• Polymer(Korea)
• /
• v.28 no.1
• /
• pp.77-85
• /
• 2004

It has been widely used ultra high molecular weight polyethylene (UHMWPE) for the biomaterials due to its excellent mechanical properties and biocompatibility. In the case of blend of UHMPE with another polymeric biomaterials, however, UHMWPE might have low blend compatibility due to surface inertness. In this study, in order to improve the mechanical properties of poly(methyl methacrylate) (PMMA) bone cement by means of the impregnation of UHMWPE powder, we developed the novel surface modification method by the mixture of methyl methacrylate (MMA) and xylene. We investigated the variation of composition of MMA/xylene. It was confirmed by the analysis of Fourier transform infrared-attenuated total reflectance, scanning electron microscope, universal transverse mercator, and digital thermometer. The maximum mechanical strength of surface modified UHMWPE powder impregnated PMMA bone cement compound was observed the ratio of 1 : 1 (v/v％) MMA/xylene. Also its curing temperature decreased from 103 $^{\circ}C$ to 58 ∼ 73 $^{\circ}C$ The mechanism of surface modification of UHMWPE powder by the mixture of MMA/xylene has been proposed.

• Membrane Journal
• /
• v.22 no.2
• /
• pp.120-127
• /
• 2012

In this study, separation of ethylbenzene from mixed xylene was performed by using TS-1 zeolite membrane. TS-1 zeolite membranes were prepared by microwave synthesis and changing the reaction temperature. MFI-type TS-1 membranes are synthesized on alumina tubes by functional coating using 3-chloropropyltrimethoxysilane (3CP-TMS). On top surface of interlayer, nano TS-1 crystals were seeded. To form interlayer, microwave-assisted growth of TS-1 zeolite was carried out and thin zeolite layers were produced. All of the prepared membranes are tested to separate ethylbenzene from mixed xylene at different operating temperatures. TS-1 membrane with zeolite seed synthesized at $170^{\circ}C$ compared to 120, $140^{\circ}C$ shows the best ethylbenzene separation at the operation temperature of $200^{\circ}C$ from ternary mixed xylene containing certain composition of ethylbenzene/p-xylene/m-xylene. (separation factor : 2.64, ethylbenzene flux : 1703.0 mol/$m^2{\cdot}s{\cdot}Pa$).

• Journal of Environmental Science International
• /
• v.12 no.4
• /
• pp.487-496
• /
• 2003

The purpose of this study was to develop the preliminary source fingerprints of volatile organic compounds (VOC). The source categories studied were vehicles, gasoline vapor, gasoline storage tank, coating, dry cleaning and road covering. The source samples were collected using 6L electro-polished stainless steel canisters for about 20 seconds. From this study, the main component emitted from VOC sources in Korea was toluene. The toluene proportion for road covering, vehicles, coating and gasoline vapor were 35, 18, 16 and 5%, respec- tively. The C$_2$-C$\sub$5/ alkane and alkene compounds were mainly emitted from vehicles, gasoline vapor and gasoline storage tank. The main compounds of coating were m/p-xylene(34%), toluene(16%), 1,2,4-TMB(10%) and o-xylene(9%), which are aromatic hydrocarbons. In the case of dry cleaning, nonane(41%), 1,2,4-TMB (22%) and 1,3,5-TMB(13%) were mainly emitted.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.1
• /
• pp.79-84
• /
• 2008

This paper describes the application of bioluminescence stimulating agents on a genetically engineered microorganism, Pseudomonas putida mt-2 KG1206, to monitor toluene analogs using in groundwater samples from petroleum hydrocarbon contaminated sites. The maximum bioluminescent response with pure chemicals followed in the order: m-methyl benzyl alchohol > m-toluate > toluene > m-xylene > benzoate > p-xylene > o-xylene. Generally, the bioluminescence production of strain mixed with groundwater samples was dependent on the contaminated total inducer concentrations. However, few samples showed opposite results, where these phenomena may be caused by the complexicity of environmental samples. Two chemicals, SL(sodium lactate) and KNO$_3$, were tested to determine a better bioluminescence stimulant. Both chemicals stimulate the bioluminescence activity of strain KG1206, however, a slightly high bioluminescence was observed with nitrogen chemical. This selected stimulant was then tested on samples collected from contaminated groundwater samples. The bioluminescence activity of all samples mixed with the strain was stimulated with KNO$_3$ amendment. This suggests that the low bioluminescence activity exhibited by the environmental groundwater samples can be stimulated by amending the culture with a proper agent, such as nitrogen compound. These findings would be useful, especially, when strain was used to monitor the groundwater samples contaminated with low inducer contaminants. Overall, the results of this study found the ability of bioluminescence producing bacteria to biosensor a specific group of environmental contaminants, and suggest the potential for more efficient preliminary application of this engineered strain in a field-ready bioassay.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.3 no.2
• /
• pp.177-187
• /
• 1993

The exposure levels of mixed organic solvents for 66 exposed workers in six paint manufacturing plants were evaluated. In 66 exposed workers and 30 control subjects, we also determined the concentrations of toluene and xylene metabolites, hippuric acid, ($o^-$, $m^-$, and $p^-$)methylhippuric acid. The results were as follow ; 1. Seven organic compounds, which on averge accounted for approximately 90% of the identified mass in each painting plants air samples, were selected for quantification : methyl ethyl ketone, ethyl acetate, methyl isobutyl ketone, toluene, butyl acetate, ethyl benzene, ($o^-$, $m^-$, $p^-$)xylene. 2. The average mixed organic solvent exposure levels in 66 points with workplce were 3.8ppm of MEK, 12.2ppm of ethyl acetate, 4.0ppm of MIBK, 28.7ppm of toluene, 3.8ppm of butyl acetate, 10.2ppm of ethyl benzene, 14.6ppm of xylene, respectively. 3. For the total 66 points with workplace, the rate of them of which mixed solvents in air was exceeded th TLV of 1.0 were obtained for 23%(15/66 point). 4. The concentrations of hippuric acid in urine of exposed group and control were $0.94{\pm}0.65g/g$ of creatinine, $0.16{\pm}0.11g/g$ of creatinine, respectively. 5. There was a linear correlation between the end shift hippuric acid acid levels in urine and exposed toluene in air : y=0.02079X+494.2, r=0.6488, n=55 y:hippuric acid in urine(mg/g of creatinine), x:toluene levels in air(ppb) Toluene levels of 100ppm in air have been caculated to hippuric acid of 2.57g/g of creatinine in urine. 6. There was a linear correlation between the end shift methylhippuric acid acid levels in urine and exposed xylene in air : y=0.01664X+31.6, r=0.7264, n=55 y:methylhippuric acid in urine(mg/g of crea.), x:xylene levels in air(ppb) Xylene levels of 100ppm in air have been caculated to methylhippuric acid of 1.69g/g of creatinine in urine.

• Microbiology and Biotechnology Letters
• /
• v.41 no.3
• /
• pp.272-277
• /
• 2013

In this study, the tar compounds derived from the plant cell cultures of Taxus chinensis were first identified and then quantified via gas chromatography/mass spectrometry (GC/MS) and gas chromatography (GC). 2-Picoline, 2,5-xylenol, acenaphthene, 1-methylnaphthalene and o-xylene were found to be the major tar compounds by biomass. These compounds were identified and confirmed by comparing their retention times with those of authentic compounds. Each compound also spiked with the pure standard. The contents of 2-picoline, 2,5-xylenol, acenaphthene, 1-methylnaphthalene, and o-xylene in biomass were 0.2512, 0.1586, 0.1240, 0.0942 and 0.0525 wt%, respectively. Liquid-liquid extraction and adsorbent treatment were able to remove 42% and 94% of the tars from biomass, respectivly. After hexane precipitation, all of the tars were perfectly removed.

• Journal of Preventive Medicine and Public Health
• /
• v.14 no.1
• /
• pp.97-110
• /
• 1981

This study was conducted in order to investigate the status of harmful working environ ment on twelve rubber and ten chemical products manufacturing industries in Busan area over a period of five months from lune 1 to October 31, 1980. The summarized results were as follows: 1. The highest and lowest mean values of harmful environmental elements in workroom of rubber products manufacturing industries were noted in twisting (98.7dB) and coating department (77.3dB) to noise, molding ($6.43mg/m^3$) and forming ($1.33mg/m^3$) to dust, bonding (toluene 463.7ppm, xylene 457.8ppm and benzene 111.8ppm, respectively) and splicing (toluene 90.0ppm, xylene 83.3ppm and benzene 6.7ppm, respectively) to organic solvents, respectively. Also in chemical products manufacturing, they were noted in grinding (95.1dB) and shining department (76.8dB) to noise, packing ($4.30mg/m^3$) and staining ($3.20mg/m^3$) to dust, shining (393.3ppm and 375.0ppm, respectively) and varnishing(125.5ppm and 121.7ppm, respectively) to toluene and xylene, and scattering (51.8ppm) and mixing (23.9ppm) to benzene, respectively. 2. The mean values of harmful elements in workroom of rubber products manufacturing were 86.3dB to noise, $4.16mg/m^3$ to dust, 258.2ppm to toluene, 230.3ppm to xylene, and 5 4.0ppm to benzene, respectively. Also in chemical products manufacturing, they were 85.2dB to noise, $3.69mg/m^3$ to dust, 227.9ppm to toluene, 213.2ppm to xylene, and 36.3ppm to benzene, respectively. 3. Number of workers exposed to harmful working environment, over TLV, of a total 10,195 workers in rubber products manufacturing were 1,002(9.8%) to noise, 212 (2.1%) to dust, 1,581(15.5%) to toluene, 1,509(14,8%) to xylene, and 1,524(15.0%) to benzene, respectively. Number of workers exposed to harmful working environment, over TLV, of a 1,913 workers in chemical products manufacturing were 112(5.9%) to noise, 132(6.9%) to each organic solvent, respectively. 4. The values of noise and dust of rubber and chemical products manufacturing in 1980 were lower then those in 1977, but the value of organic solvent in 1980 was similar with that in 1977.

• Resources Recycling
• /
• v.11 no.6
• /
• pp.38-46
• /
• 2002

Fundamental investigations were conducted far the recovery process of waste organic solvent by fractional distillation in the aspects of equilibrium and kinetics. Mixture of toluene and xylene, which were both being used in the largest amount as industrial organic solvent, was taken as the artificial waste organic solvent and their distillation behaviors were studied. The purity of recovered solvent was investigated by Cir Chromatography and shown to be in the range of 94～98%. Based upon equilibrium calculations, the changes in the Gibbs free energy, standard enthalpy, and standard entropy for distillation reaction have been estimated. The standard enthalpy changes for toluene and xylene were shown to be 44.833 and 47.044 kJ $mol^{-1}$ respectively, which were similar to their molar heats of evaporation. The activation energies of distillation fur toluene and xylene obtained from kinetic studies were 3.281 and 2.699 kJ $mol^{-1}$ and they were about one tenths of the standard enthalpy changes of distillation reaction. The highness of the purity of recovered organic solvents suggested the possibility that the recovered waste organic sol-vent could partly replace the original solvent.

• Journal of the Korean Chemical Society
• /
• v.30 no.4
• /
• pp.369-376
• /
• 1986

Diosgenin in an Indonesian Costus speciosus was determined by capillary gas-liquid chromatography (GLC). The experimental conditions for the hydrolysis, extraction and acetylation of the diosgenin, and the determination by GLC were investigated. 0.20g of dried sample powder was refluxed in the solution of 3N HCI and xylene at 95∼100${\circ}C$ for 4 hours and the xylene layer was separated. The residue evaporated the xylene was refluxed in 20 : 80 acetic anhydride-pyridine for 30 minutes and the diosgenin acetate was extracted with diethyl ether. Dehydrated with anhydrous $Na_2SO_4$ and evaporated the ether, the residue was dissolved in 5.00ml of n-hexane and injected into GLC. Capillary column of SE-30 25m ${\times}$ 0. 33mm was installed in GLC and the column temperature was increased from 180${\circ}$ to 270${\circ}C$ at rate of 10${\circ}C$/min. The flow rate of carrier gas $N_2$ was 2ml/min and FID was used to detect. The analytical result of the diosgenin was 0.281% and relative standard deviation of 5 measures was 1.8%.

• Journal of the Korean Chemical Society
• /
• v.56 no.1
• /
• pp.7-13
• /
• 2012

Ultrasonic velocities (u) for binary mixtures of propylene carbonate (PC) (1) with benzene and substituted benzenes (2) viz. benzene, ethylbenzene, o-xylene and p-xylene have been measured at 288.15-308.15 K over the entire range of composition. The experimental values of ultrasonic velocities (u) have been utilized to calculate isentropic compressibility ($K_s$), intermolecular free length ($L_f$), acoustic impedance (Z).