• Journal of the Korean Wood Science and Technology
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• v.43 no.6
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• pp.838-850
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• 2015

In this study, dilute acid pretreatment was operated using small-diameter Quercus mongolica for evaluating the yield change of furfural and levulinic acid depending on pretreatment factors. The dilute acid pretreatment was conducted depending on reaction temperature ($140-180^{\circ}C$), reaction time (10-30 min), and sulfuric acid concentration (0-2%, w/w). Then, glucose, XMG (xylose + mannose + galactose), furfural, and levulinic acid contents in the liquid hydrolyzate were measured and analyzed after pretreatment. Glucose content increased to 16.02% as reaction temperature, reaction time, and sulfuric acid concentration increased, but it decreased at the sulfuric acid concentration of 2% (reaction temperature: > $170^{\circ}C$, reaction time: > 20 min). On the other hand, reaction temperature had a strong influenced on XMG content, and XMG content decreased to 1.63% through increasing of reaction temperature and sulfuric acid concentration, but XMG content was less affected by changes of reaction time. Furfural content increased with the increase of reaction temperature, reaction time, and sulfuric acid concentration, and maximum furfural content was 7.61% (reaction temperature: $180^{\circ}C$, reaction time: 20 min, sulfuric acid concentration: 1%) based on a weight of raw material, while furfural content was dropped in more severe condition than in maximum furfural content condition. Levulinic acid content also increased with higher reaction temperature, reaction time, and sulfuric acid concentration. Especially, the sharp increase of levulinic acid content was observed above $170^{\circ}C$, and maximum levulinic acid content was 10.98% (reaction temperature: $180^{\circ}C$, reaction time: 30 min, sulfuric acid concentration: 2%). However, less than 1% of furfural and levulinic acid content was obtained in non-acidic catalyst condition that in whole conditions of reaction temperature and reaction time.

• Journal of Korean Society for Atmospheric Environment
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• v.10 no.E
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• pp.371-386
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• 1994

Ecological examinations of the radial growth Patterns of pine trees(Pinus densiflora Sieb. et Zucc) growing on Mt. Namsan in central Seoul were made to test a Proposition that the pine trees decline due to the influence of air pollution and acid rain, which was proposed by some researchers in Korea, and the potential effects of current level of air pollutants to the growth of the Pine trees in central Seoul have been speculated. Tree-rings of 40 trees sampled at 3 sites of Mt. Namsan were prepared and examined using a Computer-aided Tree-Ring Measuring System at Kookmin University, Korea. Air Pollutant data collected by the Ministry of Environment( MOE ) and the Forestry Research Institute(FRI) were used to infer the general conditions of the environment. Correlation analysis was applied to the data set of tree growth and the other environmental factors. General information derived from the close examination of the tree-rings and the data on air pollution, drought and the other biological conditions suggested that the growth of the pine trees was severely affected by the occurrence of drought(climatic variation), the prevalence of the pine leaf gall midges(insects), and the suppression by the black locust trees(Robinia pseudo-acacia L.) (competition among trees). While the current condition of air pollution in Seoul cannot be categorized as good, the concentrations of air pollutants are not so high as to cause acute damages to the trees. In addition, while the data of rain acidity showed episodic low PHs of under 4.0, the average of them is far less acidic than those which were observed in either northeastern United States or central Europe, where the decline of trees were not solely attributed to any of the air pollutants. Considering the sequential facts that one of the most important environmental factors that affect the growth of trees is weather condition of the forest that the proposition of the decline of the pine trees was made without careful examination of the growth patterns and past growth history of them as well as the complex influences of many other factors including the weather conditions to the growth of trees, and that no objective explanation has been made on the causal relationships between the current condition of air pollution and the growth of the trees, such a proposition should be evaluated as invalid for the explanation of tree growth on Mt. Namsan in central Seoul, Korea. The author evaluates the factors of air pollution (including acid rain) as the predisposing factors, which may have the Potentials to chronically affect the tree growth at the forest ecosystem on Mt. Namsan for a long period of time. Ecosystem ecological studies should be further carried out to carefully explain both the functional and the structural aspects of the ecosystem processes, which include the biogeochemistry and the long-term changes of soil conditions as well as the growth of the other tree species on the mountain.

• Korean Journal of Microbiology
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• v.49 no.2
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• pp.184-190
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• 2013

Cave environment provides special ecosystems for evolution of lives distant from surface environments. We investigated bacterial and archaeal communities of wall biofilm obtained from of a volcanic cave (Daesubee) in Jeju, Republic of Korea. Bacterial and archaeal 16S rRNA genes were PCR-amplified and sequenced using pyrosequencing technologies. Unique prokaryotic communities with low diversities were observed. The main bacterial sequences (ca. 83% of total reads) were affiliated with Pseudonocardia mongoliensis of phylum Actinobacteria and clustered with clones obtained from various caves. Reflection of light on the wall surface of cave might be caused by formation of beads of water caused by hydrophobic filaments of actinobacterial colonies. Main archaeal sequences (ca. 65.7% of total reads) were related with those of I.1a-Associated group of phylum Thaumarchaeota. The sequences were related with that of Candidatus Nitrosotalea devanaterra which was known to oxidize ammonia under acidic condition (ca. pH 5.0). Nutrients leached through volcanic soils contribute formation of unique microbial communities of wall biofilm of cave Daesubee.

• The Korean Journal of Mycology
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• v.41 no.4
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• pp.255-260
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• 2013

In order to develop new valuable pear marc nuruk and further, reduce environmental pollution by pear marc from pear juice processing, we prepared pear marc nuruk by incubation of Aspergillus oryzae into pear marc containing 50% of moisture at $30^{\circ}C$ for 7 days. ${\alpha}$-Amylase and glucoamylase activities of the pear marc nuruk were 320.2 IU and 442.8 IU, respectively and its acidic protease activity was showed 142.6 IU. After brewed makgeolli by using the pear marc nuruk, cooked rice and Saccharmyces cerevisiae, its physicochemical characteristics was investigated. Ethanol content of pear marc nuruk-makgeolli was 6.8% after fermentation at $25^{\circ}C$ for 10 days and also pear marc makgeolli showed 45.6% of antihypertensive angiotensin I-converting enzyme (ACE) inhibitory activity. In conclusion, pear marc nuruk had high amylase activity and pear marc-makgeolli had also good fermentation characteristics and antihypertensive ACE inhibitory activity. Therefore, it has the potential to become a new nuruk for brewing makgeolli.

• Journal of Microbiology and Biotechnology
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• v.27 no.12
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• pp.2119-2128
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• 2017

Citrinin (CIT) is a toxic secondary metabolite produced by fungi belonging to the Penicillium, Aspergillus, and Monascus spp. This toxin has been detected in many agricultural products. In this study, a strain Y3 with the ability to eliminate CIT was screened and identified as Cryptococcus podzolicus, based on the sequence analysis of the internal transcribed spacer region. Neither uptake of CIT by cells nor adsorption by cell wall was involved in CIT elimination by Cryptococcus podzolicus Y3. The extracellular metabolites of Cryptococcus podzolicus Y3 stimulated by CIT or not showed no degradation for CIT. It indicated that CIT elimination was attributed to the degradation of intracellular enzyme(s). The degradation of CIT by C. podzolicus Y3 was dependent on the type of media, yeast concentration, temperature, pH, and initial concentration of CIT. Most of the CIT was degraded by C. podzolicus Y3 in NYDB medium at 42 h but not in PDB medium. The degradation rate of CIT was the highest (94%) when the concentration of C. podzolicus Y3 was $1{\times}10^8cells/ml$. The quantity of CIT degradation was highest at $28^{\circ}C$, and there was no degradation observed at 3$5^{\circ}C$. The study also showed that acidic condition (pH 4.0) was the most favorable for CIT degradation by C. podzolicus Y3. The degradation rate of CIT increased to 98% as the concentration of CIT was increased to $20{\mu}g/ml$. The toxicity of CIT degradation product(s) toward HEK293 was much lower than that of CIT.

• Journal of Adhesion and Interface
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• v.17 no.4
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• pp.141-148
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• 2016

In this work, mesoporous silica (SBA-15) was synthesized via self-assembly process using triblock copolymer ($PEO_{20}PPO_{70}PEO_{20}$, P123) as template and tetraethyl orthosilicate (TEOS) as silica source under acidic condition. SBA-15 have high surface area ($704m^2g^{-1}$) and uniform pore size (8.4 nm) with well-ordered hexagonal mesostructure. Spiropyran-functionalized SBA-15 (Spiropyran-SBA-15) was synthesized via post-synthesis process using 3-(triethoxysilyl)propyl isocyanate (TESPI) and 1-(2-Hydroxyethyl)-3,3-dimethy-lindolino-6'-nitrobenzopyrylo-spiran (HDINS). Spiropyran-SBA-15 was produced with hexagonal array of mesopores without damage of mesostructre. Surface area and pore size of Spiropyran-SBA-15 were $651m^2g^{-1}$ and 8.0 nm, respectively. Optochemical properties of Spiropyran-SBA-15 was studied with chemical vapors such as EtOH, THF, $CHCl_3$, Acetone and HCl. Main peaks of photofluorescence of Spiropyran-SBA-15 exhibited blue shift in the range of 603.4~592.1 nm after exposure under EtOH, THF, $CHCl_3$, and Acetone vapors. Normalized peak intensities decreased in the range of 0.8~0.3. The main peak of photofluorescence of Spiropyran-SBA-15 showed significant blue shift of 592.1 nm after exposure under HCl vapor, while normalized peak intensity decreased to 0.1.

• Journal of Radiation Protection and Research
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• v.1 no.1
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• pp.15-21
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• 1976

The present investigation was intended to study the state of Pm-147 in solution and its adsorbed state on membrane filters by varying the concentrations of Pm-147 solution and its pH. Also, the study on the coprecipitation of Pm-147 with $Fe(OH)_3$ was carried out by varying, amounts of $Fe(OH)_3$ and pH of the solution. The carrier-free Pm-147 exists in an ionic state of $Pm^{3+}$ in solution, and is adsorbed on membrane filter in filtration process. The adsorbed state of Pm-147 on the membrane filter shows various ionic state at a constant ionic strength of 0.1M NaCl, that is, $Pm^{3+}$ state exists until pH value of 5.0, then gradually $Pm(OH)^{2+}$ state appears between pH value of 5.0 to 6.0, and the state of $Pm(OH)_2^+$ and $Pm(OH)_3$ would be expected at the higher pH value of 6.0. Coprecipitation of Pm-147 on $Fe(OH)_3$ is an adsorption penomenon in an ionic state of $Pm^{3+}$ in acidic condition. At higher pH and larger amount of Fe carrier, the adsorbed state of Pm-147 shows $Pm(OH)^{2+}$ and $Pm(OH)_2^+$ state. As a results of the present studies, it is seen that the characteristic of carrier free radioisotopes is not due to the radioactivity, but due to the adsorption of ultramicroquantity of radioisopes. Therefore, the knowledge on the ultramicroquantity of radioisotopes could help for the solution of decontamination in handing and chemical procedure with radioisotopes.

• Economic and Environmental Geology
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• v.34 no.5
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• pp.461-470
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• 2001

The Shihung mine was restored in the early 90's after abandonment for 20 yews since 1973. Although disposed mine tailings were removed and the site was replaced by an incineration plant, still some residual mine tailings remain in the places including the old mine tailing ditposal area and the adjacent agricultural area. These residual mine tailings are prone to impose an adverse impact on the soil and groundwater and needs investigation for the potential contamination. Mine tailing samples were collected from the old tailing disposal area and the iii paddy. The porewater from the mine tailing were extracted and analysed to investigate chemical changes along the reaction path. Batch leaching tests were also carried out in the laboratory to find any supporting evidence found in the field analysis. Evidence of elemental leaching was confirmed both by the mine tailing and the porewater chemistry in them. The element concentrations of Cu, Cd, Pb, Zn in the porewater exceed the standard for drinking water of Korean government and US EPA. Leaching of heavy metals from the mine tailing seem to be responsible for the contamination. In batch leaching test. heavy metals were either continuous1y released or declined rapidly. Combining the information with porewater variation with depths and the geochemical meodeling results, most of elements are controlled by dissolution and/or precipitation processes, with some solubility controlling solid phases (Cu, Pb, Fe and Zn). Batch leaching test conducted at fixed pH 4 showed much higher releases for the heavy metals up to 400 times (Zn) and this area is becoming more vulnerable to soil and groundwater pollution as precipitation pH shifts to acidic condition.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.12
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• pp.1647-1653
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• 2008

This study used response surface methodology (RSM) in an effort to optimize the water extraction conditions of Hypsizigus marmoreus in order to increase cytotoxicity activity of the extract. A central composite design was applied to investigate the effects of independent variables, which included the extraction temperature ($X_1$), extraction time ($X_2$), the ratio of solvent to sample ($X_3$) on dependent variables of the extracts, including extraction yield ($Y_1$) and protein content ($Y_2$). The estimated optimal conditions were as follows: $51.3^{\circ}C$ extraction temperature, 8.2 hrs extraction time, and 46.7 mL/g of solvent per sample. The extract (CE) was extracted at optimal condition and crude polysaccharides (CPS) were obtained from CE by ethanol precipitation, dialysis, and freeze drying. Neutral (NPS) and acidic (APS) fraction of polysaccharides were seperated from CPS by ion chromatography. The growth inhibitory effects of the APS (0.5 mg/mL) on AGS human cancer cells were 73.97%. CPS showed the highest growth inhibitory effects on HepG2 human cancer cell at 0.5 mg/mL. However all fraction polysaccharides from Hypsizigus marmoreus showed lower than 20% growth inhibition on SW480 human cancer cell.

• The Korean Journal of Food And Nutrition
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• v.30 no.2
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• pp.388-394
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• 2017

This study investigated the stability of ethanolic extract from fermented Cirsium setidens Nakai (FCSN) in order to develop functional materials during different storage conditions. We evaluated pectolinarin and pectolinarigenin contents, total phenol content and antioxidant activity (DPPH radical scavenging activity and FRAP assay) of ethanolic extract from FCSN obtained by bioconverison at various temperatures (4, 25 and $50^{\circ}C$) and pHs (4.0, 7.0 and 10.0). Our results show that the pectolinarin, pectolinarigenin, and total phenol contents in ethanolic extract from FCSN were decreased during the storage periods. Moreover, the DPPH radical scavenging activity did not significantly change at $4^{\circ}C$ and $25^{\circ}C$. Pectolinarin and pectolinarigenin contents, total phenol content and DPPH radical scavenging activity of ethanolic extract from FCSN at acidic pH (pH 4.0) and neutral pH (pH 7.0) were higher than those at the alkaline pH range. These results indicate that the optimum storage condition of the ethanolic extract from FCSN was $4^{\circ}C$ and pH 4.0~7.0 range.