Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
We have found that liquid crystals can be aligned on a polyimide surface exposed to a low energy and neutral argon ion beam. The energy of the incident ions was varied between 75 eV and 500 eV, the integrated current density from 20 µA/cm 2 to 500 µA/cm 2 , and the angle of incidence over which alignment was measured…
The size and excitation dependence of resonant low-frequency Raman scattering in CdS nanocrystals (radii less than 10 nm) embedded in a glassy matrix have been investigated. We report a size-selective excitation for excitations inside the absorption features. The Raman spectra exhibit a different behavior when the exc…
Carbon nanotubes were produced in large amounts by catalytic decomposition of acetylene over a Co incorporated zeolite NaY support. Purification of multi-wall nanotubes was required in order to eliminate catalyst and amorphous carbon produced by thermal decomposition of hydrocarbon. First, separation of nanotubes and…
Ti-MCM-41 materials with methylated silicons have been prepared in one step synthesis; the resultant organic–inorganic composites are highly stable and present the highest activity and selectivity ever reported on Ti containing mesoporous catalysts for the epoxidation of olefins using organic peroxides.
A solvothermal reaction of metal oxalates such as PbC2O4 , Bi2(C2O4)3 with E (E=S, Se, Te) in organic solvents at relatively low temperature (120–160 °C) produces crystalline PbS, PbSe, PbTe, Bi2S3 , Bi2Se3 , and Bi2Te3 :PbC2O4+Esolvent
The layered hydrotalcite, Mg10Al2(OH)24CO3, acts as an efficient base catalyst for the epoxidation of various olefins using hydrogen peroxide in the presence of benzonitrile and with MeOH as solvent.
Abstract Thin (0.5–5‐ μm) palladium (Pd) membranes were prepared inside pores or on the suface of mesoporous (pore size 4–6 nm), sol – gel‐derived γ‐Al 2 O 3 supports by the chemical vapor deposition (CVD) method using palladium acetylacetonate and palladium chloride (together with hydrogen) as Pd precursors. When Pd…
Al2O3 fibers for strengthening of high-temperature composites have been grown by a simple method that uses cheap, readily available raw materials and relatively low temperatures. The fibers are characterized and the mechanism of growth discussed. The Figure shows a characteristic fiber ending drop, which indicates tha…
Different novel nanostructures of gold–polypyrrole composites are observed by the transmission electron microscopy, for the first time, with the advent of block copolymer micelles.
Catalyst (copper-coated zeolite catalyst, i.e., Cu-ZSM-5) was used to enhance NO/sub x/ removal plasma chemical reactions. Two kinds of hydrocarbons (2-propane-1-ol, 2-propanol) were added to the synthesized flue gas before the nonthermal plasma process, and their effects on NO/sub x/ removal characteristics were inve…
The first example of a mesostructured tin oxide that is stable to surfactant removal has been prepared by hydrolysis of tin isopropoxide in the presence of a neutral amine surfactant (tetradecylamine).
Numerous reports have been published in the literature which describe the crystallization of macromolecules by a variety of crystallization methods, including the vapour-diffusion and microbatch techniques. This topical review compares the results of examples of proteins which were crystallized by both vapour-diffusio…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTA General Synthesis of End-Functionalized Oligoanilines via Palladium-Catalyzed AminationRobert A. Singer, Joseph P. Sadighi, and Stephen L. BuchwaldView Author Information Department of Chemistry Massachusetts Institute of Technology Cambridge, Massachusetts 02139 Cit…
Zwitterionic metallocenes are a subclass of olefin polymerization catalysts which offer several potential advantages over nonzwitterionic analogues. They may be classified by the location of the counteranion within the structure of the metallocene (right). The concepts involved in the synthetic approaches taken to the…
Single-wall and multiwall carbon nanotubes are currently the subject of an intense research effort owing to the outstanding properties they may possess. Many synthesis methods have been proposed, most of which involve nanometric metal particles. In this article the various mechanisms proposed for nanotube nucleation a…
4 pages, 2 figures
The recently developed, novel superhard nanocrystalline composites nc-TiN/a-Si3N4 have been investigated by means of high resolution transmission electron microscopy. The microstructure consisting of nanocrystalline TiN imbedded within a⩽1 nm thin amorphous Si3N4, the relative amount of both phases, and the TiN-crysta…
The co-condensation of tetraethoxysilane (TEOS) and organotrialkoxysilane [(RO)3SiR′] assembled in the presence of structure-directing non-ionic polyethyleneoxide surfactant micelles provides a convenient neutral pH synthesis methodology for the one-step preparation of organically functionalized mesostructured materia…
Nonracemic helicene 1 when cooled from the melt organizes itself into macroscopic liquid crystalline fibers. Transmission electron microscopic analysis shows that the fibers are comprised of lamellae 50−200 nm wide, each only ca. 10 nm high. Analyses by X-ray and electron diffraction demonstrate that the molecules are…
The incorporation of 1.0–5.0 mol% Ce3+ or La3+ ions in MSU-X alumina molecular sieves, prepared through an N○I○ assembly pathway, dramatically improves their thermal stability without altering the mesopore size or the wormhole channel motif.