• Journal of Embryo Transfer
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• v.29 no.2
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• pp.133-139
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• 2014

$K^+$ channels are involved in the regulation of a variety of physiological functions, including proliferation, apoptosis and differentiation, in mammalian cells. Our previous study demonstrated that the blockage of $K^+$ channels inhibits mouse early embryonic development. This study was designed to identify the effect of $K^+$ channels during bovine embryonic development. $K^+$ channel blockers (tetraethylammonium (TEA), $BaCl_2$, quinine, ruthenium red and fluoxetine) were added to the culture medium during in vitro fertilization (IVF) for 6 h to first identify the short-term effect of these chemicals. Among $K^+$ channel blockers, fluoxetine, which is used as a selective serotonin reuptake inhibitor, significantly increased the blastocyst formation rate by approximately 6% when compared to control. During the in vitro maturation (IVM) of immature oocytes and the in vitro culture (IVC) of embryos, the oocytes and embryos were exposed to fluoxetine for either a short-term (6 h) or a long-term (24 h) to compare the embryonic development in response to exposure time. The 6 h exposure to fluoxetine during IVM did not affect the blastocyst formation rate, but the rate of blastocyst formation was reduced after the 24 h exposure. On the other hand, embryonic development increased approximately 10% in both groups of embryos exposed to fluoxetine for 6 and 24 h during IVC. Taken together, fluoxetine treatment during IVF and IVC, but not IVM, enhances bovine embryonic development. These results suggest that fluoxetine-modulated signals in oocytes and embryos could be an important factor towards enhancing bovine embryonic development.

• Journal of Korean Society for Atmospheric Environment
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• v.8 no.1
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• pp.20-28
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• 1992

The x-ray fluorescence(XRF) is one of the most convenient and widely used techniques for analyzing trace elements in ambient particulate matters. The objects of the study were to estimate the optimum exposure time using the XRF, to investigate the distributions of heavy metal levels in particulate matters, and finally to study seasonal variation for the concentrations of total suspended particulate matters(TSP) and size fractionated particulate matters. The suspended particulate matters had been collected by a cascade impactor having 9 size fragnated stages for 3 years(Dec. 1988 to Nov. 1991) in Kyung Hee University-Suwon Campus. The particulate matters were then collected on each stage by membrane filters. The weight concentrations were determined by the XRF system. Thus, seasonal variations and relationship between concentration and particle size could be investigated. Resulting distribution was bimodal with the coarse and the fine particle groups minimum occurring around 2.1 to 3.3 $\mu$m as an aerodynamic diameter. To determine optimum exposure time of the XRF for various trace inorganic elements, membrane filters and the NIST standard filters were extensively studied. Using a statistical technique, optimum exposure time was estimated for each trace element and overall elements. The time was then determined as 20 seconds for the XRF system. The concentration of TSP was 123.9$\mum/m^3$ on an arithmatic average. The levels of each inorganic metal were Si 2420.0ng/$m^3$, Fe 977.1ng/$m^3$, and so on. The Pb. Zn, and Cu abounded in the fine mode group, while Ca, Fe, Si, Al, and K in the coarse group. Marked seasonal variation of TSP and metal concentrations was observed. The concentration of heavy metals in the fine mode was highest in winter : on the other hand, that in the coarse mode was highest in spring.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.6
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• pp.2477-2483
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• 2014

Azoxymethane (AOM) is a potent genotoxic carcinogen which specifically induces colon cancer. Hyperlipidemia and diabetes have several influences on colon cancer development, with genetic and environmental exposure aspects. Here, we investigated plasma lipid and glucose concentrations in Kunming mice randomized into four groups; control (no AOM or oil exposure), AOM control, AOM + pork oil, and AOM + canola oil. Aberrant crypt foci (ACF), plasma cholesterol, plasma triglyceride, plasma glucose and organ weight were examined 32 weeks after AOM injection. Results revealed that AOM exposure significantly increased ACF number, plasma triglyceride and glucose level. Further, male mice displayed a much higher plasma triglyceride level than female mice in the AOM control group. Dietary fat significantly inhibited AOM-induced hypertriglyceridemia, and canola oil had stronger inhibitory effect than pork oil. AOM-induced hyperglycemia had no sex-difference and was not significantly modified by dietary fat. However, AOM itself not change plasma cholesterol level. AOM significantly increased liver and spleen weight in male mice, but decreased kidney weight in female mice. On the other hand, mice testis weight decreased when fed canola oil. AOM could induce colorectal carcinogenesis, hypertriglyceridemia and hyperglycemia in Kunming mice at the same time, with subsequent studies required to investigate their genome association.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.404-406
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• 2002

We have investigated the contribution of the scattered x rays to the signal imaging in the radiographs acquired with anti-scatter grids of several grid ratios by separating the line spread functions (LSFs) derived from the signal edge image into the primary and the scatter components. By using a 1.0-mm lead plate in the scattering material, the blurred signal edge images were acquired by use of an imaging plate at a tube voltage of 80 kV with the anti-scatter grids of grid ratios for 5:1, 6:1, 8:1, 10:1 and 12:1. The edge profiles of the signal images were scanned and those in relative exposure were differentiated to obtain the LSFs. To investigate the contribution of the scattered x rays to the signal imaging, we proposed a method for separating the LSFs derived from the signal images into the primary and the scatter components, where the scatter component was approximated with exponential function. Our basic approach is to separate the area of the LSFs by ratios of the scattered x-ray exposure to the primary x-ray exposure, which were obtained for the grid ratios by use of a lead disk method. The LSFs and the two components were Fourier transformed to obtain the modulation transfer functions (MTFs) and their two components. As the result, we found that, by using the anti-scatter grids, the scattered x rays were reduced, but the shape of the LSFs of the scatter component hardly changed. The contributions of the scatter component to the MTFs were not negligible (more than 10 %) for spatial frequencies lower than about 1.0 mm$\^$-l/ and that was greater as the grid ratio decreasing. On the other hand, for higher frequencies, the primary component was dominant compared with the scatter component.

• Development and Reproduction
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• v.20 no.2
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• pp.91-99
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• 2016

Lipopolysaccharide (LPS), an endotoxin, elicits strong immune responses in mammals. Several lines of evidence demonstrate that LPS challenge profoundly affects female reproductive function. For example, LPS exposure affects steroidogenesis and folliculogenesis, resulting in delayed puberty onset. The present study was conducted to clarify the mechanism underlying the adverse effect of LPS on the delayed puberty in female rats. LPS was daily injected for 5 days ($50{\mu}g/kg$, PND 25-29) to treated animals and the date at VO was evaluated through daily visual examination. At PND 39, animals were sacrificed, and the tissues were immediately removed and weighed. Among the reproductive organs, the weights of the ovaries and oviduct from LPS-treated animals were significantly lower than those of control animals. There were no changes in the weights of uterus and vagina between the LPS-treated and their control animals. immunological challenge by LPS delayed VO. Multiple corpora lutea were found in the control ovaries, indicating ovulations were occurred. However, none of corpus luteum was present in the LPS-treated ovary. The transcription level of steroidogenic acute regulatory protein (StAR), CYP11A1, CYP17A1 and CYP19 were significantly increased by LPS treatment. On the other hand, the levels of $3{\beta}$-HSD, $17{\beta}$-HSD and LH receptor were not changed by LPS challenge. In conclusion, the present study demonstrated that the repeated LPS exposure during the prepubertal period could induce multiple alterations in the steroidogenic machinery in ovary, and in turn, delayed puberty onset. The prepubertal LPS challenge model used in our study is useful to understand the reciprocal regulation of immune (stress) - reproductive function in early life.

• Tribology and Lubricants
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• v.36 no.5
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• pp.267-273
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• 2020

This study experimentally investigates hydrophobic surfaces fabricated via additive manufacturing. Additive manufacturing, commonly known as 3D printing, is the process of joining materials to fabricate parts from 3D model data, usually in a layer-upon-layer manner. Digital light processing is used to fabricate hydrophobic surfaces in this study. This method uses photo-curable resins and ultraviolet (UV) sources. Moreover, this technique generally has faster shaping speeds and is advantageous for the fabrication of small components because it enables the fabrication of one layer at a time. Two photo-curable resins with different compositions are used to fabricate micro-patterns of hydrophobic surfaces. The resins are composed of a photo-initiator, monomer, and oligomer. Experiments are conducted to determine suitable process conditions for the fabrication of hydrophobic surfaces depending on the type of resin. The most important factors affecting the process conditions are the UV exposure time and slice thickness. The fabrication capability according to the process conditions is evaluated using the side and top views of the micro-patterns observed using a microscope. The micro-patterns are collapsed and intertwined when the exposure time is short because sufficient light (heat) is not applied to cure the photo-curable resin with a given slice thickness. On the other hand, the micro-patterns are attached to each other when the exposure time is prolonged because the over-curing time can cure the periphery of a given shape. When the slice is thicker, the additional curing area is enlarged in each slice owing to the straightness of UV light, and the slice surface becomes rough.

• Journal of Sensor Science and Technology
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• v.6 no.6
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• pp.445-450
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• 1997

An ammonia gas sensor with high sensitivity using thick-film technology were fabricated and examined. The material for sensing the ammonia gas was the mixture of oxide semiconductor, $FeO_{x}-WO_{3}-SnO_{2}$. The sensor exhibits resistance increase upon exposure to low concentration of ammonia gas. The resistance of the sensor is decreased, on the other hand, for exposure to reducing gases such as ethyl alcohol, methane, propane and carbon monoxide. A novel method for detecting ammonia gas quite selectively utilizing a sensor array consisting of an ammonia gas sensor and a compensation element were proposed and developed. The compensation element is a Pt-doped $WO_{3}-SnO_{2}$ gas sensor which shows opposite direction of resistance change in comparison with that of the ammonia gas sensor upon exposure to ammonia gas. Excellent selectivity has been achieved using the sensor array having two sensing elements.

• Safety and Health at Work
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• v.5 no.1
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• pp.27-31
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• 2014

Background: Carpal tunnel syndrome (CTS) is a common work-related peripheral neuropathy. In addition to grip force and repetitive hand exertions, wrist posture (hyperextension and hyperflexion) may be a risk factor for CTS among workers. However, findings of studies evaluating the relationship between wrist posture and CTS are inconsistent. The purpose of this paper was to conduct a meta-analysis of existing studies to evaluate the evidence of the relationship between wrist posture at work and risk of CTS. Methods: PubMed and Google Scholar were searched to identify relevant studies published between 1980 and 2012. The following search terms were used: "work related", "carpal tunnel syndrome", "wrist posture", and "epidemiology". The studies defined wrist posture as the deviation of the wrist in extension or flexion from a neutral wrist posture. Relative risk (RR) of individual studies for postural risk was pooled to evaluate the overall risk of wrist posture on CTS. Results: Nine studies met the inclusion criteria. All were cross-sectional or case-control designs and relied on self-report or observer's estimates for wrist posture assessment. The pooled RR of work-related CTS increased with increasing hours of exposure to wrist deviation or extension/flexion [RR = 2.01; 95% confidence interval (CI): 1.646-2.43; p < 0.01: Shore-adjusted 95% CI: 1.32-2.97]. Conclusion: We found evidence that prolonged exposure to non-neutral wrist postures is associated with a twofold increased risk for CTS compared with low hours of exposure to non-neutral wrist postures. Workplace interventions to prevent CTS should incorporate training and engineering interventions that reduce sustained non-neutral wrist postures.

• Elastomers and Composites
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• v.51 no.1
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• pp.1-9
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• 2016

Characterization of the UV oxidation for raw natural rubber (NR) was investigated in controlled conditions through image and FT-IR analysis. The UV oxidation was performed on a thin film of natural rubber coated on a KBr window at 254 nm and room temperature to exclude the thermal oxidation. Before or after exposure to UV light, image of the NR thin film was observed at a right or tilted angle. FT-IR absorption spectra were measured in transmission mode with the UV irradiation time. The UV oxidation of NR was examined by the changes of absorption peaks at 3425, 1717, 1084, 1477, 1377, and $833cm^{-1}$ which were assigned to hydroxyl group (-OH), carbonyl group (-C=O), carbon-oxygen bond (-C-O), methylene group $(-CH_2-)$, methyl group $(-CH_3)$, and cis-methine group $(cis-CCH_3=CH-)$, respectively. During the initial exposure period, the results indicated that the appearance of carbonyl group was directly related to the reduction of cis-methine group containing carbon-carbon double bond (-C=C-). Most of aldehydes or ketones from carbon-carbon double bonds were formed very fast by chain scission. A lot of long wide cracks with one orientation at regular intervals which resulted in consecutive chain scission were observed by image analysis. During all exposure periods, on the other hand, it was considered that the continuous increment of hydroxyl and carbonyl group was closely related to the decrement of methylene and methyl group in the allylic position. Therefore, two possible mechanisms for the UV oxidation of NR were suggested.

• Archives of Reconstructive Microsurgery
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• v.13 no.1
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• pp.14-23
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• 2004

Introduction: The hand and wrist are particularly susceptible to electrical burn. Skin defect with damage or exposure of underlying vital structure requires coverage by skin flap especially in case of the need for late reconstruction. We are reporting 4 cases of electrical burned hand treated by posterior tibial arterial free flap. The commonly used skin flaps such as scapular flap or groin flap are too bulky so that they are not satisfactory in function and cosmetic appearance. So we tried to cover them with a more thin skin flap. Materials and Method: From January 2002 to June 2003, four cases of hand and wrist electrical burn were covered using posterior tibial arterial free flap. All the cases were due to high voltage electrical burn. Age ranged from 31 years to 38 years old and all the cases were male patients. Recipient sites were 2 wrist, one thenar area and one knuckle of 2.3rd MP joint. Additional procedures were flexor tenolysis (simultaneous), FPL tenolysis and digital nerve graft (later) and extensor tendon reconstruction (later). Result: All the flap have survived totally without any complication including circulatory concern about the donar foot. Posterior tibail arterial free flap was so thin that debulking procedure was not required. Conclusion: For skin coverage of the hand & wrist region, posterior tibial arterial free flap have many advantages such as reliable anatomy, easy dissection and easy anastmosis with radial or ulnar artery and possibility of sensory flap. The most helpful advantage for hand coverage is its thinness. So we think this flap is one of the very useful armamentarium for reconstructive hand surgery.