WorldWideScience

Sample records for axial ligand effects

  1. Axial ligand effects on the diradical characters and second hyperpolarizabilities of open-shell singlet transition-metal dinuclear complexes

    Science.gov (United States)

    Yamada, Taishi; Takamuku, Shota; Matsui, Hiroshi; Champagne, Benoît; Nakano, Masayoshi

    2014-07-01

    We investigate the axial ligand effects on the diradical character (y) dependences of the second hyperpolarizabilities (γ) of transition-metal dinuclear complexes, Mo(I)2(CO)2, with different bond lengths (R) using the spin-unrestricted coupled-cluster method. Mo(I)2(CO)2 exhibits intrinsic y-γ correlation and dominant dσ-electron contribution to the maximum γ (γmax), which are also observed in the bare dinuclear analogs. The axial-ligand coordination to Mo(I)2 is found to cause the increase of the diradical character of the dσ orbital, the emergence of large negative γ for small R, and an enhancement of |γmax| by a factor of ∼30 as compared to the bare analogs.

  2. Water-Soluble Iron(IV)-Oxo Complexes Supported by Pentapyridine Ligands: Axial Ligand Effects on Hydrogen Atom and Oxygen Atom Transfer Reactivity.

    Science.gov (United States)

    Chantarojsiri, Teera; Sun, Yujie; Long, Jeffrey R; Chang, Christopher J

    2015-06-15

    We report the photochemical generation and study of a family of water-soluble iron(IV)-oxo complexes supported by pentapyridine PY5Me2-X ligands (PY5Me2 = 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine; X = CF3, H, Me, or NMe2), in which the oxidative reactivity of these ferryl species correlates with the electronic properties of the axial pyridine ligand. Synthesis of a systematic series of [Fe(II)(L)(PY5Me2-X)](2+) complexes, where L = CH3CN or H2O, and characterizations by several methods, including X-ray crystallography, cyclic voltammetry, and Mössbauer spectroscopy, show that increasing the electron-donating ability of the axial pyridine ligand tracks with less positive Fe(III)/Fe(II) reduction potentials and quadrupole splitting parameters. The Fe(II) precursors are readily oxidized to their Fe(IV)-oxo counterparts using either chemical outer-sphere oxidants such as CAN (ceric ammonium nitrate) or flash-quench photochemical oxidation with [Ru(bpy)3](2+) as a photosensitizer and K2S2O8 as a quencher. The Fe(IV)-oxo complexes are capable of oxidizing the C-H bonds of alkane (4-ethylbenzenesulfonate) and alcohol (benzyl alcohol) substrates via hydrogen atom transfer (HAT) and an olefin (4-styrenesulfonate) substrate by oxygen atom transfer (OAT). The [Fe(IV)(O)(PY5Me2-X)](2+) derivatives with electron-poor axial ligands show faster rates of HAT and OAT compared to their counterparts supported by electron-rich axial donors, but the magnitudes of these differences are relatively modest. PMID:26039655

  3. Spectroscopic properties and electronic structure of five- and six-coordinate iron(II) porphyrin NO complexes: Effect of the axial N-donor ligand.

    Science.gov (United States)

    Praneeth, V K K; Näther, Christian; Peters, Gerhard; Lehnert, Nicolai

    2006-04-01

    In this paper, the differences in the spectroscopic properties and electronic structures of five- and six-coordinate iron(II) porphyrin NO complexes are explored using [Fe(TPP)(NO)] (1; TPP = tetraphenylporphyrin) and [Fe(TPP)(MI)(NO)] (2; MI = 1-methylimidazole) type systems. Binding of N-donor ligands in axial position trans to NO to five-coordinate complexes of type 1 is investigated using UV-vis absorption and 1H NMR spectroscopies. This way, the corresponding binding constants Keq are determined and the 1H NMR spectra of 1 and 2 are assigned for the first time. In addition, 1H NMR allows for the determination of the degree of denitrosylation in solutions of 1 with excess base. The influence of the axial ligand on the properties of the coordinated NO is then investigated. Vibrational spectra (IR and Raman) of 1 and 2 are presented and assigned using isotope substitution and normal-coordinate analysis. Obtained force constants are 12.53 (N-O) and 2.98 mdyn/A (Fe-NO) for 1 compared to 11.55 (N-O) and 2.55 mdyn/A (Fe-NO) for 2. Together with the NMR results, this provides experimental evidence that binding of the trans ligand weakens the Fe-NO bond. The principal bonding schemes of 1 and 2 are very similar. In both cases, the Fe-N-O subunit is strongly bent. Donation from the singly occupied pi* orbital of NO into d(z2) of iron(II) leads to the formation of an Fe-NO sigma bond. In addition, a medium-strong pi back-bond is present in these complexes. The most important difference in the electronic structures of 1 and 2 occurs for the Fe-NO sigma bond, which is distinctively stronger for 1 in agreement with the experimental force constants. The increased sigma donation from NO in 1 also leads to a significant transfer of spin density from NO to iron, as has been shown by magnetic circular dichroism (MCD) spectroscopy in a preceding Communication (Praneeth, V. K. K.; Neese, F.; Lehnert, N. Inorg. Chem. 2005, 44, 2570-2572). This is confirmed by the 1H NMR results

  4. Study of axial magnetic effect

    International Nuclear Information System (INIS)

    The Axial Magnetic Effect manifests itself as an equilibrium energy flow of massless fermions induced by the axial (chiral) magnetic field. Here we study the Axial Magnetic Effect in the quenched SU(2) lattice gauge theory with massless overlap fermions at finite temperature. We numerically observe that in the low-temperature hadron phase the effect is absent due to the quark confinement. In the high-temperature deconfinement phase the energy flow is an increasing function of the temperature which reaches the predicted asymptotic T2 behavior at high temperatures. We find, however, that energy flow is about one order of magnitude lower compared to a theoretical prediction

  5. THE STUDY OF ORIENTATION OF AXIAL AMINO-LIGANDS IN SOME Co(III DIOXIMATES

    Directory of Open Access Journals (Sweden)

    Andrei Rija

    2013-12-01

    Full Text Available As a result of the comparative study of axial ligand orientation towards the equatorial plane in α - dioximates Co (III obtained by us and those described in the specialized literature (found in Cambridge Crystallographic Data Centre showed that the external anions and solvent molecules contribute to the orientation of axial ligands as selenourea and thiourea. For aniline and sulphanilamide ligands, is more convenient the parallel orientation to form π-π interactions between the aromatic rings of ligands and the metallocycle of equatorial plane.

  6. Building-up novel coordination polymer with Zn(II) porphyrin dimer: Synthesis, structures, surface morphology and effect of axial ligands

    Indian Academy of Sciences (India)

    Sk Asif Ikbal; Sanfaori Brahma; Avinash Dhamija; Sankar Prasad Rath

    2014-09-01

    Highly flexible Zn(II)1,2-bis(meso-octaethylporphyrin)ethane (1) has been used as host in which two porphyrin rings are found to be face-to-face in non-coordinating solvents. Upon addition of one relatively smaller 4,4′-dipyridine (L1) and one extended N,N′-bispyridine-4-yl-methylene ethylenediamine (L2) guest ligands, the syn conformation of 1 is switched to the anti complexes 1·(L1)2 and 1·L2, respectively. Single crystal X-ray structures of all the complexes are reported in which a stable one-dimensional coordination polymer is produced only in 1·L2 that is, to the best of our knowledge, the first structural report of 1D-coordination polymer with porphyrin dimer. Solution structures of the complexes along with binding studies in solution between 1 and L have also been investigated. The morphology of the polymeric complex 1·L2 on silicon wafer surface was examined by Atomic Force Microscopy (AFM) in which the crystalline islands of well defined facets of size ranging from 200-550 nm perimeter and a height of 20-40 nm have been observed.

  7. Stable ruthenium nitrosyl porphyrins with axial O-bonded ligands; preparation and redox behavior.

    Science.gov (United States)

    Awasabisah, Dennis; Xu, Nan; Sharmah Gautam, Krishna P; Powell, Douglas R; Shaw, Michael J; Richter-Addo, George B

    2013-06-28

    The six-coordinate compounds, (T(p-OMe)PP)Ru(NO)(OC6HF4) and (T(p-OMe)PP)Ru(NO)(OC(=O)CF3) have been prepared and characterized by IR and NMR spectroscopy, electrochemistry and IR spectroelectrochemistry, and by X-ray crystallography. These compounds undergo macrocycle-centered oxidations, and loss of axial ligands upon reduction. PMID:23440058

  8. Histidine is the axial ligand to cytochrome alpha 3 in cytochrome c oxidase

    OpenAIRE

    Stevens, Tom H.; Chan, Sunney I.

    1981-01-01

    The nitric oxide-bound complexes of reduced yeast cytochrome c oxidase incorporated with [1,3-15N2]histidine have been investigated by EPR spectroscopy. The results of this study have allowed the unambiguous identification of histidine as the endogenous axial ligand to cytochrome alpha 3.

  9. Effective quantum number for axially symmetric problems

    OpenAIRE

    Trunov, N. N.

    2014-01-01

    We generalize the universal effective quantum number introduced earlier for centrally symmetric problems. The proposed number determines the semiclassical quantization condition for axially symmetric potentials.

  10. Mass Effect on Axial Charge Dynamics

    CERN Document Server

    Guo, Er-dong

    2016-01-01

    We studied effect of finite quark mass on the dynamics of axial charge using the D3/D7 model in holography. The mass term in axial anomaly equation affects both the fluctuation (generation) and dissipation of axial charge. We studied the dependence of the effect on quark mass and external magnetic field. For axial charge generation, we calculated the mass diffusion rate, which characterizes the helicity flipping rate. The rate is a non-monotonous function of mass and can be significantly enhanced by the magnetic field. The diffusive behavior is also related to a divergent susceptibility of axial charge. For axial charge dissipation, we found that in the long time limit, the mass term dissipates all the charge effectively generated by parallel electric and magnetic fields. The result is consistent with a relaxation time approximation. The rate of dissipation through mass term is a monotonous increasing function of both quark mass and magnetic field.

  11. Manganese (III) cyclam complexes with aqua, iodo, nitrito, perchlorato and acetic acid/acetato axial ligands

    DEFF Research Database (Denmark)

    Mossin, Susanne; Sørensen, Henning Osholm; Weihe, Høgni; Glerup, Jørgen; Søtofte, Inger

    2005-01-01

    The syntheses, structures and magnetic properties of five new manganese (III) cyclam complexes, trans-[Mn(cyclam)(OH2)(2)]-(CF3SO3)(3)center dot-H2O, trans-[Mn(cyclam)I-2]I, trans-[Mn(cyclam)(ONO)(2)]ClO4, trans-[Mn(cyclam)(OClO3)(2)]ClO4 and trans-[Mn(cyclam) (CH3COO)(CH3COOH)](ClO4)(2), are rep...... pseudo-chain structure. The tilt of the axial ligands with respect to the equatorial plane containing the manganese and the cyclam nitrogen atoms is discussed....

  12. Monophthalocyanine complexes of samarium and terbium with axial ligands:synthesis, structure and optoelectronic properties

    Institute of Scientific and Technical Information of China (English)

    Alexander A Maleev; Mikhail N Bochkarev; Anatoly P Pushkarev; Vasily A Ilichev; Mikhail A Lopatin; Maxim A Samsonov; Georgy K Fukin; Georgy L Pakhomov; Vladislav V Travkin; Ivan D Grishin

    2014-01-01

    The monophthalocyanine complexes of samarium and terbium containing axial 2-mercaptobenzothiazole (PcSm(MBT) (1)), 2-(2-benzoxazol-2-yl) phenolate (PcTb(OON) (2)) or 2-(2-benzothiazol-2-yl)phenolate (PcTb(SON) (3)) ligands were synthe-sized and identified by elemental, LDI-TOF and X-ray (for 1) analysis. Photoluminescence (PL) and electroluminescence (EL) spec-tra of the compounds contained only emission bands of phthalocyanine and axial ligands but did not contain the bands of f-f transi-tions. It was found that among the complexes 1, 2, 3 the latter had highest photoconductivity (~10–7 S/cm) and photovoltaic properties. An organic photovoltaic device (OPV) of configuration of ITO/3/C60/Alq3/Al revealed open-circuit voltage (VOC) of 0.24 V and short current density (ISC) of 0.3μA/cm2 under illumination by a xenon lamp at 17 mW/cm2.

  13. Influence of axial and peripheral ligands on the electronic structure of titanium phthalocyanines

    DEFF Research Database (Denmark)

    Pickup, David F.; García Lastra, Juan Maria; Rogero, Celia;

    2013-01-01

    To discover how molecular changes affect the electronic structure of dye molecules for solar cells, we have investigated four titanium phthalocyanines customized by axial and peripheral ligands (monodentate oxo versus bidentate catechol and tert-butyl versus tert-butylphenoxy, respectively). X...... ligand, the multiplet structure of the Ti 2p-to-3d transitions was found to change systematically. The most noticeable change was an additional transition into the low-lying 3dxy level, which is attributed to a reduction in local symmetry from 4-fold to 2-fold at the Ti center. An increase of the Ti 2p...... core-level binding energy was observed in the bidentate complex and compared to a calculated core-level stabilization. DFT predicts a change of the LUMO from the inner phthalocyanine ring to the Ti dxy orbital and a reversal of the high-lying dx2-y2 and d z2 orbitals. The N 1s edge was calculated using...

  14. Photochemical hydrogen production and cobaloximes: the influence of the cobalt axial N-ligand on the system stability.

    Science.gov (United States)

    Panagiotopoulos, Athanassios; Ladomenou, Kalliopi; Sun, Dongyue; Artero, Vincent; Coutsolelos, Athanassios G

    2016-04-12

    We report on the first systematic study of cobaloxime-based hydrogen photoproduction in mixed pH 7 aqueous/acetonitrile solutions and demonstrate that H2 evolution can be tuned through electronic modifications of the axial cobalt ligand or through introduction of TiO2 nanoparticles. The photocatalytic systems consist of various cobaloxime catalysts [Co(dmgH)2(L)Cl] (L = nitrogen-based axial ligands) and a water soluble porphyrin photosensitizer. They were assayed in the presence of triethanolamine as a sacrificial electron donor. Optimal turnover numbers related to the photosensitizer are obtained with electron-rich axial ligands such as imidazole derivatives (1131 TONs with N-methyl imidazole). Lower stabilities are observed with various pyridine axial ligands (443 TONs for para-methylpyridine), especially for those containing electron-acceptor substituents. Interestingly, when L is para-carboxylatopyridine the activity of the system is increased from 40 to 223 TONs in the presence of TiO2 nanoparticles. PMID:26978600

  15. Isocyanide or nitrosyl complexation to hemes with varying tethered axial base ligand donors: synthesis and characterization.

    Science.gov (United States)

    Sharma, Savita K; Kim, Hyun; Rogler, Patrick J; A Siegler, Maxime; Karlin, Kenneth D

    2016-09-01

    A series of ferrous-heme 2,6-dimethylphenyl isocyanide (DIMPI) and ferrous-heme mononitrosyl complexes have been synthesized and characterized. The heme portion of the complexes studied is varied with respect to the nature of the axial ligand, including complexes, where it is covalently tethered to the porphyrinate periphery. Reduced heme complexes, [(F8)Fe(II)], [(P(Py))Fe(II)], [(P(Im))Fe(II)], and [(P(ImH))Fe(II)], where F8 = tetrakis(2,6-difluorophenyl)-porphyrinate and P(Py), P(Im), and P(ImH) are partially fluorinated tetraaryl porphyrinates with covalently appended axial base pyridyl/imidazolyl or histamine moieties, were employed; P(ImH) is a new construct. Room temperature addition of DIMPI to these iron(II) complexes affords the bis-isocyanide species [(F8)Fe(II)-(DIMPI)2] in the case of [(F8)Fe(II)], while for the other hemes, mono-DIMPI compounds are obtained, [(P(Py))Fe(II)-(DIMPI)] [(2)-DIMPI], [(P(Im))Fe(II)-(DIMPI)] [(3)-DIMPI], and [(P(ImH))Fe(II)-(DIMPI)] [(4)-DIMPI]. The structures of complexes (3)-DIMPI and (4)-DIMPI have been determined by single crystal X-ray crystallography, where interesting H…F(porphryinate aryl group) interactions are observed. (19)F-NMR spectra determined for these complexes suggest that H…F(porphyrinate aryl groups) attractions also occur in solution, the H atom coming either from the DIMPI methyl groups or from a porphyinate axial base imidazole or porphyrinate pyrrole. Similarly, we have used nitrogen monoxide to generate ferrous-nitrosyl complexes, a five-coordinate species for F8, [(F8)Fe(II)-(NO)], or low-spin six-coordinate compounds [(P(Py))Fe(II)-(NO)], [(P(Im))Fe(II)-(NO)], and [(P(ImH))Fe(II)-(NO)]. The DIMPI and mononitrosyl complexes have also been characterized using UV-Vis, IR, (1)H-NMR, and EPR spectroscopies. PMID:27350154

  16. Equilibria and kinetics for pH-dependent axial ligation of bromomethyl(aquo)cobaloxime by aliphatic amine ligands

    Indian Academy of Sciences (India)

    M Bhoopal; N Ravi Kumar Reddy; S Satyanarayana

    2003-04-01

    Kinetics and equilibria of axial ligation of bromomethyl(aquo) cobaloxime by a series of straight chain primary amines (methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine), cycloamines (cyclopentylamine, cyclohexylamine, cycloheptylamine) and secondary amines (N,N-dimethylamine, N,N-diethylamine) have been measured as functions of pH by spectrophotometric technique in aqueous solution, ionic strength 1 M (KCl) at 25°C. The rate of substitution of H2O varies with the Ka of incoming ligand, thus establishing nucleophilic participation of the ligand in the transition state. Binding and kinetic data are interpreted based on the basicity and steric influence of the entering ligand. To compare the rate constants of the entering ligands, pH independent second-order rate constants (on) are calculated.

  17. Reactivity effects of nonuniform axial burnup distributions on spent fuel

    International Nuclear Information System (INIS)

    When conducting future criticality safety analyses on spent fuel shipping casks, burnup credit may play a significant role in determining the number of fuel assemblies that can be safely loaded into each cask. An important area in burnup credit analysis is the burnup variation along the length of the fuel assembly, which is determined by the location of the assembly in the reactor core and its residence time. A study of the effects of axial burnup distributions on reactivity has been conducted, using data from existing power plant fuel. Utilizing a one-dimensional, two-group diffusion code, named REALAX, the reactivity effects of axial burnup profiles have been calculated for various PWR fuel assemblies. The reactivity effects calculated by the code are defined in terms of k for the axially dependent burnup distribution minus k for a uniform axial burnup distribution at the assembly average burnup divided by k for a uniform axial burnup distribution at the assembly average burnup. Criticality safety specialists can take advantage of the quick-running code to determine axial effects of different assembly burnup profiles. In general, the positive reactivity effects of axial burnup distributions increase as burnup increases, though they do not increase faster than the overall decrease in reactivity due to burnup

  18. Reactivity effects of nonuniform axial burnup distributions on spent fuel

    Energy Technology Data Exchange (ETDEWEB)

    Leary, R.W. II; Parish, T.A. [Texas A & M Univ., College Station, TX (United States)

    1995-12-01

    When conducting future criticality safety analyses on spent fuel shipping casks, burnup credit may play a significant role in determining the number of fuel assemblies that can be safely loaded into each cask. An important area in burnup credit analysis is the burnup variation along the length of the fuel assembly, which is determined by the location of the assembly in the reactor core and its residence time. A study of the effects of axial burnup distributions on reactivity has been conducted, using data from existing power plant fuel. Utilizing a one-dimensional, two-group diffusion code, named REALAX, the reactivity effects of axial burnup profiles have been calculated for various PWR fuel assemblies. The reactivity effects calculated by the code are defined in terms of k for the axially dependent burnup distribution minus k for a uniform axial burnup distribution at the assembly average burnup divided by k for a uniform axial burnup distribution at the assembly average burnup. Criticality safety specialists can take advantage of the quick-running code to determine axial effects of different assembly burnup profiles. In general, the positive reactivity effects of axial burnup distributions increase as burnup increases, though they do not increase faster than the overall decrease in reactivity due to burnup.

  19. Synthesis of Ruthenium(III Phthalocyanine with Di-axial Bromo Ligands - A Promising Molecular Conductor with Giant Negative Magnetoresistance

    Directory of Open Access Journals (Sweden)

    Mario A.V. Gamboa

    2015-01-01

    Full Text Available The electron transport of Phthalocyanines (Pc with central metal and di-axial ligands (such as FeIII(PcL2; where L = CN, Cl, Br originates from its intermolecular Pc π-π orbital overlap while its giant negative magnetoresistance (GNMR arises from its intramolecular Pc-π(HOMO and Fe-d (s=1/2 interaction. However, the π-d interaction tends to localize itinerant electrons resulting in the decrease in the conductivity of the FeIII(PcL2 series compared to the non-magnetic CoIII(PcL2 where π-d interaction is absent. More so, the axial ligand field energy of the FeIII(PcL2 system is found to have the ability to proportionally modulate the π-d interaction. In reference thereof, theoretical calculations point that isostructural RuIII(PcBr2 would provide the best balance of π-d orbital energy interplay. That is, RuIII(PcBr2 is expected to be a molecule with high electrical conductivity and GNMR which would make it an ideal magnetic molecular conductor. This paper reports on the synthesis of RuIII(PcBr2.

  20. Effect of axial heat flux distribution on CHF

    International Nuclear Information System (INIS)

    Previous investigations for the effect of axial heat flux distributions on CHF and the prediction methods are reviewed and summarized. A total of 856 CHF data in a tube with a non-uniform axial heat flux distribution has been compiled from the articles and analyzed using the 1995 Groeneveld look-up table. The results showed that two representative correction factors, K5 of the look-up table and Tongs F factor, can be applied to describe the axial heat flux distribution effect on CHF. However, they overpredict slightly the measured CHF, depending on the quality and flux peak shape. Hence, a corrected K5 factor, which accounts for the axial heat flux distribution effect is suggested to correct these trends. It predicted the CHF power for the compiled data with an average error of 1.5% and a standard deviation of 10.3%, and also provides a reasonable prediction of CHF locations

  1. Nuclear Axial Currents in Chiral Effective Field Theory

    OpenAIRE

    Baroni, A.; Girlanda, L.; Pastore, S.; Schiavilla, R.; Viviani, M

    2015-01-01

    Two-nucleon axial charge and current operators are derived in chiral effective field theory up to one loop. The derivation is based on time-ordered perturbation theory, and accounts for cancellations between the contributions of irreducible diagrams and the contributions due to non-static corrections from energy denominators of reducible diagrams. Ultraviolet divergencies associated with the loop corrections are isolated in dimensional regularization. The resulting axial current is finite and...

  2. Coenzyme B12 model studies: Equilibrium constants for the H-dependent axial ligation of benzyl(aquo)cobaloxime by various N- and S-donor ligands

    Indian Academy of Sciences (India)

    D Sudarshan Reddy; N Ravi Kumar Reddy; V Sridhar; S Satyanarayana

    2002-02-01

    Equilibria of the axial ligation of benzyl(aquo)cobaloximes by imidazole, 1-methyl imidazole, histidine, histamine, glycine, ethyl glycine ester, thiourea and urea have been spectrophotometrically measured in aqueous solutions of ionic strength 1.0 M (KCl) at 25°C as a function of H. The equilibrium constants are in the order CN- > 1-methyl imidazole > imidazole > histidine > histamine > glycine > ethyl glycine ester > thiourea > urea. The order of stability of benzyl(ligand)cobaloxime is explained based on the basicity of the ligand, Co(III) → - back bonding and soft-soft and soft-hard interaction. Imidazole, substituted imidazoles, histidine and histamine form more stable complexes than glycine, ethyl glycine ester in contrast to the basicity of the ligands. Benzyl(ligand)cobaloximes were isolated and characterized by elemental analysis, IR and 1H NMR spectra.

  3. Axial anomaly, Dirac sea, and the chiral magnetic effect

    OpenAIRE

    Kharzeev, Dmitri E.

    2010-01-01

    Gribov viewed the axial anomaly as a manifestation of the collective motion of charged fermions with arbitrarily high momenta in the vacuum. In the presence of an external magnetic field and a chirality imbalance, this collective motion becomes directly observable in the form of the electric current - this is the chiral magnetic effect (CME). I give an elementary introduction into the physics of CME, and discuss some recent developments.

  4. Characterization of a potentially axially symmetric europium(III) complex of a tetraacetate,tetraaza, macrocyclic ligand by luminescence excitation, emission and lifetime spectroscopy

    Science.gov (United States)

    Albin, Michael; de, William; Horrocks, W., Jr.; Liotta, Frank J.

    1982-01-01

    The Eu(III) complex of the octadentate macrocyclic ligand, 1,4,7,10-tetraazacyclododecane-N,N',N'',N''' -tetraacetate, DOTA, has been examined by luminescence excitation, emission, and lifetime spectroscopy using pulsed dye laser techniques. The results confirm the expected axially symmetric nature of the major component in solution and reveal that 1.2 ± 0.4 water molecules arc coordinatcd to the Eu(III) ion in the complex.

  5. Frequency response of a thermocouple wire: Effects of axial conduction

    Science.gov (United States)

    Forney, L. J.; Fralick, G. C.

    1990-01-01

    Theoretical expressions are derived for the steady-state frequency response of a thermocouple wire. In particular, the effects of axial heat conduction are demonstrated for both a uniform thermocouple wire and a nonuniform wire with unequal material properties and wire diameters across the junction. For the case of a uniform wire, the amplitude ratio and phase angle compare favorably with the series solution of Scadron and Warshawsky (1952) except near the ends of the wire. For the case of a non-uniform wire, the amplitude ratio at low frequency omega yields 0 agrees with the results of Scadron and Warshawsky for a steady-state temperature distribution. Moreover, the frequency response for a non-uniform wire in the limit of infinite length l yields infinity is shown to reduce to a simple expression that is analogous to the classic first order solution for a thermocouple wire with uniform properties.

  6. Effects of external axial magnetic field on fast electron propagation

    International Nuclear Information System (INIS)

    A scheme employing an external axial magnetic field is proposed to diagnose the intrinsic divergence of laser-generated fast electron beams, and this is studied numerically with hybrid simulations. The maximum beam radius of fast electrons increases with the initial divergence and decreases with the amplitude of the axial magnetic field. It is indicated that the intrinsic divergence of fast electrons can be inferred from measurements of the beam radius at different depth under the axial field. The proposed scheme here may be useful for future fast ignition experiments and in other applications of laser-generated fast electron beams.

  7. Effect of weld reinforcement on axial plastic buckling of welded steel cylindrical shells

    Institute of Scientific and Technical Information of China (English)

    Chu-lin YU; Zhi-ping CHEN; Ji WANG; Shun-juan YAN; Li-cai YANG

    2012-01-01

    The effect of weld reinforcement on axial plastic buckling of welded steel cylindrical shells is investigated through experimental and numerical buckling analysis using six welded steel cylindrical shell specimens.The relationship between the amplitude of weld reinforcement and the axial plastic buckling critical load is explored.The effect of the material yield strength and the number of circumferential welds on the axial plastic buckling is studied.Results show that circumferential weld reinforcement represents a severe imperfect form of axially compressed welded steel cylindrical shells and the axial plastic buckling critical load decreases with the increment of the mean amplitude of circumferential weld reinforcement.The material yield strength and the number of circumferential welds are found to have no significant effect on buckling waveforms; however,the axial plastic buckling critical load can be decreased to some extent with the increase of the number of circumferential welds.

  8. Effect of the axial scraping velocity on enhanced heat exchangers

    International Nuclear Information System (INIS)

    Highlights: • The flow pattern has been obtained by means of PIV in an enhanced heat exchanger. • The effects of the Reynolds number and the scraping velocity have been analysed. • The turbulence level of the flow has been related to the scraping velocity. • A numerical RNG k–ε turbulent model has been validated with the experimental data. -- Abstract: The flow pattern within an enhanced tubular heat exchanger equipped with a reciprocating scraping device is experimentally analysed. The insert device, specially designed to avoid fouling and to enhance heat transfer, has also been used to produce ice slurry. It consists of several circular perforated scraping discs mounted on a coaxial shaft. The whole is moved alternatively along the axial direction by a hydraulic cylinder. The phase-averaged velocity fields of the turbulent flow have been obtained with PIV technique for both scraping semi-cycles. Special attention has been paid to the effect of the non-dimensional scraping velocity and the Reynolds number in the flow field. CFD simulations provide support for the identification of the flow patterns and the parameter assessment extension. The results show how the scraping parameters affect the turbulence level produced in the flow and therefore the desired heat transfer enhancement

  9. Axial Magnetic Field Effect on Taylor-Couette Flow

    Directory of Open Access Journals (Sweden)

    Sofiane ABERKANE

    2015-01-01

    Full Text Available This study is interested in the effect of an axial magnetic field imposed on incompressible flow of electrically conductive fluid between two horizontal coaxial cylinders. The imposed magnetic field is assumed uniform and constant. The effect of heat generation due to viscous dissipation is also taken into account. The inner and outer cylinders are maintained at different uniform temperatures. The movement of the fluid is due to rotation of the cylinder with a constant speed. An exact solution of the equations governing the flow was obtained in the form of Bessel functions. A finite difference implicit scheme was used in the numerical solution. The velocity and temperature distributions were obtained with and without the magnetic field. The results show that for different values of the Hartmann number, the velocity between the two cylinders decreases as the Hartmann number increases. Also, it is found that by increasing the Hartmann number, the average Nusselt number decreases. On the other hand, the Hartmann number does not affect the temperature.

  10. An effective theory for QCD with an axial chemical potential

    CERN Document Server

    Andrianov, Alexander A; Espriu, Domenec; Planells, Xumeu

    2013-01-01

    We consider the low energy realization of QCD in terms of meson fields when an axial chemical potential is present; a situation that may be relevant in heavy ion collisions. We shall demonstrate that the presence of an axial charge constitutes an explicit source of parity breaking. The eigenstates of strong interactions do not have a definite parity and interactions that would otherwise be forbidden compete with the familiar ones. In this work, we first focus on scalars and pseudoscalars that are described by a generalized linear sigma model; and next, we give some hints on how the Vector Meson Dominance model describes the vector sector.

  11. Effects of PPARγ Ligands on Leukemia

    Directory of Open Access Journals (Sweden)

    Yoko Tabe

    2012-01-01

    Full Text Available Peroxisome proliferator-activated receptors (PPARs and retinoic acid receptors (RARs, members of the nuclear receptor superfamily, are transcription factors that regulate a variety of important cellular functions. PPARs form heterodimers retinoid X receptor (RXR, an obligate heterodimeric partner for other nuclear receptors. Several novel links between retinoid metabolism and PPAR responses have been identified, and activation of PPAR/RXR expression has been shown to increase response to retinoids. PPARγ has emerged as a key regulator of cell growth and survival, whose activity is modulated by a number of synthetic and natural ligands. While clinical trials in cancer patients with thiazolidinediones (TZD have been disappointing, novel structurally different PPARγ ligands, including triterpenoids, have entered clinical arena as therapeutic agents for epithelial and hematopoietic malignancies. Here we shall review the antitumor advances of PPARγ, alone and in combination with RARα ligands in control of cell proliferation, differentiation, and apoptosis and their potential therapeutic applications in hematological malignancies.

  12. Replacing the axial ligand tyrosine 75 or its hydrogen bond partner histidine 83 minimally affects hemin acquisition by the hemophore HasAp from Pseudomonas aeruginosa.

    Science.gov (United States)

    Kumar, Ritesh; Matsumura, Hirotoshi; Lovell, Scott; Yao, Huili; Rodríguez, Juan C; Battaile, Kevin P; Moënne-Loccoz, Pierre; Rivera, Mario

    2014-04-01

    Hemophores from Pseudomonas aeruginosa (HasAp), Serratia marcescens (HasAsm), and Yersinia pestis (HasAyp) bind hemin between two loops. One of the loops harbors conserved axial ligand Tyr75 (Y75 loop) in all three structures, whereas the second loop (H32 loop) contains axial ligand His32 in HasAp and HasAsm, but a noncoordinating Gln32 in HasAyp. Binding of hemin to the Y75 loop of HasAp or HasAsm causes a large rearrangement of the H32 loop that allows His32 coordination. The Q32 loop in apo-HasAyp is already in the closed conformation, such that binding of hemin to the conserved Y75 loop occurs with minimal structural rearrangement and without coordinative interaction with the Q32 loop. In this study, structural and spectroscopic investigations of the hemophore HasAp were conducted to probe (i) the role of the conserved Tyr75 loop in hemin binding and (ii) the proposed requirement of the His83-Tyr75 hydrogen bond to allow the coordination of hemin by Tyr75. High-resolution crystal structures of H83A holo-HasAp obtained at pH 6.5 (0.89 Å) and pH 5.4 (1.25 Å) show that Tyr75 remains coordinated to the heme iron, and that a water molecule can substitute for Nδ of His83 to interact with the Oη atom of Tyr75, likely stabilizing the Tyr75-Fe interaction. Nuclear magnetic resonance spectroscopy revealed that in apo-Y75A and apo-H83A HasAp, the Y75 loop is disordered, and that disorder propagates to nearby elements of secondary structure, suggesting that His83 Nδ-Tyr75 Oη interaction is important to the organization of the Y75 loop in apo-HasA. Kinetic analysis of hemin loading conducted via stopped-flow UV-vis and rapid-freeze-quench resonance Raman shows that both mutants load hemin with biphasic kinetic parameters that are not significantly dissimilar from those previously observed for wild-type HasAp. When the structural and kinetic data are taken together, a tentative model emerges, which suggests that HasA hemophores utilize hydrophobic, π-π stacking, and

  13. Effects of axial burnup distributions on the reactivity of spent fuel

    International Nuclear Information System (INIS)

    Criticality safety analyses for spent fuel shipping casks will eventually need to take credit for the decreased reactivity of spent fuel assemblies resulting from burnup. In order to do so, it will be necessary to assess the reactivity effects of the multitude of burnup shapes that can characterize spent fuel. A computer program, CASAX, has been written that allows the analyst to quickly evaluate the reactivity effects of actual and simplified axial burnup distributions on a group of PWR fuel assemblies. CASAX employs one dimensional, two group diffusion calculations to determine the k-effective of a cluster of assemblies. Assembly average, burnup dependent, two group cross sections for CASAX were obtained from CASMO3 using physical properties representative of Westinghouse 17 x 17 assemblies. Reactivity results are presented in terms of (k for the axially dependent burnup distribution minus k for a uniform axial burnup distribution at the assembly average burnup)/(k for a uniform axial burnup distribution at the assembly average burnup). Axial burnup distributions can have both positive and negative effects on the calculated k-effective. Positive reactivity effects generally result at high assembly average burnups and for axial distributions with low burnups in the assembly's tips

  14. An effective QCD Lagrangian in the presence of an axial chemical potential

    International Nuclear Information System (INIS)

    We consider the low energy realization of QCD in terms of mesons when an axial chemical potential is present; a situation that may be relevant in heavy ion collisions. We shall demonstrate that the presence of an axial charge has profound consequences on meson physics. The most notorious effect is the appearance of an explicit source of parity breaking. The eigenstates of strong interactions do not have a definite parity and interactions that would otherwise be forbidden compete with the familiar ones. In this work we focus on scalars and pseudoscalars that are described by a generalized linear sigma model. We comment briefly on the screening role of axial vectors in formation of effective axial charge and on the possible experimental relevance of our results, whose consequences may have been already seen at RHIC. (orig.)

  15. Stabilizing effects of ankle bracing under a combination of inversion and axial compression loading.

    Science.gov (United States)

    Tohyama, Harukazu; Yasuda, Kazunori; Beynnon, Bruce D; Renstrom, Per A

    2006-04-01

    The combined effects of bracing, axial compression and inversion rotation on the ankle-subtalar complexes were evaluated. Ex vivo tests under the load-controlled condition were performed on six cadaver ankle specimens using a six degree-of-freedom fixture. Inversion rotation was measured while subjecting the ankle-subtalar complex to a 2.5 N-m inversion moment and a combination of the testing variables (brace type, no brace, 178 N axial compression load, no compression load, 0 degrees and 20 degrees of plantar flexion) for a total of 16 tests per specimen. Three commercially available braces (two semirigid types and one lace up type) were evaluated. An axial compression load significantly decreased ankle-subtalar motion in unbraced ankles for the tested inversion moment. The contribution of bracing to stabilization of the ankle was smaller in the axial loading condition than in the no axial loading condition. The semirigid braces had greater stabilizing effects in response to the inversion moment than the lace up brace. Stabilizing effects of bracing were significantly greater in 20 degrees of plantar flexion than in 0 degrees of plantar flexion. The most common mechanism for an ankle sprain injury is inversion rotation on a weight-bearing ankle. Therefore, we should not overestimate stabilizing effects of bracing from evaluations of bracing without axial compression loading. PMID:15959767

  16. Modification of diphenylamine-linked bis(oxazoline) ligands: Tuning of electronic effect and rigidity of ligand skeleton

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The electronic effect of diphenylamine-linked bis(oxazoline) ligands was tuned through introduction of electron-withdrawing bromo and nitro substituents onto the 4 and 4′ position. The variation of the NH bond acidity was determined by the different chemical shifts of NH. The catalytic activity and enantioselectivity of the modified ligands were tested in the asymmetric Friedel-Crafts alkylation of indole with β-nitrostyrene. The effect of ligand skeleton rigidity was also investigated through the synthesis of iminodibenzyl-linked bis(oxazoline) ligands and evaluation of their catalytic activity in Friedel-Crafts alkylation.

  17. Ligand and ensemble effects in adsorption on alloy surfaces

    DEFF Research Database (Denmark)

    Liu, Ping; Nørskov, Jens Kehlet

    2001-01-01

    Density functional theory is used to study the adsorption of carbon monoxide, oxygen and nitrogen on various Au/Pd(111) bimetallic alloy surfaces. By varying the Au content in the surface we are able to make a clear separation into geometrical (or ensemble) effects and electronic (or ligand......) effects determining the adsorption properties....

  18. End effect analysis with various axial burnup distributions in high density spent fuel storage racks

    International Nuclear Information System (INIS)

    Highlights: • Criticality tests are carried out with various axial burnup distributions of fuel assemblies for spent fuel storage racks. • KENO-Va code system was used to obtain criticalities with 10 axial segments. • ORIGEN-S code system was used to obtain burnup dependent axial compositions. • The criticality and burnup dependent reactivity difference are obtained from the results. • End effect quantifications are satisfactory confirming the previous suggestions. - Abstract: End effect of spent fuel comes from the difference between uniform and actual axial burnup distributions of fuel assemblies. It is significant to control the criticality safety in spent fuel storage and transportation. This work is focused on estimation of end effect in the spent fuel of light water reactor for the spent fuel storage rack region-II. High and low burnups of corresponding different uranium enrichments are taken into consideration to analyze the end effect with different axial burnup distributions such as uniform, MOC and EOC profiles. Two types of fuel assemblies such as CE type and Westinghouse type are considered. The whole calculations have been carried out by using the SCALE6 code including ORIGEN-S and KENO-Va

  19. Synergistic Effects of PPARγ Ligands and Retinoids in Cancer Treatment

    Directory of Open Access Journals (Sweden)

    Masahito Shimizu

    2008-01-01

    Full Text Available Peroxisome proliferator-activated receptors (PPARs are members of the nuclear receptor superfamily. The activation of PPARs by their specific ligands is regarded as one of the promising strategies to inhibit cancer cell growth. However, recent clinical trials targeting several common cancers showed no beneficial effect when PPAR ligands are used as a monotherapy. Retinoid X receptors (RXRs, which play a critical role in normal cell proliferation as a master regulator for nuclear receptors, preferentially form heterodimers with PPARs. A malfunction of RXRα due to phosphorylation by the Ras/MAPK signaling pathway is associated with the development of certain types of human malignancies. The activation of PPARγ/RXR heterodimer by their respective ligands synergistically inhibits cell growth, while inducing apoptosis in human colon cancer cells when the phosphorylation of RXRα was inhibited. We herein review the synergistic antitumor effects produced by the combination of the PPAR, especially PPARγ, ligands plus other agents, especially retinoids, in a variety of human cancers. We also focus on the phosphorylation of RXRα because the inhibition of RXRα phosphorylation and the restoration of its physiological function may activate PPAR/RXR heterodimer and, therefore, be a potentially effective and critical strategy for the inhibition of cancer cell growth.

  20. A study of friction and axial effects in pellet-clad mechanical interaction

    International Nuclear Information System (INIS)

    An analysis is made of the effect of friction and axial forces along the fuel rod in the pellet-cladding mechanical interaction in a commercial reactor under a power-up ramp. The effect of different pellet and rod shapes on their behaviour was also determined. A linear thermoelastic computer program was used in order to obtain the stiffness matrix of a compound structure from the stiffness of its components. Pellet-cladding displacements, localized deformations of the cladding in the interfaces between pellets, as well as pellet and cladding axial deformations were determined for different power axial profiles as well as for pellets with and without dishing and with height/diameter ratios of 1.7, 1 and 0.5. (M.E.L.)

  1. Modification of diphenylamine-linked bis(oxazoline)ligands:Tuning of electronic effect and rigidity of ligand skeleton

    Institute of Scientific and Technical Information of China (English)

    LIU Han; LI Wei; DU DaMing

    2009-01-01

    The electronic effect of diphenylamine-linked bis(oxazoline) ligands was tuned through introduction of electron-withdrawing bromo and nitro substituents onto the 4 and 4' position.The variation of the NH bond acidity was determined by the different chemical shifts of NH.The catalytic activity and enantioselectivity of the modified ligands were tested in the asymmetric FriedeI-Crafts alkylation of indole with β-nitrostyrene.The effect of iigand skeleton rigidity was also investigated through the synthesis of iminodibenzyl-linked bis(oxazoline) ligands and evaluation of their catalytic activity in Friedel-Crafts alkylation.

  2. Stabilizing effects of ankle bracing under a combination of inversion and axial compression loading

    OpenAIRE

    Tohyama, Harukazu; Yasuda, Kazunori; Beynnon, Bruce D.; Renstrom, Per A.

    2006-01-01

    The combined effects of bracing, axial compression and inversion rotation on the ankle-subtalar complexes were evaluated. Ex vivo tests under the load-controlled condition were performed on six cadaver ankle specimens using a six degree-of-freedom fixture. Inversion rotation was measured while subjecting the ankle-subtalar complex to a 2.5 N-m inversion moment and a combination of the testing variables (brace type, no brace, 178 N axial compression load, no compression load, 0° and 20° of pla...

  3. Effect of Axial Force on the Performance of Micromachined Vibratory Rate Gyroscopes

    Directory of Open Access Journals (Sweden)

    Zhengyi Niu

    2010-12-01

    Full Text Available It is reported in the published literature that the resonant frequency of a silicon micromachined gyroscope decreases linearly with increasing temperature. However, when the axial force is considerable, the resonant frequency might increase as the temperature increases. The axial force is mainly induced by thermal stress due to the mismatch between the thermal expansion coefficients of the structure and substrate. In this paper, two types of micromachined suspended vibratory gyroscopes with slanted beams were proposed to evaluate the effect of the axial force. One type was suspended with a clamped-free (C-F beam and the other one was suspended with a clamped-clamped (C-C beam. Their drive modes are the bending of the slanted beam, and their sense modes are the torsion of the slanted beam. The relationships between the resonant frequencies of the two types were developed. The prototypes were packaged by vacuum under 0.1 mbar and an analytical solution for the axial force effect on the resonant frequency was obtained. The temperature dependent performances of the operated mode responses of the micromachined gyroscopes were measured. The experimental values of the temperature coefficients of resonant frequencies (TCF due to axial force were 101.5 ppm/°C for the drive mode and 21.6 ppm/°C for the sense mode. The axial force has a great influence on the modal frequency of the micromachined gyroscopes suspended with a C-C beam, especially for the flexure mode. The quality factors of the operated modes decreased with increasing temperature, and changed drastically when the micromachined gyroscopes worked at higher temperatures.

  4. Evaluation of electromagnetic shielding effectiveness of multi-axial fabrics and their reinforced PES composites

    Indian Academy of Sciences (India)

    RAMAZAN ERDEM

    2016-08-01

    The usage of electrical and electronic equipments has been increasing in daily life, which has a potential hazardous impact on humans and other living organisms. In this paper, multi-axial fabrics containing steel yarns and carbon filaments, and their polyester (PES) resin-reinforced composites have been prepared for electromagnetic shielding applications. The electromagnetic shielding effectiveness (EMSE) of these structures was determined by using coaxial transmission line measurement technique. There were eight different multi-axial fabrics constructed. It was observed that the amount and the orientation of carbon and stainless steel yarns influenced the EMSE performances of multi-axial fabrics and their reinforced PES composites. The structures containing both carbon filaments and stainless steel yarns exhibited better EMSE than the ones including only one type of conductive yarns or filaments. Also, the EMSE performance of multi-axial fabrics was found better than their reinforced composites. The best EMSE results were obtained for the fabric, including two layers of yarns (steel and carbon) on top of each otherin the centre with the angle of 45 and $−$45$^{\\circ}$.

  5. Axial buckling and transverse vibration of ultrathin nanowires: low symmetry and surface elastic effect

    Science.gov (United States)

    Lei, Xiao; Narsu, B.; Yun, Guohong; Li, Jiangang; Yao, Haiyan

    2016-05-01

    Surface effects play a deterministic role in the physical and mechanical properties of nanosized materials and structures. In this paper, we present a self-consistent theoretical scheme for describing the elasticity of nanowires. The natural frequency and the critical compression force of axial buckling are obtained analytically, taking into consideration the influences of lower symmetry, additional elastic parameters, surface reconstruction, surface elasticity, and residual surface stress. Applications of the present theory to elastic systems for the    axially oriented Si and Cu nanowires and Ag    axially oriented nanowires yield good agreement with experimental data and calculated results. The larger positive value of the new elastic parameter c12α taken into account for Si    oriented nanowires drives the curves of natural frequency and critical compression force versus thickness towards the results obtained from density functional theory simulation. Negative surface stress decreases the critical load for axial buckling, thus making the nanowires very easy to bend into various structures. The present study is envisaged to provide useful insights for the design and application of nanowire-based devices.

  6. Understanding ligand effects in gold clusters using mass spectrometry.

    Science.gov (United States)

    Johnson, Grant E; Laskin, Julia

    2016-06-21

    This review summarizes recent research on the influence of phosphine ligands on the size, stability, and reactivity of gold clusters synthesized in solution. Sub-nanometer clusters exhibit size- and composition-dependent properties that are unique from those of larger nanoparticles. The highly tunable properties of clusters and their high surface-to-volume ratio make them promising candidates for a variety of technological applications. However, because "each-atom-counts" toward defining cluster properties it is critically important to develop robust synthesis methods to efficiently prepare clusters of predetermined size. For decades phosphines have been known to direct the size-selected synthesis of gold clusters. Despite the preparation of numerous species it is still not understood how different functional groups at phosphine centers affect the size and properties of gold clusters. Using electrospray ionization mass spectrometry (ESI-MS) it is possible to characterize the effect of ligand substitution on the distribution of clusters formed in solution at defined reaction conditions. In addition, ligand exchange reactions on preformed clusters may be monitored using ESI-MS. Collision induced dissociation (CID) may also be employed to obtain qualitative insight into the fragmentation of mixed ligand clusters and the relative binding energies of differently substituted phosphines. Quantitative ligand binding energies and cluster stability may be determined employing surface induced dissociation (SID) in a custom-built Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS). Rice-Ramsperger-Kassel-Marcus (RRKM) based modeling of the SID data allows dissociation energies and entropy values to be extracted. The charge reduction and reactivity of atomically precise gold clusters, including partially ligated species generated in the gas-phase by in source CID, on well-defined surfaces may be explored using ion soft landing (SL) in a custom

  7. Effect of axial ligation and delivery system on the tumour-localising and -photosensitising properties of Ge(IV)-octabutoxy-phthalocyanines.

    Science.gov (United States)

    Soncin, M; Polo, L; Reddi, E; Jori, G; Kenney, M E; Cheng, G; Rodgers, M A

    1995-04-01

    Four Ge(IV)-octabutoxy-phthalocyanines (GePcs) bearing two alkyl-type axial ligands were assayed for their pharmacokinetic properties and phototherapeutic efficiency in Balb/c mice bearing an intramuscularly transplanted MS-2 fibrosarcoma. The GePcs were i.v. injected at a dose of 0.35 mumol kg-1 body weight after incorporation into either Cremophor emulsions or small unilamellar liposomes of dipalmitoyl-phosphatidylcholine (DPPC). Both the nature of the delivery system and the chemical structure of the phthalocyanine were found to affect the behaviour of the GePcs in vivo. Thus, Cremophor-administered GePcs invariably yielded a more prolonged serum retention and a larger association with low-density lipoproteins (LDLs) as compared with the corresponding liposome-delivered phthalocyanines. This led to a greater efficiency and selectivity of tumour targeting. These effects were more pronounced for those GePcs having relatively long alkyl chains (hexyl to decyl) in the axial ligands. Maximal tumour accumulation (0.67 nmol per g of tissue) was found for Ge-Pc(hexyl)2 at 24 h after injection. Consistently, the Ge-Pc(hexyl)2, administered via Cremophor, showed the highest phototherapeutic activity towards MS-2 fibrosarcoma. PMID:7710936

  8. Effect of axial magnetic field on axicon laser-induced electron acceleration

    Science.gov (United States)

    Kant, Niti; Rajput, Jyoti; Giri, Pankaj; Singh, Arvinder

    2016-03-01

    Radially polarized axicon Gaussian laser-induced electron acceleration has been studied under the influence of axial magnetic field. Employing an axicon is a significant method to generate a focused and diffraction free radially polarized laser beam. We have investigated direct electron acceleration in vacuum by employing a relativistic single particle simulation. It is observed that the net electron energy gain from the axicon Gaussian radially polarized laser beam can be enhanced under the influence of time varying axial magnetic field. This additional effect of the magnetic field reveals the fact that multi GeV energy gain can be achieved without the use of petawatt power lasers. Effect of laser initial intensity, initial spot size, initial phase, pulse duration and initial energy are taken into consideration for efficient electron acceleration up to GeV energies.

  9. Effects of operating factors of an axial flow rice combine harvester on grain breakage

    OpenAIRE

    Somchai Chuan-udom; Winit Chinsuwan

    2011-01-01

    The objective of this research was to study the effects of operating factors of an axial flow rice combine harvester ongrain breakage, which comprised rotor speed (RS), louver inclination (LI), grain moisture content (MC), feed rate (FR), andgrain to material other than grain ratio (GM). The study was conducted on Khao Dok Mali 105 and Chainat 1, which are thetwo important rice varieties of Thailand. The results of this study indicate that for both of these varieties, the MC and the RSaffect ...

  10. The Effect of Age, Gender, Refractive Status and Axial Length on the Measurements of Hertel Exophthalmometry

    OpenAIRE

    Karti, Omer; Selver, Ozlem B; Karahan, Eyyup; Zengin, Mehmet O; Uyar, Murat

    2015-01-01

    Purpose : To evaluate the normal distribution of exophthalmometric values in Turkish adult population and the effect of age, gender, refractive status and axial length on globe position. Methods : One hundred and twenty-two males and 114 healthy females with age ranging from 18 to 87 years were included in the study. The study population was recruited from patients presenting to our institution for routine refractive examination. Hertel exophthalmometer was used to measure the degree of ocula...

  11. Chiral extrapolation of nucleon axial charge $g_A$ in effective field theory

    CERN Document Server

    Li, Hongna

    2016-01-01

    The extrapolation of nucleon axial charge $g_A$ is investigated within the framework of heavy baryon chiral effective field theory. The intermediate octet and decuplet baryons are included in the one loop calculation. Finite range regularization is applied to improve the convergence in the quark-mass expansion. The lattice data from three different groups are used for the extrapolation. At physical pion mass, the extrapolated $g_A$ are all smaller than the experimental value.

  12. Effect of blade sweep on inlet flow in axial compressor cascades

    Directory of Open Access Journals (Sweden)

    Chang Hao

    2015-02-01

    Full Text Available This paper presents comparative numerical studies to investigate the effects of blade sweep on inlet flow in axial compressor cascades. A series of swept and straight cascades was modeled in order to obtain a general understanding of the inlet flow field that is induced by sweep. A computational fluid dynamics (CFD package was used to simulate the cascades and obtain the required three-dimensional (3D flow parameters. A circumferentially averaged method was introduced which provided the circumferential fluctuation (CF terms in the momentum equation. A program for data reduction was conducted to obtain a circumferentially averaged flow field. The influences of the inlet flow fields of the cascades were studied and spanwise distributions of each term in the momentum equation were analyzed. The results indicate that blade sweep does affect inlet radial equilibrium. The characteristic of radial fluid transfer is changed and thus influencing the axial velocity distributions. The inlet flow field varies mainly due to the combined effect of the radial pressure gradient and the CF component. The axial velocity varies consistently with the incidence variation induced by the sweep, as observed in the previous literature. In addition, factors that might influence the radial equilibrium such as blade camber angles, solidity and the effect of the distance from the leading edge are also taken into consideration and comparatively analyzed.

  13. Equilibria and kinetics for H-dependent axial ligation of alkyl(aquo) cobaloximes with aromatic and aliphatic N-donor ligands

    Indian Academy of Sciences (India)

    V Sridhar; D Sudarshan Reddy; N Ravikumar Reddy; S Satyanarayana

    2002-02-01

    Equilibria and kinetics of the reaction of bromomethyl(aquo) cobaloxime with histamine, histidine, glycine and ethyl glycine ester and iodomethyl(aquo) cobaloxime with cyanide, imidazole and substituted imidazoles were studied as a function of H at 25°C, 1.0 M ionic strength (KCl) by spectrophotometry technique. The rate of substitution of H2O varies with the of the incoming ligand, thus establishing the existence of nucleophilic participation of the ligand in the transition state. Dissociation kinetic reactions were also studied as a function of H. Binding and kinetic data were interpreted based on the basicity, steric crowd of the entering ligand and HSAB principle. To compare the rate constants of the entering ligands H independent second-order rate constants were calculated.

  14. Equilibria and kinetics for pH-dependent axial ligation of ethylester and methylester(aquo)cobaloximes with aromatic and aliphatic N-donor ligands and a molecular mechanistic study of the Co-C bond

    Indian Academy of Sciences (India)

    J V Madhuri; V Malathi; S Satyanarayana

    2004-03-01

    Equilibrium constants are determined for the reaction of ethylester and methyl ester (aquo) cobaloximes with histamine, histidine, glycine and ethyl glycine ester as a function of pH at 25°C, using spectrophotometric technique. The functional dependence of p on the substitution rate of H2O varies with the p of the incoming ligand, establishing the existence of nucleophilic participation of the ligand in the transition state. This data is interpreted with the help of kinetic data where dissociation kinetic reactions were also studied as a function of pH. Binding and kinetic data were correlated based on the basicity, steric hindrance of the entering ligand and HSAB principle. To compare the rate constants of the entering ligands pH-independent second-order rate constants were calculated. The effect of incoming ligand on Co-C bond is studied using molecular mechanics.

  15. Effective flexural stiffness of slender reinforced concrete columns under axial forces and biaxial bending

    OpenAIRE

    Bonet Senach, José Luís; Romero, Manuel L.; Miguel Sosa, Pedro

    2011-01-01

    Most of the design codes (ACI-318-2008 and Euro Code-2-2004) propose the moment magnifier method in order to take into account the second order effect to design slender reinforced concrete columns. The accuracy of this method depends on the effective flexural stiffness of the column. This paper proposes a new equation to obtain the effective stiffness EI of slender reinforced concrete columns. The expression is valid for any shape of cross-section, subjected to combined axial loads and biaxia...

  16. Simulation Research of Magnetic Constriction Effect and Controlling by Axial Magnetic Field of Vacuum Arc

    Institute of Scientific and Technical Information of China (English)

    王立军; 贾申利; 史宗谦; 荣命哲

    2005-01-01

    Based on magnetohydrodynamic (MHD) model of vacuum arc, the computer simulation of vacuum arc was carried out in this paper. In the MHD model, mass conservation equation,momentum conservation equations, energy conservation equations, generalized ohm's law and Maxwell equation were considered. MHD equations were calculated by numerical method, and the distribution of vacuum arc plasma parameters and current density were obtained. Simulation results showed that the magnetic constriction effect of vacuum arc is primarily caused by the Hall effect. In addition, the inhibition of axial magnetic field (AMF) on constriction of vacuum arc was calculated and analyzed.

  17. Assembling Stabilization of the Rayleigh-Taylor Instability by the Effects of Finite Larmor Radius and Sheared Axial Flow

    Institute of Scientific and Technical Information of China (English)

    Jian Guangde; Huang Lin; Qiu Xiaoming

    2005-01-01

    The assembling stabilizing effect of the finite Larmor radius (FLR) and the sheared axial flow (SAF) on the Rayleigh-Taylor instability in Z-pinch implosions is studied by means of the incompressible finite Larmor radius magnetohydrodynamic (MHD) equations. The finite Larmor radius effects are introduced in the momentum equation with the sheared axial flow through an anisotropic ion stress tensor. In this paper a linear mode equation is derived that is valid for arbitrary kL, where k is the wave number and L is the plasma shell thickness. Numerical solutions are presented. The results indicate that the short-wavelength modes of the RayleighTaylor instability are easily stabilized by the individual effect of the finite Larmor radius or the sheared axial flow. The assembling effects of the finite Larmor radius and sheared axial flow can heavily mitigate the Rayleigh-Taylor instability, and the unstable region can be compressed considerably.

  18. RAPID COMMUNICATION: Effect of noise on accelerometer vector measurement in an ideal tri-axial system

    Science.gov (United States)

    De Freitas, J. M.

    2010-04-01

    A new probability density function which is the direct extension of the Maxwell distribution has been given. The distribution describes the effect of signal plus noise in a tri-axial system of accelerometers. It is shown that an excitation along one axis of a perfectly aligned orthogonal system of accelerometers leads to an apparent angular misalignment in the measured signal when there is random noise in the other two axes. The amplitude distribution with no signal in two axes is the direct analogue of the Rice distribution. The mean and variance of the new distribution are provided.

  19. Recent Advances in Imaging of the Axial Skeleton in Spondyloarthritis for Diagnosis, Assessment of Treatment Effect, and Prognostication

    DEFF Research Database (Denmark)

    Pedersen, Susanne Juhl; Maksymowych, Walter P

    2015-01-01

    In the last few years, many studies have investigated the role of imaging for improved diagnosis, assessment of treatment effects, and determining prognosis in patients with axial spondyloarthritis (SpA). Recent research has primarily focused on the utility of magnetic resonance imaging (MRI) for...... improved diagnosis of patients with non-radiographic axial SpA, and in particular on the classification utility of the MRI criteria as defined by the Assessment of Spondyloarthritis International Society (ASAS). New and more sensitive methods for evaluation of MRI of the sacroiliac joints have been...... developed and have provided insight into effects of treatment on structural progression and the interrelationships between different lesions visualized by MRI. This review gives an overview of the recent advances in imaging of the axial skeleton in axial SpA from a clinical perspective....

  20. Effect of axial groove and resin luting cements on the retention of complete cast metal crowns

    Directory of Open Access Journals (Sweden)

    K Rajkumar

    2009-01-01

    Full Text Available Background : The design of the tooth preparation and the cementing medium are important consid-erations in the retention of crowns and fixed partial dentures. The purpose of this invitro study was to determine the effect of axial groove on the retention of complete cast metal crowns using two resin luting cements. Methods: Forty freshly extracted intact human molar teeth were prepared in their long axis to receive complete cast metal crowns. The specimens were randomly divided into two groups (one control and one study group. An axial groove of uniform size and shape was made on the prepared teeth under the study group. Axial surface area of prepared teeth specimens was measured. Complete cast metal crowns were fabricated for each specimen. Specimens of each group were divided into subgroups of 10 samples and were cemented with two resin luting cements, RelyX Unicem® and Calibra®, re-spectively. The cemented crowns were loaded in tension using a Universal Instron testing machine. The maximal tensile strength was recorded. Data were compared using the Mann-Whitney U test (α=0.05. Results: No significant differences in the tensile stress values were noted between the control (mean: 5.76±0.392 MPa and study (mean: 5.93±0.751 MPa groups cemented with RelyX Unicem. No sig-nificant differences in the tensile stress values were noted between the control (mean: 4.92±0.641 MPa and study (mean: 5.15 ±0.478 MPa groups cemented with Calibra. However, significant dif-ference in the tensile stress values was found between the two resin cements in the control and study groups. Conclusion: Axial groove placed in tooth preparations for resin bonded complete cast metal crowns had no statistically significant effect on retention. The use of (RelyX Unicem® yielded greater reten-tion values when compared to Calibra®.

  1. Investigation of axial blockage position effect in the SFR flow blockage analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Won Pyo; Lee, Kwi Lim; Kang, Seok Hun; Choi, Chi Woong; Jeong, Hae Yong [KAERI, Daejeon (Korea, Republic of)

    2012-10-15

    The sub channels inside a fuel subassembly in SFR{sup s}(Sodium cooled Fast Reactors) may partially be blocked by an ingression of damaged fuel debris or foreign obstacles into the subassembly, due to the geometrically compact design of the core fuel pin arrangement. When the partial blockage occurs, sodium coolant flow would be disturbed in the vicinity of the blockage, and the affected flow could lead to a high local coolant temperature, and subsequently the degradation of the fuel pin should be concerned. Therefore, a partial flow blockage accident must be a safety concern in the SFR design. Analyses were performed for the flow blockage accident postulated in a conceptual design of a 600 MWe demonstration SFR with a TRU core, using the MATRA LMR FB code. In the previous analysis, the blockage was assumed to take place near the axial position with the highest heat flux. The assumption was based on the background that the coolant heat up would be large at that position, because flow would slow down or may be temporarily stagnant in the vicinity of the blockage. In this regard, the present analysis addresses the effect of the axial blockage position on coolant, cladding, and fuel centerline temperatures for blockage sizes larger than 6 sub channels. The interest are how much the axial blockage position would be sensitive for the larger blockage cases, i.e. 24 and 54 sub channel blockage, where a flow recirculation dominantly affects the results Mixture of TRU{sup s}(TRans Uraniums) extracted from both LWR fuel and self recycled SFR fuel.

  2. Effect of axial loads on implant-supported partial fixed prostheses by strain gauge analysis

    Directory of Open Access Journals (Sweden)

    Luis Gustavo Oliveira de Vasconcellos

    2011-12-01

    Full Text Available OBJECTIVES: The present study used strain gauge analysis to perform an in vitro evaluation of the effect of axial loading on 3 elements of implant-supported partial fixed prostheses, varying the type of prosthetic cylinder and the loading points. MATERIAL AND METHODS: Three internal hexagon implants were linearly embedded in a polyurethane block. Microunit abutments were connected to the implants applying a torque of 20 Ncm, and prefabricated Co-Cr cylinders and plastic prosthetic cylinders were screwed onto the abutments, which received standard patterns cast in Co-Cr alloy (n=5. Four strain gauges (SG were bonded onto the surface of the block tangentially to the implants, SG 01 mesially to implant 1, SG 02 and SG 03 mesially and distally to implant 2, respectively, and SG 04 distally to implant 3. Each metallic structure was screwed onto the abutments with a 10 Ncm torque and an axial load of 30 kg was applied at five predetermined points (A, B, C, D, E. The data obtained from the strain gauge analyses were analyzed statistically by RM ANOVA and Tukey's test, with a level of significance of p<0.05. RESULTS: There was a significant difference for the loading point (p=0.0001, with point B generating the smallest microdeformation (239.49 µε and point D the highest (442.77 µε. No significant difference was found for the cylinder type (p=0.748. CONCLUSIONS: It was concluded that the type of cylinder did not affect in the magnitude of microdeformation, but the axial loading location influenced this magnitude.

  3. Stall Characteristics and Tip Clearance Effects in Forward Swept Axial Compressor Rotors

    Institute of Scientific and Technical Information of China (English)

    Ramakrishna PV; Govardhan M

    2009-01-01

    Tilting the blade sections to the flow direction (blade sweep) would increase the operating range of an axial com-pressor due to modifications in the pressure and velocity fields on the suction surface. On the other hand, blade tip gap, though finite, has great influence on the performance of a turbomachine. The present paper investigates the combined effect of these two factors on various flow characteristics in'a low speed axial flow compressor. For this present study, nine computational domains were modeled; three rotor sweep configurations (0°, 20° and 30°) and for three different clearance levels for each rotor. Commercial CFD solver ANSYS CFX 11.0 is used for the simulations. Results indicated that tip chordline sweep is found to improve the stall margin of the compressor by modifying the suction surface boundary layer migration phenomenon. Diffusion Factor (DF) contours showed the severity of stalling with unswept rotor. For the swept rotors, the zones of high probable stall are less severe and they become less in size with increasing sweep. Increment in the tip gap is found to gradually affect the perform-ance of unswept rotor, while the effect is very high for the two swept rotors for the earlier increments. As a mini-mum clearance is unavoidable, swept rotors suffer relatively higher deviation from the idealistic behavior than the unswept rotor due to tip clearance.

  4. Rotor whirl forces induced by the tip clearance effect in axial flow compressors

    Science.gov (United States)

    Ehrich, F.

    1993-10-01

    It is now widely recognized that destabilizing forces, tending to generate forward rotor whirl, are generated in axial flow turbines as a result of the nonuniform torque induced by the nonuniform tip-clearance in a deflected rotor-the so called Thomas/Alford force (Thomas, 1958, and Alford, 1965). It is also recognized that there will be a similar effect in axial flow compressors, but qualitative considerations cannot definitively establish the magnitude or even the direction of the induced whirling forces-that is, if they will tend to forward or backward whirl. Applying a 'parallel compressor' model to simulate the operation of a compressor rotor deflected radially in its clearance, it is possible to derive a quantitative estimate of the proportionality factor which relates the Thomas/Alford force in axial flow compressors (i.e., the tangential force generated by a radial deflection of the rotor) to the torque level in the compressor. The analysis makes use of experimental data from the GE Aircraft Engines Low Speed Research Compressor facility comparing the performance of three different axial flow compressors, each with four stages (typical of a mid-block of an aircraft gas turbine compressor) at two different clearances (expressed as a percent of blade length) - CL/L = 1.4 percent and CL/L = 2.8 percent. It is found that the value of Beta is in the range of + 0.27 to - 0.71 in the vicinity of the stages' nominal operating line and + 0.08 to - 1.25 in the vicinity of the stages' operation at peak efficiency. The value of Beta reaches a level of between - 1.16 and - 3.36 as the compressor is operated near its stalled condition. The final result bears a very strong resemblance to the correlation obtained by improvising a normalization of the experimental data of Vance and Laudadio (1984) and a generic relationship to the analytic results of Colding-Jorgensen (1990).

  5. Effects of operating factors of an axial flow rice combine harvester on grain breakage

    Directory of Open Access Journals (Sweden)

    Somchai Chuan-udom

    2011-04-01

    Full Text Available The objective of this research was to study the effects of operating factors of an axial flow rice combine harvester ongrain breakage, which comprised rotor speed (RS, louver inclination (LI, grain moisture content (MC, feed rate (FR, andgrain to material other than grain ratio (GM. The study was conducted on Khao Dok Mali 105 and Chainat 1, which are thetwo important rice varieties of Thailand. The results of this study indicate that for both of these varieties, the MC and the RSaffect the amount of grain breakage. On the contrary, the LI, the FR, and the GM do not have any effect. The MC was foundto have a greater impact on grain breakage than the RS of Khao Dok Mali 105, whereas the RS has a greater effect onChainat 1 grain than the MC.

  6. Kinetic deuterium isotope effects on ligand migrations in metal hydrides

    International Nuclear Information System (INIS)

    Variable-temperature (VT) 1H and 13C NMR studies of the complexes (μ-X)2Os3(CO)9(μ3-η2-(CH3CH2)2C2) (X = H or D) reveal that alkyne migration over the face of the cluster is directly linked to hydride migrations on the metal core as evidenced by a temperature-independent isotope effect (kHH/kDD = 1.7). In a related study of the VT 13C NMR of (μ-X)2M3(CO)9(μ3-S) (X = H or D; M = Ru, Os) the observation of a kHH/kDD = 1.6 for both the osmium and ruthenium complexes demonstrates that the first stage of carbonyl averaging is brought about by hydride migration and not axial-radial exchange of carbonyl groups, a process that occurs only at higher temperatures. The mechanistic implications of these results are discussed in the context of the reactivity of metal clusters and the dynamic properties of the metal-hydrogen bond

  7. Axial flow effects on robustness of vortical structures about actively deflected wings in flapping flight

    Science.gov (United States)

    Medina, Albert; Kweon, Jihoon; Choi, Haecheon; Eldredge, Jeff D.

    2012-11-01

    Flapping wing flight has garnered much attention in the past decade driven by our desire to understand capabilities observed in nature and to develop agile small-scale aerial vehicles. Nature has demonstrated the breadth of maneuverability achievable by flapping wing flight. However, despite recent advances the role of wing flexibility remains poorly understood. In an effort to develop a deeper understanding of wing deflection effects and to explore novel approaches to increasing leading-edge vortex robustness, this three-dimensional computational study explores the aerodynamics of low aspect ratio plates, in hovering kinematics, with isolated flexion lines undergoing prescribed deflection. Major flexion lines, recognized as the primary avenue for deflection in biological fliers, are isolated here in two distinct configurations, resulting in deflection about the wing root and the wing tip, respectively. Of interest is the interaction between axial flow along the span and the vortical structures about the wing. It is proposed that the modes of deflection explored may provide a means of axial flow control for favorably promoting LEV robustness over a broad range of flapping conditions, and provide insight into the nature of flexibility in flapping wing flight. National Science Foundation, National Research Foundation of Korea.

  8. Trans-influence and axial interactions in low spin, tetragonal cobalt(II) complexes containing macrocyclic and/or cyano ligands. Pulse radiolytic studies in fluid solution, electron paramagnetic resonance spectra at 77 k, and single-crystal x-ray structures

    International Nuclear Information System (INIS)

    Investigations of the weak interactions between low spin cobalt(II) species and their axial ligands have been performed. X-ray structural studies of six-coordinate Co(N4)(OH2)22+ and Co(N4)(ClO4)2 complexes, where (N4) is an equatorially coordinated tetradentate macrocyclic ligand, reveal that the axial Co--ligand bond lengths are 0.3 to 0.5 A longer per bond than are the equatorial Co--ligand bond lengths. By means of the pulse radiolytic reductions of the corresponding cobalt(III) complexes, low spin cobalt(II) species of the types Co/sup II/(N4)L2 (L = NH3, NO2-, CN-) and Co/sup II/(CN)5X (X = Cl, CN) have been generated, and the rates of ligand exchange with water in the reduced species have been determined by a kinetic conductivity method. All the cobalt(II) species have been found to be very labile in two (axial) coordination positions, with an appreciable range of rate constants (k greater than or equal to 103 s-1) which depend on both the equatorial and the axial ligands. Electron paramagnetic resonance spectra have provided evidence for interactions with either one or two axial ligands (at 77 K) but on the whole have not provided definitive criteria regarding the coordination number of low spin cobalt(II) species in fluid solution. Comparison of the results of this and other studies suggests a strong trans influence in the axial ligand interactions of low spin cobalt(II) complexes. A simple three-center bonding model has been used to describe the weak axial interactions. This model also provides a convenient basis for interpreting the absorption spectrum of a Co/sup II/(N4)CN transient generated in the pulse radiolysis studies. It is inferred that the synergistic trans-influence deduced for low spin cobalt(II) species may be a significant factor in inner sphere electron transfer reactions

  9. Effect of gyroviscosity on the small axial wavelength internal kink instability in the Z-pinch

    International Nuclear Information System (INIS)

    The effect of ion gyroviscosity on the stability of m=1 small axial wavelength kinks in a z-pinch with purely poloidal magnetic field is investigated by normal mode methods. We use the Incompressible FLR MHD model; a collisionless fluid model introduced to include Finite Larmor Radius effects. For vanishing Larmor radius, a stability criterion which coincides with that of ideal MHD is found; the Kadomtsev criterion 2rdp/dr+m/sp2/B/sp2///my//sb0/> or = 0. This criterion predicts instability unless the current density becomes singular at the centre of the pinch. When the Larmor radius terms of the ion pressure tensor are included, we find that marginally unstable (ideal) modes are stabilized. (authors)

  10. Understanding the shape effect on the plasmonic response of small ligand coated nanoparticles

    Science.gov (United States)

    Chen, Xing; Jensen, Lasse

    2016-07-01

    The plasmonic properties of metallic nanoparticles typically depend strongly on their shapes and local environment. However, not much is known about the shape effects on the plasmonic response in small metallic nanoparticles when quantum size effects become important. In this work, we use atomistic electrodynamics models incorporated with quantum size effects to study the optical properties of both bare and ligand coated Ag nanoparticles in different shapes. Using classical electrodynamics, we find that the plasmonic response of bare metallic nanoparticles depends strongly on the morphology of the nanoparticles due to the presence of higher-order plasmon modes. By including quantum size effects in the simulations, we find a significant blue-shift of the dipole plasmon as well as the smearing-out of the multipole plasmon modes, and both lead to a weak shape dependence. The ligand effects on the nanoparticles cause a significant red-shift of the plasmon resonance arising from the reduction of the conductivity of the Ag atoms where the ligands bind. In contrast to the bare nanoparticles, we find several higher-order plasmon modes in the ligand coated nanoparticles, that are likely caused by the weak electron spill-out effect and the symmetry breaking at the surface in the presence of the ligands. Furthermore, we show that the ligand layer strongly modify the near-field distribution due to the screening of the ligands. This work highlights the importance of quantum size and ligand effects on the optical properties of small metallic nanoparticles.

  11. Second harmonic generation of off axial vortex beam in the case of walk-off effect

    Science.gov (United States)

    Chen, Shunyi; Ding, Panfeng; Pu, Jixiong

    2016-07-01

    Process of off axial vortex beam propagating in negative uniaxial crystal is investigated in this work. Firstly, we get the formulae of the normalized electric field and calculate the location of vortices for second harmonic beam in two type of phase matching. Then, numerical analysis verifies that the intensity distribution and location of vortices of the first order original vortex beam depend on the walk-off angle and off axial magnitude. It is shown that, in type I phase matching, the distribution of vortices is symmetrical about the horizontal axis, the separation distance increases as the off axial magnitude increases or the off axial magnitude deceases. However, in type II phase matching, the vortices are symmetrical along with some vertical axis, and increase of the walk-off angle or off axial magnitude leads to larger separation distance. Finally, the case of high order original off axial vortex beam is also investigated.

  12. Effect of Deformation Condition on Axial CompressivePrecision Forming Process of Tube with Curling Die

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of the deformation condition on the axial compressive precision forming process of tube with curling die was investigated by using a rigid-plastic FEM. The results show that the forming accuracy depends mainly on geometric condition rρ/d0, little on tube material properties and friction condition; the relative gap Δ/2rρ of double-walled tubes obtained decreases with increasing rρ/d0, and there is a parameter k for a given t0/d0 or rρ/t0, when rρ,/d0>k, Δ/2rρ<1,otherwise Δ/2rρ>1.

  13. The effect of non-uniform damping on flutter in axial flow and energy harvesting strategies

    CERN Document Server

    Singh, Kiran; de Langre, Emmanuel

    2012-01-01

    The problem of energy harvesting from flutter instabilities in flexible slender structures in axial flows is considered. In a recent study, we used a reduced order theoretical model of such a system to demonstrate the feasibility for harvesting energy from these structures. Following this preliminary study, we now consider a continuous fluid-structure system. Energy harvesting is modelled as strain-based damping and the slender structure under investigation lies in a moderate fluid loading range, for which {the flexible structure} may be destabilised by damping. The key goal of this work is to {analyse the effect of damping distribution and intensity on the amount of energy harvested by the system}. The numerical results {indeed} suggest that non-uniform damping distributions may significantly improve the power harvesting capacity of the system. For low damping levels, clustered dampers at the position of peak curvature are shown to be optimal. Conversely for higher damping, harvesters distributed over the wh...

  14. The Effect of Surface Roughness on Thermodynamic Performance Parameter of Axial Flow Compressor

    Directory of Open Access Journals (Sweden)

    Huadong Yang

    2013-05-01

    Full Text Available In axial flow compressor, blade surface roughness is affected by many failure modes such as fouling, erosion, corrosion and foreign object damage. But with development of filter performance, particles with diameter larger than 2&mum cannot enter into compressor, so fouling is the most important influence factor which results in the variation of surface roughness. This study respectively discusses the effect of surface roughness on performance parameter when surface roughness is constant and linearly distributed. Finally, based on experiment result, reverse design method is applied to reconstruct the fouled compressor by combining laser triangulation sensor with compressor fouling test rig and then reconstructed solid model is imported into ANSYS CFX to simulate flow field. Result shows that the increase of surface roughness results in the decrease of pressure ratio, mass flow and efficiency.

  15. The effects of compressive sensing on extracted features from tri-axial swallowing accelerometry signals

    Science.gov (United States)

    Sejdić, Ervin; Movahedi, Faezeh; Zhang, Zhenwei; Kurosu, Atsuko; Coyle, James L.

    2016-05-01

    Acquiring swallowing accelerometry signals using a comprehensive sensing scheme may be a desirable approach for monitoring swallowing safety for longer periods of time. However, it needs to be insured that signal characteristics can be recovered accurately from compressed samples. In this paper, we considered this issue by examining the effects of the number of acquired compressed samples on the calculated swallowing accelerometry signal features. We used tri-axial swallowing accelerometry signals acquired from seventeen stroke patients (106 swallows in total). From acquired signals, we extracted typically considered signal features from time, frequency and time-frequency domains. Next, we compared these features from the original signals (sampled using traditional sampling schemes) and compressively sampled signals. Our results have shown we can obtain accurate estimates of signal features even by using only a third of original samples.

  16. Effect of Control Blade History, and Axial Coolant Density and Burnup Profiles on BWR Burnup Credit

    Energy Technology Data Exchange (ETDEWEB)

    Ade, Brian J [ORNL; Marshall, William BJ J [ORNL; Martinez-Gonzalez, Jesus S [ORNL

    2015-05-01

    Oak Ridge National Laboratory (ORNL) and the US Nuclear Regulatory Commission (NRC) have initiated a multiyear project to investigate the application of burnup credit (BUC) for boiling water reactor (BWR) fuel in storage and transportation systems (often referred to as casks) and spent fuel pools (SFPs). This work is divided into two main phases. The first phase investigated the applicability of peak reactivity methods currently used in SFPs to transportation and storage casks and the validation of reactivity calculations and spent fuel compositions within these methods. The second phase focuses on extending BUC beyond peak reactivity. This paper documents the analysis of the effects of control blade insertion history, and moderator density and burnup axial profiles for extended BWR BUC.

  17. Theoretical analysis of the effect of water and ethanol injection on axial compressor instabilities

    International Nuclear Information System (INIS)

    Two types of instabilities that occur in compression systems rotating stall and surge have an adverse effect on the compressor performance. Several techniques have been explored to minimize the effect of these instabilities. It has been observed that injection of a liquid into the compressor not only improves thermodynamic efficiencies but also results in stabilizing the system. Therefore, water and ethanol injection has been investigated as an effective tool for controlling these compressor instabilities. In the present paper a modified Moore-Greitzer model has been proposed for wet compression-based system using water and ethanol. Under this work the effect of injection of water (1) at various stages of compressor, (2) at different altitudes and (3) by varying amounts has also been presented. The effect of various parameters on wet compression such as (a) Optimum stage for liquid injection (b) Optimum amount of liquid injection and (c) Effect of altitude on liquid injection is also examined in the present work which shows that the liquid injection helps in improving the performance of compression systems in terms of increase in the stall margin and pressure rise coefficient. - Highlights: → We model the effect of liquid injection on the performance of axial flow compressors. → The basic Moore-Grietzer's model has been appropriately modified. → Injection of liquid in the later stages of the compressor resulted in improved stall margin and pressure rise. → Use of ethanol was found to give better performance than water.

  18. The effect of body position and axial load on spinal canal morphology: an MRI study of central spinal stenosis

    DEFF Research Database (Denmark)

    Madsen, Rasmus; Jensen, Tue Secher; Pope, Malcolm;

    2007-01-01

    STUDY DESIGN: A method comparison study. OBJECTIVE: To investigate the effect of body position and axial load of the lumbar spine on disc height, lumbar lordosis, and dural sac cross-sectional area (DCSA). SUMMARY OF BACKGROUND DATA.: The effects of flexion and extension on spinal canal diameters...... position with applied axial loading. Disc height, lumbar lordosis, and DCSA were measured and the different positions were compared. RESULTS: In section 1, the only significant difference between positions was a reduced lumbar lordosis during standing when compared with lying (P = 0.04), most probably a...... and DCSA are well documented. However, the effects of axial loading, achieved by upright standing or by a compression device, are still unclear. METHODS: Patients with lumbar spinal stenosis were examined in 2 separate studies, including 16 and 20 patients, respectively. In section 1, magnetic...

  19. Architecture effects on multivalent interactions by polypeptide-based multivalent ligands

    Science.gov (United States)

    Liu, Shuang

    Multivalent interactions are characterized by the simultaneous binding between multiple ligands and multiple binding sites, either in solutions or at interfaces. In biological systems, most multivalent interactions occur between protein receptors and carbohydrate ligands through hydrogen-bonding and hydrophobic interactions. Compared with weak affinity binding between one ligand and one binding site, i.e. monovalent interaction, multivalent interactioins provide greater avidity and specificity, and therefore play unique roles in a broad range of biological activities. Moreover, the studies of multivalent interactions are also essential for producing effective inhibitors and effectors of biological processes that could have important therapeutic applications. Synthetic multivalent ligands have been designed to mimic the biological functions of natural multivalent interactions, and various types of scaffolds have been used to display multiple ligands, including small molecules, linear polymers, dendrimers, nanoparticle surfaces, monolayer surfaces and liposomes. Studies have shown that multivalent interactions can be highly affected by various architectural parameters of these multivalent ligands, including ligand identities, valencies, spacing, ligand densities, nature of linker arms, scaffold length and scaffold conformation. Most of these multivalent ligands are chemically synthesized and have limitations of controlling over sequence and conformation, which is a barrier for mimicking ordered and controlled natural biological systems. Therefore, multivalent ligands with precisely controlled architecture are required for improved structure-function relationship studies. Protein engineering methods with subsequent chemical coupling of ligands provide significant advantages of controlling over backbone conformation and functional group placement, and therefore have been used to synthesize recombinant protein-based materials with desired properties similar to natural

  20. Steroid receptors and their ligands: Effects on male gamete functions

    Energy Technology Data Exchange (ETDEWEB)

    Aquila, Saveria; De Amicis, Francesca, E-mail: francesca.deamicis@unical.it

    2014-11-01

    In recent years a new picture of human sperm biology is emerging. It is now widely recognized that sperm contain nuclear encoded mRNA, mitochondrial encoded RNA and different transcription factors including steroid receptors, while in the past sperm were considered incapable of transcription and translation. One of the main targets of steroid hormones and their receptors is reproductive function. Expression studies on Progesterone Receptor, estrogen receptor, androgen receptor and their specific ligands, demonstrate the presence of these systems in mature spermatozoa as surface but also as nuclear conventional receptors, suggesting that both systemic and local steroid hormones, through sperm receptors, may influence male reproduction. However, the relationship between the signaling events modulated by steroid hormones and sperm fertilization potential as well as the possible involvement of the specific receptors are still controversial issues. The main line of this review highlights the current research in human sperm biology examining new molecular systems of response to the hormones as well as specific regulatory pathways controlling sperm cell fate and biological functions. Most significant studies regarding the identification of steroid receptors are reported and the mechanistic insights relative to signaling pathways, together with the change in sperm metabolism energy influenced by steroid hormones are discussed.The reviewed evidences suggest important effects of Progesterone, Estrogen and Testosterone and their receptors on spermatozoa and implicate the involvement of both systemic and local steroid action in the regulation of male fertility potential. - Highlights: • One of the main targets of steroid hormones and their receptors is reproductive function. • Pg/PR co-work to stimulate enzymatic activities to sustain a capacitation process. • E2/ERs regulate sperm motility, capacitation and acrosome reaction and act as survival factors. • Androgens

  1. Steroid receptors and their ligands: Effects on male gamete functions

    International Nuclear Information System (INIS)

    In recent years a new picture of human sperm biology is emerging. It is now widely recognized that sperm contain nuclear encoded mRNA, mitochondrial encoded RNA and different transcription factors including steroid receptors, while in the past sperm were considered incapable of transcription and translation. One of the main targets of steroid hormones and their receptors is reproductive function. Expression studies on Progesterone Receptor, estrogen receptor, androgen receptor and their specific ligands, demonstrate the presence of these systems in mature spermatozoa as surface but also as nuclear conventional receptors, suggesting that both systemic and local steroid hormones, through sperm receptors, may influence male reproduction. However, the relationship between the signaling events modulated by steroid hormones and sperm fertilization potential as well as the possible involvement of the specific receptors are still controversial issues. The main line of this review highlights the current research in human sperm biology examining new molecular systems of response to the hormones as well as specific regulatory pathways controlling sperm cell fate and biological functions. Most significant studies regarding the identification of steroid receptors are reported and the mechanistic insights relative to signaling pathways, together with the change in sperm metabolism energy influenced by steroid hormones are discussed.The reviewed evidences suggest important effects of Progesterone, Estrogen and Testosterone and their receptors on spermatozoa and implicate the involvement of both systemic and local steroid action in the regulation of male fertility potential. - Highlights: • One of the main targets of steroid hormones and their receptors is reproductive function. • Pg/PR co-work to stimulate enzymatic activities to sustain a capacitation process. • E2/ERs regulate sperm motility, capacitation and acrosome reaction and act as survival factors. • Androgens

  2. Differential effects of EGFR ligands on endocytic sorting of the receptor

    DEFF Research Database (Denmark)

    Roepstorff, Kirstine; Grandal, Michael Vibo; Henriksen, Lasse;

    2009-01-01

    signalling and is a more potent mitogen than EGF. In addition to EGF and TGF-alpha, five EGFR ligands have been identified. Although many of these ligands are upregulated in cancers, very little is known about their effect on EGFR trafficking. We have compared the effect of six different ligands on endocytic...... trafficking of EGFR. We find that, whereas they all stimulate receptor internalization, they have very diverse effects on endocytic sorting. Heparin-binding EGF-like growth factor and Betacellulin target all EGFRs for lysosomal degradation. In contrast, TGF-alpha and epiregulin lead to complete receptor...

  3. FFT Analysis on Coupling Effect of Axial and Torsional Vibrations in Circular Cross Section Beam of Steam Turbine Generators

    Directory of Open Access Journals (Sweden)

    Xiang Xu

    2013-09-01

    Full Text Available This paper presents a novel method to nonlinearly investigate the dynamics of the coupled axial and torsional vibrations in the circular cross section beam of the steam turbine generator using the FFT analysis. Firstly, the coupled axial and torsional vibrations of a beam are proved by equivalent law of shearing stress and different boundary conditions. Then, a nonlinear mathematical model of the coupled axial and torsional vibrations is established by the Galerkin method. Lastly, the fast Fourier transform (FFT is employed to investigate the coupled effect of the beam vibration. A practical calculation example is calculated numerically and the coupled mechanism of the beam’s axial and torsional vibrations is analyzed in detail. The analysis results show that the frequencies of the coupled response would be existed in some special orders and the coupled response frequencies are smaller than the single vibration. Since for the first time the coupled mechanism of the beam’s axial and torsional vibrations is theoretically analyzed, the findings in this work may provide directive reference for practical engineering problems in design of steam turbine generators.

  4. Effect of Axial Pre-Compression on Lateral Performance of Masonry Under Cyclic Loading

    Directory of Open Access Journals (Sweden)

    Syed HassanFarooq

    2011-10-01

    Full Text Available Strengthening of masonry against seismic events is very essential and getting maximum attention of researchers around the globe. An extensive experimental program was carried out to study the in-plane lateral performance of un-reinforced masonry, strengthened and retrofitted masonry wall panels under lateral cyclic loading. Twenty tests were carried out; four tests under monotonic lateral loading, twelve tests under static cyclic loading and four tests under pure compression. The test results were analyzed in five groups and this paper presents the analysis of group 4, which deals with effect of axial pre-compression on masonry seismic performance. Three single leaf panels with aspect ratio of 0.67 having size 1.65x1.1m were constructed using same material and workmanship. All the three un-reinforced walls were tested under 0, 0.5 and 1.0MPa vertical pre-compression and displacement controlled static cyclic loading. The wall tested under 0.5MPa pre-compression was reference specimen. The key parameters studied were hysterics behavior, peak lateral load, ultimate lateral displacement, energy dissipation, ductility, response factor and damping ratio. It was observed that level of axial pre-compression has significant effect on lateral capacity, failure mode and performance of masonry. In case of zero pre-compression the lateral capacity was very less and wall went into rocking failure at early stages of loading. Increase in pre-compression to 1.0MPa enhanced the lateral capacity by a factor of 1.92 times. After analysis of test results, it is found that pre-compression has significant effect on lateral capacity, failure mode and performance of masonry. In case of zero pre-compression the lateral capacity was very less and wall went into rocking failure at early stages of loading. Increase in pre-compression to 1.0MPa enhanced the lateral capacity by a factor of 1.92 times. After analysis of test results, it is found that pre-compression has very

  5. Differential effects of TRPV1 receptor ligands against nicotine-induced depression-like behaviors

    OpenAIRE

    2011-01-01

    Background The contributions of brain cannabinoid (CB) receptors, typically CB1 (CB type 1) receptors, to the behavioral effects of nicotine (NC) have been reported to involve brain transient receptor potential vanilloid 1 (TRPV1) receptors, and the activation of candidate endogenous TRPV1 ligands is expected to be therapeutically effective. In the present study, the effects of TRPV1 ligands with or without affinity for CB1 receptors were examined on NC-induced depression-like behavioral alte...

  6. Application of effective potential to investigation of two-dimensional lenses-mirror electrostatic systems with curvilinear axial trajectories

    CERN Document Server

    Bimurzaev, S B

    2002-01-01

    Movement equations of two-dimensional electron mirrors with curvilinear axial trajectory have been reduced to form similar for such mirrors with rectilinear axial trajectory by introduction of effective potentials. On the basis of this analogy the general expressions to within sizes of the second order trifle, describing time-of-flight and equation of a trajectory in an average plane in two-dimensional electronic mirrors with curvilinear by an axial trajectory are received. The space and time-of-flight focusing conditions and also conditions of elimination of separate kind aberration are determined. By numerical accounts the condition stigmatic focusing elimination spherical aberration of the second order in two and three-electrode mirror electrostatic power analyser are found which electrodes serve pairs of parallel plates divided by direct cracks. The time-of-flight focusing condition up to the second order inclusive for a three-electrode flat mirror are found also. (author)

  7. Sensitivity analysis of power depression and axial power factor effect on fuel pin to temperature and related properties distribution

    International Nuclear Information System (INIS)

    The presented paper is a preliminary step to evaluate the effect of radial and axial distribution of power generation on thermal analysis of whole fuel pin model with large L/D ratio. The model takes into account both radial and axial distribution of power generation due to power depression and core geometry, temperature and microstructure dependent on thermal conductivity. The microstructure distribution and the gap conductance for typical steady-state situation are given for the sensitivity analysis. The temperature and thermal conductivity distribution along the radial and axial directions obtained by different power distribution is used to indicate the sensitivity of power depression and power factor on thermal aspect. The evaluation is made for one step of incremental time and steady state approach is used. The analysis has been performed using a finite element-finite difference model. The result for typical reactor fuel shows that the sensitivity is too important to be omitted in thermal model

  8. Effects of axial load and structural damping on wave propagation in periodic Timoshenko beams on elastic foundations under moving loads

    Science.gov (United States)

    Ding, Lan; Zhu, Hong-Ping; Wu, Li

    2016-07-01

    The propagation and attenuation properties of waves in ordered and disordered periodic composite Timoshenko beams, which consider the effects of axial static load and structural damping, resting on elastic foundations are studied when the system is subjected to moving loads of constant amplitude with a constant velocity. The transfer matrix methodology is adopted to formulate the model in a reference coordinate system moving with the load. The localization factor is calculated to determine the wave velocity pass bands and stop bands. The interactions between the static axial load and moving load, structural damping and disorder on the bands are analyzed.

  9. BWR AXIAL PROFILE

    International Nuclear Information System (INIS)

    The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips. Thus, accounting for axially varying burnup in criticality analyses is also referred to as accounting for the ''end effect'' reactivity. The magnitude of the reactivity change due to ''end effect'' is dependent on the initial assembly enrichment, the assembly average burnup, and the particular axial profile characterizing the burnup distribution. The set of bounding axial profiles should incorporate multiple BWR core designs and provide statistical confidence (95 percent confidence that 95 percent of the population is bound by the profile) that end nodes are conservatively represented. The profiles should also conserve the overall burnup of the fuel assembly. More background on BWR axial profiles is provided in Attachment I

  10. BWR AXIAL PROFILE

    Energy Technology Data Exchange (ETDEWEB)

    J. Huffer

    2004-09-28

    The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips. Thus, accounting for axially varying burnup in criticality analyses is also referred to as accounting for the ''end effect'' reactivity. The magnitude of the reactivity change due to ''end effect'' is dependent on the initial assembly enrichment, the assembly average burnup, and the particular axial profile characterizing the burnup distribution. The set of bounding axial profiles should incorporate multiple BWR core designs and provide statistical confidence (95 percent confidence that 95 percent of the population is bound by the profile) that end nodes are conservatively represented. The profiles should also conserve the overall burnup of the fuel assembly. More background on BWR axial profiles is provided in Attachment I.

  11. Synthesis of silver nanoparticles: Effects of anionic ligands on formation and catalytic activity

    International Nuclear Information System (INIS)

    We report a facile method to synthesize water soluble Ag nanoparticles (NPs) using various anionic complexing ligands as reducing as well as stabilizing agents. The formation of the particles depends on the initial molar ratio of ligands to silver nitrate. Also, the alkaline condition of preparative solution is found to be necessary for the formation of Ag NPs. It has been important to mention here that the temperature of the reaction mixture plays an important factor on the rate of formation of the particles. The particles were characterized by UV–vis spectroscopy, transmission electron microscopy, dynamic light scattering and X-ray diffraction techniques. The formed particles were found to be stable for more than a month. Zeta potential measurements suggest that the negative potential created by the adsorbed complexing ligands contribute to the stability of the Ag NPs suspensions. The effect of the ligands on the formation, stability and catalytic activity of the Ag NPs was evaluated. The obtained Ag NPs exhibit a good catalytic activity toward reduction of o-nitroaniline. The results reveal that the presence of more coordination sites in the ligands affects the catalytic activity of the particles. - Highlights: • Formation of Ag nanoparticles using anionic ligands as reducing agents and stabilizers. • Number of –COOH groups in the ligands affect the formation of particles. • The formed nanoparticles show good catalytic activity. • Number of –COOH groups in the ligands affect the catalytic activity of the particles

  12. The effect of introduction of axial cineangiography and echocardiography on contrast and radiation doses during cardiac catheterisation

    International Nuclear Information System (INIS)

    The effects of routine preliminary echocardiography and adoption of axial cine angiography in a Paediatric Cardiac Investigation Centre were assessed in relation to contrast volume, fluoroscopy time and radiation dose. The results showed a significant increase in radiation dose with some reduction in fluoroscopy time in neonates and some increase in contrast volume used in infants

  13. Effects of decreased muscle activity on developing axial musculature in nic b107 mutant zebrafish (Danio rerio)

    NARCIS (Netherlands)

    Meulen, van der T.; Schipper, H.; Leeuwen, van J.L.; Kranenbarg, S.

    2005-01-01

    The present paper discusses the effects of decreased muscle activity (DMA) on embryonic development in the zebrafish. Wild-type zebrafish embryos become mobile around 18 h post-fertilisation, long before the axial musculature is fully differentiated. As a model for DMA, the nicb107 mutant was used.

  14. Vacuum effects in magnetic field with with account for fermion anomalous magnetic moment and axial-vector interaction

    Science.gov (United States)

    Bubnov, Andrey; Gubina, Nadezda; Zhukovsky, Vladimir

    2016-05-01

    We study vacuum polarization effects in the model of Dirac fermions with additional interaction of an anomalous magnetic moment with an external magnetic field and fermion interaction with an axial-vector condensate. The proper time method is used to calculate the one-loop vacuum corrections with consideration for different configurations of the characteristic parameters of these interactions.

  15. Effect of Axial Force on the Performance of Micromachined Vibratory Rate Gyroscopes

    OpenAIRE

    Zhengyi Niu; Xu Zhang; Peitao Dong; Zhihua Chen; Zhanqiang Hou; Dingbang Xiao; Xuezhong Wu

    2010-01-01

    It is reported in the published literature that the resonant frequency of a silicon micromachined gyroscope decreases linearly with increasing temperature. However, when the axial force is considerable, the resonant frequency might increase as the temperature increases. The axial force is mainly induced by thermal stress due to the mismatch between the thermal expansion coefficients of the structure and substrate. In this paper, two types of micromachined suspended vibratory gyroscopes with s...

  16. Effect of the diaminocyclohexane carrier ligand on platinum adduct formation, repair, and lethality

    International Nuclear Information System (INIS)

    Platinum compounds with the diaminocyclohexane (dach) carrier ligand are of particular interest because cell lines that have developed resistance to platinum compounds in general often retain sensitivity to dach-platinum compounds, suggesting that the dach carrier ligand affects the formation, repair, or lethality of platinum-DNA adducts. The effect of the dach ligand on platinum adduct formation was assessed by using the (HaeIII-HindIII)146 fragment of pBR322 treated to give equal amounts of dach- or ethylene-diamine-platinum adducts. The sites of adduct formation were mapped by digestion with Escherichia coli ABC excinuclease. There were no significant effects of the dach carrier ligand on the types or sites of platinum adduct formation. The effect of the dach ligand on platinum adduct repair was determined by using synthetic oligomers designed to have single, specific platinum adducts. These data suggest that if the carrier ligand has any effect on the repair of platinum adducts, it is more likely to exert that effect on the repair of platinum monoadducts or GNG diadducts rather than on the more abundant AG or GG diadducts. [14C]Thiourea incorporation was used to quantitate the rate of monoadduct to diadduct conversion. Finally, the effect of the dach ligand on platinum adduct lethality was assessed by determining the effect of dach- and en-platinum adducts on the transformation efficiency of pBR322 into a repair-deficient (recA- uvrA-) strain of E. coli. These data suggest that the dach carrier ligand can significantly affect the ability of platinum-DNA adducts to block essential processes such as replication and transcription

  17. Effect of Axial Velocity Density Ratio on the Performance of a Controlled Diffusion Airfoil Compressor Cascade

    Science.gov (United States)

    Senthil Kumaran, R.; Kamble, Sachin; Swamy, K. M. M.; Nagpurwala, Q. H.; Bhat, Ananthesha

    2015-12-01

    Axial Velocity Density Ratio (AVDR) is an important parameter to check the two-dimensionality of cascade flows. It can have significant influence on the cascade performance and the secondary flow structure. In the present study, the effect of AVDR has been investigated on a highly loaded Controlled Diffusion airfoil compressor cascade. Detailed 3D Computational Fluid Dynamics (CFD) studies were carried out with the cascade at five different AVDRs. Key aerodynamic performance parameters and flow structure through the cascade were analyzed in detail. CFD results of one AVDR were validated with the experimental cascade test data and were seen to be in good agreement. Loss characteristics of the cascade varied significantly with change in AVDR. Increase in AVDR postponed the point of separation on the suction surface, produced thinner boundary layers and caused substantial drop in the pressure loss coefficient. Strong end wall vortices were noticed at AVDR of 1.177. At higher AVDRs, the flow was well guided even close to the end wall and the secondary flows diminished. The loading initially improved with increase in AVDR. Beyond a certain limit, further increase in AVDR offered no improvements to the loading but rather resulted in drop in diffusion and deviation.

  18. The effect of calibrated nonlocal constant on the modal parameters and stability of axially compressed CNTs

    Science.gov (United States)

    Fathi, Reza; Lotfan, Saeed

    2016-05-01

    Nowadays investigating the vibration behavior of carbon nanotubes (CNTs) has drawn considerable attention due to the superior mechanical properties of the CNTs. One of the powerful theoretical methods to study the vibration behavior of CNTs is implementing the nonlocal theory. Most of studies on the vibration behavior of CNTs have assumed a fixed value for small scale parameter for all vibration modes, however, this value is mode-dependent. Therefore, in this paper, the small scale parameter is calibrated for a single-walled carbon nanotube (SWCNT) with respect to each vibration mode. For this propose, the governing equation of motion based on the nonlocal beam theory is extracted by applying the Hamilton's principle. Then, by using the power series method, an eigenvalue problem is defined to derive the calibrated value of small scale constant and nonlocal mode shapes of the CNT. By using the expansion theory, the equation of motion is discretized, and the effect of nonlocality on the modal parameters and stability of the CNT under compressive force is investigated. Finally, the possibility of estimating nonlocal parameter based on simulated frequency domain response of the system by using modal analysis methods is studied. The results show that the calibration of small scale constant is important and the critical axial force is highly sensitive to this value.

  19. Effect of axial finiteness on electron heating in low-frequency inductively coupled plasmas

    International Nuclear Information System (INIS)

    Total power absorption inside the plasma (by taking the thermal motion of the electrons into account) has been calculated using different inductively coupled plasma models. The comparison shows that in the low-frequency region the results of the semi-infinite plasma models are different from those of the finite-length plasma models. The semi-infinite plasma models show net reduction of heating in the low-frequency region, due to thermal motion of the electrons from inside the skin region to outside the skin region. The finite-length plasma models on the other hand (due to change in the skin depth owing to the boundary condition of E=0 at z=L, and reflection of electrons from the plasma boundary) show that the decrease in heating due to the motion of the electrons from inside the skin depth to outside the skin depth is recovered by the reflection of the electrons from the plasma boundary. Hence, it is concluded that the results of the semi-infinite plasma models presented by Tyshetskiy et al. [Phys Rev. Lett. 90, 255002 (2003)] can be misleading (in the low-frequency region), since they overlooked the effect of axial finiteness of the plasma

  20. Effect of axial vibration on free surface flows in cylindrical liquid

    Institute of Scientific and Technical Information of China (English)

    Pan Xiu-Hong; Jin Wei-Qing

    2005-01-01

    The influence of axial vibration on free surface flows in an open cylindrical container was studied by optical in situ observation method under isothermal conditions. This ground-based experiment was performed on an electromagnetic vibrator with oscillatory frequency of 100Hz. Water-glycerol mixture was chosen as the model liquid. Results showed that small amplitude (< 100μm) could generate a new type of steady streaming flows on a free surface, which were mainly driven by the combination of propagating surface wave and Stokes layer effect. The steady flow manifested various patterns according to the vibration amplitude level. Higher amplitude made steady flow periodical or turbulent,which could be characterized by the critical vibrational dimensionless Reynolds number (Nre)c. The calculated value of (Nre)c was of the magnitude of 10-2 - 10-1. In addition, surface streaming velocities were measured by the particle scattering technique. It was found that the velocity increased parabolically with vibration amplitude and decreased with viscosity for a fixed flow pattern.

  1. Effect of void dependent reactivity modeling bias on BWR axial power tilt - 256

    International Nuclear Information System (INIS)

    Inspired by a Pennsylvania State University study reported in the PHYSOR08 conference related to BWR axial power tilt, an investigation is made as to if there could be any intrinsic deficiency in the conventional nodal diffusion theory leading to a tilt in BWR axial power prediction. It is found that the two-group nodal diffusion theory itself does not cause axial power tilt compared to multigroup deterministic 3D transport calculation. However, the usual practice of flat source approximation in 2D lattice codes based on the Collision Probability (CP) method or the Method of Characteristics (MOC) can cause a void dependent reactivity bias when used to generate the node homogenized cross-sections, if the same geometry meshing modeling is used for all the axial sections over which the void fraction varies severely. The reactivity bias can be removed by using lattice code models based on SN method or MOC method with linear instead of flat source approximation. In absence of the void dependent reactivity bias, there is no axial power tilt between two-group nodal diffusion calculation and multi-group deterministic 3D transport calculation. Therefore there is no intrinsic deficiency in the nodal diffusion theory that causes BWR axial power tilt. But one has to be careful with using the flat source approximation and the generic-meshing modeling in generating homogenized nodal diffusion cross-sections for high void cases. As for any possible axial power tilt between multi-group deterministic 3D transport calculation and continuous energy Monte Carlo 3D simulation, that would be a different issue. (authors)

  2. Installation effects on the tonal noise generated by axial flow fans

    Science.gov (United States)

    Canepa, Edward; Cattanei, Andrea; Mazzocut Zecchin, Fabio

    2015-03-01

    The paper presents the results of experiments on a low-speed axial-flow fan flush mounted on flat panels typically employed in tests on automotive cooling fans. The experiments have been conducted in a hemi-anechoic chamber and were aimed at evaluating the installation effects of the whole test configuration, including chamber floor and size and shape of the mounting panel. The largest panels cause important SPL variations in a narrow, low frequency range. Their effect on the propagation function has been verified by means of parametric BEM computations. A regular wavy trend associated with reflections from the floor is also present. In both cases, the tonal noise is more strongly affected than the broadband one. The analysis is performed by means of an existing spectral decomposition technique and a new one, which allows to consider different noise generating mechanisms and also to separate the emitted tonal and broadband noise from the associated propagation effects. In order to better identify the features of the noise at the blade passing frequency (BPF) harmonics, the phase of the acoustic pressure is also analysed. Measurements are taken during speed ramps, which allow to obtain both constant-Strouhal number SPL data and constant-speed data. The former data set is employed in the new technique, while the latter may be employed in the standard spectral decomposition techniques. Based on both the similarity theory and the analysis of the Green's function of the problem, a theoretical description of the structure of the received SPL spectrum is given. Then, the possibility of discriminating between tonal and broadband noise generating mechanisms is analysed and a theoretical base for the new spectral decomposition technique is provided.

  3. Goldstone boson condensation and effects of the axial anomaly in color superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Basler, Hannes Gregor Steffen

    2011-01-12

    One of the central objects of interest in high energy physics is the phase diagram of strongly interacting matter, the behavior of quarks and gluons in dependence of temperature and chemical potential. At very high densities and low temperatures it is expected that quarks form a superconductor, the so-called color superconductor. Such a color superconductor might be realized in the inner core of a neutron star. To study the phase structure of a color superconductor under neutron star conditions the Nambu-Jona-Lasinio model is used. The diquark condensates appearing in a color superconductor may break the original symmetries and give rise to Goldstone bosons. In this work we study the possible condensation of these Goldstone bosons. On the level of diquark condensates the condensation of Goldstone bosons is realized by a rotation of scalar into pseudoscalar diquark condensates. The phase diagram is studied, including pseudoscalar diquark condensates, for several different values of the lepton number chemical potential. The masses and thereby the condensation of the Goldstone bosons is effected by a six-point interaction that breaks the axial U(1) symmetry. Usually this six-point interaction is implemented in the NJL model in such a way that is does not effect the diquark sector. This can be fixed by adding an second six-point interaction term to the NJL Lagrangian. The coupling strength of this new interaction term has a great influence on the phase digram. In this context also the effect on the chiral phase transition is studied. (orig.)

  4. The effect of variable stator on performance of a highly loaded tandem axial flow compressor stage

    Science.gov (United States)

    Eshraghi, Hamzeh; Boroomand, Masoud; Tousi, Abolghasem M.; Fallah, Mohammad Toude; Mohammadi, Ali

    2016-06-01

    Increasing the aerodynamic load on compressor blades helps to obtain a higher pressure ratio in lower rotational speeds. Considering the high aerodynamic load effects and structural concerns in the design process, it is possible to obtain higher pressure ratios compared to conventional compressors. However, it must be noted that imposing higher aerodynamic loads results in higher loss coefficients and deteriorates the overall performance. To avoid the loss increase, the boundary layer quality must be studied carefully over the blade suction surface. Employment of advanced shaped airfoils (like CDAs), slotted blades or other boundary layer control methods has helped the designers to use higher aerodynamic loads on compressor blades. Tandem cascade is a passive boundary layer control method, which is based on using the flow momentum to control the boundary layer on the suction surface and also to avoid the probable separation caused by higher aerodynamic loads. In fact, the front pressure side flow momentum helps to compensate the positive pressure gradient over the aft blade's suction side. Also, in comparison to the single blade stators, tandem variable stators have more degrees of freedom, and this issue increases the possibility of finding enhanced conditions in the compressor off-design performance. In the current study, a 3D design procedure for an axial flow tandem compressor stage has been applied to design a highly loaded stage. Following, this design is numerically investigated using a CFD code and the stage characteristic map is reported. Also, the effect of various stator stagger angles on the compressor performance and especially on the compressor surge margin has been discussed. To validate the CFD method, another known compressor stage is presented and its performance is numerically investigated and the results are compared with available experimental results.

  5. The Effect of Variable Stator on Performance of a Highly Loaded Tandem Axial Flow Compressor Stage

    Institute of Scientific and Technical Information of China (English)

    Hamzeh Eshraghi; Masoud Boroomand; Abolghasem M.Tousi; Mohammad Toude Fallah; Ali Mohammadi

    2016-01-01

    Increasing the aerodynamic load on compressor blades helps to obtain a higher pressure ratio in lower rotational speeds.Considering the high aerodynamic load effects and structural concerns in the design process,it is possible to obtain higher pressure ratios compared to conventional compressors.However,it must be noted that imposing higher aerodynamic loads results in higher loss coefficients and deteriorates the overall performance.To avoid the loss increase,the boundary layer quality must be studied carefully over the blade suction surface.Employment of advanced shaped airfoils (like CDAs),slotted blades or other boundary layer control methods has helped the designers to use higher aerodynamic loads on compressor blades.Tandem cascade is a passive boundary layer control method,which is based on using the flow momentum to control the boundary layer on the suction surface and also to avoid the probable separation caused by higher aerodynamic loads.In fact,the front pressure side flow momentum helps to compensate the positive pressure gradient over the aft blade's suction side.Also,in comparison to the single blade stators,tandem variable stators have more degrees of freedom,and this issue increases the possibility of finding enhanced conditions in the compressor off-design performance.In the current study,a 3D design procedure for an axial flow tandem compressor stage has been applied to design a highly loaded stage.Following,this design is numerically investigated using a CFD code and the stage characteristic map is reported.Also,the effect of various stator stagger angles on the compressor performance and especially on the compressor surge margin has been discussed.To validate the CFD method,another known compressor stage is presented and its performance is numerically investigated and the results are compared with available experimental results.

  6. Ligand effects on the electronic structure and magnetism of magnetite surfaces

    OpenAIRE

    Brymora, K.; Calvayrac, F.

    2012-01-01

    We address the effect of functionalization on the electronic and magnetic properties of magnetite surface as an indicator of the same properties in nanoparticles too big for a direct ab-initio approach. Using well-established methods and references (namely LDA+U on magnetite surfaces) we could verify the validity of our approach, and using two typical ligands, dopamine and citrate, namely pi and sigma electron donors, we could predict that those ligands would induce a different change in the ...

  7. Effect of Fluorescently Labeling Protein Probes on Kinetics of Protein-Ligand Reactions

    OpenAIRE

    Sun, Y.S.; Landry, J. P.; Fei, Y.Y.; Zhu, X.D.; Luo, J. T.; Wang, X.B.; Lam, K. S.

    2008-01-01

    We studied the effect of fluorescently labeling proteins on protein-ligand reactions. Un-labeled ligands (streptavidin-binding peptides and rabbit immunoglobulin G (IgG) as antigen targets) are immobilized on epoxy-functionalized glass slides. Unlabeled and Cy3-labeled protein probes from the same batch (streptavidin and goat antibodies) subsequently react with the surface-immobilized targets. By monitoring in situ the surface mass density change using an oblique-incidence reflectivity differ...

  8. Calculating the mean time to capture for tethered ligands and its effect on the chemical equilibrium of bound ligand pairs.

    Science.gov (United States)

    Shen, Lu; Decker, Caitlin G; Maynard, Heather D; Levine, Alex J

    2016-09-01

    We present here the calculation of the mean time to capture of a tethered ligand to the receptor. This calculation is then used to determine the shift in the partitioning between (1) free, (2) singly bound, and (3) doubly bound ligands in chemical equilibrium as a function of the length of the tether. These calculations are used in the research article Fibroblast Growth Factor 2 Dimer with Superagonist in vitro Activity Improves Granulation Tissue Formation During Wound Healing (Decker et al., in press [1]) to explain quantitatively how changes in polymeric linker length in the ligand dimers modifies the efficacy of these molecules relative to that of free ligands. PMID:27408925

  9. Effect of impeller reflux balance holes on pressure and axial force of centrifugal pump

    Institute of Scientific and Technical Information of China (English)

    CAO Wei-dong; DAI Xun; HU Qi-xiang

    2015-01-01

    The size of impeller reflux holes for centrifugal pump has influence on the pressure distribution of front and rear shrouds and rear pump chamber, as well as energy characteristics of whole pump and axial force. Low specific-speed centrifugal pump with Q=12.5 m3/h,H=60 m,n=2950 r/min was selected to be designed with eight axial reflux balance holes with 4.5 mm in diameter. The simulated Q-H curve and net positive suction head (NPSH) were in good agreement with experimental results, which illustrated that centrifugal pump with axial reflux balance holes was superior in the cavitation characteristic; however, it showed to little superiority in head and efficiency. The pressure in rear pump chamber at 0.6 times rate flow is 29.36% of pressure difference between outlet and inlet, which reduces to 29.10% at rate flow and 28.33% at 1.4 times rate flow. As the whole, the pressure distribution on front and rear shrouds from simulation results is not a standard parabola, and axial force decreases as flow rate increases. Radical reflux balance holes chosen to be 5.2 mm and 5.9 mm in diameter were further designed with other hydraulic parts unchanged. With structural grids adopted for total flow field, contrast numerical simulation on internal flow characteristics was conducted based on momentum equations and standard turbulence model (κ-ε). It is found that axial force of pump with radical reflux balance holes of 5.2 mm and 5.9 mm in diameter is significantly less than that with radical reflux balance holes of 4.5 mm in diameter. Better axial force balance is obtained as the ratio of area of reflux balance holes and area of sealing ring exceeds 6.

  10. SU(3)--Breaking Effects in Axial--Vector Couplings of Octet Baryons

    CERN Document Server

    Gensini, P M; Gensini, Paolo M.; Violini, Galileo

    1993-01-01

    Present evidence on baryon axial--vector couplings is reviewed, the main emphasis being on internal consistency between asymmetry and rate data. A complete account of all {\\sl small} terms in the Standard Model description of these latter leads to {\\sl both} consistency {\\sl and} evidence for breaking of flavour SU(3) in the axial couplings of octet baryons. Talk presented at "5th Int. Sympos. on Meson--Nucleon Physics and the Structure of the Nucleon", Boulder, CO, sept. 1993. To be published in $\\pi N$ Newsletter.

  11. The Effect of Gestational Age on Axial Length of the Eyes of Premature Infants

    OpenAIRE

    Mehmet Ali Sekeroglu

    2016-01-01

    Aim: The aim of the present study is to evaluate the axial length of the eyes of premature infants without retinopathy of prematurity and to document the relationship with gestational age and changes as infants grew-up. Material and Method: The axial length of the eyes were measured by using a mobile A-scan ultrasonographic biometry device just before the first retinopathy of prematurity screening examination and 4-weeks thereafter. Results: One-hundred and thirty-six infants with a mean gest...

  12. The Effect of Gestational Age on Axial Length of the Eyes of Premature Infants

    Directory of Open Access Journals (Sweden)

    Mehmet Ali Sekeroglu

    2016-01-01

    Full Text Available Aim: The aim of the present study is to evaluate the axial length of the eyes of premature infants without retinopathy of prematurity and to document the relationship with gestational age and changes as infants grew-up. Material and Method: The axial length of the eyes were measured by using a mobile A-scan ultrasonographic biometry device just before the first retinopathy of prematurity screening examination and 4-weeks thereafter. Results: One-hundred and thirty-six infants with a mean gestational age of 31,7±2,7 weeks and a birth-weight of 1561.0±379.3 g were included in the study. Axial length measurements were done at a mean postconceptional age of 35.8 ±2.6 (31-40 and 39.8±2.7 (35-44 weeks, consecutively. The mean axial length at first and second visits were 16.43±0.42 mm (15.28-17.13 and 16.69±0.41 mm (15.60-17.70, consecutively (p

  13. Effects of chills on the solidification pattern of an axial steel cast impeller

    OpenAIRE

    Copur, M.; Turan, A; Eruslu, M. N.

    2015-01-01

    This paper presents three-dimensional simulation of transient conduction heat transfer within an axial impeller (AISI 1016), two different sizes of chills (AISI 1016), core (green sand) and mold (green sand) by using Ansys CFX. Specific heat, density and thermal conductivity of AISI 1016 steel, mold and Core materials are considered as functions of temperatures

  14. Effects of chills on the solidification pattern of an axial steel cast impeller

    Directory of Open Access Journals (Sweden)

    M. Copur

    2015-07-01

    Full Text Available This paper presents three-dimensional simulation of transient conduction heat transfer within an axial impeller (AISI 1016, two different sizes of chills (AISI 1016, core (green sand and mold (green sand by using Ansys CFX. Specific heat, density and thermal conductivity of AISI 1016 steel, mold and Core materials are considered as functions of temperatures

  15. Large-scale molecular dynamics simulation: Effect of polarization on thrombin-ligand binding energy

    Science.gov (United States)

    Duan, Li L.; Feng, Guo Q.; Zhang, Qing G.

    2016-01-01

    Molecular dynamics (MD) simulations lasting 500 ns were performed in explicit water to investigate the effect of polarization on the binding of ligands to human α-thrombin based on the standard nonpolarizable AMBER force field and the quantum-derived polarized protein-specific charge (PPC). The PPC includes the electronic polarization effect of the thrombin-ligand complex, which is absent in the standard force field. A detailed analysis and comparison of the results of the MD simulation with experimental data provided strong evidence that intra-protein, protein-ligand hydrogen bonds and the root-mean-square deviation of backbone atoms were significantly stabilized through electronic polarization. Specifically, two critical hydrogen bonds between thrombin and the ligand were broken at approximately 190 ns when AMBER force field was used and the number of intra-protein backbone hydrogen bonds was higher under PPC than under AMBER. The thrombin-ligand binding energy was computed using the molecular mechanics Poisson-Boltzmann surface area (MM/PBSA) method, and the results were consistent with the experimental value obtained using PPC. Because hydrogen bonds were unstable, it was failed to predict the binding affinity under the AMBER force field. Furthermore, the results of the present study revealed that differences in the binding free energy between AMBER and PPC almost comes from the electrostatic interaction. Thus, this study provides evidence that protein polarization is critical to accurately describe protein-ligand binding. PMID:27507430

  16. Ultralow power complementary inverter circuits using axially doped p- and n-channel Si nanowire field effect transistors

    Science.gov (United States)

    van, Ngoc Huynh; Lee, Jae-Hyun; Whang, Dongmok; Kang, Dae Joon

    2016-06-01

    We have successfully synthesized axially doped p- and n-type regions on a single Si nanowire (NW). Diodes and complementary metal-oxide-semiconductor (CMOS) inverter devices using single axial p- and n-channel Si NW field-effect transistors (FETs) were fabricated. We show that the threshold voltages of both p- and n-channel Si NW FETs can be lowered to nearly zero by effectively controlling the doping concentration. Because of the high performance of the p- and n-type Si NW channel FETs, especially with regard to the low threshold voltage, the fabricated NW CMOS inverters have a low operating voltage (DOI: 10.1039/c6nr01040g

  17. Effect of Axial Agitator Configuration (Up-Pumping, Down-Pumping, Reverse Rotation) on Flow Patterns Generated in Stirred Vessels

    OpenAIRE

    Aubin, Joelle; Mavros, Paul; Fletcher, David F.; Bertrand, Joël; Xuereb, Catherine

    2001-01-01

    Single phase turbulent flow in a tank stirred with two different axial impellers - a pitched blade turbine (PBT) and a Mixel TT (MTT)- has been studied using Laser Doppler Velocimetry. The effect of the agitator configuration, i.e. up-pumping, down-pumping and reverse rotation, on the turbulent flow field, as well as power, circulation and pumping numbers has been investigated. An agitation index for each configuration was also determined. In the down-pumping mode, the impellers i...

  18. The Effect of Ligand Design on Metal Ion Spin State—Lessons from Spin Crossover Complexes

    Directory of Open Access Journals (Sweden)

    Malcolm A. Halcrow

    2016-05-01

    Full Text Available The relationship between chemical structure and spin state in a transition metal complex has an important bearing on mechanistic bioinorganic chemistry, catalysis by base metals, and the design of spin crossover materials. The latter provide an ideal testbed for this question, since small changes in spin state energetics can be easily detected from shifts in the spin crossover equilibrium temperature. Published structure-function relationships relating ligand design and spin state from the spin crossover literature give varied results. A sterically crowded ligand sphere favors the expanded metal–ligand bonds associated with the high-spin state. However, steric clashes at the molecular periphery can stabilize either the high-spin or the low-spin state in a predictable way, depending on their effect on ligand conformation. In the absence of steric influences, the picture is less clear since electron-withdrawing ligand substituents are reported to favor the low-spin or the high-spin state in different series of compounds. A recent study has shed light on this conundrum, showing that the electronic influence of a substituent on a coordinated metal ion depends on its position on the ligand framework. Finally, hydrogen bonding to complexes containing peripheral N‒H groups consistently stabilizes the low-spin state, where this has been quantified.

  19. Effect of size and conformation of the ligand on asialoglycoprotein receptor-mediated ligand internalization and degradation in rat hepatocytes

    International Nuclear Information System (INIS)

    The rates of internalization and degradation of 125-I-labeled desialylated cyanogen bromide fragment I of orosomucoid (AS-CNBr-I) and its reduced and carboxymethylated derivative (AS-RC-CNBr-I) were compared with those of 125I-labeled asialoorosomucoid (ASOR) in rat hepatocytes. At 30 nM the rates of internalization and degradation of 125I-AS-CNBr-I were greater than those of 125I-ASOR. 125I-AS-RC-CNBr-I also had a lower rate of internalization and degradation. In contrast to 125I-ASOR, when degradation was inhibited by 5 μM colchicine there was a significant intracellular accumulation of the smaller ligands. At 40C the hepatocytes were found to bind the fragmented ligands more than 125I-ASOR. Incubation of the cells with bound ligand at 370 indicated that diacytosis of 125I-ASOR was greater than the smaller ligands. Colchincine markedly enhanced diacytosis of 125I-ASOR. On the other hand, there were marked accumulation of the smaller ligands by colchicine. These results suggest that the rates of internalization, degradation and diacytosis of the ligand are affected by the size and conformation of the ligand through different rates of receptor binding and intracellular transport

  20. The effect of non-uniform damping on flutter in axial flow and energy harvesting strategies

    OpenAIRE

    Singh, Kiran; Michelin, Sebastien; de Langre, Emmanuel

    2012-01-01

    The problem of energy harvesting from flutter instabilities in flexible slender structures in axial flows is considered. In a recent study, we used a reduced order theoretical model of such a system to demonstrate the feasibility for harvesting energy from these structures. Following this preliminary study, we now consider a continuous fluid-structure system. Energy harvesting is modelled as strain-based damping and the slender structure under investigation lies in a moderate fluid loading ra...

  1. Effect of argon on the performance of a fast-axial flow CO2 laser

    Science.gov (United States)

    Jelvani, S.; Amiri, Kh; Pazokian, H.; Montazerolghaem, M.; Mollabashi, M.; Naeimi, S. A.; Esmaeilpour, D.

    2011-01-01

    The performance characteristics of a fast-axial flow (FAF) cw CO2 laser are described. The dependences of the output power, efficiency, and discharge voltage on the discharge current of a FAF cw CO2 laser with optimised composition of the CO2:N2:He=1:4.4:7.6 gas mixture with a small amount of argon are studied experimentally at two pressures of 50 and 60 mbar in open and closed cycle regimes of the laser system.

  2. The control effect of orthokeratology on axial length elongation in Chinese children with myopia

    OpenAIRE

    Zhu, Meng-Jun; Feng, Hao-Yan; He, Xian-Gui; Zou, Hai-Dong; Zhu, Jian-Feng

    2014-01-01

    Background To retrospectively compare axial elongation in children with different degrees of myopia wearing spectacles and undergoing ortho-k treatment. Methods The medical records of 128 patients who were fitted with spectacles or orthokeratology (ortho-k) lenses in our clinic between 2008 and 2009 were reviewed. Ortho-k group comprised 65 subjects and 63 subjects wearing spectacles were included in the control group. Subjects were also divided into low-myopia, moderate-myopia and high-myopi...

  3. Estimation of low cycle fatigue life of elbows considering bi-axial stress effect

    International Nuclear Information System (INIS)

    Elbow pipes are commonly used in the piping systems of power plants and chemical plants. The stress states at elbow part are complex and quite different from those of the straight pipes. It is well known that the fatigue lives of metals under simple push-pull conditions were successfully predicted by the Manson's universal slope method. However, it have been pointed out by the several researchers that the low cycle fatigue lives of elbows under combined cyclic bending and inner pressure could not be predicted by the Manson's universal slope method. However, the reasons for this are not made clear. In this work, the low cycle fatigue tests and the finite element analysis of elbows under cyclic bending and inner pressures were carried out. It was found that the bi-axial stress ratio, which is a ratio of hoop stress and axial stress, at elbows are quite high. Considering the bi-axial stress ratio, the revised Manson's universal slope method was proposed in this paper. It was shown that the low cycle fatigue lives of elbows under combined cyclic bending and inner pressure were predicted conservatively by the proposed method. (author)

  4. The effect of axial force and contact angle on the welded area of plastic tube welded by ultrasonic welding

    Science.gov (United States)

    Thinvongpituk, C.; Bootwong, A.; Watanabe, Y.

    2010-03-01

    This study was aimed to apply the use of ultrasonic welding to weld round plastic tubes. The ultrasonic welding machine was designed to be able to work with a normal ultrasonic welding transducer by rotating the tube while it is being welded. The specimens used in this study were round plastic tubes (PMMA) with diameter of 35 mm and 2 mm thickness. End of each tube was machined to have angle of 2.8, 3.8 and 5.7 degree in order to create contact angle at the interface. The specimens were welded with frequency of 28 kHz and tube rotational speeds of 25 rpm, 45 rpm and 100 rpm. The axial force was applied to the tube in order to enhance the quality of joint. The experimental result revealed that the modified ultrasonic welding machine can generate the welded area around the circumference of tube. It was found that the axial force and contact angle have some effect to the quality of joint. The contact angle of 2.8/2.8 provided highest welded area compared to 3.8/3.8 and 5.7/5.7 degree of contact angle. In addition, the axial force between 80 N - 120 N provided high value of welded area. The pattern of welded area is also presented and discussed in the paper.

  5. Axisymmetric deformations and stresses of unsymmetrically laminated composite cylinders in axial compression with thermally-induced preloading effects

    Science.gov (United States)

    Paraska, Peter J.

    1993-01-01

    This report documents an analytical study of the response of unsymmetrically laminated cylinders subjected to thermally-induced preloading effects and compressive axial load. Closed-form solutions are obtained for the displacements and intralaminar stresses and recursive relations for the interlaminar shear stress were obtained using the closed-form intralaminar stress solutions. For the cylinder geometries and stacking sequence examples analyzed, several important and as yet undocumented effects of including thermally-induced preloading in the analysis are observed. It should be noted that this work is easily extended to include uniform internal and/or external pressure loadings and the application of strain and stress failure theories.

  6. On the Reduction of Vector and Axial-Vector Fields in a Meson Effective Action at O(p4)

    International Nuclear Information System (INIS)

    Starting from an effective NJL-type quark interaction we have derived an effective meson action for the pseudoscalar sector. The vector and axial-vector degrees of freedom have been integrated out, applying the static equations of motion. As the results we have found a (reduced) pseudoscalar meson Lagrangian of the Gasser-Leutwyler type with modified structure coefficients Li. This method has been also used to construct the reduced weak and electromagnetic-weak currents. The application of the reduced Lagrangian and currents has been considered in physical processes. 36 refs., 1 fig., 1 tab

  7. Comparison Between Mitigation Effects of the Finite Larmor Radius and Sheared Axial Flow on Rayleigh-Taylor Instability in Z-Pinch implosions

    Institute of Scientific and Technical Information of China (English)

    邱孝明; 黄林; 简广德

    2002-01-01

    A magnetohydrodynamic (MHD) formulation is derived to investigate and compare the mitigation effects of both the sheared axial flow and finite Larmor radius (FLR) on the Rayleigh-Taylor (RT) instability in Z-pinch implosions. The sheared axial flow is introduced into MHD equations in a conventional way and the FLR effect into the equations via а/аt → -i(ω + ik2⊥ρi2Ωi), as proposed in our previous paper [Chin. Phys. Lett. 2002, 19:217] , where k2⊥ρ2i is referred to FLR effect from the general kinetic theory of magnetized plasma. Therefore the linearized continuity and momentum equations for the perturbed massdensity and velocity include both the sheared axial flow and the FLR effect. It is found that the effect of sheared axial flow with a lower peak velocity can mitigate RT instability in the whole wavenumber region and the effect of sheared axial flow with a higher one can mitigate RT instability only in the large wavenumber region (for normalized wavenumber κ> 2.4); The effect of FLR can mitigate RT instability in the whole wavenumber region and the mitigation effect is stronger than that of the sheared axial flow with a lower peak velocity in the almost whole wavenumber region.

  8. Boundary Layer Transition on an Axial Compressor Stator Blade-Wake Passing and Freestream Turbulence Effects

    Science.gov (United States)

    Walker, G. J.; Solomon, W. J.

    2007-01-01

    Quantitative observations of transitional boundary layers in regions of strong flow deceleration on an axial compressor stator blade are reported. Measurements are obtained at a fixed chordwise position, and the blade incidence was varied by changing the compressor throughflow so as to move the transition region relative to the stationary probe. It was thus possible to observe typical boundary layer behavior at various stages of transition in the turbomachine environment. The range of observations covers separating laminar flow at transition onset, and reattachment of intermittently turbulent periodically separated shear layers.

  9. Phospholipid electrospun nanofibers: effect of solvents and co-axial processing on morphology and fiber diameter

    DEFF Research Database (Denmark)

    Jørgensen, Lars; Qvortrup, Klaus; Chronakis, Ioannis S.

    2015-01-01

    Asolectin phospholipid nano-microfibers were prepared using electrospinning processing. The asolectin fibers were studied by scanning electron microscopy, and the fiber morphology was found to be strongly dependent on the phospholipid concentration and the solvents used. The solvents studied were...... does not follow the theoretically predicted value of similar to 0.35 mu m because of the intermolecular aggregation between the reverse micelles formed in the highly concentrated asolectin solutions. However, when co-axial solvent electrospinning was applied, where the outer needle contains a pure...

  10. Axial-vector current and quark spin content of the proton in an effective theory

    International Nuclear Information System (INIS)

    The background field theory is applied to study the internal spin structure of the proton in terms of both the large Nc expansion and derivative expansion. A new flavor-independent axial-vector current has been derived. Due to the higher order of this current in the large Nc expansion and the higher order in the derivative expansion a small quark spin content is expected and a nonzero strange quark spin content is revealed from the large Nc expansion. The numerical results are in agreement with the data. (orig.)

  11. Role of Iron(III)-salen Chloride as Oxidizing Agent with Thiodiglycolic Acid: The Effect of Axial Ligands

    OpenAIRE

    Perumal Subramaniam; Thangadurai Vanitha; Thiruttimuthu Kodispathi; Chandra Raj Shanmuga Sundari

    2014-01-01

    En este trabajo se estudia la sulfoxidación del ácido tio - diglicólico con cloruro de Fe(III)-salen, que actúa como agente oxi - dante en un medio 50% acetonitrilo-agua. Se observa un desplaza - miento importante hacia el rojo del valor del λ max del FeIII-salen en medio acuoso. El estudio cinético espectrofotométrico indica que el [FeIII(salen)]+ es la especie oxidante activa y que se sigue una cinética Michaelis-Menten, con respecto al sustrato. La velocidad de reacción es altamente sensib...

  12. Oligopeptide-porphyrin interaction studied by chiroptical spectroscopies: Axial ligand effect of metalloporphyrins on peptide matrix conformation

    Czech Academy of Sciences Publication Activity Database

    Setnička, V.; Hlaváček, Jan; Urbanová, M.

    2008-01-01

    Roč. 14, č. 8 (2008), s. 110-110. ISSN 1075-2617. [European Peptide Symposium /30./. 31.08.2008-05.09.2008, Helsinki] Institutional research plan: CEZ:AV0Z40550506 Keywords : interaction oligopeptide-porphyrin * chiroptic properties * peptides conformation * CD and VCD methods Subject RIV: CC - Organic Chemistry

  13. Heterometallic Effects in Trinuclear Complexes Supported by p-Terphenyl Diphosphine Ligands

    OpenAIRE

    Horak, Kyle T.; Lin, Sibo; Rittle, Jonathan; Agapie, Theodor

    2015-01-01

    A series of isostructural trinuclear complexes of metal composition Pd_2Fe, Pd_2Co, and Ni_2Fe was synthesized in a stepwise fashion. Using dinuclear precursors (Pd^I_2 and Ni_^I_2) supported by p-terphenyl diphosphine ligands allowed for the selective incorporation of a single additional metal center. The effects of both metal composition and ligand electronics on cluster properties were studied. These results highlight the importance of metal–metal interactions in mixed-metal sites of struc...

  14. The effect of pK(a) on pyrimidine/pyridine-derived histamine H4 ligands.

    Science.gov (United States)

    Savall, Brad M; Meduna, Steven P; Venable, Jennifer; Wei, Jianmei; Smith, Russell C; Hack, Michael D; Thurmond, Robin L; McGovern, Patricia; Edwards, James P

    2014-12-01

    During the course of our efforts toward the discovery of human histamine H4 antagonists from a series of 2-aminiopyrimidines, it was noted that a 6-trifluoromethyl group dramatically reduced affinity of the series toward the histamine H4 receptor. This observation was further investigated by synthesizing a series of ligands that varied in pKa of the pyrimidine derived H4 ligands by over five orders of magnitude and the effect on histamine H4 affinity. This trend was then extended to the discovery of C-linked piperidinyl-2-amino pyridines as histamine H4 receptor antagonists. PMID:25455490

  15. Effects of selected ligands on U (VI) immobilization by zerovalent iron

    OpenAIRE

    Noubactep, Chicgoua

    2006-01-01

    The effects of Cl-, CO3 2-, EDTA, NO2 -, NO3 -, PO4 3-, SO4 2-, and humic substances (HS) on U(VI) co-precipitation from aqueous solutions by zerovalent iron (ZVI) in the neutral pH range was investigated. Not shaken batch experiments were conducted for 14 days mostly with 15 g/L of five different ZVI materials and 10 mM of selected ligands and 20 mg/l (0.084 mM) of an U(VI) solution. Apart from Cl- all tested ligands induced a decrease of U(VI) coprecipitation. ...

  16. Effects of inlet circumferential fluctuation on the sweep aerodynamic performance of axial fans/compressors

    Science.gov (United States)

    Gui, Xingmin; Zhu, Fang; Wan, Ke; Jin, Donghai

    2013-10-01

    Swept blades have been widely used in the transonic fan/compressor of aircraft engines with the aids of 3D CFD simulation since the design concept of controlling the shock structure was firstly proposed and successfully tested by Dr. Wennerstrom in the 1980s. However, some disadvantage phenomenon has also been induced by excessively 3D blade geometries on the structure stress insufficiency, vibration and reliability. Much confusion in the procedure of design practice leading us to recognize a new view on the flow mechanism of sweep aerodynamical induction: the new radial equilibrium established by the influence of inlet circumferential fluctuation (CF) changes the inlet flows of blading and induces the performance modification of axial fans/compressors blade. The view is verified by simplified models through numerical simulation and circumferentially averaged analysis in the present paper. The results show that the CF source items which originate from design parameters, such as the spanwise distributions of the loading and blading geometries, contribute to the changing of averaged incidence spanwise distribution, and further more affect the performance of axial fans/compressors with swept blades.

  17. The effect of axial fuel rod power profile on fuel temperature and cladding strain

    Directory of Open Access Journals (Sweden)

    Kim Kyu-Tae

    2010-01-01

    Full Text Available The most limiting design criteria for nuclear reactor normal operating conditions (ANS Condition I are known to be rod internal pressure and cladding oxidation, while those for nuclear reactor transient operating conditions (ANS Conditon II to be fuel centerline temperature and transient cladding total tensile strain. However, the design margins against fuel temperature and transient cladding tensile strain become smaller since power uprating is being or will be utilized for the most of nuclear power reactors to enhance the economics of nuclear power. In order to secure sufficient design margins against fuel temperature and cladding total tensile strain even for power uprating, the current axial rod power profiles used in the reactor transient analysis were optimized to reduce over-conservatism, considering that 118% overpower of a steady-state peak rod average power was not exceeded during the reactor transients. The comparison of the current axial rod power profiles and the optimized ones indicates that the latter reduces the fuel centerline temperature and cladding total tensile strain by 26°C and 0.02%, respectively.

  18. The effect of residual axial gravity on the stability of liquid columns subjected to electric fields

    Science.gov (United States)

    Gonzalez, Heliodoro; Castellanos, Antonio

    1993-04-01

    The stability criterion for almost cylindrical dielectric liquid bridges subjected to axial electric fields in the presence of residual axial gravity is obtained. In its absence, a perfectly cylindrical equilibrium solution is allowed for all values of the relevant parameters, which are the slenderness of the liquid bridge, the electrical Bond number and the relative permittivity between the outer and inner media. This basic solution is unstable beyond a critical slenderness which varies with the electrical parameters (Gonzalez et al. 1989). The destabilization takes place axisymmetrically. The inclusion of the gravitational Bond number as a new, small parameter may be treated by means of the Liapunov-Schmidt Method, a well-known projection technique that gives the local bifurcation diagram relating the admissible equilibrium amplitudes for the liquid bridge and the aforementioned parameters. As in the absence of applied electric field, the gravitational Bond number breaks the pitchfork diagram into two isolated branches of axisymmetric equilibrium solutions. The stable one has a turning point whose location determines the new stability criterion. Quantitative results are presented after solving the resulting set of linear recursive problems by means of the method of lines.

  19. Spin crossover and LIESST effect of new iron(II) complexes with imidazole containing ligands

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Naohide; Sato, Tetsuya; Hashimoto, Shingo [Department of Chemistry, Faculty of Science, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555 (Japan); Kojima, Masaaki [Department of Chemistry, Faculty of Science, Okayama University, Tsushima-naka 3-1-1, Okayama 700-8530 (Japan); Iijima, Seiichiro, E-mail: naohide@aster.sci.kumamoto-u.ac.j [National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8566 (Japan)

    2009-02-01

    Three spin crossover (SCO) iron(II) complexes with imidazole containing tridentate ligands has been prepared. It was found that the complexes have versatile network structures constructed by hydrogen-bonds and pi-pi stacking, a variety of SCO properties, and LIESST(light induced excited spin state trapping) effects. The structures and magnetic SCO properties of three complexes are reported.

  20. IDENTIFICATION OF SPECIFIC PEPTIDE LIGANDS FOR B-LYMPHOMA CELL AND ITS EFFECT ON TYROSINE PHOSPHORYLATION AND CELL APOPTOSIS

    Institute of Scientific and Technical Information of China (English)

    宋良文; 马宪梅; 崔雪梅; 李扬; 王晓民

    2004-01-01

    Objective To search novel method for diagnosis and therapy of B-lymphoma, specific small molecular peptide ligands against binding site of tumor cells were screened and its effects on signal transduction and cell apoptosis were tested. Methods Specific peptide ligands were screened by binding with site of human B lymphoma cell (OC1LY8) using peptide-bead libraries. The identified peptides were characterized with responsible cells by rebinding test. The role of tyrosine phosphorylation of peptide ligand was tested by Western blot;and its apoptosispromoting role was observed by confocal fluorescent microscope. Results Specific peptide ligand was able to bind specifically to site on cell surface and enter into cytoplasm. Tetrameric peptide ligand was able to strongly trigger signal transduction resulting in tyrosine phosphorylation and cellular apoptosis in OC1LY8 cell line.Conclusion Screened peptide ligand can effectively bind with OC1LY8 cell, stimulate cellular tyrosine phosphorylation and induce cellular apoptosis.

  1. Effect of axial heat transfer and atmospheric conditions on the energy performance of GSHP systems: A simulation-based analysis

    International Nuclear Information System (INIS)

    A range of analytical and numerical models is available to investigate the thermal behaviour of vertical ground heat exchangers, both in the short- and long-term. However, most of them ignore the thermal effects of weather at ground level that affect the upper part of boreholes. Furthermore, few models look at the integrated simulation of a ground source heat pump system for both the borehole field and heat pump. Consequently, a limited number of applications to real cases are available for designers. This paper shows a study to assess the effects of both axial heat transfer in boreholes and the weather at ground level on the fluid temperature in the boreholes, as well as on the energy efficiency of the heat pump. To this purpose, long-term analysis of two ground source heat pump systems was conducted over ten years by means of a detailed numerical simulation tool. The systems were for two office buildings with unbalanced load profiles in Canada and Italy. These case studies were analyzed as they were being designed, then the influence of the borehole arrangement and borehole length was also investigated. The simulation results show that axial heat transfer affects fluid temperature in the boreholes and the seasonal energy efficiency of the whole system more than the weather. Moreover, when the load profile is unbalanced, neglecting the effect of weather does not always ensure a conservative design of the borehole field. - Highlights: • Multi-year integrated simulations of two real GSHP systems are carried out. • The work focuses on the long-term energy efficiency of GSHP systems. • The simulation tool considers both the borehole field and the heat pump. • The axial heat transfer in the ground affects the energy efficiency of the system. • The weather at the ground level affects the fluid temperature in the boreholes

  2. Approximate calculation of electronic energy levels of axially symmetric quantum dot and quantum ring by using energy dependent effective mass

    Institute of Scientific and Technical Information of China (English)

    Liu Yu-Min; Yu Zhong-Yuan

    2009-01-01

    Calculations of electronic structures about the semiconductor quantum dot and the semiconductor quantum ring are presented in this paper. To reduce the calculation costs, for the quantum dot and the quantum ring, their simplified axially symmetric shapes are utilized in our analysis. The energy dependent effective mass is taken into account in solving the Schrodinger equations in the single band effective mass approximation. The calculated results show that the energy dependent effective mass should be considered only for relatively small volume quantum dots or small quantum rings. For large size quantum materials, both the energy dependent effective mass and the parabolic effective mass can give the same results. The energy states and the effective masses of the quantum dot and the quantum ring as a function of geometric parameters are also discussed in detail.

  3. Evaluation of Aromatic Boronic Acids as Ligands for Measuring Diabetes Markers on Carbon Nanotube Field-Effect Transistors

    OpenAIRE

    Steingrimur Stefansson; Lára A. Stefansson; Suk-won Chung; Kevin Ko; Hena H. Kwon; Saeyoung Nate Ahn

    2012-01-01

    Biomolecular detections performed on carbon nanotube field-effect transistors (CNT-FETs) frequently use reactive pyrenes as an anchor to tether bioactive ligands to the hydrophobic nanotubes. In this paper, we explore the possibility of directly using bioactive aromatic compounds themselves as CNT-FET ligands. This would be an efficient way to functionalize CNT-FETs since many aromatic compounds bind avidly to nanotubes, and it would also ensure that ligand-binding molecules would be brought ...

  4. An application of the biotic ligand model to predict the toxic effects of metal mixtures.

    Science.gov (United States)

    Kamo, Masashi; Nagai, Takashi

    2008-07-01

    The rapidly developing biotic ligand model (BLM) allows us to predict the toxicity of heavy metals in water of various chemistries; however, the current BLM predicts the toxicity of a single metal and not the toxic effects of metal mixtures. The toxic mechanisms of heavy metals are not yet completely understood, but hypocalcemia is suggested to be the most likely toxic mechanism for some metals. The BLM, which predicts the toxicity of metals by the amount of metals binding to ligand, is modified to predict the toxicity by the proportion of nonmetal binding ligand that is available for calcium uptake under the assumption that the organisms die because of hypocalcemia when so few ligands are available for calcium uptake. Because the proportion can be computed when multiple metals are present, the toxic effects of metal mixtures can be predicted. Zinc, copper, and cadmium toxicity to rainbow trout (Oncorhynchus mykiss) are considered. All data are collected from the literature, and a meta-analysis using the modified version of the BLM is conducted. The present study found that the proportion of nonmetal binding ligand is a constant value for any test condition. The proportion is not influenced by water chemistry or by metal species. Using the nature of constant proportion, toxicities of metals are well estimated. In addition, the toxic effects of metal mixtures are the simple sum of the toxicities of each metal (additive effect) corresponding to the bioavailable form of the metals. In terms of total concentration of metals in water, however, nonadditive effects, such as antagonism and synergism, are possible. PMID:18260697

  5. Effect of axial ligation and delivery system on the tumour-localising and -photosensitising properties of Ge(IV)-octabutoxy-phthalocyanines.

    OpenAIRE

    Soncin, M; Polo, L.; Reddi, E.; Jori, G; Kenney, M. E.; Cheng, G; Rodgers, M. A.

    1995-01-01

    Four Ge(IV)-octabutoxy-phthalocyanines (GePcs) bearing two alkyl-type axial ligands were assayed for their pharmacokinetic properties and phototherapeutic efficiency in Balb/c mice bearing an intramuscularly transplanted MS-2 fibrosarcoma. The GePcs were i.v. injected at a dose of 0.35 mumol kg-1 body weight after incorporation into either Cremophor emulsions or small unilamellar liposomes of dipalmitoyl-phosphatidylcholine (DPPC). Both the nature of the delivery system and the chemical struc...

  6. Investigation of Reactivity Feedback Mechanism of Axial and Radial Expansion Effect of Metal-Fueled Sodium-Cooled Fast Reactor

    International Nuclear Information System (INIS)

    The major inherent reactivity feedback models for a ceramic fuel used in a conventional light water reactor are Doppler feedback and moderator feedback. The metal fuel has these two reactivity feedback mechanisms previously mentioned. In addition, the metal fuel has two more reactivity feedback models related to the thermal expansion phenomena of the metal fuel. Since the metal fuel has a good capability to expand according to the temperature changes of the core, two more feedback mechanisms exist. These additional two feedback mechanism are important to the inherent safety of metal fuel and can make metal-fueled SFR safer than oxide-fueled SFR. These phenomena have already been applied to safety analysis on design extended condition. In this study, the effect of these characteristics on power control capability was examined through a simple load change operation. The axial expansion mechanism is induced from the change of the fuel temperature according to the change of the power level of PGSFR. When the power increases, the fuel temperatures in the metal fuel will increase and then the reactivity will decrease due to the axial elongation of the metal fuel. To evaluate the expansion effect, 2 cases were simulated with the same scenario by using MMS-LMR code developed at KAERI. The first simulation was to analyze the change of the reactor power according to the change of BOP power without the reactivity feedback model of the axial and radial expansion of the core during the power transient event. That is to say, the core had only two reactivity feedback mechanism of Doppler and coolant temperature

  7. Investigation of Reactivity Feedback Mechanism of Axial and Radial Expansion Effect of Metal-Fueled Sodium-Cooled Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Seong, Seung-Hwan; Choi, Chi-Woong; Jeong, Tae-Kyung; Ha, Gi-Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    The major inherent reactivity feedback models for a ceramic fuel used in a conventional light water reactor are Doppler feedback and moderator feedback. The metal fuel has these two reactivity feedback mechanisms previously mentioned. In addition, the metal fuel has two more reactivity feedback models related to the thermal expansion phenomena of the metal fuel. Since the metal fuel has a good capability to expand according to the temperature changes of the core, two more feedback mechanisms exist. These additional two feedback mechanism are important to the inherent safety of metal fuel and can make metal-fueled SFR safer than oxide-fueled SFR. These phenomena have already been applied to safety analysis on design extended condition. In this study, the effect of these characteristics on power control capability was examined through a simple load change operation. The axial expansion mechanism is induced from the change of the fuel temperature according to the change of the power level of PGSFR. When the power increases, the fuel temperatures in the metal fuel will increase and then the reactivity will decrease due to the axial elongation of the metal fuel. To evaluate the expansion effect, 2 cases were simulated with the same scenario by using MMS-LMR code developed at KAERI. The first simulation was to analyze the change of the reactor power according to the change of BOP power without the reactivity feedback model of the axial and radial expansion of the core during the power transient event. That is to say, the core had only two reactivity feedback mechanism of Doppler and coolant temperature.

  8. Effects of the symmetry energy slope on the axial oscillations of neutron stars

    Institute of Scientific and Technical Information of China (English)

    Wen De-Hua; Zhou Ying

    2013-01-01

    The impact of symmetry energy slope L on the axial w-mode oscillations is explored,where the range of the constrained slope L of symmetry energy at saturation density is adopted from 25 MeV to 115 MeV while keeping the equation of state (EOS) of symmetric nuclear matter fixed.Based on the range of the symmetry energy slope,a constraint on the frequency and damping time of the wI-mode of the neutron star is given.It is found that there is a perfect linear relation between the frequency and the stellar mass for a fixed slope L,and the softer symmetry energy corresponds to a higher frequency.Moreover,it is confirmed that both the frequencies and damping times have a perfect universal scaling behavior for the EOSs with different symmetry energy slopes at saturation density.

  9. Effect of axial magnetic field on a 2.45 GHz permanent magnet ECR ion source

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, T., E-mail: tsubasa@oshima-k.ac.jp; Wada, H.; Furuse, M. [National Institute of Technology, Oshima College, 1091-1 Komatsu, Suouoshima, Oshima, Yamaguchi 742-2193 (Japan); Asaji, T. [National Institute of Technology, Toyama College, 13 Hongo, Toyama 939-8630 (Japan)

    2016-02-15

    Herein, we conduct a fundamental study to improve the generation efficiency of a multi-charged ion source using argon. A magnetic field of our electron cyclotron resonance ion source is composed of a permanent magnet and a solenoid coil. Thereby, the axial magnetic field in the chamber can be tuned. Using the solenoid coil, we varied the magnetic field strength in the plasma chamber and measured the ion beam current extracted at the electrode. We observed an approximately three times increase in the Ar{sup 4+} ion beam current when the magnetic field on the extractor-electrode side of the chamber was weakened. From our results, we can confirm that the multi-charged ion beam current changes depending on magnetic field intensity in the plasma chamber.

  10. Research on the effect of wear-ring clearances to the axial and radial force of a centrifugal pump

    International Nuclear Information System (INIS)

    Varying of the wear-ring clearance not only has a distinct effect on the volumetric loss of the centrifugal pump, but also on the performance of the centrifugal pump including the axial and radial forces. Comparing with the experimental studies, numerical simulation methods have some special advantages, such as the low cost, fast and high efficiency, and convenient to get the detailed structure of the internal flow characteristics, so it has been widely used in the fluid machinery study in recent years. In order to study the effect of wear-ring clearance on the force performance of the centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump with three variable styles of the wear-rings was simulated: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Comparing with the experiment, numerical results show a good agreement. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the axial force of the centrifugal pump, while has tiny effect on the radial force for all the conditions

  11. Research on the effect of wear-ring clearances to the axial and radial force of a centrifugal pump

    Science.gov (United States)

    Zhao, W. G.; Y He, M.; Qi, C. X.; Li, Y. B.

    2013-12-01

    Varying of the wear-ring clearance not only has a distinct effect on the volumetric loss of the centrifugal pump, but also on the performance of the centrifugal pump including the axial and radial forces. Comparing with the experimental studies, numerical simulation methods have some special advantages, such as the low cost, fast and high efficiency, and convenient to get the detailed structure of the internal flow characteristics, so it has been widely used in the fluid machinery study in recent years. In order to study the effect of wear-ring clearance on the force performance of the centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump with three variable styles of the wear-rings was simulated: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Comparing with the experiment, numerical results show a good agreement. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the axial force of the centrifugal pump, while has tiny effect on the radial force for all the conditions.

  12. Effect of the length of ligands passivating quantum dots on the electrooptical characteristics of organic light-emitting diodes

    International Nuclear Information System (INIS)

    The electrooptical characteristics of organic light-emitting diodes with quantum dots passivated with organic ligands of different lengths as emitting centers are investigated. It is established that the thickness of the ligand coating covering the quantum dots has little effect on the Förster energy transfer in the diodes, but significantly affects the direct injection of charge carriers into the quantum-dot layer. It is shown that the thickness of the passivation coating covering the quantum dots in a close-packed nanoparticle layer is deter- mined both by the length of passivating ligands and the degree of quantum-dot coverage with ligands

  13. Oxygen Reduction Reaction on Pt Overlayers Deposited onto a Gold Film: Ligand, Strain, and Ensemble Effect

    DEFF Research Database (Denmark)

    Deng, Yu-Jia; Tripkovic, Vladimir; Rossmeisl, Jan;

    2016-01-01

    We study the oxygen reduction reaction (ORR), the catalytic process occurring at the cathode in fuel cells, on Pt layers prepared by electrodeposition onto an Au substrate. Using a nominal Pt layer by layer deposition method previously proposed, imperfect layers of Pt on Au are obtained. The ORR on...... deposited Pt layers decreases with increasing Pt thickness. In the submonolayer region, however, the ORR activity is superior to that of bulk Pt. Using density functional theory (DFT) calculations, we correlate the observed activity trend to strain, ligand, and ensemble effects. At submonolayer coverage...... certain atom configurations weaken the binding energies of reaction intermediates due to a ligand and ensemble effect, thus effectively increasing the ORR activity. At higher Pt coverage the activity is governed by a strain effect, which lowers the activity by decreasing the oxidation potential of water...

  14. The Effect of Rotor Blade Speed to the Best Efficiency Point of Single Stage Axial Flow Compressor

    Science.gov (United States)

    Sukri, Mohamad Firdaus; Wasbari, Faizil; Mat, Shafizal

    2010-06-01

    The best efficiency point is ideal operational point for any turbomachinery. Selections of turbomachines in industry such as pump, turbine, compressor, etc are basically based on their operating point. The best efficiency point is a point at the highest efficiency. Therefore, turbomachines with nearest operating point to best efficiency point will be chosen due to higher efficiency thus produce great reduction in cost saving. Different speed of rotor blade will cause effect to the best efficiency point, as well as different in rotor and stator blade angle. If angle of rotor and stator blade constant while speed of rotor blade increased, the net head produced by the compressor will also increased. Thus, it will increase the brake horse power and fluid horse power. Although the efficiency of the compressor increases if fluid horse power increased, the increasing in brake horse power will produce lower efficiency. In this paper, the effect of rotor blade speed on best efficiency point of an axial flow compressor will be investigated and discussed. Through this paper, the highest efficiency is only 73 %, achieved at rotor blade speed of 750 rpm with net head of 9.4 mmWG, and air volumetric flow rate of 0.56m3/s. For higher net head, the rotor blade speed must be increased, but the efficiency will decrease simultaneously. The type of compressor used in this research is single stage axial flow compressor; model Dixson FM36, manufactured by Dixson FA Engineering Sdn. Bhd.

  15. Proposed Model of Predicting the Reduced Yield Axial Load of Reinforced Concrete Columns Due to Casting Deficiency Effect

    Directory of Open Access Journals (Sweden)

    Achillopoulou Dimitra

    2014-12-01

    Full Text Available The study deals with the investigation of the effect of casting deficiencies- both experimentally and analytically on axial yield load or reinforced concrete columns. It includes 6 specimens of square section (150x150x500 mm of 24.37 MPa nominal concrete strength with 4 longitudinal steel bars of 8 mm (500 MPa nominal strength with confinement ratio ωc=0.15. Through casting procedure the necessary provisions defined by International Standards were not applied strictly in order to create construction deficiencies. These deficiencies are quantified geometrically without the use of expensive and expertise non-destructive methods and their effect on the axial load capacity of the concrete columns is calibrated trough a novel and simplified prediction model extracted by an experimental and analytical investigation that included 6 specimens. It is concluded that: a even with suitable repair, load reduction up to 22% is the outcome of the initial construction damage presence, b the lower dispersion is noted for the section damage index proposed, c extended damage alters the failure mode to brittle accompanied with longitudinal bars buckling, d the proposed model presents more than satisfying results to the load capacity prediction of repaired columns.

  16. The Extraction of Silver and the effect of Diluent, Ligand side group and Solvent composition

    Czech Academy of Sciences Publication Activity Database

    Löfström-Engdahl, E.; Aneheim, E.; Ekberg, C.; Foreman, M.; Skarnemark, G.; Hájková, Zuzana; Grüner, Bohumír

    2012-01-01

    Roč. 7, DECEMBER (2012), s. 239-244. ISSN 1876-6196. [International Conference on Nuclear Chemistry for Sustainable Fuel Cycles ATALANTE 2012. Montpellier, 02.09.2012-07.09.2012] R&D Projects: GA MŠk(CZ) 7G08073 EU Projects: European Commission(XE) 211267 - ACSEPT Institutional support: RVO:61388980 Keywords : Silver * BTBP ligands * Diluent effects * Solvent effects Introduction Subject RIV: CA - Inorganic Chemistry

  17. Ruthenium Bis-diimine Complexes with a Chelating Thioether Ligand: Delineating 1,10-Phenanthrolinyl and 2,2'-Bipyridyl Ligand Substituent Effects

    Energy Technology Data Exchange (ETDEWEB)

    Al-Rawashdeh, Nathir A. F.; Chatterjee, Sayandev; Krause, Jeanette A.; Connick, William B.

    2014-01-06

    A new series of ruthenium(II) bis-diimine complexes with a chelating thioether donor ligand has been prepared: Ru(diimine)2(dpte)2+ (diimine=1,10-phenanthroline (phen) (1); 5-CH3-phen (2), 5-Cl-phen (3); 5-Br-phen (4); 5-NO2-phen (5); 3,4,7,8-tetramethyl-phen (6); 4,7-diphenyl-phen (7); 5,5'-dimethyl-2,2'-bipyridine (8); 4,4'-di-tert-butyl-2,2'-bipyridine (9)). Crystal structures of 2, 5, 7 and 9 show that the complexes form 2 of the 12 possible conformational/configurational isomers, adopting compact C2-symmetric structures with short intramolecular transannular interactions between the diimine ligands and dpte phenyl groups; crystals of 2 and 5 contain non-statistical distributions of geometric isomers. In keeping with the π-acidity of the dpte, the Ru(III/II) couple, E°'(Ru3+/2+), occurs at relatively high potentials (1.4-1.7 V vs Ag/AgCl), and the lowest spin-allowed MLCT absorption band occurs near 400 nm. Surprisingly, the complexes also exhibit fluid-solution luminescence originating from a lowest MLCT excited state with lifetimes in the 140-750 ns time range; in acetonitrile, compound 8 undergoes photo-induced solvolysis. Variations in the MLCT energies and redox potentials are quantitatively described using a summative Hammett parameter (σT), as well as using Lever's electrochemical parameters (EL). Recommended parameterizations for 2,2'-bipyridyl and 1,10-phenanthrolinyl ligands were derived from analysis of correlations based on 199 measurements of E°'(Ru3+/2+) for 99 homo- and heteroleptic ruthenium(II) tris-diimine complexes. Variations in E°'(Ru3+/2+) due to substituents at the 4- and 4'-positions of bipyridyl ligands and 4- and 7-positions of phenanthrolinyl ligands are significantly more strongly correlated with σp+ than either σm or σp. Substituents at the 5- and 6-positions of phenanthrolinyl ligands are best described by σm and have effects comparable to those of substituents at the 3

  18. Diffusion air effects on the soot axial distribution concentration in a premixed acetylene/air flame

    Energy Technology Data Exchange (ETDEWEB)

    Fassani, Fabio Luis; Santos, Alex Alisson Bandeira; Goldstein Junior, Leonardo [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia Termica e de Fluidos]. E-mails: fassani@fem.unicamp.br; absantos@fem.unicamp.br; leonardo@fem.unicamp.br; Ferrari, Carlos Alberto [Universidade Estadual de Campinas, SP (Brazil). Inst. de Fisica. Dept. de Eletronica Quantica]. E-mail: ferrari@ifi.unicamp.br

    2000-07-01

    Soot particles are produced during the high temperature pyrolysis or combustion of hydrocarbons. The emission of soot from a combustor, or from a flame, is determined by the competition between soot formation and its oxidation. Several factors affect these processes, including the type of fuel, the air-to-fuel ratio, flame temperature, pressure, and flow pattern. In this paper, the influence of the induced air diffusion on the soot axial distribution concentration in a premixed acetylene/air flame was studied. The flame was generated in a vertical axis burner in which the fuel - oxidant mixture flow was surrounded by a nitrogen discharge coming from the annular region between the burner tube and an external concentric tube. The nitrogen flow provided a shield that protected the flame from the diffusion of external air, enabling its control. The burner was mounted on a step-motor driven, vertical translation table. The use of several air-to-fuel ratios made possible to establish the sooting characteristics of this flame, by measuring soot concentration along the flame height with a non-intrusive laser light absorption technique. (author)

  19. The effects of axial length on the fracture and fragmentation of expanding rings

    Directory of Open Access Journals (Sweden)

    Razorenov S.V.

    2012-08-01

    Full Text Available Rings of Ti-6Al-4V with aspect ratios (wall thickness:axial length of 1 : 1, 1 : 2 and 1 : 4 have been expanded to failure at radial strain rates εr ∼ 1 × 104 s−1 using 4340 (EN24T steel and Cu-ETP cylindrical drivers containing a column of RDX. Expansion velocity was measured using VISAR enabling calculation of the stress-strain history of the ring alongside fragment recovery with up to 98% original ring mass recovered. Using the recovered samples average fragment length and mass and final strain have been measured along with analysis of the fracture sites to determine the active failure mechanisms. Perfect rings (aspect ratio 1 : 1 were found to undergo necking before failure, whereas the longer rings failed though ductile tensile cracking at 45∘ to the radius. This data is then compared with finite element analysis results.

  20. Effects of near-zero Dirac eigenmodes on axial U(1) symmetry at finite temperature

    CERN Document Server

    Tomiya, Akio; Fukaya, Hidenori; Hashimoto, Shoji; Noaki, Junichi

    2014-01-01

    We study the axial U(1)A symmetry of Nf = 2 QCD at finite temperature using the Dirac eigenvalue spectrum. The gauge configurations are generated employing the Mobius domain-wall fermion action on 16^3x8 and 32^3x8 lattices. The physical spatial size of these lattices is around 2 fm and 4 fm, respectively, and the simulated temperature is around 200 MeV, which is slightly above the critical temperature of the chiral phase transition. Although the Mobius domain-wall Dirac operator is expected to have a good chiral symmetry and our data actually show small values of the residual mass, we observe significant violation of the Ginsparg-Wilson relation for the low- lying eigenmodes of the Mobius domain-wall Dirac operator. Using the reweighting technique, we compute the overlap-Dirac operator spectrum on the same set of configurations and find a significant difference of the spectrum between the two Dirac operators for the low-lying eigenvalues. The overlap-Dirac spectrum shows a gap from zero, which is insensitive...

  1. Experimental Investigation of the Root Cause Mechanism and Effectiveness of Mitigating Actions for Axial Offset Anomaly in Pressurized Water Reactors

    International Nuclear Information System (INIS)

    Axial offset anomaly (AOA) in pressurized water reactors refers to the presence of a significantly larger measured negative axial offset deviation than predicted by core design calculations. The neutron flux depression in the upper half of high-power rods experiencing significant subcooled boiling is believed to be caused by the concentration of boron species within the crud layer formed on the cladding surface. Recent investigations of the root-cause mechanism for AOA [1,2] suggest that boron build-up on the fuel is caused by precipitation of lithium metaborate (LiBO2) within the crud in regions of subcooled boiling. Indirect evidence in support of this hypothesis was inferred from operating experience at Callaway, where lithium return and hide-out were, respectively, observed following power reductions and power increases when AOA was present. However, direct evidence of lithium metaborate precipitation within the crud has, heretofore, not been shown because of its retrograde solubility. To this end, this investigation has been undertaken in order to directly verify or refute the proposed root-cause mechanism of AOA, and examine the effectiveness of possible mitigating actions to limit its impact in high power PWR cores

  2. FEA modeling of effect of axial feeding velocity on strain field of rotary swaging process of pure magnesium

    Institute of Scientific and Technical Information of China (English)

    RONG Li; NIE Zuo-ren; ZUO Tie-yong

    2006-01-01

    A coupled thermal-mechanical model of the rotary swaging of pure magnesium was developed using the general finite-element software program MSC/Marc to visualize the effect of axial feeding velocity on the rotary swaging process. The radial displacement occurring in one pulse impact increases in proportion to axial feeding velocity (vax). When the other processing parameters are fixed, the surface roughness of the swaged bar increases with vax and is in parabolic relation with vax. There exists a minimum velocity vax, min below which the decrease of vax will no longer improve the surface roughness. Under the technological conditions of this simulation, when the finial diameter d=6.6 mm, vax, min=1.82 m/min, and when d=7.0 mm, vax, min=1.83 m/min. If Ra=3.2 is required for the end product, then vax, max=6.02 m/min is gotten for d=6.6 mm and vax, max=7.05 m/min for d=7.0mm. The increase of vax has no notable influence on strain distribution along radial direction. The errors between the experimental and simulated height of the spiral spine-like ridges are below 8.0%.

  3. Effects of different ligands on luminescence properties of LaF3∶Nd nanoparticles

    Institute of Scientific and Technical Information of China (English)

    GUI Luo; CUI Xiaoxia; WEI Wei; PENG Bo; FAN Dianyuan

    2013-01-01

    A series of neodymium-doped lanthanum fluoride nanoparticles (NPs) were synthesized with hydrothermal method,and the effects of several ligands on the luminescence properties of the NPs were investigated.The X-ray diffraction (XRD) results indicated that the crystal phases of the modified NPs coincided with the standard spectrum.The transmission electron microscopy (TEM) showed that the samples were of similar size,shape and dispersibility.The infrared spectra suggested that the content of-OH groups as quenchers on the NPs surfaces decreased after modification.Compared with NPs modified by branched paraffin ligands,NPs conjugating ring-contained modifiers had less quenching effect and possessed stronger fluorescence intensity and longer fluorescence lifetime.

  4. Numerical research on the effects of impeller pump-out vanes on axial force in a solid-liquid screw centrifugal pump

    International Nuclear Information System (INIS)

    A commercial CFD code has been used to predict the performance of a screw centrifugal pump with pump-out vanes, especially when changing regularity of impeller axial force based on the solid-liquid two-phase flow. The Unsteady Reynolds Averaged Navier-Stokes (URANS) approach has been applied to solve the unsteady, incompressible, three-dimensional turbulent. The SIMPLEC algorithm, standard wall functions and mix two-phase flow model were applied. The RNG k ε-model was used to account the turbulence effects. By changing the number of impeller pump-out vanes and width, six different screw centrifugal pump numerical simulation projects were given, and each scheme in the different solid volume fraction were calculated respectively. The change rules of axial force, velocity and pressure distribution of flow field were obtained on the different condition and different volume fraction. The results showed that the axial forces values based solid-fluid two-phase greater than based single-phase clear water, but both changing regularity of the axial force were consistent; as same condition, the same solid-phase volume concentration, with the increase of pump-out vanes number or width, the impeller axial force increased as well. Meanwhile the number of the pump-out vanes and the width of pump-out vanes in balancing the impeller axial force, there are the most optimal value

  5. Numerical research on the effects of impeller pump-out vanes on axial force in a solid-liquid screw centrifugal pump

    Science.gov (United States)

    Cheng, X. R.; Li, R. N.; Gao, Y.; Guo, W. L.

    2013-12-01

    A commercial CFD code has been used to predict the performance of a screw centrifugal pump with pump-out vanes, especially when changing regularity of impeller axial force based on the solid-liquid two-phase flow. The Unsteady Reynolds Averaged Navier-Stokes (URANS) approach has been applied to solve the unsteady, incompressible, three-dimensional turbulent. The SIMPLEC algorithm, standard wall functions and mix two-phase flow model were applied. The RNG k ε-model was used to account the turbulence effects. By changing the number of impeller pump-out vanes and width, six different screw centrifugal pump numerical simulation projects were given, and each scheme in the different solid volume fraction were calculated respectively. The change rules of axial force, velocity and pressure distribution of flow field were obtained on the different condition and different volume fraction. The results showed that the axial forces values based solid-fluid two-phase greater than based single-phase clear water, but both changing regularity of the axial force were consistent; as same condition, the same solid-phase volume concentration, with the increase of pump-out vanes number or width, the impeller axial force increased as well. Meanwhile the number of the pump-out vanes and the width of pump-out vanes in balancing the impeller axial force, there are the most optimal value.

  6. NO EFFECT OF DIFFERENT ESTROGEN RECEPTOR LIGANDS ON COGNITION IN ADULT FEMALE MONKEYS

    OpenAIRE

    Lacreuse, Agnès; Wilson, Mark E.; Herndon, James G.

    2008-01-01

    Many studies in women and animal models suggest that estrogens affect cognitive function. Yet, the mechanisms by which estrogens may impact cognition remain unclear. The goal of the present study was to assess the effects of different estrogen receptor (ER) ligands on cognitive function in adult ovariectomized female rhesus monkeys. The monkeys were tested for 6 weeks on a battery of memory and attentional tasks administered on a touchscreen: the object, face, and spatial versions of the Dela...

  7. Effect of an Electric Field on Transfer Processes in Axially Symmetric Magnetic Traps

    International Nuclear Information System (INIS)

    By solving the kinetic equation in the drift approximation, expressions are derived for the particle flux and energy density across a strong magnetic field in axially symmetric systems of the Levitron or Tokamak type. In addition to the longitudinal accelerating electric field, which is responsible for creating the longitudinal current, account is taken of the presence of a quasistatic electric field directed along the minor radius and resulting from ambipolarity of dispersion. Both the case of very low collision frequencies (lower than the characteristic frequency of the azimuthal motion of the ''blocked'' particles) and that of intermediate and high collision frequencies are considered. It is shown that, if either the thermal velocity of the particles or the ratio of the poloidal magnetic field to the longitudinal magnetic field is fairly large (so that the mean longitudinal velocity of the toroidally ''blocked'' particles is much less than the azimuthal variations of their longitudinal velocity), then allowance for the radial electric field corresponds to allowance in the flux expressions for corrections of the next higher (i.e. fourth) order with respect to the smallness parameter used. In the opposite limiting case, allowance for the radial electric field becomes very important: in the region of very low and very high collision frequencies it leads to a substantial change in the functional dependence of the dispersion and heat conduction coefficients on the plasma and magnetic field parameters, while in the region of intermediate collision frequencies it leads to corrections proportional to the square of the ratio of the Larmor radius in the poloidal magnetic field to the characteristic dimension of the plasma inhomogeneity. In conclusion, the author discusses the question of determining a self-consistent radial electric field within the framework of a theory which takes into account only the lowest order with respect to the Larmor radius. (author)

  8. Damped gyroscopic effects and axial-flexural-torsional coupling using spinning finite elements for wind-turbine blades characterization

    Science.gov (United States)

    Velazquez, Antonio; Swartz, R. Andrew

    2013-04-01

    Renewable energy sources like wind are important technologies, useful to alleviate for the current fossil-fuel crisis. Capturing wind energy in a more efficient way has resulted in the emergence of more sophisticated designs of wind turbines, particularly Horizontal-Axis Wind Turbines (HAWTs). To promote efficiency, traditional finite element methods have been widely used to characterize the aerodynamics of these types of multi-body systems and improve their design. Given their aeroelastic behavior, tapered-swept blades offer the potential to optimize energy capture and decrease fatigue loads. Nevertheless, modeling special complex geometries requires huge computational efforts necessitating tradeoffs between faster computation times at lower cost, and reliability and numerical accuracy. Indeed, the computational cost and the numerical effort invested, using traditional FE methods, to reproduce dependable aerodynamics of these complex-shape beams are sometimes prohibitive. A condensed Spinning Finite Element (SFE) method scheme is presented in this study aimed to alleviate this issue by means of modeling wind-turbine rotor blades properly with tapered-swept cross-section variations of arbitrary order via Lagrangian equations. Axial-flexural-torsional coupling is carried out on axial deformation, torsion, in-plane bending and out-of-plane bending using super-convergent elements. In this study, special attention is paid for the case of damped yaw effects, expressed within the described skew-symmetric damped gyroscopic matrix. Dynamics of the model are analyzed by achieving modal analysis with complex-number eigen-frequencies. By means of mass, damped gyroscopic, and stiffness (axial-flexural-torsional coupling) matrix condensation (order reduction), numerical analysis is carried out for several prototypes with different tapered, swept, and curved variation intensities, and for a practical range of spinning velocities at different rotation angles. A convergence study

  9. Influence of an axial ligand in the oxidation of the nitrosyl complex of ruthenium(II), trans-[RuX(NO)(py)4]2+ (X = Cl, OH), to give oxo complex of ruthenium(IV)

    International Nuclear Information System (INIS)

    Oxidation of trans-[Ru(OH)(NO)(py)4]2+ gives trans-[Ru(ONO)(O)(py)4]+, while that of trans-[RuCl(NO)(py)4]2+ yields trans-[RuCl(O)(py)4]+. The two complexes differ in the origin of the oxo ligand. Their formation processes were proved to be influenced by the ligand trans to the nitrosyl. (author)

  10. Effect of ligand on the geometric and electronic structure of Au13 cluster

    Science.gov (United States)

    Shafai, Ghazal; Hong, Sampyo; Rahman, Talat; Bertino, Massimo

    2008-03-01

    We have carried out calculations based on the density functional theory in the projector augmented wave scheme (PAW) and the pseudopotential approach, to examine the effect of the ligand on the geometric and electronic structure of Au13 cluster. We find bare Au13 to form a flat flake, in agreement with previous theoretical calculations. This structure is lower in energy by 2.60 eV in comparison with the well ordered icosahedron geometry. Our results show, however, that the Au13 cluster covered with ligands of phosphine (PH3) forms a stable spherical structure (icosahedron) in agreement with the experiment [1] which is by 0.08 eV lower in energy when compared to the flat-flake complex. If the phosphine is replaced by H, the spherical structure is no longer stable, but it still maintains a 3 dimensional form, signifying the effect of the ligand in stabilization of the structure. We observe a narrow d-band for flat-flake gold atoms in the complex, while in the icosahedron structure the d-band is wider. We also find a stronger overlap between the p orbitals of the P atom with d orbitals of gold atoms in the icosahedron complex. [1] M. F. Bertino et. al. Phys. Chem. B Lett. 110, 21416 (2006)

  11. Effects of Na/K-ATPase and its ligands on bone marrow stromal cell differentiation

    Directory of Open Access Journals (Sweden)

    Moustafa Sayed

    2014-07-01

    Full Text Available Endogenous ligands of Na/K-ATPase have been demonstrated to increase in kidney dysfunction and heart failure. It is also reported that Na/K-ATPase signaling function effects stem cell differentiation. This study evaluated whether Na/K-ATPase activation through its ligands and associated signaling functions affect bone marrow stromal cells (BMSCs, also known as bone marrow-derived mesenchymal stem cells differentiation capacity. BMSCs were isolated from male Sprague–Dawley rats and cultured in minimal essential medium alpha (MEM-α supplemented with 15% Fetal Bovine serum (FBS. The results showed that marinobufagenin (MBG, a specific Na/K-ATPase ligand, potentiated rosiglitazone-induced adipogenesis in these BMSCs. Meanwhile, it attenuated BMSC osteogenesis. Mechanistically, MBG increased CCAAT/enhancer binding protein alpha (C/EBPα protein expression through activation of an extracellular regulated kinase (ERK signaling pathway, which leads to enhanced rosiglitazone-induced adipogenesis. Inhibition of ERK activation by U0126 blocks the effect of MBG on C/EBPα expression and on rosiglitazone-induced adipogenesis. Reciprocally, MBG reduced runt-related transcription factor 2 (RunX2 expression, which resulted in the inhibition of osteogenesis induced by β-glycerophosphate/ascorbic acid. MBG also potentiated rosiglitazone-induced adipogenesis in 3T3-L1 cells and in mouse BMSCs. These results suggest that Na/K-ATPase and its signaling functions are involved in the regulation of BMSCs differentiation.

  12. Surface ligand effects in MEH-PPV/TiO{sub 2} hybrid solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jincheng; Wang, Wengli; Yu, Huangzhong; Wu, Zhonglian; Peng, Junbiao; Cao, Yong [Institute of Polymer Optoelectronic Materials and Devices, Key Laboratory of Special Functional Materials of the Ministry of Education, South China University of Technology, Guangzhou 510640 (China)

    2008-11-15

    TiO{sub 2} nanorods (NRs) were synthesized by hydrolysis of titanium tetraisopropoxide (TTIP) using oleic acid (99%) as surfactant at low temperatures (80-100 C) and are modified with different ligands: oleic acid (OLA), n-octyl-phosphonic acid (OPA) and thiophenol (TP) in order to investigate the effect of surface ligand on the excition dissociation and the charge transport in hybrid MEH-PPV/TiO{sub 2} photovoltaic (PV) cells. The morphology and crystalline form of as-prepared TiO{sub 2} NRs are examined by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray diffraction (XRD) and Raman spectrometer (RS). The FTIR analysis confirms all the ligands coordinated with the Ti center of TiO{sub 2} NRs. The optical properties of the modified TiO{sub 2} NRs are characterized by UV-vis absorption spectra and photoluminescence (PL) spectra. Thiophenol modified TiO{sub 2} NRs quench the PL of MEH-PPV more effectively than OLA-TiO{sub 2} NRs and OPA-TiO{sub 2} NRs. The power conversion efficiency of hybrid PV cells from thiophenol modified TiO{sub 2} NRs and MEH-PPV is the highest among the investigated TiO{sub 2} NRs. (author)

  13. Effects of counterion valency on the damping of phonons propagating along the axial direction of liquid-crystalline DNA

    Science.gov (United States)

    Liu, Yun; Chen, Sow-Hsin; Berti, Debora; Baglioni, Piero; Alatas, Ahmet; Sinn, Harald; Alp, Ercan; Said, Ayman

    2005-12-01

    The phonon propagation and damping along the axial direction of films of aligned 40wt% calf-thymus DNA rods are studied by inelastic x-ray scattering (IXS). The IXS spectra are analyzed with the generalized three effective eigenmode theory, from which we extract the dynamic structure factor S (Q,E) as a function of transferred energy E =ℏω, and the magnitude of the transferred wave vector Q. S (Q,E) of a DNA sample typically consists of three peaks, one central Rayleigh scattering peak, and two symmetric Stokes and anti-Stokes Brillouin side peaks. By analyzing the Brillouin peaks, the phonon excitation energy and damping can be extracted at different Q values from about 4 to 30nm-1. A high-frequency sound speed is obtained from the initial slope of the linear portion of the dispersion relation below Q =4nm-1. The high-frequency sound speed obtained in this Q range is 3100m /s, which is about twice faster than the ultrasound speed of 1800m/s, measured by Brillouin light scattering at Q ˜0.01nm-1 at the similar hydration level. Our observations provide further evidence of the strong coupling between the internal dynamics of a DNA molecule and the dynamics of the solvent. The effect on damping and propagation of phonons along the axial direction of DNA rods due to divalent and trivalent counterions has been studied. It is found that the added multivalent counterions introduce stronger phonon damping. The phonons at the range between ˜12.5 and ˜22.5nm-1 are overdamped by the added counterions according to our model analyses. The intermediate scattering function is extracted and it shows a clear two-step relaxation with the fast relaxation time ranging from 0.1 to 4ps.

  14. Numerical and experimental investigation of stepped tip gap effects on a subsonic axial-flow compressor rotor

    Energy Technology Data Exchange (ETDEWEB)

    Lu, X.; Zhu, J.; Chu, W. [Northwestern Polytechnical University, Xi' an (China). School of Power and Energy

    2005-12-15

    This article investigates the flow field at the tip region of compressor rotor. In particular, the effect of stepped tip gaps on the performance and flow field of axial compressor was reviewed using experimental and computational methods. An axial compressor rotor with no inlet guide vanes was tested under subsonic conditions. A parametric study of clearance levels and step profiles was performed using eight different casing geometries. This study was aimed at comparing compressor performance in specified configurations. The experimental results showed that the inclusion of stepped tip gaps with the small clearance level gave increased pressure ratio, efficiency, and stall margin throughout the mass flow range at both speeds. However, when using medium and large clearance levels, the benefits of stepped tip gaps were not noticed for all rotor operating conditions when compared with the baseline case. Steady-state Navier-Stokes analyses were performed for cases involving small clearance level and stepped tip gas geometries. They highlighted the mechanisms associated with performance improvement. The numerical procedure correctly predicted the overall effects of stepped tip gaps. Detailed numerical simulation results showed that the interaction between the stepped groove flow and the blade passage flow could entrain the blockage produced by upstream tip leakage flow into the tip gap of adjacent blades of the compressor rotor. It is through this process that stepped tip gaps can help in dissipating blockage that was caused by upstream top leakage flow. Thus, the path and extent of the blockage in the tip region are altered to increase the passage through-flow area, and so, the rotor performance can be improved. (author)

  15. Biological effects of ruthenium, osmium and copper complexes with tumour inhibiting ligands

    International Nuclear Information System (INIS)

    Many substances active against neoplastic cells lack solubility and bioavailability. Standard therapies using well-known platin analogues, among them cisplatin, can only cure a few types of malignances and have serious side effects. A major problem with many tumours is the occurrence of acquired and/or intrinsic resistance. In this study as an alternative to platinum agents, new complexes of ruthenium, osmium and copper complexes with pronouncedly biologically active ligands (indolobenzazepines, indolochinolines, chinoxalinones, flavones and benzimidazolyl-pyrazolo-pyridines) were under investigation in order to improve the desired destructive impact on cancer cells. Formulation complexes with transition metal centers which are binding to DNA or other biomolecules and biologically active ligands may yield synergistic effects, enhance the solubility of ligands and act against cancer cells in two ways. Modification of these complexes by changing the metal center and different ligands as well as an alteration of substituents were investigated in order to find a stable, well soluble and optimal structure for biomolecule interaction. The cell cycle regulated by cyclin-dependent kinases (Cdks) and their modulators is a major target of cancer therapy. Many ATP antagonists were synthesized, but among them there are only a few that have reached the stage of clinical trials. All complexes investigated here were tested as to their cytotoxic potency with three cancer cell lines (A549, CH1, SW480), some of them with three additional ones (LNCaP, T47D, N87) by an MTT assay. The results of structure-activity relationships of different cell lines were compared. All compounds under investigation showed cytotoxic potency with IC50 values in the micromolar to nanomolar range. Results with respect to selected compounds were then compared as to their influence on the cell cycle which was in most cases rather weak, and as to the induction of apoptosis (Annexin/PI stain), both measured

  16. Parameterization of an effective potential for protein-ligand binding from host-guest affinity data.

    Science.gov (United States)

    Wickstrom, Lauren; Deng, Nanjie; He, Peng; Mentes, Ahmet; Nguyen, Crystal; Gilson, Michael K; Kurtzman, Tom; Gallicchio, Emilio; Levy, Ronald M

    2016-01-01

    Force field accuracy is still one of the "stalemates" in biomolecular modeling. Model systems with high quality experimental data are valuable instruments for the validation and improvement of effective potentials. With respect to protein-ligand binding, organic host-guest complexes have long served as models for both experimental and computational studies because of the abundance of binding affinity data available for such systems. Binding affinity data collected for cyclodextrin (CD) inclusion complexes, a popular model for molecular recognition, is potentially a more reliable resource for tuning energy parameters than hydration free energy measurements. Convergence of binding free energy calculations on CD host-guest systems can also be obtained rapidly, thus offering the opportunity to assess the robustness of these parameters. In this work, we demonstrate how implicit solvent parameters can be developed using binding affinity experimental data and the binding energy distribution analysis method (BEDAM) and validated using the Grid Inhomogeneous Solvation Theory analysis. These new solvation parameters were used to study protein-ligand binding in two drug targets against the HIV-1 virus and improved the agreement between the calculated and the experimental binding affinities. This work illustrates how benchmark sets of high quality experimental binding affinity data and physics-based binding free energy models can be used to evaluate and optimize force fields for protein-ligand systems. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26256816

  17. Interactions of human hemoglobin with charged ligand-functionalized iron oxide nanoparticles and effect of counterions

    International Nuclear Information System (INIS)

    Human hemoglobin is an important metalloprotein. It has tetrameric structure with each subunit containing a ‘heme’ group which carries oxygen and carbon dioxide in blood. In this work, we have investigated the interactions of human hemoglobin (Hb) with charged ligand-functionalized iron oxide nanoparticles and the effect of counterions, in aqueous medium. Several techniques like DLS and ζ-potential measurements, UV–vis, fluorescence, and CD spectroscopy have been used to characterize the interaction. The nanoparticle size was measured to be in the range of 20–30 nm. Our results indicated the binding of Hb with both positively as well as negatively charged ligand-functionalized iron oxide nanoparticles in neutral aqueous medium which was driven by the electrostatic and the hydrophobic interactions. The electrostatic binding interaction was not seen in phosphate buffer at pH 7.4. We have also observed that the ‘heme’ groups of Hb remained unaffected on binding with charged nanoparticles, suggesting the utility of the charged ligand-functionalized nanoparticles in biomedical applications

  18. Interactions of human hemoglobin with charged ligand-functionalized iron oxide nanoparticles and effect of counterions

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Goutam, E-mail: ghoshg@yahoo.com [UGC-DAE Consortium for Scientific Research, Mumbai Centre (India); Panicker, Lata [Bhabha Atomic Research Centre, Solid State Physics Division (India)

    2014-12-15

    Human hemoglobin is an important metalloprotein. It has tetrameric structure with each subunit containing a ‘heme’ group which carries oxygen and carbon dioxide in blood. In this work, we have investigated the interactions of human hemoglobin (Hb) with charged ligand-functionalized iron oxide nanoparticles and the effect of counterions, in aqueous medium. Several techniques like DLS and ζ-potential measurements, UV–vis, fluorescence, and CD spectroscopy have been used to characterize the interaction. The nanoparticle size was measured to be in the range of 20–30 nm. Our results indicated the binding of Hb with both positively as well as negatively charged ligand-functionalized iron oxide nanoparticles in neutral aqueous medium which was driven by the electrostatic and the hydrophobic interactions. The electrostatic binding interaction was not seen in phosphate buffer at pH 7.4. We have also observed that the ‘heme’ groups of Hb remained unaffected on binding with charged nanoparticles, suggesting the utility of the charged ligand-functionalized nanoparticles in biomedical applications.

  19. Effect of template ion-ligand complex stoichiometry on selectivity of ion-imprinted polymers.

    Science.gov (United States)

    Laatikainen, Katri; Udomsap, Dutduan; Siren, Heli; Brisset, Hugues; Sainio, Tuomo; Branger, Catherine

    2015-03-01

    In order to highlight the importance of the complex stoichiometry during ion imprinted polymer (IIP) synthesis, we investigated the effect of the complex structure on IIPs selectivity by adjusting the complex stoichiometry before polymerization. 2-(aminomethyl)pyridine monomer (amp) was chosen as a functionalized ligand for nickel(II) ions and a polymerizable vinylbenzyl derivative (Vbamp) was prepared. Complex formation was studied by varying the nickel/Vbamp ratio and recording absorption spectra of the complexes at the polymerization conditions. Using a least-squares minimization scheme, the complex species distribution was successfully established. From these results, it was possible to choose the metal/ligand stoichiometry in the complex (1:1; 1:2 or 1:3) by adjusting the initial metal/ligand ratio. IIPs were then prepared by inverse suspension copolymerization of Vbamp with ethyleneglycol dimethacrylate (EDMA). Highly porous particles with good nickel binding capacity and good Ni/Zn selectivity even at acidic conditions were obtained. Equilibrium uptake of Ni(II) at pH 7 ranged from 0.12 to 0.2 mmol g(-1) and relative selective coefficient was as high as 260 for the IIP prepared using the Ni(Vbamp)2 complex. PMID:25618705

  20. Electronic spectra and photophysics of platinum(II) complexes with alpha-diimine ligands - Solid-state effects. I - Monomers and ligand pi dimers

    Science.gov (United States)

    Miskowski, Vincent M.; Houlding, Virginia H.

    1989-01-01

    Two types of emission behavior for Pt(II) complexes containing alpha-diimine ligands have been observed in dilute solution. If the complex also has weak field ligands such as chloride, ligand field (d-d) excited states become the lowest energy excited states. If only strong field ligands are present, a diimine 3(pi-pi/asterisk/) state becomes the lowest. In none of the cases studied did metal-to-ligand charge transfer excited state lie lowest.

  1. Investigation of the Shear Flow Effect and Tip Clearance on a Low Speed Axial Flow Compressor Cascade

    Directory of Open Access Journals (Sweden)

    Mahesh Varpe

    2013-01-01

    Full Text Available This paper explores the effect of inlet shear flow on the tip leakage flow in an axial flow compressor cascade. A flow with a high shear rate is generated in the test section of an open circuit cascade wind tunnel by using a combination of screens with a prescribed solidity. It is observed that a stable shear flow of shear rate 1.33 is possible and has a gradual decay rate until 15 times the height of the shear flow generator downstream. The computational results obtained agree well with the available experimental data on the baseline configuration. The detailed numerical analysis shows that the tip clearance improves the blade loading near the tip through the promotion of favorable incidence by the tip leakage flow. The tip clearance shifts the centre of pressure on the blade surface towards the tip. It, however, has no effect on the distribution of end wall loss and deviation angle along the span up to 60% from the hub. In the presence of a shear inflow, the end wall effects are considerable. On the other hand, with a shear inflow, the effects of tip leakage flow are observed to be partly suppressed. The shear flow reduces the tip leakage losses substantially in terms of kinetic energy associated with it.

  2. Scale effect on wave propagation of double-walled carbon nanotubes with initial axial loading

    Energy Technology Data Exchange (ETDEWEB)

    Heireche, H; Benzair, A [Departement de physique, Universite de Sidi Bel Abbes, BP 89 Cite Ben M' hidi, 22000 Sidi Bel Abbes (Algeria); Tounsi, A [Laboratoire des Materiaux et Hydrologie, Universite de Sidi Bel Abbes, BP 89 Cite Ben M' hidi, 22000 Sidi Bel Abbes (Algeria)], E-mail: tou_abdel@yahoo.com

    2008-05-07

    This paper studies the vibrational characteristics of double-walled carbon nanotubes (DWNTs) with initial stress using a nonlocal Euler-Bernoulli beam model. Both the effect of initial stress and the effect of small length scale are discussed in detail. The effect of van der Waals forces is incorporated in the formulation. The corresponding resonant vibrational characteristics are presented in detail; they are shown to be very different from those predicted by classical elasticity theory when nonlocal effects are significant. The influence of initial stress in carbon nanotubes on their flexural vibration modes is dependent on the tension or compression form of the initial stress. The investigation of the effects of initial stress on transverse wave propagation in carbon nanotubes may be used as a useful reference for the application and the design of nanoelectronic and nanodrive devices, nano-oscillators, and nanosensors, in which carbon nanotubes act as basic elements.

  3. Scale effect on wave propagation of double-walled carbon nanotubes with initial axial loading

    International Nuclear Information System (INIS)

    This paper studies the vibrational characteristics of double-walled carbon nanotubes (DWNTs) with initial stress using a nonlocal Euler-Bernoulli beam model. Both the effect of initial stress and the effect of small length scale are discussed in detail. The effect of van der Waals forces is incorporated in the formulation. The corresponding resonant vibrational characteristics are presented in detail; they are shown to be very different from those predicted by classical elasticity theory when nonlocal effects are significant. The influence of initial stress in carbon nanotubes on their flexural vibration modes is dependent on the tension or compression form of the initial stress. The investigation of the effects of initial stress on transverse wave propagation in carbon nanotubes may be used as a useful reference for the application and the design of nanoelectronic and nanodrive devices, nano-oscillators, and nanosensors, in which carbon nanotubes act as basic elements

  4. Space charge effects in axial injection line for U-400 cyclotron

    International Nuclear Information System (INIS)

    The space charge influence on the beam dynamics in transport line is studied by the method of the distribution moments. Fifteen equations describing dependence of the first and second order moments (average transverse beam sizes and velocities, cross terms) on longitudinal coordinate are solved numerically. For particular U-400 cyclotron injection line the value of current which produces significant effect on beam dynamics is defined. It is shown that space charge effects can be compensated by proper readjusting of the solenoid strengths

  5. Electrothermal vaporization with axially focusing convection upstream: effects of graphite furnace carbon and K/Pd modifiers on analyte transport

    CERN Document Server

    Trenin, A; Hermann, G

    2005-01-01

    A novel construction of an electrothermal vaporization (ETV) unit is described. Its main feature is an upstream within a vertical tube creating an axially focusing convection zone, where the condensation occurs in a laminar flow predominantly apart from the colder walls. The upstream is shielded against incandescent emission of the graphite furnace (GF) and surrounded with different cooling gases, which have additionally a focusing effect. Transport efficiencies (TEs) for Cu, Fe, Mn, Ni, and Pb are studied using a continuum source coherent forward scattering multi-element spectrometer coupled to the ETV. Increasing TE with the ageing of the GF is observed. The effect is presumably ascribed to the growing content of carbon particulates released during the vaporization. A positive impact of K and Pd(NO3)2 modifiers in microgram amounts foremost on the TEs of more volatile species is observed. It is assumed that K+ ions speed up the nucleated condensation while the effect of Pd(NO3)2 is attributed to the more sy...

  6. Predicting Allosteric Effects from Orthosteric Binding in Hsp90-Ligand Interactions: Implications for Fragment-Based Drug Design

    Science.gov (United States)

    Larsson, Andreas; Nordlund, Paer; Jansson, Anna; Anand, Ganesh S.

    2016-01-01

    A key question in mapping dynamics of protein-ligand interactions is to distinguish changes at binding sites from those associated with long range conformational changes upon binding at distal sites. This assumes a greater challenge when considering the interactions of low affinity ligands (dissociation constants, KD, in the μM range or lower). Amide hydrogen deuterium Exchange mass spectrometry (HDXMS) is a robust method that can provide both structural insights and dynamics information on both high affinity and transient protein-ligand interactions. In this study, an application of HDXMS for probing the dynamics of low affinity ligands to proteins is described using the N-terminal ATPase domain of Hsp90. Comparison of Hsp90 dynamics between high affinity natural inhibitors (KD ~ nM) and fragment compounds reveal that HDXMS is highly sensitive in mapping the interactions of both high and low affinity ligands. HDXMS reports on changes that reflect both orthosteric effects and allosteric changes accompanying binding. Orthosteric sites can be identified by overlaying HDXMS onto structural information of protein-ligand complexes. Regions distal to orthosteric sites indicate long range conformational changes with implications for allostery. HDXMS, thus finds powerful utility as a high throughput method for compound library screening to identify binding sites and describe allostery with important implications for fragment-based ligand discovery (FBLD). PMID:27253209

  7. Predicting Allosteric Effects from Orthosteric Binding in Hsp90-Ligand Interactions: Implications for Fragment-Based Drug Design.

    Directory of Open Access Journals (Sweden)

    Arun Chandramohan

    2016-06-01

    Full Text Available A key question in mapping dynamics of protein-ligand interactions is to distinguish changes at binding sites from those associated with long range conformational changes upon binding at distal sites. This assumes a greater challenge when considering the interactions of low affinity ligands (dissociation constants, KD, in the μM range or lower. Amide hydrogen deuterium Exchange mass spectrometry (HDXMS is a robust method that can provide both structural insights and dynamics information on both high affinity and transient protein-ligand interactions. In this study, an application of HDXMS for probing the dynamics of low affinity ligands to proteins is described using the N-terminal ATPase domain of Hsp90. Comparison of Hsp90 dynamics between high affinity natural inhibitors (KD ~ nM and fragment compounds reveal that HDXMS is highly sensitive in mapping the interactions of both high and low affinity ligands. HDXMS reports on changes that reflect both orthosteric effects and allosteric changes accompanying binding. Orthosteric sites can be identified by overlaying HDXMS onto structural information of protein-ligand complexes. Regions distal to orthosteric sites indicate long range conformational changes with implications for allostery. HDXMS, thus finds powerful utility as a high throughput method for compound library screening to identify binding sites and describe allostery with important implications for fragment-based ligand discovery (FBLD.

  8. Reversible axial-strain effect in Y-Ba-Cu-O coated conductors

    International Nuclear Information System (INIS)

    The recently discovered reversible strain effect in Y-Ba-Cu-O (YBCO) coated conductors contrasts with the general understanding that the effect of strain on the critical-current density Jc in practical high-temperature superconductors is determined only by crack formation in the ceramic component. Instead of having a constant Jc as a function of strain before an irreversible drop when cracks form in the superconductor, Jc in YBCO coated conductors can decrease or increase reversibly with strain over a significant strain range up to an irreversible strain limit. This reversible effect is present in samples fabricated either with rolling-assisted biaxially textured Ni-W substrates or with ion-beam-assisted deposition on Hastalloy substrates. The reversibility of Jc with strain is observed for thin as well as thick YBCO films, and at two very different temperatures (76 and 4 K). The reversible effect is dependent on temperature and magnetic field, thus indicating its intrinsic nature. We also report an enhancement of the irreversible strain limit εirr where the reversible strain effect ends and YBCO cracking starts. The value of εirr increases from about 0.4% to more than 0.5% when YBCO coated conductors are fabricated with an additional Cu protection layer

  9. Study on the Effects of End-bend Cantilevered Stator in a 2-stage Axial Compressor

    Institute of Scientific and Technical Information of China (English)

    Songtao WANG; Xin DU; Zhongqi WANG

    2009-01-01

    Leading edge recambering is applied to the cantilevered stator vanes in a 2-stage compressor in this paper. Dif-ferent curving effects are produced when the end-bend stator vanes are stacked in different ways. Stacking on the leading edge induces a positive curving effect near the casing.When it is stacked on the centre of gravity, a nega-tive curving effect takes place. The numerical investigation shows that the flow field is redistributed when the end-bend stators with leading edge stacking are applied. The variations in the stage matching for the mainstream and near the hub have an impact on the performance of the 2-stage compressor. The isentropic efficiency and the total pressure ratio of the compressor are increased near the design condition. The compressor total pressure ratio is decreased near choke and near stall. The maximum flow rate is reduced and the stall margin is decreased.

  10. Effects of coumestrol on lipid and glucose metabolism as a farnesoid X receptor ligand

    International Nuclear Information System (INIS)

    In the course of an effort to identify novel agonists of the farnesoid X receptor (FXR), coumestrol was determined to be one such ligand. Reporter and in vitro coactivator interaction assays revealed that coumestrol bound and activated FXR. Treatment of Hep G2 cells with coumestrol stimulated the expression of FXR target genes, thereby regulating the expression of target genes of the liver X receptor and hepatocyte nuclear factor-4α. Through these actions, coumestrol is expected to exert beneficial effects on lipid and glucose metabolism

  11. Antianxiety and antidepressant-like effects of AC-5216, a novel mitochondrial benzodiazepine receptor ligand

    OpenAIRE

    Kita, Atsuko; Kohayakawa, Hitoshi; Kinoshita, Tomoko; Ochi, Yoshiaki; Nakamichi, Keiko; Kurumiya, Satoshi; Furukawa, Kiyoshi; Oka, Makoto

    2004-01-01

    We investigated the ability of N-benzyl-N-ethyl-2-(7,8-dihydro-7-methyl-8-oxo-2-phenyl-9H-purin-9-yl)acetamide (AC-5216), a novel mitochondrial benzodiazepine receptor (MBR) ligand, to produce anti-anxiety and antidepressant-like effects in various animal models.AC-5216 showed high affinity for MBRs prepared from rat whole brain (Ki 0.297 nM), rat glioma cells (IC50 3.04 nM) and human glioma cells (IC50 2.73 nM), but only negligible affinity for the other main receptors including central benz...

  12. Displacement of one Newtonian fluid by another: density effects in axial annular flow

    DEFF Research Database (Denmark)

    Szabo, Peter; Hassager, Ole

    1997-01-01

    The arbitrary Lagrange-Euler (ALE) finite elementtechnique is used to simulate 3D displacement oftwo immiscible Newtonian fluids in vertical annular wells. For equally viscous fluids the effect of distinct fluid densities is investigated in the region of low to intermediate Reynolds numbers. Comp......, the efficiency of the displacement is analysed for various flow situations....

  13. Effect of peripheral benzodiazepine receptor ligands on lipopolysaccharide-induced tumor necrosis factor activity in thioglycolate-treated mice.

    OpenAIRE

    Matsumoto, T.; Ogata, M.; Koga, K.; Shigematsu, A

    1994-01-01

    To investigate the effect of peripheral and central benzodiazepine receptor ligands on lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF) activity in mouse macrophages, three types of ligands, 4'-chlorodiazepam (pure peripheral), midazolam (mixed), and clonazepam (pure central), were compared. Midazolam and 4'-chlorodiazepam significantly suppressed LPS (1-microgram/ml)-induced TNF activity in thioglycolate-elicited mouse macrophages. In every concentration examined (0.001 to 100 mi...

  14. Therapeutic and Adverse Effects of a Non-Steroidal Glucocorticoid Receptor Ligand in a Mouse Model of Multiple Sclerosis

    OpenAIRE

    Simone Wüst; Denise Tischner; Michael John; Tuckermann, Jan P; Christiane Menzfeld; Uwe-Karsten Hanisch; Jens van den Brandt; Fred Lühder; Reichardt, Holger M.

    2009-01-01

    BACKGROUND: Dissociating glucocorticoid receptor (GR) ligands hold great promise for treating inflammatory disorders since it is assumed that they exert beneficial activities mediated by transrepression but avoid adverse effects of GR action requiring transactivation. Here we challenged this paradigm by investigating 2-(4-acetoxyphenyl)-2-chloro-N-methyl-ethylammonium chloride (CpdA), a dissociating non-steroidal GR ligand, in the context of experimental autoimmune encephalomyelitis (EAE), an...

  15. Does the reason for discontinuation of a first TNF inhibitor influence the effectiveness of a second TNF inhibitor in axial spondyloarthritis?

    DEFF Research Database (Denmark)

    Ciurea, Adrian; Exer, Pascale; Weber, Ulrich;

    2016-01-01

    BACKGROUND: With regard to switching tumor necrosis factor inhibitors (TNFi) in axial spondyloarthritis (axSpA), conflicting results have been reported as to whether the effectiveness of a second TNFi depends on the reason for discontinuation of the first TNFi. METHODS: Patients with a clinical d...

  16. THERMO-PIEZOELECTRIC EFFECTS ON THE POSTBUCKLING OF AXIALLY-LOADED HYBRID LAMINATED CYLINDRICAL PANELS

    Institute of Scientific and Technical Information of China (English)

    沈惠申

    2004-01-01

    A compressive postbuckling analysis is presented for a laminated cylinderical panel with piezoelectric actuators subjected to the combined action of mechanical, electrical and thermal loads. The temperature field considered is assumed to be a uniform distribution over the panel surface and through the panel thickness and the electric field is assumed to be the transverse component Ez only. The material properties are assumed to be independent of the temperature and the electric field. The governing equations are based on the classicalshell theory with von Ka rman-Donnell-type of kinematic nonlinearity. The nonlinear prebuckling deformations and initial geometric imperfections of the panel are both taken into account. A boundary layer theory of shell buckling, which includes the effects of nonlinearprebuckling deformations, large deflections in the postbuckling range, and initial geometric imperfections of the shell, is extended to the case of hybrid laminated cylindrical panels of finite length. A singular perturbation technique is employed to determine the buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the compressive postbuckling behavior of perfect and imperfect, cross-ply laminated cylindrical thin panels with fully covered or embedded piezoelectric actuators under different sets of thermal and electrical loading conditions. The effects played by temperature rise, applied voltage,stacking sequence, the character of in-plane boundary conditions, as well as initial geometric imperfections are studied.

  17. Effect of compressive force on unbinding specific protein-ligand complexes with force spectroscopy.

    Science.gov (United States)

    Bowers, Carleen M; Carlson, David A; Rivera, Monica; Clark, Robert L; Toone, Eric J

    2013-05-01

    Atomic force microscopy (AFM) is used extensively for the investigation of noncovalent molecular association. Although the technique is used to derive various types of information, in almost all instances the frequency of complex formation, the magnitude of rupture forces, and the shape of the force-distance curve are used to determine the behavior of the system. We have used AFM to consider the effect of contact force on the unbinding profiles of lactose-galectin-3, as well as the control pairs lactose-KDPG aldolase, and mannose-galectin-3, where the interacting species show negligible solution-phase affinity. Increased contact forces (>250 pN) resulted in increased probabilitites of binding and decreased blocking efficiencies for the cognate ligand-receptor pair lactose-G3. Increased contact force applied to two control systems with no known affinity, mannose-G3 and lactose-KDPG aldolase, resulted in nonspecific ruptures that were indistinguishable from those of specific lactose-G3 interactions. These results demonstrate that careful experimental design is vital to the production of interpretable data, and suggest that contact force minimization is an effective technique for probing the unbinding forces and rupture lengths of only specific ligand-receptor interactions. PMID:23537272

  18. Effect of axial magnetic field variations on asymmetry-induced transport in a non-neutral plasma trap

    International Nuclear Information System (INIS)

    It has been suggested that magnetically trapped particles play a role in the asymmetry-induced radial transport observed in the Occidental non-neutral plasma trap. This magnetic trapping would occur due to a small increase (β≡δB/B≅0.4%) in magnetic field at the center of our solenoid and would keep low velocity particles confined to the ends of the trap. To test this suggestion, three coils of additional windings have been added to the trap solenoid thus allowing adjustment of the axial field variation δB. The effect of these adjustments on typical radial flux resonances is investigated. Making B as uniform as possible reduces β by a factor of 5.9, but this produces little change in the transport. Varying β over the broader range from -8.5% to 9.5% gives variations of 20%-90% in the magnitude, peak frequency, and width of the flux resonances, but these variations do not match the predictions of a simple model of trapped particle transport based on isotropic particle distributions

  19. Study of Sweep and Induced Dihedral Effects in Subsonic Axial Flow Compressor Passages—Part I: Design Considerations—Changes in Incidence, Deflection, and Streamline Curvature

    Directory of Open Access Journals (Sweden)

    P. V. Ramakrishna

    2009-01-01

    Full Text Available This article presents the study of Tip Chordline Sweeping (TCS and Axial Sweeping (AXS of low-speed axial compressor rotor blades against the performance of baseline unswept rotor (UNS for different tip clearance levels. The first part of the paper discusses the changes in design parameters when the blades are swept, while the second part throws light on the effect of sweep on tip leakage flow-related phenomena. 15 domains are studied with 5 sweep configurations (0∘, 20∘ TCS, 30∘ TCS, 20∘ AXS, and 30∘ AXS and for 3 tip clearances (0.0%, 0.7%, and 2.7% of the blade chord. A commercial CFD package is employed for the flow simulations and analysis. Results are well validated with experimental data. Forward sweep reduced the flow incidences. This is true all over the span with axial sweeping while little higher incidences below the mid span are observed with tip chordline sweeping. Sweeping is observed to lessen the flow turning. AXS rotors demonstrated more efficient energy transfer among the rotors. Tip chordline sweep deflected the flow towards the hub while effective positive dihedral induced with axial sweeping resulted in outward deflection of flow streamlines. These deflections are more at lower mass flow rates.

  20. Effect of adrenergic receptor ligands on metaiodobenzylguanidine uptake and storage in neuroblastoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Babich, J.W. [Division of Nuclear Medicine, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts (United States)]|[Department of Radiology, Harvard Medical School, Boston, Massachusetts (United States); Graham, W. [Division of Nuclear Medicine, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts (United States); Fischman, A.J. [Division of Nuclear Medicine, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts (United States)]|[Department of Radiology, Harvard Medical School, Boston, Massachusetts (United States)

    1997-05-01

    The effects of adrenergic receptor ligands on uptake and storage of the radiopharmaceutical [{sup 125}I]metaiodobenzylguanidine (MIBG) were studied in the human neuroblastoma cell line SK-N-SH. For uptake studies, cells were with varying concentrations of {alpha}-agonist (clonidine, methoxamine, and xylazine), {alpha}-antagonist (phentolamine, tolazoline, phenoxybenzamine, yohimbine, and prazosin), {beta}-antagonist (propranolol, atenolol), {beta}-agonist (isoprenaline and salbutamol), mixed {alpha}/{beta} antagonist (labetalol), or the neuronal blocking agent guanethidine, prior to the addition of [{sup 125}I]MIBG (0.1 {mu}M). The incubation was continued for 2 h and specific cell-associated radioactivity was measured. For the storage studies, cells were incubated with [{sup 125}I]MIBG for 2 h, followed by replacement with fresh medium with or without drug (MIBG, clonidine, or yohimbine). Cell-associated radioactivity was measured at various times over the next 20 h. Propanolol reduced [{sup 125}I]MIBG uptake by approximately 30% (P<0.01) at all concentrations tested, most likely due to nonspecific membrane changes. In conclusion, the results of this study establish that selected adrenergic ligands can significantly influence the pattern of uptake and storage of MIBG in cultured neuroblastoma cells, most likely through inhibition of uptake or through noncompetitive inhibition. The potential inplications of these findings justify further study. (orig./VHE). With 4 figs., 1 tab.

  1. Effect of fluorescently labeling protein probes on kinetics of protein-ligand reactions.

    Science.gov (United States)

    Sun, Y S; Landry, J P; Fei, Y Y; Zhu, X D; Luo, J T; Wang, X B; Lam, K S

    2008-12-01

    We studied the effect of fluorescently labeling proteins on protein-ligand reactions. Unlabeled ligands (streptavidin-binding peptides and rabbit immunoglobulin G (IgG) as antigen targets) are immobilized on epoxy-functionalized glass slides. Unlabeled and Cy3-labeled protein probes from the same batch (streptavidin and goat antibodies) subsequently react with the surface-immobilized targets. By monitoring in situ the surface mass density change using an oblique-incidence reflectivity difference scanning microscope (a label-free detector), we measured k(on) and k(off) for streptavidin-peptide reactions and antibody-antigen reaction. We found that (1) equilibrium dissociation constants, defined as K(D) = k(off)/k(on), for streptavidin-peptide reactions increases by a factor of 3-4 when the solution-phase streptavidin is labeled with Cy3 dye and (2) K(D) for reactions of solution-phase goat anti-rabbit antibodies with rabbit IgG targets also change significantly when the goat antibodies are labeled with Cy3 dye. PMID:18991423

  2. Axial velocity in decaying swirl flow

    Science.gov (United States)

    Algifri, A. H.; Bhardwaj, R. K.; Rao, Y. V. N.

    1988-09-01

    Experiments were carried out on turbulent swirling flow with variable initial swirl at different flow rates to study the effect of swirl on axial velocity. A correlation was made between the defect in the swirling flow axial velocity and the swirl number which locally defines the swirl intensity. An expression which can be used to predict the axial velocity distribution of turbulent swirling flow in a pipe is presented.

  3. Sensorless Control of Axial Magnetic Bearings

    Science.gov (United States)

    Atsumo, Daichi; Yoshida, Toshiya; Ohniwa, Katsumi

    This paper describes a sensorless control method of axial active magnetic bearings (AMBs). At high frequencies, inductance of the axial electromagnets is hardly dependent on the airgap because of the eddy current effects of the non-laminated core. Therefore the carrier frequency should be 3 kHz below to improve the sensitivity to the airgap. In the experiment, Sensorless controll of the axial AMBs have been achieved.

  4. The Effect of Precursor Ligands and Oxidation State in the Synthesis of Bimetallic Nano-Alloys

    KAUST Repository

    LaGrow, Alec P.

    2015-05-12

    The characteristics of bimetallic nanomaterials are dictated by their size, shape and elemental distribution. Solution synthesis is widely utilized to form nanomaterials, such as nanoparticles, with controlled size and shape. However, the effects of variables on the characteristics of bimetallic nanomaterials are not completely understood. In this study, we used a continuous-flow synthetic strategy to explore the effects of the ligands and the oxidation state of a metal precursor in a shape-controlled synthesis on the final shape of the nanomaterials and the elemental distribution within the alloy. We demonstrate that this strategy can tune the size of monodisperse PtM (M=Ni or Cu) alloy nanocrystals ranging from 3 to 16 nm with an octahedral shape using acetylacetonate or halide precursors of Pt(II), Pt(IV) and Ni or Cu (II). The nanoparticles formed from halide precursors showed an enrichment of platinum on their surfaces, and the bromides could oxidatively etch the nanoparticles during synthesis with the O2/Br- pair. The two nanocrystal precursors can be uti-lized independently and can control the size with a trend of Pt(acac)2effect of the ligand shell of a precursor during the synthesis of alloy nanoparticles as well as to control, in a scalable manner, the nanomaterial size and surface chemistry.

  5. Effect of a small cylindrical inhomogeneity on the eigenfrequency of a semicylindrical dielectric resonator featuring an axially homogeneous eigenmode

    Science.gov (United States)

    Prokopenko, Yu. V.; Filippov, Yu. F.; Shipilova, I. A.

    2007-09-01

    A semicylindrical dielectric resonator with a thin cylindrical inhomogeneity in the region of the field antinode of a whispering gallery eigenmode has been studied. Characteristic equations determining the complex eigenfrequencies of such resonators with axially homogeneous eigenmodes are obtained. It is shown that the presence of a dielectric or conducting inhomogeneity leads to a frequency shift and causes additional energy losses of the eigenmode.

  6. Renormalization of myoglobin-ligand binding energetics by quantum many-body effects

    CERN Document Server

    Weber, Cedric; O'Regan, David D; Payne, Mike C

    2014-01-01

    We carry out a first-principles atomistic study of the electronic mechanisms of ligand binding and discrimination in the myoglobin protein. Electronic correlation effects are taken into account using one of the most advanced methods currently available, namely a linear-scaling density functional theory (DFT) approach wherein the treatment of localized iron 3d electrons is further refined using dynamical mean-field theory (DMFT). This combination of methods explicitly accounts for dynamical and multi-reference quantum physics, such as valence and spin fluctuations, of the 3d electrons, whilst treating a significant proportion of the protein (more than 1000 atoms) with density functional theory. The computed electronic structure of the myoglobin complexes and the nature of the Fe-O2 bonding are validated against experimental spectroscopic observables. We elucidate and solve a long standing problem related to the quantum-mechanical description of the respiration process, namely that DFT calculations predict a st...

  7. The effect of ligand-based tautomer and protomer prediction on structure-based virtual screening.

    Science.gov (United States)

    Kalliokoski, Tuomo; Salo, Heikki S; Lahtela-Kakkonen, Maija; Poso, Antti

    2009-12-01

    As tautomerism and ionization may significantly change the interaction possibilities between a ligand and a target protein, these phenomena could have an effect on structure-based virtual screening. Tautomeric- and protonation-state enumeration ensures that the state with optimal interaction possibilities is included in the screening process, as the predicted state may not always be the optimal binder. However, there is very little information published if tautomer and protomer enumeration actually improves the enrichment of active molecules compared to the alternative of using a predicted form of each molecule. In this study, a retrospective virtual screening was performed using AutoDock on 19 drug targets with a publicly available data set. It is proposed that tautomer and protomer prediction can significantly save computing resources and can yield similar results to enumeration. PMID:19928753

  8. Metal-ligand cooperation.

    Science.gov (United States)

    Khusnutdinova, Julia R; Milstein, David

    2015-10-12

    Metal-ligand cooperation (MLC) has become an important concept in catalysis by transition metal complexes both in synthetic and biological systems. MLC implies that both the metal and the ligand are directly involved in bond activation processes, by contrast to "classical" transition metal catalysis where the ligand (e.g. phosphine) acts as a spectator, while all key transformations occur at the metal center. In this Review, we will discuss examples of MLC in which 1) both the metal and the ligand are chemically modified during bond activation and 2) bond activation results in immediate changes in the 1st coordination sphere involving the cooperating ligand, even if the reactive center at the ligand is not directly bound to the metal (e.g. via tautomerization). The role of MLC in enabling effective catalysis as well as in catalyst deactivation reactions will be discussed. PMID:26436516

  9. Steric and electronic effects of 1,3-disubstituted cyclopentadienyl ligands on metallocene derivatives of Cerium, Titanium, Manganese, and Iron

    Energy Technology Data Exchange (ETDEWEB)

    Sofield, C.D.

    2000-05-19

    Sterically demanding 1,3-disubstituted cyclopentadienyl ligands were used to modify the physical properties of the corresponding metallocenes. Sterically demanding ligands provided kinetic stabilization for trivalent cerium compounds. Tris(di-t-butylcyclopentadienyl)cerium was prepared and anion competition between halides and cyclopentadienyl groups which had complicated synthesis of the tris(cyclopentadienyl)compound was qualitatively examined. Bis(di-t-butylcyclopentadienyl)cerium methyl was prepared and its rate of decomposition, by ligand redistribution, to tris(di-t-butylcyclopentadienyl)cerium was shown to be slower than the corresponding rate for less sterically demanding ligands. Asymmetrically substituted ligands provided a symmetry label for examination of chemical exchange processes. Tris[trimethylsilyl(t-butyl)cyclopentadienyl]cerium was prepared and the rate of interconversion between the C1 and C3 isomers was examined. The enthalpy difference between the two distereomers is 7.0 kJ/mol. The sterically demanding cyclopentadienyl ligands ansa-di-t-butylcyclopentadiene (Me2Si[(Me3C)2C5H3]2), ansa-bis(trimethylsilyl)cyclopentadiene (Me2Si[(Me3Si)2C5H3]2) and tetra-t-butylfulvalene and metallocene derivatives of the ligands were prepared and their structures were examined by single crystal X-ray crystallography. The effect that substituents on the cyclopentadienyl ring have on the pi-electron system of the ligand was examined through interaction between ligand and metal orbitals. A series of 1,3-disubstituted manganocenes was prepared and their electronic states were determined by solid-state magnetic susceptibility, electron paramagnetic resonance, X-ray crystallography, and variable temperature UV-vis spectroscopy. Spin-equilibria in [(Me3C)2C5H3]2Mn and [(Me3C)(Me3Si)C5H3]2Mn were examined and indicate an enthalpy difference of 15 kJ/mol between the high-spin and low-spin forms. Cyclopentadienyl groups resistant to intramolecular oxidative addition

  10. Organic Ligand, Competing Cation, and pH Effects on Dissolution of Zinc in Soils

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A series of experiments were conducted to examine the interactive effects of an organic ligand,a competing cation,and pH on the dissolution of zinc(Zn)from three California soils,Maymen sandy loam,Merced clay,and Yolo clay loam.The concentrations of soluble Zn of the three soils were low in a background solution of Ca(NO3)2.Citric acid,a common organic ligand found in the rhizosphere,was effective in mobilizing Zn in these soils; its presence enhanced the concentration of Zn in soil solution by citrate forming a complex with Zn.The ability of Zn to form a complex with citric acid in the soil solution was dependent on the concentration of citric acid,pH,and the concentration of the competing cation Ca2+.The pH of the soil solution determined the extent of desorption of Zn in solid phase in the presence of citric acid.The amounts of Zn released from the solid phase were proportional to the concentration of citric acid and inversely proportional to the concentration of Ca(NO3)2 background solution,which supplied the competing cation Ca2+ for the formation of a complex with citrate.When the soil suspension was spiked with Zn,the adsorption of Zn by the soils was retarded by citric acid via the formation of the soluble Zn-citrate complex.The dissolution of Zn in the presence of citric acid was pH dependent in both adsorption and desorption processes.

  11. Lattice pulling effect and strain relaxation in axial (In,Ga)N/GaN nanowire heterostructures grown on GaN-buffered Si(111) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Kong, X.; Trampert, A. [Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117, Berlin (Germany); Albert, S.; Bengoechea-Encabo, A.; Sanchez-Garcia, M.A.; Calleja, E. [Dpto. Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica, Ciudad Universitaria, 28040, Madrid (Spain)

    2015-04-01

    Transmission electron microscopy and spatially resolved electron energy-loss spectroscopy have been applied to investigate the indium distribution and the interface morphology in axial (In,Ga)N/GaN nanowire heterostructures. The ordered axial (In,Ga)N/GaN nanowire heterostructures with an indium concentration up to 80% are grown by molecular beam epitaxy on GaN-buffered Si(111) substrates. We observed a pronounced lattice pulling effect in all the nanowire samples given in a broad transition region at the interface. The lattice pulling effect becomes smaller and the (In,Ga)N/GaN interface width is reduced as the indium concentration is increased in the (In,Ga)N section. The result can be interpreted in terms of the increased plastic strain relaxation via the generation of the misfit dislocations at the interface. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. The effect of axial and transverse loading on the transport properties of ITER Nb3Sn strands

    Science.gov (United States)

    Nijhuis, A.; Pompe van Meerdervoort, R. P.; Krooshoop, H. J. G.; Wessel, W. A. J.; Zhou, C.; Rolando, G.; Sanabria, C.; Lee, P. J.; Larbalestier, D. C.; Devred, A.; Vostner, A.; Mitchell, N.; Takahashi, Y.; Nabara, Y.; Boutboul, T.; Tronza, V.; Park, S.-H.; Yu, W.

    2013-08-01

    The differences in thermal contraction of the composite materials in a cable in conduit conductor (CICC) for the International Thermonuclear Experimental Reactor (ITER), in combination with electromagnetic charging, cause axial, transverse contact and bending strains in the Nb3Sn filaments. These local loads cause distributed strain alterations, reducing the superconducting transport properties. The sensitivity of ITER strands to different strain loads is experimentally explored with dedicated probes. The starting point of the characterization is measurement of the critical current under axial compressive and tensile strain, determining the strain sensitivity and the irreversibility limit corresponding to the initiation of cracks in the Nb3Sn filaments for axial strain. The influence of spatial periodic bending and contact load is evaluated by using a wavelength of 5 mm. The strand axial tensile stress-strain characteristic is measured for comparison of the axial stiffness of the strands. Cyclic loading is applied for transverse loads following the evolution of the critical current, n-value and deformation. This involves a component representing a permanent (plastic) change and as well as a factor revealing reversible (elastic) behavior as a function of the applied load. The experimental results enable discrimination in performance reduction per specific load type and per strand type, which is in general different for each manufacturer involved. Metallographic filament fracture studies are compared to electromagnetic and mechanical load test results. A detailed multifilament strand model is applied to analyze the quantitative impact of strain sensitivity, intrastrand resistances and filament crack density on the performance reduction of strands and full-size ITER CICCs. Although a full-size conductor test is used for qualification of a strand manufacturer, the results presented here are part of the ITER strand verification program. In this paper, we present an

  13. The effect of axial and transverse loading on the transport properties of ITER Nb3Sn strands

    International Nuclear Information System (INIS)

    The differences in thermal contraction of the composite materials in a cable in conduit conductor (CICC) for the International Thermonuclear Experimental Reactor (ITER), in combination with electromagnetic charging, cause axial, transverse contact and bending strains in the Nb3Sn filaments. These local loads cause distributed strain alterations, reducing the superconducting transport properties. The sensitivity of ITER strands to different strain loads is experimentally explored with dedicated probes. The starting point of the characterization is measurement of the critical current under axial compressive and tensile strain, determining the strain sensitivity and the irreversibility limit corresponding to the initiation of cracks in the Nb3Sn filaments for axial strain. The influence of spatial periodic bending and contact load is evaluated by using a wavelength of 5 mm. The strand axial tensile stress–strain characteristic is measured for comparison of the axial stiffness of the strands. Cyclic loading is applied for transverse loads following the evolution of the critical current, n-value and deformation. This involves a component representing a permanent (plastic) change and as well as a factor revealing reversible (elastic) behavior as a function of the applied load. The experimental results enable discrimination in performance reduction per specific load type and per strand type, which is in general different for each manufacturer involved. Metallographic filament fracture studies are compared to electromagnetic and mechanical load test results. A detailed multifilament strand model is applied to analyze the quantitative impact of strain sensitivity, intrastrand resistances and filament crack density on the performance reduction of strands and full-size ITER CICCs. Although a full-size conductor test is used for qualification of a strand manufacturer, the results presented here are part of the ITER strand verification program. In this paper, we present an

  14. Vectorial versus axial goldstone bosons

    International Nuclear Information System (INIS)

    The Yukawa interactions of fermions with Goldstone bosons are given in closed form for an arbitrary renormalizable field theory to all orders of perturbation theory or for a general effective Lagrangian. Although the diagonal couplings are always pseudoscalar there is an important difference between spontaneously broken vector and axial-vector global symmetries. Compared to the axial case, the diagonal douplings of 'vectorial' Goldstone bosons to charged fermions are suppressed by mixing angles or appear only via radiative corrections involving gauge fields. This general result may be relevant for the problem of flavour symmetry breaking in composite models. (Author)

  15. Origin of axial current in scyllac

    International Nuclear Information System (INIS)

    The origin of the axial current observed in Scyllac (a high beta stellarator experiment) is discussed. A shaped coil and/or helical winding produce rotational transform which links magnetic lines of force to the plasma column and the axial current is induced electromagnetically. This phenomenon is inherent in a pulsed high-beta stellarator. The rotational transform produced by the induced axial current is much smaller than that associated with the l = 1, 0 equilibrium fields. The effect of the axial current on the equilibrium and stability of the plasma column is thus small. It is also shown that the magnetic field shear near a plasma surface is very strong

  16. Inhibitory effect on hepatitis B virus in vitro by a peroxisome proliferator-activated receptor-{gamma} ligand, rosiglitazone

    Energy Technology Data Exchange (ETDEWEB)

    Wakui, Yuta; Inoue, Jun [Division of Gastroenterology, Tohoku University Graduate School of Medicine, 1-1 Seiryo, Aobaku, Sendai 980-8574 (Japan); Ueno, Yoshiyuki, E-mail: yueno@mail.tains.tohoku.ac.jp [Division of Gastroenterology, Tohoku University Graduate School of Medicine, 1-1 Seiryo, Aobaku, Sendai 980-8574 (Japan); Fukushima, Koji; Kondo, Yasuteru; Kakazu, Eiji; Obara, Noriyuki; Kimura, Osamu; Shimosegawa, Tooru [Division of Gastroenterology, Tohoku University Graduate School of Medicine, 1-1 Seiryo, Aobaku, Sendai 980-8574 (Japan)

    2010-05-28

    Although chronic infection of hepatitis B virus (HBV) is currently managed with nucleot(s)ide analogues or interferon-{alpha}, the control of HBV infection still remains a clinical challenge. Peroxisome proliferator-activated receptor (PPAR) is a ligand-activated transcription factor, that plays a role in glucose and lipid metabolism, immune reactions, and inflammation. In this study, the suppressive effect of PPAR ligands on HBV replication was examined in vitro using a PPAR{alpha} ligand, bezafibrate, and a PPAR{gamma} ligand, rosiglitazone. The effects were examined in HepG2 cells transfected with a plasmid containing 1.3-fold HBV genome. Whereas bezafibrate showed no effect against HBV replication, rosiglitazone reduced the amount of HBV DNA, hepatitis B surface antigen, and hepatitis B e antigen in the culture supernatant. Southern blot analysis showed that the replicative intermediates of HBV in the cells were also inhibited. It was confirmed that GW9662, an antagonist of PPAR{gamma}, reduced the suppressive effect of rosiglitazone on HBV. Moreover, rosiglitazone showed a synergistic effect on HBV replication with lamivudine or interferon-{alpha}-2b. In conclusion, this study showed that rosiglitazone inhibited the replication of HBV in vitro, and suggested that the combination therapy of rosiglitazone and nucleot(s)ide analogues or interferon could be a therapeutic option for chronic HBV infection.

  17. Tetrad effect in free energy changes of mixed ligand lanthanide-phenanthrdine-amino acid complexes

    International Nuclear Information System (INIS)

    The presence of tetrad effect has been investigated in the free energy changes accompanying the formation of lanthanide(III) mixed ligand complexes of the type [Ln(III). phen. L], where Ln(III)=La3+, Ce3+, Pr3+, Nd3+. Sm3+, Eu3+, Gd3+, Tb3+, Dy3+ or Er3+; phen= o-phenanthroline; L=histidine, β-phenyl alanine or tryptophan. The free energy changes Δ Gsub(MAL)sup(MA) have been computed from the formation constants log Ksub(MAL)sup(MA) determined pH-metrically by using, the Irving-Rossotti approach at 25degC and at ionic strength, I=0.2(mol dm-3, KNO3). The presence of tetrad effect has been demonstrated by Δ Gsub(MAL)sup(MA) vs 4fsup(n) plots, straight line approximation method, differential plot method and inclined W systematics. The magnitude of the effect has been found to lie in the sequence 4f7>4f3 - 4f4 ∼ 4f10 which constitutes an experimental evidence in favour of inter-electronic repulsion theory of tetrad effect. (author). 23 refs., 4 figs

  18. Effect of biquadratic exchange on the axial Heisenberg model: Application to the magnetic phase transitions in UNi2Si2

    International Nuclear Information System (INIS)

    The influence of biquadratic exchange on the Heisenberg model with strong axial anisotropy is examined for the case of spins on a body-centered tetragonal lattice with competing bilinear exchange interactions along the c axis. Contrary to the usual axial next-nearest-neighbor Ising model with third-neighbor exchange also included, a low-temperature spin-wave calculation reveals that biquadratic exchange can stabilize the sequence of phases period 3→period 2. Mean-field analysis, with support from Monte Carlo simulations, suggests a higher-temperature transition to an incommensurate state. This sequence of phase transitions has recently been observed in UNi2Si2. The importance of fluctuations is emphasized

  19. Effects of rotating stall and surge on the first rotor blade row in a six stage industrial axial flow compressor

    Energy Technology Data Exchange (ETDEWEB)

    Eisenberg, B.; Thomas, P.; Turanskyj, L.

    1995-12-31

    A six stage speed controlled research compressor representing the front section of an industrial axial flow compressor was fitted with a new wide chord controlled-diffusion-airfoil-bladed 1st stage rotor blade row. In order to check mechanical behaviour of this blade type when effected by rotating stall and surge the first stage blading was equipped with strain gauges. As the presence of rotating-stall changes also frequency spectrum of shaft vibration the output signals of three different types of transducers - i.e. strain gauge, dynamic wall pressure and shaft vibration - are compared. Rotating stall was detected by fast fourier transform (FFT) analysis of the pressure transducer`s output signal. In some cases a change of shaft vibration signals was observed. The compressor has a relatively small area of rotating stall which is located below 50% speed. Strain gauge measurements show a comapratively low stress level induced by rotating stall and surge in the first rotor blade row. Results of measurements taken during transient start-up and shut-down with different throttle valve positions behind the compressor are presented as well. (orig.) [Deutsch] Ein 6-stufiger drehzahlgeregelter Versuchskompressor, der dem vorderen Teil eines Industrie-Axialkompressors entspricht, wurde in der 1. Laufschaufelreihe mit einer neuen Breitschaufel mit `Controlled-diffusion`-Profilen versehen. Zur Ueberpruefung des mechanischen Verhaltens dieser neuen Beschaufelung im Kennfeld - insbesondere bei Auftreten von `Rotating-Stall` - wurden auf die Laufschaufeln Dehnungsmessstreifen appliziert. Da das Autreten von `Rotating-Stall` auch das Frequenzspektrum der Wellenschwingungen beeinflusst, wurden die Signale dreier verschiedener Aufnehmertypen - Dehnungsmessstreifen, dynamischer Wanddruck und Wellenschwingungen - verglichen. Das Auftreten von `Rotating-Stall` wurde ueber eine Frequenzanalyse des Ausgangssignals der dynamischen Wanddruckaufnehmer indiziert. In einigen Faellen wurde

  20. Computational fluid dynamics simulations of blade damage effect on the performance of a transonic axial compressor near stall

    OpenAIRE

    Li, Y.; Sayma, A. I.

    2014-01-01

    Gas turbine axial compressor blades may encounter damage during service for various reasons such as damage by debris from casing or foreign objects impacting the blades, typically near the rotor’s tip. This may lead to deterioration of performance and reduction in the surge margin. The damage breaks the cyclic symmetry of the rotor assembly; thus, computational fluid dynamics simulations have to be performed using full annulus compressor assembly. Moreover, downstream boundary conditions are ...

  1. Effects of the nuclear symmetry energy on gravitational waves from the axial W-modes of isolated neutron stars

    International Nuclear Information System (INIS)

    The frequencies and damping times of the axial w-mode oscillations of neutron stars are investigated using a nuclear equation of state (EOS) partially constrained by the available terrestrial laboratory data. It is found that the nuclear symmetry energy Esym(ρ), especially its high density behavior, plays an important role in determining both the eigen-frequencies and the damping times of these oscillations. (author)

  2. The Effect of the Electron-Beam Parameter Spread on Microwave Generation in a Three-Cavity Axial Vircator

    Science.gov (United States)

    Gurnevich, Evgeny; Molchanov, Pavel

    2015-04-01

    The behavior of the generation efficiency and radiation spectrum of a three-cavity axial vircator versus the radius of the injected electron beam, its impedance and energy homogeneity is studied. This paper establishes that for each geometry of a three-cavity resonator, there exist the optimal (maximizing the generation efficiency) values of these parameters and determines the range within which they may vary without losing the efficiency of generation.

  3. The effect of the electron-beam parameter spread on microwave generation in a three-cavity axial vircator

    OpenAIRE

    Gurnevich, E. A.; Molchanov, P. V.

    2014-01-01

    The behavior of the generation efficiency and radiation spectrum of a three-cavity axial vircator versus the radius of the injected electron beam, its impedance and energy homogeneity is studied. This paper establishes that for each geometry of a three-cavity resonator, there exist the optimal (maximizing the generation efficiency) values of these parameters and determines the range within which they may vary without losing the efficiency of generation.

  4. Spiral Vortices and Taylor Vortices in the Annulus between Rotating Cylinders and the Effect of an Axial Flow

    CERN Document Server

    Hoffmann, C; Pinter, A; Hoffmann, Ch.

    2004-01-01

    We present numerical simulations of vortices that appear via primary bifurcations out of the unstructured circular Couette flow in the Taylor-Couette system with counter-rotating as well as with co-rotating cylinders. The full, time dependent Navier-Stokes equations are solved with a combination of a finite difference and a Galerkin method for a fixed axial periodicity length of the vortex patterns and for a finite system of aspect ratio 12 with rigid nonrotating ends in a setup with radius ratio eta=0.5. Differences in structure, dynamics, symmetry properties, bifurcation and stability behavior between spiral vortices with azimuthal wave numbers M=+-1 and M=0 Taylor vortices are elucidated and compared in quantitative detail. Simulations in axially periodic systems and in finite systems with stationary rigid ends are compared with experimental spiral data. In a second part of the paper we determine how the above listed properties of the M=-1,0,1 vortex structures are changed by an externally imposed axial th...

  5. No effect of different estrogen receptor ligands on cognition in adult female monkeys.

    Science.gov (United States)

    Lacreuse, Agnès; Wilson, Mark E; Herndon, James G

    2009-03-01

    Many studies in women and animal models suggest that estrogens affect cognitive function. Yet, the mechanisms by which estrogens may impact cognition remain unclear. The goal of the present study was to assess the effects of different estrogen receptor (ER) ligands on cognitive function in adult ovariectomized female rhesus monkeys. The monkeys were tested for 6 weeks on a battery of memory and attentional tasks administered on a touchscreen: the object, face, and spatial versions of the Delayed Recognition Span Test (DRST) and a Visual Search task. Following a 2-week baseline period with oil vehicle treatment, monkeys were randomly assigned to one of 3 treatment groups: estradiol benzoate (EB), selective ERbeta agonist (diarylpropionitrile DPN) or selective ER modulator tamoxifen (TAM). In each treatment group, monkeys received oil vehicle for 2 weeks and the drug for 2 weeks, in a cross-over design. After a 4-week washout, a subset of monkeys was re-tested on the battery when treated with a selective ERalpha agonist (propyl-pyrazole-triol, PPT) or oil vehicle. Overall, drug treatments had no or negligible effects on cognitive performance. These results support the contention that exogenous estrogens and selective estrogen receptor modulators (SERMS) do not significantly affect cognition in young adult female macaques. Additional studies are needed to determine whether the cognitive effects of estrogens in monkeys of more advanced age are mediated by ERbeta, ERalpha or complex interactions between the two receptors. PMID:19101578

  6. Aryl hydrocarbon receptor ligand effects in RBL2H3 cells

    DEFF Research Database (Denmark)

    Maaetoft-Udsen, Kristina; Shimoda, Lori M. N.; Frøkiær, Hanne;

    2012-01-01

    responses and release a spectrum of pro-inflammatory mediators including histamine, mast cell proteases, and pro-inflammatory cytokines such as IL-6 upon stimulation. The aim was to investigate the AHR in model mast cells and examine how both putative and known AHR ligands, e.g., kynurenine, kynurenic acid...... (KA), Resveratrol, indolmycin, and violacein, affect mast cell activation and signaling. These ligands were tested on calcium signaling, degranulation, and gene expression. The data show that AHR is present in three model mast cell lines, and that various known and putative AHR ligands regulate gene...

  7. Ultrafast singlet-singlet energy transfer in self-assembled via metal-ligand axial coordination of free-base porphyrin-zinc phthalocyanine and free-base porphyrin-zinc naphthalocyanine dyads.

    Science.gov (United States)

    Maligaspe, Eranda; Kumpulainen, Tatu; Lemmetyinen, Helge; Tkachenko, Nikolai V; Subbaiyan, Navaneetha K; Zandler, Melvin E; D'Souza, Francis

    2010-01-14

    Singlet-singlet energy transfer in self-assembled via axial coordination of imidazole-appended (at different positions of one of the meso-phenyl entities) free-base tetraphenylporphyrin, H(2)PIm, to either zinc phthalocyanine, ZnPc, or zinc naphthalocyanine, ZnNc, dyads is investigated in noncoordinating solvents, o-dichlorobenzene and toluene, using both steady-state and time-resolved transient absorption techniques. The newly formed supramolecular dyads were fully characterized by spectroscopic, computational, and electrochemical methods. The binding constants measured from optical absorption spectral data were found to be in the range of 10(4)-10(5) M(-1) for the 1:1 dyads, suggesting fairly stable complex formation. Electrochemical and computational studies suggested that photoinduced electron transfer is a thermodynamically unfavorable process when free-base porphyrin is excited in these dyads. Selective excitation of the donor free-base porphyrin entity was possible in both types of dyads formed by either of the ZnPc or ZnNc energy acceptors. Efficient singlet-singlet energy transfer was observed in these dyads, and the position of imidazole linkage on the free-base porphyrin entity, although flexible, seems to have some control over the overall efficiency of excited energy transfer process. Kinetics of energy transfer was monitored by performing transient absorption measurements using both up-conversion and pump-probe techniques. Such studies revealed ultrafast singlet-singlet energy transfer in the studied dyads with time constants on the order of 2-25 ps depending upon the type of the dyad. PMID:19928821

  8. The Effects of Ozone and Organic Ligands on Manganese Speciation in Surface Seawater

    Science.gov (United States)

    Smyth, A. M.; Liss, P. S.; Chapman, P.; Yvon-Lewis, S. A.

    2013-12-01

    Manganese is a co-limiting nutrient for primary production in certain regions of the ocean and its bioavailability is strongly controlled by its redox state, with Mn(II) being the more bioavailable form. In turn, that redox state is affected by the presence of strong oxidizers or reducers, as well as the organic ligands bound to the metal. While it is expected that ozone reacting directly with Mn will result in an oxidation of the metal, ozone and the products of its decomposition in water reacting with organically complexed Mn could result in a reduction of the metal. In this study we investigate the effect of tropospheric ozone, an atmospheric pollutant, on Mn speciation in seawater with different dissolved organic carbon concentrations and compositions. This was done by exposing seawater to ambient levels of ozone and measuring the change in Mn(II) concentrations over time. Samples were filtered to separate solid Mn(IV) from dissolved Mn(II) and the dissolved Mn(II) was measured using flow injection analysis chemiluminescence. We will present results detailing the effect of ozone deposition and dissolved organic carbon concentration and composition on Mn speciation in seawater.

  9. Effect of Temperature on the Protonation of the TALSPEAK Ligands: Lactic and Diethylenetrinitropentaacetic Acids

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Guoxin; Rao, Linfeng

    2009-10-20

    The protonation reactions of two ligands that play important roles in the TALSPEAK process for the separation of trivalent actinides from lanthanides, lactic acid and diethylenetrinitropentaacetic acid (DTPA), have been studied at variable temperatures. The protonation constants at 10-70 C were determined by titration potentiometry and the protonation enthalpies were determined at 25 C by titration microcalorimetry. The protonation constants remain essentially unchanged (25-70 C) within the experimental uncertainties, indicating that the effect of temperature on the protonation of lactate is insignificant. In contrast, the protonation constants of DTPA (log {beta}H's) generally decrease as the temperature is increased. Results from this study indicate that the effect of temperature on the protonation of DTPA could alter the speciation of metal ions (actinides and lanthanides) in the TALSPEAK system, since lower values of log{beta}H at higher temperatures suggest that the hydrogen ions would compete less strongly with the metal ions for the complexation of DTPA at higher temperatures.

  10. Effect of Temperature on the Protonation of the TALSPEAK Ligands: Lactic and Diethylenetrinitropentaacetic Acids

    International Nuclear Information System (INIS)

    The protonation reactions of two ligands that play important roles in the TALSPEAK process for the separation of trivalent actinides from lanthanides, lactic acid and diethylenetrinitropentaacetic acid (DTPA), have been studied at variable temperatures. The protonation constants at 10-70 C were determined by titration potentiometry and the protonation enthalpies were determined at 25 C by titration microcalorimetry. The protonation constants remain essentially unchanged (25-70 C) within the experimental uncertainties, indicating that the effect of temperature on the protonation of lactate is insignificant. In contrast, the protonation constants of DTPA (log βH's) generally decrease as the temperature is increased. Results from this study indicate that the effect of temperature on the protonation of DTPA could alter the speciation of metal ions (actinides and lanthanides) in the TALSPEAK system, since lower values of logβH at higher temperatures suggest that the hydrogen ions would compete less strongly with the metal ions for the complexation of DTPA at higher temperatures.

  11. The effect of "on/off" molecular switching on the photophysical and photochemical properties of axially calixarene substituted activatable silicon(iv)phthalocyanine photosensitizers.

    Science.gov (United States)

    Güngör, Ömer; Altınbaş Özpınar, Gül; Durmuş, Mahmut; Ahsen, Vefa

    2016-05-01

    Silicon(iv) phthalocyanines ( and ) bearing two calixarene groups as axial ligands were synthesized. Surprisingly, both phthalocyanines were obtained as two different isomers ( and ) depending on the distance between calixarene benzene groups and the phthalocyanine ring. DFT and TD-DFT computations were performed to model plausible structures of these isomers and to simulate electronic absorption spectra. These isomers converted into each other depending on the polarity of the used solvent, temperature and light irradiation. The photophysical and photochemical properties of each isomer were investigated in dimethylsulfoxide (DMSO) for the determination of photodynamic therapy (PDT) activities of these compounds. The more blue-shifted isomers ( and ) showed higher fluorescence quantum yields and singlet oxygen generation compared to more red-shifted counterparts ( and ). This behavior is extremely important for developing activatable photosensitizers for cancer treatment by PDT. Although these photosensitizers produce lower singlet oxygen in normal cells, they produce higher singlet oxygen (six times higher for ) in cancer cells since these photosensitizers converted to more blue-shifted isomers by using light irradiation. PMID:27052992

  12. ASSESSMENT OF COCAINE-LIKE DISCRIMINATIVE STIMULUS EFFECTS OF DOPAMINE D-3 RECEPTOR LIGANDS

    NARCIS (Netherlands)

    ACRI, JB; CARTER, [No Value; ALLING, K; GETERDOUGLASS, B; DIJKSTRA, D; WIKSTROM, H; KATZ, JL; WITKIN, JM

    1995-01-01

    The highly selective dopamine D-3 receptor ligand, (+)-PD 128907 4aR10bR-(+)-trans-3,4,4a,10b-tetrahydro-4-n-propyl- 2H5H[4,3-b]-1,4-oxazin-9-ol), and other dopamine D-3 receptor ligands, (+/-)-7-hydroxy-2-(N,N-di-n-propylamino)tetralin and (+)-7-hydroxy-2-(N,N-di-n-propylamino)tetralin, substituted

  13. Reactivity and effectiveness of traditional and novel ligands for multi-micronutrient fertilization in a calcareous soil.

    Science.gov (United States)

    López-Rayo, Sandra; Nadal, Paloma; Lucena, Juan J

    2015-01-01

    This study compares the effectiveness of multi-micronutrient formulations containing iron (Fe), manganese (Mn), and zinc (Zn) with traditional (EDTA, DTPA, HEEDTA, and EDDHAm) or novel chelates (o,p-EDDHA, S,S-EDDS, and IDHA) and natural complexing agents (gluconate and lignosulfonate). The stability and reactivity of the formulations were studied on batch experiments with calcareous soil and by speciation modeling. Formulations containing traditional ligands maintained higher Mn but lower Zn concentration in soil solution than the novel ligands. The gluconate and lignosulfonate maintained low concentrations of both Mn and Zn in soil solution. Selected formulations were applied into calcareous soil and their efficacy was evaluated in a pot experiment with soybean. The formulation containing DTPA led to the highest Zn concentration in plants, as well as the formulation containing S,S-EDDS in the short-term, which correlated with its biodegradability. The application of traditional or novel ligands in formulations did not result in sufficient plant Mn concentrations, which was related to the low Mn stability observed for all formulations under moderate oxidation conditions. The results highlight the need to consider the effect of metals and ligands interactions in multi-nutrient fertilization and the potential of S,S-EDDS to be used for Zn fertilization. Furthermore, it is necessary to explore new sources of Mn fertilization for calcareous soils that have greater stability and efficiency, or instead to use foliar fertilization. PMID:26442065

  14. Thiopalmitoylation of altered peptide ligands enhances their protective effects in an animal model of multiple sclerosis.

    Science.gov (United States)

    Cloake, Nancy C; Beaino, Wissam; Trifilieff, Elisabeth; Greer, Judith M

    2014-03-01

    Previously, we have shown that conjugation of a palmitic chain via a thioester bond to a cysteine residue in weakly or nonencephalitogenic or neuritogenic peptides markedly enhances their ability to induce autoimmune disease in an MHC class II-restricted manner. From those studies, however, it was not clear whether thiopalmitoylation of the peptides was merely enhancing their disease-inducing potential or whether the lipid was itself playing a pathogenic role. To investigate this further, we have now tested the effects of thiopalmitoylation on MHC class II-restricted altered peptide ligands (APLs), which are normally protective in experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis. We hypothesized that if thiopalmitoylation of a peptide merely enhances its innate potential, then thiopalmitoylated APLs (S-palmAPLs) should show enhanced protective effects. Alternatively, if thiopalmitoylation itself can make a peptide pathogenic, then S-palmAPLs should have decreased therapeutic potential. We synthesized APLs and corresponding S-palmAPLs and showed that the S-palmAPLs were much more effective than the nonconjugated APL at inhibiting the development of experimental autoimmune encephalomyelitis. This was due to several features of the S-palmAPL:S-palmAPL-primed cells show an enhanced ability to proliferate and produce the anti-inflammatory cytokine, IL-10, in vitro. Furthermore, the bioavailability of S-palmAPL was greatly enhanced, compared with the nonpalmitoylated APL, and S-palm APL was taken up more rapidly into dendritic cells and channeled into the MHC class II processing pathway. These results show that thiopalmitoylation of MHC class II-restricted peptides is a simple way to enhance their effects in vivo and could have wide therapeutic application. PMID:24489099

  15. Research on Effect Factors of Axial Stiffness of Metallic W-ring%W形金属密封环轴向刚度影响因素研究

    Institute of Scientific and Technical Information of China (English)

    索双富; 邢敏杰; 薛庆; 王晨希

    2016-01-01

    W形金属密封环的轴向刚度与其密封效果关系紧密,合理选择其轴向刚度是进行系统结构与参数优化的基础。应用ANSYS软件计算W形密封环的轴向刚度,研究密封环结构参数(壁厚、波高、波峰半径、波谷半径和密封环外径)、波层和温度对密封环轴向刚度的影响规律。结果表明: W形金属密封环轴向刚度与波高、波峰半径、波谷半径、层数以及温度呈反比关系,与壁厚和外径呈正比关系;壁厚和波高变化对密封环轴向刚度影响显著,在W形密封环设计过程中要考虑其壁厚与波高大小;金属W形密封环的多层结构比单层结构的补偿能力更强,在对补偿性要求高的场合,优先选择多层W形密封环;金属W形密封环轴向刚度与温度呈反比,高温环境下工作的金属W形密封环还需要考虑密封环强度。%The axial stiffness of metallic W⁃ring and the sealing effect are closely related,and choosing suitable axial stiff⁃ness of W⁃ring is the foundation of optimization of system structure and parameters.The axial stiffness of W⁃ring was calcu⁃lated by using ANSYS software, and the effect of structure parameters ( as wall thickness, wave height, radius of wave trough,radius of wave peak and diameter of sealing ring) ,layers and temperature on the axial stiffness of metallic W⁃ring was researched.The results show that the axial stiffness of metallic W⁃ring is inversely proportional to wave height,radius of wave trough,radius of wave peak,layers and temperature,and is proportional to wall thickness and diameter of sealing ring. The wall thickness and wave height have a great effect on the axial stiffness of metallic W⁃ring,so the wall thickness and wave height should be taken into account in the metallic W⁃ring design.Compared to single layer structure,multilayer struc⁃ture metallic W⁃ring has better compensation performance,multilayer structure metallic

  16. Effect of Radial and Axial Deformation on Electron Transport Properties in a Semiconducting Si-C Nanotube

    Directory of Open Access Journals (Sweden)

    S. Choudhary

    2011-01-01

    Full Text Available We study the bias voltage dependent current characteristic in a deformed (8, 0 silicon carbide nanotube by applying self consistent non-equilibrium Green’s function formalism in combination with the density-functional theory to a two probe molecular junction constructed from deformed nanotube. The transmission spectra and electron density of states at zero bias shows a significant reduction in threshold in the case of both radially compressed and axially elongated nanotube. However, semiconductor to metal transition was not observed, though the results show large differences in current characteristic compared to a perfect nanotube.

  17. Effects of various cannabinoid ligands on choice behaviour in a rat model of gambling.

    Science.gov (United States)

    Gueye, Aliou B; Trigo, Jose M; Vemuri, Kiran V; Makriyannis, Alexandros; Le Foll, Bernard

    2016-04-01

    It is estimated that 0.6-1% of the population in the USA and Canada fulfil the Diagnostic and Statistical Manual of Mental Disorders, 5th ed. (DSM-5) criteria for gambling disorders (GD). To date, there are no approved pharmacological treatments for GD. The rat gambling task (rGT) is a recently developed rodent analogue of the Iowa gambling task in which rats are trained to associate four response holes with different magnitudes and probabilities of food pellet rewards and punishing time-out periods. Similar to healthy human volunteers, most rats adopt the optimal strategies (optimal group). However, a subset of animals show preference for the disadvantageous options (suboptimal group), mimicking the choice pattern of patients with GD. Here, we explored for the first time the effects of various cannabinoid ligands (WIN 55,212-2, AM 4113, AM 630 and URB 597) on the rGT. Administration of the cannabinoid agonist CB1/CB2 WIN 55,212-2 improved choice strategy and increased choice latency in the suboptimal group, but only increased perseverative behaviour, when punished, in the optimal group. Blockade of CB1 or CB2 receptors or inhibition of fatty-acid amide hydrolase did not affect rGT performance. These results suggest that stimulation of cannabinoid receptors could affect gambling choice behaviours differentially in some subgroups of subjects. PMID:26905189

  18. Effects of various cannabinoid ligands on choice behaviour in a rat model of gambling

    Science.gov (United States)

    Gueye, Aliou B.; Trigo, Jose M.; Vemuri, Kiran V.; Makriyannis, Alexandros

    2016-01-01

    It is estimated that 0.6–1% of the population in the USA and Canada fulfil the Diagnostic and Statistical Manual of Mental Disorders, 5th ed. (DSM-5) criteria for gambling disorders (GD). To date, there are no approved pharmacological treatments for GD. The rat gambling task (rGT) is a recently developed rodent analogue of the Iowa gambling task in which rats are trained to associate four response holes with different magnitudes and probabilities of food pellet rewards and punishing time-out periods. Similar to healthy human volunteers, most rats adopt the optimal strategies (optimal group). However, a subset of animals show preference for the disadvantageous options (suboptimal group), mimicking the choice pattern of patients with GD. Here, we explored for the first time the effects of various cannabinoid ligands (WIN 55,212-2, AM 4113, AM 630 and URB 597) on the rGT. Administration of the cannabinoid agonist CB1/CB2 WIN 55,212-2 improved choice strategy and increased choice latency in the suboptimal group, but only increased perseverative behaviour, when punished, in the optimal group. Blockade of CB1 or CB2 receptors or inhibition of fatty-acid amide hydrolase did not affect rGT performance. These results suggest that stimulation of cannabinoid receptors could affect gambling choice behaviours differentially in some subgroups of subjects. PMID:26905189

  19. Signatures for axial chromodynamics

    International Nuclear Information System (INIS)

    Within the context of basic left-right symmetry and the hypothesis of unification of weak, electromagnetic and strong forces at a mass level approximately equal to 104-106 GeV, relatively light ''mass'' axial gluons, confined or liberated, must be postulated. The authors remark that the existence of such ''light'' axial gluons supplementing the familiar vector octet preserves the successes of QCD, both for deep inelastic processes and charmonium physics. Through the characteristic spin-spin force, generated by their exchange, they may even help resolve some of the discrepancies between vector QCD predictions and charmonium physics. The main remark of this note is that if colour is liberated, not only vector but also axial-vector gluons are produced in high-energy e-e+ experiments, e.g. at PETRA and PEP, with fairly large cross-section. Distinctive decay modes of such liberated axial gluons are noted

  20. Dissipative Axial Inflation

    CERN Document Server

    Notari, Alessio

    2016-01-01

    We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term $\\frac{\\phi}{f_\\gamma} F \\tilde{F}$, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density $\\rho_R$, which which can lead to inflation without the need of a flat potential. We analyze the system, for momenta $k$ smaller than the cutoff $f_\\gamma$, including numerically the backreaction. We consider the evolution from a given static initial condition and explicitly show that, if $f_\\gamma$ is smaller than the field excursion $\\phi_0$ by about a factor of at least ${\\cal O} (20)$, there is a friction effect which turns on before that the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of...

  1. Surface nanoscale axial photonics

    OpenAIRE

    Sumetsky, M.; Fini, J. M.

    2011-01-01

    Dense photonic integration promises to revolutionize optical computing and communications. However, efforts towards this goal face unacceptable attenuation of light caused by surface roughness in microscopic devices. Here we address this problem by introducing Surface Nanoscale Axial Photonics (SNAP). The SNAP platform is based on whispering gallery modes circulating around the optical fiber surface and undergoing slow axial propagation readily described by the one-dimensional Schr\\"odinger e...

  2. Ligand modeling and design

    Energy Technology Data Exchange (ETDEWEB)

    Hay, B. [Pacific Northwest Lab., Richland, WA (United States)

    1996-10-01

    The purpose of this work is to develop and implement a molecular design basis for selecting organic ligands that would be used tin applications for the cost-effective removal of specific radionuclides from nuclear waste streams.

  3. The Effect of Metal-Remote Amino-Groups on Metal Center in Ruthenium (II Complexes with Terpyridine Ligands

    Directory of Open Access Journals (Sweden)

    Li H

    2015-07-01

    Full Text Available The aim of this work is to study structure, spectra and optical properties of ruthenium complexes with applications in the development of biosensors for cellular imaging. The results showed that a ruthenium complex with 4′-(aminomethylphenyl -2, 2′: 6′, 2′′ terpyridine ([Ru(TpyCH2NH22]2+ ligand has unique amino groups that reduce the energy gap between the highest occupied molecular orbital (HOMO and the lowest unoccupied molecular orbital (LUMO. The all ligand-HOMO composition of [Ru(TpyCH2NH22]2+ is contributed by the amino groups of the TpyCH2NH2 ligands. In a cell uptake test and proliferation assay, the ruthenium complex with amino group show cytoplasmic location and dose-dependent cytotoxic effect on 647V bladder cancer cells but not the complex with carboxylic as ligand substituent. Both experiment and calculation explore how the amino substituents affect the properties of the complex compared to the simple [Ru(Tpy2]2+ systems (where Tpy = 2, 2′: 6′, 2′′ terpyridine. The HOMO-LUMO energy gap calculation results of [Ru(TpyCH2NH22]2+ at the B3LYP/LANL2DZ level of theory is cons

  4. Improving the scoring of protein-ligand binding affinity by including the effects of structural water and electronic polarization.

    Science.gov (United States)

    Liu, Jinfeng; He, Xiao; Zhang, John Z H

    2013-06-24

    Docking programs that use scoring functions to estimate binding affinities of small molecules to biological targets are widely applied in drug design and drug screening with partial success. But accurate and efficient scoring functions for protein-ligand binding affinity still present a grand challenge to computational chemists. In this study, the polarized protein-specific charge model (PPC) is incorporated into the molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) method to rescore the binding poses of some protein-ligand complexes, for which docking programs, such as Autodock, could not predict their binding modes correctly. Different sampling techniques (single minimized conformation and multiple molecular dynamics (MD) snapshots) are used to test the performance of MM/PBSA combined with the PPC model. Our results show the availability and effectiveness of this approach in correctly ranking the binding poses. More importantly, the bridging water molecules are found to play an important role in correctly determining the protein-ligand binding modes. Explicitly including these bridging water molecules in MM/PBSA calculations improves the prediction accuracy significantly. Our study sheds light on the importance of both bridging water molecules and the electronic polarization in the development of more reliable scoring functions for predicting molecular docking and protein-ligand binding affinity. PMID:23651068

  5. Phonon Raman spectra of colloidal CdTe nanocrystals: effect of size, non-stoichiometry and ligand exchange

    Directory of Open Access Journals (Sweden)

    Lokteva Irina

    2011-01-01

    Full Text Available Abstract Resonant Raman study reveals the noticeable effect of the ligand exchange on the nanocrystal (NC surface onto the phonon spectra of colloidal CdTe NC of different size and composition. The oleic acid ligand exchange for pyridine ones was found to change noticeably the position and width of the longitudinal optical (LO phonon mode, as well as its intensity ratio to overtones. The broad shoulder above the LO peak frequency was enhanced and sharpened after pyridine treatment, as well as with decreasing NC size. The low-frequency mode around 100 cm-1 which is commonly related with the disorder-activated acoustical phonons appears in smaller NCs but is not enhanced after pyridine treatment. Surprisingly, the feature at low-frequency shoulder of the LO peak, commonly assigned to the surface optical phonon mode, was not sensitive to ligand exchange and concomitant close packing of the NCs. An increased structural disorder on the NC surface, strain and modified electron-phonon coupling is discussed as the possible reason of the observed changes in the phonon spectrum of ligand-exchanged CdTe NCs. PACS: 63.20.-e, 78.30.-j, 78.67.-n, 78.67.Bf

  6. Axial allometry in a neutrally buoyant environment: effects of the terrestrial-aquatic transition on vertebral scaling.

    Science.gov (United States)

    Jones, K E; Pierce, S E

    2016-03-01

    Ecological diversification into new environments presents new mechanical challenges for locomotion. An extreme example of this is the transition from a terrestrial to an aquatic lifestyle. Here, we examine the implications of life in a neutrally buoyant environment on adaptations of the axial skeleton to evolutionary increases in body size. On land, mammals must use their thoracolumbar vertebral column for body support against gravity and thus exhibit increasing stabilization of the trunk as body size increases. Conversely, in water, the role of the axial skeleton in body support is reduced, and, in aquatic mammals, the vertebral column functions primarily in locomotion. Therefore, we hypothesize that the allometric stabilization associated with increasing body size in terrestrial mammals will be minimized in secondarily aquatic mammals. We test this by comparing the scaling exponent (slope) of vertebral measures from 57 terrestrial species (23 felids, 34 bovids) to 23 semi-aquatic species (pinnipeds), using phylogenetically corrected regressions. Terrestrial taxa meet predictions of allometric stabilization, with posterior vertebral column (lumbar region) shortening, increased vertebral height compared to width, and shorter, more disc-shaped centra. In contrast, pinniped vertebral proportions (e.g. length, width, height) scale with isometry, and in some cases, centra even become more spool-shaped with increasing size, suggesting increased flexibility. Our results demonstrate that evolution of a secondarily aquatic lifestyle has modified the mechanical constraints associated with evolutionary increases in body size, relative to terrestrial taxa. PMID:26679743

  7. Thermo-electro-mechanical vibration analysis of size-dependent nanobeam resting on elastic medium under axial preload in presence of surface effect

    Science.gov (United States)

    Marzbanrad, Javad; Boreiry, Mahya; Shaghaghi, Gholam Reza

    2016-07-01

    In the present manuscript, a nonclassical beam theory is developed to analyze free vibration of piezoelectric nanobeam by considering surface effects resting on Winkler-Pasternak elastic medium and thermal loading with axial preload. The nonclassical Eringen theory is utilized to incorporate the length-scale parameter to account for the small-scale effect, while the Gurtin-Murdoch model is employed to inject the surface effects including surface elasticity, surface stress and surface density. The governing equations are derived using Hamilton's principle in the framework of Euler-Bernoulli beam theory. The governing partial differential equations of motions of system are reduced to a set of algebraic equations with the help of differential transformation method as a semi-analytical-numerical. The mathematical derivations and numerical results are presented in detail for various boundary conditions. Some numerical examples are illustrated in order to investigate the effect of several parameters such as the nonlocal parameter, piezoelectric voltage, surface effects, temperature change, axial preload and elastic medium parameters. Moreover, it is also indicated that the numerical results have good agreement with previous studies.

  8. Effects of surface ligands on the uptake and transport of gold nanoparticles in rice and tomato.

    Science.gov (United States)

    Li, Hongying; Ye, Xinxin; Guo, Xisheng; Geng, Zhigang; Wang, Guozhong

    2016-08-15

    Nanotechnology is advancing rapidly and substantial amounts of nanomaterials are released into the environment. Plants are an essential base component of the ecological environment and play a critical role in the fate and transport of nanomaterials in the environment through plant uptake and bioaccumulation. In this study, plant uptake of gold nanoparticles (GNPs) functionalized with three types of short ligands [cysteamine (CA), cysteine (CYS) and thioglycolic acid (TGA)] and of nearly identical hydrodynamic size (8-12nm) was investigated in the major crops rice (Oryza sativa L.) and tomato (Solanum lycopersicum). Uptake and translocation of GNPs not only depended on particle surface charge, but were also related to the species of ligand on the GNPs. The negatively charged GNPs capped with the CYS ligand (GNP-CYS) were more efficiently absorbed in roots and transferred to shoots (including stems and leaves) than that of GNPs capped with CA and TGA. The absorption process of GNPs involved a combination of both clathrin-dependent and -independent mechanisms. The endocytosis of GNPs was strongly inhibited by wortmannin, suggesting that clathrin-independent endocytosis was an important pathway of nanoparticle internalization in plants. Competition experiments with a free ligand (CYS) showed that the CYS ligand probably facilitated the endocytosis process of GNPs and increased the internalization of GNP-CYS in plants. The results will aid understanding of the mechanisms of nanoparticle uptake and translocation in plants. PMID:27131459

  9. Effects of the phytoestrogen coumestrol on RANK-ligand-induced differentiation of osteoclasts

    International Nuclear Information System (INIS)

    Phytoestrogens, which have structural similarity to 17β-estradiol, have been reported to act as agonists/antagonists of estrogen in animals and humans. Estrogen is known to have an important role in maintaining bone mass, because the concentration of serum estrogen decreases after menopause and the estrogen deficiency causes bone loss. In this study, we investigated the effects of coumestrol and other phytoestrogens on osteoclast differentiation using estrogen receptor α-transfected RAW264.7 (RAW264.7-ERα) cells. When the cells were cultured with the receptor activator of nuclear factor kappa B-ligand (RANKL), both formation of tartrate-resistant acid phosphatase (TRAP) positive multinucleated cells and TRAP activity were increased compared with control cells that were cultured in the absence of RANKL. Coumestrol decreased RANKL-induced formation of TRAP-positive multinucleated cells and TRAP activity dose-dependently. RANKL-stimulated RAW264.7-ERα cells formed resorption pits on calcium phosphate films and the pit formation was inhibited by coumestrol in a dose-dependent manner. RT-PCR analyses revealed that coumestrol (10 μM) decreased mRNA levels of calcitonin receptor (CTR) and matrix metalloproteinase-9 (MMP9) in RANKL-treated cells. In addition, pretreatment of coumestrol decreased RANKL-induced phosphorylation of extracellular signal-regulated kinases/p44/42 (ERK1/2). These results suggest that coumestrol has an inhibitory effect on the differentiation of osteoclasts, at least partially via ERK1/2 pathway

  10. Effects of chemokine (C–C motif) ligand 1 on microglial function

    International Nuclear Information System (INIS)

    Highlights: •CCR8, a specific receptor for CCL-1, was expressed on primary cultured microglia. •Expression of CCR-8 in microglia was upregulated in the presence of CCL-1. •CCL-1 increased motility, proliferation and phagocytosis of cultured microglia. •CCL-1promoted BDNF and IL-6 mRNA, and the release of NO from microglia. •CCL-1 activates microglia and may contribute to the development of neuropathic pain. -- Abstract: Microglia, which constitute the resident macrophages of the central nervous system (CNS), are generally considered as the primary immune cells in the brain and spinal cord. Microglial cells respond to various factors which are produced following nerve injury of multiple aetiologies and contribute to the development of neuronal disease. Chemokine (C–C motif) ligand 1 (CCL-1), a well-characterized chemokine secreted by activated T cells, has been shown to play an important role in neuropathic pain induced by nerve injury and is also produced in various cell types in the CNS, especially in dorsal root ganglia (DRG). However, the role of CCL-1 in the CNS and the effects on microglia remains unclear. Here we showed the multiple effects of CCL-1 on microglia. We first showed that CCR-8, a specific receptor for CCL-1, was expressed on primary cultured microglia, as well as on astrocytes and neurons, and was upregulated in the presence of CCL-1. CCL-1 at concentration of 1 ng/ml induced chemotaxis, increased motility at a higher concentration (100 ng/ml), and increased proliferation and phagocytosis of cultured microglia. CCL-1 also activated microglia morphologically, promoted mRNA levels for brain-derived neurotrophic factor (BDNF) and IL-6, and increased the release of nitrite from microglia. These indicate that CCL-1 has a role as a mediator in neuron-glia interaction, which may contribute to the development of neurological diseases, especially in neuropathic pain

  11. Effects of chemokine (C–C motif) ligand 1 on microglial function

    Energy Technology Data Exchange (ETDEWEB)

    Akimoto, Nozomi [Laboratory of Pathophysiology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan); Ifuku, Masataka [Laboratory of Integrative Physiology, Graduate School of Medicine, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan); Mori, Yuki [Laboratory of Pathophysiology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan); Noda, Mami, E-mail: noda@phar.kyushu-u.ac.jp [Laboratory of Pathophysiology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan)

    2013-07-05

    Highlights: •CCR8, a specific receptor for CCL-1, was expressed on primary cultured microglia. •Expression of CCR-8 in microglia was upregulated in the presence of CCL-1. •CCL-1 increased motility, proliferation and phagocytosis of cultured microglia. •CCL-1promoted BDNF and IL-6 mRNA, and the release of NO from microglia. •CCL-1 activates microglia and may contribute to the development of neuropathic pain. -- Abstract: Microglia, which constitute the resident macrophages of the central nervous system (CNS), are generally considered as the primary immune cells in the brain and spinal cord. Microglial cells respond to various factors which are produced following nerve injury of multiple aetiologies and contribute to the development of neuronal disease. Chemokine (C–C motif) ligand 1 (CCL-1), a well-characterized chemokine secreted by activated T cells, has been shown to play an important role in neuropathic pain induced by nerve injury and is also produced in various cell types in the CNS, especially in dorsal root ganglia (DRG). However, the role of CCL-1 in the CNS and the effects on microglia remains unclear. Here we showed the multiple effects of CCL-1 on microglia. We first showed that CCR-8, a specific receptor for CCL-1, was expressed on primary cultured microglia, as well as on astrocytes and neurons, and was upregulated in the presence of CCL-1. CCL-1 at concentration of 1 ng/ml induced chemotaxis, increased motility at a higher concentration (100 ng/ml), and increased proliferation and phagocytosis of cultured microglia. CCL-1 also activated microglia morphologically, promoted mRNA levels for brain-derived neurotrophic factor (BDNF) and IL-6, and increased the release of nitrite from microglia. These indicate that CCL-1 has a role as a mediator in neuron-glia interaction, which may contribute to the development of neurological diseases, especially in neuropathic pain.

  12. Axially symmetric rotating traversable wormholes

    CERN Document Server

    Kuhfittig, P K F

    2003-01-01

    This paper generalizes the static and spherically symmetric traversable wormhole geometry to a rotating axially symmetric one with a time-dependent angular velocity by means of an exact solution. It was found that the violation of the weak energy condition, although unavoidable, is considerably less severe than in the static spherically symmetric case. The radial tidal constraint is more easily met due to the rotation. Similar improvements are seen in one of the lateral tidal constraints. The magnitude of the angular velocity may have little effect on the weak energy condition violation for an axially symmetric wormhole. For a spherically symmetric one, however, the violation becomes less severe with increasing angular velocity. The time rate of change of the angular velocity, on the other hand, was found to have no effect at all. Finally, the angular velocity must depend only on the radial coordinate, confirming an earlier result.

  13. Review of Axial Burnup Distribution Considerations for Burnup Credit Calculations

    International Nuclear Information System (INIS)

    This report attempts to summarize and consolidate the existing knowledge on axial burnup distribution issues that are important to burnup credit criticality safety calculations. Recently released Nuclear Regulatory Commission (NRC) staff guidance permits limited burnup credit, and thus, has prompted resolution of the axial burnup distribution issue. The reactivity difference between the neutron multiplication factor (keff) calculated with explicit representation of the axial burnup distribution and keff calculated assuming a uniform axial burnup is referred to as the ''end effect.'' This end effect is shown to be dependent on many factors, including the axial-burnup profile, total accumulated burnup, cooling time, initial enrichment, assembly design, and the isotopics considered (i.e., actinide-only or actinides plus fission products). Axial modeling studies, efforts related to the development of axial-profile databases, and the determination of bounding axial profiles are also discussed. Finally, areas that could benefit from further efforts are identified

  14. Review of Axial Burnup Distribution Considerations for Burnup Credit Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, J.C.; DeHart, M.D.

    2000-03-01

    This report attempts to summarize and consolidate the existing knowledge on axial burnup distribution issues that are important to burnup credit criticality safety calculations. Recently released Nuclear Regulatory Commission (NRC) staff guidance permits limited burnup credit, and thus, has prompted resolution of the axial burnup distribution issue. The reactivity difference between the neutron multiplication factor (keff) calculated with explicit representation of the axial burnup distribution and keff calculated assuming a uniform axial burnup is referred to as the ``end effect.'' This end effect is shown to be dependent on many factors, including the axial-burnup profile, total accumulated burnup, cooling time, initial enrichment, assembly design, and the isotopics considered (i.e., actinide-only or actinides plus fission products). Axial modeling studies, efforts related to the development of axial-profile databases, and the determination of bounding axial profiles are also discussed. Finally, areas that could benefit from further efforts are identified.

  15. Improved Ligand-Field Theory with Effect of Electron-Phonon Interaction

    Institute of Scientific and Technical Information of China (English)

    MA Dong-Ping; CHEN Ju-Rong

    2005-01-01

    Traditional ligand-field theory has to be improved by taking into account both "pure electronic" contribution and electron-phonon interaction one (including lattice-vibrational relaxation energy). By means of improved ligand-field theory, R1, R2, R'3, R'2, and R'1 lines, U band, ground-state zero-field-splitting (GSZFS), and ground-state g factors of ruby and/or GSGG: Cr3+ as well as thermal shifts of GSZFS, R1 line and R2 line of ruby have been calculated.The results are in very good agreement with the experimental data. Moreover, it is found that the value of cubic-field parameter given by traditional ligand-field theory is inappropriately large. For thermal shifts of GSZFS, R1 line and R2 line of ruby, several conclusions have also been obtained.

  16. Improved Ligand-Field Theory with Effect of Electron-Phonon Interaction

    Science.gov (United States)

    Ma, Dong-Ping; Chen, Ju-Rong

    2005-03-01

    Traditional ligand-field theory has to be improved by taking into account both ``pure electronic'' contribution and electron-phonon interaction one (including lattice-vibrational relaxation energy). By means of improved ligand-field theory, R1, R2, R'3, R'2, and R'1 lines, U band, ground-state zero-field-splitting (GSZFS), and ground-state g factors of ruby and/or GSGG: Cr3+ as well as thermal shifts of GSZFS, R1 line and R2 line of ruby have been calculated. The results are in very good agreement with the experimental data. Moreover, it is found that the value of cubic-field parameter given by traditional ligand-field theory is inappropriately large. For thermal shifts of GSZFS, R1 line and R2 line of ruby, several conclusions have also been obtained.

  17. Theoretical study on effect of radial and axial deformation on electron transport properties in a semiconducting Si–C nanotube

    Indian Academy of Sciences (India)

    Sudhanshu Choudhary; S Qureshi

    2012-10-01

    We investigate electron transport properties in a deformed (8, 0) silicon carbide nanotube by applying self consistent non-equilibrium Green’s function formalism in combination with the density-functional theory to a two-probe molecular junction constructed from deformed nanotube. The results suggest significant reduction in threshold voltage in the case of both radially compressed and axially elongated (8, 0) SiCNTs, a large difference in current–voltage characteristics was observed. Analysis of frontier molecular orbitals (FMO) and transmission spectrum show bandgap reduction in deformed nanotubes. Deformation introduces electronic states near the Fermi level, enhancing the conduction properties of (8, 0) SiCNT. The FMOs and the orbitals corresponding to peaks in () around Fermi level obviously has some major contributions from the deformed site. However, localization of the electronic state near the Fermi level is weak in (8, 0) SiCNT, possibly because of its large bandgap.

  18. A Vitamin D Receptor Selectively Activated by Gemini Analogs Reveals Ligand Dependent and Independent Effects

    OpenAIRE

    Tiphaine Huet; Gilles Laverny; Fabrice Ciesielski; Ferdinand Molnár; Thanuja Gali Ramamoorthy; Anna Y. Belorusova; Pierre Antony; Noelle Potier; Daniel Metzger; Dino Moras; Natacha Rochel

    2015-01-01

    The bioactive form of vitamin D [1,25(OH)2D3] regulates mineral and bone homeostasis and exerts potent anti-inflammatory and antiproliferative properties through binding to the vitamin D receptor (VDR). The 3D structures of the VDR ligand-binding domain with 1,25(OH)2D3 or gemini analogs unveiled the molecular mechanism underlying ligand recognition. On the basis of structure-function correlations, we generated a point-mutated VDR (VDRgem) that is unresponsive to 1,25(OH)2D3, but the activity...

  19. Effect of a low axial magnetic field on the primary Al 2 Cu phase growth in a directionally solidified Al-Cu hypereutectic alloy

    Science.gov (United States)

    Shen, Yu; Ren, Zhongming; Li, Xi; Ren, Weili; Xi, Yan

    2011-12-01

    Effect of a low axial magnetic field on the growth behavior of the primary Al 2Cu phase in the Al-40 wt% Cu hypereutectic alloy during directional solidification at a low growth speed has been investigated experimentally. The results show that the application of a low magnetic field (≤1 T) causes the primary Al 2Cu phase to become deformed and irregular opposed to the well developed strip-like primary phase in the absence of the field. The deformation of the primary phase is maximum when a 0.5 T magnetic field is applied. Moreover, it has been found that the magnetic field promotes a transition of the primary phase morphology from faceted growth to irregular cellular structure and makes the primary phase spacing decrease with the increase of the magnetic field intensity. From the macroscopic scale, the magnetic field causes the occurrence of a considerable radial macrosegregation. These experimental results may be attributed to the effects of thermoelectric magnetic force (TEMF) in the solid and thermoelectromagnetic convection (TEMC) in the liquid. Further, the model of these effects is presented and evaluated numerically. The results indicate that the numerical magnitude of the TEMF during directional solidification under a 0.5 T low axial magnetic field can be of the order of 10 3 N/m 3. The force causes TEMC at different scales to modify the distribution of solute at the interface and should be responsible for the deformation, fracture and deflection of the primary phase.

  20. The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow

    Institute of Scientific and Technical Information of China (English)

    Christopher Long; Peter Childs

    2007-01-01

    This paper discusses experimental results from two different build configurations of a heated multiple rotating cavity test rig.Measurements of heat transfer from the discs and tangential velocities are presented.The test rig is a 70% full scale version of a high pressure compressor stack of an axial gas turbine engine.Of particular interest are the internal cylindrical cavities formed by adjacent discs and the interaction of these with a central axial throughflow of cooling air.Tests were carried out for a range of non-dimensional parameters representative of high pressure compressor internal air system flows (Reφup to 5×106 and Rez up to 2×105).Two different builds have been tested.The most significant difference between these two build configurations is the size of the annular gap between the (non-rotating) drive shaft and the bores of the discs.The heat transfer data were obtained from thermocouple measurements of surface temperature and a conduction solution method.The velocity measurements were made using a two component,LDA system.The heat transfer results from the discs show differences between the two builds.This is attributed to the wider annular gap allowing more of the throughflow to penetrate into the cavity.There are also significant differences between the radial distributions of tangential velocity in the two builds of the test rig.For the narrow annular gap,there is an increase of non-dimensional tangential velocity Vφ/Ωr with radial location to solid body rotation Vφ/Ωr=1.For the wider annular gap,the non-dimensional velocities show a decrease with radial location to solid body rotation.

  1. SPOT-Ligand: Fast and effective structure-based virtual screening by binding homology search according to ligand and receptor similarity.

    Science.gov (United States)

    Yang, Yuedong; Zhan, Jian; Zhou, Yaoqi

    2016-07-01

    Structure-based virtual screening usually involves docking of a library of chemical compounds onto the functional pocket of the target receptor so as to discover novel classes of ligands. However, the overall success rate remains low and screening a large library is computationally intensive. An alternative to this "ab initio" approach is virtual screening by binding homology search. In this approach, potential ligands are predicted based on similar interaction pairs (similarity in receptors and ligands). SPOT-Ligand is an approach that integrates ligand similarity by Tanimoto coefficient and receptor similarity by protein structure alignment program SPalign. The method was found to yield a consistent performance in DUD and DUD-E docking benchmarks even if model structures were employed. It improves over docking methods (DOCK6 and AUTODOCK Vina) and has a performance comparable to or better than other binding-homology methods (FINDsite and PoLi) with higher computational efficiency. The server is available at http://sparks-lab.org. © 2016 Wiley Periodicals, Inc. PMID:27074979

  2. Reactivity and effectiveness of traditional and novel ligands for multi-micronutrient fertilization in a calcareous soil

    OpenAIRE

    López-Rayo, Sandra; Nadal, Paloma; Lucena, Juan J.

    2015-01-01

    This study compares the effectiveness of multi-micronutrient formulations containing iron (Fe), manganese (Mn), and zinc (Zn) with traditional (EDTA, DTPA, HEEDTA, and EDDHAm) or novel chelates (o,p-EDDHA, S,S-EDDS, and IDHA) and natural complexing agents (gluconate and lignosulfonate). The stability and reactivity of the formulations were studied on batch experiments with calcareous soil and by speciation modeling. Formulations containing traditional ligands maintained higher Mn but lower Zn...

  3. The Effects of Exogenous and Endogenous Ligands of the Aryl Hydrocarbon Receptor on the Activation of Autoimmune Diabetes

    OpenAIRE

    Abu-Rizq, Hana'A

    2012-01-01

    The aryl-hydrocarbon receptor (AhR) is an important receptor found in immune cells. Itfunctions as a detector of environmental toxins, naturally occurring dietary products, andendogenous tryptophan derivatives for induction of gene transcription responses. Previousreports have implicated stimulation of AhR by various ligands in promoting T cellactivation or regulatory function, with effects on autoimmune disease models. Also, effectsof Ah toxins or natural products on increasing or suppressin...

  4. Effect of axial ligation or pi-pi-type interactions on photochemical charge stabilization in "two-point" bound supramolecular porphyrin-fullerene conjugates.

    Science.gov (United States)

    D'Souza, Francis; Chitta, Raghu; Gadde, Suresh; Zandler, Melvin E; McCarty, Amy L; Sandanayaka, Atula S D; Araki, Yasuyaki; Ito, Osamu

    2005-07-18

    Two types of structurally well-defined, self-assembled zinc porphyrin-fullerene conjugates were formed by "two-point" binding strategies to probe the effect of axial ligation or pi-pi-type interactions on the photochemical charge stabilization in the supramolecular dyads. To achieve this, meso-tetraphenylporphyrin was functionalized to possess one or four [18]crown-6 moieties at different locations on the porphyrin macrocycle while fullerene was functionalized to possess an alkyl ammonium cation, and a pyridine or phenyl entities. As a result of the crown ether-ammonium cation complexation, and zinc-pyridine coordination or pi-pi-type interactions, stable zinc porphyrin-fullerene conjugates with defined distance and orientation were formed. Evidence for the zinc-pyridine complexation or pi-pi-type interactions was obtained from the spectral and computational studies. Steady-state and time-resolved emission studies revealed efficient quenching of the zinc-porphyrin singlet excited state in these dyads, and the measured rates of charge separation, k(CS) were found to be slightly better in the case of the dyads held by axial coordination and crown ether-cation complexation. Nanosecond transient absorption studies provided evidence for the electron transfer reactions, and these studies also revealed charge stabilization in these dyads. The lifetimes of the radical ion pairs were found to depend upon the type of porphyrins utilized to form the dyads, that is, porphyrin possessing the crown ether moiety at the ortho position of one of the phenyl rings yielded prolonged charge stabilized states. Addition of pyridine to the supramolecular dyads eliminated the zinc-pyridine coordination or pi-pi-type interactions of the "two-point" bound systems due to the formation of a new zinc-pyridine axial bond thus giving a unique opportunity to probe the effect of axial coordination or pi-pi interactions on k(CS) and k(CR). Under these conditions, the measured electron transfer rates

  5. Ligand modeling and design

    Energy Technology Data Exchange (ETDEWEB)

    Hay, B.P. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-10-01

    The purpose of this work is to develop and implement a molecular design basis for selecting organic ligands that would be used in the cost-effective removal of specific radionuclides from nuclear waste streams. Organic ligands with metal ion specificity are critical components in the development of solvent extraction and ion exchange processes that are highly selective for targeted radionuclides. The traditional approach to the development of such ligands involves lengthy programs of organic synthesis and testing, which in the absence of reliable methods for screening compounds before synthesis, results in wasted research effort. The author`s approach breaks down and simplifies this costly process with the aid of computer-based molecular modeling techniques. Commercial software for organic molecular modeling is being configured to examine the interactions between organic ligands and metal ions, yielding an inexpensive, commercially or readily available computational tool that can be used to predict the structures and energies of ligand-metal complexes. Users will be able to correlate the large body of existing experimental data on structure, solution binding affinity, and metal ion selectivity to develop structural design criteria. These criteria will provide a basis for selecting ligands that can be implemented in separations technologies through collaboration with other DOE national laboratories and private industry. The initial focus will be to select ether-based ligands that can be applied to the recovery and concentration of the alkali and alkaline earth metal ions including cesium, strontium, and radium.

  6. Comparative study for axial and radial shuffling scheme effect on the performance of Pb-Bi cooled fast reactors with natural uranium as fuel cycle input

    International Nuclear Information System (INIS)

    Full text:Comparative study for the Design of Pb-Bi cooled fast reactors with natural uranium as fuel cycle input using special radial shuffling strategy and axial direction modified CANDLE burn-up scheme has been performed. The reactors utilizes UN-PuN as fuel, Eutectic Pb-Bi as coolant, and can be operated without refueling for 10 years in each batch. Reactor design optimization is performed to utilize natural uranium as fuel cycle input. This reactor subdivided into 6-10 regions with equal volume in radial directions. The natural uranium is initially put in region 1, and after one cycle of 10 years of burn-up it is shifted to region 2 and the region 1 is filled by fresh natural uranium fuel. This concept is basically applied to all regions. The calculation has been done by using SRAC-Citation system code and JENDL-3.2 library. The effective multiplication factor change increases monotonously during 10 years reactor operation time. There is significant power distribution change in the central part of the core during the BOC and the EOC in the radial shuffling system. It is larger than that in the case of modified CANDLE case which use axial direction burning region move. The burn-up level of fuel is slowly grows during the first 15 years but then grow faster in the rest of burn-up history. This pattern is a little bit different from the case of modified CANDLE burn-up scheme in Axial direction in which the slow growing burn-up period is relatively longer almost half of the burn-up history. (author)

  7. Solvent effect on thermodynamics of Ag(I) coordination to tripodal polypyridine ligands

    DEFF Research Database (Denmark)

    Del Piero, Silvia; Melchior, Andrea; Menotti, Davide;

    2009-01-01

      An investigation on the thermodynamics of complex formation between Ag(I) ion and different tripodal ligands (tris[(2-pyridyl)methyl]amine) (TPA) and 6,6'-bis[bis(2-pyridylmethyl)aminomethyl]-2,2'-bipyridine (BTPA) has been carried out in the aprotic solvents dimethylsulfoxide (DMSO) and...

  8. Organometallic Ru(II) Photosensitizers Derived from π-Expansive Cyclometalating Ligands: Surprising Theranostic PDT Effects.

    Science.gov (United States)

    Sainuddin, Tariq; McCain, Julia; Pinto, Mitch; Yin, Huimin; Gibson, Jordan; Hetu, Marc; McFarland, Sherri A

    2016-01-01

    The purpose of the present study was to investigate the influence of π-expansive cyclometalating ligands on the photophysical and photobiological properties of organometallic Ru(II) compounds. Four compounds with increasing π conjugation on the cyclometalating ligand were prepared, and their structures were confirmed by HPLC, 1D and 2D (1)H NMR, and mass spectrometry. The properties of these compounds differed substantially from their Ru(II) polypyridyl counterparts. Namely, they were characterized by red-shifted absorption, very weak to no room temperature phosphorescence, extremely short phosphorescence state lifetimes ( 300 μM) but was phototoxic to cells in the nanomolar regime. Exceptionally large phototherapeutic margins, exceeding 3 orders of magnitude in some cases, were accompanied by bright ligand-centered intracellular fluorescence in cancer cells. Thus, Ru(II) organometallic systems derived from π-expansive cyclometalating ligands, such 4,9,16-triazadibenzo[a,c]napthacene (pbpn), represent the first class of potent light-responsive Ru(II) cyclometalating agents with theranostic potential. PMID:26672769

  9. Effects of Temperature and Axial Strain on Four-Wave Mixing Parametric Frequencies in Microstructured Optical Fibers Pumped in the Normal Dispersion Regime

    Directory of Open Access Journals (Sweden)

    Javier Abreu-Afonso

    2014-10-01

    Full Text Available A study of the effect of temperature and axial strain on the parametric wavelengths produced by four-wave mixing in microstructured optical fibers is presented. Degenerate four-wave mixing was generated in the fibers by pumping at normal dispersion, near the zero-dispersion wavelength, causing the appearance of two widely-spaced four-wave mixing spectral bands. Temperature changes, and/or axial strain applied to the fiber, affects the dispersion characteristics of the fiber, which can result in the shift of the parametric wavelengths. We show that the increase of temperature causes the signal and idler wavelengths to shift linearly towards shorter and longer wavelengths, respectively. For the specific fiber of the experiment, the band shift at rates ­–0.04 nm/ºC and 0.3 nm/ºC, respectively. Strain causes the parametric bands to shift in the opposite way. The signal band shifted 2.8 nm/me and the idler -5.4 nm/me. Experimental observations are backed by numerical simulations.

  10. Forced Transverse Vibration of a Closed Double Single-Walled Carbon Nanotube System Containing a Fluid with Effect of Compressive Axial Load

    Directory of Open Access Journals (Sweden)

    Mehrdad Nasirshoaibi

    2015-01-01

    Full Text Available Based on the Rayleigh beam theory, the forced transverse vibrations of a closed double single-walled carbon nanotube (SWCNT system containing a fluid with a Pasternak layer in-between are investigated. It is assumed that the two single-walled carbon nanotubes of the system are continuously joined by a Pasternak layer and both sides of SWCNTs containing a fluid are closed. The dynamic responses of the system caused by arbitrarily distributed continuous loads are obtained. The effect of compressive axial load on the forced vibrations of the double single-walled carbon nanotube system is discussed for one case of particular excitation loading. The properties of the forced transverse vibrations of the system are found to be significantly dependent on the compressive axial load. The steady-state vibration amplitudes of the SWCNT decrease with increasing of length of SWCNT. Vibrations caused by the harmonic exciting forces are discussed, and conditions of resonance and dynamic vibration absorption are formulated. The SWCNT-type dynamic absorber is a new concept of a dynamic vibration absorber (DVA, which can be applied to suppress excessive vibrations of corresponding SWCNT systems.

  11. Ligand substitution reactions of a phenolic quinolyl hydrazone; oxidovanadium (IV complexes

    Directory of Open Access Journals (Sweden)

    Seleem Hussein S

    2011-08-01

    Full Text Available Abstract Background Quinoline ring has therapeutic and biological activities. Quinolyl hydrazones constitute a class of excellent chelating agents. Recently, the physiological and biological activities of quinolyl hydrazones arise from their tendency to form metal chelates with transition metal ions. In this context, we have aimed to study the competency effect of a phenolic quinolyl hydrazone (H2L; primary ligand with some auxiliary ligands (Tmen, Phen or Oxine; secondary ligands towards oxidovanadium (IV ions. Results Mono- and binuclear oxidovanadium (IV - complexes were obtained from the reaction of a phenolic quinolyl hydrazone with oxidovanadium (IV- ion in absence and presence of N,N,N',N'- tetramethylethylenediamine (Tmen, 1,10-phenanthroline (Phen or 8-hydroxyquinoline (Oxine. The phenolic quinolyl hydrazone ligand behaves as monobasic bidentate (NO- donor with O- bridging. All the obtained complexes have the preferable octahedral geometry except the oxinato complex (2 which has a square pyramid geometry with no axial interaction; the only homoleptic complex in this study. Conclusion The ligand exchange (substitution/replacement reactions reflect the strong competency power of the auxiliary aromatic ligands (Phen/Oxine compared to the phenolic quinolyl hydrazone (H2L towards oxidovanadium (IV ion; (complexes 2 and 3. By contrast, in case of the more flexible aliphatic competitor (Tmen, an adduct was obtained (4. The obtained complexes reflect the strength of the ligand field towards the oxidovanadium (IV- ion; Oxine or Phen >> phenolic hydrazone (H2L > Tmen.

  12. The effect of heterocyclic S,S’-ligands on the electrochemical properties of some cobalt(III complexes in acid

    Directory of Open Access Journals (Sweden)

    V. M. JOVANOVIC

    2005-02-01

    Full Text Available Eight mixed-ligand cobalt(III complexes with the macrocyclic amine 1,4,8,11-tetraazacyclotetradecane (cyclam and a heterocyclic dithiocarbamate (Rdtc- i.e., morpholine- (Morphdtc, thiomorpholine- (Timdtc, piperazine- (Pzdtc, N-methylpiperazine-(Mepzdtc, piperidine- (Pipdtc, 2-, 3- or 4-methylpiperidine- (2-, 3- and 4-Mepipdtc carbodithionato-S,S ions, of the general formula [Co(cyclamRdtc](ClO42, were investigated in deoxygenated 0.1MHClO4 solutions. Cyclic voltammetry data at a glassy carbon (GC electrode demonstrate a redox reaction of cobalt(III from the complexes at potentials strongly influenced by the presence of different heterocyclic Rdtc- ligands. In this respect, the complexes were separated into two groups: the first, with a heteroatom O, S or N in the heterocyclic ring, and the second, with a methyl group on the piperidine ring of the Rdtc- ligand. Anodic polarization of an Fe electrode in the presence of the complexes shows their influence not only on the dissolution of iron but also on the hydrogen evolution reactions and on this basis complexes the complexes could be divided into the same two groups. It was found that the weaker the inhibiting effect of the free heterocyclic amines is, the significantly higher is the efficiency of the corresponding complexes.

  13. An Effective Strategy To Construct Novel Polyoxometalate-Based Hybrids by Deliberately Controlling Organic Ligand Transformation In Situ.

    Science.gov (United States)

    Wang, Xiu-Li; Zhang, Rui; Wang, Xiang; Lin, Hong-Yan; Liu, Guo-Cheng

    2016-07-01

    Deliberately controlling organic ligand transformation in situ has remained a challenge for the construction of polyoxometalate (POM)-based inorganic-organic hybrids. In this work, four POM-based hybrids assembled from an in situ bifurcating organic ligand-[Cu2(DIBA)4](H3PMo12O40)·6H2O (1), [Cu2(DIBA)4](H4SiW12O40)·6H2O (2), [Ag(HDIBA)2](H2PMo12O40)·2H2O (3), [Ag3(HDIBA)2(H2O)][(P2W18O62)1/2]·4H2O (4) (DIBAH = 3,5-di(1H-imidazol-1-yl) benzoic acid)-have been designed and obtained under hydrothermal conditions. Compounds 1 and 2 are isostructural, displaying a three-dimensional (3D) 2-fold interpenetrating framework with two types of channels, and the bigger channels are occupied by Keggin polyoxoanions and crystallization water molecules, but only crystallization water molecules in the smaller ones. Compound 3 displays a 3D supramolecular structure constructed from {Ag(HDIBA)2} segments and PMo12O40(3-) polyoxoanions through hydrogen bonding interactions. Compound 4 shows a 3D 2-fold interpenetrating framework based on (3, 3, 4)-connected network, which is constructed from {Ag3(HDIBA)2}n chains and P2W18O62(6-) polyoxoanions as linkers. The DIBAH ligand was generated in situ from 3,5-di(1H-imidazol-1-yl)benzonitrile by deliberate design, which illustrates that the strategy to construct novel POM-based hybrids by controlling ligand transformation in situ is rational and feasible. In addition, the effects of the central metal and POMs on the structures of the target compounds were discussed. Finally, the electrochemical and photocatalytic properties of compounds 1-4 have been investigated in this paper. PMID:27322656

  14. Effects of ligand binding on the mechanical stability of protein GB1 studied by steered molecular dynamics simulation.

    Science.gov (United States)

    Su, Ji-Guo; Zhao, Shu-Xin; Wang, Xiao-Feng; Li, Chun-Hua; Li, Jing-Yuan

    2016-08-01

    Regulation of the mechanical properties of proteins plays an important role in many biological processes, and sheds light on the design of biomaterials comprised of protein. At present, strategies to regulate protein mechanical stability focus mainly on direct modulation of the force-bearing region of the protein. Interestingly, the mechanical stability of GB1 can be significantly enhanced by the binding of Fc fragments of human IgG antibody, where the binding site is distant from the force-bearing region of the protein. The mechanism of this long-range allosteric control of protein mechanics is still elusive. In this work, the impact of ligand binding on the mechanical stability of GB1 was investigated using steered molecular dynamics simulation, and a mechanism underlying the enhanced protein mechanical stability is proposed. We found that the external force causes deformation of both force-bearing region and ligand binding site. In other words, there is a long-range coupling between these two regions. The binding of ligand restricts the distortion of the binding site and reduces the deformation of the force-bearing region through a long-range allosteric communication, which thus improves the overall mechanical stability of the protein. The simulation results are very consistent with previous experimental observations. Our studies thus provide atomic-level insights into the mechanical unfolding process of GB1, and explain the impact of ligand binding on the mechanical properties of the protein through long-range allosteric regulation, which should facilitate effective modulation of protein mechanical properties. PMID:27444879

  15. Effects of ligands with different water solubilities on self-assembly and properties of targeted nanoparticles

    OpenAIRE

    Valencia, Pedro M.; Hanewich-Hollatz, Mikhail H.; Gao, Weiwei; Karim, Fawziya; Langer, Robert; Karnik, Rohit; Farokhzad, Omid C.

    2011-01-01

    The engineering of drug-encapsulated targeted nanoparticles (NPs) has the potential to revolutionize drug therapy. A major challenge for the smooth translation of targeted NPs to the clinic has been developing methods for the prediction and optimization of the NP surface composition, especially when targeting ligands (TL) of different chemical properties are involved in the NP self-assembly process. Here we investigated the self-assembly and properties of two different targeted NPs decorated ...

  16. The effect of sewage effluent on trace metal speciation: implications for the biotic ligand model approach

    OpenAIRE

    Constantino, Carlos

    2013-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University This research examined the suitability of the biotic ligand model (BLM) approach for assessing environmental risk in surface waters consisting substantially of treated sewage effluent, and the implications of its use within a compliance-based regulatory framework aimed at controlling discharges of metals into the aquatic environment. The results from a series of Daphnia magna acute copp...

  17. Effects of a piperidine ligand on DNA modification by antitumor cisplatin analogues

    Czech Academy of Sciences Publication Activity Database

    Kašpárková, Jana; Nováková, Olga; Najajreh, Y.; Gibson, D.; Perez, J.M.; Brabec, Viktor

    2003-01-01

    Roč. 16, č. 11 (2003), s. 1424-1432. ISSN 0893-228X R&D Projects: GA ČR GA305/02/1552; GA AV ČR KJB5004301; GA AV ČR IBS5004009 Institutional research plan: CEZ:AV0Z5004920 Keywords : DNA * piperidine ligand * antitumor cisplatin analogues Subject RIV: BO - Biophysics Impact factor: 3.332, year: 2003

  18. Molecular tectonics of mixed-ligand metal-organic frameworks: Positional isomeric effect, and structural diversification

    Science.gov (United States)

    Cai, Hua; Xu, Chong; Zhou, Yu-Ping; Tong, Xiao-Qiang; Guo, Ying

    2016-03-01

    To explore the influence of three structurally different polycarboxylate ligands H2L1 to H4L3 in the system Cd(II)/PPAN, three coordination polymers, formulated as {Cd2(PPAA)2(L1)2}n (1), {[Cd2(PPAA)2(HL2) (H2O)].2H2O}n (2), {Cd2(PPAN)2(L3) (H2O)2}n (3) have been obtained under similar conditions (PPAA- = 2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl)acetate, PPAN = 2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl)acetonitrile, H2L1 = 1,3-benzenedicarboxylic acid, H3L2 = 1,3,5-benzenetricarboxylic acid, H4L3 = 1,2,4,5-benzenetetracarboxylic acid). In 1-2, PPAN are hydrolyzed into a novel PPAA- ligand. The structure determination reveals that complex 1 contains 1D double chains of {[Cd(PPAA)]+}n cation structural units, which are further extended by these μ3-(L1)2- ligands forming a novel 2D three-layered framework with (4.82)2(43.62.8)2(4383)2(48.66.8) topology. Complex 2 is one-dimensional (1D) ribbon-like chains having two kinds of dimerics [Cd(PPAA)]2 and [Cd(COO)]2 subunits and dimeric Cd(II) units bridged by μ3-(HL2)2- ligands. Complex 3 shows an undulating 2D (4, 4)-network by μ4-(L3)4-. In addition, photoluminescent properties of three coordination polymers were also investigated in this paper.

  19. THERMAL EFFECTIVENESS OF THE GAS FLOW VORTICAL HEATRELEASE INTENSIFICATION AT AXIAL AND TRANSVERSAL FLOWING-AROUND THE ROUND-TUBULAR SURFACES Part 2

    Directory of Open Access Journals (Sweden)

    V. B. Kuntysh

    2015-09-01

    Full Text Available The paper demonstrates the fact that in valuating the actual heat efficiency from utilizing the vortical heat-release intensification it is necessary to account for the increase of heatreleasing area of the tube with the corresponding lacunae (hollows, lunules. It may vary from 4 to 280 % as a function of their geometrical parameters which causes heat-release increasing with its simultaneous growth from vortex formation in the boundary-layer flow by the swirls generated by lunule turbulizers. For the tube of axial flow-around with hollows applied on the outer surface the vortex intensification enhances the thermal effectiveness up to 1,39 times, and in the case of the transversal flow-around tube banks with lunuled tube outer surface it does not exceed 29 % at Re = 5000. With Re number growing to 14000 the energy effect tangibly declines to 6 %.The thermal effectiveness of the vortex intensification with spherical lunules on the tube inside surface and the air moving inside does not exceed 13 % in the interval Re = (1−2 ⋅ 104 , which is distinctive for air the preheaters of steam-boilers. However, a greater energy effect (up to 33 % for the axial flowing is attained from emerging saliences on the tube inside surface beneath the spherical lacunae on the outside. The authors establish that employing discrete roughness in the form of transverse circular saliences (diaphragms allows attaining much greater heat-emission intensification (up to 70 % in the interval of Re = (10−100 ⋅ 103 as compared to the smooth tube. The paper shows that physical principles of the heat-emission vortex intensification by way of lunuling the round tubular surfaces differentiate from those applying artificial limited roughness in the form of pyramid frusta on the tube outside surfaces flowed around by the transverse flow. 

  20. Advantages and effects of nitrogen doping into the central channel of plasma in axially viewed-inductively coupled plasma optical emission spectrometry

    International Nuclear Information System (INIS)

    Graphical abstract: -- Highlights: •Addition of N2 to the nebulizer gas used in axially viewed-ICP OES is investigated. •A small flow of N2 (20 mL min−1) increases plasma robustness. •Addition of N2 through the nebulizer gas affects energy transfer in the ICP. •Matrix effects are mitigated by adding N2 and the ICP performance is maintained. -- Abstract: The effects and benefits of N2 addition to the central channel of the ICP through the nebulizer gas used in ICP OES with axial view configuration were investigated in the present study. The N2 flow rate, nebulizer gas flow rate, RF power and sample uptake rate were evaluated and compared for two sample introduction systems (pneumatic nebulization/aerosol desolvation and conventional pneumatic nebulization). It was observed that N2 did not affect solution nebulization and aerosol transport but affects the ICP characteristics. The higher thermal conductivity of N2 (in comparison with Ar) changes energy distribution in the ICP, observed by monitoring the signals of Ar emission lines and sodium emission. The ratio Mg(II)-280.270 nm/Mg(I)-285.213 nm was utilized as a diagnostic tool for plasma robustness. The addition of N2 (20 mL min−1) increased plasma robustness significantly and mitigated effects caused by Na, K and Ca. For 40 spectral lines evaluated, it was observed that the emission signals of ionic spectral lines were in general more affected by N2 than those of atomic spectral lines. Detection limits, precision, sensitivity and linearity of calibration curves obtained using N2-Ar-ICP were almost similar to those obtained using Ar-ICP. The analysis of 5 different reference materials revealed that accuracy was not degraded by adding N2 to the Ar-ICP

  1. Effective removal of heavy metals from industrial sludge with the aid of a biodegradable chelating ligand GLDA

    International Nuclear Information System (INIS)

    Highlights: • A novel readily biodegradable chelating ligand was employed to remove heavy metals. • The effects of different conditions on the extraction with GLDA were probed. • Species distribution of metals before and after extraction with GLDA was analyzed. • GLDA was effective for Cd extraction from sludge samples under various conditions. • GLDA offers special insights in the effective removal of heavy metals. - Abstract: Tetrasodium of N,N-bis(carboxymethyl) glutamic acid (GLDA), a novel readily biodegradable chelating ligand, was employed for the first time to remove heavy metals from industrial sludge generated from a local battery company. The extraction of cadmium, nickel, copper, and zinc from battery sludge with the presence of GLDA was studied under different experimental conditions such as contact times, pH values, as well as GLDA concentrations. Species distribution of metals in the sludge sample before and after extraction with GLDA was also analyzed. Current investigation showed that (i) GLDA was effective for Cd extraction from sludge samples under various conditions. (ii) About 89% cadmium, 82% nickel and 84% copper content could be effectively extracted at the molar ratio of GLDA:M(II) = 3:1 and at pH = 4, whereas the removal efficiency of zinc was quite low throughout the experiment. (iii) A variety of parameters, such as contact time, pH values, the concentration of chelating agent, stability constant, as well as species distribution of metals could affect the chelating properties of GLDA

  2. On renormalization of axial anomaly

    International Nuclear Information System (INIS)

    It is shown that multiplicative renormalization of the axial singlet current results in renormalization of the axial anomaly in all orders of perturbation theory. It is a necessary condition for the Adler - Bardeen theorem being valid. 10 refs.; 2 figs

  3. Axial compressor stability enhancement

    OpenAIRE

    Houghton, Timothy Oliver.

    2010-01-01

    Aircraft jet engines must operate in a stable manner at all times. One source of instability is compressor stall. Stall problems can be reduced by machining cavities into the compressor casing adjacent to the rotor blades. This ?casing treatment? is the focus of the present work. Two treatment configurations are tested: circumferential grooves cut into the casing above the rotor blades, and axial slots cut into the casing adjacent to the rotor blade leading edges. The performance of a single ...

  4. Effect of mixed-ligand complex formation on the volatility of alkaline-earth element β-diketonates

    International Nuclear Information System (INIS)

    Some aspects of effect of heteroligand complexing on structure, thermal stability and volatility of β-diketonates of alkaline earth elements are considered using own and literature data. Radius of M2+ ion increases from 0.99 up to 1.34 A in the Ca-Sr-Ba row and strength and coordination numbers of forming associates increase. The strength of molecular associates decreases and volatility increases when degree of branching and degree of fluorination of alkyl radicals in β-diketonate ligands increase

  5. Effectiveness of mixed ligand chelation for the removal of plutonium and americium in the hamster

    International Nuclear Information System (INIS)

    DTPA and the combination of DTPA plus salicylic acid or other benzene derivatives which are ortho-di-substituted with functional groups containing one or more oxygen and/or nitrogen atoms as electron donors, were tested for their ability to remove 239Pu and/or 241Am from hamsters. Mixed ligand chelation of these actinides by combination of DTPA and any one of these compounds did not result in an increased efficacy for the removal of actinides, as has been reported elsewhere

  6. Moessbauer effect study of iron(III)-inidazolidine nitroxyl-free radical ligand complex

    Energy Technology Data Exchange (ETDEWEB)

    Mulaba, A. [Technikon Witwatersrand, Metallurgy Department (South Africa); Kiremire, E. [University of the Witwatersrand, Chemistry Department (South Africa); Pollak, H. [University of the Witwatersrand, Physics Department (South Africa); Boeyens, J. [University of the Witwatersrand, Chemistry Department (South Africa)

    1999-09-15

    A new complex, [Fe(acac)L{sub 2}], bearing inidazolidine nitroxyl-free radical ligand (L{sup -}) was recently synthesised for biological studies. It proved to be biologically active against African sleeping sickness, plasmodium falciparum (malaria), leishmaniasis and chaga disease causative agents. Three ESR well resolved peaks indicated the presence of a free (unpaired) and chemically active electron in the complex. The structural complex ferric iron was found at the centre of two electric gradient whose the biggest is suggested to be initiated by the unpaired charge. No distinction between different cis isomers could be made.

  7. Moessbauer effect study of iron(III)-inidazolidine nitroxyl-free radical ligand complex

    International Nuclear Information System (INIS)

    A new complex, [Fe(acac)L2], bearing inidazolidine nitroxyl-free radical ligand (L-) was recently synthesised for biological studies. It proved to be biologically active against African sleeping sickness, plasmodium falciparum (malaria), leishmaniasis and chaga disease causative agents. Three ESR well resolved peaks indicated the presence of a free (unpaired) and chemically active electron in the complex. The structural complex ferric iron was found at the centre of two electric gradient whose the biggest is suggested to be initiated by the unpaired charge. No distinction between different cis isomers could be made

  8. Effects of single- and multi-organic acid ligands on adsorption of copper by Fe3O4/graphene oxide-supported DCTA.

    Science.gov (United States)

    Liu, Shaobo; Wang, Hui; Chai, Liyuan; Li, Meifang

    2016-09-15

    The Fe3O4/graphene oxide-supported 1,2-diaminocyclohexanetetraacetic acid composite (Fe3O4/GO/DCTA) was used as an adsorbent for Cu(II) removal. The effects of six organic acid ligands (formate, acetate, benzoate, oxalate, tartrate, and edetate) on the adsorption process were investigated in single- and multi-ligand systems. The results demonstrated that the adsorption processes were affected by solution pH and ionic strength. The experimental data of kinetics and isotherm followed the pseudo-second-order model and the Langmuir model, respectively. In the single-ligand systems, the presence of formate, acetate, and benzoate slightly altered the Cu(II) adsorption property, while the adsorption processes were significantly affected by the oxalate, tartrate, and edetate ligands. In the multi-ligand systems, the Cu(II) adsorption was influenced by the type and concentration of organic acid ligands. The sequence of the main effect was found to be: edetate>oxalate>benzoate>formate>tartrate>acetate, and the sequence of the two-factor interaction effect was found to be: AE (formate×tartrate)>BF (acetate×edetate)>AF (formate×edetate)>BD (acetate×oxalate)>AC (formate×benzoate)>AD (formate×oxalate)>AB (formate×acetate). PMID:27309949

  9. Density functional theory approach to gold-ligand interactions: Separating true effects from artifacts

    Science.gov (United States)

    Koppen, Jessica V.; Hapka, Michał; Modrzejewski, Marcin; Szcześniak, Małgorzata M.; Chałasiński, Grzegorz

    2014-06-01

    Donor-acceptor interactions are notoriously difficult and unpredictable for conventional density functional theory (DFT) methodologies. This work presents a reliable computational treatment of gold-ligand interactions of the donor-acceptor type within DFT. These interactions require a proper account of the ionization potential of the electron donor and electron affinity of the electron acceptor. This is accomplished in the Generalized Kohn Sham framework that allows one to relate these properties to the frontier orbitals in DFT via the tuning of range-separated functionals. A donor and an acceptor typically require different tuning schemes. This poses a problem when the binding energies are calculated using the supermolecular method. A two-parameter tuning for the monomer properties ensures that a common functional, optimal for both the donor and the acceptor, is found. A reliable DFT approach for these interactions also takes into account the dispersion contribution. The approach is validated using the water dimer and the (HAuPH3)2 aurophilic complex. Binding energies are computed for Au4 interacting with the following ligands: SCN-, benzenethiol, benzenethiolate anion, pyridine, and trimethylphosphine. The results agree for the right reasons with coupled-cluster reference values.

  10. Density functional theory approach to gold-ligand interactions: Separating true effects from artifacts

    International Nuclear Information System (INIS)

    Donor-acceptor interactions are notoriously difficult and unpredictable for conventional density functional theory (DFT) methodologies. This work presents a reliable computational treatment of gold-ligand interactions of the donor-acceptor type within DFT. These interactions require a proper account of the ionization potential of the electron donor and electron affinity of the electron acceptor. This is accomplished in the Generalized Kohn Sham framework that allows one to relate these properties to the frontier orbitals in DFT via the tuning of range-separated functionals. A donor and an acceptor typically require different tuning schemes. This poses a problem when the binding energies are calculated using the supermolecular method. A two-parameter tuning for the monomer properties ensures that a common functional, optimal for both the donor and the acceptor, is found. A reliable DFT approach for these interactions also takes into account the dispersion contribution. The approach is validated using the water dimer and the (HAuPH3)2 aurophilic complex. Binding energies are computed for Au4 interacting with the following ligands: SCN−, benzenethiol, benzenethiolate anion, pyridine, and trimethylphosphine. The results agree for the right reasons with coupled-cluster reference values

  11. PWR AXIAL BURNUP PROFILE ANALYSIS

    International Nuclear Information System (INIS)

    The purpose of this activity is to develop a representative ''limiting'' axial burnup profile for pressurized water reactors (PWRs), which would encompass the isotopic axial variations caused by different assembly irradiation histories, and produce conservative isotopics with respect to criticality. The effect that the low burnup regions near the ends of spent fuel have on system reactivity is termed the ''end-effect''. This calculation will quantify the end-effects associated with Pressurized Water Reactor (PWR) fuel assemblies emplaced in a hypothetical 21 PWR waste package. The scope of this calculation covers an initial enrichment range of 3.0 through 5.0 wt% U-235 and a burnup range of 10 through 50 GWd/MTU. This activity supports the validation of the process for ensuring conservative generation of spent fuel isotopics with respect to criticality safety applications, and the use of burnup credit for commercial spent nuclear fuel. The intended use of these results will be in the development of PWR waste package loading curves, and applications involving burnup credit. Limitations of this evaluation are that the limiting profiles are only confirmed for use with the B andW 15 x 15 fuel assembly design. However, this assembly design is considered bounding of all other typical commercial PWR fuel assembly designs. This calculation is subject to the Quality Assurance Requirements and Description (QARD) because this activity supports investigations of items or barriers on the Q-list (YMP 2001)

  12. PWR AXIAL BURNUP PROFILE ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    J.M. Acaglione

    2003-09-17

    The purpose of this activity is to develop a representative ''limiting'' axial burnup profile for pressurized water reactors (PWRs), which would encompass the isotopic axial variations caused by different assembly irradiation histories, and produce conservative isotopics with respect to criticality. The effect that the low burnup regions near the ends of spent fuel have on system reactivity is termed the ''end-effect''. This calculation will quantify the end-effects associated with Pressurized Water Reactor (PWR) fuel assemblies emplaced in a hypothetical 21 PWR waste package. The scope of this calculation covers an initial enrichment range of 3.0 through 5.0 wt% U-235 and a burnup range of 10 through 50 GWd/MTU. This activity supports the validation of the process for ensuring conservative generation of spent fuel isotopics with respect to criticality safety applications, and the use of burnup credit for commercial spent nuclear fuel. The intended use of these results will be in the development of PWR waste package loading curves, and applications involving burnup credit. Limitations of this evaluation are that the limiting profiles are only confirmed for use with the B&W 15 x 15 fuel assembly design. However, this assembly design is considered bounding of all other typical commercial PWR fuel assembly designs. This calculation is subject to the Quality Assurance Requirements and Description (QARD) because this activity supports investigations of items or barriers on the Q-list (YMP 2001).

  13. A Research on the Effects of Exhaust Braking on the Axial Thrust of Turbocharger%排气制动对增压器轴向载荷影响的研究

    Institute of Scientific and Technical Information of China (English)

    龚金科; 黄张伟; 胡辽平; 李靖; 余明果; 陈韬

    2015-01-01

    针对车辆上同时应用排气制动与涡轮增压的情况,研究了排气制动对增压器轴向载荷的影响。通过排气制动与增压器联动试验测量了增压器在各个工况下的轴向载荷,从而确定了数值计算所需的边界条件,并通过数值计算获取了增压器在各个工况的轴向载荷的分布情况。结果表明,与正常工况相比,增压器在排气制动工况下其轴向载荷显著增大,且排气背压越高,增压器轴向载荷越大;涡轮级轴向载荷反向且增大;压气机级轴向载荷显著下降,但方向不变。%The effects of exhaust braking on the axial thrust of turbocharger are studied for the vehicles with both exhaust braking and turbo-charging applied. The axial thrust of turbocharger in different working conditions are measured by the linkage test of exhaust braking and turbo-charging with the boundary conditions for numerical com-putation determined, and the distribution patterns of axial thrust of turbocharger in different conditions are obtained by numerical computation. The results show that compared with normal condition, in exhaust braking condition, the axial thrust of turbocharger significantly increases ( the higher the exhaust back pressure, the larger the axial thrust of turbocharger) , the axial thrust of turbine increases with its direction reversed, and the axial thrust of compressor greatly reduces with its direction unchanged.

  14. Molecular path for ligand search

    Institute of Scientific and Technical Information of China (English)

    Tao Lu; Yuan Yuan Qiao; Pan Wen Shen

    2011-01-01

    A ligand is a small molecule bind to several residues of a receptor. We adapt the concept of molecular path for effective ligand search with its contacting residues. Additionally, we allow wild type definitions on atoms and bonds of molecular paths for fuzzy algorithms on structural match. We choose hydrogen bond interactions to characterize the binding mode of a ligand by several proper molecular paths and use them to query the deposited ligands in PDBe that interact with their residues in the same way. Expression of molecular path and format of database entries are described with examples. Our molecular path provides a new approach to explore the ligand-receptor interactions and to provide structural framework reference on new ligand design.

  15. Ylide Ligands

    OpenAIRE

    Esteban P. Urriolabeitia

    2010-01-01

    The use of ylides of P, N, As, or S as ligands toward transition metals is still a very active research area in organometallic chemistry. This fact is mainly due to the nucleophilic character of the ylides and to their particular bonding properties and coordination modes. They can behave as monodentate or bidentate chelate or bridging species, they can be used as chiral auxiliary reagents, and they are interesting reaction intermediates or useful starting materials in a wide ...

  16. Trypsin pretreatment dissociates the effect of GTP and Na+ on ligand binding to human platelet α2-adrenoreceptors

    International Nuclear Information System (INIS)

    The authors recently showed that maximal concentration of trypsin (TR) inactivated only 70-80% of specific [3H]yohimbine (3H-Y) binding to human platelet α2-adrenoreceptors (α2-AR). The effect of TR on the interaction between the agonist, epinephrine, and GTP or Na+ on 3H-Y binding to α2-AR of human platelets was investigated in the present study. Partially purified α2-AR protein was pretreated with 500 μg TR for 3 min at 350C, the proteolytic action was terminated by specific TR-inhibitor, and the membranes were washed twice prior to specific ligand binding studies. Under these conditions, TR produced a 40-50% reduction of specific 3H-Y binding. Further characterization of the specific ligand binding by Scatchard plots showed that TR did not modify the affinity of the α2-AR to the agonist or the antagonist or the antagonists. However, in the TR-pretreated membranes, the ability of GTP to reduce the receptor affinity for epinephrine was lost. The effect of Na+, on the other hand, remained intact under these conditions. Thus, TR can selectively destroy the GTP-α2-AR but not Na+-α2-AR interaction suggesting that the GTP- and Na+-binding proteins are distinct

  17. Effect of halides addition on the ligand field of chromium in alkali borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, M.A., E-mail: moukhtar_hassan@yahoo.com

    2013-10-15

    Highlights: •The 10 KM–64.7 B{sub 2}O{sub 3}–25 Na{sub 2}O–0.3 Cr{sub 2}O{sub 3} (M = Cl, Br and I) glassy system was prepared by a quenching method. •Optical basicity, ligand field theory optical band gap energy, refractive index, ESR and IR were studied. •The electronegativity plays an important role in deforming the crystal field around the transition metal ions. •The crystal-field sites of KCl or KBr sample are very strong compared to the very weak one in the KI sample. -- Abstract: Borate oxide glass system of composition 10 KM–64.7 B{sub 2}O{sub 3}–25 Na{sub 2}O–0.3 Cr{sub 2}O{sub 3} (M = Cl, Br and I) was prepared by conventional melt quenching technique. The amorphous nature of the investigated glasses was checked by the X-ray diffraction (XRD) technique. The optical basicity of the system has been calculated, and was found to increase by going from KCl to KBr and to KI. Optical absorption spectra were recorded in the UV–visible range. Through a careful analysis of the data, the ligand field parameters (crystal field strength Dq, Racah parameters B and nephelauxetic functions h) and the optical parameters (optical band gap, Urbach tail band width, and refractive index) have been estimated. The obtained results reveal a strong correlation between that ligand field parameters and the type of halogen atom; the crystal-field strength of KCl or KBr samples are very pronounced but it is rather weak in the KI sample. Electron spin resonance (ESR) has been used to probe the valency of the Chromium ions. The resulting ESR parameters revealed that chromium ions are predominantly in the trivalent state with traces of hexavalent state. Using Infrared spectroscopy (IR) information on the boron structural units has been obtained. The N{sub 4} ratio increases by replacing the KCl by KBr or KI, and it was found that the tetrahedral coordination of Cr{sup +} ions becomes preferential in the host glasses with increasing the optical basicity.

  18. Effect of Ligand Structural Isomerism in Formation of Calcium Coordination Networks

    Energy Technology Data Exchange (ETDEWEB)

    Plonka A. M.; Parise J.; Banerjee, D.

    2012-03-28

    Using different structural isomers (2,5-; 2,4-; 2;6-; 3,4-; 3,5-) of pyridinedicarboxylic acid, nine calcium-based coordination networks were synthesized under hydro-/solvothermal conditions and/or were produced via solvent recrystallization of previously synthesized compounds. The coordination networks reported were characterized using single crystal X-ray diffraction and thermal methods. They show diverse structural topologies, depending on the ligand geometry and coordinated solvent molecules, with inorganic connectivity motifs ranging from isolated octahedra to infinite chains, layer and a three-dimensional dense framework. The as-synthesized and desolvated networks further show structural transformation to hydrated phases through dissolution/reformation pathways. The process is likely driven by the high hydration energy of the calcium metal center.

  19. Effect of anion and solvent in extractions of cations with neutral cation binding ligands

    International Nuclear Information System (INIS)

    Mechanism of extraction of M3+ ions by neutral ligands L from acidic media is presented. This is based on the ion pair extraction model and the occurrence of maxima of dependence of D(M3+) on cH is accounted for. The extraction constants of HLX, where L is selected malonamide, into isopropylbenzene for four inorganic anions (Cl-, NO3-, ClO4-, and dicarbollide anion [(C2B9H11)2Co]-) well correlate with individual extraction constants of the anions in the system water-nitrobenzene Ki and it is proposed to use Ki values as a parameter also for the systems where ion association is prevailing. (authors)

  20. Critical Axial Load

    Directory of Open Access Journals (Sweden)

    Walt Wells

    2008-01-01

    Full Text Available Our objective in this paper is to solve a second order differential equation for a long, simply supported column member subjected to a lateral axial load using Heun's numerical method. We will use the solution to find the critical load at which the column member will fail due to buckling. We will calculate this load using Euler's derived analytical approach for an exact solution, as well as Euler's Numerical Method. We will then compare the three calculated values to see how much they deviate from one another. During the critical load calculation, it will be necessary to calculate the moment of inertia for the column member.

  1. Effect of iodination site on binding of radiolabeled ligand by insulin antibodies and insulin autoantibodies

    International Nuclear Information System (INIS)

    Four human insulins and four porcine insulins, each monoiodinated to the same specific activity at one of the four tyrosine residues (A14, A19, B16, B26) and purified by reversed-phase liquid chromatography, were tested in a radiobinding assay against a panel of insulin-antibody (IA)-positive sera from 10 insulin-treated diabetics and insulin-autoantibody-positive (IAA) sera from 10 nondiabetics. Of the 10 IAA-positive sera, five were fully cross reactive with both insulin species, and five were specific for human insulin. The rank order of binding of sera with the four ligands from each species was random for IA (mean rank values of 1.9 for A14, 2.0 for A19, 2.5 for B16, and 3.6 for B26 from a possible ranking range of 1 to 4), but more consistent for non-human-insulin-specific IAA (mean rank values 1.3 for A14, 3.8 for A19, 1.7 for B16, and 3.2 for B26 for labeled human insulins; 1.2 for A14, 4.0 for A19, 1.8 for B16, and 3.0 for B26 for labeled porcine insulins). The rank order of binding was virtually uniform for human-insulin-specific IAA (mean values 1.2 for A14, 3.0 for A19, 1.8 for B16, and 4.0 for B26). The influence of iodination site on the binding of labeled insulin appears to be dependent on the proximity of the labeled tyrosine to the antibody binding site and the clonal diversity, or restriction, of insulin-binding antibodies in the test serum. When IA and IAA are measured, the implications of this study regarding the choice of assay ligand may be important

  2. The specific heat loss combined with the thermoelastic effect for an experimental analysis of the mean stress influence on axial fatigue of stainless steel plain specimens

    Directory of Open Access Journals (Sweden)

    G. Meneghetti

    2014-10-01

    Full Text Available The energy dissipated to the surroundings as heat in a unit volume of material per cycle, Q, was recently proposed by the authors as fatigue damage index and it was successfully applied to correlate fatigue data obtained by carrying out fully reversed stress- and strain-controlled fatigue tests on AISI 304L stainless steel plain and notched specimens. The use of the Q parameter to analyse the experimental results led to the definition of a scatter band having constant slope from the low- to the high-cycle fatigue regime. In this paper the energy approach is extended to analyse the influence of mean stress on the axial fatigue behaviour of unnotched cold drawn AISI 304L stainless steel bars. In view of this, stress controlled fatigue tests on plain specimens at different load ratios R (R=-1; R=0.1; R=0.5 were carried out. A new energy parameter is defined to account for the mean stress effect, which combines the specific heat loss Q and the relative temperature variation due to the thermoelastic effect corresponding to the achievement of the maximum stress level of the stress cycle. The new two-parameter approach was able to rationalise the mean stress effect observed experimentally. It is worth noting that the results found in the present contribution are meant to be specific for the material and testing condition investigated here.

  3. Field-effect measurements of mobility and carrier concentration of Cu2S colloidal quantum dot thin films after ligand exchange

    International Nuclear Information System (INIS)

    Colloidal quantum dots (CQDs) of copper sulfide (Cu2S), an earth-abundant semiconductor, have a number of intriguing applications that require knowledge of their electrical properties. Depending on stoichiometry, mobility, and surface treatment, applications include photoabsorbers for solar cells, tunable plasmonics, and counter-electrodes for polysulfate electrolytes. However, there have not been any direct measurements of electrical properties in Cu2S CQD thin films. Here, we exchange as synthesized dodecanethiol ligands with short ethanedithiol or ethylenediamine ligands to form thin films of coupled Cu2S CQDs. The mobility and carrier concentration were found to vary by ligand treatment from 10−5 cm2/Vs and 1019 holes/cm3 for ethanedithiol ligands to 10−3 cm2/Vs and 1020 holes/cm3 for ethylenediamine. These results are consistent with the carrier concentrations inferred from sub-bandgap surface-plasmon-resonances measured by infrared spectroscopy. These results will be useful when designing Cu2S materials for future applications. - Highlights: • Colloidal Cu2S quantum dots were synthesized and characterized. • Ligand exchange was performed to alter the Cu2S nanocrystal properties. • Ligand exchange was studied using photoluminescence and infrared spectroscopy. • Field effect mobility and carrier concentration were directly measured. • Carrier concentration was compared to estimates from surface plasmon resonances

  4. A study on synergistic effects and protonation of a selected calixarene based picolinamide ligand used in the An/Ln separation

    International Nuclear Information System (INIS)

    A series of liquid-liquid extraction tests was performed on the ligand hexakis(3-N-picoline-amidepropyloxy)calix[6]arene (PAR4). First, a screening campaign was carried out, in order to select the best organic solvent to be coupled to the aforementioned calixarene ligand. 2-Nitrophenyl hexyl ether (NPHE) was chosen to this purpose, and it was used in all the subsequent experiments, because of its excellent properties from both the viewpoints of calixarene solubility and ligand extracting capabilities. In solvent extraction tests, 241Am was used as representative of minor actinides, while 152Eu was employed to simulate lanthanides. Distribution coefficients and separation factors were obtained via gamma spectrometry. In addition, the synergism between the ligand and the lipophilic dicarbollide anion Cesium commo-3,3-cobalta-Bis(8,9,12 tribromo-1,2 dicarba-closo-Dodecarborane)ate(1-) (Br-Cosan) was investigated. Experimental results indicate that at pH 3 2 a strong synergistic effect between the calixarene ligand and Br-Cosan takes place. At higher acidity, on the other hand, the ligand protonation dramatically affects the efficiency and selectivity of the system. (author)

  5. Field-effect measurements of mobility and carrier concentration of Cu{sub 2}S colloidal quantum dot thin films after ligand exchange

    Energy Technology Data Exchange (ETDEWEB)

    Brewer, Adam S.; Arnold, Michael S., E-mail: msarnold@wisc.edu

    2014-09-30

    Colloidal quantum dots (CQDs) of copper sulfide (Cu{sub 2}S), an earth-abundant semiconductor, have a number of intriguing applications that require knowledge of their electrical properties. Depending on stoichiometry, mobility, and surface treatment, applications include photoabsorbers for solar cells, tunable plasmonics, and counter-electrodes for polysulfate electrolytes. However, there have not been any direct measurements of electrical properties in Cu{sub 2}S CQD thin films. Here, we exchange as synthesized dodecanethiol ligands with short ethanedithiol or ethylenediamine ligands to form thin films of coupled Cu{sub 2}S CQDs. The mobility and carrier concentration were found to vary by ligand treatment from 10{sup −5} cm{sup 2}/Vs and 10{sup 19} holes/cm{sup 3} for ethanedithiol ligands to 10{sup −3} cm{sup 2}/Vs and 10{sup 20} holes/cm{sup 3} for ethylenediamine. These results are consistent with the carrier concentrations inferred from sub-bandgap surface-plasmon-resonances measured by infrared spectroscopy. These results will be useful when designing Cu{sub 2}S materials for future applications. - Highlights: • Colloidal Cu2S quantum dots were synthesized and characterized. • Ligand exchange was performed to alter the Cu2S nanocrystal properties. • Ligand exchange was studied using photoluminescence and infrared spectroscopy. • Field effect mobility and carrier concentration were directly measured. • Carrier concentration was compared to estimates from surface plasmon resonances.

  6. Effects of the ligand shell on the single-molecule magnet behavior in Co{sub 5} clusters

    Energy Technology Data Exchange (ETDEWEB)

    Nehrkorn, J.; Waldmann, O. [Physikalisches Institut, Universitaet Freiburg, D-79104 Freiburg (Germany); Kloewer, F.; Lan, Y.H.; Powell, A.K. [Institut fuer Anorganische Chemie, Universitaet Karlsruhe, D-76128 Karlsruhe (Germany)

    2009-07-01

    Enhancing single-molecule magnet (SMM) behavior in molecular nanomagnets to higher temperatures is one of the great aims in this field. Incorporating Co{sup I}I ions, because of their high magnetic anisotropy, has recently attracted much interest. In this work we study three Co{sub 5} clusters which exhibit similar cores, but differ in their coordination spheres due to the use of different ligands. Our dc and ac magnetic data revealed that one compound is clearly a SMM, one is a weak SMM, and the third one is no SMM. We interpret the data on the basis of an effective-spin Hamiltonian, which reproduces the magnetic data well and allows us to understand the trend of SMM behavior. A subtle effect of highly anisotropic systems was observed: anisotropic ferromagnetic couplings together with highly anisotropic g matrices can yield susceptibility curves with a temperature dependence usually associated to antiferromagnetic interactions.

  7. Numerical Study Of The Effects Of Preloading, Axial Loading And Concrete Shrinkage On Reinforced Concrete Elements Strengthened By Concrete Layers And Jackets

    International Nuclear Information System (INIS)

    In this study, the technique of seismic strengthening existing reinforced concrete columns and beams using additional concrete layers and jackets is examined. The finite element method and the finite element program ATENA is used in this investigation. When a reinforced jacket or layer is being constructed around a column it is already preloaded due to existing service loads. This effect has been examined for different values of the axial load normalized to the strengthened column. The techniques of strengthening with a concrete jacket or a reinforced concrete layer on the compressive side of the column are examined. Another phenomenon that is examined in this study is the shrinkage of the new concrete of an additional layer used to strengthen an existing member. For this investigation, a simply supported beam with an additional reinforced concrete layer on the tensile side is examined. The results demonstrate that the effect of preloading is important when a reinforced concrete layer is being used with shear connectors between the old and the new reinforcement. It was also found that the shrinkage of the new concrete reduces the strength of the strengthened beam and induces an initial sliding between the old and the new concrete

  8. [The effect of a low-dose hydrochlorothiazide therapy on the bone mineral content of the axial and peripheral skeleton].

    Science.gov (United States)

    Jergas, M; Kosow, A; Uffmann, M; Schmutz, G; Böckenförde, J B; Glüer, C C; Köster, O

    1994-12-01

    An increase in bone mineral content (BMC) as well as a decrease in the incidence of fracture of the proximal femur have been described in patients on thiazide diuretic treatment. A study was undertaken to assess, by means of dual X-ray absorptiometry, the effect of chronic low-dosage antihypertensive treatment with hydrochlorothiazide (HCT; HCT or other drugs with potential effects on mineral bone metabolism. In men who had been on HCT for more than 5 years, BMC of the lumbar vertebrae was higher by 10.3% and of the radius by 3.8% than among the controls (differences not significant). In women who had been on HCT for more than 5 years, the corresponding increases were 19.6% (P HCT for less than 5 years there were no significant differences compared with the control group. There were no significant differences between the groups relating as regards the proximal radius which, in contrast to the ultradistal radius, consists predominantly of cortical bone. -These data indicate that, while HCT has only a slight influence on BMC, it can be considered to have a desirable associated effect in the antihypertensive treatment of elderly patients. PMID:7988364

  9. Chaperonin GroEL Reassembly: An Effect of Protein Ligands and Solvent Composition

    Directory of Open Access Journals (Sweden)

    Nataliya Ryabova

    2014-04-01

    Full Text Available Chaperonin GroEL is a complex oligomeric heat shock protein (Hsp60 assisting the correct folding and assembly of other proteins in the cell. An intriguing question is how GroEL folds itself. According to the literature, GroEL reassembly is dependent on chaperonin ligands and solvent composition. Here we demonstrate dependence of GroEL reassembly efficiency on concentrations of the essential factors (Mg2+, ADP, ATP, GroES, ammonium sulfate, NaCl and glycerol. Besides, kinetics of GroEL oligomerization in various conditions was monitored by the light scattering technique and proved to be two-exponential, which suggested accumulation of a certain oligomeric intermediate. This intermediate was resolved as a heptamer by nondenaturing blue electrophoresis of GroEL monomers during their assembly in the presence of both Mg-ATP and co-chaperonin GroES. Presumably, this intermediate heptamer plays a key role in formation of the GroEL tetradecameric particle. The role of co-chaperonin GroES (Hsp10 in GroEL assembly is also discussed.

  10. Effects of increasing doses of samarium-153-ethylenediaminetetramethylene phosphonate on axial and appendicular skeletal growth in juvenile rabbits

    International Nuclear Information System (INIS)

    Introduction: Targeted radiotherapy using samarium-153-ethylenediaminetetramethylene phosphonate (153Sm-EDTMP) is currently under investigation for treatment of osteosarcoma. Osteosarcoma often occurs in children, and previous studies on a juvenile rabbit model demonstrated that clinically significant damage to developing physeal cartilage may occur as a result of systemic 153Sm-EDTMP therapy. The aim of this study was to evaluate the late effects of 153Sm-EDTMP on skeletal structures during growth to maturity and to determine if there is a dose response of 153Sm-EDTMP on growth of long bones. Methods: Female 8-week-old New Zealand white rabbits were divided into three treatment groups plus controls. Each rabbit was intravenously administered a predetermined dose of 153Sm-EDTMP. Multiple bones of each rabbit were radiographed every 2 months until physeal closure, with subsequent measurements made to assess for abbreviated bone growth. Statistical analyses were performed to determine the differences in bone length between groups, with significance set at P153Sm-EDTMP. Further investigation regarding the effects of bone-seeking radiopharmaceuticals on bone growth and physeal cartilage is warranted

  11. Axial skeletal CT densitometry

    International Nuclear Information System (INIS)

    Since the discovery of the Roentgen ray a precise and accurate assessment of bone mineral content has been a challenge to many investigators. A number of methods have been developed but no one satisfied. Considering its technical possibilities computed tomography is very promising in determination of bone mineral content (BMC). The new modality enables BMC estimations in the axial skeletal trabecular bone. CT densitometry can be performed on a normal commercially available third generation whole body CT scanner. No dedicated device in a special clinical set-up is necessary. In this study 106 patients, most of them clinically suspected of osteoporosis, were examined. The new method CT densitometry has been evaluated. The results have been correlated to alternative BMC determination methods. (Auth.)

  12. Humic Acid Complexation of Th, Hf and Zr in Ligand Competition Experiments: Metal Loading and Ph Effects

    Science.gov (United States)

    Stern, Jennifer C.; Foustoukos, Dionysis I.; Sonke, Jeroen E.; Salters, Vincent J. M.

    2014-01-01

    The mobility of metals in soils and subsurface aquifers is strongly affected by sorption and complexation with dissolved organic matter, oxyhydroxides, clay minerals, and inorganic ligands. Humic substances (HS) are organic macromolecules with functional groups that have a strong affinity for binding metals, such as actinides. Thorium, often studied as an analog for tetravalent actinides, has also been shown to strongly associate with dissolved and colloidal HS in natural waters. The effects of HS on the mobilization dynamics of actinides are of particular interest in risk assessment of nuclear waste repositories. Here, we present conditional equilibrium binding constants (Kc, MHA) of thorium, hafnium, and zirconium-humic acid complexes from ligand competition experiments using capillary electrophoresis coupled with ICP-MS (CE- ICP-MS). Equilibrium dialysis ligand exchange (EDLE) experiments using size exclusion via a 1000 Damembrane were also performed to validate the CE-ICP-MS analysis. Experiments were performed at pH 3.5-7 with solutions containing one tetravalent metal (Th, Hf, or Zr), Elliot soil humic acid (EHA) or Pahokee peat humic acid (PHA), and EDTA. CE-ICP-MS and EDLE experiments yielded nearly identical binding constants for the metal- humic acid complexes, indicating that both methods are appropriate for examining metal speciation at conditions lower than neutral pH. We find that tetravalent metals form strong complexes with humic acids, with Kc, MHA several orders of magnitude above REE-humic complexes. Experiments were conducted at a range of dissolved HA concentrations to examine the effect of [HA]/[Th] molar ratio on Kc, MHA. At low metal loading conditions (i.e. elevated [HA]/[Th] ratios) the ThHA binding constant reached values that were not affected by the relative abundance of humic acid and thorium. The importance of [HA]/[Th] molar ratios on constraining the equilibrium of MHA complexation is apparent when our estimated Kc, MHA values

  13. Improving the lattice axial vector current

    CERN Document Server

    Horsley, R; Perlt, H; Rakow, P E L; Schierholz, G; Schiller, A; Zanotti, J M

    2015-01-01

    For Wilson and clover fermions traditional formulations of the axial vector current do not respect the continuum Ward identity which relates the divergence of that current to the pseudoscalar density. Here we propose to use a point-split or one-link axial vector current whose divergence exactly satisfies a lattice Ward identity, involving the pseudoscalar density and a number of irrelevant operators. We check in one-loop lattice perturbation theory with SLiNC fermion and gauge plaquette action that this is indeed the case including order $O(a)$ effects. Including these operators the axial Ward identity remains renormalisation invariant. First preliminary results of a nonperturbative check of the Ward identity are also presented.

  14. The axial distribution of reactivity coefficients

    International Nuclear Information System (INIS)

    The purpose of the present work is to investigate the correlation of the axial distributions of the different reactivity coefficients with the neutron flux and the neutron flux squared. Calculations were carried out for the Zion Unit 2 PWR. Reactivity coefficients, forward fluxes and adjoint fluxes were all computed and correlations obtained. The core length was divided into 7 axial regions in order to obtain the effect on reactivity in the reactor as a whole of changing the cross sections in each axial region in turn. The parameters chosen for change were coolant density, coolant temperature and fuel temperature. The results appear to bear out our original hypothesis that the reactivity coefficient profiles have a higher positive correlation with the total flux squared profile than with the linear flux profile. (authors). 5 refs., 2 figs

  15. Transverse vibration characteristics of axially moving viscoelastic plate

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yin-feng; WANG Zhong-min

    2007-01-01

    The dynamic characteristics and stability of axially moving viscoelastic rectangular thin plate are investigated. Based on the two dimensional viscoelastic differential constitutive relation, the differential equations of motion of the axially moving viscoelastic plate are established. Dimensionless complex frequencies of an axially moving viscoelastic plate with four edges simply supported, two opposite edges simply supported and other two edges clamped are calculated by the differential quadrature method. The effects of the aspect ratio, moving speed and dimensionless delay time of the material on the transverse vibration and stability of the axially moving viscoelastic plate are analyzed.

  16. Laboratory model study of the effect of aeration on axial velocity attenuation of turbulent jet flows in plunge pool

    Institute of Scientific and Technical Information of China (English)

    邓军; 张法星; 田忠; 许唯临; 刘斌; 卫望汝

    2015-01-01

    In the laboratory model experiment, the velocities of the jet flow along the axis are measured, using the CQY−Z8a velocity-meter. The velocity attenuations of the jet flow along the axis under different conditions are studied. The effects of the aeration concentration, the initial jet velocity at the entry and the thickness of the jet flow on the velocity attenuation of the jet flow are analyzed. It is seen that the velocity attenuation of the jet flow along the axis sees a regular variation. It is demonstrated by the test results that under the experimental conditions, the velocity along the axis decreases linearly. The higher the air concentration is, the faster the velocity will be decayed. The absolute value of the slopeK increases with the rise of the air concentration. The relationship can be defined as=a+bKACK. The coefficientA is 0.03 under the experimental conditions. With the low air concentration of the jet flow, the thinner the jet flow is, the faster the velocity will be decayed. With the increase of the air concentra- tion, the influence of the thickness of the jet flow on the velocity attenuation is reduced. When the air concentration is increased to a certain value, the thickness of the jet flow may not have any influence on the velocity attenuation. The initial jet velocity itself at the entry has no influence on the variation of the velocity attenuation as the curves of the velocity attenuation at different velocities at the entry are practically parallel, even coinciding one with another. Therefore, improving the air concentration of the jet flow and disper- sing the jet flow in the plunge pool could reduce the influence of the jet flow on the scour.

  17. Phosphinogold(I) dithiocarbamate complexes: effect of the nature of phosphine ligand on anticancer properties.

    Science.gov (United States)

    Keter, Frankline K; Guzei, Ilia A; Nell, Margo; Zyl, Werner E van; Darkwa, James

    2014-02-17

    The reactions of potassium salts of the dithiocarbamates L {where L = pyrazolyldithiocarbamate (L1), 3,5-dimethylpyrazolyldithiocarbamate (L2), or indazolyldithiocarbamate (L3)} with the gold precursors [AuCl(PPh3)], [Au2Cl2(dppe)], [Au2Cl2(dppp)], or [Au2Cl2(dpph)] lead to the new gold(I) complexes [AuL(PPh3)] (1-3), [Au2L2(dppe)] (4-6), [(Au2L2)(dppp)] (7-9), and [Au2(L)2(dpph)] (10-12) {where dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,3-bis(diphenylphosphino)propane, and dpph = 1,6-bis(diphenylphosphino)hexane}. These gold compounds were characterized by a combination of NMR and infrared spectroscopy, microanalysis, and mass spectrometry; and in selected cases by single-crystal X-ray crystallography. Compounds 4-6, which have dppe ligands, are unstable in solution for prolonged periods, with 4 readily transforming to the Au18 cluster [Au18S8(dppe)6]Cl2 (4a) in dichloromethane. Compounds 1-3 and 7-12 are all active against human cervical epithelioid carcinoma (HeLa) cells, but the most active compounds are 10 and 11, with IC50 values of 0.51 μM and 0.14 μM, respectively. Compounds 10 and 11 are more selective toward HeLa cells than they are toward normal cells, with selectivities of 25.0 and 70.5, respectively. Further tests, utilizing the 60-cell-line Developmental Therapeutics Program at the National Cancer Institute (U.S.A.), showed 10 and 11 to be active against nine other types of cancers. PMID:24476103

  18. Axially symmetric SU(3) gravitating skyrmions

    Energy Technology Data Exchange (ETDEWEB)

    Ioannidou, Theodora [Maths Division, School of Technology, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece)]. E-mail: ti3@auth.gr; Kleihaus, Burkhard [Institut fuer Physik, Universitaet Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany)]. E-mail: kleihaus@theorie.physik.uni-oldenburg.de; Zakrzewski, Wojtek [Department of Mathematical Sciences, University of Durham, Durham DH1 3LE (United Kingdom)]. E-mail: w.j.zakrzewski@durham.ac.uk

    2004-10-21

    Axially symmetric gravitating multi-skyrmion configurations are obtained using the harmonic map ansatz introduced in [J. Math. Phys. 40 (1999) 6353]. In particular, the effect of gravity on the energy and baryon densities of the SU(3) non-gravitating multi-skyrmion configurations is studied in detail.

  19. Axially symmetric SU(3) Gravitating Skyrmions

    CERN Document Server

    Ioannidou, T A; Zakrzewski, W J; Ioannidou, Theodora; Kleihaus, Burkhard; Zakrzewski, Wojtek

    2004-01-01

    Axially symmetric gravitating multi-skyrmion configurations are obtained using the harmonic map ansatz introduced in [1]. In particular, the effect of gravity on the energy and baryon densities of the SU(3) non-gravitating multi-skyrmion configurations is studied in detail.

  20. Axially symmetric SU(3) gravitating skyrmions

    International Nuclear Information System (INIS)

    Axially symmetric gravitating multi-skyrmion configurations are obtained using the harmonic map ansatz introduced in [J. Math. Phys. 40 (1999) 6353]. In particular, the effect of gravity on the energy and baryon densities of the SU(3) non-gravitating multi-skyrmion configurations is studied in detail

  1. Effect of proximal contact strength on the three-dimensional displacements of implant-supported cantilever fixed partial dentures under axial loading

    Institute of Scientific and Technical Information of China (English)

    Zhen-zhen PENG; Xin-min CHEN; Jun WANG; Ai-jie LI; Zu-jie XU

    2013-01-01

    Objective:This study investigated the effect of proximal contact strength on the three-dimensional displacements of cantilever fixed partial denture (CFPD) under vertically concentrated loading with digital laser speckle (DLS) technique.Methods:Fresh mandible of beagle dog was used to establish the implant-supported CFPD for specimen.DLS technique was employed for measuring the three-dimensional displacement of the prosthesis under vertically concentrated loading ranging from 200 to 3000 g.The effect of the contact tightness on the displacement of CFPD was investigated by means of changing the contact tightness.Results:When an axial concentrated loading was exerted on the pontic of the implant-supported CFPD,the displacement of the CFPD was the greatest.The displacement of the prosthesis decreased with the increase of contact strength.When the contact strength was 0,0.95,and 3.25 N,the displacement of the buccolingual direction was smaller than that of the mesiodistal direction but greater than that of the occlusogingival direction.When the force on the contact area was 6.50 N,the mesiodistal displacement of the prosthesis was the biggest while the buccolingual displacement was the smallest.Conclusions:The implantsupported CFPD is an effective therapy for fully or partially edentulous patients.The restoration of the contact area and the selection of the appropriate contact strength can reduce the displacement of the CFPD,and get a better stress distribution.The most appropriate force value is 3.25 N in this study.

  2. Axial anomaly in nonrenormalizable theories

    International Nuclear Information System (INIS)

    The anomaly for the axial current in nonrenormalizable theories with electromagnetic coupling is considered. The spinor electrodynamics with Pauli term is examined in detail using the Feynman graph technique and the point-splitting method. The same finite value for the axial anomaly emerges. (author)

  3. Structural insights into the counterion effects on the manganese(iii) spin crossover system with hexadentate Schiff-base ligands.

    Science.gov (United States)

    Wang, Shi; Xu, Wu-Tan; He, Wen-Rui; Takaishi, Shinya; Li, Yong-Hua; Yamashita, Masahiro; Huang, Wei

    2016-04-01

    A series of new salts [Mn(5-MeO-sal-N-1,5,8,12)]Y (Y = ClO4 for 1, Y = BF4 for 2, Y = NO3 for 3 and Y = CF3SO3 for 4) based on the six-coordinated mononuclear manganese(iii) Schiff-base complex cation [Mn(5-MeO-sal-N-1,5,8,12)](+), has been investigated to determine the impact of counter anion effects, intramolecular ligand distortion and intermolecular supramolecular structures on the spin crossover (SCO) behavior. The SCO in salt 1 has resulted in a crystallographic observation of the coexistence of high-spin (HS, S = 2) and low-spin (LS, S = 1) manganese(iii) complex cations in equal proportions around 100 K. At room temperature, the two crystallographically distinct manganese centers are both close to the complete HS state. Only one of the two slightly different units undergoes SCO in the temperature range 300-180 K, whereas the other remains in the HS state down to 20 K. For salts 2 and 3, crystal structural analysis indicates change in the anion from ClO4(-) to BF4(-) and NO3(-) was led to the close arrangement of the cations and the stacking between phenyl groups from the ligands. With CF3SO3(-) as the counterion, although the cations and the anions separate clearly in one direction, the close arrangement of cations in other directions precludes the spin transformation of the Mn(iii) cations. Magnetic measurements on 2-4 indicate that the manganese(iii) complex cations remain in the HS state in the temperature range 2-300 K. PMID:26927027

  4. Teratogenic effects of triphenyltin on embryos of amphibian (Xenopus tropicalis): a phenotypic comparison with the retinoid X and retinoic acid receptor ligands.

    Science.gov (United States)

    Yu, Lin; Zhang, Xiaoli; Yuan, Jing; Cao, Qinzhen; Liu, Junqi; Zhu, Pan; Shi, Huahong

    2011-09-15

    Triphenyltin (TPT) has high binding affinity with the retinoid X receptor (RXR) in animals. The natural ligand of RXR, 9-cis-retinoic acid (RA), is known to induce featured malformations in vertebrate embryos by disrupting RA signal. Limited information is available on the TPT effects on amphibians. We exposed embryos of amphibian (Xenopus tropicalis) to TPT, 9-cis-RA, all-trans-RA (ligand of retinoic acid receptor, RAR), and LGD1069 (a selective ligand of RXR). The 72h LC50 of TPT was 5.25 μg Sn/L, and 72h EC50 was 0.96 μg Sn/L. TPT induced multiple malformations including enlarged proctodaeum and narrow fins. TPT at 5 μg Sn/L inhibited the differentiation of skins and muscles. The reduced brain, loss of external eyes and bent axis were observed in RXR and RAR ligands treatments. TPT and tributyltin (TBT) inhibited the mRNA expression of RXRα and increased that of TRβ. The phenotypes of malformations induced by TPT were similar to those by TBT and were much different from those by the RXR and RAR ligands. These results indicated that TPT was acute toxic and had high teratogenicity to amphibian embryos, and that TPT induced phenotypes of malformations. TPT and TBT might have a similar teratogenic mechanism, which seems not to be mainly mediated through RA signal. PMID:21820800

  5. Measurement of effect of chemical reactions on the hydrologic properties of fractured glass media using a tri-axial flow and transport apparatus

    Science.gov (United States)

    Saripalli, K. Prasad; Lindberg, Michael J.; Meyer, Philip D.

    2006-09-01

    SummaryUnderstanding the effect of chemical reactions on the hydrologic properties of sub-surface media is critical to many natural and engineered sub-surface systems. Methods and information for such characterization of fractured media are severely lacking. Influence of glass corrosion (precipitation and dissolution) reactions on fractured glass blocks HAN28 and LAWBP1, two candidate waste glass forms for a proposed immobilized low-activity waste (ILAW) disposal facility at the Hanford, WA site, was investigated. Flow and tracer transport experiments were conducted in such randomly and multiply fractured ILAW glass blocks, before and after subjecting them to corrosion using vapor hydration testing (VHT) at 200 °C temperature and 200 psig (1379 KPa) pressure, causing the precipitation of alteration products. A tri-axial fractured media flow and transport experimental apparatus, which allows the simultaneous measurement of flow and transport properties and their anisotropy, has been designed and built for this purpose. Such apparatus for fractured media characterization are being reported in the literature only recently. Hydraulic properties of fractured blocks were measured in different orientations and along different cardinal directions, before and after glass corrosion reactions. Miscible displacement experiments using a non-reactive dye were also conducted, before and after glass corrosion reactions, to study the tracer transport behavior through such media. Initial efforts to analyze breakthrough curve (BTC) data using a 1D advection dispersion equation (ADE) solution revealed that a different fractured media transport model, which accurately accounts for the heterogeneous transport behavior in 3D, may be necessary for such interpretation. It was found that glass reactions could have a significant influence on the hydrologic properties of fractured ILAW glass media. The methods and results are useful to better understand the effect of chemical reactions on

  6. Measurement of Effect of Chemical Reactions on the Hydrologic Properties of Fractured Glass Media Using a Tri-axial Flow and Transport Apparatus

    International Nuclear Information System (INIS)

    Understanding the effect of chemical reactions on the hydrologic properties of sub-surface media is critical to many natural and engineered sub-surface systems. Methods and information for such characterization of fractured media are severely lacking. Influence of glass corrosion (precipitation and dissolution) reactions on fractured glass blocks HAN28 and LAWBP1, two candidate waste glass forms for a proposed immobilized low-activity waste (ILAW) disposal facility at the Hanford, WA site, was investigated. Flow and tracer transport experiments were conducted in such randomly and multiply fractured ILAW glass blocks, before and after subjecting them to corrosion using Vapor Hydration Testing (VHT) at 200 C temperature and 200 psig (1379 KPa) pressure, causing the precipitation of alteration products. A tri-axial fractured media flow and transport experimental apparatus, which allows the simultaneous measurement of flow and transport properties and their anisotropy, has been designed and built for this purpose. Such apparatus for fractured media characterization are being reported in the literature only recently. Hydraulic properties of fractured blocks were measured in different orientations and along different cardinal directions, before and after glass corrosion reactions. Miscible displacement experiments using a non-reactive dye were also conducted, before and after glass corrosion reactions, to study the tracer transport behavior through such media. Initial efforts to analyze breakthrough curve (BTC) data using a 1D Advection Dispersion Equation (ADE) solution revealed that a different fractured media transport model may be necessary for such interpretation. It was found that glass reactions can have a significant influence on the hydrologic properties of fractured ILAW glass media. The methods and results are unique and useful to better understand the effect of chemical reactions on the hydrologic properties of fractured geomedia in general and glass media in

  7. Extra-axial brain tumors.

    Science.gov (United States)

    Rapalino, Otto; Smirniotopoulos, James G

    2016-01-01

    Extra-axial brain tumors are the most common adult intracranial neoplasms and encompass a broad spectrum of pathologic subtypes. Meningiomas are the most common extra-axial brain tumor (approximately one-third of all intracranial neoplasms) and typically present as slowly growing dural-based masses. Benign meningiomas are very common, and may occasionally be difficult to differentiate from more aggressive subtypes (i.e., atypical or malignant varieties) or other dural-based masses with more aggressive biologic behavior (e.g., hemangiopericytoma or dural-based metastases). Many neoplasms that typically affect the brain parenchyma (intra-axial), such as gliomas, may also present with primary or secondary extra-axial involvement. This chapter provides a general and concise overview of the common types of extra-axial tumors and their typical imaging features. PMID:27432671

  8. Effect of ligand self-assembly on nanostructure and carrier transport behaviour in CdSe quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kuiying, E-mail: kuiyingli@ysu.edu.cn; Xue, Zhenjie

    2014-11-14

    Adjustment of the nanostructure and carrier behaviour of CdSe quantum dots (QDs) by varying the ligands used during QD synthesis enables the design of specific quantum devices via a self-assembly process of the QD core–shell structure without additional technologies. Surface photovoltaic (SPV) technology supplemented by X-ray diffractometry and infrared absorption spectroscopy were used to probe the characteristics of these QDs. Our study reveals that while CdSe QDs synthesized in the presence of and capped by thioglycolic acid, 3-mercaptopropionic acid, mercaptoethanol or α-thioglycerol ligands display zinc blende nanocrystalline structures, CdSe QDs modified by L-cysteine possess wurtzite nanocrystalline structures, because different end groups in these ligands induce distinctive nucleation and growth mechanisms. Carboxyl end groups in the ligand served to increase the SPV response of the QDs, when illuminated by hν ≥ E{sub g,nano-CdSe}. Increased length of the alkyl chains and side-chain radicals in the ligands partially inhibit photo-generated free charge carrier (FCC) transfer transitions of CdSe QDs illuminated by photon energy of 4.13 to 2.14 eV. The terminal hydroxyl group might better accommodate energy released in the non-radiative de-excitation process of photo-generated FCCs in the ligand's lowest unoccupied molecular orbital in the 300–580 nm wavelength region, when compared with other ligand end groups. - Highlights: • CdSe QDs modified by L-cysteine possess wurtzite nanocrystalline structures. • Carboxyl end groups in the ligand serve to increase the SPV response of CdSe QDs. • Terminal hydroxyl group in the ligand might accommodate non-radiative de-excitation process in CdSe QDs. • Increased length of the alkyl chains and side-chain radicals in the ligands partially inhibit carriers transport of CdSe QDs.

  9. Effect of ligand self-assembly on nanostructure and carrier transport behaviour in CdSe quantum dots

    International Nuclear Information System (INIS)

    Adjustment of the nanostructure and carrier behaviour of CdSe quantum dots (QDs) by varying the ligands used during QD synthesis enables the design of specific quantum devices via a self-assembly process of the QD core–shell structure without additional technologies. Surface photovoltaic (SPV) technology supplemented by X-ray diffractometry and infrared absorption spectroscopy were used to probe the characteristics of these QDs. Our study reveals that while CdSe QDs synthesized in the presence of and capped by thioglycolic acid, 3-mercaptopropionic acid, mercaptoethanol or α-thioglycerol ligands display zinc blende nanocrystalline structures, CdSe QDs modified by L-cysteine possess wurtzite nanocrystalline structures, because different end groups in these ligands induce distinctive nucleation and growth mechanisms. Carboxyl end groups in the ligand served to increase the SPV response of the QDs, when illuminated by hν ≥ Eg,nano-CdSe. Increased length of the alkyl chains and side-chain radicals in the ligands partially inhibit photo-generated free charge carrier (FCC) transfer transitions of CdSe QDs illuminated by photon energy of 4.13 to 2.14 eV. The terminal hydroxyl group might better accommodate energy released in the non-radiative de-excitation process of photo-generated FCCs in the ligand's lowest unoccupied molecular orbital in the 300–580 nm wavelength region, when compared with other ligand end groups. - Highlights: • CdSe QDs modified by L-cysteine possess wurtzite nanocrystalline structures. • Carboxyl end groups in the ligand serve to increase the SPV response of CdSe QDs. • Terminal hydroxyl group in the ligand might accommodate non-radiative de-excitation process in CdSe QDs. • Increased length of the alkyl chains and side-chain radicals in the ligands partially inhibit carriers transport of CdSe QDs

  10. Build Axial Gradient Field by Using Axial Magnetized Permanent Rings

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Axial magnetic field produced by an axial magnetized permanent ring was studied. For two permanent rings, if they are magnetized in the same directions, a nearly uniform axial field can be produced. If they are magnetized in opposite direction,an axial gradient magnetic field can be generated, with the field range changing from -B0 to B0. A permanent magnet with a high axial gradient field was fabricated, the measured results agree with the PANDIRA calculation very well. For wider usage,it is desirable for the field gradient to be changed. Some methods to produce the variable gradient field are presented. These kinds of axial gradient magnetic field can also be used as a beam focusing for linear accelerator if the periodic field can be produced along the beam trajectory. The axial magnetic field is something like a solenoid, large stray field will leak to the outside environment if no method is taken to control them. In this paper, one method is illustrated to shield off the outside leakage field.

  11. Axial Patterning in Hydra

    Science.gov (United States)

    Bode, Hans R.

    2009-01-01

    Morphogen gradients play an important role in pattern formation during early stages of embryonic development in many bilaterians. In an adult hydra, axial patterning processes are constantly active because of the tissue dynamics in the adult. These processes include an organizer region in the head, which continuously produces and transmits two signals that are distributed in gradients down the body column. One signal sets up and maintains the head activation gradient, which is a morphogenetic gradient. This gradient confers the capacity of head formation on tissue of the body column, which takes place during bud formation, hydra's mode of asexual reproduction, as well as during head regeneration following bisection of the animal anywhere along the body column. The other signal sets up the head inhibition gradient, which prevents head formation, thereby restricting bud formation to the lower part of the body column in an adult hydra. Little is known about the molecular basis of the two gradients. In contrast, the canonical Wnt pathway plays a central role in setting up and maintaining the head organizer. PMID:20066073

  12. Axial asymmetry in the IVBM

    International Nuclear Information System (INIS)

    The dynamical symmetry limit of the two-fluid Interacting Vector Boson Model (IVBM), defined through the chain Sp(12,R) contains U(3,3) contains Up(3) x Un(3) contains SU*(3) contains SO(3), is considered and applied for the description of nuclear collective spectra exhibiting axially asymmetric features. The effect of the introduction of a Majorana interaction to the SU*(3) model Hamiltonian on the γ-band energies is studied. The theoretical predictions are compared with the experimental data for 192Os, 190Os, and 112Ru isotopes. It is shown that by taking into account the full symplectic structures in the considered dynamical symmetry of the IVBM, the proper description of the energy spectra and the γ-band energy staggering of the nuclei under considerations can be achieved. The obtained results show that the potential energy surfaces for the following two nuclei 192Os and 112Ru, possess almost γ-flat potentials with very shallow triaxial minima, suggesting a more complex and intermediate situation between γ-rigid and γ-unstable structures. Additionally, the absolute B(E2) intraband transition probabilities between the states of the ground-state band and γ band, as well as the B(M1) interband transition probabilities between the states of the ground and γ bands for the two nuclei 192Os and 190Os are calculated and compared with experiment and for the B(E2) values with the predictions of some other collective models incorporating the γ-rigid or γ-unstable structures. The obtained results agree well with the experimental data and reveal the relevance of the used dynamical symmetry of IVBM in the description of nuclei exhibiting axially asymmetric features in their spectra. (orig.)

  13. The effects of axial preload and dorsiflexion on the tolerance of the ankle/subtalar joint to dynamic inversion and eversion.

    Science.gov (United States)

    Funk, James R; Srinivasan, Sreebala C M; Crandall, Jeff R; Khaewpong, Nopporn; Eppinger, Rolf H; Jaffredo, Anna S; Potier, Pascal; Petit, Philippe Y

    2002-11-01

    Forced inversion or eversion of the foot is considered a common mechanism of ankle injury in vehicle crashes. The objective of this study was to model empirically the injury tolerance of the human ankle/subtalar joint to dynamic inversion and eversion under three different loading conditions: neutral flexion with no axial preload, neutral flexion with 2 kN axial preload, and 30 degrees of dorsiflexion with 2 kN axial preload. 44 tests were conducted on cadaveric lower limbs, with injury occurring in 30 specimens. Common injuries included malleolar fractures, osteochondral fractures of the talus, fractures of the lateral process of the talus, and collateral ligament tears, depending on the loading configuration. The time of injury was determined either by the peak ankle moment or by a sudden drop in ankle moment that was accompanied by a burst of acoustic emission. Characteristic moment-angle curves to injury were generated for each loading configuration. Neutrally flexed ankles with no applied axial preload sustained injury at 21 +/- 5 Nm and 38 degrees +/- 8 degrees in inversion, and 47 +/- 21 Nm and 28 degrees +/- 4 degrees in eversion. For ankles tested in neutral flexion with 2 kN of axial preload, inversion failure occurred at 77 +/- 27 Nm and 40 degrees +/- 12 degrees , and eversion failure occurred at 142 +/- 100 Nm and 41 degrees +/- 14 degrees . Ankles dorsiflexed 30 degrees and axially preloaded to 2 kN sustained inversion injury at 62 +/- 31 Nm and 33 degrees +/- 4 degrees , and eversion injury at 140 +/- 53 Nm and 40 degrees +/- 6 degrees . Survival analyses were performed to generate injury risk curves in terms of joint moment and rotation angle. PMID:17096228

  14. EFFECTS OF CONFORMATION OF POLYMER LIGANDS IN COPPER(Ⅱ) COMPLEXES ON CATALYLIC ACTIVITIES AND MECHANISM OF OXIDATIVE COUPLING OF β-NAPHTHOL

    Institute of Scientific and Technical Information of China (English)

    BIAN Kejian; LUO Chunqiao; CAO Mengjun

    1987-01-01

    Copper(Ⅱ) complexes of sericin, chitosan, 6-and 2-aminodeoxystarch were used as catalysts in oxidative coupling of β-naphthol, the effects of conformation of the polymer ligands in these complexes on activities of the catalysts and mechanisms of the reaction were studied. It was found that if the catalysts react with the substrate by mechanism similar to the enzymic catalysis they must be composed of polymer ligands with highly coiled, especially with densely helicoidal,conformations. While catalysts composed of loosely coiled or helicoidal ligands react with the substrate through molecular collision and have relatively lower activities only. Under nitrogen,catalysts from sericin and chitosam reacting with β-naphthol give optically active β-binaphthol,rotating polarized light to right, but the stereoselectivities are rather low.

  15. What Is the True Color of Fresh Meat? A Biophysical Undergraduate Laboratory Experiment Investigating the Effects of Ligand Binding on Myoglobin Using Optical, EPR, and NMR Spectroscopy

    Science.gov (United States)

    Linenberger, Kimberly; Bretz, Stacey Lowery; Crowder, Michael W.; McCarrick, Robert; Lorigan, Gary A.; Tierney, David L.

    2011-01-01

    With an increased focus on integrated upper-level laboratories, we present an experiment integrating concepts from inorganic, biological, and physical chemistry content areas. Students investigate the effects of ligand strength on the spectroscopic properties of the heme center in myoglobin using UV-vis, [superscript 1]H NMR, and EPR…

  16. Skeletal changes in osteoprotegerin and receptor activator of nuclear factor-kappab ligand mRNA levels in primary hyperparathyroidism: effect of parathyroidectomy and association with bone metabolism

    DEFF Research Database (Denmark)

    Stilgren, L S; Rettmer, E; Eriksen, E F;

    2004-01-01

    The effect of parathyroid hormone (PTH) on the production of osteoprotegerin (OPG) and ligand of receptor activator of NF-kappaB (RANKL) in human bone is incompletely understood. Most in vitro studies indicate that PTH decreases OPG and increases RANKL production. In primary hyperparathyroidism (...

  17. Effects on normal tissues during radiosensitization of Dalton's Lymphoma by the DNA ligand Hoechst 33342 in Balb/c mice

    International Nuclear Information System (INIS)

    Hoechst 33342 is a bisbenzimidazole derivative with AT specific minor groove DNA binding ability. Scavenging of free radicals and stabilization of macromolecular structure resulting in reduced induction of DNA damage contributes to radioprotection afforded by the ligand. Their ability to inhibit topoisomerases I and II, which play important roles in damage response pathways including DNA repair has been shown to sensitize tumor cells in vitro and in vivo. Due to its mutagenic and clastogenic potentials, damage to vital normal tissues are a matter of concern in deploying the ligand as adjuvant in radiotherapy. Therefore, we investigated the effects of the ligand in Dalton's Lymphoma (DL) bearing Balb/c mice by studying the local tumor control and animal survival, besides damage to normal tissues like bone marrow, kidney and testis. Hoechst 33342 (10 mg/kg b wt) was administered (i.v.) 1 h before focal irradiation (10 Gy) of the tumor (∼ 500 mm3) grown on the hind leg of the mice. Partial response with a growth delay of 16 days (3 x initial volume) was seen following irradiation, while a complete response (cure; tumor-free survival) was observed in 88% mice following the combined treatment (Hoechst 33342+radiation); ligand alone had no significant effect. Although the ligand induced marginal degree of chromosomal aberrations in the bone marrow, it did not enhance aberrations induced by radiation further. In testes, the proportions of diploid, haploid and hypo-haploid cells as well as resting primary spermatocytes (RPS) were not significantly altered by either. In kidney, Hoechst 33342 alone or in combination with radiation did not cause significant damage to the proximal tubules and glomeruli. These observations suggest that radiosensitization of tumor by the DNA ligand Hoechst 33342 may not be associated with enhanced toxicity to bone marrow as well as proximal normal tissues. (author)

  18. Calculation Simulation of Mass Transfer Coefficient and Axial Effective Diffusivity of Uranium in The Separation of Uranium From Fission Products by Ion Exchange Method

    International Nuclear Information System (INIS)

    A mass transfer coefficient (kla) and an axial effective diffusivity (De) of U in the separation of U from fission products using ion exchange method have been calculated. In this separation process, mass transfer of uranium occurs in the liquid and solid phases. Mathematical model calculation is started by setting up mass balances on an element volume in the ion exchange column which can be assumed to have a similarity to the above process. The set up differential equations (in the form of simultaneous differential equations) are then solved using numerical analysis method. It is started by predicting the (kla) value to obtain the uranium concentrations as a function of distance and time, CA1(x,t) and XA1(x,t). Both the resulted concentrations of uranium and the predicted kla are used to calculate De and concentrations of uranium in the liquid, CA2(x,t) and solid phases, XA2(x,t). The resulted concentrations of uranium are then compared with the concentrations of uranium in the previous calculation. Both the kla and De values can be accepted if the difference between the concentrations resulted from both the calculations are similar or nearly equal, i.e the concentration difference performed by sum of squares of errors (SSE) is minimum (nearly zero). For the superficial linear velocity of about 20-40 cm/minute the results from the calculations are kl a= 15.18588 -20. 48588 per minute and De = 9.14117x10-4 - 1.11612x10-3 cm2/minute. The sum of squares of errors and the average relative error on the condition above are about 2.25117.10-9 - 3.98145x10-9 and 11,541% -25.981%

  19. Non-linear dynamics of a two phase flow system in an evaporator: The effects of (i) a time varying pressure drop (ii) an axially varying heat flux

    Energy Technology Data Exchange (ETDEWEB)

    Narayanan, S.; Srinivas, B.; Pushpavanam, S. [Indian Inst. of Tech., Kanpur (India). Dept. of Chemical Engineering; Murty Bhallamudi, S. [Department of Civil Engineering, Indian Institute of Technology, Kanpur-208016 (India)

    1997-12-01

    In this paper we study the phenomena of density wave oscillations (DWO) in a vertical heated channel. The homogeneous equilibrium model is used to simulate the flow in the two-phase region. The equations are solved numerically using a `shooting-method` technique. This in its turn employs an implicit backward finite difference scheme. The scheme can incorporate the movement of the interface. It is very elegant and does not involve storage of variables in large N x N matrices. This scheme is sufficiently general and can be used to simulate the dynamic behaviour when: (i) the heat flux imposed at the surface is non-constant, i.e. exhibits an axial variation; and (ii) the imposed pressure drop is varied periodically at a fixed frequency. A possible explanation for the conflicting reports of the effect of a periodic variation in heat flux is provided using a linear stability analysis and the D-partition method. The interaction of the natural frequency of the DWO and the fixed forcing frequency of the imposed pressure drop gives rise to various phenomena viz relaxation oscillations, sub-harmonic oscillations, quasi-periodic and chaotic solutions. To aid the experimentalist describe this infinite-dimensional system on the basis of his experimental results we discuss the characterisation using only the velocity time series data. This is done employing the method of delay coordinate embedding. The phase portraits, stroboscopic map and correlation dimension of the actual attractor are compared with that of the reconstructed attractor from the velocity time series. (orig.) 19 refs.

  20. Non-linear dynamics of a two phase flow system in an evaporator: The effects of (i) a time varying pressure drop (ii) an axially varying heat flux

    International Nuclear Information System (INIS)

    In this paper we study the phenomena of density wave oscillations (DWO) in a vertical heated channel. The homogeneous equilibrium model is used to simulate the flow in the two-phase region. The equations are solved numerically using a 'shooting-method' technique. This in its turn employs an implicit backward finite difference scheme. The scheme can incorporate the movement of the interface. It is very elegant and does not involve storage of variables in large N x N matrices. This scheme is sufficiently general and can be used to simulate the dynamic behaviour when: (i) the heat flux imposed at the surface is non-constant, i.e. exhibits an axial variation; and (ii) the imposed pressure drop is varied periodically at a fixed frequency. A possible explanation for the conflicting reports of the effect of a periodic variation in heat flux is provided using a linear stability analysis and the D-partition method. The interaction of the natural frequency of the DWO and the fixed forcing frequency of the imposed pressure drop gives rise to various phenomena viz relaxation oscillations, sub-harmonic oscillations, quasi-periodic and chaotic solutions. To aid the experimentalist describe this infinite-dimensional system on the basis of his experimental results we discuss the characterisation using only the velocity time series data. This is done employing the method of delay coordinate embedding. The phase portraits, stroboscopic map and correlation dimension of the actual attractor are compared with that of the reconstructed attractor from the velocity time series. (orig.)

  1. CR4056, a new analgesic I2 ligand, is highly effective against bortezomib-induced painful neuropathy in rats

    Directory of Open Access Journals (Sweden)

    Meregalli C

    2012-06-01

    Full Text Available Cristina Meregalli,1 Cecilia Ceresa,1 Annalisa Canta,1 Valentina Alda Carozzi,1 Alessia Chiorazzi,1 Barbara Sala,1 Norberto Oggioni,1 Marco Lanza,2 Ornella Letar,i2 Flora Ferrari,2 Federica Avezza,1 Paola Marmiroli,1 GianFranco Caselli,2 Guido Cavaletti11Department of Neuroscience and Biomedical Technologies, University of Milan-Bicocca, 2Pharmacology and Toxicology Department, Rottapharm | Madaus Research Center, Monza, ItalyAbstract: Although bortezomib (BTZ is the frontline treatment for multiple myeloma, its clinical use is limited by the occurrence of painful peripheral neuropathy, whose treatment is still an unmet clinical need. Previous studies have shown chronic BTZ administration (0.20 mg/kg intravenously three times a week for 8 weeks to female Wistar rats induced a peripheral neuropathy similar to that observed in humans. In this animal model of BTZ-induced neurotoxicity, the present authors evaluated the efficacy of CR4056, a novel I2 ligand endowed with a remarkable efficacy in several animal pain models. CR4056 was administered in a wide range of doses (0.6–60 mg/kg by gavage every day for 2–3 weeks in comparison with buprenorphine (Bupre (28.8 µg/kg subcutaneously every day for 2 weeks and gabapentin (Gaba (100 mg/kg by gavage every day for 3 weeks. Chronic administration of BTZ reduced nerve conduction velocity and induced allodynia. CR4056, Bupre, or Gaba did not affect the impaired nerve conduction velocity. Conversely, CR4056 dose-dependently reversed BTZ-induced allodynia (minimum effective dose 0.6 mg/kg. The optimal dose found, 6 mg/kg, provided a constant pain relief throughout the treatment period and without rebound after suspension, being effective when coadministered with BTZ, starting before or after allodynia was established, or when administered alone after BTZ cessation. A certain degree of tolerance was seen after 7 days of administration, but only at the highest doses (20 and 60 mg/kg. Bupre was effective

  2. Effects of PPARγ ligands on TGF-β1-induced epithelial-mesenchymal transition in alveolar epithelial cells

    Directory of Open Access Journals (Sweden)

    Dagher Hayat

    2010-02-01

    Full Text Available Abstract Background Transforming growth factor β1 (TGF-β1-mediated epithelial mesenchymal transition (EMT of alveolar epithelial cells (AEC may contribute to lung fibrosis. Since PPARγ ligands have been shown to inhibit fibroblast activation by TGF-β1, we assessed the ability of the thiazolidinediones rosiglitazone (RGZ and ciglitazone (CGZ to regulate TGF-β1-mediated EMT of A549 cells, assessing changes in cell morphology, and expression of cell adhesion molecules E-cadherin (epithelial cell marker and N-cadherin (mesenchymal cell marker, and collagen 1α1 (COL1A1, CTGF and MMP-2 mRNA. Methods Serum-deprived A549 cells (human AEC cell line were pre-incubated with RGZ and CGZ (1 - 30 μM in the absence or presence of the PPARγ antagonist GW9662 (10 μM before TGFβ-1 (0.075-7.5 ng/ml treatment for up to 72 hrs. Changes in E-cadherin, N-cadherin and phosphorylated Smad2 and Smad3 levels were analysed by Western blot, and changes in mRNA levels including COL1A1 assessed by RT-PCR. Results TGFβ-1 (2.5 ng/ml-induced reductions in E-cadherin expression were associated with a loss of epithelial morphology and cell-cell contact. Concomitant increases in N-cadherin, MMP-2, CTGF and COL1A1 were evident in predominantly elongated fibroblast-like cells. Neither RGZ nor CGZ prevented TGFβ1-induced changes in cell morphology, and PPARγ-dependent inhibitory effects of both ligands on changes in E-cadherin were only evident at submaximal TGF-β1 (0.25 ng/ml. However, both RGZ and CGZ inhibited the marked elevation of N-cadherin and COL1A1 induced by TGF-β1 (2.5 ng/ml, with effects on COL1A1 prevented by GW9662. Phosphorylation of Smad2 and Smad3 by TGF-β1 was not inhibited by RGZ or CGZ. Conclusions RGZ and CGZ inhibited profibrotic changes in TGF-β1-stimulated A549 cells independently of inhibition of Smad phosphorylation. Their inhibitory effects on changes in collagen I and E-cadherin, but not N-cadherin or CTGF, appeared to be PPAR

  3. Coulombic inter-ligand repulsion effects on the Pt(II) coordination chemistry of oligocationic, ammonium-functionalized triarylphosphines

    OpenAIRE

    Snelders, D.J.M.; Siegler, M.A.M.; von Chrzanowski, L.S.; Spek, A.L.; van Koten, G.; Klein Gebbink, R.J.M.

    2011-01-01

    The Pt(II) coordination chemistry of oligocationic ammoniomethyl- and neutral aminomethyl-substituted triarylphosphines (L) is described. Complexes of the type PtX2(L)2 (X = Cl, I) have been isolated and characterized. For the hexa-meta-ammoniomethyl-substituted ligands [1]6+ and [2]6+, two ligands always occupy a trans-configuration with respect to each other in complexes of the type PtX2(L)2, while for the tri-para-ammoniomethyl-substituted ligand [7]3+, the trans/cis ratio is dependent on ...

  4. Final Activity Report: The Effects of Iron Complexing Ligands on the Long Term Ecosystem Response to Iron Enrichment of HNLC waters

    Energy Technology Data Exchange (ETDEWEB)

    Trick, Charles Gordon [Western University

    2013-07-30

    Substantial increases in the concentrations of the stronger of two Fe(III) complexing organic ligand classes measured during the mesoscale Fe enrichment studies IronEx II and SOIREE appeared to sharply curtailed Fe availability to diatoms and thus limited the efficiency of carbon sequestration to the deep. Detailed observations during IronEx II (equatorial Pacific Ocean) and SOIREE (Southern Ocean –Pacific sector) indicate that the diatoms began re-experiencing Fe stress even though dissolved Fe concentrations remained elevated in the patch. This surprising outcome likely is related to the observed increased concentrations of strong Fe(III)-complexing ligands in seawater. Preliminary findings from other studies indicate that diatoms may not readily obtain Fe from these chemical species whereas Fe bound by strong ligands appears to support growth of cyanobacteria and nanoflagellates. The difficulty in assessing the likelihood of these changes with in-situ mesoscale experiments is the extended monitoring period needed to capture the long-term trajectory of the carbon cycle. A more detailed understanding of Fe complexing ligand effects on long-term ecosystem structure and carbon cycling is essential to ascertain not only the effect of Fe enrichment on short-term carbon sequestration in the oceans, but also the potential effect of Fe enrichment in modifying ecosystem structure and trajectory.

  5. Final Technical Report: The Effects of Iron Complexing Ligands on the Long Term Ecosystem Response to Iron Enrichment of HNLC waters

    Energy Technology Data Exchange (ETDEWEB)

    Cochlan, William P.

    2008-06-13

    Substantial increases in the concentrations of the stronger of two Fe(III) complexing organic ligand classes measured during the mesoscale Fe enrichment studies IronEx II and SOIREE appeared to sharply curtailed Fe availability to diatoms and thus limited the efficiency of carbon sequestration to the deep. Detailed observations during IronEx II (equatorial Pacific Ocean) and SOIREE (Southern Ocean –Pacific sector) indicate that the diatoms began re-experiencing Fe stress even though dissolved Fe concentrations remained elevated in the patch. This surprising outcome likely is related to the observed increased concentrations of strong Fe(III)-complexing ligands in seawater. Preliminary findings from other studies indicate that diatoms may not readily obtain Fe from these chemical species whereas Fe bound by strong ligands appears to support growth of cyanobacteria and nanoflagellates. The difficulty in assessing the likelihood of these changes with in-situ mesoscale experiments is the extended monitoring period needed to capture the long-term trajectory of the carbon cycle. A more detailed understanding of Fe complexing ligand effects on long-term ecosystem structure and carbon cycling is essential to ascertain not only the effect of Fe enrichment on short-term carbon sequestration in the oceans, but also the potential effect of Fe enrichment in modifying ecosystem structure and trajectory.

  6. The Effects of 910-MHz Electromagnetic Field on Rat Cranial Arachnoid and Dura Mater Collagen. The Axial Periodicity of Collagen Fibrils

    OpenAIRE

    Margaret Tzaphlidou; Evangelos Fotiou

    2004-01-01

    The axial periodicity of rat arachnoid and dura mater collagen fibrils exposed to 910 MHz for 2 h/day for 30 consecutive days was measured by means of image analysis of electron-optical data. Such measurements were compared with those from sham-exposed animals. These measurements reveal that on exposure, the intermolecular interactions during collagen fibril assembly are affected.

  7. Characterization of Multiflux Axial Compressors

    International Nuclear Information System (INIS)

    In the present work the results of analytical models of performance are compared with experimental data acquired in the multi flux axial compressor test facility, built in The Pilcaniyeu Technological Complex for the SIGMA project.We describe the experimental circuit and the data of the dispersion inside the axial compressor obtained using a tracer gas through one of the annular inlets.The attained results can be used to validate the design code for the multi flux axial compressors and SIGMA industrial plant

  8. Axial gap rotating electrical machine

    Energy Technology Data Exchange (ETDEWEB)

    None

    2016-02-23

    Direct drive rotating electrical machines with axial air gaps are disclosed. In these machines, a rotor ring and stator ring define an axial air gap between them. Sets of gap-maintaining rolling supports bear between the rotor ring and the stator ring at their peripheries to maintain the axial air gap. Also disclosed are wind turbines using these generators, and structures and methods for mounting direct drive rotating electrical generators to the hubs of wind turbines. In particular, the rotor ring of the generator may be carried directly by the hub of a wind turbine to rotate relative to a shaft without being mounted directly to the shaft.

  9. The effect of ligand substituent on crystal packing: Structural and theoretical studies of two Ga(III) supramolecular compounds

    Science.gov (United States)

    Soleimannejad, Janet; Nazarnia, Esfandiar

    2016-07-01

    A new Ga(III) supramolecular compound (4,4‧-bipyH2)[Ga(hpydc)2]2·7H2O (2) (where H2hpydc = 4-hydroxy-pyridine-2,6-dicarboxylic acid and 4,4‧-bipy = 4,4‧-bipyridine) was synthesized using the proton transfer reaction. Compound 2 was structurally characterized using single crystal X-ray diffraction, and it was shown that its asymmetric unit consists of two independent anionic Ga(III) complexes, one fully protonated 4,4‧-bipyridine and seven uncoordinated water molecules. In order to understand the effect of pyridine OH substituent on supramolecular interactions and crystal packing, compound 2 was compared with (bipyH2)[Ga(pydc)2]·(H2pydc)·4H2O (1) (where H2pydc = pyridine-2,6-dicarboxylic acid), that does not have an OH group on the pyridine ligand. The Density Functional Theory (DFT) and Natural Bond Orbital (NBO) calculations and also Atoms in Molecules (AIM) analysis were used to analyze the non-covalent interactions in both complexes. The calculation of non-covalent interactions' energy provides a useful means to investigate their effects in the crystal packing.

  10. Cytotoxic effects of 125I-labeled PBZr ligand PK 11195 in prostatic tumor cells: therapeutic implications

    International Nuclear Information System (INIS)

    The effect of [125I]PK 11195 was examined in human prostatic tumor cells (DU 145) in culture and compared with Na[125I] and non-radioactive PK 11195. [125I]PK 11195 was clearly cytocidal. The data for dose-related cell survival with [125I]PK 11195 showed a linear relationship. Na[125I] or non-labeled PK 11195 at similar concentrations did not lead to any cell killing. The uptake of [125I]PK 11195 and [3H]PK 11195 in cells was very similar. Fragmentation of DNA measured by agarose gel electrophoresis showed that exposure of DU 145 cells to [125I]PK 11195 for 1, 4 or 24 h caused no fragmentation. These results indicate that nuclear DNA is not the prime binding site for [125I]PK 11195, which is consistent with the presence of specific peripheral benzodiazepine receptors (PBZr) in the mitochondria. The cell killing effect of [125I]PK 11195 suggests the use of PBZr ligand for radiotherapy

  11. Para-aminobenzamidine linked regenerated cellulose membranes for plasminogen activator purification: Effect of spacer arm length and ligand density

    Science.gov (United States)

    Fasoli, Ezio; Reyes, Yiaslin Ruiz; Guzman, Osiris Martinez; Rosado, Alexandra; Cruz, Vivian Rodriguez; Borges, Amaris; Martinez, Edmarie; Bansal, Vibha

    2013-01-01

    Despite membrane-based separations offering superior alternative to packed bed chromatographic processes, there has been a substantial lacuna in their actual application to separation processes. One of the major reasons behind this is the lack of availability of appropriately modified or end-group modifiable membranes. In this paper, an affinity membrane was developed using a commercially available serine protease inhibitor, para-aminobenzamidine (pABA). The membrane modification was optimized for protein binding capacity by varying: i) the length of the spacer arm (SA; 5-atoms, 7-atoms, and 14-atoms) linking the ligand to membrane surface; ii) the affinity ligand (pABA) density on membrane surface (5–25 nmoles per cm2). Resulting membranes were tested for their ability to bind plasminogen activators (PAs) from mono- and multi- component systems in batch mode. The membrane containing pABA linked through 7-atoms SA but similar ligand density as in the case of 5- or 14- atoms long SA was found to bind up to 1.6-times higher amounts of PA per nmole of immobilized ligand from conditioned HeLa cell culture media. However, membranes with similar ligand densities but different lengths of SA, showed comparable binding capacities in monocomponent system. In addition, the length of SA did not affect the selectivity of the ligand for PA. A clear inverse linear correlation was observed between ligand density and binding capacity until the point of PA binding optima was reached (11±1.0 nmoles per cm2) in mono- and multi- component systems for 7- as well as 14- atoms SA. Up to 200-fold purification was achieved in a single step separation of PA from HeLa conditioned media using these affinity membranes. The issues of ligand leaching and reuse of the membranes were also investigated. An extensive regeneration procedure allowed the preservation of approximately 95% of the PA binding capacity of the membranes even after five cycles of use. PMID:23703544

  12. Selective effects of ligands on vitamin D3 receptor- and retinoid X receptor-mediated gene activation in vivo.

    OpenAIRE

    Lemon, B D; Freedman, L P

    1996-01-01

    Steroid/nuclear hormone receptors are ligand-regulated transcription f factors that play key roles in cell regulation, differentiation, and oncogenesis. Many nuclear receptors, including the human 1,25-dihydroxyvitamin D3 receptor (VDR), bind cooperatively to DNA either as homodimers or as heterodimers with the 9-cis retinoic acid (RA) receptor (retinoid X-receptor [RXR]). We have previously reported that the ligands for VDR and RXR can differentially modulate the affinity of the receptors' i...

  13. Controlling Surface Ligand Density and Core Size of Alkanethiolate-Capped Pd Nanoparticles and Their Effects on Catalysis

    Science.gov (United States)

    Gavia, Diego J.; Shon, Young-Seok

    2016-01-01

    This article presents systematic investigations on the relationship between the catalytic property and the surface ligand density/core size of thiolate ligand-capped Pd nanoparticles (PdNPs). The systematic variations in the two-phase synthesis of PdNPs generated from sodium S-dodecylthiosulfate were performed. The resulting PdNPs were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and 1H NMR and UV–vis spectroscopy. The decrease in the molar equivalent of sodium S-dodecylthiosulfate (Bunte salts) resulted in the formation of nanoparticles with lower surface ligand density and larger particle core size. A decrease in the molar equivalent of tetra-n-octylammonium bromide or an increase in reaction temperature generated nanoparticles with higher surface ligand density and smaller particle core size. As the molar equivalent of NaBH4 decreased, the particle core size increased. The catalysis studies on various PdNPs with different surface ligand density and average core size showed a strong correlation between the PdNP composition and the turnover frequency (TOF) of the isomerization of allyl alcohol. Optimized “good” PdNPs with lower surface ligand coverage and larger core size catalyzed the isomerization of various allyl alcohols to carbonyl analogues with high activity and selectivity. PMID:22924990

  14. A new strategy of axial power distribution control based on three axial offsets concept

    International Nuclear Information System (INIS)

    We have proposed a very simple control procedure for axial xenon oscillation control based on a characteristic trajectory. The trajectory is drawn by three offsets of power distributions, namely, AOp, AOi and AOx. They are defined as the offset of axial power distribution, the offset of the power distribution under which the current iodine distribution is obtained as the equilibrium and that for xenon distribution, respectively. When these offsets are plotted on X-Y plane for (AOp-AOx, AOi-AOx) the trajectory draws a quite characteristic ellipse (or an elliptic spiral). On the other hands, Constant Axial Offset Control (CAOC) procedure is adopted as axial power distribution control strategy during both base load and load following operations in domestic PWRs. In the previous paper, we have presented an innovative procedure of axial power distribution control during load following in PWRs based on this trajectory such that the AOp-AOx is to be controlled to zero when the value deviates the pre-determined limiting values. In this paper we propose a modified control strategy to get more stability of axial power distributions. In this strategy, we control the trajectory to be close to the major axis of the ellipse when the power distribution reaches the limiting values. In other words, the plot is not controlled only to reduce AOp-AOx but also AOi-AOx is taken into account at the same time. It is known that when the plot is controlled to the major axis, it means that the point gives the peak position of axial xenon oscillation. Therefore xenon oscillation will not increase its amplitude any more. Thus more stable axial power distribution control is attained. This kind of design concept is quite important especially for the future PWRs with elongated fuel length and longer core life. Because in a longer effective core and also the longer core life, it has been known that the stability of axial xenon oscillation becomes more unstable. In this paper, some simulation

  15. Effect of cisplatin alone or combined with monoclonal anti-programmed death ligand-1 anti-body on lung adenocarcinoma cell line SPCA-1 and T lymphocytes

    Institute of Scientific and Technical Information of China (English)

    潘雪

    2014-01-01

    Objective To observe the effect of cisplatin alone or combined with anti-programmed death ligand 1 monoclonal antibody(anti-PD-L1 mA b)on the co-culture system of lung adenocarcinoma SPCA-1 cells and T lymphocytes,and therefore to study the immunotherapeutic effect of anti-PD-L1 mA b on lung cancer.Methods Human adenocarcinoma SPCA-1 cell line was selected by

  16. Nudging oligodendrocyte intrinsic signaling to remyelinate and repair: Estrogen receptor ligand effects.

    Science.gov (United States)

    Khalaj, Anna J; Hasselmann, Jonathan; Augello, Catherine; Moore, Spencer; Tiwari-Woodruff, Seema K

    2016-06-01

    Demyelination in multiple sclerosis (MS) leads to significant, progressive axonal and neuronal degeneration. Currently existing immunosuppressive and immunomodulatory therapies alleviate MS symptoms and slow, but fail to prevent or reverse, disease progression. Restoration of damaged myelin sheath by replenishment of mature oligodendrocytes (OLs) should not only restore saltatory axon conduction, but also provide a major boost to axon survival. Our previous work has shown that therapeutic treatment with the modestly selective generic estrogen receptor (ER) β agonist diarylpropionitrile (DPN) confers functional neuroprotection in a chronic experimental autoimmune encephalomyelitis (EAE) mouse model of MS by stimulating endogenous remyelination. Recently, we found that the more potent, selective ERβ agonist indazole-chloride (Ind-Cl) improves clinical disease and motor performance. Importantly, electrophysiological measures revealed improved corpus callosal conduction and reduced axon refractoriness. This Ind-Cl treatment-induced functional remyelination was attributable to increased OL progenitor cell (OPC) and mature OL numbers. At the intracellular signaling level, transition of early to late OPCs requires ERK1/2 signaling, and transition of immature to mature OLs requires mTOR signaling; thus, the PI3K/Akt/mTOR pathway plays a major role in the late stages of OL differentiation and myelination. Indeed, therapeutic treatment of EAE mice with various ERβ agonists results in increased brain-derived neurotrophic factor (BDNF) and phosphorylated (p) Akt and p-mTOR levels. It is notable that while DPN's neuroprotective effects occur in the presence of peripheral and central inflammation, Ind-Cl is directly neuroprotective, as demonstrated by remyelination effects in the cuprizone-induced demyelination model, as well as immunomodulatory. Elucidating the mechanisms by which ER agonists and other directly remyelinating agents modulate endogenous OPC and OL regulatory

  17. Contrasting effects of different cannabinoid receptor ligands on mouse ingestive behaviour.

    Science.gov (United States)

    Grey, Jonathan; Terry, Phil; Higgs, Suzanne

    2012-09-01

    This study characterized the effects of seven diverse cannabinoid receptor agonists (and one antagonist) on ingestive behaviour in nondeprived adult, male CD1 mice. Microstructural analysis of licking for a range of concentrations of condensed milk (10, 15 and 20%) was carried out following administration of vehicle or: Δ⁹-tetrahydrocannabinol (Δ⁹-THC) at 1, 3 or 6 mg/kg; CP55,940 at 10, 30 or 50 µg/kg; Win 55,212-2 at 0.5, 1 or 3 mg/kg; HU-210 at 0.01, 0.03 or 0.1 mg/kg; methanandamide at 1, 3 or 6 mg/kg; arachidonyl-2'-chloroethylamide at 1, 3 or 6 mg/kg and JWH133 at 1, 3 or 6 mg/kg. The cannabinoid receptor antagonist/inverse agonist rimonabant was also tested at 0.3, 1 or 3 mg/kg. Test sessions comprised three 30 s presentations of the milk concentrations separated by 10 s interpresentation intervals. The nonselective CB1 receptor agonists Δ⁹-THC, CP55,940 and Win 55,212-2 increased the number of licks for condensed milk, primarily by a significant increase in bout number. The potent and nonselective CB1 receptor agonist HU-210 and the selective CB1 receptor agonists methanandamide and arachidonyl-2'-chloroethylamide did not significantly affect licking behaviour but did significantly increase the latency to start licking. The CB1 receptor antagonist rimonabant produced effects that were opposite in direction to those produced by Δ⁹-THC, CP55,940 and Win 55,212-2. Finally, the selective CB2 receptor agonist JWH133 had no significant effects on behaviour. These data add to reports that cannabinoid agonists can enhance the appetitive aspects of feeding, but they also demonstrate that not all CB1 receptor agonists do this, and therefore the relationship between action at CB1 receptors and appetitive feeding effects is not straightforward. PMID:22772336

  18. Geometric and ligand effects in the infrared spectra of adsorbed carbon monoxide

    International Nuclear Information System (INIS)

    Coadsorption of ethylene or oxygen with carbon monoxide has been investigated using ir transmission spectroscopy. Information on the extent of electronic and geometric (dilution) effects on the ir stretching frequency of CO has been obtained by the isotopic dilution method. The increase of this frequency (blue shift) caused by oxygen can be explained mainly by a compression of the CO layer. The decrease of the frequency (red shift) caused by ethylene can be explained for more than 60% by a dilution of the C layer. 4 figures

  19. Uptake of cadmium by hydroponically grown, mature Eucalyptus camaldulensis saplings and the effect of organic ligands.

    Science.gov (United States)

    Fine, P; Rathod, Paresh H; Beriozkin, A; Mingelgrin, U

    2013-01-01

    The potential suitability of Eucalyptus camaldulensis for Cd phytoextraction was tested in a hydroponic study. Saplings were exposed to 4.5 and 89 microM Cd for one month, with and without EDTA and s,s-EDDS at 0.1, 1, and 5 mM. The saplings' growth was not affected at the 4.5 microM Cd concentration, yet it decreased 3-fold at 89 microM, and almost all the Cd taken up was immobilized in the roots, reaching 360 and 5300 mg Cd kg(-1), respectively (approximately 75% of which was non-washable in acid). The respective Cd root-to-shoot translocation factors were 0.14 and approximately 5*10(-4). At 0.1 mM concentration, EDTA and EDDS had no effect or even a positive effect on the saplings growth. This was reversed at 1 mM, and the chelants became lethal at the 5 mM concentration. At 89 microM Cd in the growth medium, 0.1 mM EDTA increased Cd translocation into the shoots by almost 10-fold, however it strongly reduced Cd content inside the roots. This hydroponic study indicates the feasibility of E. camaldulensis use for cleanup Cd-contaminated soils at environmental concentrations, both for site stabilization (phytostabilization) and gradual remediation (phytoextraction). EDTA was shown to be much more efficient in enhancing Cd translocation than s,s-EDDS. PMID:23819299

  20. Multifaceted effects of synthetic TLR2 ligand and Legionella pneumophilia on Treg-mediated suppression of T cell activation

    Directory of Open Access Journals (Sweden)

    Sutmuller Roger PM

    2011-03-01

    Full Text Available Abstract Background Regulatory T cells (Treg play a crucial role in maintaining immune homeostasis and self-tolerance. The immune suppressive effects of Tregs should however be limited in case effective immunity is required against pathogens or cancer cells. We previously found that the Toll-like receptor 2 (TLR2 agonist, Pam3CysSK4, directly stimulated Tregs to expand and temporarily abrogate their suppressive capabilities. In this study, we evaluate the effect of Pam3CysSK4 and Legionella pneumophila, a natural TLR2 containing infectious agent, on effector T (Teff cells and dendritic cells (DCs individually and in co-cultures with Tregs. Results TLR2 agonists can directly provide a co-stimulatory signal inducing enhanced proliferation and cytokine production of naive CD4+ Teff cells. With respect to cytokine production, DCs appear to be most sensitive to low amounts of TLR agonists. Using wild type and TLR2-deficient cells in Treg suppression assays, we accordingly show that all cells (e.g. Treg, Teff cells and DCs contributed to overcome Treg-mediated suppression of Teff cell proliferation. Furthermore, while TLR2-stimulated Tregs readily lost their ability to suppress Teff cell proliferation, cytokine production by Teff cells was still suppressed. Similar results were obtained upon stimulation with TLR2 ligand containing bacteria, Legionella pneumophila. Conclusions These findings indicate that both synthetic and natural TLR2 agonists affect DCs, Teff cells and Treg directly, resulting in multi-modal modulation of Treg-mediated suppression of Teff cells. Moreover, Treg-mediated suppression of Teff cell proliferation is functionally distinct from suppression of cytokine secretion.

  1. Effect of biquadratic exchange on the axial Heisenberg model: Application to the magnetic phase transitions in UNi sub 2 Si sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Mailhot, A.; Plumer, M.L.; Caille, A. (Centre de Recherche en Physique du Solide et Departement de Physique, Universite de Sherbrooke, Sherbrooke, Quebec, J1K 2R1 (Canada)); Azaria, P. (Laboratoire de Physique Theorique des Liquides, Universite Pierre et Marie Curie, 4 place Jussieu, 75252 Paris CEDEX 05 (France))

    1992-05-01

    The influence of biquadratic exchange on the Heisenberg model with strong axial anisotropy is examined for the case of spins on a body-centered tetragonal lattice with competing bilinear exchange interactions along the {ital c} axis. Contrary to the usual axial next-nearest-neighbor Ising model with third-neighbor exchange also included, a low-temperature spin-wave calculation reveals that biquadratic exchange can stabilize the sequence of phases period 3{r arrow}period 2. Mean-field analysis, with support from Monte Carlo simulations, suggests a higher-temperature transition to an incommensurate state. This sequence of phase transitions has recently been observed in UNi{sub 2}Si{sub 2}. The importance of fluctuations is emphasized.

  2. Biotic ligand modeling approach: Synthesis of the effect of major cations on the toxicity of metals to soil and aquatic organisms.

    Science.gov (United States)

    Ardestani, Masoud M; van Straalen, Nico M; van Gestel, Cornelis A M

    2015-10-01

    The biotic ligand model (BLM) approach is used to assess metal toxicity, taking into account the competition of other cations with the free metal ions for binding to the biotic ligand sites of aquatic and soil organisms. The bioavailable fraction of metals, represented by the free metal ion, is a better measure than the total concentration for assessing their potential risk to the environment. Because BLMs are relating toxicity to the fraction of biotic ligands occupied by the metal, they can be useful for investigating factors affecting metal bioaccumulation and toxicity. In the present review, the effects of major cations on the toxicity of metals to soil and aquatic organisms were comprehensively studied by performing a meta-analysis of BLM literature data. Interactions at the binding sites were shown to be species- and metal-specific. The main factors affecting the relationships between toxicity and conditional binding constants for metal binding at the biotic ligand appeared to be Ca(2+) , Mg(2+) , and protons. Other important characteristics of the exposure medium, such as levels of dissolved organic carbon and concentrations of other cations, should also be considered to obtain a proper assessment of metal toxicity to soil and aquatic organisms. PMID:25953362

  3. Evaluation of an intranasal virosomal vaccine against respiratory syncytial virus in mice: effect of TLR2 and NOD2 ligands on induction of systemic and mucosal immune responses.

    Directory of Open Access Journals (Sweden)

    Muhammad Shafique

    Full Text Available INTRODUCTION: RSV infection remains a serious threat to newborns and the elderly. Currently, there is no vaccine available to prevent RSV infection. A mucosal RSV vaccine would be attractive as it could induce mucosal as well as systemic antibodies, capable of protecting both the upper and lower respiratory tract. Previously, we reported on a virosomal RSV vaccine for intramuscular injection with intrinsic adjuvant properties mediated by an incorporated lipophilic Toll-like receptor 2 (TLR2 ligand. However, it has not been investigated whether this virosomal RSV vaccine candidate would be suitable for use in mucosal immunization strategies and if additional incorporation of other innate receptor ligands, like NOD2-ligand, could further enhance the immunogenicity and protective efficacy of the vaccine. OBJECTIVE: To explore if intranasal (IN immunization with a virosomal RSV vaccine, supplemented with TLR2 and/or NOD2-ligands, is an effective strategy to induce RSV-specific immunity. METHODS: We produced RSV-virosomes carrying TLR2 (Pam3CSK4 and/or NOD2 (L18-MDP ligands. We tested the immunopotentiating properties of these virosomes in vitro, using TLR2- and/or NOD2-ligand-responsive murine and human cell lines, and in vivo by assessing induction of protective antibody and cellular responses upon IN immunization of BALB/c mice. RESULTS: Incorporation of Pam3CSK4 and/or L18-MDP potentiates the capacity of virosomes to activate (antigen-presenting cells in vitro, as demonstrated by NF-κB induction. In vivo, incorporation of Pam3CSK4 in virosomes boosted serum IgG antibody responses and mucosal antibody responses after IN immunization. While L18-MDP alone was ineffective, incorporation of L18-MDP in Pam3CSK4-carrying virosomes further boosted mucosal antibody responses. Finally, IN immunization with adjuvanted virosomes, particularly Pam3CSK4/L18-MDP-adjuvanted-virosomes, protected mice against infection with RSV, without priming for enhanced

  4. Imidazoline receptors ligands

    Directory of Open Access Journals (Sweden)

    Agbaba Danica

    2012-01-01

    Full Text Available Extensive biochemical and pharmacological studies have determined three different subtypes of imidazoline receptors: I1-imidazoline receptors (I1-IR involved in central inhibition of sympathicus that produce hypotensive effect; I2-imidazoline receptors (I2-IR modulate monoamine oxidase B activity (MAO-B; I3-imidazoline receptors (I3-IR regulate insulin secretion from pancreatic β-cells. Therefore, the I1/I2/I3 imidazoline receptors are selected as new, interesting targets for drug design and discovery. Novel selective I1/I2/I3 agonists and antagonists have been recently developed. In the present review, we provide a brief update to the field of imidazoline research, highlighting some of the chemical diversity and progress made in the 2D-QSAR, 3D-QSAR and quantitative pharmacophore development studies of I1-IR and I2-IR imidazoline receptor ligands. Theoretical studies of I3-IR ligands are not yet performed because of insufficient number of synthesized I3-IR ligands.

  5. Microwave axial dielectric properties of carbon fiber

    Science.gov (United States)

    Hong, Wen; Xiao, Peng; Luo, Heng; Li, Zhuan

    2015-10-01

    Randomly distributed carbon fibers (CFs) reinforced epoxy resin composites are prepared by the pouring method, the dielectric properties of CF composites with different fiber content and length have been performed in the frequency range from 8.2 to 12.4 GHz. The complex permittivity of the composite increases with the fiber length, which is attributed to the decrease of depolarization field, and increases with the volume fraction, which is attributed to the increase of polarization. A formula, based on the theory of Reynolds-Hugh, is proposed to calculate the effective permittivity of CF composites, and validated by the experiments. The proposed formula is further applied to derive the axial permittivity of CF and analyze the effect of fiber length on the axial permittivity.

  6. The anomalous transport of axial charge: topological vs non-topological fluctuations

    CERN Document Server

    Iatrakis, Ioannis; Yin, Yi

    2015-01-01

    Axial charge imbalance is an essential ingredient in novel effects associated with chiral anomaly such as chiral magnetic effects (CME). In a non-Abelian plasma with chiral fermions, local axial charge can be generated a) by topological fluctuations which would create domains with non-zero winding number b) by conventional non-topological thermal fluctuations. We provide a holographic evaluations of medium's response to dynamically generated axial charge density in hydrodynamic limit and examine if medium's response depends on the microscopic origins of axial charge imbalance. We show a local domain with non-zero winding number would induce a non-dissipative axial current due to chiral anomaly. We illustrate holographically that a local axial charge imbalance would be damped out with the damping rate related to Chern-Simon diffusive constant. By computing chiral magnetic current in the presence of dynamically generated axial charge density, we found that the ratio of CME current over the axial charge density ...

  7. Anxiolytic effects of dopamine receptor ligands: I. Involvement of dopamine autoreceptors.

    Science.gov (United States)

    Bartoszyk, G D

    1998-01-01

    The anxiolytic-like properties of dopamine agonists and antagonists with different receptor profiles were investigated in the ultrasonic vocalization test in rats after subcutaneous administration. Only dopamine D2 receptor agonists inhibited ultrasonic vocalization with the following ED50 values: apomorphine (0.07 mg/kg), quinelorane (0.01 mg/kg), quinpirole (0.04 mg/kg), pramipexole (0.09 mg/kg), roxindole (0.04 mg/kg), talipexole (0.04 mg/kg), (+/-)-7-OH-DPAT (0.05 mg/kg), (+/-)-PPHT (0.03 mg/kg), (-)-TNPA (0.06 mg/kg), PD128907 (0.13 mg/kg). The D2 antagonists haloperidol, mazapertine, raclopride, remoxipride, L745870, U99194A, U101958 and S(-)-DS121, the partial agonists PD143188 and preclamol, the selective D1 agonist R(+)-SKF38393 and the D1 antagonist SCH23390, and the uptake inhibitors GBR12909, GBR12935 and indatraline lacked significant inhibitory effects on ultrasonic vocalization. Because at least some of the D2 receptor agonists investigated have selectivity for dopamine autoreceptors, it is speculated that the dopamine autoreceptor may be a target for the development of new antianxiety drugs. PMID:9472724

  8. Experimental studies of axial magnetic fields generated in ultrashort-pulse laser-plasma interaction

    Institute of Scientific and Technical Information of China (English)

    李玉同; 张杰; 陈黎明; 赵理曾; 夏江帆; 魏志义; 江文勉

    2000-01-01

    The quasistatic axial magnetic fields in plasmas produced by ultrashort laser pulses were measured by measuring the Faraday rotation angle of the backscattered emission. The spatial distribution of the axial magnetic field was obtained with a peak value as high as 170 Tesla. Theory suggests that the axial magnetic field is generated by dynamo effect in laser-plasma interaction.

  9. Synthesis and Application of Chiral Spiro Cp Ligands in Rhodium-Catalyzed Asymmetric Oxidative Coupling of Biaryl Compounds with Alkenes.

    Science.gov (United States)

    Zheng, Jun; Cui, Wen-Jun; Zheng, Chao; You, Shu-Li

    2016-04-27

    The vastly increasing application of chiral Cp ligands in asymmetric catalysis results in growing demand for novel chiral Cp ligands. Herein, we report a new class of chiral Cp ligands based on 1,1'-spirobiindane, a privileged scaffold for chiral ligands and catalysts. The corresponding Rh complexes are shown to be excellent catalysts in asymmetric oxidative coupling reactions, providing axially chiral biaryls in 19-97% yields with up to 98:2 er. PMID:27070297

  10. Ligand Identification Scoring Algorithm (LISA)

    Science.gov (United States)

    Zheng, Zheng; Merz, Kenneth M.

    2011-01-01

    A central problem in de novo drug design is determining the binding affinity of a ligand with a receptor. A new scoring algorithm is presented that estimates the binding affinity of a protein-ligand complex given a three-dimensional structure. The method, LISA (Ligand Identification Scoring Algorithm), uses an empirical scoring function to describe the binding free energy. Interaction terms have been designed to account for van der Waals (VDW) contacts, hydrogen bonding, desolvation effects and metal chelation to model the dissociation equilibrium constants using a linear model. Atom types have been introduced to differentiate the parameters for VDW, H-bonding interactions and metal chelation between different atom pairs. A training set of 492 protein-ligand complexes was selected for the fitting process. Different test sets have been examined to evaluate its ability to predict experimentally measured binding affinities. By comparing with other well known scoring functions, the results show that LISA has advantages over many existing scoring functions in simulating protein-ligand binding affinity, especially metalloprotein-ligand binding affinity. Artificial Neural Network (ANN) was also used in order to demonstrate that the energy terms in LISA are well designed and do not require extra cross terms. PMID:21561101

  11. Proto-I axial-focusing experiments

    International Nuclear Information System (INIS)

    The time-integrated axial (z) focus of the 4.5-cm-radius Proto I (1.5 MV, 500 kA) radial proton diode is presently limited to approx. 3 mm FWHM. This result is obtained with current neutralized beam transport in a gas cell with 6 Torr argon. If the vertical local divergence were the same (10 or less) as the horizontal divergence, the local divergence alone would produce a 1.5 mm FWHM focus. The axial focal size is evidently limited by time-dependent effects. These are studied by observing the beam incident upon various targets with two time-resolved pinhole cameras. The first camera observes Rutherford-scattered protons from gold targets with an array of 11 siicon PIN detectors. The second camera observes K/sub α/-fluorescence from aluminum targets with 4 independently-gated microchannel plates imaging tubes

  12. DYNAMIC RESPONSES OF VISCOELASTIC AXIALLY MOVING BELT

    Institute of Scientific and Technical Information of China (English)

    李映辉; 高庆; 蹇开林; 殷学纲

    2003-01-01

    Based on the Kelvin viscoelastic differential constitutive law and the motion equation of the axially moving belt, the nonlinear dynamic model of the viscoelastic axial moving belt was established. And then it was reduced to be a linear differential system which the analytical solutions with a constant transport velocity and with a harmonically varying transport velocity were obtained by applying Lie group transformations. According to the nonlinear dynamic model, the effects of material parameters and the steady-state velocity and the perturbed axial velocity of the belt on the dynamic responses of the belts were investigated by the research of digital simulation. The result shows: 1 ) The nonlinear vibration frequency of the belt will become small when the relocity of the belt increases. 2 ) Increasing the value of viscosity or decreasing the value of elasticity leads to a deceasing in vibration frequencies. 3 ) The most effects of the transverse amplitudes come from the frequency of the perturbed velocity when the belt moves with harmonic velocity.

  13. Clinical Use of PPARγ Ligands in Cancer

    Directory of Open Access Journals (Sweden)

    Jennifer L. Hatton

    2008-01-01

    Full Text Available The role of PPARγ in adipocyte differentiation has fueled intense interest in the function of this steroid nuclear receptor for regulation of malignant cell growth and differentiation. Given the antiproliferative and differentiating effects of PPARγ ligands on liposarcoma cells, investigation of PPARγ expression and ligand activation in other solid tumors such as breast, colon, and prostate cancers ensued. The anticancer effects of PPARγ ligands in cell culture and rodent models of a multitude of tumor types suggest broad applicability of these agents to cancer therapy. This review focuses on the clinical use of PPARγ ligands, specifically the thiazolidinediones, for the treatment and prevention of cancer.

  14. Transport and Retention of CdSe/ZnS Quantum Dots in Saturated Sand: Effects of Organic Ligands, pH and Ionic Strength

    Science.gov (United States)

    Li, Chunyan; Snee, Preston; Darnault, Christophe

    2016-04-01

    The presence of nanomaterials in soil, water, and air systems following their life cycle or accidents and their effects on the environment and public health are inevitable. Ability to forecast the public health and ecological impacts of these nanomaterials encountered in the environment is limited. Therefore, it is critical to be able to predict the fate and transport on nanomaterials in the environment, in particular the subsurface, in order to conduct risk assessments. To assess the transport and retention of nanomaterials in the subsurface environment, we selected quantum dots (QDs). QDs are metal and semiconductor based nanomaterials that are essential to nanoscience and nanotechnology. Understanding the parameters that effect the transport and retention of QDs in the soil water environment is critical. Natural organic ligands are commonly found in soils and impact the soil physico-chemical processes through multifaceted reactions with metal ions present in soil solution and ligand exchange reactions on soil surfaces. Therefore, ligands may modify the surface properties of QDs and effect their stability, transport and retention in the subsurface environment. In this research, size, surface charge, and stability of CdSe/ZnS QDs in water solutions are monitored in batch experiments. The influence of organic ligands (acetate, oxalate, and citrate) on the stability of QDs at different pHs (1.5, 3.5, 5, 7 and 9) and ionic strengths (0.05 and 0.1 M) conditions were examined. The stability and aggregation phenomena of QDs were studied using UV-vis and DLS methods. Parameters from batch studies were selected to establish chemical conditions to be used in transport experiments to produce breakthrough curves and retention profiles in order to characterize the fate and transport of QDs in saturated sand. These transport experiments are essential to understand the mobility and retention processes in porous media where QD interactions with surfaces of heterogeneous

  15. Simulation of an Axial Vircator

    CERN Document Server

    Tikhomirov, V V

    2013-01-01

    An algorithm of particle-in-cell simulations is described and tested to aid further the actual design of simple vircators working on axially symmetric modes. The methods of correction of the numerical solution, have been chosen and jointly tested, allow the stable simulation of the fast nonlinear multiflow dynamics of virtual cathode formation and evolution, as well as the fields generated by the virtual cathode. The selected combination of the correction methods can be straightforwardly generalized to the case of axially nonsymmetric modes, while the parameters of these correction methods can be widely used to improve an agreement between the simulation predictions and the experimental data.

  16. Host-guest complexation. 18. Effects on cation binding of convergent ligand sites appended to macrocyclic polyethers

    International Nuclear Information System (INIS)

    Syntheses are reported for 16 new macrocyclic polyether ligand systems which contain potentially convergent side chains containing additional binding sites. The free energies of association of these systems in CDCl3 at 250C with Li+, Na+, K+, Rb+, Cs+, NH4+, CH3NH3+, and t-BuNH3+ picrates were determined

  17. Diastereoselective Addition of α-Metalated Sulfoxides to Imines Revisited: Mechanism, Computational Studies, and the Effect of External Chiral Ligands

    DEFF Research Database (Denmark)

    Pedersen, Brian; Rein, Tobias; Søtofte, Inger;

    2003-01-01

    six-membered "flat chair") was probed by quantum mechanical calculations, which underpinned the idea of using external chiral ligands to enhance the diastereoselectivity of otherwise moderately selective reactions. In this way, the diastereomeric ratio of the product 3a could be raised from (84 : 16...

  18. Combined effects of ankylosing spondylitis-associated ERAP1 polymorphisms outside the catalytic and peptide-binding sites on the processing of natural HLA-B27 ligands.

    Science.gov (United States)

    Martín-Esteban, Adrian; Gómez-Molina, Patricia; Sanz-Bravo, Alejandro; López de Castro, José A

    2014-02-14

    ERAP1 polymorphism involving residues 528 and 575/725 is associated with ankylosing spondylitis among HLA-B27-positive individuals. We used four recombinant variants to address the combined effects of the K528R and D575N polymorphism on the processing of HLA-B27 ligands. The hydrolysis of a fluorogenic substrate, Arg-528/Asp-575 ERAP1 was a major determinant of the abundance of these peptides in vivo. The hydrolysis of fluorogenic and peptide substrates by an HLA-B27 ligand or a shorter peptide, respectively, was increasingly inhibited as a function of ERAP1 activity, indicating that residues 528 and 575 affect substrate inhibition of ERAP1 trimming. The significant and complex effects of co-occurring ERAP1 polymorphisms on multiple HLA-B27 ligands, and their potential to alter the immunological and pathogenetic features of HLA-B27 as a function of the ERAP1 context, explain the epistatic association of both molecules in ankylosing spondylitis. PMID:24352655

  19. Axial- and radial-resolved electron density and excitation temperature of aluminum plasma induced by nanosecond laser: Effect of the ambient gas composition and pressure

    Directory of Open Access Journals (Sweden)

    Mahmoud S. Dawood

    2015-11-01

    Full Text Available The spatial variation of the characteristics of an aluminum plasma induced by a pulsed nanosecond XeCl laser is studied in this paper. The electron density and the excitation temperature are deduced from time- and space- resolved Stark broadening of an ion line and from a Boltzmann diagram, respectively. The influence of the gas pressure (from vacuum up to atmospheric pressure and compositions (argon, nitrogen and helium on these characteristics is investigated. It is observed that the highest electron density occurs near the laser spot and decreases by moving away both from the target surface and from the plume center to its edge. The electron density increases with the gas pressure, the highest values being occurred at atmospheric pressure when the ambient gas has the highest mass, i.e. in argon. The excitation temperature is determined from the Boltzmann plot of line intensities of iron impurities present in the aluminum target. The highest temperature is observed close to the laser spot location for argon at atmospheric pressure. It decreases by moving away from the target surface in the axial direction. However, no significant variation of temperature occurs along the radial direction. The differences observed between the axial and radial direction are mainly due to the different plasma kinetics in both directions.

  20. Ligand field effects in the nuclear magnetic shielding of nitrogen-15 and cobalt-59 in bent nitrosyl complexes of cobalt(III)

    International Nuclear Information System (INIS)

    A range of square-pyramidal complexes of cobalt(III) with a bent apical nitrosyl ligand has been prepared and examined by 15N and 59Co NMR spectroscopy, in a study of nephelauxetic and spectrochemical effects at the metal and nitrogen nuclei in the bent Co-NO chromophore. The basal ligands in this comparison include dithiocarbamate, quadridentate Schiff base or porphine, and bis-chelating diamine or oximate, so as to give S4, S2N2, N4, OONN, or ONON coordination in the plane and a range of substituents in the chelate and phenylene rings. The shielding of both cobalt and nitrogen tends to decrease with decrease in the M(d) → π*(NO) back-bonding, as indicated by the MN and NO bond distances, the MNO angle and the NO stretching frequency. The shieldings decrease from sulfur to nitrogen to oxygen coligators and also with electron withdrawal by ring substituents (and vice versa), i.e. with decrease in the ligand field splitting and in the nephelauxetism of the coligands. These parallelisms of the cobalt and nitrogen shielding accord with the orbital theory that was developed to explain the bending of the MNO ligand and influences of the metal and coligands. Significant interdependence of spectrochemical and nephelauxetic effects at cobalt and nitrogen arises from the degree of overlap and similarity in energies of the frontier orbitals for the paramagnetic circulation at nitrogen [n(N) → π* (NO)] and at cobalt (d-d). 43 references, 5 figures, 2 tables

  1. Osteoprotegerin and osteoprotegerin ligand expression during human marrow stromal cell differentiation and their effect on osteoclast formation

    Institute of Scientific and Technical Information of China (English)

    YANG Lin; HAI Yong; ZHOU Jun-lin

    2011-01-01

    ackground Osteoprotegerin (OPG) and osteoprotegerin ligand (OPGL) play an important role in human bone metabolism. The aim of this research was to detect the expression of OPG and OPGL during human marrow stromal cells (hMSC) differentiation into osteoblasts (OB), and to observe their effect on osteoclasts (OC) formation in vitro to investigate bone metabolism mechanisms.Methods hMSCs were obtained from human bone marrow specimens using gradient centrifugation method, before being purified and incubated with differentiation medium to develop along the human osteoblasts (hOB) pathway. Morphology observation, biochemical detection and cell staining were performed during hMSC differentiation. OPG and OPGL mRNA levels were detected by reverse transcription-polymerase chain reaction. OPG and OPGL protein expression were determined by Western blotting. We further obtained OC progenitor cells from mice bone marrow and co-cultured with differentiating MSCs. We assessed the effect of OPG and OPGL on OC formation by identifying tartrate resistant acid phosphatase (TRAP) positive multinuclear cells.Results Optimal hMSC survival and purification were observed, along with stable biochemical indexes. Alkaline phosphatase secretion increased significantly and mineralization nodules appeared in the process of cell differentiation. OPG mRNA and protein level increased significantly, while OPGL mRNA and protein level decreased. Average levels of OPG mRNA and protein were about 2.5-fold higher than the control, while OPGL mRNA and protein levels were reduced by about one-half. In the group co-culturing with undifferentiated MSC or added OPGL, we found TRAP positive and multinuclear OC formation. However, OC formation was absent in the group co-culturing with differentiated MSC or added OPG.Conclusions During hMSC differentiation into hOB, OPG secretion increased rapidly and OPGL production decreased significantly. The OPG/OPGL ratio was also increased, while OC formation was

  2. Handling ligands with Coot

    OpenAIRE

    Debreczeni, Judit É.; Emsley, Paul

    2012-01-01

    Coot is a molecular-graphics application primarily aimed to assist in model building and validation of biological macromolecules. Recently, tools have been added to work with small molecules. The newly incorporated tools for the manipulation and validation of ligands include interaction with PRODRG, subgraph isomorphism-based tools, representation of ligand chemistry, ligand fitting and analysis, and are described here.

  3. Axial structure of the nucleon

    Energy Technology Data Exchange (ETDEWEB)

    Veronique Bernard; Latifa Elouadrhiri; Ulf-G Meissner

    2002-01-01

    We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.

  4. Design and Simulation of Axial Flow Maglev Blood Pump

    OpenAIRE

    Huachun Wu; Ziyan Wang; Xujun Lv

    2011-01-01

    The axial flow maglev blood pump (AFMBP) has become a global research focus and emphasis for artificial ventricular assist device, which has no mechanical contact, mechanical friction, compact structure and light weight, can effectively solve thrombus and hemolysis. Magnetic suspension and impeller is two of the important parts in the axial flow maglev blood pump, and their structure largely determines the blood pump performance. The research adopts electromagnetic and fluid finite element an...

  5. Radial breathing mode of carbon nanotubes subjected to axial pressure

    OpenAIRE

    Lei, Xiao-Wen; Ni, Qing-Qing; Shi, Jin-Xing; Natsuki, Toshiaki

    2011-01-01

    In this paper, a theoretical analysis of the radial breathing mode (RBM) of carbon nanotubes (CNTs) subjected to axial pressure is presented based on an elastic continuum model. Single-walled carbon nanotubes (SWCNTs) are described as an individual elastic shell and double-walled carbon nanotubes (DWCNTs) are considered to be two shells coupled through the van der Waals force. The effects of axial pressure, wave numbers and nanotube diameter on the RBM frequency are investigated in detail. Th...

  6. Particle simulation of an improved axially extracted vircator

    International Nuclear Information System (INIS)

    An axially extracted virtual cathode oscillator (vircator) with a feedback annulus is proposed and configured through particle-in-cell (PIC) simulation. In this paper, the effects of the feedback mechanism are studied through PIC method. The simulated results indicate that the improved new vircator can increase the output power twice large than that of the axially-extracted conventional vircator under the same condition. On the other hand, it can narrow the bandwidth and purify the modes

  7. Particle Simulation of an Improved Axially Extracted Vircator

    Institute of Scientific and Technical Information of China (English)

    刘振祥; 舒挺; 张建德; 钱宝良

    2003-01-01

    An axially extracted virtual cathode oscillator (vircator) with a feedback annulusis proposed and configured through particle-in-cell (PIC) simulation in Ref. [1]. In this paper,the effects of the feedback mechanism are studied through PIC method. The simulated resultsindicate that the improved new vircator can increase the output power twice large than that ofthe axially-extracted conventional vircator under the same condition. On the other hand, it cannarrow the bandwidth and purify the modes.

  8. The New Performance Calculation Method of Fouled Axial Flow Compressor

    OpenAIRE

    Huadong Yang; Hong Xu

    2014-01-01

    Fouling is the most important performance degradation factor, so it is necessary to accurately predict the effect of fouling on engine performance. In the previous research, it is very difficult to accurately model the fouled axial flow compressor. This paper develops a new performance calculation method of fouled multistage axial flow compressor based on experiment result and operating data. For multistage compressor, the whole compressor is decomposed into two sections. The first section in...

  9. Chiral benzamidinate ligands in rare-earth-metal coordination chemistry.

    Science.gov (United States)

    Benndorf, Paul; Kratsch, Jochen; Hartenstein, Larissa; Preuss, Corinna M; Roesky, Peter W

    2012-11-01

    The treatment of the recently reported potassium salt (S)-N,N'-bis-(1-phenylethyl)benzamidinate ((S)-KPEBA) and its racemic isomer (rac-KPEBA) with anhydrous lanthanide trichlorides (Ln = Sm, Er, Yb, Lu) afforded mostly chiral complexes. The tris(amidinate) complex [{(S)-PEBA}(3)Sm], bis(amidinate) complexes [{Ln(PEBA)(2)(μ-Cl)}(2)] (Ln = Sm, Er, Yb, Lu), and mono(amidinate) compounds [Ln(PEBA)(Cl)(2)(thf)(n)] (Ln = Sm, Yb, Lu) were isolated and structurally characterized. As a result of steric effects, the homoleptic 3:1 complexes of the smaller lanthanide atoms Yb and Lu were not accessible. Furthermore, chiral bis(amidinate)-amido complexes [{(S)-PEBA}(2)Ln{N(SiMe(3))(2)}] (Ln = Y, Lu) were synthesized by an amine-elimination reaction and salt metathesis. All of these chiral bis- and tris(amidinate) complexes had additional axial chirality and they all crystallized as diastereomerically pure compounds. By using rac-PEBA as a ligand, an achiral meso arrangement of the ligands was observed. The catalytic activities and enantioselectivities of [{(S)-PEBA}(2)Ln{N(SiMe(3))(2)}] (Ln = Y, Lu) were investigated in hydroamination/cyclization reactions. A clear dependence of the rate of reaction and enantioselectivity on the ionic radius was observed, which showed higher reaction rates but poorer enantioselectivities for the yttrium compound. PMID:23015310

  10. Axial electron-channelling analysis of perovskite

    International Nuclear Information System (INIS)

    The orientation dependence of characteristic X-ray emission (the Borrmann effect) under near-zone-axis diffraction conditions has been used to identify the site preferences of strontium, zirconium and uranium impurities within a CaTiO3 (perovskite) host structure. As characteristic emission lines from these impurities occur at both higher and lower energies than the calcium or titanium K-shell excitations, effects of delocalization are clearly measureable, and are used as a tool in axial electron channeling or ALCHEMI analysis. It is found that strontium and uranium strongly partition into calcium sites, whereas zirconium occupies titanium sites. (author)

  11. The Effect of Nitrogen Surface Ligands on Propane Metathesis: Design and Characterizations of N-modified SBA15-Supported Schrock-type Tungsten Alkylidyne

    KAUST Repository

    Eid, Ahmed A.

    2014-04-01

    Catalysis, which is primarily a molecular phenomenon, is an important field of chemistry because it requires the chemical conversion of molecules into other molecules. It also has an effect on many fields, including, but not limited to, industry, environment and life Science[1]. Surface Organometallic Chemistry is an effective methodology for Catalysis as it imports the concept and mechanism of organometallic chemistry, to surface science and heterogeneous catalysis. So, it bridges the gap between homogenous and heterogeneous catalysis[1]. The aim of the present research work is to study the effect of Nitrogen surface ligands on the activity of Alkane, Propane in particular, metathesis. Our approach is based on the preparation of selectively well-defined group (VI) transition metal complexes supported onto mesoporous materials, SBA15 and bearing amido and/or imido ligands. We choose nitrogen ligands because, according to the literature, they showed in some cases better catalytic properties in homogenous catalysis in comparison with their oxygen counterparts[2]. The first section covers the modification of a highly dehydroxylated SBA15 surface using a controlled ammonia treatment. These will result in the preparation of two kind of Nitrogen surface ligands: -\\tOne with vicinal silylamine/silanol, (≡SiNH2)(≡SiOH), noted [N,O]SBA15 and, -\\tAnother\\tone\\twith\\tvicinal\\tbis-silylamine moieties (≡SiNH2)2, noted [N,N]SBA15[3]. The second section covers the reaction of Schrock type Tungsten Carbyne [W(≡C- tBu)(CH2-tBu)3] with those N-surface ligands and their characterizations by FT-IR, multiple quantum solid state NMR (1H, 13C), elemental analysis and gas phase analysis. The third section covers the generation of the active site, tungsten hydride species. Their performance toward propane metathesis reaction using the dynamic reactor technique PID compared toward previous well-known catalysts supported on silica oxide or mesoporous materials[4]. A fairly good

  12. Development and validation of a terrestrial biotic ligand model predicting the effect of cobalt on root growth of barley (Hordeum vulgare)

    International Nuclear Information System (INIS)

    A Biotic Ligand Model was developed predicting the effect of cobalt on root growth of barley (Hordeum vulgare) in nutrient solutions. The extent to which Ca2+, Mg2+, Na+, K+ ions and pH independently affect cobalt toxicity to barley was studied. With increasing activities of Mg2+, and to a lesser extent also K+, the 4-d EC50Co2+ increased linearly, while Ca2+, Na+ and H+ activities did not affect Co2+ toxicity. Stability constants for the binding of Co2+, Mg2+ and K+ to the biotic ligand were obtained: log K CoBL = 5.14, log K MgBL = 3.86 and log K KBL = 2.50. Limited validation of the model with one standard artificial soil and one standard field soil showed that the 4-d EC50Co2+ could only be predicted within a factor of four from the observed values, indicating further refinement of the BLM is needed. - Biotic Ligand Models are not only a useful tool to assess metal toxicity in aquatic systems but can also be used for terrestrial plants

  13. Effect of principal and secondary ligands on the electronic structures and spectra of a series of ruthenium(II complexes

    Directory of Open Access Journals (Sweden)

    Zhang Yanli

    2016-01-01

    Full Text Available A DFT(density functional theory/TDDFT(time-dependent density functional theory investigation is performed to study the ground-state geometries, electronic structures, and absorption spectra of twelve ruthenium(II thiosemicarbazone complexes [Ru(CO(C(Ln], where Ln=derivatives of dibasic tetradentate Schiff-base ligand and X=AsPh3/PPh3/Py. The ground-state geometries are optimized at the B3LYP/6-31G(d-LANL2DZ level, and the spectra are simulated by means of TD-B3LYP/6-31G(d-LANL2DZ method on the basis of the optimized geometries. The influence of principal and secondary ligands (Ln and X on transition characters and absorption peak positions is evaluated.

  14. Photoluminescence properties of new Zn(II) complexes with 8-hydroxyquinoline ligands: Dependence on volume and electronic effect of substituents

    Science.gov (United States)

    Huo, Yanping; Lu, Jiguo; Hu, Sheng; Zhang, Liming; Zhao, Fenghua; Huang, Huarong; Huang, Baohua; Zhang, Li

    2015-03-01

    A series of 2-arylethenyl-8-hydroxyquinoline ligands (A1-A4) with a trimethoxyphenyl, naphthyl, 2-fluoro-4-bromophenyl and anthracenyl group and their corresponding Zn(II) complexes (B1-B4) were synthesized and characterized by means of 1H NMR, ESI-MS, FT-IR and elemental analysis. A1 and A4 were characterized by single-crystal X-ray crystallography. The aggregation behavior of zinc salt and ligands in solution was investigated by several techniques, containing 1H NMR, UV-vis and photoluminescence (PL). The electronic nature and volume of arylethenyl substituents affect the absorption wavelength, the emission color, fluorescence lifetime, fluorescence quantum yield and thermostability of Zn(II) complexes. The experiments corroborated that the properties of Zinc(II) complexes can be tuned by introducing different functional substituents.

  15. Application of the wavelet transforms on axial strain calculation in ultrasound elastography

    Institute of Scientific and Technical Information of China (English)

    LUO Jianwen; BAI Jing; SHAO Jinhua

    2006-01-01

    In ultrasound elastography, the axial strain distribution within biological tissues is calculated as the numerical derivative (differentiation) of the estimated axial displacement field. Unfortunately, the numerical derivative is unstable because it can greatly amplify the noises, especially at high frequencies. This work focuses on the axial strain calculation from the estimated axial displacements using wavelet transforms (WTs), including continuous wavelet transforms (CWTs) and discrete wavelet transforms (DWTs). The feasibility of the WT-based method using the quadratic spline function is verified by computer simulations and some phantom data. Results indicate that the WT-based method can effectively reduce the noise amplification in axial strain calculation.

  16. Computer axial tomography in geosciences

    International Nuclear Information System (INIS)

    Computer Axial Tomography (CAT) is one of the most adequate non-invasive techniques for the investigation of the internal structure of a large category of objects. Initially designed for medical investigations, this technique, based on the attenuation of X- or gamma-ray (and in some cases neutrons), generates digital images which map the numerical values of the linear attenuation coefficient of a section or of the entire volume of the investigated sample. Shortly after its application in medicine, CAT has been successfully used in archaeology, life sciences, and geosciences as well as for the industrial materials non-destructive testing. Depending on the energy of the utilized radiation as well as on the effective atomic number of the sample, CAT can provide with a spatial resolution of 0.01 - 0.5 mm, quantitative as well as qualitative information concerning local density, porosity or chemical composition of the sample. At present two types of axial Computer Tomographs (CT) are in use. One category, consisting of medical as well as industrial CT is equipped with X-ray tubes while the other uses isotopic gamma-ray sources. CT provided with intense X-ray sources (equivalent to 12-15 kCi or 450-550 TBq) has the advantage of an extremely short running time (a few seconds and even less) but presents some disadvantages known as beam hardening and absorption edge effects. These effects, intrinsically related to the polychromatic nature of the X-rays generated by classical tubes, need special mathematical or physical corrections. A polychromatic X-ray beam can be made almost monochromatic by means of crystal diffraction or by using adequate multicomponent filters, but these devices are costly and considerably diminish the output of X-ray generators. In the case of CT of the second type, monochromatic gamma-rays generated by radioisotopic sources, such as 169 Yb (50.4 keV), 241 Am (59 keV), 192 Ir (310.5 and 469.1 keV ) or 137 Cs (662.7 keV), are used in combination with

  17. Kit for preparing Tc (III)-99m myocardial imaging agents that are effective in humans

    International Nuclear Information System (INIS)

    This patent describes a myocardial imaging agent for humans that is a technetium (III) complex ligated in the planar positions by a tetradenate ligand such as (acac)2en and in the axial positions by an ether containing phosphine ligand such as tris(3-methoxy-1-propyl)-phosphine. The agent exhibits extremely rapid blood clearance after injection into a human and has a sufficiently high heart/liver and heart/lung ratios to provide effective myocardial images

  18. Structural diversity of silver(I) 4,6-dipyridyl-2-aminopyrimidine complexes: effect of counteranions and ligand isomerism.

    Science.gov (United States)

    Chi, Ying-Nan; Huang, Kun-Lin; Cui, Feng-Yun; Xu, Yan-Qing; Hu, Chang-Wen

    2006-12-25

    Using two ligands, 4,6-bis(2-pyridyl)-2-aminopyrimidine (L1) with two N,N'-chelating sites and 4-(2-pyridyl)-6-(4-pyridyl)-2-aminopyrimidine (L2) (as the isomer of L1) containing one chelating site and one bridging unit, a series of novel Ag(I) complexes varying from zero- to two-dimensions have been prepared and their crystal structures determined via single-crystal X-ray diffraction. The two ligands are employed for the first time in coordination chemistry. The structures of compounds 1-3 are directed by the counteranions adopted in the reaction system: The reaction of L1 with AgNO3 yielded a dimer [Ag2L12](NO3)2 (1). The reaction of L1 with AgCF3SO3 led to a one-dimension "V-shaped" chain {[AgL1](CF3SO3)}n (2). When AgSCN was used, a one-dimension ladder {[Ag2L1(SCN)2].H2O}n (3) was obtained. While ligand L2 reacted with AgNO3, a two-dimension {[Ag2(L2)2](NO3)2.H2O}n (4) was prepared with the help of an argentophilic interaction. Compounds 1-4 display room-temperature photoluminescence. PMID:17173415

  19. Metal-ligand synergistic effects in the complex Ni(η(2)-TEMPO)2: synthesis, structures, and reactivity.

    Science.gov (United States)

    Isrow, Derek; DeYonker, Nathan J; Koppaka, Anjaneyulu; Pellechia, Perry J; Webster, Charles Edwin; Captain, Burjor

    2013-12-16

    In the current investigation, reactions of the "bow-tie" Ni(η(2)-TEMPO)2 complex with an assortment of donor ligands have been characterized experimentally and computationally. While the Ni(η(2)-TEMPO)2 complex has trans-disposed TEMPO ligands, proton transfer from the C-H bond of alkyne substrates (phenylacetylene, acetylene, trimethylsilyl acetylene, and 1,4-diethynylbenzene) produce cis-disposed ligands of the form Ni(η(2)-TEMPO)(κ(1)-TEMPOH)(κ(1)-R). In the case of 1,4-diethynylbenzene, a two-stage reaction occurs. The initial product Ni(η(2)-TEMPO)(κ(1)-TEMPOH)[κ(1)-CC(C6H4)CCH] is formed first but can react further with another equivalent of Ni(η(2)-TEMPO)2 to form the bridged complex Ni(η(2)-TEMPO)(κ(1)-TEMPOH)[κ(1)-κ(1)-CC(C6H4)CC]Ni(η(2)-TEMPO)(κ(1)-TEMPOH). The corresponding reaction with acetylene, which could conceivably also yield a bridging complex, does not occur. Via density functional theory (DFT), addition mechanisms are proposed in order to rationalize thermodynamic and kinetic selectivity. Computations have also been used to probe the relative thermodynamic stabilities of the cis and trans addition products and are in accord with experimental results. Based upon the computational results and the geometry of the experimentally observed product, a trans-cis isomerization must occur. PMID:24262003

  20. Silicon(IV) phthalocyanines substituted axially with different nucleoside moieties. Effects of nucleoside type on the photosensitizing efficiencies and in vitro photodynamic activities.

    Science.gov (United States)

    Zheng, Bi-Yuan; Shen, Xiao-Min; Zhao, Dong-Mei; Cai, Yi-Bin; Ke, Mei-Rong; Huang, Jian-Dong

    2016-06-01

    A series of new silicon(IV) phthalocyanines (SiPcs) di-substituted axially with different nucleoside moieties have been synthesized and evaluated for their singlet oxygen quantum yields (ΦΔ) and in vitro photodynamic activities. The adenosine-substituted SiPc shows a lower photosensitizing efficiency (ΦΔ=0.35) than the uridine- and cytidine-substituted analogs (ΦΔ=0.42-0.44), while the guanosine-substituted SiPc exhibits a weakest singlet oxygen generation efficiency with a ΦΔ value down to 0.03. On the other hand, replacing axial adenosines with chloro-modified adenosines and purines can result in the increase of photogenerating singlet oxygen efficiencies of SiPcs. The formed SiPcs 1 and 2, which contain monochloro-modified adenosines and dichloro-modified purines respectively, appear as efficient photosensitizers with ΦΔ of 0.42-0.44. Both compounds 1 and 2 present high photocytotoxicities against HepG2 and BGC823 cancer cells with IC50 values ranging from 9nM to 33nM. The photocytotoxicities of these two compounds are remarkably higher than the well-known anticancer photosensitizer, chlorin e6 (IC50=752nM against HepG2 cells) in the same condition. As revealed by confocal microscopy, for both cell lines, compound 1 can essentially bind to mitochondria, while compound 2 is just partially localized in mitochondria. In addition, the two compounds induce cell death of HepG2 cells likely through apoptosis. PMID:27085051

  1. Analysis of differential secondary effects of novel rexinoids: select rexinoid X receptor ligands demonstrate differentiated side effect profiles.

    Science.gov (United States)

    Marshall, Pamela A; Jurutka, Peter W; Wagner, Carl E; van der Vaart, Arjan; Kaneko, Ichiro; Chavez, Pedro I; Ma, Ning; Bhogal, Jaskaran S; Shahani, Pritika; Swierski, Johnathon C; MacNeill, Mairi

    2015-03-01

    In order to determine the feasibility of utilizing novel rexinoids for chemotherapeutics and as potential treatments for neurological conditions, we undertook an assessment of the side effect profile of select rexinoid X receptor (RXR) analogs that we reported previously. We assessed pharmacokinetic profiles, lipid and thyroid-stimulating hormone (TSH) levels in rats, and cell culture activity of rexinoids in sterol regulatory element-binding protein (SREBP) induction and thyroid hormone inhibition assays. We also performed RNA sequencing of the brain tissues of rats that had been dosed with the compounds. We show here for the first time that potent rexinoid activity can be uncoupled from drastic lipid changes and thyroid axis variations, and we propose that rexinoids can be developed with improved side effect profiles than the parent compound, bexarotene (1). PMID:26038698

  2. 水压力和轴力联合作用下常态混凝土的断裂试验研究%Experimental Investigation into Fracture of Normal Concrete under Combined Effects of Water Pressure and Axial Force

    Institute of Scientific and Technical Information of China (English)

    孔祥清; 王学志; 肖克见; 刘华新; 邹浩飞

    2014-01-01

    针对常态混凝土高坝在蓄水状态下可能出现的水力劈裂现象,采用恒定水压力加轴向拉力和恒定轴向拉力加水压力两种不同的加载方式,进行了水压力和外力联合作用下的常态混凝土试件轴拉试验。对试验结果进行了分析,得到了常态混凝土断裂的荷载-应变变化规律。结合试验条件计算了裂缝尖端的应力强度因子,得到了两种不同加载条件下的失稳断裂韧度,并进行了对比分析。%For the normal concrete dam that is under reservoir condition may appear the phenomenon of hydraulic fracturing, the uniaxial tensile experiments were made on crack of normal concrete under the combined effects of water pressure and axial force. Two modes of loading control for test including the constant water pressure with variable axial tension load and the constant axial load with variable water pressure were adopted. The load-strain curves were obtained by analyzing the experimental results. The unstable fracture toughness under the two different loading modes are also obtained and the contrastive analyses are made, with the stress intensity factors on the crack tip calculated.

  3. Ligands for the peroxisome proliferator-activated receptor-γ have inhibitory effects on growth of human neuroblastoma cells in vitro

    International Nuclear Information System (INIS)

    The thiazolidinedione (TZD) or glitazone class of peroxisome proliferator-activated-γ (PPAR-γ) ligands not only induce adipocyte differentiation and increase insulin sensitivity, but also exert growth inhibitory effects on several carcinoma cell lines in vitro as well as in vivo. In the current study the in vitro effect of four PPAR-γ agonists (ciglitazone, pioglitazone, troglitazone, rosiglitazone) on the cell growth of seven human neuroblastoma cell lines (Kelly, LAN-1, LAN-5, LS, IMR-32, SK-N-SH, SH-SY5Y) was investigated. Growth rates were assessed by a colorimetric XTT-based assay kit. Expression of PPAR-γ protein was examined by immunohistochemistry and Western blot analysis. All glitazones inhibited in vitro growth and viability of the human neuroblastoma cell lines in a dose-dependent manner showing considerable effects only at high concentrations (10 μM and 100 μM). Effectiveness of the glitazones on neuroblastoma cell growth differed depending on the cell line and the agent. The presence of PPAR-γ protein was demonstrated in all cell lines. Our findings indicate that ligands for PPAR-γ may be useful therapeutic agents for the treatment of neuroblastoma. Thus the effect of glitazones on the growth of neuroblastoma should now be investigated in an in vivo animal model

  4. View of the Axial Field Spectrometer

    CERN Multimedia

    1980-01-01

    The Axial Field Spectrometer, with the vertical uranium/scintillator calorimeter and the central drift chamber retracted for service. One coil of the Open Axial Field Magnet is just visible to the right.

  5. Simulation of an Axial Vircator

    OpenAIRE

    Tikhomirov, V. V.; Siahlo, S. E.

    2013-01-01

    An algorithm of particle-in-cell simulations is described and tested to aid further the actual design of simple vircators working on axially symmetric modes. The methods of correction of the numerical solution, have been chosen and jointly tested, allow the stable simulation of the fast nonlinear multiflow dynamics of virtual cathode formation and evolution, as well as the fields generated by the virtual cathode. The selected combination of the correction methods can be straightforwardly gene...

  6. A Research on the Effects of Exhaust Braking on the Axial Load of Turbine in Turbocharger%排气制动对增压器涡轮轴向载荷影响的研究

    Institute of Scientific and Technical Information of China (English)

    龚金科; 李靖; 胡辽平; 余明果; 颜胜; 陈韬

    2014-01-01

    In this paper, the working states of turbocharger in exhaust braking condition are analyzed for the vehicles concurrently adopting exhaust braking and turbocharging. Through a linked test with both exhaust bra-king and turbocharging functioning, the boundary conditions required for numerical calculation are obtained, and based on which the axial forces of turbine in both steady and transitional conditions are calculated. The results show that in exhaust braking condition, the axial force of turbine reverses its direction, and the higher the exhaust back-pressure the larger the axial force. In the process of working condition switching, the turbine is subjected to high shock load with a highest value up to 221N, and the shorter switching time and higher back pressure will lead to a greater impact load. Hence selecting a reasonable backpressure and an appropriate witching strategy can effectively reduce the axial load of turbine.%本文中针对同时采用排气制动和涡轮增压的车辆,分析其在排气制动工况下增压器的工作状态。通过排气制动与增压器联动试验得出数值计算所需的边界条件,并据此计算涡轮转子在稳态工况和过渡工况的轴向受力。结果表明,在排气制动工况下,增压器涡轮转子的轴向受力反向,且排气背压越高,涡轮转子所受轴向力越大;在工况切换过程中,涡轮转子所受突变载荷较大,最高值达221N,工况切换时间越短、背压越高,轴向冲击载荷越大。因此确定合理的排气背压和工况切换策略可有效降低涡轮转子所承受的轴向载荷。

  7. Protein-ligand-based pharmacophores: generation and utility assessment in computational ligand profiling.

    Science.gov (United States)

    Meslamani, Jamel; Li, Jiabo; Sutter, Jon; Stevens, Adrian; Bertrand, Hugues-Olivier; Rognan, Didier

    2012-04-23

    Ligand profiling is an emerging computational method for predicting the most likely targets of a bioactive compound and therefore anticipating adverse reactions, side effects and drug repurposing. A few encouraging successes have already been reported using ligand 2-D similarity searches and protein-ligand docking. The current study describes the use of receptor-ligand-derived pharmacophore searches as a tool to link ligands to putative targets. A database of 68,056 pharmacophores was first derived from 8,166 high-resolution protein-ligand complexes. In order to limit the number of queries, a maximum of 10 pharmacophores was generated for each complex according to their predicted selectivity. Pharmacophore search was compared to ligand-centric (2-D and 3-D similarity searches) and docking methods in profiling a set of 157 diverse ligands against a panel of 2,556 unique targets of known X-ray structure. As expected, ligand-based methods outperformed, in most of the cases, structure-based approaches in ranking the true targets among the top 1% scoring entries. However, we could identify ligands for which only a single method was successful. Receptor-ligand-based pharmacophore search is notably a fast and reliable alternative to docking when few ligand information is available for some targets. Overall, the present study suggests that a workflow using the best profiling method according to the protein-ligand context is the best strategy to follow. We notably present concrete guidelines for selecting the optimal computational method according to simple ligand and binding site properties. PMID:22480372

  8. Difference between measured and predicted axial offset at NPP Krsko

    International Nuclear Information System (INIS)

    At NPP Krsko axial power distribution is monitored through periodic measurements of the AO (axial offset). AO represents the normalized power difference between top and bottom of the core. Within the core design process predicted values of axial offset (P-AO) for the entire core lifetime are calculated. During the core performance surveillance measured AO (M-AO) is compared to the predicted value. Measured vs. predicted axial offset difference (D-AO) of +3% at hot-full-power (HFP) steady-state core conditions is considered to be within measurement and design tolerances. During the last two 18 months cycles increase in the D-AO above 3 % was experienced for limited period of time at NPP Krsko - in cycle 22 for more than 90 EFPD (Effective Full Power Days). For such deviation evaluation has to be performed to confirm that reload safety evaluation and analysis of the core has not been impacted. Root cause analysis was performed afterwards and it was classified as a core design computer code deficiency. Precisely, inadequate axial actinides treatment in the computer code contributed to the observed axial offset difference. (author)

  9. Antidepressant-like effects of the cannabinoid receptor ligands in the forced swimming test in mice: mechanism of action and possible interactions with cholinergic system.

    Science.gov (United States)

    Kruk-Slomka, Marta; Michalak, Agnieszka; Biala, Grazyna

    2015-05-01

    The purpose of the experiments was to explore the role of the endocannabinoid system, through cannabinoid (CB) receptor ligands, nicotine and scopolamine, in the depression-related responses using the forced swimming test (FST) in mice. Our results revealed that acute injection of oleamide (10 and 20 mg/kg), a CB1 receptor agonist, caused antidepressant-like effect in the FST, while AM 251 (0.25-3 mg/kg), a CB1 receptor antagonist, did not provoke any effect in this test. Moreover, acute administration of both CB2 receptor agonist, JWH 133 (0.5 and 1 mg/kg) and CB2 receptor antagonist, AM 630 (0.5 mg/kg), exhibited antidepressant action. Antidepressant effects of oleamide and JWH 133 were attenuated by acute injection of both non-effective dose of AM 251, as well as AM 630. Among the all CB compounds used, only the combination of non-effective dose of oleamide (2.5 mg/kg) with non-effective dose of nicotine (0.5 mg/kg) caused an antidepressant effect. However, none of the CB receptor ligands, had influence on the antidepressant effects provoked by nicotine (0.2 mg/kg) injection. In turn, the combination of non-effective dose of oleamide (2.5 mg/kg); JWH (2 mg/kg) or AM 630 (2 mg/kg), but not of AM 251 (0.25 mg/kg), with non-effective dose of scopolamine (0.1 mg/kg), exhibited antidepressant properties. Indeed, all of the CB compounds used, intensified the antidepressant-like effects induced by an acute injection of scopolamine (0.3 mg/kg). Our results provide clear evidence that the endocannabinoid system participates in the depression-related behavior and through interactions with cholinergic system modulate these kind of responses. PMID:25660201

  10. MCM-41 Bound Ruthenium Complex as Heterogeneous Catalyst for Hydrogenation Ⅰ: Effect of Support, Ligand and Solvent on the Catalyst Performance

    Institute of Scientific and Technical Information of China (English)

    YU, Ying-Min; FEI, Jin-Hua; ZHANG, Yi-Ping; ZHENG, Xiao-Ming

    2006-01-01

    The functionalized MCM-41 mesoporous bound ruthenium complex was synthesized and characterized using elemental analysis, atomic absorption spectrophotometer, BET, XRD and FTIR. Hydrogenation of carbon dioxide to formic acid was investigated over these catalysts under supercritical CO2 condition. The effect of reactant gas partial pressure, supports, solvents and ligands on the synthesis of formic acid was studied. These factors could influence the catalyst activity, stability and reuse performance greatly and no byproduct was detected. These promising catalysts also offered the industrial advantages such as easy separation.

  11. Chitosan and carboxymethyl-chitosan capping ligands: Effects on the nucleation and growth of hydroxyapatite nanoparticles for producing biocomposite membranes.

    Science.gov (United States)

    Dumont, Vitor C; Mansur, Alexandra A P; Carvalho, Sandhra M; Medeiros Borsagli, Fernanda G L; Pereira, Marivalda M; Mansur, Herman S

    2016-02-01

    Synthetic biomaterials based on calcium phosphates (CaP) have been widely studied for bone tissue reconstruction therapies, but no definitive solution that fulfills all of the required properties has been identified. Thus, this study reports the synthesis of composite membranes based on nanohydroxyapatite particles (nHA) embedded in chitosan (CHI) and O-carboxymethyl chitosan (CMC) matrices produced using a one-step co-precipitation method in water media. Biopolymers were used as capping ligands for simultaneously controlling the nucleation and growth of the nHA particles during the precipitation process and also to form the polymeric network of the biocomposites. The bionanocomposites were extensively characterized using light microscopy (LM), scanning and transmission electron microscopy (SEM/TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), atomic force microscopy (AFM), X-ray micro-CT analysis (μCT), andMTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazoliumbromide) cell proliferation assays for cell cytotoxicity. The results demonstrated that the ligands used during the synthesis highly affected the composites produced, primarily due the changes in the mechanisms and kinetics of nucleation and growth of the HA particles at the nanoscale level. The SEMimages revealed that the use of carboxyl-functionalized chitosan (CMC) ligands significantly reduced the average size of theHA nanoparticles and caused the formation of a narrower size distribution (90±20nm) compared to theHAnanoparticles producedwith chitosan ligands (220±50nm). The same trend was verified by the AFM analysis,where the nHA particles were formed evenly dispersed in the polymer matrix. However, the CMC-based composites were more homogeneously distributed, which was endorsed by the images collected via X-ray micro-CT. The FTIR spectra and the XRD analysis indicated that nanosized hydroxyapatite was the predominant calcium

  12. Effect of Partial Shrouds on the Performance and Flow Field of a Low-Aspect-Ratio Axial-Flow Fan Rotor

    Directory of Open Access Journals (Sweden)

    N. Sitaram

    2011-01-01

    Full Text Available The flow field at the rotor exit of a low aspect ratio axial flow fan for different tip geometries and for different flow coefficients is measured in the present study. The following configurations are tested: (1 rotor without partial shroud, designated as rotor (wos, (2 rotor with partial shroud, designated as rotor (ws, and (3 rotor with perforated (perforations in the shape of discrete circular holes partial shroud, designated as rotor (wps. From steady state measurements, the performance of rotor (wps is found to be the best. Both the rotors with partial shrouds have stalled at a higher flow coefficient compared to that of rotor (wos. From periodic flow measurements, it is concluded that the low velocity region near the tip section is considerably reduced with the use of partial shrouds with perforations. The extent of this low velocity region for both rotor (wos and rotor (wps increases with decreasing flow coefficient due to increased stage loading. This core of low momentum fluid has moved inwards of the annulus and towards the pressure side as the flow coefficient decreases. The extent of the low momentum fluid is smaller for rotor (wps than that of rotor (wos at all flow coefficients.

  13. Axial Force at the Vessel Bottom Induced by Axial Impellers

    OpenAIRE

    I. Fořt; P. Hasal; A. Paglianti; F. Magelli

    2008-01-01

    This paper deals with the axial force affecting the flat bottom of a cylindrical stirred vessel. The vessel is equipped with four radial baffles and is stirred with a four 45° pitched blade impeller pumping downwards. The set of pressure transducers is located along the whole radius of the flat bottom between two radial baffles. The radial distribution of the dynamic pressures indicated by the transducers is measured in dependence on the impeller off-bottom clearance and impeller speed.It fol...

  14. Effects of charge and surface ligand properties of nanoparticles on oxidative stress and gene expression within the gut of Daphnia magna

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez, Gustavo A.; Lohse, Samuel E.; Torelli, Marco; Murphy, Catherine; Hamers, Robert J.; Orr, Galya; Klaper, Rebecca D.

    2015-05-01

    Concern has been raised regarding the current and future release of engineered nanomaterials into aquatic environments from industry and other sources. However, not all nanomaterials may cause an environ-mental impact and identifying which nanomaterials may be of greatest concern has been difficult. It is thought that the surface groups of a functionalized nanoparticles (NPs) may play a significant role in determining their interactions with aquatic organisms, but the way in which surface properties of NPs impact their toxicity in whole organisms has been minimally explored. A major point of interaction of NPs with aquatic organisms is in the gastrointestinal tract as they ingest particulates from the water column or from the sediment. The main goal of this study was to use model gold NP (AuNPs) to evaluate the potential effects of the different surfaces groups on NPs on the gut of an aquatic model organism, Daphnia magna. In this study, we exposed daphnids to a range of AuNPs concentrations and assessed the impact of AuNP exposure in the daphnid gut by measuring reactive oxygen species (ROS) production and expression of genes associated with oxidative stress and general cellular stress: glutathione S-transferase(gst), catalase (cat), heat shock protein 70 (hsp70), and metallothionein1 (mt1). We found ROS formation and gene expression were impacted by both charge and the specific surface ligand used. We detected some degree of ROS production in all NP exposures, but positively charged AuNPs induced a greater ROS response. Similarly, we observed that, compared to controls, both positively charged AuNPs and only one negatively AuNP impacted expression of genes associated with cellular stress. Finally, ligand-AuNP exposures showed a different toxicity and gene expression profile than the ligand alone, indicating a NP specific effect.

  15. Effects of charge and surface ligand properties of nanoparticles on oxidative stress and gene expression within the gut of Daphnia magna.

    Science.gov (United States)

    Dominguez, Gustavo A; Lohse, Samuel E; Torelli, Marco D; Murphy, Catherine J; Hamers, Robert J; Orr, Galya; Klaper, Rebecca D

    2015-05-01

    Concern has been raised regarding the current and future release of engineered nanomaterials into aquatic environments from industry and other sources. However, not all nanomaterials may cause an environmental impact and identifying which nanomaterials may be of greatest concern has been difficult. It is thought that the surface groups of a functionalized nanoparticles (NPs) may play a significant role in determining their interactions with aquatic organisms, but the way in which surface properties of NPs impact their toxicity in whole organisms has been minimally explored. A major point of interaction of NPs with aquatic organisms is in the gastrointestinal tract as they ingest particulates from the water column or from the sediment. The main goal of this study was to use model gold NP (AuNPs) to evaluate the potential effects of the different surfaces groups on NPs on the gut of an aquatic model organism, Daphnia magna. In this study, we exposed daphnids to a range of AuNPs concentrations and assessed the impact of AuNP exposure in the daphnid gut by measuring reactive oxygen species (ROS) production and expression of genes associated with oxidative stress and general cellular stress: glutathione S-transferase (gst), catalase (cat), heat shock protein 70 (hsp70), and metallothionein1 (mt1). We found ROS formation and gene expression were impacted by both charge and the specific surface ligand used. We detected some degree of ROS production in all NP exposures, but positively charged AuNPs induced a greater ROS response. Similarly, we observed that, compared to controls, both positively charged AuNPs and only one negatively AuNP impacted expression of genes associated with cellular stress. Finally, ligand-AuNP exposures showed a different toxicity and gene expression profile than the ligand alone, indicating a NP specific effect. PMID:25734859

  16. A new fullerene complexation ligand: N-pyridylfulleropyrrolidine.

    Science.gov (United States)

    Tat, Fatma T; Zhou, Zhiguo; MacMahon, Shaun; Song, Fayi; Rheingold, Arnold L; Echegoyen, Luis; Schuster, David I; Wilson, Stephen R

    2004-07-01

    The subject of this paper is a new fullerene building block design with the potential for defined geometry and good electronic communication. The synthesis and characterization of a new pyridinofullerene ligand capable of forming axially symmetric complexes with metalloporphyrins is reported. X-ray structural and molecular modeling studies, (1)H NMR, UV-vis spectroscopy, electrochemistry studies, and fluorescence quenching data support the formation of a strong complex between the new ligand and the metal center of ZnTPP. On the basis of computational studies, the highest occupied molecular orbital (HOMO) of this ligand is significantly different from a model compound with insulating carbons between the pyridine and the fullerene. The N-pyridinium fulleropyrrolidine salts of the new ligand and model compound were also prepared and their spectral and electrochemical properties are reported. PMID:15230581

  17. Ligand-field symmetry effects in Fe(II) polypyridyl compounds probed by transient X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hana; Strader, Matthew L.; Hong, Kiryong; Jamula, Lindsey; Kim, Tae Kyu; Groot, Frank M. F. de; McCusker, James K.; Schoenlein, Robert W.; Huse, Nils

    2012-02-28

    Ultrafast excited-state evolution in polypyridyl FeII complexes are of fundamental interest for understanding the origins of the sub-ps spin-state changes that occur upon photoexcitation of this class of compounds as well as for the potential impact such ultrafast dynamics have on incorporation of these compounds in solar energy conversion schemes or switchable optical storage technologies. We have demonstrated that ground-state and, more importantly, ultrafast time-resolved x-ray absorption methods can offer unique insights into the interplay between electronic and geometric structure that underpin the photo-induced dynamics of this class of compounds. The present contribution examines in greater detail how the symmetry of the ligand field surrounding the metal ion can be probed using these x-ray techniques. In particular, we show that steady-state K-edge spectroscopy of the nearest-neighbour nitrogen atoms reveals the characteristic chemical environment of the respective ligands and suggests an interesting target for future charge-transfer femtosecond and attosecond spectroscopy in the x-ray water window.

  18. Effect of second ligand on the luminescence of Samarium (III) dibenzoylmethane complexes: Syntheses, crystal structures, thermal analysis and luminescence study

    Indian Academy of Sciences (India)

    Muhammad Idiris Saleh; Min Yee Choo; Tai Wei Chan; Mohd R Razali

    2015-12-01

    The ternary complexes of Sm(III) with dibenzoylmethane (dbm) were synthesized by introducing 1,10-phenanthroline (phen), 4,7-dimethyl-1,10-phenanthroline (dmphen), 3,4,7,8-tetramethyl-1,10-phenanthroline (tmphen), 4,7-diphenyl-1,10-phenanthroline (dpphen), 2,2-bipyridyl (bpy), 4,4’-dimethyl-2,2-bipyridyl (4,4-dmbpy), 5,5’-dimethyl-2,2-bipyridyl (5,5-dmbpy) and 4,4’-di-tert-butyl-2,2-bipyridyl (4,4-dtbbpy) as a second ligand. The complexes were isolated and characterized by elemental analysis (CHN), thermogravimetric analysis (TGA), IR spectroscopy, luminescence spectroscopy and single crystal X-ray diffraction. Structural study shows that in all complexes Sm(III) is in square antiprism geometry. All complexes emit strong luminescence under ultraviolet excitation. The strongest emission is at 643 nm which can be assigned for 4G5/2 to 6H9/2 transition, equivalent to energy of 15550 cm−1. The addition of the second ligand has increased the emission intensity of the complexes while the transition is maintained.

  19. Crystal structures of the ligand-binding region of uPARAP: effect of calcium ion binding.

    Science.gov (United States)

    Yuan, Cai; Jürgensen, Henrik J; Engelholm, Lars H; Li, Rui; Liu, Min; Jiang, Longguang; Luo, Zhipu; Behrendt, Niels; Huang, Mingdong

    2016-08-01

    The proteins of the mannose receptor (MR) family share a common domain organization and have a broad range of biological functions. Urokinase plasminogen activator receptor-associated protein (uPARAP) (or Endo180) is a member of this family and plays an important role in extracellular matrix remodelling through interaction with its ligands, including collagens and urokinase plasminogen activator receptor (uPAR). We report the crystal structures of the first four domains of uPARAP (also named the ligand-binding region, LBR) at pH 7.4 in Ca(2+)-bound and Ca(2+)-free forms. The first domain (cysteine-rich or CysR domain) folds into a new and unique conformation different from the β-trefoil fold of typical CysR domains. The so-called long loop regions (LLRs) of the C-type lectin-like domain (CTLD) 1 and 2 (the third and fourth domain) mediate the direct contacts between these domains. These LLRs undergo a Ca(2+)-dependent conformational change, and this is likely to be the key structural determinant affecting the overall conformation of uPARAP. Our results provide a molecular mechanism to support the structural flexibility of uPARAP, and shed light on the structural flexibility of other members of the MR family. PMID:27247422

  20. Axial Shock in a Cylindrical Plasma with Current

    International Nuclear Information System (INIS)

    Hugoniot relations of a two-dimensional axial shock with current and magnetic field in a cylindrical shock tube were investigated by a numerical method. The radial profiles of the magnetic field, electric current, pressures, flow velocities and temperatures between the up- and down-stream radial force-balanced plasma of the shock were revealed by numerical analysis. It is clearly found that the axial shock can lead to two effects: one is an inverse skin effect (i.e., the current density rises towards the center of the conductor), the another is a reversed current effect which occurs near the edge and about a half radius. It is also found that the radial gradient of pressure, density and temperature all become very large near the center due to the axial shock

  1. Rotordynamics of Turbine Labyrinth Seals with Rotor Axial Shifting

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available Rotors in high-performance steam turbines experience a significant axial shifting during starting and stopping processes due to thermal expansion, for example. This axial shifting could significantly alter the flow pattern and the flow-induced rotordynamic forces in labyrinth seals, which in turn, can considerably affect the rotor-seal system performance. This paper investigates the influence of the rotor axial shifting on leakage rate as well as rotordynamic forces in high-low labyrinth seals over a range of seal clearances and inlet swirl velocities. A well-established CFD-perturbation model was employed to predict the rotordynamic coefficients. A surprisingly large effect was detected for rotordynamic characteristics due to rotor shifting. It was also found that a less destabilizing effect arose from rotor axial shifting in the leakage flow direction, whereas a more destabilizing effect arose from shifting against the leakage flow direction. Further, a tentative explanation was proposed for the large sensitivities of dynamic forces to rotor axial shifting.

  2. Rotordynamics of Turbine Labyrinth Seals with Rotor Axial Shifting

    Directory of Open Access Journals (Sweden)

    David L. Rhode

    2006-03-01

    Full Text Available Rotors in high-performance steam turbines experience a significant axial shifting during starting and stopping processes due to thermal expansion, for example. This axial shifting could significantly alter the flow pattern and the flow-induced rotordynamic forces in labyrinth seals, which in turn, can considerably affect the rotor-seal system performance. This paper investigates the influence of the rotor axial shifting on leakage rate as well as rotordynamic forces in high-low labyrinth seals over a range of seal clearances and inlet swirl velocities. A well-established CFD-perturbation model was employed to predict the rotordynamic coefficients. A surprisingly large effect was detected for rotordynamic characteristics due to rotor shifting. It was also found that a less destabilizing effect arose from rotor axial shifting in the leakage flow direction, whereas a more destabilizing effect arose from shifting against the leakage flow direction. Further, a tentative explanation was proposed for the large sensitivities of dynamic forces to rotor axial shifting.

  3. Strange axial-vector mesons

    International Nuclear Information System (INIS)

    The strange axial-vector mesons K1 (1270) and K1 (1400) are reanalyzed in the light of the updated experimental information and compared with the recent result on the Kππ production in τ decay. The mixing angle between the strange mesons of 3P1 and 1P1 is determined by the partial decay rates, and, independently, by the masses. They lead to θK∼33 degree or 57 degree. The observed K1 (1400) production dominance in the τ decay favors θK∼33 degree. Flavor-SU(3) breaking of 20% or so in the production amplitudes can explain quantitatively the observed production ratio

  4. Luminescence, magnetocaloric effect and single-molecule magnet behavior in lanthanide complexes based on a tridentate ligand derived from 8-hydroxyquinoline.

    Science.gov (United States)

    Shen, Hai-Yun; Wang, Wen-Min; Bi, Yan-Xia; Gao, Hong-Ling; Liu, Shuang; Cui, Jian-Zhong

    2015-11-21

    A new family of lanthanide complexes, [Ln2(hfac)4L2] (Ln = Eu (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6), Lu (7); hfac = hexafluoroacetylacetonate, HL = 2-(2′-benzothiazole)-8-hydroxyquinoline), was synthesized and characterized using single-crystal X-ray diffraction, elemental analysis (EA), thermal gravimetric analysis (TGA), powder X-ray diffraction (PXRD) and UV-vis spectra. X-ray crystallographic analyses reveal that 1–7 are isomorphous and crystallize in the monoclinic space group C2/c. In these dinuclear complexes, each LnШ ion is eight-coordinated with two bidentate hfac and two μ-phenol bridging L ligands. The TGA results show that the complexes have relatively high thermal stabilities. Complexes 1 and 3 show the characteristic transitions of the corresponding lanthanide ions with ligand-related emission peaks. Meanwhile, complexes 4 and 7 exhibit ligand-centered fluorescence at room temperature. Magnetic measurements were carried out on complexes 2–6. The magnetic study reveals that 2 displays a magnetocaloric effect, with a maximum −ΔSm value of 16.89 J K−1 kg−1 at 2 K for ΔH = 8 T. Dynamic magnetic studies reveal single-molecule magnet (SMM) behavior for complex 4. Fitting the dynamic magnetic data to the Arrhenius law gives an energy barrier ΔE/kB = 50.33 K and pre-exponential factor τ0 = 1.05 × 10(-8)s. PMID:26466301

  5. 配体对量子点合成影响的发展现状%Development Status on Effect of Ligands on Synthesis of Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    文丹; 喻艳华; 付成; 张玮莹; 张正涛

    2015-01-01

    量子点(quantum dots,QDs)又称纳米晶,具有优良的荧光特性,如一元激发多元发射、抗光漂、斯托克斯位移大、发射光谱可调等。其中发射光谱可以通过改变QDs的元素组成或者粒径大小来控制发光材料的发射光谱范围,且QDs的发光效率高,颜色纯度高。近年来,被更多地应用在显示和照明领域。QDs表面配体对QDs发光效率影响较大,配体可通过影响反应活性,控制QDs的生长速度,从而对其尺寸进行调控。综述了近几年国内外对QDs表面配体的研究现状,不同配体对QDs的成核及生长、形貌、荧光性质和稳定性的影响。%The quantum dots(QDs)have the feature that the emission spectrum can be regulated with particle size ,the emission spectrum scope can be regulated with the element composition or the particle size of QDs ,the luminous efficiency and the color purity are high. In recent years ,QDs are widely ap⁃plied in displaying and luminous domain. The surface ligands can influence the luminous efficiency of QDs ,reviews the recent research status of QDs surface ligands at home and abroad ,and the effects of different ligands on the nucleation ,growth ,shape ,fluorescence properties and stability of QDs.

  6. Effect of space length of mannose ligand on uptake of mannosylated liposome in RAW 264.7 cells: In vitro and in vivo studies.

    Science.gov (United States)

    Jeong, Hwan-Seok; Na, Kyung Sook; Hwang, Hyosook; Oh, Phil-Sun; Kim, Dong Hyun; Lim, Seok Tae; Sohn, Myung-Hee; Jeong, Hwan-Jeong

    2014-12-01

    The most widely used method for increasing uptake on macrophage is specific targeting for mannose receptor (MR) presented on macrophages. Efficiency of the uptake for MR is influenced by the space length and flexibility of mannose ligand in liposome (LP). We prepared mannosylated liposomes (M-EGn-LP-ICG) encapsulated indocyanine green (ICG) with mannose ligand of various ethylene glycol units (EG), LP-ICG, and mannosylated liposome (M-LP-ICG) incorporated with p-aminophenyl-α-d-mannopyranoside. We studied the effect of space length of the mannose ligand in vitro and in vivo with prepared liposomes. A space length of two ethylene glycol units at least was needed for uptake by macrophages and the uptake was increased as the space length increased up to EG4. We measured near-infrared (NIR) fluorescence intensity by ICG and the fluorescence value of cell-associated N-(4-nitrobenzo-2-oxa-1,3-diazole) (NBD) in liposome after cellular uptake. M-EG4-LP-ICG showed lower NIR fluorescence intensity but higher NBD fluorescence value than M-LP-ICG. The result of pre-treatment with d(+)-mannose as an inhibitor showed significant decreasing in uptake of mannosylated LP-ICG but no difference in LP-ICG. These were explained that mannosylated LP-ICG was taken up by macrophages through the MR and M-EG4-LP-ICG showed more specific uptake than M-LP-ICG. We obtained images as time passed in the NIR range after intravenous administration using a Balb/c mouse with inflammatory model. The results showed high uptake in liver at early time and rapid degradation of mannosylated LP-ICG. M-EG4-LP-ICG was more selectively taken up by macrophages than M-LP-ICG. PMID:24677479

  7. Effects of C-reactive protein on the expression of OX40 ligand in mouse aorta endothelial cells

    Institute of Scientific and Technical Information of China (English)

    Fei Wang; Shushu Zhu; Xuefu Han; Jindan Xu; Jinnan Zhang; Di Yang

    2009-01-01

    Objective: To investigate the expression of OX40 ligand(OX40L) on C-reactive protein(CRP)-triggered mouse aorta endothelial cells (MAECs) in vitro. Methods: MAECs from aorta were isolated by digestion with collagenase type Ⅱ. The cell growth was confirmed by morphological characteristics and the immunological marker, factor Ⅷ(or Willebrand factor, vWF). The expression of OX40L by MAECs was detected by RT-PCR and western blot after incubating with 100 μg/ml CRP for 48 hours. Results: Twenty-day cultures of MAECs formed confluent monolayer of a cobblestone pattern. RT-PCR and western blot assay showed that the level of OX40L expression in MAECs receiving CRP treatment was higher than control. Conclusion: A reliable method is described to isolate and propagate MAECs. CRP upregulates OX40L expression in MAECs.

  8. Opposing effects of the anesthetic propofol at pentameric ligand-gated ion channels mediated by a common site

    DEFF Research Database (Denmark)

    Lynagh, Timothy Peter; Laube, Bodo

    2014-01-01

    Propofol is an intravenous general anesthetic that alters neuronal excitability by modulating agonist responses of pentameric ligand-gated ion channels (pLGICs). Evidence suggests that propofol enhancement of anion-selective pLGICs is mediated by a binding site between adjacent subunits, whereas...... propofol inhibition of cation-selective pLGICs occurs via a binding site contained within helices M1-M4 of individual subunits. We considered this idea by testing propofol modulation of homomeric human glycine receptors (GlyRs) and nematode glutamate-gated chloride channels (GluCls) recombinantly expressed...... substitution in the channel-forming M2 helix (EC50 = 979 ± 88 μM). When a previously identified site between adjacent subunits was disrupted by the M3 G329I substitution, both propofol inhibition and enhancement of GluCls were severely impaired (IC50 and EC50 values could not be calculated). Similarly, when...

  9. External anion effect on the synthesis of new MOFs based on formate and a twisted divergent ligands

    Science.gov (United States)

    Lago, Ana Belén; Carballo, Rosa; Lezama, Luis; Vázquez-López, Ezequiel M.

    2015-11-01

    New copper(II) metal-organic compounds with the formulae [Cu3Cl(HCO2)5(SCS)3(H2O)2]·8H2O·EtOH (1) and [Cu3(HCO2)4(SCS)4(H2O)2](NO3)2·9H2O (2) (SCS=bis(4-pyridylthio)methane) have been synthesized after a careful study of the reaction of the SCS ligand with copper(II) formate. The compounds were obtained in the presence of sodium chloride and nitrate salts under microwave irradiation. The influence of the anion at different metal/anion ratios on the final architecture has been studied. The new chloride-MOF 1 has been characterized by electron paramagnetic resonance (EPR), magnetic properties and single crystal X-ray diffraction studies. The thermal stability and topological analysis have also been investigated.

  10. Axial vessel widening in arborescent monocots.

    Science.gov (United States)

    Petit, Giai; DeClerck, Fabrice A J; Carrer, Marco; Anfodillo, Tommaso

    2014-02-01

    Dicotyledons have evolved a strategy to compensate for the increase in hydraulic resistance to water transport with height growth by widening xylem conduits downwards. In monocots, the accumulation of hydraulic resistance with height should be similar, but the absence of secondary growth represents a strong limitation for the maintenance of xylem hydraulic efficiency during ontogeny. The hydraulic architecture of monocots has been studied but it is unclear how monocots arrange their axial vascular structure during ontogeny to compensate for increases in height. We measured the vessel lumina and estimated the hydraulic diameter (Dh) at different heights along the stem of two arborescent monocots, Bactris gasipaes (Kunth) and Guadua angustifolia (Kunth). For the former, we also estimated the variation in Dh along the leaf rachis. Hydraulic diameter increased basally from the stem apex to the base with a scaling exponent (b) in the range of those reported for dicot trees (b = 0.22 in B. gasipaes; b = 0.31 and 0.23 in G. angustifolia). In B. gasipaes, vessels decrease in Dh from the stem's centre towards the periphery, an opposite pattern compared with dicot trees. Along the leaf rachis, a pattern of increasing Dh basally was also found (b = 0.13). The hydraulic design of the monocots studied revealed an axial pattern of xylem conduits similar to those evolved by dicots to compensate and minimize the negative effect of root-to-leaf length on hydrodynamic resistance to water flow. PMID:24488857

  11. Toward Quantitatively Accurate Calculation of the Redox-Associated Acid-Base and Ligand Binding Equilibria of Aquacobalamin.

    Science.gov (United States)

    Johnston, Ryne C; Zhou, Jing; Smith, Jeremy C; Parks, Jerry M

    2016-08-01

    Redox processes in complex transition metal-containing species are often intimately associated with changes in ligand protonation states and metal coordination number. A major challenge is therefore to develop consistent computational approaches for computing pH-dependent redox and ligand dissociation properties of organometallic species. Reduction of the Co center in the vitamin B12 derivative aquacobalamin can be accompanied by ligand dissociation, protonation, or both, making these properties difficult to compute accurately. We examine this challenge here by using density functional theory and continuum solvation to compute Co-ligand binding equilibrium constants (Kon/off), pKas, and reduction potentials for models of aquacobalamin in aqueous solution. We consider two models for cobalamin ligand coordination: the first follows the hexa, penta, tetra coordination scheme for Co(III), Co(II), and Co(I) species, respectively, and the second model features saturation of each vacant axial coordination site on Co(II) and Co(I) species with a single, explicit water molecule to maintain six directly interacting ligands or water molecules in each oxidation state. Comparing these two coordination schemes in combination with five dispersion-corrected density functionals, we find that the accuracy of the computed properties is largely independent of the scheme used, but including only a continuum representation of the solvent yields marginally better results than saturating the first solvation shell around Co throughout. PBE performs best, displaying balanced accuracy and superior performance overall, with RMS errors of 80 mV for seven reduction potentials, 2.0 log units for five pKas and 2.3 log units for two log Kon/off values for the aquacobalamin system. Furthermore, we find that the BP86 functional commonly used in corrinoid studies suffers from erratic behavior and inaccurate descriptions of Co-axial ligand binding, leading to substantial errors in predicted pKas and

  12. Study on the effects of complex ligands in the synthesis of TiO{sub 2} nanorod arrays using the sol-gel template method

    Energy Technology Data Exchange (ETDEWEB)

    Attar, A Sadeghzadeh; Mirdamadi, Sh [Department of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Ghamsari, M Sasani; Hajiesmaeilbaigi, F [Solid State Lasers Research Group, Laser and Optics Research School, Tehran 11365-8486 (Iran, Islamic Republic of); Katagiri, K; Koumoto, K [Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan)], E-mail: mirdamadi@iust.ac.ir

    2008-08-07

    This work reports the effects of complex ligands on the synthesis of TiO{sub 2} nanorod arrays prepared by the improved sol-gel template method. In this method, the obtained TiO{sub 2} sols from the sol-gel process were injected by a syringe into the templates and then the samples were immediately immersed into boiling TiO{sub 2}-sol solutions. Densely and directionally aligned anatase nanorods of about 80-130 nm diameter and a length of several micrometres were successfully fabricated using an optimal molar ratio of the TiO{sub 2} sol. The results show that the molar ratio of the TiO{sub 2} sol plays an important role in the morphology and structure of TiO{sub 2} nanorods. The reaction between titanium alkoxide and acetylacetone leads to the formation of complex compounds, which can prevent the precipitation of undesired phases from the highly reactive precursors. These complex ligands can be removed after annealing at various temperatures, which depend on the molar ratio of the TiO{sub 2} sol.

  13. Nonlinear Model and Qualitative Analysis for Coupled Axial/Torsional Vibrations of Drill String

    OpenAIRE

    Fushen Ren; Baojin Wang; Suli Chen; Zhigang Yao; Baojun Bai

    2016-01-01

    A nonlinear dynamics model and qualitative analysis are presented to study the key effective factors for coupled axial/torsional vibrations of a drill string, which is described as a simplified, equivalent, flexible shell under axial rotation. Here, after dimensionless processing, the mathematical models are obtained accounting for the coupling of axial and torsional vibrations using the nonlinear dynamics qualitative method, in which excitation loads and boundary conditions of the drill stri...

  14. The Dynamics of Stall and Surge Behavior in Axial-Centrifugal Compressors

    OpenAIRE

    Cousins, William T.

    1997-01-01

    The phenomena of stall and surge in axial-centrifugal compressors is investigated through high-response measurements of both the pressure field and the flowfield throughout the surge cycle. A unique high-response forward-facing and aft-facing probe provides flow information. Several axial-centrifugal compressors are examined, both in compressor rigs and engines. Extensive discussion is presented on the differences in axial and centrifugal rotors and their effect on the system response char...

  15. Axial Vector $Z'$ and Anomaly Cancellation

    CERN Document Server

    Ismail, Ahmed; Tsao, Kuo-Hsing; Unwin, James

    2016-01-01

    Whilst the prospect of new $Z'$ gauge bosons with only axial couplings to the Standard Model (SM) fermions is widely discussed, examples of anomaly-free renormalisable models are lacking in the literature. We look to remedy this by constructing several motivated examples. Specifically, we consider axial vectors which couple universally to all SM fermions, as well as those which are generation-specific, leptophilic, and leptophobic. Anomaly cancellation typically requires the presence of new coloured and charged chiral fermions, and we argue that the masses of these new states must generally be comparable to that of the axial vector. Finally, an axial vector mediator could provide a portal between SM and hidden sector states, and we also consider the possibility that the axial vector couples to dark matter. If the dark matter relic density is set due to freeze-out via the axial vector, this strongly constrains the parameter space.

  16. Method to measure tone of axial and proximal muscle.

    Science.gov (United States)

    Gurfinkel, Victor S; Cacciatore, Timothy W; Cordo, Paul J; Horak, Fay B

    2011-01-01

    The control of tonic muscular activity remains poorly understood. While abnormal tone is commonly assessed clinically by measuring the passive resistance of relaxed limbs, no systems are available to study tonic muscle control in a natural, active state of antigravity support. We have developed a device (Twister) to study tonic regulation of axial and proximal muscles during active postural maintenance (i.e. postural tone). Twister rotates axial body regions relative to each other about the vertical axis during stance, so as to twist the neck, trunk or hip regions. This twisting imposes length changes on axial muscles without changing the body's relationship to gravity. Because Twister does not provide postural support, tone must be regulated to counteract gravitational torques. We quantify this tonic regulation by the restive torque to twisting, which reflects the state of all muscles undergoing length changes, as well as by electromyography of relevant muscles. Because tone is characterized by long-lasting low-level muscle activity, tonic control is studied with slow movements that produce "tonic" changes in muscle length, without evoking fast "phasic" responses. Twister can be reconfigured to study various aspects of muscle tone, such as co-contraction, tonic modulation to postural changes, tonic interactions across body segments, as well as perceptual thresholds to slow axial rotation. Twister can also be used to provide a quantitative measurement of the effects of disease on axial and proximal postural tone and assess the efficacy of intervention. PMID:22214974

  17. LigandRFs: random forest ensemble to identify ligand-binding residues from sequence information alone

    KAUST Repository

    Chen, Peng

    2014-12-03

    Background Protein-ligand binding is important for some proteins to perform their functions. Protein-ligand binding sites are the residues of proteins that physically bind to ligands. Despite of the recent advances in computational prediction for protein-ligand binding sites, the state-of-the-art methods search for similar, known structures of the query and predict the binding sites based on the solved structures. However, such structural information is not commonly available. Results In this paper, we propose a sequence-based approach to identify protein-ligand binding residues. We propose a combination technique to reduce the effects of different sliding residue windows in the process of encoding input feature vectors. Moreover, due to the highly imbalanced samples between the ligand-binding sites and non ligand-binding sites, we construct several balanced data sets, for each of which a random forest (RF)-based classifier is trained. The ensemble of these RF classifiers forms a sequence-based protein-ligand binding site predictor. Conclusions Experimental results on CASP9 and CASP8 data sets demonstrate that our method compares favorably with the state-of-the-art protein-ligand binding site prediction methods.

  18. Fully Flexible Docking of Medium Sized Ligand Libraries with RosettaLigand

    Science.gov (United States)

    DeLuca, Samuel; Khar, Karen; Meiler, Jens

    2015-01-01

    RosettaLigand has been successfully used to predict binding poses in protein-small molecule complexes. However, the RosettaLigand docking protocol is comparatively slow in identifying an initial starting pose for the small molecule (ligand) making it unfeasible for use in virtual High Throughput Screening (vHTS). To overcome this limitation, we developed a new sampling approach for placing the ligand in the protein binding site during the initial ‘low-resolution’ docking step. It combines the translational and rotational adjustments to the ligand pose in a single transformation step. The new algorithm is both more accurate and more time-efficient. The docking success rate is improved by 10–15% in a benchmark set of 43 protein/ligand complexes, reducing the number of models that typically need to be generated from 1000 to 150. The average time to generate a model is reduced from 50 seconds to 10 seconds. As a result we observe an effective 30-fold speed increase, making RosettaLigand appropriate for docking medium sized ligand libraries. We demonstrate that this improved initial placement of the ligand is critical for successful prediction of an accurate binding position in the ‘high-resolution’ full atom refinement step. PMID:26207742

  19. Effects of ligand substitution on the excited state dynamics of the Ru(dcbpy)(CO)2I2 complex

    International Nuclear Information System (INIS)

    Spectroscopic evidence suggest [PCCP 3 (2001) 1992] that illumination with visible light of the [trans-I-Ru(dcbpy)(CO)2I2] (dcbpy4,4'-dicarboxy-2,2'-bipyridine) complex in solution induces dissociation of a CO group followed by reorganization of the ligands and attachment of a solvent molecule. In the present study, we report results on excited state dynamics of this ruthenium complex and its photoproduct. Femtosecond transient absorption measurements reveal dominance of excited state absorption of the reactant and the photoproduct [cis-I-Ru(dcbpy)(CO)(Sol)I2] (Sol=ethanol or acetonitrile) in the visible spectral region. The time-resolved measurements for the reactant at 77 K indicate interligand charge transfer from mixed Ru-I states to empty dcbpy orbitals. For the photoproduct, no such transfer was observed. In both complexes recovery from the lowest energy excited triplet state to the ground state occurs via two channels: radiative relaxation and a parallel barrier controlled non-radiative relaxation. The barrier is much higher in the reactant (about 850 cm-1) than in the product. A combination of DFT and ZINDO/CI calculations was used to estimate excited singlet and triplet spectra of the reactant and the product molecules. Calculated singlet-triplet difference spectra qualitatively match the observed transient spectra 500 fs after excitation supporting the idea that observed excited state relaxation occurs from the triplet states in both complexes

  20. Anti-analgesic effect of the mu/delta opioid receptor heteromer revealed by ligand-biased antagonism.

    Directory of Open Access Journals (Sweden)

    Laura Milan-Lobo

    Full Text Available Delta (DOR and mu opioid receptors (MOR can complex as heteromers, conferring functional properties in agonist binding, signaling and trafficking that can differ markedly from their homomeric counterparts. Because of these differences, DOR/MOR heteromers may be a novel therapeutic target in the treatment of pain. However, there are currently no ligands selective for DOR/MOR heteromers, and, consequently, their role in nociception remains unknown. In this study, we used a pharmacological opioid cocktail that selectively activates and stabilizes the DOR/MOR heteromer at the cell surface by blocking its endocytosis to assess its role in antinociception. We found that mice treated chronically with this drug cocktail showed a significant right shift in the ED50 for opioid-mediated analgesia, while mice treated with a drug that promotes degradation of the heteromer did not. Furthermore, promoting degradation of the DOR/MOR heteromer after the right shift in the ED50 had occurred, or blocking signal transduction from the stabilized DOR/MOR heteromer, shifted the ED50 for analgesia back to the left. Taken together, these data suggest an anti-analgesic role for the DOR/MOR heteromer in pain. In conclusion, antagonists selective for DOR/MOR heteromer could provide an avenue for alleviating reduced analgesic response during chronic pain treatment.

  1. Forced convection in a circular duct with periodic boundary conditions and axial heat conduction

    Energy Technology Data Exchange (ETDEWEB)

    Barletta, A.; Rossi di Schio, E. [Bologna Univ., Bologna (Italy). Dipt. di Ingegneria Energetica, Nucleare e del Controllo Ambientale

    2000-07-01

    An investigation of the effect of axial heat conduction in the fluid on laminar forced convection is performed in a cylindrical duct with circular cross section. Two different kinds of boundary conditions are analysed: 1, a wall temperature distribution which undergoes a sinusoidal axial variation; 2, a wall heat flux distribution which undergoes a sinusoidal axial variation and such that its mean value is equal to the modulus of the amplitude. Reference is made to the hydrodynamical and thermally developed region, where the temperature distribution is given in case 1 by an axially periodic function and in case 2 by the sum of an axially periodic function and a linear function of the axial coordinate. The temperature distribution within the fluid and the local and mean Nusselt have been evaluated analytically.

  2. The Szilard-Chalmers effect in macrocyclic ligands to increase the specific activity of reactor-produced radiolanthanides. Experiments and explanations

    Energy Technology Data Exchange (ETDEWEB)

    Zhernosekov, K.P.; Roesch, F. [Mainz Univ. (Germany). Inst. of Nuclear Chemistry; Filosofov, D.V. [Laboratory of Nuclear Problems, Dubna (Russian Federation). Joint Inst. of Nuclear Research

    2012-07-01

    Successful utilization of medical isotopes in the radiolabeling reactions to a significant degree depends on the technically achievable specific activity. In this respect, the Szilard-Chalmers effect is considered in detail as a radiochemical tool to increase the specific activity of radionuclides produced by direct nuclear reactions. In the present study, a physico-chemical model is described utilizing the specific aspects of thermodynamically and kinetically stabilised metal-ligand complexes. The approach is applied as a proof-of-principle study to increase the specific activity of {sup 166}Ho, produced via the (n,{gamma}) nuclear reaction. As a target material, {sup 165}Ho-DOTA is used. In this case, {sup 166}Ho, the product nucleus of the neutron capture reaction, is obtained chemically as non-complexed cationic {sup 166}Ho{sup III} species in situ. Consequently, it can effectively and quantitatively be separated from the inactive {sup 165}Ho-DOTA target material by means of fast and simple chromatographic, column-based methods. We were able to verify the physico-chemical model by the experimentally obtained data. For the first time we quantitatively describe the interaction of the ligand-framework of the target material (e.g. the Ho-DOTA complex) with the radiation field of the nuclear reactor. The analysis of the experimental data allows to assume that radionuclides with half-lives of T{sub 1/2} < 64 h can be produced at a TRIGA II nuclear reactor via the Szilard-Chalmers effect with specific activities higher than in the case of direct irradiation of common target materials such as oxides. (orig.)

  3. Liquid Axial Mixing in Packed Tower at Elevated Pressure

    Institute of Scientific and Technical Information of China (English)

    唐忠利; 张鹏; 等

    2003-01-01

    Liquid phase axial mixing was measured with the tracer technique in a packed column with inner diameter of 0.15m,in which the structured packing,Mellapak 350Y,was installed.Tap water as the liquid phase flowed down through the column and stagnant gas was at elevated pressure ranging from atmospheric to 2.0MPa.The model parameters of Bo andθwere estimated with the least square method in the time domain.As liquid flow rate was increased,the liquid axial mixing decreased.under our experimental conditions,the effect of pressure on Bo number on single liquid phase was negligible,and eddy diffusion was believed to be the primary cause of axial mixing in liquid phase.

  4. Numerical analysis of cavitation within slanted axial-flow pump

    Institute of Scientific and Technical Information of China (English)

    张睿; 陈红勋

    2013-01-01

    In this paper, the cavitating flow within a slanted axial-flow pump is numerically researched. The hydraulic and cavitation performance of the slanted axial-flow pump under different operation conditions are estimated. Compared with the experimental hydraulic performance curves, the numerical results show that the filter-based model is better than the standard k-e model to predict the parameters of hydraulic performance. In cavitation simulation, compared with the experimental results, the proposed numerical method has good predicting ability. Under different cavitation conditions, the internal cavitating flow fields within slanted axial-flow pump are investigated. Compared with flow visualization results, the major internal flow features can be effectively grasped. In order to explore the origin of the cavitation performance breakdown, the Boundary Vorticity Flux (BVF) is introduced to diagnose the cavitating flow fields. The analysis results indicate that the cavitation performance drop is relevant to the instability of cavitating flow on the blade suction surface.

  5. Optimum axial flow taper in a countercurrent gas centrifuge

    Energy Technology Data Exchange (ETDEWEB)

    Von Halle, E.

    1979-02-01

    The effect of an axially varying countercurrent circulation rate in a gas centrifuge on the efficiency factors, e/sub I/, the ideality efficiency, and e/sub C/, the circulation efficiency, is investigated and compared with the case in which the countercurrent circulation rate is constant throughout the centrifuge. The optimum variation of the centrifuge parameter m, which is a measure of the countercurrent circulation rate, as a function of axial position in the centrifuge is determined. It is shown that when the countercurrent circulation rate has its optimum value at every axial position in the centrifuge, the product of the efficiency factors, e/sub I/ x e/sub C/, can exceed 81 per cent, the nominal upper limit of the value of the product of the efficiency factors for a constant countercurrent circulation rate, and can be quite close to unity. This is illustrated by numerical examples based on a centrifuge previously described in the literature.

  6. A simple approach to the ABJ axial anomaly

    International Nuclear Information System (INIS)

    A very simple semi-quantitative derivation of the Adler-Bell-Jackiw (ABJ) axial anomaly is given, based on an investigation of the absorptive part of the VVA triangle graph and dispersion relations. Essential ingredients of our discussion are: normal Ward identities for the absorptive part of the relevant diagram, dimensional analysis, unitarity, and energy-momentum conservation. An explanation of the physical origin of axial anomaly, proposed in some earlier treatments within such a dispersive framework, is critically examined. In particular, the interpretation of the ABJ anomaly as an analogy of the Lee-Nauenberg effect occurring in the massless limit of spinor electrodynamics is shown to be fallacious

  7. Axial-symmetrical domain structures in ferrite-garnet films

    International Nuclear Information System (INIS)

    Applying the improved technique of double ultrahigh-speed photography one studied occurrence and progress of domain structure upon magnetization of a small section of (BiLaTm)3(FeGa)5O12 ferrite-garnet film prior to saturation. The radial deformation affecting the specimen on the magnetized coil side was determined to break single-axis anisotropy resulting in occurrence of axial-oriented band domain structure inside the magnetized range. That structure period reduced with growth of the pulse field amplitude. Band axial-oriented domain structure is formed under the effect of the magnetostatic axisymmetric field

  8. Vector and axial currents in Wilson chiral perturbation theory

    International Nuclear Information System (INIS)

    We reconsider the construction of the vector and axial-vector currents in Wilson Chiral Perturbation Theory, the low-energy effective theory for lattice QCD with Wilson fermions. We discuss in detail the finite renormalization of the currents that has to be taken into account in order to properly match the currents. We explicitly show that imposing the chiral Ward identities on the currents does, in general, affect the axial-vector current at O(a). As an application of our results we compute the pion decay constant to one loop in the two-flavor theory. Our result differs from previously published ones.

  9. Instability of Meridional Axial System in f(R) Gravity

    CERN Document Server

    Sharif, M

    2015-01-01

    We analyze dynamical instability of non-static reflection axial stellar structure by taking into account generalized Euler's equation in metric $f(R)$ gravity. Such an equation is obtained by contracting Bianchi identities of usual anisotropic and effective stress-energy tensors, which after using radial perturbation technique gives modified collapse equation. In the realm of $R+\\epsilon R^n$ gravity model, we investigate instability constraints at Newtonian and post-Newtonian approximations. We find that instability of meridional axial self-gravitating system depends upon static profile of structure coefficients while $f(R)$ extra curvature terms induce stability to the evolving celestial body.

  10. Mixed ligand oxovanadium(IV) complexes with salicylic acid and N,N-bidentate ligands

    International Nuclear Information System (INIS)

    Two mixed-ligand oxovanadium(IV) complexes VO(A)(B) [where H2A=salicylic acid and B=2,2'-bipyridine or 1,10-phenanthroline (hereafter, bipy and phen respectively)] have been synthesized and characterized by magnetic moment and spectral (IR, UV/VIS and EPR) data. The A2- ion acts as a bidentate dinegative ligand while B ligands acts as a neutral bidentate. The magnetic susceptibility values indicate the existence of a small amount of antiferromagnetic interaction. The vanadium atoms in the complexes are hexacoordinated and the coordination sphere is of the type [VO(OO)(NN)], where O atoms are of oxo, carboxylic and phenolic type and N atoms are of pyridine type. The sixth coordination site is occupied by phenolic oxygen of the neighbouring molecule forming a bridge. The vv=o confirms the hexacoordination. All the complexes have dxy1 type axial EPR spectra and they exhibit two ligand field transitions at 740 and 440 nm. (author)

  11. Axial dispersion in packed bed reactors involving viscoinelastic and viscoelastic non-Newtonian fluids.

    Science.gov (United States)

    Gupta, Renu; Bansal, Ajay

    2013-08-01

    Axial dispersion is an important parameter in the performance of packed bed reactors. A lot of fluids exhibit non-Newtonian behaviour but the effect of rheological parameters on axial dispersion is not available in literature. The effect of rheology on axial dispersion has been analysed for viscoinelastic and viscoelastic non-Newtonian fluids. Aqueous solutions of carboxymethyl cellulose and polyacrylamide have been chosen to represent viscoinelastic and viscoelastic liquid-phases. Axial dispersion has been measured in terms of BoL number. The single parameter axial dispersion model has been applied to analyse RTD response curve. The BoL numbers were observed to increase with increase in liquid flow rate and consistency index 'K' for viscoinelastic as well as viscoelastic fluids. Bodenstein correlation for Newtonian fluids proposed has been modified to account for the effect of fluid rheology. Further, Weissenberg number is introduced to quantify the effect of viscoelasticity. PMID:23138641

  12. Chemistry of Marine Ligands and Siderophores

    OpenAIRE

    Vraspir, Julia M.; Butler, Alison

    2009-01-01

    Marine microorganisms are presented with unique challenges to obtain essential metal ions required to survive and thrive in the ocean. The production of organic ligands to complex transition metal ions is one strategy to both facilitate uptake of specific metals, such as iron, and to mitigate the potential toxic effects of other metal ions, such as copper. A number of important trace metal ions are complexed by organic ligands in seawater, including iron, cobalt, nickel, copper, zinc, and cad...

  13. Tumor targeting via integrin ligands

    Directory of Open Access Journals (Sweden)

    HorstKessler

    2013-08-01

    Full Text Available Selective and targeted delivery of drugs to tumors is a major challenge for an effective cancer therapy and also to overcome the side effects associated with current treatments. Overexpression of various receptors on tumor cells is a characteristic structural and biochemical aspect of tumors and distinguishes them from physiologically normal cells. This abnormal feature is therefore suitable for selectively directing anticancer molecules to tumors by using ligands that can preferentially recognize such receptors. Several subtypes of integrin receptors that are crucial for cell adhesion, cell signaling, cell viability and motility have been shown to have an upregulated expression on cancer cells. Thus, ligands that recognize specific integrin subtypes represent excellent candidates to be conjugated to drugs or drug carrier systems and be targeted to tumors. In this regard, integrins recognizing the RGD cell adhesive sequence have been extensively targeted for tumor specific drug delivery. Here we review key recent examples on the presentation of RGD-based integrin ligands by means of distinct drug delivery systems, and discuss the prospects of such therapies to specifically target tumor cells.

  14. Acyl-CoA esters antagonize the effects of ligands on peroxisome proliferator-activated receptor alpha conformation, DNA binding, and interaction with Co-factors

    DEFF Research Database (Denmark)

    Elholm, M; Dam, I; Jorgensen, C;

    2001-01-01

    The peroxisome proliferator-activated receptor alpha (PPARalpha) is a ligand-activated transcription factor and a key regulator of lipid homeostasis. Numerous fatty acids and eicosanoids serve as ligands and activators for PPARalpha. Here we demonstrate that S-hexadecyl-CoA, a nonhydrolyzable...

  15. Metal, bond energy, and ancillary ligand effects on actinide-carbon σ-bond hydrogenolysis. A kinetic and mechanistic study

    International Nuclear Information System (INIS)

    A kineticmechanistic study of actinide hydrocarbyl ligand hydrogenolysis (An-R + H2 → An-H + RH) is reported. For the complex Cp'2TH(CH2-t-Bu)(O-t-Bu)(Cp' = eta5-Me5C5), the rate law is first-order in organoactinide and first-order in H2, with k/sub H2/k/sub D2/ = 2.5 (4) and k/sub THF/k/sub toluene/ = 2.9 (4). For a series of complexes, hydrogenolysis rates span a range of ca. 105 with Cp'2ThCH2C(CH3)2CH2 ≅ Cp'2U(CH2-t-Bu) (too rapid to measure accurately) > Cp'2Th(CH2-t-Bu)[OCH(t-Bu)2] = Cp'2Th(CH2-t-Bu)(O-t-Bu) > Cp'2Th(CH2-t-Bu)(Cl) > Me2Si(Me4C5)2Th(n-Bu)2 > Cp'2Th(n-Bu)2 ≅ Cp'2ThMe2 > Cp'2Th(Me)(O3SCF3) > Cp'2Th(n-Bu)[OCG(t-Bu)2] ≅ Cp'2Th(Me)[OSiMe2(t-Bu)] > Cp'2ZrMe2 = Cp'2Th(rho-C6H4NMe2)(O-tu-Bu) > Cp'2Th(Ph)(O-t-Bu) > Cp'2U(Me)[OCH(t-Bu)2] > Cp'2Th(Me)[OCH(t-Bu)2]. In the majority of cases, the rate law is cleanly first-order in organoactinide over 3 or more half-lives. However, for Cp'2ThMe2 → (Cp'2ThH2)2, an intermediate is observe by NMR that is probably [Cp'2Th(Me)(μ-H)]2. For Cp'2Th(Me)(O3SCF3), a follow-up reaction, which consumes Cp'2TH(H)(O3SCF3) is detected. Variable-temperature kinetic studies yield ΔH** = 3.7 (2) kcalmol and ΔS double dagger = -50.8 (7) eu for Cp'2Th(CH2-t-Bu)(O-t-Bu) and ΔH double dagger = 9 (2) kcalmol and ΔS double dagger = -45 (5) eu for Cp'2U(Me)[OCH(O-t-Bu)2

  16. Development of the terrestrial biotic ligand model for predicting nickel toxicity to barley (Hordeum vulgare): ion effects at low pH.

    Science.gov (United States)

    Antunes, Paula M C; Kreager, Nancy J

    2009-08-01

    The focus of the present study was to investigate the potential for Al3+, Mg2+, and H+ to influence Ni2+ toxicity for barley seedlings grown in acidic aqueous solutions and to assess the capacity of a two-site terrestrial biotic ligand model (tBLM) to accurately predict 50% effect activities (EA50s). To accomplish these objectives, 48-h EA50Ni2+ values were obtained for three sets of exposures in which the pH and activity of Al3+ and Mg2+ were varied. Exposures contained both Al alone and in combination with Mg so that compound ion effects could be investigated. A tBLM was then constructed to predict EA50Ni2+ values from the exposure solution chemistry. The results show a slight protective effect of H+ against Ni2+ toxicity and a strong protective effect of Mg2+, as indicated by a 4.6- and 8.0-fold increase in the measured EA50Ni2+ values corresponding to changes in pH from 6.0 to 4.5 and {Mg2+} from 0 to 1.40 mM, respectively. Increasing solution {Al3+} from 0 to 0.5 microM had no effect on Ni2+ toxicity, although Al itself negatively affected root elongation. Comparison of EA50 values calculated as both Ni2+ and measured concentration of total Ni in the root ([Root-Ni]T) showed [Root-Ni]T to be a more normalized measure of Ni bioavailability. The strong correlation between root growth inhibition and tBLM-predicted root-Ni accumulation suggests that toxicity was influenced by Ni2+ binding to low-affinity ligands within the cell wall, in addition to Ni2+ uptake through Mg2+ transporters. Predicted EA50Ni2+ values generated with the model were all within a factor of +/-1.5 from measured values--a result that emphasizes the advantage of using the tBLM for risk assessment. PMID:19374472

  17. Observing the Transition from Equatorial to Axial CO Chemisorption: Infrared Photodissociation Spectroscopy of Yttrium Oxide-Carbonyls.

    Science.gov (United States)

    Xie, Hua; Liu, Zhiling; Zhao, Zhi; Kong, Xiangtao; Fan, Hongjun; Tang, Zichao; Jiang, Ling

    2016-06-01

    A series of yttrium oxide-carbonyls are prepared via a laser vaporization supersonic cluster source in the gas phase and identified by mass-selected infrared photodissociation (IRPD) spectroscopy in the C-O stretching region and by comparing the observed IR spectra with those from quantum chemical calculations. For YO(CO)4(+), all four CO ligands prefer to occupy the equatorial site of the YO(+) unit, leading to a quadrangular pyramid with C4v symmetry. Two energetically nearly degenerate isomers are responsible for YO(CO)5(+), in which the fifth CO ligand is either inserted into the equatorial plane of YO(CO)4(+) or coordinated opposite the oxygen on the C4 axis. YO(CO)6(+) has a pentagonal bipyramidal structure with C5v symmetry, which includes five equatorial CO ligands and one axial CO ligand. The present IRPD spectroscopic and theoretical study of YO(CO)n(+) extends the first shell coordination number of CO ligands in metal monoxide carbonyls to six. The transition from equatorial to axial CO chemisorption in these yttrium oxide-carbonyls is fortunately observed at n = 5, providing new insight into ligand interactions and coordination for the transition metal oxides. PMID:27158889

  18. Effect of aluminum closed-cell foam filling on the quasi-static axial crush performance of glass fiber reinforced polyester composite and aluminum/composite hybrid tubes

    OpenAIRE

    Güden, Mustafa; YÜKSEL, Sinan; Taşdemirci, Alper; Tanoğlu, Metin

    2007-01-01

    The effect of Al closed-cell foam filling on the quasi-static crushing behavior of an E-glass woven fabric polyester composite tube and thin-walled Al/polyester composite hybrid tube was experimentally investigated. For comparison, empty Al, empty composite and empty hybrid tubes were also tested. Empty composite and empty hybrid tubes crushed predominantly in progressive crushing mode, without applying any triggering mechanism. Foam filling was found to be ineffective in increasing the crush...

  19. Effect of Common Buffers and Heterocyclic Ligands on the Binding of Cu(II at the Multimetal Binding Site in Human Serum Albumin

    Directory of Open Access Journals (Sweden)

    Magdalena Sokołowska

    2010-01-01

    Full Text Available Visible-range circular dichroism titrations were used to study Cu(II binding properties of Multimetal Binding Site (MBS of Human Serum Albumin (HSA. The formation of ternary MBS-Cu(II-Buffer complexes at pH 7.4 was positively verified for sodium phosphate, Tris, and Hepes, the three most common biochemical buffers. The phosphate > Hepes > Tris order of affinities, together with strong spectral changes induced specifically by Tris, indicates the presence of both Buffer-Cu(II and Buffer-HSA interactions. All complexes are strong enough to yield a nearly 100% ternary complex formation in 0.5 mM HSA dissolved in 100 mM solutions of respective buffers. The effects of warfarin and ibuprofen, specific ligands of hydrophobic pockets I and II in HSA on the Cu(II binding to MBS were also investigated. The effects of ibuprofen were negligible, but warfarin diminished the MBS affinity for Cu(II by a factor of 20, as a result of indirect conformational effects. These results indicate that metal binding properties of MBS can be modulated directly and indirectly by small molecules.

  20. Axial force measurement for esophageal function testing.

    Science.gov (United States)

    Gravesen, Flemming H; Funch-Jensen, Peter; Gregersen, Hans; Drewes, Asbjørn Mohr

    2009-01-14

    The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method. PMID:19132762

  1. Axial force measurement for esophageal function testing

    Institute of Scientific and Technical Information of China (English)

    Flemming H Gravesen; Peter Funch-Jensen; Hans Gregersen; Asbjφrn Mohr Drewes

    2009-01-01

    The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the "golden standard" for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.

  2. Improvement of the axial diffusion solver of DeCART employing 1-D transport solution

    International Nuclear Information System (INIS)

    Instead of the 3-D transport equation, DeCART solves a transverse leakage coupled radial transport and axial diffusion equations to obtain an approximate 3-D transport solution. In this paper, two of the approximations contained in DeCART related with diffusion constants and cell homogenization are exmained, and practical improvement schemes are suggested. To overcome the diffusion approximation used in the axial direction, a current conservation scheme based on the axial 1-D transport solution is introduced. To overcome the cell homogenization effect, a plane height refinement scheme is employed near the axial core/reflector boundary where homogenization constants vary significantly in the axial direction within the plane. These schemes are evaluated by solving the 3-D VENUS-2 MOX core benchmark. The current conservation and plane height refinement schemes bring about 280 pcm and 100 pcm improvement in k-eff, respectively, and about 390 pcm in total, but trivial effects in the power distribution

  3. Oxovanadium (2) complexes with monothiophosphate ligands from the data of ESR

    International Nuclear Information System (INIS)

    Complexes of the composition VO (mtp)3 (2) and VO (MTP)2 (1), where mtp=monothiophosphate-ion in toluene solution, were identified by the ESR method. Complex 1 has a plane structure with VO2S2 coordination unit. It is assumed that complex 2 has the structure with one of the ligands bound in a bidentate way via S and 0 atoms, which is similar to the plane one. Two other ligands are bound in monodentate way via S and O atoms and coordination atoms of the ligands are weakly coordinated into axial positions

  4. Synthesis and characterization of an iron complex bearing a cyclic tetra-N-heterocyclic carbene ligand: An artifical heme analogue?

    KAUST Repository

    Anneser, Markus R.

    2015-04-20

    An iron(II) complex with a cyclic tetradentate ligand containing four N-heterocyclic carbenes was synthesized and characterized by means of NMR and IR spectroscopies, as well as by single-crystal X-ray structure analysis. The iron center exhibits an octahedral coordination geometry with two acetonitrile ligands in axial positions, showing structural analogies with porphyrine-ligated iron complexes. The acetonitrile ligands can readily be substituted by other ligands, for instance, dimethyl sulfoxide, carbon monoxide, and nitric oxide. Cyclic voltammetry was used to examine the electronic properties of the synthesized compounds. © 2015 American Chemical Society.

  5. Effects of the Imidazoline Binding Site Ligands, Idazoxan and Efaroxan, on the Viability of Insulin-Secreting BRIN-BD11 Cells

    Directory of Open Access Journals (Sweden)

    Gao H

    2003-05-01

    Full Text Available CONTEXT: Certain imidazoline drugs stimulate insulin secretion acutely but their longer term effects on the viability of pancreatic beta-cells are less well characterised. Indeed, some reports have suggested that imidazolines can be toxic to beta-cells while others have reported protective effects against other cytotoxic agents. OBJECTIVE: In order to address these discrepancies, the effects of two structurally related imidazolines, efaroxan and idazoxan, on the viability of clonal BRIN-BD11 beta-cells, were compared. DESIGN AND MAIN OUTCOME MEASURES: BRIN-BD11 cells were exposed to test reagents and their viability monitored by measuring cellular reducing ability and DNA fragmentation. Nitric oxide was measured indirectly via medium nitrite formation. RESULTS: Efaroxan (up to 100 micro M did not directly affect BRIN-BD11 cell viability in the absence of other agents and it did not protect these cells against the cytotoxic effects of interleukin-1beta. Indeed, analysis of DNA fragmentation in BRIN-BD11 cells revealed that efaroxan enhanced the level of damage caused by interleukin-1beta. Idazoxan caused a time- and dose-dependent loss of BRIN-BD11 cell viability in the absence of other ligands. This was associated with marked DNA degradation but was not associated with formation of nitric oxide. The effects of idazoxan were insensitive to blockade of alpha(2-adrenoceptors or 5-HT(1A (5-hydroxytryptamine; serotonin receptors. CONCLUSIONS: The results confirm that idazoxan is cytotoxic to beta-cells but show that efaroxan is better tolerated. However, since efaroxan enhanced the cytotoxic effects of interleukin-1beta, it appears that this imidazoline may sensitise BRIN-BD11 cells to the damaging effects of certain cytokines.

  6. Axial length variability in cataract surgery

    International Nuclear Information System (INIS)

    To determine the mean axial length and biometric measures in patients undergoing cataract surgery and further compare the variability of axial length between the gender and with age. Study Design: Cross-sectional observational study. Place and Duration of Study: Eye Unit I, Department of Ophthalmology, Liaquat University of Medical and Health Sciences, Hyderabad, Pakistan from January 2010 to December 2012. Methodology: All patients referred for cataract surgery were assessed. The study included 886 eyes which were straightforward cataract cases with no other ocular problem. The data was collected for axial length, keratometric values and Intra-Ocular Lens (IOL) power prior to cataract surgery. The collected data was then analyzed using SPSS version 19 for windows software. Results: Gender based comparison showed significant difference in age, axial length, keratometric values and IOL power between the two groups (p=0.000). 86% of the eyes had an axial length between 21.00 mm and 23.99 mm. In univariate analysis there was significant (p=0.000) relation between overall age and axial length. The keratometric values ranged between 36.75 D and 52.50 D. Majority of the IOL powers ranged between 20.00 D and 23.00 D. Conclusion: The mean axial length of patients undergoing cataract surgery was 22.96 +- 1.04 mm, was comparable to Indian and Chinese population but shorter than the Western population. Females had shorter axial lengths, similar to other studies. Axial length was positively associated with age among the females, the cause of which is yet to be determined. (author)

  7. The Effect of Small Bubbles on Resistance Reduction of Water Flow in Co-axial Cylinders with an Inner Rotating Cylinder

    Science.gov (United States)

    Maryami, R.; Farahat, S.; Poor, M. J.

    2015-04-01

    Drawing on effective experiments and measurement technology, the present study seeks to discuss the interaction between liquid turbulent boundary layer and a crowded group of small bubbles. Experiments are carried out using a circulating water Couette-Taylor system especially designed for small bubble experiments. Couette-Taylor system has a detailed test section, which allows measuring the effect of persistent head resistance reduction caused by small bubbles in the streamwise direction. Pressure difference is measured using sensors which are mounted at the bottom and top of the system to calculate head resistance. Pressure difference and bubble behavior are measured as a function of rotational Reynolds number up to 67.8 × 103. Small bubbles are injected constantly into annulus gap using two injectors installed at the bottom of the system and they are lifted through an array of vertical cells. Water is used to avoid uncertain interfacial property of bubbles and to produce relatively mono-sized bubble distributions. The bubble sizes range approximately from 0.9 to 1.4 mm, which are identified by the image processing method. The results suggest that head resistance is decreased after the injection of small bubble in all rotational Reynolds number under study, changing from 7,000 to 67.8 × 103. Moreover, void fraction is increased from 0 to 10.33 %. A head resistance reduction greater than 75 % was achieved in this study after the maximum measured volume of air fraction was injected into fluid flow while bubbles were distinct without making any gas layer.

  8. Investigation of Unsteady Flow Field in a Low-Speed One and a Half Stage Axial Compressor. Part 2; Effects of Tip Gap Size On the Tip Clearance Flow Structure at Near Stall Operation

    Science.gov (United States)

    Hah, Chunill; Hathaway, Michael; Katz, Joseph

    2014-01-01

    The primary focus of this paper is to investigate the effect of rotor tip gap size on how the rotor unsteady tip clearance flow structure changes in a low speed one and half stage axial compressor at near stall operation (for example, where maximum pressure rise is obtained). A Large Eddy Simulation (LES) is applied to calculate the unsteady flow field at this flow condition with both a small and a large tip gaps. The numerically obtained flow fields at the small clearance matches fairly well with the available initial measurements obtained at the Johns Hopkins University with 3-D unsteady PIV in an index-matched test facility which renders the compressor blades and casing optically transparent. With this setup, the unsteady velocity field in the entire flow domain, including the flow inside the tip gap, can be measured. The numerical results are also compared with previously published measurements in a low speed single stage compressor (Maerz et al. [2002]). The current study shows that, with the smaller rotor tip gap, the tip clearance vortex moves to the leading edge plane at near stall operating condition, creating a nearly circumferentially aligned vortex that persists around the entire rotor. On the other hand, with a large tip gap, the clearance vortex stays inside the blade passage at near stall operation. With the large tip gap, flow instability and related large pressure fluctuation at the leading edge are observed in this one and a half stage compressor. Detailed examination of the unsteady flow structure in this compressor stage reveals that the flow instability is due to shed vortices near the leading edge, and not due to a three-dimensional separation vortex originating from the suction side of the blade, which is commonly referred to during a spike-type stall inception. The entire tip clearance flow is highly unsteady. Many vortex structures in the tip clearance flow, including the sheet vortex system near the casing, interact with each other. The

  9. Effect of ligand structure of stationary phase of high per-formance hydrophobic interaction chromatography on re-naturation efficiency of GuHCl-denatured α-chymotrypsin

    Institute of Scientific and Technical Information of China (English)

    SHEN; Yehua; WANG; Haibo; BAI; Quan; GENG; Xindu

    2005-01-01

    The renaturation of the denatured α-chymotrypsin (α-Chy) with 1.7 mol · L-1 guanidine hydrochloride (GuHCI) by three kinds of stationary phase of high performance hydrophobic interaction chromatography (STHIC) with a comparable hydrophobicity but different ligand structures was investigated. The obtained result indicates that the ligand structures of the three STHIC contribute to the renaturation efficiency of α-Chy in the order of the end ligands PEG-600< phenyl group < tetrahydrofurfuryl alcohol (THFA).

  10. Hydrogen bonding to the cysteine ligand of superoxide reductase: acid-base control of the reaction intermediates.

    Science.gov (United States)

    Tremey, Emilie; Bonnot, Florence; Moreau, Yohann; Berthomieu, Catherine; Desbois, Alain; Favaudon, Vincent; Blondin, Geneviève; Houée-Levin, Chantal; Nivière, Vincent

    2013-10-01

    Superoxide reductase (SOR) is a non-heme iron metalloenzyme that detoxifies superoxide radical in microorganisms. Its active site consists of an unusual non-heme Fe(2+) center in a [His4Cys1] square pyramidal pentacoordination, with the axial cysteine ligand proposed to be an essential feature in catalysis. Two NH peptide groups from isoleucine 118 and histidine 119 establish hydrogen bonds involving the sulfur ligand (Desulfoarculus baarsii SOR numbering). To investigate the catalytic role of these hydrogen bonds, the isoleucine 118 residue of the SOR from Desulfoarculus baarsii was mutated into alanine, aspartate, or serine residues. Resonance Raman spectroscopy showed that the mutations specifically induced an increase of the strength of the Fe(3+)-S(Cys) and S-Cβ(Cys) bonds as well as a change in conformation of the cysteinyl side chain, which was associated with the alteration of the NH hydrogen bonding involving the sulfur ligand. The effects of the isoleucine mutations on the reactivity of SOR with O2 (•-) were investigated by pulse radiolysis. These studies showed that the mutations induced a specific increase of the pK a of the first reaction intermediate, recently proposed to be an Fe(2+)-O2 (•-) species. These data were supported by density functional theory calculations conducted on three models of the Fe(2+)-O2 (•-) intermediate, with one, two, or no hydrogen bonds involving the sulfur ligand. Our results demonstrated that the hydrogen bonds between the NH (peptide) and the cysteine ligand tightly control the rate of protonation of the Fe(2+)-O2 (•-) reaction intermediate to form an Fe(3+)-OOH species. PMID:23917995

  11. Released ligand fluoroimmunoassay

    International Nuclear Information System (INIS)

    Radioimmunoassay (RIA) is one of the most sensitive and specific methods for analysis of proteins, drugs and other substances commonly found in biological fluids. Because of the limited stability and problems in handling radioisotopes (particularly 125I), there has been a continuous effort in recent years to develop non-isotopic immunoassays. Fluoroimmunoassay is one of the more promising alternatives to RIA, but has relatively low sensitivity due to background fluorescence from other substances in biological fluids. The authors have proposed an alternative type of fluoroimmunoassay, released ligand fluoroimmunoassay (RLFIA), wherein the fluorophore is released from the analyte and analyzed separately, thus reducing the problems of background fluorescence. 1-(4-(3-(2,3-dihydroxy-1-carboxyethyl))-phenyl)-3-(3-(7-diethylamino-4-methylcoumarinyl)) thiourea (IX), a fluorescent coumarin derivative with a periodate cleavable vic-glycol linkage, was synthesized and employed to demonstrate the principle of RLFIA. The principle of the RLFIA was tested by comparison with a commercially available kit Immuno-Fluor IgG Assay. Because of the lower quantum yield of the fluorophore used, the sensitivity of the resulting RLFIA was only one tenth that of the commercial kit. As an outgrowth of this project, a series of analogs of compound IX, having electron donating and withdrawing groups at the phenyl ring, were synthesized in order to study the effect of substituent on fluorescence yield. An interactive computer graphics system, Chemical Structure Drawing 2-Dimensional (CSD2D), developed by the author mainly for the generation of publication quality structure drawings is also described

  12. Etanercept for the treatment of non-radiographic axial spondyloarthritis.

    Science.gov (United States)

    Rios Rodriguez, Valeria; Poddubnyy, Denis

    2016-05-01

    Presently, tumor necrosis factor α antagonist therapy is the only effective alternative treatment to nonsteroidal anti-inflammatory drugs for the entire spectrum of axial spondyloarthritis, including non-radiographic and radiographic (=ankylosing spondylitis) forms. Recently, etanercept has been approved by the European Medicines Agency for the treatment of non-radiographic axial spondyloarthritis, increasing the number of available treatment options for this indication. The latest data on etanercept concerning clinical efficacy and safety in short-term and long-term treatment of patients with non-radiographic axial spondyloarthritis who do not respond to the first-line therapy with non-steroidal anti-inflammatory drugs suggests good efficacy and safety profiles similar to that observed previously in ankylosing spondylitis. This article reviews recent data on the efficacy and safety of etanercept and is focused on the treatment of non-radiographic axial spondyloarthritis. This article will also discuss the role of etanercept in the context of current and developing treatment options. PMID:26788837

  13. New Anomaly of the Axial-Vector Current

    Institute of Scientific and Technical Information of China (English)

    HE Han-Xin

    2001-01-01

    By computing the axial-vector current operator equation, we find the anomalous axial-vector curl equation besides the well-known anomalous axial-vector divergence equation (the Adler-Bell-Jackiw anomaly) and discuss its implication.``

  14. A numerical simulation model for studying the effects of stress levels, multi axial stress states and texture on hydride reorientation in Zr alloys

    International Nuclear Information System (INIS)

    A numerical simulation model for stress reorientation of hydrides in zirconium alloys is proposed, to predict the orientation and distribution of the precipitated hydride. It was assumed in the model that all the hydrogen precipitates on the basal plane of α-Zr form transgranular hydrides, and the relative density of the precipitated hydride is proportional to the elastic strain energy induced by the positive strain along the c-axis in each crystal. Based on the model, the effects of changes in the stress states, crystallographic texture and heat treatment on the hydride precipitation properties were studied numerically and the following conclusions were reached. The typical circumferential hydride morphology observed in the tube cross-section under a stress free condition was successfully simulated when the texture of the tube was taken into consideration. The results obtained by the numerical method suggest that the radial hydride fraction, or Fn value, obtained from uniaxial tensile tests, will be useful for the substitute method of the internal pressurization tests to elucidate the hydride precipitation properties of the fuel cladding with internal pressure. The experimental data published in the literature, indicating that high fn, namely highly concentrated caxis to the tube radial direction, formed by the tube fabrication process decreased the radial hydride fraction Fn under stress free cooling, was interpreted by the proposed method. Macroscopic hydride morphologies on the cross sections of as cold worked (CW), stress relieved (SR), and recrystallization annealing heat treated (RX) tubes, cooled under a stress free condition, were estimated to be almost the same. A smaller change in the hydride reorientation was estimated for larger internal strains, which suggested that the RX tube was susceptible to stress reorientation as compared to the SR or CW tubes with larger internal strains

  15. Toxicity, mutagenicity, and behavioral effects of β-CIT, a ligand for dopamine transporter exploration by SPECT

    International Nuclear Information System (INIS)

    The cocaine analog β-CIT is one of the most used compounds for SPET examination of the dopamine transporter in drug abuse and Parkinson's disease. However, the toxicity of this agent has not yet been studied. We report here acute toxicity, mutagenicity, and effect on locomotor activity of β-CIT. Acute toxicity experiments were performed in mice and rats. The LD50 values were about 20 mg and 5 mg for mice and rats, respectively. There was no sex difference. The mutagenicity was evaluated using the Ames' test. No mutagenic effect was observed for β-CIT. Effects on locomotor activity were measured in mice using the open-field test. β-CIT increased locomotion (+65%) when injected at a dose of 0.312 mg/kg; the maximal increase (+205%) was observed at a dose of 1.25 mg/kg; at higher doses, the effect was decreased slightly. These pharmacological findings are in agreement with an inhibitory effect of β-CIT at the dopamine transporter. We conclude that with no mutagenic effects and LD50 more than 6 orders of magnitude higher than the routinely used doses in PET or SPET, it can be assumed that β-CIT can be safely used as a radioligand in humans

  16. Effects of anterior fusion cage fixation on cervical curvature, stability and axial symptoms%增加前路cage融合对颈椎曲度、稳定性及轴性症状的影响

    Institute of Scientific and Technical Information of China (English)

    李宽宽; 夏磊; 桑亮

    2014-01-01

    , stability and axial symptoms after treatment. METHODS:Clinical data of 50 patients, who received surgical treatment for cervical spondylosis, were retrospectively analyzed. 22 cases underwent I-stage spinal decompression by the combination of anterior and posterior approaches (anterior fusion cage+steel plate fixation) (combination group). 28 cases underwent cervical posterior single-door laminoplasty (posterior windowing rivet fixation) (posterior approach group). They were fol owed up for 6 to 24 months. The recovery of neurological function, incidence of axial symptoms, cervical curvature index, and slipping degree of affected intervertebral segments were analyzed statistical y. RESULTS AND CONCLUSION:The neurological functions were greatly improved according to Japanese Orthopaedic Association in both groups. Incidence of axial symptoms was relatively low in the combination group. Cervical curvature index was obviously improved in the combination group compared with the posterior approach group. The slipping degree of affected intervertebral segments was relatively greater in the posterior approach group than that in the combination group. Results suggested that fusion cage, anterior steel plate and posterior rivet for spinal decompression in I-stage combination of anterior and posterior approaches can effectively maintain cervical physiological curvature and the balance of sagittal level, reduce incidence of axial symptoms, and play a key effect on keeping posttreatment long-period cervical stability.

  17. Glutamate receptor ligands

    DEFF Research Database (Denmark)

    Guldbrandt, Mette; Johansen, Tommy N; Frydenvang, Karla Andrea; Bräuner-Osborne, Hans; Stensbøl, Tine B; Nielsen, Birgitte; Karla, Rolf; Santi, Flavio; Krogsgaard-Larsen, Povl; Madsen, Ulf

    2002-01-01

    Homologation and substitution on the carbon backbone of (S)-glutamic acid [(S)-Glu, 1], as well as absolute stereochemistry, are structural parameters of key importance for the pharmacological profile of (S)-Glu receptor ligands. We describe a series of methyl-substituted 2-aminoadipic acid (AA...

  18. AMPA receptor ligands

    DEFF Research Database (Denmark)

    Strømgaard, Kristian; Mellor, Ian

    2004-01-01

    polyamines are known to modulate the function of these receptors in vivo. In this study, recent developments in the medicinal chemistry of polyamine-based ligands are given, particularly focusing on the use of solid-phase synthesis (SPS) as a tool for the facile generation of libraries of polyamine toxin...

  19. Therapeutic effect of an altered peptide ligand derived from heat-shock protein 60 by suppressing of inflammatory cytokines secretion in two animal models of rheumatoid arthritis.

    Science.gov (United States)

    Lorenzo, N; Barberá, A; Domínguez, M C; Torres, A M; Hernandez, M V; Hernandez, I; Gil, R; Ancizar, J; Garay, H; Reyes, O; Altruda, F; Silengo, L; Padrón, G

    2012-09-01

    Rheumatoid arthritis is a systemic autoimmune disease mediated by T cells. Productive engagement of T cell receptors by major histocompatibility complex-peptide leads to proliferation, differentiation and the definition of effector functions. Altered peptide ligands (APL) generated by amino acid substitutions in the antigenic peptide have diverse effects on T cell response. We predicted a novel T cell epitope from human heat-shock protein 60, an autoantigen involved in the pathogenesis of rheumatoid arthritis. Three APLs were designed from this epitope and it was demonstrated that these peptides induce the activation of T cells through their ability to modify cell cycle phase's distribution of CD4+T cells from RA patients. Also, IL-17, TNF-α and IL-10 levels were determined in PBMC from these patients. Unlike the wild-type peptide and the other two APLs, APL2 increased the IL-10 level and suppressed IL-17 secretion in these assays. Therapeutic effect of this APL in adjuvant arthritis (AA) and collagen-induced arthritis (CIA) models was also evaluated. Clinical score, histopathology, inflammatory and regulatory cytokine concentration were monitored in the animals. APL2 efficiently inhibited the progression of AA and CIA with a significant reduction of the clinical and histopathologic score. Therapeutic effect of APL2 on CIA was similar to that obtained with MTX; the standard treatment for RA. This effect was associated with a decrease of TNF-α and IL-17 levels. These results suggest that the therapeutic effect of APL2 is mediated in part by down-regulation of inflammatory cytokines and support the potential use of APL2 as a therapeutic drug in RA patients. PMID:22686732

  20. Dynamic Assemblies and Photophysical Changes of Zinc Porphyrin Dimer Regulated by N-Containing Ligands

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zai-Chun; HE Lin; ZHU Yi-Zhou; ZHENG Jian-Yu

    2007-01-01

    Zinc porphyrin dimer (1) has been designed and synthesized as a novel host of N-containing ligands. The assembly behavior and photophysical changes of its host-guest complexes were evaluated by 1H NMR, fluorescence,and UV-visible titrations, and the processes reveal that the host-guest assembly first creates a stable sandwich complex, then an axial coordination equilibrium appears between the sandwich complex and free ligand. The changes of absorption spectra of the assembly processes rely on the stabilities of the complexes, and fluorescence quenching depends on the axial coordination equilibrium, which indicates that the axial ligation/de-ligation dynamics is indeed a pathway from the excited state to the ground state for metalloporphyrin complexes.

  1. Axial Thermal Rotation of Slender Rods

    Science.gov (United States)

    Li, Dichuan; Fakhri, Nikta; Pasquali, Matteo; Biswal, Sibani Lisa

    2011-05-01

    Axial rotational diffusion of rodlike polymers is important in processes such as microtubule filament sliding and flagella beating. By imaging the motion of small kinks along the backbone of chains of DNA-linked colloids, we produce a direct and systematic measurement of axial rotational diffusivity of rods both in bulk solution and near a wall. The measured diffusivities decrease linearly with the chain length, irrespective of the distance from a wall, in agreement with slender-body hydrodynamics theory. Moreover, the presence of small kinks does not affect the chain’s axial diffusivity. Our system and measurements provide insights into fundamental axial diffusion processes of slender objects, which encompass a wide range of entities including biological filaments and linear polymer chains.

  2. Investigation of Valve Plate in Water Hydraulic Axial Piston Motor

    Institute of Scientific and Technical Information of China (English)

    聂松林; 李壮云; 等

    2002-01-01

    This paper has introduced the developments of water hydraulic axial piston equipments.According to the effects of physicochemical properties of water on water hydraulic components,a novel valve plate for water hydraulic axial motor has been put forward,whose moment exerted by the fluid field between valve plate and bearing plate is balanced entirely.The material screening experiment of valve plate is done on the test rig.Through numerical simulation the effects of some geometry parameters on the performance of water hydraulic motor have been studied.The silencing grooves on the valve plate in water hydraulic motor can reduce the pressure shock and the occurrence of cavitation effectively.It is evident that the appropriate structure should change the wear status between matching paris and reduces the wear and specific pressure of the matching pairs.The specimen with the new type valve plate is used in a tool system.

  3. Specificity of Receptor – Ligand Interactions and Their Effect on Dimerisation as Observed by Electrospray Mass Spectrometry: Bile Acids Form Stable Adducts to the RXRα

    OpenAIRE

    Lengqvist, Johan; Mata de Urquiza, Alexander; Perlmann, Thomas; Sjövall, Jan; Griffiths, William J.

    2005-01-01

    Electrospray (ES) mass spectrometry data is presented showing that agonist binding to the nuclear receptor (NR), retinoid X receptor α (RXRα), is competitive. The competitive nature of agonist binding can be used to discriminate between the specific and non-specific binding of small lipophilic molecules to NRs. Further, data is presented showing that high affinity ligand binding to the RXRα ligand binding domain (LBD) stabilises the domain homodimer. The results indicate that homodimerisation...

  4. Nonperturbative features of the axial current

    CERN Document Server

    Kopeliovich, B Z; Siddikov, M

    2013-01-01

    In this paper we study the nonperturbative structure of the axial current and evaluate the two-point distribution amplitudes $\\int d\\xi\\, e^{-iq...\\xi}$ in the framework of the instanton vacuum model in the leading order in $\\mathcal{O}(N_{c})$. We perform a direct numerical test of the relations between the axial current and the pion distribution amplitudes, imposed by PCAC, and found excellent agreement.

  5. Axial Vircator for Electronic Warfare Applications

    OpenAIRE

    L. Drazan; R. Vrana

    2009-01-01

    This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM) is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered b...

  6. Nonperturbative Aspects of Axial Vector Vertex

    Institute of Scientific and Technical Information of China (English)

    ZONG Hong-Shi; CHEN Xiang-Song; WANG Fan; CHANG Chao-Hsi; ZHAO En-Guang

    2002-01-01

    It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model.Gluon dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger Dyson equation in the rainbow approximation,respectively.

  7. Axial blanket fuel design and demonstration. First semi-annual progress report, January-September 1980

    International Nuclear Information System (INIS)

    The axial blanket fuel design in this program, which is retrofittable in operating pressurized water reactors, involves replacing the top and bottom of the enriched fuel column with low-enriched (less than or equal to 1.0 wt % 235U) fertile uranium. This repositioning of the fissile inventory in the fuel rod leads to decreased axial leakage and increased discharge burnups in the enriched fuel. Various axial blanket fuel designs, with blanket thicknesses from 0 to 10 inches and blanket enrichments from 0.2 to 1.0 wt % 235U, were investigated to determine the relationship between uranium utilization and power peaking. Analyses were preformed to assess the nuclear, mechanical, and thermal-hydraulic effects arising from the use of axial blankets. Four axial blanket lead test assemblies are being fabricated for scheduled irradiation in cycle 5 of Sacramento Municipal Utility District's Rancho Seco pressurized water reactor. Analyses to support licensing cycle 5 are in progress

  8. Phencyclidine-induced disruption of oscillatory activity in prefrontal cortex: Effects of antipsychotic drugs and receptor ligands.

    Science.gov (United States)

    Lladó-Pelfort, L; Troyano-Rodriguez, E; van den Munkhof, H E; Cervera-Ferri, A; Jurado, N; Núñez-Calvet, M; Artigas, F; Celada, P

    2016-03-01

    The non-competitive NMDA receptor (NMDA-R) antagonist phencyclidine (PCP) markedly disrupts thalamocortical activity, increasing excitatory neuron discharge and reducing low frequency oscillations (LFO, effects. Atypical antipsychotic reversal may additionally involve 5-HT1A-R activation (but not 5-HT2A-R blockade) since 8-OH-DPAT and BAYx3702 (but not M100907) fully countered PCP effects. Blockade of histamine H1-R (pyrilamine) and α1-adrenoceptors (prazosin) was without effect. However, the enhancement of GABAA-R-mediated neurotransmission (using muscimol, diazepam or valproate) and the reduction of excitatory neurotransmission (using the mGluR2/3 agonist LY379268 and the preferential kainite/AMPA antagonist CNQX - but not the preferential AMPA/kainate antagonist NBQX) partially or totally countered PCP effects. Overall, these results shed new light on the neurobiological mechanisms used by antipsychotic drugs to reverse NMDA-R antagonist actions and suggest that agents restoring the physiological excitatory/inhibitory balance altered by PCP may be new targets in antipsychotic drug development. PMID:26781158

  9. Caffeine increases Nr1i3 expression and potentiates the effects of its ligand, TCPOBOP, in mice liver

    Directory of Open Access Journals (Sweden)

    Heidge Fukumasu

    2015-06-01

    Full Text Available Caffeine is one of the world's most consumed substances. It is present in coffee, green tea and guarana, among others. The xenobiotic-sensing nuclear receptor subfamily 1, group I, member 3 (Nr1i3, also known as the Constitutive Androstane Receptor (Car is a key regulator of drug metabolism and excretion. No consistent description of caffeine effects on this receptor has been described. Thus, to unravel the effects of caffeine on this receptor, we performed experiments in mice. First, C57Bl/6 mice that were treated daily with caffeine (50 mg/kg for 15 days presented a slight but significant increase in Nr1i3 and Cyp2b10 gene expression. A second experiment was then performed to verify the effects of caffeine on TCPOBOP (1,4-bis-[2-(3,5-dichloropyridyloxy]benzene, 3,3′,5,5′-tetrachloro-1,4-bis(pyridyloxybenzene, the most potent agonist known for mice Nr1i3. Interestingly, caffeine potentiated TCPOBOP pleiotropic effects in mice liver, such as hepatomegaly, hepatotoxicity, hepatocyte proliferation and loss of cell-to-cell communication through gap junctions. In addition, caffeine plus TCPOBOP treatment increased liver gene expression of Nr1i3 and Cyp2b10 comparing with only caffeine or TCPOBOP treatments. Together, these results indicate that caffeine increases the expression of Nr1i3 in mice liver, although at this point it is not possible to determine if Nr1i3 directly or indirectly mediates this effect.

  10. Axial compression physical testing of traditional and bird beak SHS T-joints

    Institute of Scientific and Technical Information of China (English)

    陈誉; 王江

    2015-01-01

    The static tests of nine traditional and bird beak square hollow structure (SHS) T-joints with differentβ values and connection types under axial compression at brace end were carried out. Experimental test schemes, failure modes of specimens, jack load−vertical displacement curves, jack load−deformation of chord and strain intensity distribution curves of joints were presented. The effects ofβ and connection types on axial compression property of joints were studied. The results show that the ultimate axial compression capacity of common bird beak SHS T-joints and diamond bird beak SHS T-joints is larger than that of traditional SHS T-joint specimens with big values ofβ. The ultimate axial compression capacity of diamond bird beak SHS T-joints is larger than that of common bird beak SHS T-joints. Asβ increases, the increase of the ultimate axial compression capacity of diamond bird beak SHS T-joints over that of common bird beak joints grows. The ultimate axial compression capacity and the initial axial stiffness of all kinds of joints increase asβincreases, and the initial axial stiffness of the diamond bird beak SHS T-joints is the largest. The ductilities of common bird beak and diamond bird beak SHS T-joints increase asβ increases, but the ductility of the traditional SHS T-joints decreases asβ increases.

  11. Design and experimental investigations of a new type of casing treatment for an axial flow compressor

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, I.; Lu, X. [Chinese Academy of Sciences Beijing (China). Institute of Engineering Thermophysics

    2006-07-01

    A new type of bend skewed groove casing treatment was designed on the basis of the test results of the axial skewed groove casing treatment. The influences of utilizing it on an isolated axial-flow rotor, as well as comparisons between it and axial skewed groove, have been investigated experimentally. The effects on overall performance of the axial chord of the rotor exposed to the treated area have been examined, and the ideal axial position of the casing treatment relative to the rotor leading edge was found. For the tested rotor with the new casing treatment, experimental results showed that significant improvements in stall margin were observed without efficiency penalty (in some axial locations) at two different speeds. Compared with the axial skewed groove casing treatment, the new treated casing at the axial exposure does not increase the secondary circulation in the radial-circumferential plane based on x-wire, hot-wire measurements under the operating conditions near peak efficiency. This can be considered to be one of many factors that keep the rotor efficiency identical. (author)

  12. An Unbroken Axial Vector Current Conservation Law

    CERN Document Server

    Sharafiddinov, Rasulkhozha S

    2015-01-01

    The mass, energy and momentum of the neutrino of a true flavor have an axial-vector nature. As a consequence, the left-handed truly neutral neutrino in an axial-vector field of emission can be converted into a right-handed one and vice versa. This predicts the unidenticality of masses, energies and momenta of neutrinos of the different components. Recognizing such a difference in masses, energies, momenta and accepting that the left-handed axial-vector neutrino and the right-handed antineutrino of true neutrality refer to long-lived C-odd leptons, and the right-handed truly neutral neutrino and the left-handed axial-vector antineutrino are of short-lived fermions of C-oddity, we would write a new CP-even Dirac equation taking into account the flavor symmetrical axial-vector mass, energy and momentum matrices. Their presence explains the spontaneous mirror symmetry violation, confirming that an axial-vector current conservation law has never violated. They reflect the availability of a mirror Minkowski space i...

  13. An Assessment of Cumulative Axial and Torsional Fatigue in a Cobalt-Base Superalloy

    Science.gov (United States)

    Kalluri, Sreeramesh; Bonacuse, Peter J.

    2010-01-01

    Cumulative fatigue under axial and torsional loading conditions can include both load-order (higMow and low/high) as well as load-type sequence (axial/torsional and torsional/axial) effects. Previously reported experimental studies on a cobalt-base superalloy, Haynes 188 at 538 C, addressed these effects. These studies characterized the cumulative axial and torsional fatigue behavior under high amplitude followed by low amplitude (Kalluri, S. and Bonacuse, P. J., "Cumulative Axial and Torsional Fatigue: An Investigation of Load-Type Sequance Effects," in Multiaxial Fatigue and Deformation: Testing and Prediction, ASTM STP 1387, S. Kalluri, and P. J. Bonacuse, Eds., American Society for Testing and Materials, West Conshohocken, PA, 2000, pp. 281-301) and low amplitude followed by high amplitude (Bonacuse, P. and Kalluri, S. "Sequenced Axial and Torsional Cumulative Fatigue: Low Amplitude Followed by High Amplitude Loading," Biaxial/Multiaxial Fatigue and Fracture, ESIS Publication 31, A. Carpinteri, M. De Freitas, and A. Spagnoli, Eds., Elsevier, New York, 2003, pp. 165-182) conditions. In both studies, experiments with the following four load-type sequences were performed: (a) axial/axial, (b) torsional/torsional, (c) axial/torsional, and (d) torsional/axial. In this paper, the cumulative axial and torsional fatigue data generated in the two previous studies are combined to generate a comprehensive cumulative fatigue database on both the load-order and load-type sequence effects. This comprehensive database is used to examine applicability of the Palmgren-langer-Miner linear damage rule and a nonlinear damage curve approach for Haynes 188 subjected to the load-order and load-type sequencing described above. Summations of life fractions from the experiments are compared to the predictions from both the linear and nonlinear cumulative fatigue damage approaches. The significance of load-order versus load-type sequence effects for axial and torsional loading conditions

  14. Spin crossover and solvate effects in 1D Fe{sup II} chain compounds containig Bis(dipyridylamine)-linked triazine ligands.

    Energy Technology Data Exchange (ETDEWEB)

    Ross, , T. M.; Moubaraki, B.; Turner, D. R.; Halder, G. J.; Chastanet, G.; Neville, S. M.; Cashion, J. D.; Letard, J. F.; Batten, S. R.; Murray, K. S. (X-Ray Science Division); (Monash Univ.); (Univ. de Bordeaux)

    2011-03-01

    A series of 1D polymeric FeII spin crossover (SCO) compounds of type trans-[FeII(NCX)2(L)] Solvent has been synthesised {l_brace}L = DPPyT = 1-[4,6-bis(dipyridin-2-ylamino)-1,3,5-triazin-2-yl]pyridin-4(1H)-one for 1-4{r_brace}; NCX = NCS- for 1 and 2, NCSe- for 3 and 4; Solvent = 2.5CH2Cl2 for 1, 2CHCl3 {center_dot} 0.5CH3OH for 2 and 4, CH2Cl2 for 3; L = DPT (6-phenoxy-N2,N2,N4,N4-tetra-2-pyridinyl-1,3,5-triazine-2,4-diamine) for 5; NCX = NCS- for 5; Solvent = 2CH3OH {center_dot} H2O for 5; L = DQT {l_brace}4-[4,6-bis(dipyridin-2-ylamino)-1,3,5-triazin-2-yloxy]phenol{r_brace} for 6-8; NCX- = NCS- for 6; Solvent = 2CH2Cl2 for 6; NCX- = NCSe- for 7; Solvent = CH2Cl2 {center_dot} CH2ClCH2Cl for 7; NCX- = NCSe- for 8; Solvent = 1.5CH2Cl2 {center_dot} 0.5CH3OH for 8. Two mononuclear complexes, trans-[FeII(NCS)2(DPT)2] {center_dot} 2CH3OH (9) and trans-[FeII(NCSe)2(DPT)2] {center_dot} 2CH3OH (10), contained the L ligand in a terminal bidentate coordination mode. As well as variations made in the NCX- ligands, variations were also made in substituent groups on the s-triazine 'core' of L to investigate their intermolecular/supramolecular role in crystal packing and, thus, their influence on SCO properties. All the complexes crystallised as solvates, and the influence of the latter on the magnetism and spin transitions was explored. A wide range of physical methods was employed, as a function of temperature, viz. crystallography, PXRD (synchrotron), susceptibilities, LIESST and Moessbauer effect, in order to probe magnetostructural correlations in these 1D families. New examples of half-crossovers, with ordered -LS-HS-LS-HS- intrachain states existing below T1/2, have been observed and comparisons made to related one- or two-step systems. All the observed transitions are gradual and non-hysteretic, and brief comments are made in relation to recent theoretical models for cooperativity, developed elsewhere.

  15. Rotational Control of a Dirhodium-Centered Supramolecular Four-Gear System by Ligand Exchange.

    Science.gov (United States)

    Sanada, Kazuma; Ube, Hitoshi; Shionoya, Mitsuhiko

    2016-03-01

    Self-assembled molecular machines have great potential to enable noncovalent regulation of a coupled motion of the building blocks. Herein we report the synthesis and the rotational control of a lantern-type dirhodium complex with circularly arranged four 2,3,6,7,14,15-hexamethyltriptycene carboxylates as gears and two axial ligands as the rate control elements. The rotating rates in solution were markedly affected by the coordination ability and the bulkiness of axial ligands. Notably, the rate changes were closely correlated with the changes in the electronic states of the dirhodium center. Such ligand exchange-based control of rotational motions with color changes would advance stimulus-responsive metallo-molecular multirotors. PMID:26910765

  16. Elucidating the immunological effects of 5-azacytidine treatment in patients with myelodysplastic syndrome and identifying new conditional ligands and T-cell epitopes of relevance in melanoma.

    Science.gov (United States)

    Frøsig, Thomas Mørch

    2015-08-01

    This review is focused on research within three different areas of tumor immunology: discovery of new T-cell epitopes and a new immunological antigen (reported in Paper I and II), elucidation of the immunological effects of treatment with a hypomethylating drug (reported in Paper III) and discovery of new conditional ligands (reported in Paper IV). Many melanoma-associated T-cell epitopes have been described, but 45% of these are restricted to human leukocyte antigen (HLA)-A2, leaving the remaining 36 different HLA molecules with only a few described T-cell epitopes each. Therefore we wanted to expand the number of T-cell epitopes restricted to HLA-A1, -A3, -A11 and -B7, all HLA molecules frequently expressed in Caucasians in Western Europe and Northern America. In Paper I we focused on the proteins gp100, Mart1, MAGE-A3, NY-ESO-1, tyrosinase and TRP-2, all melanoma-associated antigens frequently recognized by T cells from HLA-A2 patients. On contrary, in Paper II we wanted to investigate the protein Nodal as a novel immunological target. We took advantage of a T-cell epitope mapping platform in which HLA ligands are predicted by computer-based algorithms, further tested in the laboratory by an ELISA-based method and used for flow cytometry-based detection of specific T-cell responses by use of combinatorial encoded major histocompatibility (MHC) class I multimers. This procedure resulted in 127 (Paper I) and 32 (Paper II) confirmed HLA ligands, respectively, which we used for screening of the T-cell recognition within peripheral blood mononuclear cell samples from melanoma patients. As spontaneous tumor-specific T-cell responses tend to be of very low frequency and probably below the detection threshold of the method, we incorporated a T-cell enrichment step prior to the detection of these responses. Our screening of 39 melanoma patients resulted in 26 (17 different) T-cell responses against the common melanoma-associated antigens and 10 (8 different) T

  17. Concentration-dependent bimodal effect of specific 18 kDa translocator protein (TSPO) ligands on cell death processes induced by ammonium chloride: potential implications for neuropathological effects due to hyperammonemia.

    Science.gov (United States)

    Caballero, Beatriz; Veenman, Leo; Bode, Julia; Leschiner, Svetlana; Gavish, Moshe

    2014-01-01

    The role of the 18-kDa Translocator Protein (TSPO) in cell death induced by NH4Cl (1-50 mM) for 24-72 hours to human glioblastoma U118MG cells was investigated. Cell death was already observed after 48 hours of treatment with NH4Cl at 5 mM. Dose and time-responses curves indicated that 15 mM of NH4Cl applied for 72 hours was the optimal condition for our viability assays. For example, 72 hours of 15 mM of NH4Cl caused a 50.3% increase in propidium iodide uptake, and lactate dehydrogenase release was 41.2% of the positive control, indicating significant increases in cell death. Furthermore, compared to vehicle control, these experimental conditions resulted in a significant decrease of 44.9% of the mitochondrial activity, a 62.3% increase in incidence of collapse of mitochondrial membrane potential, and an increase of 49.0% of cardiolipin peroxidation. In addition, a significant 4.3 fold increase in the maximal binding capacity (Bmax) of TSPO was found in NH4Cl-exposed cells. Surprisingly, western blot analysis and real-time PCR did not demonstrate changes in TSPO expression. We also found that neither NH4Cl nor glutamine (a metabolic product of enhanced NH4Cl levels) inhibited binding of the TSPO ligand [(3)H]PK 11195. Interestingly, we observed a bimodal effect of the TSPO ligands PK 11195, Ro5-4864, and FGIN-1-27 on the toxicity of NH4Cl; such that 1-100 nM concentrations of TSPO ligands were protective, while concentrations above 1 μM enhanced NH4Cl-induced cell death processes. In conclusion, TSPO takes part in a bimodal way in the lethal effects induced by NH4Cl in glial type cells. PMID:24168369

  18. Landscape of protein-small ligand binding modes.

    Science.gov (United States)

    Kasahara, Kota; Kinoshita, Kengo

    2016-09-01

    Elucidating the mechanisms of specific small-molecule (ligand) recognition by proteins is a long-standing conundrum. While the structures of these molecules, proteins and ligands, have been extensively studied, protein-ligand interactions, or binding modes, have not been comprehensively analyzed. Although methods for assessing similarities of binding site structures have been extensively developed, the methods for the computational treatment of binding modes have not been well established. Here, we developed a computational method for encoding the information about binding modes as graphs, and assessing their similarities. An all-against-all comparison of 20,040 protein-ligand complexes provided the landscape of the protein-ligand binding modes and its relationships with protein- and chemical spaces. While similar proteins in the same SCOP Family tend to bind relatively similar ligands with similar binding modes, the correlation between ligand and binding similarities was not very high (R(2)  = 0.443). We found many pairs with novel relationships, in which two evolutionally distant proteins recognize dissimilar ligands by similar binding modes (757,474 pairs out of 200,790,780 pairs were categorized into this relationship, in our dataset). In addition, there were an abundance of pairs of homologous proteins binding to similar ligands with different binding modes (68,217 pairs). Our results showed that many interesting relationships between protein-ligand complexes are still hidden in the structure database, and our new method for assessing binding mode similarities is effective to find them. PMID:27327045

  19. Immunomodulatory Effect of Toll-Like Receptor-3 Ligand Poly I:C on Cortical Spreading Depression.

    Science.gov (United States)

    Ghaemi, Amir; Sajadian, Azadeh; Khodaie, Babak; Lotfinia, Ahmad Ali; Lotfinia, Mahmoud; Aghabarari, Afsaneh; Khaleghi Ghadiri, Maryam; Meuth, Sven; Gorji, Ali

    2016-01-01

    The release of inflammatory mediators following cortical spreading depression (CSD) is suggested to play a role in pathophysiology of CSD-related neurological disorders. Toll-like receptors (TLR) are master regulators of innate immune function and involved in the activation of inflammatory responses in the brain. TLR3 agonist poly I:C exerts anti-inflammatory effect and prevents cell injury in the brain. The aim of the present study was to examine the effect of systemic administration of poly I:C on the release of cytokines (TNF-α, IFN-γ, IL-4, TGF-β1, and GM-CSF) in the brain and spleen, splenic lymphocyte proliferation, expression of GAD65, GABAAα, GABAAβ as well as Hsp70, and production of dark neurons after induction of repetitive CSD in juvenile rats. Poly I:C significantly attenuated CSD-induced production of TNF-α and IFN-γ in the brain as well as TNF-α and IL-4 in the spleen. Poly I:C did not affect enhancement of splenic lymphocyte proliferation after CSD. Administration of poly I:C increased expression of GABAAα, GABAAβ as well as Hsp70 and decreased expression of GAD65 in the entorhinal cortex compared to CSD-treated tissues. In addition, poly I:C significantly prevented production of CSD-induced dark neurons. The data indicate neuroprotective and anti-inflammatory effects of TLR3 activation on CSD-induced neuroinflammation. Targeting TLR3 may provide a novel strategy for developing new treatments for CSD-related neurological disorders. PMID:25416860

  20. Effect of Inorganic and Organic Ligands on the Bioavailability of Methylmercury as Determined by Using a mer-lux Bioreporter

    OpenAIRE

    Ndu, Udonna; Mason, Robert P.; Zhang, Huan; Lin, Senjie; Visscher, Pieter T.

    2012-01-01

    A mer-lux bioreporter was constructed to assess the bioavailability of methylmercury [CH3Hg(II)] in Escherichia coli. The bioreporter was shown to be sensitive, with a detection limit of 2.5 nM CH3Hg(II), and was used to investigate the effects of chlorides, humic acids, and thiols on the bioavailability of CH3Hg(II) in E. coli. It was found that increasing the concentration of chlorides resulted in an increase in CH3Hg(II) bioavailability, suggesting that there was passive diffusion of the n...