Materials Literature
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Polycrystalline bulk porous samples with a large number of weak-link grain boundaries and high density polycrystalline bulk samples with strong-link boundaries were synthesized by conventional solid-state reaction and a partial melting technique. The weak-link samples showed large magnetoresistance (MR,Δρ/ρH=[ρ0−ρH]/ρ…
The level spectrum of a single-walled carbon nanotube rope, studied by transport spectroscopy, shows Zeeman splitting in a magnetic field parallel to the tube axis. The pattern of splittings implies that the spin of the ground state alternates by $\frac{1}{2}$ as consecutive electrons are added. Other aspects of the C…
The dynamical behaviour of the glass transition of propylene glycol confined in droplets in butyl rubber (three-dimensional confinement, mean droplet diameter d = 8-11 nm) and in pores in controlled porous glasses (two-dimensional confinement, mean pore diameter d = 2.5-7.5 nm) has been studied in detail by means of b…
The 7.9 eV photons of a ${\mathrm{F}}_{2}$ laser induced photochemical desorption of molecular hydrogen from $\mathrm{Si}(111)\ensuremath{-}(1\ifmmode\times\else\texttimes\fi{}1):\mathrm{H}$ surfaces with a cross section of $(1.2\ifmmode\pm\else\textpm\fi{}0.8)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}20}\…
We report the formation of large, branched silver aggregates after deposition of Ag on silicone oil surfaces. The origin of these ramified aggregates is traced to a two stage process, the first of which involves nucleation and growth of disk-shaped Ag clusters during deposition. In the subsequent stage after depositio…
The question of whether the primary $\ensuremath{\alpha}$ relaxation in glass-forming systems is homogeneous or heterogeneous in nature is investigated by incoherent neutron scattering techniques in glass-forming polymers. It is shown that the momentum transfer dependence of the Kohlrausch-Williams-Watts relaxation ti…
Rietveld refinements using neutron powder profiles are reported for a series of samples (commonly known as PZT), with x ranging from to . Cation shifts, octahedral distortion and tilts are determined with varying composition across the ferroelectric rhombohedral regions, and , of the PZT phase diagram. These parameter…
We propose a structural model for decagonal Al-Cu-Co quasicrystals based upon existing experimental diffraction data supplemented by total energy calculations. The model is a decoration of tiles related to the Penrose rhombus tiling. Strong chemical ordering between Cu and Co leads to chains of alternating Cu and Co a…
We have calculated the frictional drag between spatially separated quantum wells with parallel two-dimensional electron gases due to interlayer electron-electron interaction mediated by virtual exchange of acoustic phonons due to piezoelectric and deformation potential interaction. It is shown that the frictional drag…
A large entropy variation (magnetocaloric effect) has been discovered in ceramic perovskites with the formulas La0.65Ca0.35Ti1−xMnxO3−z and La0.5+x+yLi0.5−3yTi1−3xMn3xO3−z. Both Curie temperature and entropy change were studied from 4.2 to 400 K for different stoichiometric compositions and applied magnetic fields. Ou…
Dipole resonant x-ray scattering from ordered Mn $3d$ orbitals in $\mathrm{LaMn}{\mathrm{O}}_{3}$ has been observed near the Mn $K$-absorption edge. The polarization of the scattered photons is rotated from $\ensuremath{\sigma}$ to ${\ensuremath{\pi}}^{\ensuremath{'}}$ and the azimuthal angle dependence shows a charac…
Minimum film-formation temperature (MFFT) of vinylidene chloride (VDC)-methyl acrylate (MA) copolymer latexes prepared by batch emulsion polymerization with various compositions from 20 to 97 wt % of VDC were measured. For latexes with VDC content below 90 wt %, MFFT was similar to polymer Tg. As VDC content increased…
Moderate increases (∼ 50–75%) in the toughness of bismaleimides (BMIs) were achieved with very low-molecular-weight (∼ 1000 g/mol) imide thermoplastics at low levels of thermoplastic loading (∼ 10–20%). The thermoplastic was introduced into the BMI using a simple, one-pot, reactive solvent approach. In this approach,…
Surface carboxyl groups were formed during the 60Co γ-ray irradiation of poly(tetrafluoroethylene) (PTFE) in air. Fourier transform infrared spectroscopy enables the detection of surface carboxyl groups. The contact angles were used to calculate the dispersive and polar components of the surface free energy according…
The effects of blend composition, melt viscosity of poly(acrylonitrile-butadiene-styrene) (ABS), and compatibilizing effect of poly(methyl methacrylate) (PMMA) on mechanical properties of ABS/polycarbonate (PC) blends at ABS-rich compositions were studied. As the content of PC was increased, impact strength and Vicat…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTCaged Catalytic Subunit of cAMP-Dependent Protein KinaseChung-yu Chang, Tania Fernandez, Rekha Panchal, and Hagan BayleyView Author Information Worcester Foundation for Biomedical Research Shrewsbury, Massachusetts 01545 Departments of Medical Biochemistry & Genetics a…
Thiol-passivated AgI nanoparticles of 7−15 nm were synthesized in large quantities by changing the initial molar ratio of iodide to 1-thioglycerol, and thus their competitive reaction rates with silver ions was adjusted, leading to a precise control of the final particle size. Powder X-ray diffraction and transmission…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSignificant Effects of Nonconjugated Remote Substituents in Catalytic Asymmetric EpoxidationDan Yang, Yiu-Chung Yip, Jian Chen, and Kung-Kai CheungView Author Information Department of Chemistry, The University of Hong Kong Pokfulam Road, Hong Kong Cite this: J. Am. Ch…
Latex prepared from 91 : 5 : 4 wt % vinylidene chloride-acrylonitrile-methyl acrylate monomer mixture by seeded semicontinuous emulsion polymerization was investigated for a change in minimum film-formation temperature (MFFT) during storage, with focus placed on polymer crystallinity in the dispersed state. MFFT rose…
We report the first example of intramolecular excimer formation in supramolecular trichromophoric systems resulting from the metal-directed self-assembly of chromophore-labeled ligand molecules. The trichromophoric gallium(III) chelate, ( 1 ) 3 Ga, shows an intense pyrene excimer fluorescence emission in acetonitrile,…