Tailoring the characteristics of graphite oxides by different oxidation times

Jeong, H K,Jin, M H,So, K P,Lim, S C,Lee, Y H Institute of Physics [etc.] 2009 Journal of Physics. D, Applied Physics Vol.42 No.6

<P>Graphite oxide was synthesized using various oxidation times and characterized by its physical and chemical properties. The degree of oxidation of the graphite oxide was systematically controlled via oxidation time up to 24 h. Three phases of interlayer distances were identified by x-ray diffraction: pristine graphite (3.4 Å), intermediate (4 Å) and fully expanded graphite oxide (6 Å) phases. These phases were distinguished by an atomic ratio of O/C, which occurred from the different compositions of epoxide, carboxyl and hydroxyl groups. The band gap of the graphite oxides was also tuned via the oxidation time, resulting in direct band gap engineering from 1.7 to 2.4 eV and strong correlation with the atomic ratio of O/C.</P>

Effects of ginsenoside on large-conductance K_Ca channels in human corporal smooth muscle cells

Sung, H H,Chae, M R,So, I,Jeon, J-H,Park, J K,Lee, S W Macmillan Publishers Limited 2011 International journal of impotence research Vol.23 No.5

Ginseng was known to be an effective natural product that enhances penile erection. However, the precise biological function and mechanisms of action of ginseng with regard to erectile function remain unknown. The principal objective of this study was to identify ginsenoside (principal molecular ingredients of ginseng)-induced activation of large-conductance K<SUB>Ca</SUB> channel in human corporal smooth muscle cells, and to determine ginseng's mechanism of action on penile erection. Electrophysiological studies using cultured human corporal smooth muscle cells were conducted. We evaluated the effects of total ginsenosides (TGS) and ginsenoside Rg3 on large-conductance K<SUB>Ca</SUB> channel by determining whole-cell currents and single-channel activities. There was an increase in outward current dependent on TGS concentration (at +60 mV, 1 μg ml<SUP>−1</SUP>; 168.3±59.3%, n=6, P<0.05, 10 μg ml<SUP>−1</SUP>; 173.2±36.8%, n=4, P<0.05, 50 μg ml<SUP>−1</SUP>; 295.3±62.3%, n=19, P<0.001, 100 μg ml<SUP>−1</SUP>; and 462.3±97.1%, n=5, P<0.001) and Rg3 concentration (at +60 mV, 1 μM (0.78 μg ml<SUP>−1</SUP>); 222.8±64.8%, n=11, P<0.0001, 10 μM; 672.6±137.1%, n=10, P<0.0001, 50 μM; and 1713.3±234.7%, n=15, P<0.001) in the solution that was blocked completely by tetraethylammonium (TEA). Channel opening in cell-attached mode and channel activity in the inside-out membrane patches was also increased significantly by 50 μg of TGS or 10 μM of Rg3. The results of this study suggested that the activation of large-conductance K<SUB>Ca</SUB> channels by ginsenoside could be one mechanism of ginsenoside-induced relaxation in corporal smooth muscle.

農村地域의 영아사망 및 出産에 關한 硏究

朴敬姬,韓卿燮,朴南永,李仁辛,邵淑貞,金聖九 國立保健硏究院 1977 국립보건연구원보 Vol.14 No.-

Effect of ultrasonic treatment on swine wastewater solubilization

Lee, Y. H.,Kim, S.-M.,Na, S.,So, K.-H.,Nam, J.-J. IWA Publishing 2009 Water Science & Technology Vol.59 No.3

<P>In order to accelerate hydrolysis known to be the rate-limiting step of the overall digestion process for swine wastewater, an ultrasonic treatment process was tested for the solubilization of the swine wastewater. The effectiveness of ultrasonic solubilization of the swine wastewater under various operational conditions was compared by means of an increment of soluble organics in the treated swine wastewater and the hydrolysis rate constant. Ultrasonic treatment resulted in the high degree of solubilization of particulate organics in the swine wastewater and the degree of solubilization increased with increasing supplied energy. The highest extent of an increment of SCOD concentration and SCOD/TCOD ratio at the end of the operation time of 60 min was 109.7 and 117.5%, respectively, under 120 W power output and 20oC operating temperature conditions. The observed highest hydrolysis rate constant described by pseudo-first order rate constant was 2.94 h−1 under the same conditions. Based on the estimated activation energy from modeling using the Arrhenius equation, ultrasonic solubilization of the swine wastewater under higher supplied energy conditions was more dependent on the operating temperature, which was consistent with the experimentally obtained results. Based on the investigation into the effect of gas type and gas delivery methods for ultrasonic solubilization of the swine wastewater, oxygen gas bubbling through the liquid showed the highest degree of an increment of soluble organics possibly attributed to the influent of oxygen in an increase of radicals during the sonolysis.</P>

Subregular Points for Some Cases of Lie Algebras

Kim, Y . K .,Choi, S . H .,Jeong, J . W .,So, K . H .,Park, D . Y . 호남수학회 1999 호남수학학술지 Vol.21 No.1

Dimensions of irreducible so_5(F)-modules aver an algebraically closed field F of characteristic p$gt;2 shall be obtained. It turns out that they should be coincident with p^m, where 2m is the dimension of coadjoint orbits of χ∈so_5(F)%* \ 0 as Premet asserted. But there is no subregular point for g=sp_4(F)=so_5(F) over F.

Induction of bone formation by <i>Escherichia coli</i>‐expressed recombinant human bone morphogenetic protein‐2 using block‐type macroporous biphasic calcium phosphate in orthotopic and ectopic rat models

Park, J‐,C.,So, S‐,S.,Jung, I‐,H.,Yun, J‐,H.,Choi, S‐,H.,Cho, K‐,S.,Kim, C‐,S. Blackwell Publishing Ltd 2011 Journal of periodontal research Vol.46 No.6

<P><I>Park J‐C, So S‐S, Jung I‐H, Yun J‐H, Choi S‐H, Cho K‐S, Kim C‐S. Induction of bone formation by</I> Escherichia coli<I>‐expressed recombinant human bone morphogenetic protein‐2 using block‐type macroporous biphasic calcium phosphate in orthotopic and ectopic rat models. J Periodont Res 2011; 46: 682–690. © 2011 John Wiley & Sons A/S</I></P><P><B>Background and Objective: </B> The potential of the <I>Escherichia coli</I>‐expressed recombinant human bone morphogenetic protein‐2 (ErhBMP‐2) to support new bone formation/maturation using a block‐type of macroporous biphasic calcium phosphate (bMBCP) carrier was evaluated in an orthotopic and ectopic rat model.</P><P><B>Material and Methods: </B> Critical‐size (Φ 8 mm) calvarial defects and subcutaneous pockets in 32 Sprague–Dawley rats received implants of rhBMP‐2 (2.5 μg) in a bMBCP carrier or bMBCP alone (control). Implant sites were evaluated using histological and histometric analysis following 2‐ and 8‐wk healing intervals (eight animals/group/interval).</P><P><B>Results: </B> ErhBMP‐2/bMBCP supported significantly greater bone formation at 2 and 8 wk (10.8% and 25.4%, respectively) than the control at 2 and 8 wk (5.3% and 14.0%, respectively) in calvarial defects (<I>p</I> < 0.01). Bone formation was only observed for the ErhBMP‐2/bMBCP ectopic sites and was significantly greater at 8 wk (7.5%) than at 2 wk (4.5%) (<I>p</I> < 0.01). Appositional and endochondral bone formation was usually associated with a significant increase in fatty marrow at 8 wk. The bMBCP carrier showed no evidence of bioresorption.</P><P><B>Conclusion: </B> ErhBMP‐2/bMBCP induced significant bone formation in both calvarial and ectopic sites. Further study appears to be required to evaluate the relevance of the bMBCP carrier.</P>

현미 조질에 관한 연구(Ⅰ) : 조질 후 현미의 물성 변화와 예측모델 Property variation and predicted model of brown rice after conditioning

한충수,연광석,강태환,전홍영,고학균,서정덕,송대빈 한국농업기계학회 2001 바이오시스템공학 Vol.26 No.1

ALD of Hafnium Dioxide Thin Films Using the New Alkoxide Precursor Hafnium 3-Methyl-3-pentoxide, Hf(mp)₄

Cho, W.,An, K.-S.,Chung, T.-M.,Kim, C. G.,So, B.-S.,You, Y.-H.,Hwang, J.-H.,Jung, D.,Kim, Y. WILEY-VCH Verlag 2006 Chemical vapor deposition Vol.12 No.11

<P>A new alkoxide precursor, Hf(mp)<SUB>4</SUB> [mp = 3-methyl-3-pentoxide, OC(CH<SUB>3</SUB>)(C<SUB>2</SUB>H<SUB>5</SUB>)<SUB>2</SUB>] has been employed in the atomic layer deposition (ALD) of HfO<SUB>2</SUB> thin films using water (H<SUB>2</SUB>O) as the oxygen source. The self-limiting ALD process via alternate surface reactions of Hf(mp)<SUB>4</SUB> and H<SUB>2</SUB>O is confirmed from thickness measurements of the HfO<SUB>2</SUB> films grown with varied Hf(mp)<SUB>4</SUB> supply time and number of Hf(mp)<SUB>4</SUB>/H<SUB>2</SUB>O ALD cycles. The ALD temperature window for this precursor is found to be between 250 and 350 °C. Under optimal reaction conditions, the growth rate of the HfO<SUB>2</SUB> films is ∼0.9 Å per cycle. Amorphous films can be obtained across the entire temperature range with atomically flat and uniform surfaces. X-ray photoelectron spectroscopy (XPS) and depth-profiling Auger electron spectroscopy (AES) indicate that the films are stoichiometric with negligible amounts (less than 2 %) of carbon impurities.</P> <B>Graphic Abstract</B> <P>The new precursor hafnium 3-methyl-3-pentoxide is shown to have excellent ALD behavior when used with water as the oxygen source. It is a liquid, volatile at moderately elevated temperatures, and shows a relatively low ALD temperature window, 250–350 °C, and minimal carbon incorporation in the HfO<SUB>2</SUB> films deposited. The growth rate of the HfO<SUB>2</SUB> films was found to be ca. 0.9 Å/cycle under optimal reaction conditions.</P>

Growth and Scintillation Characterizations of SrMoO4 Single Crystals

Hua Jiang,Gul Rooh,H.J. Kim,H. Park,J. H. So,김성환,S.K.Kim,Y.D.Kim,Wansong Zhang 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.10

Transparent crack-free samples of SrMoO₄ single crystals are grown by using the Czochralski method. X-ray diffraction results confirmed a single phase of the grown crystals. Photoluminescence and X-ray-induced emission spectra showed a broad emission band in the wavelength range from 380 to 750 nm. The decay time curve contained two decay-time components of 0.7 ± 0.5 ns (20%) and 943 ± 50 ns (80%) at room temperature. Temperature dependences of the scintillation light yield and the decay time of the SrMoO₄ crystal are also presented. Changes in the light yield and the decay time are observed at temperatures between 10 and 250 K. The light yield of SrMoO₄ at 70 K is found to be three times higher than that at 250 K. The decay time of SrMoO₄ get slower as the temperature decreases.

Mechanistic insights into the interaction between energetic oxygen ions and nanosized ZnFe₂O₄: XAS-XMCD investigations

Singh, Jitendra Pal,Kaur, Baljeet,Sharma, Aditya,Kim, So Hee,Gautam, Sanjeev,Srivastava, Ramesh Chandra,Goyal, Navdeep,Lim, Weol Cheol,Lin, H.-J.,Chen, J. M.,Asokan, K.,Kanjilal, D.,Won, Sung Ok,Lee, The Royal Society of Chemistry 2018 Physical Chemistry Chemical Physics Vol.20 No.17

<P>The interactions of energetic ions with multi-cation compounds and their consequences in terms of changes in the local electronic structure, which may facilitate intriguing hybridization between O 2p and metal d orbitals and magnetic ordering, are the subject of debate and require a deep understanding of energy transfer processes and magnetic exchange mechanisms. In this study, nanocrystals of ZnFe2O4 were exposed to O<SUP>7+</SUP> ions with an energy of 100 MeV to understand, qualitatively and quantitatively, the metal-ligand field interactions, cation migration and magnetic exchange interactions by employing X-ray absorption fine structure measurements and X-ray magnetic circular dichroism to get deeper mechanistic insights. Nanosized zinc ferrite nanoparticles (NPs) with a size of ∼16 nm synthesized in the cubic spinel phase exhibited deterioration of the crystalline phase when 100 MeV O<SUP>7+</SUP> ions passed through them. However, the size of these NPs remained almost the same. The behaviour of crystal deterioration is associated with the confinement of heat in this interaction. The energy confined inside the nanoparticles promotes cation redistribution as well as the modification of the local electronic structure. Prior to this interaction, almost 42% of Zn<SUP>2+</SUP> ions occupied AO4 tetrahedra; however, this value increased to 63% after the interaction. An inverse effect was observed for metal ion occupancies in BO6 octahedra. The L-edge spectra of Fe and Zn reveal that the spin and valence states of the metal ions were not affected by this interaction. This effect is also supported by K-edge measurements for Fe and Zn. The t2g/eg intensity ratio in the O K-edge spectra decreased after this interaction, which is associated with detachment of Zn<SUP>2+</SUP> ions from the lattice. The extent of hybridization, as estimated from the ratio of the post-edge to the pre-edge region of the O K-edge spectra, decreased after this interaction. The metal-oxygen and metal-metal bond lengths were modified as a result of this interaction, as determined from extended X-ray absorption fine structure measurements. These measurements further support the observation of cation migration from AO4 tetrahedra to AO6 octahedra and <I>vice versa</I>. The Fe L-edge magnetic circular dichroism spectra indicate that Fe<SUP>3+</SUP> ions occupying sites in AO4 tetrahedra and BO6 octahedra exhibited antiferromagnetic-like ordering prior to this interaction. The NPs that interacted with energetic O ions displayed a different kind of magnetic ordering.</P>