Materials Literature
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Experimental techniques for studying the behaviour of water in confined geometry using neutron scattering and NMR methods are reviewed. A brief survey is given of earlier work on sol–gel silicas and these findings are updated by reference to current work on MCM- and SBA-type silicas. Particular attention is focused on…
In contrast to non-associating liquids such as oils or organic solvents, whose viscosity diverges when they are confined by solid surfaces to films thinner than about ten molecular diameters, recent studies reveal that salt-free water remains fluid, with a viscosity close to its bulk value, even when confined to films…
Characterization of palladium catalysts, supported on alumina and alumina modified by zirconia added by impregnation, was performed by CO adsorption from 143 to 298 K and monitored by infrared spectroscopy. It was found that the population of the Al3+ octahedral sites in the alumina decreased by the addition of zircon…
We review our incoherent quasielastic neutron scattering (QENS) studies of the dynamics of supercooled water confined in nanoporous silica materials. QENS data were analysed by using the relaxing cage model (RCM) previously developed by us. We first use molecular dynamics (MD) simulation of the extended simple point c…
Molecular imaging is a powerful tool that has the ability to elucidate biochemical mechanisms and signal the early onset of disease. Overexpression of the peripheral benzodiazepine receptor (PBR) has been observed in a variety disease states, including glioblastoma, breast cancer, and Alzheimer's disease. Thus, the PB…
The molecular weight dependence of the fast dynamics, sound velocity, and fragility has been studied for polystyrene (PS) and polyisobutylene (PIB). These different physical properties vary with molecular weight ( M n ) and level off near the same chain length where T g becomes independent of M n . The latter differs…
A layer-by-layer thin film composed of avidin and 2-iminobiotin-labeled poly(ethyleneimine) (ib-PEI) was prepared and their sensitivity to the environmental pH and biotin was studied. The avidin/ib-PEI multilayer assemblies were stable at pH 8-12, whereas the assemblies were decomposed at pH 5-6 due to the low affinit…
A novel photosensitive octacinnamamidophenyl polyhedral oligomeric silsesquioxane (OcapPOSS) was synthesized via the reaction between cinnamoyl chloride and octaaminophenyl polyhedral oligomeric silsesquioxane (OapPOSS). The photosensitive OapPOSS was characterized by Fourier transform infrared (FTIR), nuclear magneti…
Co nanowire arrays have been electrodeposited into self-assembled anodic aluminium oxide templates. It is found that the crystal structure of the Co nanowires depends on the pH value of the deposition electrolyte. The XRD results show that Co nanowires are fcc structure at pH = 2.7, amixture of structures of fcc and h…
The dimensionality of a system largely determines the nature of any long range order that is possible in the solid phase. For this reason considerable effort has been directed towards elucidating the behaviour of materials under confinement and at interfaces. This has ranged from theoretical studies that predict that…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTNanostructures of n-Type Organic Semiconductor in a p-Type Matrix via Self-Assembly of Block CopolymersStefan M. Lindner and Mukundan ThelakkatView Author Information Makromolekulare Chemie I, Universität Bayreuth, Universitätsstras…
An in situ ring-opening polymerization strategy was employed to grow multihydroxyl dendritic macromolecules on the convex surfaces of multiwalled carbon nanotubes (MWNTs), affording novel one-dimensional (1D) molecular nanocomposites. The crude MWNTs were oxidized using 60% HNO 3 and then reacted with thionyl chloride…
We demonstrate a tomographic method for determining the degree of ellipticity and the orientation of a gold nanoparticle. To do this, we attach a single nanoparticle to the end of a sharp glass fiber tip and record its plasmon spectra for different incident polarizations and angles of incidence. Our measurements allow…
Although the interest in half-metallic Heusler alloys, likely to be usable in spintronic applications, has grown considerably, their interfaces with semiconductors show very low spin polarization. I identify mechanisms which can keep high spin polarization at the interface (more than 80% of the electrons at the Fermi…
Magnetic and electrical properties of four series of rare earth cobaltates of the formula La 0.7− x Ln x Ca 0.3 CoO 3 with Ln = Pr, Nd, Gd and Dy have been investigated. Compositions close to x = 0.0 contain large ferromagnetic clusters or domains, and show Brillouin-like behaviour of the field-cooled DC magnetization…
Density functional theory (DFT) is used to study vibrations, electrical dipole moments, and polarizabilities of NaF clusters. Because of prior experimental and theoretical studies, this is a good model system for tracking the evolution of the properties from diatomic molecule to bulk crystal. The ratio of vibrational…
Here I present an overview of recent studies of the phenomenon of negative refraction and left-handed materials. I will discuss some basic questions pertinent to the problem. It is pointed out that the current claims of negative refraction and left handed materials are not conclusive. To support our consideration, I w…
In a recent communication, Parimi et al. (Nature 426, 404 (2003)) reported the experimental results on imaging by a flat lens made of photonic crystals. They attributed the observed focusing to the negative refraction expected for the Left-Handed-Materials (LHMs). Here we demonstrate that the experimental observation…
We have investigated reversible single-wall carbon nanotube (SWNT) oxidation by quantitative analysis of the oxide-induced absorption bleaching and luminescence quenching at low pH. These data, in combination with DFT structure calculations, suggest that the nanotube oxide is a 1,4-endoperoxide. At low pH, the endoper…
Curves of the crack growth resistance parameters K R , J R and R as a function of crack length were obtained for IM1-24 nuclear grade graphite subject to oxidation in CO 2 at 900°C up to 20% burn-off. For the unoxidized graphite, the curves show three regions: (i) an initial rise attributed to the development of bridg…