• Journal of Microbiology
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• 제45권6호
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• pp.492-498
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• 2007

GacS and GacA proteins form a two component signal transduction system in bacteria. Here, Tn5 transposon gacS and gacA (Gac) mutants of Pseudomonas sp. KL28, an alkylphenol degrader, were isolated by selecting for smooth colonies of strain KL28. The mutants exhibited reduced ability to migrate on a solid surface. This surface motility does not require the action of flagella unlike the well-studied swarming motility of other Pseudomonas sp. The Gac mutants also showed reduced levels of biofilm and pellicle formation in liquid culture. In addition, compared to the wild type KL28 strain, these mutants were more resistant to high concentrations of m-cresol but were more sensitive to $H_2O_2$, which are characteristics that they share with an rpoS mutant. These results indicate that the Gac regulatory cascade in strain KL28 positively controls wrinkling morphology, biofilm formation, surface translocation and $H_2O_2$ resistance, which are important traits for its capacity to survive in particular niches.

• Asian-Australasian Journal of Animal Sciences
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• 제12권4호
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• pp.642-650
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• 1999

Options available for utilization of animal wastes include sources of plant nutrients, feed ingredients for farm animals, substrate for methane generation, and substrate for microbial and insect protein synthesis. The wastes have the most economic value for use as animal feed. Performance of animals fed diets containing animal wastes is similar to that of animals fed conventional diets. Processing of animal wastes to be used as animal feed is necessary for destruction of pathogens, improvement of handling and storage characteristics, and maintenance or enhancement of palatability. Feeding of animal waste has not adversely affected the quality and taste of animal products. In the USA copper toxicity has been reported in sheep fed high-copper poultry litter, but this is not a serious problem with cattle. Potential pathogenic microorganisms in animal wastes are destroyed by processing such as heat treatment, ensiling and deep stacking. Incidents of botulism, caused by Clostridium botulinum, have been reported in cattle in some countries, and this problem was caused by the presence of poultry carcasses in litter. This problem has not occurred in the USA. With appropriate withdrawal, heavy metal, pesticide or medicinal drug accumulation in edible tissues of animals fed animal wastes is not a problem. Feeding of animal wastes is regulated by individual states in the USA. The practice is regulated in Canada, also. With good management, animal wastes can be used safely as animal feed.

• IMMUNE NETWORK
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• 제15권2호
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• pp.51-57
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• 2015

Vaccines are the most effective and cost-efficient method for preventing diseases caused by infectious pathogens. Despite the great success of vaccines, development of safe and strong vaccines is still required for emerging new pathogens, re-emerging old pathogens, and in order to improve the inadequate protection conferred by existing vaccines. One of the most important strategies for the development of effective new vaccines is the selection and usage of a suitable adjuvant. Immunologic adjuvants are essential for enhancing vaccine potency by improvement of the humoral and/or cell-mediated immune response to vaccine antigens. Thus, formulation of vaccines with appropriate adjuvants is an attractive approach towards eliciting protective and long-lasting immunity in humans. However, only a limited number of adjuvants is licensed for human vaccines due to concerns about safety and toxicity. We summarize current knowledge about the potential benefits of adjuvants, the characteristics of adjuvants and the mechanisms of adjuvants in human vaccines. Adjuvants have diverse modes of action and should be selected for use on the basis of the type of immune response that is desired for a particular vaccine. Better understanding of current adjuvants will help exploring new adjuvant formulations and facilitate rational design of vaccines against infectious diseases.

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1708-1714
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• 2013

Polyhexamethylene guanidine (PHMG) polymers used as an active ingredient in an antibacterial humidifier disinfectant were reported to cause harm to the human health when inhaled, although physical contact with this material was known to present low toxicity to humans. It is therefore necessary to develop an optimal analysis method which enables detection and analysis of PHMG polymers. MALDI-TOF investigations of PHMG are performed with a variety of matrices, and it is found that CHCA and 2,5-DHB are excellent matrices which well reflects the polymer population even at high mass. For the provided PHMG sample, the number-average ($M_n$) and weight-average ($M_w$) molecular masses were determined to be 744.8 and 810.7, respectively, when the CHCA was used as a matrix. The rank of the matrices in terms of averaged molecular weight was CHCA ~2,5-DHB > 5-NSA > DHAP, THAP > ATT > IAA ~ super-DHB ~ HABA. In addition, PSD of the PHMG oligomer ions exhibited a few unique fragmenation characteristics. The formation of a- and c-type fragments was the major fragmentation pathway, and the 25-Da loss peaks generally accompanied a- and c-type fragments.

• 산업기술연구
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• 제20권A호
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• pp.57-62
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• 2000

This experiment was done to investigate the leaching and adsorption properties of heavy metals on porphyry. The comparison with respect to the leachability of heavy metals from porphyry between the Korea Standard Leaching Test (KSLT) and the Toxicity Characteristic Leaching Procedure (TCLP) was carried out. The fractional composition of leachate and the total concentration of heavy metal of porphyry were studied through Sequential Extraction Procedure (SEP) and EPA Method 3050. Adsorption experiment of porphyry has pointed out that the optimum dosage of porphyry for 50ppm Pb was over 10g/L, the effective particle size for absorption was below 200 mesh and the optimum pH was about 7. From the Freundlich' adsorption equation, 1/n was 1.0722, and k was 0.0041. After adsorption, the fractional composition of Pb was changed. The exchangeable, carbonate, reducible fractions were increased, and the organic fraction was not changed, and the residual fraction was decreased.

• 한국전기전자재료학회논문지
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• 제30권9호
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• pp.583-588
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• 2017

Thermal batteries are used in military power sources that require robustness and long storage life for applications in missiles and torpedoes. $FeS_2$ powder is currently used as a cathode material because of its high specific energy density, environmental non-toxicity, and low cost. $MS_2$ (M = Fe, Ni, Co) cathodes have been explored as novel candidates for thermal batteries in many studies; however, the discharge characteristics (1, 2, 3 plateau) of single cells in thermal batteries with different cathodes have not been elucidated in detail. In this study, we independently analyzed the discharge voltage and calculated the total polarizations of single cells using $MS_2$ cathodes. Based on the results of this study, we propose $NiS_2$ as a potential cathode material for use in thermal batteries.

• 한국재료학회지
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• 제22권3호
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• pp.159-167
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• 2012

Hydrogen is in the spotlight as an alternative next generation energy source for the replacement of fossil fuels because it has high specific energy density and emits almost no pollution, with zero $CO_2$ emission. In order to use hydrogen safely, reliable storage and transportation methods are required. Recently, solid hydrogen storage systems using metal hydrides have been under extensive development for application to fuel cell vehicles and fuel cells of MCFC and SOFC. For the practical use of hydrogen on a commercial basis, hydrogen storage materials should satisfy several requirements such as 1) hydrogen storage capacity of more than 6.5wt.% $H_2$, moderate hydrogen release temperature below $100^{\circ}C$, 3) cyclic reversibility of hydrogen absorption/desorption, 4) non toxicity and low price. Among the candidate materials, Li based metal hydrides are known to be promising materials with high practical potential in view of the above requirements. This paper reviews the characteristics and recent R&D trends of Li based complex hydrides, Li-alanates, Li-borohydrides, and Li-amides/imides.

• 펄프종이기술
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• 제30권4호
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• pp.28-34
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• 1998

Polyvinyl acetate emulsion has been widely used as adhesives for wood and paper, paint additives and binders for fiber, leather, and other materials because it is an excellent adhesive with many advantages including low in toxicity risks and manufacturing cost. It is expected the consumption of polyvinyl acetate emulsion as adhesives will increase in cigarette industry as well as in paperboard coating industry. Recently the operation speed of the cigarette tip wrapper increased so substantially that improvement of the emulsion properties is required including good wet tack development, narrow and controlled particle size distribution, low viscosity, etc. In this study the effects of such polymerization conditions as the type and amount of emulsifier, internal or external plasticizing, and emulsification methods on the viscosity and particle size of polyvinyl acetate emulsions were examined. Results showed that polyvinyl alcohol with a high degree of hydrolysis and low molecular weight and nonionic surfactants are superior to anionic surfactant in improving adhesion and emulsion stability. They also tend to produce emulsions with smaller particle size. External plasticization with dipropylene glycol dibenzoate was more effective in improving flexibility than internal plasticization with butyl acrylate. Monomer emulsification under high shear was more effective in decreasing the particle size.

• 한국토양비료학회지
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• 제45권4호
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• pp.593-601
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• 2012

Heavy metals and metalloids removal can be considered as one of the most important world challenges because of their toxicity and direct impact on human health. Many processes have been introduced but biological processes of remediation seem to offer the most suitable solution in terms of efficiency and low cost. Actinobacteria constitute one of the major microbial populations in soil, and this can be attributed to their adaptive morphological structure as well as their exceptional metabolic power. Among microbes, actinobacteria are morphologic intermediate between fungi and bacteria. Studies on microbial diversities in metal contaminated lands have shown that actinobacteria may constitute a dominantly active microbiota in addition to ${\alpha}$ Proteobacteria. Furthermore, isolation studies have shown metal removal mechanisms which are reminiscent of notable multiresistant strains, such as Cupriavidus metallidurans. Apart from members of genus Streptomyces, which produce more than 90% of commercialized antibiotics, and the nitrogen fixing Frankia, little attention has been given to other members of this phylum. This is because of difficult culture condition requirements and maintenance. In this review, we focused on specific isolation of actinobacteria and their potential applications in metal bioremediation and plant growth promotion.

• 한국발생생물학회지:발생과생식
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• 제24권1호
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• pp.1-17
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• 2020

Phthalates and those metabolites have long history in industry and suspected to have deficient effects in development and reproduction. These are well-known anti-androgenic chemicals and many studies have examined the effects of these compounds on male reproduction as toxins and endocrine disruptors. Uterus is a key organ for proper embryo development, successful reproduction, and health of eutherian mammals including women. To understand the effects of the phthalate, the horizontal approach with a whole group of phthalate is best but the known phthalates are huge and all is not uncovered. Di-(2-ethylhexyl) phthalate (DEHP) is the most common product of plasticizers in polymer products and studied many groups. Although, there is limited studies on the effects of phthalates on the female, a few studies have proved the endocrine disrupting characters of DEHP or phthalate mixture in female. An acute and high dose of DEHP has adverse effects on uterine histological characters. Recently, it has been revealed that a chronical low-dose exposing of DEHP works as endocrine disrupting chemicals (EDC). DEHP can induce various cellular responses including the expression regulation of steroid hormone receptors, transcription factors, and paracrine factors. Interestingly, the response of uterus to DEHP is not monotonous and the exposed female has various phenotypes in fertility. These suggest that the exposing of DEHP may causes of histological modification in uterus and of disease in female such as endometriosis, hyperplasia, and myoma in addition to developmental and reproductive toxicity.