• Bulletin of the Korean Chemical Society
• /
• v.15 no.10
• /
• pp.852-856
• /
• 1994

A series of aliphatic hydrocarbons, methane to hexane in the liquid state, are modeled with the molecular mechanical potential parameters treating all hydrogen degrees of freedom explicitly. Thermodynamic properties (heat capacities and heats of vaporization) are calculated from relatively short (20ps) molecular dynamics trajectories. The liquid state structures are also examined through various radial distribution functions. Molecular dynamics simulations reproduce experimentally measured properties within a few percent errors, thus indicate that the present set of all-hydrogen parameters is suitable for simulating macromolecular systems in bulk.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.10 no.1
• /
• pp.120-127
• /
• 2002

This study was carried out to evaluate the effects of initial concentration on composting of diesel-contaminated soil. Silt loam was used in this study. Target contaminant, diesel oil, was spiked at about 2,000, 4,000, and 10,000mg/kg of dry soil, respectively. Mix ratio of soil to sludge was 1:0.3 as wet weight basis. Temperature was maintained at $20^{\circ}C$ Volatilization loss of TPH was 0.7-3.5% of the initial concentrations. Volatilization loss of TPH was not increased in proportion to the initial concentration. After 30 days of operation, 86% and 94% of the initial concentrations at about 2,000 and 10,000mg TPH/kg were biodegraded. Normal alkanes were degraded more rapidly than TPH. The compounds of C12 to C14 were volatilized greatly among n-alkanes. The first order degradation rate constants of about 2,000, 4,000, and 10,000mg TPH/kg were 0.079, 0.069, and 0.061/day, respectively. Produced-$CO_2$ and degraded-TPH were correlated highly regardless of the initial TPH concentration(r = 0.97-0.99).

• Bulletin of the Korean Chemical Society
• /
• v.19 no.10
• /
• pp.1068-1072
• /
• 1998

We present results of molecular dynamic (MD) simulations for the segmental motion of liquid n-butane as the base case for a consistent study for conformational transition from one rotational isomeric state to another in long chains of liquid n-alkanes. The behavior of the hazard plots for n-butane obtained from our MD simulations are compared with that for n-butane of Brownian dynamics study. The MD results for the conformational transition of n-butane by a Poisson process form the total first passage times are different from those from the separate t-g and g-t first passage times. This poor agreement is probably due to the failure of the detailed balance between the fractions of trans and gauche. The enhancement of the transitions t-g and g-t at short time regions are also discussed.

• Membrane and Water Treatment
• /
• v.10 no.5
• /
• pp.361-372
• /
• 2019

Effect of different alkane based solvents on the stability of emulsion liquid membrane was investigated using normal alkanes (n-hexane, n-heptane, n-octane and n-decane) under various operating parameters of surfactant concentration, emulsification time, internal phase concentration, volume ratio of internal phase to organic phase, volume ratio of emulsion phase to external phase and stirring speed. Results of stability revealed that emulsion liquid membrane containing n-octane as solvent and span-80 (5 % (w/w)) as emulsifying agent presented the highest amount of emulsion stability (the lowest breakage) compared with other solvents; however, operating parameters (surfactant concentration (5% (w/w)), emulsification time (6 min), internal phase concentration (0.05 M), volume ratio of internal phase to organic phase (1/1), volume ratio of emulsion phase to external phase (1/5) and stirring speed (300 rpm)) were also influential on improving the stability (about 0.2% breakage) and on achieving the most stable emulsion. The membrane with the highest stability was employed to extract acridine orange with various concentrations (10, 20 and 40 ppm) from water. The emulsion liquid membrane prepared with n-octane as the best solvent almost removed 99.5% of acridine orange from water. Also, the prepared liquid membrane eliminated completely (100%) other cationic dyes (methylene blue, methyl violet and crystal violet) from water demonstrating the efficacy of prepared emulsion liquid membrane in treatment of dye polluted waters.

• Asian-Australasian Journal of Animal Sciences
• /
• v.20 no.6
• /
• pp.872-879
• /
• 2007

A study was conducted to investigate the seasonal changes in nutrient composition of pasture, voluntary intake and digestibility of sheep grazing an introduced Leymus chinensis pasture located in western Jilin Province, China. The whole-plant of L. chinensis and the samples simulating ingestion by sheep (simulating sample) were collected in spring (May, 2004), summer (July, 2004), autumn (September, 2004) and the end of winter (April, 2005). The contents of gross energy (GE), organic matter (OM), crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF) and alkanes were determined. Voluntary intake and apparent digestibility of the nutrients in each season were also examined using 6 mature Chinese Northeast Merino ewes (differed among the seasons) grazing on a paddock of 1 ha size. The apparent digestibilities of GE, dry matter (DM), OM, CP, NDF and ADF of L. chinensis were significantly greater (p<0.05) in spring and summer than in autumn and winter. Metabolizable energy (ME) content was 12.13, 11.62, 8.66 and 10.40 MJ/kg DM for L. chinensis in spring, summer, autumn and winter respectively, and the corresponding voluntary feed intakes were 91, 119, 59 and 58 g/d per kg metabolic weight ($LW^{0.75}$). The ME contents and DM intakes in autumn and winter were significantly lower than in spring and summer (p<0.05). The intake of L. chinensis pasture was sufficient to provide ME requirements for maintenance by the dry ewes in all the seasons, but inadequate for maintenance protein requirement in winter. (Supported by funds from National Basic Research Program of China, Grant No. 2007CB106800).

• Microbiology and Biotechnology Letters
• /
• v.17 no.3
• /
• pp.236-240
• /
• 1989

The isolated bacterial strain 1K1 able to grow on extremely high concentration of toluene was morphologically and physiologically best described as Pseudomonas putida. This strain could grow on at least eight aromatic compounds, e.g., benzene, benzoate, phenol, o-cresol, m-cresol, toluene, m-tolunte, and xylene, but did not Brow on alkanes, such as hexane, octane, decane, and cyclohexane. Strain 1K1 could grow on above 95% toluene, but it could not grow on above 1% of other aromatic compounds. In the point of survival, strain 1K1 was resistant to high concentration of alkanes, appreciably resistant to toluene and xylene, and damaged by to other aromatic compounds. Strain 1K1 which grew on high concentration of toluene had irregular cell shape in comparing with normal cell shape of the genus Pseudomonas. Strain 1K1 was shown to have at least two aromatic compound dissimilation pathway, one for benzoate and the other for toluene.