• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05a
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• pp.35-37
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• 2001

The Al etching was studied employing negative ions generated in the downstream $Cl_2$ plasma. In order to etch the Al film practically on an insulator covered electrode coupled with RF power, reduction of the negative self bias voltage (Vdc) was examined using a magnetic filter which trapped electrons. Addition of $SF_6$ and $H_2$ to a $Cl_2/BCl_3$ mixture reduced significantly Vdc.

• Archives of Pharmacal Research
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• v.19 no.6
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• pp.566-569
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• 1996

A sensitivity method has been developed for the detection and determination of niflmic acid(NA) in human urine. Samples were extracted with diethylether. Flunixin (FN) was added to the sample prior to extraction as an internal standard. Niflumic acid was converted to its methyl derivative and analyzed by capillary gas chromatography/negative chemical isonization mass spectrometry. Using selected ion monitoring (SIM), the levels of NA down to 5 pg/ml could be detected in 5 ml spiked urine sample. Calibration curve was linear over the range of 0.5 ppm-50 ppm. The recovery of niflumic acid from urine at 40 pg/ml was to be $91.7{\pm}3.8(n=3)$ and the coefficient of variation was 4.1%.

• Korean Journal of Veterinary Service
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• v.43 no.1
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• pp.39-44
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• 2020

The aim of this study is to investigate how the gut microbiome shifts when pigs were exposed with low concentrations of mycotoxins, deoxynivalenol (DON) and zearalenone (ZEN) in feed. Fifteen of pigs, 15 kg in weight which were negative for PRRSV and PCV2 were purchased, acclimatized until 20 kg in weight, and randomly divided into 3 groups; the DON group (DON treated), the ZEN group (ZEN treated) and the CTL (untreated negative control). DON and ZEN administered to each group for 30 days at 0.8 mg/kg (800 ppb) and 0.20 mg/kg (200 ppb) in feed, respectively. After extraction of microbial DNA from intestine and fecal samples, sequencing procedures were performed in the Ion PGM using an Ion 316 V2 chip and Ion PGM sequencing 400 kit. The results suggested that the bacterial communities in duodenum, jejunum and ileum of the DON and ZEN groups presented low-abundant OTUs compared with the CTL group. OTUs in cecum, colon and feces were determined more than in small intestine of all three groups. However, the CTL group yielded more OTUs than other two groups in inter-group comparison. It is not fully clarified how the richness and abundance in microbiome functions in the health condition of animals, however, the exposure to DON and ZEN has caused microbial population shifts representing microbial succession and changes following the diversity and abundance of porcine gut microbiome. The metabolomic analysis correlate with microbiome analysis is needed for further study.

• Biomolecules & Therapeutics
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• v.21 no.6
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• pp.470-475
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• 2013

Ultraviolet (UV) radiation is a major environmental factor that leads to acute and chronic reactions in the human skin. UV exposure induces wrinkle formation, DNA damage, and generation of reactive oxygen species (ROS). Most mechanistic studies of skin physiology and pharmacology related with UV-irradiated skin have focused on proteins and their related gene expression or single-targeted small molecules. The present study identified and analyzed the alteration of skin metabolites following UVB irradiation and topical retinyl palmitate (RP, 5%) treatment in hairless mice using direct analysis in real time (DART) time-of-flight mass spectrometry (TOF-MS) with multivariate analysis. Under the negative ion mode, the DART ion source successfully ionized various fatty acids including palmitoleic and linolenic acid. From DART-TOF-MS fingerprints measured in positive mode, the prominent dehydrated ion peak (m/z: 369, M+H-$H_2O$) of cholesterol was characterized in all three groups. In positive mode, the discrimination among three groups was much clearer than that in negative mode by using multivariate analysis of orthogonal partial-least squares-discriminant analysis (OPLS-DA). DART-TOF-MS can ionize various small organic molecules in living tissues and is an efficient alternative analytical tool for acquiring full chemical fingerprints from living tissues without requiring sample preparation. DART-MS measurement of skin tissue with multivariate analysis proved to be a powerful method to discriminate between experimental groups and to find biomarkers for various experiment models in skin dermatological research.

• Journal of Electrochemical Science and Technology
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• v.7 no.4
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• pp.306-315
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• 2016

Amorphous vanadium titanates (aVTOs) are examined for use as a negative electrode in lithium-ion batteries. These amorphous mixed oxides are synthesized in nanosized particles (<100 nm) and flocculated to form secondary particles. The $V^{5+}$ ions in aVTO are found to occupy tetrahedral sites, whereas the $Ti^{4+}$ ions show fivefold coordination. Both are uniformly dispersed at the atomic scale in the amorphous oxide matrix, which has abundant structural defects. The first reversible capacity of an aVTO electrode ($295mAhg^{-1}$) is larger than that observed for a physically mixed electrode (1:2 $aV_2O_5$ | $aTiO_2$, $245mAhg^{-1}$). The discrepancy seems to be due to the unique four-coordinated $V^{5+}$ ions in aVTO, which either are more electron-accepting or generate more structural defects that serve as $Li^+$ storage sites. Coin-type Li/aVTO cells show a large irreversible capacity in the first cycle. When they are prepared under nitrogen (aVTO-N), the population of surface hydroxyl groups is greatly reduced. These groups irreversibly produce highly resistive inorganic compounds (LiOH and $Li_2O$), leading to increased irreversible capacity and electrode resistance. As a result, the material prepared under nitrogen shows higher Coulombic efficiency and rate capability.

• Journal of Plant Biology
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• v.37 no.4
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• pp.441-444
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• 1994

From immature seed of Phaseolus vulgaris L., a novel phytosteryl glucoside was isolated. Strong ion peaks at m/z 613 $[M+Na}^{+},\;696\;[M+Matrix]^{+}$ in positive F AB- MS and at m/z 589 $[M-1]^{-}$ in negative F AB- MS indicated the molecular weight of the compound is 590. Four hundred MHz $^IH-NMR$ analysis revealed that the compound canys a 24-hydroxy-24-vinyl-cholesterol (saringosterol) as an aglycone and a ${\beta}-D-glucopyranose$. Four hundred MHz $^IH-NMR$ analysis of the acetate derivate of the compound revealed that hydroxyls at C-1' in glucose moeity and at C-3 in aglycone have been condensed. Therefore, the phytosteryl glucoside was characterized to be $3-0-{\beta}-D-glucopyranosyl-24-hydroxy-24-vinyl-cholesterol$ (saringosteryl glucoside). This is the first demonstration for the presence of saringosterol in higher plants. Also this is the first identification of saringosteryl glucoside in natural materials.erials.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.843-846
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• 1992

This thesis was investigated on optical-and ion-induced characteristics in positive(a-$Se_{75}Ge_{25}$) and negative (Ag/a-$Se_{75}Ge_{25}$) resists for focused-ion-beam microlithogaphy. The a-$Se_{75}Ge_{25}$ inorganic thin film shows an increase in optical absorption after exposure to$\sim$$10^{16}$ dose(ions/$cm^{2}$) of Ga ions. The observed shift in the absorption edge toward longer wavelengths is consistent with that in films exposed to band-gap photons ($\sim$$10^{20}$ photons/$cm^{2}$). But, ion induced shift is twice as much as that in film exposed to optical radiation. This result may be related with microstructural rearrangements with in the short range of SeGe network. Due to changes in the short range order, the chemical bonding may be affected, which results in increased chemical dissolution in ion-induced film. Also, this resist exhibits good thermal stability because of its high Tg(~220$^{\circ}C$). The composition of deposited film measured by AES is consistent with that of bulk.

• Analytical Science and Technology
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• v.9 no.2
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• pp.161-167
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• 1996

An investigation was made of possible ways in which one could control the relative rates of cadmium deposition and hydrogen evolution by binary additive systems. Benzyl alcohol was employed as an additives due to its ability to form a hydrophobic film which inhibit the electroreduction of water to form hydrogen. The second additive was chosen to make the cadmium(II) ion less hydrophilic and increase its ability to cross the hydrophobic benzyl alcohol film and be electrodeposited at the cathode. It was shown by voltammetric and current efficiency studies that ion pairing and complexing additives could be used to accelerate the reduction of cadmium in the presence of the benzyl alcohol film. It was also shown that the benzyl alcohol film lowered the dielectric constant of the solution near the electrode enough to obtain ion pairing between the sodium ion and the negative chloride complex of cadmium and accelerate the reduction of the cadmium. This acceleration did not occur in the sulfate solution in the absence of chloride since cadmium(II) is primarily present as a positive aquo complex and ion pairing, if it occured, would not accelerate but would hinder reduction of cadmium.

• Nuclear Engineering and Technology
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• v.21 no.1
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• pp.40-47
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• 1989

For the effective design of a beam forming structure of the negative-ion-based neutral beam injector, a computer program based on a particle simulation model is developed for the calculation of charged particle motions in the electrostatic fields. The motions of negative ions inside the acceleration tube of a multiple-aperture triode are computed at finite time steps. The electrostatic potentials are obtained from the Poisson's equation by the finite difference method. The successive overrelaxation method is used to solve the matrix equation. The particle and force weighting methods are used on a cloud-in-cell model. The optimum design of the beam forming structure has been studied by using this computer code for the various conditions of elctrodes. The effects of the acceleration-deceleration gap distance, the thickness of the deceleration electrode and the shape of the acceleration electrode on beam trajectories are exmined to find the minimum beam divergence. Some numerical illustrations are presented for the particle movements at finite time steps in the beam forming tubes. It is found in this particle simulation modelling that the shape of the acceleration electrode is the most significant factor of beam divergence.

• Journal of Astronomy and Space Sciences
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• v.22 no.2
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• pp.147-174
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• 2005

To understand the physical processes that control the high-latitude lower thermospheric dynamics, we quantify the forces that are mainly responsible for maintaining the high-latitude lower thermospheric wind system with the aid of the National Center for Atmospheric Research Thermosphere-Ionosphere Electrodynamics General Circulation Model (NCAR-TIEGCM). Momentum forcing is statistically analyzed in magnetic coordinates, and its behavior with respect to the magnitude and orientation of the interplanetary magnetic field (IMF) is further examined. By subtracting the values with zero IMF from those with non-zero IMF, we obtained the difference winds and forces in the high-latitude 1ower thermosphere(<180 km). They show a simple structure over the polar cap and auroral regions for positive($B_y$ > 0.8|$\overline{B}_z$ |) or negative($B_y$ < -0.8|$\overline{B}_z$|) IMF-$\overline{B}_y$ conditions, with maximum values appearing around -80$^{\circ}$ magnetic latitude. Difference winds and difference forces for negative and positive $\overline{B}_y$ have an opposite sign and similar strength each other. For positive($B_z$ > 0.3125|$\overline{B}_y$|) or negative($B_z$ < -0.3125|$\overline{B}_y$|) IMF-$\overline{B}_z$ conditions the difference winds and difference forces are noted to subauroral latitudes. Difference winds and difference forces for negative $\overline{B}_z$ have an opposite sign to positive $\overline{B}_z$ condition. Those for negative $\overline{B}_z$ are stronger than those for positive indicating that negative $\overline{B}_z$ has a stronger effect on the winds and momentum forces than does positive $\overline{B}_z$ At higher altitudes(>125 km) the primary forces that determine the variations of tile neutral winds are the pressure gradient, Coriolis and rotational Pedersen ion drag forces; however, at various locations and times significant contributions can be made by the horizontal advection force. On the other hand, at lower altitudes(108-125 km) the pressure gradient, Coriolis and non-rotational Hall ion drag forces determine the variations of the neutral winds. At lower altitudes(<108 km) it tends to generate a geostrophic motion with the balance between the pressure gradient and Coriolis forces. The northward component of IMF By-dependent average momentum forces act more significantly on the neutral motion except for the ion drag. At lower altitudes(108-425 km) for negative IMF-$\overline{B}_y$ condition the ion drag force tends to generate a warm clockwise circulation with downward vertical motion associated with the adiabatic compress heating in the polar cap region. For positive IMF-$\overline{B}_y$ condition it tends to generate a cold anticlockwise circulation with upward vertical motion associated with the adiabatic expansion cooling in the polar cap region. For negative IMF-$\overline{B}_z$ the ion drag force tends to generate a cold anticlockwise circulation with upward vertical motion in the dawn sector. For positive IMF-$\overline{B}_z$ it tends to generate a warm clockwise circulation with downward vertical motion in the dawn sector.