• Journal of Microbiology and Biotechnology
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• 제10권4호
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• pp.441-448
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• 2000

The production and cation flux-mediated activation of the P-type ATPase in Helicobacter pylori was investigated. Using the polymerase chain reaction (PCR), the proton pump genotype of H. pylori was found to be positive for both F-type and P-type ATPases. Yet, their production in terms of enzyme specific activity varied substantially depending on H. pylori strains, ranging over 3-fold. Its main constituent appeared to be the P-type ATPase pool, in contrast to other common bacterial compositions. Interestingly, the F-type ATPase was observed only when intact H. pyloricells were exposed to pH 4.5 or above (37$^{\circ}C$ for 1 h). In contrast, significant amounts of the P-type ATPase still remained after 1 h of cell treatment even at pH below 4.5. By enriching the acidic medium with RPMI(pH 3.0), the P-type ATPase was stabilized, accompained by inactivation of the F-type ATPase. Using H. pylori membrane vesicles, it was found that ammionia-mediated cation flux increased the rate of ATP hydrolysis by the P-type ATPase. Accordingly, these data strongly suggest that the P-type ATPase is involved or functions as an effective regulator for the cation flux across the H. pylori membrane, thereby reducing the risk of excess proton influx.

• 한국환경생태학회지
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• 제15권3호
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• pp.230-236
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• 2001

본 연구는 일본 북해도 지방의 임해공업단지에 인접되어 있는 점소목지역 내 활엽수 천연림에서 주요 염기성 양이온에 대한 물질순환 수지를 파악하고자 강우(wet deposition), 임내우(throughfall), 수간류(stemflow) 그리고 토양침투수(soil leachate)에 대한 이온 flux를 정량화하였다. 조사 결과 강우는 평균 pH 4.3의 강한 산성우로 강우에 의한 $H^{+}$ flux는 034kmo1$_{c }$ $ha^{-1}$ /이었고, 임내우와 수간류에 의한 염기성 양이온($K{+ }$ , $Na^{+}$ , $Ca^{ 2+ }$, $Mg^{2+}$ )의 flux는 $1.6kmol_{c}$ ha$^{-1}$ 로 강우의 0.49 kmolc $ha^{-1+}$ /보다 3배 많았다. 수관충 용탈(canopy leaching)에 의한 염기성 양이온의 flux는 0.95kmo1c $ha^{H}$ 로 강우에 의한 $H^{+}$ flux보다 2.8배 높았으며, H$^{+}$는 수관층에서 치환성 양이온들에 의해서 거의 소비되었다. 토양층에서 이온배출 flux는 토양특성에 의존되었으며, 토양 중 Ca은 proton소비에 중요한 인자로 작용하였다. 생태계의 물질순환에 대한 수지에서 Na, Ca및 Mg은 생태계 내부에서 외부로 방출되는 양보다 생태계로 유입되고 있는 양이 많아 생태계에 축적되고 있었으나, K의 경우는 부의 flux를 나타냈다.

• 한국물환경학회지
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• 제21권3호
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• pp.242-247
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• 2005

In this study, we investigated the removal efficiencies of pollutants and permeate fluxes depending on chemistry of feed water, various molecular weight cut-offs (MWCOs) and materials of membrane, operating pressure. We used seven MWCO membranes of YC0.5, YM1, YM3, YM10, YM30, YM100 and PM30, humic acid solution and surface water as feed water, and examined variation in permeate flux. Results of TOC removal experiment demonstrate that MWCO lower 1,000daltons could remove humic acid effectively. As increasing solution pH and decreasing divalent cations ($Ca^{2+}$) concentration, TOC removal increased. But $UV_{254}$ removal efficiency increased with higher divalent cation concentration and solution pH. Membrane fouling increased with increasing electrolyte (NaCl), divalent cation concentration and decreasing solution pH. In spite of initial permeate flux of the hydrophobic membrane (PM30) was higher than that of the hydrophilic membrane (YM30), flux decline of PM30 was significant during operation. At higher operating pressure, compactness of the cake layer on the membrane surface increased, resulting in gradual increase in hydraulic resistance.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.109-112
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• 2004

The charged mosaic membranes having cation and anion exchange mixed groups within membrane were researched. The composite charged mosaic membrane was investigated from simultaneous transport such as solute and solvent flux. On the other hand, the reflection coefficient and salt flux coefficient were estimated by taking account of the cross constants of the phenomenological equation.(omitted)

• KSBB Journal
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• 제6권2호
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• pp.207-213
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• 1991

In this study poly (1-methyl-4-vinylpyridinium iodide-co-styrene) membrane with pyridinium cation as a fixed carrier was synthesized and the transport characteristics of the membrane was examined over various factors. As the concentration of the fixed carrier in the membrane was increased, the water content was increased. Meanwhile, the counter current of the organic anion and the chloride ion, the following results were obtained. Initial flux of Cl-, organic anion and Na+ decreased with the increasing thickness of membrane, and as the concentration of the fixed carrier increases, the initial flux of Cl- and organic anion increase but the initial flux of Na+ decreased. The flux equation of the organic anion, CCl3COO- was obtained from saturation kinetics as follows;$V_{o}=\frac{(8.67{\times}10^{-5}){\cdot}[NaCl]}{9.63{\times}10^{-2}+[NaCl]} mol/cm^2h$

• 멤브레인
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• 제17권1호
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• pp.54-60
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• 2007

본 연구에서는 복막 투석 시스템에 있어서, 요소를 가수분해 후 발생하는 암모니아를 제거하기 위하여, 방사선 그라프트 중합법에 의해 다공성 중공사막에 술폰산기($SO_3H$)를 도입시킨 양이온 교환막(이때 얻어진 막을 SS막이라 함)을 합성하였다. 여기에 금속이온(Cu, Ni, Zn)을 이용하여 그라프트 체인을 가교시킨 이온가교형 양이온 교환막(이때 얻어진 막을 SS-M막이라 함)을 합성하여, SS막과 SS-M막의 투과 유속과 암모니아의 흡착에 대하여 고찰하였다. 술폰산기 밀도에 따라 순수투과 유속은 술폰산기 밀도가 높아짐에 따라 투과 유속이 급격히 감소하였으나, 금속 이온이 도입됨에 따라, 투과 유속이 빨라진다는 것을 알 수 있었다. SS막의 경우 암모니아 흡착은 이온교환기 용량에 따라 1 : 1로 흡착되었고, SS-M막 보다 높은 흡착량을 나타났다. 또한, SS막, SS-M막 모두 pH 9에서 가장 높은 흡착량을 나타냈다.

• ALGAE
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• 제36권4호
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• pp.315-326
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• 2021

Ion channels are membrane protein complexes mediating passive ion flux across the cell membranes. Every organism has a certain set of ion channels that define its physiology. Dinoflagellates are ecologically important microorganisms characterized by effective physiological adaptability, which backs up their massive proliferations that often result in harmful blooms (red tides). In this study, we used a bioinformatics approach to identify homologs of known ion channels that belong to 36 ion channel families. We demonstrated that the versatility of the dinoflagellate physiology is underpinned by a high diversity of ion channels including homologs of animal and plant proteins, as well as channels unique to protists. The analysis of 27 transcriptomes allowed reconstructing a consensus ion channel repertoire (channelome) of dinoflagellates including the members of 31 ion channel families: inwardly-rectifying potassium channels, two-pore domain potassium channels, voltage-gated potassium channels (K_v), tandem K_v, cyclic nucleotide-binding domain-containing channels (CNBD), tandem CNBD, eukaryotic ionotropic glutamate receptors, large-conductance calcium-activated potassium channels, intermediate/small-conductance calcium-activated potassium channels, eukaryotic single-domain voltage-gated cation channels, transient receptor potential channels, two-pore domain calcium channels, four-domain voltage-gated cation channels, cation and anion Cys-loop receptors, small-conductivity mechanosensitive channels, large-conductivity mechanosensitive channels, voltage-gated proton channels, inositole-1,4,5-trisphosphate receptors, slow anion channels, aluminum-activated malate transporters and quick anion channels, mitochondrial calcium uniporters, voltage-dependent anion channels, vesicular chloride channels, ionotropic purinergic receptors, animal volage-insensitive cation channels, channelrhodopsins, bestrophins, voltage-gated chloride channels H⁺/Cl^- exchangers, plant calcium-permeable mechanosensitive channels, and trimeric intracellular cation channels. Overall, dinoflagellates represent cells able to respond to physical and chemical stimuli utilizing a wide range of G-protein coupled receptors- and Ca²⁺-dependent signaling pathways. The applied approach not only shed light on the ion channel set in dinoflagellates, but also provided the information on possible molecular mechanisms underlying vital cellular processes dependent on the ion transport.

• Nuclear Engineering and Technology
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• 제28권3호
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• pp.274-279
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• 1996

Diffusion coefficient is a critical parameter for predicting radiological source term(migration rate and flux of radionuclide) through given near field conditions in spent fuel or high level waste repository. The effect of exchangeable cation-$Na^+$ and $Ca^{2+} - on the diffusion of $I^- \;and^3H$ (as HTO) in compacted bentonite was examined using a through-diffusion method. Bentonite material used here was compacted to a density of 1.3 Mg/m$^3$, and Na-bentonite was saturated with a solution of 100 mol NaCl/m$^3$ and Ca-bentonite with 50 $mol\;CaCl_2$/m$^3$. The results show that effective diffusion coefficients are generally higher by a factor of two to five in Ca-than Na-clay. This is attributed to the larger particle size of Ca-compared to Na-bentonite; hence, Ca-bentonite has a greater proportion of relatively large pores, which make a greater contribution to mass transport than small pores. Although the nature of the exchangeable cation affects mass diffusion in compacted bentonite, the effect is small and not likely to influence performance assessment modeling of compacted bentonite-based barriers.

• 상하수도학회지
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• 제25권2호
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• pp.171-176
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• 2011

Organic matters that comprise a tiny part of seawater generally occur over 50% of membrane fouling in Reverse Osmosis Process. This study evaluates Foundation efficiency of reverse osmosis membranes under brackish and seawater conditions and resistance of organic fouling. Moreover, analyzing the membrane surface through roughness, contact angle and zeta potential results in roughness and contact angle are proportional to flux decline rate (FDR), yet FDR has high value when zeta potential is low level. Furthermore, with various membrane fouling of different raw water conditions, the flux tends to improve when pH value is high and raw water which is complex with organic and cation pollutes membrane faster than organic separated raw water condition.

• Journal of Applied Biological Chemistry
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• 제43권1호
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• pp.18-24
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• 2000

A one-dimensional transport of displacing monovalent ion, $A^+$, and a trivalent ion being displaced, $B^{3+}^ in a porous exchange system such as soil was approximated using the Crank-Nicolson implicit finite difference technique and the Thomas algorithm in tandem. The variations in the concentration profile were investigated by varying the ion-exchange equilibrium constant (k) of ion-exchange reactions, the influent concentrations, and the cation exchange capacity (CEC) of the exchanger, under constant flux condition of pore water and dispersion coefficient. A higher value of k resulted in a greater removal of the native ion, behind the sharper advancing front of displacing ion, while the magnitude of the penetration distance of $A^+$ was not great. As the CEC increased, the equivalent fraction of $B^{3+}^ initially in the soil was greater, thus indicating that a higher CEC adsorbed trivalent cations preferentially over monovalent ions. Mass balance error from simulation results was less than 1%, indicating this model accounted for instantaneous charge balance fairly well.