• Restorative Dentistry and Endodontics
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• v.12 no.2
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• pp.73-80
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• 1987

The present study was designed to help elucidate the effect of glass ionomer cements on the exposed dental pulp by means of histologic examination. A total of 40 cavities of class V were prepared on the teeth of 4 dogs with exposure of 1mm in diameter on the bases of them. 20 cavities were filled with glass ionomer cement as the experimental group and the other 20 cavities were filled with zinc oxide eugenol cement as the control group. The dogs were sacrificed at one, two, three, and four weeks after filling, and the specimens were routinely prepared and stained with Hematoxylin-Eosin. The obtained microscopic findings were as follows: Inflammatory cell infiltrations were observed in control in 1 week, which decreased markedly with time. In all control groups, hemorrhage around exposed pulp tissue and coagulation change of pulp were observed. Secondary dentin formation and thickened predentin were observed in 4 week cases, and the recovery of pulp tissue was favorable on the whole. Inflammatory cell infiltration was observed in all GIC groups. Proliferation of blood vessel and congestion were observed with coagulation changes around the exposed pulp tissue. Secondary dentin formation and thickened predentin were observed in 3 weeks. In the experimental 4 week case, secondary dentin formation was evident. On the whole, pulpal irritation of glass ionomer cement was relatively severe. Recovery of pulp tissue in GIC groups was less favorable compared with that of ZOE groups.

• Membrane Journal
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• v.33 no.6
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• pp.390-397
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• 2023

Conventional extraction methods for polyhydroxybutyrate (PHB), a sustainable alternative to petroleum-based plastics, cause a decrease in molecular weight and a change in properties. In this work, we developed a method to extract PHB accumulated in microorganisms by physical disruption through filtration using a spiked carbon nanotube (CNT) membrane with functionalized CNT. In addition, filtration of the PHB-containing microbial solution was performed to confirm PHB extraction, which was found to be 4% more efficient than chloroform, the most used extraction method. These results indicate that the spiked CNT membrane has potential in the bioplastics recovery process.

• Journal of the Korean Applied Science and Technology
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• v.40 no.5
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• pp.1010-1021
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• 2023

In this study, we would like to confirm the collagen recovery effect through cell experiments of the flavonoid apigenin and baicalein and propose results that can support the collagen recovery effect through comparative transcriptome analysis. As a result of the study, it was confirmed that apigenin and baicalein were effective in recovering type I collagen damaged by UV in the HS68 cell line, and that both substances resulted in changes in the expression of ECM-related genes. Not only did it show a common mechanism for regulating the ECM, but it also showed the results of changing different categories of genes, making it possible to predict that it would have various effects on cells.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.5
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• pp.345-350
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• 2018

Nanomaterials have considerable potential to solve several key challenges in various electrochemical devices, such as fuel cells. However, the use of nanoparticles in high-temperature devices like solid-oxide fuel cells (SOFCs) is considered problematic because the nanostructured surface typically prepared by deposition techniques may easily coarsen and thus deactivate, especially when used in high-temperature redox conditions. Herein we report the synthesis of a self-regenerated Pd metal nanoparticle on the perovskite oxide anode surface for SOFCs that exhibit self-recovery from their degradation in redox cycle and $CH_4$ fuel running. Using Pd-doped perovskite, $La(Sr)Fe(Mn,Pd)O_3$, as an anode, fairly high maximum power densities of 0.5 and $0.2cm^{-2}$ were achieved at 1,073 K in $H_2$ and $CH_4$ respectively, despite using thick electrolyte support-type cell. Long-term stability was also examined in $CH_4$ and the redox cycle, when the anode is exposed to air. The cell with Pd-doped perovskite anode had high tolerance against re-oxidation and recovered the behavior of anodic performance from catalytic degradation. This recovery of power density can be explained by the surface segregation of Pd nanoparticles, which are self-recovered via re-oxidation and reduction. In addition, self-recovery of the anode by oxidation treatment was confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

• Korean Journal of Animal Reproduction
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• v.21 no.4
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• pp.373-379
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• 1997

This study was carried out to determine the hormone treatment scheme for an efficient superovulation and optimal recovery time for obtaining pronuclear embryos suitable for DNA injection in Korean native goats. For a superovulation, FSH(5.6mg) was given over four days in twice daily injections with (FSH/hCG group) or without(FSH group) hCG(100 IU) co-injection at the time of 7th FSH injection. Estrus cycle was synchronized by norgestomet ear-implantation for 11 days and its removal at the time of 6th FSH injection. Among the treated goats, the percentage of ovulated goats, which were examined at 70 to 76 h following implant removal, was greater in FSH/hCG group than in FSH group (100% vs 36.4%) but there was no significant difference in the mean numbers of ovulation points and fertilization rates between the two groups. To optimize hCG treatment scheme and recovery time, we injected hCG at the time of 7th (FSH/hCGa) or 8th(FSH/hCGb) FSH injection and then examined the developmental stage of the embryos recovered at different times after implant removal. In FSH/hCGa group, significant portions(31 to 44%) were beyond 1-cell stage, which was non-injectable, irrespective of their recovery time. However, in FSH/hCGb group recovered at 70 to 76 h after implant removal, great portions(69%) were fertilized and most of them(96.6%) were injectable 1-cell stage. Considering together the fertilization rate and developmental stage of recovered embryos, it is recommendable to administrate hCG at the time of final 8th FSH injection and collect the embryos at 70 to 76 h after implant removal to obtain injectable embryos as many as possible in Korean native goats.

• Journal of Microbiology and Biotechnology
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• v.28 no.5
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• pp.739-747
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• 2018

The low solubility and high-cost recovery of Propionibacterium acnes polyunsaturated fatty acid isomerase (PAI) are key problems in the bioproduction of high value-added conjugated linoleic acid (CLA). To improve the solubility of recombinant PAI, six chaperone proteins were coexpressed with PAI. Introduction of GroELS proteins dramatically improved the PAI solubility from 29% to 97%, with increased activity by 57.8%. Combined expression of DnaKJ-GrpE and GroELS proteins increased the activity by 11.9%. In contrast, coexpression of DnaKJ-GrpE proteins significantly reduced the activity by 57.4%. Plasmids pTf16 harboring the tig gene and pG-Tf2 containing the tig and groEL-groES genes had no visible impact on PAI expression. The lytic protein E was then introduced into the recombinant Escherichia coli to develop a cell autolysis system. A 35% activity of total intracellular PAI was released from the cytoplasm by suspending the lysed cells in distilled water. The PAI recovery was further improved to 81% by optimizing the release conditions. The lipase from Rhizopus oryzae was also expressed in E. coli, with an extracellular activity of 110.9 U/ml. By using the free PAI and lipase as catalysts, a joint system was established for producing CLA from sunflower oil. Under the optimized conditions, the maximum titer of t-10,c-12-CLA reached 9.4 g/l. This work provides an effective and low-cost strategy to improve the solubility and recovery of the recombinant intracellular PAI for further large-scale production of CLA.

• Korean Journal of Animal Reproduction
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• v.8 no.1
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• pp.16-21
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• 1984

This experiment was carried out to compare with the nonsurgical and surgical recovery of fertilized eggs in super-ovulated rabbits. Sixty-four eggs recovered were transferred to twelve synchronized, pseudopregnant rabbits to test the viability of the eggs by surgical transfer. Each group(I, II, III) received a single subcutaneous injection of 5mg PGF2${\alpha}$/kg B.W. at 24(Group I), 48(Group II) and 72 hours (Group III) after mating, respectivity. After the administration of PGF2${\alpha}$, vaginal washings were conducted at 3, 6, 9, 12 and 24 hrs, and frequency of vaginal washing was 5 times for the each group (I, II, III). In Group (IV, V, Ⅵ), the rabbits were killed to recover the fertilized eggs from the genital tract at 24(Group Ⅵ), 48(Group V) and 72 hours (Group Ⅵ) after mating, respectively. The results obtained were as follows: 1. Of the total eggs, 69.3%, 73.4% and 66.9% were recovered for Group I, II and III, respectively from the vagina within 6 hrs after PGF2${\alpha}$ injection and particularly for Group III. 2. The rates of egg recovery versus the number of corpora lutea were 55 (51.6-60%), 35.8 (24-52.6%), 33.4 (25-47%) and 72 (70.7-73.0)%, 60.3 (50-71.4)%, 449(44.4-45.5)% in Group I, II, III and Group IV, V, Ⅵ, respectively. 3. Most of eggs recovered were one-cell stage in Group Iand Group IV. More than one half of the eggs recovered in Group II and V were over eight-cell stage, and most of the eggs were so in Group III and Ⅵ. 4. When sixty-four eggs recovered between 24 to 72 hours after mating were transferred to pseudopregnant rabbits. Three recipients were pregnant, and the rate of pregnancy was 25%.

• Journal of Microbiology and Biotechnology
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• v.21 no.9
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• pp.979-987
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• 2011

Culture pH change has some important roles in signal transduction and secondary metabolism. We have already reported that acidic pH shock enhanced actinorhodin production in Streptomyces coelicolor. Among many potential governing factors on pH variation, the putative $Na^+/H^+$ antiporter (sha) genes in S. coelicolor have been investigated in this study to elucidate the association of the sha on pH variation and secondary metabolism. Through the transcriptional analysis and overexpression experiments on 8 sha genes, we observed that most of the sha expressions were promoted by pH shock, and in the opposite way the pH changes and actinorhodin production were enhanced by the overexpression of each sha. We also confirmed that sha8 especially has a main role in maintaining cell viability and pH homeostasis through $Na^+$ extrusion, in salt effect experiment under the alkaline medium condition by deleting sha8. Moreover, this gene was observed to have a function of pH recovery after pH variation such as the pH shock, being able to cause the sporulation. However, actinorhodin production was not induced by the only pH recovery. The sha8 gene could confer on the host cell the ability to recover pH to the neutral level after pH variation like a pH drop. Sporulation was closely associated with this pH recovery caused by the action of sha8, whereas actinorhodin production was not due to such pH variation patterns alone.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.833-837
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• 2010

This study aims at finding an optimal exhaust diffuser design of a high altitude testing chamber for a low bypass turbofan engine (F404-402) with thrust pound force of 17,700 and air mass flow rate of 66kg/s ejecting at a speed of Mach 1.66. The final proposed ejector size has better pressure recovery characteristics and targets to reduce operational cost at engine performance testing. Conventional high altitude test chamber layout was adopted and first drawn in two dimensions using Autocad software so as to determine the gas path, the ejector frontal size was then determined from gas dynamics equations considering traditional gas ejection method where both the engine exhaust and cell cooling air are exhausted via the ejector. Modification to a smaller ejector with an alternative secondary cell cooling exhaust port was then performed and modelled in 3D using Solid Works software.

• The Korean Journal of Physiology
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• v.15 no.1
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• pp.9-18
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• 1981

For centuries, ginseng has been used for the therapeutic purpose in oriental herb medicine. Several studies have been conducted in the past to evaluate the effect of ginseng on erythropoiesis. However the results were controversial. We therefore attempted in the present studies to evaluate the effect of ginseng on the erythropoietic activity. In one series of experiments, the recovery pattern of peripheral blood(red cell count, hemoglobin content, hematocrit and reticulocyte count) was studied in posthemorrhagic anemic rabbits. After animals were maintained with normal(control group) or 1 gm% ginseng (experimental group) diet for 2 weeks, hemorrhagic anemia was induced by withdrawing blood equivalent to 25% of the total blood volume and then changes in peripheral blood were followed for following 30 days. In other series of experiments, we studied effect of ginseng on erythrokinetics using $^{59}Fe$. $^{59}Fe(10{\sim}40\;{\mu}Ci/animal)$ was injected intravenously after animals were fed with normal (control group) or 1 gm% ginseng(experimental group) diet for 2 weeks. And radioactivities in the blood compartments were measured at appropriate intervals for 15 days. Front these various erythrokinetic parameters were estimated. Results are summarized as follows: 1) Reticulocyte count was higher in the experimental group than in the control group after 2 weeks of administration of experimental diet. During the posthemorrhagic period, the reticulocyte count increased in both the control and experimental groups, but the increase appeared much earlier in the experimental group. 2) The posthemorrhagic recoveries of hematocrit, hemoglobin content and red cell count appeared to be faster in the experimental group as compaired with the control group. 3) The half life$(T_{1/2})$ of $^{59}Fe$ in the plasma was significantly(P<0.05) shorter in the experimental group(82.6 min, N=8) than in the control group(121 min, N=6). Plasma iron turnover (PIT) of the experimental group (1.78 mg/dl/24 hr.) was approximately 4 times greater than that of the control group(0.45 mg/dl/24 hr.). 4) The maximum red cell utilization(RC-U) was 82.1% in the experimental group ana 74.5% in the control group. Red cell iron turnover(RIT) of the experimental group(1.62 mg/dl/24 hr.) was slightly higher than that of the control group(0.35 mg/dl/24 hr). 5) Erythron turnover was significantly(p<0.05) greater in the experimental group(1.27 mg/dl/24 hr.) than in the control group(0.24 mg/dl/24 hr.). Marrow transit time of the experimental group(2.05 days) tended to he faster than that of the control group(2.84 days). These results suggest that the gingseng improves the recovery of posthemorrhagic anemia and stimulates the erythropoiesis in rabbits.