N-doped TiO₂ nanotubes coated with a thin TaO_<i>x</i>N_<i>y</i> layer for photoelectrochemical water splitting: dual bulk and surface modification of photoanodes

Kim, Hyoung-il,Monllor-Satoca, Damiá,n,Kim, Wooyul,Choi, Wonyong The Royal Society of Chemistry 2015 ENERGY AND ENVIRONMENTAL SCIENCE Vol.8 No.1

<P>TaON is a good photoanode material with a suitable band structure for water splitting as well as coupling with TiO<SUB>2</SUB> for efficient charge separation. However, the synthesis of TaON that requires high temperature nitridation (850 °C) limits the combination with other materials. In this work, we deposited a thin amorphous TaO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> layer on N-doped TiO<SUB>2</SUB> nanotubes (N-TNTs) through low temperature nitridation (500 °C) and demonstrated its successful performance as an efficient photoanode for water-splitting. Since the preparation temperature is low, TaO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> on N-TNTs has a unique amorphous structure with a smooth thin layer (5 nm). It is proposed that the thin amorphous TaO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> layer plays dual roles: (i) surface sensitization and/or charge rectification at the heterojunction between the TaO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> layer and N-TNTs, and (ii) passivation of N-TNT surface trap states to retard the charge recombination. TaO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> layer-decorated N-TNTs as dual modified TNTs (N-doping in the bulk and TaO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> overlayer deposition on the surface) have significantly improved both visible (<I>ca.</I> 3.6 times) and UV (<I>ca.</I> 1.8 times) activities for PEC water-splitting as well as the faradaic efficiency (<I>ca.</I> 1.4 times, <I>η</I> = 98%) for H<SUB>2</SUB> production. Making the amorphous TaO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> layer crystalline at higher temperatures reduced the PEC activity of the hybrid photoanode, in contrast, which indicates that the amorphous TaO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> layer deposition on N-TNTs through low temperature nitridation (500 °C) is optimized for the PEC activity. A range of spectroscopic and electrochemical techniques were systematically employed to investigate the properties of the PEC process.</P> <P>Graphic Abstract</P><P>Thin amorphous TaO<SUB><I>x</I></SUB>N<SUB><I>y</I></SUB> layer-coated <I>N</I>-doped TiO<SUB>2</SUB> nanotubes successfully serve as a water splitting photoanode. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4ee02169j'> </P>

Characterization of the N - ras proto - oncogene by PCR - cDNA amplification

Kim, Young Soo,Min, Kyung Rak,Gerald N Wogan 한국유전학회 1989 Genes & Genomics Vol.11 No.4

A 600-base pair cDNA containing the entire rat N-ras coding exonic sequence was amplified by a transcript-PCR method. Sequence comparison of mammalian N-ras genes revealed that the rat N-ras proto-oncogene shared extensive sequence homology with human and mouse N-ras proto-oncogenes. The homology of N-ras in human, mouse, and rat was 90 to 95% in nucleotide sequence. Rat N-ras exhibited 4 amino acid differences when compared to mouse N-ras, 3 of which were in the C-terminal region encoded by exon IV. An evolutionary divergence at position 69 was also found, in which rat N-ras contained glycine but other known mammalian ras proteins including H-, K-, and N-ras have aspartate at position 69 in this highly conserved region. Starting from total RNA derived from the liver of Fischer rat, a double strand cDNA containing two unique endonuclease sites in its termini was obtained within 5 hrs. The terminal endonuclease sites were used for direct cloning into M13 to obtain a library enriched for N-ras proto-oncogene. Screening assay of plaques and sequence analysis of individual cloned cDNA product were used to evaluate the efficency and fidelity of this cDNA amplification-direct M13 cloning procedure. The target N-ras cDNA clones were detected in 5% of the total screened plaques and no sequence errors introduced by the in vitro amplification procedure were observed. This method proved satisfactory for obtaining a complete cDNA sequence of the N-ras proto-oncogene from nanogram quantities of the total liver RNA.

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.

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>

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>

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.

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.

Hydrogen-Release Mechanisms in Lithium Amidoboranes

Kim, Dong Young,Singh, N. Jiten,Lee, Han Myoung,Kim, Kwang S. WILEY-VCH Verlag 2009 Chemistry Vol.15 No.22

<P>Hydrogen storage: In lithium amidoboranes an initial molecule of H<SUB>2</SUB> is released by the formation of LiH, followed by a redox reaction of the dihydrogen bond formed between LiH<SUP>δ−</SUP> and NH<SUP>δ+</SUP>. In this dehydrogenation process, an intermolecular N&n.bond;B bond forms through the catalytic effect of a Li cation. After releasing the first molecule of H<SUB>2</SUB>, a Li cation binds to a nitrogen atom, lowering the energy barrier for the second H<SUB>2</SUB> loss per lithium amidoborane dimer (see figure). <img src='wiley_img/09476539-2009-15-22-CHEM200900092-content.gif' alt='wiley_img/09476539-2009-15-22-CHEM200900092-content'> </P><P>Alkali-metal amidoboranes have been recently highlighted as materials that satisfy many of the criteria required to make hydrogen-storage media. It is, therefore, crucial for us to understand the dehydrogenation mechanism of these materials for further development towards making successful hydrogen-storage media. In the present study, we attempt to shed light on the mechanisms involved in the loss of one molar equivalent of H<SUB>2</SUB> from solid lithium amidoboranes by using high-level ab initio calculations of monomeric and dimeric compounds in the gas phase. In the lithium amidoborane dimer, H<SUB>2</SUB> is released by the formation of LiH, which is followed by a redox reaction of the dihydrogen bond formed between the strongly basic H<SUP>−</SUP> in LiH and H<SUP>δ+</SUP> bonded to N. In the dehydrogenation process, the Li cation catalyzes the intermolecular N&n.bond;B bond formation; this could lead to new pathways for N&n.bond;B polymerization. After the release of the first molecule of H<SUB>2</SUB>, a Li cation binds to a nitrogen atom, resulting in a lowering of the energy barrier for the second dehydrogenation process per dimer. These results will be useful for the design of future hydrogen-storage media.</P> <B>Graphic Abstract</B> <P>Hydrogen storage: In lithium amidoboranes an initial molecule of H<SUB>2</SUB> is released by the formation of LiH, followed by a redox reaction of the dihydrogen bond formed between LiH<SUP>δ−</SUP> and NH<SUP>δ+</SUP>. In this dehydrogenation process, an intermolecular N&n.bond;B bond forms through the catalytic effect of a Li cation. After releasing the first molecule of H<SUB>2</SUB>, a Li cation binds to a nitrogen atom, lowering the energy barrier for the second H<SUB>2</SUB> loss per lithium amidoborane dimer (see figure). <img src='wiley_img/09476539-2009-15-22-CHEM200900092-content.gif' alt='wiley_img/09476539-2009-15-22-CHEM200900092-content'> </P>

N-BACK 프로그램이 뇌졸중 환자의 인지, 시지각, 우울, 불안과 일상생활활동에 미치는 효과

김소영(S. Y. Kim),권상남(S. N. Kwon),김지훈(J. H. Kim) 한국재활복지공학회 2015 재활복지공학회논문지 Vol.9 No.3

본 연구의 목적은 임상에서 사용하고 있는 뇌 자극 훈련인 N-BACK 프로그램을 뇌졸중 환자들에게 적용하여 인지, 시지각, 우울, 불안과 일상생활활동에 미치는 임상적 효과를 증명하고자 하는 것이다. 이를 증명하기 위해 뇌졸중으로 진단받고 유병기간이 6개월 이상인자로 한국판 정신상태판별검사(MMSE-K)에서 18∼23점으로 인지기능 손상이 의심되는 자로써 무작위로 실험군과 대조군 각각 10명씩 선정하였다. 연구자 1인의 진행 하에 임상경력 5년 이상의 숙련된 치료사 8명에 의해 연구가 진행되었으며, 4주간 주 5회 1일 30분, 총 20회를 실시하였다. 그 결과 뇌졸중 환자에게 뇌 자극 훈련인 N-BACK 프로그램을 적용한 실험군이 대조군보다 인지, 시지각, 우울, 불안과 일상생활활동 기능 향상에 긍정적인 결과를 보였다. 이 연구로부터 얻은 결과들은 뇌졸중 환자의 인지, 시지각, 우울 및 불안의 향상을 위해 N-BACK 프로그램을 적용하면 환자의 재활에 긍정적인 효과가 있음을 기대할 수 있고, 그로 인해 일상생활 활동이 보다 독립적으로 향상될 것으로 기대할 수 있다. The purpose of this study was to demonstrate clinical effects on cognition, visual perception, depression, anxiety, and activities of daily living by applying the N-BACK program, a brain stimulated training program, which is used for the clinical purpose. To prove this, subjects suspected of cognitive impairment with 18-23 points in a Korean version of mental status examination (MMSE-K) were recruited among the population who had been diagnosed with stroke duration and suffered from it for six months of duration, and 10 of the subjects were selected into the experimental group and the control group, respectively. A total of 20 sessions were carried out for 30 minutes per day 5 times for 4 weeks. As a result, the experimental group who has been applied the N-BACK program showed positive results in the improvement of cognition, visual perception, depression, anxiety, and daily living skills. The results obtained from this study expect us that applying the N-BACK program for the improvement of cognition, visual perception, depression, and anxiety to stroke patients has a positive effect on the rehabilitation of patients and will lead them to improve daily living activities more independently.

Adsorption of sodium dodecyl sulfate on cleaning of an N-polar GaN surface in an alkaline solution

Kim, M.S.,Paluvai, N.R.,Kim, H.T.,Park, J.G. Elsevier 2017 Materials science & engineering. B, Advanced funct Vol.222 No.-

<P>The present study investigated the removal of contaminated particles from a polished N-polar GaN surface using an alkaline cleaning solution along with sodium dodecyl sulfate (SDS) surfactant. The zeta potential, etch rate, and particle removal efficiency (PRE) of N-polar GaN surfaces were reported. A lower etch rate and smoother N-polar GaN surface were obtained when the surface is treated with a diluted NH4OH solution. However, the etch rate and PRE of the N-polar GaN surface increased as a function of the pH of the NH4OH solution. The PRE of the N-polar GaN surface reached to 96% at pH 10 with a high surface roughness of 0.5 nm. SDS was added to the ammonia solutions to control the surface roughness. The N-polar GaN surface reached 100% PRE and surface roughness shown less than 0.4 nm when cleaned in a diluted NH4OH solution with 5 mM SDS surfactant in a megasonic bath. (C) 2017 Elsevier B.V. All rights reserved.</P>