• Membrane Journal
• /
• v.21 no.1
• /
• pp.46-54
• /
• 2011

In this study, combined effect of airflow rate, $TiO_2$ concentration, solution pH and $Ca^{+2}$ addition on HA (humic acid) fouling in submerged, photocatalytic hollow-fiber microfiltraiton was investigated systematically. Results showed that UV irradiation alone without $TiO_2$ nanoparticles could reduce HA fouling by 40% higher than the fouling obtained without UV irradiation. Compared to the HA fouling without UV irradiation and $TiO_2$ nanoparticles, the HA fouling reduction was about 25% higher only after the addition of $TiO_2$ nanoparticles. Both adsorptive and hydrophilic properties of $TiO_2$ nanoparticles for the HA can be involved in mitigating membrane fouling. It was also found that the aeration itself had lowest effect on fouling mitigation while the HA fouling was affected significantly by solution pH. Transient behavior of zeta potential at different solution pHs suggested that electrostatic interactions between HA and $TiO_2$ nanoparticles should improve photocatalytic efficiency on HA fouling. $TiO_2$ concentration was observed to be more important factor than airflow rate to reduce HA fouling, implying that surface reactivity on $TiO_2$ naoparticles should be important fouling mitigation mechanisms in submerged, photocatalyic microfiltraiton. This was further supported by investigating the effect of $Ca^{+2}$ addition on fouling mitigation. At higher pH (= 10), addition of $Ca^{+2}$ can play an important role in bridging between HA and $TiO_2$ nanoparticles and increasing surface reactivity on nanoparticles, thereby reducing membrane fouling.

• Microbiology and Biotechnology Letters
• /
• v.40 no.1
• /
• pp.57-65
• /
• 2012

Antifungal compounds from Bacillus polyfermenticus CJ6 were purified using SPE, preparative HPLC, and reverse phase-HPLC. Antifungal compounds from B. polyfermenticus CJ6 were separated into three fractions (8, B, C) using preparative HPLC. LC/MS analysis of antifungal peaks suggested that B. polyfermenticus CJ6 produces lipopeptides; two kinds of iturin A ($C_{14}$, $C_{15}$), three kinds of surfactins ($C_{13}$, $C_{14}$, $C_{15}$), four kinds of fengycin A ($C_{14}$, $C_{15}$, $C_{16}$, $C_{17}$) and two kinds fengycin B ($C_{16}$, $C_{17}$). The antifungal activity of fraction 8, which was presumed as inturin A, was found to be stable after the pH, heat or proteolytic enzyme treatment, but it was unstable at 50-$70^{\circ}C$ for 24 hr. The antifungal activity of fraction B, which presumed as surfactins and fengycin A, was found to be stable after the heat treatment, but it was unstable in the pH 3.0 and after the protease (type I) or ${\alpha}$-chymotrypsin treatment. The antifungal activity of fraction C, which was presumed as fengycin A and B, was found to be stable in the pH 3.0-9.0 range and the heat treatment, but it was unstable with the treatment of protease (type I). The amino acid composition of the purified peaks 8-1 and 8-2 were Asx, Tyr, Gln, Pro, and Ser in a molar ratio of 3:1:1:1:1, which showed the same amino acid composition as iturin. From these results, we confirmed that antifungal compounds from B. polyfermenticus CJ6 most likely belonged to iturin A as well as surfactins and fengycins. As lipopeptides are known to act in a synergistic manner, the antifungal compounds from B. polyfermenticus CJ6 might have potential uses in biotechnology and biopharmaceutical applications.

• Korean Journal of Veterinary Research
• /
• v.25 no.1
• /
• pp.7-17
• /
• 1985

Many investigators have been pursuing various attempts so far to produce hepatitis B surface antigen(HBsAg) vaccines using the techniques such as isolation from plasma of chronic HBsAg carrier, recombinant DNA technique or preparation of synthetic peptides specific for immunogenic determinants. Hepatitis B virus can not grow on any cell lines by the tissue culture technique at the present time. The plasma of chronic HBsAg carrier is expensive and its source is limited. The HBsAg from the recombinant DNA technique gave still very low yield. Another approach, therefore, has been initiated to develop a synthetic hepatitis B virus vaccine. The possible use of several distinct synthetic vaccines in prophylaxis can be facilitated by availability of full synthetic immunogens. Peptides synthesized for potential application as antiviral vaccines have been mostly tested in the form of conjugates with carrier proteins, although the free synthetic peptide can be immunogenic. To understand basic knowledges on the antigenicity and immunogenicity of a synthetic peptide specific for major immunogenic determinant of HBsAg, a nonapeptide, $H_2N^{139}Cys-Thr-Lys-Pro-Thr-Asp-Gly-^{146}Asn-Aba$ COOH, which corresponds to HBsAg amino acid residues 139 to 147, was synthesized by the Merrifield's solid-phase method with a slight modification. The antigenicity and immunogenicity of this specific synthetic peptide were examined comparing with purified plasma-derived natural HBsAg. The results obtained are as follows; 1. The peptide synthesized showed the identical amino acid composition to the theoretical value. The degree of purification and molecular weight were acertained by methods of high performance liquid chromatography and mass spectrometry. 2. Using m-maleimidobenzoyl-N-hydroxysuccinimide ester as a conjugating agent, the synthetic peptide was conjugated to rabbit albumin and ${\gamma}$-globulin, tetanus and diphtheria toxoids, and keyhole limpet hemocyanin. Their conjugation yields were 8.3, 9.5, 15.8, 13.5, and 11.2%, respectively. 3. The natural HBsAg was purified from plasma of chronic HBsAg carrier. By the electron microscopic observation of the purified natural HBsAg preparation, no Dane particles were observed and the preparation showed negative DNA polymerase activity. 4. Antigenicity of the synthetic peptide and the plasma-derived natural HBsAg was determined by competition radioimmunoassay using $^{125}I$-natural HBsAg. Their 50% inhibitions appeared as $90{\mu}g/ml$ and $0.12{\mu}g/ml$ for the synthetic peptide and the natural HBsAg, respectively. This indicates that the former was about 750-fold less antigenic than the latter. 5. Immunogenicity of the synthetic peptide was determined by administering the peptide-carrier conjugates into rabbits with and without Freund's complete adjuvant. Regardless the carrier proteins and adjuvant, positive immune responses to the synthetic peptide were observed. The higher antibody titers, however, were shown in the groups administered with Freund's complete adjuvant. 6. Immunizing dose 50% in mice of the various peptide-carrier conjugates was 5.47, 6.00, 65.16, 31.25 and $13.03{\mu}g/dose$ for rabbit albumin and ${\gamma}$-globulin, tetanus and diphtheria toxoids, and keyhole limpet hemocyanin, respectively, while the natural HBsAg showed $0.65{\mu}g/dose$. 7. It was postulated that homologous proteins prefer to heterologous ones as the carriers.

• Applied Chemistry for Engineering
• /
• v.31 no.2
• /
• pp.115-124
• /
• 2020

Sustainable plastics can be mainly categorized into (1) biodegradable plastics decomposed into water and carbon dioxide after use, and (2) biomass-derived plastics possessing the carbon neutrality by utilizing raw materials converted from atmospheric carbon dioxide to biomass. Recently, biomass-derived engineering plastics (EP) and natural nanofiber-reinforced nanocomposites are emerging as a new direction of the industry. In addition to the eco-friendliness of natural resources, these materials are competitive over petroleum-based plastics in the high value-added plastics market. Polyesters and polycarbonates synthesized from isosorbide and 2,5-furandicarboxylic acid, which are representative biomass-derived monomers, are at the forefront of industrialization due to their higher transparency, mechanical properties, thermal stability, and gas barrier properties. Moreover, isosorbide has potential to be applied to super EP material with continuous service temperature over 150 ℃. In situ polymerization utilizing surface hydrophilicity and multi-functionality of natural nanofibers such as nanocellulose and nanochitin achieves remarkable improvements of mechanical properties with the minimal dose of nanofillers. Biomass-derived tough-plastics covered in this review are expected to replace petroleum-based plastics by satisfying the carbon neutrality required by the environment, the high functionality by the consumer, and the accessibility by the industry.

• Journal of the Korean Applied Science and Technology
• /
• v.36 no.3
• /
• pp.766-778
• /
• 2019

In this study, Poria cocos bark were extracted by supercritical process, and anti-inflammatory, whitening, and antioxidant effects were measured in comparison with ethanol extract. Also, An effective percutaneous permeation method using a selected formulation of the extract and a drug delivery peptide was proposed. Pachymic acid, known as the anti-cancer and anti-inflammatory compound of the ventricle, is an indicator component and the HPLC analysis shows that the supercritical extract of the pericardium is more than twice that of the Poria cocos bark extract. In order to confirm antioxidative effect of Bombyx mori, DPPH scavenging ability and ABTS scavenging ability test showed that the ethanol extract of Poria cocos Back had lower concentration than the supercritical extract of Poria cocos back. However, RAW 264.7 Measurements of Nitric oxide (NO) production in cells showed lower NO production at the same concentration than the Poria cocos back ethanol extract. In addition, after 72 hours of processing of $20{\mu}g/mL$ of the Poria cocos back extract in B16 melanoma cells, both the intracellular and extracellular melanin extract were effective and the supercritical extract was lower melanin content. No toxicity was observed at the concentration of $800{\mu}g/mL$ in RAW 264.7 cells used in NO production experiments. However, in B16 melanoma cells, even at $50{\mu}g/mL$, both Poria cocos back ethanol extract and supercritical extract showed a survival rate of less than 60%. The liposome formulation and drug delivery peptides were shown to be useful for percutaneous permeation of Supercritical Extract of Poria cocos back using a liposome formulation and a drug delivery peptide. it is expected that there will be great potential for development as a variety of cosmetic materials for Poria cocos back.

• Journal of Life Science
• /
• v.31 no.2
• /
• pp.229-236
• /
• 2021

This study was carried out to evaluate the antioxidant properties of the dried leaves and branches of Stewartia koreana Nakai. The dried leaf and branch of S. koreana were extracted with 70% ethanol at 80℃. The antioxidant activities of ethanol extracts of S. koreana leaf (EESL) and S. koreana branch (EESB) were analyzed. The total polyphenol contents in EESL and EESB were 162.57±0.9 mg of GAEs/extract g and 59.1±0.9 mg of GAEs/extract g, respectively. The flavonoid contents in EESL and EESB were 59.1±0.9 mg of QEs/extract g and 4.7±0.1 mg of QEs/extract g, respectively. EESL showed a better scavenging ability with DPPH and ABTS than EESB, at 0.4 mg/ml. Moreover, EESL were more effective according to ORAC values than EESL. The toxicity of EESL was investigated using a WST-1 assay on the human skin fibroblast cell line CCD-986sk. Therefore, EESL can be used as a potential source of functional, naturally-sourced material in cosmetics as well as food.

• Journal of Life Science
• /
• v.31 no.11
• /
• pp.1010-1018
• /
• 2021

Although varieties of silkworms, which have recently attracted attention as a health functional food, are being produced, studies on the differences in the functionality of different silkworm varieties are insufficient. Therefore, in this study, the antioxidant activities of different silkworm breeds bred in domestic farms were analyzed, and the potential for their cultivation as specialized varieties with excellent antioxidant function was investigated. To compare antioxidant activity, four varieties of silkworms, white Bakokjam, Golden silk, Yeonokjam, and Hanseongjam, were bred; water and ethanol extracts of these silkworms were prepared on the 3rd and 5th days of the 5th instar larval stage. The highest extraction yield was seen for the water extract from the Golden silk variety on the 3rd day of the 5th instar; the highest total phenolic compound and flavonoid contents were observed for the water extract (86.11±4.04 ㎍/mg GE) and 70% (v/v) ethanol extract (46.70±2.81 ㎍/mg QE). Bakokjam and Yeonokjam exhibited DPPH radical scavenging activity of up to 78% and showed the highest nitrite scavenging activity (85%) at pH 1.2. The maximum SOD-like activity of Yeonokjam was about 47%. Furthermore, 48 ㎍/ml of the Yeonokjam extract showed a reducing power of 0.7 abs, which was the best among the four varieties. Considering these results, the Yeonokjam (on the 3rd day of the 5th instar) had antioxidant activity and represents a silkworm cultivar that would be suitable for cultivation as a health food.

• Microbiology and Biotechnology Letters
• /
• v.50 no.3
• /
• pp.337-346
• /
• 2022

The purpose of this study was to investigate the antioxidant and anti-inflammatory activities of hot water (AMPW) and 70% ethanol (AMPE) extracts of apple mango (Mangifera indica L.) peel. The antioxidant activities were measured using a total polyphenol, electron-donating, 2,2'-azinobis [3-ethylbenzothiazoline6-sulfonic acid] (ABTS) radical scavenging assay. The total polyphenol content of AMPW and AMPE was 66.08 ± 0.62 mg TAE/100 g and 100.13 ± 0.23 mg TAE/100 g, respectively. As a result of measuring the electrondonating ability, at a concentration of 1,000 ㎍/ml, AMPW and AMPE showed an effectiveness of 86% and 94%, respectively. The ABTS assay showed 80% and 98% respective radical scavenging activity for AMPW and AMPE, at a concentration of 1,000 ㎍/ml. The cell viability on macrophage cells was performed using a 3-[4,5-dimethyl-thiazol-2-yl]-2,5-diphenyl-tetrazoliumbromide (MTT) assay, and the results showed more than 90% cell viability at a 100 ㎍/ml concentration. Anti-inflammatory activity was verified by confirming nitric oxide (NO) production inhibitory activity, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) protein and mRNA expression inhibitory activity from lipopolysaccharide (LPS)-treated RAW 264.7 cells. The NO production inhibitory effects were measured using the Griess assay, which confirmed 45% and 40% inhibition after treatment with AMPW and AMPE, respectively. Moreover, the protein and mRNA expression of inflammatory-related factors iNOS and COX-2, decreased in a concentrationdependent manner. In conclusion, this study showed antioxidant and anti-inflammatory effects of Mangifera indica L. peel and revealed its promising potential for application as an antioxidant and anti-inflammatory agent.

• The Journal of Korean Academy of Prosthodontics
• /
• v.61 no.4
• /
• pp.257-267
• /
• 2023

Purpose. The purpose of the study was to fabricate a prototype robotic simulator for dental education, to test whether it could simulate mandibular movements, and to assess the possibility of the stimulator responding to stimuli during dental practice. Materials and methods. A virtual simulator model was developed based on segmentation of the hard tissues using cone-beam computed tomography (CBCT) data. The simulator frame was 3D printed using polylactic acid (PLA) material, and dentiforms and silicone face skin were also inserted. Servo actuators were used to control the movements of the simulator, and the simulator's response to dental stimuli was created by pressure and water level sensors. A water level test was performed to determine the specific threshold of the water level sensor. The mandibular movements and mandibular range of motion of the simulator were tested through computer simulation and the actual model. Results. The prototype robotic simulator consisted of an operational unit, an upper body with an electric device, a head with a temporomandibular joint (TMJ) and dentiforms. The TMJ of the simulator was capable of driving two degrees of freedom, implementing rotational and translational movements. In the water level test, the specific threshold of the water level sensor was 10.35 ml. The mandibular range of motion of the simulator was 50 mm in both computer simulation and the actual model. Conclusion. Although further advancements are still required to improve its efficiency and stability, the upper-body prototype simulator has the potential to be useful in dental practice education.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.12 no.4
• /
• pp.287-304
• /
• 2007

This study was carried out to investigate spatio-temporal variations of benthic environment and macrobenthic polychaete communities in Gamak Bay where excessive organic matters from untreated sewage effluents and fish and shellfish farming activities have been accumulated in certain regions. Such environmental variables as sediment composition, organic content, acid volatile sulfide and dissolved oxygen content etc. were measured and polychaete specimens were taken in September 1999 and February 2000. In September 1999, organic contents were up to three times higher in the northwestern part of the bay and the area closed to Gukdong harbor than in the rest of the bay. In particular, benthic environment of the northwestern part of the bay was extremely deteriorated by the occurrence of hypoxia and highly concentrated sulfide. Of 28 stations investigated in summer, 5 stations located in the northwestern part were azoic. In the rest of the stations, a total of 119 polychaete species were sampled with a mean density of 900 $ind./m^2$. While species richness was higher in the entrance and central part of the bay where water exchanges with open sea were relatively active, density was higher in the moderately enriched stations neighbouring Gukdong harbor and fish farms where such potential indicators of organic pollution as Aphelochaeta monilaris, Lumbrineris longifolia were largely dominant. In February 2000, a total of 81 polychaete species appeared with a mean density of 2,802 $ind./m^2$ from 12 stations sampled in winter. Azoic areas were recolonized by Capitella capitata, Pseudopolydora paucibranchiata and Dipolydora socialis which showed maximum density in the innermost station. On the other hand, the rest of the stations were dominated by Euchone alicaudata and Praxillella affinis. The configuration of the stations sampled in summer and winter on the multidimensional scaling plots reflected the position of each stations within the bay in which there were great differences in organic content, sulfide concentration and oxygen content rather than in sediment composition. Therefore, heterogeneities in polychaete community structure in Gamak Bay were primarily influenced by the degree of the disturbance depending on the position within the bay.