• Microbiology and Biotechnology Letters
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• v.48 no.2
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• pp.121-128
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• 2020

Diarrhea is a major public health concern associated with pathogenic Escherichia coli infections. Food-borne pathogenic E. coli can lead to large diarrheal outbreaks and hence, there is a need to estimate the frequency of pathogenic E. coli load in the various types of meat available in markets. In the present study, we classified and characterized diarrheagenic E. coli isolates collected from 399 raw meat samples from retail sources in Korea. Shiga toxin-producing E. coli (STEC) were detected in 11 (9.7%) samples, including nine strains (8.0%) in beef and two strains (1.8%) in chicken. The frequency of the detected virulence markers were as follows: astA, 28.3%; escV,18.6%; eaeA,17.7%; ent, 7.0%; EHEC-hly, 4.4%; stx1, 3.5%; and stx2, 3.5%. We did not observe any typical EPEC, EIEC, or ETEC virulence determinants in any of the samples. The STEC serotype O26 was detected in one sample, but no other serogroups (O91, O103, O128, O157, O145, O111, and O121) were found. Further research is needed to better understand the virulence mechanism of STEC serotypes, their ecology, and prevalence in animals, food, and the environment. These results will help improve risk assessment and predict the sources of food poisoning outbreaks.

• Geomechanics and Engineering
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• v.23 no.6
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• pp.503-512
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• 2020

Mining activities focus on the production of mineral resources for energy generation and raw material requirements worldwide and it is a known fact that shallow reserves become scarce. For this reason, exploration of new resources proceeds consistently to meet the increasing energy and raw material demand of industrial activities. Rock mechanics has a vital role in underground mining and surface mining. Devices and instruments used in laboratory testing to determine rock mechanics related parameters might have limited sensing capability of the failure behavior. However, methodologies such as, thermal cameras, digital speckle correlation method and acoustic emission might enable to investigate the initial crack formation in detail. Regarding this, in this study, thermographic analysis was performed to analyze the failure behaviors of different types of rock specimens during uniaxial compressive strength experiments. The energy dissipation profiles of different types of rocks were characterized by the temperature difference recorded with an infrared thermal camera during experiments. The temperature increase at the failure moment was detected as 4.45℃ and 9.58℃ for andesite and gneiss-schist specimens, respectively. Higher temperature increase was observed with respect to higher UCS value. Besides, a temperature decreases of about 0.5-0.6℃ was recorded during the experiments of the marble specimens. The temperature change on the specimen is related to release of radiation energy. As a result of the porosity tests, it was observed that increase in the porosity rate from 5.65% to 20.97% can be associated to higher radiation energy released, from 12.68 kJ to 297.18 kJ.

• Korean Journal of Pharmacognosy
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• v.39 no.4
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• pp.316-323
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• 2008

In this study, we have investigated the HPLC analysis methods and quantitative analysis of standard compounds for quality standardization of a medicinal crude drug GCSB-5, a herbal formulation consisting of 6 medicinal plants (Acanthopanacis Cortex, Achyranthis Radix, Ledebouriellae Radix, Cibotii Rhizoma, Glycine Semen, Eucommiae Cortex) which are used in traditional medicine to treat various bone disorders. HPLC analysis methods of acanthoside D(Acanthopanacis Cortex), 20-hydroxyecdysone(Achyranthis Radix) which were known standard compounds among 6 medicinal plants were developed on crude material and product. And validation of HPLC analysis methods were conformed for verification of HPLC methods by check to specificity, linearity, intra-day precision, inter-day precision and accuracy following ICH guideline. Content of acanthoside D and 20-hydroxyecdysone on raw material of GCSB-5 were decided at 0.577-0.578 mg/g and 0.311-0.312 mg/g. And we confirmed that content of acanthoside D and 20-hydroxyecdysone on GCSB-5 preparation were 0.302-0.303 mg/capsule and 0.113-0.115 mg/capsule.

• Microbiology and Biotechnology Letters
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• v.10 no.2
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• pp.123-132
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• 1982

These experiments were conducted to investigate the enzymatic characteristics of the purified $\alpha$-amylase (F-2A) of Bacillus circulans F-2 and the digestion rate of various starches. 1. The molecular weight was estimated to be 93000 by SDS-polyacrylamide disc gel electrophoresis. The isoelectric point was about pH 5.0. The optimum pH for the enzyme action was 6.0-6.5 and the stable pH ranged pH 5.5-12.0. The optimum temperature was 6$0^{\circ}C$, and the purified $\alpha$-amylase was stable below 4$0^{\circ}C$. 2. The purified $\alpha$-amylase was activated by Mn$^{＋＋}$ and Co$^{＋＋}$, whereas it was inhibited by Ag$^{＋}$, HT$^{＋＋}$, Cu$^{＋＋}$ and Pb$^{＋＋}$. 3. The purified $\alpha$-amylase is considered to have no sulfhydryl residue essential for its catalytic activity. 4. Michaelis constant (Km) was 1.704 mg/$m\ell$. Activation energy between 25-4$0^{\circ}C$ was 12.297 Kcal/mole, and between 40-6$0^{\circ}C$, it was 7.831 Kcal/mole. 5. The hydrolysis product from soluble starch, amylose and amylopectin in the early stage of hydrolysis was G$_{6}$, and as hydrolysis proceeds, G$_4$and G$_2$appeared. 6. Products from each oligosaccarides are as follows: G$_4$longrightarrow G$_2$＋ G$_2$,G$_3$ ＋G$_1$,G$_{5}$longrightarrow G$_4$＋G$_1$,G$_{6}$longrightarrowG$_4$＋ G$_2$,G$_{7}$ G$_4$,G$_{8}$longrightarrow G$_4$＋G$_4$, 7. On raw potato starch, raw sago starch and raw yam starch, the purified enzyme exhibited a remarkably high digestion rate than Porcine pancreatic amylase and Streptococcus bovis amylase.

• The Korean Journal of Mycology
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• v.15 no.3
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• pp.175-182
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• 1987

A raw starch saccharifying enzyme from Aspergillus sp. SN-871 was purified by ammonium sulfate precipitation, DEAE-cellulose column chromatography, CM-Sephadex C-50 column chromatography and Sephadex G-75 gel filtration. The specific activity of purified enzyme was 18 fold and the yeild was 13.40%. The molecular weight of the purified enzyme was estimated as approximately 40,000 dalton by the method of Andrews gel filtration. The optimum pH and temperature for this enzyme were found to be 4 and $40^{\circ}C$, respectively and the stable range of pH was 2 to 5. The enzyme was themostable at below $60^{\circ}C$ and inactivated at $70^{\circ}C$. It showed a tendency to increase the enzyme activity under the presence of 0.01 M $BaCl_2$, but under 0.01 M$Pb(NO_3)_2$, $AgSO_4$, and $K_3Fe(CN)_6$ and citric acid etc. inhibited it completely. The substrate specifity of enzyme showed a tendency to increase the enzyme activity under addition of dextrin and glycogen, but under saccharose inhibited it. COD removal rate of Aspergillus sp. SN-871 was approximately 67 to 68%.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.414-422
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• 2022

The objective of this work was to investigate the feasibility of acid-catalyzed hydrothermal fractionation for maximum solubilization of the hemicellulosic portion of two typical agricultural residues. The fractionation conditions converted into combined reaction severity (CS) in the range of 1.2-2.9 was used to establish a simple reaction criteria at glance. The hemicellulosic sugar yield of 56.6% was shown when rice straw was fractionated at the conditions at the conditions; 160 ℃ of temperature 0.75% (w/v) of H₂SO₄, 20 min of reaction time, 1:15 solid/liquid ratio. The hemicellulosic sugar yield of 83.0%, however, was achieved when barley straw was fractionated at the conditions at the conditions; 150 ℃ of temperature 0.75% (w/v) of H₂SO₄, and 15 min of reaction time, 1:10 solid/liquid ratio. For barley straw, acid-catalyzed hydrothermal fractionation could be effectively performed. After the fractionation process, the remaining fractionated solids were 48.5% and 57.5% from raw rice and barley straws, respectively. The XMG contents in the solid residues decreased from 17.3% and 17.6% to 6.0% and 2.6%, which corresponded to 16.7% and 8.5% on the basis of the raw straws, respectively. In another way, only 5.6% of cellulose and 8.5% of XMG were lost due to excessive decomposition during the acid-catalyzed hydrothermal fractionation of barley straw, compared to cellulose and XMG losses of 6.4% and 26.6% in rice straw. Hemicellulosic sugars from the rice straw were considered more over-decomposed due to the somewhat higher reaction severity at the acid-catalyzed hydrothermal fractionation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.5
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• pp.661-665
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• 2012

Garlic (Allium sativum L.) is one of the oldest cultivated plants and has been used throughout the world as a food supplement and a folk medicine for thousands of years. Raw garlic has been processed into a variety of commercial garlic products for consumer convenience. The latest new processing technology, 'spontaneous short-term fermentation', has been developed to process raw garlic into black garlic. The physiologically active effects of garlic have been attributed to its organosulfur compounds. In this study, the proximate compositions and the total amino acid content of raw Namhae garlic and black garlic were determined. The two major organosulfur compounds of garlic, $S$-allyl-L-cysteine (SAC), and diallyl-disulfide (DADS), were also analyzed using RP-HPLC. The proximate compositions were not different between raw and black garlic. The amount of 13 amino acids was greater in black garlic than in raw garlic among a total of 17 amino acids considered. The black garlic had 2-fold higher levels of SAC and 30-fold higher levels of DADS than the raw garlic. Therefore, it is suggested that consuming black garlic produced by spontaneous short-term fermentation is more effective than consuming raw garlic, in order for consumers to take more physiologically active organosulfur compounds (SAC and DADS), which are the compounds that are good for consumer health.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.5
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• pp.588-597
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• 2004

In this research, we investigated the variation of transmembrane pressure and permeate water quality with pre coagulation and sedimentation with iron based coagulant and chlorination of feed water for PVDF (polyvinylidene fluoride) based MF membrane filtration. NaCIO was fed to the membrane module with dosage of 0.5mg/L and maintained during filtration. To observe the effect of raw water, three types of raw and processed waters, including river surface water, coagulated water and coagulated-settled water, were applied. In case of river surface water, the transmembrane pressure increased drastically in 500 hours of operation. On the contrary, no significant increase in transmembrane pressure was observed for 1,200 hours of operation for coagulated water and coagulated-settled waters. The turbidity of permeate was lower than a detection limit of equipment for all raw waters. The removal efficiency of humic substances of coagulated water and coagulated-settled water was approximate ten times of that of surface river water. And, the removal efficiency of TOC and DOC was approximate two times of that of surface river water. From the results of plant operation, stable operation was maintained at $0.9m^3/m^2{\cdot}day$ filtration flux through the combination of pre-coagulation and pre-chlorination. However, the water quality of permeate was the best when pre-coagulation-sedimentation process was combined with pre-chlorination.

• Journal of Environmental Health Sciences
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• v.32 no.4 s.91
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• pp.316-323
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• 2006

This study was performed to assess the microbial contamination level for the processing of sandwich products in the middle of Gyeongnam province from December 2004 to January 2005. A total of 85 samples were collected from 5 sandwich shops. These samples were tested sanitary indication bacteria, such as aerobic Plate count(APC), coliforms, and Escherchia coli and pathogenic bacteria such as Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes, and Staphylococcus aureus. As a result of APC and coliform count ranged 0-4.59 $log_{10}$ CFU/(ml, g, 100 $cm^2$, hand) and 0-3.86 $log_{10}$ CFU/(ml, g, 100 $cm^2$, hand), respectively. Especially, the highly contaminated items for APC were confirmed 1.64-4.59 $log_{10}$ CFU/g to employees', raw materials and sandwich in all items. Escherichia coli was isolated from 5 samples. Listeria monocytogenes and Staphylococcus aureus were detected in 1 sample and 11 samples from utensil, raw materials and sandwiches, respectively. However, Escherichia coli O157:H7 and Salmonella spp. were not detected in anywhere. For the production of safety sandwich, education of sanitation for employees, control of raw materials, and continuous monitoring for microorganism will be required.

• Toxicological Research
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• v.22 no.1
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• pp.9-13
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• 2006

Diesel exhausted particles (DEP), a kind of fine particles with aerodynamic diameters less than $2.5{\mu}m$ (PM2.5), is of great concern to human health because they remain in atmosphere for long periods, invade an indoor air environment, and can be breathed most deeply into lung and reached the alveoli because of their small size ($0.1{\sim}0.4\;{\mu}m$ in diameter). Epidemiological and experimental studies suggested that DEP may play an active role in the increased respiratory mortality and morbidity. In addition to their physical characteristics, the chemical components including polyaromatic hydrocarbon (PAH) are regarded as a carcinogen causing pulmonary tumors. PLD plays an important role in cell proliferation with various physiological phenomena and affects other enzymes by activating signal transduction pathway. We investigated the cytotoxic mechanism of DEP on RAW 264.7 cells focusing on the role in activation of PLD. Our results suggested DEP induced PLD activity through a specific signaling pathway involving phospholipase $A_2$, PLC, PKC and $Ca^{2+}$ mobilization.