Materials Literature
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Abstract Any simultaneous interpenetrating network (SIN) synthesis contains three key events. These are gelation of polymer I, gelation of polymer II, and phase separation of polymer I from polymer II. Metastable phase diagrams of SINs are developed, in which the time occurrence of these three events is represented. A…
The influence of multiple-scattering contributions in the X-ray absorption fine structure (XAFS) above the iridium L III edge is discussed for the iridium oxide IrO 2 . It is shown that multiple scattering in the IrO 6 cluster cannot explain the occurrence of some features, as previously proposed by comparing with rhe…
In this letter we report a nanoparticle-derived route to CdTe thin films. CdTe nanoparticles 39±8 Å in diameter, prepared by an organometallic route, were characterized by x-ray diffraction, UV-Vis spectroscopy, transmission electron microscopy, and energy dispersive x-ray spectroscopy. CdTe thin-film deposition was r…
Bright rings are observed in the scanning electron microscope (SEM) image when charge flashover in vacuum occurs on circularly bound polymethylmethacrylate surfaces using a SEM. The number and diameters of these rings vary with the applied observation voltage. These bright rings in the SEM correspond to the charge acc…
Planar metal–diamond–metal photoconductive devices have been fabricated from free standing large grain (20–30 μm) polycrystalline thin film diamond. An interdigitated electrode design with spacings of 20 μm was used to produce effective UV photodetecting devices at bias values in the range 0.1–10 V. A methane-air trea…
Using small angle neutron scattering techniques, we have determined the interfacial density profile of polyelectrolyte brushes. We show that in pure water the density profile has a Gaussian shape whose characteristic length appears to be a decreasing function of the grafting density. Upon the addition of salt, the lay…
We report the fabrication and characterization of zinc-indium-oxide films with similar electrical conductivity and better transparency in both the visible and infrared compared with indium–tin–oxide, a widely used transparent conductor in many technological applications. Dramatically superior transmission properties i…
A new aspect of the nature of the relaxation rate distribution of $\ensuremath{\alpha}$ relaxation in glasses is analyzed for the example of a polymer: How long does a polymer segment remember its relaxation rate? For a two-state system we describe the rate memory in terms of a single dimensionless parameter. Applying…
The metastable states of a glass are localized and counted by adding a weak pinning field that explicitly breaks the ergodicity. The entropy of the metastable states, that is, the logarithm of their number, is extensive in a range of temperatures ${T}_{s}<T<{T}_{c}$ only. It is argued that ${T}_{s}$ and ${T}_{c}…
The crystal structures and site populations of 8 calcic amphiboles from a leucogabbro from Punta Falcone, Sardinia, have been refined to R indices of similar to 2 % using single-crystal MoK alpha X-ray diffraction data. These amphiboles are unusual in that they show a significant degree of disorder of [4]-coordinated…
Abstract Monodisperse crosslinked polystyrene (PS) beads were prepared by a reaction of semibatch emulsion polymerization with styrene monomer, divinylbenzene (DVB) crosslinking agent, and potassium persulfate (K 2 S 2 O 8 ) initiator in the absence of emulsifier. The glass transition temperature ( T g ) and the mean…
Abstract A measure of the effective shear rate range for dispersive mixing in the Haake mixer has been developed, which is more representative of shearing conditions than that currently used. In addition, the effects of processing conditions, composition, and compatibilizer on linear low‐density polyethylene and polys…
Abstract A constitutive equation to describe the yield behavior of poly(methyl methacrylate (PMMA) is useful not only from the technological point of view, but also for the comprehension of the nonlinear mechanisms acting in the material. In both compression and tension, the yield stress is usually represented as a fu…
Abstract Gelatin, a natural macromolecule, is widely used in biomedical and biotechnological applications and is a good candidate for preparation of microspheres and microcapsules for the purpose of controlled release applications of drugs. In this study, gelatin microspheres crosslinked with glutaraldehyde with diffe…
Various procedures for preparation of the biopolymers chitin and chitosan have been developed over the years. Preparation methodology and analysis of physicochemical properties of these biopolymers are reviewed in terms of crustacean species and diverse characterization methodology. Such properties influence biopolyme…
Two previously undetected automerization processes occur among C3H2 isomers. On irradiation at λ = 313 nm, compounds 1a,b equilibrate via 3a,b; irradiation of compounds 2a,b at longer wavelengths (λ>444 nm) also leads to their interconversion, perhaps via a cyclopropyne intermediate or transition state.
The growth of twin-free single crystals of Tb0.3Dy0.7Fe2 with 〈111〉 orientation by the Czochralski method with cold crucible is reported. Various characterizations demonstrated the twin-free and single-crystalline quality of the crystals. The optimized growth parameters have been experimentally found to avoid constitu…
Antiferroelectric lead zirconate thin films were formed on platinum coated silicon substrates by a reactive magnetron co-sputtering method. The films showed (240) preferred orientation. The crystallization temperatures and the preferred orientation were affected by the lead content in the films. The electric field for…
The specific linking of two dendrimers is achieved by incorporating terpyridine moieties at precise locations in cascade molecules. Metal complex formation then enables nonrandom attachment of one dendritic assembly to another (see picture). The electronic properties of the metal depend on the dendritic environment.
Abstract Paleosols in the Lochness Formation (1.8 Ga, Australia) include both rare, non-red and abundant, strongly reddened varieties that formed at subaerial exposure surfaces in both ephemeral-river and lacustrine settings. Physical processes dominated non-red paleosols, which were characterized by repeated episodes…