• Journal of the Korean Ceramic Society
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• v.34 no.8
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• pp.886-896
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• 1997

To investigate an effect of phase separation on precipitation characteristics of CuCl nanocrystals in CuCl doped nonlinear optical glasses, borosilicate glass systems with 9 different compositions with ~2wt% of CuCl were selected and CuCl doped glasses were prepared by melting and precipitation method. Microstructural properties of the CuCl doped glasses were analyzed by optical absorption spectroscopy, acid elution test, TEM, and EDXS. While phase separation did not occur in Glass A~D, interconnected and droplet microstructures due to phase separation were found in Glass E, F and Glass G~I, respectively. In the particular composition of the matrix glasses in this study, the precipitation of the CuCl particles was observed in the phase separable glasses, not in phase non-separable glasses. The CuCl particles were precipitated in both silica-rich phase region and boronrich phase region of the glass matrix. In the case of 7.7Na2O-36.6B2O3-52.7SiO2(mole%) glass, the larger CuCl particles than those in the silica-rich phase region were observed in the boron-rich phase region.

• The Korean Journal of Food And Nutrition
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• v.3 no.2
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• pp.207-210
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• 1990

Paper chromatography and (NH4)2SO4 precipitation method were used for refinement and separation of proteins Color reaction was tested by Biuret test, Million test, Xanthoprotein test, and Ninhydrin test. Precipitation reaction and coagulation of proteins were tested by heating method (Ethanol, HNO3).

• Progress in Superconductivity and Cryogenics
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• v.21 no.2
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• pp.15-21
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• 2019

In the mine exploration sites, sustainable treatment system of mine water with energy saving and minimized chemical additives is required. Since most of the mine water contains highly-concentrated ferrous ion, it is necessary to study on the removal method of iron ions. We propose the system consisting of two processes; precipitation process by air oxidation using solid catalyst-modified magnetite and separation process combining gravitational sedimentation and magnetic separation using a permanent magnet. Firstly, in the precipitation process (a former process of the system), we succeeded to prepare solid catalyst-modified magnetite. Air oxidation using solid catalyst-modified magnetite using $Fe_2(SO_4)_3$ as a starting material showed high iron removal capability. Secondly, in the separation process (latter process of the system), solid catalyst-modified magnetite using $Fe_2(SO_4)_3$ as a starting material can be separated by a superconducting bulk magnet and a permanent magnet.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.10a
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• pp.45-46
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• 1995

Generally, two different techniques have been employed for the precipitation of membranes from a polymer casting solution. In the first method, a precipitant is introduced from a vapor phase. In this case the precipitaion rate is very slow and a more or less symmetric structure is formed. In the second method, a precipitant is added to a casting solution by immersing the cast polymer film in a nonsolvent bath. In this case the precipitation rate is very fast and a skinned asymmetric membrane structure is obtained. In this study, we introduced water-vapor to PSf/NMP solution and took photographs of phase separation phenomena of polymer lean phase.

• Journal of Environmental Science International
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• v.15 no.3
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• pp.253-260
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• 2006

Groundwater recharge from precipitation is affected by the infiltration from ground surface and the movement of soil water. Groundwater recharge is directly related to the groundwater amount and flow in aquifers, and baseflow to rivers. Determining groundwater recharge rate for a given watershed is a prerequisite to estimate sustainable groundwater resources. The estimation of groundwater recharge rate were carried out for three subwatersheds in the Wicheon watershed and two subwatersheds in the Pyungchang River basin and for the period 1990-2000, using the NRCS-CN method and the baseflow separation method. The recharge rate estimates were compared to each other. The result of estimation by the NRCS-CN method shows the average annual recharge rate 15.4-17.0% in the Wicheon watershed and 26.4-26.8% in the Pyungchang River basin. The average annual recharge rates calculated by the baseflow separation method ranged 15.1-21.1% in the W icheon watershed, and 25.2-33.4% in the Pyungchang River basin. The average annual recharge rates calculated by the NRCS-CN method is less variable than the baseflow separation method. However, the average annual recharge rates obtained from the two methods are not very different, except NO. 6 subwatershed in Pyungchang River basin.

• Analytical Science and Technology
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• v.18 no.6
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• pp.469-474
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• 2005

This paper presents a quantitative method of sequential separation of $^{90}Sr$, $^{241}Am$ and Pu radionuclides with an anion exchange resin and a Sr-Spec resin. The Pu isotopes were purified with an anion exchange resin. The americium and strontium fractions were separated from the matrix elements with an oxalate co-precipitation method. Americium fraction was separated from the strontium fraction with iron co-precipitation method and purified from lanthanides with anion exchange resin. Strontium-90 was purified from other hindrance elements with the Sr-Spec resin after oxalate co-precipitation. The measurement of Pu and Am isotopes was carried out by an ${\alpha}$-spectrometer. Strontium-90 was measured by a liquid scintillation counter. The radiochemical procedure of $^{90}Sr$, $^{241}Am$ and Pu radionuclides investigated in this study has been validated by application to IAEA-Reference soils.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2003.10a
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• pp.196-200
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• 2003

A novel prepurification method was developed aiming at increasing yield and purity, also reducing solvent usage for purification of paclitaxel. The use of a micelle and precipitation in the prepurification process allows for rapid separation of paclitaxel from interfering compounds and dramatically reduces solvent usage compared to alternative methodologies. The prepurification process serves to minimize the size and complexity of the HPLC operations for paclitaxel purification. The process is readily scalable to a pilot plant and eventually to a production environment where multikilogram quantities of material are expected to be produced. As much as possible, the process has been optimized to minimize solvent usage, complexity, and operating costs.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.501-504
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• 2003

A novel prepurification method was developed aiming at increasing yield and purity, also reducing solvent usage for purification of paclitaxel. This method was a simple and efficient procedure, for the isolation and prepurification of paclitaxel from the biomass of Taxus chinensis, consisting of micelle formation, followed by two steps of precipitation. The use of a micelle and precipitation in the prepurification process allows for rapid separation of paclitaxel from interfering compounds and dramatically reduces solvent usage compared to alternative methodologies. This prepurification process serves to minimize the size and complexity of the HPLC operations for paclitaxel purification. This process is readily scalable to a pilot plant and eventually to a production environment where multikilogram quantities of material are expected to be produced. As much as possible, the process has been optimized to minimize solvent usage, complexity, and operating costs.

• Macromolecular Research
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• v.9 no.5
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• pp.285-291
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• 2001

The polysulfone(PSf)/polyethersulfone(PES) blend membranes were prepared by an immersion precipitation method. N-methyl-2-pyrrolidone(NMP) was used as a solvent and water as a nonsolvent. The composition of the coagulation bath and the dope polymer concentration as well as the blend ratio of two polymers were varied. The membrane morphologies were interpreted on the basis of the phase diagram of the PSf/PES/NMP/water system. As the solvent content in the coagulation bath increased in the single polymer system, the number of macrovoids decreased and the morphology was changed from finger-like to cellular structure. In the given bath condition phase separation occurs earlier for the solutions of PSf/PES blend than for those of single polymer. A horizontally layered structure and horizontal protuberances inside the macrovoid were observed for the membranes formed from PSf/PES blend solutions. This peculiar structure formation can be interpreted by a PSf-rich/PES-rich phase separation followed by a polymer-rich/polymer-lean phase separation during the exchange of solvent and nonsolvent.

• Journal of Microbiology and Biotechnology
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• v.12 no.3
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• pp.522-525
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• 2002

A very rapid and efficient separation technique for cellular rhizobial cyclosophoraoses was developed based on fractional precipitation and partition chromatography. Cyclosophoraoses are known to function in the osmotic regulation and root nodule formation of legumes during the nitrogen fixation process. Cyclosophoraoses are produced as unbranched cyclic (1longrightarrow12)-${\beta}$-D-glucans in Agrobacterium or Rhizobium species. Recent research has shown that cyclosophoraoses can form inclusion complexation with various unstable or insoluble guest chemicals, thereby implying great potential for industrial application. Typical separation of pure cellular cyclosophoraoses has been so far carried out by several time-consuming steps, including size exclusion, anion exchange, and desalting liquid chromatographies, with a relatively poor recovery. However, the proposed method demonstrated that the successive application of fractional ethanol precipitation and one step of silica gel-based flash column chromatography was enough to simultaneously purify neutral or anionic forms of cyclosophoraoses. This novel technique is very rapid and provides a high recovery.