• Natural Product Sciences
• /
• v.14 no.3
• /
• pp.156-160
• /
• 2008

The methanolic extract of Rhus verniciflua Stokes (RVS-T) and its fractions (RVS-H, RVS-C, RVS-E and RVS-B) showed significant neuroprotective activity against glutamate-induced toxicity in primary cultures of rat cortical cells. RVS-B, which showed the most potent neuroprotective activity, was further fractionated to yield RVS-B5. Treatment of cortical cells with the RVS-T, RVS-B and RVS-B5 reduced the cellular ROS level and restored the reduced activities of glutathione reductase and SOD induced by glutamate. Although, the activity of glutathione peroxidase was not virtually changed by glutamate, RVS-B5 increased the glutathione peroxidase activity. In addition, these three tested fractions significantly restored the content of GSH which was decreased by glutamate insult in our cultures. Taken together, it could be postulated that RVS extract, in particular its fraction RVS-B5, protected neuronal cells against glutamate-induced neurotoxicity through acting on the antioxidative defense system.

• Journal of The Korean Association For Science Education
• /
• v.22 no.3
• /
• pp.617-631
• /
• 2002

This study has examined 5-year students in the kindergarten and students in the 2nd, 4th, and 6th grade in the primary school to analyze their perceptions about scientists. science, and how they apply science in their daily lives. First, students have 4 stereotypic images on scientists, specifically in 'indoor', 'male', 'lab coat'. and 'scientific instrument'. There were significant differences in stereotypic images on scientists depending on genders and ages. Girls and primary students showed higher scores than boys and kindergarten students did. respectively, in stereotypic images on scientists. No differences were observed for the stereotypic images on scientists among primary students, regardless of their grades. Second, most of students were interested in science. Depending on grades, there were significant differences in their preference for science. Students in higher grades showed lower scores than those in lower grades did. In addition, only a few of them hoped to be a scientist in the future. Boys showed higher scores in their hope to be a scientist in the future than girls did. The students in lower grades showed higher scores than those in higher grades. Third, most of children thought themselves doing activity-oriented science in school. Outside school, however, they did not use the knowledge and skills they had learned for science in school. Students in the primary school showed more concept-oriented perception for science than those in kindergarten did. This perception was gradually increased as the grades of the students go up.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.36 no.4
• /
• pp.625-630
• /
• 2009

Root resorption of primary teeth usually occurs as the succeeding permanent teeth erupt, which induces differentiation of the hemopoietic cells into osteoclasts. Their root resorption pattern reflects the eruption path of the succeeding permanent teeth, and eventually the primary teeth shed as their succeeding permanent teeth erupt. Even when a permanent tooth germ is congenitally missing, root resorption of the corresponding primary tooth may still occur due to various factors, such as inflammation, traumatic occlusal force, and weakness of periodontium etc. Such congenital missing of permanent teeth is a commonly observed phenomenon in human be ing, and it often accompanies delayed retention of primary teeth. The etiologic factors for congenital missing in elude not only systemic diseases, but also local factors and human evolution process. In the radiographs of the cases in this report, the primary teeth without succeeding permanent teeth show pathologic root resorption. Root resorption progressed about 1/2~3/4 of the roots, and the surfaces of the resorption area were irregular. Considering high susceptibility of the periodontal ligament of primary teeth to root resorption, pathologic root resorption of primary teeth with delayed retention can be explained by the increased masticatory muscle force and abnormal occlusion developed during the mixed dentition. When the primary teeth without succeeding permanent teeth are lost, decision for space maintenance is required and long-term treatment plan for further prosthetic or orthodontic treatment should be establsihed.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.38 no.3
• /
• pp.290-295
• /
• 2011

During tooth formation, tooth development can be affected by physical action or metabolic changes around dental follicle. Especially trauma to primary dentition is the most representative physical factor that can cause development disorders of succedaneous tooth. Enamel hypoplasia and crown discoloration of succedaneous tooth are common complications of trauma. And impaction, ectopic eruption, arrest of root formation and root dilaceration of succedaneous tooth are rare. In this case, a 6-year and 5-month-old female patient visited for dental evaluation after trauma. She was diagnosed with alveolar bone fracture near upper front teeth, extrusion of the upper right and left primary central incisors, intrusion of the upper right primary lateral incisor, and palatal luxation of the upper left primary lateral incisor. Upper right and left primary central incisors with severe mobility were extracted, with gingival suture on the day of the visit. During 24 months check up, root dilacerations were found near the cemento enamel junction in the upper lateral incisors and arrests of root formation were found on the coronal 1/3 of the root in the upper central incisors. Although alveolar bone fracture is rare type of trauma in children, a thorough examination of alveolar bone is essential for prognosis and following treatment in patients with trauma.

• Journal of Korean Elementary Science Education
• /
• v.35 no.3
• /
• pp.277-287
• /
• 2016

This study explores how a teacher copes with anomalous situation in primary practical science lesson and what factors affect teacher's strategy to cope with anomalous situations. The method of auto-ethnography was used in order to capture the inner experience of the individual teacher. For this, one of the researchers participated in this study as the teacher participant. Two science lessons that the researcher taught as a teacher were observed by a co-author and video-recorded. However, only one lesson which the teacher experienced the anomalous situation was analyzed. After the lesson, self-interviews were conducted with the co-author. Also the researcher wrote four reflective journals about anomalous situations that she experienced. What has emerged in this study is that anomalous situations were experienced by the teacher while students were doing practical work and while students were presenting their results of practical work. As each anomalous situation was experienced in different contexts, the strategies that the teacher used were different and were affected not only by the personal epistemological belief but also by the socio-cultural context that the teacher was surrounded by. This study has implications to help teachers who have difficulties in coping with anomalous situations.

• Korean Journal of Medicinal Crop Science
• /
• v.21 no.4
• /
• pp.276-281
• /
• 2013

This study was conducted to compare the contents of ginsenoside according the water extract conditions of red ginseng. In method A, red ginseng extract was prepared at $75^{\circ}C$ for 18 hours by 1 time extraction, and method B, the preparation was done at $85^{\circ}C$ for 18 hours by 1 time extraction. In method C, the primary extract prepared at $75^{\circ}C$ for 9 hours was blended with the secondary extract prepared by re-extracting the red ginseng residue obtained after the primary extraction, at $85^{\circ}C$ for 9 hours. Method D was the same procedure as method C but the extraction temperature for the primary extraction was $85^{\circ}C$ and that for the secondary extraction was $95^{\circ}C$. The contents of total and $Rb_1$, $Rg_1$ and $Rg_3$ ginsenoside were highest in Method C. The content of prosapogenin (ginsenoside $Rg_2$, $Rg_3$, $Rb_1$ and $Rb_2$) was highest in Method B. There was no consistent tendency in Brix, pH, Hue value and absorbance among extraction methods.

• Corrosion Science and Technology
• /
• v.20 no.6
• /
• pp.367-372
• /
• 2021

The effect of carbon addition on the general corrosion behavior of high-chromium cast iron (HCCI) was studied by a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) or electron back-scattered diffraction (EBSD), or electrochemical polarization techniques in 0.1 mol dm^-3 H₂SO₄ + 0.05 mol dm^-3 HCl at room temperature. The addition of 2.1-2.8 wt% carbon to HCCI increased the fraction of eutectic austenite and eutectic carbide phases, while that of HCCI decreased the fraction of the primary austenitic phase. Potentiostatic polarization of the HCCI at -0.35 V_SSCE or 0.0 V_SSCE resulted in preferential general corrosion of the primary austenitic or eutectic austenitic phases, respectively. The decrease in corrosion current density and the shift in noble corrosion potential direction with increasing carbon content in the HCCI indicated that the fraction and the chemical composition of austenitic (primary and eutectic) and carbide phases were strongly related to the general corrosion behavior of the HCCI.

• Korean Journal of Ecology and Environment
• /
• v.34 no.3 s.95
• /
• pp.166-174
• /
• 2001

The autochthonous and allochthonous organic carbon loading were measured in Lake Soyang, to estimate the amount of carbon loading into the lake and the contribution of their sources to tile lake's carbon loading. Autochthonous carbon loading was estimated from phytoplankton primary production with the extracellular organic carbon (EOC). Allochthonous loading was determined by measuring dissolved organic carbon (DOC) and particulate organic carbon (POC) concentration in the main inflowing Soyang River. Both autochthonous and allochthonous organic carbon loading were high during the svmmer, from July to September, and accounted for 43.2% and 71.7% of the annual loading, respectively. Primary productivity was elevated up to $1,000\;mgC\;m^{-2}\;d^{-1}$ during summer and lowest in winter. EOC production from phytoplankton was also large in summer, resulting in a high DOC concentration in the lake water. Primary production of phytoplankton and allochthonous organic matter loading from the watershed contributed to 53.6% and 46.4% of total loading, respectively. The EOC production accounted far $4.4{\sim}21.2%$ of POC primary production, implying that EOC production of phytolankton must be considered in estimation of primary production.

• Journal of Embryo Transfer
• /
• v.28 no.4
• /
• pp.373-379
• /
• 2013

Spermatogonial stem cells (SSCs) developed into sperms through spermatogenesis have been utilized as a useful tool in the field of regenerative medicine and infertility. However, a small number of highly qualified SSCs are resided in the seminiferous tubule of testis, resulted in developing effective in-vitro culture system of SSCs for solving simultaneously quantitative and qualitative problems. Presently, SSCs can be enriched on testicular stromal cells (TSCs), but there are no systematic researches about TSC culture. Therefore, we tried to optimize culture condition of TSCs derived from mouse with different strains. For these, proliferation and viability were measured and compared by culturing ICR outbred or DBA/2 inbred mouse-derived TSCs at 35 or $37^{\circ}C$. In case of ICR strain, primary TSCs cultured at $37^{\circ}C$ showed significantly higher proliferation and viability than those at $35^{\circ}C$ and significant increase of proliferation and viability in sub-passaged TSCs was detected in the $35^{\circ}C$ culture condition. Moreover, sub-passage of primary TSCs at $35^{\circ}C$ induced no significant effects on proliferation and viability. In contrast, in case of DBA/2 strain, significantly improved proliferation were detected in the primary TSCs cultured at $35^{\circ}C$, which showed no significant difference in the viability, compared to those at $37^{\circ}C$. Furthermore, sub-passaged TSCs cultured at $37^{\circ}C$ showed no significant differences in proliferation and viability, compared to those at $35^{\circ}C$. However, with significant decrease of proliferation induced by sub-passage of primary TSCs at $35^{\circ}C$, no significant effects on proliferation and viability were resulted from sub-passage of primary TSCs at $37^{\circ}C$. From these results, culture temperature of primary TSCs derived from outbred and inbred strain of mouse could be separately optimized in primary culture and subculture.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.6
• /
• pp.1698-1702
• /
• 2013

Glucose is a common medical analyte measuring in human serum or blood samples. The development of a primary method is necessary for the establishment of traceability in measurements. We have developed an isotope dilution liquid chromatography tandem mass spectrometry as a primary method for the measurement of glucose in human serum. Glucose and glucose-$^{13}C_6$ in sample were ionized in ESI negative mode and monitored at mass transfers of m/z 179/89 and 185/92 in MRM, respectively. Glucose was separated on $NH_2P$-50 2D column, and the mobile phase was 20 mM $NH_4OAc$ in 30% acetonitrile/70% water. Verification of this method was performed by the comparison with NIST SRMs. Our results agreed well with the SRM values. We have developed two levels of glucose serum certified reference material using this method and distributed them to the clinical laboratories in Korea as samples for proficiency testings. The expended uncertainty was about 1.2% on 95% confidence level. In proficiency testings, the results obtained from the clinical laboratories showed about 3.6% and 3.9% RSD to the certified values. Primary method can provide the traceability to the field laboratories through proficiency testings or certified reference materials.