Disulfuric acid dissociated by two water molecules: <i>ab initio</i> and density functional theory calculations

Kim, Seong Kyu,Myoung Lee, Han,Kim, Kwang S. The Royal Society of Chemistry 2015 Physical chemistry chemical physics Vol.17 No.43

<P>We have studied geometries, energies and vibrational spectra of disulfuric acid (H<SUB>2</SUB>S<SUB>2</SUB>O<SUB>7</SUB>) and its anion (HS<SUB>2</SUB>O<SUB>7</SUB><SUP>−</SUP>) hydrated by a few water molecules, using density functional theory (M062X) and <I>ab initio</I> theory (SCS-MP2 and CCSD(T)). The most noteworthy result is found in H<SUB>2</SUB>S<SUB>2</SUB>O<SUB>7</SUB>(H<SUB>2</SUB>O)<SUB>2</SUB> in which the lowest energy conformer shows deprotonated H<SUB>2</SUB>S<SUB>2</SUB>O<SUB>7</SUB>. Thus, H<SUB>2</SUB>S<SUB>2</SUB>O<SUB>7</SUB> requires only two water molecules, the fewest number of water molecules for deprotonation among various hydrated monomeric acids reported so far. Even the second deprotonation of the first deprotonated species HS<SUB>2</SUB>O<SUB>7</SUB><SUP>−</SUP> needs only four water molecules. The deprotonation is supported by vibration spectra, in which acid O–H stretching peaks disappear and specific three O–H stretching peaks for H<SUB>3</SUB>O<SUP>+</SUP> (eigen structure) appear. We have also kept track of variations in several geometrical parameters, atomic charges, and hybrid orbital characters upon addition of water. As the number of water molecules added increases, the S–O bond weakens in the case of H<SUB>2</SUB>S<SUB>2</SUB>O<SUB>7</SUB>, but strengthens in the case of HS<SUB>2</SUB>O<SUB>7</SUB><SUP>−</SUP>. It implies that the decomposition leading to H<SUB>2</SUB>SO<SUB>4</SUB> and SO<SUB>3</SUB> hardly occurs prior to the 2nd deprotonation at low temperatures.</P> <P>Graphic Abstract</P><P>Superacid H<SUB>2</SUB>S<SUB>2</SUB>O<SUB>7</SUB>, attributed to its S–O–S torsional flexibility for many sulfone groups, is deprotonated by two water molecules, which sets a new record for the fewest number of water molecules to induce dissociation of acids. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c5cp05201g'> </P>

Microbacterium xylanilyticum sp. nov., a xylan-degrading bacterium isolated from a biofilm

Kim, Kwang Kyu,Park, Hye Yoon,Park, Wooshin,Kim, In S.,Lee, Sung-Taik Microbiology Society 2005 International journal of systematic and evolutiona Vol.55 No.5

<P>A novel xylan-degrading bacterium, S3-E<SUP>T</SUP>, was isolated from the biofilm of a membrane bioreactor. The cells of this strain were Gram-positive, non-motile, non-spore-forming rods, produced primary branches and formed yellow colonies on nutrient agar. The strain had chemotaxonomic markers that were consistent with classification in the genus <I>Microbacterium</I>, i.e. MK-12, MK-11 and MK-13 as the major menaquinones, predominant iso- and anteiso-branched cellular fatty acids, glucose and galactose as the cell-wall sugars, peptidoglycan-type B2<I>β</I> with glycolyl residues and a DNA G+C content of 69·7 mol%. Phylogenetic analysis, based on 16S rRNA gene sequencing, showed that strain S3-E<SUP>T</SUP> is most similar to <I>Microbacterium hominis</I> IFO 15708<SUP>T</SUP> and <I>Microbacterium foliorum</I> DSM 12966<SUP>T</SUP> (97·6 and 97·4 % sequence similarity, respectively), and that it forms a separate lineage with <I>M. hominis</I> in the genus <I>Microbacterium</I>. DNA-DNA hybridization results and phenotypic properties showed that strain S3-E<SUP>T</SUP> could be distinguished from all known <I>Microbacterium</I> species and represented a novel species, for which the name <I>Microbacterium xylanilyticum</I> sp. nov. is proposed; the type strain is S3-E<SUP>T</SUP> (=DSM 16914<SUP>T</SUP>=KCTC 19079<SUP>T</SUP>).</P>

Species-specific responses of temperate macroalgae with different photosynthetic strategies to ocean acidification: a mesocosm study

Kim, Ju-Hyoung,Kang, Eun Ju,Edwards, Matthew S.,Lee, Kitack,Jeong, Hae Jin,Kim, Kwang Young The Korean Society of Phycology 2016 ALGAE Vol.31 No.3

Concerns about how ocean acidification will impact marine organisms have steadily increased in recent years, but there is a lack of knowledge on the responses of macroalgae. Here, we adopt an outdoor continuous-flowing mesocosm system designed for ocean acidification experiment that allows high CO₂ conditions to vary with natural fluctuations in the environment. Following the establishment of the mesocosm, five species of macroalgae that are common along the coast of Korea (namely Ulva pertusa, Codium fragile, Sargassum thunbergii, S. horneri, and Prionitis cornea) were exposed to three different CO₂ concentrations: ambient (×1) and elevated CO₂ (2× and 4× ambient), over two-week period, and their ecophysiological traits were measured. Results indicated that both photosynthesis and growth exhibited species-specific responses to the different CO₂ concentrations. Most notably, photosynthesis and growth increased in S. thunbergii when exposed to elevated CO₂ conditions but decreased in P. cornea. The preference for different inorganic carbon species (CO₂ and HCO₃⁻), which were estimated by gross photosynthesis in the presence and absence of the external carbonic anhydrase (eCA) inhibitor acetazolamide, were also found to vary among species and CO₂ treatments. Specifically, the two Sargassum species exhibited decreased eCA inhibition of photosynthesis with increased growth when exposed to high CO₂ conditions. In contrast, growth of U. pertusa and C. fragile were not notably affected by increased CO₂. Together, these results suggest that the five species of macroalgae may respond differently to changes in ocean acidity, with species-specific responses based on their differentiated photosynthetic acclimation. Understanding these physiological changes might allow us to better predict future changes in macroalgal communities in a more acidic ocean.

촉매 지지체의 기공특성에 대한 가교제 및 용매의 효과

김광락,정흥석,강희석,이한수,안도희,백승우,이성호 한국공업화학회 1998 응용화학 Vol.2 No.2

Effect of cross-linking agent and solvent on pore characteristics of styrene-divinylbenzene copolymer was investigated experimentally. Influence of cross-linking agent on surface area of the polymeric support was dominant over all the others. Surface area and pore volume of the polymeric support were decreased and the second peak was shifted to large pore size in the pore size distribution with increasing the content of poor solvent in the solvent mixture. When toluene was used as a good solvent, and n-heptane as poor solvent, the optimum range of good/poor solvent ratio was 1.5∼0.7 for styrene-divinylbenzene copolymer of large surface and micropore area and pore volume.

Large-scale pattern growth of graphene films for stretchable transparent electrodes

Kim, Keun Soo,Zhao, Yue,Jang, Houk,Lee, Sang Yoon,Kim, Jong Min,Kim, Kwang S.,Ahn, Jong-Hyun,Kim, Philip,Choi, Jae-Young,Hong, Byung Hee Macmillan Publishers Limited. All rights reserved 2009 Nature Vol.457 No.7230

Problems associated with large-scale pattern growth of graphene constitute one of the main obstacles to using this material in device applications. Recently, macroscopic-scale graphene films were prepared by two-dimensional assembly of graphene sheets chemically derived from graphite crystals and graphene oxides. However, the sheet resistance of these films was found to be much larger than theoretically expected values. Here we report the direct synthesis of large-scale graphene films using chemical vapour deposition on thin nickel layers, and present two different methods of patterning the films and transferring them to arbitrary substrates. The transferred graphene films show very low sheet resistance of ∼280 Ω per square, with ∼80 per cent optical transparency. At low temperatures, the monolayers transferred to silicon dioxide substrates show electron mobility greater than 3,700 cm<SUP>2</SUP> V<SUP>-1</SUP> s<SUP>-1</SUP> and exhibit the half-integer quantum Hall effect, implying that the quality of graphene grown by chemical vapour deposition is as high as mechanically cleaved graphene. Employing the outstanding mechanical properties of graphene, we also demonstrate the macroscopic use of these highly conducting and transparent electrodes in flexible, stretchable, foldable electronics.

수소가 흡착된 W(011)표면의 재구성

김희봉(Kim Hei Bong),최원국(Choi Won Kook),홍사용(S. Y. Hong),황정남(Chung Nam Whang),정광호(Kwang Ho Jeong) 한국진공학회(ASCT) 1992 Applied Science and Convergence Technology Vol.1 No.1

최근 Angle Resolved Ultraviolet Photoemission Spectroscopy(ARUPS)를 통하여 Mo(011)과 W(011)의 surface Fermi contour에 관한 연구가 발표되었다. Hydrogen 흡착시 W(011)의 electron contour는 팽창하였다. 이것은 electron contour를 이루는 surface state가 hydrogen 흡착시 higher binding energy로 이동한 결과이다. Surface state의 higher binding energy로의 이동은 결국 band flattening으로 이해되며, 이 band flattening에 S. E. Trullinger의 long range dipole dipole force와 Kohn anomaly 현상을 부합시켜 W(011) surface에 수소 흡착시 일어나는 reconstruction 현상에 대한 설명을 시도해 보았다. Rencently, angle-resolved ultraviolet photoemission measurements of the Fermi surface contours for Mo(011) and W(011) are reported. The electron contour of W(011) is expanded upon hydrogen adsorption, which implies that the surface states consisting of electron pockets are shifted to higher binding energy. This phenomena can be explained by the band flattening. We explained here the reconstruction of W(011) surface induced by adsorption of hydrogen in terms of band flattening of surface states with a combination of S. E. Trullinger long range dipole-dipole interaction force and Kohn anomaly.

독성물질의 세포사 기전 및 세포사 유발물질의 검색법 개발에 관한 연구(Ⅰ) : 독성물질로 인한 파킨슨병 모델에서의 세포사 기전 연구 Study on the cell-death mechanisms of toxin-induced parkinsonism

강태석,김종민,서경원,김영옥,김준규,오재호,이윤동,김규봉,오정자,송연정,임종준,전범석,문전옥,최광식 식품의약품안전청 2000 식품의약품안전청 연보 Vol.4 No.-

MPTP 독성물질이 도파민성 신경세포에 선택적으로 작용하여 산화성 손상에 의한 신경세포사를 일으키는 것을 이용하여 파킨슨병의 동물모델을 만들고, 이를 통해서 아폼토시스를 비롯한 포사의 기전에 대한 연구 및 너코틴의 신경세포 보호효과 여부를 판정하는 실험을 병행하고자 하였다. 파킨슨꾐의 동물모델을 MPTf 독성 물질을 이용하여 확립하였으며, MPTP(30mgag, i.p.)를 투여한 후 1, 2,3, 4, 5일째 흑질 조직을 채춰하여 tarm로 박걸하여 tyrosine hydroxylase 면역조직화학염색을 수행하여 cell countif우한 결과, control은 57.635ce11s, 1일째 친.OfDells,2일째 57.9±6cells,3일릴 없.3±죠ells, 4일째 49.0츠3cells, 5일째 39.4±Scells료 4, 3일째 뚜렷한 신경세포 수의 감소를 보였다. 신경세포사 기전 규명을 위한 아폼토시스 분걱에서는 벼PTP 투여 후 1, 2, 3, 4, 5일째 조직을 채취하여 Hoechst staining, TUNEL staining을 수곡하였는데 양성 반응을 보인 신경세포는 관찰되지 않아. 아폼토시스로 인한 세포사가 관찰되지 않았다. bIPTP 파킨슨병 동물모델에서 nicotine 보호효과 탐색에 관한 실험은 nicat푸e 0.2mgAg을 5일 퐁안 투여 후 리『fP(30mgag)를 CS7Bt/6 마은스에 복강 내주사로 nicotine과 병용 투여한 후 1, 2, 3, 4, 5일째 뇌를 적출하땄다. 신경세포사가 뚜렷이 관찰되기 시작하는 4, 5일째의 신경세포 수의 감소 정도를 20. 30% 정도 약화시키는 경향을 보였으나, nicotine 보호효과에 대한 추가 실헝이 현재 수행 중에 있다. The cause of Parkinson's disease (PD) is largely unknown. However, free radical toxicit? may plaf a role ip. the degeneration of substantia nigra, which is the Hajorfocus of pathological damages in PD. Recently, a neuroprotective effect of nicotine in PD has been suggested. Therefore, the mechanism of neurodegenerafion and protective potential o( nicotine in PD were investigated in the experimental modeB of Pll using a neurotoxin, C57BL/6mice were administered with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 30 mg/kg,j.p.). The degree of neurodegenerafion was determined by immunohistochemical stainiHB oftyrosine hydroxylase (TH). TH-positive cells on nigral sections were found 56.0 ±4, 57.9 ±6,52.315ce11s, 49.0±3cells, and 39,4±Scells at days 1, 2, 3, 4, 5, respectively (controls : 57.6±Scells). Hoechst and TUNEL staining showed no evidence of apoptosis. The exandnation on themice co-adrunistered with nicotine(0.2mgAg) and MPTP(30mgag) revealed a tendency ofnicotine protective effects. At days 4 and 5, the degree of TH-positive cells was decreased by20-30%, In corclusiffn, the role of apoptosis was not evidenced in this MPTP modeB of PB.The possible proteccon by nicotine should be elucidated with further studies.

국내 TMR의 입자도에 관한 조사 연구

기광석,김현섭,정하연,이현준,안병석,김준식,강수원,김용국,하종규 한국동물자원과학회 2003 한국축산학회지 Vol.45 No.5

This study was carried out to survey operation system of self-making TMR and particle size of self-making and commercial TMR, then to compare TMR particle size recommended by Penn State particle Size Separator. Daily mixing time in self-making TMR averaged 48.6±28.0min, 2 angar type of mixer was most by 55.5% and daily 2 times of mixing in summer and other season was 44.4 and 22.2%, respectively. Percentage of residual feed in upper sieve(19㎜ diameter), middle sieve(8 ti 18㎜ diameter) and lower pen was 21.5~25.6%, 16.0~25.8%, 52.8~61.4%, respectively, at self-making TMR mixer. Percentage of particle sizes of more than 19㎜ in self-making and commercial TMR was 24.9±1.4 and 26.2±1.7%, that of 8-10㎜ 22.8±1.0 and 12.8±1.2 and that of less than 8㎜ 52.3±1.7 and 61.0±1.5, respectively, which in particle length of 8~13㎜ in self-making and commercial TMR was lower by 82.6 and 100% compared to that recommended by Penn State particle separator, respectively. Especially there was not particle length of more than 19㎜ in commercial TMR at all. It is necessary to check the number of cows ruminating in a farm in order to estimate the particle size of TMR; it is recommended to change the TMR mixing time or the TMR formulae if the proportion of ruminating cows in a farm is less than 40%.

REMOVAL OF METAL IONS BY ULTRAFILTRATION OF A MICELLAR SOLUTION CONTAINING ANIONIC SURFACTANT

Yang, Hyun S,Han, Kwang H,Kang, Duck W,Kim, Young Ho 한국화학공학회 1996 Korean Journal of Chemical Engineering Vol.13 No.5

Heavy metals in wastewater were removed by ultrafiltration of a micellar solution containing surfactant such as sodium dodecyl sulfate. Experimental results showed that permeate flux was primarily controlled by the operating parameters such as transmembrane pressure difference, flow rate and feed concentration. The average permeate flux incrcased at a higher transmembrane pressure, feed velocity, and at a lower solution concentration. The transmembrane pressure had a relatively small effect on metal removal whereas the level of surfactant-to-metal ratio (S/M) had a substantial effect. The optimal ratio of S/M for a best removal of metal ions was measured around 5 and 8 in the presence of sodium dodecyl sulfate, and the affinity resulted in the order of Cr$gt;Co$gt;Ni$gt;Mg.

발포 EPP/EPS의 충격특성에 관한 실험적 연구

김한국 ( Han Kook Kim ),김병준 ( Byeoung Jun Kim ),정광영 ( Kwang Young Jeong ),전성식 ( Seong S Cheon ) 한국복합재료학회 2013 Composites research Vol.26 No.6

본 연구에서는 발포 폴리프로필렌(Expanded polypropylene)과 발포 폴리스티렌(Expanded polystyrene)의 준정적 시험(Quasi-static test) 및 계장화 충격 시험(Instrumented impact test)을 수행하였다. EPP와 EPS는 4가지의 다른 밀도에 대해 원통형 시편이 준비되었다. 준정적 시험에는 MTS 858을 사용하여 0.001 s-1과 0.1 s-1 두 가지 변형률속도 조건으로 진행되어 결과를 분석하였다. 계장화 충격 시험에서는 Instron dynatup 9250HV를 사용하여, 각각 100 J, 200 J, 300 J의 서로 다른 충격에너지를 가했을 때의 응력-변형률 선도 결과를 비교 분석하였다. In the present study, quasi-static tests and impact tests were performed for investigating the mechanical behaviour of EPP (Expanded polypropylene) and EPS (Expanded polystyrene). Four different density cylindrical type specimens were prepared for EPP and EPS and 0.001 s-1 and 0.1 s-1 of strain rate conditions for quasi-static tests and 100 J, 200 J and 300 J of incident energy conditions for the instrumented impact tests were considered.