• 분석과학
• /
• 제25권1호
• /
• pp.50-59
• /
• 2012

DNPH 카트리지 방식으로 카보닐성분들을 채취할 때, 습도변화에 따른 채취효율의 특성을 체계적으로 진단하였다. 6개의 카보닐성분(formaldehyde (FA), acetaldehyde (AA), propionaldehyde (PA), butyraldehyde (BA), isovaleraldehyde (IA), valeraldehyde (VA))을 함유한 기체상 표준시료를 DNPH카트리지로 흡수 후 용출하여 HPLC/UV 검출기로 분석하였다. 이 결과를 비슷한 수준으로 조제한 액상 혼합표준용액의 검정 결과와 비교하였다. 액상 표준시료와 대비하였을 때, 상대적으로 저분자 성분(폼알데하이드, 아세트알데하이드)에 비해 고분자 성분(프로피온알데하이드 이상)들의 회수율이 낮게 나타났다. 습도변화에 따른 기체상 표준시료의 채취효율을 0-80% 상대습도 범위에서 비교한 결과, 20~80%에서 저분자량과 고분자량 카보닐화합물들 간에 채취효율의 차이가 유지되었다. FA와 AA와 같은 저분자량 카보닐화합물의 경우, 습도의 변화에 대해 미미한 변화를 보였다. 그러나 PA 이상의 성분들은 회수율이 증가하는 경향을 보였다. 이러한 경향은 비교분석을 시도한 3개 제품에서 모두 유사한 경향을 보였으며, 고분자 카보닐화합물의 경우, 습도에 따른 회수율-변화를 적절히 보정할 필요가 있다.

• 한국물환경학회지
• /
• 제23권6호
• /
• pp.843-849
• /
• 2007

Monitoring of NOM characteristics is important for improving removal efficiency of natural organic matter (NOM) in water treatment processes. In this study, several NOM characteristics, which include specific UV absorbance (SUVA), total carbonate content, molecular weight distribution, and fluorescence properties, were measured using samples collected from a pilot-scale water treatment plant consisting of coagulation/flocculation (C/F), filtration, ozonation and granular activated carbon (GAC) processes. The highest removal of NOM was observed in C/F and filtration processes as demonstrated by the reduction of dissolved organic carbon (DOC) by 25% and 21%, respectively. Despite nearly no change in DOC, however, the lowest SUVA value and the highest total carbohydrate content were observed in the sample from ozonation process. This indicates that non-degradable aromatic compounds become depleted and biodegradable organic compounds are enriched during the process. Comparison of synchronous fluorescence spectra of the samples showed that ozoation process increased protein-like fluorescence while it decreased fulvic-like and terrestrial humic-like fluorescence. Consistently, a slight peak of protein-like fluorescence was observed in the sample from ozonation process. The greatest change in molecular weight distributions of the samples was observed in C/F process. Comparison of size exclusion chromatogram of the samples revealed that NOM fractions with the molecular weight greater than 2000 Da were reduced by over 90% after C/F process. SUVA values and total carbohydrate content of the samples were well correlated with a ratio of protein-like fluorescence and terrestrial humic-like fluorescence intensities with the correlation coefficients of 0.99 and 0.91, respectively. This suggests that synchronous fluorescence properties of NOM could be used as useful tolls for monitoring changes of some NOM characteristics during water treatment processes.

• 상하수도학회지
• /
• 제29권1호
• /
• pp.33-38
• /
• 2015

In this study, flat-type photocatalytic reaction system is applied to reduce toxic hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)) in aqueous solution under UV irradiation. To overcome the limitation of conventional photocatalysis, a novel approach toward photocatalytic system for reduction of hexavalent chromium including nanotubular $TiO_2$ (NTT) on two kinds of titanium substrates (foil and mesh) were established. In addition, modified Ti substrates were prepared by bending treatment to increase reaction efficiency of Cr(VI) in the flat-type photocatalytic reactor. For the fabrication of NTT on Ti substrates, Ti foil and mesh was anodized with mixed electrolytes ($NH_4F-H_2O-C_2H_6O_2$) and then annealed in ambient oxygen. The prepared NTT arrays were uniformly grown on two Ti substrates and surface property measurements were performed through SEM and XRD. Hydraulic retention time(HRT) and substrate type were significantly affected the Cr(VI) reduction. Hence, the photocatalytic Cr(VI) reduction was observed to be highest up to 95% at bended(modified) Ti mesh and lowest HRT. Especially, Ti mesh was more effective as NTT substrate in this research.

• 한국수정란이식학회지
• /
• 제27권1호
• /
• pp.37-43
• /
• 2012

This study evaluated a method of sorting X and Y chromosomes based on size using the forward angle light scatter related refractive index (FSC) of a flow cytometer. Hanwoo bulls sperm were separated to X and Y chromosomes by the parameters of FSC or Hoechst 33342 intensity. As a result, using monitor program linked flow cytometry during sorting processing, the purities were $97{\pm}0.57$ or $96{\pm}0.67%$ for the X-fraction and $96{\pm}0.33$ or $97{\pm}1.33%$ for the Y-fraction in the two sperm sorting methods. There were no differences in the X and Y ratios (X and Y %) between the sperm sorting methods based on FSC or DNA content. The proportions of female and male embryos used for in vitro fertilization and development were $66.03{\pm}3.31$ or $69.37{\pm}1.41%$, and $70.56{\pm}2.42$ or $56.11{\pm}3.09%$ when sperm were processed using the sex sorting method by FSC or Hoechst 33342. In conclusion, further study is needed to determine the optimum procedure and improve the nozzle to enhancing sorting accuracy or efficiency. Also, the findings of this study do not negate the possibility that the difference method of sperm sorting cannot use a UV laser beam.

• 한국재료학회지
• /
• 제30권9호
• /
• pp.489-494
• /
• 2020

SiC is a material with excellent strength, heat resistance, and corrosion resistance. It is generally used as a material for SiC invertors, semiconductor susceptors, edge rings, MOCVD susceptors, and mechanical bearings. Recently, SiC single crystals for LED are expected to be a new market application. In addition, SiC is also used as a heating element applied directly to electrical energy. Research in this study has focused on the manufacture of heating elements that can raise the temperature in a short time by irradiating SiC-I₂ with microwaves with polarization difference, instead of applying electric energy directly to increase the convenience and efficiency. In this experiment, Polydimethylsilane (PDMS) with 1,2 wt% of iodine is synthesized under high temperature and pressure using an autoclave. The synthesized Polycarbosilane (PCS) is heat treated in an argon gas atmosphere after curing process. The experimental results obtain resonance peaks using FT-IR and UV-Visible, and the crystal structure is measured by XRD. Also, the heat-generating characteristics are determined in the frequency band of 2.45 GHz after heat treatment in an air atmosphere furnace.

• 대한화학회지
• /
• 제51권6호
• /
• pp.513-519
• /
• 2007

수용액에서 vesicle을 형성하는 고분자, poly(sodium acrylamidoundecanoate)(PSAU)와 수용성 형광다이, TPADSB-C를 합성하고 흡수 및 형광 분광기를 이용하여 광학적 특성을 연구하였다. N-phenyl naphthylamine을 형광 probe로 사용하여 PSAU의 농도가 0.01 g/L 이상에서 고분자들의 응집에 의해 vesicle을 형성함을 확인하였다. 수용성 형광다이의 형광 특성을 vesicle의 존재유무에 따라 조사함으로써 형광다이 주위의 미세환경의 변화에 따른 광학적 특성 의 변화를 측정하였다. 형광다이를 고분자 vesicle안에 침투시킬 경우 형광체 주변의 미세 환경(극성 등)의 변화에 따라 수용액 대비 발광 파장은 blue-shift하였고 형광 효율도 90%로 증가하였다. 본 연구는 형광다이를 함유하고 있는 고분 자 vesicle이 바이오이메징 응용에 있어 효과적이고 안정적이면서 biocompatible한 레이블용 테그로 사용될 수 있음을 보여준다.

• 청정기술
• /
• 제13권3호
• /
• pp.222-227
• /
• 2007

축산폐수처리에 광촉매공정을 적용하였을 때 운전변수 중 자외선 조사거리, 반응면적, 부유고형물(SS)농도, 컬럼직경이 처리율에 미치는 영향을 실험실 규모의 광촉매반응기를 사용하여 실험하였다. 최적운전조건은 자외선 조사거리 3 cm (7 cm 이하 권장), 반응면적 $3.6\;m^2$, SS농도 40 mg/L (300 mg/L이하 권장), 컬럼직경 5 mm (10 mm 이하 권장)로서 COD, 색도, coliform 제거율이 반응시간 300 min에서 각각 49%, 53% 100%로 나타났다. 최적운전조건에서 난분해성 COD의 제거율은 57%로 나타나 광촉매반응이 난분해성 유기물제거에 어느 정도 효과가 있는 것으로 나타났다.

• Corrosion Science and Technology
• /
• 제19권2호
• /
• pp.82-88
• /
• 2020

This work examined the corrosion protection performance of benzoate loaded hydrotalcite/graphene oxide (HT/GO-BZ) for carbon steel. HT/GO-BZ was fabricated by the co-precipitation method and characterized by infrared spectroscopy, X-ray diffraction, and scanning electronic microscopy. The corrosion inhibition action of HT/GO-BZ on carbon steel in 0.1 M NaCl solution was evaluated by electrochemical measurements. The benzoate content in HT/GO-BZ was determined by UV-Vis spectroscopy. Subsequently, the effect of HT/GO-BZ on the corrosion resistance of the water-based epoxy coating was investigated by the salt spray test. The obtained results demonstrated the intercalation of benzoate and GO in the hydrotalcite structure. The benzoate content in HT/GO-BZ was about 16%. The polarization curves of the carbon steel electrode revealed anodic corrosion inhibition activity of HT/GO-BZ and the inhibition efficiency was about 95.2% at a concentration of 3g/L. The GO present in HT/GO-BZ enhanced the inhibition effect of HT-BZ. The presence of HT/GO-BZ improved the corrosion resistance of the waterborne epoxy coating.

• 한국재료학회지
• /
• 제23권1호
• /
• pp.31-34
• /
• 2013

Trivalent cerium-ion-doped $Y_3(Al,\;Ga)_5O_{12}$ nanoparticle phosphor nanoparticles were synthesized using the reverse micelle process. The Ce doped $Y_3(Al,\;Ga)_5O_{12}$ particles were obtained from nitrate solutions dispersed in the nanosized aqueous domains of a micro emulsion consisting of cyclohexane as the oil phase and poly(oxyethylene) nonylphenyl ether (Igepal CO-520) as the non-ionic surfactant. The crystallinity, morphology, and thermal properties of the synthesized $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ powders were characterized by thermogravimetry-differential thermal analysis (TGA-DTA), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and transmission electron microscopy. The crystallinity, morphology, and chemical states of the ions were characterized; the photo-physical properties were studied by taking absorption, excitation, and emission spectra for various concentrations of cerium. The photo physical properties of the synthesized $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ powders were studied by taking the excitation and emission spectra for various concentrations of cerium. The average particle size of the synthesized YAG powders was below $1{\mu}m$. Excitation spectra of the $Y_3Al_5O_{12}$ and $Y_3Al_{3.97}Ga_{1.03}O_{12}$ samples were 485 nm and 475 nm, respectively. The emission spectra of the $Y_3Al_5O_{12}$ and $Y_3Al_{3.97}Ga_{1.03}O_{12}$ were around 560 nm and 545 nm, respectively. $Y_3(Al,\;Ga)_5O_{12}:Ce^{3+}$ is a red-emitting phosphor; it has a high efficiency for operation under near UV excitation, and may be a promising candidate for photonic applications.

• Journal of Pharmaceutical Investigation
• /
• 제40권6호
• /
• pp.357-362
• /
• 2010

To enhance therapeutic effects of insulin-sensitizing adipokine, ADN gene and potent agonists, rosiglitazone for the $PPAR{\gamma}$, cationic liposomes as non-viral vectors were formulated. The particle size and zeta potential of drug loaded and unloaded cationic liposomes were investigated. The complex formation between cationic liposomes and negatively charged plasmid DNA was confirmed and the protection from DNase was observed. In vitro transfection was investigated in HepG2, HeLa, and HEK293 cells by mRNA expression of ADN. Encapsulation efficacy of rosiglitazone-loaded liposomes was determined by UV detection. Particle sizes of cationic liposomes were in the range of 110-170 nm and those of rosiglitazone-loaded cationic liposomes were in the range of 130-180 nm, respectively. Gel retardation of complexes indicated that the complex was formed at weight ratios of cationic lipid to plasmid DNA higher than 20:1. Both complexes protected plasmid DNA from DNase either drug free or drug loading. Encapsulation efficiency of rosiglitazone-loaded emulsion was increased by drug dose. The mRNA expression levels of ADN were dose-dependently increased in cells transfected with plasmid DNA. Therefore, cationic liposomes could be potential co-delivery system for drug and gene.