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.

General Formulas for Evaluation of Singular Modulus of the Complete Elliptic Integral

K. R. Vasuki,G. Sharath,N. Bhaskar 장전수학회 2010 Advanced Studies in Contemporary Mathematics Vol.20 No.1

The complete elliptic integral of the first kind K(k) is defined for 0 < k < 1 by K(k) := π /2Ɵ=0dƟ/√1 − k2 sin2 ƟThe real number k is called the modulus of the elliptic integral. The complementary modulus is k' = √1 − k2 (0 < k' < 1). Let ⋋ be a positive integer. The equation K(k') = √K(k),defines a unique real number k(k') (0 < k' < 1) called the singular modulus of K(k). In this paper, we establish certain general formulas for evaluating k(λ), by employing Ramanujan’s modular equation.

Measurement of $^{93}Nb(n,n{\alpha})^{89m}Y$, $^{93}Nb(n,{\alpha})^{90m}Y$ and $^{93}Nb(n,2n)^{92m}Nb$ Cross Sections for 14 MeV Neutrons

김영석,김낙배,정기형,박혜일,Kim, Y.S.,Kim, N.B.,Chung, K.H.,Bak, H.I. Korean Nuclear Society 1986 Nuclear Engineering and Technology Vol.18 No.2

The $^{93}Nb(n,n\alpha)^{89m}Y$, $^{93}Nb(n,{\alpha})^{90m}Y$ and $^{93}Nb(n,2n)^{92m}Nb$ cross sections at a neutron energy of 14.6 MeV have been measured relative to the $^{27}Al(n,p)^{27}Mg$ and $^{27}Al(n,{\alpha})^{24}Na$ cross sections. A small accelerator utilizing $T(D,n)^4He$ reaction was used as a neutron source and the neutron energy spread is about 0.4MeV at the sample. All induced activities were measured with a 70cc HPGe detector in the same geometry.

질소 시비량이 정예피의 생육특성 , 수량 , 및 조성분 함량에 미치는 영향

조남기,강영길,조영일,부창훈 한국동물자원과학회 2001 한국축산학회지 Vol.43 No.2

A native cultivar of Japanese millet [Echinochloa crusgalli var. frumentacea (Roxb.) W. F. Wight) was grown with N rates of 0, 50, 100, 150, 200, and 250 ㎏/㏊ from 31 May to 6 September in 1999 to determine the optimum N rate for forage production in a volcanic ash soil of Jeju island. Half of N fertilizer rate was applied at planting and half at 60 days after planting. Days to heading increased from 84 to 90 days as nitrogen rate increased from 0 to 250㎏/㏊. Plant height increased from 144 to 183 cm with increasing nitrogen rate. However, there was no significant difference between 200 and 250 ㎏ N/㏊ for the two characteristics. Increasing N rate from 0 to 250 ㎏/㏊ increased dry matter (DM) yield from 6.76 to 12.67 MT/㏊, crude protein yield from 0.47 to 1.21 MT/㏊, and total digestible nutrients (TDN) yield from 3.46 to 7.18 MT/㏊. However, no significant differences in these yields were found between 200 and 250 ㎏ N/㏊. Nitrogen uptake increased from 75.1 to 194.2 ㎏/㏊ but N use efficiency decreased from 90.0 to 65.2 ㎏ DM/㎏ N with increasing N from 0 to 250 ㎏/㏊. As N rate increased from 0 to 250 ㎏/㏊, CP and TDN contents increased from 6.9 to 9.6% and from 51.3 to 56.7%. respectively. while crude fiber content decreased from 39.5 to 35.9%. Ether extract and nitrogen free extract contents increased up to 200 ㎏ N/㏊ and then did not significantly increase with the further increase in N rate. Crude ash content decreased up to 200 ㎏ N/㏊ and then did not significantly decrease with the further increase in N rate. Based on the these findings, the optimum N rate for forage production of Japanese millet seems to be about 200 ㎏/㏊ in volcanic ash soils of Jeju island.

Neutron-Induced Activation Cross Sections on Hafnium Isotopes from the Threshold to 20 MeV

V. Semkova,N. Janeva,N. Koyumdjieva,R. Jaime Tornin,A. Moens,A. J. M. Plompen,K. Volev 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Results of new cross section measurements are presented for the following neutron-induced reactions: ^(178)Hf(n,α)^(175)Yb, ^(180)Hf(n,α)^(177)Yb, ^(177)Hf(n,p)^(177)Lu^g, ^(178)Hf(n,x)^(177)Lu^g, ^(180)Hf(n,p)^(180)Lu, ^(180)Hf(n,n'α)^(180)Hf^m, ^(174)Hf(n,2n) ^(173)Hf, ^(176)Hf(n,2n)^(175)Hf, and ^(177)Hf(n,3n)^(175)Hf obtained with the activation technique. The irradiations were carried out at the 7-MV Van de Graaff accelerator at IRMM, Geel. Quasi monoenergetic neutrons with energies between 14.8 and 20.5 MeV were produced via the ^3H(d,n)^4He reaction at E_d = 1, 1.4, 2, 3, and 4 MeV. The ^3H(p,n)^3He reaction was employed for the production of neutrons in the 2 - 3 MeV energy range. Both natural and enriched samples were used to facilitate correction for interference between reactions leading to the same product. The radioactivity of the samples was determined by standard γ-ray spectrometry using HPGe detector. The current measurements are compared with the data from other authors and Evaluated Nuclear Data Files. Cross sections for three of the studied reactions are reported for the first time.

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>

Harmonic decomposition of two particle angular correlations in Pb-Pb collisions at s_NN=2.76 TeV

ALICE Collaboration,Aamodt, K.,Abelev, B.,Abrahantes Quintana, A.,Adamova, D.,Adare, A.M.,Aggarwal, M.M.,Aglieri Rinella, G.,Agocs, A.G.,Agostinelli, A.,Aguilar Salazar, S.,Ahammed, Z.,Ahmad, N.,Ahmad North-Holland Pub. Co 2012 Physics letters: B Vol.708 No.3

Angular correlations between unidentified charged trigger (t) and associated (a) particles are measured by the ALICE experiment in Pb-Pb collisions at s<SUB>NN</SUB>=2.76 TeV for transverse momenta 0.25<p<SUB>T</SUB><SUP>t,a</SUP><15 GeV/c, where p<SUB>T</SUB><SUP>t</SUP>>p<SUB>T</SUB><SUP>a</SUP>. The shapes of the pair correlation distributions are studied in a variety of collision centrality classes between 0 and 50% of the total hadronic cross section for particles in the pseudorapidity interval |η|<1.0. Distributions in relative azimuth Δφ=φ<SUP>t</SUP>-φ<SUP>a</SUP> are analyzed for |Δη|=|η<SUP>t</SUP>-η<SUP>a</SUP>|>0.8, and are referred to as ''long-range correlations''. Fourier components V<SUB>nΔ</SUB>≤cos(nΔφ)> are extracted from the long-range azimuthal correlation functions. If particle pairs are correlated to one another through their individual correlation to a common symmetry plane, then the pair anisotropy V<SUB>nΔ</SUB>(p<SUB>T</SUB><SUP>t</SUP>,p<SUB>T</SUB><SUP>a</SUP>) is fully described in terms of single-particle anisotropies v<SUB>n</SUB>(p<SUB>T</SUB>) as V<SUB>nΔ</SUB>(p<SUB>T</SUB><SUP>t</SUP>,p<SUB>T</SUB><SUP>a</SUP>)=v<SUB>n</SUB>(p<SUB>T</SUB><SUP>t</SUP>)v<SUB>n</SUB>(p<SUB>T</SUB><SUP>a</SUP>). This expectation is tested for 1≤n≤5 by applying a global fit of all V<SUB>nΔ</SUB>(p<SUB>T</SUB><SUP>t</SUP>,p<SUB>T</SUB><SUP>a</SUP>) to obtain the best values v<SUB>n</SUB>{GF}(p<SUB>T</SUB>). It is found that for 2≤n≤5, the fit agrees well with data up to p<SUB>T</SUB><SUP>a</SUP>~3-4 GeV/c, with a trend of increasing deviation as p<SUB>T</SUB><SUP>t</SUP> and p<SUB>T</SUB><SUP>a</SUP> are increased or as collisions become more peripheral. This suggests that no pair correlation harmonic can be described over the full 0.25<p<SUB>T</SUB><15 GeV/c range using a single v<SUB>n</SUB>(p<SUB>T</SUB>) curve; such a description is however approximately possible for 2≤n≤5 when p<SUB>T</SUB><SUP>a</SUP><4 GeV/c. For the n=1 harmonic, however, a single v<SUB>1</SUB>(p<SUB>T</SUB>) curve is not obtained even within the reduced range p<SUB>T</SUB><SUP>a</SUP><4 GeV/c.

Synthesis of nitrogen-doped multilayer graphene from milk powder with melamine and their application to fuel cells

Zhao, H.,Hui, K.S.,Hui, K.N. Pergamon Press ; Elsevier Science Ltd 2014 Carbon Vol.76 No.-

We reported on the facile synthesis of N-doped multilayer graphene (N-MLG) from milk powder that uses melamine as a nitrogen-doping source with Fe<SUP>2+</SUP> ions as catalytic growth agents. We showed that milk powder could be used as a precursor for large-scale N-MLG synthesis through heat treatment at 1000<SUP>o</SUP>C under N<SUB>2</SUB> atmosphere for 45-120min. In addition, heating time has a remarkable effect on N content and type in N-MLG. The resulting N-MLG exhibited higher catalytic activity than undoped graphene and carbon nanotubes (CNTs), as well as comparable catalytic activity to commercial Pt/C catalyst toward oxygen reduction reaction (ORR). Furthermore, the catalytic activity was sensitive to N content and type, particularly the ratio of pyridinic-N to total N atoms. Results showed that Fe atoms in N-MLG were found to function not as synergetic catalysts for ORR but as catalytic growth agents for N-MLG formation, thereby promoting and stabilizing N atoms. The present method could lead to the synthesis of bulk amounts of N-MLG, which is promising for applications in electrochemical energy devices, such as fuel cells and metal-air batteries.

쥐의 근육 및 간장 콜레스테롤 수준에 미치는 사료 중 n-3 / n-6 지방산 , PUFA / SFA 및 MUFA / SFA 비율의 반응표면 분석

박병성(B . S . Park),고병대(B . D . Ko),이영철(Y . C . Rhee),황보종(J . Howang - Bo),성기승(K . S . Seong),이남형(N . H . Lee) 한국영양사료학회 1995 韓國營養飼料學會誌 Vol.19 No.5

Diabetes augments cognitive dysfunction in chronic cerebral hypoperfusion by increasing neuronal cell death: Implication of cilostazol for diabetes mellitus-induced dementia

Kwon, K.J.,Lee, E.J.,Kim, M.K.,Kim, S.Y.,Kim, J.N.,Kim, J.O.,Kim, H.J.,Kim, H.Y.,Han, J.S.,Shin, C.Y.,Han, S.H. Blackwell Science ; Academic Press 2015 Neurobiology of disease Vol.73 No.-

Many patients with diabetes are at increased risk of cognitive dysfunction and dementia. Diabetes mellitus is a vascular risk factor that may increase the risk of dementia through its associations with vascular dementia. We tested whether cognitive impairment could be exacerbated in combined injury using a rat model of chronic cerebral hypoperfusion with diabetes. We also determined whether a potent inhibitor of type III phosphodiesterase could prevent the cognitive decline caused by this combined injury. We used Otsuka Long-Evans Tokushima Fatty (OLETF) rats as a model of type II diabetes (T2DM) and Long-Evans Tokushima Otsuka (LETO) rats as a control. Chronic cerebral hypoperfusion was modeled by permanent bilateral common carotid artery occlusion (BCCAO). At 24weeks, the non-diabetic and T2DM rats were randomly assigned into groups for the following experiments: analysis I (1) sham non-diabetic rats (n=8); (2) hypoperfused non-diabetic rats (n=9); (3) sham T2DM rats (n=8); (4) hypoperfused T2DM rats (n=9); analysis II- (1) sham T2DM rats without treatment (n=8); (2) cilostazol-treated T2DM rats (n=8); (3) hypoperfused T2DM rats (n=9); and (4) hypoperfused T2DM rats and cilostazol treatment (n=9). The rats were orally administered cilostazol (50mg/kg) or vehicle once a day for 2weeks after 24weeks. Rats performed Morris water maze tasks, and neuronal cell death and neuroinflammation were investigated via Western blots and histological investigation. Spatial memory impairment was exacerbated synergistically in the hypoperfused T2DM group compared with the hypoperfused non-diabetic group and sham T2DBM group (P<0.05). Compared with the control group, neuronal cell death was increased in the hippocampus of the hypoperfused T2DM group. Cilostazol, a PDE-3 inhibitor, improved the memory impairments through inhibition of neuronal cell death, activation of CREB phosphorylation and BDNF expression in the hypoperfused T2DM group. Our experimental results support the hypothesis that there are deleterious interactions between chronic cerebral hypoperfusion and T2DM. That is, metabolic diseases such as diabetes may exacerbate cognitive impairment in a rat model of vascular dementia. We also suggest that surprisingly, the phosphodiesterase III inhibitor, cilostazol may be useful for the treatment of cognitive impairment in diabetes mellitus-induced dementia. In conclusion, diabetes can aggravate cognitive dysfunction in vascular dementia, and PDE-3 inhibitors, such as cilostazol, may form the basis of a novel therapeutic strategy for diabetes-associated cognitive impairment or vascular dementia.