• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.643-653
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• 2003

Fibroblast growth factor (FGF) / FGF receptor (FGFR) mediated signaling is required for skeletogenesis in cluding intramembranous and endochondral ossifications Runx2 ($Cbfa1/Pebp2{\alpha}A/AML3$) is an essential transcription factor for osteoblast differentiation and bone formation. Murine calvaria and mandible are concurrently undergoing both intramembranous bone and cartilage formations in the early developmental stage. However the mechanism by which these cartilage formations are regulated remains unclear. To elucidate the effect of FGF signaling on development of cranial sutural cartilage and Meckel's cartilage and to understand the role of Runx2 in these process, we have done both in vivo and in vitro experiments. Alcian blue staining showed that cartilage formation in sagittal suture begins from embryonic stage 16 (E16), Meckel's cartilage formation in mandible from E12. We analyzed by in situ hybridization the characteristics of cartilage cells that type II collagen, not type X collagen, was expressed in sagittal sutural cartilage and Meckel's cartilage. In addition, Runx2 was not expressed in Meckel's cartilage as well as sagittal sutural cartilage, except specific expression pattern only surrounding both cartilages. FGF signaling pathway was further examined in vitro. Beads soaked in FGF2 placed on the sagittal suture and mandible inhibited both sutural and Meckel's cartilage formations. We next examined whether Runx2 gene lies in FGF siganling pathway during regulation of cartilage formation. Beads soaked in FGF2 on sagittal suture induced Runx2 gene expression. These results suggest that FGF signaling inhibits formations of sagittal sutural and Meckel's cartilages, also propose that FGF siganling is involved in the proliferation and differentiation of chondroblasts through regulating the transcription factor Runx2.

• Korean Journal of Medicinal Crop Science
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• v.2 no.1
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• pp.60-66
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• 1994

This study was conducted to determine the optimum conditions of inducing callus, proliferating callus, forming somatic embryos, and regenerating plantlets via somatic embryogenesis, for the purpose of producing artificial seeds and substantially developing plant factory technologies that can be employed to all seasons production of Bupleurum plants. Callus was efficiently induced from leaf tissues at three leaf stage in the MS medium supplemented with 2, 4-D 2mg /1 and thidiazuron(TDZ) 0.lmg /1. Callus induction from leaf tissues at maturity was mostly effective in the mixture of 2,4- D 2mg /1 and TDZ 1.0mg /1 while that from flower bud tissues was fairly good in the MS medium containing 2,4-D 1 or 2mg /1.Callus was formed in 15 to 20 days after culture initiation in the MS media supplemented with 2, 4- D 1-2mg /1 and TDZ 0.l-1.0mg /1. Such hormones as kinetin 3mg /1, GA 1mg /1, and the mixture of GA 1mg /1 and TDZ 1mg /1 effected markedly to proliferate the callus cells.The optimum temperature and light intensity for callus culture were found to be $25^{\circ}C$ and 3000 Lux, respectively. Direct plant regeneration from cultured callus was fairly made on hormone-free MS or half-strength MS medium. Somatic embryogenesis was most frequently observed in hormone-free media:60 somatic embryos per 20ml in MS medium and 28 somatic embryos per 20ml in half -strength MS medium. There were three stages-globular, heart, and torpedo-in development of somatic embryos, among which globular stage was more frequently observed in MS medium rather than in half-strength MS medium. Somatic embryos induced from suspension culture fairly differentiated a number of shoots and roots on hormone-free and half-strength MS solid medium.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.1
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• pp.8-15
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• 2021

TiO2 has been used in various fields such as solar cells, dental implants, and photocatalysis, because it has high physical and chemical stability and is harmless to the body. TiO2 nanofibers which have a large specific surface area also show a good reactivity in bio-friendly products and excellent photocatalysis in air and water purification. To fabricate TiO2 nanofibers, an electrospinning method was used. To observe the diameter of TiO2 nanofibers with fabrication variables, the fabrication variables was divided into precursor composition variables and process variables and microstructure was analyzed. The concentrations of PVP (Polyvinylpyrrolidone) and TTIP (Titanium(IV) isopropoxide) were selected as precursor composition variables, and inflow velocity and voltage were also selected as process variables. Microstructure and crystal structure of TiO2 nanofibers were analyzed using FE-SEM (Field emission scanning electron microscope) and XRD (X-ray diffraction), respectively. As-spun TiO2 nanofibers with an average diameter of about 0.27 ㎛ to 1.31 ㎛ were transformed to anatase TiO2 nanofibers with an average diameter of about 0.22 ㎛ to 0.78 ㎛ after heat treatment of 3 hours at 450℃. Anatase TiO2 nanofibers with an average diameter of 0.22 ㎛ can be expected to improve the photocatalytic properties by increasing the specific surface area. To change the average diameter of TiO2 nanofibers, the control of precursor composition variables such as concentrations of PVP and TTIP is more efficient than the control of electrospinning process variables such as inflow velocity and voltage.

• Journal of Radiation Protection and Research
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• v.35 no.2
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• pp.49-56
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• 2010

Developments of radioprotective agents are important issues for minimizing the troubles and the effective treatments in radiotherapy. But few agents are useful in clinical and practical fields. It was shown that trace elements in alcohol beverages might have radioprotective effect. In this study, the types of cell death of lymphocytes according to the commercial alcohol beverage was investigated. Normal healthy volunteers ingested distilled water, beer or soju containing $81.5mg{\cdot}dl^{-1}$ ethyl ahcohol, respectively. After 2 hours, their blood were sampled with their consents. Fraction of lymphocytes was isolated by density gradient method with Histopaque-1077 (Sigma) and irradiated with dose from 0.5 to 5 Gy. After 60 hour incubation, the cells were harvested and analysed by flow cytometry. Cell viability was decreased by dose dependent manner. Cell viability of beer group was reduced about 15% compared with control group. Apoptosis in soju group was reduced about 20% compared with control group. Apoptosis of beer and control groups are similar. Necrosis of soju group significantly increased about 35% compared with control group. Early apoptosis of beer group was increased compared with control group. Early apoptosis of soju group was decreased about 25% compared with control group. Late apoptosis of beer and control group was increased by dose dependent manner. Late apoptosis of soju group was increased about 20-30% compared with control group. Late apoptosis of soju was increased and the radioprotective effect of soju was minimal because late apoptosis induced the cell necrosis. In case of soju trace elements, total cell apoptosis was decreased about 20% and early cell apoptosis was remarkably low. In this case, mitotic cells death may be dominant mechanism. Therefore, trace elements in soju may not be effective radioprotective agents.

• Journal of the Korean Electrochemical Society
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• v.23 no.2
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• pp.25-38
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• 2020

Photoelectrochemical water splitting has been considered as the most promising technology for generating hydrogen energy. Transition metal dichalcogenide (TMD) compounds have currently attracted tremendous attention due to their outstanding ability towards the catalytic water-splitting hydrogen evolution reaction (HER). Herein, we report the synthesis method of various transition metal dichalcogenide including MoS₂, MoSe₂, WS₂, and WSe₂ nanosheets as excellent catalysts for solar-driven photoelectrochemical (PEC) hydrogen evolution. Photocathodes were fabricated by growing the nanosheets directly onto Si nanowire (NW) arrays, with a thickness of 20 nm. The metal ion layers were formed by soaking the metal chloride ethanol solution and subsequent sulfurization or selenization produced the transition metal chalcogenide. They all exhibit excellent PEC performance in 0.5 M H₂SO₄; the photocurrent reaches to 20 mA cm^-2 (at 0 V vs. RHE) and the onset potential is 0.2 V under AM1.5 condition. The quantum efficiency of hydrogen generation is avg. 90%. The stability of MoS₂ and MoSe₂ is 90% for 3h, which is higher than that (80%) of WS₂ and WSe₂. Detailed structure analysis using X-ray photoelectron spectroscopy for before/after HER reveals that the Si-WS₂ and Si-WSe₂ experience more oxidation of Si NWs than Si-MoS₂ and Si-MoSe₂. This can be explained by the less protection of Si NW surface by their flake shape morphology. The high catalytic activity of TMDs should be the main cause of this enhanced PEC performance, promising efficient water-splitting Si-based PEC cells.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.388-388
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• 2016

Chemical mist deposition (CMD) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was investigated with cavitation frequency f, solvent, flow rate of nitrogen, substrate temperature $T_s$, and substrate dc bias $V_s$ as variables for efficient PEDOT:PSS/crystalline (c-)Si heterojunction solar cells (Fig. 1). The high-speed camera and differential mobility analysis characterizations revealed that average size and flux of PEDOT:PSS mist depend on f, solvent, and $V_s$. The size distribution of mist particles including EG/DI water cosolvent is also shown at three different $V_s$ of 0, 1.5, and 5 kV for a f of 3 MHz (Fig. 2). The size distribution of EG/DI water mist without PEDOT:PSS is also shown at the bottom. A peak maximum shifted from 300-350 to 20-30 nm with a narrow band width of ~150 nm for PEDOT:PSS solution, whose maximum number density increased significantly up to 8000/cc with increasing $V_s$. On the other hand, for EG/water cosolvent mist alone, the peak maximum was observed at a 72.3 nm with a number density of ~700/cc and a band width of ~160 nm and it decreased markedly with increasing $V_s$. These findings were not observed for PEDOT:PSS/EG/DI water mist. In addition, the Mie scattering image of PEDOT:PSS mist under white bias light was not observed at $V_s$ above 5 kV, because the average size of mist became smaller. These results imply that most of solvent is solvated in PEDOT:PSS molecule and/or solvent is vaporized. Thus, higher f and $V_s$ generate preferentially fine mist particle with a narrower band width. Film deposition occurred when $V_s$ was impressed on positive to a c-Si substrate at a Ts of $30-40^{\circ}C$, whereas no deposition of films occurred on negative, implying that negatively charged mist mainly provide the film deposition. The uniform deposition of PEDOT:PSS films occurred on textured c-Si(100) substrate by adjusting $T_s$ and $V_s$. The adhesion of CMD PEDOT:PSS to c-Si enhanced by $V_s$ conspicuously compared to that of spin-coated film. The CMD PEDOT:PSS/c-Si solar cell devices on textured c-Si(100) exhibited a ${\eta}$ of 11.0% with the better uniformity of the solar cell parameters. Furthermore, ${\eta}$ increased to 12.5% with a $J_{sc}$ of $35.6mA/cm^2$, a $V_{oc}$ of 0.53 V, and a FF of 0.67 with an antireflection (AR) coating layer of 20-nm-thick CMD molybdenum oxide $MoO_x$ (n= 2.1) using negatively charged mist of 0.1 wt% 12 Molybdo (VI) phosphoric acid n-Hydrate) $H_3(PMo_{12}O_40){\cdot}nH_2O$ in methanol. CMD. These findings suggest that the CMD with negatively charged mist has a great potential for the uniform deposition of organic and inorganic on textured c-Si substrate by adjusting $T_s$ and $V_s$.

• Korean Journal of Animal Reproduction
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• v.26 no.3
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• pp.253-261
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• 2002

This study was carried out to investigate the semen characteristic, motility and viability and sperm motion characteristic by CASA test for establishing the Jindo-dog's semen freezing system. The results obtained are as follow: 1. The semen was collected 63 times. Average volume of semen, concentration of sperm, total number of sperm, progressive motility and viability were 3.8 $m\ell$ 145.6$\times$10$^{6}$ cells/$m\ell$, 396.2 x10$^{8}$ cells, 79.7% and 89.5%, respectively. Also, Fawn (Yellow) Jindo-dog comparing with White Jindo-dog showed better concentration of sperm, total number of sperm, progressive motility and viability. Among all dogs, the results of No. 2 Fawn Jindo-dog were the best. 2. The average progressive motility and viability of semen from 46 times were 73.5%, 82.3% before freezing and 51.1%, 64.9% after freezing. So, the freezing of semen has affected the progressive motility and viability. The progressive motility and viability of Fawn Jindo-dog's semen, before and after freezing, were better than White Jindo-dog. And No. 2 Fawn Jindo-dog showed the best results and showed significantly different among all dogs (P<0.05). 3. The 44 times-tested .esults by CASA system were as follow; MOT (motility) 65.6%. PROG (progressive motility) 54.8%, VAP (average path velocity) 75.3 ${\mu}{\textrm}{m}$/sec, VCL (curve linear velocity) 90.0 ${\mu}{\textrm}{m}$/sec, VSL (straight-line velocity) 69.4 ${\mu}{\textrm}{m}$/sec and ALH (amplitude of lateral head displacement) 4.4 ${\mu}{\textrm}{m}$. Although the motion characteristic of frozen semen were not significantly different between White and Fawn Jindo-dog, No. 2 Fawn Jindo-dog showed the best results and was significantly different among all dogs (P<0.05). 4. The success rate of frozen semen production between White and Fawn Jindo-dog were 43% (13/28), 94% (33/35), respectively, and the total success rate was 73% (46/63). The freezing-ability of Fawn Jindo-dog's semen was better than the other. Conclusively, the present results indicated that the characteristic and motility of Jindo-dog') semen were suitable for processing frozen semen, artificial insemination and mass production system. Also, the selection of suitable dog-breed was so important because the characteristic and freezing-ability of semen were significantly different between White and Fawn Jindo-dogs and among all individual dogs.

• Tuberculosis and Respiratory Diseases
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• v.52 no.3
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• pp.241-250
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• 2002

Background : Coal-worker's pneumoconiosis(CWP) is characterized by a chronic inflammatory lung reaction associated with macrophage accumulation in the alveolar spaces. CWP is usually divided into two stage : simple pneumoconiosis(SP) where there are a limited number of fibrotic lesions remain limited, with radiological opacities smaller than 1cm and progressive massive fibrosis(PMF), which is characterized by the development of a perifocal extensive fibrotic response of the lung and severe alterations in pulmonary function. In this study, the lymphocyte compartment and cytokine were evaluated by measuring the serum levels in the control, SP and PMF groups. Materials and Methods : The coal workers selected for this study were employees(patients?) of the Tae-Baek and Dong-Hae hospital. All were men, 45-76 years old and the mean duration of their exposure to coal dust was 23.2 years in the lymphocyte compartment and 24.3 years in the cytokine checked group. According to X-ray examination results, the patients were classified into either one of the SP, PMF categories. The normal controls examined were 26-70 years old men. The serum cytokine levels were estimated by using an end point enzyme immunoassay technique. Results : T lymphocyte, helper and suppressor T cells were highly related to pneumoconiosis in this study. A statistically significant decrease in the number of suppressor T lymphocytes was observed in the simple pneumoconiosis patients and at the same time, there was an increase in the lymphocyte index. Howevere, there was no statistically difference in the serum cytokines levels among the SP, PMF and control groups. Conclusion : T lymphocyte, helper T, and suppressor T cells may be highly related to the development of CWP compared to the control group particularly in the early stage of pneumoconiosis. The changes observed in the immunological system in patients with pneumoconiosis may lie at the bottom of the pathogenesis of fibrosis. Further study is needed to evaluate the lymphocyte compartment as a marker for pneumoconiosis development in the early stage.

• Journal of Korean Society of Forest Science
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• v.84 no.2
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• pp.151-165
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• 1995

This study was conducted to establish a systematized taxonomic problems of through the leaf morphological characters and leaf venation patterns, and stomatal cell patterns and cell characteristics of abaxial and adaxial surface of the leaflets by SEM, of 6 native species in Korea and 2 foreign species of the Genus Rhus in the Family Anacardiaceae. The results obtained from this study are summarized as followings: 1. Morphological study measured 32 characters of leaves from herbarium specimen and field-collected samples for each species. The results of cluster analysis based on the Euclidean distance showed that the species could be classified into 3 groups: R. sylvestris. R. typhina, R. succedanea: R. trichocarpa. R. chinensis. R. verniciflua: and R. ambigua. R. radicans subsp. orientale, Analysis of principal components showed 5 groups: The major factors in the first principal component group was length of petiole of the terminal leaflets, that in the second group angle of left side in the terminal leaflet bash, that in the third group area ratio between first and terminal leaflets, that in the forth group angle ratio between right and left side in the terminal leaflet base, and that in the fifth group was angle of main and secondary vein at midrib of terminal leaflet. Cumulative contribution by the first, second and third principal component group was explained with 82.6%, a large percent of all information. 2. The leaf venation pattern investigated using soft X-ray photography revealed clado-and reticulo-camptodromous types according to branching angle of the secondary vein. And three groups by the developing degree of secondary vein were R. trichocarpa, R. ambigua. R. chinensis, R. typhina; R. radicans subsp. onentale, R. succedanea, R. verniciflua: and R. sylvestris. Classification key for the Rhus of Korean-native Anacardiaceae was made by the venation pattern and devevoping degree of the secondary vein. 3. The stomatal cell patterns were greatly classified into paracytic and anomocytic types, specific among species according to stomatal and subsidiary cell patterns, and various differences among the species was determined. Microstructure of the adaxial and abaxial surfaces could be divided into synclinal and anticlinal cell wall patterns, and were specific-species. Stomatal cells of R. chinensis were surrounded with characterized villus-like cells.

• Applied Microscopy
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• v.24 no.4
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• pp.61-77
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• 1994

The calcium-binding proteins (CaBP), parvalbumin (PV) and calbindin-D 28K (calbindin) are particularly abundant and specific in their distribution, and present in different subsets of neurons in many brain regions. Although their physiological roles in the neurons have not been elucidated, they are valuable markers of neuronal subpopulations for anatomical and developmental studies. This study is designed to characterize dorsal lateral geniculate nucleus (dLGN) neurons and axon terminals in terms of differential expression of immunoreactivity (IR) for two well-known CaBPs, PV and calbindin. The experiments were carried out on 6 adult monkeys. Monkeys were perfused under deep Nembutal anesthesia with 2% paraformaldehyde and 0.2% glutaraldehyde in 0.1M phosphate buffer. After removal, the brains were postfixed for 6-8 hr in 2% paraformaldehyde at $4^{\circ}C$ and infiltrated with 30% sucrose at $4^{\circ}C$. Thereafter, they were frozen in dry ice. Serial sections of the thalamus, at $20{\mu}m$, were made in the frontal plane with a sliding microtome. The sections were stained for PV and calbindin with indirect immunocytochemical methods. For electron microscopy, after infiltration with 30% sucrose the blocks of thalamus were serially sectioned at $50{\mu}m$ with a Vibratome in the coronal plane and stained immediately by indirect ABC methods without Triton X-100 in incubation medium. Stained sections were postfixed in 0.2% osmium tetroxide, dehydrated and flat-embedded in Spurr resin. The block was then trimmed to contain only a selected lamina or interlaminar space. The dLGN proper showed strong PV IR in fibers in all laminae and interlaminar zones. Particularly dense staining was noted in layers 1 and 2 that contain many stained fibers from optic tract. Neuronal cell body stained with PV was concentrated only in the laminae. In these laminae staining was moderate in cell bodies of all large and medium-sized neurons, and was strong in cell bodies of some small neurons together with their processes. Calbindin IR was marked in the neuronal cell body and neuropil in the S layers and interlaminar zones whereas moderate in the neuropil throughout the nucleus. Regional difference in distribution of PV and calbindin IR cell is distinct; the former is only in the laminae and the latter in both the S layer and interlaminar space. The CaBP-IR elements were confined to about $10{\mu}m$ in depth of Vibratome section. The IR product for CaBP was mainly associated with synaptic vesicle, pre- and post-synaptic membrane, and outer mitochondrial membrane and along microtubule. PV-IR was noted in various neuronal elements such as neuronal soma, dendrite, RLP, F, PSD and some myelinated or unmyelinated axons, and was not seen in the RSD and glial cells. Only a few neuronal components in dLGN was IR for calbindin and its reaction product was less dense than that of PV, and scattered throughout cytoplasm of soma of some relay neurons, and was also persent in some dendrite, myelinated axons and RLP. The RSD, F, PSD and glial elements were always non-IR for calbindin. Calbindin labelled RLP were presynaptic to unlabeled dendrite or dendritic spine and PSD. Calbindin-labeled dendrite of various sizes were always postsynaptic to unlabeled RSD, RLP or F. From this study it is suggested that dLGN cells of different functional systems and their differential projection to the visual cortex can be distinguished by differential expression of PV and calbindin.