• 한국식품영양과학회지
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• 제28권2호
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• pp.348-352
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• 1999

We have intended to accelerate the secretion of human lysozyme(HLY) with permeabilizing agents from the cultivated cells of the recombinant Saccharomyces cerevisiae. The five agents CaCl2, Tween 80, ethanol, Triton X 100, and cetyltrimethylammonium bromide(CTAB) were used as permeabilizing agents. Treatments of the yeast cell with CaCl2, Tween 80, and ethanol were effective to increase the secretion from the yeast cells. Especially, treatment of 10% ethanol increased the extracellular HLY activity by 38.6% at 30oC for 48 h in culture broth. But Triton X 100 and CTAB unexpectedly didn't play a role in increase of HLY secretion. Recovery of a foreign protein by permeabilizing agents is easier than by osmotic shock, and is less expensive than enzymatic digestion.

• 자원환경지질
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• 제38권6호
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• pp.657-662
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• 2005

Extractions fro fertilizer and soil samples were performed to yield the operationally defined fractions 'soluble' chromate (extractable with $NH_4NO_3$), 'exchangeable' chromate (extractable with phosphate buffer pH 7.2), and these results were compared with the data obtained by extractions with ammonium sulfate, borate buffer pH 7.2, saturated borax pH 9.6, and polyphosphate (Graham's salt). In order to maintain the pH of extractant solution about constant, the concentration of extractant buffer had to be raised to at least 0.5 M. The results strongly depended on the kind of extractant, and the solid: liquid ratio. For most of the samples investigated, the extraction efficiency increased in the order borate-sulfate-nitrate-phosphate. Whereas the recovery of $K_2CrO_4\;and\;CaCrO_4$ added to the samples of basic slags prior to the extraction was about complete, the recovery of added $PbCrO_4$ was highly variable. In soil extracts, the color reaction was interfered from co-extracted humics, which react with the chromate in weak acid solution during the time period necessary for color reaction (1 hour). However, this problem can be overcome by standard addition and subtraction of the color of the extractant solution. In soil extract of about pH < 7, organic material reduced chromate during the extraction period also, and standard addition of soluble chromate is recommended to prove recovery and the stability of chromate in the samples. In admixtures of soils and basic slags, results for hexavalent chromium were lower than from the mere basic slags. This effect was more pronounced in phosphate than in nitrate extracts. As a proficiency test, samples low in organic carbon from contaminated sites in Hungary were tested. The results from $NH_4NO_3$ extracts satisfactorily matched the results of the Hungarian labs obtained from $CalCl_2$ extractants.

• 멤브레인
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• 제17권2호
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• pp.93-98
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• 2007

The reliability of innovative membrane contactors technology (i.e. Gas/Liquid Membrane Contactors, Membrane Distillation/Crystallization) is today increasing for seawater desalination processes, where traditional pressure-driven membrane separation units are routinely operated. Furthermore, conventional membrane operations can be integrated with membrane contactors in order to promote possible improvements in process efficiency, operational stability, environmental impact, water quality and cost. Seawater is the most abundant aqueous solution on the earth: the amount of dissolved salts covers about 3% of its composition, and six elements (Na, Mg, Ca, K, Cl, S) account for more than 90% of ionic species. Recent investigations on Membrane Distillation-Crystallization have shown the possibility to achieve significant overall water recovery factors, to limit the brine disposal problem, and to recover valuable salts (i.e. calcium sulphate, sodium chloride, magnesium sulphate) by combining this technology with conventional RO trains. In this work, the kinetics of $CaSO_4{\cdot}2H_2O,\;NaCl\;and\;MgSO_4{\cdot}7H_2O$ crystallization is experimentally investigated in order to improve the design of the membrane-based crystallization unit.

• 한국광물학회지
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• 제27권4호
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• pp.207-222
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• 2014

폐-광석으로부터 금속구리분말을 회수하기 위하여 더미 미생물용출, Fe 제거와 전기분해실험을 수행하였다. Cu가 0.034% 함유된 폐-광석시료에 대하여 더미 용출실험을 수행한 결과, Cu 용출률은 박테리아 용출-용액에서 61%, 황산 용출-용액에서 62%로 나타났다. Fe를 효과적으로 제거하기 위하여 더미 용출-용액에 NaOH, $H_2O_2$ 및 $Ca(OH)_2$를 각각 적용한 결과 $H_2O_2$가 가장 효과적인 Fe 제거제로 선정되었다. 전해질 용액을 준비하기 위하여 $H_2O_2$를 더미 용출-용액에 처리한 결과 박테리아 용출-용액에서 Fe가 99%, 황산 용출-용액에서 60%로 제거된 반면에 Cu 제거율은 각각 5%와 7%로 나타났다. 이 용액에 대하여 전기분해 실험을 수행한 결과 Cu 회수율이 박테리아 용출-용액에서 98%, 황산 용출-용액에서 76%로 나타났다. 모수석 형태의 금속구리분말이 양쪽 용출-용액에서 회수되었다.

• 방사성폐기물학회지
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• 제3권4호
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• pp.309-317
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• 2005

방사성 폐기물 핵종 재고량 평가에 필요한 핵종분석을 위하여 다양한 매질의 방사성 폐기물 시료로부터 $^{99}Tc,\;^{94}Ng,\;^{55}Fe,\;^{90}Sr$ 및 $^{59/63}Ni$의 분리에 관한 연구가 수행되고 있다. Ni은 음이온교환 수지와 Sr-Spec 추출 크로마토그래피 수지로 Re($^{99}Tc$의 대용물), Nb, Fe 및 Sr을 차례로 분리하는 과정에서 Ca, Mg, Al, Cr, Ti, Mn, Ce, Na, K 및 Cu와 함께 회수되었다. 본 연구에서는 Ni의 선택적 분리기술을 확립하기 위하여 Ni-Spec 추출 크로마토그래피 및 양이온교환수지법으로 이들의 분리거동을 비교하였다. 또한 Ni의 정제와 기체비례계수법으로 방사능을 측정하기에 적합한 계측시료 준비를 위하여 ammonium $citrate/ethanol-H_2O$ 및 tartaric $acid/acetone-H_2O$에서 dimethylglyoxime(DMG)에 의한 Ni의 침전거동을 조사하였다 원자력발전소로부터 채취한 폐이온교환수지 시료 용해용액의 화학조성을 모사하여 만든 모의 폐이온교환수지 용액을 사용하여 Re, Nb, Fe 및 Sr 분리과정을 거쳐 최종적으로 분리한 Ni의 회수율은 $92.1\%\;(RSD:\;0.9\%)$이었다. 또한 tartaric $acid/acetone-H_2O$에서 DMG에 의한 Ni의 회수율은 $85.6\%\;(RSD:\;1.9\%)$이었다.

• 암석학회지
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• 제2권1호
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• pp.32-40
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• 1993

The light pinkish granite (LPG) and pinkish granite (PG) distributing widely in the Mungyeong-Sangju area are characterized by miarolitic texture of various shape and size. By the joint frequency contour diagram, the joints of orthogonal thpe are recognized in the LPG and PG. From the petrologic textures, joint pattern, and joint spacings, it is recommended that the LPG has more possibility than the PG in recovery ratio of stone. The average physical properties such as specific gravity, absorption ratio (%), porosity (%) and compressive strength (kg/$cm^2$) have been tested 2.6 and 2.6, 0.5 and 0.6, 1.4 and 1.5, 1440 and 1680 for the LPG and PG, respectively. The stones belong to the hard rock, and represent applicable building stone. The thermal conductivity (w/m.k) showing proportional relationships with the absorption ratio and porosity is 2.2~3.2 and suggests massive texture. With increasing of the compressive strength, the ratio of $Fe_2O_3$/($Fe_2O_3$+FeO) show irregular trend and CaO, $Na_2O$ and $K_2O$ have uniformal values without variations. These results suggest there are no matual relationships.

• 자원리싸이클링
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• 제2권2호
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• pp.27-38
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• 1993

본 연구에서는 제철소에서 발생하는 전로 dust를 사용하여 심강법(분급)에 의한 철산화물을 분리하여 고순도의 철분말을 회수하였으며, 아래와 같은 결론을 얻었다. 가. 전로 dust의 물성 1) 재항의 1제강, 2제강 C/F(Clarifier) dust, 광장의 E/C(Evaporation coolar), dust, 중국강철공사(C.S.C) OM(Clarifier underflow) dust 금철분이 63~72%로 높고, Metal Fe 가 21~50% 함유되어 있으며, 기타 산화물로는 CaO, MgO, Al$_{2}O_{3}$, SiO$_{2}$ 등이 있다. 2) 재항의 1제강, 2제강 C/F dust, 광양의 E/C, E/P dust, 중국강철공사(C.S.C), OM(clarifier underflow) dust 입자의 형상은 청입이 주로 구형으로 응고된 모양이었으며, 일반적으로는 출립의 외각부는 magnetite, hematite 등으로 산화가 진해되어 있다. 3) 전로 dust 들에 대한 X-ray 회절분석결과, 재항의 1제강, 2제강, C/F dust, 광양의 E/C, E/P dust는 ${\alpha}$-Fe, FeO(wusute)가 중성분으로 존재하며 그 밖에 FE$_{3}O_{4}$9magnetite), Fe$_{2}O_{3}$ CaO가 소량으로 존재하고 있었으며, 중국강철공사(C.S.D) OM(underflow) dust는 ${\alpha}$-Fe, ${\alpha}Fe_{2}O_{3}$, graphite가 주성분으로 존재하며, 그 밖에 $Fe_{3}O_{4}$, Fe$_{2}O_{3}$, ZnO이 소량으로 존재하고 있었다. 4) 순수한 순철분말과 전로 dust를 구성하고 있는 순철은 마광에 따른 입자의 분쇄보다는 마광시 구형의 입자가 소성변형으로 인해 flake형상으로 변하여 체질입도분석시 입도의 증가를 초래하였으며, 반면 철산화물은 마광에 따른 입자의 미세화가 발생함을 볼 수 있었다. 나. 철분구 외수 실험 1) 광양의 dust를 40분간 마광하여 심강(분급)실험을 행했을 때 Fe 99.17% 품위 철분말을 37.8% 회수할 수 있었다. 2) 재항의 C/F dust를 40분간 마광하여 심강(분급)실험을 행했을 때 Fe 98.38% 품위의 철분말을 44.42% 회수할 수 있었다. 3) 70 gauss 자석을 사용하여 자력선별을 행했을 때 +65-200 mesh 사이에서 Fe 품위 98% 이상의 철분말을 회수 할 수 있으나 회수율(14%)이 낮다.

• 대한환경공학회지
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• 제28권6호
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• pp.620-625
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• 2006

본 연구에서는 ICP-DRC/MS를 이용하여 비소(arsenic) 분석의 주요 방해물질인 $^{40}Ar^{35}Cl^+$과 $^{40}Ca^{35}Cl^+$에 의한 간섭의 영향 없이 극미량의 비소를 간편하고 신속하게 측정할 수 있는 방법을 제시하였다. 즉, 반응기체로 산소($O_2$)를 dynamic reaction cell에 도입하여 플라즈마 기체 내부에서 생성된 비소이온($As^+$)과 반응시켜 $AsO^+$를 생성시킨 후 m/z=91을 검출함으로써 기존의 m/z=75($As^+$) 검출방법에 비해 우수한 재현성과 검출한계를 얻을 수 있었다. 반응기체($O_2$)의 양은 0.5 mL/min 일 때 최적조건으로 나타났으며, 검출한계는 $0.02{\mu}g/L$, 정확도(RSD)는 3.4%, 회수율은 96%로 나타났다. 이 분석방법으로 서울시 한강 팔당 본류 유입 지류천에서 채취된 시료 중의 비소를 분석한 결과, $0.53{\sim}1.26{\mu}g/L$의 농도로 나타났으며 우수한 재현성을 나타냈다. 또한 이 방법은 다량의 염소(Cl)나 칼슘(Ca)을 함유한 해수, 식품, 하수 및 폐수 중의 비소 분석에도 유용하게 적용될 수 있으리라 기대된다.

• The Korean Journal of Physiology
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• 제18권1호
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• pp.37-50
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• 1984

The effects of $Ca^{++}$ and its antagonists (verapamil and $La^{+++}$) upon the spontaneous contraction and the contracture induced by 60 mM K-Tyrode solution were studied in the isolated uterine muscle. Longitudinal muscle strips were prepared from the rat uteri at estrous stage. All experiments were performed in tris-buffered Tyrode solution which was aerated with 100% $O_2$ and kept at 35^{\circ}$. The results obtained were as follows: 1) In the uterine strips contracting spontaneously, both the amplitude of peak tension and the area of contraction curve increased dose-dependently in the range of $0.5${\sim}8$ mM $Ca^{++}$. The frequency of contraction increased as the concentration of $Ca^{++}$ increased up to 2 mM, but above this concentration the frequency decreased. In $Ca^{++}-free$ media, however, contraction did not develop. In the contracture induced by 60 mM K-Tyrode solution, the developed tension increased dose-dependently as the concentration of external $Ca^{++}$ increased to 8 mM. In the absence of external $Ca^{++}$ K-contracture appeared, but it was not sustained. 2) The spontaneous contraction of rat uterus was suppressed by verapamil in proportion to an increase of its concentration and totally abolished at the concentration of $3{\times}10^{-4}\;g/l$, but the spontaneous contraction re-appeared by addition of $Ca^{++}$. The amplitude of peak tension recovered completely but the recovery of frequency was incomplete. K-contracture decreased in a dose-dependent manner after the treatment with verapamil and totally disappeared at its concentration of $3{\times}10^{-4}\;g/l$. Even in this case contracture developed again by extra $Ca^{++}$. 3) The spontaneous contractile activity was inhibited by $La^{+++}$. At the concentration of $10^{-4}$M $La^{+++}$, fibrillation appeared. In the strip inhibited by $10^{-5}M\;La^{+++}$, contractility recovered completely by extra $Ca^{++}$ while in the $10^{-4}M\;La^{+++}$ treated preparation, the rhythmic spontaneous contraction did not develop even at the concentration of 16 mM $Ca^{++}$. After the initial transient depression of contracture tension by $10^{-3}M$ of $La^{+++}$, the strip stowed considerably large size of contracture, hardly influenced by external $Ca^{++}$ or verapamil. The results obtained in this experiment suggest that in the rat uterine muscle there would be some competitive actions between $Ca^{++}$ and its antagonists. It is speculated that $Ca^{++}$ plays an important role in the conduction of excitation, and $La^{+++}$ influences upon cellular $Ca^{++}$ mobilization and re-uptake process as well as transmembrane $Ca^{++}$ transport in a K-depolarized state.

• 상하수도학회지
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• 제28권2호
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• pp.207-215
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• 2014

Wastewater containing heavy metals such as copper (Cu) and nickel (Ni) is harmful to humans and the environment due to its high toxicity. Crystallization in a fluidized bed reactor (FBR) has recently received significant attention for heavy metal removal and recovery. It is necessary to find optimum reaction conditions to enhance crystallization efficacy. In this study, the effects of crystallization reagent and pH were investigated to maximize crystallization efficacy of Cu-S and Ni-S in a FBR. CaS and $Na_2S{\cdot}9H_2O$ were used as crystallization reagent, and pH were varied in the range of 1 to 7. Additionally, each optimum crystallization condition for Cu and Ni were sequentially employed in two FBRs for their selective removal from the mixture of Cu and Ni. As major results, the crystallization of Cu was most effective in the range of pH 1-2 for both CaS and $Na_2S{\cdot}9H_2O$ reagents. At pH 1, Cu was completely removed within five minutes. Ni showed a superior reactivity with S in $Na_2S{\cdot}9H_2O$ compared to that in CaS at pH 7. When applying each optimum crystallization condition sequentially, only Cu was firstly crystallized at pH 1 with CaS, and then, in the second FBR, the residual Ni was completely removed at pH 7 with $Na_2S{\cdot}9H_2O$. Each crystal recovered from two different FBRs was mainly composed of CuxSy and NiS, respectively. Our results revealed that Cu and Ni can be selectively recovered as reusable resources from the mixture by controlling pH and choosing crystallization reagent accordingly.