• 대한의용생체공학회:의공학회지
• /
• 제34권3호
• /
• pp.117-122
• /
• 2013

Hyaluronic acid(HA) microbeads were synthesized by dropping the sodium hyaluronate(Streptococcus) solutions in NaOH into a solution mixture of divinyl sulfone(DVS) in 2-methyl-1-propanol, followed by stirring, cleaning and drying process at room temperature. The initial experimental conditions are crosslinking time(CLTi) of 5 h, crosslinking temperature(CLTe) of room temperature, injection air pressure(IAPr) of 5 psi, and DVS concentration( DVSc) of 0.2 vol%, respectively. Then, parametric studies were performed by varying the parameters to investigate the morphology, the porosity, the swelling ratio and the size of the beads. The microbead size pattern was not regular to function of the degree of crosslink. It was observed that the swelling ratio, the degree of crosslink, and the pore size can be controlled by adjusting the CLTi, CLTe and DVSc. Among the parameters investigated, the smallest bead size can be achieved by varying the CLTi parameter. The lowest swelling ratio, as an indication of the highest degree of crosslink, can be obtained by varying CLTe.

• 한국염색가공학회지
• /
• 제10권1호
• /
• pp.11-19
• /
• 1998

For the purpose of standardization and practicability of dyeing by natural dyes, the mordanting and dyeing properties of cochineal and carminic acid were studied. Appropriate extraction, dyeing and mordanting condition of cochineal were determined, and the effect of mordanting method on dye uptake and color fastness of dyed fabric was investigated. The maximum absorbance of cochineal solution was 495nm, carminic acid was 533nm and 577nm. The color of carminic acid solution was affected by pH 6~9. The optimum temperature to extract cochineal was $80-100^\circ{C}$ and dyeing solution for 1 hour. And effective dyeing time to silk was 60min. Effective mordanting temperature was $80^\circ{C}$, and its time was 30min. In case mordants concentration, the maximum absorbance of Sn solution was 3%, K, Cu and Cr were in 1%. K/S value of dyeing fabrics was recoginazed by mordant treatment, specially Fe, Sn, Al, Cu. In the case of cochineal light fastness was increased by mordant treatment, specially Fe treatment. Perspiration fastness was good in acidic solution than in alkaline solution and perspiration fastness of cochineal was poor. Fastness of abrasion and dry-cleaning were good and these fastness improvement were generally effective for post-mordanting treatment.

• Membrane and Water Treatment
• /
• 제3권1호
• /
• pp.35-49
• /
• 2012

In membrane processes, various agents are used to enhance, protect, and recover membrane performance. Applying these agents in membrane modification could potentially be considered as a simple method to improve membrane performance without additional process. Citric acid (CI) and sodium bisulfite (SB) are two chemicals that are widely used in membrane feed water pretreatment and cleaning processes. In this work, preadsorptions of CI and SB were developed as simple methods for polysulfone ultrafiltration membrane modification. It was found that hydrogen bonding and Van Der Waals attraction could be responsible for the adsorptions of CI and SB onto membranes, respectively. After modification with CI or SB, the membrane surfaces became more hydrophilic. Membrane permeability improved when modified by SB while decreased a little when modified by CI. The modified membranes had an increase in PEG and BSA rejections and better antifouling properties with higher flux recovery ratios during filtration of a complex pharmaceutical wastewater. Moreover, membrane chlorine tolerance was elevated after modification with either agent, as shown by the mechanical property measurements.

• 한국식품영양학회지
• /
• 제35권2호
• /
• pp.88-95
• /
• 2022

The antioxidant effects by pre-treatment of Hutgae fruit water and ethanol (30°, Soju) extract on refrigerated eels were analyzed. The antioxidant activities were measured through DPPH and ABTS scavenging effect, values of acidity, peroxide, carbonyl, and TBA. The peroxide prevention effects of linoleic acid and eel oil were also assessed. Regarding DPPH radical scavenging, Hutgae ethanol extract presented higher scavenging effects than vitamin C 5 mM solution (p<0.05). The eel's peroxidation degree was measured through 21 days of refrigeration after cleaning and immersion into the extract solution for one hour. Upon measuring the values of four different peroxide indicators, those of eels pre-treated with Hutgae extracts were lower than those of eels untreated. The POV of Hutgae ethanol extract, vitamin C 5 mM, and the control was 11.1, 11.3, 15.5 meq/kg, respectively. Hutgae ethanol extract showed higher antioxidant activities in TBA value, and carbonyl value than other samples. In linoleic acid or eel oil, Hutgae extract was as superiorly effective in preventing peroxide generation of refrigerated eels as vitamin C 10 mM solution. In conclusion, pre-application of Hutgae water and ethanol (30°, Soju) extract on eels was proved to be competent in stopping peroxidation of eel in refrigeration.

• Journal of Periodontal and Implant Science
• /
• 제31권4호
• /
• pp.749-763
• /
• 2001

Osseointegrated titanium implants have become an integral therapy for the replacement of teeth lost. For dental implant materials, titanium, hydroxyapatite and alumina oxide have been used, which of them, titanium implants are in wide use today. Titanium is known for its high corrosion resistance and biocompatability, because of the high stability of oxide layer mainly consists of $TiO_2$. With the development of peri-implantitis, the implant surface is changed in surface topography and element composition. None of the treatments for cleaning and detoxification of implant surface is efficient to remove surface contamination from contaminated titanium implants to such extent that the original surface elemental composition. In this sights, the purpose of this study was to evaluate rough surface titanium implants by means of scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS) with respect to surface appearance and surface elemental composition. Moreover, it was also the aim to get the base for treatments of peri-implantitis. For the SEM and XPS study, rough surface titanium models were fabricated for control group. Six experimental groups were evaluated: 1) long-time room exposure, 2 ) air-powder abrasive cleaning for 1min, 3) burnishing in citric acid(pH1) for 1min, 4) burnishing in citric acid for 3min, 5) burnishing in tetracycline for 1min, 6) burnishing in tetracycline for 3min. All experimental treatments were followed by 1min of rinsing with distilled water. The results were as follows: 1. SEM observations of all experimental groups showed that any changes in surface topography were not detected when compared with control group. (750 X magnification) 2. XPS analysis showed that in all experimental groups, titanium and oxygen were increased and carbon was decreased, when compared with control group. 3. XPS analysis showed that the level of titanium, oxygen and carbon in the experimental group 3(citric acid treatment for 1min, followed by 1min of distilled water irrigation) reached to the level of control group. 4. XPS analysis showed that significant differences were not detected between the experimental group 1 and the other experimental groups except of experimental group 3. The Ti. level of experimental group 2, airpowder abrasive treatment for lmin followed by 1min of saline irrigation, was lower than the Ti. level of tetracycline treated groups, experimental group 5 and 6. From the result of this study, it may be concluded that the 1min of citric acid treatment followed by same time of rinsing with distilled water gave the best results from elemental points of view, and can be used safely to treat peri-implantitis.

• 멤브레인
• /
• 제24권3호
• /
• pp.201-212
• /
• 2014

본 연구는 국내 최초로 도입된 Y 정수장의 세라믹막 고도정수처리를 위한 최적 운영 인자를 도출하기 위하여 수행되었다. 경제성과 수질조건을 만족하면서도 세라믹막 여과성능을 지속 유지할 수 있는 최적 운영조건을 도출한 결과, Y 정수장의 평상시 수질 조건에서 막역세척으로 인한 배출수 발생량을 최소화시키면서도 막여과성능을 유지할 수 있는 최적 여과지속시간(역세척 주기)은 시설용량($16,000m^3$/일) 기준 시 4.0시간으로 조사되었다. 또한 화학세척(CIP)에 따른 막차압 회복력을 조사한 결과, 구연산을 이용한 산세정을 통하여 철, 망간, 알루미늄 등의 막 파울링을 일으키는 무기오염물질은 제거되지만 막회복률은 낮았다. 반면 차아염소산나트륨을 사용한 알칼리 세정을 통해서는 막 운영 초기 막차압으로 회복되는 것으로 나타났다. 막차압을 발생시키는 파울링 주요 원인물질은 친수성 고분자 유기오염물인 polysaccharides로 조사되었으며, 화학세척(CIP)시 막성능 회복률은 세척약품 온도에 의한 영향이 매우 크며, 온도가 높은수록 막성능 회복률이 향상되는 것으로 조사되었다.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
• /
• pp.143-144
• /
• 2002

A series of alcohols with perfluorinated segments $F(CF_2)_m(CH_2)_n-OH$, with m=8, 10 and n=4, 6, 10, were synthesized. First, the alcohols were reacted with fatty acid to produce several esters $(F(CF_2)_m(CH_2)-OOC-R$ with m=8, 10 and n=2, 4, 8,) containing perfluoro group by condensation reaction, and characterized by FT-IR, GC, and surface tension. The esters were soluble in ethyl ether, toluene, hexane, ethyl acetate, chloroform, and acetone, but insoluble in methyl alcohol, ethyl alcohol and isopropyl alcohol. Preliminary experiments on 1,2-dichloroethane solutions showed a remarkable decrease of surface tension upon addition of the esters. Also, the esters films ranged from 100 to $122^{\circ}$, depending on the structure of fatty acid esters. As the separate experiment, the water-repellency of coated paper and cotton was evaluated. As a result, the water droplet dropped in surface was not permeated for two weeks.

• Natural Product Sciences
• /
• 제10권1호
• /
• pp.16-19
• /
• 2004

Triphala churna is a widely used herbal formulation that contains equal proportion of dried fruit powder of Emblica officinalis, Terminalia chebula and Terminalia belirica. In the Indian system of medicine, it is used in cleaning wounds, urinary disorders, diabetes mellitus, leprosy, constipation, eyesight promotion, piles, and as a rejuvenator. In the present study, the methanolic extract of 5 commercial Triphala was evaluated for antioxidant activity by 1,1-diphenyl-2-picryl-hydrazyl free radical scavenging method, total phenolic content by Folin-Ciocalteu method and gallic acid equivalents (GAE) by high performance thin layer chromatographic (HPTLC) method. All extracts exhibited antioxidant activity significantly. The $IC_{50}$ of the extracts ranged between $7.16\;to\;12.96\;{\mu}g/ml$. The total phenolic content of the extracts was found to be 195.3-296.4 mg of GAE/gm of GAE/gm dw. The HPTLC chromatographic data reveal that the content of GAE present in the extract was found to be $7.17-4.11\;{\mu}g/ml$. The study reveals that out of the churnas analysed, C was found to exhibit the most potent antioxidant activity. A clear correlation between $IC_{50}$ and content of GAE nor the total phenolic content could be observed. The study reveals that the consumption of Triphala would exert several beneficial effects by virtue of its antioxidant activity.

• 한국대기환경학회지
• /
• 제22권4호
• /
• pp.431-439
• /
• 2006

Catalytic oxidation of benzene, toluene and xylene (BTX) using regenerated metal oxide catalysts (ZnO-CuO, NiO, $Fe_2O_3$, ZnO, CrO) were investigated in a fixed bed flow reactor to evaluate their feasibility for the purpose of removing volatile organic compounds (VOCs). Four kinds of pre-treatment methods such as gas (air and hydrogen), acid aqueous solution, alkali aqueous solution and cleaning agent were used to find out the optimal regeneration conditions. The physico-chemical properties of the used and regenerated catalysts were characterized by BET and TPR (Temperature Programmed Reduction). The used catalysts showed high conversion ratio and the catalytic ability of toluene oxidation was in the order of ZnO-CuO>$Fe_2O_3$>NiO>ZnO>CrO. We found that the acid aqueous pre-treatment (0.1 N HNO$_3$) was the best way to enhance the catalytic activity of $Fe_2O_3$. In addition, air and hydrogen gas treatment were optimal for NiO and ZnO-CuO catalysts, respectively. Furthermore, the decomposition of BTX depends on the type of a catalyst and a gas molecule.

• 한국응용과학기술학회지
• /
• 제35권3호
• /
• pp.876-885
• /
• 2018

폐 RHDM(Residue Hydrodemetallation) 촉매상에 침적된 비활성화 성분인 탄소, 황 을 고온배소 처리하여 제거한 후, 과량 침적되어 있는 바나듐은 초음파 교반기에서 5~15wt% 옥살산 수용액을 이용하여 $50^{\circ}C$, 5분 조건하에 바나듐 추출량을 조절함으로써 NOx 저감을 위한SCR(Selective Catalytic Reduction) 촉매로의 적용 가능성을 확인하고자 하였다. 폐촉매와 단계별 처리된 RHDM 촉매를 대상으로 상압반응기상에서 NOx 저감 효율을 측정하였고, 촉매의 성분분석은 ICP, C & S analyzer 및 XRF를 이용하여 분석하였다. 10wt% 옥살산 수용액으로 바나듐을 침출한 촉매가 가장 안정적이었으며 높은 NOx 저감 효율을 보였다. 이를 메탈폼 형태의 지지체에 워시코팅한 촉매는 상용 SCR 촉매와 동등 수준의 NOx 저감 효율을 나타내었다. 따라서 폐 RHDM 촉매의 처리 조건 조정에 관한 후속 연구를 통하여 각 적용처에 적합한 SCR 촉매로의 이용 가능성은 충분할 것으로 사료된다.