• The korean journal of orthodontics
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• v.24 no.1 s.44
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• pp.105-114
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• 1994

The movement of teeth during orthodontic treatment requires bone remodeling process of bone formation and bone resolution. To find out the changes occuring in the cell itself, mechanical stress was applied to the cell populations involved in the bone metabolism. Bone tissue cell populations were isolated from fetal rat calvaria and divided into OC and OB groups. Following results were obtained from measuring the changes in acid & alkaline phosphatease activity, cyclic AMP and $PGE_2$ production in time lapse after the application of mechanical stress. 1. In case of the marker enzyme of specific bone tissue cell, acid phosphatase activity was high in OC group and alkaline phosphatase activity was high in OB group. 2. After the mechanical stress was applied, acid phosphatase activity was decreased in both OC and OB groups and alkaline phosphatase activity was increase in OB group. 3. When the mechanical stress was applied for 15, 30 and 60 minutes, the production of $PGE_2$ increased in both OC and OB groups, as the time span increased. 4. When the mechanical stress was applied for 20 and 40 minutes, the production of $PGE_2$ increased in both OC and OB groups, as the time span increased.

• Journal of Ocean Engineering and Technology
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• v.9 no.2
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• pp.141-148
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• 1995

Fatigue tests were carried out by a rotary bending testing machine of cantilever type. M.E.F.(ferrite encapsulated islands of martensite) materials were made by a series of heat treatment from a low carbon steel(SM 20 C). The fatigue tests were conducted at stress levels of 302 MPa and with frequencies of 25Hz, 2.5 Hz and 0.5 Hz in 3% NaCl solution. The fatigue strength increased with frequency got higher. The microcracks and corrosion pits were generated at the boundary between the matrix and the 2nd phase. The cracks generated by the corrosion pits were coalesced with the pits around the notch and became the initial crack. The $N_i/N_f$ ratio increased as the frequency and stress level decreased. The interference phenomenon increased with stress level and frequency gots higher. The crack propagation rate was delayed as the stress level lowers and the frequency gets higher, however, the range of the stress intensity factor depended only on a stress level.

• Development and Reproduction
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• v.17 no.2
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• pp.141-147
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• 2013

Keeping the intact germinal vesicle (GV) is essential for maintaining the capacity of mammals including human. It is maintained by very complex procedures along with folliculogenesis and is a critical step for getting competent oocyte. So far, a few mechanisms involved in folliculogenesis are known but GV arrest mechanisms are largely unrevealed. Cyclic AMP, a adenosine derived substance, have been used as inhibitor of germinal vesicle breakdown as a putative oocyte maturation inhibitor. In this study, we examined the potency of adenosine as GV maintainer and a possible signaling mediator for that. A1, A2b, and A3 were detected in cumulus cells of cumulus enclosed-oocyte (CEO). Intact of germinal vesicle was not kept like in follicle but the spontaneous maturation was inhibited by exogenous adenosine. It is inhibited with concentration dependent manners. Intracellular calcium level of cumulus was extensively increased after adenosine treatment. Based on these results it is suggested that one of the pathway for GV arrest by adenosine and its receptors is calcium mediated signaling pathway in CEO.

• Transactions on Electrical and Electronic Materials
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• v.15 no.2
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• pp.81-86
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• 2014

The process parameter in optimized KOH alkali activation of soft carbon series coke material in high purity was set with DOE experiments design. The activated carbon was produced by performing the activation process based on the set process parameters. The specific surface area was measured and pore size was analyzed by $N_2$ absorption method for the produced activated carbon. The surface functional group was analyzed by Boehm method and metal impurities were analyzed by XRF method. The specific surface area was increased over 2,000 $m^2/g$ as the mixing ratio of activation agent increased. The micro pores in $5{\sim}15{\AA}$ and surface functional group under 0.4 meq/g were obtained. The contents of the metal impurity in activated carbon which is the factor for reducing the electrochemical characteristics was reduced less than 100 ppm through the cleansing process optimization. The electrochemical characteristics of activated carbon in 38.5 F/g and 26.6 F/cc were checked through the impedance measuring with cyclic voltammetry scan rate in 50~300 mV/s and frequency in 10 mHz ~100 kHz. The activated carbon was made in the optimized activation process conditions of activation time in 40 minutes, mixing ratio of activation agent in 4.5 : 1.0 and heat treatment temperature over $650^{\circ}C$.

• Natural Product Sciences
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• v.22 no.4
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• pp.246-251
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• 2016

This study investigated the effects of (-)-sesamin on memory deficits in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned mouse model of Parkinson's disease (PD). MPTP lesion (30 mg/kg/day, 5 days) in mice showed memory deficits including habit learning memory and spatial memory. However, treatment with (-)-sesamin (25 and 50 mg/kg) for 21 days ameliorated memory deficits in MPTP-lesioned mouse model of PD: (-)-sesamin at both doses improved decreases in the retention latency time of the passive avoidance test and the levels of dopamine, norepinephrine, 3,4-dihydroxyphenylacetic acid, and homovanillic acid, improved the decreased transfer latency time of the elevated plus-maze test, reduced the increased expression of N-methyl-D-aspartate (NMDA) receptor, and increased the reduced phosphorylation of extracellular signal-regulated kinase (ERK1/2) and cyclic AMP-response element binding protein (CREB). These results suggest that (-)-sesamin has protective effects on both habit learning memory and spatial memory deficits via the dopaminergic neurons and NMDA receptor-ERK1/2-CREB system in MPTP-lesioned mouse model of PD, respectively. Therefore, (-)-sesamin may serve as an adjuvant phytonutrient for memory deficits in PD patients.

• Journal of Microbiology and Biotechnology
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• v.26 no.5
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• pp.953-958
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• 2016

Chitosan-based film-forming gel is regarded as a promising vehicle for topical delivery of antimicrobial agents to skin wounds, since it protects from microbial infection and the cationic polymer itself possesses antibacterial activity. In this study, possible synergistic interaction against common skin pathogens between the cationic polymer and tyrothricin (TRC), a cyclic polypeptide antibiotic, was investigated, by determining the concentration to inhibit 90% of bacterial isolates (MIC). The addition of the polysaccharide to TRC dramatically reduced the MIC values of TRC by 1/33 and 1/4 against both methicillin-resistant and methicillin-susceptible Staphylococcus aureus, respectively. The synergism of TRC and chitosan combination against both strains was demonstrated by the checkerboard method, with a fractional inhibitory concentration index below 0.5. Moreover, co-treatment of TRC and chitosan exhibited antibacterial activity against Pseudomonas aeruginosa, due to the antibacterial activity of chitosan, whereas TRC itself did not inhibit the gram-negative bacterial growth. These findings suggested that the use of chitosan-based film for topical delivery of TRC could be an alternative to improve TRC antimicrobial activity against strains that are abundant in skin wounds.

• Structural Engineering and Mechanics
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• v.53 no.5
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• pp.867-880
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• 2015

Mechanical fastening is still one of the main methods used for joining components. Different techniques have been applied to reduce the effect of stress concentration of notches like fastener holes. In this work we evaluate the feasibility of combining laser shock peening (LSP) and cold expansion to improve fatigue crack initiation and propagation of open hole specimens made of 6061-T6 aluminum alloy. LSP is a new and competitive technique for strengthening metals, and like cold expansion, induces a compressive residual stress field that improves fatigue, wear and corrosion resistance. For LSP treatment, a Q-switched Nd:YAG laser with infrared radiation was used. Residual stress distribution as a function of depth was determined by the contour method. Compact tension specimens with a hole at the notch tip were subjected to LSP process and cold expansion and then tested under cyclic loading with R=0.1 generating fatigue cracks on the hole surface. Fatigue crack initiation and growth is analyzed and associated with the residual stress distribution generated by both treatments. It is observed that both methods are complementary; cold expansion increases fatigue crack initiation life, while LSP reduces fatigue crack growth rate.

• Asian-Australasian Journal of Animal Sciences
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• v.7 no.4
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• pp.527-530
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• 1994

The effect of orally supplemented urea on eating and rumination behaviour of sheep fed a low-quality hay was investigated in this study. Daily time spent eating was not influenced by ruminal addition of urea, thus the eating rate (g DM/min) also did not change with urea supplementation. The rumination appearance (the lag time after eating) tended to be shorted with urea supplement than without supplement, but not significantly (p>0.05). Daily time spent ruminating was in the range of 600-630 min/d, and rumination index (ruminating time/100 g DM ingested) was 85 min. on the average for all the treatments, but there were no significant differences among the values in each treatment. Daily number of rumination periods tended to be smaller with urea supplement than with no urea, but not significantly (p>0.05), and cyclic rate was almost constant in all the treatments. From these results, it may be concluded that an administration of urea in sheep receiving hay diet could have little effect on eating and rumination behaviour, when it was given at two times a day.

• CELLMED
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• v.3 no.4
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• pp.29.1-29.11
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• 2013

Certain dietary contents, biological supplements might influence the occurrence or treatment of epilepsy. Some studies have found that the supplementation with individual nutrients reduced seizure frequency or improved other aspects of health in patients with epilepsy. Potentially beneficial dietary interventions include treating blood glucose dysregulations. Identifying and avoiding allergenic foods, and avoiding suspected triggering agents such as alcohol, aspartame, and monosodium glutamate. The Atkins diet (very low in carbohydrates) is a less restrictive type diet that may be effective in some cases. Nutrients that may reduce seizure frequency include vitamin B6, magnesium, vitamin E, manganese, taurine, dimethylglycine, and omega-3 fatty acids. Administration of thiamine may improve cognitive function in patients with epilepsy. Supplementation with folic acid, vitamin B6, biotin, vitamin D, and L-carnitine may be needed to prevent or treat deficiencies resulting from the use of anticonvulsant drugs. Vitamin K1 has been recommended near the end of pregnancy for women taking anticonvulsants. Melatonin may reduce seizure frequency in some cases, and progesterone may be useful for women with cyclic exacerbations of seizures. In most cases, nutritional therapy is not a substitute for anticonvulsant medications. However, in selected cases, depending on the effectiveness of the interventions, dosage reductions or discontinuation of medications may be possible. However, nutrient supplementation may be necessary to prevent or reverse the effects of certain deficiencies that frequently result from the use of antiepileptic drugs.

• Journal of Microbiology and Biotechnology
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• v.16 no.5
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• pp.678-682
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• 2006

To remove nitrate from wastewater, a novel bioelectrochemical denitrification system is introduced. In this proposed system, biological reactions are coupled with reactions on the electrode, whereby the electrons are transferred to the bacterial enzymes via a mediator as an electron carrier. The denitrification reaction was achieved with permeabilized Ochrobactrum anthropi SY509 containing denitrifying enzymes, such as nitrate reductase, nitrite reductase, and nitrous oxide reductase, and methyl viologen was used as the mediator. The electron transfer from the electrode to the enzymes in the bacterial cells was confirmed using cyclic voltammetry. A high removal efficiency of nitrate was achieved when the bioelectrochemical system was used with the permeabilized cells. Furthermore, when the permeabilized cells were immobilized to a graphite felt electrode using a calcium alginate matrix containing graphite powder, a high removal efficiency was achieved (4.38 nmol/min mg cell) that was comparable to the result when using the free permeabilized cells.