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 report about the observation of intrinsic optical bistability of nanometer-size spherical CdS particles coated with silver. The particles were chemically prepared as isolated CdS clusters in aqueous suspensions and coated with silver by chemical reduction from added AgNO3. They exhibit intrinsic optical bistability…
Two different crystal forms of the 9 kDa protein of the signal recognition particle (SRP9) have been prepared by the hanging drop vapor diffusion technique using 28% (w/v) PEG8000 or 28% saturated ammonium sulphate as precipitant. The crystals are hexagonal bipyramids with average dimensions of 0.2 X 0.1 X 0.1 mm(3) a…
Polyaniline films prepared via the camphorsulphonic acid (CSA)m-cresol solution processing route have been synthesized with doping levels in the range of 10 - 90%. The electrical conductivity of these films has been measured as a function of temperature between 10 and 300 K. At a doping level of 30% the onset of metal…
The optical excitations in $\rug$ and higher fullerenes, including isomers of C$_{76}$, C$_{78}$, and C$_{84}$, are theoretically investigated. We use a tight binding model with long-range Coulomb interactions, treated by the Hartree-Fock and configuration-interaction methods. We find that the optical excitations in t…
Charge-transfer (CT) exciton effects are investigated for the optical absorption spectra of crosslinked C60 systems by using the intermediate exciton theory. We consider the C60-dimers, and the two (and three) molecule systems of the C60-polymers. We use a tight-binding model with long-range Coulomb interactions among…
Competition between the ferromagnetic double-exchange interaction and the antiferromagnetic charge-ordering instability gives rise to thermally as well as magnetic field (H) induced insulator-metal transitions in distorted perovskites $({\mathrm{Nd}}_{1\ensuremath{-}y}{\mathrm{Sm}}_{y}{)}_{1/2}{\mathrm{Sr}}_{1/2}{\mat…
The large-magnetoresistance compounds ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ have been studied using specific heat, sound velocity $(v)$, and electron diffraction. For $0.63\ensuremath{\le}x\ensuremath{\le}0.67$ charge ordering is observed at 260 K and accompanied by a dramatic $(>10%…
Transparent zinc oxide (ZnO) films has been cathodically deposited on conductive glasses from a simple aqueous zinc nitrate electrolyte kept at 335 K. ZnO films prepared had a wurtzite structure and exhibited an optical band gap energy of 3.3 eV which is characteristic of ZnO. A 2-μm-thick ZnO film with an optical tra…
The macroscopic four-wave mixing susceptibility is separated into a geometrical and a molecular factor using vector coupling algebra. The geometrical factor for isotropic samples is given explicitly for collinear circularly polarized beams and for an arbitrary geometry of linearly polarized beams. The result for four…
We examine sequences of dense packings of $n$ congruent non-overlapping disks inside a square which follow specific patterns as $n$ increases along certain values, $n = n(1), n(2),... n(k),...$. Extending and improving previous work of Nurmela and Östergård where previous patterns for $n = n(k)$ of the form $ k^2$, $…
Alcaligenes latus, a growth-associated PHB producer, was cultivated by a pH-stat modal fed-batch culture technique to attain high PHB productivity. Both sucrose solution and inorganic medium were fed in conjunction with the supply of ammonia solution which serves as a nitrogen source and as a means of pH control. Comp…
Molecular sieves from a building kit?! Gallium siloxanes of the type shown (substituents on the Si and Ga atoms have been omitted for clarity), which have been synthesized and structurally characterized for the first time, add to the number of molecules that can be considered for the directed synthesis of zeolite-like…
Scanning tunneling microscope (STM)-induced selective bond breaking in individual molecules and conventional STM imaging are combined to determine the nature of chemisorbed O 2 species formed during the initial stages of silicon (111)-(7×7) oxidation. A selective atomic-scale modification mechanism that involves disso…
Fast and efficient—energy is transferred within a supramolecular system from the light-harvesting aggregate of zinc chlorins to the coaggregated metal-free bacteriochlorin chromophore (see schematic representation below). This is a first example of a self-assembled light-harvesting antenna that efficiently transfers l…
Some materials exhibit large changes in electrical resistance in the presence of a magnetic field, and this change can be used in applications from sensor technology to magnetic data storage. In their Perspective, Rao and Cheetham discuss magnetoresistance in perovskite manganates, where the effect is unusually strong…
Subpicosecond photoexcitation of CdS/HgS/CdS quantum dot quantum well nanoparticles at wavelengths shorter than their interband absorption (390 nm) leads to a photobleach spectrum at longer wavelengths (440−740 nm). The photobleach spectrum changes and its maximum red-shifts with delay time. These results are explaine…
In this work, the critical temperature (Tc) of a series of polymeric superconducting systems is determined which, sintered or not, are obtained through the incorporation of the superconducting ceramic YBaCuO into two extrinsic conducting polymer systems: PVDF/PS/carbon black and PVDF/PS/copper. In addition, the diamag…
CF 4 and O 2 glow discharge treatment of biaxially oriented polypropylene film results in the surface incorporation of fluorine and oxygen atoms, respectively, together with an increase in surface roughness. The stability and extent of substrate modification have been investigated by X-ray photoelectron spectroscopy (…
The boron-substituted MCM-41 was hydrothermally synthesized using Na 2 B 4 O 7 and H 3 BO 3 as boron sources. The influence of the nature of the boron source on the textural properties as well as the stability of MCM-41 structure and the state of boron upon different procedures such as NH 3 treatment, ion-exchange, an…
Graft polymerizations of methyl acrylate (MA) onto granular cornstarch were carried out in water with both ferrous ammonium sulfate/hydrogen peroxide (FAS/H2O2) and ceric ammonium nitrate (CAN) initiation. Starch concentrations were 10, 20, and 30% in water, and the amount of MA used was either 0.5, 1, or 2 mol per AG…