• 한국연초학회지
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• 제12권2호
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• pp.77-83
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• 1990

This study was conducted to develop the method of hydrocarbon analysis and investigate hydrocarbon contents in flue-cured and burley tobacco leaves harvested in Korea and U.S.A. Tobacco leaf was extract with hexane in soxhlet apparatus. Hydrocarbon was fractionated from hexane extract by silica gel column chromatography, and then separated and indentified by GC, GC/MS using SE-54 fused silica capillary column. The developed method was feasible to analyze neophytadiene, normal and branched hydrocarbons from Clo to Cn. The result of recovery test was decade 99%, eicosane 100%, triacontane 102%. The major hydrocarbon of tobacco leaves were neophytadiene, nC3l, iC31, nC33, aC33, aC32, aC30 and nC29. The amount of total hydrocarbon in burley and flue-cured tobacco leaves harvested in U.S.A. and Korea were 4591, 2931, 2929 and 3015$\mu\textrm{g}$/g, respectively.

• Bulletin of the Korean Chemical Society
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• 제30권4호
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• pp.945-947
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• 2009

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2008년도 추계학술논문발표회 논문집
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• pp.17-20
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• 2008

Numerical simulations were performed for the prediction of the flame structure of a hydrocarbon flame interacting with a hydrogen flame. Methane was used as a hydrocarbon fuel in this study. The interaction of two 1D premixed flames established in counterflow geometry was investigated. The temperature of the flame interacting with each other was much higher and the flame thickness was wider at a global strain of $1000\;s^{-1}$ than normal methane flame.

• 한국수소및신에너지학회논문집
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• 제15권1호
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• pp.12-22
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• 2004

In order to evaluate the potential of partial hydrocarbon substitution to improve the safety of hydrogen use in general and the performance of internal combustion engines in particular, the outward propagation and development of surface cellular instability of spark-ignited spherical premixed flames of mixtures of hydrogen, hydrocarbon, and air were experimentally studied at NTP (normal temperature and pressure) condition in a constant-pressure combustion chamber. With propane being the substituent, the laminar burning velocities, the Markstein lengths, and the propensity of cell formation were experimentally determined, while the laminar burning velocities and the associated flame thicknesses were computed using a recent kinetic mechanism. Results show substantial reduction of laminar burning velocities with propane substitution, and support the potential of propane as a suppressant of both diffusional-thermal and hydrodynamic cellular instabilities in hydrogen-air flames.

• Asian Pacific Journal of Cancer Prevention
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• 제13권11호
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• pp.5445-5450
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• 2012

Although benign uterine leiomyomata (LMA) is the most common reproductive tumor in premenopausal women, its etiology is largely unknown. We aimed in the present study to demonstrate the potential role of environmental factors with estrogenic activity in tumor etiology by focusing on the role of aryl hydrocarbon receptor (AhR) which mediates the effects of many environmental endocrine disruptors and contributes to the loss of normal ovarian function in polluted environments. This case-control study aimed to compare the interactions between AhR and lifestyle factors in a clinical setting for the first time among 138 newly diagnosed LMA patients and 138 normal controls who lived in Tehran and Mashhad, respectively, during the last 10 years. To conduct immunohistochemical studies using appropriate monoclonal antibodies, 30 cases were selected retrospectively from 2009-2011 from the pathology departments of two university hospitals in Tehran. Although the levels of sex steroid receptors were similar in adjacent myometrium and uterine leiomyomas of all cases, AhR was significantly overexpressed (p=0.034, OR=1.667) in uterine LMA and this overexpression was correlated with living in Tehran [(p=0.04, OR=16 (1.216-210.58)], smoking[P=0.04, OR=2.085 (1.29-3.371)], living near polycyclic aromative hydrocarbon producing companies [p=0.007, OR=2.22 (1.256-3.926)] and eating grilled meat [p=0.042, OR=1.28 (1.92-3.842)]. Our study contributes to the understanding of the effects of EDCs on AhR levels as well as women's health and points out possible risk factors for the development and growth of uterine LMA. It seems that the development of LMA could be the result of interactions between hormonal and environmental factors.

• 한국연소학회지
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• 제6권2호
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• pp.43-49
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• 2001

Instantaneous, three-dimensional scalar dissipation rates of the reaction progress variable are measured in turbulent premixed Bunsen flames of lean hydrocarbon/air mixtures with the two-sheet, two-dimensional Rayleigh scattering technique. The flames investigated are located in the turbulent flame-front regime on a newly proposed combustion diagram for premixed flames. The conditionally-averaged mean scalar dissipation rates, $N_{\zeta}$ are found to be lower than the calculated laminar values, indicating a locally broadened flame front. In agreement with previous measurements, the maximum of $N_{\zeta}$, decreases strongly with increasing Karlovitz numbers. The conditional probability density functions are close to a log-normal distribution for scalar dissipation rates conditioned at the progress variable value where the scalar dissipation is maximum in unstretched laminar flame calculations. The time scale for the Favre-averaged mean scalar dissipation rate decreases in general across the turbulent flame brush from the unburnt to burnt side.

• Bulletin of the Korean Chemical Society
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• 제12권4호
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• pp.441-444
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• 1991

The intramolecular proton transfers of 2-hydroxy-4,5-naphthotropone in room temperature solutions are studied using static and time-resolved absorption and emission spectroscopy. Dual normal and tautomer fluorescence is observed in ethanol solution, while only the tautomer fluorescence is observed in cyclohexane solution. The fluorescence lifetimes and quantum yields in ethanol and cyclohexane solutions indicate that in hydrocarbon solvents, rapid intersystem crossing competes with proton transfer in the first excited singlet state. Transient absorption spectra and kinetics indicate that proton transfer also undergoes in the first triplet state with a transfer time of ∼ 3 ns. No transient absorption from the tautomer ground state indicates a rapid back proton transfer in the ground state.

• Macromolecular Research
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• 제11권4호
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• pp.231-235
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• 2003

Phase behavior information is necessary for accomplishing homogeneous copolymerization to obtain high yield of copolymers and prevent a fouling problem. Cloud-point data to $160^{\circ}C$ and 1,450 bar are presented for five $C_6$ hydrocarbon solvents, normal hexane, 2,2-dimethyl butane, 2,3-dimethyl butane, 2-methyl pentane, and 3-methyl pentane, with poly(ethylene-co-53 mol% norbornene) ($PEN_{53}$). The pressure-concentration isotherms measured for $PEN_{53}$/n-hexane have maximums that range between 5 and 12 wt% $PEN_{53}$. The cloud-point curves for $PEN_{53}$ all have negative slopes that decrease in pressure with temperatures. The single-phase region of $PEN_{53}$ in n-hexane is larger than the regions in 2,2-dimethyl butane, 2,3-dimethyl butane, 2-methyl pentane, and 3-methyl pentane. The cloud-point curve of $PEN_{53}$ in 2,2-dimethyl butane is located at higher temperatures and pressures than the curve in 2,3-dimethyl butane due to the reduced dispersion interactions with and limited access of 2,2-dimethyl butane to the copolymer. Similar cloud-point behavior is observed for $PEN_{53}$ in 2-methyl pentane and 3-methyl pentane.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.83-84
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• 2002

For estimation of chain-matching phenomena between normal paraffin as a solvent and straight-chain fatty acid as an additive, the density measurement of n-dodecane, n-tetradecane and n-hexadecane were carried out at oil temperature 313K and pressure up to 1.3 GPa. Their solidification pressure were easily determined by the appearance of molecular crystal, abrupt volumetric contraction and generation of heat of solidification and showed minima under the matching condition. The bulk modulus K of molecular crystal was evaluated using phase diagram. The bulk modulus showed maxima under the each matching condition. The chain matching effect on the bulk modulus beyond the scope of the interfacial phenomena are confirmed.

• 한국환경성돌연변이발암원학회지
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• 제26권3호
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• pp.77-85
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• 2006

2,3,7,8-Tetrachlorodibenzo-$\rho$-dioxin(TCDD) displays high toxicity in animals and has been implicated in human carcinogenesis. Although TCDD is recognized as potent carcinogens, relatively little is known about their role in the tumor promotion and carcinogenesis. It is known that TCDD can increase of cancer risk from various types of tissue by a mechanism possibly involving the aryl hydrocarbon receptor (AhR) activation. In this study, effects of TCDD on cellular proliferation of normal human skin and lung fibroblasts, Detroit551 and WI38 cells were investigated. In addition, to enhance our understanding of TCDD-mediated carcinogenesis, we have investigated process in which expression of Erk1/2, cyclinD1, oncogene such as Ha-ras and c-myc, and their cognate signaling pathway. TCDD that are potent activators of AhR-mediated activity was found to induce significant increase of cytochrome P4501A1 mRNA expression, suggesting a presence of functional AhR. These results support that CYP1A1 enzyme may be involved in the generation of TCDD-induced toxicity. Moreover mitogen-activated protein kinases (MARKs) phosphorylation and cyclin D1 overexpression are induced by TCDD, which corresponded with the progression of cellular proliferation. However, TCDD did not affected Ha-ras and c-myc mRNA expression. Taken together, it seems that TCDD are could be a part of cellular proliferation in non-tumorigenic normal human cells such as Detroit551 and WI38 cells through the upregulation of MAPKs signaling pathway regulating growth of cell population. Therefore, AhR-activating TCDD could potentially contribute to tumor promotion and Detroit551 and WI38 cells have been used as a detection system of tumorigenic effects of TCDD.