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        검색결과 7

        1.
        2022.05 구독 인증기관·개인회원 무료
        Measurement of the physical properties of high-temperature molten salts is important for the efficient design and operation of molten salt reactors (MSR) in which the reactor coolant and nuclear fuel are in a homogeneous liquid state. Although some crucial physical properties such as viscosity, thermal conductivity, density, etc., have been drawing much attention, relative data, especially for molten chloride salts, are scarce. Thus, it is urgent to prepare the viscosity data as one of the key transport properties in thermal hydraulics analysis. However, it is not an easy task to measure the molten salt viscosity with high accuracy due to end effect, a small gap between the chamber and spindle, thermal expansion of the chamber and spindle at high temperatures in a rotational viscometer. Additionally, molten salt temperatures inside furnace are not uniform due to the large temperature gradient inside the chamber, and therefore the assumption of laminar condition can be violated. In this study, geometric factors, which can be a major interference in the torque measurement, were considered for the accurate determination of the viscosity. We established a high-temperature molten salt viscosity measurement system with Brookfield rotational viscometer. KNO3 molten salt was used as a model substance at a temperature range of 650–773 K. In-house designed spindles and chambers were made of corrosion-resistant alumina. Thermal expansion has a significant influence on the size and shape of the chamber and spindle. The effect of thermal expansion on the conventional correction method was examined with temperature variation and distribution. Gap size variation was also investigated in order to improve the accuracy.
        3.
        2013.10 구독 인증기관·개인회원 무료
        Previously, we have performed de novo RNA sequencing of Scolpendra subpinipes mutilans using next generation sequencing technology and identified several AMP candidates. Among them, a synthetic peptide (scolopendrasin I) was designed based on SVM algorithm. In this study, we reported that the synthetic peptide scolopendrasin I had an antimicrobial and anticancer activity. As a result, scolopendrasin I showed antibacterial activities against Gram positive and Gram negative bacteria strains in radial diffusion assay and colony count assay without hemolytic activity. In addition, we confirmed that scolopendrasin I bound to the surface of bacteria via a specific interaction with lipoteichoic acid and lipopolysaccharide, which is one of bacteria cell membrane components. In addition, we found that scolopendrasin I had anticancer activities in the human leukemic T lymphocyte cell line Jurkat using MTS assay. In conclusion, our results suggested that scolopendrasin I could be useful for developing peptide antibiotics and anticancer agents.
        4.
        2006.12 구독 인증기관 무료, 개인회원 유료
        The effects of adenosine triphosphate(ATP) on salivary glands have been recognized since 1982. The presence of purinergic recepetors(P2Rs) that mediate the effects of ATP in various tissues, including parotid and submandibular salivary gland, has been supported by the cloning of receptor cDNAs and the expression of the receptor proteins. P2Rs have many subtypes, and the activation of these receptor subtypes increase intracellular Cα²+, a key ion in the regulation of the secretion in the salivary gland. The apical pores of taste buds in circumvallate and foliate papillae are surrounded by the saliva from von Ebner salivary gland(vEG). Thus, it is important how the secretion of vEG is controlled. This study was designed to elucidate the roles of P2Rs on salivary secretion of vEG. Male Sprague-Dawley rats (about 200 g) were used for this experiment. vEG-rich tissues were obtained from dissecting 500-1,000μm thick posterior tongue slices under stereomicroscope view. P2Rs mRNA in vEG acinar cells were identified with RT-PCR. To observe the change in intracellular Cα²+ activity, we employed Cα²+-ion specific fluorescence analysis with fura-2. Single acinar cells and cell clusters were isolated by a sequential trypsin/collagenase treatment and were loaded with 10 μM fura -2 AM for 60 minutes at room temperature. Several agonists and antagonists were used to test a receptor specificity. RT-PCR revealed that the mRNAs of P2X₄, P2Y₁, P2Y₂ and P2Y₃ are expressed in vEG acinar cells. The intracellular calcium activity was increased in response to 10 μM ATP, a P2Rs agonist, and 2-MeSATP, a P2Y₄ and P2Y₂R agonist. However, 300 μM αβ-MeATP, a P2X₁ and P2X₃R agonist, did not elicit the response. The responses elicited by 10 μM ATP and UTP, a P2Y₂R agonists, were maintained when extracellular calcium was removed. 10 μM suramin, a P2XR antagonist, and reactive blue 2, a P2YR antagonist, partially blocked ATP-induced response. However, when extracellular calciums were removed, suramin did not abolish the responses elicited by ATP. These results suggest that P2Rs play an important role in salivary secretion of vEG acinar cells and the effects of ATP on vEG salivary secretion may be mediated by P2X₄, P2Y₁, P2Y₂, and/or P2Y₃.
        4,000원
        5.
        2006.09 구독 인증기관 무료, 개인회원 유료
        Von Ebner's glands (vEG) are minor salivary glands associated with circumvallate and foliate papilla. The secretions of vEG consist of microenvironment of the taste buds in the circumvallate and foliate papillae, and thus saliva from vEG plays a role in the perception of taste. The Ca²+ signaling system in rat vEG acinar cell was examined using the Ca²+-sensitive fluorescent indicator Fura-2. Agonist-induced increase in intracellular Ca²+([Ca²+]i) was stimulated by carbachol (CCh) and substance P (SP), but not by norepinephrine (NE), and recovered to control levels by their receptor antagonists dose-dependently. The effects were also observed in Ca²+-free medium, suggesting mobilization from intracellular Ca²+ store. These results in the vEG acinar cell indicate that 1) [Ca²+]i is at least regulated by muscarinic and neurokininergic (NK1) receptors; 2) the increases in [Ca²+]i activated by CCh and SP are mainly mediated by discharge of cytosolic calcium pool.
        4,000원
        7.
        2017.09 KCI 등재 서비스 종료(열람 제한)
        Robots are used in early childhood education as a new instructional media, and educational activities using robots have been increased. So the purpose of this study is to investigate the effect of educational activities using hands-on robots on logic-mathematical knowledge and creative problemsolving ability of young children. The total number of subjects was 43, and they were all five-year-old children. The experimental group and control group did activities with hands-on robots and general free activities, respectively. Results using ANCONA have shown that the activities with hands-on robots positively affected logic-mathematical knowledge and creative problem-solving ability of young children. These meaningful results have shown the possibility of early childhood educational use as the effectiveness of hands-on robots has come out.