• 한국토양비료학회지
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• 제37권6호
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• pp.371-377
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• 2004

산림토양에서의 황산이온 흡착은 식물의 흡수, 양이온 이동 및 산중화능 등 산림생태계의 황 동태에 중요한 영향을 미친다. 따라서 본 연구는 산림토양 중의황산이온 분포와 그와 관련된 황산이온 흡착이 어떠한 토양특성에 의해 영향을 받는지를 밝히기 위해 수행되었다. 이를 위해 소나무와 신갈나무 임분으로 조성된 4개 산림지역을 대상으로 표토층과 심토층으로 구분하여 황산이온 흡착지표로서의 추출성 황산이온함량 및 황산이온 흡착능을 정량 한 후 관련 토양 물리화학적 특성인 pH. 양이온치환용량, 점토함량 및 Ai과 Fe 산화물의 종류별 함량과의 상관성을 분석하였다. 토양 중 추출성 황산이온 함량 및 황산이온 흡착능은 각 조사지별로 큰 차이를 보였으며 전체적으로 유기물 함량이 적고 Al 또는 Fe 산화물 함량은 많은 심토층이 표토층에 비하여 황산이온 흡착량이 많았다. 황산이온 흡착량이 많았던 심토층의$Al_d$와 $Fe_d$ 산화물 평균 함량은 각각 8.49와 $12.45g\;kg^{-1}$로 대체로 낮은 수준이었다. 황산이온 흡착지표들은 토양 pH, 양이온치환용량 및 점토함량과 대체로 유의적인 정의 상관관계를 보였다. 반면에 유기탄소 함량과는 부의 상관성을 보여 산림토양 중에서 유기물이 황산이온 흡착에 대해 경합물질로 작용함을 알 수 있었다. Ai과 Fe 산화물 중에서는 $Al_d,\;Al_o,\;Al_p,\;Al_a$ 및 $Fe_a$가 황산이온 흡착지표들과 유의성 있는 상관성을 보였으나, $Al_c$와 $Fe_c$는 황산이온 흡착지표들과 상관성이 없었다. 황산이온 흡착지표인자들과 토양 pH, 양이온치환용량 및 비결정형 Ai 함량간의 정의 상관관계 결과는 토양산성화로 인해 산림생태계에서 황 동태에 기여하는 산림토양의 황산이온 흡착 능력이 저하될 수 있음을 반영한다.

• Progress in Superconductivity
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• 제8권1호
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• pp.87-92
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• 2006

The effects of Ba and Ce addition has been investigated in YBCO prepared by trifluoroacetate(TFA) metalorganic depostition(MOD) method. Precursor solutions with cation ratios of Y:Ba:Cu:Ce=1:2+x:3:x(x=0, 0.05, 0.1 and 1.5) have been prepared by adding an excess amount of cerium and barium. Coated film was calcined at lower temperature under a moisture-containing oxygen atmosphere. Superconducting YBCO films have been obtained by performing conversion heat treatment at temperature of $780{\sim}810^{\circ}C$ under a moisture-containing Ar(1,000 ppm oxygen) atmosphere. It has been shown that the critical current($I_c$) of YBCO film was degraded by doping of Ba and Ce atoms. But $I_c$ was increased as the amount of doped Ba and Ce content increased from 5% to 15 %. It was observed that there was little increase of a flux pinning force with Ba and Ce addition in YBCO film prepared by TFA-MOD process.

• Membrane and Water Treatment
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• 제6권3호
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• pp.173-187
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• 2015

The goal of present work is the preparation of a novel positively charged nanofiltration (NF) membrane and its development for the cation removal of aqueous solutions. This NF membrane was fabricated by the surface modification of polysulfone (PSf) ultrafiltration support. The active top-layer was formed by interfacial cross-linking polymerization of poly(ethyleneimine) (PEI) with p-xylylene dichloride (XDC) and then quaternized with methyl iodide to form a perpetually positively charged layer. In order to improve the efficiency of nanofiltration membrane, the concentration of PEI, XDC and methyl iodide solutions, PEI coating and cross-linking time have been optimized. As a result, a high water flux and high $CaCl_2$ rejection (1,000 ppm) was obtained for the composite membrane with values of $18.29L/m^2.h$ and 93.62% at 4 bar and $25^{\circ}C$, respectively. The rejections of NF membrane for different salt solutions followed the order of $Na_2SO_4$ < $MgSO_4$ < NaCl < $CaCl_2$. Molecular weight of cut off (MWCO) was calculated via retaining of PEG solutions with different molecular weights that finally, it revealed the Stokes and hydrodynamic radius of 1.457 and 2.507 nm on the membrane selective layer, respectively. The most efficient positively charged nanofiltration membrane exhibited a $Ni^{2+}$ rejection of 96.26% for industrial wastewater from Shamse Hadaf Co. (Kashan, Iran).

• International Journal of Oral Biology
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• 제43권1호
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• pp.23-27
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• 2018

Increased intracellular levels of $Ca^{2+}$ are generally thought to negatively regulate lipolysis in mature adipocytes, whereas store-operated $Ca^{2+}$ entry was recently reported to facilitate lipolysis and attenuate lipotoxicity by inducing lipophagy. Transient receptor potential mucolipin1 (TRPML1), a $Ca^{2+}$-permeable non-selective cation channel, is mainly expressed on the lysosomal membrane and plays key roles in lysosomal homeostasis and membrane trafficking. However, the roles of TRPML1 in lipolysis remains unclear. In this study, we examined whether the channel function of TRPML1 induces lipolysis in mature adipocytes. We found that treatment of mature adipocytes with ML-SA1, a specific agonist of TRPML1, solely upregulated extracellular glycerol release, but not to the same extent as isoproterenol. In addition, knockdown of TRPML1 in mature adipocytes significantly reduced autophagic flux, regardless of ML-SA1 treatment. Our findings demonstrate that the channel function of TRPML1 partially contributes to lipid metabolism and autophagic membrane trafficking, suggesting that TRPML1, particularly the channel function of TRPML1, is as therapeutic target molecule for treating obesity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.1998-2000
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• 2005

The effects of the addition of nanocrystalline Y2O3 powder on the microstructure and superconducting properties have been investigated in YBCO films prepared by TFA-MOD process. Precursor solution doped with extra $Y_2O_3$ Powder was prepared by adding $Y_2O_3$ powder into a stoichiometic precursor solution with a cation ratio of Y:Ba:Cu=1:2:3. Coating solutions with and without $Y_2O_3$ doping were coated on $LaAlO_3(100)$ single crystal by a dip coating method, cacination and conversion heat treatments were performed at the controlled atmosphere containing water vapor Current carry capacity(Jc) of YBCO film was enhanced about 50% by $Y_2O_3$ doping. It is thought that the enhancement of Jc is due to the better connectivity of YBCO grains and/or the flux pinning by the presence of nanocrystalline $Y_2O_3$ Particles embedded in YBCO grains.

• 멤브레인
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• 제17권3호
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• pp.210-218
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• 2007

바이폴라막을 이 용한 전기탈이온(Continuous Electrodeionization-Bipolar Membrane(CEDI-BPM))공정 은 이온교환막의 이온 선택적 투과를 통한 제거의 효율을 높이며, 바이폴라막에서 생성된 수소이온과 수산화이온이 이온교환수지를 전기적으로 재생하여 재생효율을 높일 수 있는 장점을 지니고 있다. 본 연구에서는 CEDI-BPM을 이용하여 경도물질을 제거하고 전기적 재생을 수행하였다. 이를 위하여 이온교환수지의 흡착 특성 및 유량의 변화에 따른 경도제거효율의 영향과 전기적 재생방법을 이용한 재생효율을 조사하였다. CEDI-BPM에서 Ca의 제거율이 Mg보다 높은 값을 보여주었는데, 이는 흡착실험에서 Ca의 높은 흡착능력과 관계가 있음을 보여주었다. 유량이 증가함에 따라 Ca과 Mg의 플럭스는 증가하는 경향을 보이는데, 양이온 교환막의 선택 투과가 경도물질의 제거에 더 큰 영향을 미치고 있음을 알 수 있다. CEDI-BPM의 전기적인 재생 실험결과 재생 전압을 낮게 유지할수록 높은 경도물질 제거효율 및 높은 플럭스를 보여 전기적 재생에 효율적으로 사용할 수 있음을 보여주었다.

• 한국약용작물학회지
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• 제6권1호
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• pp.51-56
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• 1998

본 연구는 1995년부터 1997년까지 경기도와 강원도 5개군 7개소를 중심으로 자생하는 삼지구엽초의 환경특성을 구명하여 삼지구엽초 작물화재 배연구의 기초자료로 제공하고자 수행하였던 바 그 결과를 요약하면 다음과 같다. 1. 조사된 자생지는 대체로 북서 사면에 표고 $60{\sim}400m$, 경사도 $2{\sim}20%$인 곳의 냇가에서 $5{\sim}80m$ 주위로 물줄기를 따라 장타원으로 위치하고 있었다. 2. 자생지 토양은 잔자갈이 있는 양토 또는 사양토로서 가비중이 $0.74{\sim}1.26g/cm^3$, 공극율 $52.5{\sim}72.1%$로 나타났다. 3. 토양화학성은 pH $4.1{\sim}5.8$, 유기물함량 $4.9{\sim}6.6%$, 유효인산 $21{\sim}125\;ppm$, 치환성양이온 (me/100g)은 $K^+\;0.35{\sim}1.09,\;Ca^{++}5.42{\sim}18.73,\;Mg^{++}\;0.99{\sim}1.53$, CEC는 $14.8{\sim}34.3me/100g$이었다. 4. 자생지는 주로 개암나무, 떡갈나무, 참나무 등 낙엽광엽활엽수에 의하여 차광되어 취, 둥굴레, 삽주, 뱀딸기, 제비꽃 등 반음지식물과 함께 자생하고 있었다. 5. 삼지구엽초 군락에 도달하는 광투과 정도는 노지 대비 relative photon flux density $3.5{\sim}13.1%$ 상대조도는 $3.3{\sim}11.9%$ 였으며 기온은 $4.3{\sim}6.5^{\circ}C$낮았다. 또한 지온은 5월에서 8월까지 $17.5{\sim}20.1^{\circ}C$로 경과되어 외기기온의 $25.1{\sim}30.8^{\circ}C$에 비하여 낮았으나 변화폭이 작았다.

• 한국분말재료학회지
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• 제27권2호
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• pp.146-153
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• 2020

The co-doping effect of aliovalent metal ions such as Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, and Zn²⁺ on the photoluminescence of the Y₂O₃:Eu³⁺ red phosphor, prepared by spray pyrolysis, is analyzed. Mg²⁺ metal doping is found to be helpful for enhancing the luminescence of Y₂O₃:Eu³⁺. When comparing the luminescence intensity at the optimum doping level of each Mg²⁺ ion, the emission enhancement shows the order of Zn²⁺ ≈ Ba²⁺ > Ca²⁺ > Sr³⁺ > Mg²⁺. The highest emission occurs when doping approximately 1.3% Zn²⁺, which is approximately 127% of the luminescence intensity of pure Y₂O₃:Eu³⁺. The highest emission was about 127% of the luminescence intensity of pure Y₂O₃:Eu³⁺ when doping about 1.3% Zn²⁺. It is determined that the reason (Y, M)₂O₃:Eu³⁺ has improved luminescence compared to that of Y₂O₃:Eu³⁺ is because the crystallinity of the matrix is improved and the non-luminous defects are reduced, even though local lattice strain is formed by the doping of aliovalent metal. Further improvement of the luminescence is achieved while reducing the particle size by using Li₂CO₃ as a flux with organic additives.

• Journal of Microbiology and Biotechnology
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• 제13권5호
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• pp.673-679
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• 2003

Glutamine and urea, abundant in body fluids or plasma, yield net ammonium ions upon hydrolysis by ${\gamma}-glutamyl$ transpeptidase (${\gamma}-GTP$) and urease, respectively, and these two enzymes are largely produced from Helicobacter pylori. To investigate bacterial potential of ammonium production, we first quantified those in whole-cell systems and found that the relative ratio of their amounts varied greatly, especially with pH values and the cell's aging. During the H. pylori cultivation, the ratio appeared to be inversely proportional to each other, showing a progressive increase of the ${\gamma}-GTP$ with decreasing of the urease. Under the urease-defective conditions due to low pH or coccoids, the bacterial cells still possessed a considerable amount of ${\gamma}-GTP$, which was found exclusively in the external compartment, therefore, the cell's ammonium production was found to be solely dependent upon glutamine, and the external ammonium concentration was constant without any contribution of urea concentration. Such ammonium constancy would definitely have an adverse effect on the host, because of its absolute requirement for vacuolar degeneration by H. pylori VacA, maximized at approximately 10 mM $NH_4Cl$. It was also found that, by using the metal-saturated membrane vesicles, ammonium ions were likely to be involved in the pH-dependent cation-flux across the H. pylori membrane, where the role of ${\gamma}-GTP$ in ammonium homeostasis around cells was suggested, especially under the hostile conditions against H. pylori.

• Journal of Microbiology and Biotechnology
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• 제21권5호
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• pp.483-493
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• 2011

An acid phosphatase (HppA) activated by $NH_4Cl$ was purified 192- and 34-fold from the periplasmic and membrane fractions of Helicobacter pylori, respectively. SDS-polyacrylamide gel electrophoresis revealed that HppA from the latter appears to be several kilodaltons larger in molecular mass than from the former by about 24 kDa. Under acidic conditions (pH${\leq}$4.5), the enzyme activity was entirely dependent on the presence of certain mono- and/or divalent metal cations (e.g., $K^+$,$ NH_4{^+}$, and/or $Ni^{2+}$). In particular, $Ni^{2+}$ appeared to lower the enzyme's $K_m$ for the substrates, without changing $V_{max}$. The purified enzyme showed differential specificity against nucleotide substrates with pH; for example, the enzyme hydrolyzed adenosine nucleotides more rapidly at pH 5.5 than at pH 6.0, and vice versa for CTP or TTP. Analyses of the enzyme's N-terminal sequence and of an $HppA^-$ H. pylori mutant revealed that the purified enzyme is identical to rHppA, a cloned H. pylori class C acid phosphatase, and shown to be the sole bacterial 5'-nucleotidase uniquely activated by $NH_4Cl$. In contrast to wild type, $HppA^-$ H. pylori cells grew more slowly. Strikingly, they imported $Mg^{2+}$ at a markedly lowered rate, but assimilated urea rapidly, with a subsequent increase in extracellular pH. Moreover, mutant cells were much more sensitive to extracellular potassium ions, as well as to metronidazole, omeprazole, or thiophenol, with considerably lowered MIC values, than wild-type cells. From these data, we suggest that the role of the acid phosphatase HppA in H. pylori may extend beyond 5'-nucleotidase function to include cation-flux as well as pH regulation on the cell envelope.