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O I Takao - One of the best experts on this subject based on the ideXlab platform.

  • calculations of reduced partition function ratios of monomeric and dimeric Boric Acids and borates by the ab initio molecular orbital theory
    Journal of Nuclear Science and Technology, 2000
    Co-Authors: O I Takao
    Abstract:

    With the final goal to elucidate boron isotope fractionation observed experimentally, molecular orbital calculations were performed on Boric acid and borate monomers and dimers. The geometries of B(OH)3 and B(OH)4 − were first optimized and their vibrational frequencies were calculated at their optimized structures. The estimated 11B-to-10B isotopic reduced partition function ratios (RPFRs) of B(OH)3 and B(OH)4 − and the calculated equilibrium constant of the boron isotope exchange reaction between the two boron species revealed that a more advanced molecular orbital theory with a higher level basis set did not necessarily yield better results. It was concluded that HF/6-31G(d) calculations were most appropriate for the present purpose. The RPFRs of the dimers, H4B2O5, H5B2O6AJA- and H6B2AJA-, estimated from the RPFRs of the monomers by the use of additivity of the logarithm of RPFRs agreed with those calculated using the frequencies of the dimers within a margin of 1%. This error corresponded to the erro...

J A Tossell - One of the best experts on this subject based on the ideXlab platform.

  • ab initio molecular orbital calculations for boron isotope fractionations on Boric Acids and borates
    Geochimica et Cosmochimica Acta, 2005
    Co-Authors: Yun Liu, J A Tossell
    Abstract:

    Abstract Ab initio quantum chemistry calculations have been performed on the isotopic exchange reaction between B(OH) 3 and B(OH) 4 − . Several calculation methods have been carefully compared and evaluated. The “water-droplet” method is chosen to investigate this isotope exchange reaction using cluster models with up to 34 water molecules surrounding the solute. HF/6-31G* level calculations coupled with a 0.920 scaling factor are used for the frequency calculations. A larger K value (1.027) is obtained from this study compared to the commonly used 1.0194 (Kakihana et al., 1977). The fractionations for several Boric acid polymers and boron minerals are also studied. Our results suggest that assuming the BO 4 bonding in B(OH) 4 − is identical to that in borosilicates is wrong. Tetrahedral boron in silicates has a significantly smaller reduced isotopic partition function ratio (RPFR) and hence will be much isotopically lighter than in B(OH) 4 − . The new theoretical curve of pH vs. δ 11 B composition of B(OH) 4 − using our calculated 1.027 can be used to predict pH values for equilibrium cases such as incorporation into inorganic calcite. We also find that the shape of this curve is very sensitive to both K and p K a value, giving the possibility of also predicting salinity from the different shapes of the curve.

Ashkan Yazdani - One of the best experts on this subject based on the ideXlab platform.

  • Anodizing of 2024-T3 aluminum alloy in sulfuric-Boric-phosphoric Acids and its corrosion behavior
    Transactions of Nonferrous Metals Society of China (English Edition), 2013
    Co-Authors: M. Saeedikhani, Malihe Javidi, Ashkan Yazdani
    Abstract:

    The corrosion resistance of 2024-T3 aluminum alloy was improved by anodizing treatment in a mixed electrolyte containing 10% sulfuric acid, 5% Boric acid and 2% phosphoric acid. Electrochemical impedance spectroscopy (EIS) technique was used to study the corrosion behavior of the anodized alloy. Using Tafel plot and salt spray techniques, it is revealed that the anodizing treatment of 2024-T3 aluminum alloy in sulfuric-Boric-phosphoric Acids provides better corrosion resistance and durability in comparison with the anodizing treatment in phosphoric acid or sulfuric-Boric Acids. This electrolyte can be a suitable alternative for chromate baths which are generally used in the anodizing of aluminum alloys.

Hiroyuki Ohno - One of the best experts on this subject based on the ideXlab platform.

  • enhanced ionic conduction in organoboron ion gels facilely designed via condensation of cellulose with Boric Acids in ionic liquids
    Polymer Journal, 2009
    Co-Authors: Noriyoshi Matsumi, Yusuke Nakamura, Keigo Aoi, Takeshi Watanabe, Tomonobu Mizumo, Hiroyuki Ohno
    Abstract:

    Novel ion-gels bearing lithium borate were synthesized via condensation between cellulose and Boric Acids in IL. Ion-gels obtained showed high ionic conductivity comparable to IL itself. First, ion-gels containing 5 wt % and 7 wt % of cellulose were prepared in 1-allyl-3-ethylimidazolium chloride. Their ionic conductivities were evaluated by ac-impedance method after drying ion-gels thoroughly. The ion-gel including 5 wt % of cellulose exhibited higher conductivity than that including 7 wt % of cellulose. This should be because of lower activating energy under lower composition of cellulose. The effect of concentration of C6F5B(OH)2 on ionic conductivity was also examined with varying the ratio of B(OH)3 and C6F5B(OH)2. It was demonstrated that the ion-gel including greater amount of pentafluorophenylborate showed significantly enhanced ionic conductivity. Preparation of ion-gels including 1-allyl-3-ethylimidazolium formate was also examined at the cellulose concentration of 7wt%. The ion-gels synthesized in 1-allyl-3-ethylimidazolium formate showed higher ionic conductivity (1.98 x 10-3 Scm-1; 30°C) than that synthesized in 1-allyl-3-ethylimidazolium chloride. This should be because of lower viscosity of 1-allyl-3-ethylimidazolium formate.

Tony D James - One of the best experts on this subject based on the ideXlab platform.