• Polymer(Korea)
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• 제32권5호
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• pp.415-420
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• 2008

The porcine small intestinal submucosa (SIS) without immunorejection responses and hyalunonic acid (HA) can be used as biomaterials. In this study, we tried to design and characterize novel sponge. SIS- HA sponge was prepared by freeze-drying after addition 1wt% HA solution into fabricated SIS sponge. Sponge was crosslinked with 1-ethyl-(3-3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC) solution with 100mM concentration for 24 hrs and lyophilized. SIS-HA sponge was characterized by scanning electron microscopy and fourier transform infrared spectrometer. And water absorption ability of sponge was evaluated. We seeded NIH/3T3 cells in SIS-HA sponge and cellular attachment was assayed by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltertazolium-bromide (MTT) test. We demonstrated presence of HA in SIS-HA sponge from C-O functional group observed by the FT-IR analysis. Moreover, we confirmed low cytotoxicity and high cell viability of the SIS-HA sponges. Therefore, we could expect that SIS- HA scaffolds are applicable for the tissue regeneration.

• International Journal of Industrial Entomology and Biomaterials
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• 제22권2호
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• pp.101-105
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• 2011

Transparency and insolubility of eardrum patch against exudates are important for otolaryngological surgery. The author prepared silk fibroin (SF) films with various concentrations and temperature and then examined solubility and conformation of SF films. SF films were transparent regardless of the various preparation conditions. Although most SF films are soluble in 1X PBS solution at $37^{\circ}C$ for 1 h, the SF film with 3.4% with $60^{\circ}C$ was insoluble. Scanning electron microscopy (SEM) showed that the SF films have solid and smooth surface. Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) results showed that the conformation of SF films was influenced by the preparation conditions including SF concentration and casting temperature. In conclusion, SF membrane with transparence and insolubility against exudates could be considered as eardrum patch resources.

• Korean Journal of Materials Research
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• 제29권3호
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• pp.155-159
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• 2019

Surface plasmon resonance is the resonant oscillation of conduction electrons at the interface between negative and positive permittivity material stimulated by incident light. In particular, when light transmits through the metallic microhole structures, it shows an increased intensity of light. Thus, it is used to increase the efficiency of devices such as LEDs, solar cells, and sensors. There are various methods to make micro-hole structures. In this experiment, micro holes are formed using a wet chemical etching method, which is inexpensive and can be mass processed. The shape of the holes depends on crystal facets, temperature, the concentration of the etchant solution, and etching time. We select a GaAs(100) single crystal wafer in this experiment and satisfactory results are obtained under the ratio of etchant solution with $H_2SO_4:H_2O_2:H_2O=1:5:5$. The morphology of micro holes according to the temperature and time is observed using field emission - scanning electron microscopy (FE-SEM). The etching mechanism at the corners and sidewalls is explained through the configuration of atoms.

• Journal of Surface Science and Engineering
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• 제52권2호
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• pp.62-71
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• 2019

Al1050 and Al7075 alloy specimens were exposed to atmospheric conditions for 24 months and analyzed by Transmission Electron Microscopy to characterize their corrosion behavior and oxide film characteristics, especially focusing on intergranular corrosion or oxidation. In general, the intergranular oxygen penetration depth of Al1050 was deeper than Al7075. Since O and Si signals were overlapped at the oxidized grain boundaries of Al1050 and Mg is not included in Al1050, it is concluded that Si segregated along the grain boundaries directly impacts on the intergranular corrosion of Al1050. Cr-Si or Mg-Si intermetallic particles were not observed along the grain boundaries of Al7050, but Mg-Si particle was barely observed in the matrix. 10-nm size Mg-Zn particles were also found all over the matrix. Mg was mainly observed along the oxidized grain boundary of Al7075, but Si was not detected due to the Mg-Si particle formation in the matrix and relatively low concentration of Si in Al7075. Therefore, it is thought that Mg plays an important role in the intergranular corrosion of Al7075 under atmospheric corrosion conditions.

• Molecules and Cells
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• 제42권4호
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• pp.292-300
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• 2019

Immunometabolism, defined as the interaction of metabolic pathways with the immune system, influences the pathogenesis of metabolic diseases. Metformin and carbon monoxide (CO) are two pharmacological agents known to ameliorate metabolic disorders. There are notable similarities and differences in the reported effects of metformin and CO on immunometabolism. Metformin, an anti-diabetes drug, has positive effects on metabolism and can exert anti-inflammatory and anti-cancer effects via adenosine monophosphate-activated protein kinase (AMPK)-dependent and AMPK-independent mechanisms. CO, an endogenous product of heme oxygenase-1 (HO-1), can exert anti-inflammatory and antioxidant effects at low concentration. CO can confer cytoprotection in metabolic disorders and cancer via selective activation of the protein kinase R-like endoplasmic reticulum (ER) kinase (PERK) pathway. Both metformin and CO can induce mitochondrial stress to produce a mild elevation of mitochondrial ROS (mtROS) by distinct mechanisms. Metformin inhibits complex I of the mitochondrial electron transport chain (ETC), while CO inhibits ETC complex IV. Both metformin and CO can differentially induce several protein factors, including fibroblast growth factor 21 (FGF21) and sestrin2 (SESN2), which maintain metabolic homeostasis; nuclear factor erythroid 2-related factor 2 (Nrf2), a master regulator of the antioxidant response; and REDD1, which exhibits an anticancer effect. However, metformin and CO regulate these effects via different pathways. Metformin stimulates p53- and AMPK-dependent pathways whereas CO can selectively trigger the PERK-dependent signaling pathway. Although further studies are needed to identify the mechanistic differences between metformin and CO, pharmacological application of these agents may represent useful strategies to ameliorate metabolic diseases associated with altered immunometabolism.

• Journal of dental hygiene science
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• 제19권1호
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• pp.1-8
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• 2019

Background: Erosion is a gradual process that occurs fairly quickly, and the full extent of the erosive effects of acidic beverages is not yet clear. The present study aimed to determine the differences in the erosive potentials among four naturally acidic fruit nectars within the same range of titratable acidity and to determine the influence of the components of organic acids on tooth erosion. Methods: Diluted fruit nectars (mandarin 1:1.1, orange 1:1.7, lemon 1:15, grapefruit 1:20) with the same range of titratable acidity (7.9 ml) and their corresponding organic acids (0.05%, 0.1%, 0.3%, and 0.5% citric acid, malic acid, and a citric and malic acid mixture [pH 2.8], respectively) were used. Specimens were placed in conical tubes with 50 ml of each of the test solutions for 1 hour. A microhardness test and scanning electron microscopy were used to measure enamel erosion. Acid separation was carried out using high-performance liquid chromatography to analyze the composition of each test solution. Results: Similar decreases in the Vickers hardness number (VHN) were observed among the groups treated with the following diluted fruit nectars: diluted mandarin nectar ($75.9{\Delta}VHN$), diluted lemon nectar ($89.1{\Delta}VHN$), diluted grapefruit nectar ($91.7{\Delta}VHN$), and diluted orange nectar ($92.5{\Delta}VHN$). No statistically significant differences were found in the enamel surface hardness after erosion (p>0.05). Citric and malic acids were the major organic acids in the test fruits. The lemon and orange groups had the highest malic acid concentrations, and the mandarin group had the lowest malic acid concentration. Conclusion: The titratable acidity and the citric and malic acid contents of the fruits could be crucial factors responsible for enamel erosion. Therefore, fruit-based drinks should be regarded as potentially erosive.

• Biomedical Science Letters
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• 제25권3호
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• pp.227-236
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• 2019

In this study, the anti-oxidant, anti-inflammatory, and anti-obesity activities of an ethanol extracts of Ulmus divididiana var. japonica (UDE) were investigated in vitro and in vivo. UDE anti-oxidant activity was evaluated with an Electron Spin Resonance (ESR) spectrometer, which measured 1, 1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activity. Cell viabilities were estimated using 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay. LPS-stimulated BV-2 microglia were used to study the production of nitric oxide (NO). Cells stimulated with LPS produce more NO than normal control cells. However, cells treated with the UDE decreased this production in a concentration dependent manner (100, 250, 500, $1,000{\mu}g/mL$). Also, we investigated the anti-obese activity of UDE in SD rats. The SD rats were randomly divided into five groups: 10% low fat diet (N), 45% high fat diet (H), 45% high fat diet + garcinia extracts 200 mg/kg/day (HG200), high fat diet + UDE 200 mg/kg/day (HU200), high fat diet + UDE 400 mg/kg/day (HU400). UDE was found to lower whole body and abdominal and epididymal adipose tissue weights and lowered plasma levels of triglyceride (TG), compared to those in H group. Histological analyses of the liver and fat tissues of rat treated with UDE revealed significantly decreased number of lipid droplets and decreased size of adipocytes compared to the H group. These results suggest that UDE might be used to develop potent anti-oxidant, anti-inflammatory, and anti-obesity agents, and may be useful as ingredients for related new functional raw materials.

• Corrosion Science and Technology
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• 제17권6호
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• pp.287-291
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• 2018

In this study, corrosion behavior of a SA178-A alloy used in the boiler tube of a district heating system was investigated in different environments where it was exposed to pure water, district heating (DH) water, and filtered district heating (FDH) water. After the corrosion test, the surface morphology was examined for observation of the number of pitting sites and pitting area fraction, using a scanning electron microscope. The DH water and FDH water conditions resulted in a lower corrosion potential and pitting potential, and revealed a significantly higher corrosion rate than the pure water condition. The pitting sites in the DH water (pH 9.6) were approximately eighteen times larger than those in the pure water (pH 9.6). Compared to the DH water, the corrosion potential became more noble in the FDH water condition, where iron ions were reduced through filtration. However, the corrosion rate increased in the FDH water due to an increased concentration of chloride ions, which deteriorated the stability of passive film.

• Asian-Australasian Journal of Animal Sciences
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• 제32권7호
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• pp.977-987
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• 2019

Objective: The use of tannin extract and other phytochemicals as dietary additives in ruminants is becoming more popular due to their wide biological actions such as in methane mitigation, bypass of dietary protein, intestinal nematode control, among other uses. Unfortunately, some have strong astringency, low stability and bioavailability, and negatively affecting dry matter intake and digestibility. To circumvent these drawbacks, an effective delivery system may offer a promising approach to administer these extracts to the site where they are required. The objectives of this study were to encapsulate acacia tannin extract (ATE) with native starch and maltodextrin-gum arabic and to test the effect of encapsulation parameters on encapsulation efficiency, yield and morphology of the microparticles obtained as well as the effect on rumen in vitro gas production. Methods: The ATE was encapsulated with the wall materials, and the morphological features of freeze-dried microparticles were evaluated by scanning electron microscopy. The in vitro release pattern of microparticles in acetate buffer, simulating the rumen, and its effect on in vitro gas production was evaluated. Results: The morphological features revealed that maltodextrin/gum-arabic microparticles were irregular shaped, glossy and smaller, compared with those encapsulated with native starch, which were bigger, and more homogenous. Maltodextrin-gum arabic could be used up to 30% loading concentration compared with starch, which could not hold the core material beyond 15% loading capacity. Encapsulation efficiency ranged from $27.7%{\pm}6.4%$ to $48.8%{\pm}5.5%$ in starch and $56.1%{\pm}4.9%$ to $64.8%{\pm}2.8%$ in maltodextrin-gum arabic microparticles. Only a slight reduction in methane emission was recorded in encapsulated microparticles when compared with the samples containing only wall materials. Conclusion: Both encapsulated products exhibited the burst release pattern under the pH conditions and methane reduction associated with tannin was marginal. This is attributable to small loading percentages and therefore, other wall materials or encapsulation methods should be investigated.

• Korean Chemical Engineering Research
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• 제59권2호
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• pp.174-179
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• 2021

Recently, hybrid coal research is underway to upgrade low-grade coal. The hybrid coal is made by mixing low-grade coal with bioliquids such as molasses, sugar cane, and lignin. In the case of lignin used here, a large amount of lignin is included in the wastewater of the papermaking process, and thus, research on hybrid coal production using the same is attracting attention. However, since a large amount of metal ions are contained in the lignin wastewater from the papermaking process, substances that corrode the generator are generated during combustion, and the amount of fly ash is increased. To solve this problem, it is essential to remove metal ions in the lignin wastewater. In this study, metal ions were removed by ion exchange with a alumina hollow fiber membrane coated with K-Phillipsite (K-PHI) zeolite. The alumina hollow fiber membrane used as the support was prepared by the nonsolvent induced phase separation (NIPS) method, and K-PHI seeds were prepared by hydrothermal synthesis. The prepared K-PHI seed was seeded on the surface of the support and coated by secondary growth hydrothermal synthesis. The characteristic of prepared coating membrane was analyzed by Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Energy Dispersive Spectroscopy (EDX), and the concentration of metal ions before and after ion exchange was measured by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The extraction amount of K+ is 86 mg/kg, and the extraction amount of Na+ is 54.9 mg/kg. Therefore, K-PHI zeolite membrane has the potential to remove potassium and sodium ions from the solution and can be used in acidic lignin wastewater.