• The Journal of Korean Academy of Prosthodontics
• /
• v.58 no.4
• /
• pp.275-281
• /
• 2020

Purpose: Development of a latent antimicrobial soft liner is strongly needed to overcome a possible inflammation related with its dimensional degrade or surface roughness. Modified tissue conditioner (TC) containing chitosan-doped silver nanoparticles (ChSN) complexes were synthesized and assessed for their characterizations. Materials and methods: ChSN were preliminarily synthesized from silver nitrate (AgNO₃), sodium borohydride (NaBH₄) as a reducing agent and chitosan biopolymer as a capping agent. Ultraviolet-visible and Fourier transform infrared spectroscopy were conducted to confirm the stable reduction of nanoparticles with chitosan. Modified TC blended with ChSN by 0 (control), 1.0, 3.0 and 5.0 % mass fraction were mechanically tested by ultimate tensile strength (UTS), silver ion elution and color stability (n=7). Results: At 24 hour and 7 day storage periods, UTS values were not significant (P>.05) as compared with pristine TC (control) and silver ion was detected with the dose-dependent values of ChSN incorporated. Color stability of TC were influenced by ChSN add, with the higher doses, the significantly greater color changes (P<.05). Conclusion: A stable synthesized ChSN was acquired and modified TC loading ChSN was characterized as silver ion releasing without detrimental physical property. For its clinical application, antimicrobial test, color control and multifactor investigations are still required.

• Korean journal of communication and information
• /
• v.77
• /
• pp.200-254
• /
• 2016

This paper deals with historical changes in the market of Korean newsprint paper since 1945. Particularly, this paper does not examine only the structure of supply and demand in the newsprint paper market, but also general dynamics of the market from a perspective of Harold Innis's socioeconomic history. As a result, this paper concludes that the general dynamics of Korean newsprint paper market has persistently responded to a stimulus from external markets due to a scarcity of natural resources. To more concretely put it, until 1967 when the newsprint paper market was opened, Korean government had tried to control both newspaper industries and paper manufacture businesses by the matters of price and distribution of the newsprint paper. But since the market was opened, a general dynamics of the Korean newsprint paper market has been vulnerable to uncoordinated properties of external markets. Consequently, even though 'self-sufficiency' of newsprint papers was achieved in 1974, the price of newsprint papers has been often rising and falling.

• Journal of the Korean Ceramic Society
• /
• v.45 no.10
• /
• pp.618-624
• /
• 2008

Various calcium phosphate bioceramics are distinguished by their excellent biocompatibility and osteoconductivity. Especially, the exceptional biodegradability of $\beta$-TCP makes it a bone graft substitute of choice in many clinical applications. The activation of osteoclasts, differentiated from macrophage precursor cells, trigger a cell-mediated resorption mechanism that renders $\beta$-TCP biodegradable. Based on this evidence, we studied the biodegradation process of granular-type $\beta$-TCP bone graft substitute through in vitro and in vivo studies. Raw 264.7 cells treated with RANKL and M-CSF differentiated into osteoclasts with macrophage-like properties, as observed with TRAP stain. These osteoclasts were cultured with $\beta$-TCP nano powders synthesized by microwave-assisted process. We confirmed the phagocytosis of osteoclasts by observing $\beta$-TCP particles in their phagosomes via electron microscopy. No damage to the osteoclasts during phagocytosis was observed, nor did the $\beta$-TCP powders show any sign of cytotoxicity. We also observed the histological changes in subcutaneous tissues of rats implanted with granule-type $\beta$-TCP synthesized by fibrous monolithic process. The $\beta$-TCP bone graft substitute was well surrounded with fibrous tissue, and 4 months after implantation, 60% of its mass had been biodegraded. Also, histological findings via H&E stain showed a higher level of infiltration of lymphocytes as well as macrophages around the granule-type $\beta$-TCP. From the results, we have concluded that macrophages play an important role in the biodegradation process of $\beta$-TCP bone graft substitutes.

• Journal of the Korean Electrochemical Society
• /
• v.10 no.3
• /
• pp.196-202
• /
• 2007

The performance characteristics of the polymer electrolyte fuel cells (PEFCS) were investigated under various humidification conditions at steady-state and transient conditions. The PEFC studied in this study was characterized by I-V curves in the potentiostatic mode and EIS (electrochemical impedance spectroscopy). The I-V curves representing steady-state performance were obtained from OCV to 0.25 V, and the dynamic performance responses were obtained at some voltages. The effects of anodic external humidification were measured by varying relative humidity of hydrogen from 20% to 100% while dry air was supplied in the cathode. At the high voltage region, the performance became higher with the increase of the temperature, while at the low voltage region, the performance decreased with the increase of temperature. The EIS showed that ohmic losses were larger at the dry condition of membrane and the effects of mass transport losses increased remarkably when the external and self-humidification were high. The dynamic responses were also monitored by changing the voltage of the PEFC instantly. As the temperature increased, the current reached steady-state earlier. The self-humidification with the generated water delayed the stabilization of the current except for low voltage conditions.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.2
• /
• pp.161-168
• /
• 2011

The heating, ventilating, air conditioning (HVAC) system is a very important part of an automotive vehicle: it controls the microclimate inside the passenger's compartment and removes the frost or mist that is produced in cold/rainy weather. In this study, the numerical analysis of the defrost duct in an HVAC system and the de-icing pattern is carried out using commercial CFX-code. The mass flow distribution and flow structure at the outlet of the defrost duct satisfied the duct design specification. For analyzing the de-icing pattern, additional grid generation of solid domain of ice and glass is pre-defined for conductive heat transfer. The flow structure near the windshield, streakline, and temperature fields clearly indicate that the de-icing capacity of the given defrost duct configuration is excellent and that it can be operated in a stable manner. In this paper, the unsteady changes in temperature, water volume fraction, and static enthalpy at four monitoring points are discussed.

• Korean Journal of Biological Psychiatry
• /
• v.11 no.2
• /
• pp.117-126
• /
• 2004

Objects:It has been reported that the incidence of tardive dyskinesia(TD), the remarkable abnormal involuntary movement, was higher in the schizophrenics with high blood sugar levels and that TD had been improved by small amount of insulin-injection for 90 days. And also it was generally known that the blood lipids were higher in the schizophrenics with tardive dyskinesia. Thus, we tried to replicate the correlations of abnormal involuntary movements with blood sugar levels and blood lipids in chronic schizophrenics treated with antipsychotics. Methods:Thirty-eight male schizophrenic inpatients who were stable in clinical state with medications, were included. The patients who had been already diagnosed as diabetes mellitus(DM), organic brain disorder, substance- related disorder, physical illness were excluded and also we excluded female patients to remove the hormonal effect on TD. Eleven patients who ranked higher(above five) in the Abnormal Involuntary Movement Scale(AIMS) were assigned into 2 groups, a dibenese group and a placebo group. Diabinese or placebos were administrated for 3 weeks with antipsychotics and AIMS was rechecked. Results:There were no correlations between the total AIMS scores and blood sugar and lipids levels in all subjects. The means of total and subscale scores(objective, face, and extremity) of AIMS did not reveal statistical significances between diabinese and placebo groups. However(total, jaw, face, upper arm, and objective feeling), were statistically higher in the diabinese group than those in the placebo group. And correlations of total cholesterol(TC) with fast blood sugar(FBS), weight with body mass index(BMI) and waist, total glycerol (TG) with BMI were statistically significant. Conclusion:In this study, there were statistical significances in the changes in ratings of AIMS scores between the diabinese group and the placebo group. Application of oral hypoglycemic agent might be a way of improving abnormal involuntary movements in schizophrenics with abnormal involuntary movements or TD. Althogugh it was not certain that there were correlations of abnormal involuntary movement with blood sugar and lipids, correlations of TC/TG with AIMS, of FBS with AIMS cautiously suggest that the regular check of $HbA_1C$, waist, and weight are recommended for schizophrenics.

• Toxicological Research
• /
• v.28 no.1
• /
• pp.25-31
• /
• 2012

The purpose of this study was to determine the acute pulmonary toxicity of metallic silver nanoparticles (MSNPs, 20.30 nm in diameter). Acute pulmonary toxicity and body distribution of inhaled MSNPs in mice were evaluated using a nose-only exposure chamber (NOEC) system. Bronchoalveolar lavage (BAL) fluid analysis, Western blotting, histopathological changes, and silver burdens in various organs were determined in mice. Mice were exposed to MSNPs for 6 hrs. The mean concentration, total surface area, volume and mass concentrations in the NOEC were maintained at $1.93{\times}10^7$ particles/$cm^3$, $1.09{\times}10^{10}\;nm^2/cm^3$, $2.72{\times}10^{11}\;nm^3/cm^3$, and 2854.62 ${\mu}g/m^3$, respectively. Inhalation of MSPNs caused mild pulmonary toxicity with distribution of silver in various organs but the silver burdens decreased rapidly at 24-hrs post-exposure in the lung. Furthermore, inhaled MSNPs induced activation of mitogen-activated protein kinase (MAPK) signaling in the lung. In summary, single inhaled MSNPs caused mild pulmonary toxicity, which was associated with activated MAPK signaling. Taken together, our results suggest that the inhalation toxicity of MSNPs should be carefully considered at the molecular level.

• Molecular & Cellular Toxicology
• /
• v.1 no.2
• /
• pp.116-123
• /
• 2005

The application of high pressure on cellular morphology, proliferation and protein expression of Jurkat cells (human T lymphocyte cell line) has been extensively investigated. In the present study, we manufactured a novel pressure chamber that modulates 5% $CO_{2}$, temperature and pressure (up to 3 ATA). Jurkat cells was incubated 2 ATA pressure and analyzed cellular morphology and growth using an electron microscopy and MTT assay. The cells showed the morphological changes in the cell surface, which appeared to cause a severe damage in cell membrane. The growth rate of the cells under 2 ATA pressure decreased as cultured time got increased. Furthermore, a long term exposure of high pressure on Jurkat cells may act as one of the important cellular stresses that leads to inducing cell death. Cellular proteomes were separated by 2-dimensional electrophoresis with pH 3-10 ranges of IPG Dry strips. And many proteins showed significant up-and-down expressions with hyperbaric pressure. Out of all, 10 spots were identified significantly using matrix-assisted laser desorption/ionization-time of fight (MALDI-TOF) mass spectrometry. We and found that 9 protein expressions were decreased and one protein, heat shock protein HSP 60, was increased in Jurkat cells under 2 ATA. Identified proteins were related to lipid metabolism and signal transduction.

• Korean Journal of Food Science and Technology
• /
• v.28 no.5
• /
• pp.827-833
• /
• 1996

Along with the increased necessity for an efficient utilization of Korean wild edible plants growing in fields and mountains, attempts were made to investigate the patterns of flavor changes accompanied hy various conditions of dispersion medium. The effect of various pH values and concentration of sucrose or NaCl of dispersion medium on volatile flavor patterns was investigated to evaluate the applicability of flavor components extracted from Capsella bursa-pastoris for food industry. Essential oils from this wild plant were isolated by simultaneous steam distillation-extraction (SDE) method using diethyl ether as solvent. Concentrated samples were analyzed s chromatography (GC) and combined gas chromatography-mass spectrometry (GC-MS). Most volatile flavor components of Capsella bursa-pastoris showed good recovery when steam distilled at pH 7 by SDE method. Increasing concentration of sucrose and 15% by NaCl, resulted in greater numbers of identified flavor components from Capsella bursa-pastoris.

• Clinical and Experimental Reproductive Medicine
• /
• v.44 no.1
• /
• pp.33-39
• /
• 2017

Objective: The aim of this study was to assess the changes of follicular fluid (FF) and serum levels of cerebellin precursor protein 1 (cbln1) and betatrophin in patients with polycystic ovary syndrome (PCOS) undergoing in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) with a gonadotropin-releasing hormone (GnRH) antagonist protocol. Methods: Twenty infertile women with PCOS and 20 control women diagnosed as poor responders undergoing ovarian stimulation with a GnRH antagonist were included. Blood samples were obtained during ovum pick-up. Follicular fluid from a dominant follicle was collected from the subjects. Using enzyme-linked immunosorbent assays, FF and serum levels of cbln1 and betatrophin were measured in both groups of participants. Metabolic and hormonal parameters were also determined and correlated with each other. Results: Both groups of women had similar serum and FF betatrophin levels ($55.0{\pm}8.9ng/mL$ vs. $53.1{\pm}10.3ng/mL$, p=0.11). The serum and FF betatrophin levels of poor responders were found to be similar ($49.9{\pm}5.9ng/mL$ vs. $48.9{\pm}10.7ng/mL$, p=0.22). Conversely, the FF cbln1 levels of PCOS women were found to be significantly higher than the serum cbln1 levels ($589.1{\pm}147.6ng/L$ vs. $531.7{\pm}74.3ng/L$, p<0.02). The FF cbln1 levels of control participants without PCOS were significantly higher than their serum cbln1 levels ($599.3{\pm}211.5ng/L$ vs. $525.3{\pm}87.0ng/L$, p=0.01). Positive correlations were detected among body mass index, insulin resistance, serum insulin, total testosterone, and betatrophin levels in the PCOS group. Conclusion: Follicular fluid betatrophin and cbln1 concentrations may play a pivotal role on follicular growth in PCOS subjects undergoing IVF/ICSI with an antagonist protocol.