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        검색결과 9,762

        4681.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Activated carbon fibers (ACFs) were prepared from cost effective commercial textiles through stabilization, carbonization, and subsequently activation by carbon dioxide. ACFs were characterized for surface area and pore size distribution by physical adsorption of nitrogen at 77 K. ACFs were also examined for various surface characteristics by scanning electron microscopy, Fourier transform infrared spectroscopy, and CHNO elemental analyzer. The prepared ACFs exhibited good surface textural properties with well developed micro porous structure. With improvement in physical strength, the commercial textile grade acrylic precursor based ACFs developed in this study may have great utility as cost effective adsorbents in environmental remediation applications.
        3,000원
        4683.
        2011.03 구독 인증기관 무료, 개인회원 유료
        To investigate the effect of carnosine on exhaustive exercise, swimming tests were conducted weekly with loads corresponding to 5% of body weight attached to the tails of mice, and the swimming time to exhaustion was measured. Eighty male ICR mice were divided into four groups, to which carnosine was administered at doses of 0 (control), 10, 50, and 250 mg/kg/day, respectively, for a period of four weeks. At the end of swimming exercise challenges, serum biochemistry, oxidative stress enzyme activity, and antioxidant enzyme activity in tissues were determined. Treatment with 250 mg/kg carnosine resulted in a significant increase in swimming times to exhaustion, compared to the control group in the first (P<0.01) and third week (P<0.05). Significantly lower serum lactate levels were observed after the swimming exercise in the carnosine-treated groups (10 and 250 mg/kg), compared with the control (P<0.01). Malondialdehyde levels in the liver (10 and 50 mg/kg carnosine treated groups) and skeletal muscle (250 mg/kg carnosine treated group) were significantly lower, compared with the control (P<0.05). Significantly lower protein carbonyl levels in skeletal muscle were observed in the 50 and 250 mg/kg carnosine treated groups, compared with the control (P<0.01). Superoxide dismutase and glutathione peroxidase activities in skeletal muscle did not differ significantly among the groups. These results indicate that carnosine may improve swimming exercise capacity by attenuating production of lactate and reducing oxidative stress in mice.
        4,300원
        4684.
        2011.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We study the relationships between the thermal emissivity of nuclear graphites (IG-110, PCEA, IG-430 and NBG-18) and their surface structural change by oxidation using scanning electron microscope and X-ray diffraction (XRD). The nonoxidized (0% weight loss) specimen had the surface covered with glassy materials and the 5% and 10% oxidized specimens, however, showed high roughness of the surface without glassy materials. During oxidation the binder materials were oxidized first and then graphitic filler particles were subsequently oxidized. The 002 interlayer spacings of the non-oxidized and the oxidized specimens were about 3.38~3.39a. There was a slight change in crystallite size after oxidation compared to the nonoxidized specimens. It was difficult to find a relationship between the thermal emissivity and the structural parameters obtained from the XRD analysis.
        4,000원
        4685.
        2011.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Larix kaempferi is a tree with a major economic impact and is processed in large quantity every year in Korea. This study was carried out to collect basic data for the reasonable use of Larix kaempferi and to investigate the relation between anatomical properties and modulus of rupture (MOR) for heartwood and sapwood. As the length of earlywood tracheid and the radial wall thickness of earlywood tracheid and latewood tracheid increased, the modulus of rupture (MOR) increased, but decreased with increasing microfibril angle. Statistical analysis by the stepwise regression technique shows that the main factors affecting the modulus of rupture (MOR) of heartwood are the microfibril angle and the radial wall thickness of latewood tracheid, while those affecting MOR of sapwood are the length of earlywood tracheid and the microfibril angle.
        4,000원
        4686.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        HACCP is applicable when there are control measures which can be applied to prevent, eliminate, or reduce the occurrence of a food safety hazard to a consumer, but much of the life cycle of a food does not lend itself to strict application of HACCP principles. FSIS HACCP is mandatorily applied to meat and poultry slaughter and processing establishments to reduce harmful bacteria on their products. FSIS manages the HACCP plants under continuous inspection of the FSIS inspectors: Inspector in Charge (IIC), Public Health Veterinarian (PHV), on line/off line Consumer Safety Inspectors (CSI). More than 7,600 inspection personnel inspect nearly 6,500 meat, poultry, and egg processing plants, and verify that regulations regarding food safety and other consumer protection concerns are met. But only half of violations observed are recorded on the non-compliance report due to inspector shortages. The change from traditional sanitation system to HACCP system has been difficult because of several factors: Lack of technical expertise in processing facilities makes a scientific hazard analysis difficult, preventive measures and validation efforts are not supported by data, plant management and inspectors concentrate on what they know, plants are still very dependent on the regulatory agency for guidance, focus is on regulatory procedures more than determining food safety issues, and also plants are less efficient at producing and maintaining records that are not specifically tied to production lots. However HACCP is an effective tool in food safety continuum.
        4,000원
        4687.
        2010.12 구독 인증기관 무료, 개인회원 유료
        Cells that have endogenous multipotent properties can be used as a starting source for the generation of induced pluripotent cells (iPSC). In addition, small molecules associated with epigenetic reprogramming are also widely used to enhance the multi- or pluripotency of such cells. Skinderived precursor cells (SKPs) are multipotent, sphereforming and embryonic neural crest-related precursor cells. These cells can be isolated from a juvenile or adult mammalian dermis. SKPs are also an efficient starting cell source for reprogramming and the generation of iPSCs because of the high expression levels of Sox2 and Klf4 in these cells as well as their endogenous multipotency. In this study, valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, was tested in the generation of iPSCs as a potential enhancer of the reprogramming potential of SKPs. SKPs were isolated from the back skins of 5-6 week old C57BL/6 X DBA/2 F1 mice. After passage 3, the SKPs was treated with 2 mM of VPA and the quantitative real time RT-PCR was performed to quantify the expression of Oct4 and Klf4 (pluripotency specific genes), and Snai2 and Ngfr (neural crest specific genes). The results show that Oct4 and Klf4 expression was decreased by VPA treatment. However, there were no significant changes in neural crest specific gene expression following VPA treatment. Hence, although VPA is one of the most potent of the HDAC inhibitors, it does not enhance the reprogramming of multipotent skin precursor cells in mice.
        4,000원
        4688.
        2010.12 구독 인증기관 무료, 개인회원 유료
        Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most prevalent pathogens in hospitals. To investigate cross contamination by this bacterium in both dental and medical settings, the pathogens that cause acute pyogenic infection and one of the major microbes responsible for nosocomial infection were isolated from health care providers, nurses and patients. We used VITEK II to measure drug sensitivity, and we further performed biochemical testing, coagulase serotype testing and pulse-field gel electrophoresis (PFGE) for isolated MRSA colonies. The isolation rate of Staphylococcus aureus from nasal swabs was 75.0% from dental health care providers and 18.8% from the medical health care providers. A total of 10 MRSA strains were isolated from 40 health care providers and 2 patients and the prevalent coagulase serotype from patients and health care providers was VII. The antimicrobial drug resistance and partial PFGE types of the isolated MRSA strains showed a similar pattern. These results suggest that MRSA may be one of the principal causes of nosocomial infection in dental and medical hospitals.
        4,000원
        4689.
        2010.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        According to the historical documents and paintings in many civilizations, rocks that fell from the sky fascinated humans as the message from the God or supernaturals. Scientific progress allows humans to recognize these exciting extraterrestrial objects as meteorites. Meteorites contain a wealth of pivotal information regarding formation of the early Solar System. Meteorites also provide broader scientific insights on, for example, the origin of life, interplanetary transfer of life forms, massive depletion of biosphere on Earth, and evolution of lithosphere on Earth-like planetary bodies.
        4,000원
        4690.
        2010.12 구독 인증기관 무료, 개인회원 유료
        Periodontitis is an inflammatory disorder of the periodontium and is characterized by destruction of the tooth supporting tissues, mediated by the upregulation of synthesis and release of a variety of pro-inflammatory factors. Inflammatory cytokines and prostaglandins upregulate RANKL and its subsequent binding to RANK stimulates osteoclast formation, resorption activity, and survival. In our present study, we investigated the effects of HP08-0111, composed of Coptis japonica (Thunb.) Makino, vitamin C and vitamin E, upon inflammatory responses, osteoclastogenesis and alveolar bone loss. HP08-0111 decreased the expression of IL-1β and COX2 on LPS-induced RAW 264.7 cells and inhibited osteoclast-specific genes such as c-Fos, MMP-9, and TRAP. HP08-0111 also exhibited protective effects against alveolar bone loss in rats with ligature-induced periodontitis. Our results suggest that HP08-0111 is potentially an important therapeutic tool for the treatment of disorders associated with bone loss such as periodontitis.
        4,000원
        4691.
        2010.12 구독 인증기관 무료, 개인회원 유료
        This study is Korean traditional heating system, named 'AZABANG'. Ondol characterized by“ Azabang ”is dated back to 119 AD and it has approximately 2000 years history. Among various kinds of traditional radiant floor heating system, Ondol is the most reasonable and scientific one. This type of imaginative Ondol which have superior ability to keep temperature during a long period, roughly 100 days could be attributable to the special structural pattern . The Ondol characterized by "Azabang" represents extraordinary creativeness originated from Korean traditional culture and at the same time, it is the significant evidence that those missing historical rings, in some degree, have been connected. Therefore we well do our best to apply the scientific and reasonable concept into the real world.
        4,000원
        4696.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, the use of thermal conductive polymeric composites is growing up, where the polymers filled with the thermally conductive fillers effectively dissipate heat generated from electronic components. Therefore, the management of heat is directly related to the lifetime of electronic devices. For the purpose of the improvement of thermal conductivity of composites, fillers with excellent thermally conductive behavior are commonly used. Thermally conductive particles filled polymer composites have advantages due to their easy processibility, low cost, and durability to the corrosion. Especially, carbon-based 1-dimensional nanomaterials such as carbon nanotube (CNT) and carbon nanofiber (CNF) have gained much attention for their excellent thermal conductivity, corrosion resistance and low thermal expansion coefficient than the metals. This paper aims to review the research trends in the improvement of thermal conductivity of the carbon-based materials filled polymer composites.
        4,000원
        4697.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Four estrus-induced Himalayan tahrs (Hemitragus jemlahicus) were inseminated with frozen-thawed semen by laparoscopic or transcervical insemination techniques with no regard to the site of ovulation in non-breeding season. In June and July, 2009, estrus was synchronized by Eazi-Breed (Controlled internal drug release; Pfizer Animal Health, New Zealand) insertion for 16 days and PG 600 (PMSG 400IU, hCG 200 IU; Intervet, Netherlands) injection (IM) a day before removing . Forty eight hours later, laparoscopic or transcervical insemination was done to each of two tahrs under anesthetic condition inducted by ketamine (1.5 mg/kg) and medetomidine (0.09 mg/kg). For examination of estradiol and progesterone, blood was collected right before insertion, PG 600 injection, removal and insemination. Estradiol levels of four tahrs (No. 1, 2, 3, 4) before insertion and insemination were 13.3, 8.8, 14.3, 12 pg/ml and 23.5, 25.5, 21.1, 11.5 pg/ml, respectively. Progesterone levels of four tahrs (No. 1, 2, 3, 4) before insertion and insemination were 1.8, 0.05, 0.63, 0.61 ng/ml and 1.03, 0.37, 1.48, 2.12 ng/ml. Except for No. 4 tahr, cervices showed cervical mucus and opened enough to penetrate with embryo transfer gun sheet usually used for cows. Therefore, No.4 was laparoscopically inseminated together with No. 1. In conclusion, none of four Himalayan tahrs was pregnant. However, we proved that estrus could be induced by CIDR and PG 600 injection in non-breeding season, and laparoscopic or transcervical insemination with frozen-thawed semen could be one of assisted reproductive techniques in Himalayan Tahr.
        4,000원
        4698.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        On January 6, 2010, two months earlier than normal breeding season, a red fox vixen was implanted with synthetic GnRH analogue, Deslorelin. Blood was sampled every 2~3 days from the day of implant to identifying spermatozoa on stains of epithelial cells. Estradiol and progesterone were examined. Even though the vixen was in non-breeding season, she was mated by a male fox. Pregnancy was confirmed by canine pregnancy detection kit that detect relaxin released from placenta. Four healthy pups were born on March 9, 2010. This is the first report showing synthetic GnRH can activate ovarian function and lead to fertile estrus of red fox in non-breeding season.
        3,000원
        4699.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Novel unsaturated polyester composites with PAN-based nanofiber, stabilized PAN nanofiber, and carbonized nanofiber webs have been fabricated, respectively, and the effects of the nanofiber web content on their electrical resistivity, the thermal stability, dynamic storage modulus, and fracture surfaces were studied. The result demonstrated that the introduction of just one single layer (which is corresponding to 2 wt.%) of the carbonized nanofiber web to unsaturated polyester resin (UPE) could contribute to reducing markedly the electrical resistivity of the resin reflecting the percolation threshold, to improving the storage modulus, and to increasing the thermal stability above 350℃. The effect on decreasing the resistivity and increasing the modulus was the greatest at the carbonized PAN nanofiber web content of 8 wt.%, particularly showing that the storage modulus was increased about 257~283% in the measuring temperature range of -25℃ to 50℃. The result also exhibited that the carbonized PAN nanofibers were distributed uniformly and compactly in the unsaturated polyester, connecting the matrix three-dimensionally through the thickness direction of each specimen. It seemed that such the fiber distribution played a role in reducing the electrical resistivity as well as in improving the dynamic storage modulus.
        4,000원
        4700.
        2010.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 시험은 국화에서의 기형화 발생과 DNA 메틸레 이션에 관여하는 S-adenosyl-L-homocysteine hydrolase (SAHH) 유전자 발현과의 관련성을 검토하기 위해 수행 하였다. 스프레이 국화 ‘Lerbin’은 단일후 14일에서 27일 사이에 고온과 장일 조건에서 기형화가 발생되어, 35/20oC 의 고온과 14시간의 장일 처리 할 경우 25/20oC(12 h/ 12 h)에 비해 설상화가 2배 이상 증가하는 양상을 보였다. 스프레이 국화 ‘Lerbin’에서 분리한 전장 cDNA (DgSAHH) 는 크기가 1455 bp로 다른 작물과 90%이상의 높은 상동 성을 나타내었다. 국화의 DgSAHH 유전자 발현은 기형화 발생을 유도하는 고온과 장일 조건에서 크게 감소하였다. 이러한 결과를 통해 국화의 화아 발달에 있어서 DgSAHH 유전자 발현은 온도와 일장의 영향을 받으며, 억제된 이 유전자의 발현이 기형화 발생에 관여할 수 있을 것으로 판단된다.
        4,000원