Twenty-five Saccharomyces cerevisiae strains were screened for the highest sugar tolerance, ethanol-tolerance, ethanol production, and inhibitor resistance, and S. cerevisiae KL5 was selected as the best strain. Inhibitor cocktail (100%) was composed of 75 mM formic acid, 75 mM acetic acid, 30 mM furfural, 30 mM hydroxymethyl furfural (HMF), and 2.7 mM vanillin. The cells of strain KL5 were treated with γ-irradiation, and among the survivals, KL5- G2 with improved inhibitor resistance and the highest ethanol yield in the presence of inhibitor cocktail was selected. The KL5-G2 strain was adapted to inhibitor cocktail by sequential transfer of cultures to a minimal YNB medium containing increasing concentrations of inhibitor cocktail. After 10 times of adaptation, most of the isolated colonies could grow in YNB with 80% inhibitor cocktail, whereas the parental KL5 strain could not grow at all. Among the various adapted strains, the best strain (KL5-G2-A9) producing the highest ethanol yield in the presence of inhibitor cocktail was selected. In a complex YP medium containing 60% inhibitor cocktail and 5% glucose, the theoretical yield and productivity (at 48 h) of KL5- G2-A9 were 81.3% and 0.304 g/l/h, respectively, whereas those of KL5 were 20.8% and 0.072 g/l/h, respectively. KL5-G2-A9 reduced the concentrations of HMF, furfural, and vanillin in the medium in much faster rates than KL5.
We experimentally investigate the periodic vortex shedding dynamics in a highly oblate Bose-Einstein condensate using a moving penetrable Gaussian obstacle. The shedding frequency fv is measured as a function of the obstacle velocity v and characterized by a linear relationship of fv = a(v − vc) with vc being the critical velocity. The proportionality constant a is linearly decreased with a decrease in the obstacle strength, whereas vc approaches the speed of sound. When the obstacle size increases, both a and vc are decreased. The critical vortex shedding is further investigated for an oscillating obstacle and found to be consistent with the measured fv. When the obstacle's maximum velocity exceeds vc but its oscillation amplitude is not large enough to create a vortex dipole, we observe that vortices are generated in the low-density boundary region of the trapped condensate, which is attributed to the phonon emission from the oscillating obstacle. Finally, we discuss a possible asymptotic association of a with the Strouhal number in the context of universal shedding dynamics of a superfluid.
This study uses long-term field measurements to quantify the indoor humidity generation rates of low-income households vulnerable to condensation and related problems. We found that the mean internal moisture excess of low-income households in Korea was 4.69 g/m3 higher than those of prior studies. Indoor water vapor generation rates of various activities considering the life style of low-income households were also quantified. The moisture generation rates of the shower and bath were 125.3 g/event and 51.1 g/event, respectively, and showed a similar or lower value compared to the existing results. The moisture generation rate of cooking showed the largest difference due to the residential characteristics of low-income households, such as cooking less frequently due to meal delivery services from the welfare center and the lower number of residents per household. Even though the moisture generation rates of low-income households for certain activities showed lower values compared to the results of prior studies, the indoor conditions were very humid due to the lower ventilation rates and studio-type open floor plan.
The contents of starch, moisture, crude protein, crude fat, crude fiber, and ash of different varieties of potatoes were analyzed. The average starch contents of Go-woon, Ha-ryoung, Dae-seo, Jo-won, Ga-won potatoes were 17.9±0.2, 18.0±1.7, 17.7±0.5, 14.8±0.4, and 16.2±1.0%, respectively. The ground powder of each starchy substrate was suspended in distilled water, and then liquefied, saccharified, and fermented by Saccharomyces cerevisiae ATCC26603 at 30℃ for 4 days. By statistical analysis, the effectiveness of the contents of the different components of the potato tubers on the ethanol production were examined. The results showed that the starch content positively affected the ethanol production. while moisture content affected negatively the ethanol production. Ethanol production from the 5 different varieties of potato tubers harvested on different time were examined and the results indicated that both of potato variety and the harvesting-time significantly affected the ethanol production. Among the several varieties of potato, Ha-ryoung produced the highest yield of ethanol as much as 94.3±1.9 L/ton or 3111±62.7 L/ha.
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