Materials Literature
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The vacuum systems of all scanning electron microscopes (SEMs), even in the so-called clean instruments, have certain hydrocarbon residues that the vacuum pumps do not effectively remove. The cleanliness of the vacuum and the amount and nature of these residual molecules depends on the type of the pumps and also on th…
Aging dynamics in glassy systems is investigated by considering the hopping motion in a rugged energy landscape whose deep minima are characterized by an exponential density of states $\ensuremath{\rho}{(E)=T}_{g}^{\ensuremath{-}1}\mathrm{exp}{(E/T}_{g}),$ $\ensuremath{-}\ensuremath{\infty}<E<~0.$ In particular…
Abstract The melting behavior of syndiotactic polypropylene (s‐PP) after isothermal crystallization from the melt state was studied using differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD) techniques. Three melting endotherms were observed for isothermal crystallization at high degrees of…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTCatalytic Asymmetric Dihydroxylation of Olefins with New Catalysts: The First Example of Heterogenization of OsO42- by Ion-Exchange TechniqueBoyapati M. Choudary, Naidu S. Chowdari, Mannepalli L. Kantam, and Kondapuram V. RaghavanView Author Information Indian Institut…
Results are presented for the structural and thermodynamic properties of the orthorhombic phase of crystalline polyethylene (PE) from detailed atomistic molecular-dynamics (MD) simulations in the NPT statistical ensemble. Two different PE crystal systems have been investigated: (a) paraffins consisting of an odd numbe…
The isothermal crystallization process of poly(ether-ether-ketone) from the glass has been studied in real time by dielectric spectroscopy and x-ray scattering experiments. The combination of these two techniques revealed a complete picture of the crystallization processes from the point of view of both amorphous and…
Iron(II) bis(1,4,7-triazacylononane), Fe(tacn)22+, exhibits 1A1g ⇌ 5T2g spin-crossover behavior in solution. Values of ΔH°se = 23 kJ mol-1 and ΔS°se = 67 J mol-1 K-1 are obtained for the reaction by variable-temperature UV−visible and 1H NMR spectroscopy. The thermodynamic parameters reflect intramolecular structural…
Abstract A sequence of experimental steps was perfected to produce high‐impact modified polypropylene (PP), and to study the influence of particle morphology and rubber content on the reaction kinetics, especially in terms of mass transfer limitations. It was found that after a critical copolymer content at approximat…
Abstract For numerical simulations of the injection‐molding process, an accurate description of the specific volume is needed to predict differential shrinkage during and after molding, which causes thermally induced stresses and controls the dimensional accuracy and long‐term dimensional stability. For amorphous poly…
The electronic properties of gold–silver binary cluster anions (AunAgm−; 2⩽n+m⩽4) were studied by using photoelectron spectroscopy (PES) with a magnetic-bottle-type electron spectrometer. The AunAgm− cluster anions were generated by a laser vaporization of a gold–silver alloy rod. For triatomic AunAg3−n clusters, mono…
Abstract The morphology of some ternary blends was investigated. In all of the blends polypropylene, as the major phase, was blended with two different minor phases, ethylene–propylene–diene terpolymer (EPDM) or ethylene–propylene–rubber (EPR) as the first minor phase and high‐density polyethylene (HDPE) or polystyren…
Low-frequency Raman scattering experiments have been performed on metal nanoparticles embedded in two different thermally treated matrices. In addition to the well-known Raman scattering by the nanoparticle quadrupolar vibrational mode, the spectra measured in the 3–40 cm−1 frequency range exhibit several new bands. T…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPeriodic Tiling of Pentagons: The First Example of a Two-Dimensional ( )-netBrian Moulton, Jianjiang Lu, and Michael J. ZaworotkoView Author Information Department of Chemistry University of South Florida 4202 East Fowler Avenue (SCA 400) Tampa, Florida 33620 Cite this…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTHeterogeneous Seeded Growth: A Potentially General Synthesis of Monodisperse Metallic NanoparticlesHeng Yu, Patrick C. Gibbons, K. F. Kelton, and William E. BuhroView Author Information Departments of Chemistry and Physics Washington University, St. Louis, Missouri 631…
The problem of adequate electronic model for doped manganites like La_{1-x}Sr_{x}MnO_3 remains controversial. In such a situation we argue a necessity to discuss all possible candidate states with different valent structure of manganese and oxygen atoms, as well as different valent states of octahedral MnO_{6} centers…
Four new quaternary selenides CsGdZnSe3, CsZrCuSe3, CsUCuSe3, and BaGdCuSe3 have been synthesized with the use of traditional high-temperature solid-state experimental methods. These compounds are isostructural with KZrCuS3, crystallizing with four formula units in the orthorhombic space group Cmcm. Cell constants (A)…
We propose the two-band s-d model to describe theoretically a diffuse regime of the spin-dependent electron transport in magnetic tunnel junctions (MTJ's) of the form F/O/F where F's are 3d transition metal ferromagnetic layers and O is the insulating spacer. We aim to explain the strong interface sensitivity of the t…
Single crystals of hexagonal $R{\mathrm{MnO}}_{3}$ $(R=\mathrm{Y},$ Yb, and Lu), where Mn ions form the triangular lattice, were investigated, focusing on their dielectric/magnetic anomalies as well as geometrical spin frustration. It is found that the ratio of a Weiss temperature to ${T}_{\mathrm{N}}$ is $\ensuremath…
TiNi/CFRP composites were fabricated by hot-pressing in the temperature range of 130-180 degree(s)C, by controlling the applied pressure. The TiNi wires were embedded as an 1mm interval into the center of CFRP layers and CFRP host materials were stacked as 0, 30, 60 and 90 degrees configuration on tensile direction, r…
The phase behavior, rheology, and morphology of binary blends of semiflexible main-chain thermotropic liquid-crystalline polymers (TLCPs) were investigated. Specifically, binary blends consisting of poly[(phenylsulfonyl)- p -phenylene alkylene-bis(4-oxybenzoate)]s (PSHQ n ) having five methylene groups (PSHQ5) and 11…