Cloning and characterization of a thermostable H₂O-forming NADH oxidase from Lactobacillus rhamnosus

Zhang, Y.W.,Tiwari, M.K.,Gao, H.,Dhiman, S.S.,Jeya, M.,Lee, J.K. IPC Science and Technology Press ; Elsevier Scienc 2012 Enzyme and microbial technology Vol.50 No.4

NADH oxidase (Nox) catalyzes the conversion of NADH to NAD<SUP>+</SUP>. A previously uncharacterized Nox gene (LrNox) was cloned from Lactobacillus rhamnosus and overexpressed in Escherichia coli BL21(DE3). Sequence analysis revealed an open reading frame of 1359bp, capable of encoding a polypeptide of 453 amino acid residues. The molecular mass of the purified LrNox enzyme was estimated to be ∼50kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and 100kDa by gel filtration chromatography, suggesting that the enzyme is a homodimer. The enzyme had optimal activity at pH 5.6 and temperature 65<SUP>o</SUP>C, and k<SUB>cat</SUB>/K<SUB>m</SUB> of 3.77x10<SUP>7</SUP>s<SUP>-1</SUP>M<SUP>-1</SUP>, the highest ever reported. Heat inactivation studies revealed that LrNox had high thermostability, with a half-life of 120min at 80<SUP>o</SUP>C. Molecular dynamics simulation studies shed light on the factors contributing to the high activity of LrNox. Although the properties of Nox from several microorganisms have been reported, this is the first report on the characterization of a recombinant H<SUB>2</SUB>O-forming Nox with high activity and thermostability. The characteristics of the LrNox enzyme could prove to be of interest in industrial applications such as NAD<SUP>+</SUP> regeneration.

Laser-induced Plasma Atomic Emission Spectrometry for Application to Element-based Sorting of Steel Scraps

( L Zhang ),( K Wagatsuma ) 경남대학교 신소재연구소 2013 신소재연구 Vol.25 No.-

Laser-induced plasma - atomic emission spectrometry (LIPS) is a rapid analytical method which can determine the elemental composition in a remote-sensing configuration without any need for sample pretreatment; therefore, it is expected to be employed for the practical analysis of industrial process control. More recently, recycling of metallic materials can greatly contribute to the saving of resources as well as energy, because the amounts of metal products are huge and they contain various rare metals such as nickel and chromium. In the recycling process, an on-site analytical method would give useful information for separating the steel products by employing the quantitative analytical result. In laser-induced plasma (LIP), a gas body in the plasma state, in which specimen sampling, atomization, and ionization occur, is produced near the sample surface through convergent laser beam irradiation with a high energy density. This sampling process is called laser ablation, where sample atoms are evaporated from the surface and are then introduced into the plasma. The pulsated LIP has both spatial and temporal variations, depending on various experimental parameters, such as the kind and pressure of the plasma gas employed, which is generally known as an expansion process of the plasma [1]. It means that the emission zone changes with the progress of the plasma to produce a plume-like shape, which is strongly dependent on the nature of the plasma gas. Therefore, time-resolved measurements of the emission spectra give useful information on optimization of the measuring conditions for the emission analysis, such as the delay time as well as the gate width on the data acquisition; however, such measurements cannot provide the overall variation of the plasma expansion. For this purpose, a two-dimensional image of a spectral line emitted from LIP should be observed, which is expected to give information on the fundamental processes occurring in the LIP. In the present work [2], we focused on the determination of copper in steel samples, because it is a typical tramp element containing in steel scraps. For this purpose, the intensity variations of iron emission lines as well as copper atomic lines were investigated in various experimental conditions in LIPS, in order to obtain the optimum operating parameters for the laser as well as the detection system, when argon was selected as the plasma gas. Several pairs of iron and copper emission lines were tested to improve the performance of the calibration curve. [1] Y. Ushirozawa, K. Wagatsuma: Anal. Sci., 2006, 22, 1011. [2] L. Zhang, K. Wagatsuma: ISIJ International, 2013, 54(12), in press.

Long-lived K isomer and enhanced γ vibration in the neutron-rich nucleus ¹⁷²Dy: Collectivity beyond double midshell

Watanabe, H.,Zhang, G.X.,Yoshida, K.,Walker, P.M.,Liu, J.J.,Wu, J.,Regan, P.H.,Soderstrom, P.A.,Kanaoka, H.,Korkulu, Z.,Lee, P.S.,Nishimura, S.,Yagi, A.,Ahn, D.S.,Alharbi, T.,Baba, H.,Browne, F.,Bruce North-Holland Pub. Co 2016 Physics letters. Section B Vol.760 No.-

The level structure of <SUP>172</SUP>Dy has been investigated for the first time by means of decay spectroscopy following in-flight fission of a <SUP>238</SUP>U beam. A long-lived isomeric state with T<SUB>½</SUB>=0.71(5) s and K<SUP>π</SUP>=8<SUP>-</SUP> has been identified at 1278 keV, which decays to the ground-state and γ-vibrational bands through hindered electromagnetic transitions, as well as to the daughter nucleus <SUP>172</SUP>Ho via allowed β decays. The robust nature of the K<SUP>π</SUP>=8<SUP>-</SUP> isomer and the ground-state rotational band reveals an axially-symmetric structure for this nucleus. Meanwhile, the γ-vibrational levels have been identified at unusually low excitation energy compared to the neighboring well-deformed nuclei, indicating the significance of the microscopic effect on the non-axial collectivity in this doubly mid-shell region. The underlying mechanism of enhanced γ vibration is discussed in comparison with the deformed Quasiparticle Random-Phase Approximation based on a Skyrme energy-density functional.

Emodin accentuates atrial natriuretic peptide secretion in cardiac atria

Zhou, G.H.,Zhang, F.,Wang, X.N.,Kwon, O.J.,Kang, D.G.,Lee, H.S.,Jin, S.N.,Cho, K.W.,Wen, J.F. North-Holland ; Elsevier Science Ltd 2014 european journal of pharmacology Vol.735 No.-

Emodin, an active anthraquinone constituent isolated from the rhubarb, a traditional Chinese herbal medicine which is widely used in clinical treatment, has cardiovascular protective properties. However, it remains unclear whether the cardiovascular protective actions of emodin are related to an activation of cardiac natriuretic hormone secretion. The purpose of the present study was to explore the effect of emodin on the secretion of ANP, a member of the family of cardiac natriuretic hormones, and its mechanisms involved. Experiments were performed in isolated perfused beating rabbit atria allowing measurement of ANP secretion, atrial pulse pressure, and stroke volume. Emodin increased ANP secretion concomitantly with a decrease in atrial pulse pressure and stroke volume in a concentration-dependent manner. These effects were reversible. Inhibition of K<SUP>+</SUP> channels with tetraethylammonium and glibenclamide attenuated the emodin-induced changes in ANP secretion and atrial dynamics. Furthermore, the emodin-induced changes in ANP secretion and atrial dynamics were attenuated by inhibition of L-type Ca<SUP>2+</SUP> channels with nifedipine. Atropine, methoctramine, tertiapin-Q, and pertussis toxin had no significant effect on the emodin-induced changes in ANP secretion and mechanical dynamics. The present study demonstrates that emodin increases ANP secretion via inhibition of L-type Ca<SUP>2+</SUP> channels through an activation of K<SUP>+</SUP><SUB>ATP</SUB> channel in isolated beating rabbit atria. The results also provide a rationale for the use of emodin in the treatment of impairment of the regulation of the cardiovascular homeostasis.

Inhibition of TREK-2 K+ channels by PI(4,5)P2: an intrinsic mode of regulation by intracellular ATP via phosphatidylinositol kinase

Woo, J.,Shin, D. H.,Kim, H. J.,Yoo, H. Y.,Zhang, Y. H.,Nam, J. H.,Kim, W. K.,Kim, S. J. Springer Science + Business Media 2016 Pfl ugers Arch Vol.468 No.8

<P>TWIK-related two-pore domain K+ channels 1 and 2 (TREKs) are activated under various physicochemical conditions. However, the directions in which they are regulated by PI(4,5)P-2 and intracellular ATP are not clearly presented yet. In this study, we investigated the effects of ATP and PI(4,5)P-2 on overexpressed TREKs (HEK293T and COS-7) and endogenously expressed TREK-2 (mouse astrocytes and WEHI-231 B cells). In all of these cells, both TREK-1 and TREK-2 currents were spontaneously increased by dialysis with ATP-free pipette solution for whole-cell recording (I-TREK-1,I-w-c and (ITREK-2w-c)) or by membrane excision for inside-out patch clamping without ATP (I-TREK-1,I-i-o and I-TREK-2,I-i-o). Steady state I-TREK-2,I-i-o was reversibly decreased by 3 mM ATP applied to the cytoplasmic side, and this reduction was prevented by wortmannin, a PI-kinase inhibitor. An exogenous application of PI(4,5)P-2 inhibited the spontaneously increased I-TREKs,I-i-o, suggesting that intrinsic PI(4,5)P-2 maintained by intracellular ATP and PI kinase may set the basal activity of TREKs in the intact cells. The inhibition of intrinsic TREK-2 by ATP was more prominent in WEHI-231 cells than astrocytes. Interestingly, unspecific screening of negative charges by poly-L-lysine also inhibited I-TREK-2,I-i-o. Application of PI(4,5)P-2 after the poly-L-lysine treatment showed dose-dependent dual effects, initial activation and subsequent inhibition of I-TREK-2,I-i-o at low and high concentrations, respectively. In HEK293T cells coexpressing TREK-2 and a voltage-sensitive PI(4,5)P-2 phosphatase, sustained depolarization increased I-TREK-2,I-w-c initially (< 5 s) but then decreased the current below the control level. In HEK293T cells coexpressing TREK-2 and type 3 muscarinic receptor, application of carbachol induced transient activation and sustained suppression of I-TREK-2,I-w-c and cell-attached ITREK-2. The inhibition of TREK-2 by unspecific electrostatic quenching, extensive dephosphorylation, or sustained hydrolysis of PI(4,5)P-2 suggests the existence of dual regulatory modes that depend on PI(4,5)P-2 concentration.</P>

Results of availability imposed configuration details developed for K-DEMO

Brown, T.,Titus, P.,Brooks, A.,Zhang, H.,Neilson, H.,Im, K.,Kim, K. North-Holland ; Elsevier Science Ltd 2016 Fusion engineering and design Vol.109 No.2

The Korean fusion demonstration reactor (K-DEMO) has completed a two year study looking at key Tokamak components and configuration options in preparation of a conceptual design phase. A key part of a device configuration centers on defining an arrangement that enhances the ability to reach high availability values by defining design solutions that foster simplified maintenance operations. To maximize the size and minimize the number of in-vessel components enlarged TF coils were defined that incorporate a pair of windings within each coil to mitigate pressure drop issues and to reduce the cost of the coils. A semi-permanent shield structure was defined to develop labyrinth interfaces between double-null plasma contoured shield modules, provide an entity to align blanket components and provide support against disruption loads-with a load path that equilibrates blanket, TF and PF loads through a base structure. Blanket piping services and auxiliary systems that interface with in-vessel components have played a major role in defining the overall device arrangement-concept details will be presented along with general arrangement features and preliminary results obtained from disruption analysis.

Fabrication of Nitrogen Doped p-ZnO and ZnO Light-Emitting Diodes on Sapphire

Y. M. Lu,Z. P. Wei,D. Z. Shen,Z. Z. Zhang,B. Yao,B. H. Li,J. Y. Zhang,D. X. Zhao,X. W. Fan,Z. K. Tang 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5

Nitrogen-doped p-type ZnO thin films were grown on c-plane sapphire (Al2O3) substrates by plasma-assistant molecular beam epitaxy, where O2 and N2 were introduced via a RF plasma source simultaneously. In situ optical emission spectra of the plasma were employed to monitor the chemical species in the active gas sources, one of the most important growth parameters. By adjusting the growth parameters, we confirm the optimal condition for p-type doping growth. The reproducible p-type ZnO thin films have the hole concentration (NA −ND) up to 1.0 × 1018 cm−3 and the resistivity of 6 cm. A ZnO LED was fabricated by depositing undoped n-type ZnO on the p-type layer. Electroluminescence spectra centered about 430 nm were obtained even at 350 K.

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.

Separation dynamics of hydrogen isotope gas in mesoporous and microporous adsorbent beds at 77 K: SBA-15 and zeolites 5A, Y, 10X

Chu, X.Z.,Cheng, Z.P.,Xiang, X.X.,Xu, J.M.,Zhao, Y.J.,Zhang, W.G.,Lv, J.S.,Zhou, Y.P.,Zhou, L.,Moon, D.K.,Lee, C.H. Pergamon Press ; Elsevier Science Ltd 2014 International journal of hydrogen energy Vol.39 No.9

The separation of a hydrogen isotope mixture on porous materials was studied using equilibrium and breakthrough experiments. The adsorption equilibria of H<SUB>2</SUB> and D<SUB>2</SUB> on SBA-15 with mesopores and molecular sieves 5A, Y, and 10X with micropores were measured at 77 K using the volumetric method. The breakthrough experiments of a H<SUB>2</SUB> and D<SUB>2</SUB> mixture in each adsorbent bed were carried out at various conditions of flow rate and pressure. The equilibrium ratio of D<SUB>2</SUB> to H<SUB>2</SUB> on mesoporous molecular sieves was larger than the ratio on microporous molecular sieves (SBA-15 > 10X > Y > 5A), but the difference among the adsorbents decreased with increases in pressure. On the other hand, the order of breakthrough separation factor showed the opposite result (SBA-15 < 10X < Y < 5A). The breakthrough separation factors for zeolite 10X was approximately equal to the equilibrium ratio of D<SUB>2</SUB> to H<SUB>2</SUB> at the corresponding partial pressures, whereas zeolites 5A and Y showed higher breakthrough separation factors than their equilibrium ratios. In SBA-15, the separation factors from breakthrough results were even smaller than the corresponding equilibrium ratio. In the microporous adsorbent with a limited pore size (zeolite 5A in the study), the diffusion mechanism contributed to the separation of hydrogen isotope gases as one of key factors.

Measurement ofD0−D¯0mixing and search for indirectCPviolation usingD0→KS0π+π−decays

Peng, T.,Zhang, Z. P.,Abdesselam, A.,Adachi, I.,Aihara, H.,Arinstein, K.,Asner, D. M.,Aulchenko, V.,Aushev, T.,Ayad, R.,Bakich, A. M.,Bala, A.,Bhardwaj, V.,Bhuyan, B.,Bobrov, A.,Bondar, A.,Bonvicini, American Physical Society 2014 PHYSICAL REVIEW D - Vol.89 No.9

We report a measurement of D-0-(D) over bar(0) mixing parameters and a search for indirect CP violation through a time-dependent amplitude analysis of D-0 -> K-S(0)pi(+)pi(-) decays. The results are based on 921 fb(-1) of data accumulated with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. Assuming CP conservation, we measure the mixing parameters x = (0.56 +/- 0.19(-0.09-0.09)(+0.03+0.06))% and y = (0.30 +/- 0.15(-0.05-0.06)(+0.04+0.03))%, where the errors are statistical, experimental systematic, and systematic due to the amplitude model, respectively. With CP violation allowed, the parameters vertical bar q/p vertical bar = 0.90(-0.15-0.04-0.05)(+0.16+0.05+0.06) and arg(q/p) = (- 6 +/- 11 +/- 3(-4)(+3))degrees are found to be consistent with conservation of CP symmetry in mixing and in the interference between mixing and decay, respectively.