Development of a Simulation Model for Solid Objects Suspended in a Fluctuating Fluid

We introduce a new scheme for the future application of Real-coded Lattice Gas (RLG) to the numerical simulation of suspended solid objects in a fluctuating fluid environment. The reproduction of Brownian motion for a single solid object is verified through the Gaussian distribution of its displacements. The effectiveness of the solid–solid interaction model is also confirmed in an N-body simulation.     

Optimization of mark edge recording waveform for a phase change rewritable optical disk using a 680 nm laser diode

A high density mark edge recording method on a phase change rewritable disk is reported. A carrier-to-noise ratio of 55 dB for a mark length of 0.55,μm is obtained by using a 680 nm, NA 0.6 head and a phase change rewritable disk. In mark edge recording, it is necessary to record each mark in correct length. A new laser power modulation pattern is proposed. This pattern consists of a first-pulse, a multi-pulse chain and a last-pulse. Both positions of the first-ptilse and the last-pulse are movable. By adjusting these positions, a jitter, σ/T_w (T_w is window margin), is improved to 6.5% in high density EFM (Eight to Fourteen Modulation) recording of 0.4 μm/bit.     

Palladium‐Catalyzed Coupling Reaction of Perfluoroarenes with Diarylzinc Compounds

This report describes the first Pd⁰‐catalyzed cross‐coupling of hexafluorobenzene (C₆F₆) with diarylzinc compounds to give a variety of pentafluorophenyl arenes. This reaction could be applied to other perfluoroarenes, such as octafluorotoluene, pentafluoropyridine, and perfluoronaphthalene, to give the corresponding polyfluorinated coupling products. The optimal ligand in this catalytic reaction was PCy₃, and lithium iodide was indispensable as an additive for the coupling reaction. One of the roles of lithium iodide in this catalytic reaction was to promote the oxidative addition of one C?F bond of C₆F₆ to palladium. Stoichiometric reactions revealed that an expected oxidative‐addition product, trans‐[Pd(C₆F₅)I(PCy₃)₂], generated from the reaction of [Pd(PCy₃)₂] with C₆F₆ in the presence of lithium iodide, was not involved in the catalytic cycle. Instead, a transient three‐coordinate, monophosphine‐ligated species, [Pd(C₆F₅)I(PCy₃)], emerged as a potential intermediate in the catalytic cycle. Therefore, we isolated a novel Pd^II complex, [Pd(C₆F₅)I(PCy₃)(py)], in which pyridine (py) acted as a labile ligand to generate the transient species. In fact, in the presence of lithium iodide, this Pd^II complex was found to react smoothly with diphenylzinc to give the desired pentafluorophenyl benzene, whereas the same reaction conducted in the absence of lithium iodide resulted in a decreased yield of pentafluorophenyl benzene, which indicated that the other role of lithium iodide was to enhance the reactivity of the organozinc species during the transmetalation step.     

Thermodynamic evidence for nanoscale bose-einstein condensation in (4)He confined in nanoporous media

We report the measurements of the heat capacity of (4)He confined in nanoporous Gelsil glass that has nanopores of 2.5-nm diameter at pressures up to 5.3 MPa. The heat capacity has a broad peak at a temperature much higher than the superfluid transition temperature obtained using the torsional oscillator technique. The peak provides definite thermodynamic evidence for the formation of localized Bose-Einstein condensates on nanometer length scales. The temperature dependence of the heat capacity is described well by the excitations of phonons and rotons, supporting the existence of localized Bose-Einstein condensates.     

The Critical Effect of Niobium Doping on the Formation of Mesostructured TiO2: Single‐Crystalline Ordered Mesoporous Nb‐TiO2 and Plate‐like Nb‐TiO2 with Ordered Mesoscale Dimples

Highly ordered mesoporous niobium‐doped TiO₂ with a single‐crystalline framework was prepared by using silica colloidal crystals with ca. 30 nm in diameter as templates. The preparation of colloidal crystals composed of uniform silica nanoparticles is a key to obtain highly ordered mesoporous Nb‐doped TiO₂. The XPS measurements of Nb‐doped TiO₂ showed the presence of Nb⁵⁺ and correspondingly Ti³⁺. With the increase in the amount of doped Nb, the crystalline phase of the product was converted from rutile into anatase, and the lattice spacings of both rutile and anatase phases increased. Surprisingly, the increase in the amount of Nb led to the formation of plate‐like TiO₂ with dimpled surfaces on one side, which was directly replicated from the surfaces of the colloidal silica crystals.     

Stability and vibrational spectra of toroidal isomers of C 240

To study the thermodynamic and mechanical stability of toroidal isomers of C ₂₄₀, we use a semi-empirical tight-binding theory and calculate their electronic structure, cohesive energy and vibrational spectra within the harmonic approximation. From these, we deduce their free energy at temperatures up to 1500K. The results are also compared to the isomer with icosahedral symmetry. Finally, we discuss within this approach, their stability and abundance.     

Compact apparatus for rapid measurement of high-pressure phase equilibria of carbon dioxide expanded liquids

A new apparatus based on a synthetic method was developed for phase equilibrium measurements. The characteristic features of the apparatus are its light weight (ca. 288 g), variable-volume with a free piston, position sensing device for the piston, precise pressure and temperature control, and a window for visual observation. The inner volume of the cell can vary from 2.5 to 8.8 cm³. The cell was constructed from titanium so that the composition of the sample can be determined by direct weighing of the cell. The apparatus was designed for temperatures up to 473 K and pressures up to 25 MPa.     

Synthesis and properties of copolymers of methyl methacrylate with 2,3,4,5,6‐pentafluoro and 4‐trifluoromethyl 2,3,5,6‐tetrafluoro styrenes: An intrachain interaction between methyl ester and fluoro aromatic moieties

2,3,4,5,6‐Pentafluoro and 4‐trifluoromethyl 2,3,5,6‐tetrafluoro styrenes were readily copolymerized with methyl methacrylate (MMA) by a free radical initiator. The copolymers were soluble in tetrahydrofuran and acetone. The films obtained were transparent and flexible. The glass transition temperatures (T_gs) of the copolymers were found positively deviated from the Gordon–Taylor equation. The positive deviation could be accounted for by dipole–dipole intrachain interaction between the methyl ester group of MMA and the highly fluorinated aromatic moiety, which resulted in a decrease in the segmental mobility of the polymer chains and the enhanced T_g values of the copolymers. The water absorption of PMMA was greatly decreased by copolymerization of MMA with the highly fluorinated styrenes. With as little as 10 mol % of pentafluoro styrene content in the copolymer, the water absorption was decreased to one‐third of that for pure PMMA. The fluorinated styrenes‐MMA copolymers were thermally stable up to 420 °C under air and nitrogen atmospheres. With 50 mol % of MMA in the copolymer, the copolymer was still stable up to 350 °C. Since these copolymers contain a large number of fluorine atoms, the light absorption in the region of the visible to near infrared is decreased in comparison with nonfluorinated polymers. Thus, these copolymers may be suitable for application in optical devices, such as optical fibers and waveguides. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010