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。
In this paper we present the synthesis and characterization of the so far largest polycyclic aromatic hydrocarbon (PAH), containing 222 carbon atoms or 37 separate benzene units. First a suitable three-dimensional oligophenylene precursor molecule is built up by a sequence of Diels-Alder and cyclotrimerization reactio…
PURPOSE: Preclinical studies have shown good anticancer activity following targeting of a polymer bearing doxorubicin with galactosamine (PK2) to the liver. The present phase I study was devised to determine the toxicity, pharmacokinetic profile, and targeting capability of PK2. PATIENTS AND METHODS: Doxorubicin was l…
Electrical conductivity and dielectric measurements have been performed for nanocrystalline NiFe 2 O 4 spinel for four different average grain sizes, ranging from 8 to 97 nm. The activation energy for the grain and grain boundary conduction and its variation with grain size have been reported in this paper. The conduc…
Structural evidence for the Gillard mechanism of covalent hydrates is provided by two mixed-valence CuI/CuII complexes containing 2,2′-bipyridine (see picture) or 1,10-phenanthroline ligands, in which a hydroxy group is added to a carbon atom adjacent to a nitrogen atom. These complexes are synthesized by hydrothermal…
In situ transmission electron microscopy is used to obtain atom-resolved images of copper nanocrystals on different supports. These are catalysts for methanol synthesis and hydrocarbon conversion processes for fuel cells. The nanocrystals undergo dynamic reversible shape changes in response to changes in the gaseous e…
Carrier generation layer samples representative of layered photoreceptors consisting of carrier generation materials (CGM), carrier transport materials (CTM), and binder resin were prepared by the wet-coating technique. The samples were analyzed in terms of the CTM reaction species, the morphology of molecular contact…
Abstract Polyester powder coatings have been used for many years on architectural products, such as aluminium window trim. This study investigates the degradation mechanism of naturally weathered coatings that have been exposed to aggressive climatic conditions, including high ultraviolet radiation and coastal atmosph…
Using various ultraviolet laser excitation lines between 199.8 nm (50 034 cm -1 ) and 266 nm (37 583 cm -1 ), emission transitions have been observed and assigned for the first time from the 3 P 2 term of Tm 3+, located near 37 500 cm -1 . The most intense transitions are to the terminal 3 H 6 and 3 F 4 states, and ar…
Abstract A series of oligomeric, hydroxy‐terminated silarylene–siloxane prepolymers of various lengths were prepared via dehydrogenative coupling between 1,4‐bis(dimethylsilyl)benzene [H(CH 3 ) 2 SiC 6 H 4 Si(CH 3 ) 2 H] and excess 1,4‐bis(hydroxydimethylsilyl)benzene [HO(CH 3 ) 2 SiC 6 H 4 Si(CH 3 ) 2 OH] in the pres…
The factors that govern the materials chemistry of a variety of new catalysts are identified and illustrated. Prominence is given mainly to nanoporous (and some nanoparticle) catalysts, which are of high relevance in ‘clean’ technology and ‘green’ chemistry. In particular, molecular sieve catalysts for the regioselect…
The structures of an optically isotropic cubic phase and a bluish colored phase exhibited in an (R,S) dichiral compound with fluorines have been investigated. Not only the bluish colored phase but also the cubic phase exhibit circular dichroism, being confirmed to be chiral phases. Based on the analysis of several X-r…
We present a single-orbital double-exchange model, coupled with cooperative phonons (the so called breathing modes of the oxygen octahedra in manganites). The model is studied with Monte Carlo simulations. For a finite range of doping and coupling constants, a first-order metal-insulator phase transition is found, whi…
This communication describes scanning tunnelling microscopy investigations of the electronic properties of singlewalled carbon nanotubes (SWNTs). First, the unique relationship between the atomic structure and electronic properties of SWNTs is presented. Second, structural defects in nanotubes are addressed, and quant…
Highly saddle shaped iron(III) porphyrin complex 1 showing a novel spin crossover process between the S = 3/2 and S = 1/2 has been crystallographically analyzed at 298, 180, and 80 K. As the temperature is lowered, the lattice contraction has occurred specifically along the b-axis. Correspondingly, the iron-pyridine b…
Electrolysis of benzylthiocyanate, benzyl chloride, p-methylbenzyl chloride, p-methoxybenzyl chloride, or toluene in acetonitrile, at platinum electrodes in a two compartments cell divided by a glass-frit diaphragm, affords 2,6-dimethyl-4-arylpyridine-3,5-dicarbonitrile as major product.
We report on upconversion luminescence in ${\mathrm{Y}}_{3}{\mathrm{Ga}}_{5}{\mathrm{O}}_{12}$ codoped with ${\mathrm{Cr}}^{3+}$ and ${\mathrm{Yb}}^{3+}.$ This is, to our knowledge, the first upconversion process directly involving ${\mathrm{Cr}}^{3+}.$ At low temperature excitation around 10 314 ${\mathrm{cm}}^{\math…
In comparison with their symmetrical analogues, unsymmetrically substituted Cu-Salen complexes show mesophases with lowered melting points. For terminally substituted complexes, symmetrical ones (R(1) = R(2)) have only an S(A) phase, while for unsymmetrical alkoxy substitution a monotropic S(E) phase occurs and the me…
Two new A-type proanthocyanidins have been isolated from Ecdysanthera utilis and identified as epicatechin-(4beta-->8,2beta-->O-->7)-epicatechin-(4beta-->8)-epicatechin (5) and epicatechin-(4beta-->8)-epicatechin-(4beta-->8,2beta-->O-->7)-epicatechin-(4beta-->8)-epicatechin (6), respectively. The structure-related com…
The preparation and crystal structure determination of the iron(III) compound of formula [(NH(4))(2)[Fe(2)O(ox)(2)Cl(2)].2H(2)O](n) (1) (ox = oxalate dianion) are reported here. Complex 1 crystallizes in the orthorhombic system, space group Fdd2, with a = 14.956(7) A, b = 23.671(9) A, c = 9.026(4) A, and Z = 8. The st…
Manuscript received: 2 January 2002. Final version: 4 February 2002.