• Archives of Pharmacal Research
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• 제28권1호
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• pp.120-126
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• 2005

The objective of this study was to investigate the effects of sodium lauryl sulfate upon the saturation solubility of carbamazepine, its dissolution kinetics, and $T_{50\%}$ defined as the time required for dissolving $50\%$ of carbamazepine. Water, 0.1N-HCI, and phosphate buffers at pH 4.0 and 6.8 containing 0.1, 0.5, 1, and $2\%$ sodium lauryl sulfate were used as dissolution media. The dissolution study was conducted by using the USP dissolution apparatus II with an agitation rate of 75 rpm. Samples of the dissolution media were taken in 7, 15, 30, 45, 60, 75, and 90 min, and the amounts of carbamazepine were determined spectrophotometrically at 285 nm. All dissolution data were fitted well into a four-parameter exponential equation: $Q\;=\;a(1\;-\;e^{-bxt})\;+\;c(1\;-\;e^{-dxt})$. In this equation Q represented $\%$ carbamazepine dissolved at a time t, and a, b, c, and d were constants. This equation led to the calculation of dissolution rates at various time points and $T_{50\%}$. It was found that the dissolution rate of carbamazepine was directly proportional to the aqueous concentration of sodium lauryl sulfate. In addition, under our experimental conditions $T_{50%}$ values ranged from 37.8 to 4.9 min. It was interesting to note that $T_{50\%}$ declined rapidly as the surfactant concentration increased from 0.1 to $0.5\%$, whereas it declined more slowly at concentrations greater than $1\%$. These results clearly demonstrated that the dissolution rate of carbamazepine and duration of its dissolution test could be tailored by optimizing the amount of sodium lauryl sulfate in a dissolution medium.

• Fisheries and Aquatic Sciences
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• 제12권4호
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• pp.350-353
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• 2009

As a result of human industrial development, carbon dioxide ($CO_2$) is currently accumulating in the atmosphere and dissolving into the oceans. Sequestration into the deep sea has been proposed as a possible solution to this increasing atmospheric $CO_2$, although the impact of such a program on marine ecosystems is unknown. We examined the effects of increased $CO_2$ levels on the growth of the olive flounder, Paralichthys olivaceus. Juvenile olive flounder 40 days post hatching were exposed to two levels of $CO_2$ (3.60-7.55 and 4.05-11.46 kPa) in running seawater for 26 days. During the exposure period, the pH and $CO_2$ levels of the water were measured, and the numbers of dead individuals were counted in each aquarium. Following the exposure period, the total lengths (mm) and body weights (mg) of the juvenile fish were measured. Both $CO_2$ treatments significantly increased fish mortality compared to controls ($19.87\pm4.53%$ vs. 7.14% and $75.96\pm1.36%$ vs. 7.14% for high and low doses, respectively). After the high $CO_2$ treatment, total length ($14.98\pm6.58$ mm vs. $19.52\pm1.83$ mm) and body weight ($28.92\pm13.85$ mg vs. $67.35\pm18.32$ mg) of the exposed flounder were reduced compared to the control fish; however, no significant differences in these values were observed after the low $CO_2$ dose. These results suggested that $CO_2$ exposure inhibits growth in the juvenile stage and that $CO_2$-enriched seawater is toxic in the early life stages of olive flounder.

• 한국환경보건학회지
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• 제38권6호
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• pp.568-574
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• 2012

Objectives: The purpose of this experiment is to understand the phosphorus removal ratio effects of iron plates per unit of surface area through the iron electrolysis system, which consists of an anoxic basin, aerobic basin, and iron precipitation apparatus. Methods: Iron electrolysis, which uses an iron precipitation reactor in anoxic and oxic basins, consisted of iron plates with total areas of 400 $cm^2$, 300 $cm^2$ and 200 $cm^2$ respectively. The FNR process was operated with a hydraulic retention time and a sludge retention time of 12 hours and three days, respectively. Wastewater used in the experiments was prepared by dissolving $KH_2PO_4$ in influent water. Results: The iron plates 400 $cm^2$ (16.6 $mA/cm^2$), 300 $cm^2$ (13.3 $mA/cm^2$) and 200 $cm^2$ (7.3 $mA/cm^2$) in surface area in the phosphorus reactor had respective phosphorus of 2.4 mg/l, 2.7 mg/l and 3.2 mg/l in the effluent and phosphorus removal respective efficiencies of 90.3%, 89.1% and 87.1%. The effluent in the reactor, where the iron plate was not used, had relatively very low phosphorus removal efficiency showing phosphorus concentration of 15.3 mg/l and a phosphorus removal efficiency about 38.3%. Phosphorus removal per ferrous was 0.472 mgP/mgFe in the iron electrolysis system where the surface area of iron was low. Phosphorus pollution load per active surface area and the phosphorus removal efficiency had an interrelation of RE = -0.27LS + 89.0 (r = 0.85). Conclusion: With larger iron plate surface area, the elution of iron concentration and phosphorus removal efficiency was higher. The removal efficiency of phosphorus has decreased by increasing the initial phosphate concentration in the iron electrodes. This shows a tendency of decreasing phosphorus removal efficiency because of decreasing of iron deposition as the phosphorus pollution load per active surface area increases.

• Asian-Australasian Journal of Animal Sciences
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• 제7권3호
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• pp.389-396
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• 1994

Effects of chemical treatments on in sacco and in vitro digestibility of barley straw by rumen fluid and pure cultures of cellulolytic bacteria were studied to evaluate the pretreatment and to improve the poor quality feed. Chemicals were applied by dissolving them in water equivalent to 40% of the weight of the straw (dry matter basis). Pretreatment with 5% NaOH yielded the largest increase in sacco digestion followed by pretreatment with 2% $(NH_4)_2SO_3$, 2.6% $NH_4OH$, 1.6% $NaHSO_3$ and untreated straw (control). In sacco dry matter digestibility of straw treated with NaOH and $(NH_4)_2SO_3$ continued to increase as the concentration of chemical increased (1 to 7.5%), as it was the in vitro dry matter loss by leaching. Treatment of barley straw with 5% NaOH enhanced significantly (p < 0.01) in vitro digestibility by rumen fluid, Fibrobacter suceinogenes and Ruminococcus albus though the fermentation products by cellulolytic bacteria were low, whereas the treatment with 5% $(NH_4)_2SO_3$ inhibited in vitro digestibility by F. succinogenes and R. albus together with lower fermentation products. Dry matter loss by leaching and bacterial digestion from barley straw treated with NaOH and $(NH_4)_2SO_3$ suggested the effect of pretreatment with these chemicals were based on leaching, and the cellulolytic bacteria had little to do with digestion.

• 한국표면공학회지
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• 제50권1호
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• pp.29-34
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• 2017

Chloride plating solution was fabricated by dissolving metal Ni powders in a mixed solution with HCl and de-ionized water. Effects of $Ni^{2+}$ and saccharin concentrations in the plating baths on current efficiency, residual stress, surface morphology and microstructure of Ni films were studied. In the case of $0.2M\;Ni^{2+}$ concentration, current efficiency was decreased to about 65 % with increasing saccharin concentration, but, in the case of $0.7M\;Ni^{2+}$ concentration, it was shown more than 90 % with the increase of saccharin concentration. Residual stress of Ni thin film was appeared to be about 400 MPa up to 0.0244 M saccharin concentration at the $0.2M\;Ni^{2+}$ concentration and surface morphology with severe cracks was observed in the range of 0.0487~0.0975 M saccharin concentration. Residual stress of Ni thin films was measured to be about 750 MPa without saccharin addition and 114~148 MPa at the range of 0.0097~0.0975 M saccharin concentration for the $0.7M\;Ni^{2+}$ concentration. Relatively low residual stress values (114~148 MPa) of the Ni films at the range of 0.0097~0.0975 M saccharin concentration may be resulted from codeposition of S from saccharin. Ni films at $0.7M\;Ni^{2+}$ concentration showed smooth surface morphology and were independent of saccharin concentration. Ni films at $0.7M\;Ni^{2+}$ concentration consist of FCC(111), FCC(200), FCC(220) and FCC(311) peaks and the intensities of FCC(111) and FCC(200) peaks increased with increasing saccharin concentration. Also, the average grain size decreased with increasing saccharin concentration from about 30 nm to about 15 nm.

• Restorative Dentistry and Endodontics
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• 제14권2호
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• pp.65-76
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• 1989

The purpose of this study was to observe the effect on the removal of dentinal smear layer and morphological changes of reduced dentin surfaces by various dentin surface conditioners. Thirty-two healthy human premolars extracted due to periodontal or orthodontic reasons were used. The teeth were cross-sectioned to expose dentin at the middle portion of the crown with diamond rotary saw. The specimens were then divided into 8 groups. The sectioned dentin surfaces in group 1 to 4 were grinded with No. 400 grit silicone abrasive paper and those in group 5 to 8 were cut with #700 carbide bur under air-water spray. The grinded or cut dentin surfaces were conditioned with 3% $H_2O$, Dentin Conditioner(GC Inter. Corp., Japan), and Scotchprep(3M Dent Prod., U.S.A) according to manufacturer's directions. All the specimens were dried in room temperature for 48 hours, and gold-coated with Eiko ion coater(Eik-engineering Co.), and observed in Hitachi S-450 Scanning electron microscope at 15-25 KV. The following results were obtained; 1. The dentin surfaces grinded with the silicon abrasive paper were rougher in texture and heavier in amount of smear layer than those cut with the carbide bur. 2. Scrubbing of 3% $H_2O_2$ was not effective in removing dentinal smear layer. 3. 20-second conditioning of Dentin Conditioner (GC Inter. Corp) resulted in the removal of a significant amount of the smear layer without removing the tubular plugs and dissolving the peritubular dentin. 4. Scotchprep removed the smear layer very effectively. But at the same time it dissolved the peritubular dentin. 5. Irrespective of the uses of the silicon carbide abrasive paper or the carbide bur the morphological changes of dentin surfaces treated with the same conditioning agents were similar.

• Journal of Pharmaceutical Investigation
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• 제34권3호
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• pp.185-192
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• 2004

The objective of this study was to evaluate the effects of surfactant type and concentration upon dissolution rates of carbamazepine from an immediate-release tablet. The dissolution media used in this study were aqueous solutions containing 0.1-2% sodium lauryl sulfate, cetyltrimethylammonium bromide, or polysorbate 80. The solubility of carbamazepine in the dissolution media was determined at first. A dissolution study was then conducted by using the USP dissolution apparatus II (paddle method) with an agitation rate of 75 rpm. Aliquots of the dissolution media were taken at predetermined time intervals, and the amount of carbamazepine dissolved was measured spectrophotometrically at 285 nm. The dissolution data obtained were fitted into a biphasic exponential equation with four parameters. Excellent correlations were observed between the experimental data and the theoretical ones predicted by the equation. This equation permitted the calculation of $T_{50%}$ (the time required for dissolving 50% of carbamazepine) under various experimental conditions. Differentiation of the equation also led to the attainment of dissolution rates at dissolution time points. The addition of a surfactant to an aqueous solution led to increasing the solubility of carbamazepine by 3- to 12-folds, depending upon its type and concentration. This event also resulted in enhancing the magnitude of a sink condition during the dissolution study. As a result, the dissolution rate of carbamazepine was affected by the aqueous surfactant concentration in a proportional manner. Subsequently, $T_{50%}$ values declined rapidly, as the surfactant concentration increased. Such effects were observed in decreasing order of sodium lauryl sulfate, cetyltirmethylammonium bromide, and polysorbate 80. These results clearly demonstrated that it was possible to tailor a dissolution rate and $T_{50%}$ of carbamazepine by manipulating the type and concentration of a surfactant. Relevant information would be beneficial to setting up dissolution specifications for poorly water-soluble drug products.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.531-538
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• 2013

A mass balance method established in this laboratory was applied to determine the purity of an endosulfan-II pure substance. Gas chromatography-flame ionization detector (GC-FID) was used to measure organic impurities. Total of 10 structurally related organic impurities were detected by GC-FID in the material. Water content was determined to be 0.187% by Karl-Fischer (K-F) coulometry with an oven-drying method. Non-volatile residual impurities was not detected by Thermal gravimetric analysis (TGA) within the detection limit of 0.04% (0.7 ${\mu}g$ in absolute amount). Residual solvents within the substance were determined to be 0.007% in the Endosulfan-II pure substance by running GC-FID after dissolving it with two solvents. The purity of the endosulfan-II was finally assigned to be ($99.17{\pm}0.14$)%. Details of the mass balance method including interpretation and evaluating uncertainties of results from each individual methods and the finally assayed purity were also described.

• 청정기술
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• 제14권1호
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• pp.35-39
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• 2008

본 연구에서는 용매에 따른 고분자의 용해도 차이를 이용하여 슬라이드글라스 표면위에 초소수성 고분자막을 성공적으로 제조하였다. 폴리스타이렌 (PS)을 tetrahydrofuran (THF)에 녹인 후 다시 에탄올(EtOH)을 첨가하여 두 용매의 용해도 차이로 표면에 초소수성 성질을 갖게 제조하였다. 한편, EtOH 첨가, 코팅방법, 용액혼합 시간과 속도 및 다른 알콜들이 형성된 표면의 소수성에 미치는 영향들을 각각 조사하였다. 접촉 각 측정기를 사용하여 측정한 결과 $150^{\circ}$ 이상의 물 접촉각을 확인하였고, 광학현미경(optical microscopy)과 주사전자현미경(scanning electron microscope, SEM)으로 관찰한 표면 구조는 $5\;{\mu}m$ 이하의 입자들로 구성된 미세다공성 구조임이 확인되었다.

• Nuclear Engineering and Technology
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• 제45권2호
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• pp.203-210
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• 2013

The objective of this conducted research is to study the iodine removal efficiency in a self-priming venturi scrubber for submerged and non-submerged operating conditions experimentally and theoretically. The alkaline solution is used as an absorbent, which is prepared by dissolving sodium hydroxide (NaOH) and sodium thiosulphate ($Na2S_2O_3$) in water to remove the gaseous iodine ($I_2$) from the gas. Iodine removal efficiency is examined at various gas flow rates and inlet concentrations of iodine for submerged and non-submerged operating conditions. In the non-submerged venturi scrubber, only the droplets take part in iodine removal efficiency. However, in a submerged venturi scrubber condition, the iodine gas is absorbed from gas to droplets inside the venturi scrubber and from bubbles to surrounding liquid at the outlet of a venturi scrubber. Experimentally, it is observed that the iodine removal efficiency is greater in the submerged venturi scrubber as compare to a non-submerged venturi scrubber condition. The highest iodine removal efficiency of $0.99{\pm}0.001$ has been achieved in a submerged self-priming venturi scrubber condition. A mathematical correlation is used to predict the theoretical iodine removal efficiency in submerged and non-submerged conditions, and it is compared against the experimental results. The Wilkinson et al. correlation is used to predict the bubble diameter theoretically whereas the Nukiyama and Tanasawa correlation is used for droplet diameter. The mass transfer coefficient for the gas phase is calculated from the Steinberger and Treybal correlation. The calculated results for a submerged venturi scrubber agree well with experimental results but underpredicts in the case of the non-submerged venturi scrubber.