• Investigative Magnetic Resonance Imaging
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• v.4 no.1
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• pp.27-33
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• 2000

Purpose: To determine the electronic spin relaxation times, $T_{le}$, of three commercially available Gd-chelated MR contrast agents, Gd-DTPA, Gd-DTPA-BMA and Gd-DOTA, using Electron Paramagnetic Resonance(EPR) technique. Material and Methods: The paramagnetic MR contrast agents, Gd-DTFA(Magnevist) , Gd-DTFA-BMA(OMNISCAN) and Gd-DOTA(Dotarem), were used for this study, The EPR spectra of these contrast agents, which were prepared 2:1 methanol/water solution, were obtained at low temperatures, from $-160^{\circ}C~20^{\circ}C$. The glassy-state EPR spectra for these contrast agents were then fitted by the simulation spectra generated with different zero-field splitting (ZFS) parameters by a computer simulation program 'GEN', which generates the EPR powder spectrum using a given ZFS in $3{\times}3$ tensor. Finally, the spin relaxation times of the contrast agents were then determined from the $T_{2e}$, D, and E values of the best simulation spectra using the McLachlan's theory of average relaxation rate. Results: The electronic transverse spin relaxation times, $T_{2e}'s$, of Gd-DTPA, Gd-DTPA-BMA and Gd-DOTA were 0.113ns, 0.147ns and 1.81ns respectively. The g-values were 1.9737, 1.9735 and 1.9830 and the electronic spin relaxation times, $T_{1e}'s$, were 18.70ns, 33.40ns and $1.66{\mu}s$, respectively. Conclusion: The results of these studies reconfirm that the paramagnetic MR contrast agents with larger ZFS parameters should have shorter $T_{1e}'s$. Among three contrast agents used for this study, Gd-DOTA chelated with cyclic ligand structure shows better electronic property then the others with linear structure. Thus, it is concluded that the exact determination of ZFS parameters is the important factor in evaluating relaxation enhancement effect of the agents and in developing new contrast agents.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.92-99
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• 2005

To discriminate the provenance of shelf sediments in the East China Sea, textural and elemental compositions along with strontium isotopic ratio ($^{87}Sr/^{86}Sr$) were analyzed and compared with the sediments originated from Chinese rivers. The sediments in the study area are composed of fine-grained mud with a mean grain size of $47\;{\phi}$ and their $CaCO_3$, contents range from 3.9 to 11.5% (average 7.6%). In the study area, the content of most metallic elements are strongly constrained by sediment grain size (quartz dilution effect) and that of biogenic material and, thereby, their spatial distribution seems not enough for understanding sediment provenance in the study area. The muddy sediments of the Yangtze river have much lower $^{87}Sr/^{86}Sr$ ratio ($0.71197{\sim}0.71720$) than the Yellow Sea shelf muddy sediments which are supposed to be originated from the Huanghe river ($0.72126{\sim}0.72498$), suggesting the distribution pattern of $^{87}Sr/^{86}Sr$ ratios as a new tracer to discriminate the provenance of shelf sediments in the study area. Different source rock compositions and weathering processes between both drainage basins may account for the differences in $^{87}Sr/^{86}Sr$ ratio. Although the ratios show wide range, from 0.71445 to 0.72184 with an average 0.71747 in the study area, they are close to the values of the Yangtze river sediments, suggesting that the sediments were mainly originated from the Yangtze river. The previous studies on the dispersal pattern of modern sediments and the physico-chemical properties of seawater in the Yellow and East China seas support the possibility that the fine-grained Yangtze river sediments can reach to the East China Sea shelf as well as to the southeastern Yellow Sea.

• Korean Journal of Plant Resources
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• v.31 no.5
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• pp.489-497
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• 2018

In Korea, common and Tartary buckwheat are cultivated mainly in spring and fall, however the available buckwheat varieties are still very limited. In this study, we have evaluated buckwheat germplasm for agronomic traits and compared flavonoids contents in different cultivation period and collection area. In common buckwheat, the number of days from sowing to flowering was 40 and 31 days and from sowing to maturity took 90 and 69 days in spring and fall cultivation, respectively. The number of nodes and branches were higher in spring cultivation while the hundred seed weight was higher in fall cultivation. The average flavonoids contents in common buckwheat were 0.20 mg/g dry weight (DW) and 0.40 mg/g DW in spring and fall cultivation, respectively. The highest flavonoids content was detected in Jeonnam accessions with 0.29 mg/g DW and 0.43 mg/g DW during spring and fall cultivation, respectively. The flavonoids contents were varied from 1.5 to 2.5 times according to the collection area. These results suggest that the agronomic traits and flavonoids contents were vary depending on the cultivation environment and germplasm collection area. Therefore, it is necessary to select the material by considering the characteristics of the germplasm for breeding of new varieties.

• 한국환경농학회:학술대회논문집
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• 2009.07a
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• pp.273-282
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• 2009

The transmissible spongiform encephalopathies (TSEs) disease group are fatal neurodegenerative disorders affecting a wide range of hosts. The group includes kuru and Creutzfeldt-Jakob disease (CJD) in humans, scrapie in sheep and goats and Bovine spongiform encephalopathy (BSE) in cattle. The exact nature of the infectious agent involved in the transmission of these diseases remains controversial. However, a central event in their pathogenesis is the accumulation in infected tissues of an abnormal form of a host-encoded protein, the prion protein (PrP). Whereas the normal cellular protein is fully sensitive to protease ($PrP^{sen}$), the disease-associated prion protein ($PrP^d$) is only partly degraded ($PrP^{res}$), its amino-terminal end being removed. BSE was first reported in the mid-80s in the UK. Ten years later, a new form of human prion disease, variant CJD (vCJD) developed in the wake of the BSE epidemic, and there is now strong scientific evidence that vCJD was initiated by the exposure of humans to BSE-infected tissues, thus indicating a zoonotic disease. However, the ban on the feeding of animal-derived proteins to ruminants, and the apparent lack of vertical transmission of BSE, have led to a decline in the incidence of the disease within cattle herd and therefore, an assumed decreased risk for human contacting vCJD. The origin of the original case(s) of BSE still remains an enigma even though three hypotheses have been raised. Hypotheses are i) sheep- or goat-derived scrapie-infected tissues included in meat and bone meal fed to cattle, ii) a previously undetected sporadic or genetic bovine TSE contaminating cattle feed or iii) originating from a human TSE through animal feed contaminated with human remains. A host cellular membrane protein ($PrP^C$), which is abundant in central nervous system tissue, appear to be conformationally altered in the diseased host into a prion protein ($PrP^{Sc}$). This $PrP^{Sc}$ is detergent insoluble and partially protease-resistant ($PrP^{res}$). The term $PrP^{res}$ is normally used to describe the protein detected after protease treatment, in techniques such as Western immunoblotting, and enzyme-linked immunosorbant assay using fresh/frozen tissue. Immunohistochemistry may performed with formalin-fixed tissues. Also, clinical signs of the BSE are one of the major diagnostic indicators. Recently, atypical forms (known as H- and L-type) of BSE have appeared in several European countries, Japan, Canada and the United States. An unusual case was also reported in a miniature zebu. The atypical BSE fall into two groups based on the relative molecular mass (Mm) of the unglycosylated $PrP^{res}$ band relative to that of classical BSE, one of the higher Mm (H-type) and the other lower (L-type). Both types have been detected worldwide as rare cases in older animals, at a low prevalence consistent with the possibility of sporadic forms of prion diseases in cattle. This raises the unwelcome possibility that vCJD could increase in the human population. Now, active surveillance program against BSE is going on in Korea. In regional veterinary service lab, ELISA is applied to screen the BSE in slaughter and confirmatory tests by Western immunoblotting and immunohistochemisty are carried out if there are positive or suspect in the screening test. Also, the ruminant feed ban is rigorously enforced. Removal of specified risk materials such as brain and spinal cord from cattle is mandatory process at slaughter to prevent the infected material from entering the human food chain.

• Ecology and Resilient Infrastructure
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• v.7 no.3
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• pp.208-217
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• 2020

A biopolymer based on microorganism-derived β-glucan and xanthan gum is being studied as a new eco-friendly material that stabilizes the riverbank slope, and also promotes vegetation growth. However, it is still inconclusive whether biopolymers have a positive effect on plant performance in the riverbanks which are subjected to various climatic factors and plant competitions. For a practical ecological evaluation of the biopolymers, their effect on plant growth promotion was studied in a natural environment. Considering the relationship between competition and plant community formation, the effects of biopolymers on competition were also investigated. For four plant species (Echinochloa crus-galli, Pennisetum alopecuroides, Leonurus japonicus, and Coreopsis lanceolata), the biopolymer effects under intra/interspecific competition were tested at the riverbank (20 m × 10 m) near Samjigyo Bridge in Damyang-gun, Jeollanam-do. A biopolymer powder was mixed with water and commercial soil following the manufacturer's recommendations. The soil mixed with the biopolymer was filled in a pot or applied to the surface of the commercial soil with a thickness of 3 cm. Across the competition treatments, the biopolymer treatment promoted root growth of the target plant species and decreased the specific leaf area. The total biomass and shoot dry weight of P. alopecuroides increased in response to the biopolymer treatment. The competition treatment decreased the total biomass and shoot dry weight compared to the case without competition. Notably, such a competitive effect was similar in all the biopolymer treatments. Thus, biopolymers, when mixed with soil, promote the growth of some plant species, but do not appear to affect the competitive ability of plants.

• Journal of Environmental Impact Assessment
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• v.27 no.4
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• pp.367-377
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• 2018

A cultural ecosystem service(CES), which is non-material benefit that human gains from ecosystem, has been recently further recognized as gross national income increases. Previous researches proposed to quantify the value of CES, which still remains as a challenging issue today due to its social and cultural subjectivity. This study proposes new way of assessing CES which is called Cultural Service Opportunity Spectrum(CSOS). CSOS is accessibility based CES assessment methodology for regional scale and it is designed to be applicable for any regions in Korea for supporting decision making process. CSOS employed public spatial data which are road network and population density map. In addition, the results of 'Rapid Assessment of Natural Assets' implemented by National Institute of Ecology, Korea were used as a complementary data. CSOS was applied to Namyangju-si and the methodology resulted in revealing specific areas with great accessibility to 'Natural Assets' in the region. Based on the results, the advantages and limitations of the methodology were discussed with regard to weighting three main factors and in contrast to Scenic Quality model and Recreation model of InVEST which have been commonly used for assessing CES today due to its convenience today.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.330-339
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• 2010

In order to suggest correct direction of researches on Miscanthus spp. which are promising bioenergy crop, authors had reviewed and summarized various literature about botanical taxonomy, morphology and present condition of breeding, cultivation and utilization of miscanthus. Among the genus of Miscanthus which are known 17 species, the most important species are M. sinensis and M. sacchariflorus which origin are East Asia including Korea, and M. x giganteus which is inter-specific hybrid of tetraploid M. sacchariflorus and diploid M. sinensis. Miscanthus is superior to other energy crops in resistance to poor environments including cold, saline and damp soil, nitrogen utilization efficiency, budget of input energy and carbon which are required for producing biomass and output which are stored in biomass. The major species for production of energy and industrial products including construction material in Europe, USA and Canada is M. x giganteus which was introduced from Japan in 1930s. In present, many breeding programs are conducted to supplement demerits of present varieties and to develop "Miscanes" which is hybrid of miscanthus and sugar cane. In Korea, the researches on breeding and cultivation of miscanthus were initiated in 2007 by collecting germplasms, and developed "Goedae-Uksae 1" which is high biomass yield and "mass propagation method of miscanthus" which can improve propagation efficiency in 2009. In order to develop "Korean miscanthus industry" in future, the superior varieties available not only domestic but also foreign market should be developed by new breeding method including molecular markers. Researches on production process of cellulosic bio-ethanol including pre-treatment and saccharification of miscanthus biomass also should be strengthen.

• Journal of Chest Surgery
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• v.37 no.10
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• pp.833-838
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• 2004

Background: Despite the excellent early results after the repair of congenital bicuspid aortic valve (BAV) disease, the mid-term durability of the repaired valve has still controversies. Material and Method: To evaluate the mid-term results of BAV repair, retrospective review of medical records and echocardiographic data were done. Between 1994 and 2003, twenty-two patients underwent reparative procedure for either regurgitant or stenotic congenital bicuspid aortic valve (BAV). Result: Mean age was $41\pm14$ years with male predominance (Male=17, Female=5). The pathophysiologies of the BAV were regurgitation-dominant in 20 (91%) and stenosis-dominant in 2 (9%) cases. Various repair techniques were used for raphe, prolapsed leaflet, thickened leaflet, and commissures; 1) release of raphe in 19 (86%), 2) wedge resection and primary repair in 11 (50%), pericardial patch reinforcement after plication of the leaflet in 6 (27%), and plication of the leaflet in 3 (14%), 3) slicing of thickened leaflet was used in 12 (55%) cases, 4) commissuroplasty in 8 (36%), and commissurotomy in 6 (27%) cases. There was no in-hospital mortality. During the mean follow-up of $38\pm17$ months, one patient underwent aortic valve replacement after developing acute severe regurgitation from dehiscence of the suture on postoperative 2 months. New York Heart Association functional class was improved from $1.9\pm0.6$ to $1.2\pm0.5$ (p<0.01). Left ventricular end-systolic and diastolic dimension (LVESD/LVEDD) were also improved from $45\pm9$ and $67\pm10$ to $37\pm10$ and $56\pm10,$ respectively (p<0.01). The grade of aortic regurgitation (AR) was improved from preoperative $(3.1\pm1.2)$ to post-bypass $(0.9\pm0.7).$ However, the grade at last follow-up $(1.7\pm1.1)$ was deteriorated during the follow-up period (p<0.01). Freedom from grade III and more AR at one, three, and four year were 89.7%, 89.7%, and 39.9% respectively. Conclusion: Midterm clinical result of the BAV repair was favorable. But, the durability of the repaired valve was not satisfactory.

• Journal of Chest Surgery
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• v.41 no.4
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• pp.405-416
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• 2008

Background: Spinal cord ischemic injury during thoracic and thoracoabdominal aortic surgeries remains a potentially devastating outcome despite using various methods of protection. Neuronal voltage-dependent sodium channel antagonists are known to provide neuroprotection in cerebral ischemic models. This study was designed to compare the neuroprotective effects of phenytoin with those of hypothermia in a rabbit model of spinal cord ischemia. Material and Method: Spinal cord ischemia was induced in New Zealand white rabbits by means of infrarenal aortic cross clamping for 25 minutes. Four groups of 8 animals each were studied. The control group and the hypothermia group received retrograde infusion of saline only ($22^{\circ}C$, 2 mL/min); the normothermic phenytoin group and the hypothermicphenytoin group received retrograde infusion of 100 mg of phenytoin at different rectal temperatures ($39^{\circ}C$ and $37^{\circ}C$, respectively) during the ischemic period. The neurologic function was assessed at 24 and 72 hours after the operation with using the modified Tarlov criteria. The spinal cords were harvested after the final neurologic examination for histopathological examination to objectively quantify the amount of neuronal damage. Result: No major adverse effects were observed with the retrograde phenytoin infusion during the aortic ischemic period. All the control rabbits became severely paraplegic, Both the phenytoin group and the hypothermia group had a better neurological status than did the control group (p < 0.05). The typical morphological changes that are characteristic of neuronal necrosis in the gray matter of the control animals were demonstrated by means of the histopathological examination, whereas phenytoin or hypothermia prevented or attenuated these necrotic phenomena (p < 0.05). The number of motor neuron cells positive for TUNEL staining was significantly reduced, to a similar extent, in the rabbits treated with phenytoin or hypothermia. Phenytoin and hypothermia had some additive neuroprotective effect, but there was no statistical significance between the two on the neurological and histopathological analysis. Conclusion: The neurological and histopathological analysis consistently demonstrated that both phenytoin and hypothermia may afford significant spinal cord protection to a similar extent during spinal cord ischemia in rabbits, although no significant additive effects were noticed.

• The Korean Journal of Food And Nutrition
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• v.25 no.3
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• pp.564-569
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• 2012

Selenium was initially considered toxic to humans, but it was then discovered that selenium is essential for normal life processes. Selenium plays important roles in antioxidants. It is expected that chitosan microcapsules containing nano-selenium will be able to be used as a key material in bio-medical and cosmetic applications. The high concentration of chitosan derivatives guarantees increased antioxidative activity. Both inorganic and organic forms of selenium can be nutritional sources. The antioxidant properties of selenoproteins help prevent cellular damage from free radicals. The objective of this experiment was to study the antioxidative activity of chitosan nano-selenium. Our experiments were divided into five groups, in the presence of various concentrations(0.1%, 0.3%, 0.5%, 0.7%, and 0.9%) of chitosan. We performed an assessment of the antioxidant properties and cytotoxicity of respective concentrations of chitosan nano-selenium. The antioxidant activity was examined by the free radical scavenging activity on 1,1-diphenyl-2-picrylhydrazyl(DPPH) assay. The cytotoxicity effect was measured by means of 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay. As a result, the electron donating abilities of 0.1%, 0.3%, 0.5%, 0.7%, and 0.9% of chitosan nano-selenium exhibited effective andioxidant scavenging activity at 12.5 ${\mu}g/m{\ell}$ against DPPH radicals. 0.3% chitosan nano-selenium did not show cytotoxicity on human keratinocytes. In general, the cytotoxicity of 0.1% and 0.9% chitosan nano-selenium showed the lowest effects. Though low cytotoxicity of 0.5% and 0.7% chitosan nano-selenium exhibited 29.67% and 38.4% against human keratinocytes on adding 100 ${\mu}g/m{\ell}$ and 50 ${\mu}g/m{\ell}$, respectively, cell vitality was recovered with 200 ${\mu}g/m{\ell}$. These findings support the notion that chitosan nano-selenium may be useful as a new active ingredient source for bioactive compounds.