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        검색결과 9,512

        4861.
        2012.12 구독 인증기관 무료, 개인회원 유료
        Skin serves as an easily accessible source of multipotent stem cells with potential for cellular therapies. In pigs, stem cells from skin tissues of fetal and adult origins have been demonstrated as either floating spheres (cell aggregates) or adherent spindle-shaped mesenchymal stem cell (MSC)-like cells depending on culture conditions. The cells isolated from the epidermis and dermis of porcine skin showed plastic adherent growth in the presence of serum and positively expressed a range of surface and intracellular markers that are considered to be specific for MSCs. The properties of primitive stem cells have been observed with the expression of alkaline phosphatase and markers related to pluripotency. Further, studies have shown the ability of skin-derived MSCs to differentiate in vitro along mesodermal, neuronal and germ-line lineages. Moreover, preclinical studies have also been performed to assess their in vivo potential, and the findings appear to be effective in tissue regeneration at the defected site after transplantation. The present review describes the recent progress on the biological features of porcine skin-derived MSCs as adherent cells, and summarizes their potential in advancing stem cell based therapies.
        4,000원
        4862.
        2012.12 구독 인증기관 무료, 개인회원 유료
        To evaluate the acute to chronic effects of crude oil exposure on hematological and blood biochemical toxicities, Sprague-Dawley rats were given oral doses of 0, 50, or 100 mg/kg BW/day of Iranian heavy crude oil for a period of four weeks. In the acute phase of exposure (one day after four weeks of oil treatment), decreases in weight of thymus, serum level of interferon gamma (IFN-γ), superoxide dismutase (SOD), and catalase activities in liver or kidney, and increase in weight of adrenal gland occurred after oral administration of crude oil. In body weight, histopathological examination, hematological and blood biochemical analyses in the acute phase of exposure, no significant differences were observed among the experimental groups. In the subchronic and chronic phase of exposure (two months and six months after four weeks of oil treatment), the changes of biomarkers were normalized, except the indicators of oxidative stress. Our findings showed that the bioassay on the indicators of oxidative stress is a sensitive method for determining exposure to crude oil in rats.
        4,000원
        4863.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was carried out to effects of ethylene glycol concentration, sucrose and culture day of in vitro production embryo on slow-down freezing in Hanwoo. 6, 7, 8 and 9 day embryos produced in vitro were frozen using 1.8M EG+0.1M sucrose, 1.8M EG+0.5% BSA and 1.5M EG+0.1M sucrose media. Survivability was confirmed after frozen-thawed 24 and 48h and ICM, TE cell number were counted by Hoechst 33342 and PI staining after frozen-thawed 24h. As a result, 1.8M EG+0.1M sucrose group was most significantly (p<0.05) higher compared with the other treatment groups on survivability, TE and total cell number after frozen-thawed 24h (, and ). ICM number did not found significant (p<0.05) differences between the three treatment groups. in 6, 7, 8 and 9 day of embryos using three types of freezing media, frozen-thawed, 1.8M EG+0.1M sucrose groups with embryos cultured 8 day was significantly (p<0.05) highest survivability to after frozen-thawed 24h. 1.5M EG+0.1 sucrose group with embryos cultured 9 day was significantly higher survivability than group of embryos cultured 8 day after frozen-thawed 24 and 48h. In conclusion, 1.8M EG+0.1M sucrose media is considered to be effective to cryopreservation of embryos cultured 8 and 9 day.
        4,000원
        4864.
        2012.12 구독 인증기관 무료, 개인회원 유료
        This study aimed at investigating whether a porcine follicular fluid (pFF) supplementation positively affects the characteristics of donor cells and the developmental competence of porcine cloned embryos. Ear fibroblast cells (donor cell) from an Massachusetts General Hospital miniature pig were cultured in different culture methods: (1) Dulbecco's modified Eagle's medium (DMEM)+10% FBS (Control); (2) DMEM+0.5% FBS (SS); and (3) DMEM+10% FBS+10% pFF (pFF) for 72 h. In each conditioned medium, the concentrations of 4 amino acids (Thr, Glu, Pro, and Val) in the pFF group were significantly different from those in the control group (p<0.05 or p<0.01). The proliferation of the cells cultured in the SS group was significantly lower than that of the other treatment groups (p<0.01). The population of apoptotic and necrotic cells in the SS group was significantly higher than that of either the control or the pFF group (p<0.01). The number of embryos that cleaved (p<0.05) and developed into blastocysts (p<0.01) in the SS group was significantly lower than that of either the control or the pFF group. Compared to other groups, the blastocysts produced from the donor cells in the pFF group had higher total cells and lower apoptotic cells (p<0.05). It can be concluded that pFF supplementation in the donor cell culture medium positively affects cell death, cell cycle and quality of the cloned blastocyst.
        4,000원
        4865.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A fabrication method to improve the processability of thermoplastic carbon nanotube (CNT) mat composites was investigated by using in-situ polymerizable and low viscous cyclic butylene terephthalate oligomers. The electrical conductivity of the CNT mat composites strongly depended on the compression pressure, and the trend can be explained in terms of two cases, low and high compression pressure, respectively. High CNT mat content in the CNT mat composites and the surface of the CNT mat composites with fully contacted CNTs was achieved under high compression pressure, and direct contact between four probes and the surface of the CNT mat composites with fully contacted CNTs gave resistance of 2.1Ω. In this study the maximum electrical conductivity of the CNT mat composites, obtained under a maximum applied compression pressure of 27 MPa, was 11 904 S m-1, where the weight fraction of the CNT mat was 36.5%.
        4,000원
        4866.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, reduced graphene oxide/polyimide (r-GO/PI) composite films, which showed significant enhancement in their electrical conductivity, were successfully fabricated. GO was prepared from graphite using a modified Hummers method. The GO was used as a nanofiller material for the preparation of r-GO/PI composites by in-situ polymerization. An addition of 20 wt% of GO led to a significant decrease in the volume resistivity of composite films by less than nine orders of magnitude compared to that of pure PI films due to the electrical percolation networks of reduced GO created during imidization within the films. A tensile test indicated that the Young's modulus of the r-GO/PI composite film containing 20 wt% GO increased drastically from 2.3 GPa to 4.4 GPa, which was an improvement of approximately 84% compared to that of pure PI film. In addition, the corresponding tensile strength was found to have decreased only by 12%, from 113 MPa to 99 MPa.
        4,000원
        4867.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Polyacetylene (PA) films with vertically aligned fibril morphology were synthesized in homeotropic nematic liquid crystal (N-LC) solvent by using a magnetic field of 5 Tesla as an external perturbation. Scanning electron microscope (SEM) photographs indicated that the lengths of fibrils from the substrate were 5-35μm, depending on polymerization time. Carbonization was carried out using iodine-doped PA film and a morphology-retaining carbonization method. From the SEM results, we confirmed that the vertical morphology of the PA remains unchanged even after carbonization at 800℃. The weight loss of the films due to carbonization at 800℃ is about 20% of the weight of the film before iodine doping. It is expected that vertically aligned carbon might be a precursor for preparing vertical graphite materials, which materials could be useful for electrochemical energy storage and cell electrodes.
        3,000원
        4868.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Graphite oxide (GO) was produced using the modified Hummer's method. Poly(p-phenylene sulfide) (PPS)/reduced graphite oxide (RGO) composites were prepared by in situ polymerization method. The electrical conductivity of the PPS/RGO composites was no more than 82 S/m. It was found that as GO content increased in the PPS/RGO composites, the crystallization temperature and electrical conductivity of the composites increased and the percolation threshold value was at 5-8 wt% of GO content.
        4,000원
        4869.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Orange peel (OP) exhibits a sorption capacity towards anionic dyes such as reactive blue 19 (RB19). Cetyltrimethylammonium bromide (CTAB) as a cationic surfactant was used to modify the surface nature of OP to enhance its adsorption capacity for anionic dyes from an aqueous solution. Four adsorbents were investigated: the OP, sodium hydroxide-treated OP (SOP), CTAB-modified OP and CTAB-modified SOP. The physical and chemical properties of these sorbents were determined using nitrogen adsorption at 77 K and by scanning electron microscope and Fourier transform infrared spectroscopy techniques. The adsorption of the RB19 dye was assessed with these sorbents at different solution pH levels and temperatures. The effect of the contact time was considered to determine the order and rate constants of the adsorption process. The adsorption data were analyzed considering the Freundlich, Langmuir, Elovich and Tempkin models. The adsorption of RB19 by the assessed sorbents is of the chemisorption type following pseudo-first-order kinetics. CTAB modification brought about a significant increase in RB19 adsorption, which was ascribed to the grafting of the sorbent with a cationic surfactant.
        4,000원
        4870.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The process of embryo implantation requires physical contact and physiological communication between the conceptus trophectoderm and the maternal uterine endometrium. During the peri-implantation period in pigs, the conceptus undergoes significant morphological changes and secretes estrogens, the signal for maternal recognition of pregnancy. Estrogens secreted from the conceptus act on uterine epithelia to redirect , luteolysin, secretion from the uterine vasculature to the uterine lumen to prevent luteolysis as well as to induce expression of endometrial genes that support implantation and conceptus development. In addition, conceptuses secrete cytokines, interferons, growth factors, and proteases, and in response to these signals, the uterine endometrium produces hormones, protease inhibitors, growth factors, transport proteins, adhesion molecules, lipid molecules, and calcium regulatory molecules. Coordinated interactions of these factors derived from the conceptus and the uterus play important roles in the process of implantation in pigs. To better understand mechanism of implantation process in pigs, this review provides information on signaling molecules at the conceptus-uterine interface during early pregnancy, including recently reported data reported.
        4,200원
        4871.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Methanol as a carbon source in chemical vapor deposition (CVD) graphene has an advantage over methane and hydrogen in that we can avoid optimizing an etching reagent condition. Since methanol itself can easily decompose into hydrocarbon and water (an etching reagent) at high temperatures [1], the pressure and the temperature of methanol are the only parameters we have to handle. In this study, synthetic conditions for highly crystalline and large area graphene have been optimized by adjusting pressure and temperature; the effect of each parameter was analyzed systematically by Raman, scanning electron microscope, transmission electron microscope, atomic force microscope, four-point-probe measurement, and UV-Vis. Defect density of graphene, represented by D/G ratio in Raman, decreased with increasing temperature and decreasing pressure; it negatively affected electrical conductivity. From our process and various analyses, methanol CVD growth for graphene has been found to be a safe, cheap, easy, and simple method to produce high quality, large area, and continuous graphene films.
        4,000원
        4872.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Transgenic rats and mice are useful experimental animal models for medical research including human disease model studies. Somatic cell nuclear transfer (SCNT) technology is successfully applied in most mammalian species including cattle, sheep, pig and mouse. SCNT is also considered to increase the efficacy of transgenic/knockout mouse and rat production. However, in the area of reproductive biotechnology, the rodent model is inadequate because of technical obstacles in manipulating the oocytes including intracytoplasmic sperm injection and SCNT. In particular, success of rat SCNT is very limited so far. In this review, the history of rodent cloning is described.
        4,000원
        4873.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        예이츠의 환상록 속의 신비적-환상적 작품은 두 가지 인식 흐름, 즉 하 향적이거나 상향적 움직임, 다시 말해서 신적 존재의 하향적 목소리와 인간의 상향적 목소리의 흐름을 보인다. 이원적 의식의 흐름은 곧 시인의 인식론적 마음을 표현하는 과정이며, 불교의 중도론적 인식 과정을 대변한다. 예이츠의 신비학도 이 불가지 세계 에 대한 인식론적 반응이며, 대체적으로그의 문학적 의도성은 시인의 원소론적 마음을 드러내는 고정, 심학(心學)이라고 할 수 있다. 다만 만성제야 시에 드러나듯이, 4 원소 인의 인식 형상이 인식론적 도식화 과정의 어려움을 대변해준다.
        4,600원
        4874.
        2012.12 구독 인증기관 무료, 개인회원 유료
        We would like to present three aspects of Jeju global governance of World Heritages in Jeju Island. To accomplish its international designations, including the UNESCO triple crown, intangible cultural heritages, and RAMSAR wetlands sites, the Jeju Government has created a GIS system where 5 types of land-use have been successfully designated and managed for the preservation of the Environment: 1) Absolutely Preserved Zone, 2) Relatively Preserved Zone, 3) City Planning District, 4) Preserved Eco-System District, 5) Preserved Scenery District. Through these 5 land-use categories, we can see how as a whole, the land is managed, protected, and kept pristine.Jeju must embody the three goals of the Jeju Declaration: “Scaling up Conservation,” “Nature-based Solutions,” and “Sustainability in Action.” Jeju has the ability to mobilize communities to work for biodiversity conservation and sustainable development. Jeju also has the ability to halt biodiversity loss and apply nature-based solutions to conserve biodiversity, enhance resilience, and so improve the well-being of the people on the island and in turn to improve the well-being of the people on the planet. To actualize practices of 4 Jeju Motions (M067; Establishment of an Integrated Management System for UNESCO Protected Areas, M 108 : Supporting the Sustainability of Jeju Haenyeos as a Unique Marine Ecology Stewardship, M 162 : The Development of an Evaluation and Certification System for World Environment Hubs and unapproved motion, M 181 : Protection of the People, Nature, Culture and Heritage of Gangjeong Village), Jeju National University opens Peace Island Leadership School. We also need to involve in an initiativeto integrate each component into a framework of a World Environment University grounded in the Island province of Jeju in South Korea. Within that framework the establishment of a Green Growth and Travelism Institute is a priority element. As a torchbearer of the green growth 2050 vision, this is envisaged as the centre of a virtual global network of related organizations and institutions.
        6,100원
        4875.
        2012.12 구독 인증기관 무료, 개인회원 유료
        Research and technology has been transforming the agriculture to agribusiness which encompasses all operations with all the connections from faming per se, to manufacture & distribution of production supplies and farm commodities. Further, with the revolutionary development of information technology in the last two decades, we cannot talk about agribusiness process alone without considering the information technology embedded in the artifact, process, and structure. Despite the emergence of precision agriculture (PA) which is supported by IT based innovations which can not only improve efficiency in farming operations but also contribute to environmental sustainability, the adoption of IT among farmers and in agriculture industry are rather low than expected. Thus, Korean government has been seeking to converge IT into food, agriculture, forestry and fisheries to improve the competency of the agribusiness, and much progress has been made. This paper investigated the status quo of the current IT convergence with Food, Agriculture, Forestry and Fisheries in Korea, and further proposed future policy directions.
        4,000원
        4876.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study presents the effectiveness of a composite structure at improving blast resistance. The proposed composite structure consists of carbon fiber reinforced polymer (CFRP) and steel layers. While CFRP layer is used for blast energy reflection due to its high strength, steel layer is used for blast energy absorption due to its high ductility. A dynamic model is used to simulate the elastoplastic behavior of the proposed composite structure subject to blast load. Considering the magnitude variations of a blast event, the probability of failure of each layer is evaluated using reliability analysis. By assigning design probability of failure of each layer in the composite structure, the thickness of layers is optimized. A case study for the design of CFRP-steel composite structure subjected to an uncertain blast event is also presented.
        4,000원
        4879.
        2012.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to identify the effects of tensor fasciae latae-iliotibial band (TFL-ITB) self-stretching exercise on the lumbopelvic movement patterns during active prone hip lateral rotation (HLR) in subjects with lumbar extension rotation syndrome accompanying TFL-ITB shortness. Eleven subjects (9 male and 2 female) were recruited for the two-week study. A three dimensional ultrasonic motion analysis system was used to measure the lumbopelvic movement patterns. The TFL-ITB length was measured using the modified Ober's test and was expressed as the hip horizontal adduction angle. The subjects were instructed how to perform TFL-ITB self-stretching exercise program at home. A paired t-test was performed to determine the significant difference in the angle of lumbopelvic rotation, movement onset time of lumbopelvic rotation, TFL-ITB length, and LBP intensity before and after the two-week period of performing the TFL-ITB self-stretching exercise. The results showed that after the intervention, the lumbopelvic rotation angle decreased significantly (p<.05), the movement onset time reduced significantly (p<.05), and LBP intensity decreased slightly but not significantly (p=.07). The hip horizontal adduction angle increased significantly (p<.05) after the intervention. These findings indicate that TFL-ITB stretching exercise increased TFL-ITB length, decreased lumbopelvic rotation angle, and delayed the movement onset time of lumbopelvic rotation after two-weeks. In conclusion, the TFL-ITB self-stretching exercise performed over a period of two weeks may be an effective approach for patients with lumbar extension rotation syndrome accompanying TFL-ITB shortness.
        4,000원
        4880.
        2012.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to investigate the quantitative data of downward pulling tension in subjects with scapular downward rotation syndrome (SDRS) before and after 6-week self scapular upward rotation exercise (SURE) program. Eleven subjects with bilateral SDRS. The downward pulling tension(DPT) was measured digital tension-meter. The tension force data were collected using a surface electromyography before and after a 6-week self-scapular SURE program. The significance of difference between pre- and post-program was assessed using a paired t-test, with the level of significance set at =.05. The results showed that significant differences between pre- and post-SURE program were found for DPT (p<.05). These findings suggest that 6-week self SURE program is effective for reducing DPT in subjects with SDRS. Additionally, our DPT measurement can be useful for maintaining shoulder position and providing quantitative data between pre- and post-SURE program during passive correction of scapular position test.
        4,000원