherical and polyhedral carbon onions prepared from diamond nanoparticles are investigated by high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and electron spin resonance (ESR). HRTEM and Raman studies show that, as a result of thermal annealing, diamond nanoparticles are transformed into…
Routine preparation of mesostructured nanoparticles (see Figure) at room temperature is possible using the simple quenching procedure presented here. Silica particles with mesostructured interiors and diameters as small as 15 nm can be synthesized as can organo-silica derivatives with chemically functionalized mesopor…
We have carried out systematic calculations for hydrogen-adsorption and -storage mechanism in carbon nanotubes at zero temperature. Hydrogen atoms first adsorb on the tube wall in an arch-type and zigzag-type up to a coverage of theta = 1.0 and are stored in the capillary as a form of H(2) molecule at higher coverages…
Zircon crystals were grown from a Li-Mo flux (7.5 mol% Li 2 MoO 4 ; 86.5 mol% MoO 3 ) to which equal molar proportions ZrO 2 and Li 2 SiO 3 were added (3 mol% each). The crystals were initially grown undoped, but later Dy was added to the flux without any other charge-compensating species. With Dy and P added, in equa…
The large shear displacements of atomic layers in Gd5(SixGe1–x)4 materials, coupled with the change of crystallographic symmetry and magnetic order, characterizes these transformations as magnetic–martensitic, which are extremely rare. The start and the end of the magnetic–martensitic transitions depends strongly on t…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTFabrication of Novel Mesocellular Carbon Foams with Uniform Ultralarge MesoporesJinwoo Lee, Kwonnam Sohn, and Taeghwan HyeonView Author Information School of Chemical Engineering and Institute of Chemical Processes Seoul National University, Seoul 151-742, Korea Cite t…
Nanosized α-nickel hydroxide with an interlayer spacing of 7.2 Å has been synthesized with the aid of ultrasound radiation. This method was found to be a simple and convenient method to produce α-nickel hydroxide. The synthesized hydroxide was found to possess good stability in KOH medium and the material might be int…
Material design of GaN-based ferromagnetic diluted magnetic semiconductors is given based on ab initio calculations within the local spin density approximation. The electronic structure of 3 d -transition-metal-atom-doped GaN was calculated by the Korringa-Kohn-Rostoker method combined with the coherent potential appr…
Nanoparticles assembled from poly( d, l -lactic acid)−poly(ethylene glycol) (PLA−PEG) block copolymers may have a therapeutic application in site-specific drug delivery. A series of AB block copolymers based on a fixed PEG block (5 kDa) and a varying PLA segment (2−110 kDa) have been synthesized by the ring-opening po…
Real-time measurements of stress evolution during the deposition of Volmer–Weber thin films reveal a complex interplay between mechanisms for stress generation and stress relaxation. We observed a generic stress evolution from compressive to tensile, then back to compressive stress as the film thickened, in amorphous…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTControlled Synthesis of Multi-armed CdS Nanorod Architectures Using Monosurfactant SystemYoung-wook Jun, Sang-Min Lee, Nam-Jung Kang, and Jinwoo CheonView Author Information Department of Chemistry and School of Molecular Science BK21, Korea Advanced Institute of Scien…
Not to be confused with semiconductors, half metals belong to a new class of materials that look set to play a key role in next-generation electronic devices.
Se ha extendido en la actualidad el uso de materiales compuestos formados por resinas poliméricas o plásticos, reforzados con fibras de vidrio. de carbono o fibras de aramida, que alcanzan grandes resistencias, del mismo orden que la de los aceros, con una densidad mucho menor, algo más que la de la madera.
A series of mixed-ligand complexes of the formulae [Co (tyr)(gly)(H2O)2], [Co(tyr)(ala)(H2O)2], [Co(tyr)(thr)(H2O)2], [Co(tyr)(met)(H2O)2],[Ni(tyr)(gly)(H2O)2], [Ni(tyr)(ala) (H2O)2] and [Ni(tyr)(thr)(H2O)2], where tyr = L-tyrosine, gly = glycine, ala = alanine, thr = threonine, met = L-methionine has been prepared an…
A pyrolysis route has been used to synthesize arrays of highly aligned BxCyNz nanotubes in bulk. The structure and composition of the product were characterized by scanning electron microscopy, high-resolution transmission electron microscopy, and electron energy-loss spectroscopy. The length and diameter of the nanot…
The exciton–erbium coupling and the excitation dynamics of Er3+ in erbium-doped silicon-rich silicon oxide are investigated using time-resolved measurements of Er3+ luminescence. The dependence of the Er3+ luminescence on the pump power and duration indicates that the exciton–erbium coupling is dominant over carrier–e…