• Journal of Environmental Health Sciences
• /
• v.41 no.1
• /
• pp.17-23
• /
• 2015

Objectives: The cytotoxcities of Au, Ag, SWCNT, $SiO_2$, and ZnO nanomaterials were evaluated in order to assess their potential toxicological effects in in vitro cell models using colony forming efficiency (CFE) assay. Methods: The CFE assay of the test materials was carried out on Hep G2 cells. The size distribution of nanomaterials was studied by transmission electron microscopy (TEM). Changes in cell viability after treatment with a toxicant will result in a decreased number of colonies formed in comparison to solvent. Results: The TEM images show that all the particles except SWCNT and ZnO can be considered approximately spherical. The gold and $SiO_2$ nanoparticles show no response (no toxicity) in concentration response experiments. A statistically significant toxic effect was found in Hep G2 cells treated with Ag, SWCNT and ZnO nanomaterials. Conclusion: In this study, we considered CFE assay to be a promising test for screening studies for cytotoxicity with physicochemical analysis.

• Korean Journal of Optics and Photonics
• /
• v.19 no.2
• /
• pp.116-121
• /
• 2008

A two dimensional point light source array can replace both the viewing zone forming optics and the back light panel in the contact-type 3 dimensional imaging systems based on LC panels. This replacement can make the system structure of the 3 dimensional imaging systems no different from that of the conventional LCD and can reduce undesirable visual effects caused by the viewing zone forming optics. The problem with the point light source array is the visual quality deterioration of the system due to the non-ideal nature of the array.

• Fisheries and Aquatic Sciences
• /
• v.19 no.10
• /
• pp.42.1-42.10
• /
• 2016

The objectives of this study were to identify the histamine-forming bacteria and bacteriocin- producing lactic acid bacteria (LAB) isolated from Myeolchi-jeot according to sequence analysis of the 16S rRNA gene, to evaluate the inhibitory effects of the bacteriocin on the growth and histamine accumulation of histamine-forming bacteria, and to assess the physico-chemical properties of the bacteriocin. Based on 16S rRNA gene sequences, histamine-forming bacteria were identified as Bacillus licheniformis MCH01, Serratia marcescens MCH02, Staphylococcus xylosus MCH03, Aeromonas hydrophila MCH04, and Morganella morganii MCH05. The five LAB strains identified as Pediococcus acidilactici MCL11, Leuconostoc mesenteroides MCL12, Enterococcus faecium MCL13, Lactobacillus sakei MCL14, and Lactobacillus acidophilus MCL15 were found to produce an antibacterial compound with inhibitory activity against the tested histamine-producing bacteria. The inhibitory activity of these bacteriocins obtained from the five LAB remained stable after incubation at pH 4.0-8.0 and heating for 10 min at $80^{\circ}C$; however, the bacteriocin activity was destroyed after treatment with papain, pepsin, proteinase K, ${\alpha}$-chymotrypsin, or trypsin. Meanwhile, these bacteriocins produced by the tested LAB strains also exhibited histamine-degradation ability. Therefore, these antimicrobial substances may play a role in inhibiting histamine formation in the fermented fish products and preventing seafood-related food-borne disease caused by bacterially generated histamine.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.05a
• /
• pp.321-324
• /
• 2005

The main purpose of the present study has been placed on investigating the effects of controlled rolling and cooling on the microstructures and mechanical properties of C-Si-Mn-V steels for cold forming. The steels were manufactured in vacuum induction melting(VIM) furnace and casted to 1.1ton Ingots and the ingots were forged to $\Box150$ billet. The forged billets were reheated in walking beam furnace and rolled to coil, the stocks were rolled by Controlled Rolling and Cooling Technology (CRCT), so rolled at low temperature by water spraying applied in rolling stage and acceleratly cooled before coiling. Rolled coils were cold drawed to the degree of $27\%$ of area reduction without heat treatment. Microstructual observation, tensile test, compression test and charpy impact tests were conducted. The mechanical properties of the steels were changed by area reduction of cold drawing and it is founded that there are optimum level of cold drawing to minimize compression stress for these steels. From the result of this study, it is conformed that mechanical properties and microstructure of C-Si-Mn-V steels for cold forming were enhanced by accelerated cooling and founded optimum level of cold drawing.

• Transactions of Materials Processing
• /
• v.33 no.2
• /
• pp.112-117
• /
• 2024

In this study, the friction and wear characteristics of Inconel 600 in the superplastic forming process of Ti6Al4V were evaluated through pin-on-disc tests. To achieve an efficient and systematic experimental design, the Taguchi method was employed. The wear track of the Inconel 600 pin showed scratches in the sliding contact direction, confirming that the wear mechanism is abrasive wear. Through sensitivity analysis such as ANOVA and Main effects, it was confirmed that both normal force and sliding distance have a significant impact on the wear. Changes in sliding velocity and distance did not affect the friction coefficient, which remained relatively constant at approximately 0.380. The wear prediction model for Inconel 600 in the superplastic forming of Ti6Al4V was constructed, which can be utilized as a guideline for the prediction and management of tool wear.

• Journal of the Korean Dietetic Association
• /
• v.11 no.1
• /
• pp.44-50
• /
• 2005

Natural products are increasingly appreciated as a lead for drug discovery and development. A number of investigators have studied various activities of natural products and have found that they have not only nutritional effects but also beneficial properties to cure various diseases and to maintain good health. Job's Tear(Yul-Moo) is a grass crop that have long been used in traditional medicine and a nourishing food. Job's Tear has been reported to exhibit anti-inflammatory, stomachic, antiallergic activity, and antispastic effects and has been used in China for the treatment of warts, rheumatism, and neuralgia although its mechanism remains unclear. Previous results in our laboratory demonstrated that the ethanol extract and water extract of Job's Tear exerted an immune regulatory function on mice cells in vitro. The present study was performed to investigate the ex vivo effect of Job's Tear on immune function. Seven to eight weeks old mices(Balb/c) were fed ad libitum on chow diet and water extract of Job's Tear were orally administrated every other day for two or four weeks at two different concentrations (50 and 500mg/kg B.W.). Proliferation of mice spenocytes and antibody production to sheep red blood cells(SRBC) using hemolytic plague forming cell assay were used to indicate the immune activity. Splenocytes proliferation of Job's Tear with mitogen stimulation such as Con A and LPS was enhanced at 50 mg/kg B.W. concentrations compared to those of control group. In case of antibody production to sheep red blood cells, the number of antibody- secreting cells was increased by administration of 50mg/kg B.W. concentration in mice immunized as a T-dependent antigen. From the present study, Job's Tear water extracts may be suggested to stimulate the mice immune response by enhancing the splenocytes proliferation and the number of plague forming cells.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.10
• /
• pp.1463-1470
• /
• 2010

Microforming, which exploits the advantages of metal forming technology, appears very promising in manufacturing microparts since it enables the production of parts using various materials at a high production rate, it has high material utilization efficiency, and it facilitates the production of parts with excellent mechanical properties. However, the conventional macroscale forming process cannot be simply scaled down to the micro-scale process on the basis of the extensive results and know-how on the macroscale process. This is because a so-called "size effect" occurs as the part size decreases to the microscale. In this paper, we attempt to develop an effective analytical and experimental modeling technique for explaining the effects of the grain size and the specimen size on the behavior of metals in microscale deformation processes. Copper sheet specimens of different thicknesses were prepared and heat-treated to obtain various grain sizes for the experiments. Tensile tests were conducted to investigate the influence of specimen thickness and grain size on the flow stress of the material. In addition, an analytical model was developed on the basis of phenomenological experimental findings to quantify the effects of the grain size and the specimen size on the flow stress of the material in microscale and macroscale forming.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.6
• /
• pp.1189-1197
• /
• 2017

Lichen-forming fungi are known to have various biological activities, such as antioxidant, antimicrobial, antitumor, antiviral, anti-inflammation, and anti proliferative effects. However, the immunosuppressive effects of Bryoria sp. extract (BSE) have not previously been investigated. In this study, the inhibitory activity of BSE on the proliferation of $CD8^+$ T cells and the mixed lymphocytes reaction (MLR) was evaluated in vitro. BSE was non-toxic in spleen cells and suppressed the growth of splenocytes induced by anti-CD3. The suppressed cell population in spleen cells consisted of $CD8^+$ T cells and their proliferation was inhibited by the treatment with BSE. This extract significantly suppressed the IL-2 associated with T cell growth and $IFN-{\gamma}$ as the $CD8^+$ T cell marker. Furthermore, BSE reduced the expression of the IL-2 receptor alpha chain ($IL-2R{\alpha}$) on $CD8^+$ T cells and CD86 on dendritic cells by acting as antigen-presenting cells. Finally, the MLR produced by the co-culture of C57BL/6 and MMC-treated BALB/c was suppressed by BSE. IL-2, $IFN-{\gamma}$, and CD69 on $CD8^+$ T cells in MLR condition were inhibited by BSE. These results indicate that BSE inhibits the MLR via the suppression of $IL-2R{\alpha}$ expression in $CD8^+$ T cells. BSE has the potential to be developed as an anti-immunosuppression agent for organ transplants.

• The Korean Journal of Mycology
• /
• v.12 no.4
• /
• pp.141-152
• /
• 1984

Aspergillus niger van Tieghem was cultured by the method of synchronous and submerged culture. Throughout the culture, sporulation was occured. Highly phosphorylated nucleotides in sporulating mycelia were detected to assure whether the eucaryotic Aspergillus niger produce these substances or not during the differentiation. Phosphorylated nucleotides were extracted from the conidiophore, bearing mycelia and spore forming body, these nucleotides were identified by TLC with P.E.I. cellulose. Guanosine tetraphosphate was found in both phialide forming mycelia and spore forming body. The contents of free amino acids were assayed and its level was found to increase at early stage of sporulation. The effects of 8-azaguanine examined, it was found to prevent spore formation and to made abnormal structure. The effects of inosinic monophosphate and guanosine monophosphate on spore formation were examined, spore formation was enhanced by these nucleotides.

• Journal of Dairy Science and Biotechnology
• /
• v.22 no.2
• /
• pp.99-106
• /
• 2004

Tumor cell proliferation inhibitory, antioxidative activities and glutathione content were analyzed in a variety of spore forming lactic acid bacteria. Tumor cell proliferation inhibitory activity varied widely depending upon the strains of spore forming lactic acid bacteria and the types of carcinoma cell lines(0${\simn}$56.7%), Bacillus coagulans KTCC3625 has shown a marked antipro-liferative effect against the carcinoma cells and NCL-H1299 human lymphoma cell line tended to be least affected by the spore forming lactic acid bacterial cell extracts. Antioxidative activity analyzed in the lipid peroxidation occurred in all the test strains varied on the strains(5.0 to 52.0%) an extensively high degree of antioxidative activity was demonstrated by three strains of Bacillus coagulans KTCC3625, Bacillus coagulans KTCC1015 and Lactobacillus sporogens CU 815. Concentrations of glutathione were highest in a strain of Lactobacillus sporogenes CU 815 followed by Sporo-lactobacillus inulinus ATCC13538 (5.34 to 8.19 mol/g). Spearmans' rank correlation quotient between cellular GSH levels and linoleic acid peroxidation inhibitory effects of the spore forming lactic acid bacteria revealed highly significant correlation quotient of 0.78. Spearmans' rank correlation quotient between the Caski human cervix carcinoma cell proliferation inhibitory activity and the linoleic acid peroxidation inhibitory effects of the spore forming lactic acid bacteria and that between Caski carcinoma cell proliferation inhibitory activity and the cellular GSH levels were shown to be 0.29 and 0.32,respectively, which means an insignificant positive correlation however.