• The Korean Journal of Physiology
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• 제14권2호
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• pp.17-20
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• 1980

This study was undertaken to investigate the effect of the acidosis on the gastric acid secretion in the isolated whole stomach of the rat and the effect of prostaglandin $E_1$ on the gastric acid secretion influenced by the acidosis. Twenty-two male albino rats(Sprague-Dawley strain) were used. The isolated whole stomach from each rat was introduced into the Kreb's solution which was continuously gassed with $95%O_2-5%CO_2$ for 1 hour, after irrigation of the lumen with cold physiological saline$(4^{\circ}C)$. Thereafter, each stomach was irrigated again with 5% dextrose solution (pH 7.4, $37^{\circ}C$), and filled with the dextrose solution. All the stomachs with the dextrose solution were divided into 4 groups according to the Kreb's solutions in which each stomach was incubated for 30 min: 1) control group, in the pH 7.4 solution, 2) $PGE_1$ group, in the pH 7.4 solution containing $5\;{\mu}g/ml$ of $PGE_1$, 3) acid group, in the pH 7.0 solution, and 4) $acid+PGE_1$ group, in the pH 7.0 solution containing $5\;{\mu}g/ml$ of $PGE_1$. After incubatory period, the contents of each stomach were collected and centrifuged(1,500 rpm, room temperature) for 15 min. The acid output in the supernatant was determined with 0.012 N NaOH by means of autotitrator(Dosimat, Metrohm Herisau Co.) at pH 7.4. Results obtained were as follows: 1) The acid output of the acid group increased significantly in comparison with the control value. 2) The acid output of the $acid+PGE_1$ group decreased significantly in comparison with the acid group. It is inferred from the above results that the acidosis facilitates the gastric acid secretion and $PGE_1$ inhibits the gastric acid secretion induced by the acidosis.

• 방사성폐기물학회지
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• 제19권1호
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• pp.1-7
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• 2021

The pH dependence of sorption distribution coefficient (Kd) of Np(IV) on MX-80 in Ca-Na-Cl type solution with the ionic strength of 0.3 M, which was similar to one of the reference groundwaters in crystalline rock, was experimentally investigated under the reducing conditions. The overall trend of Kd on MX-80 was independent of pH at 5 ≤ pH ≤ 10 but increased as pH increased at pH ≤ 5. The 2-site protolysis non-electrostatic surface complexation and cation exchange model was applied to the experimentally measured pH dependence of Kd and the optimized surface complexation constants of Np(IV) sorption on MX-80 were estimated. The values of surface complexation constants in this work agreed relatively well with those in the Na-Ca-Cl solution previously evaluated, suggesting that compared to Na+, the competition of Ca2+ with Np(IV) for surface complexation on MX-80 was not much strong in Ca-Na-Cl solution. The sorption model well predicted the pH dependence of Kd values but slightly overestimated the sorption at the low pH region.

• 생물환경조절학회지
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• 제12권2호
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• pp.89-94
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• 2003

본 실험은 토마토의 순환식 시스템 양액재배에서 배액의 재순환 시 안정된 pH와 균형적인 양분 공급 방법을 구명하고자 수행되었다. 배액의 pH나 무기성분을 교정하지 않는 구(대조구), EC측정 및 양분 분석 교정구를 처리내용으로 두었다. 초기생육인 초장은 처리간에 차이가 없었으나 생체중 및 건물중은 양분분석구가 대조구에 비해 무거웠다. 후기생육에서는 양분분석구가 대조구에 비해 과중이 무겁고, 착과수가 많아 수량이 증가하였다 배액 EC는 대조구에 비해 EC측정구와 양분분석구가 전반적으로 낮았다. 배액의 pH는 전 생육기간에서 양분 분석구 및 EC측정구는 6.2∼6.5를 유지하였으나 대조구는 지속적으로 높아져 후기에는 7.2정도 되었다. 배액의 무기성분에서 N, P 및 K의 함량은 모든 처리구에서 셍육이 경과함에 따라 적어졌으며, 대조구에 비해 양분분석구가 적었다 Ca 및 Mg의 함량은 모든 처리구에서 생육초기에는 급격히 감소하였으며 생육후기에는 앙분 분석구와 EC측정구는 적은 상태로 유지되었으나 대조구는 급격히 증가하는 경향이었다. 이상의 결과에서 순환식 시스템을 이용한 토마토의 양액재배시 배액의 양분을 분석한 후 교정하는 것이 생육에 효과적이었다.

• 한국환경과학회지
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• 제17권5호
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• pp.509-516
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• 2008

New functional surfactant, N,N-dimethyl-N-dodecyl-N-(2-methyl benzimidazoyl) ammonium chloride(DDBAC) having benzimidazole(BI) functional group have been synthesized and the critical micellar concentration of DDBAC measured by surface tentiometry and electric conductivity method was $8.9{\times}10^{-4}M$. Micellar effects in DDBAC functional surfactant solution on the hydrolysis of p-nitrophenylacetate(p-NPA), p-nitro-phenylpropionate(p-NPP) and p-nitrophenylvalerate(p-NPV) were observed with change of various pH (Tris-buffer). The pseudo first rate constants of hydrolysis of p-NPA, p-NPP and p-NPV in optimum concentration of DDBAC solution increase to about 160, 280 and 600 times, respectively, as compared with those of aqueous solution at pH 8.00(Tris-buffer). It is considered that benzimidazole functional moiety accelerates the reaction rates of hydrolysis because they act as nucleophile or general base. In optimum concentration of DDBAC solution, the rate constants of hydrolysis of p-NPP and p-NPV increase to about 1.5 and 3.0 times, respectively, as compared with that of p-NPA. It means that the more the carbon numbers of alkyl group of substrates, the larger the binding constants between DDBAC micelle and substrates are. To know the hydrolysis mechanism of p-NPCE(p-NPA, p-NPP and p-NPV), the deuterium kinetic isotope effects were measured in $D_2O$ solutions. Consequently the pseudo first order rate constant ratios in $H_2O$ and $D_2O$ solution, $k_{H_2O}/k_{D_2O}$, were about $2.8{\sim}3.0$ range. It means that the mechanism of hydrolysis were proceeded by nucleophile and general base attack in approximately same value.

• 한국잡초학회지
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• 제16권4호
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• pp.292-300
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• 1996

벼 담수직파시 제초제에 의한 약해의 원인을 구명하고자 온도, 용액의 pH, 수심, 토성 및 영양(營養)의 유무(有無) 등의 조건하에서 실험을 실시한 결과는 다음과 같다. 1. Bensulfuron methyl 및 pyrazosulfuron-ethyl 처리는 20/$11^{\circ}C$에서 30/22$^{\circ}C$에서보다 벼 생육 억제 정도가 컸으며, 특히 근부(根部)에서 현저히 컸다. Dimepiperate 및 molinate 처리는 저온 (20/$11^{\circ}C$) 고온(30/$22^{\circ}C$) 에서 생육억제 정도가 컸으며 경엽부(莖葉部)에서 현저하였다. 2. 무영양(無營養) 조건에서는 bensulfuron methyl 처리에서, 영양(營養)조건 에서는 pyrazosulfuron-ethyl의 처리에서 생육 억제 정도가 컸다. 3. pH3.5, 5.5, 7.5 및 9.5 용액에 bensulfuron methyl 및 pyrazosulfuron-ethyl 처리시 벼 생육은 pH3.5 및 5.5의 낮은 pH에서 저조하였으며, 무처리 대비한 생육 억제정도는 bensulfuron methyl 처리는 pH5.5 및 7.5에서 pyrazosulfuron-ethyl 처리는 pH7.5 및 pH9.5에서 낮았다. 4. 수심 6cm의 심수조건에 bensulfuron methyl 및 pyrazosulfuron-ethyl 처리시는 근부(根部)의 생육이, dimepiperate 및 molinate의 처리는 경엽부(莖葉部)의 생육이 크게 억제되었으며, 특히 dimepiperate처리는 90% 정도 억제되었다. 또한 pyrazosulfuron-ethyl+molinate의 처리에서 bensulfuron methyl+dimepiperate 처리보다 경엽부(莖葉部)의 억제정도가 컸다. 5. Pyrazosulfuron-ethyl 처리는 무비구는 식양토에서, 시비구는 사양토에서 생육저해 정도가 컸으며, bensulfuron methyl 처리는 사양토에서 생육이 저조한 경향이었다.

• Korean Chemical Engineering Research
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• 제57권1호
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• pp.133-141
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• 2019

침전법으로 환류방법 또는 수열합성법을 이용하여 산 염기점을 갖는 고비표면적 지르코니아를 합성하였다. 제조된 지르코니아는 침전제로 수산화암모늄 수용액을 사용하여 Zr 용액의 pH를 2에서 10 범위 내에서 조절하였으며 질소흡착분석, X-선 회절분석(XRD), 이소프로판올 승온탈착법(IPA-TPD), 주사전자현미경 분석, X-선 광전자분광분석, 산-염기점 분석을 통해 IPA 분해반응의 촉매활성과 연관하여 특성분석을 수행하였다. 환류방법을 사용할 시, tetragonal 상이 높은 지르코니아를 얻기 위해서는 Zr 용액의 pH가 높아야 하며, pH 9 이상에서는 순수한 tetragonal 상의 지르코니아 합성이 가능하였다. 또한, 비표면적이 큰 지르코니아를 얻기 위해서는 높은 pH가 요구되었으며, pH 10에서 합성한 경우에는 $600^{\circ}C$에서 소성 후에도 $260m^2g^{-1}$의 높은 비표면적이 얻어졌다. 하지만 같은 조건 하에서 고압이 수반되는 수열합성에는 $40m^2g^{-1}$ 이하의 매우 낮은 비표면적을 보였으며, monoclinic 상의 지르코니아가 합성되었다. 고 비표면적 tetragonal 상의 지르코니아를 얻기 위해서는 용액의 pH가 가장 큰 영향을 미쳤으며, 용액의 pH와 무관하게 높은 압력이 필요한 수열합성에서는 monoclinic 지르코니아가 생성되었으며 상대적으로 비표면적이 낮게 나타났다. 높은 비표면적과 tetragonal 상을 갖는 지르코니아는 염기점에 비해 산점이 우세하여 IPA 분해반응에서 선택적 탈수반응만 진행되는 프로필렌만 생성되었다.

• 한국광물학회지
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• 제9권1호
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• pp.1-6
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• 1996

Woolastonite from Susan occurs as intercalations in limestone beds of Lower Paleozoic Joseon Supergroup. It is a thermal metamorphic product of impure limestone. Electron microprobe analysis shows that it is considerably pure wollastonite. It has triclinic cell with a=7.932$\AA$, b=7.328$\AA$, c=7.069$\AA$, $\alpha$=89.995$^{\circ}$, $\beta$=$95.255^{\circ}$, and $ \Upsilon=103.367^{\circ}$.Dissolution behaviors of wollastonite have been studied conducting three different dissolution experiments; two different reactions with HC1 (one batch and one re-initialization experiment) and one traction with distilled water. In the batch type powder wollastonite-HCl reaction, pH of solution rapidly increases in the early stage and then its rate of increase slows down to reach plateau resulting in parabolic relationship with time. It is represented by the early rapid rise and fall in pH giving a sharp pH-edge and succeeding slow rise in the re-initialization experiment. The early rapid rise in pH is due to the rapid sorption of H- in solution to oxygens on the reactive surface of wollastonite and the fall in pH means that all reactive surface sites are occupied by H- ions and no more H- adsorption occurs. The slow rise in pH following the pH- edge is due to the dissolution of wollastonite as evidenced by the correlation of pH variation and cation concentration. Dissolution of powder wollastonite in HCl shows linear trend with time. Si is dissolved predominantly over Ca at a constant rate. Ca is dissolved predominantly in the very early stage. Dissolution rate of coarse-grained wollastonite fragments in distilled water is parabolic with times howing a rapid reaction in the early stage and a slow reaction in the advanced stage. The Ca/Si ratio in solution is high in the case of coarse-grained wollastonite fragment as compared with powder wollastonite. The coarse-grained wollastonite fragment-water (acid) reaction resulted in the solution with an elevated constant pH value (alkaline) giving an important significance on the environmental view point.

• 대한화학회지
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• 제44권1호
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• pp.10-16
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• 2000

일반적으로 산성비는 이온세기가 낮아 저항이 크고 완충능이 없는 용액이다. 그러므로 산성비의 pH측정 시, 시료용액의 액간접촉전위는 이온세기의 차이로 인해 pH표준용액의 액간접촉전위와 달라서 pH 측정값에 오차가 발생될 수 있다. 실제 1998년도 대덕연구단지에 내린 빗물의 평균 전도도 값이 12.8 ${\mu}S/cm$인데 비해, pH 표준용액의 전도도 값은 약 5,980 ${\mu}S/cm$으로 이온세기의 차이가 크다. 본 연구에서는 산성비의 pH를 측정할 때 액간접촉전위로 인해 발생되는 오차를 보정하기 위해, 빗물과 비슷한 pH와 전도도를 가지는 묽은 황산의 물성조절표준물(Quality Control Standard, 이하 QCS로 표기)을 제조하여 사용하였다. QCS의 pH값을 액간접합이 없는 수소전극 시스템으로 인증한 다음, 유리전극으로 다시 pH를 측정하여 그 차이값 만큼 보정하였다. 아울려 이 방법으로 1998년도 대덕연구단지에 내린 빗물의 pH를 측정하였다.

• 한국토양비료학회지
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• 제44권2호
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• pp.297-302
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• 2011

Acid drainage generated by pyrite oxidation has caused the acidification of soil and surface water, the heavy metal contamination and the corrosion of structures in abandoned mine and construction sites. The applicability of Na-acetate (Na-OAc) buffer and/or Na-silicate solution was tested for suppressing pyrite oxidation by reacting pyrite containing rock and treating solution and by analyzing solution chemistry after the reaction. A finely ground Mesozoic andesite containing 10.99% of pyrite and four types of reacting solutions were used in the applicability test: 1) $H_2O_2$, 2) $H_2O_2$ and Na-silicate, 3) $H_2O_2$ and 0.01M Na-OAc buffer at pH 6.0, and 4) $H_2O_2$, Na-silicate and 0.01M Na-OAc buffer at pH 6.0. The pH in the solution after the reaction with the andesite sample and the solutions was decreased with increasing the initial $H_2O_2$ concentration but the concentrations of Fe and $SO_4^{2-}$ were increased 10 - 20 times. However, the pH of the solution after the reaction increased and the concentrations of Fe and $SO_4^{2-}$ decreased in the presence of Na-acetate buffer and with increasing Na-silicate concentration at the same $H_2O_2$ concentration. The solution chemistry indicates that Na-OAc buffer and Na-silicate suppress the oxidation of pyrite due to the formation of Fe-hydroxide and Fe-silicate complex and their coating on the pyrite surface. The effect of Na-OAc buffer and Na-silicate on reduction of pyrite oxidation was also confirmed with the surface examination of pyrite using scanning electron microscopy (SEM). The result of this study implies that the treatment of pyrite containing material with the Na-OAc buffer and Na-silicate solution reduces the generation of acid drainage.

• Preventive Nutrition and Food Science
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• 제7권1호
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• pp.52-56
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• 2002

This study was conducted to evaluate the possibility of gamma radiation for reducing egg allergies through the observation of conformational and allergenic changes of egg ovomucoid (OM) in basic pH conditions. An OM solution of 2.0 mg/mL was individually prepared with different pH conditions, pH 7.0, 9.0 or 10.0, and was irradiated with the absorbed dose of 10 kGy. Irradiated OM solutions were tested by Ci-ELISA formatted with egg-hypersensitive patients'IgE. Binding abilities of IgE to OM in irradiated solution decreased with the increase of pH. Turbidity of the solution highly increased by irradiation and the increase of pH. A yellowish color was observed in the irradiated OM solution of basic condition. Coagulation of OM by irradiation decreased with the increase of pH, when observed by SDS-PAGE.