• Bulletin of the Korean Chemical Society
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• 제27권4호
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• pp.539-544
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• 2006

Proton transfer reactions and ion-molecule reactions of bifunctional ethanes of $H_2NCH_2CH_2NH_2$, $H_2NCH_2CH_2OH$, and $HOCH_2CH_2OH$ were studied using Fourier transform mass spectrometry (FTMS). The rate constants for proton transfer reactions between the fragment ions and neutral molecules were obtained from the temporal variation of the ion abundances. The rate constants were consistent with the heats of reaction. The fastest proton transfer reactions were the reactions of $CH_2N^+$, $CHO^+$, and $CH_3O^+$ for $H_2NCH_2CH_2NH_2$, $H_2NCH_2CH_2OH$, and $HOCH_2CH_2OH$, respectively. The $[M+13]^+$ ion was formed by the ion-molecule reaction between $H_2C=NH_2 ^+$ or $H_2C=OH^+$ and the neutral molecule. The major product ions generated from the ion-molecule reactions between the protonated molecule and neutral molecule were $[2M+H]^+$, $[M+27]^+$, and $[M+15]^+$.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권6호
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• pp.376-385
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• 2001

Considerable attention has been focused in recent years upon the field of biosorption for the removal of metal ions from aqeous effluents. Compared to other technologies, the advan-tages of biosortption are the high purity of the treated waste water and the cheap raw material. Really, the first major challenge for the biosorption field is to select the most promising types of biomass. Abundant biomass types either generated as a waste by-product of large-scale industrial fermentations particularly fungi or certain metal-binding seaweeds have gained importance in re-cent years due to their natural occurrence, low cost and, of course good performance in metal biosorption. Industrial solutions commonly contain multimetal systems or several organic and in organic substances that form complexes with metals at relatively high stability forming a very complex environment. When several components are present, interference and competition phe-nomena for sorption sites occur and lead to a more complex mathematical formulation of the process. The most optimal configuration for continuous flow-biosorption seems to the packed-bed column which gets gradually from the feed to the solution exit end. Owing to the com-petitive ion exchange taking place in the column, one or more of the metals present even at trace levels may overshot the acceptable limit in the column effluent before the breakthrough point of the trargeted metal. Occurrence of 'overshoot's and impact on havey metal removal has not been analyzed enough. New trends in biosorption are discussed in this review.

• Mass Spectrometry Letters
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• 제4권4호
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• pp.71-74
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• 2013

In the present study, we report that the charge-directed (assisted) peptide dissociation products, such as b- and y-type peptide backbone fragments, were the major products in MS/MS and $MS^3$ applications of some o-TEMPO-Bz-C(O)-peptide ions, while radical-driven dissociation products, such as a/x and c/z-type fragments, were previously shown to be the major products in the free radical initiated peptide sequencing mass spectrometry (FRIPS MS). Those o-TEMPO-Bz-C(O)-peptides share a common feature in their sequences, that is, the peptides do not include an arginine residue that has the highest proton affinity among free amino acids. The appearance of b- and y-type fragments as major products in FRIPS MS can be understood in terms of the so-called "mobile-proton model". When the proton is highly mobilized by the absence of arginine, the chare-directed peptide dissociation pathways appear to be more competitive than the radical-driven dissociation pathways, in our FRIPS experiments.

• 대한약침학회지
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• 제14권3호
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• pp.71-79
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• 2011

Objectives : This study was undertaken to identify fibrinolytic proteases from Gloydius blomhoffii siniticus venom and to characterize a major fibrinolytic protease purified from the venom. Methods : The venom was subjected to chromatography using columns of Q-Sepharose and Sephadex G-75. The molecular weights of fibrinolytic proteases showing fibrinolytic zone in fibrin plate assay were determined in SDS-PAGE (Sodium dodecyl sulfate-polyacrylamide gel electrophoresis) The effects of inhibitors and metal ions on fibrinolytic protease and the proteolysis patterns of fibrinogen, gelatin, and bovine serum albumin were investigated. Results : 1) The fibrinolytic fractions of the three peaks isolated from Gloydius blomhoffii siniticus venom contained two polypeptides of 46 and 59 kDa and three polypeptides of 32, 18, and 15 kDa and a major polypeptide of 54 kDa, respectively. 2) The fibrinolytic activity of the purified protease of 54 kDA was inhibited by metal chelators, such as EDTA, EGTA, and 1,10-phenanthroline, and disulfhydryl-reducing compounds, such as dithiothreitol and cysteine. 3) Calcium chloride promoted the fibrinolytic activity of the protease, but mercuric chloride and cobalt(II) chloride inhibited it. 4) The fibrinolytic protease cleaved preferentially A${\alpha}$-chain and slowly B${\beta}$-chain of fibrinogen. It also hydrolyzed gelatin but not bovine serum albumin. Conclusions : The Gloydius blomhoffii siniticus venom contained more than three fibrinolytic proteases. The major fibrinolytic protease was a metalloprotease which hydrolyzed both fibrinogen and gelatin, but not bovine serum albumin.

• 한국재난관리표준학회지
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• 제4권2호
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• pp.65-72
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• 2011

본 연구는 새만금지역에서 재난관리 및 우수이용을 목적으로 강우를 채취하여 pH 측정과 이온성분을 분석하고 강우의 특성 파악과 용수부족에 따른 수자원 대체 가능성 등을 파악하기 위한 기초 자료를 제공하고자 한다. 새만금지역의 강우시료 채취를 위해 안정적 시료 채취와 장비관리의 효율성, 접근성이 높은 지점을 선정하여 1개소의 측정소(수동형 우수채취기(R-100형) 2기 설치)를 운영하였다. 시료채취의 기간은 강수량이 풍부한 2009년 3월부터 2009년 9월까지로 7차에 걸쳐 월별로 1회 이상의 시료를 채취하였다. 강우시료의 음이온 분석결과, 음이온은 $SO{_4}^{2-}$>$NO_3{^-}$>$Cl^-$ 순으로 강우의 pH에 높은 영향을 미치는 것으로 나타났다. 양이온은 $Ca^{2+}$>$K^+$>$NH_4{^+}$>$Na^+$>$Mg^{2+}$ 순으로 영향을 미치는 것으로 나타났으며, $Mg^{2+}$이온은 영향이 거의 없는 것으로 분석되었다. 강우중 이온성분의 농도는 초기강우에서 높게 나타났고, 강수량이 증가함에 따라 대기중 이온성분이 감소되어 중기 이후 강우는 농도가 감소되는 것으로 나타났다. 강우의 월별 pH는 5월이 가장 낮고 다음은 3월로 나타났으며, 황사가 발생한 4월과 강우량과 강우빈도가 높은 6월, 7월 8월과 건조한 9월의 pH는 모두 유사한 분포특성을 나타내었다. 새만금지역의 강우는 외부에서 유입되는 대기오염물질의 영향으로 pH 5.6이하로 약산성을 나타내는 것으로 분석되었다.

• 한국대기환경학회지
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• 제13권5호
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• pp.371-381
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• 1997

Precipitation sampls were collected in Chonju-city during October 1994 to September 1995 and were analysed for major ions (N $a^{+}$, $K^{+}$, $Ca^{2+}$, $Mg^{2+}$, C $l^{[-10]}$ , NO/$_3$, S $O_4$$^{2-}$) and trace metals (Al, Cd, Ni, Pb, Sr, Zn) in addition to pH, in order to understand the chemical characteristics of acid rain and to estimate the origin of the determined ions. Most rain showed a neutral or alkaline character, and only 35% had a pH lower than 5.6. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ are identified as the primary contributors to precipitation acidity in this region. Neutralization of precipitation acidity occurs as a result of the dissolution of alkaline compounds containing $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$. S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ precipitation concentrations exhibit a seasonal pattern in which higher concentrations are observed during spring months and lower concentrations during summer months. However, the seasonal behavior of $H^{+}$ concentrations differs from this pattern, in that the highest concentrations occur during autumn months, owing to the different influence of neutralization processes. In all rain, S $O_4$$^{2-}$ concentration exceeded NO/$_3$$^{[-10]}$ concentration. The contribution of maritime sources to the total S $O_4$$^{2-}$ concentration was very low or negligible. For rain strongly affacted by yellow sand, $Ca^{2+}$, $Mg^{2+}$ and $K^{+}$ ions show a sharp increase in concentration, reflecting the increased amount of dust and soil suspended in atmosphere. At the same time, S $O_4$$^{2-}$ and N $O_3$$^{[-10]}$ concentrations are at their highest levels while $H^{+}$ values are not comparably elevated, presumably beacause much of the acidity has been neutralized by alkaline substances. The seasonal variance of trace metal concentrations in rainwater is similar to that of major cations. The annual wet flux of acidic pollutants and trace metals wat calculated to be as follows: N $O_3$$^{[-10]}$ ; 2.32 g/$m^2$, S $O_4$$^{2-}$, 5.34 g/$m^2$, Al; 6.30 mg/$m^2$, Cd; 0.62 mg/$m^2$, Ni; 4.08 mg/$m^2$, Pb: 9.76 mg/$m^2$, Sr; 5.94 mg/$m^2$, Zn; 111 mg/$m^2$./$m^2$.

• 한국대기환경학회지
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• 제21권4호
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• pp.439-458
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• 2005

An automated analysis system for water soluble constituents in $PM_{2.5}$ has been developed. The system consists of a high capacity multi tube diffusion scrubber (MTDS), a low temperature particle impactor (LTPI), and two ion (anion and cation) chromatography (IC) systems. Atmospheric particles have been collected by passing sample air through a thermostated MTDS followed by a LTPI. This system allows simultaneous measurements of soluble ions in $PM_{2.5}$ at 30 minutes interval. At the air sampling flow rate of 1.0L/min, the detection limits of the overall system are in the order of tens of $ng/m^3$. This system has been successfully used for the measurement of particulate components of Seoul air from April 2003 to January 2004. $SO_4^{2-},\;NO_3^-,\;NH_4^+,\;NO_2^-,\;Cl^-,\;Na^+,\;K^+,\;Ca^{2+},\;and\;Mg^{2+}$ are the major ionic species for $PM_{2.5}$ at Seoul. Among them, $SO_4^{2-},\;NO_3^-\;and\;NH_4^+$ are the most abundant ions, contributed up to $86\%$ of the total and the concentrations were higher than those in any other urban sites in the world except for Chinese cities. There are high pollutant episodes which contribute about $15\~20\%$ of annual average values of the major ions. During the episode, the all parcels were transported from the asian continent and $PM_{2.5}$ were significantly neutralized. This suggests that aged and long range transported pollutants caused the high pollutant episodes. They showed a distinct daily and seasonal variations:they showed a peak in the early morning caused by the night-time accumulation of particulate matters. Atmospheric reactions including gas-to-particle reactions and inter-particle reactions and meteorological parameters including relative humidity and ambient temperature were described with related to the $PM_{2.5}$ 5 concentrations. All of the ionic species showed higher concentrations during the spring than those for summer and winter.

• 한국전기전자재료학회논문지
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• 제36권3호
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• pp.249-254
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• 2023

La_0.7-xCe_xSr_0.3MnO₃ specimens were fabricated by a solid state reaction method and structural and electrical properties with variation of Ce⁴⁺ contents were measured. All specimens exhibited a polycrystalline rhombohedral crystal structure, and the (110) peaks were shifted to low angle side with increasing the amount of Ce⁴⁺ contents. As Ce⁴⁺ ions with different ion radii and charges are substituted with La³⁺ ions, electrical properties are thought to be affected by changes in the double exchange interaction between Mn³⁺-Mn⁴⁺ ions due to distortion of the unit lattice, a decrease in oxygen vacancy concentration, and an increase in lattice defects. Resistivity gradually decrease as the amount of Ce⁴⁺ added increased, and negative temperature coefficient of resistance (NTCR) properties were shown in all specimens. In the La_0.5Ce_0.2Sr_0.3MnO₃ specimens, electrical resistivity, TCR and B-value were 31.8 Ω-cm, 0.55%/℃ and 605 K, respectively.

• 반도체디스플레이기술학회지
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• 제21권2호
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• pp.15-18
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• 2022

The ultraviolet-C emitting praseodymium doped yttrium phosphate (YPO₄:Pr³⁺) powder was synthesized by conventional solid-state reaction. The electroluminescence device was fabricated by simple screen-printing method using the synthesized YPO₄:Pr³⁺ powder, especially, polyvinylidene fluoride as an insulating layer was applied on the printed YPO₄:Pr³⁺ powder for stable performance of the electroluminescence. The electroluminescence properties were investigated under alternating current power system of 400 Hz. The device starts to emit at 350 V, which showed the ultraviolet-C emission peaking at the 233, 245, 264, 273 nm attributed to electronic transition of the Pr³⁺ ions. The electroluminescence intensity was increased as increasing the operating voltage and the device revealed stable performance up to 600 V due to the polyvinylidene fluoride serve as a protective layer.

• 대한환경공학회지
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• 제37권4호
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• pp.197-203
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• 2015

최근 들어 미세먼지에 의한 건강위해성에 대한 많은 문제가 지적되고 있다. 따라서 서울지역은 미세먼지를 줄이기 위한 합리적인 대책과 해결방안이 시급한 실정이다. 미세먼지의 악영향을 줄이기 위해서 우선 미세먼지의 구성성분 중 비율이 가장 많은 이온성분에 대한 명확한 해석이 선결되어야 하고, 이를 바탕으로 미세먼지의 특성을 파악하여 효과적인 저감 대책 수립 및 실천이 진행되어야 한다. 미세먼지 중 이온성분에 대한 물리화학적 특성을 해석하기 위하여 먼저 서울지역에서 미세먼지를 필터에 채취하고 이온성분 분석을 하였다. 그리고 이온크로마토그래피(IC)로 분석이 되지 않는 수소이온($H^+$)과 탄산이온${CO_3}^{2-}$)은 pH와 음이온과 양이온의 당량비 차이로 농도를 추정하였다. 질량수지를 기본원리로 하는 수학적 모델링 적용 결과 음이온과 양이온의 결합형태를 도출할 수 있었다. 미세먼지의 결합에 사용된 이온은 IC로 분석한 8개 이온과 추가로 해석한 $H^+$, ${CO_3}^{2-}$이며, 본 연구에서 나온 존재형태는 $NH_4Cl$, $NH_4NO_3$, $CaSO_4$, $(NH_4)_2SO_4$, $NaNO_3$, NaCl, $Na_2CO$, 그리고 $(NH_4)_2CO_3$ 등이 주를 이루고 있는 것으로 추정되었다.