Stable disruption of ethanol production by deletion of the genes encoding alcohol dehydrogenase isozymes in Saccharomyces cerevisiae

We analyzed the effects of the deletions of genes encoding alcohol dehydrogenase (ADH) isozymes of Saccharomyces cerevisiae. The decrease in ethanol production by ADH1 deletion alone could be partially compensated by the upregulation of other isozyme genes, while the deletion of all known ADH isozyme genes stably disrupted ethanol production.     

The Formation of β‐Damascenone in Sweet Potato Shochu

The formation of β‐damascenone during shochu manufacture was investigated by quantifying β‐damascenone at each stage of manufacturing. Steamed sweet potato has a low level of free β‐damascenone (0.02–0.1 μg/g). During fermentation, β‐damascenone was produced in small quantities that were degraded by yeast. Thus, the second mash accumulates little free β‐damascenone (approximately 17 μg/L). The concentration profile in the fractionated distillate showed that β‐damascenone was produced during heating. Most β‐damascenone in shochu was formed during distillation, not during steam heating and fermentation. It is suggested that the level of β‐damascenone in shochu could be increased by reducing the pH of the second mash and prolonging the distillation period. Sweet potato cultivars differed in total free and hydrolyzed β‐damascenone content and there was a strong association between each cultivar and its shochu β‐damascenone content. The selection of the sweet potato cultivar is important for determining the quantity of β‐damascenone in a shochu brew.     

Study of deep oxidation and sulfonation of graphene oxide as low-temperature fuel cell electrolyte

In order improve the fuel cell performance of a free-standing graphene oxide (GO) membrane, the impacts of both the additional oxidation of GO and the modification with vinilsulfonic acid were investigated. The modification with vinilsulfonic acid was conducted with and without adding potassium persulfate, K₂S₂O₈, which is a radical initiator for the polymerization of vinylsulfonate. A total of six types of free-standing GO membranes with and without the oxidation and/or the modification were prepared. The oxidation and the modification additively increased the proton conductivity, and the oxidation significantly improved the durability of the fuel cell performance at 30 °C. The membrane of GOhvsi, of which GO was oxidized and modified with the initiator, showed very high in-plane proton conductivities at 30 °C, i.e., 0.54 S cm^?1 at RH 100%. The H₂–O₂ fuel cell using GOhvsi showed maximum power densities as high as 136 mW cm^?2 and 184 mW cm^?2 at 30 °C and 50 °C, respectively. The performance at 30 °C was stable for more than 20 h. The improved durability by the oxidation was attributed to the increased defects of carbon based on an XPS analysis. The TPD-MS analysis suggested that the oxygenated functional groups at the defects would increase the binding strength.     

Electrochemical and magnetic studies of Cr- or Co-substituted Li-Mn-Ni spinel oxides

LiMn_1.5−xM_2xNi_0.5−xO₄ (M = Co or Cr, 0.0 ≤ x ≤ 0.2) compounds were synthesized by the sol-gel method. It is found from X-ray diffraction analysis that single spinel phases are obtained for both Cr³⁺- and Co³⁺-substitution, but a small cation mixing between the 8a and 16d sites is found only in the Co³⁺-substitution case. All of the compounds exhibit M-T curves characteristic of ferromagnetic materials. As the substitution degree is raised, the saturation magnetization at 4.2 K decreases and the Curie temperature shifts lower, irrespective of the kind of the substituent. That is, the cation substitution yields a reduction of the ferromagnetism. Additionally, both Cr³⁺- and Co³⁺-substitution have a large influence on the electrochemical properties. The Cr³⁺-substitution induces a rise in the average operating potential without a loss of redox capacity, while both the average operating potential and the redox capacity decrease with an increase in the Co³⁺-substitution degree.     

Improvement in pulping and bleaching properties of xylem from transgenic tobacco plants

In an attempt to improve the pulping properties of xylem pieces and the bleaching properties of the resultant pulp, we compared two lines of transgenic tobacco in which the biosynthesis of lignin had been altered by suppression of the activity of 4‐coumarate: CoA ligase (4CL). The results of Kraft pulping on a laboratory scale indicated that the xylem of transgenic tobacco exhibited a higher delignification efficiency than that of corresponding controls subjected to the same conditions. This facilitated delignification was accompanied by a high pulp yield, but there was no excessive degradation of cellulose in the pulp fibres. The unbleached pulps from the 4CL‐suppressed tobacco plants were easily bleached with a lower consumption of chemicals than was required for the controls. Furthermore, the strength and optical properties of handsheets prepared from the 4CL‐suppressed tobacco plants were similar to those of handsheets prepared from the controls. Our observations suggest that modification of lignin by genetic engineering of the suppression of 4CL activity should result in both an increased pulping yield and a saving of bleaching reagent. © 2002 Society of Chemical Industry     

Growth and properties of SiGe multicrystals with microscopic compositional distribution for high-efficiency solar cells

The growth technique and physical properties of SiGe multicrystals with microscopic compositional distribution are demonstrated for new high-efficiency solar cells in which the wavelength dependence of the absorption coefficient can be freely designed by controlling the compositional distribution in the SiGe multicrystals. This growth technique is suitable for the practical casting method, and it is made up of melt growth of SiGe multicrystals with wide and microscopic distribution of the composition from Si to Ge all over the crystals. It is studied how much widely the microscopic compositional distribution in SiGe multicrystals grown from binary Si–Ge melts can be controlled by the melt composition and the cooling process. The range of the microscopic compositional distribution becomes wider as the starting Si concentration in the growth melt becomes larger. SiGe multicrystals with various microscopic compositional distribution can be freely controlled by optimizing the melt composition and the cooling process. The wavelength dependence of the absorption coefficient of such SiGe multicrystals can also be freely designed. Using the experimentally determined absorption coefficient of a SiGe crystal with microscopic compositional distribution, the short circuit photo-current of solar cells was calculated and it is demonstrated that the short circuit photo-current can be much larger for SiGe with microscopic compositional distribution than for SiGe with uniform composition. Si thin film can be easily grown on such a SiGe multicrystal and the Si/SiGe heterostructure can be obtained. These results show that SiGe multicrystals with microscopic compositional distribution are hopeful for new high-efficiency solar cell applications by using the practical casting method.     

Characteristic odour compounds in shochu derived from rice koji

Shochu, a traditional Japanese distilled liquor, makes use of rice koji, which is koji mould grown on rice grain. Rice koji is an essential ingredient of Japanese liquors such as shochu, and it plays a role as a source of the enzyme to degrade starch. However, there has been no research on the effect of rice koji on the flavour of shochu. Therefore, in this study, the volatile compounds in shochu derived from rice koji were investigated. Two shochu samples were prepared to assess the contribution of rice koji to the flavour. One shochu sample was prepared from rice koji, yeast and water (rice koji‐shochu). The other shochu sample was obtained from steamed rice and various enzymes instead of rice koji (enzyme‐shochu), along with yeast and water. The volatile compounds were analysed by gas chromatography–mass spectrometry (GC‐MS) and GC‐MS/olfactometry with aroma extract dilution analysis. The results showed that enzyme‐shochu had a higher flavour dilution value of dimethyl trisulphide and hexanal, whereas rice koji‐shochu had a higher flavour dilution value of some ester compounds that imparted aromatic odours such as fruity. Some unknown peaks representing compounds that impart characteristic odours such as soda, potato, lavender, and tea‐like were specifically detected in rice koji‐shochu. The concentrations and calculated odour active values of 14 compounds were measured. These results showed that isovaleraldehyde, ethyl caprylate, ethyl caproate and ethyl 2‐methylbutyrate played an important role in imparting the specific odour of rice koji‐shochu. Copyright © 2016 The Institute of Brewing & Distilling     

Transient Thermal Stress Problem of a Functionally Graded Magneto-Electro-Thermoelastic Hollow Cylinder Due to a Uniform Surface Heating

This article is concerned with the theoretical analysis of the functionally graded magneto-electro-thermoelastic hollow cylinder due to uniform surface heating. We analyze the transient thermal stress problem for a functionally graded hollow cylinder constructed of the anisotropic and linear magneto-electro-thermoelastic materials using a laminated composite model as one of theoretical approximation under a plane strain state. As an illustration, we carry out numerical calculations for a functionally graded hollow cylinder constructed of piezoelectric and magnetostrictive materials and examined the behaviors in the transient state. We investigate the effects of the nonhomogeneity of material on the stresses, electric potential, and magnetic potential, and the effect of the applied electric potential on the thermal stress σ_θθ.     

Determination of benzylaminopurine in agricultural products

A simplified method for the determination of benzylaminopurine in agricultural products by LC/MS was investigated. Benzylaminopurine in agricultural products was extracted with acetone and the extract was concentrated to below 30 mL. Buffer solution of pH 9.0 and ethyl acetate were added to the residue, and the solution was shaken. The ethyl acetate layer was evaporated to dryness, and the residue was dissolved in acetone-n-hexane (1 : 1). The solution was applied to a SAX/PSA mini-column, which was then rinsed with acetone-n-hexane (1 : 1). Benzylaminopurine was eluted with acetone-n-hexane (1 : 1) containing 1% water. The eluates were evaporated to dryness, and the residue was dissolved in 10 mmol/L ammonium acetate-methanol (1 : 1). Benzylaminopurine was analyzed by LC/MS. The MS detection was performed in the selected ion monitoring (SIM) mode, with detection of the M+H(+) ion of benzylaminopurine (m/z 226) generated by electrospray ionization (ESI). Recoveries of benzylaminopurine from 15 agricultural products were in the range of 83.1-97.2%. The limits of detection (S/N=3) of benzylaminopurine in all samples except green tea and in green tea were 0.0003 and 0.0012 microg/g, respectively.