Discrimination Between 8‐Oxo‐2′‐Deoxyguanosine and 2′‐Deoxyguanosine in DNA by the Single Nucleotide Primer Extension Reaction with Adap Triphosphate

The adenosine derivative of 2‐oxo‐1,3‐diazaphenoxazine (Adap) exhibits a superb ability to recognize and form base pairs with 8‐oxo‐2′‐deoxyguanosine (8‐oxo‐dG) in duplex DNA. In this study, the triphosphate of Adap (dAdapTP) was synthesized and tested for single nucleotide incorporation into primer strands using the Klenow Fragment. The efficiency of dAdapTP incorporation into 8‐oxo‐dG‐containing templates was more than 36‐fold higher than with dG‐containing templates, and provides better discrimination than does the incorporation of natural 2′‐deoxyadenosine triphosphate (dATP). The selective incorporation of dAdapTP into 8‐oxo‐dG templates was therefore applied to the detection of 8‐oxo‐dG in human telomeric DNA sequences extracted from H₂O₂‐treated HeLa cells. The enzymatic incorporation of dAdapTP into 8‐oxo‐dG‐containing templates may provide a novel basis for sequencing oxidative DNA damage in the genome.     

Localized solutions to the nonlinear wave equation for flexural motions of an elastic beam traveling in an air-filled tube

Steady-progressive-wave solutions are sought to the nonlinear wave equation derived previously [J. Fluids Struct. 16 (2002) 597] for flexural motions of an elastic beam traveling in an air-filled tube along its center axis at a subsonic speed. Fluid-structure interactions are taken into account through aerodynamic loading on the lateral surface of the beam subjected to small but finite deflection but end effects and viscous effects are neglected. Linear dispersion characteristics are first examined by exploiting the small ratio of the induced mass to the mass of the beam per unit length. Centered around the traveling speed of the beam, there exists such a narrow range of propagation velocity that the linear steady propagation is prohibited. In this range, it is revealed that some interesting nonlinear solutions exist. The periodic wavetrain is found to exist as the exact solution. Asymptotic analysis is then made by applying the method of multiple scales and the stationary nonlinear Schrödinger equation is derived for a complex amplitude. A monochromatic solution to this equation corresponds to the exact periodic solution. Imposing undisturbed boundary conditions at infinity, it is revealed that the localized solution exists as a result of balance between the linear instability and the nonlinearity. This solution is checked by solving the nonlinear equation numerically. It is further revealed that the amplitude-modulated wavetrain exists not only in the range of the velocity mentioned above but also outside of it.     

Fiber-optic distributed measurement of polarization beat length using slope-assisted Brillouin optical correlation-domain reflectometry

Optical Review - We demonstrate distributed measurement of the polarization beat length along single-mode optical fibers (SMFs) using slope-assisted Brillouin optical correlation-domain...     

Minimization of erase-band in shingled PMR with asymmetric writer

To make the write-field much stronger with sharper cross-track field gradient in Shingled perpendicular Magnetic Recording (SMR), we have successfully developed asymmetric SMR heads with one-side shield design. Using these heads, higher track density capability on the shielded-side was demonstrated, which came from narrower erase-band width at shielded side.     

Photoluminescence of bis(8-hydroxyquinoline) zinc (Znq2) and magnesium (Mgq2)

Absorption and photoluminescence (PL) spectra, PL quantum efficiency, and PL lifetime have been investigated on bis(8-hydroxyquinoline) zinc (Znq₂) and magnesium (Mgq₂) in solutions and powder. Znq₂ and Mgq₂ have the lowest-energy absorption band at 376 and 396 nm in acetonitrile solution, respectively, and emission band with peak at 555 and 480 nm. The PL quantum efficiency is 0.03 and 0.45 for Znq₂ and Mgq₂ in the solution, respectively, while 0.45 and 0.36 in powder. Unlike the case of powders, two PL lifetimes are obtained in solutions. The longer lifetime is attributed to molecule having interaction with its neighboring molecule, while the shorter one to the isolated single molecule.     

Preparation of dibromopyridines having -(CH2)m-SO3Na groups as monomers for new polypyridines

Dibromopyridines or dibromopyridone with -(CH₂)_m-SO₃Na group(s) has been prepared via the reactions of the corresponding dibromopyridines with -OH and -NH₂ groups with sultone. These compounds were converted into polymers with the -(CH₂)_m-SO₃H groups via organometallic polycondensation. The polymer showed proton conducting properties and high stability toward oxidation.     

Water‐ and Temperature‐Triggered Reversible Structural Transformation of Tetranuclear Cobalt(II) Cores Sandwiched by Polyoxometalates

Although stimuli‐responsive structural transformations of inorganic materials have attracted considerable attention because of their potential use as functional switchable materials, multinuclear metal cores frequently suffer from unexpected dissociation of metal cations and/or irreversible transformations into infinite structures. In this study, we describe the successful demonstration of the water‐ and temperature‐triggered reversible structural transformation between cubane‐ and planar‐type tetranuclear Co^II cores sandwiched by polyoxometalates. The arrangements and coordination geometries of the Co^II cations were interconverted by simple hydration and dehydration, resulting in the manipulation of the magnetic and optical properties of these compounds. Moreover, this system showed unique thermochromism through temperature‐dependent reversible structural interconversion.     

Copper–Oxygen Dynamics in the Tyrosinase Mechanism

The dinuclear copper enzyme, tyrosinase, activates O₂ to form a (μ-η²:η²-peroxido)dicopper(II) species, which hydroxylates phenols to catechols. However, the exact mechanism of phenolase reaction in the catalytic site of tyrosinase is still under debate. We herein report the near atomic resolution X-ray crystal structures of the active tyrosinases with substrate l -tyrosine. At their catalytic sites, CuA moved toward l -tyrosine (CuA1 → CuA2), whose phenol oxygen directly coordinates to CuA2, involving the movement of CuB (CuB1 → CuB2). The crystal structures and spectroscopic analyses of the dioxygen-bound tyrosinases demonstrated that the peroxide ligand rotated, spontaneously weakening its O−O bond. Thus, the copper migration induced by the substrate-binding is accompanied by rearrangement of the bound peroxide species so as to provide one of the peroxide oxygen atoms with access to the phenol substrate's ϵ carbon atom.     

Thermodynamic study on the interaction of imidazolium salts and POE-type nonionic surfactant in the adsorbed film

The composition of the adsorbed film and the excess Gibbs energy of adsorption $ {\widehat{g}}^{\mathrm{H},\mathrm{E}} $ were evaluated from thermodynamic analysis of surface tensions for the 1-decyl-3-methylimidazoulium bromide (C₁₀mimBr)–tetraethylene glycol monooctyl ether (C₈E₄) and 1-decyl-3-methyl-imidazolium tetrafluorobrorate (C₁₀mimBF₄)–C₈E₄ systems, where the counter anion of imidazolium salts is different from each other. The higher miscibility of two components compared to an ideal mixing and thus negative $ {\widehat{g}}^{\mathrm{H},\mathrm{E}} $ were observed in the former, which comes from the ion–dipole interaction between imidazolium cation and the oxyethylene group of C₈E₄. On the other hand, the lower miscibility and thus positive $ {\widehat{g}}^{\mathrm{H},\mathrm{E}} $ were observed for the latter. Such differences were attributed to that BF₄ ^? forms two hydrogen bonds and has stronger affinity with the cationic head group of C₁₀mim⁺ than Br^?. This results in that the ion–dipole interaction between C₈E₄ and C₁₀mim⁺ cation is diminished in the C₁₀mimBF₄–C₈E₄ system.