Influence of the surface free energy of silane-coupled mica substrate on the fixing and straightening of DNA

Methyltrimethoxysilane (MTMS)-coupled mica substrate is reportedly suitable for fixing and straightening of DNA, but 3-aminopropyltriethoxysilane (APTES)-coupled mica substrate has been found less suitable. On MTMS-coupled mica substrate, the straightness of fixed DNA was sufficient, and the adsorption of contaminants was not observed using fluorescence microscopy and atomic force microscopy. For the APTES-coupled mica substrate, however, aggregated or curved DNA and adsorption of contaminants were observed. To clarify the surface factors that are responsible for this suitability, we analyzed the surface free energies of these substrates using the extended Fowkes theory. In each of the surface free energy components, the dispersion force component in the MTMS-coupled mica substrate was lower than that in the APTES-coupled mica substrate. The ratio of the polar force component on the MTMS-coupled mica substrate was about one order of magnitude on the APTES-coupled mica substrate. In addition, the ratio of the hydrogen-bonding force component for the MTMS-coupled mica substrate was about two times larger than that of the APTES-coupled mica substrate. These results suggest that the polar force and hydrogen-bonding force components are important factors for the fixation and straightening of DNA and that the dispersion force components influence the production and adsorption of contaminants.     

Development of GEM tracking detector for intermediate-energy nuclear experiments

We have developed a tracking detector with a gas electron multiplier (GEM) for nuclear experiments. The developed GEM detector was installed inside the dipole magnet used for transporting the primary beam to the beam dump and it was used to measure the momentum of charged particles. A sufficiently high spatial resolution was achieved at a high counting rate and a magnetic field for coherent pion production with a 392 MeV proton beam to study the short-range component of the residual nuclear interaction. The detector systems and development procedure are described.     

AC loss characteristics of copper-stabilized YBCO coated conductor

Influence of copper layer and mechanical stress-strain on AC losses in copper-stabilized YBCO coated conductor (CC) was investigated. The uni-axial tensile stress-strain was applied to the sample CC in liquid nitrogen at atmospheric pressure, and the AC losses (transport, magnetization and total AC losses) were measured by an electric method. Experimental results showed that the stress-strain dependence of the AC losses can be estimated by knowing stress dependent critical current and magnetization losses in the non-stressed CC. Influence of the copper layer was investigated by measuring frequency dependence of the AC losses. The experimental results showed that there are some influences of the copper layer. However, the influence of the copper layer was not significant from the stand point of practice applications.     

Low-Temperature Structural Phase Transition in ZrO2–12 mol% CeO2 Studied by Infrared Spectroscopy and X-ray Diffractometry

The low-temperature tetragonal ( t ) to monoclinic ( m ) phase transition in ZrO₂–12 mol% CeO₂ was studied by Fourier-transform infrared spectroscopy and X-ray diffractometry (XRD). When the ZrO₂–12 mol% CeO₂ was cooled, the t → m phase transition occurred at about 120 K; this caused significant changes in the infrared reflectance spectra and X-ray diffractograms. As the phase transition proceeded, "difference spectra" obtained by subtracting the infrared spectra before and after the phase transition revealed two infrared modes at 575 and 740 cm⁻¹ which were assigned to the m phase. The volume fraction of the m phase (determined by XRD) and the subtraction coefficient (defined such that the difference spectra reproduced the infrared spectrum of m -ZrO₂) were consistent with each other; this revealed a marked discontinuity at about 120 K. Full width at half maximum of the ( 1 11) _m and (111) _t reflections also indicated a similar discontinuity at about 120 K.     

Bloch-wave-based STEM image simulation with layer-by-layer representation

In a dynamical STEM image simulation by the Bloch-wave method, Allen et al. formulated a framework for calculating the cross-section for any incoherent scattering process from the inelastic scattering coefficients: thermal diffuse scattering (TDS) for high-angle annular dark-field (HAADF) and back-scattered electron (BSE) STEM, and ionization for electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDX) STEM. Furthermore, their method employed a skilful approach for deriving the excitation amplitude and block diagonalization in the eigenvalue equation. In the present work, we extend their scheme to a layer-by-layer representation for application to inhomogeneous crystals that include precipitates, defects and atomic displacement. Calculations for a multi-layer sample of Si–Sb–Si were performed by multiplying Allen et al.'s block-diagonalized matrices. Electron intensities within the sample and EDX STEM images, as an example of the inelastic scattering, were calculated at various conditions. From the calculations, 3-dimensional STEM analysis was considered.     

Facile preparation and characterization of novel fluoroalkyl end‐capped oligomer/zinc oxide nanocomposites

BACKGROUND: The aim of the present work was to prepare novel fluoroalkyl end‐capped oligomer/zinc oxide nanocomposites by the use of fluoroalkyl end‐capped oligomers as key intermediates. In addition, it was intended to clarify the unique properties of these fluorinated nanocomposites. RESULTS: A variety of fluoroalkyl end‐capped oligomer/zinc oxide nanocomposites were prepared by the interaction of the corresponding oligomers with zinc oxide particles, which were obtained by the reaction of zinc acetate dihydrate with sodium hydroxide in ethanol solution at room temperature. In contrast, fluoroalkyl end‐capped 2‐methacryolyoxyethanesulfonic acid oligomer was found to afford the corresponding fluorinated amorphous zinc oxide composites under similar conditions. CONCLUSION: These fluorinated zinc oxide composites thus obtained are nanometer size‐controlled very fine particles, and they exhibit a good dispersibility and stability in water and traditional organic media. These fluorinated nanocomposites were also applied for the surface modification of poly(methyl methacrylate) (PMMA) films, which gave not only a good surface‐active property imparted by fluorine but also unique characteristics related to the presence of zinc oxide nanoparticles on the modified PMMA film surface. Copyright © 2008 Society of Chemical Industry     

Bioactive Bone Cement Based on CaO─SiO2─P2O5 Glass

A CaO─SiO₂─P₂O₅─CaF₂ glass powder hardened within 4 min when mixed with an ammonium phosphate solution to form CaNH₄PO₄·H₂O. After it had soaked in a simulated body fluid for 3 d, forming hydroxyapatite, the cement showed a compressive strength of 80 MPa. Implanted into a rat tibia, the mixed paste formed a tight chemical bond to the living bone within 4 weeks. Such a bioactive cement could be useful not only for fixing various kinds of implants to the surrounding bones but also, by itself, as a bone filler.     

Modification of epoxy resins with poly(aryl ether ketone)s

Poly(aryl ether ketone)s were used as modifiers for bisphenol-A diglycidyl ether epoxy resin (AER 331) cured with methyl hexahydrophthalic anhydride. Poly(phthaloyl diphenyl ether) (PPDE), soluble in the uncured epoxy resin without using solvents, was prepared by the Friedel-Crafts reaction of phthaloyl chloride and diphenyl ether. The mechanical, thermal, and dynamic viscoelastic properties of the modified resins with PPDE were examined and compared to the parent resin (AER 331). The fracture toughness, K_IC, for the modified resins increased at no expense to their mechanical and thermal properties on 10 wt % addition of PPDE with molecular weights of more than 17,000. The toughening mechanism is discussed based on the morphological and dynamic viscoelastic behaviors of the modified epoxy resin system.     

A thermally resistant and air-stable n-type organic semiconductor: Naphthalene diimide of 3,5-bis-trifluoromethyl aniline

We report a thermally resistant and air-stable n-type semiconductor based on our study of naphthalene diimide (NTCDI) derivatives (N1, N2, and N3) with various numbers of electron-withdrawing CF₃ groups. The device using N3, which contains aromatic NTCDI, was found to exhibit an electron mobility (μ_e) of 0.15 (±0.04) cm²/V s (the maximum μ_e observed was 0.24 cm²/V s) and an I_on/I_off (at V_d = 80 V) of approximately 2 × 10⁵. Moreover, the N3 device exhibits excellent air stability, even when exposed to the open air for 42 days, and significantly better thermal resistance than the previously reported benzylic imide derivative R1.     

Oxidation and vitrification of aluminum with lead borate glass for low level radioactive waste treatment

ABSTRACT

For the direct vitirification of low level radioactive wastes containing metallic aluminum, the oxidation and vitirification of aluminum was carried out using lead borate glass as a flux. Among the six fluxes employed in this study, 0.11Na₂O ?3PbO ?B₂O₃ was the most suitable for the oxidation and vitirification of aluminum based on the initial oxidation rate and alumina solubility. The increase of the lead fraction in the flux increased the oxidation rate, while the sodium fraction affected the alumina solubility resulting in the product maintaining its transparent appearance. The agglomerate product by the oxidation was confirmed metallic lead by X-ray diffraction analysis, and its impurities, aluminum, boron and sodium, were lower than 0.2 wt% by the quantitative analysis.