Materials Literature
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Dehydrogenation of ethylbenzene to styrene under excess carbon dioxide flow was carried out over activated carbon-supported metal oxide catalysts (Cr, Mn, Co, Ni, Mo, Ru, La, and Ce) at 823 K and W / F = 35 g of catalyst·h/mol. The highest yield of styrene (about 40%) with selectivity of above 80% was obtained using a…
Luminescence sensitivity changes in natural quartz induced by high temperature annealing: a high frequency EPR and OSL study, N R J Poolton, G M Smith, P C Riedi, E Bulur, L Bøtter-Jensen, A S Murray, M Adrian
Four different forms of jute fibers, namely untreated jute filament (UJF), sliver jute filament (SJF), bleached jute filament (BJF), and mercerized jute filament (MJF), have been subjected to tensile strength analysis following Weibull's theory. The MJF and BJF were obtained by the chemical modification of the UJF. A…
The time-evolution of a three-dimensional (3D), bicontinuous interface of a phase-separated polymer mixture in the late stage spinodal decomposition (SD) process has been studied by laser scanning confocal microscopy (LSCM) and time-resolved light scattering. The time evolution of the interface between two coexisting…
Results are presented of friction and wear measurements during diamond polishing using new instrumentation designed and built in our laboratory. The wear rates are found to be highly anisotropic, depending both on the crystallographic plane and on the direction along which sliding occurs. Friction measurements perform…
Two enantiomeric triblock ABA copolymers composed of poly(L-lactide)–poly(ethylene glycol)–poly(L-lactide) (PLLA–PEG–PLLA) and poly(D-lactide)–poly(ethylene glycol)–poly(D-lactide) (PDLA–PEG–PDLA) were synthesized with two different middle-block PEG chain lengths by ring-opening polymerization of L-lactide and D-lacti…
Chemical modification of cellulose powder is performed by successive reactions with acrylonitrile in an alkaline medium followed by aqueous hydroxylamine to prepare amidoximated cellulose. Due to complexation, the amidoxime groups immobilize heavy cations from buffered solutions at various pH values. The capacity of a…
The glass transition temperature ( T g ) in the thin poly(α-methyl styrene) and polysufone films that are coated on the surface of a Si wafer is investigated in this paper. A novel equation was suggested to estimate the thickness dependence of T g in thin films. Ellipsometry has been used to measure T g of various thi…
Higher generations of poly(propylene imine) dendrimers functionalized with aliphatic chains form large micrometer-sized spherical objects in aqueous solution below pH 8. These spheres are giant vesicles with a multilaminar onion-like structure. The size distribution and the structure of the vesicles depend on the pH o…
The charge density distribution of a protein has been refined experimentally. Diffraction data for a crambin crystal were measured to ultra-high resolution (0.54 A) at low temperature by using short-wavelength synchrotron radiation. The crystal structure was refined with a model for charged, nonspherical, multipolar a…
The current status of research on the carrier-mediated ferromagnetism in tetrahedrally coordinated semiconductors is briefly reviewed. The experimental results for III-V semiconductors, where Mn atoms introduce both spins and holes, are compared to the case of II-VI compounds, in which the ferromagnetism has been obse…
Electron-hole mixing-induced fine structure in alkaline earth hexaborides leads to lower energy (temperature) scales, and thus stronger tendency toward an excitonic instability, than in their doped counterparts (viz. Ca(1-x)La(x)B(6), x=0.005), which are high Curie temperature, small moment ferromagnets. Comparison of…
We have studied the influence of the patterning procedure on the critical current density of high-$T_c$ YBa$_2$Cu$_3$O$_{7-δ}$ thin rings using the nonlinear ac susceptibility method. At no applied dc magnetic field we have found that laser ablation degrades strongly the critical current density whereas ion beam etchi…
A microscopically motivated theory of glassy dynamics based on an underlying random first order transition is developed to explain the magnitude of free energy barriers for glassy relaxation. A variety of empirical correlations embodied in the concept of liquid "fragility" are shown to be quantitatively explained by s…
Novel vegetable oil derived macromonomers were synthesized by the chemical modification of castor, lesquerella and vernonia oils. The castor oil derivative has been successfully copolymerized into vinyl-acrylic and all-acrylic latexes designed for use as architectural coatings. The castor oil derived monomer provides…
Starting from rapidly quenched NdδFe13.1B(2.05⩽δ⩽147.6) alloys and by appropriate annealing, the microstructure was tailored from strongly interacting Nd2Fe14B grains to magnetically isolated single domain Nd2Fe14B grains embedded in a nonmagnetic Nd-rich matrix (α-Nd and γ-Nd). This change in microstructure was found…
ZnS layers were grown by metalorganic vapor phase epitaxy on GaAs substrates using diethylzinc, ditertiarybutyl sulphide, and triallylamine as organometallic sources. After postgrowth rapid thermal annealing, the ZnS layers showed p-type conductivity with hole concentrations up to 1018 cm−3. Photoluminescence measurem…
We compare the large magnetoresistive response of slightly nonstoichiometric Ag2±δTe for a wide range of hole (p⩽8×1017 cm−3) and electron (n⩽4×1018 cm−3) carrier densities. In the p-type material alone, a characteristic peak in the resistivity ρ(T,H) is dramatically enhanced and moves to higher temperature with incre…
Perfectly c-axis oriented micrometer thick Na0.5K0.5NbO3(NKN) films have been prepared on a thermally grown ultrathin SiO2 template layer onto a Si(001) wafer by the pulsed laser deposition technique. A x-ray diffraction θ–2θ scan reveals multiple-cell structuring of single phase NKN film along the polar axis, while f…
Using atomistic pseudopotential wave functions we calculate the quasiparticle gap, the optical gap and the electron and hole addition energies of CdSe nanocrystals. We find that the quasiparticle gap and the addition energies depend strongly on the dielectric constant of the surrounding material, while the optical gap…