Changes in the near-edge X-ray absorption fine structure spectra of long-chain diacetylene derivatives through photopolymerization in Langmuir–Blodgett films

Photopolymerization of cadmium 10,12-pentacosadiynoate (CdDA) in Langmuir–Blodgett (LB) films, with the molecular packing well arranged by moderate preannealing, was investigated with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Greenish films of polydiacetylene with an absorption wavelength of 705 nm were obtained through the photopolymerization of preannealed monomer LB films, and this resulted in an extended π-conjugate system based on the well-ordered monomer in a two-dimensional arrangement. The electronic structures of the polydiacetylenes were found to be correlated to the variation of the molecular arrangements in the films from the changes in the NEXAFS spectra through photopolymerization in the LB films. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2329–2336, 2004     

2‐connected 7‐coverings of 3‐connected graphs on surfaces

An m‐covering of a graph G is a spanning subgraph of G with maximum degree at most m. In this paper, we shall show that every 3‐connected graph on a surface with Euler genus k ≥ 2 with sufficiently large representativity has a 2‐connected 7‐covering with at most 6k ? 12 vertices of degree 7. We also construct, for every surface F² with Euler genus k ≥ 2, a 3‐connected graph G on F² with arbitrarily large representativity each of whose 2‐connected 7‐coverings contains at least 6k ? 12 vertices of degree 7. © 2003 Wiley Periodicals, Inc. J Graph Theory 43: 26–36, 2003     

Clinical evaluation of osteocalcin in sera of the patients with neoplasms of bone

The clinical significance of osteocalcin in sera of bone tumors were measured in sera of various kinds of bone tumors. The levels of osteocalcin were higher in bone tumors than those in normal subjects. Serum osteocalcin levels in hypercalcemic groups of bone metastasis and myeloma showed a remarkable increase in a parallelism with serum ALP and LDH levels. These results suggested to be directly or indirectly activated on osteoblast by bone tumors and to be synthesized osteocalcin in osteoblast.     

Expedient Conversion of Lactose into Versatile Derivatives of Lactosamine and β-d-Galactosyl-(1→4)-d-mannosamine

Abstract

A practical, nine-step protocol is described for the preparation of synthetically useful N-acetyllactosamine (LacNAc) derivatives as well as LacNAc itself from lactose using the benzoylated oxime of lactos-2-ulosyl bromide 2 as the key intermediate. All steps are performed with simple reagents, do not require chromatography, are large-scale adaptable and allow overall yields of 30%.     

Transverse wave generation mechanism in rotating detonation

Detonation engines are expected to be included in a number of aerospace thrusters in the future. Several types of detonation engines are currently under examination, including the rotating detonation engine (RDE). Although the RDE has been explored experimentally, its rotating detonation propagation mechanism is not well understood. This paper clarifies the detonation mechanism and dynamics of the RDE by 2D and 3D simulation using compressible Euler equations with a full chemical reaction mechanism of H₂/O₂ and H₂/Air, especially from the triple-point and transverse detonation points of view. A total variation diminishing (TVD) scheme is used for the mixture of H₂/Air, and an advection upwind splitting method difference vector (AUSMDV) scheme is used for the mixture of H₂/O₂. The use of an AUSMDV scheme provides a much clearer detonation structure than does the TVD scheme. We focus on the complex interaction mechanism of the detonation front and burned mixture gases. We found out that at this interaction point, an unreacted gas pocket appears and ignites periodically to generate transverse waves at the detonation front and maintain detonation propagation.     

Surface-modified lead–zirconium-titanate system for solution-processed ferroelectric-gate thin-film transistors

We propose the use of a La₂O₃ (LO) film as the capping layer for improvement of a semiconductor/insulator interface in a solution-processed indium–tin–oxide (ITO) ferroelectric-gate thin-film transistor (FGT) device. It is demonstrated that the LO layer acts as a good barrier film not only for preventing the interdiffusion between the ITO semiconductor and lead–zirconium-titanate (PZT) insulator layers, but also for stabilizing the PZT surface structure. The fabricated FGT device exhibited high I _on/I _off, large M _w, high μ _FE and improved retention time of about 10⁹, 3.5 V, 7.94 cm²?V^?1?s^?1 and 1 day, respectively, which are comparable to or better than those obtained with FGTs fabricated by means of conventional vacuum processes. We also point out that the key origin of the interface improvement is likely due to the incorporation of La into the PZT system, forming a La surface-modified PZT system which is more stable than the pure PZT in terms of Pb volatility and formation of oxygen vacancies.     

Control of island formation using overgrowth technique on cleaved edges of strained multiple quantum wells and selective epitaxy on patterned substrates

Two approaches to control the position and the size of semiconductor islands are proposed. The first method is to perform overgrowth on a cleaved edge of strained multiple quantum wells which acts as a substrate with a periodically modulated lattice constant, thus inducing a periodic strain to the overgrown layer. The second method is to selectively grow islands in specific windows defined by electron beam lithography. Both the methods are applied to the Ge/Si system and the controllability of the Ge island formation is demonstrated.     

Numerical analysis on auto-ignition of a high pressure hydrogen jet spouting from a tube

In this study, a direct numerical simulation based on compressible flow dynamics has been applied to the autoignition and extinction of a high-pressure hydrogen jet spouting from a tube. The diameter of the tube is 4.8 mm. The length of the tube is 71 mm. At the inlet, pressure is set at 3.6, 5.3 and 21.1 MPa, and temperature is set at 300 K for all cases. To explore the autoignition of hydrogen jet, two-dimensional axisymmetric Navier–Stokes equations with a detailed chemical kinetics and rigorous transport properties have been employed. The hydrogen jet through the tube is choked. The numerical results show that the high-pressure hydrogen jet produces a semi-spherical shock wave in the ambient air at the early time of jetting. The shock wave heats up the air to a high temperature and causes the autoignition of the hydrogen and air mixture in the tube as well as at the tube exit.     

The oldest mid-oceanic carbonate buildup complex: Setting and lithofacies of the Vendian (Late Neoproterozoic) Baratal limestone in the Gorny Altai Mountains,Siberia

The Baratal limestone in the Gorny Altai Mountains, southern Siberia, occurs as large allochthonous blocks within a Cambrian accretionary complex that developed around the Siberia craton. Before the final accretion to Siberia in the Cambrian, the terrigenous clastic-free Baratal limestone was deposited directly upon a basaltic basement with a geochemical signature identical to that of modern oceanic plateau. The Baratal limestone with 598 ± 25 Ma (Early Vendian) Pb-Pb isochron age consists of three distinct facies; 1) massive lime mudstone with ooids and stromatolites, 2) bedded lime mudstone, and 3) limestone conglomerate/breccia dominated by ooid-bearing lime mudstone clasts. The first represents a shallow marine environment on top of an ancient oceanic plateau, while the latter two represent the deeper slope to bottom-of-slope facies of a plateau. The Vendian Baratal limestone provides the oldest example of a reconstructed shallow marine carbonate buildup complex developed on a plateau/seamount in a mid-ocean.     

Shock-wave velocity of a femtosecond-laser-produced plasma

Fluorescence measurements have been used to characterize the velocity of atoms in a femtosecond-laser-produced plasma. Nanogram amounts of a copper sample were ablated by the focused radiation (λ=775 nm) of an all-solid-state laser. The laser was operated at a pulse rate of 10 Hz with an energy of 200μJ per pulse. The microplasma expanded into a defined argon atmosphere of pressures between 0.02 and 850 mbar. Atomic fluorescence was excited in the laser plume by a dye-laser pulse with the wavelength set to the line Cu I 282.4 nm. The narrowed beam of the dye-laser was directed into the plasma at different heights above the sample surface. The fluorescence radiation was measured with an échelle-spectrometer, equipped with an intensified-charge-coupled device as the detector. The velocity depends strongly on the pressure of the ambient atmosphere and the distance from the sample surface. The highest velocity found at an argon pressure of 0.02 mbar was 1.0×10⁶ cm s⁻¹.