The production of gluconic acid was carried out with high catalase containing Aspergillus niger mutant. This osmofil strain enables to convert the concentrated solutions of D-glucose (300g/l) to D-gluconic acid without gasing using hydrogen peroxide as oxygen source. A controlled addition of hydrogen peroxide based on the pO₂ measurement was performed. The conversion of 300g/l glucose solution was achieved with 7 hours and triple conversion (with biomass recycling) within 27 hours with yield with regard to the substrate over 98%. Kinetics of inactivation of glucose oxidasecatalase complex as a whole was examined. Some general factors influencing the inactivation of glucose oxidase and catalase in mycelium are discussed.

Internal oxidation of dilute silver alloys containing Al, Mg, Zn, Cu, and Sn was studied in air at temperatures between 573 K and 1173 K. Electrical resistivity, gravimetric, and gas-extraction measurements were made. The general trend of the resistivity is that it increases upon oxidation at lower temperatures and the resistivity decreases at higher temperatures in all of these alloys except Ag-Mg, in which it increases even at 1173 K. The increase in resistivity is considered to be related to the formation of clusters having excess oxygen. A detailed investigation was performed on Ag-Al alloys. The O/Al ratio in the clusters in Ag-2.2 at.% Al is much higher on oxidation at 773 K than for stoichiometric Al₂O₃ at 1173 K. The clusters release the excess oxygen on subsequent annealing at high temperatures, and decompose to stable Al₂O₃ at 1173 K.

Studies have shown that plots of the log of the distribution ratio versus pH for the distribution of uranium(VI) between non-plasticized and TBP-plasticized dibenzoylmethane-loaded polyurethane foams and dilute aqueous uranium(VI) solutions have a limiting slope of 0.6 at equilibrium pH values ≤4 and reach a maximum distribution constant at about pH 6.0. The results indicate that the extracted complex is a simple chelate, UO₂Me₂, where HMe denotes dibenzoylmethane. Plasticization of the foam with TBP has been found to significantly enhance the rate of extraction.

Summary

The enantioselectivity of the α₁ glycoprotein chiral stationary phase, Chiral AGP^® has been evaluated for a number of β-blocking agents. A correlation has been found between the retention behaviour on this stationary phase and the hydrophobicity of the compounds. The separation factor α is higher for compounds that are well retained. Retention, and thus α, are also controlled by pH and the percentage of organic modifier in the mobile phase.

Ethanol (EtOH) is being evaluated as an alternate solvent to hexane for the extraction of glanded cottonseed. Hot EtOH, needed for efficient oil and aflatoxin extraction, binds gossypol to protein. However, this binding can be minimized by acidifying aqueous EtOH with a tribasic acid, such as phosphoric or citric. While this solvent extracts oil and gossypol, it does not affect EtOH’s ability to extract aflatoxin. The defatted cottonseed meals produced from this process contained 0.03% total gossypol (which is lower than meal prepared by most other processes) and the aflatoxin content was reduced from 69 to 2.9 ppb. These are preliminary results and additional research is needed to determine commercial feasibility. The removal of essentially all gossypol from an extracted meal has the potential to expand the use of cottonseed meal as a feed, increasing its value to both the cotton farmer and the seed processor.

Summary

Handy et al. have shown that the asymptotic behavior of Hartree-Fock orbitals is controlled by the energy of highest occupied molecular orbital, except for the atomic case in which onlys-orbitals are occupied. However, their proof is not complete at one point. This point is clarified, and a more unified derivation is given. Further, we discuss the preexponential factorr^α of the leading asymptotic termr^α exp[−βr], where β=(−2ε_HOMO)^1/2 and ε_HOMO is the orbital energy of HOMO. New results are obtained for linear molecules, and the results of several authors for atoms and non-linear molecules are reproduced.

Summary

A standardized method to determine the vitamin D content of food by means of HPLC is described. After the test material was homogenized and saponified with ethanolic aqueous potassium hydroxide solution, vitamin D was extracted usingn-hexane. Using HPLC on a silica gel column, the fraction containing vitamin D is separated from the nonsaponifiable residue. After the fraction was reduced, the residue was dissolved in methanol and the vitamin D content determined after HPLC separation on an RP-C₁₈ column. For evaluation, either a conventional external standard method using laboratory and matrix specific recovery rates as correction factors, or an internal standard method using vitamin D₂, and D₃, respectively as internal standards were employed. The method was developed and standardized by the working group “Vitamin Analysis” in accordance with § 35 LMBG (German Food Act). Repeatability and comparability of the results were checked in collaborative studies (14 laboratories) in milk powder and gruel that had been enriched with vitamin D₃. Applicability of the method to other food (eggs, milk, fish, margarine) was checked separately. The statistical evalution of the results of the collaborative studies has shown that the method is reliable enough to be included into the “Amtliche Sammlung” (official collection of analytical methods) according to § 35 LMBG. The present method may be used to determine the content of vitamin D₂ and D₃ in natural and vitaminized food. It is specific for the vitamins D₂ and D₃ released during saponification of food, but does not allow separate determination of the pre-vitamins D already present in the sample.

A series of V₂O₅/TiO₂/SiO₂ catalysts were structurally investigated byin situ Raman spectroscopy and chemically probed by methanol oxidation in order to determine the molecular structure-reactivity relationships of the V₂O₅/TiO₂/SiO₂ catalysts. Only surface TiO_x species are present on the 3% TiO₂/SiO₂ catalysts, and the surface TiO_x species as well as bulk TiO₂ (anatase) particles coexist on the 40% TiO₂/SiO₂ catalyst. The deposition of 1–3% vanadium oxide onto 3% TiO₂/SiO₂ and 4% vanadium oxide onto 40% TiO₂/SiO₂ forms only a surface vanadium oxide phase.In situ Raman studies reveal that the surface vanadium oxide species preferentially exist on the titania sites of the TiO₂/SiO₂ system. The interaction between the surface vanadia and the surface titania overlayer on SiO₂ increases the methanol oxidation reactivity by two orders of magnitude relative to V₂O₅/SiO₂. In the presence of bulk TiO₂ (anatase) particles on the SiO₇ support, the reactivity of the surface vanadia further increases by an order magnitude relative to the catalysts containing only surface titania, and is close to that of surface vanadia on bulk TiO₂. This suggests that the surface VO_x-TiO₂ (bulk) interactions results in a more active site than the surface VO_x-TiO_x-SiO₂ interactions. In addition, the V₂O₅/TiO₂/SiO₂ catalysts exhibit high selectivity towards HCHO because redox sites are predominant on the surface of these catalysts with essentially no acid site present.