• 한국토양비료학회지
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• 제49권5호
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• pp.489-494
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• 2016

Carbon-based sorbents such as biochar and activated carbon have been proven to be cost-effective in removing pollutants containing heavy metals from wastewater. The aim of this study was using batch experiment to evaluate the adsorption characteristics of heavy metals in single-metal conditions onto reed biochar for treating wastewater containing heavy metals. The removal rates of heavy metals were in the order of Pb > $Cu{\fallingdotseq}Cd{\fallingdotseq}Zn$, showing the adsorption efficiency of Pb was higher than the other heavy metals. Freundlich and Langmuir adsorption isotherms were used to model the equilibrium adsorption data obtained from adsorption of Pb on reed biochar. For reed biochar, the Langmuir model provided a slightly better fit than the Freundlich model. Lead was observed on the biochar surface after adsorption by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The main functional groups of reed biochar were aromatic carbons. Overall, the results suggested that reed biochar could be useful adsorbent for treating wastewater containing Pb.

• 한국광물학회지
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• 제11권1호
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• pp.20-31
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• 1998

Adsorption of metal elements onto illite and halloysite was investigated at $25^{\circ}C$ using pollutant water collected from the gold-bearing metal mine. Incipient solution of pH 3.19 was reacted with clay minerals as a function of time: 10 minute, 30 minute, 1 hour, 12 hour, 24 hour, 1 day, 2 day, 1 week, and 2 week. Twenty-seven cations and six anions from solutions were analyzed by AAs (atomic absorption spectrometer), ICP(induced-coupled plasma), and IC (ion chromatography). Speciation and saturation index of solutions were calculated by WATEQ4F and MINTEQA2 codes, indicating that most of metal ions exist as free ions and that there is little difference in chemical species and relative abundances between initial solution and reacted solutions. The adsorption results showed that the adsorption extent of elements varies depending on mineral types and reaction time. As for illite, adsorption after 1 hour-reaction occurs in the order of As>Pb>Ge>Li>Co, Pb, Cr, Ba>Cs for trace elements and Fe>K>Na>Mn>Al>Ca>Si for major elements, respectively. As for halloysite, adsorption after 1 hour-reaction occurs in the order of Cu>Pb>Li>Ge>Cr>Zn>As>Ba>Ti>Cd>Co for trace elements and Fe>K>Mn>Ca>Al>Na>Si for major elements, respectively. After 2 week-reaction, the adsorption occurs in the order of Cu>As>Zn>Li>Ge>Co>Ti>Ba>Ni>Pb>Cr>Cd>Se for trace elements and Fe>K>Mn>Al, Mg>Ca>Na, Si for major elements, respectively. No significant adsorption as well as selectivity was found for anions. Although halloysite has a 1:1 layer structure, its capacity of adsorption is greater than that of illite with 2:1 structure, probably due to its peculiar mineralogical characteristics. According to FTIR (Fourier transform infrared spectroscopy) results, there was no shift in the OH-stretching bond for illite, but the ν1 bond at 3695 cm-1 for halloysite was found to be stronger. In the viewpoint of adsorption, illite is characterized by an inner-sphere complex, whereas halloysite by an outer-sphere complex, respectively. Initial ion activity and dissociation constant of metal elements are regarded as the main factors that control the adsorption behaviors in a natural system containing multicomponents at the acidic condition.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2508-2512
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• 2012

Cold shock proteins (CSPs) are a family of proteins induced at low temperatures. CSPs bind to single-stranded nucleic acids through the ribonucleoprotein 1 and 2 (RNP 1 and 2) binding motifs. CSPs play an essential role in cold adaptation by regulating transcription and translation via molecular chaperones. The solution nuclear magnetic resonance (NMR) or X-ray crystal structures of several CSPs from various microorganisms have been determined, but structural characteristics of psychrophilic CSPs have not been studied. Therefore, we optimized the purification process to obtain highly pure Lm-Csp and determined the three-dimensional structure model of Lm-Csp by comparative homology modeling using MODELLER on the basis of the solution NMR structure of Bs-CspB. Lm-Csp consists of a ${\beta}$-barrel structure, which includes antiparallel ${\beta}$ strands (G4-N10, F15-I18, V26-H29, A46-D50, and P58-Q64). The template protein, Bs-CspB, shares a similar ${\beta}$ sheet structure and an identical chain fold to Lm-Csp. However, the sheets in Lm-Csp were much shorter than those of Bs-CspB. The Lm-Csp side chains, E2 and R20 form a salt bridge, thus, stabilizing the Lm-Csp structure. To evaluate the contribution of this ionic interaction as well as that of the hydrophobic patch on protein stability, we investigated the secondary structures of wild type and mutant protein (W8, F15, and R20) of Lm-Csp using circular dichroism (CD) spectroscopy. The results showed that solvent-exposed aromatic side chains as well as residues participating in ionic interactions are very important for structural stability. Further studies on the three-dimensional structure and dynamics of Lm-Csp using NMR spectroscopy are required.

• Molecules and Cells
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• 제27권6호
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• pp.651-656
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• 2009

The formation of ${\beta}$-amyloid peptide ($A{\beta}$) is initiated from cleavage of amyloid precursor protein (APP) by a family of protease, ${\alpha}$-, ${\beta}$-, and ${\gamma}$-secretase. Sub W, a substrate peptide, consists of 10 amino acids, which are adjacent to the ${\beta}$-cleavage site of wild-type APP, and Sub M is Swedish mutant with double mutations on the left side of the ${\beta}$-cleavage site of APP. Sub W is a normal product of the metabolism of APP in the secretary pathway. Sub M is known to increase the efficiency of ${\beta}$-secretase activity, resulting in a more specific binding model compared to Sub W. Three-dimensional structures of Sub W and Sub M were studied by CD and NMR spectroscopy in water solution. On the basis of these structures, interaction models of ${\beta}$-secretase and substrate peptides were determined by molecular dynamics simulation. Four hydrogen bonds and one water-mediated interaction were formed in the docking models. In particular, the hydrogen bonding network of Sub M-BACE formed spread over the broad region of the active site of ${\beta}$-secretase (P5-P3'), and the side chain of P2- Asn formed a hydrogen bond specifically with the side chain of Arg235. These are more favorable to the cleavage of Sub M by ${\beta}$-secretase than Sub W. The two substrate peptides showed different tendency to bind to ${\beta}$-secretase and this information may useful for drug development to treat and prevent Alzheimer's disease.

• 한국염색가공학회지
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• 제21권5호
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• pp.51-57
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• 2009

Since heavy metal pollution is a significant global environmental problem and very dangerous to human health, the improved methods for detecting heavy metals are required recently. Colorimetric chemosensors are now considered as one of the most effective analytical method used in the environment monitoring. New direct dyes having the function of colorimetric chemosensors were synthesized. When metal ions such as $Al^{3+}$, $Ca^{2+}$, $Cd^{2+}$, $Cr^{3+}$, $Cu^{2+}$, $Fe^{2+}$, $Fe^{3+}$, $Hg^{2+}$, $Li^+$, $Mg^{2+}$, $Na^+$, $Ni^{2+}$, $Pb^{2+}$ and $Zn^{2+}$ were added each solution of new direct dyes, the color of solution was changed and can be easily detected with naked eyes without expensive experimental equipment such as atomic absorption spectrometer (AAS) or inductively coupled plasma?mass spectrometer (ICP-MS). The new benzidine analogues were diazotized and reacted with couplers such as H-acid, J-acid, Chromotropic acid, Nevill-winther acid and gamma acid to synthesize new direct dyes. The structures of the new direct dyes were confirmed by high resolution mass spectrometer (FAB ionization) and evaluated with UV-Vis spectroscopy. The UV-VIS spectroscopy was measured for the dye solutions by adding various concentrations of metal ions. It was observed that the absorbance in UV-Vis spectra was changed as the heavy metal ions were added.

• 폴리머
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• 제34권1호
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• pp.69-73
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• 2010

Effects of reaction time and temperature on the isomerization and dehydrobromination reactions of brominated butyl rubber were investigated. The structural composition of brominated butyl rubber was determined by Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy($^1H$-NMR), Density functional theory (DFT) was used to study on the isomerization and dehydrobromination mechanisms of model compounds. The geometries for model compounds of 3-bromo-5,5,7,7-tetramethyl-2(2',2',4',4'-tetramethyl)pentyl-1-octylene (3BrOE), 1-bromo-5,5,7,7-tetramethyl-2(2',2',4',4'-tetramethyl)pentyl-2-octylene (1Br2OE) and 5,5,7,7-tetramethyl-2(2',2', 4',4'-tetramethyl)pentyl-1,3-octadiene (CD) had been optimized by using density functional theory at B3LYP/3-21G and B3LYP/6-31G levels. The predicted energy of 3BrOE lies higher than that of 1Br2OE which suggests that 1Br2OE configuration is more stable than the 3BrOE configuration. Compared with the energy barrier, the pathway of dehydrobromination is less competitive than that of isomerization. This is qualitatively consistent with the experimental results.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.176.2-176.2
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• 2013

Property of optical diagnostics for pulse-discharged plasma in liquid and its biological applications to proteins are investigated by making use of high voltage Marx generator. The Marx generator has been consisted of 5 stages, where each charging capacitor is 0.5 ${\mu}F$, to generate a high voltage pulse with rising time of $1{\mu}s$. We have applied an input voltage of 6 kV to the each capacitor of 0.5 ${\mu}F$. High voltage pulsed plasma has been generated inside a polycarbonate tube by a single-shot operation, where the breakdown voltage is measured to be 7 kV, current of 1.2 kA, and pulse width of ~ 1 ${\mu}s$ between the two electrodes of anode-cathode whose material is made of tungsten pin, which are immersed into the liquids. We have investigated the emitted hydrogen lines for optical diagnostics of high voltage pulsed plasma. The emission line of 656.3 nm from $H-{\alpha}$ and 486.1 nm from $H-{\beta}$ have been measured by a monochromator. If we assumed that the focused plasma regions satisfy the local thermodynamic equilibrium conditions, the electron temperature and density of the high voltage pulsed plasma in liquid could be obtained by the Stark broadening of optical emission spectroscopy. For the investigation of the influence of pulsed plasma on biological proteins, we have exposed it onto the proteins such as hemoglobin and myoglobin. The structural changes in these proteins and their analysis have also been obtained by circular dichroism (CD) and ultraviolet (UV) visible spectroscopy.

• 한국자기공명학회논문지
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• 제9권2호
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• pp.110-121
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• 2005

E.coli methionyl tRNA synthetase consist of 676 amino acids and plays a key role in initiation of protein synthesis. The native form of this enzyme is a homodimer, but the monomeric enzyme truncated approximately C-terminal 120 amino acids retains the full enzymatic activities. X-ray crystal structure of the active monomeric enzyme shows that it has two domains. The N-terminal domain is thought to be a binding site for acceptor stem of tRNA, ATP, and methionine. The C-terminal domain is mainly a-helical and makes an interaction with the anticodon of $tRNA^{Met}$. Especially it is suggested that the region of helix-loop-helix including the tryptophan residue at the position 461 may be the essential for the interaction with anticodon of $tRNA^{Met}$. In this work the structure and function of E. coli methionyl-tRNA synthetase was studied by spectroscopic method (NMR, CD, Fluorescence). The importance of tryptophan residue at the position 461 was investigated by fluorescence spectroscopy. Tryptophan 461 is expected to be an essential site for the interaction between E. coli methionyl-tRNA synthetase and E. coli $tRNA^{Met}$. Proton and heteonuclear 2-dimensional NMR spectroscopy were also used to elucidate the protein-tRNA interaction.

• 한국재료학회지
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• 제31권11호
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• pp.619-625
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• 2021

Cu₂ZnSn(S,Se)₄ (CZTSSe) based thin-film solar cells have attracted growing attention because of their earth-abundant and non-toxic elements. However, because of their large open-circuit voltage (V_oc)-deficit, CZTSSe solar cells exhibit poor device performance compared to well-established Cu(In,Ga)(S,Se)₂ (CIGS) and CdTe based solar cells. One of the main causes of this large V_oc-deficit is poor absorber properties for example, high band tailing properties, defects, secondary phases, carrier recombination, etc. In particular, the fabrication of absorbers using physical methods results in poor surface morphology, such as pin-holes and voids. To overcome this problem and form large and homogeneous CZTSSe grains, CZTSSe based absorber layers are prepared by a sputtering technique with different RTA conditions. The temperature is varied from 510 ℃ to 540 ℃ during the rapid thermal annealing (RTA) process. Further, CZTSSe thin films are examined with X-ray diffraction, X-ray fluorescence, Raman spectroscopy, IPCE, Energy dispersive spectroscopy and Scanning electron microscopy techniques. The present work shows that Cu-based secondary phase formation can be suppressed in the CZTSSe absorber layer at an optimum RTA condition.

• KSBB Journal
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• 제14권6호
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• pp.651-654
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• 1999

재조합 인성장호르몬을 사용하여 in vitro 재접힘 공정(풀림, 희석에 의한 공기 중 산화, 그리고 투석)을 수행하였다. 표면소수성이 풀림-재접힘 공정에 중요한 역할을 한다는 것을 형광값의 변화를 통하여 알 수 있었다. 변성제의 intermediate 농도는 Urea와 Gu-HCl 경우 하나의 peak로 SDS와 Sarkosyl의 경우 두개의 peak로 나타났다. 형광값의 변화 중 특이한 점은 Urea의 경우 공기 중 산화와 투석 중의 후반부에 형광값이 증가한다는 것이다. 따라서 공기 중 산화도중 형광값이 증가하기 전에 투석을 시킨 결과 형광값이 증가를 막을 수 있었다. 아직 이 원인에 대해 자세히 알 수 없지만 계속 실험 중에 있다. 이번 실험에서 표면소수성 변화와 연관시켜 fluorescence를 이황화결합에 의한 산화된 형태를 알아보기 위한 방법으로 RP-HPLC를 마지막으로 단백질의 2차원적인 구조를 알아 보기 위해 CD를 사용하였다. CD측정 결과 Gu-HCl보다 SDS의 경우 ${\alpha}$-helices의 파괴가 더 많음을 볼 수 있었다. 재접힘된 rhGH는 본래의 2차원적 구조의 90%이상을 얻을 수 있었다. 이 실험이 기지는 의의는 이 모든 실험결과를 토대로 단백질 재접힘을 모니터링 하였다는 점이다. 즉, 형광값의 변화를 통하여 형광값이 증가하는 것은 표면 소수성이 증가함을 보이는 것으로 단백질의 풀림이 일어난 것이고 3차원적 구조가 깨지고 2차원 구조를 알아 볼 수 있는 ${\alpha}$-helices의 감소를 의미하였다. 이와는 반대로 형광값이 감소하는 것을 통해 재접힘이 일어남을 알 수 있었고, 이러한 결과를 바탕으로 단백질의 재접힘 공정의 변화과정을 형광값을 통하여 모니터링 할 수 있었다. 또한 이 실험의 목적 단백질은 rhGH이지만 다른 단백질에 적용이 될 경우 단백질 재접힘 과정을 수시로 모니터링하고 상태를 예측할 수 있으므로 산업현장에서 소량의 sample로 재접힘 상태를 쉽고 빠르게 판단할 수 있을 것이다. 단백질 재접힘 과정에서 이러한 개념의 성공적 도입은 단백질 회수 수율을 높임으로써 생물분리공정 분야의 기술 발전에 이바지 하리라 사료된다.