• Journal of the Korean Applied Science and Technology
• /
• v.27 no.2
• /
• pp.168-174
• /
• 2010

In this research, an effective method for reducing the fibrillation of lyocell fibers, which are spun from a solution of cellulose in N-methyl morpholine-N-oxide(NMMO), through consecutive chemical treatments. Undried solution-spun cellulosic fiber was firstly treated with 10 to 30 wt% of multifunctional crosslinking agents, such as ethylene glycol poly(3-chloro-2-hydroxypropyl) ether, and then dipped into alkaline solution to introduce epoxy functions. Finally steam condition was applied to occur a chemical crosslinking in order to reduce the fibrillation on the surface of fibers. Fibrillation was also reduced significantly by adding extra $Na_2SO_4$ in NaOH solution. In addition, Antifibrilllated lyocell fibers show the slightly higher dyeability(4 %) to Cibacron Blue without serious reduction of mechanical properties.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.20 no.5
• /
• pp.19-25
• /
• 2012

This study describes effects of DME additives on combustion and exhaust emissions characteristics including nano-particle in a single cylinder compression ignition engine. Considered additives include bio-diesel, n-butanol, and MTBE for increasing kinematic viscosity. Among three additives, n-butanol showed the greatest kinematic viscosity. In addition MTBE showed the highest vapor pressure. In the present study mixing ratios of additives were kept constant at 1 and 10% by volume. Experiments were performed at 1200rpm engine speed and nano-particles were measured by SMPS (Scanning mobility particle sizer) devices. Results of combustion characteristics showed that considered additives had little effects on combustion pressure. However, patterns of heat release rate were dependent on properties of additives. Nano-particles of MTBE were the lowest among considered additives.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.10a
• /
• pp.89-110
• /
• 2003

The limitations of conventional soil and groundwater contamination remediation technologies have motivated a search for innovative technologies; particularly in situ technologies that do not require extraction of contaminants from the subsurface. All engineered in situ remediation systems require that the contaminant be mixed with a remedial compound. Horizontal flow treatment wells (HFTWs), an innovative technology that consists of a pair of dual-screened treatment wells, were used at a trichloroethylene (TCE) contaminated site to efficiently achieve this mixing of contaminant and remedial compound in order to effect in situ bioremediation (McCarty et al., 1998). In this paper, the potential of HFTWs to treat chlorinated aliphatic hydrocarbons (CAHs) as well as other soil and groundwater contaminants of concern, such as nitroaromatic compounds (NACs), perchlorate, and methyl-tert-butyl ether (MTBE), is examined. Through a combination of laboratory studies, model analyses, and field evaluations, the effectiveness of this innovative technology to manage these contaminants is investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.551-552
• /
• 2006

The miniature fuel cells have emerged as a promising power source for applications such as cellular phones, small digital devices, and autonomous sensors to embedded monitors or to micro-electro mechanical system (MEMS) devices. Several chemicals run candidate at a fuel in those systems, such as hydrogen. methanol, ethanol, acetic acid, and di-methyl ether (DME). Among them, hydrogen shows most efficient fuel performance. However, there are some difficulties in practical application for portable power sources. Therefore, more recently, there have been many efforts for development of micro-reformer to operate highly efficient micro fuel cells with liquid fuels such as methanol, ethanol, and DME In our experiments, we have integrated a micro-fuel processor system using low temperature co-fired ceramics (LTCC) materials. Our integrated micro-fuel processor system is containing embedded heaters, cavities, and 3D structures of micro- channels within LTCC layers for embedding catalysts (cf. Figs. 1 and 2). In the micro-channels of LTCC, we have loaded $CuO/ZnO/Al_2O_3$ catalysts using several different coating methods such as powder packing or spraying, dipping, and washing of catalyst slurry.

• Natural Product Sciences
• /
• v.18 no.2
• /
• pp.97-101
• /
• 2012

Six lignan compounds, 1-(17,21-dihydroxyphenyl)-9-(12,13-dihydroxyphenyl)-1-nonanone (malabaricone C) (1), 7'-(3',4'-methylenedioxyphenyl)-8,8'-dimethyl-7-(3,4-dihydroxyphenyl)-butane (2), 7'-(3',4'-dimethoxyphenyl)-8,8'-dimethyl-7-(3-methoxy-4-hydroxyphenyl)-butane (3), 7-(4-hydroxy-3-methoxyphenyl)-7'-(3',4'-methylenedioxyphenyl)-8,8'-lignan-7-methyl ether (4), (+)-erythro-(7S,8R)-${\Delta}^{8^'}$-7-hydroxy-3,4,3',5'-tetramethoxy-8-O-4'-neolignan (5), and (+)-erythro-(7S,8R)-${\Delta}^{8^'}$-7-acetoxy-3,4,3',5'-tetramethoxy-8-O-4'-neolignan (6), were isolated from the seeds of Myristica fragrans. The chemical structures of these compounds were determined on the basis of spectroscopic analyses including 2D NMR. Compounds 1 - 6 were evaluated for their cytotoxic activity against the HL-60, MCF-7, and A549 cancer cell lines in in vitro.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1998.11a
• /
• pp.184-184
• /
• 1998

Aldose reductase(AR), a rate-limiting enzyme in the polyol pathway, has been demonstrated to cause the intracellular accumulation of sorbitol or galactitol and hence to play key roles not only in the cataract formation in the lens but also in the pathogenesis of diabetic complications such as neuropathy, retinopathy and nephropathy, etc. In a series of investigations to evaluate potential AR inhibitors from medicinal plants, we have shown that some hot water extracts exhibited a significant inhibition of a significant inhibition of bovine lens AR in vitro. Among active plants, the roots of Angelica dahuria (Umbelliferae) were shown to have relatively potent AR inhibitory activity. Systematic fractionation of the ether soluble fraction monitored by bioassay led to isolation of two furanocoumarins, byakangelicin(I) and ter-O-methyl byakangelicin( II), were identified as potential AR inhibitors, their $IC_{50}$ values being 6.2 M and 2.8 M, respectively.

• Mass Spectrometry Letters
• /
• v.1 no.1
• /
• pp.29-32
• /
• 2010

Cross reacting antibodies can cause an overestimation of the results of immunoassays. Therefore, alternative methods are needed for the accurate quantification of steroids. Gas chromatography combined with isotope-dilution mass spectrometry (GC-IDMS) is developed to quantify urinary active androgens, testosterone, epitestosterone and dihydrotestosterone, which are clinically relevant androgens to both hair-loss and prostate diseases. The method devised involves enzymatic hydrolysis with $\beta$-glucuronidase, solid-phase extraction, liquid-liquid extraction using methyl tert-butyl ether and subsequent conversion to pentafluorophenyldimethylsilyl-trimethylsilyl (flophemesyl-TMS) derivatives for sensitive and selective analysis in selected-ion monitoring mode. Flophemesyl-TMS derivatization not only eliminates matrix interference but also has a good peak resolution within a 6 min-run. A selective and sensitive GC technique with flophemesyl-TMS derivatives also allows accurate quantitative analysis of three active androgens when combined with IDMS. The limit of quantification of the three analytes was <50 pg/mL, and extraction recoveries ranged from 91.9 to 102.1%. The precision and accuracy were 1.2~6.5% and 89.0~106.7%, respectively. This GC-IDMS method can be useful for evaluating the drug efficacy and monitoring the biological processes responsible for male-pattern baldness and prostate diseases.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.5
• /
• pp.29-34
• /
• 2011

This study investigates the potential of DME/Diesel dual fuel engine for reducing emissions with same power. Dual fuel engine controls the combustion using two different fuels, DME and diesel with different auto-ignition timings. In the previous work, the caracteristics of combustion and emissions under single cylinder engine and ignition is done by compression ignition. Pre-mixture is formed by injecting low-pressure DME into an intake manifold and high-pressure fuel (diesel or DME) is injected directly into the cylinder. Both direct diesel injection and port fuel injection reduced the significant amount of Smoke, CO and NOx in the homogeneous charge compression ignition engine due to present of oxygen in DME. In addition, when injecting DME directly in cylinder with port DME injection, there is no changes in emissions and energy consumption rate even operated by homogeneous charge compression ignition.

• Archives of Pharmacal Research
• /
• v.27 no.12
• /
• pp.1202-1206
• /
• 2004

A rapid, sensitive and selective liquid chromatography-tandem mass spectrometric (LC-MS/ MS) method for the determination of lithospermic acid B (LSB) in rat serum was developed. LSB and internal standard, 7-hydroxy-3-phenyl-chromen-4-one (HPC) were extracted from rat serum with methyl-tert-butyl ether at acidic pH and analyzed on a Luna $C_8$ column with the mobile phase of acetonitrile-ammonium formate (10 mM, pH 6.5) (50:50, v/v). The analytes were detected using a negative electrospray ionization tandem mass spectrometry in the multiple- reaction-monitoring mode. The standard curve was linear $(r^2 = 0.997)$ over the concentration range of 10.0-500 ng/mL. The coefficient of variation and relative error for intra- and interassay at three QC levels were 1.1~6.2% and -10.3~-2.7%, respectively. The recovery of LSB from serum sample ranged from 73.2 to 79.5%, with that of HPC (internal standard) being 75.1 %. The lower limit of quantification for LSB was 10 ng/mL using 50 ${\mu}L$ of serum sample.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.4
• /
• pp.575-579
• /
• 2002

Two-dimensionally cross-linked ultrathin films of poly(maleic acid-alt-methyl vinyl ether) (MA-MVE) and poly(allylamine) (PAA) were produced by using sodium dioctadecyl sulfate (2C18S) as the monolayer template for Langmuir-Blodgett (LB) depositio n. The template molecules were subsequently removed by thermal treatment followed by extraction. The polyion-complexed monolayers of three components, i.e., template 2C18S, co-spread PAA, and subphase MA-MVE, were formed at the air-water interface. Their monolayer properties were studied by the surface pressure-area isotherm. The monolayers were transferred on solid substrates as Y type. The polyion-complexed LB films and the resulting network films were characterized by FT-IR spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The cross-linking to form a polymer network was achieved by amide or imide formation through heat treatment under a vacuum. SEM observation of the film on a porous fluorocarbon membrane filter (pore diameter 0.1 ㎛) showed covering of the pores by four layers in the polyion complex state. Extraction by chloroform followed by heat treatment produced hole defects in the film.