세관 양광주 방전에서 플라즈마 확산의 완전 해

김동준,정종문,김정현,황하청,정재윤,조윤희,임현교,구제환,최은하,조광섭,Jin, D.J.,Jeong, J.M.,Kim, J.H.,Hwang, H.C.,Chung, J.Y.,Cho, Y.H.,Lim, H.K.,Koo, J.H.,Choi, E.H.,Cho, G.S. 한국진공학회 2010 Applied Science and Convergence Technology Vol.19 No.1

관경이 수 mm인 세관 램프 내부에서 플라즈마의 확산을 조사하기 위하여 이극성(ambipolar) 확산방정식을 해하였다. 반경 방향의 확산에 의한 유리관 벽에서의 플라즈마 소멸 특성시간은 $\tau_r\;=\;(r_0/2.4)^2/D_a$로 주어진다. 반경 $r_0{\sim}1\;mm$이고 이극성 확산계수 $D_a{\sim}0.01\;m^2/s$ 이면, $\tau_r{\sim}17\;{\mu}s$이다. 이는 램프의 교류전원 구동에서 플라즈마를 유지하기 위한 구동 최소 주파수 ~30 kHz에 해당한다. 고전압이 인가되는 전극부에 발생한 고밀도의 플라즈마가 양광주로 확산되는 특성시간은 $\tau_z{\sim}0.1\;s$이다. 고밀도 플라즈마 경계에서의 시간에 대한 확산속도는 $t{\sim}10^{-6}\;s$일 때 $u_D{\sim}10^2\;m/s$이고, $t{\sim}10^{-3}\;s$이면 그 속도는 $u_D{\sim}1\;m/s$로 느려진다. 따라서 램프 길이 ~1 m에 대하여 전극부에서 생성된 고밀도 플라즈마가 양광주 전체로 확산되는 시간은 수 초가 걸린다. The ambipolar diffusion equation has been solved in a fine-tube lamp of a few mm in diameter. In the diffusion of radial direction, the plasma diffuses and vanishes away at the glass wall by recombination with the characteristic time of plasma loss is given by $\tau_r\;=\;(r_0/2.4)^2/D_a$. With the radius $r_0{\sim}1\;mm$ and the ambipolar diffusion coefficient $D_a{\sim}0.01\;m^2/s$, the vanishing time is calculated $\tau_r{\sim}10\;{\mu}s$ which corresponds to the least value of frequency 30 kHz for the sustaining the plasma in the operation of high voltage AC-power. In the diffusion of longitudinal z-direction, a high density plasma generated at the area of a high voltage electrode, diffuses into the positive column with the characteristic time $\tau_z{\sim}0.1\;s$. The plasma diffusion velocity at the boundary of high density plasma is $u_D{\sim}10^2\;m/s$ at the time $t{\sim}10^{-6}$ s and the diffusion velocity becomes slow as $u_D{\sim}1\;m/s$ at $t{\sim}10^{-3}\;s$. Therefore, for the long lamp of 1 m, it takes about several seconds for the high density plasma at the area of electrode to diffuse through the whole positive column space.

Dual-layered nanocomposite substrate membrane based on polysulfone/graphene oxide for mitigating internal concentration polarization in forward osmosis

Lim, Sungil,Park, Myoung Jun,Phuntsho, Sherub,Tijing, Leonard D.,Nisola, Grace M.,Shim, Wang-Geun,Chung, Wook-Jin,Shon, Ho Kyong Elsevier 2017 Polymer Vol.110 No.-

<P><B>Abstract</B></P> <P>A novel thin-film composite (TFC) forward osmosis (FO) membrane with dual-layered substrate membrane was fabricated by a double-blade casting technique using different polysulfone (PSf) concentrations for top (15 wt%) and bottom (7 wt%) substrate layers. Graphene oxide (GO) was incorporated in the substrate layer, and the dual casting approach resulted in a membrane support with a highly porous bottom structure and a dense top skin layer on which the polyamide active layer was effectively formed. The dual-layered TFC PSf/GO membrane (TFC-PSf<SUB>d</SUB>GO) exhibited high water permeability, and ion selectivity was enhanced by the presence of well dispersed hydrophilic GO in the PSf substrate. The TFC-PSf<SUB>d</SUB>GO also exhibited the lowest specific reverse salt flux (<I>J</I> <SUB> <I>s</I> </SUB> <I>/J</I> <SUB> <I>v</I> </SUB> = 0.19 g L<SUP>-1</SUP>) and a more favorable structural parameter (S = 130 μm) compared to GO-free membranes. Using deionized water as feed solution and 1 M NaCl as draw solution (DS), TFC-PSf<SUB>d</SUB>GO had <I>J</I> <SUB> <I>v</I> </SUB> = 33.8 L m<SUP>−2</SUP> h<SUP>−1</SUP> and <I>J</I> <SUB> <I>s</I> </SUB> = 6.9 g<SUP>−2</SUP> h<SUP>−1</SUP> under AL-FS mode, and <I>J</I> <SUB> <I>v</I> </SUB> = 61.5 L m<SUP>−2</SUP>h<SUP>−1</SUP> and <I>J</I> <SUB> <I>s</I> </SUB> = 14.0 g<SUP>−2</SUP> h<SUP>−1</SUP> under AL-DS mode. The potential of TFC-PSf<SUB>d</SUB>GO for commercial application was further evaluated by fabricating it with a fabric backing support (denoted as TFC-PSf<SUB>d</SUB>GO<SUB>f</SUB>). Compared to TFC-PSf<SUB>d</SUB>GO, TFC-PSf<SUB>d</SUB>GO<SUB>f</SUB> exhibited only 14% decline in its water flux. The overall results reveal that, fabrication of TFC substrate membrane via dual-blade casting approach along with GO incorporation produced high-performance TFC FO membranes which likely reduced the internal concentration polarization effects.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The dual-layered PSf/GO membrane was developed to mitigate the ICP effect. </LI> <LI> The dual-layered PSf substrates exhibited higher porosity and water permeability. </LI> <LI> Incorporation of GO further improved hydrophilicity of membrane substrate. </LI> <LI> The dual-layered PSf/GO membrane demonstrated the best membrane performances. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Properties of MTiO₃ (M = Sr, Ba) and PbM'O₃(M'= Ti, Zr) Superlattice Thin Films Fabricated by Laser Ablation

Lim, T.M.,Park, J.Y.,Han, J.S.,Hwang, P.G.,Lee, K.H.,Jung, K.W.,Jung, D. Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.1

$BaTiO_3/SrTiO_3$ and $PbTiO_3/PbZrO_3$ superlattice thin films were fabricated on $Pt/Ti/SiO_2/Si$ substrate by the pulsed laser deposition process. The morphologies and physical properties of deposited films were characterized by using X-ray diffractometer, HR-SEM, and Impedance Analyzer. XRD data and SEM images of the films indicate that each layer was well deposited alternatively in the superlattice structure. The dielectric constant of $BaTiO_3/SrTiO_3$ superlattice thin film was higher than that of individual $BaTiO_3$ or $SrTiO_3$ film. Same result was obtained in the $PbTiO_3/PbZrO_3$system. The dielectric constant of a superlattice film was getting higher as the number of layer is increased.

SNP typing in Korean Native Chicken Mitochondrial D-loop region for Breed Identification

M. R. Hoque(라세둘),B. S. Kang,H. K. Lim,K. D. Choi,J. H. Lee 한국가금학회 2010 한국가금학회 정기총회 및 학술발표회 Vol.27 No.-

The mitochondrial (mt) DNA D-loop sequences have been widely used for identification of origin of the breeds in animals. In this study, single nucleotide polymorphisms (SNP) from chicken mtDNA were investigated for identifying breed differences between the two commercial Korean native chicken (KNC) breeds. A total of 566 individual birds were used in this study. Of these, 280 mtDNA sequences were obtained from different chicken breeds. The sequence data indicated that there are 14 mtDNA clades from the 27 nucleotide variations. We also investigated whether the D-loop hypervariable region in chicken mtDNA found four specific SNPs can be used for the breed identification. In addition to our previous study, three more SNPs were also included for discrimination of KNC breeds. Using the seven SNPs markers, the probabilities of breed identification in CCP1 and CCP2 were 78.4% and 90.8%, respectively. The results obtained in this study can help for the consumers when they select the KNC meats.

Changes in the Central Dopaminergic Systems in the Streptozotocin-induced Diabetic Rats

Lim, D.K.,Lee, K.M.,Ho, I.K. The Pharmaceutical Society of Korea 1994 Archives of Pharmacal Research Vol.17 No.6

The behavioral response, depamine metabolism, and characteristics of dopamine subtypes after developing the hyperlycemia were studied in the striata of rats. In animals developed hyperglycemia, the on-set duration of cataleptic behavior responded to SCH 23390 injection was delayed abd shortened, respectively. However, the cataleptic response to spiperone occurred significantly earlier in on-set and prolonged in duration. Dopamine metabolites, dihydroxyphenylacetic acid (DDPAC) and homovanillic acid (HVA), were significantly reduced in teh striata of hyeprglycemic rats. However, level of DA was significantly increased. It is noted that the ratios of DOPAC and HVA to DA were decreased, suggesting decreased tumover of DA. The affinity of striatal D-1 receptors was significantly increased without changes in the number of binding sites, while the maximum binding number of D-2 recptors was significantly increased without affecting its affinity in the diabetic rats. These results indicate that the dopaminergic activity in striatia was altered in hyperglycemic rats. Furthermore, it suggests that the upregulation of dopamine receptors might be due to the decreased dopamine matabolism.

Effect of bamboo oil on antioxidative activity and nitrite scavenging activity

Choi, D.,Cho, K.A.,Na, M.S.,Choi, H.S.,Kim, Y.O.,Lim, D.H.,Cho, S.J.,Cho, H. Korean Society of Industrial and Engineering Chemi 2008 Journal of industrial and engineering chemistry Vol.14 No.6

The purposes of this study were to investigate the effects of the bamboo oil on antioxidative activity and nitrite scavenging activity in vitro and in vivo. When the bamboo oil concentration was increased from 10 to 90μL/mL, the DPPH scavenging rate increased from 15.6 to 98.2%. However, at bamboo oil concentrations above 110μL/mL, it was not increased. The superoxide anion radical scavenging rate increased from 54.8 to 89.1% when the bamboo oil concentration increased from 110 to 150μL/mL. When the bamboo oil was incubated for 20h, the linoleic acid scavenging rate was approximately 91.2%, similar to that of ascorbic acid. The glutathione production using bamboo oil in vivo was 59.0μM/g of liver, which was about 6.5-fold higher than that of the control. In the case of the activities of glutathione peroxidase and catalase, they were 16.8U/mg of protein and 295KU/mg of protein, respectively, approximately 5.6-fold higher and 3.0-fold higher than that of the control. The nitrite scavenging activity was increased from 60.1 to 93.9% at pH of 1.2 when the saturation time was increased from 2 months to 8 months. However, at more than 10 months of saturation, this level was not increased. These results suggest that the bamboo oil of Phyllostachys nigra var. henonis can be used in bioactive and functional materials.

The LIM-only transcription factor LMO2 determines tumorigenic and angiogenic traits in glioma stem cells

Kim, S-H,Kim, E-J,Hitomi, M,Oh, S-Y,Jin, X,Jeon, H-M,Beck, S,Jin, X,Kim, J-K,Park, C G,Chang, S-Y,Yin, J,Kim, T,Jeon, Y-j,Song, J,Lim, Y C,Lathia, J D,Nakano, I,Kim, H Macmillan Publishers Limited 2015 CELL DEATH AND DIFFERENTIATION Vol.22 No.9

Glioblastomas (GBMs) maintain their cellular heterogeneity with glioma stem cells (GSCs) producing a variety of tumor cell types. Here we interrogated the oncogenic roles of Lim domain only 2 (LMO2) in GBM and GSCs in mice and human. High expression of LMO2 was found in human patient-derived GSCs compared with the differentiated progeny cells. LMO2 is required for GSC proliferation both in vitro and in vivo, as shRNA-mediated LMO2 silencing attenuated tumor growth derived from human GSCs. Further, LMO2 is sufficient to induce stem cell characteristics (stemness) in mouse premalignant astrocytes, as forced LMO2 expression facilitated in vitro and in vivo growth of astrocytes derived from Ink4a/Arf null mice and acquisition of GSC phenotypes. A subset of mouse and human GSCs converted into vascular endothelial-like tumor cells both in vitro and in vivo, which phenotype was attenuated by LMO2 silencing and promoted by LMO2 overexpression. Mechanistically, the action of LMO2 for induction of glioma stemness is mediated by transcriptional regulation of Jagged1 resulting in activation of the Notch pathway, whereas LMO2 directly occupies the promoter regions of the VE-cadherin gene for a gain of endothelial cellular phenotype. Subsequently, selective ablation of human GSC-derived VE-cadherin-expressing cells attenuated vascular formation in mouse intracranial tumors, thereby significantly prolonging mouse survival. Clinically, LMO2 expression was elevated in GBM tissues and inversely correlated with prognosis of GBM patients. Taken together, our findings describe novel dual roles of LMO2 to induce tumorigenesis and angiogenesis, and provide potential therapeutic targets in GBMs.

Hexacyanometallates for sodium-ion batteries: insights into higher redox potentials using d electronic spin configurations

Kim, D.,Hwang, T.,Lim, J. M.,Park, M. S.,Cho, M.,Cho, K. Royal Society of Chemistry 2017 Physical chemistry chemical physics Vol.19 No.16

<P>A fundamental understanding of anomalous redox mechanisms in hexacyanometallate compounds, compared with conventional NaMO2 systems (M: transition metals), is presented based on first-principles calculations and experimental validations. From theoretical calculations, we identified low-spin and high-spin states of Fe ions coordinated by the cyanide group (-CN) with the same oxidation state (Fe2+) in Na2Fe2(CN)(6). Considering the site dependency of d electronic spin configurations based on the crystal field theory (CFT) of transition metals (TMs), we calculated the thermodynamic mixing energy using Na2Fe2(CN)(6) and Na2Mn2(CN)(6) for obtaining a thermodynamically stable phase of Na2FeMn(CN)(6). The phase stabilities of Na2Fe2-xMnx(CN)(6) among many atomic configurations and lattice parameters originating from octahedral structures (i.e., Fe(CN)(6) and Mn(NC)(6)) are highly dependent on the electronic structures of TMs with spin states. From partial density of states (PDOS) and spatial electron distributions, it was observed that Fe2+ in the low-spin state (t(2g)(6)) and Mn2+ in the high-spin states (t(2g)(3) and e(g)(2)) in the stable phase lead to higher redox potentials (similar to 3.55 V vs. Na/Na+) with the removal of Na+ as compared to that of Na2Fe2(CN)(6). In addition, lattice parameters from x = 0 to x = 1 in Na2Fe2-xMnx(CN)(6) are increased due to the larger ionic radius of Mn2+ in the high-spin states. On the other hand, Fe2+ in the high-spin states (t(2g)(4) and e(g)(2)) and Mn2+ in the low-spin state (t(2g)(5)) in the most unstable phase of Na2FeMn(CN)(6) would have lower redox potentials. Based on the fundamental correlation between redox potentials and CFT with spin configurations of TMs, we suggest a material design concept for intercalation compounds with higher energy densities for rechargeable battery systems.</P>

Piezoelectric and field emitted properties of controlled ZnO nanorods on CNT yarns

Seo, M.,Jung, Y.,Lim, D.,Cho, D.,Jeong, Y. North-Holland 2013 Materials letters Vol.92 No.-

ZnO nanorods were synthesized on carbon nanotube (CNT) yarns by an electrochemical deposition method. The grown ZnO shapes varied from a sharp cone-type nanorod to a hexagonal type nanorod according to the increase of counter electrodes. A hexagonal type nanorod changed about 0.3% of its static dimension when it was exposed to an external electric field. From an external pressure with a constant force is applied to the hexagonal type ZnO nanorods, a voltage was generated from 7.5mV to 10mV. A cone-type nanorod showed a remarkable field emission whose threshold voltage was as low as 1.5V/μm. As the results of piezoelectric and field emission tests, the ZnO nanorods on CNT yarn could be a useful material in the applications of a power generator and an emitter.

Discrimination of Korean Native Chicken Populations Using SNPs from mtDNA and MHC Polymorphisms

Hoque, M.R.,Lee, S.H.,Jung, K.C.,Kang, B.S.,Park, M.N.,Lim, H.K.,Choi, K.D.,Lee, J.H. Asian Australasian Association of Animal Productio 2011 Animal Bioscience Vol.24 No.12

Korean native chickens are a very valuable chicken population in Korea and their prices are higher than that of commercial broilers. In order to discriminate two commercial Korean native chicken populations (CCP1 and CCP2), single nucleotide polymorphisms (SNPs) from mitochondrial (mt) DNA D-loop sequences and LEI0258 marker polymorphisms in the major histocompatibility complex (MHC) region were investigated. A total of 718 birds from nine populations were sampled and 432 mtDNA sequences were obtained. Of these, two commercial Korean native chicken populations (363 birds) were used for investigation of their genetic relationship and breed differentiation. The sequence data classified the chickens into 20 clades, with the largest number of birds represented in clade 1. Analysis of the clade distribution indicated the genetic diversity and relation among the populations. Based on the mtDNA sequence analysis, three selected SNPs from mtDNA polymorphisms were used for the breed identification. The combination of identification probability (Pi) between CCP1 and CCP2 using SNPs from mtDNA and LEI0258 marker polymorphisms was 86.9% and 86.1%, respectively, indicating the utility of these markers for breed identification. The results will be applicable in designing breeding and conservation strategies for the Korean native chicken populations and also used for the development of breed identification markers.