Anion-exchange separation and spectrophotometric determination of vanadium in silicate rocks

A combined anion-exchange-spectrophotometric method has been developed for the determination of vanadium in silicate rocks. A rock sample weighing about 0.1 g is decomposed with a mixture of sulphuric and hydrofluoric acids and after removal of HF the residue is taken up with dilute sulphuric acid. This solution is adjusted to be 0.05M in sulphuric acid and contain 0.3% hydrogen peroxide, and is passed through a column of Amberlite CG 400 (sulphate form). The sorbed vanadium is eluted with 30 ml of 1M hydrochloric acid. The effluent is evaporated to dryness, made 0.1M in hydrochloric acid and 3% in hydrogen peroxide content, and passed through a column of Amberlite CG 400 (chloride form) to get rid of accompanying thorium and zirconium. Vanadium is stripped by elution with 20 ml of 1M hydrochloric acid and subsequently determined spectrophotometrically with 4-(2-pyridylazo)resorcinol. The detection limit is 0.4 ppm.     

Spin-polarized Dirac-cone-like surface state with d character at W(110)

The surface of W(110) exhibits a Dirac-cone-like state with d character within a spin-orbit-induced symmetry gap. As a function of the wave vector parallel to the surface, it shows a nearly massless energy dispersion and a pronounced spin polarization, which is antisymmetric with respect to the Brillouin zone center. In addition, the observed constant energy contours are strongly anisotropic for all energies. This discovery opens new pathways to the study of surface spin-density waves arising from a strong Fermi surface nesting as well as d-electron-based topological properties.     

Results from GRACE/SUSY at one-loop

We report the recent development on the SUSY calculations with the help of GRACE system. GRACE/SUSY/1LOOP is the computer code which can generate Feynman diagrams in the MSSM automatically and compute one-loop amplitudes in the numerical way. We present new results of various two-body decay widths and chargino pair production at ILC (international linear collider) at one-loop level.      

Di-isotacticity of poly(methyl propenyl ether) and double-bond opening of methyl propenyl ether in cationic polymerization

The di-isotacticity of poly(methylpropenyl ether) obtained by the cationic polymerization has been studied by NMR spectra. The NMR spectra of β-methyl protons of the polymer are decoupled from the β-methine proton spectra to determine the di-isotactic fraction in a polymer. The signals of β-methyl protons at 8.78 and 8.89 τ are estimated as spectra based on threo- and erythro-di-isotactic diads, respectively. With BF₃·O(C₂H₅)₂ as a catalyst, the trans monomer yields a crystalline polymer and its structure is threo-di-isotactic. Otherwise, cis monomer produces an amorphous polymer, and it is a mixture of threo- and erythro-di-isotactic structure. From these results, it is concluded that the double bond in trans monomer is opened exclusively in the cis type, and in cis monomer cis- and trans-openings take place at almost the same rate.     

Design of New Reaction Fields for Spherical Polypyrrole Particle Synthesis

Summary: Polypyrrole conducting polymers have been investigated widely for various applications because of their thermal and environmental stability and good electrical conductivity. Using chemical oxidative polymerization for the synthesis of polypyrrole particles, the reaction rate is very fast. In this study, we designed two new reaction fields for the synthesis of spherical polypyrrole nanoparticles. In the first system, oxidative polymerization of monomer droplets infused in a water/oil (W/O) emulsion reaction field was investigated. The second system employed dispersed monomer in an aqueous solution with a low concentration of oxidant in which polymerization was augmented by ultrasonic irradiation. Effective control of the reaction rate was important for enabling the synthesis of fine spherical polypyrrole particles.     

Effects of Temperature and Mobile Phase Condition on Chiral Recognition of Poly(l-phenylalanine) Chiral Stationary Phase

Characteristics of the chiral stationary phase with poly(l-phenylalanine) peptide selector, which was in ??-helical state, was reported. Since environmental factors affect peptide conformation, the changes in enantioselectivity were examined depending on column temperature and mobile phase conditions (ionic strength, pH, mobile phase composition). Column temperature and pH drastically affected the enantioselectivity. Based on these changes, the relation between chiral recognition and secondary structure of the peptide selector was discussed. The column stability during sequential analysis under different separation conditions was also evaluated.     

Molecular Chirality Recognized by Achiral Compounds

Abstract

Three cases are described where chirality is recognized by achiral molecules, where chirality is induced into achiral compounds through interactions with chiral compounds, and lastly where induced chirality in the solid-state is utilized for an enantio-selective photoreaction. In the first instance, the thermodynamically and kinetically preferred diastereoisomer of an optically labile chromium complex depended on the nature of the achiral solvent. In the second case, for the first time 1,2-chloroethane was trapped and observed in a chiral near-eclipsed form and 1-chloropropane in the truly eclipsed form at room temperature in a 1:1 inclusion complex with an optically active host molecule. Finally, induced chirality in a prochiral compound in the solid-state was successfully employed in an enantio-selective photoreaction. In the two cases, solid-state CD provided valuable information.     

Bis(μ‐6‐hydroxy­picolinato)‐μ‐oxo‐bis­[di­pyridine­manganese(III)] monohydrate

The title compound, [Mn₂(μ‐O)(C₆H₃NO₃)₂(C₅H₅N)₄]·H₂O, was isolated from the reaction of 2,6‐pyridine­di­carboxylic acid with [Mn₁₂O₁₂(CH₃COO)₁₆(H₂O)₄] in pyridine. The dimanganese complex has twofold symmetry; the Mn^III atoms are bridged by one oxo and two amidate ligands and show compressed octahedral Jahn–Teller distortion. The molecular packing comprises a three‐dimensional structure constructed by means of extensive intermolecular interactions, including three kinds of hydrogen bonds and π–π interactions.