• Journal of the Korean Ceramic Society
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• v.43 no.10 s.293
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• pp.666-672
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• 2006

GDC20($Ce_{0.8}Gd_{0.2}O_{1.9}$) powder was synthesized by oxalate co-precipitation and milling and its thermal decomposition, phase formation, and sinterability were investigated. As-prepared precipitates were non-crystalline due to the milling process and completely decomposed at 400$^{\circ}C$ The powder calcined at 800$^{\circ}C$ for 2 h contained fine p]sty particles with an average size of 0.69 $\mu$m. Attrition milling of the calcined powder for 2 h had a little milling effect, resulting in a slight decrease in the particle size to 0.45 $\mu$m. The milled powder consisted of small spherical primary particles and some large particles, which had been agglomerated during calcination. Due to the excellent sinterability of the powder, sintering of the powder compacts for 4 h showed relative densities of 78.7% at 1000$^{\circ}C$ and 97.8% at 1300$^{\circ}C$, respectively. Densification was found to almost complete at temperature above 1200$^{\circ}C$ and a dense and homogeneous microstructure was obtained. A rapid grain growth occurred between 1200$^{\circ}C$ and 1300$^{\circ}C$. Grains in 0.1$\sim$0.5 $\mu$m sizes at 1200$^{\circ}C$ grew to 0.2$\sim$2 $\mu$m and their size distribution became broader at 1300$^{\circ}C$.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.3
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• pp.39-45
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• 1998

SrBi$_{2}$Ta$_{2}$O$_{9}$ (SBT) ferroelectric thin films for nonvolatile memory were prepared on Pt/Ti/SiO$_{2}$/Si and RuO$_{2}$/SiO$_{2}$/Si substrates by RF magnetron sputtering. The dependences of crystalline and electrical properties on the lower electrode type(Pt and RuO$_{2}$) and the annealing temperatures were investigated. SBT films regardless of their electrode types showed typeical Bi layered peroviskite crystal structures. The crystalline quality of as-deposited SBT films was improved by the rapid thermal annealing at 650.deg. C for 30 sec. The remanetn polarization of 2Pr (Pr+-Pr-) of the annealed SBT films deposited on Pt/Ti/SiO$_{2}$/Si substrates were about 11 .mu.C/cm$^{2}$ and 3 .mu.C/cm$^{2}$, respectively. The leakage currents at 3 V bias voltage were about 0.8 .mu.A/cm$^{2}$ for SBT/ Pt/Ti/SiO$_{2}$/Si and about 1 .mu.A/cm$^{2}$ for SBT/RuO$_{2}$/SiO$_{2}$/Si sample. SBT films annealed at 650 .deg. C showed no degradation in Pr values after 10$^{11}$ polarization switching cycles, indicating good fatigue properties. In addition, for SBT samples deposited on Pt/Ti/SiO$_{2}$/Si, Pr values increased to more than that of initial state, suggesting the increament of leakage current caused by repeated polarization.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2413-2418
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• 2013

Forensic and legal medicine require reliable data to indicate excessive alcohol consumption. Ethanol is oxidatively metabolized to acetate by alcohol dehydrogenase and non-oxidatively metabolized to ethyl glucuronide (EtG), ethyl sulfate (EtS), phosphatidylethanol, or fatty acid ethyl esters (FAEE). Oxidative metabolism is too rapid to provide biomarkers for the detection of ethanol ingestion. However, the non-oxidative metabolite EtG is a useful biomarker because it is stable, non-volatile, water soluble, highly sensitive, and is detected in body fluid, hair, and tissues. EtG analysis methods such as mass spectroscopy, chromatography, or enzyme-linked immunosorbent assay techniques are currently in use. We suggest that nuclear magnetic resonance (NMR) spectroscopy could be used to monitor ethanol intake. As with current conventional methods, NMR spectroscopy doesn't require complicated pretreatments or sample separation. This method has the advantages of short acquisition time, simple sample preparation, reproducibility, and accuracy. In addition, all proton-containing compounds can be detected. In this study, we performed $^1H$ NMR analyses of urine to monitor the ethanol and EtG. Urinary samples were collected over time from 5 male volunteers. We confirmed that ethanol and EtG signals could be detected with NMR spectroscopy. Ethanol signals increased immediately upon alcohol intake, but decreased sharply over time. In contrast, EtG signal increased and reached a maximum about 9 h later, after which the EtG signal decreased gradually and remained detectable after 20-25 h. Based on these results, we suggest that $^1H$ NMR spectroscopy may be used to identify ethanol non-oxidative metabolites without the need for sample pretreatment.

• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.139-142
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• 2018

Silicon (Si) is a promising anode material for next-generation lithium ion batteries (LIBs) because of its high capacity of 4,200 mAh/g ($Li_{4.4}Si$ phase). However, the large volume expansion of Si during lithiation leads to electrical failure of electrode and rapid capacity decrease. Generally, a binder is homogeneously mixed with active materials to maintain electrical contact, so that Si needs a particular binding system due to its large volume expansion. Polyvinyl alcohol (PVA) is known to form a hydrogen bond with partially hydrolyzed silicon oxide layer on Si nanoparticles. However, the decrease of its cohesiveness followed by the repeated volume change of Si still remains unsolved. To overcome this problem, we have introduced the electrospinning method to weave active materials in a stable nanofibrous PVA structure, where stresses from the large volume change of Si can be contained. We have confirmed that the capacity retention of Si-based LIBs using electrospun PVA matrix is higher compared to the conservative method (only dissolving in the slurry); the $25^{th}$ cycle capacity retention ratio based on the $2^{nd}$ cycle was 37% for the electrode with electrospun PVA matrix, compared to 27% and 8% for the electrodes with PVdF and PVA binders.

• Asian Journal of Atmospheric Environment
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• v.2 no.2
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• pp.102-108
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• 2008

In China, energy and environmental problems are becoming serious owing to rapid economic development. Coal is the most problematic energy source because it causes indoor and outdoor air pollution, acid rain, and global warming. One type of clean coal technology that has been developed is the coal-biomass briquette (or bio-briquette, BB) technique. BBs, which are produced from pulverized coal, biomass (typically, agricultural waste), and a sulfur fixation agent (slaked lime, $Ca(OH)_2$) under high pressure without any binder, have a high sulfur-fixation effect. In addition, BB combustion ash, that is, the waste material, can be used as a neutralization agent for acidic soil because of its high alkalinity, which originates from the added slaked lime. In this study, we evaluated the suitability of alternative biomass sources, namely, aquatic plants, as a BB constituent from the perspective of their use as a source of energy. We selected three types of aquatic plants for use in BB preparation and compared the fuel, handling, and environmental characteristics of the new BBs with those of conventional BBs. Our results showed that air-dried aquatic plants had a higher calorific value, which was in proportion to their carbon content, than agricultural waste biomass; the compressive strength of the new BBs, which depends on the lignin content of the biomass, was high enough to bear long-range intracontinental transport in China; and the new BBs had the same emission control capacity as the conventional BBs.

• Journal of Pharmaceutical Investigation
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• v.30 no.4
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• pp.247-252
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• 2000

The advantages of transdermal administration are avoiding hepatic first pass effect, minimizing inter- and intra-patient variation, maintaining steady-state plasma level to provide long-term therapy from a single dose, and allowing a rapid termination of drug input. Clenbuterol, a selective ${\beta}_2-adrenergic$ receptor stimulant, has been introduced as a potent bronchodilator for patients with bronchial asthma, chronic obstructive bronchial disease. For the development of transdermal systems containing clenbuterol, two limiting factors - long lag time and low flux - must be overcome. In this study, we attempted to select optimal formulation for preparation of clenbuterol patch using hairless mouse skin and flow-through diffusion cell. The flux of clenbuterol increased as the percent of clenbuterol dose dependently in the concentration range of 5-15%. Based on this result, we fixed the concentration of clenbuterol as 15%. The effect of various penetration enhancers on percutaneous absorption of clenbuterol through hairless mouse skin was investigated. Labrafil was the most effective enhancer, which increased the permeability of clenbuterol approximately 4-fold compared with the control without penetration enhancer. Optimal enhancer concentration was 3%. The effect of various adhesives on penetration of clenbuterol was also investigated. Among the adhesives studied, MA-31 was the most effective adhesive. Furthermore, the clenbuterol patch composed of 15% clenbuterol, 3% Labrafil and 82% MA-31, which gave most excellent penetration of drug in in vitro penetration study, maintained therapeutic plasma levels in in vivo study using S.D. rats. These studies demonstrated a good feasibility of clenbuterol administration through the intact skin using a transdermal patch, and show a possibility of the development of clenbuterol patches.

• Analytical Science and Technology
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• v.28 no.4
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• pp.299-307
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• 2015

In May 2012, a safety hazard issue arose because some kiwifruit growers in New Zealand had sprayed streptomycin to prevent kiwifruit canker. Therefore, for food safety management, analytical methods to determine streptomycin residues in kiwifruits are required. We developed an analytical method to determine streptomycin residues in kiwifruit samples using liquid chromatograph tandem mass spectrometer (LC-ESI-MS/MS). Streptomycin residues in samples were extracted using 1% formic acid in methanol, centrifugation for 10 min, and subsequent supernatant filtration. Purified samples were subjected to LC-ESI-MS/MS to confirm presence of and quantify streptomycin residues. Average streptomycin recoveries (6 replicates each sample) were in the range of 94.8%-110.6% with relative standard deviations of <10%. The linearity of the concentration range of 0.01-5.0 mg/kg using a matrix-matched calibration gave R² = 0.9995. The limit of quantification (LOQ) was 0.01 mg/kg. Results showed that our analytical method is rapid, simple, and sensitive, with easy sample preparation.

• Journal of Animal Science and Technology
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• v.46 no.5
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• pp.841-848
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• 2004

Rapid detection of viable Salmonella in pasteurized milk is important to protect public health from food poisoning. Reverse transcriptase-polymerase chain reaction(RT-PCR) is recognized as a molecular genetical method to differentiate between live and dead bacteria The RT-PCR in this study was designed to detect specifically viable Salmonella in milk by using the primers whose nucleotide sequences were determined based on fimA gene which encodes the submit of type 1 fimbriae. Treatment of RNA preparation with RNase-free DNase was adequate enough to destroy DNA, which may otherwise be amplified in the RT PCR Seven strains of Salmonella were detected in the RT-PCR but Escherichia coli, Shigella sonnei, Citrobacter freundii, and Klebsiella pneumoniae were not. $10^7/ml$ and $10^6/ml$ of dead Salmonella which were heat-treated in milk were detectable by using the RT-PCR but $10^5{\sim}10/ml$ of the dead bacteria were not. The sensitivity of the RT-PCR in detecting viable Salmonella was 100 cells/ml.

• Korean Journal of Materials Research
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• v.24 no.5
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• pp.255-258
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• 2014

Zirconium boride is an artificial or which is rarely found in the nature. $ZrB_2$ is popular in the hard material industry because it has a high melting point, excellent mechanical properties and chemical stability. There are two known methods to synthesize $ZrB_2$. The first involves direct reaction between Zr and B, and the second is by reduction of the metal halogen. However, these two methods are known to be unsuitable for mass production. SHS(Self-propagating High-temperature Synthesis) is an efficient and economic method for synthesizing hard materials because it uses exothermic reactions. In this study, $ZrB_2$ was successfully synthesized by subjecting $ZrO_2$, Mg and $B_2O_3$ to SHS. Because of the high combustion temperature and rapid combustion, in conjunction with the stoichiometric ratio of $ZrO_2$, Mg and $B_2O_3$; single phase $ZrB_2$ was not synthesized. In order to solve the temperature problem, Mg and NaCl additives were investigated as diluents. From the experiments it was found that both diluents effectively stabilized the reaction and combustion regime. The final product, made under optimum conditions, was single-phase $ZrB_2$ of $0.1-0.9{\mu}m$ particle size.

• The Korean Journal of Food And Nutrition
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• v.30 no.4
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• pp.804-812
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• 2017

This study investigated the effects of Goami 2 on the properties of Garaetteok. The moisture, crude protein, crude lipid and crude ash contents of the rice were 16.02, 5.40, 1.87 and 0.77%, respectively. The amylose contents (32.16%) and total dietary fiber contents (9.03%) were the highest in Goami 2. The water binding capacity of Goami 2 (167.84%) was higher than general rice flour. Using a rapid visco analyzer (RVA), the initial pasting temperature of Goami 2 was found to be the highest; also, the peak viscosities of Goami 2 were higher than general rice powder. To assess the effect of Goami 2 on the quality characteristics of Garaetteok, the rice-cake was made by adding various amounts of Goami 2 (0, 10, 20, 30, and 40% w/w) to rice. It was observed that higher the amount of added Goami 2, lower were the grades. In terms of the color values of Goami 2 addition, the L-values of Garaetteok were lower with increasing amount of Goami 2; addition of 40% Goami 2 had the lowest value. The textural properties (hardness) also showed that tteok containing the greater amounts of Goami 2 were considerably harder compared with the control. Sensory preference tests revealed that addition of less Goami 2 had the highest scores for appearance, color and overall acceptability, and the Goami 2 added was lower than control. Therefore, as compared to others cultivars, rice flour proved the most acceptable for the preparation of Garaetteok with cultivar rice.