• KSBB Journal
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• v.13 no.5
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• pp.577-584
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• 1998

A sensitive membrane strip assay for plasma lipoprotein cholesterol that can be performed without handling reagents has been investigated. We previously developed an assay system with immobilized enzymes (cholesterol esterase and cholesterol oxidase) on the surfaces of nitrocellulose membrane(1). In such a case, the amount of enzymes present on the membrane was limited by its surface area and, thus, the detection capability was relatively poor (> 50 mg/dL cholesterol). To overcome this problem, we devised a new system with non-immobilized enzymes by placing them within interstitial spaces of a celullose membrane pad in a dry state. Upon contact with sample medium, the enzymes were immediately dissolved and participated in the reactions with cholesterol in a liquid phase. We constructed a user-friendly system consisting of four membrane pads fro sample application, cholesterol decomposition, color development as signal, and medium absorption to invoke a continuous flow (sequential location from the bottom). A sample containing lipoproteins was added into the application pad by capillary action and transferred to the next pad for decomposition. The decomposition pad (namely, enzyme pad) contained a detergent (sodium cholate) for the destruction of lipoprotein particles, the two enzymes for cholesterol decomposition, and a chromogen (3,3'-diaminobenzidine). As a consequence of the enzyme reactions, hydrogen peroxide was produced, and then reacted in the presence of the chromogen with horseradish peroxidase immobilized on the signal generation pad. Finally, a colorimetric signal directly proportional to the cholesterol concentration was produced. The detection limit determined from this system under optimal conditions was at least 2 times lower than of the enzyme-immobilized system.

• Journal of the Korean Vacuum Society
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• v.10 no.2
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• pp.182-188
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• 2001

Thin films of $SiO_xC_y$ deposited by means of PECVD(plasma enhanced chemical vapor deposition) using HMDSO(hexamethyldisiloxane)/$O_2$ were characterized. The effects of deposition conditions such as RF power, oxygen flow rate and hydrogen flow rate on the chemical bond structure, atomic composition, surface roughness and wear characteristics of the films were investigated by means of FTIR, XPS, AFM and Hazemeter. The deposition rate of $SiO_xC_y$ was greater than 100 nm/min, which is relatively high rate. The XPS results showed that the carbon content in a deposited film was lower than that of previous studies where different organosilicone materials were used. The optimum wear resistance was attained when RF power was 200 Watt and oxygen flow rate was 100 sccm. This study implies that the $HMDSO/O_2$ system is effective in forming a film with a lower carbon content and good abrasion resistance.

• Journal of Korean Ophthalmic Optics Society
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• v.9 no.2
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• pp.291-299
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• 2004

DLC films were deposited using the ECR-PECVD method with the fixed deposition condition, such as ECR power, methane and hydrogen gas-flow rates and deposition time, for various substrate bias voltage. We have investigated the ion bombardment effect induced by the substrate bias voltage on films during the deposition of film. The characteristic of the films were analyzed using the FTIR, Raman, and UV/Vis spectroscopy analysis shows that the amount of dehydrogenation in films was increased with the increase of substrate bias voltage and films thickness was decreased. Raman scattering analysis shows that integrated intensity ratio(ID/IG) of the D and G peak was increased as the substrate bias voltage increased and films hardness was increased. Optical transmittances of DLC film were decreased with increasing deposition time and substrate bias voltage. From these results, it can be concluded that films deposited at this experimental have the enhanced characteristics of DLC because of the ion bombardment effect on films during the deposition of film.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.7
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• pp.39-44
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• 2005

A great part of flint fuel is Hydrogen and carbon's combination, they should be generated steam and carbon gas when combine with oxygen for perfect combustion in the inside of engine but, the pollutive material are discharged, even though perfect combustion condition especially $NO_x$ and Smoke. they are really harmful for health. In this paper was shown the result of discharging gas' reduction quality. which used combination of corona discharge using the high voltage source of common frequency with EGR. $NO_x$ is increased in entire load erea in proportion to increasing of EGR rate and impression voltage. Smoke is increased slowly under 75[%] in load rate but it is increased rapidly in entire load erea and the reduction rate of Smoke is increased in proportion to increasing of impression voltage.

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.659-665
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• 2016

The oligosaccharides in human milk constitute a major innate immunological mechanism by which breastfed infants gain protection against infectious diarrhea. Clostridium difficile is the most important cause of nosocomial diarrhea, and the C-terminus of toxin A with its carbohydrate binding site, TcdA-f2, demonstrates specific abolishment of cytotoxicity and receptor binding activity upon diethylpyrocarbonate modification of the histidine residues in TcdA. TcdA-f2 was cloned and expressed in E. coli BL21 (DE3). A human milk oligosaccharide (HMO) mixture displayed binding with TcdA-f2 at 38.2 respond units (RU) at the concentration of 20 μg/ml, whereas the eight purified HMOs showed binding with the carbohydrate binding site of TcdA-f2 at 3.3 to 14 RU depending on their structures via a surface plasma resonance biosensor. Among them, Lacto-N-fucopentaose V (LNFPV) and Lacto-N-neohexaose (LNnH) demonstrated tight binding to TcdA-f2 with docking energy of −9.48 kcal/mol and −12.81 kcal/mol, respectively. It displayed numerous hydrogen bonding and hydrophobic interactions with amino acid residues of TcdA-f2.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3817-3824
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• 2013

Various separation modes in HPLC, such as anion exchange (AE), reversed-phase (RP), and affinity (AF) chromatography were examined for the separation of selenium species in human blood serum and urine. While RP- and AE-HPLC were mainly used for the separation of small molecular selenium species, double column AF-HPLC achieved the separation of selenoproteins in blood serum efficiently. Further, the effluent of AF-HPLC was enzymatically hydrolyzed and then analyzed with RP HPLC for selenoamino acid study. The versatility of the hybrid technique makes the in-depth study of selenium species possible. For quantification, post column isotope dilution (ID) with $^{78}Se$ spike was performed. ORC ICP/MS (octapole reaction cell inductively coupled plasma/mass spectrometry) was used with 4 mL $min^{-1}$ Hydrogen as reaction gas. In urine sample, inorganic selenium and SeCys were identified. In blood serum, selenoproteins GPx, SelP and SeAlb were detected and quantified. The concentration for GPx, SelP and SeAlb was $22.8{\pm}3.4\;ng\;g^{-1}$, $45.2{\pm}1.7\;ng\;g^{-1}$, and $16.1{\pm}2.2\;ng\;g^{-1}$, respectively when $^{80}Se/^{78}Se$ was used. The sum of these selenoproteins ($84.1{\pm}4.4\;ng\;g^{-1}$) agrees well with the total selenium concentration measured with the ID method of $87.0{\pm}3.0\;ng\;g^{-1}$. Enzymatic hydrolysis of each selenium proteins revealed that SeCys is the major amino acid for all three proteins and SeMet is contained in SeAlb only.

• Preventive Nutrition and Food Science
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• v.21 no.4
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• pp.378-383
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• 2016

Diabetic kidney disease is the most common and severe chronic complication of diabetes. The leaf of Diospyros kaki Thumb (persimmon) has been commonly used for herbal tea and medicinal purposes to treat a variety of conditions, including hypertension and atherosclerosis. However, the effect of persimmon leaf on kidney failure has not been investigated. This study aimed to examine the role of persimmon leaf in protecting the diabetes-associated kidney damage in a mouse model of type 2 diabetes. Mice were fed either a normal chow diet with or without powered persimmon leaf (5%, w/w) for 5 weeks. In addition to kidney morphology and blood markers of kidney function, we assessed levels of oxidative stress markers as well as antioxidant enzymes activities and mRNA expression in the kidney. Supplementation of the diet with powered persimmon leaf not only decreased the concentration of blood urea nitrogen in the plasma but also improved glomerular hypertrophy. Furthermore, the persimmon leaf significantly decreased the levels of hydrogen peroxide and lipid peroxide in the kidney. The activities of superoxide dismutase, catalase, and glutathione peroxidase and the mRNA expression of their respective genes were also increased in the kidney of persimmon leaf-supplemented db/db mice. Taken together, these results suggest that supplementation with the persimmon leaf may have protective effects against type 2 diabetes-induced kidney dysfunction and oxidative stress.

• Journal of the Korean Vacuum Society
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• v.19 no.1
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• pp.58-65
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• 2010

AlN thin films were deposited on sapphire substrates and ZnO templates by rf-magnetron sputtering. Powder-sintered AlN target was adopted for source material. Thickness of AlN layer was linearly dependent on plasma power from 50 to 110 W, and it decreased slightly when working pressure increased from 3 to 10 mTorr due to short mean free path of source material sputtered from AlN target by Ar working gas. When $N_2$ gas was mixed with Ar, the thickness of AlN layer decreased significantly because of low sputter yield of nitrogen. AlN layer was also deposited on ZnO template. However, it showed weak thermal stability that the interface between AlN and ZnO was deteriorated by rapid thermal annealing treatment above $700^{\circ}C$. In addition, ZnO layer was largely attacked by MOCVD ambient gas of hydrogen and ammonia around $700^{\circ}C$ through inferior AlN layer deposited by sputtering. And AlN layers were fully peeled off above $900^{\circ}C$.

• Korean Journal of Materials Research
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• v.26 no.1
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• pp.47-53
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• 2016

Silicon nitride ($SiN_x:H$) films made by plasma enhanced chemical vapor deposition (PECVD) are generally used as antireflection layers and passivation layers on solar cells. In this study, we investigated the properties of silicon nitride ($SiN_x:H$) films made by PECVD. The passivation properties of $SiN_x:H$ are focused on by making the antireflection properties identical. To make equivalent optical properties of silicon nitride films, the refractive index and thickness of the films are fixed at 2.0 and 90 nm, respectively. This limit makes it easier to evaluate silicon nitride film as a passivation layer in realistic application situations. Next, the effects of the mixture ratio of the process gases with silane ($SiH_4$) and ammonia ($NH_3$) on the passivation qualities of silicon nitride film are evaluated. The absorption coefficient of each film was evaluated by spectrometric ellipsometry, the minority carrier lifetimes were evaluated by quasi-steady-state photo-conductance (QSSPC) measurement. The optical properties were obtained using a UV-visible spectrophotometer. The interface properties were determined by capacitance-voltage (C-V) measurement and the film components were identified by Fourier transform infrared spectroscopy (FT-IR) and Rutherford backscattering spectroscopy detection (RBS) - elastic recoil detection (ERD). In hydrogen passivation, gas ratios of 1:1 and 1:3 show the best surface passivation property among the samples.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.83-87
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• 2002

Plasma enhanced chemical vapor deposited (PECVD) silicon nitride ($SiN_X$) is widely used as a gate dielectric material for the hydrogenated amorphous silicon(a-Si:H) thin film transistors (TFT's). We investigated $SiN_X$ films were deposited PECVD at low temperature ($300^{\circ}C$). The reaction gases were used pure nitrogen and a helium diluted of silane gas(20% $SiH_4$, 80% He). Experimental investigations were carried out with the variation of $N_2/SiH_4$ flow ratios from 3 to 50 and the rf power of 200 W. This article presents the $SiN_X$ gate dielectric studies in terms of deposition rate, hydrogen content, etch rate and C-V, leakage current density characteristics for the gate dielectric layer of thin film transistor applications. Electrical properties were analyzed through high frequency (1MHz) C-V and current-voltage (I-V) measurements. The thickness and the refractive index on the films were measured by ellipsometry and chemical bonds were determined by using an FT-IR equipment.