• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
• /
• pp.222-232
• /
• 2000

The relationship between carrier electron concentration(n) and atmosphere oxygen partial pressure($P_{O_2}$ for pure ZnO calculated by the mass-action law, well-known as n ${\propto}P^{-1/m}_{O_2}$ where m = 4 or 6 for the single or the double ionization of the native donor defects due to its nonstoichiometry, respectively, is found in competition with the calculation result on the basis that the total defect concentration is the sum of those of unionized and ionized defects. Definitively, it is found inconsistent with the calculation result by employing the Fermi-Dirac(FD) statistics for their ionization processes. By application of the FD statistics law to the ionization while assuming the defect formation is still ruled by the mass-action law, the calculation results shows the concentration is proportional to $P^{-1/2}_{O_2}$ whenever they ionize singly and/or doubly. Conclusively we would like to propose the new theoretical relation n ${\propto}P^{-1/m}_{O_2}$ because the ionization processes of donors in ZnO should be treated with the electronoccupation probability at localized quantum states in its forbidden band created by the donor defects, i.e. the FD statistics

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제21권3호
• /
• pp.88-94
• /
• 2016

The simultaneous biodegradation between MTBE (Gasoline additives) and BTEX (Benzene, Toluene, Ethyl-benzene, o-Xylene, m-Xylene, p-Xylene) was achieved within a competitive inter-relationship, with not only electron accepters such as nitrate, sulfate, and iron(III) without oxygen, but also with electron donors such as MTBE and BTEX. Preexisting indigenous microorganisms from a domestic sample of gasoline contaminated soil was used for a lab-scale batch test. The result of the test showed that the biodegradation rate of MTBE decreased when there was co-existing MTBE and BTEX, compared to having just MTBE present. The growth of indigenous microorganisms was not affected in the case of the MTBE treatment, whereas the growth of the microorganisms was decreased in combined MTBE and BTEX sample. This may indicate that an inhibitor related to biodegradation when BTEX and MTBE are mixed will be found. This inhibitor may be found to retard the anaerobic conditions needed for efficient breakdown of these complex carbon chain molecules in-situ. Moreover, it is also possible that an unknown competitive reaction is being imposed on the interactions between MTBE and BTEX dependent on conditions, ratios of mixture, etc.

• Bulletin of the Korean Chemical Society
• /
• 제30권10호
• /
• pp.2233-2239
• /
• 2009

In the present study, firstly, the variations of the geometric parameters induced by different substituents on boroxine skeleton (symmetrically H, $CH_3$, Cl, F, $NO_2$ substituted boroxines) are investigated by using B3LYP/6-31G(d,p), RHF/6-31G(d,p), and MP2/6-31G(d,p) levels of the theory. The second objective is to estimate the substituent effect on the molecular aromaticity of boroxine derivatives using energetic and NICS criteria. Moreover, the effects of different theoretical levels on NICS values have been investigated in a systematic approach. Lastly, a rotational analysis has been performed to investigate the effect of rotation around the B-Me and B-$NO_2$ bonds on total energy of the system. It has been found that electron withdrawing substituents contribute the aromaticity of boroxine affirmatively. Conversely, electron donors make the system less aromatic. Also, the theoretical vibrational spectra for these boroxine derivatives are presented and compared with the experimental data from the literature.

• 한국환경과학회지
• /
• 제16권10호
• /
• pp.1147-1155
• /
• 2007

The applicability of in situ biobarrier or microbial filter technology for the remediation of groundwater contaminated with chlorinated solvent was investigated through column study. In this study, the effect of packing materials on the reductive dechlorination of PCE was investigated using Canadian peat, Pahokee peat, peat moss and vermicompost (or worm casting) as a biobarrier medium. Optimal conditions previously determined from a batch microcosm study was applied in this column study. Lactate/benzoate was amended as electron donors to stimulate reductive dechlorination of PCE. Hydraulic conductivity was approximately $6{\times}10^{-5}-8{\times}10^{-5}\;cm/sec$ and no difference was found among the packing materials. The transport and dispersion coefficients determined from the curve-fitting of the breakthrough curves of $Br^-$ using CXTFIT 2.1 showed no difference between single-region and two-region models. The reductive dechlorination of PCE was efficiently occurred in all columns. Among the columns, especially the column packed with vermicompost exhibited the highest reductive dechlorination efficiency. The results of this study showed the promising potential of in situ biobarrier technology using peat and vermicompost for the remediation of groundwater contaminated with chlorinated solvents.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제14권6호
• /
• pp.29-34
• /
• 2009

본 연구에서는 질산염(${NO_3}^-$)과 용존산소(DO)에 의한 생물학적 퍼클로레이트 환원의 저해 그리고 전자공여체를 차지하기 위한 이러한 전자수용체들의 경쟁적 관계를 조사하고자 염소이온프로브(chloride ion probe)를 직접적인 측정방법으로 사용하였다. 퍼클로레이트 환원미생물을 포함하는 플라스크에서 염소이온프로브를 이용하여 염소생성 (=퍼클로레이트 환원)을 모니터링하였다. 2 mM 퍼클로레이트의 생물학적 환원은 2 mM의 질산염에 의해 저해를 받았으며, 염소이온 생성율이 퍼클로레이트가 단독으로 존재하는 경우에 비해 30% 정도 감소하였고, 아세테이트가 제한된 상태이며 질산염과 퍼클로레이트가 공존하는 경우는 염소이온의 생성율이 약 70% 정도 감소하였다. 7-8 mg/L의 용존산소와 2 mM의 퍼클로레이트가 공존하는 조건에서 아세테이트의 공급정도와 상관없이 퍼클로레이트의 생물학적 환원작용이 완벽하게 저해를 받았다.

• 대한화학회지
• /
• 제20권5호
• /
• pp.380-390
• /
• 1976

전자 공여체로서 할로겐으로 치환되어 있는 아니솔 유도체들(아니솔, 4-클로로아니솔, 2,3-디클로로 아니솔, 2-플루오로-4-클로로아니솔, 2-브로모-4-클로로아니솔, 2-요도드-4-클로로아니솔, 2-브로모 4,6-디클로로아니솔, 2-요오드-4,6-디클로로 아니솔, 2-요오드-2,4,6-드리클로로아니솔)을 쓰고 전자를 받아들이는 화합물로서는 요오드 또는 염화 요오드를 사용하여 그 사이에 생성되는 전하이동 착물에 관하여서 사염화탄소 또는 헥산을 용매계로 하여 연구하여 보았다. 연구한 결과로서 착물의 생성량이 벤젠고리의 2-치환 할로겐 원자의 Van der Waals 반경에 따라서 영향을 받음이 확인 되었으며 더 나아가서 전자 공여 화합물 분자의 입체적 배치 환경에 의하여서도 역시 영향을 받고 있음을 알 수 있었다. 이와 같은 경향은 클로로포름과의 착물 생성에서도 핵자기 공명분석법으로 확인될 수 있었다. 분광 분석법으로 얻은 착물 생성에 관한 데이터를 제시하였으며 벤젠고리에 치환된 2-할로겐 원자의 입체구조와의 상호관계를 논의하였다.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2003년도 생물공학의 동향(XII)
• /
• pp.539-542
• /
• 2003

SDS-PAGE 결과 elution pH에 따라 분리되는 band pattern은 비슷하게 2band의 양상을 보이지만, FI값을 비교하여 보았을 때 다른 pH보다 8.0에서 가장 높은 수준을 보였으므로 GFPuv/cytochrome c-552 fusion Protein의 분리 ${\cdot}$ 정제에 가장 적합한 pH를 8.0으로 정하였다.

• Journal of Photoscience
• /
• 제10권1호
• /
• pp.127-148
• /
• 2003

Zeolite is a porous highly interactive matrix. Zeolitic cations help to generate triplets from molecules that possess poor intersystem crossing efficiency. Certain zeolites act as electron acceptors and thus can spontaneously generate radical cations. Zeolites also act as proton donors and thus yield carbocations without any additional reagents. These reactive species, radical cations and carbocations, have long lifetime within a zeolite and thus lend themselves to be handled as ‘regular’ chemicals. Internal structure of zeolites is studded with cations, the counter-ions of the anionic framework. The internal constrained structure and the cations serve as handles for chemists to control the behavior of guest molecules included within zeolites.

• Bulletin of the Korean Chemical Society
• /
• 제35권10호
• /
• pp.3009-3014
• /
• 2014

A palladium-catalyzed C-H arylation reaction of nitroimidazoles and nitropyrazoles was developed using aryl bromides as arene donors. The electron-withdrawing effect of the nitro group allows for direct C-H arylation reactions of the nitro diazoles with high regioselectivity under mild conditions. The new C-H arylation approach is thus complementary to nucleophilic substitution reactions, enabling the preparation of complex nitroazole compounds.

• 한국재료학회지
• /
• 제16권7호
• /
• pp.412-415
• /
• 2006

Te-doped $CoSb_3$ was prepared by the encapsulated induction melting, and its doping effects on the thermoelectric properties were investigated. Single phase ${\delta}-CoSb_3$ was successfully obtained by the subsequent annealing at 773 K for 24 hrs. Tellurium atoms acted as electron donors by substituting antimony atoms. Thermoelectric properties were remarkably improved by the appropriate doping. Dimensionless figure of merit was obtained to be 0.83 at 700K for the $CoSb_{2.8}Te_{0.2}$ specimen.