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        검색결과 75

        1.
        2023.10 구독 인증기관·개인회원 무료
        매년 국내로 비래해 오는 해충인 벼멸구는 그 기원이 중국 또는 중국 남부일 것으로 예상해왔으나, 이에 대한 유전학적 근거는 Mun et al. (1999)에 의해 제시된 세 가지 COI haplotype 비교가 유일하다. Mun et al. (1999)은 국내에 서 확인된 두 가지 haplotype 유형이 인도차이나반도 이남의 균일한 한 가지 haplotype 집단 유형과 중국에서 확인 된 또 다른 haplotype 집단 유형임을 근거로 국내 벼멸구의 기원을 중국으로 특정한 바 있다. 본 연구는 국내 및 동남아시아 5개국(부탄, 미얀마, 캄보디아, 라오스 및 태국)으로부터 직간접적으로 확보한 개체들을 대상으로 GBS (genotyping by sequencing) 및 NGS 기법을 통해 PCA를 포함한 다양한 집단유전학적 분석을 수행하였다. 그 결과 인도차이나반도의 벼멸구 집단은 크게 북부와 남부로 나뉘며, 국내 개체들은 북부에 비해 남부(캄보디 아, 태국)에 더 가깝다는 사실을 확인하였다. 따라서 벼멸구의 국내 비래는 중국으로부터의 기원 이전에 장마전 선이 형성될 무렵부터 인도차이나반도 남쪽의 고온다습한 서풍이 남남서풍으로 바뀌면서 중국 내륙을 거쳐 국내로 비래하는 경로를 따르는 것으로 보인다. 하지만 태안의 개체 중에는 인도차이나반도 집단들의 외군으로 확인되는 개체가 있었고, 이는 인도차이나반도 외의 샘플링되지 않은 다른 지역에서도 벼멸구가 국내로 비래할 수 있다는 가능성을 제시하였다. 따라서 국내로 유입되는 벼멸구의 유전적 기원을 확인하기 위해서는 인도차이 나반도 남쪽 지역에서 시작한 동아시아 여름 몬순의 바람이 한국으로 도착하는 경로에 위치한 다른 지역에서의 추가적인 샘플링 및 지속적인 관심과 추적이 필요할 것이다.
        3.
        2020.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We report the discovery of a giant exoplanet in the microlensing event OGLE-2017-BLG-1049, with a planet―host star mass ratio of q = 9.53 ± 0.39 × 10-3 and a caustic crossing feature in Korea Microlensing Telescope Network (KMTNet) observations. The caustic crossing feature yields an angular Einstein radius of θE = 0.52 ± 0.11 mas. However, the microlens parallax is not measured because the time scale of the event, tE ≃ 29 days, is too short. Thus, we perform a Bayesian analysis to estimate physical quantities of the lens system. We fi nd that the lens system has a star with mass Mh = 0.55+0.36 -0.29 M⊙ hosting a giant planet with Mp = 5.53+3.62 -2.87 MJup, at a distance of DL = 5.67+1.11 -1.52 kpc. The projected star{planet separation is aㅗ = 3.92+1.10 -1.32 au. This means that the planet is located beyond the snow line of the host. The relative lens{source proper motion is μrel ~ 7 mas yr-1, thus the lens and source will be separated from each other within 10 years. After this, it will be possible to measure the flux of the host star with 30 meter class telescopes and to determine its mass.
        4,000원
        5.
        2018.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present the analysis of KMT-2016-BLG-0212, a low flux-variation (Iflux−var ∼ 20 mag) microlensing event, which is in a high-cadence (Γ = 4hr −1) field of the three-telescope Korea Microlensing Telescope Network (KMTNet) survey. The event shows a short anomaly that is incompletely covered due to the brief visibility intervals that characterize the early microlensing season when the anomaly occurred. We show that the data are consistent with two classes of solutions, characterized respectively by low-mass brown-dwarf (q = 0.037) and sub-Neptune (q < 10−4) companions. Future high-resolution imaging should easily distinguish between these solutions.
        4,000원
        11.
        2016.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We report the characterization of a massive (mp = 3:91:4Mjup) microlensing planet (OGLE- 2015-BLG-0954Lb) orbiting an M dwarf host (M = 0:33  0:12M ) at a distance toward the Galactic bulge of 0:6+0:4 􀀀0:2 kpc, which is extremely nearby by microlensing standards. The planet-host projected separation is a?  1:2AU. The characterization was made possible by the wide- eld (4 deg2) high cadence (􀀀 = 6 hr􀀀1) monitoring of the Korea Microlensing Telescope Network (KMTNet), which had two of its three telescopes in commissioning operations at the time of the planetary anomaly. The source crossing time t = 16 min is among the shortest ever published. The high-cadence, wide- eld observations that are the hallmark of KMTNet are the only way to routinely capture such short crossings. High-cadence resolution of short caustic crossings will preferentially lead to mass and distance measurements for the lens. This is because the short crossing time typically implies a nearby lens, which enables the measurement of additional e ects (bright lens and/or microlens parallax). When combined with the measured crossing time, these e ects can yield planet/host masses and distance.
        4,000원
        14.
        2011.10 구독 인증기관·개인회원 무료
        Cell transplantation therapy using adult stem cells has recently been identified as a potential treatment for spinal cord injury (SCI). But, recovery after traumatic SCI is very limited. As dogs are physiologically much more similar to human compared with other traditional mammalian models in disease presentation and clinical responses, a number of researches demonstrated canis familiaris is a suitable model for human diseases. This study investigated the effect of transplantation of canine Mesenchymal Stem Cells (cMSC) and neural-induced cMSC (nMSC) to understand how these cells improve neurological function in canine SCI model. The differentiation of cMSC into neural precursor cells was induced in dulbecco’s modified eagle’s medium supplemented with N2-supplement, dibutyryl cyclic adenosine monophosphate, and butylated hydroxyanisole. SCI was induced between T1 and T2 by surgical hemi-section in adult dogs, and then assigned to two groups according to the applied cell types (cMSC vs nMSC). Pelleted cMSC or nMSC were transplanted directly into the injured site after SCI, respectively. Analysis of motor function after transplantation was evaluated by modified Olby score. Magnetic resonance imaging (MRI), histological and immunohistichemical analysis were also performed. Functional recovery in group of cMSC was increasing gradually after transplantation and was higher than nMSC. In MRI, we could not confirm any difference between the cMSC and nMSC experimental groups. Immunohistochemically, beta3-tubuline and nestin were observed in injury site of two experimental groups with the expression level close to non-injured groups. Transplantation of mesenchymal stem cells could promote neuronal reconstruction and repair motor function in SCI. These showed mesenchymal stem cells could be a great candidate as a therapeutic tools in degeneration disease, and dogs could be used to explore human regenerative medicine as a promising animal model. This research was supported by iPET (Grants 110056032CG000), Ministry for Food, Agriculture, Forestry and Fisheries, Republic of Korea.
        15.
        2011.10 구독 인증기관·개인회원 무료
        Acteoside (verbascoside) is a typical phenylethanoid glycoside, extracted from various plants. It has various biological functions such as anti-oxidant, anti-inflammation, and anti-hypertension. Specially, it was powerful anti-oxidants either by direct scavenging of reactive oxygen and nitrogen species, or by acting as chain-breaking peroxyl radical scavengers. We examined the role of acteoside in IVM medium on the morphological progress of meiosis, developmental competence, and ROS in porcine oocytes. And we investigated effect of acteoside on the oocytes condition represented by cytoplasmic maturation by homogeneous distribution and formation of cytoplasmic organelles and regulation of apoptosis-related genes. The selected COCs were cultured in TCM-199 with various concentration of acteoside: 0 (control), 10, 30, and 50 μM. After 22 h of maturation with hormones, the oocytes were washed twice in a fresh maturation medium before being cultured in hormone-free medium for additional 22 h. The oocytes maturation rates of supplemented with acteoside were no significantly different compared with control group (71.13, 75.96, 72.95 and 73.68%, respectively). Level of ROS was significantly decreased in acteoside treated group. Furthermore, the parthenogenetic blastocyst rate was significantly improved in 10 μM acteoside treated group compared with control group (40.03 vs. 22.95%). During IVM, 10 μM acteoside treated oocytes showed that the mitochondria and lipid droplet were smaller and homogeneous distribution in cytoplasm compare with non-treated control oocytes. And reverse transcription polymerase chain reaction (RT-PCR) witarthenogenetic blstocysts revealed that acteoside increased the anti-apoptoticgenes, otherwise reibued pro-apoptotic genes. In conclusion, our results represents that addition of acteoside to the IVM medium has a beneficial effect in physiology of porcine oocytes such as viability and activation, providing a improved method for porcine oocytes in vitro.
        16.
        2011.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        nanopowders with anatase structure were firstly prepared by controlling the pH value of a precursor solution without any heat-treatment at room temperature. The prepared nanopowders were hydrothermally treated in 10M NaOH solution at . Then, the samples were washed in DI water or 0.1M HCl. The nanotubes were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The gas sensitivity of nanotubes for toluene gas was also investigated. The results show that nanotubes can be prepared by hydrothermal treatment. The morphology of nanotubes prepared by 0.1M HCl washing is destroyed to some extent. nanotubes with DI water washing show better sensitivity than that with 0.1M HCl washing.
        3,000원
        20.
        2006.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Co-Fe-Ni-B-Si-Cr based amorphous strips containing nitrogen were manufactured via melt spinning, and then devitrified by crystallization treatment at the various annealing temperatures of for up to 30 minutes in an inert gas atmosphere. The microstructures were examined by using XRD and TEM and the magnetic properties were measured by using VSM and B-H meter. Among the alloys, the amorphous ribbons of containing 121 ppm of nitrogen showed relatively high saturation magnetization. The alloy ribbons crystallized at showed that the grain size of alloy containing 121 ppm of nitrogen was about f nm, which exhibited paramagnetic behavior. The formation of nano-grain structure was attributed to the finely dispersed Fe4N particles and the solid-solutionized nitrogen atoms in the matrix. Accordingly, it can be concluded that the nano-grain structure of 5nm in size could reduce the core loss within the normally applied magnetic field of 300A/m at 10kHz.
        4,000원
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