• YAKHAK HOEJI
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• v.52 no.6
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• pp.419-425
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• 2008

A qualitative and quantitative analytical method was developed for detection of methamphetamine (MA) and its main metabolite amphetamine (AM) in oral fluid. Oral fluids of eleven drug abusers were provided by Police, specimens were collected by stimulation with a cotton swab treated with 20 mg of citric acid ($Salivette^{(R)}$; Sarstedt, USA). As the preliminary test, oral fluid samples were screened for amphetamines by Fluorescence Polarization Immunoassay (TDxFLx, Abbott Co.). Extraction for MA was performed using solid-phase extraction (SPE) by $RapidTrace^{TM}$ (Zymark, USA) with mixed mode cation exchange cartridge, CLEAN $SCREEN^{(R)}$ (130 mg/3 ml, UCT) after dilution with phosphate buffer. Samples were evaporated and derivatized by pentafluoropropionic acid anhydride (PFPA). Quantitation of MA and AM was performed by gas chromatography-mass spectrometry (GC-MS) using selective ion monitoring (SIM), the quantitation ions were m/z 204 (MA), 208 (MA-$D_5$), 190 (AM) and 194 (AM-$D_5$). The selectivity, linearity of calibration, limit of detection (LOD) and quantification (LOQ) within- and between day precision, accuracy and recoveries were examined as parts of the method validation. All oral fluid samples gave positive results to immunoassay for MA (cut-off level, 50 ng/ml as d-amphetamine). Concentrations of MA and AM by GC-MS in eleven samples were ranged 104.2${\sim}$4603.3 ng/ml and 32.4${\sim}$268.6 ng/ml, respectively. Extracted calibration curves of MA and AM were linear over the two concentration range of 1${\sim}$100 and 50${\sim}$1000 ng/ml with correlation coefficient of above 0.999. LOQ of MA and AM was 1 and 3 ng/ml, respectively. The intraand inter-day run precisions (CV) for MA and AM were less than 10%, and the accuracies (bias) for MA and AM were also less than 10% at the two different concentrations 5 and 100 ng/ml at low calibration range, 50 and 1000 ng/ml at high calibration range. The absolute recoveries of MA and AM at low and high calibration ranges were more than 82% and 75%, respectively. In this study the qualitative and quantitative analytical method of MA in oral fluid was established. Oral fluid testing may detect drug use in past hours because of its shorter detection window than urine, and be useful in post-accident situations. So oral fluids will be most useful for testing drug abuse in the driving under the influence of drug (DUID) as the alternative specimens of urine.

• Polymer(Korea)
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• v.33 no.6
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• pp.537-543
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• 2009

The direct fluorination of polymers is a heterogeneous reaction using the mixture of $F_2$ and inert gas. In general, the resulting fluorinated polymers have good barrier property chemical stability similar to those of the fluoro-polymers, and could be prepared from the simple process. In this study, the polysulfone dense films were surface fluorinated using the direct fluorination technique and gas permeability and selectivity of the prepared membranes were measured with varying both $F_2$ concentration and reaction time. The introduction of $F_2$ was confirmed by X-ray photoelectron spectroscopy (XPS), water contact angles, and atomic force microscopy (AFM). As the $F_2$ increased, the permeability decreased while the selectivities for $O_2$, $CO_2$, and He gases relative to $N_2$ increased.

• Journal of Life Science
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• v.22 no.10
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• pp.1277-1285
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• 2012

The tumor necrosis, factor-related, apoptosis-inducing ligand (TRAIL) is regarded as a potentially useful anticancer agent with excellent selectivity for cancer cells. However, a considerable number of cancer cells are resistant to apoptosis induction by TRAIL. Developing strategies to overcome this resistance are important for the successful use of TRAIL for cancer therapy. Here, we revealed that siRNA-mediated downregulation of SIRT1 or SIRT1 inhibitor Amurensin G upregulated DR5 and c-Myc and downregulated c-$FLIP_{L/S}$ and Mcl-1, which was associated with sensitization of TRAIL-resistant MCF-7 cells to TRAIL. This result was followed by the activation of caspases, PARP cleavage, and downregulation of Bcl-2 in both TRAIL-treated MCF-7 cells transfected with SIRT1 siRNA and cells co-treated with Amurensin G and TRAIL. Our results suggest that the induction of DR5 and downregulation of c-FLIP via suppression of SIRT1 expression may be a useful strategy to increase the susceptibility of TRAIL-resistant cancer cells to TRAIL-induced cell death.

• Membrane Journal
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• v.21 no.4
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• pp.389-397
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• 2011

In this study, polymer composite membranes based on sulfonated poly(arylene ether sulfone) (SPAES) were prepared using a solution casting method with different amount of vermiculite (VMT) content. The dispersion of VMT particles in the SPAES matrix was confirmed by means of a scanning electron microscopy observation. The composite membrane containing less than 1 wt% of VMT has a smooth skin on the top and bottom, which means there is a good dispersion of VMT in the matrix. The water uptake of the composite membranes gradually increases as the temperature increases, and the results confirm that all the adsorbed water is bound water because VMT has a strong water affinity on account of its high cation exchange value. A composite membrane with a VMT content of less than 1 wt% increases the proton conductivity and reduces the methanol permeability. Of all the composite membranes, the membrane SPAES/VMT 1.0 has the best fuel cell performance in terms of membrane selectivity. The performance value of SPAES/VMT 1.0 is double that of Nafion 112, which suggests that SPAES/VMT1.0 could be an excellent candidate for direct methanol fuel cells.

• Membrane Journal
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• v.28 no.6
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• pp.406-413
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• 2018

In OBIGGS, a small amount of ozone in the atmosphere damages the polymer membrane. Therefore, the ozone removal device is installed at the front end to prevent the damage of the membrane by reducing the concentration of ozone in the gas delivered to the membrane. In this study, two hollow fiber membranes, PI and PSf, used to fabrication hollow fiber module with an effective membrane area of $6.37cm^2$ for gas separation in OBIGGS. The ozone concentration in the chamber was maintained at 2-3 ppm. The gas was continuously supplied into the module by using a pump. The gas permeation characteristics and the tensile strength were evaluated as a function of ozone exposure time. The PI-based hollow fiber membrane showed only 20% reduction in the transmittance, and remained its original uniformity without any significant changes. However, when PSf type hollow fiber membranes were used, the permeability decreased by more than 80% and the tensile strength decreased by more than 70%.

• Journal of the Korean Applied Science and Technology
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• v.38 no.5
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• pp.1335-1344
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• 2021

Ginsenoside Compound K is a triterpene saponin found in the leafs, stems and roots of Panax ginseng. This study aimed to prepare a valuable ginsenoside Compound K using ginseng extracts with the enzyme(Plantase). Plantase showed very efficient activity to produce Compound K from ginseng extracts. Plantase exhibited the highest activity at pH 5 and 50 ℃, as a result of investigating the yield of Compound K by changing the temperature and pH, while fixing the enzyme concentration to 10% or 15% over 48 hours of reaction time. Under optimium conditions, Plantase produced and accumulated Compound K over 35 wt% of whole ginseng extracts. Antimicrobial activitiy of bioconvertied ginseng extracts showed selectivity against Cutibacterium acnes KCTC 3314. Minimal inhibitory concentration (MIC) of bioconverted ginseng extract (35% of Compound K enriched extract) against Cutibacterium acnes KCTC 3314 strain is 31.25ug/mL. These results suggest that the Compound K enriched extract is potential materials for cosmetic products and Plantase is a very useful enzyme for Compound K production.

• Applied Chemistry for Engineering
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• v.33 no.5
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• pp.477-481
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• 2022

As a part of improving the quality of crude methylnaphthalene (CMNO), this study was experimentally examined the reduction of nitrogen-containing compounds (NC) present in the CMNO by solvent extraction. The CMNO was composed of three kinds of NC [quinolone (QU), iso-quinoline (IQU), indole (IN)], three kinds of bicyclic aromatic compound [BAC; naphthalene (NA), 1-methylnaphthalene (1MNA), 2-methylnaphthalene (2MNA)] and biphenyl (BP) etc., in addition to an aqueous formamide solution, which were used as raw materials and a solvent, respectively. The increase in the volume fraction of water to the solvent in the initial state (y_w,0) caused a sharp decrease in the distribution coefficient and the yield of NC, but conversely raised the increased selectivity of NC based on 2MNA. The compositions of QU, IQU and IN in the raffinate oil recovered through the equilibrium extraction of batch co-current 5-stage under constant conditions [y_w,0 = 0.1, volume fraction of solvent to feed (CMNO) at the initial state = 1, operating temperature = 303 K, liquid-liquid contacting time = 72 h] were reduced by about 51.5%, 55.2%, and 71.8%, respectively, when compared to those of CMNO. From the excellent reduction rate of NC, the formamide extraction method suggested in this study can be expected to be a useful reduction method for NC contained in the CMNO.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.188-194
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• 2022

This work presents a non-destructive and straightforward approach to assemble a large-scale conductive electronic film made of a pre-treated single-walled carbon nanotube (SWCNT) solution. For effective electron transfer between the immobilized enzyme and SWCNT electronic film, we optimized the pre-treatment step of SWCNT with p-terphenyl-4,4"-dithiol and dithiothreitol. Glucose oxidase (GOx, a model enzyme in this study) was immobilized on the SWCNT electronic film following the positively charged polyelectrolyte layer deposition. The glucose detection was realized through effective electron transfer between the immobilized GOx and SWCNT electronic film at the negative potential value (-0.45 V vs. Ag/AgCl). The SWCNT electronic film-based glucose biosensor exhibited a sensitivity of 98 ㎂/mM·cm². In addition, the SWCNT electronic film biosensor showed the excellent selectivity (less than 4 % change) against a variety of redox-active interfering substances, such as ascorbic acid, uric acid, dopamine, and acetaminophen, by avoiding co-oxidation of the interfering substances at the negative potential value.

• Clean Technology
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• v.20 no.4
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• pp.375-382
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• 2014

This work investigated the plasma-catalytic decomposition of isopropyl alcohol (IPA) and the behavior of the byproduct compounds over monolith-supported metal oxide catalysts. Iron oxide ($Fe_2O_3$) or copper oxide (CuO) was loaded on a monolithic porous ${\alpha}-Al_2O_3$ support, which was placed inside the coaxial electrodes of plasma reactor. The IPA decomposition efficiency itself hardly depended on the presence and type of metal oxides because the rate of plasma-induced decomposition was so fast, but the behavior of byproduct formation was largely affected by them. The concentrations of the unwanted byproducts, including acetone, formaldehyde, acetaldehyde, methane, carbon monoxide, etc., were in order of $Fe_2O_3/{\alpha}-Al_2O_3$ < $CuO/{\alpha}-Al_2O_3$ < ${\alpha}-Al_2O_3$ from low to high. Under the condition (flow rate: $1L\;min^{-1}$; IPA concentration: 5,000 ppm; $O_2$ content: 10%; discharge power: 47 W), the selectivity towards $CO_2$ was about 40, 80 and 95% for ${\alpha}-Al_2O_3$, $CuO/{\alpha}-Al_2O_3$ and $Fe_2O_3/{\alpha}-Al_2O_3$, respectively, indicating that $Fe_2O_3/{\alpha}-Al_2O_3$ is the most effective for plasma-catalytic oxidation of IPA. Unlike plasma-alone processes in which tar-like products formed from volatile organic compounds are deposited, the present plasma-catalyst hybrid system did not exhibit such a phenomenon, thus retaining the original catalytic activity.

• Journal of the Korean GEO-environmental Society
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• v.16 no.4
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• pp.13-22
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• 2015

The combined impact of Dissolved Organic Matter (DOM) fouling and inorganic ($CaSO_4,Ca_3(PO_4)_2$) scaling on the retention of TNT (2, 4, 6-Trinitrotoluene), RDX (Hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine) and HMX (1, 3, 5, 7-Tetranitro-1, 3, 5, 7-tetrazocane) explosive contaminants by nano-filtration membrane were studied, since organic fouling and salt scaling are the major limitations for membrane filtration. Results reported here indicate that DOM fouling layer with a humic acid does not necessarily lead to an immediate loss of permeate flux but can result in a severe impact on the flux loss when both humic acid and inorganic scaltants were presented simultaneously. The $Ca_3(PO_4)_2$ mixed with humic acid showd most sever flux loss (42%) compared to that of only humic acid presence (8%). It could be a result that the scaling formation of the NF membrane was dominated by cake layer formation of DOM and it was along with pore blocking by the formation of crystals inside the porous active matrix of the NF membrane. In addition, these results indicated that the membrane selectivity of the explosives retention trended correlated with respect to increasing explosives size (listed by MW) based on greater steric interactions and followed the order (MW, g $mol^{-1}$; removal, %): HMX (296.15; 83%) ${\gg}$ RDX (222.12; 49%) ≋ TNT (227.13; 32%). Because the scaling and fouling layer could lead to a additional cake-enhanced concentration polarisation effect, the retention of explosives with the presence of humic acid in the feed solution and inorganic scaling formation on top of an organic fouling layer do not differ substantially retention from that of pure DI feed and NaCl solution.