Determination of potent odorants in apple by headspace gas dilution analysis

Gas chromatography-olfactometry with headspace gas dilution analysis was used to evaluate the odor potencies of volatile compounds in Fuji apple. To improve the resolution of volatile compounds, the dilution analysis was conducted on two types of capillary columns with different polarities. Thirty three and 20 compounds were identified on DB-WAX and DB-5 columns, respectively. Methyl 2-methylbutanoate, isobutyl acetate, ethyl butanoate, ethyl 2-methylbutanoate, isopentyl formate, butyl acetate and hexyl acetate as well as hexanal were important odor contributors in the headspace gas of apple on the basis of high Flavor Dilution (FD) factors. Threshold values-in-air of these compounds were also estimated from the relationships between their FD factors and concentrations. Methyl 2-methylbutanoate and ethyl 2-methylbutanote were considered as the most potent odorants because of their lowest threshold values. In addition, the threshold values-in-air of isopentyl formate, isopentyl acetate and butyl isobutanoate, which have never been reported, were estimated at 0.149, 1.95 and 0.00607 μl/l, respectively.     

Comparison of single sample methods for determination of plasma clearance using 99mTc-MAG3

We compared relationship among three single blood sampling methods which have been proposed for determination of plasma clearance with 99mTc-MAG3. Russell's and Bubeck's algorithms were employed for 48 adults (average age: 53 years) and Bubeck's and Piepsz's algorithms were used in 9 children (average age: 5.8 years). Three methods showed very high correlation among them. However, Russell's and Piepsz's methods were about 1.4 times higher than Bubeck's method in calculating plasma clearance of 99mTc-MAG3. The present study indicates that three methods discussed here are useful for the determination of plasma clearance with 99mTc-MAG3. In addition, Bubeck's method may be preferable as a reference for single plasma sampling method because of common application to adults and children.     

Mating-induced mating-type cassette conversion in Saccharomyces cerevisiae

We have previously reported that the HMRa-bearing restriction fragment of a rho degrees sir4-11 strain (HMLalpha-MATalpha-HMRa), which acts as an alpha-mater because of being rho degrees , changes its electrophoretic mobility when the strain mates with a certain group of a-mating strains (HMLalpha-MATa-HMRa). In this study, we found that the sir4-11 strain being rho degrees was not essential for this phenomenon and also that the altered form of the fragment contained HMRalpha in place of HMRa. Furthermore, we observed conversion of HMLa to HMLalpha in the cross in which a sir4-11 HMLa-MATalpha-HMRalpha strain was mated with a representative of the above-mentioned a-mating strain. In addition, when this a-mating strain was mated with a SIR(+) HMLalpha-MATa-HMRalpha strain, the resultant diploid was found to be HMLalpha/HMLalpha MATa/MATalphaHMRa/HMRalpha, indicating that conversion of MATa to MATalpha had taken place in the course of mating. From all these observations, we conclude that there is a group of S. cerevisiae strains that carries factor(s) that induces conversion of a mating-type cassette of the mating partner to alpha mating-type cassette and that this mating type cassette conversion takes place in all three mating type loci, HML, MAT and HMR, if the loci are in the non-silenced condition.     

Characteristics of neutralization of acids by newly isolated fungal cells

Soil microorganisms play an important role in maintaining soil pH at levels suitable for other soil organisms. To clarify the biological neutralization mechanism in soil, we isolated soil microorganisms showing a high ability to neutralize acids and studied their characteristics. From our taxonomic study, three isolated strains were identified as filamentous fungi, namely Mucor sp., Aspergillus fumigatus, and Aureobasidium pullulans. These strains could secrete basic materials, such as ammonia, for neutralization, grow in the medium at pH 4.0 and increase the pH of the medium to approximately 8.0. These microbial cells could neutralize not only nitric acid but also sulfuric and hydrochloric acids. The strains could also grow by utilizing nitric acid as a sole nitrogen source. In the soil containing these organisms, the pH was maintained in the neutral range by the buffering action of basic materials that they secrete. These results suggest that these fungal cells are useful for protecting the soil from acidification by acid rain.     

Spinning of the solutions of poly(vinyl alcohol)/NaCl/H2O systems and their fiber properties

The NaCl/water solutions of commercial poly(vinyl alcohol) (a-PVA) with the degrees of polymerization and saponification of 1730 and 99.39%, respectively were gel-spun into methanol (–30°C) and then the removed NaCl dry-filaments were drawn at 200°C. The draw ratio showed the maximum at NaCl concentration C _N = 3 wt% (polymer concentration C _P = 150 kg/m³). The Young's modulus and strength at break were 95 and 6 GPa ( = 19). In the case of DMSO system (C _P = 170 kg/m³), the Young's modulus was 52 GPa ( = 25) and the strength at break was 3.3 GPa. Under a polarized microscope, the fine lateral structure was observed for the DMSO system, but not for the NaCl system, that is, the smooth structure was recognized. The smooth structure, like a Netlon packing net for oranges, might be considered to result in heightening of mechanical properties.     

Evaluation of the Fracture Strength for Silicon Carbide Layers in the Tri-Isotropic-Coated Fuel Particle

A program to develop new methods to measure the fracture strength of the chemical vapor deposition SiC coatings in nuclear fuel particles has been carried out. Internal pressurization and crush test techniques were developed and applied to prototype-sized tubular and hemispherical shell specimens. The fracture strength measured from each test method applying the Weibull two-parameter distribution, and Weibull parameters were measured. It was shown that data generated with each test technique were independent of the test technique applied. This implies that the developed test methods are reliable and provide reasonable strength data. For the same material, fracture strength varied with the specimen geometry and loading configuration. These size and loading configuration effects on the fracture strength are explained with the concept of effective surface.     

Overproduction of Mpd2p suppresses the lethality of protein disulfide isomerase depletion in a CXXC sequence dependent manner

The third multicopy suppressor gene of the PDI1 deletion from Saccharomyces cerevisiae, MPD2, was isolated and characterized. The MPD2 gene encodes a protein with a putative signal sequence, ER retention signal, and a disulfide isomerase active site like sequence. The amino acid sequence around the active site like sequence is similar to the thioredoxin-like domains of PDI and PDI related proteins, although the similarity is comparatively low. A delta-pdi1 strain over-producing Mpd2p showed slow growth and was sensitive to 1 mM dithiothreitol. Mpd2p can be detected in wild type cells and is a glycoprotein. Although the MPD2 gene was not essential for growth, overexpression of the gene partially restored the maturation defect of carboxypeptidase Y caused by the PDI1 deletion. Mutagenesis analysis revealed that Mpd2p can compensate for the loss of PDI with its CXXC sequence.     

Group Symmetry in Interior-Point Methods for Semidefinite Program

A class of group symmetric Semi-Definite Program (SDP) is introduced by using the framework of group representation theory. It is proved that the central path and several search directions of primal-dual interior-point methods are group symmetric. Preservation of group symmetry along the search direction theoretically guarantees that the numerically obtained optimal solution is group symmetric. As an illustrative example, we show that the optimization problem of a symmetric truss under frequency constraints can be formulated as a group symmetric SDP. Numerical experiments using an interior-point algorithm demonstrate convergence to strictly group symmetric solutions.