1H Nuclear Magnetic Resonance study of Ferroelectric (NH4)3H(SO4)2

S. H. Choi,K. S. Han,S. K. Kwon,S. K. Nam,H. H. Choi,Moohee Lee,Ae Ran Lim 한국자기공명학회 2007 Journal of the Korean Magnetic Resonance Society Vol.11 No.2

1H nuclear magnetic resonance (NMR) experiments have been performed at 30 - 300 K and 7 T to investigate dynamics of hydrogen bond network in the single crystal (NH4)3H(SO4)2. The two proton sites, ammonium proton and hydrogen-bond proton, are identified from the 1H NMR MAS spectrum at 340 K. As temperature decreases, the 1H NMR spectrum shifts to the higher frequency side with a larger linewidth. The spectrum at 65 K shows a distinctive change in line shape toward the ferroelectric transition at 63 K. The measured values of T1 for ammonium and hydrogen-bond protons are similar in the whole range of temperature. T1 of 1H NMR shows a gradual decrease down to 120 K and starts to steeply increase below 100 K. Then T1 shows abrupt decrease below 70 K with a sharp minimum at 63 K, where the ferroelectric transition occurs. This temperature dependence of spectrum and T1 clearly prove that the large change in the dynamics of hydrogen bond network is associated with the ferroelectric phase transition at 63 K.

Electrocatalytic activity of chemically deposited Cu_xS thin film for counter electrode in quantum dots-sensitized solar cells

Lim, I.,Lee, D.Y.,Patil, S.A.,Shrestha, N.K.,Kang, S.H.,Nah, Y.C.,Lee, W.,Han, S.H. Elsevier Science Publishers 2014 Materials chemistry and physics Vol.148 No.3

The compact (c-Cu<SUB>x</SUB>S) and the porous (p-Cu<SUB>x</SUB>S) with particle decorated films of coppers-ulfidearesynthesized using a chemical bath deposition technique, and the films are characterized using electrochemical techniques. In addition, the chemically deposited Cu<SUB>x</SUB>S films are investigated as a counter electrode in quantum dots-sensitized solar cells (QSSCs). The available redox active reaction sites of the p-Cu<SUB>x</SUB>S film are found to be 57.9% higher than those available in the c-Cu<SUB>x</SUB>S film. From the electrochemical impedance spectroscopy, the effective diffusion coefficients of the polysulfide electrolyte in the c-Cu<SUB>x</SUB>S and p-Cu<SUB>x</SUB>S films are estimated to be 3.67 x 10<SUP>-5</SUP> and 6.35 x 10<SUP>-5</SUP> cm<SUP>2</SUP> s<SUP>-1</SUP>, respectively. These results can be ascribed to the improvement in the available redox active reaction sites and the electrocatalytic activity of the Cu<SUB>x</SUB>S counter electrode. As compared to the c-Cu<SUB>x</SUB>S film, the p-Cu<SUB>x</SUB>S film as a counter electrode exhibits an enhanced photovoltaic performance of the QSSCs with the power conversion efficiency of 3.17%, short-circuit current of 11.89 mA c<SUP>-</SUP>m<SUP>2</SUP>, open-circuit voltage of 0.50 V, and fill factor of 53.29. The improved performance of the QSSCs is ascribed to the improvements on the available redox active reaction sites, electrocatalytic activity and the diffusion coefficients, which are directly related to the surface morphology of the sulfide films.

1H NMR Measurements of the Phase Transition of (NH₄)₃H(SO₄)₂ Single Crystals

S. H. Choi,Moohee Lee,Ae Ran Lim,K. S. Han,S. K. Kwon,S. K. Nam 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.2

$^1$H nuclear magnetic resonance (NMR) experiments have been performed in the temperature range of 30 -- 300 K at 7 T to investigate the phase-dependent nature of the dynamic network of hydrogen bonds in a ((NH₄)₃H(SO₄)₂ single crystal. The crystal has six phases, which are ferroelectric, antiferroelectric, incommensurate, antiferroelectric, ferroelastic, and superionic with the respective transition temperatures of 63, 133, 139, 256 and 413 K. The spin-lattice relaxation time, T₁, of ¹H NMR is similar for the ammonium protons and the hydrogen-bond protons over the entire range of experimental temperatures. The T₁, of ¹H NMR gradually decreases down to 120 K and starts to steeply increase below 100 K. Then, the T₁ shows an abrupt decrease below 68 K with a sharp minimum at 63 K, where the ferroelectric transition occurs. The ¹H NMR spectrum shifts to the high-frequency side at temperatures below 63 K due to the ferroelectric phase transition. This behavior of the T₁ and the spectrum confirms a dramatic change in the dynamics of hydrogen bonds associated with the ferroelectric phase transition at 63 K. $^1$H nuclear magnetic resonance (NMR) experiments have been performed in the temperature range of 30 -- 300 K at 7 T to investigate the phase-dependent nature of the dynamic network of hydrogen bonds in a ((NH₄)₃H(SO₄)₂ single crystal. The crystal has six phases, which are ferroelectric, antiferroelectric, incommensurate, antiferroelectric, ferroelastic, and superionic with the respective transition temperatures of 63, 133, 139, 256 and 413 K. The spin-lattice relaxation time, T₁, of ¹H NMR is similar for the ammonium protons and the hydrogen-bond protons over the entire range of experimental temperatures. The T₁, of ¹H NMR gradually decreases down to 120 K and starts to steeply increase below 100 K. Then, the T₁ shows an abrupt decrease below 68 K with a sharp minimum at 63 K, where the ferroelectric transition occurs. The ¹H NMR spectrum shifts to the high-frequency side at temperatures below 63 K due to the ferroelectric phase transition. This behavior of the T₁ and the spectrum confirms a dramatic change in the dynamics of hydrogen bonds associated with the ferroelectric phase transition at 63 K.

DMNQ S-64 Induces Apoptosis via Caspase Activation and Cyclooxygenase-2 Inhibition in Human Nonsmall Lung Cancer Cells

LIM, E.-S.,RHEE, Y.-H.,PARK, M.-K.,SHIM, B.-S.,AHN, K.-S.,KANG, H.,YOO, H.-S.,KIM, S.-H. Wiley (Blackwell Publishing) 2007 Annals of the New York Academy of Sciences Vol.1095 No.1

<P>Shikonin has been reported to induce apoptosis and inhibit angiogenesis in vivo and in vitro. 6-(1-propoxyiminoalkyl)-5,8-dimethoxyoxy 1,4-naphtoquinone S-64 (DMNQ S-64) was synthesized as a shikonin derivative. In this article, the underlying apoptotic mechanism of DMNQ S-64 was examined. DMNQ S-64 exerted cytotoxicity against A549 lung carcinoma cells with IC(50) of 27.3 microM. Apoptotic bodies were observed in DMNQ S-64-treated A549 cells by 4'-6-diamidino-2-phenylindole (DAPI) staining assay. DMNQ S-64 also increased sub-G1 DNA portion in a concentration-dependent manner by flow cytometric analysis. Western blotting has revealed that DMNQ S-64 effectively activates the expression of caspase 8, 9, and 3, cleaves poly (ADP-ribose) polymerase, and increases the ratio of Bax/Bcl-2. Furthermore, cytochrome c was released in a concentration-dependent manner by DMNQ S-64. Similarly, DMNQ S-64 significantly increased caspase 3 activity by enzyme-linked immunosorbent assay (ELISA). It also significantly inhibited the level of prostaglandin E2 (PGE(2)) by ELISA and downregulated the expression of cyclooxygenase-2 (COX-2) in a concentration-dependent manner. Taken together, DMNQ S-64 may exhibit cytotoxicity against A549 cells via caspase activation and COX-2 inhibition.</P>

Phase II study of S-1 combined with oxaliplatin as therapy for patients with metastatic biliary tract cancer: influence of the <i>CYP2A6</i> polymorphism on pharmacokinetics and clinical activity

Kim, K-p,Jang, G,Hong, Y S,Lim, H-S,Bae, K-s,Kim, H-S,Lee, S S,Shin, J-G,Lee, J-L,Ryu, M-H,Chang, H-M,Kang, Y-K,Kim, T W Nature Publishing Group 2011 The British journal of cancer Vol.104 No.4

<P><B>Background:</B></P><P>Advanced biliary cancer is often treated with fluoropyrimidine-based chemotherapy. In this study, we evaluated the efficacy and tolerability of a combination of S-1, an oral fluoropyrimidine prodrug, and oxaliplatin in patients with metastatic biliary cancer.</P><P><B>Methods:</B></P><P>Patients with histologically confirmed metastatic biliary cancer and no history of radiotherapy or chemotherapy were enrolled. Oxaliplatin was administered intravenously (130 mg m<SUP>−2</SUP>), followed by 14-day administration of oral S-1 (40 mg m<SUP>−2</SUP> twice daily) with a subsequent 7-day rest period every 21 days. Pharmacokinetic analysis of S-1 was performed at cycle 1. Patients were genotyped for <I>CYP2A6</I> polymorphisms (<SUP>*</SUP>1, <SUP>*</SUP>4, <SUP>*</SUP>7, <SUP>*</SUP>9 or <SUP>*</SUP>10), and pharmacokinetic and clinical parameters compared according to the <I>CYP2A6</I> genotype.</P><P><B>Results:</B></P><P>In total, 49 patients were evaluated, who received a median of four cycles. The overall response rate was 24.5%. Median progression-free and overall survival was 3.7 and 8.7 months, respectively. The most common haematological grade 3 out of 4 toxicity was neutropenia (14%), while non-hematological grade 3 out of 4 toxicities included anorexia (14%), nausea (12%), asthenia (10%), vomiting (10%), and diarrhoea (4%). Biotransformation of S-1 (AUC<SUB>0−24 h</SUB> of 5-fluorouracil/AUC<SUB>0−24 h</SUB> of tegafur) was 1.85-fold higher for the <I>*1/*1</I> group than for the other groups (90% confidence interval 1.37–2.49). Diarrhoea (<I>P</I>=0.0740), neutropenia (<I>P</I>=0.396), and clinical efficacy (response rate, <I>P</I>=0.583; PFS, <I>P</I>=0.916) were not significantly associated with <I>CYP2A6</I> genotype, despite differences in 5-FU exposure.</P><P><B>Conclusion:</B></P><P>The combination of S-1 and oxaliplatin appears to be active and well tolerated in patients with metastatic biliary cancer, and thus is feasible as a therapeutic modality. <I>CYP2A6</I> genotypes are associated with differences in the biotransformation of S-1. However, the impact of the <I>CYP2A6</I> polymorphism on variations in clinical efficacy or toxicity requires further evaluation.</P>

[ $^1H$ ] Nuclear Magnetic Resonance Study of Ferroelectric $(NH_4)_3H(SO_4)_2$

Choi, S.H.,Han, K.S.,Kwon, S.K.,Nam, S.K.,Choi, H.H.,Lee, Moo-Hee,Lim, Ae-Ran Korean Magnetic Resonance Society 2007 Journal of the Korean Magnetic Resonance Society Vol.11 No.2

[ $^1H$ ] nuclear magnetic resonance (NMR) experiments have been performed at 30 - 300 K and 7 T to investigate dynamics of hydrogen bond network in the single crystal $(NH_4)_3H(SO_4)_2$. The two proton sites, ammonium proton and hydrogen-bond proton, are identified from the $^1H$ NMR MAS spectrum at 340 K. As temperature decreases, the $^1H$ NMR spectrum shifts to the higher frequency side with a larger linewidth. The spectrum at 65 K shows a distinctive change in line shape toward the ferroelectric transition at 63 K. The measured values of $T_1$ for ammonium and hydrogen-bond protons are similar in the whole range of temperature. $T_1$ of $^1H$ NMR shows a gradual decrease down to 120 K and starts to steeply increase below 100 K. Then $T_1$ shows abrupt decrease below 70 K with a sharp minimum at 63 K, where the ferroelectric transition occurs. This temperature dependence of spectrum and $T_1$ clearly prove that the large change in the dynamics of hydrogen bond network is associated with the ferroelectric phase transition at 63 K.

Live attenuated nephropathogenic infectious bronchitis virus vaccine provides broad cross protection against new variant strains.

Lim, T-H,Kim, M-S,Jang, J-H,Lee, D-H,Park, J-K,Youn, H-N,Lee, J-B,Park, S-Y,Choi, I-S,Song, C-S Poultry Science Association, etc 2012 Poultry science Vol.91 No.1

<P>Infectious bronchitis virus (IBV) infections cause great economic losses to the poultry industry worldwide, and the emergence of new variant strains complicates disease control. The present study investigated the genetic and protectotypic features of newly emerged Korean IBV strains. A phylogenetic analysis showed that several recent isolates formed 2 different clusters (new cluster 1 and 2), which were distinct from other preexisting clusters. New cluster 1 IBV strains represented recombinants between Korean nephropathogenic strain KM91 and the QXIBV strain. New cluster 2 IBV strains showed low amino acid homology (<58.7%) compared with previous isolates. We evaluated the protective efficacy of commercial IBV vaccines (H120 and K2 strain) against these new isolates. In cross-protection studies, the H120 strain did not provide sufficient protection against these variants. However, highly attenuated nephropathogenic IBV vaccine, K2 strain, provided significantly higher levels of protection against variants compared with chickens vaccinated with H120 (P < 0.05 or better). These results indicate that the K2 vaccine could be helpful for the reduction of economic losses caused by newly evolving IBV recombinants (new cluster 1) and variants (new cluster 2).</P>

Effect of S-adenosylmethionine on neointimal formation after balloon injury in obese diabetic rats

Lim, S.,Moon, M. K.,Shin, H.,Kim, T. H.,Cho, B. J.,Kim, M.,Park, H. S.,Choi, S. H.,Ko, S. H.,Chung, M. H. Oxford University Press 2011 Cardiovascular research Vol.90 No.2

RF Interference Analysis for KOMPSAT-II Spacecraft

Lim, S.B.,Kim, D.Y.,Chang, Y.K. 통신위성우주산업연구회 2001 Joint Conference on Satellite Communications Vol.2001 No.-

In general, LEO satellite uses S-band communication link for the whole satellite management, whereas the satellite payload frequently implements X-band and/or Ku-band transmitter for payload data transmission. The transmission system should have out-band rejection filter (protection circuit) to prevent any interference with the satellite receiver, so that the receiver can be normally operated. It is usually implemented in the transmitter itself but the vendor of a transmitter could not take it into account whole out of band frequency because a variety of individual satellites utilize different RF communication systems. The KOMPSAT-II, which is an earth observation satellite, is being developed by Korea Aerospace Research Institute and Korean industries. It has S-band communication system for the bus and X-band transmission system for payload data. In addition, L-band GPS Receiver is being incorporated to achieve the KOMPSAT-II mission goal. Unfortunately, the KOMPSAT-2 payload system does not have external out-band rejection~ filter nor transmitter for S-band and L-band protection. The transmitter only has band rejection filter for TDRSS. In addition, it has high gain directional antenna whose directional beam has to pass over the S-band antenna. In this paper, the analysis method is described to calculate the interference effects of the S-band spurious noise power on X-band transmitting system to S-band receiver. The S-band antenna is positioned very closely to the X-band Antenna by I .2m. We will also introduce general simple RF interference analysis method applicable to a traditional system, including advantage and disadvantages. The X-band transmitting system is often required to add the specified filter to suppress the S-band spurious signal for the safety of the receiver performance. The analysis result shows that the performance of S-band receiver is satisfied with no implementation of the specified filter.

Analysis of the relationship between the kinetic energy and intensity of rainfall in Daejeon, Korea

Lim, Y.S.,Kim, J.K.,Kim, J.W.,Park, B.I.,Kim, M.S. Pergamon Press 2015 QUATERNARY INTERNATIONAL Vol.384 No.-

The kinetic energy and momentum of rainfall are widely used as erosivity indicators for estimating soil detachment (erosion) induced by the impact of raindrops. Because direct measurements of the force or kinetic energy of rainfall on ground surfaces are not widely available, many empirical relationships have been derived to link the kinetic energy and intensity (I) of rainfall, the factor that has the most control over soil erosion and is readily accessible. This study considered three rainfall erosivity indices: kinetic energy expenditure (KE<SUB>time</SUB>, J m<SUP>-2</SUP> h<SUP>-1</SUP>), kinetic energy content (KE<SUB>mm</SUB>, J m<SUP>-2</SUP> mm<SUP>-1</SUP>), and momentum (M, kg m s<SUP>-1</SUP> m<SUP>-2</SUP> s<SUP>-1</SUP> or N m<SUP>-2</SUP>). The relationships between these rainfall erosivity indices (KE<SUB>time</SUB>, KE<SUB>mm</SUB>, and M) and rainfall intensity were established by fitting to an existing functional model based on measurements of the number of drops by size and terminal velocity made from January 2010 to July 2011 using a laser optical disdrometer in Daejeon City, Korea. The best fit for the relationship between the three kinetic energy indices and rainfall intensity was obtained with a power law (KE<SUB>time</SUB>-I, and M-I) and an exponential model (KE<SUB>mm</SUB>-I). Validation results for two different events indicated good performance for the KE<SUB>time</SUB>-I and M-I equations, with a similar distribution of observed data and power-law curve fitting. However, the rainfall momentum index produced much lower uncertainty as determined from the measured terminal velocity when the equipment was exposed to in situ changeable conditions. Therefore, we suggest that the power-law relationship between momentum and rainfall intensity is the most suitable equation for the prediction of rainfall erosivity.