Electronic structure of DNA nucleobases and their dinucleotides explored by soft X-ray spectroscopy

The electronic structures of a series of DNA nucleobases and their dinucleotides were investigated by N 1s X-ray absorption, X-ray photoemission, and resonant X-ray emission spectroscopy. Resonant X-ray emission spectra of the guanine base and its dinucleotide indicate that it has a weak structure at the lowest binding energy; at this energy, it isolates from the main valence band and forms the HOMO state. This indicates that the HOMO state is localized in the guanine base, as claimed by valence and core photoemissions and expected from theoretical predictions. In addition, the XAS and XES profiles of the guanine dinucleotide indicate that disruption of the aromatic character of the six-membered ring results in the localization of the pi state at the imine (-N=) site of the guanine base; this may favor charge transfer among stacked guanine bases and further influence the conductivity of DNA.     

Direct benzylation and allylic alkylation in high-temperature water without added catalysts

In high-temperature water a series of benzyl and allylic alcohols reacted with 1,3-dicarbonyl compounds and activated aromatic compounds to give the alkylated products without added catalysts.     

Simultaneous determination of traces of impurities in high-purity molybdenum and molybdenum trioxide by coprecipitation and inductively coupled plasma-atomic emission spectrometry

Summary Inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been developed for a simultaneous determination of traces of non-hydride-forming elements in high-purity Mo and molybdenum trioxide. Coprecipitation of diverse elements with lanthanum hydroxide is used to separate them from the Mo matrix and for concentration. Effects of pH and amount of La on the recoveries of diverse elements are discussed. Ten elements (Co, Cr, Cu, Fe, Mn, Ni, Ti, V, Zn, and Zr) are quantitatively recovered and determined. Matrix-matched calibration solutions are used for the determination.     

Positron annihilation in Sn fine particles

It was found that positron annihilation mechanisms in Sn fine particles fall into two categories: annihilation with electrons inside the particles and that from particle surface trapped states.     

Dependence of the conduction of a single biphenyl dithiol molecule on the dihedral angle between the phenyl rings and its application to a nanorectifier

The transport properties of a biphenyl dithiol (BPD) molecule sandwiched between two gold electrodes are studied using the nonequilibrium Green's function method based on the density functional theory. In particular, their dependence on the dihedral angle (phi=90 degrees -180 degrees ) between two phenyl rings is investigated. While the dihedral-angle dependence of the density of states projected on the BPD molecular orbitals is small, the transport properties change dramatically with phi. The transmission at the Fermi energy exhibits a minimum at phi=90.0 degrees and greatly increases with phi. The ratio of the maximum obtained at phi=180 degrees to the minimum exceeds 100. As an application of this characteristic transport behavior, a BPD molecule functionalized with NH(2) and NO(2) groups is considered. It is found that this molecule works as a nanorectifier.     

Spectroscopy of η′ Mesic Nuclei with (p, d) Reaction

We are going to perform an inclusive spectroscopy experiment of η′ mesic nuclei with the ¹²C(p,d) reaction to study in-medium properties of the η′ meson. In nuclear medium, the η′ meson mass may be reduced due to partial restoration of chiral symmetry. In case of sufficiently large mass reduction and small absorption width of η′ at normal nuclear density, peak structures of η′ mesic states in ¹¹C will be observed near the η′ emission threshold even in an inclusive spectrum. The experiment will be carried out at GSI with proton beam supplied by SIS using FRS as a spectrometer. The detail of the experiment is described.     

Highly Active Multidentate Ligand‐Based Alkyne Metathesis Catalysts

Alkyne metathesis catalysts composed of molybdenum(VI) propylidyne and multidentate tris(2‐hydroxylbenzyl)methane ligands have been developed, which exhibit excellent stability (remains active in solution for months at room temperature), high activity, and broad functional‐group tolerance. The homodimerization and cyclooligomerization of monopropynyl or dipropynyl substrates, including challenging heterocycle substrates (e.g., pyridine), proceed efficiently at 40–55 °C in a closed system. The ligand structure and catalytic activity relationship has been investigated, which shows that the ortho groups of the multidentate phenol ligands are critical to the stability and activity of such a catalyst system.     

Dislocation behaviour during anelastic strain recovery in zinc single crystals prestrained under basal glide

Anelastic strain recovery experiments of zinc single crystals strained under basal glide were performed as a function of the forest pyramidal dislocation density at room temperature. The instantaneous strain recovery of specimens unloaded after prestraining in compression is proportional to lγ_p^1.8 where l is the average spacing between forest dislocations and γ_p is the prestrain. It is suggested that the instantaneous strain recovery results from the back motion of basal dislocations which multiplied under prestraining. The basal dislocations move to back under the influence of the internal stress unless they are impeded by intersection with forest dislocations. The time dependent strain recovery was measured on all specimens in either the unloaded or partially unloaded states, which enabled the activation volume of the process to be determined. The time dependent strain recovery is explainable in terms of the thermally activated back motion of basal dislocations via cutting the forest dislocations.