• Journal of Ocean Engineering and Technology
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• v.28 no.4
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• pp.356-362
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• 2014

Wear and corrosion of the engine parts surrounded with combustion chamber is more serious compared to the other parts of the engine because temperature of the exhaust gas in a combustion chamber is getting higher and higher with increasing of using the heavy oil of low quality. Therefore, an optimum repair weldment as well as an available choice of the base metal for these parts are very important to prolong their lifetime in a economical point of view. It reported that there was an experimental result for repair weldment on the forged steel which would be generally used with piston crown material, however, it is considered that there is no study for the repair weldment on the cast steel of piston crown material. In this study, four types of electrodes such as 1.25Cr-0.5Mo, 0.5Mo Inconel 625 and 718 were welded with SMAW and GTAW methods on the cast steel which would be generally used with piston crown material. And the corrosion properties of weld metal, heat affected zone and base metal were investigated using electrochemical methods such as measurement of corrosion potential, anodic polarization curves, cyclic voltammogram and impedance etc. in 35% $H_2SO_4$ solution. In the cases of Inconel 625, 718, the weld metals and base metals exhibited the best and worst corrosion resistance respectively, however, 1.25Cr-0.5Mo and 0.5Mo indicated that corrosion resistance of the base metal was better than the weld metal. And the weld metal welded with electrodes of Inconel 625 revealed the best corrosion resistance among the electrodes, and Inconel 718 followed the Inconel 625. Hardness relatively also indicated higher value in the weld metal compared to heat affected zone and base metal. In particular, Inconel 718 indicated the highest value of hardness compared to other electrodes in the heat affected zone.

• The Journal of the Korean bone and joint tumor society
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• v.5 no.3
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• pp.162-168
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• 1999

The products of c-fos and c-jun proto-oncogenes form the heterodimeric complex activator protein 1 (AP-1), which plays an important part in the control of bone cell proliferation and differentiation, as well as in the development of bone tumors. The expression of c-fos protein was examined in 35 cases of human osteosarcomas as formalin-fixed paraffin-embedded tissue sections using a monoclonal antibody. The expression of c-fos was restricted to bone-forming lesions, while low grade cartilaginous tumors were devoid of immunoreactivity. The highest levels of c-fos expression were detected in osteoblastic osteosarcoma (13 of 17 cases with grade one on two) while two chondroblastic osteosarcomas, one fibroblastic osteosarcoma, and two parosteal osteosarcomas were negative. Two cases of telangiectatic osteosarcomas were positive for c-fos protein. However, since there is a tendency of high c-fos protein expression at the higher histological grade, significant differences were not present in the expression of c-fos protein. Thus c-fos expression may be implicated in the development of osteosarcomas, but they appear to have little or no relevance in the development of low grade cartilaginous neoplasms.

• KSBB Journal
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• v.14 no.1
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• pp.114-118
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• 1999

In order to use a polysaccharide, curdlan, as a concrete admixture, we first developed a pilot-scale fermentation process for the mass production of curdlan. We also examined the rheological properties of curdlan, and tested how well the curdlan obtained in this work increased the segregational resistance of the cement slurry. Fermentation was performed in a 300-liter fermenter equipped with 3 disk-turbine impellers. Since curdlan production is stimulated under nitrogen-limiting conditions, the culture pH was shifted from the optimal pH for cell growth (pH 7.0) to the optimal pH for curdlan production (pH 5.5) at the onset of ammonium exhaustion. We obtained a curdlan production of 65 g/L in 120 hr batch cultivation of Agrobacterium species. The insoluble curdlan at the final stage of fermentation was readily harvested by centrifugation together with the cells. The freeze-dried sample contained 78% (w/w) of curdlan. The solubility and viscosity of the curdlan increased with the increase of the solution pH, which enhances the viscosity of concrete since the pH of concrete is extremely high (pH 13.0). Test results of the curdlan as a concrete admixture with cement slurry demonstrated that it prohibits the leakage of water. In conclusion, this work certifies and enlarges curdlan's industrial potential as a concrete admixture.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.11
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• pp.1872-1877
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• 2013

Lactic acid bacteria were selected on the basis of lactic acid producing ability from kimchi, a traditional Korean fermented food. Among the initial screening of over 150 strains selected from the sample, 27 strains were selected as lactic acid producing bacteria, and 4 strains were finally selected based on their ability to produce relatively high levels of lactic acid. The four strains were identified as Lactobacillus (L.) plantarum Gk04, Pediococcus pentosaceus Gk07, L. brevis Gk35 and L. curvatus Gk36 by the conventional morphological, cultural, physiological and biochemical characteristics, as well as by 16S rRNA sequence analysis. Among the identified lactic acid bacteria, L. curvatus Gk36 was used for soymilk fermentation. The viable cell counts and acidity values measured for the L. curvatus Gk36 were comparable to the commmercial L. acidopillus. Thus, the L. curvatus Gk36 is a potential probiotic strain to prepare fermented soy products, such as kephir, yogurt, tempeh and soy sauce.

• Applied Microscopy
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• v.39 no.2
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• pp.107-115
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• 2009

The programed cell death of the cutaneous epithelial tissue during tail regression stages in anuran tadpoles of the blackspotted frog, Rana nigromaculata were visualized by the histochemical and transmission electron microscopic techniques. Metamorphotic changes in the tail regression during the period of the Shumway stage number 31 to 33 are characterized by the disappearance of mucous layer and formation of compound epithelium through cutaneous thickening. Following the TUNEL (terminal deoxynucleotidyl transferase-mediated biotinylated d-uridine triphosphate nick end labeling) staining technique, the apoptotic cells were detected at the distal region of the tail skin initially, but they can be seen at the proximal region according to their following development. It has been also revealed that the number of the TUNEL-positive cells gradually increased from apical to basal direction of the epithelial layers during the tail regressing stages. Following the TEM observation, the early apoptotic cells shown in the epithelium demonstrated condensation and margination of the chromatin material at the nuclear periphery. Another epithelial apoptotic cells were shown nuclear fragmentation, membrane blebbing and cytoplasmic condensation. Following the process of the apoptotic degradation, well preserved organelles and nuclear fragments can be identified in the cytoplasm of lysosome-rich cells, however they soon reduced to lysosomal residual bodies through the progressive degradation.

• Development and Reproduction
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• v.16 no.4
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• pp.339-351
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• 2012

Fetal bovine serum (FBS) is the most frequently used serum for the cultivation of mammalian cells. However, since animal-derived materials might not be appropriate due to safety issues, allogeneic human serum (HS) has been used to replace FBS, particularly for the culture of human cells. While there has been a debate about the advantages of HS, its precise effect on human adult stem cells have not been clarified. The present study aimed to investigate the effect of HS on the human eyelid adipose stem cells (HEACs) in vitro. When HEACs were cultivated in a medium containing 10% HS, many cells moved into several spots and aggregated there. The phenomenon was observed as early as 9 days following 10% HS treatment, and 12 days following 5% HS plus 5% FBS treatment. However, the aggregation was never observed when the same cells were cultivated with 10% FBS or bovine serum albumin. To examine whether cell density might affect the aggregation, cells were seeded with different densities on 12-well dish. Until the beginning of aggregation, cells seeded at low densities exhibited the longest culture period of 16 days whereas cells seeded at high densities showed the shortest period of 9 days to form aggregation. The number of cells was $15.1{\pm}0.2{\times}10^4$ as the least for the low density group, and $29.3{\pm}2.8{\times}10^4$ as the greatest for the high density group. When human cord blood serum or normal bovine serum was examined for the same effect on HEACs, interestingly, cord blood serum induced the aggregation of cells whereas bovine serum treatment has never induced. When cells were cultivated with 10% HS for 9 days, they were obtained and analyzed by RT-PCR. Compared to FBS-cultivated HEACs, HS-cultivated HEACs did not express VIM, and less expressed GATA4, PALLD. On the other hand, HS-cultivated HEACs expressed MAP2 more than FBS-cultivated HEACs. In conclusion, human adult stem cells could move and form aggregates by the treatment with human body fluids.

• Development and Reproduction
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• v.16 no.4
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• pp.295-300
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• 2012

Manganese ($Mn^{2+}$) is a trace element that is essential for normal physiology, and is predominantly obtained from food. Several lines of evidence, however, demonstrated that overexposure to $MnCl_2$ exerts serious neurotoxicity, immunotoxicity and developmental toxicity, particularly in male. The present study aimed to evaluate the effect of 0, 1.0, 3.3, and 10 mg/kg/day doses of $MnCl_2$ on the reproductive organs in the immature female rats. Rats (PND 22; S.D. strain) were exposed to $MnCl_2$ ($MnCl_2{\cdot}4H_2O$) dissolved in drinking water for 2 weeks. The animals were sacrificed on PND 35, then the tissues were immediately removed and weighed. Histological studies were performed using the uteri tissue samples. Serum LH and FSH levels were measured with the specific ELISA kits. Body weights of the experimental group animals were not significantly different from those of control group animals. However, ovarian tissue weights in 1 mg and 3.3 mg $MnCl_2$ dose groups were significantly lower than those of control animals (p<0.05 and p<0.01, respectively). Uterine tissue weights of 3.3 mg dose $MnCl_2$ groups were significantly lower than those of control animals (p<0.01), while the 1 mg $MnCl_2$ dose and 10 mg $MnCl_2$ dose failed to induce any change in uterine weight. Similarly, only 3.3 mg $MnCl_2$ dose could induce the significant decrease in the oviduct weight compared to the control group (p<0.05). Non-reproductive tissues such as adrenal and kidney failed to respond to all doses of $MnCl_2$ exposure. The uterine histology revealed that the $MnCl_2$ exposure could affect the myometrial cell proliferation particularly in 3.3 mg dose and 10mg dose group. Serum FSH levels were significantly decreased in 1mg $MnCl_2$ dose and 10 $MnCl_2$ mg groups (p<0.05 and p<0.01, respectively). In contrast, treatment with 1 mg $MnCl_2$ dose induced a significant increment of serum LH level (p<0.05). The present study demonstrated that $MnCl_2$ exposure is capable of inducing abnormal development of reproductive tissues, at least to some extent, and altered gonadotropin secretions in immature female rats. Combined with the well-defined actions of this metal on GnRH and prolactin secretion, one can suggest the $Mn^{2+}$ might be a potential environmental mediator which is involved in the female pubertal process.

• Development and Reproduction
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• v.11 no.2
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• pp.59-66
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• 2007

Understanding molecular mechanisms that control embryonic stem cell (ESC) self-renewal and differentiation is important for the development of ESC-based therapies. Statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase), potently reduce cholesterol level. As well as inhibiting cholesterol synthesis, statins inhibit other intermediates in the mevalonate pathway such as farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP), major substrates for protein isoprenylation. Studies showed that pleiotropic effects of statins beyond cholesterol lowering property arise from inhibition of protein isoprenylation that is involved in various cellular functions including proliferation and differentiation. It has been determined that statins have inhibitory effect on ESC self-renewal and stimulatory effect on ESC differentiation into adipogenic/osteogenic lineages. Importantly, statins mediate downregulation of ESC self-renewal by inhibiting RhoA-dependent signaling, independently of their choresterol-lowering properties. Understanding statin's actions on ESCs may provide important insights into the molecular mechanisms that regulate self-renewal or differentiation of ESCs.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.217-223
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• 2015

Effects of the post-acid treatment of SAPO-34 sample by hydrochloric acid were investigated to enhance the catalytic performance in DTO reaction. Uniformly sized SAPO-34 samples with cubic-like morphology were prepared by hydrothermal method using TEAOH and DEA as the structure directing agents. It was modified in terms of the HCl concentration and treating time. As a result, the total surface area and micropore volume for the well modified samples increased and the total acid site was somewhat decreased along with the erosion of the external surface. Especially, the catalytic lifetime and light olefins selectivity for acid treated SAPO-0.2 M (3 h) samples were considerably enhanced compared with those of untreated SAPO-34 samples. It indicates that the deactivation by coke formation proceeds mainly at the pore entrance on the external surface. Therefore, the acid treatment was confirmed to be a simple method which can significantly improve the catalytic performance by modifying the external surface of SAPO-34 catalyst.

• Korean Journal of Ecology and Environment
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• v.40 no.2
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• pp.294-302
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• 2007

This study was to evaluate microcystin production by Microcystis aeruginosa in response to three different levels of indirect (0, 10, 50% of fish cultured media filtrate; control, FCMF1 and FCMF2) exposures to omnivorous and planktivorous fish (Carassius gibelio langsdorfi and Hypophthalmichthys molitrix, CCMF and HCMF, repectively). The cell biomass, intracellular microcystin (MC) and extracellular MC were measured everyday. The intracellular MC contents of all treatments were significantly increased than the controls (CCMF1, P=0.015; CCMF2, P<0.001; HCMF1, P<0.001; HCMF2, P<0.001). The intracellular MC contents of M. aeruginosa were significantly higher in CCMF2 than in CCMF1 (P=(0.023), Those of M, aeruginosa in HCMF2 were significantly higher than that in HCMF1 (P<0.001). The extracellular MC contents were not significantly different between control and CCMFs but those of M, aeruginosa in HCMF1 and HCMF2 were significantly higher than that in control (HCMF1, P=0.003; HCMF2, P<0.001). This study strongly supports that induced-defensive MC production (intra and extracellular MC) of potentially toxic cyanobacteria in response to kairomone concentration and this results can consider the biomanipulation of eutrophic waters as well as an information concerning strategies for recovering eutrophic waters.