Interannual variation in summer N₂O concentration in the hypoxic region of the northern Gulf of Mexico, 1985-2007

Kim, I.-N.,Lee, K.,Bange, H. W.,Macdonald, A. M. Copernicus GmbH 2013 Biogeosciences Vol.10 No.11

<P><p><strong>Abstract.</strong> Microbial nitrous oxide (N₂O) production in the ocean is enhanced under low-oxygen (O₂) conditions. This is especially important in the context of increasing hypoxia (i.e., oceanic zones with extremely reduced O₂ concentrations). Here, we present a study on the interannual variation in summertime nitrous oxide (N₂O) concentrations in the bottom waters of the northern Gulf of Mexico (nGOM), which is well-known as the site of the second largest seasonally occurring hypoxic zone worldwide. To this end we developed a simple model that computes bottom-water N₂O concentrations with a tri-linear ΔN₂O/O₂ relationship based on water-column O₂ concentrations, derived from summer (July) Texas-Louisiana shelf-wide hydrographic data between 1985 and 2007. &amp;Delta;N₂O (i.e., excess N₂O) was computed including nitrification and denitrification as the major microbial production and consumption pathways of N₂O. The mean modeled bottom-water N₂O concentration for July in the nGOM was 14.5 ± 2.3 nmol L⁻¹ (min: 11.0 ± 4.5 nmol L⁻¹ in 2000 and max: 20.6 ± 11.3 nmol L⁻¹ in 2002). The mean bottom-water N₂O concentrations were significantly correlated with the areal extent of hypoxia in the nGOM. Our modeling analysis indicates that the nGOM is a persistent summer source of N₂O, and nitrification is dominating N₂O production in this region. Based on the ongoing increase in the areal extent of hypoxia in the nGOM, we conclude that N₂O production (and its subsequent emissions) from this environmentally stressed region will probably continue to increase into the future.</p> </P>

Imazethapyr 유도체의 제초활성에 미치는 3-(N-methyl-N-(X)-치환-phenylaminooxoacetyl) group의 영향

성낙도,김현재,장해성,김대황 충남대학교 생물공학연구소 1993 생물공학연구지 Vol.3 No.-

새로운 25종의 Imazethapyr 유도체, (2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-3-(N-methyl-N-(X)치환 -phenylaminooxoacetyl)-5-methylpyridine)들을 합성하여 치환기(X) 변화에 따른 발아 전 후, 피(Echinochla crus-galli.)의 제초활성에 미치는 3-(N-methyl-N-(X)치환 -phenylaminoozoacetyl) group의 영향을 검토한 바, 발아 전보다 발아 후의 제초활성에 더 큰 영향을 미침을 알 수 있었다. 발아 후의 제초활성은 X-치환기의 전자밀게 효과와 입체상수(E_s)에 의존적이었으며 가장 큰 제초활성을 나타내는 화합물로는 bulky(E_s<O)하고 전자밀게 (б<O)가 치환된 화합물, 15(4-t-butyl group)와 20(3,5-dimethyl group)이었다. 그리고 높은 제초활성을 나타낼 것으로 예상되는 화합물의 조건들이 검토되었다. (1993년 9월 18일 접수, 1993년 9월 22일 수리). New twenty five Imazethapyr derivatives, [2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-3-(N-methyl-N-X(sub.)-phenylaminooxoacetyl)-5-methylpyridine] were synthesized. and The quantitative structure activity relationships (QSARs) between their post-emergence herbicidal activity(pI_50) values in vivo against Barnyard grass (Echinochloa crus-galli) and physicochemical parameters of substituents(X) of 3-(N-methyl-N-X(sub.)-phenylaminoo-xoacetyl) group have been studied. From the basis on the findings, in case of post-emergence, the activities were dependent on the steric constant(E_s<θ)and electron donating (o<O) effect by subsitituents(X) of 3-(N-methyl-N-X(sub.)phenylaminooxacetyl) group. Therefore, The most effective compound, 15 (4-t-butyl group) and 20 (3,5-dimethyl group) were examined in this study. And the conditions on the compounds predicted to show higher herbicidal activity were also discussed.

N₂/ CH₄가스비에 따른 Hydrogenated Amorphous Carbon Nitride 박막의 특성

장홍규(H. K. Jang),김근식(G. S. Kim),황보상우(S. W. Whangbo),이연승(Y. S. Lee),황정남(C. N. Whang),유영조(Y. Z. Yoo),김효근(H. G. Kim) 한국진공학회(ASCT) 1998 Applied Science and Convergence Technology Vol.7 No.3

DC saddle-field-plasma-enhanced chemical-vapor deposition(PECVD) 장치를 이용하여 상온에서 p-type Si (100) 기판위에 hydrogenated amorphous carbon nitride [a-C:H(N)]박막을 증착하였다. 원료가스인 CH₄과 N₂의 전체압력은 90 mTorr로 고정하고 N₂/CH₄비를 0에서 4까지 변화하면서 제작한 a-C:H(N) 박막의 미세 구조의 변화를 연구하였다. 진공조의 도달 진공도는 1×10^(-6) Torr이고, 본 실험시 CH₄+N₂가스의 유량은 5 sc㎝으로 고정하고 배기량을 조절하여 진공조의 가스 압력을 90 mTorr로 고정하였으며 기판에 200 V의 직류 bias 전압을 인가하였다. α-step과 X-ray photoelectron spectroscopy(XPS)를 이용한 분석결과 N₂/CH₄비가 0에서 0.5로 증가함에 따라 박막 두께는 4840 Å에서 2600 Å으로 급격히 감소하였으며, 박막내의 탄소에 대한 질소함유량(N/C비)는 N₂/CH₄비가 4일때 최대 0.25로 증가하는 것을 확인하였다. 또한 XPS 스펙트럼의 fitting 결과 N₂/CH₄비가 증가할수록 CN결합이 증가하였다. Fourier Transformation Infrared (FT-IR) 분석결과 N₂/CH₄비가 증가함에 따라 박막내의 C-H 결합은 감소하고, N-H, C≡N 결합은 증가하였다. Optical bandgap 측정 결 과 N₂/CH₄비가 0에서 4로 증가함에 따라 a-C:H(N)박막의 bandgap 에너지는 2.53 eV에서 2.3 eV로 감소하는 것을 확인하였다. Hydrogenated amorphous carbon nitride[a-C:H(N)] films were deposited on p-type Si(100) at room temperature with substrate bias voltage of 200 V by DC saddle-field plasma-enhanced chemical vapor deposition. Effects of the ratio of N₂to CH₄(N₂/CH₄), in the range of 0 and 4 on such properties as optical properties, microstucture, relative fraction of nitrogen and carbon, etc. of the films have been investigated. The thickness of the a-C:H(N) film was abruptly decreased with the addition of nitrogen, but at N₂/CH₄> 0.5, the thickness of the film gradually decreased with the increase of the N₂/CH₄. The ratio of N to C(N/C) of the films was saturated at 0.25 with the increase of N₂/CH₄. N-H, C≡N bonds of the films increased but C-H bond decreased with the increase of N₂/CH₄. Optical band gap energy of the film decreased from 2.53 eV deposited with pure methane to 2.3 eV at the ratio of N₂/CH₄=4.

토코페롤에서 유도된 기능성 화장품용의 새로운 계면 활성제

김영대 ( Y. D. Kim ),김창규 ( C. K. Kim ),이충남 ( C. N. Lee ),하병조 ( B. J. Ha ),이우영 ( W. Y. Lee ) 대한화장품학회 1992 대한화장품학회지 Vol.18 No.1

기능성 화장품을 위한 일련의 새롭고 독특한 비이온 계면활성제들을 생리활성물질인 a-Tocopherol과 에칠렌옥사이드의 반응에 의해서 제조하였다. 반응 생성물의 구조는 H¹-NMR, FT-IR, 원소분석, TLC를 통해 확인하였다. EP0에 대한 POV 와 CDV 연구에서 POE(n)TEs는 모두 토코페릴아세테이트와 유사한 항산화효과를 나타내었다. 그러나 POE(5)TE, POE(10)TE, P0E(18)TE의 광용혈에 대한 세포막보호효과는 Control에 비해 높은 결과를 나타내었다. POE(10)TE의 자외선흡수능은 Homosalate와 유사하게 나타났다. Primary Skin Irritation, Primary Eye Irritation 및 Acute Oral Toxicity 테스트결과 POE(n)TEs의 안전성이 입증되었다. P0E(n)TEs의 계면화학연구에서는 POE(10)TE가 가장낮은 CMC값을 나타내었고, POE(18)TE는 Maximum surface tension reduction과 최대 Foam volume을 보였다. 화장품의 실질적인 응용을 위한 테스트 결과 W/0유화에서는 POE(5>TE, 0/W유화에 서는 POE(10)TE 와 POE(12)TE, 분산에서는 POE(12)TE, 가용화에서는 P0E(18)TE, 겔화에서는 POE(50)TE가 우수하였는데, 이것은 POE(n)TEs의 구조적특성과 Liquid Crystal형성에 기인한 것으로 여겨진다. A new and unique class of nonionic surfactants was synthesized by reacting biological a-tocopherol with ethylene oxide for functional cosmetics. The structures were confirmed by Hl-UMR, FT-lR, TLC and elemental analysis. POV and conjugated diene value study for EPO showed POE(n)TE had antioxidative effect similar to tocopheryl acetate. Protective effect on cell membrane in photohemolysis of POE(5)TE, POE(10)TE and POE(18)TE were slightly lower than tocopherol but higher than nonoxynol-12, and POE(10)TE had UV absorption power comparable with tocopherol and homosalate. Biological activity of the hydrophobic group of the new surfactants make them unique and different from those of conventional nonionic surfactants. Systematic safety evaluations of POE(n)TEs on the skin and eye proved that they are as safe as tocopherol. The results of physicochemical study showed POE(10)TE had the lowest CMC value, POE(18)TE had the maximum surface tension reduction and the highest foam volume and POE(n)TEs had various HLB values by the degree of ethoxylation. The test results of technological and practical applications of these surfactants for cosmetics showed some POE(n)TEs were superior to conventional surfactants. POE(5)TE in W/O emulsions, POE(10)TE and POE(12)TE in O/W emulsions, POE(12)TE in dispersions, POE(18)TE in solubilizations and POE(50)TE in gelations were shown to be excellent which was considered due to the structural characteristic and formation of liquid crystals of POE(n)TEs. By the development and applications of these excel lent multi-functional surfactants, innovative functional cosmetics were successfully formulated.

Effects of N₂addition on chemical etching of silicon nitride layers in F₂/Ar/N₂remote plasma processing

S. M. Park,H. W. Kim,S. I. Kim,Y. B. Yun,N. -E. Lee 한국표면공학회 2007 한국표면공학회 학술발표회 초록집 Vol.2007 No.-

In this study, chemical dry characteristics of silicon nitride layers were investigated in the F₂/N₂/Ar remote plasma. A toroidal-type remote plasma source was used for the generation of remote plasmas. The effects of additive N₂gas on the etch rates of various silicon nitride layers deposited using different deposition techniques and precursors were investigated by varying the various process parameters, such as the F₂flow rate, the addition N₂flow rate and the substrate temperature. The etch rates of the various silicon nitride layers at the room temperature were initially increased and then decreased with the N₂flow increased, which indicates an existence of the maximum etch rates. The etch rates of the silicon oxide layers were also significantly increased with the substrate temperature increased. In the present experiments the F₂gas flow, addition N₂flow rate and the substrate temperature were found to be the critical parameters in determining the etch rate of the silicon nitride layers.

Identification and quantification of seven volatile n-nitrosamines in cosmetics using gas chromatography/chemical ionization-mass spectrometry coupled with head space-solid phase microextraction

Choi, N.R.,Kim, Y.P.,Ji, W.H.,Hwang, G.S.,Ahn, Y.G. Pergamon Press ; Elsevier Science Ltd 2016 Talanta Vol.148 No.-

<P>An analytical method was developed for the identification and quantification of seven volatile n-nitrosamines (n-nitrosodimethylamine [NDMA], n-nitrosoethylmethylamine [NMEA], n-nitrosodiethylamine [NDEA], n-nitrosodipropylamine [NDPA], n-nitrosodibutylamine [NDBA], n-nitrosopiperidine [NPIP], and n-nitrosopyrrolidine [NPYRD]) in water insoluble cream type cosmetics. It was found that the head space-solid phase microextraction (HS-SPME) was suitable for extraction, clean up, and pre-concentration of n-nitrosamines in the cream type samples so its optimal conditions were investigated. Identification and quantification of n-nitrosamines using single quadrupole gas chromatography/mass spectrometry (GC/MS) in chemical ionization (CI) mode were carried out with accurate mass measurements. Their accurate masses of protonated molecular ions were obtained within 10 mDa of the theoretical masses when sufficiently high signal was acquired from the unique calibration method using mass and isotope accuracy. For the method validation of quantification, spiking experiments were carried out to determine the linearity, recovery, and method detection limit (MDL) using three deuterated internal standards. The average recovery was 79% within 20% relative standard deviation (RSD) at the concentration of 50 ng/g. MDLs ranged from 0.46 ng/g to 36.54 ng/g, which was satisfactory for the directive limit of 50 ng/g proposed by the European Commission (EC). As a result, it was concluded that the method could be provided for the accurate mass screening, confirmation, and quantification of n-nitrosamines when applied to cosmetic inspection. (C) 2015 Elsevier B.V. All rights reserved.</P>

계단형 텅스텐 결정면의 질소 흡착에 관한 연구 : Ⅱ. W(210) 및 W(310)면

최대선(D. S. Choi),한종훈(J. H. Han),백선목(S. M. Paik),박노길(N. G. Park),김욕욱(Y. W. Kim),황정남(C. N. Whang) 한국진공학회(ASCT) 1996 Applied Science and Convergence Technology Vol.5 No.4

장전자 방출법으로 텡스텐 (210)면 및 (310)면(100)면의 질소 흡착에 의한 일함수의 변화에 heat of desorption을 측정하였으며 Thermal Desortion Spectra(TDS) 결과로부터 adsorption site를 예측하였다. 텅스텐 (210)면 및 (310)면에 에 질소가 흡착될 때 흡착율에 따라 일함수는 증가하다가 각 면에 대하여 흡착율 5 Langmuir일때 최대 변화량 0.29 eV및 0.20 eV에서 포화되었다. TDS 결과는 이 면들은 낮은 dose의 영역에서 각각 3개의 흡착 site가 있음을 보였으며 이 흡착 site들 중 α₁state의 spectrum의 강도는 (210)면에서 보다 (310)면에서 상대적으로 강해짐을 보였다. 또한 (210)와 (310)면의 α₁ 과 β₂ state의 흡착 site에 흡착된 질소의 dipole moment의 방향은 이 흡착 site들에 대응되는 (100)면의 α₁ 과 β₂state의 흡착 site에 흡착된 질소의 dipole moment의 방향과 반대 방향으로 측정되었으며 이 현상으로부터 질소의 상대적인 흡착 위치를 예측하였다. The heat of desorption and the work function change induced by nitrogen adsorption on the stepped tungstein surface planes, W(210) and W(310), are measured using the Field Electron Emission Microscope(FEM). The adsoption sites are predicted from the Thermal Desortion Spectra(TDS). The work function change of both W(210) and W(310) planes increase as increasing the nitrogen dose and saturates at the nitrogen dose about 5 Langmuir to 0.29 eV and 0.20 ev respectively. We find three adsorption site on each plane for the low dose range. The TDS result shows that the intensity of α₁, state on W(310) is much stronger than that of α₁ state on W(210), and the direction of nitrogen dipole moment adsorbed on the sites correspond to α₁, and β₂ states on W(210) and W(310) planes are in the opposite direction to that of the equivalent states on W(100) plane. From this observation we can predict the relative atomic position in the zdirection (perpendicular direction to the surface) of nitrogen molecules/atoms adsorbed on these sites.

Pulse Shape Discrimination of Nuclear Recoil and Electron Recoil Events With a NaI(Tl) Crystal for Dark Matter Search

Kim, K. W.,Adhikari, G.,Adhikari, P.,Choi, S.,Ha, C.,Hahn, I. S.,Jeon, E. J.,Joo, H. W.,Kang, W. G.,Kim, H. J.,Kim, N. Y.,Kim, S. K.,Kim, Y. D.,Kim, Y. H.,Lee, H. S.,Lee, M. H.,Leonard, D. S.,Oh, S. Y IEEE 2016 IEEE transactions on nuclear science Vol.63 No.2

<P>In order to investigate discrimination between nuclear recoil and electron recoil events for the KIMS-NaI dark matter search experiment, we measured the pulse shapes produced by neutrons and gamma rays in a NaI(Tl) crystal. Relatively good pulse shape discrimination (PSD) power due to high light output of recently developed crystals makes it possible to test whether the annual modulation signal observed by the DAMA/LIBRA experiment is caused by nuclear recoil events. We applied the PSD to underground data taken with a 9.15 kg low-background and high-light-output NaI(Tl) crystal for 134 days. Good agreement between underground data and electron recoil events was observed.</P>

Disposition and metabolism of (2S,3S,4R)-N''-cyano-N-(6-amino-3,4-dihydro-3-hydroxy-2-methyl-2-dimethoxy methyl-2H-benzopyran-4-yl)-N'-benzylguanidine, a novel neuroprotective agent for ischemia-reperfusion damage, in rats

Kim, N. S.,Yoo, H. H.,Lee, M. W.,Kim, H. S.,Kim, D. H. Taylor & Francis 2007 Xenobiotica Vol.37 No.5

<P> The metabolism and disposition of KR31378 (a benzopyran derivative and a novel neuroprotective agent) were investigated following single oral or intravenous administration of [14C]-KR31378 to rats. [14C]-KR31378 was rapidly absorbed after oral dosing with an oral bioavailability of greater than 71%. The maximum plasma concentration and area under the curve of total radioactivity in rat plasma increased proportionally to the administered dose. KR31378 was distributed over all organs and tissues except for brain, eyeball and testis, and declined by first order kinetics up to 24 h after dosing. Excretion of the radioactivity was 29.5% of the dose in the urine and 58.5% in the feces within 2 days after oral administration. Biliary excretion of the radioactivity in bile duct-cannulated rats was about 66.0% for the first 24 h. KR31378 was extensively metabolized by ring hydroxylation, O-demethylation, oxidation and reduction with subsequent N-acetylation and O-glucuronide conjugation. N-acetylated conjugates (M2, M10, M11, M12, M14, and M15) were identified as the predominant metabolites in rats.</P>

Effect of annealing of graphene layer on electrical transport and degradation of Au/graphene/n-type silicon Schottky diodes

Kim, D.J.,Kim, G.S.,Park, N.W.,Lee, W.Y.,Sim, Y.,Kim, K.S.,Seong, M.J.,Koh, J.H.,Hong, C.H.,Lee, S.K. Elsevier Sequoia 2014 JOURNAL OF ALLOYS AND COMPOUNDS Vol.612 No.-

We have investigated the effect of annealing of graphene sheets on the electrical properties of Au/graphene/n-type silicon Schottky diode. Large scale graphene sheets were grown by chemical vapor deposition and then annealed at 300, 400, and 500<SUP>o</SUP>C; one sheet was left un-annealed as the control. The diodes were fabricated by transferring the graphene sheets directly onto n-type Si substrates and the current-voltage (I-V) and capacitance-voltage (C-V) characteristics were evaluated. The average values of the Schottky barrier height (SBH) and ideality factor (η) for the as-fabricated Au/graphene/n-type silicon Schottky diode from I-V measurements were determined to be ~0.8+/-0.01eV and ~1.79+/-0.05, respectively, whereas the SBH from C-V measurements was ~0.89+/-0.01eV. The electrical transport characteristics measured at room temperature indicated that annealing of graphene sheet prior to the transfer of the graphene onto the n-Si substrates significantly reduces the electric degradation of the Schottky diodes, even though no distinct differences in other electric properties, including ideality factors and SBHs, before or after annealing of the graphene sheets were observed. Thus, by simply annealing the graphene sheets at 500<SUP>o</SUP>C, we found that the Au/graphene/n-type silicon Schottky diode showed an approximately 3.3-fold lower series resistance as compared with the un-annealed Schottky diode under air exposure of up to 7days. These annealed diodes showed significantly reduced electrical degradation by removing the potentially trapped H<SUB>2</SUB>O and/or O<SUB>2</SUB> at the interface between the graphene layer and the n-Si substrate.