• Clean Technology
• /
• v.18 no.4
• /
• pp.419-425
• /
• 2012

This work explored the characteristics and the photocatalytic activities of S element-doped $TiO_2$ (S-$TiO_2$) and N element-doped $TiO_2$ (N-$TiO_2$) for the decomposition of gas-phase isopropyl alcohol (IPA) at sub-ppm concentrations, using a plug-flow reactor irradiated by 8-W daylight lamp or visible light-emitting-diodes (LEDs). In addition, the generation yield of acetone during photocatalytic processes for IPA at sub-ppm levels was examined. The surface characteristics of prepared S- and N-$TiO_2$ photocatalysts were analyzed to indicate that they could be effectively activated by visible-light irradiation. Regarding both types of photocatalysts, the cleaning efficiency of IPA increased as the air flow rate (AFR) was decreased. The average cleaning efficiency determined via the S-$TiO_2$ system for the AFR of 2.0 L $min^{-1}$ was 39%, whereas it was close to 100% for the AFR of 0.1 L $min^{-1}$. Regarding the N-$TiO_2$ system, the average cleaning efficiency for the AFR of 2.0 L $min^{-1}$ was above 90%, whereas it was still close to 100% for the AFR of 0.1 L $min^{-1}$. In contrast to the cleaning efficiencies of IPA, both types of photocatalysts revealed a decreasing trend in the generation yields of acetone with decreasing the AFR. Consequently, the N-$TiO_2$ system was preferred for cleaning of sub-ppm IPA to S-$TiO_2$ system and should be operated under low AFR conditions to minimize the acetone generation. In addition, 8-W daylight lamp exhibited higher cleaning efficiency of IPA than for visible LEDs.

• The Korean Journal of Mycology
• /
• v.44 no.3
• /
• pp.150-154
• /
• 2016

To determine a favorable substrate formulation for Grifola frondosa, physicochemical conditions, culture properties, and yields according to various substrate formulations were investigated. Based on these analyses, T4 (80:5:15 ratio of oak sawdust to dried bean-curd refuse to corn husk) resulted in a shorter cultivation period and higher yields (weight of fresh mushrooms harvested at maturity) than those of other treatments. The physicochemical properties of T4 were pH 5.4, 2.4% crude fat contents, 54 C/N ratio, 74.3% porosity, and 0.26 g/cm3 bulk density. These results emphasize the importance of optimal substrate development on the production efficiency of G. frondosa mushrooms and have implications for commercial applications.

• Food Science and Preservation
• /
• v.22 no.5
• /
• pp.721-726
• /
• 2015

Phellinus baumii has been used in traditional oriental medicine for the treatment of various cancer types, such as lung cancer, ovarian cancer and malignant melanoma. It has strong anti-cancer, anti-inflammatory and antioxidant activities due to its polysaccharides including glucan, schizophyllan, heteroglycan and lentinan, as well as its polyphenolics such as protocatechuic acid, caffeic acid, coumaric acid. ${\beta}$-Glucan and polyphenolics may be the most important activ ecompounds in P. baumii. Therefore, researchers have focused on these two compounds to improve their contents in extracts. In this study, P. baumii was extracted with hot-water and ethanol at different pH conditions, and their ${\beta}$-glucan contents, antioxidant activity and antioxidant contents were determined. Extraction yield was highest for the 60% ethanol extract at pH 4. The ${\beta}$-glucan contents of the hot-water extract at pH 7 was higher than those of the ethanol extracts. The antioxidant contents and antioxidant activities of the ethanol extracts were higher than those of the hot-water extracts. Extraction with 60% ethanol at pH 7 was appropriate with respect to the antioxidant capacities.

• Food Science and Preservation
• /
• v.22 no.1
• /
• pp.70-77
• /
• 2015

The physiological properties of water extracts from Hizikia fusiformis extracted using different extraction methods (water extraction, WE; autoclave extraction, AE; high pressure extraction, HPE) were investigated. The freeze-dried powder yields from HPE, AE and WE were 29.33, 27.84 and 23.63%, respectively. The $L^*$ and $b^*$ color values were higher in WE, while the $a^*$ color values were higher in WE and AE. The total sugar content of AE (60.14%) was higher than those of WE (47.10%), HPE (40.97%). The reducing sugar content (7.88%) and protein content (42.83%) of AE was higher than those of WE, and HPE. The uronic acid (5.04%), total free amino acid (785.19 mg/g), taurine (19.16 mg/g), aspartic acid (66.63 mg/g), asparagine (204.84 mg/g), alanine (188.87 mg/g) and ammonium chloride (243.91 mg/g) contents, however, were the highest in HPE. Additionally, the crude polysaccharide yield was higher in HPE (4.75%) than in AE and WE, and the crude saccharide (fucose, galactose, glucose, xylose and fucose) yields were higher in AE. It can be concluded that optimum conditions for the efficient extraction of Hizikia fusiformis depending on components are high pressure and a lower temperature than in the typical process.

• Journal of Life Science
• /
• v.26 no.8
• /
• pp.976-982
• /
• 2016

Seaweed has high growth rate, low land usage, high CO₂ absorption and no competition for food resources. Therefore, the use of lignin-free seaweed as a raw material is arising as a third generation biomass for bioethanol production. Various pretreatment techniques have been introduced to enhance the overall hydrolysis yield, and can be categorized into physical, chemical, biological, enzymatic or a combination. Thermal acid hydrolysis pretreatment is one of the most popular methods to attain high sugar yields from seaweed biomass for economic reasons. At thermal acid hydrolysis conditions, the 3,6-anhydro-galactose (AHG) from biomass could be converted to 5-hydroxymethylfurfural (HMF), which might inhibit the cell growth and decrease ethanol production. AHG is prone to decomposition into HMF, due to its acid-labile character, and subsequently into weak acids such as levulinic acid and formic acid. These inhibitors can retard yeast growth and reduce ethanol productivity during fermentation. Thus, the carbohydrates in seaweed require effective treatment methods to obtain a high concentration of monosaccharides and a low concentration of inhibitor HMF for ethanol fermentation. The efficiency of bioethanol production from the seaweed biomass hydrolysate is assessed by separate hydrolysis and fermentation (SHF). To improve the efficiency of the ethanol fermentation of mixed monosaccharides, the adaptation of yeast to high concentration of sugar could make simultaneous utilization of mixed monosaccharides for the production of ethanol from seaweed.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.16 no.1
• /
• pp.22-28
• /
• 2014

This study was conducted to investigate the photosynthetic characters of Populus alba${\times}$glandulosa cuttings in response to elevated $CO_2$ concentration and air temperature for selecting tree species adaptive to climate change. The cuttings were grown in environment controlled growth chambers with two combinations of $CO_2$ concentration and air temperature conditions: (i) $22^{\circ}C$ + $CO_2$ 380 ${\mu}mol$ $mol^{-1}$ (control) and (ii) $27^{\circ}C$ + $CO_2$ 770 ${\mu}mol$ $mol^{-1}$ (elevated) for almost three months. The cuttings under the elevated treatment showed reduced tree height and photosynthetic pigment contents such as chlorophyll and carotenoid. In particular, the elevated treatment resulted in a marked reduction in the chlorophyll a closely associated with $CO_2$ fixative reaction system. Different levels of reduction in photosynthetic characters were found under the elevated treatment. A decrease was noted in photochemical reaction system parameters: net apparent quantum yield (7%) and photosynthetic electron transport rate (14%). Moreover, a significant reduction was obvious in $CO_2$ fixative reaction system parameters: carboxylation efficiency (52%) and ribulose-1,5-bisphosphate(RuBP) regeneration rate (24%). These results suggest that the low level of photosynthetic capacity may be attributed to the decreased $CO_2$ fixative reaction system rather than photochemical reaction system.

• Korean Journal of Microbiology
• /
• v.21 no.4
• /
• pp.221-228
• /
• 1983

An improved procedure for the rapid purification of glucose-6-phosphate dehydrogenase from extracts of Saccharomyces cerevisiae was developed by using affinity chromatography. Among six affinty media tested, $NADP^+ -agarose$ and Affi-gel Blue were more effective than others (i.e., Affi-gel Red, AMP-agarose, ATP-agarose, and $NAD^+ -agarose$). Conditions to desorb the enzyme bound to the affinity media were examined to increase the purity as well as yield. The best result was obtained when the column was developed with a linear gradient of KCl (0-1.0M). In case of Affi-gel Blue, introduction of $NAD^+$ (15mM) washing step prior to the salt gradient was most effective to remove $NAD^+ -binding$ proteins. For a large scale preparation of G-6-P dehydrogenase higher recovery was obtained by Affi-gel Blue than $NADP^+ -agarose$, however, the purity of the enzyme was decreased by 10 times if the former was used as the affinity medium. The capacity of Affi-gel Blue for G-6-P dehydrogenase was found to be 5 times higher than that of $NADP^+ -agarose$. Furthermore Affi-gel Blue could be reused repeatedly and its preparation is relatively easier and less expensive than $NADP^+ -agarose$.

• Journal of the Korean Geotechnical Society
• /
• v.32 no.9
• /
• pp.51-62
• /
• 2016

Parametric studies for various site conditions by using 3d numerical model were carried out in order to estimate dynamic behavior of soil-pile-structure system in dry soil deposits. Proposed model was analyzed in time domain using FLAC3D which is commercial finite difference code to properly simulate nonlinear response of soil under strong earthquake. Mohr-Coulomb criterion was adopted as soil constitutive model. Soil nonlinearity was considered by adopting the hysteretic damping model, and an interface model which can simulate separation and slip between soil and pile was adopted. Simplified continuum modeling was used as boundary condition to reduce analysis time. Also, initial shear modulus and yield depth were appropriately determined for accurate simulation of system's nonlinear behavior. Parametric study was performed by varying weight of superstructure, pile length, pile head fixity, soil relative density with proposed numerical model. From the results of parametric study, it is identified that inertial force induced by superstructure is dominant on dynamic behavior of soil-pile-structure system and effect of kinematic force induced by soil movement was relatively small. Difference in dynamic behavior according to the pile length and pile head fixity was also numerically investigated.

• Korean Chemical Engineering Research
• /
• v.51 no.3
• /
• pp.407-410
• /
• 2013

The chlorination of a metallurgical-grade silicon was carried out in a fluidized bed reactor, 25 mm in diameter. The flow rate of the chlorine admitted into the reactor was 0.2 L/min and that of the carrier nitrogen was 0.8~1.0 L/min. The reactor temperature was maintained at $450^{\circ}C$ and the temperature of the coolant at the $SiCl_4$ condenser was at $-5^{\circ}C$. The $SiCl_4$ yield increased with increasing the mole fraction of chlorine in the feed gas, exhibiting 28% at the mole fraction of 0.2. Further increase of the chlorine mole fraction was not attempted in a worry that the reactor might be failed due to the high exothermicity of the reaction. The production of $SiCl_4$ from silicon by fluidized bed chlorination was demonstrated on a laboratory scale, which is a stepping stone for future studies under more severe conditions toward industrial application.

• KSBB Journal
• /
• v.10 no.3
• /
• pp.283-291
• /
• 1995

The characteristics of aminopeptidase M(ApM) immobilized covalently on Cellufine Formyl and the continuous production of authentic human growth hormone(hGH) from methionyl human growth hormono(met-hGH) using the column reactor packed with immobilized ApM were investigated. Immobilized ApM with the proportion of 2.3mg ApM per 1g Cellufine Formyl gel had the highest met-hGH conversion activity. The optimum pH(7.0) and temperature($55^{\circ}C$) showed no appreciable difference between free and immobilized enzymes and the optimum temperature in continuous operation of the column reactor was also found to be $55^{\circ}C$. Under the conditions at which met-hGH was converted completely to hGH, the yield and productivity were about 77% and 0.8mg hGH/ml$.$h, respectively. In two column reactors of different sizes, met-hGH was converted to hGH with the same conversion rates and hGH yields at the same space velocities. The half-life of the reactor systems at $45^{\circ}C$ and $55^{\circ}C$ were projected from the continuous operations for 90 days to be 225 days and 81 days, respectively.