Adsorption structure of acetic anhydride on a TiO2(1 1 0) surface observed by scanning tunneling microscopy

The carboxylic acids are stably adsorbed on TiO₂(1 1 0) surfaces at room temperature. To demonstrate the neutralization mechanism proposed by Ashima et al. [H. Ashima, W.-J. Chun, K. Asakura, Surf. Sci. 601 (2007) 1822.] that explains the stable adsorption of carboxylic acids, we studied the full-coverage adsorption structure of acetic anhydride on a TiO₂(1 1 0) surface by STM (scanning tunneling microscopy). We directly observed three postulated species on the TiO₂(1 1 0) surface; normal acetates (termed acetate A) forming a (2 × 1) ordered structure, a minor acetate species (termed acetate B) which was present between the bridging oxygen and the 5-fold Ti, and the oxygen vacancies. We determined the ratio of these three species. This ratio was in good agreement with the postulated conversion reaction of acetate B to A.     

Revised spin-parity assignment and a new interpretation of the high-spin isomer in 151Er

The high-spin isomer in ¹⁵¹Er ( E _x = 10.3 MeV, T _1/2 = 420 ns) has been studied by the ¹¹⁶Sn ( ⁴⁰Ar , 5n) ¹⁵¹Er reaction at 197MeV. From the $ \gamma \gamma$ coincidence relations, a new transition with an energy of 1514keV was found. This finding requires the revision of the spin-parity assignment from previous 67/2^- to 61/2⁺ or 65/2^- . The 61/2⁺ assignment is the one which was predicted by the deformed independent particle model as an isomer with a large oblate deformation ( $ \beta$ = - 0.17) of the $\ensuremath[\nu(f_{7/2}h_{9/2} i_{13/2}) \pi(h^4_{11/2})]_{61/2^+}$ configuration. The isomerism may be attributed to the sudden shape change of the isomer from the nearly spherical shape of the lower-spin yrast states to the oblate shape.     

Synthesis of pyrone-annulated 2-oxabicyclo[3.3.1]nonanes by palladium-catalyzed cyclization of 4-hydroxy-2-pyrones with allylic bisacetates

Cyclization of 4-hydroxy-2-pyrones with allylic bisacetates by a palladium catalyst is described. Pyrone-annulated 2-oxabicyclo[3.3.1]nonane derivatives were regioselectively produced from the reaction of 4-hydroxy-2-pyrones with 1,4-diacetoxy-2-cyclohexene at high temperature. The reaction would proceed via a migration of the π-allylpalladium intermediate.     

The birch reduction of heterocyclic compounds V Birch reduction of 2‐ and 5‐acylfuran‐3‐carboxylic acids and reductive elimination of 2‐(arylmethoxymethyl)furan‐3‐carboxylic acids

The Birch reduction of 2‐ and 5‐acylfuran‐3‐carboxylic acid 1 and 4 gave 2‐acyl‐2,3‐dihydrofuran‐3‐carboxylic acid 2 and 5‐acyltetrahydrofuran‐3‐carboxylic acid 5 , respectively. Further examination of the reductive elimination was also studied on 2‐(arylmethoxymethyl)furan‐3‐carboxylic acids 7.     

Tailored coupled cluster singles and doubles method applied to calculations on molecular structure and harmonic vibrational frequencies of ozone

To assess the separation of dynamic and nondynamic correlations and orbital choice, we calculate the molecular structure and harmonic vibrational frequencies of ozone with the recently developed tailored coupled cluster singles and doubles method (TCCSD). We employ the Hartree-Fock and complete active space (CAS) self-consistent field (SCF) orbitals to perform TCCSD calculations. When using the Hartree-Fock orbitals, it is difficult to reproduce the experimental vibrational frequency of the asymmetric stretching mode. On the other hand, the TCCSD based on the CASSCF orbitals in a correlation consistent polarized valence triple zeta basis yields excellent results with the two symmetric vibrations differing from the experimental harmonic values by 2 cm(-1) and the asymmetric vibration differing by 9 cm(-1).     

Generation of superoxide anions during the reaction of guanidino compounds with methylglyoxal

Uremic toxins are accumulated in the blood of patients with chronic renal failure (CRF), although alteration of the toxicity by the interaction of various uremic retention products has not been precisely clarified. In this study, we found that cytochrome c added to incubation mixtures containing guanidino compounds and methylglyoxal in phosphate buffer solution (pH 7.4) resulted in reduction of cytochrome c. Superoxide anions were generated from incubation mixtures of each guanidino compound with methylglyoxal, because the reduction was inhibited by the addition of superoxide dismutase. The incubation mixture containing each guanidino compound and methylglyoxal had different rates of generation of the superoxide anion from other mixtures. A relatively higher superoxide anion formation rate was observed in the incubation mixture containing Arg and methylglyoxal (7.9 +/- 0.5nmol x m(-1) x min(-1)), or in the incubation mixture containing methylguanidine and methylglyoxal (6.3 +/- 0.6 nmol x ml(-1) min(-1)). These findings suggest that interactions of various uremic retention products which accumulate in the blood of uremic patients may generate reactive oxygen species and may be involved in the oxidative stress observed in CRF patients. The addition of aminoguanidine, which is known to inhibit the formation of advanced glycation end products, to a mixture of guanidino compounds and methylglyoxal inhibited reactions between guanidino compounds and methylglyoxal.     

Amperometric response to reducing carbohydrates of an enzyme electrode based on oligosaccharide dehydrogenase. Detection of lactose and α-amylase

A mediated amperometric enzyme electrode, which was constructed by immobilizing oligosacharide dehydrogenase behind a dialysis membrane on the surface of a carbon paste electrode containing p-benzoquinone, showed a current response to d-xylose, d-galactose, d-mannose, lactose, maltose, maltotriose, maltopentaose and maltohexaose. The sensitivity of the current response to these carbohydrates was dependent on the kinetics of the immobilized enzyme reaction and/or the permeation rate of the substrate through the dialysis membrane. Hence the sensitivity could be varied by controlling the amount of the immobilized enzyme and the thickness of the dialysis membrane. The time dependence of the current response ofthe enzyme electrode with a large amount of the immobilized enzyme and a thicker dialysis membrane could be explained by an equation describing diffusion of the substrate in the membrane. The enzyme electrode was used to measure lactose in milk and to assay α-amylase in standard serum.