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Sample records for acid doping level

  1. Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

    NASA Astrophysics Data System (ADS)

    Puthirath, Anand B.; Methattel Raman, Shijeesh; Varma, Sreekanth J.; Jayalekshmi, S.

    2016-04-01

    Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra can be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.

  2. Novel phosphoric acid doped polybenzimidazole membranes for fuel cells

    NASA Astrophysics Data System (ADS)

    Zhang, Haifeng

    Acid doped polybenzimidazole (PBIRTM, called mPBI in this thesis) membranes are applied as electrolytes in high temperature polymer electrolyte membrane fuel cells (PEMFCs). Several series of homopolymers and copolymers with high I.V. were synthesized in PPA solution. A novel membrane fabrication and acid doping process, called the PPA process, was developed by casting the polymer-polyphosphoric acid (PPA) solution directly after polymerization without isolation or redissolution of the polymers. The PPA absorbed moisture from the atmosphere and hydrolyzed to phosphoric acid, which induced a sol-gel transition and produced a high acid doped PBI membrane. A water spray method was developed to make an acid doped ABPBI membrane by spraying water or dilute phosphoric acid onto the cast solution directly. This process induced film formation for ABPBI, but washed out most of the phosphoric acid dopant. A more rigid pPBI homopolymer was synthesized in PPA solution with high inherent viscosity (2˜3 dL/g). Acid doped pPBI membranes showed high acid doping level (pPBI·69H3PO4) and high conductivity (0.24 S/cm at 160°C). Fuel cells based on pPBI/PA showed good performance at various conditions. For example, a fuel cell based on pPBI/PA showed a maximum power density of 0.92 W/cm2 at 160°C and ambient pressure (H2/O2). The degradation rate of the cell potential was -21 mV/1,000 hours and -35 mV/1,000 hours at 160°C and 180°C, respectively in continuous testing. Fuel cells also showed good performance and tolerance to carbon monoxide poisoning when operated at temperatures higher than 120°C. The voltage drop was only 31 mV (from 0.657 V to 0.626 V at 0.3 A/cm2) when reformate gas (40.0% H2, 0.2% CO, 19.0% CO2, 40.8% N2) was used instead of pure hydrogen at one atmosphere pressure and 160°C. The structure-property relationships were investigated on the homopolymers and copolymers with different rigidities in the main chain. It is found that para-oriented structures

  3. Doping optimization of polypyrrole with toluenesulfonic acid using Box-Behnken design

    NASA Astrophysics Data System (ADS)

    Syed Draman, Sarifah Fauziah; Daik, Rusli; El-Sheikh, Said M.; Latif, Famiza Abdul

    2013-11-01

    A three-level Box-Behnken design was employed in doping optimization of polypyrrole with toluenesulfonic acid (TSA-doped PPy). The material was synthesized via chemical oxidative polymerization using pyrrole, toluenesulfonic acid (TSA) and ammonium persulfate (APS) as monomer, dopant and oxidant, respectively. The critical factors selected for this study were concentration of dopant, molar ratio between dopant to monomer (pyrrole) and concentration of oxidant. Obtaining adequate doping level of TSA-doped PPy is crucial because it affects the charge carriers for doped PPy and usually be responsible for electronic mobility along polymeric chain. Furthermore, the doping level also affects other properties such as electrical and thermal conductivity. Doping level was calculated using elemental analysis. SEM images shows that the prepared TSA-doped PPy particles are spherical in shape with the diameters of about. The range of nanoparticles size is around 80-100 nm. The statistical analysis based on a Box-Behnken design showed that 0.01 mol of TSA, 1:1 mole ratio TSA to pyrrole and 0.25 M APS were the optimum conditions for sufficient doping level.

  4. Doping optimization of polypyrrole with toluenesulfonic acid using Box-Behnken design

    SciTech Connect

    Syed Draman, Sarifah Fauziah; Daik, Rusli; El-Sheikh, Said M.; Latif, Famiza Abdul

    2013-11-27

    A three-level Box-Behnken design was employed in doping optimization of polypyrrole with toluenesulfonic acid (TSA-doped PPy). The material was synthesized via chemical oxidative polymerization using pyrrole, toluenesulfonic acid (TSA) and ammonium persulfate (APS) as monomer, dopant and oxidant, respectively. The critical factors selected for this study were concentration of dopant, molar ratio between dopant to monomer (pyrrole) and concentration of oxidant. Obtaining adequate doping level of TSA-doped PPy is crucial because it affects the charge carriers for doped PPy and usually be responsible for electronic mobility along polymeric chain. Furthermore, the doping level also affects other properties such as electrical and thermal conductivity. Doping level was calculated using elemental analysis. SEM images shows that the prepared TSA-doped PPy particles are spherical in shape with the diameters of about. The range of nanoparticles size is around 80-100 nm. The statistical analysis based on a Box–Behnken design showed that 0.01 mol of TSA, 1:1 mole ratio TSA to pyrrole and 0.25 M APS were the optimum conditions for sufficient doping level.

  5. Structural and Electrical Characterization of Protonic Acid Doped Polyaniline

    NASA Astrophysics Data System (ADS)

    Shaktawat, Vinodini; Saxena, Narendra S.; Sharma, Kananbala; Sharma, Thaneshwar P.

    2008-04-01

    Polyaniline doped with different protonic acids were chemically synthesized using ammonium persulfate (APS) as an oxidant. These samples were characterized through X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, which confirms the amorphous nature and acid doping, respectively. Electrical conduction in these samples has been studied through the measurement of I-V characteristics at room temperature as well as in the temperature range from 313 K to 413 K. So obtained characteristic curves were found to be nonlinear. The conductivity of phosphoric acid doped polyaniline sample is higher as compared to HCl doped polyaniline and pure polyaniline. Temperature dependence of conductivity suggests a semiconducting nature with increase in temperature. Activation energies have been found to be 50.86, 25.74 and 21.05 meV for pure polyaniline (base), polyaniline doped with hydrochloric, phosphoric acid, respectively.

  6. Boosting the Boron Dopant Level in Monolayer Doping by Carboranes.

    PubMed

    Ye, Liang; González-Campo, Arántzazu; Núñez, Rosario; de Jong, Michel P; Kudernac, Tibor; van der Wiel, Wilfred G; Huskens, Jurriaan

    2015-12-16

    Monolayer doping (MLD) presents an alternative method to achieve silicon doping without causing crystal damage, and it has the capability of ultrashallow doping and the doping of nonplanar surfaces. MLD utilizes dopant-containing alkene molecules that form a monolayer on the silicon surface using the well-established hydrosilylation process. Here, we demonstrate that MLD can be extended to high doping levels by designing alkenes with a high content of dopant atoms. Concretely, carborane derivatives, which have 10 B atoms per molecule, were functionalized with an alkene group. MLD using a monolayer of such a derivative yielded up to ten times higher doping levels, as measured by X-ray photoelectron spectroscopy and dynamic secondary mass spectroscopy, compared to an alkene with a single B atom. Sheet resistance measurements showed comparably increased conductivities of the Si substrates. Thermal budget analyses indicate that the doping level can be further optimized by changing the annealing conditions. PMID:26595856

  7. Luminescence of benzoic acid polycrystals doped with n-terphenyl and n-quaterphenyl

    SciTech Connect

    Zarochentseva, E.P.; Korotkov, V.I.; Oleinik, Y.P.

    1994-10-01

    The luminescence and luminescence excitation spectra of benzoic acid polycrystals, terphenyl, quaterphenyl, and benzoic acid doped with terphenyl and quaterphenyl are studied. Blue shifts of the fluorescence and fluorscence excitation spectra are found. These shifts result from nonplanar entering of polyphenyl molecules into the unit cell of the benzoic acid dimmers around the acid carbonyl groups. In the impurity polycrystals at room temperature, the internal conversion from the triplet level efficiently occurs resulting in the absence of phosphorescence. 12 refs., 4 figs.

  8. Acid and alkali doped PBI electrolyte in electrochemical system

    NASA Astrophysics Data System (ADS)

    Xing, Baozhong

    In this work the conductivity of blank PBI membrane, acid doped PBI and alkaline doped PBI was systematically studied. A new methodology for sorption kinetics study in electrolyte solution has been established by monitoring the conductivity change during the sorption process. The model of the doping process and mechanism of conductivity are proposed. The performance of PBI (doped under optimum conditions) in fuel cell as PEM was evaluated. The experimental results show that the blank PBI in acid solution is an ionic insulator. It clarified the long time confusion in this area. The acid doped PBI membrane is an ionic conductor. The conductivity increases with the concentration of the acid solution. In high concentration acid solution, the conductivity increases with the type of acid in the order: H2SO 4 > H3PO4 > HClO4 > HNO3 > HCl. The kinetics of the doping process was studied, by a continuous method. The ionic conductivity mechanism was established. The PBI membranes doped with H2SO4 and H3PO4 exhibit better performance than NafionRTM. The doped FBI has more resistance to CO poison. 3% CO in H2 has little effect on the H3PO 4 doped PBI membrane at 185°C. The conductivity of the alkali doped PBI membrane changes with the concentration of the alkaline solution and the type of the alkalis. The conductivity has a maximum in KOH and NaOH solution. The maximum conductivity in KOH is higher than in NaOH and LiOH. It is about 5 times of that of NafionRTM in alkaline solution. The two-step sorption process in alkaline solution was observed. The first step is the permeation process of the alkalis in the PBI membrane. The permeation is the results of diffusion and interaction. It is concluded that the permeation process is controlled by the rate of interaction between the alkali and PBI molecule. The second step is the relaxation process in the membrane. This step contributes more to the conductivity for the membrane than the first step. The ionic conductivity mechanism

  9. Reporting doping in sport: national level athletes' perceptions of their role in doping prevention.

    PubMed

    Whitaker, L; Backhouse, S H; Long, J

    2014-12-01

    This paper qualitatively explores national level athletes' willingness to report doping in sport. Following ethical approval, semi-structured interviews were conducted with nine national level athletes from rugby league (n = 5) and track and field athletics (n = 4). Thematic analysis established the main themes within the data. Contextual differences existed around the role that athletes perceived they would play if they became aware of doping. Specifically, track and field athletes would adopt the role of a whistle-blower and report individuals who were doping in their sport. In comparison, the rugby league players highlighted a moral dilemma. Despite disagreeing with their teammates' actions, the players would adhere to a code of silence and refrain from reporting doping. Taking these findings into account, prevention programs might focus on changing broader group and community norms around doping. In doing so, community members' receptivity to prevention messages may increase. Moreover, developing skills to intervene (e.g., speaking out against social norms that support doping behavior) or increasing awareness of reporting lines could enhance community responsibility for doping prevention. In sum, the findings highlight the need to consider the context of sport and emphasize that a one-size-fits-all approach to anti-doping is problematic. PMID:24673128

  10. Vacuum thermal evaporation of polyaniline doped with camphor sulfonic acid

    SciTech Connect

    Boyne, Devon; Menegazzo, Nicola; Pupillo, Rachel C.; Rosenthal, Joel; Booksh, Karl S.

    2015-05-15

    Intrinsically conducting polymers belong to a class of organic polymers with intriguing electronic and physical properties specifically for electro-optical applications. Significant interest into doped polyaniline (PAni) can be attributed to its high conductivity and environmental stability. Poor dissolution in most solvents has thus far hindered the successful integration of PAni into commercial applications, which in turn, has led to the investigations of various deposition and acidic doping methods. Physical vapor deposition methods, including D.C. magnetron sputtering and vacuum thermal evaporation, have shown exceptional control over physical film properties (thickness and morphology). However, resulting films are less conductive than films deposited by conventional methods (i.e., spin and drop casting) due to interruption of the hyperconjugation of polymer chains. Specifically, vacuum thermal evaporation requires a postdoping process, which results in incorporation of impurities and oxidation of surface moieties. In this contribution, thermally evaporated films, sequentially doped by vacuum evaporation of an organic acid (camphorsulfonic acid, CSA) is explored. Spectroscopic evidence confirms the successful doping of PAni with CSA while physical characterization (atomic force microscopy) suggests films retain good morphology and are not damaged by the doping process. The procedure presented herein also combines other postpreparation methods in an attempt to improve conductivity and/or substrate adhesion.

  11. Dependence of resistivity on the doping level of polycrystalline silicon

    NASA Technical Reports Server (NTRS)

    Fripp, A. L.

    1975-01-01

    The electrical resistivity of polycrystalline silicon films has been studied as a function of doping concentration and heat treatment. The films were grown by the chemical vapor decomposition of silane on oxidized silicon wafers. The resistivity of the as-deposited films was widely scattered but independent of dopant atom concentration at the lightly doped levels and was strong function of dopant level in the more heavily doped regions. Postdeposition heat treatments in an oxidizing atmosphere remove scatter in the data. The resultant resistivity for dopant levels less than 10 to the 16th atoms/per cu cm was approximately equal to that of intrinsic silicon. In the next 2 orders of magnitude increase in dopant level, the resistivity dropped 6 orders of magnitude. A model, based on high dopant atom segregation in the grain boundaries, is proposed to explain the results.

  12. Preparation of polyaniline nanostructures doped with different dicarboxylic acids through template-free method

    NASA Astrophysics Data System (ADS)

    Sun, Chuanyu; Wang, Yu

    2014-09-01

    In this article nanoscaled polyanilines (PANI) were prepared based on template-free method in the presence of dicarboxylic acid dopants (e.g. D-tartaric acid, succinic acid, maleic acid and fumaric acid). The trans-cis isomerization of butenedioic acid played an important role in the formation of nanostructures from the plane-like to nanofibers, and the PANI doped with maleic acid (MA) had larger diameter, higher crystallinity and conductivity than PANI doped with fumaric acid (FA).

  13. Energy levels scheme simulation of divalent cobalt doped bismuth germanate

    SciTech Connect

    Andreici, Emiliana-Laura; Petkova, Petya; Avram, Nicolae M.

    2015-12-07

    The aim of this paper is to simulate the energy levels scheme for Bismuth Germanate (BGO) doped with divalent cobalt, in order to give a reliable explanation for spectral experimental data. In the semiempirical crystal field theory we first modeled the Crystal Field Parameters (CFPs) of BGO:Cr{sup 2+} system, in the frame of Exchange Charge Model (ECM), with actually site symmetry of the impurity ions after doping. The values of CFPs depend on the geometry of doped host matrix and by parameter G of ECM. First, we optimized the geometry of undoped BGO host matrix and afterwards, that of doped BGO with divalent cobalt. The charges effect of ligands and covalence bonding between cobalt cations and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the CFPs we simulate the energy levels scheme of cobalt ions, by diagonalizing the matrix of the doped crystal Hamiltonian. Obviously, energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison of obtained results with experimental data shows quite satisfactory, which justify the model and simulation schemes used for the title system.

  14. A Comparative Study of Phosphoric Acid-doped m-PBI Membranes

    SciTech Connect

    Perry, Kelly A; More, Karren Leslie; Payzant, E Andrew; Meisner, Roberta A; Sumpter, Bobby G; Benicewicz, Brian

    2014-01-01

    Phosphoric acid (PA)-doped m-polybenzimidazole (PBI) membranes used in high temperature fuel cells and hydrogen pumps were prepared by a conventional imbibing process and a sol-gel fabrication process. A comparative study was conducted to investigate the critical properties of PA doping levels, ionic conductivities, mechanical properties, and molecular ordering. This systematic study found that sol-gel PA-doped m-PBI membranes were able to absorb higher acid doping levels and to achieve higher ionic conductivities than conventionally imbibed membranes when treated in an equivalent manner. Even at similar acid loadings, the sol-gel membranes exhibited higher ionic conductivities. Heat treatment of conventionally imbibed membranes with 29wt% solids caused a significant reduction in mechanical properties; conversely, sol-gel membranes exhibited an enhancement in mechanical properties. From X-ray structural studies and atomistic simulations, both conventionally imbibed and sol-gel membranes exhibited d-spacings of 3.5 and 4.6 , which were tentatively attributed to parallel ring stacking and staggered side-to-side packing, respectively, of the imidazole rings in these aromatic hetercyclic polymers. An anisotropic staggered side-to-side chain packing present in the conventional membranes may be root to the reduction in mechanical properties.

  15. Doping level influence on chemical surface of diamond electrodes

    NASA Astrophysics Data System (ADS)

    Azevedo, A. F.; Baldan, M. R.; Ferreira, N. G.

    2013-04-01

    The modification of surface bond termination promoted by the doping level on diamond electrodes is analyzed. The films were prepared by hot filament chemical vapor deposition technique using the standard mixture of H2/CH4 with an extra H2 flux passing through a bubbler containing different concentrations of B2O3 dissolved in methanol. Diamond morphology and quality were characterized by scanning electron microscopy and Raman scattering spectroscopy techniques while the changes in film surfaces were analyzed by contact angle, cyclic voltammetry and synchrotron X-ray photoelectron spectroscopy (XPS). The boron-doped diamond (BDD) films hydrophobicity, reversibility, and work potential window characteristics were related to their physical properties and chemical surface, as a function of the doping level. From the Mott-Schottky plots (MSP) and XPS analyzes, for the lightly (1018 cm-3) and highly (1020 cm-3) BDD films, the relationship between the BDD electrochemical responses and their surface bond terminations is discussed.

  16. Polybenzimidazole membranes for direct methanol fuel cell: Acid-doped or alkali-doped?

    NASA Astrophysics Data System (ADS)

    Li, Long-Yun; Yu, Bor-Chern; Shih, Chao-Ming; Lue, Shingjiang Jessie

    2015-08-01

    Polybenzimidazole (PBI) films immersed in 2 M phosphoric acid (H3PO4) or 6 M potassium hydroxide (KOH) solution form electrolytes for conducting proton or hydroxide, respectively. A direct methanol fuel cell (DMFC) with the alkali-KOH doped PBI gives 117.9 mW cm-2 of power output which is more than 2 times greater than the power density of 46.5 mW cm-2 with the H3PO4-doped PBI (vs.) when both of the DMFCs use a micro porous layer (MPL) in a gas-fed cathode and a MPL-free anode and are operated at 90 °C. When the MPL-free anode and cathode are used and the fuel flow rate is tripled, the peak power density of alkaline DMFC reaches 158.9 mW cm-2.

  17. First solar cells on silicon wafers doped using sprayed boric acid

    NASA Astrophysics Data System (ADS)

    Silva, J. A.; Brito, Miguel C.; Costa, Ivo; Alves, Jorge Maia; Serra, João; Vallêra, António

    2010-11-01

    A new method for boron bulk doping of silicon ribbons is developed. The method is based on the spraying of the ribbons with a boric acid solution and is particularly suited for silicon ribbons that require a zone-melting recrystallization step. To analyse the quality of the material thus obtained, multicrystalline silicon samples doped with this doping process were used as substrate for solar cells and compared with solar cells made on commercial multicrystalline silicon wafers. The values obtained for the diffusion length and the IV curve parameters show that the method of doping with the boric acid solution is suitable to produce p-doped silicon ribbons for solar cell applications.

  18. Terminal-level relaxation in ND-doped laser materials

    SciTech Connect

    Bibeau, C.; Payne, S.A.

    1996-06-01

    During the energy extraction of a 1-{mu}m pulse in a Nd-doped laser material, the Nd-ion population is transferred from the metastable {sup 4}F{sub 3/2} level into the terminal {sup 4}I{sub 11/2} level. The terminal-level lifetime, {tau}{sub 11/2}, is defined in this case as the time it takes the Nd-ion population to decay from the {sup 4}I{sub 11/2} level into the {sup 4}I{sub 9/2} ground state. Several experimental and theoretical approaches over the last three decades have been made to measure the terminal-level lifetime. However, an agreement in the results among the different approaches for a large sampling of laser materials has never been demonstrated. This article presents three independent methods (pump-probe, emission, and energy extraction) for measuring the terminal-level lifetime in Nd:phosphate glass LG-750. The authors find remarkable agreement among the data and determine the {tau}{sub 11/2} lifetime to be 253{+-}50 ps. They extend their studies to show that the results of the pump-probe and emission methods agree to within a factor of two for additional Nd-doped glases and crystals investigated, thus offering validation for the emission method, which is a simpler, indirect approach.

  19. EPR investigations of silicon carbide nanoparticles functionalized by acid doped polyaniline

    NASA Astrophysics Data System (ADS)

    Karray, Fekri; Kassiba, Abdelhadi

    2012-06-01

    Nanocomposites (SiC-PANI) based on silicon carbide nanoparticles (SiC) encapsulated in conducting polyaniline (PANI) are synthesized by direct polymerization of PANI on the nanoparticle surfaces. The conductivity of PANI and the nanocomposites was modulated by several doping levels of camphor sulfonic acid (CSA). Electron paramagnetic resonance (EPR) investigations were carried out on representative SiC-PANI samples over the temperature range [100-300 K]. The features of the EPR spectra were analyzed taking into account the paramagnetic species such as polarons with spin S=1/2 involved in two main environments realized in the composites as well as their thermal activation. A critical temperature range 200-225 K was revealed through crossover changes in the thermal behavior of the EPR spectral parameters. Insights on the electronic transport properties and their thermal evolutions were inferred from polarons species probed by EPR and the electrical conductivity in doped nanocomposites.

  20. Growth and characterization studies of pure and tartaric acid doped benzilic acid crystals

    NASA Astrophysics Data System (ADS)

    Gilda, M. J. Jarald Brigit; Devarajan, Prem Anand

    2016-04-01

    The organic nonlinear optical crystals of pure benzilic acid (PBA) and tartaric acid doped benzilic acid (TADBA) single crystals were grown by using slow evaporation method utilizing dimethyl formamide (DMF) as a solvent. Transparent single crystals of PBA and TADBA of dimensions 9×4×1 mm3 and 7×5×2 mm3 were grown after thirty days. Lattice parameters and space groups of PBA and TADBA were evaluated using single crystal X-ray diffraction analysis. Employing Fourier transform infrared spectral analysis, various functional groups in pure and doped crystals were ascertained. 1H and C13 nuclear magnetic resonance spectral analysis suggests the presence of hydrogen- and carbon-bonded network. Optical transparency of PBA and TADBA was investigated using ultraviolet-visible (UV-vis) spectral analysis whereas thermal properties of the grown crystals were studied by thermogravimetric and differential scanning calorimetry analyses. Second harmonic generation efficiency of PBA and TADBA was found to be 2.2 and 2.7 times higher than that of potassium dihydrogen phosphate.

  1. A novel phosphoric acid doped poly(ethersulphone)-poly(vinyl pyrrolidone) blend membrane for high-temperature proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Xu, Xin; Wang, Haining; Lu, Shanfu; Guo, Zhibin; Rao, Siyuan; Xiu, Ruijie; Xiang, Yan

    2015-07-01

    A high-temperature proton exchange membrane, poly(ethersulphone)-poly(vinyl pyrrolidone) (PES-PVP) blend membrane is successfully prepared by scalable polymer blending method. The physical properties of blend membrane are characterized by DSC, TG and tensile strength test. The DSC and TG results indicate PES-PVP blend membranes possess excellent thermal stability. After phosphoric acid (PA) doping treatment, the blend membrane shows enhanced proton conductivity. PA doping level and volume swelling ratio of the blend membrane are found to be positively related to the PVP content. A high proton conductivity of 0.21 S/cm is achieved at 180 °C for PA doped PES-PVP 80% with a PA doping level of 9.1. PEM fuel cell based on PA doped PES-PVP 80% membrane shows a high power density of 850 mW/cm2 and outstanding stability at 180 °C without extra humidification.

  2. Highly improved hydration level sensing properties of copper oxide films with sodium and potassium doping

    NASA Astrophysics Data System (ADS)

    Sahin, Bünyamin; Kaya, Tolga

    2016-01-01

    In this study, un-doped, Na-doped, and K-doped nanostructured CuO films were successfully synthesized by the successive ionic layer adsorption and reaction (SILAR) technique and then characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and current-voltage (I-V) measurements. Structural properties of the CuO films were affected from doping. The XRD pattern indicates the formation of polycrystalline CuO films with no secondary phases. Furthermore, doping affected the crystal structure of the samples. The optimum conductivity values for both Na and K were obtained at 4 M% doping concentrations. The comparative hydration level sensing properties of the un-doped, Na-doped, and K-doped CuO nanoparticles were also investigated. A significant enhancement in hydration level sensing properties was observed for both 4 M% Na and K-doped CuO films for all concentration levels. Detailed discussions were reported in the study regarding atomic radii, crystalline structure, and conductivity.

  3. Attachment-level parameterization in copper-doped lithium tetraborate

    NASA Astrophysics Data System (ADS)

    Hunda, B. M.; Solomon, A. M.; Hunda, T. V.; Holovey, V. M.; Puga, P. P.; Puga, G. D.

    2003-04-01

    The copper-doped lithium tetraborate Li2B4O7 (LBO) is one of the promising materials for the thermoluminescent dosimetry since it possesses the best tissue-equivalence among known non-organic materials used in the dosimetry. In addition, this material has high radiation resistance, a linear dose dependence, a wide range of operating doses and an insignificant dependence of a dose on the ionizing radiation energy. However, the results of the studies on the local attachment level parameters, which define the dosimetric properties of Li2B4O7:Cu, obtained by various authors differ considerably. To some extent, this descrepancies are due to the different purity of the initial materials and the technology of luminophor preparation, the methods of measuring the thermostimulated luminescence (TSL) and determining the parameters from the temperature luminescence glow curves (TLGC). In the present paper, the studies of the integral TSL in the polycristalline and monocrystalline LBO have been carried out at different heating rates. By means of a partial luminescence overall light collection method the energy positions of the local attachment levels have been determined, while the TLGC computer simulation technique has allowed the corresponding frequency factors to be found.

  4. The composite capacitive behaviors of the N and S dual doped ordered mesoporous carbon with ultrahigh doping level

    NASA Astrophysics Data System (ADS)

    Zhang, Deyi; Lei, Longyan; Shang, Yonghua; Wang, Kunjie; Wang, Yi

    2016-01-01

    Heteroatoms doping provides a promising strategy for improving the energy density of supercapacitors based on the carbon electrodes. In this paper, we present a N and S dual doped ordered mesoporous carbon with ultrahigh doping level using dimethylglyoxime as pristine precursor. The N doping content of the reported materials varies from 6.6 to 15.6 at.% dependent on the carbonization temperature, and the S doping content varies from 0.46 to 1.01 at.%. Due to the ultrahigh heteroatoms doping content, the reported materials exhibit pronounced pseudo-capacitance. Meanwhile, the reported materials exhibit high surface areas (640-869 m2 g-1), large pore volume (0.71-1.08 cm2 g-1) and ordered pore structure. The outstanding textual properties endow the reported materials excellent electrical double-layer capacitance (EDLC). By effectively combining the pseudo-capacitance with EDLC, the reported materials exhibit a surprising energy storage/relax capacity with the highest specific capacitance of 565 F g-1, which value is 3.3 times higher than that of pristine CMK-3, and can compete against some conventional pseudo-capacitance materials.

  5. Effect of amino acid doping on the growth and ferroelectric properties of triglycine sulphate single crystals

    SciTech Connect

    Raghavan, C.M.; Sankar, R.; Mohan Kumar, R.; Jayavel, R.

    2008-02-05

    Effect of amino acids (L-leucine and isoleucine) doping on the growth aspects and ferroelectric properties of triglycine sulphate crystals has been studied. Pure and doped crystals were grown from aqueous solution by low temperature solution growth technique. The cell parameter values were found to significantly vary for doped crystals. Fourier transform infrared analysis confirmed the presence of functional groups in the grown crystal. Morphology study reveals that amino acid doping induces faster growth rate along b-direction leading to a wide b-plane and hence suitable for pyroelectric detector applications. Ferroelectric domain structure has been studied by atomic force microscopy and hysteresis measurements reveal an increase of coercive field due to the formation of single domain pattern.

  6. Resistivity reduction of boron-doped multiwalled carbon nanotubes synthesized from a methanol solution containing boric acid

    NASA Astrophysics Data System (ADS)

    Ishii, Satoshi; Watanabe, Tohru; Ueda, Shinya; Tsuda, Shunsuke; Yamaguchi, Takahide; Takano, Yoshihiko

    2008-05-01

    Boron-doped multiwalled carbon nanotubes (MWNTs) were synthesized using a methanol solution of boric acid as a source material. Accurate measurements of the electrical resistivity of an individual boron-doped MWNT was performed with a four-point contact, which was fabricated using an electron beam lithography technique. The doped boron provides conduction carriers, which reduces the resistivity of the MWNT.

  7. Photoelectrocatalytic degradation of benzoic acid using Au doped TiO2 thin films.

    PubMed

    Mohite, V S; Mahadik, M A; Kumbhar, S S; Hunge, Y M; Kim, J H; Moholkar, A V; Rajpure, K Y; Bhosale, C H

    2015-01-01

    Highly transparent pure and Au doped TiO2 thin films are successfully deposited by using simple chemical spray pyrolysis technique. The effect of Au doping onto the structural and physicochemical properties has been investigated. The PEC study shows that, both short circuit current (Isc) and open circuit voltage (Voc) are (Isc=1.81mA and Voc=890mV) relatively higher at 3at.% Au doping percentage. XRD study shows that the films are nanocrystalline in nature with tetragonal crystal structure. FESEM images show that the film surface covered with a smooth, uniform, compact and rice shaped nanoparticles. The Au doped thin films exhibit indirect band gap, decreases from 3.23 to 3.09eV with increase in Au doping. The chemical composition and valence states of pure and Au doped TiO2 films are studied by using X-ray photoelectron spectroscopy. The photocatalytic degradation effect is 49% higher in case 3at.% Au doped TiO2 than the pure TiO2 thin film photoelectrodes in the degradation of benzoic acid. It is revealed that Au doped TiO2 can be reused for five cycles of experiments without a requirement of post-treatment while the degradation efficiency was retained. PMID:25550120

  8. Critical Current Density Performance of Malic Acid Doped Magnesium Diboride Wires at Different Operating Temperatures

    NASA Astrophysics Data System (ADS)

    Xu, X.; Kim, J. H.; Zhang, Y.; Jercinovic, M.; Babic, E.

    We investigated the effects of different operating temperatures on the performance of transport critical current density, Jc, for MgB2 + 10 wt% C4H6O5 MgB2/Fe wires. It was shown that the Jc values of the malic acid doped wires sintered at 900°C reached 104 Acm-2 at 20 K and 5 T. The Jc value extrapolated to 2 T and 20 K exceeds the practical level of 105 Acm-2. According to the Kramer plots, the pinning force, FK = Jc1/2 x B1/4, is expected to be a linear function of magnetic field B. The irreversibility field, Birr, at which extrapolated FK reaches zero, was 1.8 T at 32.8 K, 2.8 T at 30 K, 5.7 T at 25 K, 8.6 T at 20 K, and 12.5 T at 15 K, respectively.

  9. Radiation and storage-induced ageing of polypyrrole doped with dodecylbenzene sulfonic acid

    NASA Astrophysics Data System (ADS)

    Kappen, P.; Brack, N.; Hale, P. S.; Prissanaroon, W.; Welter, E.; Pigram, P. J.

    2005-04-01

    The effects of storage and exposure to X-rays on the surface chemistry of electrochemically prepared polypyrrole (PPy) doped with dodecylbenzene sulfonic acid (DBSA) were investigated using X-ray photoelectron spectroscopy (XPS). For irradiation, different photon sources (lab source and synchrotron radiation) and energies (1.4-9 keV) were chosen. This covers an energy range of relevance for many X-ray based investigations (e.g. XPS or X-ray absorption spectroscopy) of PPy[DBSA], PPy-metal interfaces, and transition metals embedded into PPy. The DBSA doping level and the concentration ratio of sulfonate species are discussed as a function of storage and irradiation times, and links between both ageing parameters are given. New sulfur species are found to emerge upon repeated soft X-ray irradiation. Severe changes in the polaron/bipolaron structure of PPy[DBSA] during exposure to high energy (several keV) synchrotron radiation are observed, and the results are discussed in the light of photon absorption and photoelectron generation in the polymer surface.

  10. Probing the Doping level in Graphene Using Surface Plasmon Resonance.

    NASA Astrophysics Data System (ADS)

    Alam, Kamrul; Li, Yang; Bao, Jiming

    2015-03-01

    The present work describes an investigation of the electrochemically doped large area CVD grown graphene by using surface plasmon resonance (SPR). As graphene was doped electrochemically its conductance changes based on electron and hole concentration, that have an effect on its permittivity which has influence on the refractive index. We have used SPR angle interrogation scheme, generally known as Kretschmann configuration, to detect this change in refractive index of graphene as a shift in the angle of the SPR curve. To verify our results we have use Raman spectroscopy of the graphene-Au hybrid sample that was used for SPR measurement. Shift in the G peak signifies that graphene is doped electrochemically which is also in agreement with the shift in the angle of the SPR curve.

  11. Refractive index modulation in polymer film doped with diazo Meldrum's acid

    NASA Astrophysics Data System (ADS)

    Zanutta, Alessio; Villa, Filippo; Bertarelli, Chiara; Bianco, Andrea

    2016-08-01

    Diazo Meldrum's acid undergoes a photoreaction induced by UV light and it is used as photosensitizer in photoresists. Upon photoreaction, a change in refractive index occurs, which makes this system interesting for volume holography. We report on the sublimation effect at room temperature and the effect of photoirradiation on the refractive index in thin films of CAB (Cellulose acetate butyrate) doped with different amount of diazo Meldrum's acid. A net modulation of the refractive index of 0.01 is achieved with 40% of doping ratio together with a reduction of the film thickness.

  12. Heavy metals influence on ascorbic acid level

    NASA Astrophysics Data System (ADS)

    Kamaldinov, E. V.; Patrashkov, S. A.; Batenyeva, E. V.; Korotkevich, O. S.

    2003-05-01

    It is well known that heavy metals (HM) are extremely dangerous pollutants influencing to metabolism in animals' organisms. The vitamin C is one of the most important metabolites taking part in many biochemical processes. We studied the influence of main essential HM-Zn and Cu as well as the based supertoxical elements - Cd and Pd on ascorbic acid level in serum. The studies were carried out in Tulinskoe farm of Novosibirsk region. The objects of investigations were piglets (2 month after weaning) and 6-month pigs of Early Ripe Meat breed. The levels of HM in bristle were found by stripping voltammetric analysis using the TA-2 analyzer. Vitamin C content was determined by I.P. Kondrakhin (1985) method using 2,2-dipyridyl. The significant negative correlations between Pb, Cd content and vitamin C (-0.46 ± 0.18, -0.47 ± 0.19) in 6-month pigs were determined. The tendencies of negative correlation between all HM levels in hair and ascorbic acid level in plasma of piglets were revealed. Thus, the obtained correlations let us to suppose that all studied HM influence on 1-gulono-gamma-lactone oxidase and other vitamin C metabolism enzymes activity.

  13. The shift of optical band gap in W-doped ZnO with oxygen pressure and doping level

    SciTech Connect

    Chu, J.; Peng, X.Y.; Dasari, K.; Palai, R.; Feng, P.

    2014-06-01

    Highlights: • CVD–PLD co-deposition technique was used. • Better crystalline of the ZnO samples causes the redshift of the optical band gap. • Higher W concentration induces blueshift of the optical band gap. - Abstract: Tungsten-doped (W-doped) zinc oxide (ZnO) nanostructures were synthesized on quartz substrates by pulsed laser and hot filament chemical vapor co-deposition technique under different oxygen pressures and doping levels. We studied in detail the morphological, structural and optical properties of W-doped ZnO by SEM, XPS, Raman scattering, and optical transmission spectra. A close correlation among the oxygen pressure, morphology, W concentrations and the variation of band gaps were investigated. XPS and Raman measurements show that the sample grown under the oxygen pressure of 2.7 Pa has the maximum tungsten concentration and best crystalline structure, which induces the redshift of the optical band gap. The effect of W concentration on the change of morphology and shift of optical band gap was also studied for the samples grown under the fixed oxygen pressure of 2.7 Pa.

  14. Effects of high doping levels on silicon solar cell performance

    NASA Technical Reports Server (NTRS)

    Godlewski, M. P.; Brandhorst, H. W., Jr.; Baraona, C. R.

    1975-01-01

    Open-circuit voltages measured in silicon solar cells made from 0.01 ohm-cm material are 150 mV lower than voltages calculated from simple diffusion theory and cannot be explained by poor diffusion lengths or surface leakage currents. An analytical study was made to determine whether high doping effects, which increase the intrinsic carrier concentration, could account for the low observed voltages and to determine the limits on voltage and efficiency imposed by high doping effects. The results indicate that the observed variation of voltage with base resistivity is predicted by these effects. A maximum efficiency of 19% (AMO) and a voltage of 0.7 volts were calculated for 0.1 ohm-cm cells assuming an optimum diffused layer impurity profile.

  15. Evaluation of the acid properties of porous zirconium-doped and undoped silica materials

    SciTech Connect

    Fuentes-Perujo, D.; Santamaria-Gonzalez, J.; Merida-Robles, J.; Rodriguez-Castellon, E.; Jimenez-Lopez, A.; Maireles-Torres, P. . E-mail: maireles@uma.es; Moreno-Tost, R.

    2006-07-15

    A series of porous silica and Zr-doped silica molecular sieves, belonging to the MCM-41 and MSU families, were prepared and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N{sub 2} adsorption at 77 K. Their acid properties have been evaluated by NH{sub 3}-TPD, adsorption of pyridine and deuterated acetonitrile coupled to FT-IR spectroscopy and the catalytic tests of isopropanol decomposition and isomerization of 1-butene. The acidity of purely siliceous solids were, in all cases, very low, while the incorporation of Zr(IV) into the siliceous framework produced an enhancement of the acidity. The adsorption of basic probe molecules and the catalytic behaviour revealed that Zr-doped MSU-type silica was more acidic than the analogous Zr-MCM-41 solid, with a similar Zr content. This high acidity observed in the case of Zr-doped silica samples is due to the presence of surface zirconium atoms with a low coordination, mainly creating Lewis acid sites. - Graphical abstract: The adsorption of basic probe molecules and the catalytic behaviour have revealed that MSU-type materials are more acidic than the analogous MCM-41 solids, mainly after the incorporation of zirconium into the silica framework.

  16. The interaction of propionic and butyric acids with ice and HNO₃-doped ice surfaces at 195-212 K.

    PubMed

    Romanias, Manolis N; Papadimitriou, Vassileios C; Papagiannakopoulos, Panos

    2014-12-01

    The interaction of propionic and butyric acids on ice and HNO3-doped ice were studied between 195 and 212 K and low concentrations, using a Knudsen flow reactor coupled with a quadrupole mass spectrometer. The initial uptake coefficients (γ0) of propionic and butyric acids on ice as a function of temperature are given by the expressions: γ0(T) = (7.30 ± 1.0) × 10(-10) exp[(3216 ± 478)/T] and γ0(T) = (6.36 ± 0.76) × 10(-11) exp[(3810 ± 434)/T], respectively; the quoted error limits are at 95% level of confidence. Similarly, γ0 of propionic acid on 1.96 wt % (A) and 7.69 wt % (B) HNO3-doped ice with temperature are given as γ(0,A)(T) = (2.89 ± 0.26) × 10(-8) exp[(2517 ± 266)/T] and γ(0,B)(T) = (2.77 ± 0.29) × 10(-7) exp[(2126 ± 206)/T], respectively. The results show that γ0 of C1 to C4 n-carboxylic acids on ice increase with the alkyl-group length, due to lateral interactions between alkyl-groups that favor a more perpendicular orientation and well packing of H-bonded monomers on ice. The high uptakes (>10(15) molecules cm(-2)) and long recovery signals indicate efficient growth of random multilayers above the first monolayer driven by significant van der Waals interactions. The heterogeneous loss of both acids on ice and HNO3-doped ice particles in dense cirrus clouds is estimated to take a few minutes, signifying rapid local heterogeneous removal by dense cirrus clouds. PMID:25384192

  17. Understanding the sprayed boric acid method for bulk doping of silicon ribbons

    NASA Astrophysics Data System (ADS)

    Silva, J. A.; Pêra, David; Brito, Miguel C.; Alves, Jorge Maia; Serra, João; Vallêra, A. M.

    2011-07-01

    The sprayed boric acid (SBA) method for bulk doping of silicon ribbons is investigated. Experimental procedures and main results are reviewed. Computational fluid dynamics and experimental tests using partial spraying suggest the role of gas transported evaporated boron oxide to explain the boron incorporation profiles along the sample. The industrial applicability of the SBA method is discussed.

  18. Evaluation of the acid properties of porous zirconium-doped and undoped silica materials

    NASA Astrophysics Data System (ADS)

    Fuentes-Perujo, D.; Santamaría-González, J.; Mérida-Robles, J.; Rodríguez-Castellón, E.; Jiménez-López, A.; Maireles-Torres, P.; Moreno-Tost, R.; Mariscal, R.

    2006-07-01

    A series of porous silica and Zr-doped silica molecular sieves, belonging to the MCM-41 and MSU families, were prepared and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N 2 adsorption at 77 K. Their acid properties have been evaluated by NH 3-TPD, adsorption of pyridine and deuterated acetonitrile coupled to FT-IR spectroscopy and the catalytic tests of isopropanol decomposition and isomerization of 1-butene. The acidity of purely siliceous solids were, in all cases, very low, while the incorporation of Zr(IV) into the siliceous framework produced an enhancement of the acidity. The adsorption of basic probe molecules and the catalytic behaviour revealed that Zr-doped MSU-type silica was more acidic than the analogous Zr-MCM-41 solid, with a similar Zr content. This high acidity observed in the case of Zr-doped silica samples is due to the presence of surface zirconium atoms with a low coordination, mainly creating Lewis acid sites.

  19. Effects of high doping levels silicon solar cell performance

    NASA Technical Reports Server (NTRS)

    Godlewski, M. P.; Brandhorst, H. W., Jr.; Baraona, C. R.

    1975-01-01

    The significance of the heavy doping effects (HDE) on the open-circuit voltage of silicon solar cells is assessed. Voltage calculations based on diffusion theory are modified to include the first order features of the HDE. Comparisions of the open-circuit voltage measured for cells of various base resistivities are made with those calculated using the diffusion model with and without the HDE. Results indicate that the observed variation of voltage with base resistivity is predicted by these effects. A maximum efficiency of 19% (AM0) and a voltage of 0.7 volts are calculated for 0.1 omega-cm cells assuming an optimum diffused layer impurity profile.

  20. ALCHEMI of Fe-doped B2-ordered NiAl alloys with different doping levels

    SciTech Connect

    Anderson, I.M.; Bentley, J.; Duncan, A.J.

    1994-09-01

    The ALCHEMI technique yields exact expressions for best-fit parameters in terms of ionization localization constants and site distributions of 3 elements distributed over two sublattices. In this paper, a graphical plotting technique is applied to Fe-doped NiAl B2-ordered alloys Ni{sub 0.5-x}Fe{sub x}Al{sub 0.5}, with x=0.02 or 0.10. The thin foil samples were examined in an electron microscope with an x-ray spectrometer.

  1. Enhanced diffusion of oxygen depending on Fermi level position in heavily boron-doped silicon

    SciTech Connect

    Torigoe, Kazuhisa Fujise, Jun; Ono, Toshiaki; Nakamura, Kozo

    2014-11-21

    The enhanced diffusivity of oxygen in heavily boron doped silicon was obtained by analyzing oxygen out-diffusion profile changes found at the interface between a lightly boron-doped silicon epitaxial layer and a heavily boron-doped silicon substrate by secondary ion mass spectrometry. It was found that the diffusivity is proportional to the square root of boron concentration in the range of 10{sup 18 }cm{sup −3}–10{sup 19 }cm{sup −3} at temperatures from 750 °C to 950 °C. The model based on the diffusion of oxygen dimers in double positive charge state could explain the enhanced diffusion. We have concluded that oxygen diffusion enhanced in heavily boron-doped silicon is attributed to oxygen dimers ionized depending on Fermi level position.

  2. Unintentional F doping of SrTiO3(001) etched in HF acid-structure and electronic properties

    SciTech Connect

    Chambers, Scott A.; Droubay, Timothy C.; Capan, Cigdem; Sun, Guangyuan

    2012-02-01

    We show that the HF acid etch commonly used to prepare SrTiO3(001) for heteroepitaxial growth of complex oxides results in a non-negligible level of F doping within the terminal surface layer of TiO2. Using a combination of x-ray photoelectron spectroscopy and scanned angle x-ray photoelectron diffraction, we determine that on average ~ 13% of the O anions in the surface layer are replaced by F, but that F does not occupy O sites in deeper layers. Despite this perturbation to the surface, the Fermi level remains unpinned, and the surface-state density, which determines the amount of band bending, is driven by factors other than F doping. The presence of F at the STO surface is expected to result in lower electron mobilities at complex oxide heterojunctions involving STO substrates because of impurity scattering. Unintentional F doping can be substantially reduced by replacing the HF-etch step with a boil in deionized water, which in conjunction with an oxygen tube furnace anneal, leaves the surface flat and TiO2 terminated.

  3. Microstructures of La 1.85Sr 0.15CuO 4 doped with Ni at high doping level

    NASA Astrophysics Data System (ADS)

    Wu, X. S.; Jiang, S. S.; Pan, F. M.; Lin, J.; Xu, N.; Mao Zhiqiang; Xu Gaoji; Zhang Yuheng

    1996-02-01

    Ceramic superconductors of La 1.85Sr 0.15Cu 1- yNi yO 4 with 0.00 ≤ y ≤ 0.50 were synthesized. There is no impurity phase detected in the entire Ni doped region. The structure of these Ni-doped samples was characterized by X-ray diffraction studies. The atomic structural parameters were obtained by Rietveld refinements for the Ni-doped samples with y ≤ 0.50. Some meaningful bond distances were determined according to the refined results. According to the variations of some bond distances with y, the whole doping range could be divided into two regions: low doping level (LDL) and high doping level (HDL). The bond length between the two apical oxygen atoms in the CuO 6 octahedra for the Ni-doped samples increased with increasing content of Ni in the LDL, and decreased in the HDL. The average bond distance of LaO was not changed in the whole doping region. The metal-insulator transition was also observed in this Ni-doped system.

  4. Lysobisphosphatidic acid controls endosomal cholesterol levels.

    PubMed

    Chevallier, Julien; Chamoun, Zeina; Jiang, Guowei; Prestwich, Glenn; Sakai, Naomi; Matile, Stefan; Parton, Robert G; Gruenberg, Jean

    2008-10-10

    Most cell types acquire cholesterol by endocytosis of circulating low density lipoprotein, but little is known about the mechanisms of intra-endosomal cholesterol transport and about the primary cause of its aberrant accumulation in the cholesterol storage disorder Niemann-Pick type C (NPC). Here we report that lysobisphosphatidic acid (LBPA), an unconventional phospholipid that is only detected in late endosomes, regulates endosomal cholesterol levels under the control of Alix/AlP1, which is an LBPA-interacting protein involved in sorting into multivesicular endosomes. We find that Alix down-expression decreases both LBPA levels and the lumenal vesicle content of late endosomes. Cellular cholesterol levels are also decreased, presumably because the storage capacity of endosomes is affected and thus cholesterol clearance accelerated. Both lumenal membranes and cholesterol can be restored in Alix knockdown cells by exogenously added LBPA. Conversely, we also find that LBPA becomes limiting upon pathological cholesterol accumulation in NPC cells, because the addition of exogenous LBPA, but not of LBPA isoforms or analogues, partially reverts the NPC phenotype. We conclude that LBPA controls the cholesterol capacity of endosomes. PMID:18644787

  5. Structural, functional and optical studies on the amino acid doped glycine crystal

    NASA Astrophysics Data System (ADS)

    Manikandan, M. R.; Mahalingam, T.; Ravi, G.

    2012-06-01

    Single crystals of pure and amino acid (L-arginine) doped γ-glycine single crystals have been grown from aqueous solution by employing slow evaporation method. Morphological changes in different crystallographic planes were observed in the L-arginine doped γ-glycine crystals. Incorporation of L-arginine was confirmed qualitatively by FTIR spectroscopy. Powder X-ray diffraction was carried out to confirm γ-glycine and assess the single phase nature of the crystals. The lower cutoff wavelength was decreased by the influence of L-arginine in γ-glycine and this leads to an increase in the band gap. Nonlinear optical study revealed that L-arginine doping increases the SHG efficiency of the glycine crystal.

  6. Chemical doping of MoS2 multilayer by p-toluene sulfonic acid

    NASA Astrophysics Data System (ADS)

    Andleeb, Shaista; Singh, Arun Kumar; Eom, Jonghwa

    2015-06-01

    We report the tailoring of the electrical properties of mechanically exfoliated multilayer (ML) molybdenum disulfide (MoS2) by chemical doping. Electrical charge transport and Raman spectroscopy measurements revealed that the p-toluene sulfonic acid (PTSA) imposes n-doping in ML MoS2. The shift of threshold voltage for ML MoS2 transistor was analyzed as a function of reaction time. The threshold voltage shifted toward more negative gate voltages with increasing reaction time, which indicates an n-type doping effect. The shift of the Raman peak positions was also analyzed as a function of reaction time. PTSA treatment improved the field-effect mobility by a factor of ~4 without degrading the electrical characteristics of MoS2 devices.

  7. Structural, optical, thermal, mechanical and dielectric studies of Sulfamic acid single crystals: An influence of dysprosium (Dy3+) doping

    NASA Astrophysics Data System (ADS)

    Singh, Budhendra; Shkir, Mohd.; AlFaify, S.; Kaushal, Ajay; Nasani, Narendar; Bdikin, Igor; Shoukry, H.; Yahia, I. S.; Algarni, H.

    2016-09-01

    Sulfamic acid is a potential material that exhibits excellent optical properties. A good quality, pure and dysprosium (Dy3+) doped (2.5 and 5 mol %) Sulfamic acid (SA) single crystals were grown successfully by slow cooling method. Structural study revealed a slight change in its lattice parameters and volume, suggesting the successful incorporation of Dy3+ in crystal system. The existence of dysprosium in the system was also confirmed. Presence of various vibrational modes was confirmed. Optical transparency was found to have a significant effect with variation in the doping concentration. Furthermore, a marked enhancement in its mechanical parameters with doping was also identified by nanoindentation technique. Etching study was also performed on the grown crystals to study the etch-pit formation and growth mechanism. Effect of doping on the thermal stability was analysed. All the results were compared and discussed in detail to get insight of the effect of doping concentration on Sulfamic acid crystal.

  8. Growth of DL-malic acid-doped ammonium dihydrogen phosphate crystal and its characterization

    NASA Astrophysics Data System (ADS)

    Rajesh, P.; Ramasamy, P.

    2009-06-01

    Single crystals of DL-malic acid-doped ammonium dihydrogen phosphate have been grown using slow evaporation method and also by Sankaranarayanan-Ramasamy (SR) method with the vision to improve the properties of the ADP crystals. The characterization of grown crystals was made by single-crystal X-ray diffraction, powder X-ray diffraction, UV-vis. spectroscopy, Fourier transform infrared spectroscopy (FTIR), differential thermal analysis (DTA), Vicker's microhardness, dielectric measurements, high-resolution X-ray diffraction (HRXRD) and second-harmonic studies. Structural difference between pure and doped crystal has been studied by XRD analysis. Functional groups were identified by FTIR spectroscopy. The grown crystals were found to be transparent in the entire visible region. Decomposition temperatures of the grown crystals were measured by DTA. Vicker's hardness study carried out on (0 0 1) face at room temperature shows increased hardness of the doped crystals and SR-method-grown crystals. Dielectric measurements reveal that SR-method-grown DLM-doped ADP crystals have low dielectric loss. Crystalline perfection of the grown crystals is analyzed using HRXRD. Preliminary measurements indicate that the second harmonic generation efficiency of the doped crystals at a fundamental wavelength of 1064 nm is roughly 1.5 times greater than that of pure ADP.

  9. Studies of structural, optical, dielectric relaxation and ac conductivity of different alkylbenzenesulfonic acids doped polypyrrole nanofibers

    NASA Astrophysics Data System (ADS)

    Hazarika, J.; Kumar, A.

    2016-01-01

    Polypyrrole (PPy) nanofibers doped with alkylbenzenesulfonic acids (ABSA) have been synthesized using interfacial polymerization method. HRTEM studies confirm the formation of PPy nanofibers with average diameter ranging from 13 nm to 25 nm. Broad X-ray diffraction peak in 2 θ range 20-23.46° reveals amorphous structure of PPy nanofibers. The ordering or crystallinity of polymer chains increases, while their interplanar spacing (d) and interchain separation (R) decreases for short alkyl chain ABSA doped PPy nanofibers. FTIR studies reveal that short alkyl chain ABSA doped PPy nanofibers show higher value of "effective conjugation length". PPy nanofibers doped with short alkyl chain ABSA dopant exhibit smaller optical band gap. TGA studies show enhanced thermal stability of short alkyl chain ABSA doped PPy nanofibers. Decrease in dielectric permittivity ε ‧ (ω) with increasing frequency suggests presence of electrode polarization effects. Linear decrease in dielectric loss ε ″ (ω) with increasing frequency suggests dominant effect of dc conductivity process. Low value of non-exponential exponent β (<1) reveals non-Debye relaxation of charge carriers. Scaling of imaginary modulus (M ″) reveals that the charge carriers follow the same relaxation mechanism. Moreover, the charge carriers in PPy nanofibers follow the correlated barrier hopping (CBH) transport mechanism.

  10. Sonocatalytic degradation of Acid Blue 92 using sonochemically prepared samarium doped zinc oxide nanostructures.

    PubMed

    Khataee, Alireza; Saadi, Shabnam; Vahid, Behrouz; Joo, Sang Woo; Min, Bong-Ki

    2016-03-01

    Pure and Sm-doped ZnO nanoparticles were synthesized applying a simple sonochemical method. The nanocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) techniques which confirmed the successful synthesis of the doped sonocatalyst. The sonocatalytic degradation of Acid Blue 92 (AB92), a model azo dye, was more than that with sonolysis alone. The 6% Sm-doped ZnO nanoparticles had a band gap of 2.8 eV and demonstrated the highest activity. The degradation efficiency (DE%) of sonolysis and sonocatalysis with undoped ZnO and 6% Sm-doped ZnO was 45.73%, 63.9%, and 90.10%, after 150 min of treatment, respectively. Sonocatalytic degradation of AB92 is enhanced with increasing the dopant amount and catalyst dosage and with decreasing the initial AB29 concentration. DE% declines with the addition of radical scavengers such as chloride, carbonate, sulfate, and tert-butanol. However, the addition of enhancers including potassium periodates, peroxydisulfate, and hydrogen peroxide improves DE% by producing more free radicals. The results show adequate reusability of the doped sonocatalyst. Degradation intermediates were recognized by gas chromatography-mass spectrometry (GC-MS). Using nonlinear regression analysis, an empirical kinetic model was developed to estimate the pseudo-first-order constants (kapp) as a function of the main operational parameters, including the initial dye concentration, sonocatalyst dosage, and ultrasonic power. PMID:26584981

  11. Iminodiacetic acid doped ferroelectric triglycine sulphate crystal: Crystal growth and characterization

    NASA Astrophysics Data System (ADS)

    Rai, Chitharanjan; Narayana Moolya, B.; Dharmaprakash, S. M.

    2011-01-01

    Single crystals of iminodiacetic acid (HN(CH 2COOH) 2) doped triglycine sulphate (IDATGS) crystals have been grown from aqueous solution containing 1-10 mol% of iminodiacetic acid at constant temperature by slow evaporation technique. The effects of different amounts of doping entities on the growth habit have been investigated. X-ray powder diffraction pattern for pure and doped TGS was collected to determine the lattice parameters. The grown crystals were subjected to Fourier transform infrared (FTIR) spectroscopy studies to find the presence of various functional groups qualitatively. The dielectric permittivity has been studied as a function of temperature. An increase in the transition temperature (49.2-49.7 °C) of IDATGS crystals is observed. The dielectric constant ( ε‧ max) of IDATGS crystals vary in the range 922-2410 compared to pure TGS ( Tc=49.12 °C and ε‧ max=3050). Curie Weiss constants Cp and Cf in the paraelectric and ferroelectric phases were determined. The transition temperature ( Tc) is found to decrease with increase in dopant concentration. P- E hysteresis studies show the presence of internal bias field in the crystal. Piezoelectric measurements were also carried out at room temperature. Domain patterns on b-cut plates were observed using scanning electron microscope. The micro hardness studies reveal that the doped crystals are harder than the pure TGS crystals. The low dielectric constant, higher transition temperature, internal bias field and hardness suggest that IDATGS crystals could be a potential material for IR detectors.

  12. Layered manganites : magnetic structure at extreme doping levels.

    SciTech Connect

    Mitchell, J. F.

    1998-09-11

    We report powder neutron diffraction results on the crystal and magnetic structures of the bilayer Ruddlesden-Popper phase Sr{sub 3}Mn{sub 2}O{sub 7{minus}{delta}} ({delta} = 0.0, 0.45) and correlate these structures with their magnetic and transport properties. The {delta} = 0.45 compound contains a large number of oxygen vacancies that are disordered in the MnO{sub 2} planes. As a result of this disordered vacancy structure, Sr{sub 3}Mn{sub 2}O{sub 6.55} is a nonmagnetic insulator. Sr{sub 3}Mn{sub 2}O{sub 7.0} ({delta} = 0) is an antiferromagnetic insulator whose magnetic structure is related to that of the SrMnO{sub 3} perovskite. Comparison of this end-member compound to its doped congeners in the La{sub 2{minus}2x}Sr{sub 1+2x}Mn{sub 2}O{sub 7} series highlights the extreme sensitivity of magnetic structure to dopant concentration in these layered materials.

  13. Ferromagnetic Conducting Lignosulfonic Acid-doped Polyaniline Nanocomposites

    NASA Technical Reports Server (NTRS)

    Viswansthan, Tito (Inventor); Berry, Brian (Inventor)

    2004-01-01

    A conductive ferromagnetic composition of matter comprising sulfonated lignin or a sulfonated polyflavonoid, or derivatives thereof, and ferromagnetic iron oxide particles is disclosed. Among the uses of the composition is to shield electromagnetic radiation. The ferromagnetic iron oxide particles of the composition are surprisingly stable to acid, and are easily and inexpensively formed from iron cations in solution.

  14. Electroactive self-doped poly(amic acid) with oligoaniline and sulfonic acid groups: synthesis and electrochemical properties.

    PubMed

    Chi, Maoqiang; Wang, Shutao; Liang, Yuan; Chao, Danming; Wang, Ce

    2014-06-01

    A novel poly(amic acid) with pendant aniline tetramer and sulfonic acid groups (ESPAA) was synthesized by ternary polymerization and characterized by Fourier-transform infrared spectra, ((1))H NMR and gel permeation chromatography. The polymer showed good thermal stability and excellent solubility in the common organic solvents. The electrochemical properties were investigated carefully on a CHI 660A Electrochemical Workstation. The polymer displayed good electroactivity in acid, neutral and even in alkaline solutions (pH=1-10) due to the self-doping effect between aniline tetramer and sulfonic/carboxylic acid groups. It also exhibited satisfactory electrochromic performance with high contrast value, acceptable coloration efficiency and fast switching time in the range of pH=1-9. PMID:24703661

  15. 3D Polyaniline Architecture by Concurrent Inorganic and Organic Acid Doping for Superior and Robust High Rate Supercapacitor Performance.

    PubMed

    Gawli, Yogesh; Banerjee, Abhik; Dhakras, Dipti; Deo, Meenal; Bulani, Dinesh; Wadgaonkar, Prakash; Shelke, Manjusha; Ogale, Satishchandra

    2016-01-01

    A good high rate supercapacitor performance requires a fine control of morphological (surface area and pore size distribution) and electrical properties of the electrode materials. Polyaniline (PANI) is an interesting material in supercapacitor context because it stores energy Faradaically. However in conventional inorganic (e.g. HCl) acid doping, the conductivity is high but the morphological features are undesirable. On the other hand, in weak organic acid (e.g. phytic acid) doping, interesting and desirable 3D connected morphological features are attained but the conductivity is poorer. Here the synergy of the positive quality factors of these two acid doping approaches is realized by concurrent and optimized strong-inorganic (HCl) and weak-organic (phytic) acid doping, resulting in a molecular composite material that renders impressive and robust supercapacitor performance. Thus, a nearly constant high specific capacitance of 350 F g(-1) is realized for the optimised case of binary doping over the entire range of 1 A g(-1) to 40 A g(-1) with stability of 500 cycles at 40 A g(-1). Frequency dependant conductivity measurements show that the optimized co-doped case is more metallic than separately doped materials. This transport property emanates from the unique 3D single molecular character of such system. PMID:26867570

  16. 3D Polyaniline Architecture by Concurrent Inorganic and Organic Acid Doping for Superior and Robust High Rate Supercapacitor Performance

    NASA Astrophysics Data System (ADS)

    Gawli, Yogesh; Banerjee, Abhik; Dhakras, Dipti; Deo, Meenal; Bulani, Dinesh; Wadgaonkar, Prakash; Shelke, Manjusha; Ogale, Satishchandra

    2016-02-01

    A good high rate supercapacitor performance requires a fine control of morphological (surface area and pore size distribution) and electrical properties of the electrode materials. Polyaniline (PANI) is an interesting material in supercapacitor context because it stores energy Faradaically. However in conventional inorganic (e.g. HCl) acid doping, the conductivity is high but the morphological features are undesirable. On the other hand, in weak organic acid (e.g. phytic acid) doping, interesting and desirable 3D connected morphological features are attained but the conductivity is poorer. Here the synergy of the positive quality factors of these two acid doping approaches is realized by concurrent and optimized strong-inorganic (HCl) and weak-organic (phytic) acid doping, resulting in a molecular composite material that renders impressive and robust supercapacitor performance. Thus, a nearly constant high specific capacitance of 350 F g-1 is realized for the optimised case of binary doping over the entire range of 1 A g-1 to 40 A g-1 with stability of 500 cycles at 40 A g-1. Frequency dependant conductivity measurements show that the optimized co-doped case is more metallic than separately doped materials. This transport property emanates from the unique 3D single molecular character of such system.

  17. 3D Polyaniline Architecture by Concurrent Inorganic and Organic Acid Doping for Superior and Robust High Rate Supercapacitor Performance

    PubMed Central

    Gawli, Yogesh; Banerjee, Abhik; Dhakras, Dipti; Deo, Meenal; Bulani, Dinesh; Wadgaonkar, Prakash; Shelke, Manjusha; Ogale, Satishchandra

    2016-01-01

    A good high rate supercapacitor performance requires a fine control of morphological (surface area and pore size distribution) and electrical properties of the electrode materials. Polyaniline (PANI) is an interesting material in supercapacitor context because it stores energy Faradaically. However in conventional inorganic (e.g. HCl) acid doping, the conductivity is high but the morphological features are undesirable. On the other hand, in weak organic acid (e.g. phytic acid) doping, interesting and desirable 3D connected morphological features are attained but the conductivity is poorer. Here the synergy of the positive quality factors of these two acid doping approaches is realized by concurrent and optimized strong-inorganic (HCl) and weak-organic (phytic) acid doping, resulting in a molecular composite material that renders impressive and robust supercapacitor performance. Thus, a nearly constant high specific capacitance of 350 F g−1 is realized for the optimised case of binary doping over the entire range of 1 A g−1 to 40 A g−1 with stability of 500 cycles at 40 A g−1. Frequency dependant conductivity measurements show that the optimized co-doped case is more metallic than separately doped materials. This transport property emanates from the unique 3D single molecular character of such system. PMID:26867570

  18. Critical boron-doping levels for generation of dislocations in synthetic diamond

    SciTech Connect

    Alegre, M. P. Araújo, D.; Pinero, J. C.; Lloret, F.; Villar, M. P.; Fiori, A.; Achatz, P.; Chicot, G.; Bustarret, E.; Jomard, F.

    2014-10-27

    Defects induced by boron doping in diamond layers were studied by transmission electron microscopy. The existence of a critical boron doping level above which defects are generated is reported. This level is found to be dependent on the CH{sub 4}/H{sub 2} molar ratios and on growth directions. The critical boron concentration lied in the 6.5–17.0 × 10{sup 20}at/cm{sup 3} range in the 〈111〉 direction and at 3.2 × 10{sup 21 }at/cm{sup 3} for the 〈001〉 one. Strain related effects induced by the doping are shown not to be responsible. From the location of dislocations and their Burger vectors, a model is proposed, together with their generation mechanism.

  19. Enhancing proton conduction via doping of supramolecular liquid crystals (4-alkoxybenzoic acids) with imidazole

    NASA Astrophysics Data System (ADS)

    Liang, Ting; Wu, Yong; Tan, Shuai; Yang, Xiaohui; Wei, Bingzhuo

    2015-09-01

    Enhancing proton conduction via doping was first achieved in hydrogen-bonded liquid crystals consisting of benzoic acids. Supramolecular liquid crystals formed by pure 4-alkoxybenzoic acids (nAOBA, n = 8, 10, 12) exhibited the maximum proton conductivity of 5.0 × 10-8 S cm-1. Doping of nAOBA with 25 mol% imidazole (Im0.25) had little impact on mesomorphism but increased proton conductivities by at least 3 orders of magnitude. The liquid crystals formed by nAOBA-Im0.25 exhibited the maximum proton conductivity of 1.9 × 10-4 S cm-1. It was proposed that structure diffusion of imidazole bridged interdimer proton transfer to form continuous conducting pathways in mesomorphic nAOBA-Im0.25.

  20. Synthesis and characterization of β-napthalene sulphonic acid doped poly(o-anisidine)

    NASA Astrophysics Data System (ADS)

    Sangamithirai, D.; Narayanan, V.; Stephen, A.

    2014-04-01

    Poly(o-anisidine) doped with β-napthalene sulphonic acid (β-NSA) was synthesized using ammonium persulphate as an oxidizing agent. The polymer was characterized by using FTIR, XRD and conductivity measurements. The FTIR spectra reveal the presence of functional groups that account for the formation of polymer. The structure was characterized by XRD. The conductivity of the poly(o-anisidine) salt was found to be 2.25 × 10-6 S/m.

  1. Eu-doped Mg-Al layered double hydroxide as a responsive fluorescent material and its interaction with glutamic acid

    NASA Astrophysics Data System (ADS)

    Chen, Yufeng; Li, Fei; Yu, Gensheng; Wei, Junchao

    2012-10-01

    The paper describes a study on the fluorescence of a Eu-doped Mg-Al layered double hydroxide (Eu-doped LDH) response to glutamic acid (Glu). Various characterizations (UV-Vis transmittance, TG-DTA and IR-spectrum) indicated that there is an interaction between the Eu-doped LDH and Glu. Fluorescent study was found that the red emissions resulted from 5D0-7FJ transition (J = 1, 2) of Eu3+ markedly decreased, while the blue emission at 440 nm contributed to Glu shifted to low energy after the addition of Glu to the Eu-doped LDH. The fluorescent changes may be relevant to the hydrogen-bond interaction between the Eu-doped LDH and Glu, and the mechanism of the interaction between Eu-doped LDH and Glu was discussed.

  2. Quantum confinement, core level shifts, and dopant segregation in P-doped Si⟨110⟩ nanowires

    NASA Astrophysics Data System (ADS)

    Han, Jiaxin; Chan, Tzu-Liang; Chelikowsky, James R.

    2010-10-01

    We examine P-doped Si⟨110⟩ nanowires by employing a real-space pseudopotential method. We find the defect wave function becomes more localized along the nanowire axis and the donor ionization energy increases, owing to quantum confinement. It is more difficult to dope a P atom into a Si⟨110⟩ nanowire than to dope Si bulk because the formation energy increases with decreasing size. By comparing the formation energy for different P positions within a nanowire, we find that if a P atom at the nanowire surface can overcome the energy barrier close to the surface, there is a tendency for the dopant to reside within the nanowire core. We calculate P core levels shift as P changes position within the nanowire and provide a means for x-ray photoelectron spectroscopy experiments to determine the location of P atoms within a Si nanowire.

  3. Dimensionality and doping effect on the Core-level X-ray photoemission satellites in layered ruthenates.

    NASA Astrophysics Data System (ADS)

    Guo, Haizhong; Li, Yi; Hu, Biao; Jin, Rongying; Plummer, E. W.; Zhang, Jiandi; Urbina, D.; Liu, Tijiang; Fobes, David; Mao, Zhiqiang

    2009-03-01

    Core-level photoelectron spectra of the layered perovskite crystal Srn+1RunO3n+1 (n = 1, 2, and 3) and Mn-doped Sr3Ru2O7 are investigated by x-ray photoemission spectroscopy (XPS) techniques. The Sr 3d and Ru 3d core-level spectra exhibit a two-peak structure, screened and unscreened peaks, indicating strong correlation effects among Ru 4d electrons. However, there are little changes of the core-level satellite features with n, suggesting the electron-electron correlation is mainly confined in the RuO2 plane. On the other hand, doping of Mn will drastically affect the core-level spectral weight, reflecting the doping-induced metal-to-insulator transition in the doped system. The position of Ru-core levels remain the same, thus, indicating no doping-induced change of Ru valence.

  4. Polypyrrole electrodes doped with sulfanilic acid azochromotrop for electrochemical supercapacitors

    NASA Astrophysics Data System (ADS)

    Chen, S.; Zhitomirsky, I.

    2013-12-01

    In this work we demonstrate the feasibility of deposition of polypyrrole (PPy) films by electropolymerization on stainless steel substrates and fabrication of PPy powders by chemical polymerization using sulfanilic acid azochromotrop (SPADNS) as a new anionic dopant. The problem of low adhesion of PPy films to stainless steel substrates is addressed by the use of SPADNS, which exhibits chelating properties, promoting film formation. The use of fine particles, prepared by the chemical polymerization method, allows impregnation of Ni foams and fabrication of porous electrodes with high materials loading for electrochemical supercapacitors (ES). PPy films and Ni foam based PPy electrodes show capacitive behaviour in Na2SO4 electrolyte. The electron microscopy studies, impedance spectroscopy data and analysis of the SPADNS structure provide an insight into the factors, controlling capacitive behaviour. The Ni foam based electrodes offer advantages of improved capacitive behaviour at high materials loadings and good cycling stability. The area normalized and volume normalized specific capacitances are as high as 5.43 F cm-2 and 93.6 F cm-3, respectively, for materials loading of 35.4 mg cm-2. The capacitance retention of Ni foam based electrodes is 91.5% after 1000 cycles. The Ni foam based PPy electrodes are promising for application in ES.

  5. Electrochemical incineration of sulfanilic acid at a boron-doped diamond anode.

    PubMed

    El-Ghenymy, Abdellatif; Arias, Conchita; Cabot, Pere Lluís; Centellas, Francesc; Garrido, José Antonio; Rodríguez, Rosa María; Brillas, Enric

    2012-06-01

    The anodic oxidation of sulfanilic acid solutions has been studied in acidic medium using a divided cell with a boron-doped diamond (BDD) anode and a stainless steel cathode. Overall mineralization was achieved under all experimental conditions tested due to the efficient destruction of sulfanilic acid and all its by-products with hydroxyl radicals generated at the BDD anode from water oxidation. The alternative use of an undivided cell with the same electrodes gave rise to the coating of the cathode with polymeric compounds, thus preventing the complete electrochemical incineration of sulfanilic acid. The solutions treated in the anodic compartment of the divided cell were degraded at similar rate under pH regulation within the pH interval 2.0-6.0. The mineralization current efficiency was enhanced when the applied current decreased and the initial substrate concentration increased. The decay of sulfanilic acid was followed by reversed-phase HPLC, showing a pseudo first-order kinetics. Hydroquinone and p-benzoquinone were identified as aromatic intermediates by gas chromatography-mass spectrometry and/or reversed-phase HPLC. Maleic, acetic, formic, oxalic and oxamic acids were detected as generated carboxylic acids by ion-exclusion HPLC. Ionic chromatographic analysis of electrolyzed solutions revealed that the N content of sulfanilic acid was mainly released as NH(4)(+) ion and in much smaller proportion as NO(3)(-) ion. PMID:22365277

  6. High performance B doped BiVO4 photocatalyst with visible light response by citric acid complex method.

    PubMed

    Wang, Min; Zheng, Haoyan; Liu, Qiong; Niu, Chao; Che, Yinsheng; Dang, Mingyan

    2013-10-01

    A B-doped BiVO4 photocatalyst was synthesized by citric acid complex method and using H3BO3 as the dopant source, and the photocatalyst was characterized with XPS, XRD, SEM, BET and UV-Vis DRS. The photocatalytic activity was evaluated by the photocatalytic degradation of a methyl orange (MO) solution under visible light. This assay revealed that both the pure BiVO4 and all of the B doped samples were the monoclinic phase. Doping the BiVO4 with B increased the number of V(4+) and oxygen vacancies, which led to the red shift of the absorbing boundary of the B-doped BiVO4 but had little influence on the morphology and crystal size. The B doping improved the photocatalytic activity, and the highest photocatalytic degradation rate of 98% occurred with a B dopant concentration of 0.04. PMID:23751222

  7. Thermoelectric performance of co-doped SnTe with resonant levels

    NASA Astrophysics Data System (ADS)

    Zhou, Min; Gibbs, Zachary M.; Wang, Heng; Han, Yemao; Li, Laifeng; Snyder, G. Jeffrey

    2016-07-01

    Some group III elements such as Indium are known to produce the resonant impurity states in IV-VI compounds. The discovery of these impurity states has opened up new ways for engineering the thermoelectric properties of IV-VI compounds. In this work, resonant states in SnTe were studied by co-doping with both resonant (In) and extrinsic (Ag, I) dopants. A characteristic nonlinear relationship was observed between the Hall carrier concentration (nH) and extrinsic dopant concentration (NI, NAg) in the stabilization region, where a linear increase of dopant concentration does not lead to linear response in the measured nH. Upon substituting extrinsic dopants beyond a certain amount, the nH changed proportionally with additional dopants (Ag, I) (the doping region). The Seebeck coefficients are enhanced as the resonant impurity is introduced, whereas the use of extrinsic doping only induces minor changes. Modest zT enhancements are observed at lower temperatures, which lead to an increase in the average zT values over a broad range of temperatures (300-773 K). The improved average zT obtained through co-doping indicates the promise of fine carrier density control in maximizing the favorable effect of resonant levels for thermoelectric materials.

  8. Evolution of the electron acoustic signal as function of doping level in III-V semiconductors

    SciTech Connect

    Bresse, J.F.; Papadopoulo, A.C.

    1988-07-01

    The evolution of the electron acoustic signal has been measured for Be- and Si-doped GaAs and Ga/sub 0.28/Al/sub 0.19/In/sub 0.53/As layers with doping levels from10/sup 17/ to 10/sup 20/ at. cm/sup -3/. The samples have also been analyzed by cathodoluminescence spectroscopy for near-band-edge transition and deep level emission. The results are explained by the reduction of the mean free path of phonons, giving rise to a lattice thermal conductivity decrease. Meanwhile, the electronic part of the thermal conductivity of these compounds is found to be nearly negligible.

  9. Effect of doping level of colored TiO2 nanotube arrays fabricated by electrochemical self-doping on electrochemical properties.

    PubMed

    Kim, Choonsoo; Kim, Seonghwan; Hong, Sung Pil; Lee, Jaehan; Yoon, Jeyong

    2016-06-01

    Recently, two types of TiO2 nanotube arrays (NTAs) (blue- and black-colored TiO2 NTAs), which are easily fabricated by electrochemical self-doping, have gained much attention due particularly to their enhanced capacitive and oxidant-generating properties. These enhanced electrochemical properties mean that they have potential as basic materials for energy and environmental applications, such as in supercapacitors and anodes for water treatment. However, the understanding of the effect of the doping level of these TiO2 NTAs on their electrochemical properties is limited because there is no direct comparison or relevant discussion of their respective electrochemical properties under the same conditions, despite the similar surface characteristics of the TiO2 NTAs obtained by comparable electrochemical doping. Therefore, the objective of this study was to investigate the effect of the doping level of blue and black TiO2 NTAs on their electrochemical properties, including the capacitive and oxidant-generating properties. Although no significant difference in their surface properties was found using SEM, XRD and XPS, the black TiO2 NTA revealed a slightly higher doping level than the blue TiO2 NTA, which is caused by the order of the electrochemical self-doping and annealing conditions. With the different doping levels of the two TiO2 NTAs, the black TiO2 NTA showed a higher areal capacitance, indicating good capacitive properties, and better service life in oxidant-generation than that of the blue TiO2 NTA. The blue TiO2 NTA exhibited a larger oxygen evolution overpotential and higher chlorine evolution efficiency than that of the black TiO2 NTA. We report that the new knowledge on blue and black TiO2 NTAs from this study can contribute to the further development of supercapacitors and oxidant-generating anodes for water treatment. PMID:27169417

  10. Dual responsive dysprosium-doped hydroxyapatite particles and toxicity reduction after functionalization with folic and glucuronic acids.

    PubMed

    Sánchez Lafarga, Ana Karen; Pacheco Moisés, Fermín P; Gurinov, Andrey; Ortiz, Genaro Gabriel; Carbajal Arízaga, Gregorio Guadalupe

    2015-03-01

    The development of probes for biomedical applications demands materials with low toxicity levels besides fluorescence or magnetic properties to be detected by confocal microscopes or MRI resonators. Several drug delivery systems or other biomedical materials prepared with hydroxyapatite have been proposed, however, toxicity effects might arise when the size of particles is nanometric. In this study, hydroxyapatite functionalized with glucuronic or folic acids presented lower oxidative stress, measured from lipoperoxides and nitric oxide indicators in rats than pure hydroxyapatite. In separated experiments, hydroxyapatite was doped with dysprosium cations by coprecipitation producing a single crystal phase with fluorescent properties easily visualized by confocal microscopy when excited at 488nm. These particles also presented the ability to modify the proton relaxation time in T1 maps collected by magnetic resonance imaging. These modified hydroxyapatite nanoparticles could be candidates to design bimodal probes with low toxicity. PMID:25579955

  11. Magnetic resonance and electrical properties of p-toluene sulphonic acid doped polyaniline

    NASA Astrophysics Data System (ADS)

    Arora, Manju; Arya, S. K.; Barala, Sunil Kumar; Saini, Parveen

    2013-06-01

    p-Toluene Sulphonic Acid (PTSA) doped polyaniline (PANI) analogues were synthesized by oxidative chemical polymerization method and characterized by TGA FTIR and EPR spectroscopic techniques. FTIR spectra indicates the formation of PTSA doped PANI and also revealed the dopant ions mediated interactions between polymeric chain through weak hydrogen bonding. TGA plots revealed that there is systematic variation in the weight loss at ˜300 °C from ˜4% to ˜38% with increase in dopant concentration from 0.01 N to 1.0 N. Magnetic resonance spectra of polaron charge carriers exhibit the single Lorentzian line signal with the Dysonian contribution indicating formation of metal-like domains. The polarons are localized in these domains by strong interaction between the neighboring conducting chains, in which the charge is transferred by quasi-three-dimensional (Q3D) delocalized electron. In higher concentration analogue some of polarons merge into diamagnetic bipolarons and this reduces intensity of EPR signal. The electrical conductivity of the 1.0 N PTSA doped sample was ˜4.5 S/cm which satisfies the EMI shielding criteri.

  12. Raman scattering investigations of the interaction of a COV with pure and acid doped ice particles

    NASA Astrophysics Data System (ADS)

    Facq, S.; Oancea, A.; Focsa, C.; Chazallon, B.

    2009-04-01

    Ice present in polar stratosphere is as well a common component of the troposphere, particularly in cirrus clouds widespread in tropopause and upper troposphere region. With water droplets, ice constitutes the condensed matter that can interact with atmospheric trace gases via many different trapping processes (co-deposition i.e; incorporation during growing ice conditions, adsorption, freezing etc). The incorporation of trace gases in ice surface/volume can both affect the atmospheric chemistry and the ice structure and reactivity. This can therefore modify the nature and composition of the incorporated species in ice, or in the gas phase. Recently, field measurements have demonstrated the presence of nitric acid in ice particles from cirrus clouds(1,2) (concentration between 0.63 wt% and 2.5 wt %). Moreover, laboratory experiments have shown that the uptake of atmospheric trace gases can be enhanced up to 1 or 2 orders of magnitude in these doped ice particles. Among trace gases capable to interact with atmospheric condensed matter figure volatile organic compounds such as aldehydes, ketones and alcohols (ex: ethanol and methanol). They play an important role in the upper troposphere (3,4) and snowpack chemistry (5) as they can be easily photolysed, producing free radicals and so influence the oxidizing capacity and the ozone-budget of the atmosphere (3,4). The temperature range at which these physico-chemical processes occur extents between ~ 190 K and 273K. Interaction between ice and trace gases are therefore largely dependent on the ice surface properties as well as on the phase formation dynamic (crystalline or not). This study aims to examine and characterize the incorporation of a COV (ex: ethanol), at the surface or in the volume of ice formed by different growth mechanisms (vapour deposition or droplets freezing). Vibrational spectra of water OH and ethanol CH-spectral regions are analysed using confocal micro-Raman spectroscopy at different temperatures

  13. Synthesis, characterization and binding interactions of amino acids coupled perylene diimides with colloidal doped and undoped TiO2

    NASA Astrophysics Data System (ADS)

    Kavery, E.; Nagarajan, N.; Paramaguru, G.; Renganathan, R.

    2015-07-01

    Two sensitizers based on amino acids coupled with perylene moiety having absorption in the visible region have been designed and their interaction with doped and undoped TiO2 for the application of dye sensitized solar cells (DSSCs) has been studied. The synthesized compounds PDI-PA and PDI-AA were characterized using 1H and 13C NMR, Mass and FT-IR spectroscopic techniques. The optical properties and lifetime measurements of the sensitizers were analyzed using various solvents with different polarity. The solvatochromism effect was studied using Lippert-Mataga plot. The electrochemical studies of both dyes were investigated in DMF with various scan rate ranging from 200 to 1000 mV s-1. Colloidal doped and undoped TiO2 was prepared and characterized by using absorption measurements. Binding ability of the sensitizers with the nanoparticles was studied through absorption, fluorescence quenching, cyclic voltammetry and FT-IR measurements. Results obtained from all the above analysis suggest the mode of quenching may be static. The binding constant values were calculated using Kamat-Fox equation indicates the binding behavior of the sensitizers with the nanoparticles. The fluorescence quenching was mainly attributed to electron transfer from the excited state of PDI's to the conduction band of colloidal semiconductors. The electron transfer mechanism was explained based on the Rehm-Weller equation as well as the energy level diagram.

  14. Shear bond strength of orthodontic brackets after acid-etched and erbium-doped yttrium aluminum garnet laser-etched

    PubMed Central

    Alavi, Shiva; Birang, Reza; Hajizadeh, Fatemeh

    2014-01-01

    Background: Laser ablation has been suggested as an alternative method to acid etching; however, previous studies have obtained contrasting results. The purpose of this study was to compare the shear bond strength (SBS) and fracture mode of orthodontic brackets that are bonded to enamel etched with acid and erbium-doped yttrium aluminum garnet (Er:YAG) laser. Materials and Methods: In this experimental in vitro study, buccal surfaces of 15 non-carious human premolars were divided into mesial and distal regions. Randomly, one of the regions was etched with 37% phosphoric acid for 15 s and another region irradiated with Er:YAG laser at 100 mJ energy and 20 Hz frequency for 20 s. Stainless steel brackets were then bonded using Transbond XT, following which all the samples were stored in distilled water for 24 h and then subjected to 500 thermal cycles. SBS was tested by a chisel edge, mounted on the crosshead of universal testing machine. After debonding, the teeth were examined under ×10 magnification and adhesive remnant index (ARI) score determined. SBS and ARI scores of the two groups were then compared using t-test and Mann-Whitney U test. Significant level was set at P < 0.05. Results: The mean SBS of the laser group (16.61 ± 7.7 MPa) was not significantly different from that of the acid-etched group (18.86 ± 6.09 MPa) (P = 0.41). There was no significant difference in the ARI scores between two groups (P = 0.08). However, in the laser group, more adhesive remained on the brackets, which is not suitable for orthodontic purposes. Conclusion: Laser etching at 100 mJ energy produced bond strength similar to acid etching. Therefore, Er:YAG laser may be an alternative method for conventional acid-etching. PMID:25097641

  15. The significance of plasma phytanic acid levels in adults.

    PubMed Central

    Britton, T C; Gibberd, F B; Clemens, M E; Billimoria, J D; Sidey, M C

    1989-01-01

    The presence of phytanic acid in tissues and plasma has been considered diagnostic of heredopathia atactica polyneuritiformis (Refsum's disease), but recently slightly raised plasma phytanic acid levels have been reported in other conditions. Forty two normal people were found to have a phytanic acid level of 0-33 mumol/l. Fourteen patients with heredopathia atactica polyneuritiformis had a plasma phytanic acid level before treatment of 992-6400 mumol/l. Five patients with retinitis pigmentosa but not heredopathia atactica polyneuritiformis had plasma levels of 38-192 mumol/l. It was concluded that some patients with retinitis pigmentosa without heredopathia atactica polyneuritiformis but a raised plasma phytanic acid may represent a group of patients with a disease or diseases as yet uncharacterised apart from the retinal condition. PMID:2475586

  16. Dietary supplementation and doping-related factors in high-level sailing

    PubMed Central

    2012-01-01

    Background Although dietary supplements (DSs) in sports are considered a natural need resulting from athletes’ increased physical demands, and although they are often consumed by athletes, data on DS usage in Olympic sailing are scarce. The aim of this study was to study the use of and attitudes towards DSs and doping problems in high-level competitive sailing. Methods The sample consisted of 44 high-level sailing athletes (5 of whom were female; total mean age 24.13 ± 6.67 years) and 34 coaches (1 of whom was female; total mean age 37.01 ± 11.70). An extensive, self-administered questionnaire of substance use was used, and the subjects were asked about sociodemographic data, sport-related factors, DS-related factors (i.e., usage of and knowledge about DSs, sources of information), and doping-related factors. The Kruskal-Wallis ANOVA was used to determine the differences in group characteristics, and Spearman’s rank order correlation and a logistic regression analysis were used to define the relationships between the studied variables. Results DS usage is relatively high. More than 77% of athletes consume DSs, and 38% do so on a regular basis (daily). The athletes place a high degree of trust in their coaches and/or physicians regarding DSs and doping. The most important reason for not consuming DSs is the opinion that DSs are useless and a lack of knowledge about DSs. The likelihood of doping is low, and one-third of the subjects believe that doping occurs in sailing (no significant differences between athletes and coaches). The logistic regression found crew number (i.e., single vs. double crew) to be the single significant predictor of DS usage, with a higher probability of DS consumption among single crews. Conclusion Because of the high consumption of DSs future investigations should focus on real nutritional needs in sailing sport. Also, since athletes reported that their coaches are the primary source of information about nutrition and DSs, further

  17. Fabrication of folic acid sensor based on the Cu doped SnO2 nanoparticles modified glassy carbon electrode

    NASA Astrophysics Data System (ADS)

    Lavanya, N.; Radhakrishnan, S.; Sudhan, N.; Sekar, C.; Leonardi, S. G.; Cannilla, C.; Neri, G.

    2014-07-01

    A novel folic acid biosensor has been fabricated using Cu doped SnO2 nanoparticles (NPs) synthesized by a simple microwave irradiation method. Powder XRD and TEM studies confirmed that both the pure and Cu doped SnO2 (Cu: 0, 10, 20wt%) crystallized in tetragonal rutile-type structure with spherical morphology. The average crystallite size of pure SnO2 was estimated to be around 16 nm. Upon doping, the crystallite sizes decreased to 9 nm and 5 nm for 10 and 20wt% Cu doped SnO2 respectively. XPS studies confirmed the electronic state of Sn and Cu to be 4+ and 2+ respectively. Cu (20wt%) doped SnO2 NPs are proved to be a good sensing element for the determination of folic acid (FA). Cu-SnO2 NPs (20wt%) modified glassy carbon electrode (GCE) exhibited the lowest detection limit of 0.024 nM over a wide folic acid concentration range of 1.0 × 10-10 to 6.7 × 10-5 M at physiological pH of 7.0. The fabricated sensor is highly selective towards the determination of FA even in the presence of a 100 fold excess of common interferent ascorbic acid. The sensor proved to be useful for the estimation of FA content in pharmaceutical sample with satisfactory recovery.

  18. Thermal properties of phosphoric acid-doped polybenzimidazole membranes in water and methanol-water mixtures

    NASA Astrophysics Data System (ADS)

    Nores-Pondal, Federico J.; Buera, M. Pilar; Corti, Horacio R.

    The thermal properties of phosphoric acid-doped poly[2-2‧-(m-phenylene)-5-5‧ bi-benzimidazole] (PBI) and poly[2,5-benzimidazole] (ABPBI) membranes, ionomeric materials with promising properties to be used as electrolytes in direct methanol and in high temperature polymer electrolyte membrane (PEM) fuel cells, were studied by means of differential scanning calorimetry (DSC) technique in the temperature range from -145 °C to 200 °C. The DSC scans of samples equilibrated in water at different relative humidities (RH) and in liquid water-methanol mixtures were analyzed in relation to glass transition, water crystallization/melting and solvent desorption in different temperature regions. The thermal relaxation observed in the very low temperature region could be ascribed to the glass transition of the H 3PO 4-H 2O mixture confined in the polymeric matrix. After cooling the samples up to -145 °C, frozen water was detected in PBI and ABPBI at different RH, although at 100% RH less amount of water had crystallized than that observed in Nafion membranes under the same conditions. Even more important is the fact that the freezing degree of water is much lower in ABPBI membranes equilibrated in liquid water-methanol mixtures than that observed for PBI and, in a previous study, for Nafion. Thus, apart from other well known properties, acid-doped ABPBI emerges as an excellent ionomer for applications in direct methanol fuel cells working in cold environments.

  19. Characterization of nano-lead-doped active carbon and its application in lead-acid battery

    NASA Astrophysics Data System (ADS)

    Hong, Bo; Jiang, Liangxing; Xue, Haitao; Liu, Fangyang; Jia, Ming; Li, Jie; Liu, Yexiang

    2014-12-01

    In this paper, nano-lead-doped active carbon (nano-Pb/AC) composite with low hydrogen evolution current for lead-acid battery was prepared by ultrasonic-absorption and chemical-precipitate method. The nano-Pb/AC composite was characterized by SEM, EDS and TEM. The electrochemical characterizations are performed by linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) in a three-electrode system. Since intermediate adsorption is the rate-determining step, the hydrogen evolution reaction (HER) is markedly inhibited as the intermediate adsorption impedance of nano-Pb/AC increased. Meanwhile, the working potential of nano-Pb/AC is widened to the whole potential region of Pb negative plate (from -1.36 V to -0.86 V vs. Hg/HgSO4) in lead-acid battery. In addition, nano-Pb can improve the interfacial compatibility between AC and Pb paste, accordingly relieve the symptoms of carbon floatation. Finally, 2.0 V single-cell flooded lead-acid batteries with 1.0 wt.% nano-Pb/AC or 1.0 wt.% AC addition in negative active materials are assembled. The cell performances test results show that the 3 h rate capacity, quick charging performance, high current discharging performance and cycling performance of nano-Pb/AC modified battery are all improved compared with regular lead-acid battery and AC modified lead-acid battery.

  20. Ethanol Effects On Physiological Retinoic Acid Levels

    PubMed Central

    Napoli, Joseph L.

    2011-01-01

    Summary All-trans-retinoic acid (atRA) serves essential functions during embryogenesis and throughout post-natal vertebrate life. Insufficient or excess atRA causes teratogenic and/or toxic effects in the developing embryo: interference with atRA biosynthesis or signaling likely underlies some forms of cancer. Many symptoms of vitamin A (atRA precursor) deficiency and/or toxicity overlap with those of another pleiotropic agent—ethanol. These overlapping symptoms have prompted research to understand whether interference with atRA biosynthesis and/or action may explain (in part) pathology associated with excess ethanol consumption. Ethanol affects many aspects of retinoid metabolism and mechanisms of action site-specifically, but no robust data support inhibition of vitamin A metabolism, resulting in decreased atRA in vivo during normal vitamin A nutriture. Actually, ethanol either has no effect on or increases atRA at select sites. Despite this realization, insight into whether interactions between ethanol and retinoids represent cause vs. effect requires additional research. PMID:21766417

  1. [Serum uric acid levels and risk of developing preeclampsia].

    PubMed

    Corominas, Ana I; Balconi, Silvia M; Palermo, Mario; Maskin, Bernardo; Damiano, Alicia E

    2014-01-01

    It is well known that preeclampsia is associated to high uric acid levels, but the clinical assessment of this relationship is still under consideration. Our research was to evaluate if periodic doses of uric acid during pregnancy might help to identify a high risk group prior to the onset of preeclampsia. We conducted a retrospective investigation in 79 primary gestates with normal blood pressure and 79 women with preeclampsia who were assisted at Hospital Nacional Posadas during 2010. Serum uric acid levels, creatininemia, uremia, and proteinuria data from the clinical records of the pregnant women were considered. Uric acid levels were similar in both groups during the first half of gestation. However, as of the 20th week, uric acid increased 1.5-times in preeclamptic women with no changes in creatinine and urea, confirming that these patients had no renal complications. Furthermore, we noted that higher levels of uric acid correlated with low birth weight. We also observed that pregnant women with a family history of hypertension were more likely to develop this condition. Moreover, we did not find a direct relationship with the fetal sex or the appearance of clinical symptoms. The analytical evidence suggests that changes in uric acid concentrations may be due to metabolic alterations at the initial stages of preeclampsia. Therefore, we propose that monitoring levels of uric acid during pregnancy might contribute to the early control of this condition. PMID:25555007

  2. Uric Acid Levels in Normotensive Children of Hypertensive Parents

    PubMed Central

    Yildirim, Ali; Keles, Fatma; Kosger, Pelin; Ozdemir, Gokmen; Ucar, Birsen; Kilic, Zubeyir

    2015-01-01

    This study evaluated uric acid concentrations in normotensive children of parents with hypertension. Eighty normotensive children from families with and without a history of essential hypertension were included. Concentrations of lipid parameters and uric acid were compared. Demographic and anthropometric characteristics were similar in the groups. Systolic and diastolic blood pressure were higher in the normotensive children of parents with hypertension without statistically significant difference (P > 0.05). Uric acid concentrations were higher in the normotensive children of parents with hypertension (4.61 versus 3.57 mg/dL, P < 0.01). Total cholesterol and triglyceride concentrations were similar in the two groups. Systolic and diastolic blood pressure were significantly higher in control children aged >10 years (P < 0.01). Uric acid levels were significantly higher in all children with more pronounced difference after age 10 of years (P < 0.001). Positive correlations were found between the level of serum uric acid and age, body weight, body mass index, and systolic and diastolic blood pressure in the normotensive children of parents. The higher uric acid levels in the normotensive children of hypertensive parents suggest that uric acid may be a predeterminant of hypertension. Monitoring of uric acid levels in these children may allow for prevention or earlier treatment of future hypertension. PMID:26464873

  3. Significant Enhancement of Water Splitting Activity of N-Carbon Electrocatalyst by Trace Level Co Doping.

    PubMed

    Bayatsarmadi, Bita; Zheng, Yao; Tang, Youhong; Jaroniec, Mietek; Qiao, Shi-Zhang

    2016-07-01

    Replacement of precious metal electrocatalysts with highly active and cost efficient alternatives for complete water splitting at low voltage has attracted a growing attention in recent years. Here, this study reports a carbon-based composite co-doped with nitrogen and trace amount of metallic cobalt (1 at%) as a bifunctional electrocatalyst for water splitting at low overpotential and high current density. An excellent electrochemical activity of the newly developed electrocatalyst originates from its graphitic nanostructure and highly active Co-Nx sites. In the case of carefully optimized sample of this electrocatalyst, 10 mA cm(-2) current density can be achieved for two half reactions in alkaline solutions-hydrogen evolution reaction and oxygen evolution reaction-at low overpotentials of 220 and 350 mV, respectively, which are smaller than those previously reported for nonprecious metal and metal-free counterparts. Based on the spectroscopic and electrochemical investigations, the newly identified Co-Nx sites in the carbon framework are responsible for high electrocatalytic activity of the Co,N-doped carbon. This study indicates that a trace level of the introduced Co into N-doped carbon can significantly enhance its electrocatalytic activity toward water splitting. PMID:27246288

  4. Deep levels in n-GaN Doped with Carbon Studied by Deep Level and Minority Carrier Transient Spectroscopies

    NASA Astrophysics Data System (ADS)

    Honda, Unhi; Yamada, Yujiro; Tokuda, Yutaka; Shiojima, Kenji

    2012-04-01

    Electron and hole traps in the carbon doping of n-type GaN films grown by metal-organic chemical vapor deposition were investigated by deep level and minority carrier transient spectroscopies. Four electron traps were observed in the samples. Of these traps, the electron trap concentration of E2 (Ec-0.40 eV) rose with increasing C incorporation. Two hole traps H1 (Ev + 0.86 eV) and H2 also showed the dependence of C doping concentration. According to these results, traps E2, H1, and H2 correspond to C-related defects. Moreover, the energy level of H1 was consistent with an ionization energy of 0.9 eV of CN acting as a deep acceptor, which might give rise to conventional yellow luminescence and current collapse of GaN-based high electron mobility transistors (HEMTs). This was confirmed by photoluminescence (PL) spectra that the integrated intensity of yellow luminescence (YL) band was largely dependent on C incorporation. Therefore, we speculated that hole trap H1 might be responsible for a broad YL band in the samples.

  5. Transient Fluorescence Spectroscopy and laser induced fluorescence lifetimes of terbium doped dipicolinic acid

    NASA Astrophysics Data System (ADS)

    Makoui, Anali

    We have investigated the use of deep UV laser induced fluorescence for the sensitive detection and spectroscopic lifetime studies of terbium doped dipicolinic acid (DPA-Tb) and used this to study the optical characteristics of DPA which is a chemical surrounding most bacterial spores. Background absorption spectra, fluorescence spectra, and Excitation Emission Matrix (EEM) spectra were made of the DPA-Tb complex, using both fixed 266 nm wavelength and tunable (220 nm--280 nm) UV laser excitations. Of importance, the fluorescence lifetimes of the four main fluorescence peaks (488 nm, 543 nm, 581 nm, and 618 nm) of the DPA-Tb complex have been measured for the first time to our knowledge. The lifetimes of all the fluorescing lines have been measured as a function of DPA-Tb concentration, solvent pH, and solvent composition, including that for the weakest fluorescing line of DPA-Tb at 618 nm. In addition, a new spectroscopic lifetime measurement technique, which we call "Transient Fluorescence Spectroscopy", was developed. In this technique, a weak, quasi-CW, amplitude modulated UV laser (8.5 kHz) was used to measure the lifetimes of the fluorescence lines, and yields insight into energy transfer and excitation lifetimes within the system. This technique is especially useful when a high power laser is not either available or not suitable. In the latter case, this would be when a high power pulsed deep-UV laser could produce bleaching or destruction of the biological specimen. In addition, this technique simulated the excitation and fluorescence emission of the DPA-Tb using a 4-level energy model, and solved the dynamic transient rate equations to predict the temporal behavior of the DPA-Tb emitted fluorescence. Excellent agreement between the experiments and the simulation were found. This technique has the potential to provide a more accurate value for the fluorescence lifetime values. In addition, with the use of asymmetric excitation waveforms, the dynamic

  6. [Hydroxycinnamic acid levels of various batches from mugwort flowering tops].

    PubMed

    Fraisse, D; Carnat, A; Carnat, A-P; Guédon, D; Lamaison, J-L

    2003-07-01

    Dried flowering tops of 24 harvested batches (Artemisia vulgaris: 13; Artemisia verlotiorum: 11) and 12 batches of mugwort from commercial origin were examined. The levels of principal compounds averaged respectively: total hydroxycinnamic acids 6.09; 10.29 and 9.13%, chlorogenic acid 0.79; 2.05 and 1.35%, 1,5-dicaffeoylquinic acid 0.51; 4.01 and 1.25%, 3,5-dicaffeoylquinic acid 2.21; 1.25 and 2.60%. Specifications were discussed for an European Pharmacopoeial monography. PMID:12843960

  7. Hydrophilic and blue fluorescent N-doped carbon dots from tartaric acid and various alkylol amines under microwave irradiation

    NASA Astrophysics Data System (ADS)

    Xu, Minghan; Xu, Shusheng; Yang, Zhi; Shu, Mengjun; He, Guili; Huang, Da; Zhang, Liling; Li, Li; Cui, Daxiang; Zhang, Yafei

    2015-09-01

    The desired control of particle size, doping element composition, and surface structure of carbon dots (CDs) are vital for understanding the fluorescence mechanism and exploring their potential applications. Herein, nitrogen-doped CDs (N-doped CDs) have been synthesized with tartaric acid and various alkylol amines (monoethanolamine, biethanolamine and triethanolamine) under microwave irradiation. A systematic investigation was performed to characterize the N-doped CDs. It is found that with increasing nitrogen proportion, the fluorescent quantum yield and lifetime of N-doped CDs increases, whereas cell toxicity decreases. In other words, N-doped CDs synthesized by tartaric acid and monoethanolamine have the highest nitrogen content, the highest fluorescent quantum yield, the longest lifetime and the lowest cell toxicity. A corresponding mechanism has been proposed. Moreover, as-synthesized N-doped CDs have been applied for selectively detecting the Fe3+ ion and writing letters as a fluorescent ink.The desired control of particle size, doping element composition, and surface structure of carbon dots (CDs) are vital for understanding the fluorescence mechanism and exploring their potential applications. Herein, nitrogen-doped CDs (N-doped CDs) have been synthesized with tartaric acid and various alkylol amines (monoethanolamine, biethanolamine and triethanolamine) under microwave irradiation. A systematic investigation was performed to characterize the N-doped CDs. It is found that with increasing nitrogen proportion, the fluorescent quantum yield and lifetime of N-doped CDs increases, whereas cell toxicity decreases. In other words, N-doped CDs synthesized by tartaric acid and monoethanolamine have the highest nitrogen content, the highest fluorescent quantum yield, the longest lifetime and the lowest cell toxicity. A corresponding mechanism has been proposed. Moreover, as-synthesized N-doped CDs have been applied for selectively detecting the Fe3+ ion and writing

  8. Fermi level pinning in Fe-doped PbTe under pressure

    SciTech Connect

    Skipetrov, E. P. Kruleveckaya, O. V.; Skipetrova, L. A.; Slynko, E. I.; Slynko, V. E.

    2014-07-14

    We synthesize an iron-doped PbTe single-crystal ingot and investigate the phase and the elemental composition as well as galvanomagnetic properties in weak magnetic fields (4.2 K≤T≤300 K, B ≤ 0.07 T) of Pb{sub 1−y}Fe{sub y}Te alloys upon varying the iron content, at atmospheric pressure and under hydrostatic compression up to 10 kilobars. We find an increase of iron concentration along the length of the ingot and the appearance of microscopic inclusions enriched with iron in the heavily doped samples. Lightly doped alloys are characterized by the p-type metal conductivity. An increase of the iron impurity content leads to a decrease in the free hole concentration, a stabilization of galvanomagnetic parameters, indicating the pinning of the Fermi energy by the iron resonant impurity level lying under the bottom of the valence band, and to the p-n inversion of the conductivity type. Under pressure, the free hole concentration in the sample, in which the stabilization of galvanomagnetic parameters takes place, increases by approximately a factor of four due to the flow of electrons from the valence band to the iron-induced resonant level. Using the two-band Kane and the six-band Dimmock dispersion relations, the pressure dependence of the Fermi energy is calculated. The model of the electronic structure rearrangement of Pb{sub 1−y}Fe{sub y}Te under pressure is proposed. The energy position and the pressure coefficient of the resonant iron impurity level are determined.

  9. Crystal field parameters and energy levels scheme of trivalent chromium doped BSO

    SciTech Connect

    Petkova, P.; Andreici, E.-L.; Avram, N. M.

    2014-11-24

    The aim of this paper is to give an analysis of crystal field parameters and energy levels schemes for the above doped material, in order to give a reliable explanation for experimental data. The crystal field parameters have been modeled in the frame of Exchange Charge Model (ECM) of the crystal field theory, taken into account the geometry of systems, with actually site symmetry of the impurity ions. The effect of the charges of the ligands and covalence bonding between chromium cation and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the crystal field parameters we simulated the scheme of energy levels of chromium ions by diagonalizing the matrix of the Hamiltonian of the doped crystal. The obtained energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison with experiment shows that the results are quite satisfactory which justify the model and simulation scheme used for the title system.

  10. Crystal field parameters and energy levels scheme of trivalent chromium doped BSO

    NASA Astrophysics Data System (ADS)

    Petkova, P.; Andreici, E.-L.; Avram, N. M.

    2014-11-01

    The aim of this paper is to give an analysis of crystal field parameters and energy levels schemes for the above doped material, in order to give a reliable explanation for experimental data. The crystal field parameters have been modeled in the frame of Exchange Charge Model (ECM) of the crystal field theory, taken into account the geometry of systems, with actually site symmetry of the impurity ions. The effect of the charges of the ligands and covalence bonding between chromium cation and oxygen anions, in the cluster approach, also were taken into account. With the obtained values of the crystal field parameters we simulated the scheme of energy levels of chromium ions by diagonalizing the matrix of the Hamiltonian of the doped crystal. The obtained energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data and discussed. Comparison with experiment shows that the results are quite satisfactory which justify the model and simulation scheme used for the title system.

  11. Study of spatial rings in TPPOH4 doped in boric acid glass

    NASA Astrophysics Data System (ADS)

    Rao Allam, Srinivasa; Dar, Mudasir H.; Venkatramaiah, N.; Venkatesan, R.; Sharan, Alok

    2015-02-01

    Single beam optical nonlinearity is studied in TPPOH4 doped in boric acid sandwiched films between two microscope glass slides at three different molar concentrations (4×10-4M, 1×10-4M, 5×10-5M). It shows absorption peak at 700nm with bandwidth of 70nm. We have used diode laser output at 671nm to probe resonant optical nonlinearities. We have observed interesting phenomena of formation of spatial concentric rings centered on the z-axis of the sample. To our knowledge this is first such observation of spatial rings in these systems. We have carried out studies to separate the contribution to the ring formation due to absorptive/refractive optical nonlinearity and the thermal nonlinearity.

  12. Polyaniline nanotubes and their dendrites doped with different naphthalene sulfonic acids

    SciTech Connect

    Zhang Zhiming; Wei Zhixiang; Zhang Lijuan; Wan Meixiang . E-mail: wanmx@iccas.ac.cn

    2005-03-01

    Polyaniline (PANI) nanotubes (130-250 nm in average diameter) doped with {alpha}-naphthalene sulfonic acid ({alpha}-NSA), {beta}-naphthalene sulfonic acid ({beta}-NSA) and 1,5-naphthalene disulfonic acid were synthesized via a self-assembly process. It was found that the formation yield, morphology (hollow or solid), size, crystalline and electrical properties of the nanostructures are affected by the position and number of -SO{sub 3}H groups attached to the naphthalene ring of NSA as well as the synthesis conditions. Moreover, these nanotubes aggregate to form a dendritic morphology when the polymerization is performed at a static state. The micelles composed of dopant or dopant/anilinium cations might act in a template-like fashion in forming self-assembled PANI nanotubes, which was further confirmed by X-ray diffraction measurements, while the aggregated morphology of the nanotubes might result from polymer chain interactions including {pi}-{pi} interactions, hydrogen and ionic bonds.

  13. N-doped carbon nanomaterials are durable catalysts for oxygen reduction reaction in acidic fuel cells

    PubMed Central

    Shui, Jianglan; Wang, Min; Du, Feng; Dai, Liming

    2015-01-01

    The availability of low-cost, efficient, and durable catalysts for oxygen reduction reaction (ORR) is a prerequisite for commercialization of the fuel cell technology. Along with intensive research efforts of more than half a century in developing nonprecious metal catalysts (NPMCs) to replace the expensive and scarce platinum-based catalysts, a new class of carbon-based, low-cost, metal-free ORR catalysts was demonstrated to show superior ORR performance to commercial platinum catalysts, particularly in alkaline electrolytes. However, their large-scale practical application in more popular acidic polymer electrolyte membrane (PEM) fuel cells remained elusive because they are often found to be less effective in acidic electrolytes, and no attempt has been made for a single PEM cell test. We demonstrated that rationally designed, metal-free, nitrogen-doped carbon nanotubes and their graphene composites exhibited significantly better long-term operational stabilities and comparable gravimetric power densities with respect to the best NPMC in acidic PEM cells. This work represents a major breakthrough in removing the bottlenecks to translate low-cost, metal-free, carbon-based ORR catalysts to commercial reality, and opens avenues for clean energy generation from affordable and durable fuel cells. PMID:26601132

  14. Visible light caffeic acid degradation by carbon-doped titanium dioxide.

    PubMed

    Venditti, Francesco; Cuomo, Francesca; Ceglie, Andrea; Avino, Pasquale; Russo, Mario Vincenzo; Lopez, Francesco

    2015-03-31

    The removal of the phenolic compound, caffeic acid, by photodegradation has been investigated using carbon-doped titanium dioxide particles as a photocatalyst under visible light. UV-vis absorption spectroscopy and gas chromatography-ion trap mass spectrometry analyses revealed a substrate concentration dependence of the removal of caffeic acid from a water solution. The k2 and t(0.5) parameters of each reaction were calculated by fitting kinetics data to a second-order kinetic adsorption model. To evaluate the photodegradation event, the effect of the adsorption process on the whole degradation was also monitored in the absence of light. Adsorption isotherm studies supported by ζ potential and scanning electron microscopy data demonstrated the pivotal role of the absorption mechanism. It was found that the whole photodegradation process is governed by a synergic mechanism in which adsorption and photodegradation are involved. This study, centered on the removal of caffeic acid from aqueous solutions, highlights the potential application of this technology for the elimination of phenolic compounds from olive mill wastewater, a fundamental goal in both the agronomical and environmental fields. PMID:25763603

  15. Ammonia Gas Sensing Behavior of Tanninsulfonic Acid Doped Polyaniline-TiO2 Composite

    PubMed Central

    Bairi, Venu Gopal; Bourdo, Shawn E.; Sacre, Nicolas; Nair, Dev; Berry, Brian C.; Biris, Alexandru S.; Viswanathan, Tito

    2015-01-01

    A highly active tannin doped polyaniline-TiO2 composite ammonia gas sensor was developed and the mechanism behind the gas sensing activity was reported for the first time. A tanninsulfonic acid doped polyaniline (TANIPANI)-titanium dioxide nanocomposite was synthesized by an in situ polymerization of aniline in the presence of tanninsulfonic acid and titanium dioxide nanoparticles. X-ray diffraction and thermogravimetric analysis were utilized to determine the incorporation of TiO2 in TANIPANI matrix. UV-Visible and infrared spectroscopy studies provided information about the electronic interactions among tannin, polyaniline, and TiO2. Scanning electron microscopy (SEM) along with energy dispersive X-ray spectroscopy (EDS) and atomic force microscopy (AFM) surface analysis techniques were used to investigate the metal oxide dispersions inside polyaniline matrix. Gas sensors were prepared by spin coating solutions of TANIPANI-TiO2 and TANIPANI composites onto glass slides. Sensors were tested at three different concentrations (20 ppm, 40 ppm, and 60 ppm) of ammonia gas at ambient temperature conditions by measuring the changes in surface resistivity of the films with respect to time. Ammonia gas sensing plots are presented showing the response values, response times and recovery times. The TANIPANI-TiO2 composite exhibited better response and shorter recovery times when compared to TANIPANI control and other polyaniline composites that have been reported in the literature. For the first time a proposed mechanism of gas sensing basing on the polaron band localization and its effects on the gas sensing behavior of polyaniline are reported. PMID:26501291

  16. Ammonia gas sensing behavior of tanninsulfonic acid doped polyaniline-TiO₂ composite.

    PubMed

    Bairi, Venu Gopal; Bourdo, Shawn E; Sacre, Nicolas; Nair, Dev; Berry, Brian C; Biris, Alexandru S; Viswanathan, Tito

    2015-01-01

    A highly active tannin doped polyaniline-TiO₂ composite ammonia gas sensor was developed and the mechanism behind the gas sensing activity was reported for the first time. A tanninsulfonic acid doped polyaniline (TANIPANI)-titanium dioxide nanocomposite was synthesized by an in situ polymerization of aniline in the presence of tanninsulfonic acid and titanium dioxide nanoparticles. X-ray diffraction and thermogravimetric analysis were utilized to determine the incorporation of TiO₂ in TANIPANI matrix. UV-Visible and infrared spectroscopy studies provided information about the electronic interactions among tannin, polyaniline, and TiO₂. Scanning electron microscopy (SEM) along with energy dispersive X-ray spectroscopy (EDS) and atomic force microscopy (AFM) surface analysis techniques were used to investigate the metal oxide dispersions inside polyaniline matrix. Gas sensors were prepared by spin coating solutions of TANIPANI-TiO₂ and TANIPANI composites onto glass slides. Sensors were tested at three different concentrations (20 ppm, 40 ppm, and 60 ppm) of ammonia gas at ambient temperature conditions by measuring the changes in surface resistivity of the films with respect to time. Ammonia gas sensing plots are presented showing the response values, response times and recovery times. The TANIPANI-TiO₂ composite exhibited better response and shorter recovery times when compared to TANIPANI control and other polyaniline composites that have been reported in the literature. For the first time a proposed mechanism of gas sensing basing on the polaron band localization and its effects on the gas sensing behavior of polyaniline are reported. PMID:26501291

  17. Deep level study of Mg-doped GaN using deep level transient spectroscopy and minority carrier transient spectroscopy

    NASA Astrophysics Data System (ADS)

    Duc, Tran Thien; Pozina, Galia; Amano, Hiroshi; Monemar, Bo; Janzén, Erik; Hemmingsson, Carl

    2016-07-01

    Deep levels in Mg-doped GaN grown by metal organic chemical vapor deposition (MOCVD), undoped GaN grown by MOCVD, and halide vapor phase epitaxy (HVPE)-grown GaN have been studied using deep level transient spectroscopy and minority charge carrier transient spectroscopy on Schottky diodes. One hole trap, labeled HT1, was detected in the Mg-doped sample. It is observed that the hole emission rate of the trap is enhanced by increasing electric field. By fitting four different theoretical models for field-assisted carrier emission processes, the three-dimensional Coulombic Poole-Frenkel (PF) effect, three-dimensional square well PF effect, phonon-assisted tunneling, and one-dimensional Coulombic PF effect including phonon-assisted tunneling, it is found that the one-dimensional Coulombic PF model, including phonon-assisted tunneling, is consistent with the experimental data. Since the trap exhibits the PF effect, we suggest it is acceptorlike. From the theoretical model, the zero field ionization energy of the trap and an estimate of the hole capture cross section have been determined. Depending on whether the charge state is -1 or -2 after hole emission, the zero field activation energy Ei 0 is 0.57 eV or 0.60 eV, respectively, and the hole capture cross section σp is 1.3 ×10-15c m2 or 1.6 ×10-16c m2 , respectively. Since the level was not observed in undoped GaN, it is suggested that the trap is associated with an Mg related defect.

  18. The thickness design of unintentionally doped GaN interlayer matched with background doping level for InGaN-based laser diodes

    NASA Astrophysics Data System (ADS)

    Chen, P.; Zhao, D. G.; Jiang, D. S.; Zhu, J. J.; Liu, Z. S.; Yang, J.; Li, X.; Le, L. C.; He, X. G.; Liu, W.; Li, X. J.; Liang, F.; Zhang, B. S.; Yang, H.; Zhang, Y. T.; Du, G. T.

    2016-03-01

    In order to reduce the internal optical loss of InGaN laser diodes, an unintentionally doped GaN (u-GaN) interlayer is inserted between InGaN/GaN multiple quantum well active region and Al0.2Ga0.8N electron blocking layer. The thickness design of u-GaN interlayer matching up with background doping level for improving laser performance is studied. It is found that a suitably chosen u-GaN interlayer can well modulate the optical absorption loss and optical confinement factor. However, if the value of background doping concentration of u-GaN interlayer is too large, the output light power may decrease. The analysis of energy band diagram of a LD structure with 100 nm u-GaN interlayer shows that the width of n-side depletion region decreases when the background concentration increases, and may become even too small to cover whole MQW, resulting in a serious decrease of the output light power. It means that a suitable interlayer thickness design matching with the background doping level of u-GaN interlayer is significant for InGaN-based laser diodes.

  19. KDP crystal doped with L-arginine amino acid: growth, structure perfection, optical and strength characteristics

    NASA Astrophysics Data System (ADS)

    Pritula, I. M.; Kostenyukova, E. I.; Bezkrovnaya, O. N.; Kolybaeva, M. I.; Sofronov, D. S.; Dolzhenkova, E. F.; Kanaev, A.; Tsurikov, V.

    2016-07-01

    Potassium Dihydrogen Phosphate (KDP) crystal doped with L-arginine (L-arg) amino acid with 1.4 wt% concentration in the solution was grown onto a point seed by the method of temperature reduction. For the first time an attempt was made to grow large-size (7 × 6 × 8 cm3) optically transparent crystals, which allowed to analyze the effect of L-arg additive on the physical properties of the different growth sectors ({100} and {101}) of KDP. The incorporation of L-arg into both growth sectors of the crystal was confirmed by the methods of optical and IR spectroscopy and found to be caused by the ability of the amino acid to form hydrogen bonds with the face {100} and electrostatically interact with the positively charged face {101} of KDP crystal. A slight variation in the unit cell parameters was reported, the elementary cell volume of KDP:L-arg crystal increased in comparison with the one of pure KDP by 2·10-2 and 2.07·10-2 Å3 in the sectors {100} and {101}, respectively. It was found that the doping of L-arg enhanced the SHG efficiency of KDP and depended on the crystal growth sectors. The SHG efficiency of KDP:L-arg was by a factor 2.53 and 3.95 higher in comparison with those of pure KDP for {101} and {100} growth sector, respectively. The doping was found to lead to softening of both faces by ∼3-10% and ∼14-17% in the sectors {101} and {100}, respectively. Investigation of the influence of L-arg molecules on the bulk laser damage threshold of the crystals showed that the bulk laser damage threshold of the samples of KDP:L-arg crystal was higher than the one of the pure crystal in the sector {101} and lower in the sector {100}. The correlation between microhardness and laser damage threshold were discussed. The study is helpful for further searching, designing and simulation of hybrid NLO materials.

  20. Charge transition levels of Mn-doped Si calculated with the GGA-1/2 method

    NASA Astrophysics Data System (ADS)

    Matusalem, Filipe; Pelá, Ronaldo R.; Marques, Marcelo; Teles, Lara K.

    2014-12-01

    Although Mn impurities are promising to bring Si, the most widespread semiconductor employed in electronic devices, into the spintronics realm, few theoretical works exist that calculate the charge transition levels of Mn in Si. Among these works, none of them makes use of gap correction methods. To fill this void, we performed first principles calculations for Mn-doped Si, using the GGA-1/2 method, which approximately includes quasiparticle corrections at a small computational price. Our results improve the theoretical description of these charge transition levels, achieving good agreement with experimental results for interstitial and substitutional sites. Furthermore, the GGA-1/2 method allowed us to use reasonably large supercells, up to 217 atoms.

  1. An efficient hydrogenation catalyst in sulfuric acid for the conversion of nitrobenzene to p-aminophenol: N-doped carbon with encapsulated molybdenum carbide.

    PubMed

    Wang, Tao; Dong, Zhen; Cai, Weimeng; Wang, Yongzheng; Fu, Teng; Zhao, Bin; Peng, Luming; Ding, Weiping; Chen, Yi

    2016-08-23

    The transfer of catalytic function from molybdenum carbide to N-doped carbon has been tested by encapsulating molybdenum carbide with N-doped carbon using a one-pot preparation process. The outer layer of N-doped carbon, inert itself, exhibits high activity and excellent selectivity with molybdenum carbide as the catalyst for the hydrogenation of nitrobenzene to p-aminophenol in sulfuric acid. PMID:27506592

  2. Periodic Modulation of the Doping Level in Striped MoS2 Superstructures.

    PubMed

    Zhou, Xiebo; Shi, Jianping; Qi, Yue; Liu, Mengxi; Ma, Donglin; Zhang, Yu; Ji, Qingqing; Zhang, Zhepeng; Li, Cong; Liu, Zhongfan; Zhang, Yanfeng

    2016-03-22

    Although the recently discovered monolayer transition metal dichalcogenides exhibit novel electronic and optical properties, fundamental physical issues such as the quasiparticle bandgap tunability and the substrate effects remain undefined. Herein, we present the report of a quasi-one-dimensional periodically striped superstructure for monolayer MoS2 on Au(100). The formation of the unique striped superstructure is found to be mainly modulated by the symmetry difference between MoS2 and Au(100) and their lattice mismatch. More intriguingly, we find that the monolayer MoS2 is heavily n-doped on the Au(100) facet with a bandgap of 1.3 eV, and the Fermi level is upshifted by ∼0.10 eV on the ridge (∼0.2 eV below the conduction band) in contrast to the valley regions (∼0.3 eV below the conduction band) of the striped patterns after high-temperature sample annealing process. This tunable doping effect is considered to be caused by the different defect densities over the ridge/valley regions of the superstructure. Additionally, an obvious bandgap reduction is observed in the vicinity of the domain boundary for monolayer MoS2 on Au(100). This work should therefore inspire intensive explorations of adlayer-substrate interactions, the defects, and their effects on band-structure engineering of monolayer MoS2. PMID:26913990

  3. Strong compensation hinders the p-type doping of ZnO: a glance over surface defect levels

    NASA Astrophysics Data System (ADS)

    Huang, B.

    2016-07-01

    We propose a surface doping model of ZnO to elucidate the p-type doping and compensations in ZnO nanomaterials. With an N-dopant, the effects of N on the ZnO surface demonstrate a relatively shallow acceptor level in the band gap. As the dimension of the ZnO materials decreases, the quantum confinement effects will increase and render the charge transfer on surface to influence the shifting of Fermi level, by evidence of transition level changes of the N-dopant. We report that this can overwhelm the intrinsic p-type conductivity and transport of the ZnO bulk system. This may provide a possible route of using surface doping to modify the electronic transport and conductivity of ZnO nanomaterials.

  4. The effect and mechanism of bismuth doped lead oxide on the performance of lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Chen, H. Y.; Wu, L.; Ren, C.; Luo, Q. Z.; Xie, Z. H.; Jiang, X.; Zhu, S. P.; Xia, Y. K.; Luo, Y. R.

    Flooded automotive and motorcycle lead-acid batteries were manufactured from three kinds of lead oxides including electrolyzed pure lead (99.99 wt.% Pb) oxide, electrolyzed pure lead oxide doped with Bi 2O 3 (0.02 wt.% Bi 2O 3) and bismuth-bearing refined lead (0.02 wt.% Bi) oxide. The first cranking and cold cranking curves of the automotive batteries show that there is no obvious difference among the above lead oxides. Bismuth in lead oxide does not affect the water loss of flooded batteries. However, bismuth results in the improvement of capacity and charge-acceptance capability. In discharge, the positive voltage versus cadmium of plates with bismuth decreases more slowly than that of plates without bismuth. In order to investigate the mechanism of the function of bismuth, three other kinds of test electrodes were prepared from electrolyzed pure lead (99.99 wt.% Pb) oxide, electrolyzed pure lead oxide doped 0.02 wt.% Bi 2O 3 and electrolyzed pure lead oxide doped 0.06 wt.% Bi 2O 3. The cyclic voltammetry curve shows that bismuth has no significant influence on the electrochemical behavior of the positive active-material. There is an opposite result concerning the cathodic polarization curves between bismuth doped in the electrode and Bi 3+ ion doped in the electrolyte. Bismuth doped in the electrode results in a decrease of the hydrogen overpotential. Conversely, Bi 3+ ion doped in the electrolyte results is an increase. The chemical analysis confirms that a trace of Bi 3+ ion exists in sulfuric acid solution (e.g. plates soaking, after formation, after cycling). A higher porosity is observed in the positive active-material containing bismuth by SEM technique. SEM morphology shows that needle-like crystals begin to occur after a few cycles. X-ray diffraction phase analysis proves that the amount of α-PbO 2 is increased by doping bismuth in to lead oxide. The existing forms, chemical characteristics and electrochemical reactions of bismuth during manufacture

  5. High Chloride Doping Levels Stabilize the Perovskite Phase of Cesium Lead Iodide.

    PubMed

    Dastidar, Subham; Egger, David A; Tan, Liang Z; Cromer, Samuel B; Dillon, Andrew D; Liu, Shi; Kronik, Leeor; Rappe, Andrew M; Fafarman, Aaron T

    2016-06-01

    Cesium lead iodide possesses an excellent combination of band gap and absorption coefficient for photovoltaic applications in its perovskite phase. However, this is not its equilibrium structure under ambient conditions. In air, at ambient temperature it rapidly transforms to a nonfunctional, so-called yellow phase. Here we show that chloride doping, particularly at levels near the solubility limit for chloride in a cesium lead iodide host, provides a new approach to stabilizing the functional perovskite phase. In order to achieve high doping levels, we first co-deposit colloidal nanocrystals of pure cesium lead chloride and cesium lead iodide, thereby ensuring nanometer-scale mixing even at compositions that potentially exceed the bulk miscibility of the two phases. The resulting nanocrystal solid is subsequently fused into a polycrystalline thin film by chemically induced, room-temperature sintering. Spectroscopy and X-ray diffraction indicate that the chloride is further dispersed during sintering and a polycrystalline mixed phase is formed. Using density functional theory (DFT) methods in conjunction with nudged elastic band techniques, low-energy pathways for interstitial chlorine diffusion into a majority-iodide lattice were identified, consistent with the facile diffusion and fast halide exchange reactions observed. By comparison to DFT-calculated values (with the PBE exchange-correlation functional), the relative change in band gap and the lattice contraction are shown to be consistent with a Cl/I ratio of a few percent in the mixed phase. At these incorporation levels, the half-life of the functional perovskite phase in a humid atmosphere increases by more than an order of magnitude. PMID:27135266

  6. Effects of thickness, dopant type and doping levels of flexible nanoscale polyaniline films on responses to gases

    NASA Astrophysics Data System (ADS)

    Sinha, Mousumi; Panda, Siddhartha

    2015-07-01

    While doped nanoscale (sub-100 nm) polyaniline films have shown interesting behavior with respect to electrical conductivities and thermal sensing, there has been scant attention to responses of such films to gases. In this work, a detailed study on the effects of film thicknesses, doping levels and dopant types on the responses to different gases is presented. The responses to NO2 were higher than to NO and NH3, and the films were unresponsive to N2, O2, CO2 and H2. The responses to NO2 and NH3 increased with decrease in film thickness below about 50 nm and were prominent at lower doping levels, and also were dependent on the type of dopant used. Explanations for the experimental observations were provided based on energy considerations. The modulation of the calculated LUMO levels and band gaps, and the Fermi energy levels at lower film thicknesses and doping levels correlated well with the responses. As the transfer of electrons resulting in the formation of the charge complex depends on the difference between the Fermi level of the film and the Mulliken electronegativity of the gas molecules, this difference in the energy levels also correlated with the effects of different gases and different dopants. Limited tests on the effect of water vapor were conducted.

  7. Enhanced photocatalytic activity of sprayed Au doped ferric oxide thin films for salicylic acid degradation in aqueous medium.

    PubMed

    Mahadik, M A; Shinde, S S; Kumbhar, S S; Pathan, H M; Rajpure, K Y; Bhosale, C H

    2015-01-01

    Various doping percentage of Au were successfully introduced into the Fe2O3 photocatalysts via a spray pyrolysis method different. The effect of Au doping on photoelectrochemical, structural, optical and morphological properties of these deposited thin films is studied. The PEC characterization shows that, the photocurrent increases gradually with increasing Au content initially up to 2at.% indicating the maximum values of short circuit current (Isc) and open circuit voltage (Voc) are (Isc=90μA and Voc=220.5mV) and then decreases after exceeding the optimal Au doping content. Therefore, the photocurrent of Au doped Fe2O3 photocatalysts can be adjusted by the Au content. Deposited films are polycrystalline with a rhombohedral crystal structure having (104) preferred orientation. SEM and AFM images show deposited thin films are compact and uniform. The photocatalytic activities of the Fe2O3 and Au:Fe2O3 photocatalyst were evaluated by photoelectrocatalytic degradation of salicylic acid under sunlight irradiation. The results show that the Au:Fe2O3 thin film photocatalyst exhibited about 45% more degradation of pollutants than the pure Fe2O3. Thus, in Au doped Fe2O3 photocatalysts, the interaction between Au and Fe2O3 reduces the recombination of photogenerated charge carriers and improve the photocatalytic activity. PMID:25496876

  8. Increased isoprostane levels in oleic acid-induced lung injury

    SciTech Connect

    Ono, Koichi; Koizumi, Tomonobu; Tsushima, Kenji; Yoshikawa, Sumiko; Yokoyama, Toshiki; Nakagawa, Rikimaru; Obata, Toru

    2009-10-16

    The present study was performed to examine a role of oxidative stress in oleic acid-induced lung injury model. Fifteen anesthetized sheep were ventilated and instrumented with a lung lymph fistula and vascular catheters for blood gas analysis and measurement of isoprostanes (8-epi prostaglandin F2{alpha}). Following stable baseline measurements, oleic acid (0.08 ml/kg) was administered and observed 4 h. Isoprostane was measured by gas chromatography mass spectrometry with the isotope dilution method. Isoprostane levels in plasma and lung lymph were significantly increased 2 h after oleic acid administration and then decreased at 4 h. The percent increases in isoprostane levels in plasma and lung lymph at 2 h were significantly correlated with deteriorated oxygenation at the same time point, respectively. These findings suggest that oxidative stress is involved in the pathogenesis of the pulmonary fat embolism-induced acute lung injury model in sheep and that the increase relates with the deteriorated oxygenation.

  9. Relationship between Uric Acid Level and Achievement Motivation. Final Report.

    ERIC Educational Resources Information Center

    Mueller, Ernst F.; French, John R. P., Jr.

    In an investigation of the relationship of uric acid (a metabolic end product) to achievement, this study hypothesized that a person's serum urate level (a factor often associated with gout) is positively related to achievement need as well as indicators of actual achievement. (Speed of promotion and number of yearly publications were chosen as…

  10. Observation of Landau levels on nitrogen-doped flat graphite surfaces without external magnetic fields

    NASA Astrophysics Data System (ADS)

    Kondo, Takahiro; Guo, Donghui; Shikano, Taishi; Suzuki, Tetsuya; Sakurai, Masataka; Okada, Susumu; Nakamura, Junji

    2015-11-01

    Under perpendicular external magnetic fields, two-dimensional carriers exhibit Landau levels (LLs). However, it has recently been reported that LLs have been observed on graphene and graphite surfaces without external magnetic fields being applied. These anomalous LLs have been ascribed primarily to a strain of graphene sheets, leading to in-plane hopping modulation of electrons. Here, we report the observation of the LLs of massive Dirac fermions on atomically flat areas of a nitrogen-doped graphite surface in the absence of external magnetic fields. The corresponding magnetic fields were estimated to be as much as approximately 100 T. The generation of the LLs at the area with negligible strain can be explained by inequivalent hopping of π electrons that takes place at the perimeter of high-potential domains surrounded by positively charged substituted graphitic-nitrogen atoms.

  11. Observation of Landau levels on nitrogen-doped flat graphite surfaces without external magnetic fields

    PubMed Central

    Kondo, Takahiro; Guo, Donghui; Shikano, Taishi; Suzuki, Tetsuya; Sakurai, Masataka; Okada, Susumu; Nakamura, Junji

    2015-01-01

    Under perpendicular external magnetic fields, two-dimensional carriers exhibit Landau levels (LLs). However, it has recently been reported that LLs have been observed on graphene and graphite surfaces without external magnetic fields being applied. These anomalous LLs have been ascribed primarily to a strain of graphene sheets, leading to in-plane hopping modulation of electrons. Here, we report the observation of the LLs of massive Dirac fermions on atomically flat areas of a nitrogen-doped graphite surface in the absence of external magnetic fields. The corresponding magnetic fields were estimated to be as much as approximately 100 T. The generation of the LLs at the area with negligible strain can be explained by inequivalent hopping of π electrons that takes place at the perimeter of high-potential domains surrounded by positively charged substituted graphitic-nitrogen atoms. PMID:26549618

  12. Investigation of the origin of deep levels in CdTe doped with Bi

    SciTech Connect

    Saucedo, E.; Franc, J.; Elhadidy, H.; Horodysky, P.; Ruiz, C. M.; Bermudez, V.; Sochinskii, N. V.

    2008-05-01

    Combining optical (low temperature photoluminescence), electrical (thermoelectric effect spectroscopy), and structural (synchrotron X-ray powder diffraction) methods, the defect structure of CdTe doped with Bi was studied in crystals with dopant concentration in the range of 10{sup 17}-10{sup 19} at./cm{sup 3}. The semi-insulating state observed in crystals with low Bi concentration is assigned to the formation of a shallow donor level and a deep donor recombination center. Studying the evolution of lattice parameter with temperature, we postulate that the deep center is formed by a Te-Te dimer and their formation is explained by a tetrahedral to octahedral distortion, due to the introduction of Bi in the CdTe lattice. We also shows that this model agrees with the electrical, optical, and transport charge properties of the samples.

  13. Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors

    PubMed Central

    2013-01-01

    Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail. PMID:24369051

  14. Observation of an electron band above the Fermi level in FeTe₀.₅₅Se₀.₄₅ from in-situ surface doping

    DOE PAGESBeta

    Zhang, P.; Richard, P.; Xu, N.; Xu, Y. -M.; Ma, J.; Qian, T.; Fedorov, A. V.; Denlinger, J. D.; Gu, G. D.; Ding, H.

    2014-10-27

    We used in-situ potassium (K) evaporation to dope the surface of the iron-based superconductor FeTe₀.₅₅Se₀.₄₅. The systematic study of the bands near the Fermi level confirms that electrons are doped into the system, allowing us to tune the Fermi level of this material and to access otherwise unoccupied electronic states. In particular, we observe an electron band located above the Fermi level before doping that shares similarities with a small three-dimensional pocket observed in the cousin, heavily-electron-doped KFe₂₋xSe₂ compound.

  15. Observation of an electron band above the Fermi level in FeTe₀.₅₅Se₀.₄₅ from in-situ surface doping

    SciTech Connect

    Zhang, P.; Richard, P.; Xu, N.; Xu, Y. -M.; Ma, J.; Qian, T.; Fedorov, A. V.; Denlinger, J. D.; Gu, G. D.; Ding, H.

    2014-10-27

    We used in-situ potassium (K) evaporation to dope the surface of the iron-based superconductor FeTe₀.₅₅Se₀.₄₅. The systematic study of the bands near the Fermi level confirms that electrons are doped into the system, allowing us to tune the Fermi level of this material and to access otherwise unoccupied electronic states. In particular, we observe an electron band located above the Fermi level before doping that shares similarities with a small three-dimensional pocket observed in the cousin, heavily-electron-doped KFe₂₋xSe₂ compound.

  16. Nitrogen doped carbon nanotubes with encapsulated ferric carbide as excellent electrocatalyst for oxygen reduction reaction in acid and alkaline media

    NASA Astrophysics Data System (ADS)

    Zhong, Guoyu; Wang, Hongjuan; Yu, Hao; Peng, Feng

    2015-07-01

    Nitrogen doped carbon nanotubes (NCNTs) with encapsulated Fe3C nanoparticles (Fe3C@NCNTs) are synthesized by a simple direct pyrolysis of melamine and ferric chloride. The characterization results reveal that Fe3C is mainly encapsulated in the interior of NCNTs and N species is mainly distributed on the outside surface of NCNTs. Iron and iron carbide catalyze the growth of NCNTs and are wrapped by carbon to form Fe3C@NCNTs. The as-prepared Fe3C@NCNTs catalyst exhibits superior oxygen reduction reaction (ORR) activity, excellent methanol tolerance and long-term stability in both acid and alkaline media. It is proven that the doped N is the main active site for ORR and the inner Fe3C with outside carbon form the synergetic active site to enhance ORR activity. The ORR mechanism of direct four electron transfer pathway is proved in acid and alkaline media.

  17. Improvement of holographic thermal stability in phenanthrenequinone-doped poly(methyl methacrylate-co-methacrylic acid) photopolymer

    NASA Astrophysics Data System (ADS)

    Yu, Dan; Liu, Hongpeng; Wang, Heng; Wang, Jian; Jiang, Yongyuan; Sun, Xiudong

    2011-08-01

    Experimental studies of holographic thermal stability in phenanthrenequinone (PQ)-doped poly(methyl methacrylate-co-methacrylic acid) [P(MMA-co-MAA)] photopolymers are presented. A possibility to improve the thermal stability of holograms is demonstrated by doping methacrylic acid (MAA) into the poly(methyl methacrylate) (PMMA) polymer matrix. MAA as a copolymerization monomer can form a more stable polymer matrix with methyl methacrylate (MMA) monomer and increase average molecular weight of photoproducts, which finally depress the diffusion of photoproduct. The optimized MAA concentration copolymerized into P(MMA-co-MAA) polymer matrix can bring nearly a month's lifetime of gratings, which is obviously an improvement over the usual PQ-PMMA material under thermal treatment.

  18. Puget Sound acidity levels drop after ASARCO shutdown

    SciTech Connect

    Not Available

    1987-07-01

    The levels of acidity in Puget Sound region rainfall have decreased significantly since the shutdown of the ASARCO copper smelter in Tacoma, Washington, according to a study funded by the US Environmental Protection Agency. Results indicate that sulfate and hydrogen ion concentrations obtained from samples taken before the closure were significantly different than those collected after the shutdown. Rainwater samples collected downwind during smelter operation were also significantly different from those collected upwind. Sulfur dioxide is considered to be one of the principal contributors to acid rain. The smelter was a major source of sulfur dioxide emissions in the Puget Sound region before it shut down in March 1985.

  19. Sulfuric acid doped poly diaminopyridine/graphene composite to remove high concentration of toxic Cr(VI).

    PubMed

    Dinda, Diptiman; Kumar Saha, Shyamal

    2015-06-30

    Sulfuric acid doped diaminopyridine polymers are synthesized in situ on graphene oxide surface via mutual oxidation-reduction technique. Exploiting large and highly porous surface, we have used this polymer composite as an adsorbent to remove high concentration of toxic Cr(VI) from water. It shows very high adsorption capacity (609.76 mg g(-1)) during removal process. The composite takes only 100 min to remove high concentration of 500 mg L(-1) Cr(VI) from water. Interesting features for this material is the enhancement of removal efficiency at lower acidic condition due to the formation of acid doped emeraldine salt during polymerization. XPS and AAS measurements reveal that our prepared material mainly follows reduction mechanism at higher acidic condition while anions exchange mechanism at lower acidic condition during the removal experiments. Good recycling ability with ∼ 92% removal efficiency after fifth cycle is also noticed for this material. Easy preparation, superior stability in acidic condition, remarkable removal efficiency and excellent recycling ability make this polymer composite an efficient material for modern filtration units in waste water purification. PMID:25771215

  20. Fluorine-Doped and Partially Oxidized Tantalum Carbides as Nonprecious Metal Electrocatalysts for Methanol Oxidation Reaction in Acidic Media.

    PubMed

    Yue, Xin; He, Chunyong; Zhong, Chengyong; Chen, Yuanping; Jiang, San Ping; Shen, Pei Kang

    2016-03-16

    A nonprecious metal electrocatalyst based on fluorine-doped tantalum carbide with an oxidative surface on graphitized carbon (TaCx FyOz/(g)C) is developed by using a simple one-pot in situ ion exchange and adsorption method, and the TaCxFyOz/(g)C shows superior performance and durability for methanol oxidation reaction and extreme tolerance to CO poisoning in acidic media. PMID:26779940

  1. Circulating Docosahexaenoic Acid Levels Are Associated with Fetal Insulin Sensitivity

    PubMed Central

    Zhao, Jin-Ping; Levy, Emile; Fraser, William D.; Julien, Pierre; Delvin, Edgard; Montoudis, Alain; Spahis, Schohraya; Garofalo, Carole; Nuyt, Anne Monique; Luo, Zhong-Cheng

    2014-01-01

    Background Arachidonic acid (AA; C20∶4 n-6) and docosahexaenoic acid (DHA; C22∶6 n-3) are important long-chain polyunsaturated fatty acids (LC-PUFA) in maintaining pancreatic beta-cell structure and function. Newborns of gestational diabetic mothers are more susceptible to the development of type 2 diabetes in adulthood. It is not known whether low circulating AA or DHA is involved in perinatally “programming” this susceptibility. This study aimed to assess whether circulating concentrations of AA, DHA and other fatty acids are associated with fetal insulin sensitivity or beta-cell function, and whether low circulating concentrations of AA or DHA are involved in compromised fetal insulin sensitivity in gestational diabetic pregnancies. Methods and Principal Findings In a prospective singleton pregnancy cohort, maternal (32-35 weeks gestation) and cord plasma fatty acids were assessed in relation to surrogate indicators of fetal insulin sensitivity (cord plasma glucose-to-insulin ratio, proinsulin concentration) and beta-cell function (proinsulin-to-insulin ratio) in 108 mother-newborn pairs. Cord plasma DHA levels (in percentage of total fatty acids) were lower comparing newborns of gestational diabetic (n = 24) vs. non-diabetic pregnancies (2.9% vs. 3.5%, P = 0.01). Adjusting for gestational age at blood sampling, lower cord plasma DHA levels were associated with lower fetal insulin sensitivity (lower glucose-to-insulin ratio, r = 0.20, P = 0.036; higher proinsulin concentration, r = −0.37, P <0.0001). The associations remained after adjustment for maternal and newborn characteristics. Cord plasma saturated fatty acids C18∶0 and C20∶0 were negatively correlated with fetal insulin sensitivity, but their levels were not different between gestational diabetic and non-diabetic pregnancies. Cord plasma AA levels were not correlated with fetal insulin sensitivity. Conclusion Low circulating DHA levels are associated with compromised

  2. ELECTROCHEMICAL PROPERTIES, MECHANICAL TESTING, AND GEL MORPHOLOGY STUDY OF PHOSPHORIC ACID-DOPED META-POLYBENZIMIDAZOLE MEMBRANES VIA CONVENTIONALLY IMBIBING AND THE SOL-GEL PROCESS

    SciTech Connect

    Perry, Kelly A; More, Karren Leslie; Benicewicz, Brian

    2009-01-01

    Proton exchange membrane (PEM) research has been directed at phosphoric acid (PA)-doped polybenzimidazole (PBI) membranes since the 1990s. PEM fuel cells based on PA-doped PBI membranes produced via a sol-gel transition process have achieved lifetimes >10,000hrs with low degradation rates. It has been suggested that the gel morphology of the PA-doped PBI membranes is responsible for their excellent electrochemical performance. Thus, a study has been underway to characterize the microstructure of PA-doped PBI membranes, and to correlate structure with performance. However, PA-doped PBI membranes present special challenges for microscopy analysis, as these membranes are extremely sensitive to the electron beam and high vacuum conditions. This paper will discuss and compare the mechanical, electrochemical, and cryo-SEM analyses of PA-doped meta-PBI membranes produced via conventional imbibing and the sol-gel process.

  3. Z-scan measurements of single walled carbon nanotube doped acetylenedicarboxylic acid polymer under CW laser

    NASA Astrophysics Data System (ADS)

    Zidan, M. D.; Allaf, A. W.; Allahham, A.; AL-Zier, A.

    2016-06-01

    Z-scan measurements of single walled carbon nanotube (SWCNT) doped with acetylenedicarboxylic acid (ADC) polymer are performed using a CW diode laser at 635 nm wavelength with 17 mW power. The nonlinear absorption coefficient (β), nonlinear refractive index (n2), the real and imaginary parts of the third-order nonlinear optical susceptibility (Re χ3), (Im χ3) of the investigated samples are calculated. It was found that the β values decrease with increase in on-axis input intensity I0. Also, these values are found to be proportional with sample concentrations. The excited-state absorption cross sections were calculated to be at σex=5.08×10-14 cm2 for the (SWCNT) and at 15.1×10-14 cm2 for the ADC polymer. It was found that the σex is larger than ground-state absorption cross sections, indicating that the reverse saturable absorption mechanism (RSA) is the dominating mechanism for the observed absorption nonlinearities.

  4. Comparison of chondroitin sulfate and hyaluronic Acid doped conductive polypyrrole films for adipose stem cells.

    PubMed

    Björninen, Miina; Siljander, Aliisa; Pelto, Jani; Hyttinen, Jari; Kellomäki, Minna; Miettinen, Susanna; Seppänen, Riitta; Haimi, Suvi

    2014-09-01

    Polypyrrole (PPy) is a conductive polymer that has aroused interest due to its biocompatibility with several cell types and high tailorability as an electroconductive scaffold coating. This study compares the effect of hyaluronic acid (HA) and chondroitin sulfate (CS) doped PPy films on human adipose stem cells (hASCs) under electrical stimulation. The PPy films were synthetized electrochemically. The surface morphology of PPy-HA and PPy-CS was characterized by an atomic force microscope. A pulsed biphasic electric current (BEC) was applied via PPy films non-stimulated samples acting as controls. Viability, attachment, proliferation and osteogenic differentiation of hASCs were evaluated by live/dead staining, DNA content, Alkaline phosphatase activity and mineralization assays. Human ASCs grew as a homogenous cell sheet on PPy-CS surfaces, whereas on PPy-HA cells clustered into small spherical structures. PPy-CS supported hASC proliferation significantly better than PPy-HA at the 7 day time point. Both substrates equally triggered early osteogenic differentiation of hASCs, although mineralization was significantly induced on PPy-CS compared to PPy-HA under BEC. These differences may be due to different surface morphologies originating from the CS and HA dopants. Our results suggest that PPy-CS in particular is a potential osteogenic scaffold coating for bone tissue engineering. PMID:24823653

  5. High Level Waste System Impacts from Acid Dissolution of Sludge

    SciTech Connect

    KETUSKY, EDWARD

    2006-04-20

    This research evaluates the ability of OLI{copyright} equilibrium based software to forecast Savannah River Site High Level Waste system impacts from oxalic acid dissolution of Tank 1-15 sludge heels. Without further laboratory and field testing, only the use of oxalic acid can be considered plausible to support sludge heel dissolution on multiple tanks. Using OLI{copyright} and available test results, a dissolution model is constructed and validated. Material and energy balances, coupled with the model, identify potential safety concerns. Overpressurization and overheating are shown to be unlikely. Corrosion induced hydrogen could, however, overwhelm the tank ventilation. While pH adjustment can restore the minimal hydrogen generation, resultant precipitates will notably increase the sludge volume. OLI{copyright} is used to develop a flowsheet such that additional sludge vitrification canisters and other negative system impacts are minimized. Sensitivity analyses are used to assess the processability impacts from variations in the sludge/quantities of acids.

  6. Energy levels fitting and crystal-field calculations of Nd3+ doped in GYSGG crystal

    NASA Astrophysics Data System (ADS)

    Gao, Jinyun; Zhang, Qingli; Sun, Dunlu; Luo, Jianqiao; Liu, Wenpeng; Yin, Shaotang

    2012-10-01

    The single crystal Nd3+-doped in GdY2Sc2Ga3O12 (Nd3+:GYSGG) was grown by Czochralski method successfully, and its absorption spectra was analyzed in a wider spectral wavelength range at 7.6 K and 300 K, respectively. The free-ions and crystal-field parameters were fitted to the experimental energy levels at 7.6 K and 300 K with the root mean square deviation of 11.25 and 12.48 cm-1, respectively. According to the crystal-field calculations, 116 levels of Nd3+ at 7.6 K and 114 levels of Nd3+ at 300 K were assigned. The fitting results of free-ions and crystal-field parameters were compared with those already reported of Nd3+:GSGG and Nd3+:YSAG. The results indicated that the free-ions parameters are similar to those of the Nd3+ in GYSGG, GSGG and YSAG crystals, and the crystal-field interaction of GSGG and YSAG is stronger than that of GYSGG, which results in the dual-wavelength properties of Nd3+:GYSGG crystal.

  7. The complexities of anti-doping violations: a case study of sanctioned cases in all performance levels of USA cycling

    PubMed Central

    Henning, April D; Dimeo, Paul

    2015-01-01

    The use of banned substances and techniques in sport is regulated by anti-doping rules co-ordinated by the World Anti-Doping Agency. The purposes of these rules are to protect the health of the athlete, the level playing field and what WADA refers to as the spirit of sport. In this article, we review the known cases of sanctions in USA cycling since 2001. We show that the diversity of cases expands upon the simplistic, one-dimensional understanding of doping as risky and cheating. Contrary to this paradigm, we establish a typology of cases that challenges the one size fits all approach and, more specifically, we argue that WADA should develop new policies with independent standards for amateur and masters athletes. PMID:26688790

  8. Pig bones derived N-doped carbon with multi-level pores as electrocatalyst for oxygen reduction

    NASA Astrophysics Data System (ADS)

    Wang, Rongfang; Wang, Kai; Wang, Zihan; Song, Huihui; Wang, Hui; Ji, Shan

    2015-11-01

    In this work, a N-doped highly porous carbon material with multi-level pores and high activity for oxygen reduction reaction (ORR) is successfully prepared by carbonizing pig bones instead of separated carbon/nitrogen-containing and template precursors. The N-doped porous carbon material has high specific surface area of ca. 562.6 m2 g-1. Due to its high surface area and N-doped active sites, the ORR activity of obtained carbon in alkaline media is higher than that of commercial Pt/C catalyst (10 wt.%). In addition, it shows a higher methanol tolerance than Pt/C catalyst and long term-operating stability, rendering it as promising ORR catalyst material for fuel cells.

  9. Lowering the platinum loading of high temperature polymer electrolyte membrane fuel cells with acid doped polybenzimidazole membranes

    NASA Astrophysics Data System (ADS)

    Martin, S.; Li, Q.; Jensen, J. O.

    2015-10-01

    Membrane electrode assemblies (MEAs) with ultra-low Pt loading electrodes were prepared for high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) based on acid doped polybenzimidazole. With no electrode binders or ionomers, the triple phase boundary of the catalyst layer was established by the acid transfer from the acid doped membrane to the electrodes and can therefore be tailored by using catalysts with varied Pt to C ratios. With a loading of ca. 0.1 mgPtcm-2 on each electrode the best performance was obtained with electrodes prepared from 10 wt.% Pt/C due to the improved Pt dispersion, extended triple phase boundary upon the acid transfer and the alleviated acid flooding of the catalytic layer. The MEA delivered a peak power density of 482 mW cm-2 for H2/O2 and 321 mW cm-2 for H2/air, corresponding to an overall Pt utilization of 2.5 and 1.7 kW gPt-1, respectively. The durability test revealed no net voltage decay during more than 1700 h of uninterrupted operation at 200 mA cm-2 and 160 °C.

  10. Low thermal budget n-type doping into Ge(001) surface using ultraviolet laser irradiation in phosphoric acid solution

    NASA Astrophysics Data System (ADS)

    Takahashi, Kouta; Kurosawa, Masashi; Ikenoue, Hiroshi; Sakashita, Mitsuo; Takeuchi, Wakana; Nakatsuka, Osamu; Zaima, Shigeaki

    2016-02-01

    We have investigated phosphorus (P) doping into Ge(001) surfaces by using ultraviolet laser irradiation in phosphoric acid solution at room temperature. We demonstrated that the diffusion depth of P in Ge and the concentration of electrically activated P can be controlled by the number of laser shots. Indeed, a high concentration of electrically activated P of 2.4 × 1019 cm-3 was realized by 1000-times laser shots at a laser energy of 1.0 J/cm2, which is comparable or better than the counterparts of conventional n-type doping using a high thermal budget over 600 °C. The generation current is dominant in the reverse bias condition for the laser-doped pn-junction diodes independent on the number of laser shots, thus indicating low-damage during the pn-junction formation. These results open up the possibility for applicable low thermal budget doping process for Ge-based devices fabricated on flexible substrates as well as Si electronics.

  11. Simultaneous assay of glucose, lactate, L-glutamate and hypoxanthine levels in a rat striatum using enzyme electrodes based on neutral red-doped silica nanoparticles.

    PubMed

    Zhang, Fen-Fen; Wan, Qiao; Li, Chen-Xin; Wang, Xiao-Li; Zhu, Zi-Qiang; Xian, Yue-Zhong; Jin, Li-Tong; Yamamoto, Katsunobu

    2004-10-01

    An electrochemical method suitable for the simultaneous measurement of cerebral glucose, lactate, L-glutamate and hypoxanthine concentrations from in vivo microdialysis sampling has been successfully performed for the first time using a neutral red-doped silica (NRDS) nanoparticle-derived enzyme sensor system. These uniform NRDS nanoparticles (about 50 +/- 3 nm) were prepared by a water-in-oil (W/O) microemulsion method, and characterized by a TEM technique. The neutral red-doped interior maintained its high electron-activity, while the exterior nano-silica surface prevented the mediator from leaching out into the aqueous solution, and showed high biocompability. These nanoparticles were then mixing with the glucose oxidase (GOD), lactate oxidase (LOD), L-glutamate oxidase (L-GLOD) or xanthine oxidase (XOD), and immobilized on four glassy carbon electrodes, respectively. A thin Nafion film was coated on the enzyme layer to prevent interference from molecules such as ascorbic acid and uric acid in the dialysate. The high sensitivity of the NRDS modified enzyme electrode system enables the simultaneous monitoring of trace levels of glucose, L-glutamate, lactate and hypoxanthine in diluted dialysate samples from a rat striatum. PMID:15517210

  12. 100-fs-level diode-pumped Yb-doped laser amplifiers

    NASA Astrophysics Data System (ADS)

    Delaigue, M.; Pouysegur, J.; Ricaud, S.; Hönninger, C.; Mottay, E.

    2013-03-01

    Ultrashort pulse lasers with pulse duration on the level of 100 fs can be used for à variety of interesting applications that rely on multiphoton processes or ultrafast dynamics. Up to now, this field was reserved to Ti:sapphire-based laser systems that exhibit a quite complex laser architecture and relatively low laser efficiency. This may be an important reason why such applications could not yet penetrate into large scale industrial applications. We have realized an Yb-doped tungstate-based regenerative amplifier in innovative amplifier architecture. We succeeded to produce 106-fs-pulses at 70μJ and 140 fs at 40 μJ pulse energy, respectively. The average power is on the level of several Watts. The optimized management and exploitation of dispersive and nonlinear effects during the amplification process inside the regenerative amplifier cavity enabled the generation of such short pulses with excellent temporal quality and in an extremely simple and robust laser architecture that is well suited for industrial environments. Applying the same amplifier architecture to an Yb:YAG thin disk regenerative amplifier enabled the generation of pulses as short as 360-fs at high pulse energies exceeding 200 μJ and high average powers of more than 30 W.

  13. Enhanced Fischer-Tropsch synthesis performance of iron-based catalysts supported on nitric acid treated N-doped CNTs

    NASA Astrophysics Data System (ADS)

    Li, Zhenhua; Liu, Renjie; Xu, Yan; Ma, Xinbin

    2015-08-01

    Iron-based catalysts supported on N-doped CNTs (NCNTs) treated by various concentrations of nitric acid for Fischer-Tropsch synthesis (FTS) were investigated. An improved catalytic performance for the iron catalyst supported on acid treated NCNTs was obtained and the suitable nitric acid concentration was 10 M. The physiochemical properties of the NCNTs and the corresponding catalysts were characterized by BET, TEM, XRD, XPS, TGA and H2-TPR. The acid treatment removed the impurity and amorphous carbon, damaged the bamboo-like structure and increased the number of oxygen-containing functional groups and graphitization degree on the NCNTs. The more iron particles located inside the channels of NCNTs, the better catalytic FTS performance due to high dispersion and reducibility.

  14. Quantitative analysis of urinary glycerol levels for doping control purposes using gas chromatography-mass spectrometry.

    PubMed

    Thevis, Mario; Guddat, Sven; Flenker, Ulrich; Schänzer, Wilhelm

    2008-01-01

    The administration of glycerol to endurance athletes results in an increased fluid retention and improved performance, particularly under hot and humid conditions. Consequently, glycerol is considered relevant for sports drug testing and methods for its detection in urine specimens are required. A major issue in this regard is the natural occurrence of trace amounts of glycerol in human urine, which necessitates a quantitative analysis and the determination of normal urinary glycerol levels under various sporting conditions. A quantitative method was established using a gas chromatography/isotope-dilution mass spectrometry-based approach that was validated with regard to lower limit of detection (0.3 microg mL(-1)), lower limit of quantification (0.9 microg mL(-1)), specificity, linearity (1.0-98.0 microg mL(-1)), intraday and interday precision (<20% at 2.4, 24.1 and 48.2 microg mL(-1)) as well as accuracy (92-110%). Sample aliquots of 20 microL were enriched with five-fold deuterated glycerol, dried and derivatised using N-methyl-trimethylsilyltrifluoroacetamide (MSTFA) before analysis. The established method was applied to a total of 1039 doping control samples covering various sport disciplines (349 endurance samples, 286 strength sport samples, 325 game sport samples and 79 other samples) in- and out-of-competition, which provided quantitative information about the glycerol content commonly observed in elite athletes' urine samples. About 85% of all specimens yielded glycerol concentrations < 20.0 microg mL(-1) and few reached values up to 132.6 microg mL(-1). One further sample, however, was found to contain 2690 microg mL(-1), which might indicate the misuse of glycerol, but no threshold for urinary glycerol concentrations has been established yet due to the lack of substantial data. Based on the results obtained from the studied reference population, a threshold for glycerol levels in urine set at 200 microg mL(-1) is suggested, which provides a tool to

  15. Does high serum uric acid level cause aspirin resistance?

    PubMed

    Yildiz, Bekir S; Ozkan, Emel; Esin, Fatma; Alihanoglu, Yusuf I; Ozkan, Hayrettin; Bilgin, Murat; Kilic, Ismail D; Ergin, Ahmet; Kaftan, Havane A; Evrengul, Harun

    2016-06-01

    In patients with coronary artery disease (CAD), though aspirin inhibits platelet activation and reduces atherothrombotic complications, it does not always sufficiently inhibit platelet function, thereby causing a clinical situation known as aspirin resistance. As hyperuricemia activates platelet turnover, aspirin resistance may be specifically induced by increased serum uric acid (SUA) levels. In this study, we thus investigated the association between SUA level and aspirin resistance in patients with CAD. We analyzed 245 consecutive patients with stable angina pectoris (SAP) who in coronary angiography showed more than 50% occlusion in a major coronary artery. According to aspirin resistance, two groups were formed: the aspirin resistance group (Group 1) and the aspirin-sensitive group (Group 2). Compared with those of Group 2, patients with aspirin resistance exhibited significantly higher white blood cell counts, neutrophil counts, neutrophil-to-lymphocyte ratios, SUA levels, high-sensitivity C-reactive protein levels, and fasting blood glucose levels. After multivariate analysis, a high level of SUA emerged as an independent predictor of aspirin resistance. The receiver-operating characteristic analysis provided a cutoff value of 6.45 mg/dl for SUA to predict aspirin resistance with 79% sensitivity and 65% specificity. Hyperuricemia may cause aspirin resistance in patients with CAD and high SUA levels may indicate aspirin-resistant patients. Such levels should thus recommend avoiding heart attack and stroke by adjusting aspirin dosage. PMID:26656902

  16. [Effect of amino acid solutions on the blood ammonia level].

    PubMed

    Sanjo, K; Harihara, Y; Kawasaki, S; Umekita, N; Idezuki, Y

    1985-09-01

    We have carried out several basic experiments on artificial liver support and found that the plasma free amino acid balance was lost after treatment according to this procedure. Application of fluid therapy--Using conventional amino acid preparations available on the market--Is not adequate during and after the treatment with artificial liver. Fluid therapy using mainly special amino acid preparations should have been established; preparations, named Todai Hospital fluid (THF), are intended to correct the deranged aminogram, supply nutrition and promote the improvement in symptoms. Furthermore, experimental animals with acute hepatic insufficiency of diverse severity were prepared and basic experiments were performed which these animals to see how the efficacy of THF developed. In the basic experiments, psychoneurotic symptoms and the electroencephalogram were improved with the lowering of the blood ammonia level. Clinically, THF was not only used as a therapeutic agent after treatment by artificial liver support in patients with fulminant hepatitis, but is also served as a further indication in hepatic encephalopathy accompanying chronic liver diseases in late stages. Improvement in encephalopathy was observed immediately after the administration of THF and persisted while the aminogram pattern returned to the premedication representation. There was more improvement in patients in whom ammonemia was complicated, and the blood ammonia level was reduced markedly. PMID:4088243

  17. Serum fluoride and sialic acid levels in osteosarcoma.

    PubMed

    Sandhu, R; Lal, H; Kundu, Z S; Kharb, S

    2011-12-01

    Osteosarcoma is a rare malignant bone tumor most commonly occurring in children and young adults presenting with painful swelling. Various etiological factors for osteosarcoma are ionizing radiation, family history of bone disorders and cancer, chemicals (fluoride, beryllium, and vinyl chloride), and viruses. Status of fluoride levels in serum of osteosarcoma is still not clear. Recent reports have indicated that there is a link between fluoride exposure and osteosarcoma. Glycoproteins and glycosaminoglycans are an integral part of bone and prolonged exposure to fluoride for long duration has been shown to cause degradation of collagen and ground substance in bones. The present study was planned to analyze serum fluoride, sialic acid, calcium, phosphorus, and alkaline phosphatase levels in 25 patients of osteosarcoma and age- and sex-matched subjects with bone-forming tumours other than osteosarcoma and musculo-skeletal pain (controls, 25 each). Fluoride levels were analyzed by ISE and sialic acid was analyzed by Warren's method. Mean serum fluoride concentration was found to be significantly higher in patients with osteosarcoma as compared to the other two groups. The mean value of flouride in patients with other bone-forming tumors was approximately 50% of the group of osteosarcoma; however, it was significantly higher when compared with patients of group I. Serum sialic acid concentration was found to be significantly raised in patients with osteosarcoma as well as in the group with other bone-forming tumors as compared to the group of controls. There was, however, no significant difference in the group of patients of osteosarcoma when compared with group of patients with other bone-forming tumors. These results showing higher level of fluoride with osteosarcoma compared to others suggesting a role of fluoride in the disease. PMID:19390788

  18. N-Co-O Triply Doped Highly Crystalline Porous Carbon: An Acid-Proof Nonprecious Metal Oxygen Evolution Catalyst.

    PubMed

    Yang, Shiliu; Zhan, Yi; Li, Jingfa; Lee, Jim Yang

    2016-02-10

    In comparison with nonaqueous Li-air batteries, aqueous Li-air batteries are kinetically more facile and there is more variety of non-noble metal catalysts available for oxygen electrocatalysis, especially in alkaline solution. The alkaline battery environment is however vulnerable to electrolyte carbonation by atmospheric CO2 resulting in capacity loss over time. The acid aqueous solution is immune to carbonation but is limited by the lack of effective non-noble metal catalysts for the oxygen evolution reaction (OER). This is contrary to the oxygen reduction reaction (ORR) in acid solution where a few good candidates exist. We report here the development of a N-Co-O triply doped carbon catalyst with substantial OER activity in acid solution by the thermal codecomposition of polyaniline, cobalt salt and cyanamide in nitrogen. Cyanamide and the type of cobalt precursor salt were found to determine the structure, crystallinity, surface area, extent of Co doping and consequently the OER activity of the final carbon catalyst in acid solution. We have also put forward some hypotheses about the active sites that may be useful for guiding further work. PMID:26795393

  19. Prognostic Significance of Uric Acid Levels in Ischemic Stroke Patients.

    PubMed

    Zhang, Xia; Huang, Zhi-Chao; Lu, Tao-Sheng; You, Shou-Jiang; Cao, Yong-Jun; Liu, Chun-Feng

    2016-01-01

    The importance and function of serum uric acid (UA) levels in patients with cardiovascular disease or stroke are unclear. We sought to evaluate the appropriate UA levels for stroke patients and the association between endogenous UA levels and clinical outcomes in acute ischemic stroke (AIS) patients, particularly regarding the possible interaction between gender and UA levels with respect to AIS prognosis. We examined 303 patients who had an onset of ischemic stroke within 48 h. Of those, 101 patients received thrombolytic treatment. Serum UA (μmol/L) levels were measured the second morning after admission. Patient prognosis was evaluated 90 days after clinical onset by modified Rankin Scale. Patients were divided into four groups according to serum UA quartiles. A binary multivariate logistic regression model was used to assess clinical relevance in regard to functional outcome and endogenous UA levels. Analysis of subgroups by gender and normal glomerular filtration rate were also been done. Poor functional outcome was associated with older age, history of atrial fibrillation, or higher baseline National Institutes of Health Stroke Scale scores. After adjustment for potential confounders, patients with higher UA levels (>380 μmol/L) or lower UA levels (≤250 μmol/L) were 2-3 times more likely to have a poor outcome (OR 2.95, 95% CI 1.14-7.61; OR 2.78, 95% CI 1.02-7.58, respectively) compared to the baseline group (UA level 316-380 μmol/L). The same results were observed in thrombolyzed patients. Patients with high and low UA levels were 9-18 times more likely to having poor outcomes compared to the baseline group (UA level: 316-380 μmol/L; OR 18.50, 95% CI: 2.041-167.67; OR 9.66, 95% CI 1.42-65.88, respectively). In men, patients with high UA levels were 6 times more likely to have poor outcomes compared to the baseline group (UA level: 279-334 μmol/L; OR 6.10, 95% CI 1.62-22.93). However, female patients with UA level 271-337 μmol/L were seven times more

  20. Cancellous bone healing around strontium-doped hydroxyapatite in osteoporotic rats previously treated with zoledronic acid.

    PubMed

    Li, Yunfeng; Shui, Xueping; Zhang, Li; Hu, Jing

    2016-04-01

    Bisphosphonates (BPs) are potent anti-osteoporotic agents. Strontium-doped hydroxyapatite (HA) (SrHA) has been reported to increase bone density and improve trabecular microarchitecture in osteoporotic animals. But information about the effect of SrHA on the surrounding bone tissue in osteoporotic animals previously on BPs treatment is limited. We hypothesize that SrHA will induce increased bone density in the vicinity of the material when compared to HA, even in osteoporotic animals previously treated with BPs. HA and 10%SrHA (HA with 10 mol % calcium substituted by strontium) implants were prepared and characterized by scanning electronic microscopy (SEM), X-ray photoemission spectroscopy (XPS), and X-ray diffraction (XRD). Osteoporotic animal model was established by bilateral ovariectomy. Twelve weeks later, all OVX rats accepted subcutaneous injection of zoledronic acid (ZOL) at the dose of 1.5 μg/kg weekly for another twelve weeks. Subsequently, rod-shaped HA and SrHA implants were inserted in the distal femur of the OVX animals previously treated with ZOL. Eight weeks after implantation, specimens were harvested for histological and micro-computed tomography (micro-CT) analysis. Compared to HA, 10%SrHA raised the percent bone volume by 32.7%, the mean trabecular thickness by 36.5%, the mean trabecular number by 34.3%, the mean connectivity density by 38.4%, while the mean trabecular separation showed no significant difference. 10%SrHA also increased the bone area density by 36.3% in histological analysis. Results from this study indicated that 10%SrHA increased bone density and improved trabecular microarchitecture around implants in osteoporotic animals previously treated with ZOL when compared to HA. PMID:25891947

  1. Kinetics of the electrochemical mineralization of perfluorooctanoic acid on ultrananocrystalline boron doped conductive diamond electrodes.

    PubMed

    Urtiaga, Ane; Fernández-González, Carolina; Gómez-Lavín, Sonia; Ortiz, Inmaculada

    2015-06-01

    This work deals with the electrochemical degradation and mineralization of perfluorooctanoic acid (PFOA). Model aqueous solutions of PFOA (100mg/L) were electro-oxidized under galvanostatic conditions in a flow-by undivided cell provided with a tungsten cathode and an anode formed by a commercial ultrananocrystalline boron doped diamond (BDD) coating on a niobium substrate. A systematic experimental study was conducted in order to analyze the influence of the following operation variables: (i) the supporting electrolyte, NaClO4 (1.4 and 8.4g/L) and Na2SO4 (5g/L); (ii) the applied current density, japp, in the range 50-200 A/m(2) and (iii) the hydrodynamic conditions, in terms of flowrate in the range 0.4×10(-4)-1.7×10(-4)m(3)/s and temperature in the range 293-313K. After 6h of treatment and at japp 200A/m(2), PFOA removal was higher than 93% and the mineralization ratio, obtained from the decrease of the total organic carbon (TOC) was 95%. The electrochemical generation of hydroxyl radicals in the supporting electrolyte was experimentally measured based on their reaction with dimethyl sulfoxide. The enhanced formation of hydroxyl radicals at higher japp was related to the faster kinetics of PFOA removal. The fitting of experimental data to the proposed kinetic model provided the first order rate constants of PFOA degradation, kc(1) that moved from 2.06×10(-4) to 15.58×10(-4)s(-1), when japp varied from 50 to 200A/m(2). PMID:24981910

  2. Nitrogen-doped carbon nanofoam derived from amino acid chelate complex for supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, Prakash; Shanmugam, Sangaraju

    2016-06-01

    We report a novel strategy to fabricate the nitrogen-doped mesoporous carbon nanofoam structures (N-MCNF), derived from magnesium amino acid chelate complex (Mg-acc-complex) for its application towards high performance supercapacitor (SCs) system. A series of N-MCNF with well-connected carbon nanofoam structure have been developed by varying the synthesis temperature. The fabricated N-MCNF material possesses a high surface area (1564 m2 g-1) and pore volume (1.767 cm3 g-1) with nitrogen content of 3.42 wt%. A prototypical coin cell type symmetric N-MCNF SC device has been assembled with 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIMBF4] ionic liquid electrolyte, and evaluated for SCs studies. The N-MCNF with high textural properties delivers unprecedented SC performance, such as high specific capacitance (204 Fg-1 at 0.25 Ag-1, 25 °C), high energy density (63.4 Wh kg-1), high power density (35.9 kW kg-1) and long-term cycle life (32,500 cycles). Significantly, N-MCNF materials exhibited high power rate performance, at 500 mV-1 (115 Fg-1) and 25 Ag-1 (166 Fg-1) owing to the uniform mesopore size distribution (∼4 nm). The N-MCNF SC device delivered maximum energy densities of 83.4 and 93.3 Wh kg-1 at 60 °C and 90 °C, respectively. Such outstanding N-MCNF SC device is successfully demonstrated in solar energy harvester applications.

  3. Light-Induced Alterations in Basil Ganglia Kynurenic Acid Levels

    NASA Technical Reports Server (NTRS)

    Sroufe, Angela E.; Whittaker, J. A.; Patrickson, J. W.; Orr, M. C.

    1997-01-01

    The metabolic synthesis, release and breakdown of several known CNS neurotransmitters have been shown to follow a circadian pattern entrained to the environmental light/dark cycle. The levels of excitatory amino acid (EAA) transmitters such as glutamate, have been shown to vary with environmental lighting conditions. Kynurenic Acid (KA), an endogenous tryptophan metabolite and glutamate receptor antagonist, has been reported to have neuroprotective effects against EAA-induced excitotoxic cell damage. Changes in KA's activity within the mammalian basal ganglia has been proposed as being contributory to neurotoxicity in Huntington's Disease. It is not known whether CNS KA levels follow a circadian pattern or exhibit light-induced fluctuations. However, because the symptoms of certain degenerative motor disorders seem to fluctuate with daily 24 hour rhythm, we initiated studies to determine if basal ganglia KA were influenced by the daily light/dark cycle and could influence motor function. Therefore in this study, HPLC-EC was utilized to determine if basal ganglia KA levels in tissue extracts from adult male Long-Evans rats (200-250g) entrained to 24 and 48 hours constant light and dark conditions, respectively. Samples were taken one hour before the onset of the subjective day and one hour prior to the onset of the subjective night in order to detect possible phase differences in KA levels and to allow for accumulation of factors expressed in association with the light or dark phase. Data analysis revealed that KA levels in the basal ganglia vary with environmental lighting conditions; being elevated generally during the dark. Circadian phase differences in KA levels were also evident during the subjective night and subjective day, respectively. Results from these studies are discussed with respect to potential cyclic changes in neuronal susceptibility to excitotoxic damage during the daily 24 hour cycle and its possible relevance to future therapeutic approaches in

  4. The effect of porosity on performance of phosphoric acid doped polybenzimidazole polymer electrolyte membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Celik, Muhammet; Genc, Gamze; Elden, Gulsah; Yapici, Huseyin

    2016-03-01

    A polybenzimidazole (PBI) based polymer electrolyte fuel cells, which called high temperature polymer electrolyte fuel cells (HT-PEMS), operate at higher temperatures (120-200°C) than conventional PEM fuel cells. Although it is known that HT-PEMS have some of the significant advantages as non-humidification requirements for membrane and the lack of liquid water at high temperature in the fuel cell, the generated water as a result of oxygen reduction reaction causes in the degradation of these systems. The generated water absorbed into membrane side interacts with the hydrophilic PBI matrix and it can cause swelling of membrane, so water transport mechanism in a membrane electrode assembly (MEA) needs to be well understood and water balance must be calculated in MEA. Therefore, the water diffusion transport across the electrolyte should be determined. In this study, various porosity values of gas diffusion layers are considered in order to investigate the effects of porosity on the water management for two phase flow in fuel cell. Two-dimensional fuel cell with interdigitated flow-field is modelled using COMSOL Multiphysics 4.2a software. The operating temperature and doping level is selected as 160°C and 6.75mol H3PO4/PBI, respectively.

  5. Effects of Pressure on Optically Active Deep Levels in Phosphorus Doped ZnSe

    NASA Astrophysics Data System (ADS)

    Weinstein, B. A.; Iota, V.

    1998-03-01

    We report high pressure photoluminescence (PL) and PL-excitation (PLE) studies at 8K of the 'midgap' emission in P-doped ZnSe using a diamond-cell with He medium. The dominant emission at low pressure is due to donor-acceptor-pair (DAP) transitions between shallow donors and deep trigonally relaxed P_Se acceptors.(J. Davies, et al., J. Luminescence 18/19, 322 (1979)) Its PL and PLE peaks shift by 8.2meV/kbar and 5.9meV/kbar, respectively -- Stokes shift decreasing with pressure. At 35kbar a new PL band, shifting to lower energy (-5.4meV/kbar), emerges from above the absorption edge, and concurrently the original DAP PL quenches. This shows that a resonant level, a deep donor or possibly a P_Se antibonding state,(R. Watts, et al., Phys. Rev. B3), 404 (1971) crosses the conduction edge into the gap. A third PL band is seen only with internse UV excitation. It occurs initially as a high energy shoulder of the original DAP peak, but shifts more rapidly upward (9.4meV/kbar) until it crosses the edge and quenches at 40kbar. We discuss candidates for this band, including donor-P_Se complexes, and we compare our results to similar work on the Zn vacancy in ZnSe. (figures)

  6. Pressure-induced Mott transition in an organic superconductor with a finite doping level.

    PubMed

    Oike, H; Miyagawa, K; Taniguchi, H; Kanoda, K

    2015-02-13

    We report the pressure study of a doped organic superconductor with a Hall coefficient and conductivity measurements. We find that maximally enhanced superconductivity and a marginal-Fermi liquid appear around a certain pressure where mobile carriers increase critically, suggesting a possible quantum phase transition between strongly and weakly correlated regimes. This observation points to the presence of a criticality in Mottness for a doped Mott insulator with tunable correlation. PMID:25723239

  7. Development of Sensitive Analytical Approach for the Quantification of α-Lipoic Acid Using Boron Doped Diamond Electrode.

    PubMed

    Stankovic, Dalibor M; Mehmeti, Eda; Kalcher, Kurt

    2016-01-01

    A boron doped diamond (BDD) electrode was investigated for use as an electrochemical sensor for α-lipoic acid (LA) using amperometric and differential pulse voltammetric detection. LA displays a well expressed oxidation peak at +0.9 V vs. Ag/AgCl in solutions with a pH value of 3. It was found that signals obtained are linearly related to the concentration range from 0.3 to 105 μM with detection limit of 0.088 μM. Interferences by common compounds such as ascorbic acid, uric acid and dopamine were tested and the method was successfully applied to the determination of LA in human body fluids where it gave recoveries in the range from 95 to 97%. PMID:27506710

  8. Energy transfer and energy level decay processes in Tm{sup 3+}-doped tellurite glass

    SciTech Connect

    Gomes, Laercio; Lousteau, Joris; Milanese, Daniel; Scarpignato, Gerardo C.; Jackson, Stuart D.

    2012-03-15

    The primary excited state decay and energy transfer processes in singly Tm{sup 3+}-doped TeO{sub 2}:ZnO:Bi{sub 2}O{sub 3}:GeO{sub 2} (TZBG) glass relating to the {sup 3}F{sub 4}{yields}{sup 3}H{sub 6}{approx}1.85 {mu}m laser transition have been investigated in detail using time-resolved fluorescence spectroscopy. Selective laser excitation of the {sup 3}H{sub 4} manifold at 794 nm, the {sup 3}H{sub 5} manifold at 1220 nm, and {sup 3}F{sub 4} manifold at 1760 nm has established that the {sup 3}H{sub 5} manifold is entirely quenched by multiphonon relaxation in tellurite glass. The luminescence from the {sup 3}H{sub 4} manifold with an emission peak at 1465 nm suffers strong suppression due to cross relaxation that populates the {sup 3}F{sub 4} level with a near quadratic dependence on the Tm{sup 3+} concentration. The {sup 3}F{sub 4} lifetime becomes longer as the Tm{sup 3+} concentration increases due to energy migration and decreases to 2.92 ms when [Tm{sup 3+}] = 4 mol. % as a result of quasi-resonant energy transfer to free OH{sup -} radicals present in the glass at concentrations between 1 x 10{sup 18} cm{sup -3} and 2 x 10{sup 18} cm{sup -3}. Judd-Ofelt theory in conjunction with absorption measurements were used to obtain the radiative lifetimes and branching ratios of the energy levels located below 25 000 cm{sup -1}. The spectroscopic parameters, the cross relaxation and Tm{sup 3+}({sup 3}F{sub 4}) {yields} OH{sup -} energy transfer rates were used in a numerical model for laser transitions emitting at 2335 nm and 1865 nm.

  9. 40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Silicic acid (H6SiO2O7), magnesium...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as silicic acid (H6SiO2O7)...

  10. Diazeniumdiolate-Doped Poly(lactic-co-glycolic acid)-Based Nitric Oxide Releasing Films as Antibiofilm Coatings

    PubMed Central

    Cai, Wenyi; Wu, Jianfeng; Xi, Chuanwu; Meyerhoff, Mark, E.

    2012-01-01

    Nitric oxide (NO) releasing films with a bilayer configuration are fabricated by doping dibutyhexyldiamine diazeniumdiolate (DBHD/N2O2) in a poly(lactic-co-glycolic acid) (PLGA) layer and further encapsulating this base layer with a silicone rubber top coating. By incorporating pH sensitive dyes within the films, pH changes in the PLGA layer are visualized and correlated with the NO release profiles (flux vs. time). It is demonstrated that PLGA acts as both a promoter and controller of NO release from the coating by providing protons through its intrinsic acid residues (both end-groups and monomeric acid impurities) and hydrolysis products (lactic acid and glycolic acid). Control of the pH changes within the PLGA layer can be achieved by adjusting the ratio of DBHD/N2O2 and utilizing PLGAs with different hydrolysis rates. Coatings with a variety of NO release profiles are prepared with lifetimes of up to 15 d at room temperature (23 °C) and 10 d at 37 °C. When incubated in a CDC flow bioreactor for a one-week period at RT or 37 °C, all the NO releasing films exhibit considerable antibiofilm properties against gram-positive S. aureus and gram-negative E. coli. In particular, compared to the silicone rubber surface alone, an NO releasing film with a base layer of 30 wt% DBHD/N2O2 mixed with poly(lactic acid) exhibits an ~98.4% reduction in biofilm biomass of S. aureus and ~ 99.9% reduction for E. coli at 37 °C. The new diazeniumdiolate-doped PLGA-based NO releasing coatings are expected to be useful antibiofilm coatings for a variety of indwelling biomedical devices (e.g., catheters). PMID:22841918

  11. Association between serum folic acid level and erectile dysfunction.

    PubMed

    Karabakan, M; Erkmen, A E; Guzel, O; Aktas, B K; Bozkurt, A; Akdemir, S

    2016-06-01

    This study measured the serum folic acid (FA) level in patients with erectile dysfunction (ED) and evaluated the possible association between the serum FA level and erectile function. The study divided 120 patients with ED into 3 groups of 40 patients each: those with severe, moderate and mild ED. Forty healthy men served as controls. Fasting serum samples were obtained, and the total testosterone, cholesterol and FA levels were measured using chemiluminescent immunoassays. There were no significant differences in the mean age, mean body mass index or mean serum total testosterone and cholesterol levels among the three ED groups and controls (P > 0.05). The mean serum FA concentrations were 7.2 ± 3.7, 7.1 ± 3.2, 10.2 ± 4.6 and 10.7 ± 4.6 ng ml(-1) in the severe, moderate and mild ED and control groups respectively. The mean serum FA concentration was significantly higher in the control group than in the severe and moderate ED groups (both P < 0.001), but not the mild ED group (P = 0.95). Considering the significant differences in the serum FA levels between the control and ED groups, serum FA deficiency might reflect the severity of ED. PMID:26302884

  12. Ocean acidification increases fatty acids levels of larval fish.

    PubMed

    Díaz-Gil, Carlos; Catalán, Ignacio A; Palmer, Miquel; Faulk, Cynthia K; Fuiman, Lee A

    2015-07-01

    Rising levels of anthropogenic carbon dioxide in the atmosphere are acidifying the oceans and producing diverse and important effects on marine ecosystems, including the production of fatty acids (FAs) by primary producers and their transfer through food webs. FAs, particularly essential FAs, are necessary for normal structure and function in animals and influence composition and trophic structure of marine food webs. To test the effect of ocean acidification (OA) on the FA composition of fish, we conducted a replicated experiment in which larvae of the marine fish red drum (Sciaenops ocellatus) were reared under a climate change scenario of elevated CO2 levels (2100 µatm) and under current control levels (400 µatm). We found significantly higher whole-body levels of FAs, including nine of the 11 essential FAs, and altered relative proportions of FAs in the larvae reared under higher levels of CO2. Consequences of this effect of OA could include alterations in performance and survival of fish larvae and transfer of FAs through food webs. PMID:26179801

  13. What is the relationship between gestational age and docosahexaenoic acid (DHA) and arachidonic acid (ARA) levels?

    PubMed

    Baack, Michelle L; Puumala, Susan E; Messier, Stephen E; Pritchett, Deborah K; Harris, William S

    2015-09-01

    Long chain polyunsaturated fatty acids (LCPUFA) including docosahexaenoic acid (DHA) and arachidonic acid (ARA) are increasingly transferred from mother to fetus late in pregnancy. Infants born before this transfer is complete are at risk for deficiency. This study determines the relationship between gestational age (GA) and circulating LCPUFA levels to better understand the unique needs of premature infants born at various GAs. Whole blood was collected within the first 7 days of life from 60 preterm (≤34 weeks GA) and 30 term infants (≥38 weeks GA) and FA levels were analyzed. Since concurrent intravenous lipid emulsion can skew composition data, blood LCPUFA concentrations were also measured. Levels were compared among groups, and linear regression models were used to examine the association between FA composition and GA. Preterm infants had significantly lower DHA and ARA levels than term peers, and whether assessed as concentrations or compositions, both directly correlated with GA (p<0.0001). Moreover, FA comparisons suggest that premature infants have impaired synthesis of LCPUFAs from precursors and may require preformed DHA and ARA. This study confirms that essential FA status is strongly related to GA, and that those babies born the earliest are at the greatest risk of LCPUFA deficiency. PMID:26205427

  14. Correlation between the energy level structure of cerium-doped yttrium aluminum garnet and luminescent behavior at varying temperatures

    NASA Astrophysics Data System (ADS)

    Song, Zhen; Liu, Xiaolang; He, Lizhu; Liu, Q. L.

    2016-05-01

    Luminescent spectra of cerium-doped yttrium aluminum garnet are measured at varying temperatures. It is found that the two excitation peaks demonstrate a reverse trend as the temperature rises, and the breadth of the high-energy emission peak experiences an abrupt widening. These effects could be directly linked to the energy level scheme of Ce3+ under the crystal field of local symmetry. Moreover, an alternative fitting function is provided which could effectively resolve the emission curve.

  15. Phosphorus-doped carbon nanotubes supported low Pt loading catalyst for the oxygen reduction reaction in acidic fuel cells

    NASA Astrophysics Data System (ADS)

    Liu, Ziwu; Shi, Qianqian; Zhang, Rufan; Wang, Quande; Kang, Guojun; Peng, Feng

    2014-12-01

    To develop low-cost and efficient cathode electrocatalysts for fuel cells in acidic media, phosphorus-doped carbon nanotubes (P-CNTs) supported low Pt loading catalyst (0.85% Pt) is designed. The as-prepared Pt/P-CNTs exhibit significantly enhanced electrocatalytic oxygen reduction reaction (ORR) activity and long-term stability due to the stronger interaction between Pt and P-CNTs, which is proven by X-ray photoelectron spectroscopic analysis and density functional theory calculations. Moreover, the as-prepared Pt/P-CNTs also display much better tolerance to methanol crossover effects, showing a good potential application for future proton exchange membrane fuel cell devices.

  16. Investigation of the doping efficiency of poly(styrene sulfonic acid) in poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonic acid) dispersions by capillary electrophoresis.

    PubMed

    Diah, Anang W M; Quirino, Joselito P; Belcher, Warwick; Holdsworth, Clovia I

    2014-07-01

    CE can efficiently separate poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonic acid) (PEDOT/PSS) complexes and free PSS in dispersions and can be used to estimate the degree of PSS doping. We investigated the doping efficiency of PSS on PEDOT in dispersions using CE and its effect on the conductivity of the resulting PEDOT/PSS films. Results of this study indicate that dispersions containing 1:2.5-3 EDOT:PSS feed ratio (by weight) exhibiting 72-73% PSS doping generate highly processable and highly conductive films. Conductivity can be optimized by limiting the time of reaction to 12 h. At this point of the reaction, the PEDOT/PSS segments, appearing as broad band in the electropherogram, could still exist in an extended coil conformation favoring charge transport resulting in high conductivity. Above a threshold PEDOT length formed at reaction times longer than 12 h, the PEDOT/PSS complex, appearing as spikes in the electropherogram, most likely have undergone a conformational change to coiled core-shell structure restricting charge transport resulting in low conductivity. The optimal conductivity (5.2 S/cm) of films from dispersions synthesized for 12 h is significantly higher than those from its commercial equivalent Clevios P and other reported values obtained under similar conditions without the addition of codopants. PMID:24782292

  17. Crystal growth, structural, crystalline perfection, optical and mechanical properties of Nd3+ doped sulfamic acid (SA) single crystals

    NASA Astrophysics Data System (ADS)

    Shkir, Mohd.; Riscob, B.; Ganesh, V.; Vijayan, N.; Gupta, Rahul; Plaza, J. L.; Dieguez, E.; Bhagavannarayana, G.

    2013-10-01

    Sulfamic acid (SA) single crystals, both pure and doped with 1, 2.5 and 5 mol% Nd, were grown successfully in an aqueous solution by the slow cooling method. Powder X-ray diffraction patterns were recorded to check the variation in the lattice parameters and phase of the crystals. The optical transparency was found to be higProd. Type: FTPhest (∼80%) for the 1 mol% Nd3+ doped SA single crystal. The optical band gap was also calculated and found to be ∼4.31, 4.20 and 3.67 eV. The influence of Nd3+ doping on the crystalline perfection was assessed by a high resolution X-ray diffractometer (HRXRD) and shows that the grown crystals could accommodate Nd3+ at the interstitial positions in the crystalline matrix of SA up to some critical concentration without any deterioration in the crystalline perfection. The etching studies were carried out and the etch pits densities were calculated. The mechanical property of grown single crystals was also studied.

  18. Association of Serum Uric Acid Levels in Psoriasis

    PubMed Central

    Li, Xin; Miao, Xiao; Wang, Hongshen; Wang, Yifei; Li, Fulun; Yang, Qiong; Cui, Rutao; Li, Bin

    2016-01-01

    Abstract High levels of serum uric acid (SUAC) are frequently detected in patients with psoriasis. However, the relationship between psoriasis and hyperuricemia remains unknown. Here we conducted a meta-analysis to identify the SUAC levels in subjects with psoriasis and to determine whether there is an associated risk between psoriasis and hyperuricemia. A comprehensive search of the literature from January 1980 to November 2014 across 7 databases (MEDLINE, Embase, Cochrane Central Register, and 4 Chinese databases) was conducted to determine whether there is an associated risk between psoriasis and hyperuricemia. Among the 170 identified reports, 14 observational studies were included in this meta-analysis. We found a significant higher SUAC level (MD 0.68, 95% CI 0.26–1.09; P = 0.002) in patients with psoriasis in Western Europe, but no significant differences were found between the East Asia and India subgroup (MD 1.22, 95% CI –0.13–2.56; P = 0.08) or the Middle East subgroup (MD 0.48, 95% CI –0.49–1.44; P = 0.33). Similar results were obtained from the meta-analysis of SUAC levels in subjects with severe psoriasis. Our meta-analysis showed that the correlation between psoriasis and hyperuricemia was either ethnicity- or region-dependent and that patients with psoriasis in Western Europe were more likely to have hyperuricemia. PMID:27175702

  19. The effect of humic acids on the element release from high level waste glass

    SciTech Connect

    Wei, J.; Van Iseghem, P.

    1997-12-31

    Eu and Am doped glasses were interacted with synthetic interstitial clay water (SiC) and corresponding reference leachant, humic acids free interstitial solution (IS) to investigate the influence of humic acids on the leaching behavior of the waste glass. Static leach tests were carried out at 40 C and 90 C. The release of the lanthanide Eu and the actinide Am from the glass was obviously enhanced by the presence of humic acids. The leaching of transition elements, Fe and Ti strongly depends on the humic acids concentration. The leaching of glass matrix components, Al and B was also influenced by the concentrations of humic acids. However, humic acids have little effect on the leaching of glass matrix element Si.

  20. Low irradiances affect abscisic acid, indole-3-acidic acid, and cytokinin levels of wheat (Triticum aestivum L.) tissues

    NASA Technical Reports Server (NTRS)

    Nan, R.; Carman, J. G.; Salisbury, F. B.

    1999-01-01

    Wheat (Triticum aestivum L.) plants were grown under four irradiance levels: 1,400, 400, 200, and 100 micromol m-2 s-1. Leaves and roots were sampled before, during, and after the boot stage, and levels of abscisic acid (ABA), indole-3-acetic acid (IAA), zeatin, zeatin riboside, dihydrozeatin, dihydrozeatin riboside, isopentenyl adenine, and isopentenyl adenosine were quantified using noncompetitive indirect ELISA systems. Levels of IAA in leaves and roots of plants exposed to 100 micromol m-2 s-1 of irradiance were 0.7 and 2.9 micromol kg-1 dry mass (DM), respectively. These levels were 0.2 and 1.0 micromol kg-1 DM, respectively, when plants were exposed to 1,400 micromol m-2 s-1. Levels of ABA in leaves and roots of plants exposed to 100 micromol m-2 s-1 were 0.65 and 0.55 micromol kg-1 DM, respectively. They were 0.24 micromol kg-1 DM (both leaves and roots) when plants were exposed to 1,400 micromol m-2 s-1. Levels of isopentenyl adenosine in leaves (24.3 nmol kg-1 DM) and roots (29.9 nmol kg-1 DM) were not affected by differences in the irradiance regime. Similar values were obtained in a second experiment. Other cytokinins could not be detected (<10 nmol kg 1 DM) in either experiment with the sample sizes used (150-600 mg DM for roots and shoots, respectively).

  1. Unsaturated fatty acids supplementation reduces blood lead level in rats.

    PubMed

    Skoczyńska, Anna; Wojakowska, Anna; Nowacki, Dorian; Bobak, Łukasz; Turczyn, Barbara; Smyk, Beata; Szuba, Andrzej; Trziszka, Tadeusz

    2015-01-01

    Some dietary factors could inhibit lead toxicity. The aim of this study was to evaluate the effect of dietary compounds rich in unsaturated fatty acids (FA) on blood lead level, lipid metabolism, and vascular reactivity in rats. Serum metallothionein and organs' lead level were evaluated with the aim of assessing the possible mechanism of unsaturated FA impact on blood lead level. For three months, male Wistar rats that were receiving drinking water with (100 ppm Pb) or without lead acetate were supplemented per os daily with virgin olive oil or linseed oil (0.2 mL/kg b.w.) or egg derived lecithin fraction: "super lecithin" (50 g/kg b.w.). Mesenteric artery was stimulated ex vivo by norepinephrine (NE) administered at six different doses. Lecithin supplementation slightly reduced pressor responses of artery to NE. Lead administered to rats attenuated the beneficial effect of unsaturated FA on lipid metabolism and vascular reactivity to adrenergic stimulation. On the other hand, the super lecithin and linseed oil that were characterized by low omega-6 to omega-3 ratio (about 1) reduced the blood lead concentration. This effect was observed in lead poisoned rats (p < 0.0001) and also in rats nonpoisoned with lead (p < 0.05). PMID:26075218

  2. Unsaturated Fatty Acids Supplementation Reduces Blood Lead Level in Rats

    PubMed Central

    Skoczyńska, Anna; Wojakowska, Anna; Nowacki, Dorian; Bobak, Łukasz; Turczyn, Barbara; Smyk, Beata; Szuba, Andrzej; Trziszka, Tadeusz

    2015-01-01

    Some dietary factors could inhibit lead toxicity. The aim of this study was to evaluate the effect of dietary compounds rich in unsaturated fatty acids (FA) on blood lead level, lipid metabolism, and vascular reactivity in rats. Serum metallothionein and organs' lead level were evaluated with the aim of assessing the possible mechanism of unsaturated FA impact on blood lead level. For three months, male Wistar rats that were receiving drinking water with (100 ppm Pb) or without lead acetate were supplemented per os daily with virgin olive oil or linseed oil (0.2 mL/kg b.w.) or egg derived lecithin fraction: “super lecithin” (50 g/kg b.w.). Mesenteric artery was stimulated ex vivo by norepinephrine (NE) administered at six different doses. Lecithin supplementation slightly reduced pressor responses of artery to NE. Lead administered to rats attenuated the beneficial effect of unsaturated FA on lipid metabolism and vascular reactivity to adrenergic stimulation. On the other hand, the super lecithin and linseed oil that were characterized by low omega-6 to omega-3 ratio (about 1) reduced the blood lead concentration. This effect was observed in lead poisoned rats (p < 0.0001) and also in rats nonpoisoned with lead (p < 0.05). PMID:26075218

  3. Highly efficient electrochemical degradation of perfluorooctanoic acid (PFOA) by F-doped Ti/SnO2 electrode.

    PubMed

    Yang, Bo; Jiang, Chaojin; Yu, Gang; Zhuo, Qiongfang; Deng, Shubo; Wu, Jinhua; Zhang, Hong

    2015-12-15

    The novel F-doped Ti/SnO2 electrode prepared by SnF4 as the single-source precursor was used for electrochemical degradation of aqueous perfluorooctanoic acid (PFOA). Higher oxidation reactivity and significantly longer service life were achieved for Ti/SnO2-F electrode than Ti/SnO2-X (X=Cl, Br, I, or Sb) electrode, which could decomposed over 99% of PFOA (50 mL of 100 mg L(-1)) within 30-min electrolysis. The property of Ti/SnO2-F electrode and its electrooxidation mechanism were investigated by XRD, SEM-EDX, EIS, LSV, and interfacial resistance measurements. We propose that the similar ionic radii of F and O as well as strong electronegativity of F caused its electrochemical stability with high oxygen evolution potential (OEP) and smooth surface to generate weakly adsorbed OH. The preparation conditions of electrode were also optimized including F doping amount, calcination temperature, and dip coating times, which revealed the formation process of electrode. Additionally, the major mineralization product, F(-), and low concentration of shorter chain perfluorocarboxylic acids (PFCAs) were detected in solution. So the reaction pathway of PFOA electrooxidation was proposed by intermediate analysis. These results demonstrate that Ti/SnO2-F electrode is promising for highly efficient treatment of PFOA in wastewater. PMID:26183235

  4. Thermal quenching effect of an infrared deep level in Mg-doped p-type GaN films

    NASA Astrophysics Data System (ADS)

    Kim, Keunjoo; Chung, Sang Jo

    2002-03-01

    The thermal quenching of an infrared deep level of 1.2-1.5 eV has been investigated on Mg-doped p-type GaN films, using one- and two-step annealing processes and photocurrent measurements. The deep level appeared in the one-step annealing process at a relatively high temperature of 900 °C, but disappeared in the two-step annealing process with a low-temperature step and a subsequent high-temperature step. The persistent photocurrent was residual in the sample including the deep level, while it was terminated in the sample without the deep level. This indicates that the deep level is a neutral hole center located above a quasi-Fermi level, estimated with an energy of EpF=0.1-0.15 eV above the valence band at a hole carrier concentration of 2.0-2.5×1017/cm3.

  5. Energy levels and zero field splitting parameter for Fe{sup 2+} doped in ZnS

    SciTech Connect

    Ivaşcu, Simona

    2013-11-13

    The aim of present paper is to report the results on the modeling of the crystal field parameters of Fe{sup 2+} doped in host matrix ZnS, simulate the energy levels scheme and calculate the zero field splitting parameter D of such system. The crystal field parameters were modeled in the frame of the superposition model of crystal field and the simulation of the energy levels scheme and calculation of the zero field splitting parameters done by diagonalization the Hamiltonian of Fe{sup 2+}:ZnS system. The obtained results were disscused and compared with experimental data. Satisfactory agreement have been obtained.

  6. Serum uric acid levels during leprosy reaction episodes

    PubMed Central

    Alves-Junior, Eduardo R.; Arruda, Talita A.; Lopes, Jose C.; Fontes, Cor J.F.

    2016-01-01

    Background. Leprosy reactions are acute inflammatory episodes that occur mainly in the multibacillary forms of the disease. The reactions are classified as type 1 (reverse reaction) or type 2 (erythema nodosum leprosum). Leprosy-associated oxidative stress has been widely demonstrated. Several recent studies have shown uric acid (UA) to have antioxidative effects under pathologic conditions. The objective of this study was to assess serum levels of UA in patients with leprosy reactions, with the aim of monitoring their levels before and after treatment, compared with levels in leprosy patients without reactions. Methods. The study included patients aged 18–69 years assisted at a leprosy treatment reference center in the Central Region of Brazil. Patients who were pregnant; were using immunosuppressant drugs or immunobiologicals; or had an autoimmune disease, human immunodeficiency virus infection, acquired immune deficiency syndrome, or tuberculosis were excluded. Upon recruitment, all individuals were clinically assessed for skin lesions and neural or systemic impairment. Some patients had already completed treatment for leprosy, while others were still undergoing treatment or had initiated treatment after being admitted. The treatment of the reactional episode was started only after the initial evaluation. Laboratory assessments were performed upon admission (baseline) and at approximately 30 and 60 days (time points 1 and 2, respectively). Results. A total of 123 leprosy patients were recruited between June 2012 and June 2015; among them, 56, 42, and 25 presented with type 1, type 2, and no reactions, respectively. Serum UA levels were significantly reduced in patients with type 2 leprosy reactions compared with patients in the control group and remained lower in the two subsequent assessments, after initiation of anti-reaction treatments, with similar values to those recorded before the treatment. Discussion. The decreased serum UA levels in patients with

  7. Serum uric acid levels during leprosy reaction episodes.

    PubMed

    Morato-Conceicao, Yvelise T; Alves-Junior, Eduardo R; Arruda, Talita A; Lopes, Jose C; Fontes, Cor J F

    2016-01-01

    Background. Leprosy reactions are acute inflammatory episodes that occur mainly in the multibacillary forms of the disease. The reactions are classified as type 1 (reverse reaction) or type 2 (erythema nodosum leprosum). Leprosy-associated oxidative stress has been widely demonstrated. Several recent studies have shown uric acid (UA) to have antioxidative effects under pathologic conditions. The objective of this study was to assess serum levels of UA in patients with leprosy reactions, with the aim of monitoring their levels before and after treatment, compared with levels in leprosy patients without reactions. Methods. The study included patients aged 18-69 years assisted at a leprosy treatment reference center in the Central Region of Brazil. Patients who were pregnant; were using immunosuppressant drugs or immunobiologicals; or had an autoimmune disease, human immunodeficiency virus infection, acquired immune deficiency syndrome, or tuberculosis were excluded. Upon recruitment, all individuals were clinically assessed for skin lesions and neural or systemic impairment. Some patients had already completed treatment for leprosy, while others were still undergoing treatment or had initiated treatment after being admitted. The treatment of the reactional episode was started only after the initial evaluation. Laboratory assessments were performed upon admission (baseline) and at approximately 30 and 60 days (time points 1 and 2, respectively). Results. A total of 123 leprosy patients were recruited between June 2012 and June 2015; among them, 56, 42, and 25 presented with type 1, type 2, and no reactions, respectively. Serum UA levels were significantly reduced in patients with type 2 leprosy reactions compared with patients in the control group and remained lower in the two subsequent assessments, after initiation of anti-reaction treatments, with similar values to those recorded before the treatment. Discussion. The decreased serum UA levels in patients with type

  8. Effects of low-level Ag doping on Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+x}

    SciTech Connect

    Deis, T.A.; Eror, N.G.; Krishnaraj, P.; Prorok, B.C.; Lelovic, M.; Balachandran, U.

    1995-07-01

    Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8} has been doped with silver, up to 10,000 ppm, in three ways: excess additions, substitution of Ag for Bi, and substitution of Ag for Sr. Effects of doping on the c-axis lattice parameter and critical temperature ({Tc}) were measured. Effects from doing were only observed in slow-cooled [10{degree}/hr] oxygen equilibrated samples. Doping by excess additions caused a small decrease in {Tc} and an increase in the c-axis length of the lattice. Doping by substitution, compared to excess Ag additions, caused a larger decrease in {Tc} and higher c-axis values for doping levels up to 1,000 ppm. Doping by substitution at higher levels (1,000--10,000 ppm) caused {Tc} to increase and the c-axis to decrease. Samples with similar substitutional doping levels exhibited comparable {Tc} values and samples with Ag substituted for Sr consistently exhibited higher c-axis values than samples that had equivalent amounts of Ag substituted for Bi.

  9. Higher transcription levels in ascorbic acid biosynthetic and recycling genes were associated with higher ascorbic acid accumulation in blueberry.

    PubMed

    Liu, Fenghong; Wang, Lei; Gu, Liang; Zhao, Wei; Su, Hongyan; Cheng, Xianhao

    2015-12-01

    In our preliminary study, the ripe fruits of two highbush blueberry (Vaccinium corymbosum L.) cultivars, cv 'Berkeley' and cv 'Bluecrop', were found to contain different levels of ascorbic acid. However, factors responsible for these differences are still unknown. In the present study, ascorbic acid content in fruits was compared with expression profiles of ascorbic acid biosynthetic and recycling genes between 'Bluecrop' and 'Berkeley' cultivars. The results indicated that the l-galactose pathway was the predominant route of ascorbic acid biosynthesis in blueberry fruits. Moreover, higher expression levels of the ascorbic acid biosynthetic genes GME, GGP, and GLDH, as well as the recycling genes MDHAR and DHAR, were associated with higher ascorbic acid content in 'Bluecrop' compared with 'Berkeley', which indicated that a higher efficiency ascorbic acid biosynthesis and regeneration was likely to be responsible for the higher ascorbic acid accumulation in 'Bluecrop'. PMID:26041210

  10. Cutaneous retinoic acid levels determine hair follicle development and downgrowth.

    PubMed

    Okano, Junko; Levy, Clara; Lichti, Ulrike; Sun, Hong-Wei; Yuspa, Stuart H; Sakai, Yasuo; Morasso, Maria I

    2012-11-16

    Retinoic acid (RA) is essential during embryogenesis and for tissue homeostasis, whereas excess RA is well known as a teratogen. In humans, excess RA is associated with hair loss. In the present study, we demonstrate that specific levels of RA, regulated by Cyp26b1, one of the RA-degrading enzymes, are required for hair follicle (hf) morphogenesis. Mice with embryonic ablation of Cyp26b1 (Cyp26b1(-/-)) have excessive endogenous RA, resulting in arrest of hf growth at the hair germ stage. The altered hf development is rescued by grafting the mutant skin on immunodeficient mice. Our results show that normalization of RA levels is associated with reinitiation of hf development. Conditional deficiency of Cyp26b1 in the dermis (En1Cre;Cyp26b1f/-) results in decreased hair follicle density and specific effect on hair type, indicating that RA levels also influence regulators of hair bending. Our results support the model of RA-dependent dermal signals regulating hf downgrowth and bending. To elucidate target gene pathways of RA, we performed microarray and RNA-Seq profiling of genes differentially expressed in Cyp26b1(-/-) skin and En1Cre;Cyp26b1f/- tissues. We show specific effects on the Wnt-catenin pathway and on members of the Runx, Fox, and Sox transcription factor families, indicating that RA modulates pathways and factors implicated in hf downgrowth and bending. Our results establish that proper RA distribution is essential for morphogenesis, development, and differentiation of hfs. PMID:23007396

  11. Cutaneous Retinoic Acid Levels Determine Hair Follicle Development and Downgrowth*

    PubMed Central

    Okano, Junko; Levy, Clara; Lichti, Ulrike; Sun, Hong-Wei; Yuspa, Stuart H.; Sakai, Yasuo; Morasso, Maria I.

    2012-01-01

    Retinoic acid (RA) is essential during embryogenesis and for tissue homeostasis, whereas excess RA is well known as a teratogen. In humans, excess RA is associated with hair loss. In the present study, we demonstrate that specific levels of RA, regulated by Cyp26b1, one of the RA-degrading enzymes, are required for hair follicle (hf) morphogenesis. Mice with embryonic ablation of Cyp26b1 (Cyp26b1−/−) have excessive endogenous RA, resulting in arrest of hf growth at the hair germ stage. The altered hf development is rescued by grafting the mutant skin on immunodeficient mice. Our results show that normalization of RA levels is associated with reinitiation of hf development. Conditional deficiency of Cyp26b1 in the dermis (En1Cre;Cyp26b1f/−) results in decreased hair follicle density and specific effect on hair type, indicating that RA levels also influence regulators of hair bending. Our results support the model of RA-dependent dermal signals regulating hf downgrowth and bending. To elucidate target gene pathways of RA, we performed microarray and RNA-Seq profiling of genes differentially expressed in Cyp26b1−/− skin and En1Cre;Cyp26b1f/− tissues. We show specific effects on the Wnt-catenin pathway and on members of the Runx, Fox, and Sox transcription factor families, indicating that RA modulates pathways and factors implicated in hf downgrowth and bending. Our results establish that proper RA distribution is essential for morphogenesis, development, and differentiation of hfs. PMID:23007396

  12. Preparation and characterization of mesoporous N-doped and sulfuric acid treated anatase TiO 2 catalysts and their photocatalytic activity under UV and Vis illumination

    NASA Astrophysics Data System (ADS)

    Kun, Robert; Tarján, Sándor; Oszkó, Albert; Seemann, Torben; Zöllmer, Volker; Busse, Matthias; Dékány, Imre

    2009-11-01

    Nitrogen-doped TiO 2 catalysts were prepared by a precipitation method. The samples were calcined at 400 °C for 4 h in air. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), low temperature N 2-adsorption was used for structural characterization and UV-diffuse reflectance (UV-DR) was applied to investigate the optical properties of the as-prepared samples. It was found that microporous N-doped catalysts have solely anatase crystalline structure. Acidic treatment of the calcined samples was performed using sulfuric acid agitation. The crystalline structure remained unchanged due to surface treatment, while the porosity and the surface areas (aBETS) were decreased dramatically. Optical characterization of the doped catalysts showed that they could be excited by visible light photons in the 400-500 nm wavelength range ( λ g,1=˜390 nm, λ g,2=˜510 nm). It was also established that surface treatment enhances the Vis-light absorption of the N-TiO 2 powders. Finally the catalysts were tested in the photocatalytic degradation of phenol in aqueous suspensions. Two different light sources were used; one of them was a UV-rich high pressure Hg-lamp, while the other was a tubular visible light source. We found that using visible light illumination N-doped, acid treated TiO 2 samples were more catalytically active than non-doped TiO 2 catalysts.

  13. Dependence of intestinal amino acid uptake on dietary protein or amino acid levels

    SciTech Connect

    Karasov, W.H.; Solberg, D.H.; Diamond, J.M.

    1987-05-01

    To understand how intestinal amino acid (AA) transport is regulated by dietary substrate levels, the authors measured uptake of seven radioactively-labelled AAs and glucose across the jejunal brush-border membrane of mice kept on one of three isocaloric rations differing in nitrogen content. In the high-protein ration, uptake increased by 77-81% for the nonessential, less toxic AAs, proline, and aspartate but only by 32-61% for the more toxic essential AAs tested. In the nitrogen-deficient ration, uptake decreased for the nonessential aspartate and proline but stayed constant or increased for essential AAs and for the nonessential alanine. These patterns imply independent regulation of the intestine's various AA transporters. With decreasing dietary AA (or protein), the imino acid and acidic AA private transporters are repressed, while activities of the basic AA transporter and the neutral AA public transporter decrease to an asymptote or else go through a minimum. These regulatory patterns can be understood as a compromise among conflicting constraints imposed by protein's multiple roles as a source of calories, nitrogen, and essential AAs and by the toxicity of essential AAs at high concentrations.

  14. Au/ZnO hybrid nanocatalysts impregnated in N-doped graphene for simultaneous determination of ascorbic acid, acetaminophen and dopamine.

    PubMed

    Chen, Xianlan; Zhang, Guowei; Shi, Ling; Pan, Shanqing; Liu, Wei; Pan, Hiabo

    2016-08-01

    The formation of nitrogen-doped (N-doped) graphene uses hydrothermal method with urea as reducing agent and nitrogen source. The surface elemental composition of the catalyst was analyzed through XPS, which showed a high content of a total N species (7.12at.%), indicative of the effective N-doping, present in the form of pyridinic N, pyrrolic N and graphitic N groups. Moreover, Au nanoparticles deposited on ZnO nanocrystals surface, forming Au/ZnO hybrid nanocatalysts, undergo a super-hydrophobic to super-hydrophilic conversion. Herein, we present Au/ZnO hybrid nanocatalysts impregnated in N-doped graphene sheets through sonication technique of the Au/ZnO/N-doped graphene hybrid nanostructures. The as-prepared Au/ZnO/N-doped graphene hybrid nanostructure modified glassy carbon electrode (Au/ZnO/N-doped graphene/GCE) was first employed for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and acetaminophen (AC). The oxidation over-potentials of AA, DA and AC decreased dramatically, and their oxidation peak currents increased significantly at Au/ZnO/N-doped graphene/GCE compared to those obtained at the N-doped graphene/GCE and bare CCE. The peak separations between AA and DA, DA and AC, and AC and AA are large up to 195, 198 and 393mV, respectively. The calibration curves for AA, DA and AC were obtained in the range of 30.00-13.00×10(3), 2.00-0.18×10(3) and 5.00-3.10×10(3)μM, respectively. The detection limits (S/N=3) were 5.00, 0.40 and 0.80μM for AA, DA and AC, respectively. PMID:27157730

  15. Piezoresistivity of polycrystalline p-type diamond films of various doping levels at different temperatures

    SciTech Connect

    Wang, W.L.; Jiang, X.; Taube, K.; Klages, C.

    1997-07-01

    The piezoresistivity of polycrystalline p-type diamond films has been studied. The films were grown by microwave plasma assisted chemical vapor deposition and {ital in situ} doped with different concentrations of boron. A four-point electrical measurement was performed to evaluate the film resistivity change upon straining in a four-point bending beam setup. Films were glued directly onto a stainless steel beam and the silicon substrates were selectively removed. A gauge factor (relative change of the resistivity divided by the elastic strain) of about 690 under 100 microstrains was obtained at room temperature for a film doped with 32 ppm boron. With increasing temperature and dopant concentration the gauge factor increases. The experimental results obtained are discussed. {copyright} {ital 1997 American Institute of Physics.}

  16. Delta-Doping at Wafer Level for High Throughput, High Yield Fabrication of Silicon Imaging Arrays

    NASA Technical Reports Server (NTRS)

    Hoenk, Michael E. (Inventor); Nikzad, Shoulch (Inventor); Jones, Todd J. (Inventor); Greer, Frank (Inventor); Carver, Alexander G. (Inventor)

    2014-01-01

    Systems and methods for producing high quantum efficiency silicon devices. A silicon MBE has a preparation chamber that provides for cleaning silicon surfaces using an oxygen plasma to remove impurities and a gaseous (dry) NH3 + NF3 room temperature oxide removal process that leaves the silicon surface hydrogen terminated. Silicon wafers up to 8 inches in diameter have devices that can be fabricated using the cleaning procedures and MBE processing, including delta doping.

  17. Electrochemical mineralization of perfluorocarboxylic acids (PFCAs) by ce-doped modified porous nanocrystalline PbO2 film electrode.

    PubMed

    Niu, Junfeng; Lin, Hui; Xu, Jiale; Wu, Hao; Li, Yangyang

    2012-09-18

    The Ce-doped modified porous nanocrystalline PbO(2) film electrode prepared by electrodeposition technology was used for electrochemical mineralization of environmentally persistent perfluorinated carboxylic acids (PFCAs) (~C(4)-C(8)), i.e., perfluorobutanoic acid (PFBA), perfluopentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoheptanoic acid (PFHpA), and perfluorooctanoic acid (PFOA) in aqueous solution (100 mL of 100 mg L(-1)). The degradation of PFCAs follows pseudo-first-order kinetics, and the values of the relative rate constant (k) depend upon chain length k(PFHpA) (4.1 × 10(-2) min(-1); corresponding half-life 16.8 min) ≈ 1.1k(PFOA) ≈ 2.5k(PFHxA)≈ 6.9k(PFPeA) ≈ 9.7k(PFBA). The carbon mineralization indices [i.e., 1 - (TOC(insolution)/TOC(inPFCA,degraded))] were 0.49, 0.70, 0.84, 0.91, and 0.95 for PFBA, PFPeA, PFHxA, PFHpA, and PFOA, respectively, after 90 min electrolysis. The major mineralization product, F(-), as well as low amount of intermediate PFCAs with shortened chain lengths were detected in aqueous solution. By observing the intermediates and tracking the concentration change, a possible pathway of electrochemical mineralization is proposed as follows: Kolbe decarboxylation reaction occurs first at the anode to form the perfluoroalkyl radical, followed by reaction with hydroxyl radicals to form the perfluoroalkyl alcohol which then undergoes intramolecular rearrangement to form the perfluoroalkyl fluoride. After this, the perfluoroalkyl fluoride reforms perfluorinated carboxylic with shorter chain length than its origin by hydrolysis. This electrochemical technique could be employed to treat PFCAs (~C(4)-C(8)) in contaminated wastewater. PMID:22913426

  18. Tunable phase control of slow and fast light propagation in a slab doped by four-level quantum dot nanostructure

    NASA Astrophysics Data System (ADS)

    Jafarzadeh, Hossein; Sangachin, Elnaz Ahmadi; Asadpour, Seyyed Hossein

    2015-12-01

    Tunable phase control of the slow and fast light propagation through a defect slab medium doped by four-level InGaN/GaN quantum dot structure is demonstrated. By solving the Schrödinger and Poisson’s equations self-consistently, a spherical InGaN quantum dot with GaN barrier shell which can interact by terahertz (THz) signal field is designed numerically. It is found that the phase variation of THz signal field imparts the tunability in the group velocity of the transmitted and reflected pulses through a dielectric slab.

  19. A diode-pumped Nd3+-doped gadolinium gallium garnet quasi-three-level laser at 933 nm

    NASA Astrophysics Data System (ADS)

    Liu, J. H.; Han, Y. H.; Zhao, Y. D.

    2013-11-01

    We report for the first time a Nd3+-doped gadolinium gallium garnet (Nd:GGG) laser operating on a quasi-three-level laser at 933 nm, based on the 4F3/2-4I9/2 transition. Continuous wave 691 mW output power at 933 nm is obtained under 10.2 W of incident pump power. Moreover, intracavity second-harmonic generation has also been achieved with a blue power of 89 mW by using a LiB3O5 (LBO) nonlinear crystal.

  20. Preparation and characterization of mesoporous N-doped and sulfuric acid treated anatase TiO{sub 2} catalysts and their photocatalytic activity under UV and Vis illumination

    SciTech Connect

    Kun, Robert; Tarjan, Sandor; Oszko, Albert; Seemann, Torben; Zoellmer, Volker; Busse, Matthias; Dekany, Imre

    2009-11-15

    Nitrogen-doped TiO{sub 2} catalysts were prepared by a precipitation method. The samples were calcined at 400 deg. C for 4 h in air. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), low temperature N{sub 2}-adsorption was used for structural characterization and UV-diffuse reflectance (UV-DR) was applied to investigate the optical properties of the as-prepared samples. It was found that microporous N-doped catalysts have solely anatase crystalline structure. Acidic treatment of the calcined samples was performed using sulfuric acid agitation. The crystalline structure remained unchanged due to surface treatment, while the porosity and the surface areas (a{sub BET}{sup S}) were decreased dramatically. Optical characterization of the doped catalysts showed that they could be excited by visible light photons in the 400-500 nm wavelength range (lambda{sub g,1}={approx}390 nm, lambda{sub g,2}={approx}510 nm). It was also established that surface treatment enhances the Vis-light absorption of the N-TiO{sub 2} powders. Finally the catalysts were tested in the photocatalytic degradation of phenol in aqueous suspensions. Two different light sources were used; one of them was a UV-rich high pressure Hg-lamp, while the other was a tubular visible light source. We found that using visible light illumination N-doped, acid treated TiO{sub 2} samples were more catalytically active than non-doped TiO{sub 2} catalysts. - Graphical abstract: The effect of the acid treatment on the visible-light-driven photocatalytic activity of the N-doped, anatase TiO{sub 2} catalysts.

  1. Nitrogen-doped carbon-TiO2 composite as support of Pd electrocatalyst for formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Qin, Yuan-Hang; Li, Yunfeng; Lam, Thomas; Xing, Yangchuan

    2015-06-01

    We report Pd nanoparticles supported on a composite consisting of oxide TiO2 and nitrogen-doped carbon for formic acid oxidation (FAO). The nitrogen-doped carbon-TiO2 (NCx-TiO2) composite support was prepared by a simple polymerization-pyrolysis process using commercial TiO2 nanoparticles (P25). Surface analysis showed that elements of Ti, C, O, and N were present on the composite surface, on which nitrogen existed in both pyridinic and quaternary forms. Pd nanoparticles with a mean size of ca. 4 nm were uniformly deposited on the composite via a polyol process. Electrochemical characterizations showed that the NCx-TiO2-supported Pd particles (Pd/NCx-TiO2) exhibited an electrocatalytic activity towards FAO that almost doubled that of the carbon black-supported Pd particles (Pd/C) with much enhanced electrocatalytic stability. The better performance of the composite supported Pd was attributed to a possible electronic structure modification in the metallic Pd particles and bifunctional effect produced by the NCx-TiO2 composite.

  2. Depth profiling of 4-acetamindophenol-doped poly(lactic acid) films using cluster secondary ion mass spectrometry.

    PubMed

    Mahoney, Christine M; Roberson, Sonya V; Gillen, Greg

    2004-06-01

    The feasibility of using cluster secondary ion mass spectrometry for depth profiling of drug delivery systems is explored. The behavior of various biodegradable polymer films under dynamic SF(5)(+) primary ion bombardment was investigated, including several films doped with model drugs. The SF(5)(+) depth profiles obtained from these biodegradable polymer films showed very little degradation in secondary ion signal as a function of increasing primary ion dose, and it was discovered that the characteristic ion signals for the polymers remained constant for ion doses up to approximately 5 x 10(15) ions/cm(2). These results suggest that the polyester structure of the biodegradable polymers studied here allows for a greater ability to depth profile due to ease of main chain scission. Attempts were also made to depth profile through a series of poly(lactic acid) (PLA) films containing varying concentrations of the drug 4-acetamidophenol. The depth profiles obtained from these films show very little decrease in both the 4-acetamidophenol molecular ion and PLA fragment ion signals as a function of increasing SF(5)(+) primary ion dose. Similar results were obtained with theophylline-doped PLA films. These results show that, in some drug delivery devices, it is possible to monitor the distribution of a drug as a function of depth by using cluster primary ion beams. PMID:15167802

  3. Chlorine-doped reduced graphene oxide nanosheets as an efficient and stable electrode for supercapacitor in acidic medium.

    PubMed

    Kakaei, Karim; Hamidi, Milad; Husseindoost, Somayeh

    2016-10-01

    We demonstrate the efficient doping of reduced graphene oxide (RGO) by Chlorine and its capacitive performance was calculated by cyclic voltammetry and charge-discharge cycling in 1M H2SO4 solution. In this regard, we are prepared RGO nanosheets through a simple, eco-friendly and efficient electrochemical method, with selectively functionalized edges by chlorine which involves added the RGO to the halogen-containing acid solution and dispersed by ultrasonic. After synthesis, Cl-RGO is characterized using X-ray diffraction, Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, Energy-dispersive X-ray (EDX) spectroscopy and tunneling electron microscopy. FTIR spectra show the chlorine-containing functional groups. Energy-dispersive X-ray spectroscopy analysis confirmed the presence of doped chlorine in RGO. Raman spectroscopy shows a high density of defects in the RGO layer. Electrochemical characteristics of Cl-RGO are characterized by cyclic voltammetery, galvanostatic charge/discharge and electrochemical impedance spectroscopy. According to the galvanostatic charge/discharge analysis, Cl-RGO represents specific capacitance (Cs) of 178.4Fg(-1) at current density of 1Ag(-1), which is higher than that of RGO (100.5Fg(-1)) in H2SO4 solution. PMID:27388125

  4. Aluminum-doped zinc oxide nanoparticles attenuate the TSLP levels via suppressing caspase-1 in activated mast cells.

    PubMed

    Kim, Min-Ho; Seo, Jun-Ho; Kim, Hyung-Min; Jeong, Hyun-Ja

    2016-04-01

    Zinc oxide nanoparticles (ZO-NPs) are used as antimicrobials, anti-inflammatories, and to treat cancer. However, although ZO-NPs have excellent efficiency and specificity, their cytotoxicity is higher than that of micron-sized zinc oxide. Doping ZO-NPs with aluminum can improve therapeutic efficacy, but the biological effects and mechanisms involved have not been elucidated. Here, we reported the efficacy of aluminum-doped ZO-NP (AZO) on thymic stromal lymphopoietin (TSLP) production and caspase-1 activation in human mast cell line, HMC-1 cells. AZO significantly reduced TSLP levels as well as interleukin (IL)-6, IL-8, and tumor necrosis factor (TNF)-α without inducing cytotoxicity. Furthermore, AZO more effectively reduced TSLP, IL-6, IL-8, and TNF-α levels than ZO-NP. The levels of inflammatory cytokine mRNA were also reduced by AZO treatment. AZO blocked production of IL-1β and activations of caspase-1 and nuclear factor-κB by inhibiting IκB kinase β and receptor interacting protein 2. In addition, AZO attenuated phosphorylation of mitogen-activated protein kinases, such as extracellular signal-regulated kinase, c-Jun N-terminal kinases, and p38. These findings provide evidence that AZO improves anti-inflammatory properties and offer a safe and effective potential treatment option. PMID:26825457

  5. Uptake measurements of acetic acid on ice and nitric acid-doped thin ice films over upper troposphere/lower stratosphere temperatures.

    PubMed

    Romanias, Manolis N; Zogka, Antonia G; Papadimitriou, Vassileios C; Papagiannakopoulos, Panos

    2012-03-01

    The adsorption of gaseous acetic acid (CH(3)C(O)OH) on thin ice films and on ice doped with nitric acid (1.96 and 7.69 wt %) was investigated over upper troposphere and lower stratosphere (UT/LS) temperatures (198-208 K), and at low gas concentrations. Experiments were performed in a Knudsen flow reactor coupled to a quadrupole mass spectrometer. The initial uptake coefficients, γ(0), on thin ice films or HNO(3)-doped ice films were measured at low surface coverage. In all cases, γ(0) showed an inverse temperature dependence, and for pure thin ice films, it was given by the expression γ(0)(T) = (4.73 ± 1.13) × 10(-17) exp[(6496 ± 1798)/T]; the quoted errors are the 2σ precision of the linear fit, and the estimated systematic uncertainties are included in the pre-exponential factor. The inverse temperature dependence suggests that the adsorption process occurs via the formation of an intermediate precursor state. Uptakes were well represented by the Langmuir adsorption model, and the saturation surface coverage, N(max), on pure thin ice films was (2.11 ± 0.16) × 10(14) molecules cm(-2), independent of temperature in the range 198-206 K. Light nitration (1.96 and 7.69 wt %) of ice films resulted in more efficient CH(3)C(O)OH uptakes and larger N(max) values that may be attributed to in-bulk diffusion or change in nature of the gas-ice surface interaction. Finally, it was estimated that the rate of adsorption of acetic acid on high-density cirrus clouds in the UT/LS is fast, and this is reflected in the short atmospheric lifetimes (2-8 min) of acetic acid; however, the extent of this uptake is minor resulting in at most a 5% removal of acetic acid in UT/LS cirrus clouds. PMID:22313232

  6. Chicoric Acid Levels in Basil (Ocimum basilicum L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recently, we reported the presence of chicoric acid in basil leaves (confirmed by co-chromatography with purchased standard). Chicoric acid being the chief phenolic of the Echinacea purpurea plant which is popularly consumed as a dietary supplement. For this study, basil products commonly purchased ...

  7. Novel Proton Conducting Solid Bio-polymer Electrolytes Based on Carboxymethyl Cellulose Doped with Oleic Acid and Plasticized with Glycerol

    NASA Astrophysics Data System (ADS)

    Chai, M. N.; Isa, M. I. N.

    2016-06-01

    The plasticized solid bio-polymer electrolytes (SBEs) system has been formed by introducing glycerol (Gly) as the plasticizer into the carboxymethyl cellulose (CMC) doped with oleic acid (OA) via solution casting techniques. The ionic conductivity of the plasticized SBEs has been studied using Electrical Impedance Spectroscopy. The highest conductivity achieved is 1.64 × 10‑4 S cm‑1 for system containing 40 wt. % of glycerol. FTIR deconvolution technique had shown that the conductivity of CMC-OA-Gly SBEs is primarily influenced by the number density of mobile ions. Transference number measurement has shown that the cation diffusion coefficient and ionic mobility is higher than anion which proved the plasticized polymer system is a proton conductor.

  8. Tannic acid functionalized N-doped graphene modified glassy carbon electrode for the determination of bisphenol A in food package.

    PubMed

    Jiao, Shoufeng; Jin, Jing; Wang, Lun

    2014-05-01

    A rapid, environmental friendly, and sensitive sensor for the detection of bisphenol A (BPA) was developed at glassy carbon electrode (GCE) modified with Tannic acid functionalized N-doped graphene (TA/N-G) immobilized by Nafion. Compared with other sensors, the proposed sensor greatly enhanced the response signal of BPA due to the active surface area of N-G and high absorption efficiency of TA. Under the optimal conditions, the oxidation current increased linearly with increasing the concentration of BPA in the range of 0.05-13 µM with the detection limit of 4.0 nM. The fabricated electrode showed good reproducibility, stability and anti-interference. The developed electrochemical sensor was successfully applied to determine BPA in food package. PMID:24720975

  9. Dehydrogenation of Formic Acid at Room Temperature: Boosting Palladium Nanoparticle Efficiency by Coupling with Pyridinic-Nitrogen-Doped Carbon.

    PubMed

    Bi, Qing-Yuan; Lin, Jian-Dong; Liu, Yong-Mei; He, He-Yong; Huang, Fu-Qiang; Cao, Yong

    2016-09-19

    The use of formic acid (FA) to produce molecular H2 is a promising means of efficient energy storage in a fuel-cell-based hydrogen economy. To date, there has been a lack of heterogeneous catalyst systems that are sufficiently active, selective, and stable for clean H2 production by FA decomposition at room temperature. For the first time, we report that flexible pyridinic-N-doped carbon hybrids as support materials can significantly boost the efficiency of palladium nanoparticle for H2 generation; this is due to prominent surface electronic modulation. Under mild conditions, the optimized engineered Pd/CN0.25 catalyst exhibited high performance in both FA dehydrogenation (achieving almost full conversion, and a turnover frequency of 5530 h(-1) at 25 °C) and the reversible process of CO2 hydrogenation into FA. This system can lead to a full carbon-neutral energy cycle. PMID:27552650

  10. Novel Proton Conducting Solid Bio-polymer Electrolytes Based on Carboxymethyl Cellulose Doped with Oleic Acid and Plasticized with Glycerol

    PubMed Central

    Chai, M. N.; Isa, M. I. N.

    2016-01-01

    The plasticized solid bio-polymer electrolytes (SBEs) system has been formed by introducing glycerol (Gly) as the plasticizer into the carboxymethyl cellulose (CMC) doped with oleic acid (OA) via solution casting techniques. The ionic conductivity of the plasticized SBEs has been studied using Electrical Impedance Spectroscopy. The highest conductivity achieved is 1.64 × 10−4 S cm−1 for system containing 40 wt. % of glycerol. FTIR deconvolution technique had shown that the conductivity of CMC-OA-Gly SBEs is primarily influenced by the number density of mobile ions. Transference number measurement has shown that the cation diffusion coefficient and ionic mobility is higher than anion which proved the plasticized polymer system is a proton conductor. PMID:27265642

  11. Voltammetric determination of mixtures of caffeine and chlorogenic acid in beverage samples using a boron-doped diamond electrode.

    PubMed

    Yardım, Yavuz; Keskin, Ertugrul; Şentürk, Zühre

    2013-11-15

    Herein, a boron-doped diamond (BDD) electrode that is anodically pretreated was used for the simultaneous determination of caffeine (CAF) and chlorogenic acid (CGA) by cyclic and adsorptive stripping voltammetry. The dependence of peak current and potential on pH, scan rate, accumulation parameters and other experimental variables were studied. By using square-wave stripping mode after 60 s accumulation under open-circuit voltage, the BDD electrode was able to separate the oxidation peak potentials of CAF and CGA present in binary mixtures by about 0.4V in Britton-Robinson buffer at pH 1.0. The limits of detection were 0.107 µg mL(-1) (5.51×10(-7) M) for CAF, and 0.448 µg mL(-1) (1.26×10(-6) M) for CGA. The practical applicability of this methodology was tested in commercially available beverage samples. PMID:24148509

  12. Chemometric study on the electrochemical incineration of nitrilotriacetic acid using platinum and boron-doped diamond anode.

    PubMed

    Zhang, Chunyong; He, Zhenzhu; Wu, Jingyu; Fu, Degang

    2015-07-01

    This study investigated the electrochemical incineration of nitrilotriacetic acid (NTA) at boron-doped diamond (BDD) and platinum (Pt) anodes. Trials were performed in the presence of sulfate electrolyte media under recirculation mode. The parameters that influence the degradation efficiency were investigated, including applied current density, flow rate, supporting electrolyte concentration and reaction time. To reduce the number of experiments, the system had been managed under chemometric technique named Doehlert matrix. As a consequence, the mineralization of NTA demonstrated similar behavior upon operating parameters on these two anodes. Further kinetic study indicated that the degradations followed pseudo-first-order reactions for both BDD and Pt anodes, and the reaction rate constant of the former was found to be higher than that of the latter. Such difference could be interpreted by results from fractal analysis. In addition, a reaction sequence for NTA mineralization considering all the detected intermediates was also proposed. PMID:25747300

  13. Gut Microbial Fatty Acid Metabolites Reduce Triacylglycerol Levels in Hepatocytes.

    PubMed

    Nanthirudjanar, Tharnath; Furumoto, Hidehiro; Zheng, Jiawen; Kim, Young-Il; Goto, Tsuyoshi; Takahashi, Nobuyuki; Kawada, Teruo; Park, Si-Bum; Hirata, Akiko; Kitamura, Nahoko; Kishino, Shigenobu; Ogawa, Jun; Hirata, Takashi; Sugawara, Tatsuya

    2015-11-01

    Hydroxy and oxo fatty acids were recently found to be produced as intermediates during gut microbial fatty acid metabolism. Lactobacillus plantarum produces these fatty acids from unsaturated fatty acids such as linoleic acid. In this study, we investigated the effects of these gut microbial fatty acid metabolites on the lipogenesis in liver cells. We screened their effect on sterol regulatory element binding protein-1c (SREBP-1c) expression in HepG2 cells treated with a synthetic liver X receptor α (LXRα) agonist (T0901317). The results showed that 10-hydroxy-12(Z)-octadecenoic acid (18:1) (HYA), 10-hydroxy-6(Z),12(Z)-octadecadienoic acid (18:2) (γHYA), 10-oxo-12(Z)-18:1 (KetoA), and 10-oxo-6(Z),12(Z)-18:2 (γKetoA) significantly decreased SREBP-1c mRNA expression induced by T0901317. These fatty acids also downregulated the mRNA expression of lipogenic genes by suppressing LXRα activity and inhibiting SREBP-1 maturation. Oral administration of KetoA, which effectively reduced triacylglycerol accumulation and acetyl-CoA carboxylase 2 (ACC2) expression in HepG2 cells, for 2 weeks significantly decreased Srebp-1c, Scd-1, and Acc2 expression in the liver of mice fed a high-sucrose diet. Our findings suggest that the hypolipidemic effect of the fatty acid metabolites produced by L. plantarum can be exploited in the treatment of cardiovascular diseases or dyslipidemia. PMID:26399511

  14. 300 W-level, wavelength-widely-tunable, all-fiber integrated thulium-doped fiber laser.

    PubMed

    Yin, Ke; Zhu, Rongzhen; Zhang, Bin; Liu, Guangchen; Zhou, Pu; Hou, Jing

    2016-05-16

    A high-power, wavelength-tunable, all-fiber integrated thulium-doped fiber laser (TDFL) at 2 μm is presented. The TDFL has a compact configuration which only consists of a low power seed oscillator and a stage of fiber power amplifier. The seed oscillator adopts a tunable band-pass filter as the wavelength selective element, matching the gain spectrum of thulium-doped fiber. It can provide ~5 W single-mode seed laser with superb spectral characteristics, and the lasing wavelength is adjustable from 1890 to 2050 nm. The fiber power amplifier provides a total gain of ~17 dB at 2 μm which boosts the signal power to the 300 W-level. The maximum average power reaches 327.5 W at 1930 nm with the highest slope efficiency of 57.4%. This TDFL can afford >270 W lasing operation over the whole tuning range of 140 nm spanning from 1910 to 2050 nm, together with high spectral quality and power stability. This is the first demonstration, to the best of our knowledge, on an all-fiber integrated wavelength-widely-tunable TDFL at 2 μm with output power at the 300 W-level. The results are of great interest for many applications. PMID:27409931

  15. Quantum effect on the energy levels of Eu2+ doped K2Ca2(SO4)3 nanoparticles.

    PubMed

    Salah, Numan; Habib, Sami S; Khan, Zishan H

    2010-09-01

    Quantum confinement effect on the energy levels of Eu(2+) doped K(2)Ca(2)(SO(4))(3) nanoparticles has been observed. The broad photoluminescence (PL) emission band of Eu(2+) doped K(2)Ca(2)(SO(4))(3) microcrystalline sample observed at ∼436 nm is found to split into two narrow well resolved bands, located at 422 and 445 nm in the nanostructure form of this material. This has been attributed to the reduction in the crystal field strength of the nanomaterials, which results in widening the energy band gap and splitting the broad 4f(6)5d energy level of Eu(2+). Energy band gap values of the micro and nanocrystalline K(2)Ca(2)(SO(4))(3) samples were also determined by measuring the UV-visible absorption spectra. These values are 3.34 and 3.44 eV for the micro and nanocrystalline samples, respectively. These remarkable results suggest that activators having wide emission bands might be subjected to weak crystal strength via nanostructure materials to modify their electronic transitions. This might prove a powerful technique for producing new-advanced materials for use in the fields of solid state lasers and optoelectronic devises. PMID:20386964

  16. Aluminum doping tunes band gap energy level as well as oxidative stress-mediated cytotoxicity of ZnO nanoparticles in MCF-7 cells

    NASA Astrophysics Data System (ADS)

    Akhtar, Mohd Javed; Alhadlaq, Hisham A.; Alshamsan, Aws; Majeed Khan, M. A.; Ahamed, Maqusood

    2015-09-01

    We investigated whether Aluminum (Al) doping tunes band gap energy level as well as selective cytotoxicity of ZnO nanoparticles in human breast cancer cells (MCF-7). Pure and Al-doped ZnO nanoparticles were prepared by a simple sol-gel method. Characterization study confirmed the formation of single phase of AlxZn1-xO nanocrystals with the size range of 33-55 nm. Al-doping increased the band gap energy of ZnO nanoparticles (from 3.51 eV for pure to 3.87 eV for Al-doped ZnO). Al-doping also enhanced the cytotoxicity and oxidative stress response of ZnO nanoparticles in MCF-7 cells. The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml. Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 & caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway. Importantly, Al-doping did not change the benign nature of ZnO nanoparticles towards normal cells suggesting that Al-doping improves the selective cytotoxicity of ZnO nanoparticles toward MCF-7 cells without affecting the normal cells. Our results indicated a novel approach through which the inherent selective cytotoxicity of ZnO nanoparticles against cancer cells can be further improved.

  17. Aluminum doping tunes band gap energy level as well as oxidative stress-mediated cytotoxicity of ZnO nanoparticles in MCF-7 cells.

    PubMed

    Akhtar, Mohd Javed; Alhadlaq, Hisham A; Alshamsan, Aws; Majeed Khan, M A; Ahamed, Maqusood

    2015-01-01

    We investigated whether Aluminum (Al) doping tunes band gap energy level as well as selective cytotoxicity of ZnO nanoparticles in human breast cancer cells (MCF-7). Pure and Al-doped ZnO nanoparticles were prepared by a simple sol-gel method. Characterization study confirmed the formation of single phase of Al(x)Zn(1-x)O nanocrystals with the size range of 33-55 nm. Al-doping increased the band gap energy of ZnO nanoparticles (from 3.51 eV for pure to 3.87 eV for Al-doped ZnO). Al-doping also enhanced the cytotoxicity and oxidative stress response of ZnO nanoparticles in MCF-7 cells. The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml. Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 &caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway. Importantly, Al-doping did not change the benign nature of ZnO nanoparticles towards normal cells suggesting that Al-doping improves the selective cytotoxicity of ZnO nanoparticles toward MCF-7 cells without affecting the normal cells. Our results indicated a novel approach through which the inherent selective cytotoxicity of ZnO nanoparticles against cancer cells can be further improved. PMID:26347142

  18. Aluminum doping tunes band gap energy level as well as oxidative stress-mediated cytotoxicity of ZnO nanoparticles in MCF-7 cells

    PubMed Central

    Akhtar, Mohd Javed; Alhadlaq, Hisham A.; Alshamsan, Aws; Majeed Khan, M.A.; Ahamed, Maqusood

    2015-01-01

    We investigated whether Aluminum (Al) doping tunes band gap energy level as well as selective cytotoxicity of ZnO nanoparticles in human breast cancer cells (MCF-7). Pure and Al-doped ZnO nanoparticles were prepared by a simple sol-gel method. Characterization study confirmed the formation of single phase of AlxZn1-xO nanocrystals with the size range of 33–55 nm. Al-doping increased the band gap energy of ZnO nanoparticles (from 3.51 eV for pure to 3.87 eV for Al-doped ZnO). Al-doping also enhanced the cytotoxicity and oxidative stress response of ZnO nanoparticles in MCF-7 cells. The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml. Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 & caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway. Importantly, Al-doping did not change the benign nature of ZnO nanoparticles towards normal cells suggesting that Al-doping improves the selective cytotoxicity of ZnO nanoparticles toward MCF-7 cells without affecting the normal cells. Our results indicated a novel approach through which the inherent selective cytotoxicity of ZnO nanoparticles against cancer cells can be further improved. PMID:26347142

  19. Research progress of chelate precursor doping method to fabricate Yb-doped large-mode-area silica fibers for kW-level laser

    NASA Astrophysics Data System (ADS)

    Wang, Zhen; Zhan, Huan; Ni, Li; Peng, Kun; Wang, Xiaolong; Wang, Jianjun; Jing, Feng; Lin, Aoxiang

    2015-11-01

    With continuous efforts and practical managing experiences, the chelate precursor doping method has been justified as an effective way to dope rare-earth ions into silica host materials, a key technique in making large-mode-area silica fibers for high power laser applications. It is characterized by good controllability, stability and repeatability to accomplish different refractive index profiles. Different preforms with a large core, designed refractive index profile, good symmetrical shape and homogeneous elemental distribution were successfully fabricated. The home-made standard 20/400-type double-cladding Yb-doped large-mode-area silica fiber was drawn and presented a 1.6 kW laser output at 1064 nm, the highest power record publically reported with this method. With further optimization, chelate precusor doping method has potential to manufacture high power laser fibers for the next generation.

  20. Nitrogen-doped, FeNi alloy nanoparticle-decorated graphene as an efficient and stable electrode for electrochemical supercapacitors in acid medium.

    PubMed

    El-Deen, Ahmed G; El-Newehy, Mohamed; Kim, Cheol Sang; Barakat, Nasser Am

    2015-01-01

    Nitrogen-doped graphene decorated by iron-nickel alloy is introduced as a promising electrode material for supercapacitors. Compared to pristine and Ni-decorated graphene, in acid media, the introduced electrode revealed excellent specific capacitance as the corresponding specific capacitance was multiplied around ten times with capacity retention maintained at 94.9% for 1,000 cycles. Briefly, iron acetate, nickel acetate, urea, and graphene oxide were ultrasonicated and subjected to MW heating and then sintered with melanin in Ar. The introduced N-doped FeNi@Gr exhibits remarkable electrochemical behavior with long-term stability. PMID:25852399

  1. Nitrogen-doped, FeNi alloy nanoparticle-decorated graphene as an efficient and stable electrode for electrochemical supercapacitors in acid medium

    NASA Astrophysics Data System (ADS)

    El-Deen, Ahmed G.; El-Newehy, Mohamed; Kim, Cheol Sang; Barakat, Nasser AM

    2015-03-01

    Nitrogen-doped graphene decorated by iron-nickel alloy is introduced as a promising electrode material for supercapacitors. Compared to pristine and Ni-decorated graphene, in acid media, the introduced electrode revealed excellent specific capacitance as the corresponding specific capacitance was multiplied around ten times with capacity retention maintained at 94.9% for 1,000 cycles. Briefly, iron acetate, nickel acetate, urea, and graphene oxide were ultrasonicated and subjected to MW heating and then sintered with melanin in Ar. The introduced N-doped FeNi@Gr exhibits remarkable electrochemical behavior with long-term stability.

  2. Hole-level structure of double δ-doped quantum wells in Si: The influence of the split-off band

    NASA Astrophysics Data System (ADS)

    Rodríguez-Vargas, I.; Gaggero-Sager, L. M.

    2007-02-01

    We present the electronic structure calculation of two closely p-type δ-doped quantum wells within the lines of the Thomas-Fermi-Dirac (TFD) theory. The distance between the impurity planes as well as the impurity density of the δ-doped wells is varied. The exchange effects are also considered in the present study. We have paid special attention to the split-off band and its influence on the subband hole levels. We also calculate the mobility ratio of double δ-doped (DDD) quantum wells in Si with respect to a single δ-doped (SDD) one, finding the optimum distance between the wells for maximum mobility. Our results are in a good agreement with respect to the experimental data available.

  3. Assessment of Folic Acid Supplementation in Pregnant Women by Estimation of Serum Levels of Tetrahydrofolic Acid, Dihydrofolate Reductase, and Homocysteine

    PubMed Central

    Saxena, Vartika; Mirza, Anissa Atif; Kumari, Ranjeeta; Sharma, Kapil; Bharadwaj, Jyoti

    2016-01-01

    Background. Status of folic acid use in pregnant women of the hilly regions in North India was little known. This study was carried out to assess the folic acid use and estimate folate metabolites in pregnant women of this region. Materials and Methods. This cross-sectional study is comprised of 76 pregnant women, whose folic acid supplementation was assessed by a questionnaire and serum levels of homocysteine, tetrahydrofolic acid (THFA), and dihydrofolate reductase (DHFR) were estimated using Enzyme Linked Immunoassays. Results. The study data revealed awareness of folic acid use during pregnancy was present in 46.1% and 23.7% were taking folic acid supplements. The study depicted that there was no statistically significant difference between serum levels of THFA and DHFR in pregnant women with and without folic acid supplements (p = 0.790). Hyperhomocysteinemia was present in 15.78% of the participants. Conclusion. Less awareness about folic acid supplementation and low use of folic acid by pregnant women were observed in this region. Sufficient dietary ingestion may suffice for the escalated requirements in pregnancy, but since this cannot be ensured, hence folic acid supplementation should be made as an integral part of education and reproductive health programs for its better metabolic use, growth, and development of fetus. PMID:27064332

  4. Simultaneous voltammetric determination of paracetamol and ascorbic acid using a boron-doped diamond electrode modified with Nafion and lead films.

    PubMed

    Tyszczuk-Rotko, Katarzyna; Bęczkowska, Ilona; Wójciak-Kosior, Magdalena; Sowa, Ireneusz

    2014-11-01

    The paper describes the fabrication and application of a novel sensor (a boron-doped diamond electrode modified with Nafion and lead films) for the simultaneous determination of paracetamol and ascorbic acid by differential pulse voltammetry. The main advantage of the lead film and polymer covered boron-doped diamond electrode is that the sensitivity of the stripping responses is increased and the separation of paracetamol and ascorbic acid signals is improved due to the modification of the boron-doped diamond surface by the lead layer. Additionally, the repeatability of paracetamol and ascorbic acid signals is improved by the application of the Nafion film coating. In the presence of oxygen, linear calibration curves were obtained in a wide concentration range from 5×10(-7) to 2×10(-4) mol L(-1) for paracetamol and from 1×10(-6) to 5×10(-4) mol L(-1) for ascorbic acid. The analytical utility of the differential pulse voltammetric method elaborated was tested in the assay of paracetamol and ascorbic acid in commercially available pharmaceutical formulations and the method was validated by high performance liquid chromatography coupled with diode array detector. PMID:25127609

  5. Mineralization of salicylic acid in acidic aqueous medium by electrochemical advanced oxidation processes using platinum and boron-doped diamond as anode and cathodically generated hydrogen peroxide.

    PubMed

    Guinea, Elena; Arias, Conchita; Cabot, Pere Lluís; Garrido, José Antonio; Rodríguez, Rosa María; Centellas, Francesc; Brillas, Enric

    2008-01-01

    Solutions containing 164 mg L(-1) salicylic acid of pH 3.0 have been degraded by electrochemical advanced oxidation processes such as anodic oxidation, anodic oxidation with electrogenerated H(2)O(2), electro-Fenton, photoelectro-Fenton and solar photoelectro-Fenton at constant current density. Their oxidation power has been comparatively studied in a one-compartment cell with a Pt or boron-doped diamond (BDD) anode and a graphite or O(2)-diffusion cathode. In the three latter procedures, 0.5mM Fe(2+) is added to the solution to form hydroxyl radical (()OH) from Fenton's reaction between Fe(2+) and H(2)O(2) generated at the O(2)-diffusion cathode. Total mineralization is attained for all methods with BDD and for photoelectro-Fenton and solar photoelectro-Fenton with Pt. The poor decontamination achieved in anodic oxidation and electro-Fenton with Pt is explained by the slow removal of most pollutants by ()OH formed from water oxidation at the Pt anode in comparison to their quick destruction with ()OH produced at BDD. ()OH generated from Fenton's reaction oxidizes rapidly all aromatic pollutants, but it cannot destroy final Fe(III)-oxalate complexes. Solar photoelectro-Fenton treatments always yield quicker degradation rate due to the very fast photodecarboxylation of these complexes by UVA irradiation supplied by solar light. The effect of current density on the degradation rate, efficiency and energy cost of all methods is examined. The salicylic acid decay always follows a pseudo-first-order kinetics. 2,3-Dihydroxybenzoic, 2,5-dihydroxybenzoic, 2,6-dihydroxybenzoic, alpha-ketoglutaric, glycolic, glyoxylic, maleic, fumaric, malic, tartronic and oxalic acids are detected as oxidation products. A general reaction sequence for salicylic acid mineralization considering all these intermediates is proposed. PMID:17692891

  6. Salivary Sialic Acid Levels in Smokeless Tobacco Users

    PubMed Central

    Farhad Mollashahi, Leila; Honarmand, Marieh; Nakhaee, Alireza; Mollashahi, Ghasem

    2016-01-01

    Background Smokeless tobacco chewing is one of the known risk factors for oral cancer. It is consumed widely by residents of southeastern Iran. Objectives In this study, salivary free and total sialic acid, and total protein were compared in paan consumers and non-consumers. Patients and Methods In this cross-sectional study, unstimulated saliva of 94 subjects (44 paan consumers and 50 non-consumers) who were referred to the oral medicine department of the dentistry school of Zahedan were collected. Salivary free and total sialic acid, and total protein concentration were measured by standard biochemical methods, and the obtained data were analyzed using SPSS 20 through the non-parametric Mann-Whitney test. Results The concentration of salivary free sialic acid (23.21 ± 18.98 mg/L) was significantly increased in paan consumers. The concentration of salivary Total sialic acid (TSA) (39.57 ± 26.58 mg/L) and total protein (0.77 ± 0.81 mg/mL) showed increases in paan consumers, however, the results were not statistically significant. Conclusions Salivary free and total sialic acid, and total protein were higher in the paan consumers compared to non-consumers. Due to the carcinogenic effect of smokeless tobacco, measurement of these parameters in saliva may be useful in early detection of oral cancer. PMID:27622172

  7. Differential effects of cyclosporin A on transport of bile acids by rat hepatocytes: relationship to individual serum bile acid levels.

    PubMed

    Azer, S A; Stacey, N H

    1994-02-01

    Cyclosporin A treatment has been reported to induce hepatotoxicity marked by a rise in total serum bile acid and total bilirubin. The mechanism of cyclosporin A-induced hepatotoxicity seems to be related to interference with hepatocellular transport of these substrates although this remains to be fully substantiated. The purpose of this study was to investigate whether the hepatocellular uptake of the different bile acids, in the presence of cyclosporin A, is consistent with the changes in their respective individual serum bile acid concentrations. High-performance liquid chromatography has been used to assay individual serum bile acids in cyclosporin A-treated rats at doses of 0.1, 1, and 10 mg/kg/day for 4 days. Control rats were treated with Cremophor (1 ml/kg/day). At the higher doses, cyclosporin A produced a significant increase in levels of cholic acid, taurocholic acid, chenodeoxycholic acid, and deoxycholic acid compared with controls. Serum glycocholate was unaffected even at the highest dose. Inhibition of initial rate of uptake and accumulation of [14C]cholic acid, [14C]chenodeoxycholic acid, and [14C]deoxycholic acid by isolated rat hepatocytes was consistent with the changes in their respective serum bile acids. Coincubation of rat hepatocytes with unlabeled cholic acid (100 microM), the major serum bile acid in cyclosporin A-treated rats, showed a further inhibitory effect on [14C]cholic acid and [14C]deoxycholic acid accumulation. The initial rate of uptake of [14C]glycocholate was also inhibited. However, accumulation of glycocholic acid did not show significant changes at the longer incubation times (2-30 min). In addition, coincubation of rat hepatocytes with unlabeled cholic acid (100 microM) plus cyclosporin A did not induce any inhibition of glycocholate accumulation. Together, these differences provide an explanation for the unchanged serum levels of glycocholate. In conclusion, the changes in individual serum bile acids in cyclosporin A

  8. Growth of thin, c-axis oriented Sr-doped LaP3O9 electrolyte membranes in condensed phosphoric acid solutions

    NASA Astrophysics Data System (ADS)

    Hatada, Naoyuki; Takahashi, Kota; Adachi, Yoshinobu; Uda, Tetsuya

    2016-08-01

    Proton-conducting Sr-doped LaP3O9 has potential application as electrolytes in intermediate temperature fuel cells, but reduction of the electrical resistance of the electrolyte membranes is necessary for practical applications. In this study, we focused on reducing the resistance by reducing the electrolyte thickness, while maintaining a preferable microstructure for proton conduction (c-axis orientation and absence of the small-crystal layer). Thin, c-axis oriented Sr-doped LaP3O9 membranes were successfully obtained in condensed phosphoric acid solutions by a novel "two-step precipitation method". In this method, Sr-doped LaP3O9 powder was artificially deposited on the surface of the carbon paper supports as seeds, and then columnar crystals were grown "downward" in the solutions. We expect that this method will be utilized to produce LaP3O9 electrolyte membranes with lower electrical resistance.

  9. Dye-doped spheres with plasmonic semi-shells: Lasing modes and scattering at realistic gain levels

    PubMed Central

    Ding, Boyang; Hrelescu, Calin; Klar, Thomas A

    2013-01-01

    Summary We numerically simulate the compensation of absorption, the near-field enhancement as well as the differential far-field scattering cross section for dye-doped polystyrene spheres (radius 195 nm), which are half-covered by a silver layer of 10–40 nm thickness. Such silver capped spheres are interesting candidates for nanoplasmonic lasers, so-called spasers. We find that spasing requires gain levels less than 3.7 times higher than those in commercially available dye-doped spheres. However, commercially available concentrations are already apt to achieve negative absorption, and to narrow and enhance scattering by higher order modes. Narrowing of the plasmonic modes by gain also makes visible higher order modes, which are normally obscured by the broad spectral features of the lower order modes. We further show that the angular distribution of the far-field scattering of the spasing modes is by no means dipole-like and is very sensitive to the geometry of the structure. PMID:24455456

  10. Determination of trans fatty acid levels by FTIR in processed foods in Australia.

    PubMed

    McCarthy, Justine; Barr, Daniel; Sinclair, Andrew

    2008-01-01

    Health authorities around the world advise 'limiting consumption of trans fatty acid', however in Australia the trans fatty acid (TFA) content is not required to be listed in the nutrition information panel unless a declaration or nutrient claim is made about fatty acids or cholesterol. Since there is limited knowledge about trans fatty acid levels in processed foods available in Australia, this study aimed to determine the levels of TFA in selected food items known to be sources of TFA from previously published studies. Food items (n=92) that contain vegetable oil and a total fat content greater than 5% were included. This criterion was used in conjunction with a review of similar studies where food items were found to contain high levels of trans fatty acids. Lipids were extracted using solvents. Gravimetric methods were used to determine total fat content and trans fatty acid levels were quantified by Attenuated Total Reflectance Fourier Transform Infrared spectroscopy. High levels of trans fatty acids were found in certain items in the Australian food supply, with a high degree of variability. Of the samples analysed, 13 contained greater than 1 g of trans fatty acids per serving size, the highest value was 8.1 g/serving. Apart from when the nutrition information panel states that the content is less than a designated low level, food labels sold in Australia do not indicate trans fatty acid levels. We suggested that health authorities seek ways to assist consumers to limit their intakes of trans fatty acids. PMID:18818158

  11. Samarium and Nitrogen Co-Doped Bi2 WO6 Photocatalysts: Synergistic Effect of Sm(3+) /Sm(2+) Redox Centers and N-Doped Level for Enhancing Visible-Light Photocatalytic Activity.

    PubMed

    Wang, Fangzhi; Li, Wenjun; Gu, Shaonan; Li, Hongda; Wu, Xue; Liu, Xintong

    2016-08-26

    Samarium and nitrogen co-doped Bi2 WO6 nanosheets were successfully synthesized by using a hydrothermal method. The crystal structures, morphology, elemental compositions, and optical properties of the prepared samples were investigated. The incorporation of samarium and nitrogen ions into Bi2 WO6 was proved by X-ray diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. UV/Vis diffuse reflectance spectroscopy indicated that the samarium and nitrogen co-doped Bi2 WO6 possessed strong visible-light absorption. Remarkably, the samarium and nitrogen co-doped Bi2 WO6 exhibited higher photocatalytic activity than single-doped and pure Bi2 WO6 under visible-light irradiation. Radical trapping experiments indicated that holes (h(+) ) and superoxide radicals ((.) O2 (-) ) were the main active species. The results of photoluminescence spectroscopy and photocurrent measurements demonstrated that the recombination rate of the photogenerated electrons and holes pairs was greatly depressed. The enhanced activity was attributed to the synergistic effect of the in-built Sm(3+) /Sm(2+) redox pair centers and the N-doped level. The mechanism of the excellent photocatalytic activity of Sm-N-Bi2 WO6 is also discussed. PMID:27464522

  12. Modulation of sialic acid levels among some organs during insulin resistance or hyperglycemic states.

    PubMed

    Ibrahim, Mohammed Auwal; Abdulkadir, Aisha; Onojah, Alice; Sani, Lawal; Adamu, Auwal; Abdullahi, Hadiza

    2016-01-01

    Previous studies have suggested a possible connection between insulin resistance and chronic hyperglycemia with membrane sialic acid content. In this study, the effects of high (20% ad libitum) fructose and glucose feeding on the sialic acid levels of some organs were investigated in rats. The blood glucose levels of the high fructose- and glucose-fed rats were consistently and significantly (P < 0.05) higher than the normal control throughout the experiment. Free serum sialic acid and total hepatic sialic acid levels were elevated in the high fructose- and glucose-fed rats compared to normal control, but only the data for the high glucose-fed group were significantly (P < 0.05) different from the normal control. Conversely, a significant (P < 0.05) decrease in the pancreatic sialic acid level was observed in high glucose-fed group compared to normal control. Also, the high fructose-fed rats had lower, but insignificant (P > 0.05), pancreatic sialic acid level than the normal control. On the other hand, high fructose and glucose feeding did not significantly (P > 0.05) affect the sialic acid levels of the skeletal muscle and heart, though a tendency to increase the sialic acid level was evident in the heart. In the kidney, the sialic acid level was significantly (P < 0.05) increased in both high fructose- and glucose-fed groups. It was concluded that the liver and kidney tend to stimulate sialic acid synthesis, while the pancreas downregulate sialic acids synthesis and/or promote sialic acid release from glycoconjugates. Also, these organs may contribute to high-serum sialic acid level observed during diabetes. PMID:26468092

  13. The Synthesis and Characterization of Substituted Polyaniline Hollow Spheres doped with a Polymeric Acid

    NASA Astrophysics Data System (ADS)

    Sui, Jing; Zhang, Lijuan; Travas-Sejdic, Jadranka; Kilmartin, Paul A.

    2009-07-01

    Self-assembled poly(o-toluidine) (POT) and poly(o-anisidine) (POA) hollow spheres were prepared by oxidative polymerization using ammonium persulfate as the oxidant in the presence of 5% by weight of a polymeric acid, poly(methyl vinyl ether-alt-maleic acid) (PMVEA). The substituent at the ortho position had a significant effect on the size of the hollow nanospheres as determined by SEM and TEM. The nanospheres were of a very uniform size in the presence of the polymeric acid, with average diameters of 338±25 nm for POT and 210±20 nm for POA. The POT and POA hollow spheres were also characterized by FTIR and UV-Vis spectroscopy, which confirmed the chemical identity of the substituted polyanilines.

  14. The Anti-Doping Movement.

    PubMed

    Willick, Stuart E; Miller, Geoffrey D; Eichner, Daniel

    2016-03-01

    Historical reports of doping in sports date as far back as the ancient Greek Olympic Games. The anti-doping community considers doping in sports to be cheating and a violation of the spirit of sport. During the past century, there has been an increasing awareness of the extent of doping in sports and the health risks of doping. In response, the anti-doping movement has endeavored to educate athletes and others about the health risks of doping and promote a level playing field. Doping control is now undertaken in most countries around the world and at most elite sports competitions. As athletes have found new ways to dope, however, the anti-doping community has endeavored to strengthen its educational and deterrence efforts. It is incumbent upon sports medicine professionals to understand the health risks of doping and all doping control processes. PMID:26972261

  15. High fluorescence S, N co-doped carbon dots as an ultra-sensitive fluorescent probe for the determination of uric acid.

    PubMed

    Wang, Haiyan; Lu, Qiujun; Hou, Yuxin; Liu, Yalan; Zhang, Youyu

    2016-08-01

    Sulfur, nitrogen co-doped carbon dots (S, N co-doped C-dots) as highly selective fluorescent probe for uric acid (UA) detection were designed. The S, N co-doped C-dots with high quantum yield of 73.1% were prepared by hydrothermal method. It was found that the fluorescence of S, N co-doped C-dots was quenched apparently by hydroxyl radicals from Fenton reaction between H2O2 and Fe(2+). The production of H2O2 originated from the oxidization of UA by uricase. Therefore, an optical biosensor was developed for the detection of UA based on Fenton reaction and enzymatic reaction. Under the optimized conditions, two linear relationships between the ratio of fluorescence quenching of the C-dots and UA concentration were found in the range of 0.08-10µM and 10-50µM, respectively. The detection limit was down to 0.07µM. Moreover, the proposed biosensor was successfully applied to the detection of uric acid in human serum samples. PMID:27216657

  16. Watt-level passively Q-switched heavily Er3+-doped ZBLAN fiber laser with a semiconductor saturable absorber mirror

    PubMed Central

    Shen, Yanlong; Wang, Yishan; Luan, Kunpeng; Huang, Ke; Tao, Mengmeng; Chen, Hongwei; Yi, Aiping; Feng, Guobin; Si, Jinhai

    2016-01-01

    A diode-cladding pumped mid-infrared passively Q-switched Er3+-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 μm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail. PMID:27225029

  17. Watt-level passively Q-switched heavily Er3+-doped ZBLAN fiber laser with a semiconductor saturable absorber mirror

    NASA Astrophysics Data System (ADS)

    Shen, Yanlong; Wang, Yishan; Luan, Kunpeng; Huang, Ke; Tao, Mengmeng; Chen, Hongwei; Yi, Aiping; Feng, Guobin; Si, Jinhai

    2016-05-01

    A diode-cladding pumped mid-infrared passively Q-switched Er3+-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 μm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail.

  18. Atomic-level structural and chemical analysis of Cr-doped Bi2Se3 thin films

    PubMed Central

    Ghasemi, A.; Kepaptsoglou, D.; Collins-McIntyre, L. J.; Ramasse, Q.; Hesjedal, T.; Lazarov, V. K.

    2016-01-01

    We present a study of the structure and chemical composition of the Cr-doped 3D topological insulator Bi2Se3. Single-crystalline thin films were grown by molecular beam epitaxy on Al2O3 (0001), and their structural and chemical properties determined on an atomic level by aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy. A regular quintuple layer stacking of the Bi2Se3 film is found, with the exception of the first several atomic layers in the initial growth. The spectroscopy data gives direct evidence that Cr is preferentially substituting for Bi in the Bi2Se3 host. We also show that Cr has a tendency to segregate at internal grain boundaries of the Bi2Se3 film. PMID:27221782

  19. Watt-level passively Q-switched heavily Er(3+)-doped ZBLAN fiber laser with a semiconductor saturable absorber mirror.

    PubMed

    Shen, Yanlong; Wang, Yishan; Luan, Kunpeng; Huang, Ke; Tao, Mengmeng; Chen, Hongwei; Yi, Aiping; Feng, Guobin; Si, Jinhai

    2016-01-01

    A diode-cladding pumped mid-infrared passively Q-switched Er(3+)-doped ZBLAN fiber laser with an average output power of watt-level based on a semiconductor saturable absorber mirror (SESAM) is demonstrated. Stable pulse train was produced at a slope efficiency of 17.8% with respect to launched pump power. The maximum average power of 1.01 W at a repetition rate of 146.3 kHz was achieved with a corresponding pulse energy of 6.9 μJ, from which the maximum peak power was calculated to be 21.9 W. To the best of our knowledge, the average power and the peak power are the highest in 3 μm region passively Q-switched fiber lasers. The influence of gain fiber length on the operation regime of the fiber laser has been investigated in detail. PMID:27225029

  20. Three-dimensional modeling of CPA to the multimillijoule level in tapered Yb-doped fibers for coherent combining systems.

    PubMed

    Andrianov, Alexey; Anashkina, Elena; Kim, Arkady; Meyerov, Iosif; Lebedev, Sergey; Sergeev, Alexander; Mourou, Gerard

    2014-11-17

    We developed a three-dimensional numerical model of Large-Mode-Area chirped pulse fiber amplifiers which includes nonlinear beam propagation in nonuniform multimode waveguides as well as gain spectrum dynamics in quasi-three-level active ions. We used our model in tapered Yb-doped fiber amplifiers and showed that single-mode propagation is maintained along the taper even in the presence of strong Kerr nonlinearity and saturated gain, allowing extraction of up to 3 mJ of output energy in 1 ns pulse. Energy scaling and its limitation as well as the influence of fiber taper bending and core irregularities on the amplifier performance were studied. We also investigated numerically the capabilities for compression and coherent combining of up to 36 perturbed amplifying channels and showed more than 70% combining efficiency, even with up to 11% of high-order modes in individual channels. PMID:25402067

  1. Atomic-level structural and chemical analysis of Cr-doped Bi2Se3 thin films.

    PubMed

    Ghasemi, A; Kepaptsoglou, D; Collins-McIntyre, L J; Ramasse, Q; Hesjedal, T; Lazarov, V K

    2016-01-01

    We present a study of the structure and chemical composition of the Cr-doped 3D topological insulator Bi2Se3. Single-crystalline thin films were grown by molecular beam epitaxy on Al2O3 (0001), and their structural and chemical properties determined on an atomic level by aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy. A regular quintuple layer stacking of the Bi2Se3 film is found, with the exception of the first several atomic layers in the initial growth. The spectroscopy data gives direct evidence that Cr is preferentially substituting for Bi in the Bi2Se3 host. We also show that Cr has a tendency to segregate at internal grain boundaries of the Bi2Se3 film. PMID:27221782

  2. Atomic-level structural and chemical analysis of Cr-doped Bi2Se3 thin films

    NASA Astrophysics Data System (ADS)

    Ghasemi, A.; Kepaptsoglou, D.; Collins-McIntyre, L. J.; Ramasse, Q.; Hesjedal, T.; Lazarov, V. K.

    2016-05-01

    We present a study of the structure and chemical composition of the Cr-doped 3D topological insulator Bi2Se3. Single-crystalline thin films were grown by molecular beam epitaxy on Al2O3 (0001), and their structural and chemical properties determined on an atomic level by aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy. A regular quintuple layer stacking of the Bi2Se3 film is found, with the exception of the first several atomic layers in the initial growth. The spectroscopy data gives direct evidence that Cr is preferentially substituting for Bi in the Bi2Se3 host. We also show that Cr has a tendency to segregate at internal grain boundaries of the Bi2Se3 film.

  3. Photoluminescence Analysis of Energy Level on Li-Doped ZnO Nanowires Grown by a Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Hyo Lee, Sang; Lee, Jun Seok; Ko, Won Bae; Inn Sohn, Jung; Cha, Seung Nam; Kim, Jong Min; Park, Young Jun; Hong, Jin Pyo

    2012-09-01

    The optical and structural properties of Li-doped ZnO nanowires grown by a hydrothermal method are reported herein. The low-temperature and temperature-dependent photoluminescence spectra clearly exhibited emission peaks that confirmed the presence of a lithium impurity as an acceptor dopant. Particularly, the acceptor energy level of the Li dopant was estimated to be 121 meV from the PL spectra. This value was also indicated from an Arrhenius plot of the integrated PL intensity of the A°X emission as a function of temperature. These results are in agreement with theoretical and experimental results of previously considered p-type dopants reported in other studies.

  4. Photoluminescence Analysis of Energy Level on Li-Doped ZnO Nanowires Grown by a Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Lee, Sang Hyo; Lee, Jun Seok; Ko, Won Bae; Sohn, Jung Inn; Cha, Seung Nam; Kim, Jong Min; Park, Young Jun; Hong, Jin Pyo

    2012-09-01

    The optical and structural properties of Li-doped ZnO nanowires grown by a hydrothermal method are reported herein. The low-temperature and temperature-dependent photoluminescence spectra clearly exhibited emission peaks that confirmed the presence of a lithium impurity as an acceptor dopant. Particularly, the acceptor energy level of the Li dopant was estimated to be 121 meV from the PL spectra. This value was also indicated from an Arrhenius plot of the integrated PL intensity of the A\\circX emission as a function of temperature. These results are in agreement with theoretical and experimental results of previously considered p-type dopants reported in other studies.

  5. Interaction between excitons and 2DEG Landau levels in modulation doped GaAs/AlGaAs heterojunctions

    NASA Astrophysics Data System (ADS)

    Preezant, Yulia; Gabbay, A.; Eitan, A. A.; Ashkinadze, B. M.; Cohen, E.; Pfeiffer, L. N.

    2007-04-01

    The reflection and photoluminescence spectra of n-type, modulation-doped GaAs/AlxGa1-xAs wide quantum wells (QW) and heterojunctions (HJ) were studied at T = 2K and under a perpendicularly applied magnetic field. The spectra show two groups of very sharp lines that originate in two types of excitations: excitons, whose center of mass motion is quantized, and interband Landau transitions of the 2DEG, that is confined to the QW edges. Abrupt energy and intensity variations of both types of lines are observed at filling factors ν = 1,2 of the 2DEG. These variations are interpreted in terms of an interaction between excitations that are spatially confined in separate parts of the wide QW (or HJ). It leads to energy level splittings and increased exciton dissociation by the magnetized 2DEG layer.

  6. Boron deactivation in heavily boron-doped Czochralski silicon during rapid thermal anneal: Atomic level understanding

    SciTech Connect

    Gao, Chao; Dong, Peng; Yi, Jun; Ma, Xiangyang E-mail: mxyoung@zju.edu.cn; Yang, Deren; Lu, Yunhao E-mail: mxyoung@zju.edu.cn

    2014-01-20

    The changes in hole concentration of heavily boron (B)-doped Czochralski silicon subjected to high temperature rapid thermal anneal (RTA) and following conventional furnace anneal (CFA) have been investigated. It is found that decrease in hole concentration, namely, B deactivation, is observed starting from 1050 °C and increases with RTA temperature. The following CFA at 300–500 °C leads to further B deactivation, while that at 600–800 °C results in B reactivation. It is supposed that the interaction between B atoms and silicon interstitials (I) thus forming BI pairs leads to the B deactivation during the high temperature RTA, and, moreover, the formation of extended B{sub 2}I complexes results in further B deactivation in the following CFA at 300–500 °C. On the contrary, the dissociation of BI pairs during the following CFA at 600–800 °C enables the B reactivation. Importantly, the first-principles calculation results can soundly account for the above-mentioned supposition.

  7. New alleles of FATB-1A to reduce palmitic acid levels in soybean

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In wild-type soybeans, palmitic acid typically constitutes 10% of the total seed oil. Palmitic acid is a saturated fat linked to increased cholesterol levels, and reducing levels of saturated fats in soybean oil has been a breeding target. To identify novel and useful variation that could help in re...

  8. Plasma Amino Acid Levels in Children with Autism and Their Families.

    ERIC Educational Resources Information Center

    Aldred, Sarah; Moore, Kieran M.; Fitzgerald, Michael; Waring, Rosemary H.

    2003-01-01

    Plasma amino acid levels were measured in autistic (n=12), Asperger syndrome (n=11) patients, their parents and siblings. Patients with autism or Asperger syndrome and their siblings and parents all had raised glutamic acid, phenyalanine, asparagine, tyrosine, alanine, and lysine levels than age-matched controls. Results suggest dysregulated amino…

  9. Application of visible-light photocatalysis with nitrogen-doped or unmodified titanium dioxide for control of indoor-level volatile organic compounds.

    PubMed

    Jo, Wan-Kuen; Kim, Jong-Tae

    2009-05-15

    The present study evaluated visible-light photocatalysis, applying an annular reactor coated with unmodified or nitrogen (N)-doped titanium dioxide (TiO(2)), to cleanse gaseous volatile organic compounds (VOCs) at indoor levels. The surface chemistry investigation of N-doped TiO(2) suggested that there was no significant residual of sulfate ions or urea species on the surface of the N-doped TiO(2). Under visible-light irradiation, the photocatalytic technique using N-doped TiO(2) was much superior to that for unmodified TiO(2) for the degradation of VOCs. Moreover, the degradation efficiency by a reactor coated with N-doped TiO(2) was well above 90% for four target compounds (ethyl benzene, o,m,p-xylenes), suggesting that this photocatalytic system can be effectively employed to cleanse these pollutants at indoor air quality (IAQ) levels. The degradation efficiency of all target compounds increased as the stream flow rate (SFR) decreased. For most target compounds, a reactor with a lower hydraulic diameter (HD) exhibited elevated degradation efficiency. The result on humidity effect suggested that the N-doped photocatalyst could be employed effectively to remove four target compounds (ethyl benzene, o,m,p-xylenes) under conditions of less humidified environments, including a typical indoor comfort range (50-60%). Consequently, it is suggested that with appropriate photocatalytic conditions, a visible-light-assisted N-doped photocatalytic system is clearly an important tool for improving IAQ. PMID:18809252

  10. A Doped Polyaniline Modified Electrode Amperometric Biosensor for Gluconic Acid Determination in Grapes

    PubMed Central

    Albanese, Donatella; Malvano, Francesca; Sannini, Adriana; Pilloton, Roberto; Di Matteo, Marisa

    2014-01-01

    In winemaking gluconic acid is an important marker for quantitative evaluation of grape infection by Botrytis cinerea. A screen-printed amperometric bienzymatic sensor for the determination of gluconic acid based on gluconate kinase (GK) and 6-phospho-D-gluconate dehydrogenase (6PGDH) coimmobilized onto polyaniline/poly (2-acrylamido-2-methyl-1-propanesulfonic acid; PANI-PAAMPSA) is reported in this study. The conductive polymer electrodeposed on the working electrode surface allowed the detection of NADH at low potential (0.1 V) with a linear range from 4 × 10−3 to 1 mM (R2 = 0.99) and a sensitivity of 419.44 nA·mM−1. The bienzymatic sensor has been optimized with regard to GK/6PGDH enzymatic unit ratio and ATP/NADP+ molar ratio which resulted equal to 0.33 and 1.2, respectively. Under these conditions a sensitivity of 255.2 nA·mM−1, a limit of detection of 5 μM and a Relative Standard Deviation (RSD) of 4.2% (n = 5) have been observed. Finally, the biosensor has been applied for gluconic acid measurements in must grape samples and the matrix effect has been taken into consideration. The results have been compared with those obtained on the same samples with a commercial kit based on a spectrophotometric enzyme assay and were in good agreement, showing the capability of the bienzymatic PANI-PAAMPSA biosensor for gluconic acid measurements and thus for the evaluation of Botrytis cinerea infection in grapes. PMID:24960084

  11. Effect of erbium-doped: yttrium, aluminium and garnet laser irradiation on the surface microstructure and roughness of sand-blasted, large grit, acid-etched implants

    PubMed Central

    Lee, Ji-Hun; Kwon, Young-Hyuk; Herr, Yeek; Shin, Seung-Il

    2011-01-01

    Purpose The present study was performed to evaluate the effect of erbium-doped: yttrium, aluminium and garnet (Er:YAG) laser irradiation on sand-blasted, large grit, acid-etched (SLA) implant surface microstructure according to varying energy levels and application times of the laser. Methods The implant surface was irradiated by the Er:YAG laser under combined conditions of 100, 140, or 180 mJ/pulse and an application time of 1 minute, 1.5 minutes, or 2 minutes. Scanning electron microscopy (SEM) was used to examine the surface roughness of the specimens. Results All experimental conditions of Er:YAG laser irradiation, except the power setting of 100 mJ/pulse for 1 minute and 1.5 minutes, led to an alteration in the implant surface. SEM evaluation showed a decrease in the surface roughness of the implants. However, the difference was not statistically significant. Alterations of implant surfaces included meltdown and flattening. More extensive alterations were present with increasing laser energy and application time. Conclusions To ensure no damage to their surfaces, it is recommended that SLA implants be irradiated with an Er:YAG laser below 100 mJ/pulse and 1.5 minutes for detoxifying the implant surfaces. PMID:21811689

  12. The Association between Marine n-3 Polyunsaturated Fatty Acid Levels and Survival after Renal Transplantation

    PubMed Central

    Jenssen, Trond; Hartmann, Anders; Diep, Lien M.; Dahle, Dag O.; Reisæter, Anna V.; Bjerve, Kristian S.; Christensen, Jeppe H.; Schmidt, Erik B.; Svensson, My

    2015-01-01

    Background and objectives Several studies have reported beneficial cardiovascular effects of marine n-3 polyunsaturated fatty acids. To date, no large studies have investigated the potential benefits of marine n-3 polyunsaturated fatty acids in recipients of renal transplants. Design, setting, participants, & measurements In this observational cohort study of 1990 Norwegian recipients of renal transplants transplanted between 1999 and 2011, associations between marine n-3 polyunsaturated fatty acid levels and mortality were investigated by stratified analysis and multivariable Cox proportional hazard regression analysis adjusting for traditional and transplant-specific mortality risk factors. Marine n-3 polyunsaturated fatty acid levels in plasma phospholipids were measured by gas chromatography in a stable phase 10 weeks after transplantation. Results There were 406 deaths (20.4%) during a median follow-up period of 6.8 years. Mortality rates were lower in patients with high marine n-3 polyunsaturated fatty acid levels (≥7.95 weight percentage) compared with low levels (<7.95 weight percentage) for all age categories (pooled mortality rate ratio estimate, 0.69; 95% confidence interval, 0.57 to 0.85). When divided into quartiles according to marine n-3 polyunsaturated fatty acid levels, patients in the upper quartile compared with the lower quartile had a 56% lower risk of death (adjusted hazard ratio, 0.44; 95% confidence interval, 0.26 to 0.75) using multivariable Cox proportional hazard regression analysis. There was a lower hazard ratio for death from cardiovascular disease with high levels of marine n-3 polyunsaturated fatty acid and a lower hazard ratio for death from infectious disease with high levels of the marine n-3 polyunsaturated fatty acid eicosapentaenoic acid, whereas there was no association between total or individual marine n-3 polyunsaturated fatty acid levels and cancer mortality. Conclusions Higher plasma phospholipid marine n-3

  13. Observation of an electron band above the Fermi level in FeTe{sub 0.55}Se{sub 0.45} from in-situ surface doping

    SciTech Connect

    Zhang, P.; Ma, J.; Qian, T.; Richard, P. Ding, H.; Xu, N.; Xu, Y.-M.; Fedorov, A. V.; Denlinger, J. D.; Gu, G. D.

    2014-10-27

    We used in-situ potassium (K) evaporation to dope the surface of the iron-based superconductor FeTe{sub 0.55}Se{sub 0.45}. The systematic study of the bands near the Fermi level confirms that electrons are doped into the system, allowing us to tune the Fermi level of this material and to access otherwise unoccupied electronic states. In particular, we observe an electron band located above the Fermi level before doping that shares similarities with a small three-dimensional pocket observed in the cousin, heavily electron-doped KFe{sub 2−x}Se{sub 2} compound.

  14. Dependence of the electrical parameters of MBE-grown Cd{sub x}Hg{sub 1} {sub -} {sub x}Te films on the level of doping with indium

    SciTech Connect

    Varavin, V. S. Dvoretskii, S. A.; Ikusov, D. G.; Mikhailov, N. N.; Sidorov, Yu. G.; Sidorov, G. Yu.; Yakushev, M. V.

    2008-06-15

    Dependences of the minority-carrier lifetime and electron mobility in Cd{sub x}Hg{sub 1-x}Te films on their indium-doping level are studied. Films with x {approx} 0.22 grown by molecular-beam epitaxy on GaAs substrates were in situ doped with indium across their entire thickness. The temperature dependences of the lifetime were studied in the temperature range 77-300 K. The decrease in the lifetime, observed as the doping level increases, is governed by the mechanism of Auger recombination. As the doping level becomes higher, the mobility decreases in qualitative agreement with theoretical calculations.

  15. Methylenetetrahydrofolate reductase deficiency alters levels of glutamate and γ-aminobutyric acid in brain tissue

    PubMed Central

    Jadavji, N.M.; Wieske, F.; Dirnagl, U.; Winter, C.

    2015-01-01

    Methylenetetrahydrofolate reductase (MTHFR) is an enzyme key regulator in folate metabolism. Deficiencies in MTHFR result in increased levels of homocysteine, which leads to reduced levels of S-adenosylmethionine (SAM). In the brain, SAM donates methyl groups to catechol-O-methyltransferase (COMT), which is involved in neurotransmitter analysis. Using the MTHFR-deficient mouse model the purpose of this study was to investigate levels of monoamine neurotransmitters and amino acid levels in brain tissue. MTHFR deficiency affected levels of both glutamate and γ-aminobutyric acid in within the cerebellum and hippocampus. Mthfr−/− mice had reduced levels of glutamate in the amygdala and γ-aminobutyric acid in the thalamus. The excitatory mechanisms of homocysteine through activation of the N-methyl-d-aspartate receptor in brain tissue might alter levels of glutamate and γ-aminobutyric acid. PMID:26937386

  16. Resonant Levels, Vacancies, and Doping in Bi2Te3, Bi2Te2Se, and Bi2Se3 Tetradymites

    NASA Astrophysics Data System (ADS)

    Wiendlocha, Bartlomiej

    2016-07-01

    The electronic structure of the tetradymites, Bi_2Te_3, Bi_2Te_2Se, and Bi_2Se_3, containing various dopants and vacancies, has been studied using first-principles calculations. We focus on the possibility of formation of resonant levels (RL), confirming the formation of RL by Sn in Bi_2Te_3 and predicting similar behavior of Sn in Bi_2Te_2Se and Bi_2Se_3. Vacancies, which are likely present on chalcogen atom sites in real samples of Bi_2Te_2Se and Bi_2Se_3, are also studied and their charged donor and resonant behavior discussed. Doping of vacancy-containing materials with regular acceptors, such as Ca or Mg, is shown to compensate the donor effect of vacancies, and n-p crossover, while increasing the dopant concentration, is observed. We verify that the RL on Sn is not disturbed by chalcogen vacancies in Bi_2Te_2Se or Bi_2Se_3, and for the Sn-doped materials with Se or Te vacancies, double doping, instead of heavy doping with Sn, is suggested as an effective way of obtaining the resonant level. This should help to avoid smearing of the RL, a possible reason for earlier unsuccessful experimental observation of the influence of the RL on the thermoelectric properties of Sn-doped Bi_2Te_2Se. Finally, we show that Al and Ga are possible new resonant impurities in tetradymites, hoping that this will stimulate further experimental studies.

  17. Resonant Levels, Vacancies, and Doping in Bi2Te3, Bi2Te2Se, and Bi2Se3 Tetradymites

    NASA Astrophysics Data System (ADS)

    Wiendlocha, Bartlomiej

    2016-04-01

    The electronic structure of the tetradymites, Bi_2 Te_3 , Bi_2 Te_2 Se, and Bi_2 Se_3 , containing various dopants and vacancies, has been studied using first-principles calculations. We focus on the possibility of formation of resonant levels (RL), confirming the formation of RL by Sn in Bi_2 Te_3 and predicting similar behavior of Sn in Bi_2 Te_2 Se and Bi_2 Se_3 . Vacancies, which are likely present on chalcogen atom sites in real samples of Bi_2 Te_2 Se and Bi_2 Se_3 , are also studied and their charged donor and resonant behavior discussed. Doping of vacancy-containing materials with regular acceptors, such as Ca or Mg, is shown to compensate the donor effect of vacancies, and n-p crossover, while increasing the dopant concentration, is observed. We verify that the RL on Sn is not disturbed by chalcogen vacancies in Bi_2 Te_2 Se or Bi_2 Se_3 , and for the Sn-doped materials with Se or Te vacancies, double doping, instead of heavy doping with Sn, is suggested as an effective way of obtaining the resonant level. This should help to avoid smearing of the RL, a possible reason for earlier unsuccessful experimental observation of the influence of the RL on the thermoelectric properties of Sn-doped Bi_2 Te_2 Se. Finally, we show that Al and Ga are possible new resonant impurities in tetradymites, hoping that this will stimulate further experimental studies.

  18. What is the intrapatient variability of mycophenolic acid trough levels?

    PubMed

    Todorova, Ekaterina K; Huang, Shih-Han S; Kobrzynski, Marta C; Filler, Guido

    2015-11-01

    TDM of MPA, the active compound of MMF, is rarely used despite its substantial intra- and interpatient variability. Little is known about the utility of long-term MPA TDM. Data are expressed as mean (one standard deviation). All available data from 27 renal transplant recipients (mean age at transplantation: 7.7 [5.0] yr) with an average follow-up of 9.3 (4.6) yr were analyzed. MPA levels were measured using the EMIT. GFR was measured using cystatin C and eGFR was calculated using the Filler formula. Intrapatient CV of the trough level was calculated as the ratio of the mean divided by one standard deviation. Mean cystatin C eGFR was 56.9 (24.4) mL/min/1.73 m(2) . There was a weak but significant correlation between the MPA trough level and the AUC (Spearman r = 0.6592, p < 0.0001). A total of 1964 MPA trough levels (73 [45]/patient) were measured, as compared to 3462 Tac trough levels (144 [71]/patient). The average MPA trough level was 3.01 (1.26) mg/L and the average trough Tac level was 7.3 (1.8) ng/mL. Intrapatient CV was statistically higher (p = 0.00093) for MPA at 0.68 (0.29) when compared to Tac with a CV of 0.46 (0.12). CV did not correlate with eGFR. Intrapatient MPA trough level CV is significantly higher than for Tac, while CV for both MPA and Tac was high. MPA trough level monitoring may be a feasible monitoring option to improve patient exposure and possibly outcomes. PMID:26201386

  19. Fe-N-Doped Carbon Capsules with Outstanding Electrochemical Performance and Stability for the Oxygen Reduction Reaction in Both Acid and Alkaline Conditions.

    PubMed

    Ferrero, Guillermo A; Preuss, Kathrin; Marinovic, Adam; Jorge, Ana Belen; Mansor, Noramalina; Brett, Dan J L; Fuertes, Antonio B; Sevilla, Marta; Titirici, Maria-Magdalena

    2016-06-28

    High surface area N-doped mesoporous carbon capsules with iron traces exhibit outstanding electrocatalytic activity for the oxygen reduction reaction in both alkaline and acidic media. In alkaline conditions, they exhibit more positive onset (0.94 V vs RHE) and half-wave potentials (0.83 V vs RHE) than commercial Pt/C, while in acidic media the onset potential is comparable to that of commercial Pt/C with a peroxide yield lower than 10%. The Fe-N-doped carbon catalyst combines high catalytic activity with remarkable performance stability (3500 cycles between 0.6 and 1.0 V vs RHE), which stems from the fact that iron is coordinated to nitrogen. Additionally, the newly developed electrocatalyst is unaffected by the methanol crossover effect in both acid and basic media, contrary to commercial Pt/C. The excellent catalytic behavior of the Fe-N-doped carbon, even in the more relevant acid medium, is attributable to the combination of chemical functions (N-pyridinic, N-quaternary, and Fe-N coordination sites) and structural properties (large surface area, open mesoporous structure, and short diffusion paths), which guarantees a large number of highly active and fully accessible catalytic sites and rapid mass-transfer kinetics. Thus, this catalyst represents an important step forward toward replacing Pt catalysts with cheaper alternatives. In this regard, an alkaline anion exchange membrane fuel cell was assembled with Fe-N-doped mesoporous carbon capsules as the cathode catalyst to provide current and power densities matching those of a commercial Pt/C, which indicates the practical applicability of the Fe-N-carbon catalyst. PMID:27214056

  20. Hydroxamic acid derivatives of mycophenolic acid inhibit histone deacetylase at the cellular level.

    PubMed

    Batovska, Daniela I; Kim, Dong Hoon; Mitsuhashi, Shinya; Cho, Yoon Sun; Kwon, Ho Jeong; Ubukata, Makoto

    2008-10-01

    Mycophenolic acid (MPA, 1), an inhibitor of IMP-dehydrogenase (IMPDH) and a latent PPARgamma agonist, is used as an effective immunosuppressant for clinical transplantation and recently entered clinical trials in advanced multiple myeloma patients. On the other hand, suberoylanilide hydroxamic acid (SAHA), a non-specific histone deacetylase (HDAC) inhibitor, has been approved for treating cutaneous T-cell lymphoma. MPA seemed to bear a cap, a linker, and a weak metal-binding site as a latent inhibitor of HDAC. Therefore, the hydroxamic acid derivatives of mycophenolic acid having an effective metal-binding site, mycophenolic hydroxamic acid (MPHA, 2), 7-O-acetyl mycophenolic acid (7-O-Ac MPHA, 3), and 7-O-lauroyl mycophenolic hydroxamic acid (7-O-L MPHA, 4) were designed and synthesized. All these compounds inhibited histone deacetylase with IC50 values of 1, 0.9 and 0.5 microM, and cell proliferation at concentrations of 2, 1.5 and 1 microM, respectively. PMID:18838793

  1. Increased Serum Level of Cyclopropaneoctanoic Acid 2-Hexyl in Patients with Hypertriglyceridemia-Related Disorders.

    PubMed

    Mika, Adriana; Stepnowski, Piotr; Chmielewski, Michal; Malgorzewicz, Sylwia; Kaska, Lukasz; Proczko, Monika; Ratnicki-Sklucki, Krzysztof; Sledzinski, Maciej; Sledzinski, Tomasz

    2016-07-01

    We recently reported the presence of various cyclopropane fatty acids-among them, cyclopropaneoctanoic acid 2-hexyl-in the adipose tissue of obese women. The aim of this study was to verify whether the presence of cyclopropaneoctanoic acid 2-hexyl in human serum was associated with obesity or chronic kidney disease (both being related to dyslipidemia), and to find potential associations between the serum level of this compound and specific markers of the these conditions. The serum concentration of cyclopropaneoctanoic acid 2-hexyl was determined by gas chromatography-mass spectrometry (GC-MS) in non-obese controls, obese patients, obese patients after a 3-month low-calorie diet, and individuals with chronic kidney disease. Obese patients and those with chronic kidney disease presented with higher serum levels of cyclopropaneoctanoic acid 2-hexyl than controls. Switching obese individuals to a low-calorie (low-lipid) diet resulted in a reduction in this fatty acid concentration to the level observed in controls. Cyclopropaneoctanoic acid 2-hexyl was also found in foods derived from animal fat. Serum concentrations of triacylglycerols in the analyzed groups followed a pattern similar to that for serum cyclopropaneoctanoic acid 2-hexyl, and these variables were positively correlated with each other among the studied groups. Patients with hypertriglyceridemia-related conditions presented with elevated serum levels of cyclopropaneoctanoic acid 2-hexyl. Our findings suggest that its high serum level is related to high serum triacylglycerol concentrations rather than to body mass or BMI. PMID:27003900

  2. Hippuric Acid Levels in Paint Workers at Steel Furniture Manufacturers in Thailand

    PubMed Central

    Decharat, Somsiri

    2014-01-01

    Background The aims of this study were to determine hippuric acid levels in urine samples, airborne toluene levels, acute and chronic neurological symptoms, and to describe any correlation between urinary hippuric acid and airborne toluene. Methods The hippuric acid concentration in the urine of 87 paint workers exposed to toluene at work (exposed group), and 87 nonexposed people (control group) was studied. Study participants were selected from similar factories in the same region. Urine samples were collected at the end of a shift and analyzed for hippuric acid by high performance liquid chromatography. Air samples for the estimation of toluene exposure were collected with diffusive personal samplers and the toluene quantified using gas–liquid chromatography. The two groups were also interviewed and observed about their work practices and health. Results The median of the 87 airborne toluene levels was 55 ppm (range, 12–198 ppm). The median urinary hippuric acid level was 800 mg/g creatinine (range, 90–2547 mg/g creatinine). A statistically significant positive correlation was found between airborne toluene exposure and urine hippuric acid levels (r = 0.548, p < 0.01). Workers with acute symptoms had significantly higher hippuric acid levels than those who did not (p < 0.05). It was concluded that there was a significant correlation between toluene exposure, hippuric acid levels, and health (p < 0.001). Conclusion There appears to be a significant correlation between workers exposure to toluene at work, their urine hippuric acid levels, and resulting symptoms of poor health. Improvements in working conditions and occupational health education are required at these workplaces. There was good correlation between urinary hippuric acid and airborne toluene levels. PMID:25516817

  3. Fabrication of Nitrogen-Doped Mesoporous-Carbon-Coated Palladium Nanoparticles: An Intriguing Electrocatalyst for Methanol and Formic Acid Oxidation.

    PubMed

    Ray, Chaiti; Dutta, Soumen; Sahoo, Ramkrishna; Roy, Anindita; Negishi, Yuichi; Pal, Tarasankar

    2016-05-20

    Inspired by the attractive catalytic properties of palladium and the inert nature of carbon supports in catalysis, a concise and simple methodology for in situ nitrogen-doped mesoporous-carbon-supported palladium nanoparticles (Pd/N-C) has been developed by carbonizing a palladium dimethylglyoximate complex. The as-synthesized Pd/N-C has been exfoliated as a fuel cell catalyst by studying the electro-oxidation of methanol and formic acid. The material synthesized at 400 °C,namely, Pd/N-C-400,exhibitssuperior mass activity and stability among catalysts synthesized under different carbonization temperaturesbetween300 and 500 °C. The unique 1D porous structure in Pd/N-C-400 helps better electron transport at the electrode surface, which eventually leads to about five times better catalytic activity and about two times higher stability than that of commercial Pd/C. Thus, our designed sacrificial metal-organic templatedirected pathway becomes a promising technique for Pd/N-C synthesis with superior catalytic performances. PMID:27016895

  4. Photoinduced proton transfer coupled with energy transfer: Mechanism of sensitized luminescence of terbium ion by salicylic acid doped in polymer.

    PubMed

    Misra, Vinita; Mishra, Hirdyesh

    2008-06-28

    In the present work, excited state intramolecular proton transfer (ESIPT) in salicylic acid (SA) monoanion and subsequent sensitization of Tb(3+) ion in polyvinyl alcohol (PVA) have been studied. The study has been carried out both by steady state and time domain fluorescence measurement techniques at room temperature. It is found that the SA completely ionizes and exists as monoanion in PVA. It exhibits a large Stokes shifted blue emission (10 000 cm(-1)) due to ESIPT and shows a decay time of 6.85 ns. On the other hand, Tb(3+) ion shows a very weak green emission and a decay time of approximately 641 mus in PVA film. Upon incorporating Tb(3+) ion in SA doped PVA film, both intensity and decay time of SA decrease and sensitized emission from Tb(+3) ion along with 3.8 mus rise time is observed. Energy transfer is found to take place both from excited singlet as well as triplet states. A brief description of the properties of the present system from the viewpoint of luminescent solar collector material is addressed. PMID:18601359

  5. Highly sensitive detection of influenza virus by boron-doped diamond electrode terminated with sialic acid-mimic peptide.

    PubMed

    Matsubara, Teruhiko; Ujie, Michiko; Yamamoto, Takashi; Akahori, Miku; Einaga, Yasuaki; Sato, Toshinori

    2016-08-01

    The progression of influenza varies according to age and the presence of an underlying disease; appropriate treatment is therefore required to prevent severe disease. Anti-influenza therapy, such as with neuraminidase inhibitors, is effective, but diagnosis at an early phase of infection before viral propagation is critical. Here, we show that several dozen plaque-forming units (pfu) of influenza virus (IFV) can be detected using a boron-doped diamond (BDD) electrode terminated with a sialic acid-mimic peptide. The peptide was used instead of the sialyloligosaccharide receptor, which is the common receptor of influenza A and B viruses required during the early phase of infection, to capture IFV particles. The peptide, which was previously identified by phage-display technology, was immobilized by click chemistry on the BDD electrode, which has excellent electrochemical characteristics such as low background current and weak adsorption of biomolecules. Electrochemical impedance spectroscopy revealed that H1N1 and H3N2 IFVs were detectable in the range of 20-500 pfu by using the peptide-terminated BDD electrode. Our results demonstrate that the BDD device integrated with the receptor-mimic peptide has high sensitivity for detection of a low number of virus particles in the early phase of infection. PMID:27457924

  6. Improvement in fingerprint detection using Tb(III)-dipicolinic acid complex doped nanobeads and time resolved imaging.

    PubMed

    Hauser, Frank M; Knupp, Gerd; Officer, Simon

    2015-08-01

    This paper deals with the synthesis and application of lanthanide complex doped nanobeads used as a luminescent fingerprint powder. Due to their special optical properties, namely a long emission lifetime, sharp emission profiles and large Stokes shifts, luminescent lanthanide complexes are useful for discriminating against signals from background emissions. This is a big advantage because latent fingerprints placed on multicoloured fluorescent surfaces are difficult to develop with conventional powders. The complex of 2,6-dipicolinic acid (DPA) and terbium ([Tb(DPA)3](3-)) is used for this purpose. Using the Stöber process, this complex is incorporated into a silica matrix forming nanosized beads (230-630nm). It is shown that the [Tb(DPA)3](3-) is successfully incorporated into the beads and that these beads exhibit the wanted optical properties of the complex. A phenyl functionalisation is applied to increase the lipophilicity of the beads and finally the beads are used to develop latent fingerprints. A device for time resolved imaging was built to improve the contrast between developed fingerprint and different background signals, whilst still detecting the long lasting luminescence of the complex. The developed fingerprint powder is therefore promising to develop fingerprints on multicoloured fluorescent surfaces. PMID:26046677

  7. Comparing atrazine and cyanuric acid electro-oxidation on mixed oxide and boron-doped diamond electrodes.

    PubMed

    Malpass, Geoffroy R P; Salazar-Banda, Giancarlo R; Miwa, Douglas W; Machado, Sérgio A S; Motheo, Artur J

    2013-01-01

    The breakdown of pesticides has been promoted by many methods for clean up of contaminated soil and wastewaters. The main goal is to decrease the toxicity of the parent compound to achieve non-toxic compounds or even, when complete mineralization occurs, carbon dioxide and water. Therefore, electrochemical degradation (potentiostatic and galvanostatic) of both the pesticide atrazine and cyanuric acid (CA) at boron-doped diamond (BDD) and Ti/Ru0.3Ti0.7O2 dimensionally stable anode (DSA) electrodes, in different supporting electrolytes (NaCl and Na2SO4), is presented with the aim of establishing the influence of the operational parameters on the process efficiency. The results demonstrate that both the electrode material and the supporting electrolyte have a strong influence on the rate of atrazine removal. In the chloride medium, the rate of atrazine removal is always greater than in sulfate under all conditions employed. Furthermore, in the sulfate medium, atrazine degradation was significant only at the BDD electrode. The total organic carbon (TOC) load decreased by 79% and 56% at the BDD and DSA electrodes, respectively, in the chloride medium. This trend was maintained in the sulfate medium but the TOC removal was lower (i.e. 33% and 13% at BDD and DSA electrodes, respectively). CA, a stable atrazine degradation intermediate, was also studied and it is efficiently removed using the BDD electrode in both media, mainly when high current densities are employed. The use of the BDD electrode in the chloride medium not only degrades atrazine but also mineralized cyanuric acid leading to the higher TOC removal. PMID:23837356

  8. Influence of surfactant on dynamics of photoinduced motions in a dye-doped deoxyribonucleic acid

    NASA Astrophysics Data System (ADS)

    Mysliwiec, Jaroslaw; Parafiniuk, Kacper; Miniewicz, Andrzej; Rau, Ileana; Kajzar, Francois; Niziol, Jacek; Hebda, Edyta; Pielichowski, Jan; Sahraoui, Bouchta

    2012-10-01

    Pure deoxyribonucleic acid (DNA) is known to be soluble in water only and exhibits poor temperature stability. In contrary, it is well known that the complex of DNA - with cetyltrimethyl ammonium (CTMA) is soluble in alcohols and can be processed into very good optical quality thin films by solution casting and spin deposition. Despite the success of DNA-CTMA, there is still need for new cationic surfactants which would extend the range of available solvents for DNA complex. We test and present experimental results of influence of new surfactants based on benzalkonium chloride (BA), and didecyldimethylammonium chloride (DDCA) for applications in all optical switching.

  9. Amperometric ascorbic acid sensor based on doped ferrites nanoparticles modified glassy carbon paste electrode.

    PubMed

    Dimitrijević, Teodora; Vulić, Predrag; Manojlović, Dragan; Nikolić, Aleksandar S; Stanković, Dalibor M

    2016-07-01

    In this study, a novel electrochemical sensor for quantification of ascorbic acid with amperometric detection in physiological conditions was constructed. For this purpose, cobalt and nickel ferrites were synthesized using microwave and ultrasound assistance, characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray powder diffraction (XRPD), and used for modification of glassy carbon paste electrode (GCPE). It was shown that introducing these nanoparticles to the structure of GCPE led to increasing analytical performance. Co ferrite modified GCPE (CoFeGCPE) showed better characteristics toward ascorbic acid sensing. The limit of detection (LOD) obtained by sensor was calculated to be 0.0270 mg/L, with linear range from 0.1758 to 2.6010 mg/L. This sensor was successfully applied for practical analysis, and the obtained results demonstrated that the proposed procedure could be a promising replacement for the conventional electrode materials and time-consuming and expensive separation methods. PMID:27059753

  10. Genome level analysis of bacteriocins of lactic acid bacteria.

    PubMed

    Singh, Neetigyata Pratap; Tiwari, Abhay; Bansal, Ankiti; Thakur, Shruti; Sharma, Garima; Gabrani, Reema

    2015-06-01

    Bacteriocins are antimicrobial peptides which are ribosomally synthesized by mainly all bacterial species. LABs (lactic acid bacteria) are a diverse group of bacteria that include around 20 genera of various species. Though LABs have a tremendous potential for production of anti-microbial peptides, this group of bacteria is still underexplored for bacteriocins. To study the diversity among bacteriocin encoding clusters and the putative bacteriocin precursors, genome mining was performed on 20 different species of LAB not reported to be bacteriocin producers. The phylogenetic tree of gyrB, rpoB, and 16S rRNA were constructed using MEGA6 software to analyze the diversity among strains. Putative bacteriocins operons identified were found to be diverse and were further characterized on the basis of physiochemical properties and the secondary structure. The presence of at least two cysteine residues in most of the observed putative bacteriocins leads to disulphide bond formation and provide stability. Our data suggests that LABs are prolific source of low molecular weight non modified peptides. PMID:25733445

  11. delta-Aminolevulinic acid dehydratase activity, urinary delta-aminolevulinic acid concentration and zinc protoporphyrin level among people with low level of lead exposure.

    PubMed

    Wang, Qi; Zhao, Huan-hu; Chen, Jian-wei; Hao, Qiao-ling; Gu, Kang-ding; Zhu, Ye-xiang; Zhou, Yi-kai; Ye, Lin-xiang

    2010-01-01

    To evaluate the relationship of delta-aminolevulinic acid dehydratase (ALAD) activity, urinary delta-aminolevulinic acid (ALAU) level and blood zinc protoporphyrin (ZPP) concentration to low blood lead (PbB) levels, these biomarkers were determined for all subjects enrolled from a rural area of southeast China where people had low levels of exposure to lead. The mean values of PbB, ALAD, ALAU and ZPP were 67.11 microg/L (SD: 1.654, range: 10.90-514.04), 339.66 nmol ml(-1)h(-1) (1.419, 78.33-793.13), 20.64 microg/L (1.603, 2.00-326.00), and 0.14 micromol/L (3.437, 0.01-2.26), respectively. ALAD was inversely associated with low levels of PbB. ZPP was inversely related to low levels of PbB but positively related to relatively higher levels of PbB. Alcohol drinking contributed to low ALAD in men. Women had higher ZPP than men. ALAU had no significant association with PbB. In conclusion, ALAD possibly has a non-linear relation with low to moderate levels of PbB. At moderate levels of PbB, ZPP increases with increasing levels of PbB. ALAU is not suitable as an indicator for low levels of lead exposure. PMID:19733117

  12. Doped copolymer of polyanthranilic acid and o-aminophenol (AA-co-OAP): Synthesis, spectral characterization and the use of the doped copolymer as precursor of α-Fe2O3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Hosny, Nasser Mohammed; Nowesser, Nourhan; Al-Hussaini, A. S.; Zoromba, Mohamed Shafick

    2016-02-01

    The copolymer of anthranilic acid and o-aminophenol (AA-co-OAP) was synthesized and characterized by IR, UV-Vis. and thermal analyses (TGA). Linear chain mode was suggested for the pure (AA-co-OAP). The effect of inclusion of MnCl2, CoCl2, NiCl2, CuCl2 and FeCl3 on the spectral, thermal and optical properties of AA-co-OAP has been studied. Octahedral stereochemistry was suggested for Fe, Mn and Ni doped AA-co-OAP, while tetrahedral and square-planar geometries were suggested for Co and Cu doped AA-co-OAP, respectively. Fe doped AA-co-OAP has been used as a precursor for α-Fe2O3 nanoparticles by thermal decomposition route at 800 °C. The obtained hematite has been characterized by XRD and TEM. The average size of the prepared nanoparticles was estimated as 34 nm. The optical band gap of the synthesized hematite nanoparticles was measured and compared with the bulk.

  13. Significantly enhancing supercapacitive performance of nitrogen-doped graphene nanosheet electrodes by phosphoric acid activation.

    PubMed

    Wang, Ping; He, Haili; Xu, Xiaolong; Jin, Yongdong

    2014-02-12

    In this work, we present a new method to synthesize the phosphorus, nitrogen contained graphene nanosheets, which uses dicyandiamide to prevent the aggregation of graphene oxide and act as the nitrogen precursor, and phosphoric acid (H3PO4) as the activation reagent. We have found that through the H3PO4 activation, the samples exhibit the remarkably enhanced supercapacitive performance, and depending on the amount of H3PO4 introduced, the specific capacitance of the samples is gradually increased from 7.6 to 244.6 F g(-1). Meanwhile, the samples also exhibit the good rate capability and excellent stability (up to 10 000 cycles). Through the transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller analyses, H3PO4 treatment induced large pore volume and phosphorus related function groups in the product are assumed to response for the enhancement. PMID:24456232

  14. Synthesis and characterization of self-assembled polyaniline nanotubes doped with D-10-camphorsulfonic acid

    NASA Astrophysics Data System (ADS)

    Zhang, Lijuan; Wan, Meixiang

    2002-12-01

    Conducting nanotubes of polyaniline (PANI) about 80-180 nm in diameter were synthesized by a chemical template-free method in the presence of D-10-camphorsulfonic acid (D-CSA) as the dopant, and ammonium persulfate ((NH4)2S2O8) as the oxidant. The effect of synthetic conditions, such as the molar ratio of D-CSA to aniline (An), the concentration of D-CSA in the polymerization media, the reaction temperature and time, on the morphology and size as well as the electrical properties of the PANI-(D-CSA) was investigated. It was found that the above synthetic conditions, especially the molar ratio of D-CSA to An, strongly affected the morphology and formation probability of the resulting PANI. The micelles formed by D-CSA and anilinium cations act as the templates in the formation of PANI-(D-CSA) nanotubes.

  15. Growth of boric acid crystallites on the surface of boron-doped silicon carbide samples

    SciTech Connect

    Vassen, R.; Stoever, D.

    1996-06-01

    White crystallites were visually observed on fractured or polished surfaces of SiC samples (grain sizes below {approx}500 nm) during exposure to air at room temperature for several days. Characterization of the crystallites by scanning electron microscopy, secondary ion mass spectroscopy, and X-ray diffraction identified B(OH){sub 3} crystals with a strong (002) texture. The rate of boric acid formation was determined by a gravimetric experiment. The rate of weight gain increased significantly after an incubation period of 1 week. Nucleation is initially the rate-limiting process. Subsequently small B(OH){sub 3} crystals form on the surface, whose growth rate is determined by grain boundary diffusion of boron to the SiC surface. An estimated grain boundary boron to the SiC surface. An estimated grain boundary diffusion coefficient of boron in SiC was many orders of magnitude higher than extrapolated literature values.

  16. Optical Energy Levels Scheme for Co2+ doped in K(Mg,Zn)F3 Fluoroperovskites

    NASA Astrophysics Data System (ADS)

    Barb, A. M.; Gruia, A. S.; Avram, C. N.

    2016-02-01

    The aim of this paper is to model the crystal field parameters and simulate the fine structure of optical energy levels scheme of Co2+:K(Mg,Zn)F3 systems. The crystal field parameters were modeled in the frame of an Exchange Charge Model of the crystal field theory, taking into account the effects of the covalent bond formation between the Co2+ and F- ions. The obtained parameters were used for simulating the fine structure of the system energy levels scheme, by diagonalization of the full Hamiltonian matrix, in the base of 100 wave functions of Co2+ ion. For resolving some discrepancies, the electron-phonon interaction in 4T2g excited state is investigated in the frame of the Ham theory, with the Jahn-Teller stabilization energy calculation. The comparison of the calculated energy levels with experimental data gives a good agreement, which confirms the model and used method.

  17. Plasma and cerebrosponal fluid amino acid levels in diabetic ketoacidosis before and after corrective therapy.

    PubMed

    Aoki, T T; Assal J-P; Manzano, F M; Kozak, G P; Cahill, G F

    1975-05-01

    To evaluate the effect of insulin-saline-bicarbonate therapy on amino acid metabolism in diabetic ketoacidosis, arterial and venous blood samples as well as cerebrospinal fluid (CSF) were obtained from six patients before and after initiation of corrective therapy. Levels of CSF glutamine were decreased while alanine alpha-amino-n-butyrate, valine, isoleucine and leucine were increased significantly compared to a control group composed of six normal, postabsorptive adults free of any neurologic disease. Following therapy, CSF levels of alanine, alpha-amino-n-butyrate, valine, isoleucine, and leucine declined while glutamine levels did not change. Admission arterial plasma levels of the glycogenic amino acids were lower than normal while the branched-chain amino acids were elevated. Plasma alanine and glutamine arterio-venous (A-V) differences across forearm tissue were larger. After four hours of corrective therapy, arterial plasma levels of most of the amino acids had declined sharply and A-V differences for glutamine and alanine were markedly reduced (p smaller than.025 and p smaller than.01, paired t, respectively). Coincident with the decrease in A-V amino acid differences, plasma glucagon and free fatty acid levels declined significantly. These data suggest that the effect exerted by insulin-saline-bicarbonate therapy on amino acid metabolism is manifested by diminished A-V plasma alanine and glutamine differences across forearm tissue. Thus, the role played by the splanchnic bed both before and following corrective measures may be secondary to substrate availability. PMID:805076

  18. Effects of toxic work environments on sperm quality and ascorbic acid levels

    SciTech Connect

    Dawson, E.B.; Harris, W.A.; Powell, L.C. )

    1990-02-26

    Surveys have shown that toxic work environments lower sperm quality, and controlled studies indicate that ascorbic acid supplementation improves sperm viability and agglutination. The sperm quality of 50 subjects each from: (1) office workers, (2) a lead smelter, (3) petroleum refineries, and (4) a herbicide plant were compared with serum and semen ascorbic acid levels. The sperm characteristics studied were: count as million/ml and as percent; viability, motility, clumping, and abnormal morphology. The serum ascorbic acid levels were directly proportional to sperm viability and inversely correlated to clumping of all groups. Moreover, serum ascorbic acid levels were also inversely correlated to twin tail and amorphous forms of abnormal sperm morphology. The results of the study indicate that toxic environments depress sperm quality and suggest that ascorbic acid supplementation will improve sperm quality and fertility.

  19. Unusually high levels of n-6 polyunsaturated fatty acids in whale sharks and reef manta rays.

    PubMed

    Couturier, L I E; Rohner, C A; Richardson, A J; Pierce, S J; Marshall, A D; Jaine, F R A; Townsend, K A; Bennett, M B; Weeks, S J; Nichols, P D

    2013-10-01

    Fatty acid (FA) signature analysis has been increasingly used to assess dietary preferences and trophodynamics in marine animals. We investigated FA signatures of connective tissue of the whale shark Rhincodon typus and muscle tissue of the reef manta ray Manta alfredi. We found high levels of n-6 polyunsaturated fatty acids (PUFA), dominated by arachidonic acid (20:4n-6; 12-17 % of total FA), and comparatively lower levels of the essential n-3 PUFA-eicosapentaenoic acid (20:5n-3; ~1 %) and docosahexaenoic acid (22:6n-3; 3-10 %). Whale sharks and reef manta rays are regularly observed feeding on surface aggregations of coastal crustacean zooplankton during the day, which generally have FA profiles dominated by n-3 PUFA. The high levels of n-6 PUFA in both giant elasmobranchs raise new questions about the origin of their main food source. PMID:23975574

  20. Modeling and optimization of actively Q-switched Nd-doped quasi-three-level laser

    NASA Astrophysics Data System (ADS)

    Yan, Renpeng; Yu, Xin; Li, Xudong; Chen, Deying; Gao, Jing

    2013-09-01

    The energy transfer upconversion and the ground state absorption are considered in solving the rate equations for an active Q-switched quasi-three-level laser. The dependence of output pulse characters on the laser parameters is investigated by solving the rate equations. The influence of the energy transfer upconversion on the pulsed laser performance is illustrated and discussed. By this model, the optimal parameters could be achieved for arbitrary quasi-three-level Q-switched lasers. An acousto-optical Q-switched Nd:YAG 946 nm laser is constructed and the reliability of the theoretical model is demonstrated.

  1. Changes in Metabolite Levels in Kalanchoë daigremontiana and the Regulation of Malic Acid Accumulation in Crassulacean Acid Metabolism.

    PubMed

    Cockburn, W; McAulay, A

    1977-03-01

    Changes in glucose-6-P, fructose-6-P, fructose-1,6-diP, 6-phospho-gluconate, phosphoenolpyruvate, 3-phosphoglycerate, and pyruvate levels in the leaves of the Crassulacean plant Kalanchoë daigremontiana Hammet et Perrier were measured enzymically during transitions from CO(2)-free air to air, air to CO(2)-free air, and throughout the course of acid accumulation in darkness. The data are discussed in terms of the involvement of phosphoenolpyruvate carboxylase in malic acid synthesis and in terms of the regulation of the commencement of malic acid synthesis and accumulation through the effects of CO(2) on storage carbohydrate mobilization and its termination through the effects of malic acid on phosphoenolpyruvate carboxylase activity. PMID:16659872

  2. Structural, electronic and photoluminescence properties of Eu3+-doped CaYAlO4 obtained by using citric acid complexes as precursors

    NASA Astrophysics Data System (ADS)

    Perrella, R. V.; Júnior, C. S. Nascimento; Góes, M. S.; Pecoraro, E.; Schiavon, M. A.; Paiva-Santos, C. O.; Lima, H.; Couto dos Santos, M. A.; Ribeiro, S. J. L.; Ferrari, J. L.

    2016-07-01

    The search for new materials that meet the current technological demands for photonic applications, make the Rare Earth ions embedded in inorganic oxides as excellent candidates for several technological devices. This work presents the synthesis of Eu3+-doped CaYAlO4 using citric acid as ligand to form a complex precursor. The methodology used has big draw due to its easy handling and low cost of the materials. The thermal analysis of viscous solutions was evaluated and the obtained compounds show the formation of a polycrystalline tetragonal phase. Rietveld refinement was used to understand the structural and the cell parameters of the crystalline phase as a function of temperature of heat-treatment. Crystallite size and microstrain were determined and were shown to have a direct relationship with the temperature of the heat-treatment. The band-gap of the CaYAlO4 doped with 1 and 10 mol% of Eu3+ showed values close to 4.30 eV, resulting in their transparency in the visible region between 330 and 750 nm. Besides the intense photoluminescence from Eu3+, a study was conducted to evaluate the possible position of the Eu3+ in the CaYAlO4 as host lattice. Lifetime of the emission decay from Eu3+ excited state 5D0 show that CaYAlO4 is a good host to rare earth ions, once it can avoid clustering of these ions in concentration as high as 10 mol%. The predictions of the sublevels of the 7F1 crystal field level are discussed through the method of equivalent nearest neighbours (MENN). The intensity parameters (Ωλ, λ = 2 and 4) are reproduced with physically reasonable values of average polarizabilities. The set of charge factors used in both calculations are in good agreement with the charge of the europium ion described by the Batista-Longo improved model (BLIM). The quantum efficiencies of the materials were calculated based on Judd-Ofelt theory. Based on the results obtained in this work, the materials have potential use in photonic devices such as lasers and solid

  3. Plasma levels of ursodeoxycholic acid in black bears, Ursus americanus: seasonal changes.

    PubMed

    Solá, Susana; Garshelis, David L; Amaral, Joana D; Noyce, Karen V; Coy, Pam L; Steer, Clifford J; Iaizzo, Paul A; Rodrigues, Cecília M P

    2006-06-01

    To date, no other studies have examined the seasonal changes in circulating levels of various bile acids in the plasma of wild North American black bears, Ursus americanus. Using gas chromatography, bile acid concentrations were measured in plasma samples obtained during either early or late hibernation, and during summer active periods. Thus, specific compositional changes from individual animals were examined through a given year. Total bile acid concentrations in the plasma of these normal animals were found to range between 0.2 and 3.1 micromol/L (0.9 +/- 0.2 micromol/L, mean +/- SEM). Cholic, ursodeoxycholic and chenodeoxycholic acids were the major bile acid species identified. Ursodeoxycholic acid represented 28.0 +/- 2.6% of the total bile acid pool. Deoxycholic and lithocholic acids were found only in small amounts. In addition, total bile acid concentrations were lower in plasma samples obtained during hibernation compared with those obtained during summer active periods (0.6 +/- 0.1 and 1.2 +/- 0.4 micromol/L, respectively; p < 0.05). However, the relative proportion of ursodeoxycholic acid, was significantly greater in winter than in summer (31.5 +/- 3.2% and 22.2 +/- 4.5%, p < 0.05). Finally, taurine-conjugated bile acids were the predominant species in bear plasma, accounting for >67% of the total bile acids. These data demonstrate that ursodeoxycholic acid is a major bile acid in black bear plasma, mostly conjugated with taurine. Further, the finding of seasonal variation in plasma bile acid composition provides evidence to support the possible role that ursodeoxycholic acid may play in cellular protection in hibernating black bears. PMID:16571381

  4. Inhibitions of several antineoplastic drugs on serum sialic Acid levels in mice bearing tumors.

    PubMed

    Lu, Da-Yong; Xu, Jing; Lu, Ting-Ren; Wu, Hong-Ying; Xu, Bin

    2013-03-01

    Six murine tumors, including ascetic tumors HepA, EC, P388 leukemia, S180 and solid tumor S180, and Lewis lung carcinoma, were employed in this work. The free sialic acid concentrations in both blood and ascites were measured in tumor-bearing mice. The results showed that the content of sialic acids in blood was increased in tumor growth and certain tumor types. Higher sialic acid content was observed in ascites than that present in blood. The influence of antineoplastic agents (vincristine, thiotepa, adriamycin, probimane, cisplatin, oxalysine, cortisone, nitrogen mustard, lycobetaine, Ara-C, harringtonine, and cyclophosphamide) on the content of sialic acids in mice blood bearing solid tumors of either S180 or Lewis lung carcinoma was observed. Different inhibitions of antineoplastic drugs on both tumor growth and serum sialic acid levels in mice bearing tumors were found. Among these antineoplastic drugs, probimane, cisplatin, nitrogen mustard, and lycobetaine were able to decrease the serum sialic acid levels in mice bearing tumors. Since these four antineoplastic drugs are all DNA chelating agents, it was proposed that the inhibition of tumor sialic acids by these drugs might be through the DNA template via two ways. Since we have found no effect of antineoplastic drugs on serum sialic acid levels in normal mice, this suggests that the inhibition of antineoplastic drugs on sialic acids is by tumor involvement. PMID:23641340

  5. Dissolution of Simulated and Radioactive Savannah River Site High-Level Waste Sludges with Oxalic Acid & Citric Acid Solutions

    SciTech Connect

    STALLINGS, MARY

    2004-07-08

    sludge solids. We recommend that these results be evaluated further to determine if these solutions contain sufficient neutron poisons. We observed low general corrosion rates in tests in which carbon steel coupons were contacted with solutions of oxalic acid, citric acid and mixtures of oxalic and citric acids. Wall thinning can be minimized by maintaining short contact times with these acid solutions. We recommend additional testing with oxalic and oxalic/citric acid mixtures to measure dissolution performance of sludges that have not been previously dried. This testing should include tests to clearly ascertain the effects of total acid strength and metal complexation on dissolution performance. Further work should also evaluate the downstream impacts of citric acid on the SRS High-Level Waste System (e.g., radiochemical separations in the Salt Waste Processing Facility and addition of organic carbon in the Saltstone and Defense Waste Processing facilities).

  6. Investigations on the growth, optical, thermal, dielectric, and laser damage threshold properties of crystal violet dye-doped potassium acid phthalate single crystal

    NASA Astrophysics Data System (ADS)

    Rao, G. Babu; Rajesh, P.; Ramasamy, P.

    2016-03-01

    Influence of crystal violet dye with different concentration on potassium acid phthalate single crystal grown by conventional method has been studied. No change has been observed in the structure, whereas changes have been observed in the external morphology of the crystal when the dyes are incorporated in the crystal lattice. Thermogravimetric and differential thermal analyses show the onset decomposition temperatures to be at 302, 285, 284, and 285 °C for pure, 0.1, 0.3, and 0.5 mol% crystal violet-doped potassium acid phthalate crystals, respectively. The dielectric measurement was carried out on the grown crystals as a function of frequency at various temperatures. In addition, strong luminescent emission bands at 638, 648, and 640 nm were observed in which the relative intensity was found to be reversed as a result of doping concentration. The laser damage threshold value significantly increased for dye-doped crystal in comparison with pure crystal which may make it suitable for the solid-state dye laser applications.

  7. Element-Doped Polyacrylic Acid Thin Films as SIMS Standards for Organic Materials

    NASA Astrophysics Data System (ADS)

    Davisson, M.; Phinney, D. L.; Weber, P. K.

    2009-12-01

    To constrain relative sensitive factors for SIMS elemental analysis of organic materials, calibration standards are being developed by coordinating ppm quantities of Group I, Group II, and transition metals with polyacrylic acid resin and depositing them as thin films. Each element is prepared as an aqueous acetate, oxalate, or nitrate solution to avoid unwanted elements that compromise thin film uniformity or produce interfering masses. These are subsequently mixed proportionally with reagent grade resins (Mw ~2000 and ~50,000), and dried passively on an Al bullet or spin-coated for thin layering (~100nm). Initial results using an O- primary beam on a Cameca NanoSIMS demonstrate excellent lateral homogeneity for Na, K, Fe, Co, and Cd at nanometer scale and consistent ratios to 12C (stdev <10%) over multiple 10um raster areas, whereas Mg, Ca, Sr, and Cu show variable ratios to 12C over sputter depth (stdev >10%). Depth profiling over the entire film thickness using a Cameca 3f show high reproducibility of element trends at 250um raster areas. Additional measurements will incorporate multi-element suites of biologically-relevant species (e.g. Na, K, Ca, P) to facilitate quantitative analysis of sensitivity factors with compositional changes.

  8. Supramolecular guest-host systems: combining high dye doping level with low aggregation tendency

    NASA Astrophysics Data System (ADS)

    Priimagi, Arri; Cattaneo, Stefano; Ras, Robin H. A.; Valkama, Sami; Ikkala, Olli; Kauranen, Martti

    2006-08-01

    We demonstrate that the aggregation tendency of dye molecules in a host polymer can be significantly reduced by exploiting non-covalent interactions between the host polymer and guest dye molecules. Such interactions occur spontaneously with no need for chemical synthesis, and could thus be utilized to combine the ease of processing of traditional guest-host systems with the high dye concentrations achievable in covalently linked systems. We studied the aggregation properties of the common azo-dye Disperse Red 1 in polymers with different functional groups. Compared to a nonpolar polymer (polystyrene), dye aggregation tendency is substantially reduced in polar polymer matrices containing hydrogen-bond donating [poly(vinylphenol)] or hydrogen-bond accepting [poly(4-vinylpyridine)] functional sites. Furthermore, by forming a polyelectrolyte-dye complex [Disperse Red 1/poly(styrenesulfonic acid)], a dye monomer can be attached to approximately each polymer unit, resulting in dye concentration of 63 wt. %. Complexation through proton transfer was further studied by using a fluorescent dye 5-phenyl-2-(4-pyridyl)oxazole. Our results indicate that polymer-dye complexes could provide a facile route for new type of optical materials, with potential applications in various fields of optics and photonics.

  9. Photocatalytic activity of undoped and Ag-doped TiO{sub 2}-supported zeolite for humic acid degradation and mineralization

    SciTech Connect

    Lazau, C.; Ratiu, C.; Orha, C.; Pode, R.; Manea, F.

    2011-11-15

    Highlights: {yields} Hybrid materials based on natural zeolite and TiO{sub 2} obtained by solid-state reaction. {yields} XRD proved the presence of anatase form of undoped and Ag-doped TiO{sub 2} onto zeolite. {yields} FT-IR spectra evidenced the presence on TiO{sub 2} bounded at the zeolite network. {yields} Ag-doped TiO{sub 2} onto zeolitic matrix exhibited an enhanced photocatalytic activity. -- Abstract: The hybrid materials based on natural zeolite and undoped and Ag-doped TiO{sub 2}, i.e., Z-Na-TiO{sub 2} and Z-Na-TiO{sub 2}-Ag, were successfully synthesized by solid-state reaction in microwave-assisted hydrothermal conditions. Undoped TiO{sub 2} and Ag-doped TiO{sub 2} nanocrystals were previously synthesized by sol-gel method. The surface characterization of undoped TiO{sub 2}/Ag-doped TiO{sub 2} and natural zeolite hybrid materials has been investigated by X-ray diffraction, DRUV-VIS spectroscopy, FT-IR spectroscopy, BET analysis, SEM microscopy and EDX analysis. The results indicated that anatase TiO{sub 2} is the dominant crystalline type as spherical form onto zeolitic matrix. The presence of Ag into Z-Na-TiO{sub 2}-Ag was confirmed by EDX analysis. The DRUV-VIS spectra showed that Z-Na-TiO{sub 2}-Ag exhibited absorption within the range of 400-500 nm in comparison with Z-Na-TiO{sub 2} catalyst. The enhanced photocatalytic activity of Z-Na-TiO{sub 2}-Ag catalyst is proved through the degradation and mineralization of humic acid under ultraviolet and visible irradiation.

  10. Effective role of trifluoroacetic acid (TFA) to enhance the photocatalytic activity of F-doped TiO2 prepared by modified sol-gel method

    NASA Astrophysics Data System (ADS)

    Samsudin, Emy Marlina; Hamid, Sharifah Bee Abd; Juan, Joon Ching; Basirun, Wan Jefrey; Kandjani, Ahmad Esmaielzadeh; Bhargava, Suresh K.

    2016-03-01

    Highly photoactive mesoporous F-doped TiO2 with improved physico-chemical characteristics is achieved using modified sol-gel method. The usage of trifluoroacetic as fluorine precursor significantly modifies the morphology, size, pore shape, crystal phase, crystal structure, surface chemical state and to a lesser extent, {1 0 1} and {0 0 1} facets. The accessibility of fluoride ions on Tisbnd Osbnd Ti polymer chains during crystal growth during the sol-gel process remarkably influences the properties of catalyst. To the best of our knowledge, preparation of F-doped TiO2 using modified sol-gel and trifluoroacetic acid are limited, and still not enough. Thus this work provides additional insight by using an approach which is less hazardous, less costly and practical for large scale agile development in the photocatalysis industry.

  11. Combination of cathodic reduction with adsorption for accelerated removal of Cr(VI) through reticulated vitreous carbon electrodes modified with sulfuric acid-glycine co-doped polyaniline.

    PubMed

    Mo, Xi; Yang, Zhao-hui; Xu, Hai-yin; Zeng, Guang-ming; Huang, Jing; Yang, Xia; Song, Pei-pei; Wang, Li-ke

    2015-04-01

    Improving the reduction kinetics is crucial in the electroreduction process of Cr(VI). In this study, we developed a novel adsorption-electroreduction system for accelerated removal of Cr(VI) by employing reticulated vitreous carbon electrode modified with sulfuric acid-glycine co-doped polyaniline (RVC/PANI-SA-GLY). Firstly, response surface methodology confirmed the optimum polymerization condition of co-doped polyaniline for modifying electrodes (Aniline, sulfuric acid and glycine, respectively, of 0.2 mol/L, 0.85 mol/L, 0.93 mol/L) when untraditional dopant glycine was added. Subsequently, RVC/PANI-SA-GLY showed higher Cr(VI) removal percentages in electroreduction experiments over RVC electrode modified with sulfuric acid doped polyaniline (RVC/PANI-SA) and bare RVC electrode. In contrast to RVC/PANI-SA, the improvement by RVC/PANI-SA-GLY was more significant and especially obvious at more negative potential, lower initial Cr(VI) concentration, relatively less acidic solution and higher current densities, best achieving 7.84% higher removal efficiency with entire Cr(VI) eliminated after 900 s. Current efficiencies were likewise enhanced by RVC/PANI-SA-GLY under quite negative potentials. Fourier transform infrared (FTIR) and energy dispersive spectrometer (EDS) analysis revealed a possible adsorption-reduction mechanism of RVC/PANI-SA-GLY, which greatly contributed to the faster reduction kinetics and was probably relative to the absorption between protonated amine groups of glycine and HCrO4(-). Eventually, the stability of RVC/PANI-SA-GLY was proven relatively satisfactory. PMID:25603298

  12. Millijoule-level picosecond mid-infrared optical parametric amplifier based on MgO-doped periodically poled lithium niobate.

    PubMed

    Xu, Hongyan; Yang, Feng; Chen, Ying; Liu, Ke; Du, Shifeng; Zong, Nan; Yang, Jing; Bo, Yong; Peng, Qinjun; Zhang, Jingyuan; Cui, Dafu; Xu, Zuyan

    2015-03-20

    A millijoule-level high pulse energy picosecond (ps) mid-infrared (MIR) optical parametric amplifier (OPA) at 3.9 μm based on large-aperture MgO-doped periodically poled lithium niobate (MgO:PPLN) crystal was demonstrated for the first time, to the best of our knowledge. The MIR OPA was pumped by a 30 ps 1064 nm Nd:YAG laser at 10 Hz and injected by an energy-adjustable near-infrared seed based on a barium boron oxide (BBO) optical parametric generator/optical parametric amplifier (OPG/OPA) with double-pass geometry. Output energy of 1.14 mJ at 3.9 μm has been obtained at pump energy of 15.2 mJ. Furthermore, the performance of MIR OPG in MgO:PPLN was also investigated for comparing with the seeded OPA. PMID:25968539

  13. Energy level alignment of electrically doped hole transport layers with transparent and conductive indium tin oxide and polymer anodes

    NASA Astrophysics Data System (ADS)

    Fehse, Karsten; Olthof, Selina; Walzer, Karsten; Leo, Karl; Johnson, Robert L.; Glowatzki, Hendrik; Bröker, Benjamin; Koch, Norbert

    2007-10-01

    Using ultraviolet photoemission spectroscopy, we investigated the energy level alignment at the interfaces of typical anodes used in organic electronics, indium tin oxide (ITO) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), with the oligomeric hole transport material N ,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD), and studied the influence of electrical interface doping by the strong electron acceptor tetrafluoro tetracyanoquinodimethane (F4-TCNQ). The fundamentally different anode materials with work functions of 4.40eV (ITO) and 4.85eV (PEDOT:PSS) show different hole injection barriers, which also depend on the thickness of the F4-TCNQ interface dopant layer. PEDOT:PSS anodes exhibit a consistently lower hole injection barrier to MeO-TPD compared to ITO by 0.1eV. We attribute this low hole injection barrier to additional charge transfer reactions at the PEDOT:PSS/MeO-TPD interface. In contrast, the deposition of the electron acceptor at the interface helps significantly to lower the hole injection barrier for ITO anodes.

  14. Coherent dynamics of Landau-Levels in modulation doped GaAs quantum wells at high magnetic fields

    NASA Astrophysics Data System (ADS)

    Liu, Cunming; Paul, Jagannath; Reno, John; McGill, Stephen; Hilton, David; Karaiskaj, Denis

    By using two-dimensional Fourier transform spectroscopy, we investigate the dynamics of Landau-Levels formed in modulation doped GaAs/AlGaAs quantum wells of 18 nm thickness at high magnetic fields and low temperature. The measurements show interesting dephasing dynamics and linewidth dependency as a function of the magnetic field. The work at USF and UAB was supported by the National Science Foundation under grant number DMR-1409473. The work at NHMFL, FSU was supported by the National Science Foundation under grant numbers DMR-1157490 and DMR-1229217. This work was performed, in part, at the Center for Integrated Nanotechnologies, a U.S. Department of Energy, Office of Basic Energy Sciences user facility. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract No. DE-AC04-94AL85000.

  15. Exploration of Zn resonance levels and thermoelectric properties in I-doped PbTe with ZnTe nanostructures.

    PubMed

    Rawat, P K; Paul, B; Banerji, P

    2014-03-26

    Motivated by the theoretically predicted Zn resonant states in the conduction band of PbTe, in the present work, we investigated the effect of Zn substitution on the thermoelectric properties in I-doped n-type PbTe. The room temperature thermopower values show good agreement with the theoretical Pisarenko plot of PbTe up to a carrier concentration of 4.17 × 10(19) cm(-3); thus, the presence of Zn resonance levels is not observed. Because of the low solubility of Zn in PbTe, a second phase of coherent ZnTe nanostructures is observed within the PbTe host matrix, which is found to reduce the lattice thermal conductivity. The reduced lattice thermal conductivity in PbTe by ZnTe nanostructures leads to notable enhancement in the figure of merit with a maximum value of 1.35 at 650 K. In contrast to the recent literature, the carrier mobility is not found to be affected by the band offset between ZnTe nanostructures and PbTe. This is explained by the quantum tunneling of the charge carrier through the narrow offset barrier and depletion width and coherent nature of the interface boundary between the two phases, i.e., ZnTe and PbTe. PMID:24575978

  16. Amino acid limitation induces down-regulation of WNT5a at transcriptional level

    SciTech Connect

    Wang Zuguang; Chen Hong

    2009-01-23

    An aberrant WNT signaling contributes to the development and progression of multiple cancers. WNT5a is one of the WNT signaling molecules. This study was designed to test the hypothesis that amino acid deprivation induces changes in the WNT signaling pathway in colon cancer cells. Results showed that targets of the amino acid response pathway, ATF3 and p21, were induced in the human colon cancer cell line SW480 during amino acid limitation. There was a significant decrease in the WNT5a mRNA level following amino acid deprivation. The down-regulation of WNT5a mRNA by amino acid deprivation is not due to mRNA destabilization. There is a reduction of nuclear {beta}-catenin protein level by amino acid limitation. Under amino acid limitation, phosphorylation of ERK1/2 was increased and the blockage of ERK1/2 by the inhibitor U0126 partially restored WNT5a mRNA level. In conclusion, amino acid limitation in colon cancer cells induces phosphorylation of ERK1/2, which then down-regulates WNT5a expression.

  17. High glucose levels reduce fatty acid oxidation and increase triglyceride accumulation in human placenta.

    PubMed

    Visiedo, Francisco; Bugatto, Fernando; Sánchez, Viviana; Cózar-Castellano, Irene; Bartha, Jose L; Perdomo, Germán

    2013-07-15

    Placentas of women with gestational diabetes mellitus (GDM) exhibit an altered lipid metabolism. The mechanism by which GDM is linked to alterations in placental lipid metabolism remains obscure. We hypothesized that high glucose levels reduce mitochondrial fatty acid oxidation (FAO) and increase triglyceride accumulation in human placenta. To test this hypothesis, we measured FAO, fatty acid esterification, de novo fatty acid synthesis, triglyceride levels, and carnitine palmitoyltransferase activities (CPT) in placental explants of women with GDM or no pregnancy complication. In women with GDM, FAO was reduced by ~30% without change in mitochondrial content, and triglyceride content was threefold higher than in the control group. Likewise, in placental explants of women with no complications, high glucose levels reduced FAO by ~20%, and esterification increased linearly with increasing fatty acid concentrations. However, de novo fatty acid synthesis remained unchanged between high and low glucose levels. In addition, high glucose levels increased triglyceride content approximately twofold compared with low glucose levels. Furthermore, etomoxir-mediated inhibition of FAO enhanced esterification capacity by ~40% and elevated triglyceride content 1.5-fold in placental explants of women, with no complications. Finally, high glucose levels reduced CPT I activity by ~70% and phosphorylation levels of acetyl-CoA carboxylase by ~25% in placental explants of women, with no complications. We reveal an unrecognized regulatory mechanism on placental fatty acid metabolism by which high glucose levels reduce mitochondrial FAO through inhibition of CPT I, shifting flux of fatty acids away from oxidation toward the esterification pathway, leading to accumulation of placental triglycerides. PMID:23673156

  18. Molecular dynamics investigation of separation of hydrogen sulfide from acidic gas mixtures inside metal-doped graphite micropores.

    PubMed

    Huang, Pei-Hsing

    2015-09-21

    The separation of poisonous compounds from various process fluids has long been highly intractable, motivating the present study on the dynamic separation of H2S in acidic-gas-mixture-filled micropores. The molecular dynamics approach, coupled with the isothermal-isochoric ensemble, was used to model the molecular interactions and adsorption of H2S/CO2/CO/H2O mixtures inside metal-doped graphite slits. Due to the difference in the adsorption characteristics between the two distinct adsorbent materials, the metal dopant in the graphitic micropores leads to competitive adsorption, i.e. the Au and graphite walls compete to capture free adsorbates. The effects of competitive adsorption, coupled with changes in the gas temperature, concentration, constituent ratio and slit width on the constituent separation of mixtures were systematically studied. The molecule-wall binding energies calculated in this work (those of H2S, H2O and CO on Au walls and those of H2O, CO and CO2 on graphite walls) show good agreement with those obtained using density functional theory (DFT) and experimental results. The z-directional self-diffusivities (Dz) for adsorbates inside the slit ranged from 10(-9) to 10(-7) m(2) s(-1) as the temperature was increased from 10 to 500 K. The values are comparable with those for a typical microporous fluid (10(-8)-10(-9) m(2) s(-1) in a condensed phase and 10(-6)-10(-7) m(2) s(-1) in the gaseous state). The formation of H-bonding networks and hydrates of H2S is disadvantageous for the separation of mixtures. The results indicate that H2S can be efficiently separated from acidic gas mixtures onto the Au(111) surface by (i) reducing the mole fraction of H2S and H2O in the mixtures, (ii) raising the gas temperature to the high temperature limit (≥400 K), and (iii) lowering the slit width to below the threshold dimension (≤23.26 Å). PMID:26256825

  19. Evaluation of circulating levels and renal clearance of natural amino acids in patients with Cushing's disease.

    PubMed

    Faggiano, A; Pivonello, R; Melis, D; Alfieri, R; Filippella, M; Spagnuolo, G; Salvatore, F; Lombardi, G; Colao, A

    2002-02-01

    Although the hypercortisolism-induced impairment of protein homeostasis is object of several studies, a detailed evaluation of the complete amino acid profile of patients with Cushing's syndrome (CS) has never been performed. The aim of the current open transversal controlled study was to evaluate serum and urinary concentrations as well as renal clearance of the complete series of natural amino acids and their relationship with glucose tolerance in patients with Cushing's disease (CD). Twenty patients with CD (10 active and 10 cured) and 20 sex- and age-matched healthy controls entered the study. Measurement of serum and urinary levels of the complete series of natural amino acids was performed in all patients analyzed by cationic exchange high performance liquid cromatography (HPLC) after 2 weeks of a standardized protein intake regimen. The renal clearance (renal excretion rate) of each amino acid was calculated on the basis of the serum and urinary concentrations of creatinine and the specific amino acid. Fasting glucose and insulin levels, glucose and insulin response to standard glucose load, insulinogenic and homeostasis model insulin resistance (Homa-R) indexes were also evaluated and correlated to the circulating levels and renal clearances of each amino acid. Significantly higher serum (p<0.01) and urinary (p<0.05) levels of alanine and cystine, lower serum and higher urinary levels of leucine, isoleucine and valine (p<0.05) and higher renal excretion rates of leucine, isoleucine and valine (p<0.01) were found in patients with active CD than in patients cured from the disease and in controls. No difference was found between cured patients and controls. Creatinine clearance was similar in active and cured patients and in controls. In patients with active CD, urinary cortisol levels were significantly correlated to urinary cystine levels (r=0.85; p<0.01) and renal excretion rate of leucine (r=-0.76; p<0.05), isoleucine (r=-0.76; p<0.05) and valine (r=-0

  20. Uric Acid Levels Can Predict Metabolic Syndrome and Hypertension in Adolescents: A 10-Year Longitudinal Study

    PubMed Central

    Sun, Hai-Lun; Pei, Dee; Lue, Ko-Huang; Chen, Yen-Lin

    2015-01-01

    The relationships between uric acid and chronic disease risk factors such as metabolic syndrome, type 2 diabetes mellitus, and hypertension have been studied in adults. However, whether these relationships exist in adolescents is unknown. We randomly selected 8,005 subjects who were between 10 to 15 years old at baseline. Measurements of uric acid were used to predict the future occurrence of metabolic syndrome, hypertension, and type 2 diabetes. In total, 5,748 adolescents were enrolled and followed for a median of 7.2 years. Using cutoff points of uric acid for males and females (7.3 and 6.2 mg/dl, respectively), a high level of uric acid was either the second or third best predictor for hypertension in both genders (hazard ratio: 2.920 for males, 5.222 for females; p<0.05). However, uric acid levels failed to predict type 2 diabetes mellitus, and only predicted metabolic syndrome in males (hazard ratio: 1.658; p<0.05). The same results were found in multivariate adjusted analysis. In conclusion, a high level of uric acid indicated a higher likelihood of developing hypertension in both genders and metabolic syndrome in males after 10 years of follow-up. However, uric acid levels did not affect the occurrence of type 2 diabetes in both genders. PMID:26618358

  1. Uric Acid Levels Can Predict Metabolic Syndrome and Hypertension in Adolescents: A 10-Year Longitudinal Study.

    PubMed

    Sun, Hai-Lun; Pei, Dee; Lue, Ko-Huang; Chen, Yen-Lin

    2015-01-01

    The relationships between uric acid and chronic disease risk factors such as metabolic syndrome, type 2 diabetes mellitus, and hypertension have been studied in adults. However, whether these relationships exist in adolescents is unknown. We randomly selected 8,005 subjects who were between 10 to 15 years old at baseline. Measurements of uric acid were used to predict the future occurrence of metabolic syndrome, hypertension, and type 2 diabetes. In total, 5,748 adolescents were enrolled and followed for a median of 7.2 years. Using cutoff points of uric acid for males and females (7.3 and 6.2 mg/dl, respectively), a high level of uric acid was either the second or third best predictor for hypertension in both genders (hazard ratio: 2.920 for males, 5.222 for females; p<0.05). However, uric acid levels failed to predict type 2 diabetes mellitus, and only predicted metabolic syndrome in males (hazard ratio: 1.658; p<0.05). The same results were found in multivariate adjusted analysis. In conclusion, a high level of uric acid indicated a higher likelihood of developing hypertension in both genders and metabolic syndrome in males after 10 years of follow-up. However, uric acid levels did not affect the occurrence of type 2 diabetes in both genders. PMID:26618358

  2. Low-temperature sintering of silica-boric acid-doped willemite and microwave dielectric properties

    NASA Astrophysics Data System (ADS)

    Ando, Minato; Ohsato, Hitoshi; Igimi, Daisuke; Higashida, Yutaka; Kan, Akinori; Suzuki, Sadahiko; Yasufuku, Yoshitoyo; Kagomiya, Isao

    2015-10-01

    Millimeter-wave wireless communications in a high-level information society have been expanding in terms of high-density data transfer and radar for pre-crash safety systems. For these communications, millimeter-wave dielectrics have been expected for the development of substrates with high quality factor (Qf), low dielectric constant (ɛr), and near-zero temperature coefficient of resonance frequency (TCf). We have been studying several silicates such as forsterite, willemite, diopside, wollastonite, and cordierite/indialite glass ceramics. In this study, the synthesis of willemite and low-temperature-sintered willemite for low temperature co-fired ceramics (LTCC) is examined. The raw materials used for preparing slurries in doctor blade tape casting are also analyzed.

  3. Crystal-field level inversion in lightly Mn-doped Sr3Ru2O7

    SciTech Connect

    Hossain, M. A.; Hu, Z.; Haverkort, M. W.; Burnus, T.; Chang, C. F.; Klein, S.; Denlinger, J. D.; Lin, H.-J.; Chen, C. T.; Mathieu, R.; Kaneko, Y.; Tokura, Y.; Satow, S.; Yoshida, Y.; Takagi, H.; Tanaka, A.; Elfimov, I. S.; Sawatzky, G. A.; Tjeng, L. H.; Damascelli, A.

    2008-01-15

    Sr3(Ru1-xMnx)2O7, in which 4d-Ru is substituted by the more localized 3d-Mn, is studied by x-ray dichroism and spin-resolved density functional theory. We find that Mn impurities do not exhibit the same 4+ valence of Ru, but act as 3+ acceptors; the extra eg electron occupies the in-plane 3dx2-y2 orbital instead of the expected out-of-plane 3d3z2-r2. We propose that the 3d-4d interplay, via the ligand oxygen orbitals, is responsible for this crystal-field level inversion and the material's transition to an antiferromagnetic, possibly orbitally ordered, low-temperature state.

  4. Significant association between parathyroid hormone and uric acid level in men

    PubMed Central

    Chin, Kok-Yong; Ima Nirwana, Soelaiman; Wan Ngah, Wan Zurinah

    2015-01-01

    Background Previous reports of patients undergoing parathyroidectomy and of patients receiving teriparatide as antiosteoporotic treatment have suggested a plausible relationship between parathyroid hormone (PTH) and uric acid. However, similar data at population level were lacking. The current study aimed to determine the relationship between PTH and uric acid in a group of apparently healthy Malaysian men. Methods A cross-sectional study was conducted among 380 Malay and Chinese men aged 20 years and above, residing in the Klang Valley, Malaysia. Their body anthropometry was measured, and their fasting blood samples were collected for biochemical analysis. The relationship between PTH and uric acid was analyzed using regression analysis. Results Increased serum PTH level was significantly associated with increased serum uric acid level (β=0.165; P=0.001). Increased PTH level was also significantly associated with the condition of hyperuricemia in the study population (odds ratio [OR], 1.045; 95% confidence interval [CI], 1.017–1.075; P=0.002). All analyses were adjusted for age, body mass index, vitamin D, total calcium, inorganic phosphate, blood urea nitrogen and creatinine levels. Conclusion There is a significant positive relationship between PTH level and uric acid level in Malaysian men. This relationship and its clinical significance should be further investigated in a larger longitudinal study. PMID:26346636

  5. Comparative Indole-3-Acetic Acid Levels in the Slender Pea and Other Pea Phenotypes 1

    PubMed Central

    Law, David M.; Davies, Peter J.

    1990-01-01

    Free indole-3-acetic acid levels were measured by gas chromatography-mass spectrometry in three ultra-tall `slender' Pisum sativum L. lines differing in gibberellin content. Measurements were made for apices and stem elongation zones of light-grown plants and values were compared with wild-type, dwarf, and nana phenotypes in which internode length is genetically regulated, purportedly via the gibberellin level. Indole-3-acetic acid levels of growing stems paralleled growth rates in all lines, and were high in all three slender genotypes. Growth was inhibited by p-chlorophenoxyisobutyric acid, demonstrating the requirement of auxin activity for stem elongation, and also by the ethylene precursor 1-aminocyclopropane-1-carboxylic acid. It is concluded that the slender phenotype may arise from constant activation of a gibberellin receptor or transduction chain event leading directly or indirectly to elevated levels of indole-3-acetic acid, and that increased indole-3-acetic acid levels are a significant factor in the promotion of stem elongation. PMID:16667653

  6. Detection and Monitoring of Toxic Chemical at Ultra Trace Level by Utilizing Doped Nanomaterial

    PubMed Central

    Khan, Sher Bahadar; Rahman, Mohammed M.; Akhtar, Kalsoom; Asiri, Abdullah M.

    2014-01-01

    Composite nanoparticles were synthesized by eco-friendly hydrothermal process and characterized by different spectroscopic techniques. All the spectroscopic techniques suggested the synthesis of well crystalline optically active composite nanoparticles with average diameter of ∼30 nm. The synthesized nanoparticles were applied for the development of chemical sensor which was fabricated by coating the nanoparticles on silver electrode for the recognition of phthalimide using simple I–V technique. The developed sensor exhibited high sensitivity (1.7361 µA.mM−1.cm−2), lower detection limit (8.0 µM) and long range of detection (77.0 µM to 0.38 M). Further the resistances of composite nanoparticles based sensor was found to be 2.7 MΩ which change from 2.7 to 1.7 with change in phthalimide concentration. The major advantages of the designed sensor over existing sensors are its simple technique, low cost, lower detection limit, high sensitivity and long range of detection. It can detect phthalimide even at trace level and sense over wide range of concentrations. Therefore the composite nanoparticals would be a better choice for the fabrication of phthalimide chemical sensor and would be time and cost substituted implement for environmental safety. PMID:25329666

  7. Prednisone lowers serum uric acid levels in patients with decompensated heart failure by increasing renal uric acid clearance.

    PubMed

    Liu, Chao; Zhen, Yuzhi; Zhao, Qingzhen; Zhai, Jian-Long; Liu, Kunshen; Zhang, Jian-Xin

    2016-07-01

    Clinical studies have shown that large doses of prednisone could lower serum uric acid (SUA) in patients with decompensated heart failure (HF); however, the optimal dose of prednisone and underlying mechanisms are unknown. Thirty-eight patients with decompensated HF were randomized to receive standard HF care alone (n = 10) or with low-dose (15 mg/day, n = 8), medium-dose (30 mg/day, n = 10), or high-dose prednisone (60 mg/day, n = 10), for 10 days. At the end of the study, only high-dose prednisone significantly reduced SUA, whereas low- and medium-dose prednisone and standard HF care had no effect on SUA. The reduction in SUA in high-dose prednisone groups was associated with a significant increase in renal uric acid clearance. In conclusion, prednisone can reduce SUA levels by increasing renal uric acid clearance in patients with decompensated HF. PMID:27144905

  8. Fermi level pinning characterisation on ammonium fluoride-treated surfaces of silicon by energy-filtered doping contrast in the scanning electron microscope.

    PubMed

    Chee, Augustus K W

    2016-01-01

    Two-dimensional dopant profiling using the secondary electron (SE) signal in the scanning electron microscope (SEM) is a technique gaining impulse for its ability to enable rapid and contactless low-cost diagnostics for integrated device manufacturing. The basis is doping contrast from electrical p-n junctions, which can be influenced by wet-chemical processing methods typically adopted in ULSI technology. This paper describes the results of doping contrast studies by energy-filtering in the SEM from silicon p-n junction specimens that were etched in ammonium fluoride solution. Experimental SE micro-spectroscopy and numerical simulations indicate that Fermi level pinning occurred on the surface of the treated-specimen, and that the doping contrast can be explained in terms of the ionisation energy integral for SEs, which is a function of the dopant concentration, and surface band-bending effects that prevail in the mechanism for doping contrast as patch fields from the specimen are suppressed. PMID:27576347

  9. Fermi level pinning characterisation on ammonium fluoride-treated surfaces of silicon by energy-filtered doping contrast in the scanning electron microscope

    PubMed Central

    Chee, Augustus K. W.

    2016-01-01

    Two-dimensional dopant profiling using the secondary electron (SE) signal in the scanning electron microscope (SEM) is a technique gaining impulse for its ability to enable rapid and contactless low-cost diagnostics for integrated device manufacturing. The basis is doping contrast from electrical p-n junctions, which can be influenced by wet-chemical processing methods typically adopted in ULSI technology. This paper describes the results of doping contrast studies by energy-filtering in the SEM from silicon p-n junction specimens that were etched in ammonium fluoride solution. Experimental SE micro-spectroscopy and numerical simulations indicate that Fermi level pinning occurred on the surface of the treated-specimen, and that the doping contrast can be explained in terms of the ionisation energy integral for SEs, which is a function of the dopant concentration, and surface band-bending effects that prevail in the mechanism for doping contrast as patch fields from the specimen are suppressed. PMID:27576347

  10. Phosphoric acid distribution and its impact on the performance of polybenzimidazole membranes

    NASA Astrophysics Data System (ADS)

    Mack, Florian; Heissler, Stefan; Laukenmann, Ruben; Zeis, Roswitha

    2014-12-01

    Phosphoric acid doped polybenzimidazole (PBI) is the most common membrane material for high-temperature polymer electrolyte membrane fuel cells (HT-PEMFC). The PBI membrane is usually doped by immersion in hot phosphoric acid. Immersion time and acid temperature affect the doping level of the membrane. In this work we studied the influence of doping time and temperature on the ex-situ and in-situ proton conductivities of poly (2, 5-benzimidazole) (AB-PBI) membranes as well as the fuel cell performance. Confocal Raman microscopy was employed to spatially resolve the acid distribution within the AB-PBI membranes. Therefore the interactions between the basic nitrogen-sides of the AB-PBI polymer and the phosphoric acid protons were investigated. We found that membranes with a 6 h doping time had significantly higher proton conductivity than those doped for only 3 h. In terms of absolute acid up-take, however, the difference was rather small. This result shows that the doping level alone does not define the conductivity of the membrane. The conductivity is also influenced by the micro acid distribution within the membrane. Highest membrane conductivity and fuel cell performance with fumapem AM cross-linked membranes were achieved with a doping time of 6 h and a doping temperature of 120 °C.

  11. Regulation of Invertase Levels in Avena Stem Segments by Gibberellic Acid, Sucrose, Glucose, and Fructose 1

    PubMed Central

    Kaufman, Peter B.; Ghosheh, Najati S.; Lacroix, J. Donald; Soni, Sarvjit L.; Ikuma, Hiroshi

    1973-01-01

    Gibberellic acid and sucrose play significant roles in the increases in invertase and growth in Avena stem segments. About 80% of invertase is readily solubilized, whereas the rest is in the cell wall fraction. The levels of both types of invertase change in a similar manner in the response to gibberellic acid and sucrose treatment. The work described here was carried out with only the soluble enzyme. In response to a treatment, the level of invertase activity typically follows a pattern of increase followed by decrease; the increase in activity is approximately correlated with the active growth phase, whereas the decrease in activity is initiated when growth of the segments slows. A continuous supply of gibberellic acid retards the decline of enzyme activity. When gibberellic acid was pulsed to the segments treated with or without sucrose, the level of invertase activity increased at least twice as high in the presence of sucrose as in its absence, but the lag period is longer with sucrose present. Cycloheximide treatments effectively abolish the gibberellic acid-promoted growth, and the level of enzyme activity drops rapidly. Decay of invertase activity in response to cycloheximide treatment occurs regardless of gibberellic acid or sucrose treatment or both, and it is generally faster when the inhibitor is administered at the peak of enzyme induction than when given at its rising phase. Pulses with sucrose, glucose, fructose, or glucose + fructose elevate the level of invertase significantly with a lag of about 5 to 10 hours. The increase in invertase activity elicited by a sucrose pulse is about one-third that caused by a gibberellic acid pulse given at a comparable time during mid-phase of enzyme induction, and the lag before the enzyme activity increases is nearly twice as long for sucrose as for gibberellic acid. Moreover, the gibberellic acid pulse results in about three times more growth than the sucrose pulse. Our studies support the view that gibberellic

  12. Effect of doping of calcium fluoride nanoparticles on the photoluminescence properties of europium complexes with benzoic acid derivatives as secondary ligands and 2-aminopyridine as primary ligand

    NASA Astrophysics Data System (ADS)

    Sharma, Garima; Narula, Anudeep Kumar

    2015-08-01

    The present article reports the synthesis of three Eu(III) complexes [Eu(BA)3(2-ap)] (1), [Eu(HBA)3(2-ap)] (2) and [Eu(ABA)3(2-ap)] (3) (BA = benzoic acid, HBA = 2-hydroxy benzoic acid, ABA = 2-amino benzoic acid and 2-ap = 2-aminopyridine) carried out in ethanol solution. The complexes were further doped with CaF2 nanoparticles and a change in the photoluminescence properties was observed. The compositions and structural investigation of the complexes were determined by elemental analysis and Fourier transform infrared spectroscopy (FTIR) which suggest the coordination of ligands with the central Eu(III) ion. The optical properties of the complexes were studied by Ultraviolet Visible absorption spectroscopy (UV-Vis) and photoluminescence studies (PL). The relative PL intensity was enhanced in the Eu(III) complexes doped with CaF2 nanoparticles as compared to the pure Eu(III) complexes, however the increase in intensity varied in the order of ligands ABA > HBA > BA. The photoluminescence lifetime decay curves also revealed the longer lifetime (τ) and higher quantum efficiency (η) for europium complexes with ABA ligands suggesting the efficient energy transfer and better sensitizing ability of the ligand to europium ion. The morphology of the synthesized compounds were studied by Scanning Electron Microscopy (SEM) revealing spherical morphology with agglomeration of the nanoparticles.

  13. Two Levels of Caffeine Ingestion on Blood Lactate and Free Fatty Acid Responses during Incremental Exercise.

    ERIC Educational Resources Information Center

    McNaughton, Lars

    1987-01-01

    Research was conducted to determine the effects of two doses of caffeine on the lactate threshold and also to examine the effects on substrate utilization during incremental cycle ergometry. Results found that caffeine increased heart rates and free fatty acid levels for all workloads and decreased blood lactate levels at some of the workloads.…

  14. Serum homocysteine, vitamin B12, folic acid levels and methylenetetrahydrofolate reductase (MTHFR) gene polymorphism in vitiligo.

    PubMed

    Yasar, Ali; Gunduz, Kamer; Onur, Ece; Calkan, Mehmet

    2012-01-01

    The aim of this study was to determine serum vitamin B12, folic acid and homocysteine (Hcy) levels as well as MTHFR (C677, A1298C) gene polymorphisms in patients with vitiligo, and to compare the results with healthy controls. Forty patients with vitiligo and 40 age and sex matched healthy subjects were studied. Serum vitamin B12 and folate levels were determined by enzyme-linked immunosorbent assay. Plasma Hcy levels and MTHFR polymorphisms were determined by chemiluminescence and real time PCR methods, respectively. Mean serum vitamin B12 and Hcy levels were not significantly different while folic acid levels were significantly lower in the control group. There was no significant relationship between disease activity and vitamin B12, folic acid and homocystein levels. No significant difference in C677T gene polymorphism was detected. Heterozygote A1298C gene polymorphism in the patient group was statistically higher than the control group. There was no significant relationship between MTHFR gene polymorphisms and vitamin B12, folic acid and homocysteine levels. In conclusion, vitamin B12, folate and Hcy levels are not altered in vitiligo and MTHFR gene mutations (C677T and A1298C) do not seem to create susceptibility for vitiligo. PMID:22846211

  15. Glycodeoxycholic Acid Levels as Prognostic Biomarker in Acetaminophen-Induced Acute Liver Failure Patients

    PubMed Central

    Woolbright, Benjamin L.; McGill, Mitchell R.; Staggs, Vincent S.; Winefield, Robert D.; Gholami, Parviz; Olyaee, Mojtaba; Sharpe, Matthew R.; Curry, Steven C.; Lee, William M.; Jaeschke, Hartmut

    2014-01-01

    Acetaminophen (APAP)-induced acute liver failure (ALF) remains a major clinical problem. Although a majority of patients recovers after severe liver injury, a subpopulation of patients proceeds to ALF. Bile acids are generated in the liver and accumulate in blood during liver injury, and as such, have been proposed as biomarkers for liver injury and dysfunction. The goal of this study was to determine whether individual bile acid levels could determine outcome in patients with APAP-induced ALF (AALF). Serum bile acid levels were measured in AALF patients using mass spectrometry. Bile acid levels were elevated 5–80-fold above control values in injured patients on day 1 after the overdose and decreased over the course of hospital stay. Interestingly, glycodeoxycholic acid (GDCA) was significantly increased in non-surviving AALF patients compared with survivors. GDCA values obtained at peak alanine aminotransferase (ALT) and from day 1 of admission indicated GDCA could predict survival in these patients by receiver-operating characteristic analysis (AUC = 0.70 for day 1, AUC = 0.68 for peak ALT). Of note, AALF patients also had significantly higher levels of serum bile acids than patients with active cholestatic liver injury. These data suggest measurements of GDCA in this patient cohort modestly predicted outcome and may serve as a prognostic biomarker. Furthermore, accumulation of bile acids in serum or plasma may be a result of liver cell dysfunction and not cholestasis, suggesting elevation of circulating bile acid levels may be a consequence and not a cause of liver injury. PMID:25239633

  16. Evaluation of serum sialic acid, fucose levels and their ratio in oral squamous cell carcinoma

    PubMed Central

    Chinnannavar, Sangamesh Ningappa; Ashok, Lingappa; Vidya, Kodige Chandrashekhar; Setty, Sunil Mysore Kantharaja; Narasimha, Guru Eraiah; Garg, Ranjana

    2015-01-01

    Background: Detection of cancer at the early stage is of utmost importance to decrease the morbidity and mortality of the disease. Apart from the conventional biopsy, minimally invasive methods like serum evaluation are used for screening large populations. Thus, this study aimed to estimate serum levels of sialic acid and fucose and their ratio in oral cancer patients and in healthy control group to evaluate their role in diagnosis. Materials and Methods: Serum samples were collected from 52 healthy controls (group I) and 52 squamous cell carcinoma patients (group II). Estimation of serum levels of sialic acid and fucose and their ratio was performed. This was correlated histopathologically with the grades of carcinoma. Statistical analysis was done by using analysis of variance (ANOVA) test and unpaired “t” test. Results: Results showed that serum levels of sialic acid and fucose were significantly higher in oral cancer patients compared to normal healthy controls (P < 0.001). The sialic acid to fucose ratio was significantly lower in cancer patients than in normal controls (P < 0.01). However, comparison with histological grading, habits, gender, and age group did not show any significant result. Conclusion: The mean serum sialic acid and fucose levels showed an increasing trend from controls to malignant group and their corresponding ratio showed decreasing trend from controls to malignant group. The ratio of sialic acid to fucose can be a useful diagnostic aid for oral cancer patients. PMID:26759796

  17. Evaluation of the {sup 4}I{sub 11/2} terminal level lifetime for several neodymium-doped laser crystals and glasses

    SciTech Connect

    Bibeau, C.

    1995-04-25

    All models of lasing action require knowledge of the physical parameters involved, of which many can be measured or estimated. The value of the terminal level lifetime is an important parameter in modeling many high power laser systems since the terminal level lifetime can have a substantial impact on the extraction efficiency of the system. However, the values of the terminal level lifetimes for a number of important laser materials such as ND:YAG and ND:YLF are not well known. The terminal level lifetime, a measure of the time it takes for the population to drain out of the terminal (lower) lasing level, has values that can range from picoseconds to microseconds depending on the host medium, thus making it difficult to construct one definitive experiment for all materials. Until recently, many of the direct measurements of the terminal level lifetime employed complex energy extraction or gain recovery methods coupled with a numerical model which often resulted in large uncertainties in the measured lifetimes. In this report we demonstrate a novel and more accurate approach which employs a pump-probe technique to measure the terminal level lifetime of 16 neodymium-doped materials. An alternative yet indirect method, which is based on the ``Energy Gap Law,`` is to measure the nonradiative lifetime of another transition which has the same energy gap as the transition of the terminal level lifetime. Employing this simpler approach, we measured the lifetime for 30 neodymium-doped materials. We show for the first time a direct comparison between the two methods and determine that the indirect method can be used to infer the terminal level lifetime within a factor of two for most neodymium-doped glasses and crystals.

  18. Structural and optical study of spin-coated camphorsulfonic acid-doped polyaniline/titanium-di-oxide nanoparticles hybrid thin films

    NASA Astrophysics Data System (ADS)

    Geethalakshmi, D.; Muthukumarasamy, N.; Balasundaraprabhu, R.

    2015-06-01

    Polyaniline (PANI) doped with Camphorsulfonic acid (CSA) has been prepared by chemical oxidative polymerization and blend with titanium-di-oxide (TiO2) nanoparticles prepared by sol-gel method to form CSA-doped PANI/TiO2 hybrid thin films. The properties of as-deposited and heat-treated (100 °C) hybrid thin films having different PANI:TiO2 weight ratios (1:0.5, 1:1, and 1:2) have been compared. FTIR study indicated that chemical bonding between CSA-doped PANI and TiO2 has been formed. XRD studies reveal that the as-deposited hybrid thin films are of amorphous nature and heat-treatment of such films initiates crystallization. SEM study shows that as-deposited hybrid films are rough; increase in TiO2 ratio and heat-treatment increased the roughness due to coalescing and agglomeration. UV-visible absorbance of hybrid films shows its characteristic peak in the visible region along with a peak in UV range and its intensity increased with TiO2 ratio and heat-treatment due to agglomeration of TiO2 particles. Photoluminescence spectra revealed that emission occurs in visible region (495 nm) for as-deposited hybrid thin film and this emission increased with TiO2 ratio and heat-treatment of hybrid films.

  19. Layered Lithium-Rich Oxide Nanoparticles Doped with Spinel Phase: Acidic Sucrose-Assistant Synthesis and Excellent Performance as Cathode of Lithium Ion Battery.

    PubMed

    Chen, Min; Chen, Dongrui; Liao, Youhao; Zhong, Xiaoxin; Li, Weishan; Zhang, Yuegang

    2016-02-01

    Nanolayered lithium-rich oxide doped with spinel phase is synthesized by acidic sucrose-assistant sol-gel combustion and evaluated as the cathode of a high-energy-density lithium ion battery. Physical characterizations indicate that the as-synthesized oxide (LR-SN) is composed of uniform and separated nanoparticles of about 200 nm, which are doped with about 7% spinel phase, compared to the large aggregated ones of the product (LR) synthesized under the same condition but without any assistance. Charge/discharge demonstrates that LR-SN exhibits excellent rate capability and cyclic stability: delivering an average discharge capacity of 246 mAh g(-1) at 0.2 C (1C = 250 mA g(-1)) and earning a capacity retention of 92% after 100 cycles at 4 C in the lithium anode-based half cell, compared to the 227 mA g(-1) and the 63% of LR, respectively. Even in the graphite anode-based full cell, LR-SN still delivers a capacity of as high as 253 mAh g(-1) at 0.1 C, corresponding to a specific energy density of 801 Wh kg(-1), which are the best among those that have been reported in the literature. The separated nanoparticles of the LR-SN provide large sites for charge transfer, while the spinel phase doped in the nanoparticles facilitates lithium ion diffusion and maintains the stability of the layered structure during cycling. PMID:26799282

  20. Childrens' learning and behaviour and the association with cheek cell polyunsaturated fatty acid levels.

    PubMed

    Kirby, A; Woodward, A; Jackson, S; Wang, Y; Crawford, M A

    2010-01-01

    Increasing interest in the role of omega-3 fatty acids in relation to neurodevelopmental disorders (e.g. ADHD, dyslexia, autism) has occurred as a consequence of some international studies highlighting this link. In particular, some studies have shown that children with ADHD may have lower concentrations of polyunsaturated fatty acids (PUFAs), particularly omega-3, in their red blood cells and plasma, and that supplementation with omega-3 fatty acids may alleviate behavioural symptoms in this population. However, in order to compare levels it seems appropriate to establish fatty acid levels in a mainstream school aged population and if levels relate to learning and behaviour. To date no study has established this. For this study, cheek cell samples from 411 typically developing school children were collected and analysed for PUFA content, in order to establish the range in this population. In addition, measures of general classroom attention and behaviour were assessed in these children by teachers and parents. Cognitive performance tests were also administered in order to explore whether an association between behaviour and/or cognitive performance and PUFA levels exists. Relationships between PUFA levels and socio-economic status were also explored. Measures of reading, spelling and intelligence did not show any association with PUFA levels, but some associations were noted with the level of omega-3 fatty acids and teacher and parental reports of behaviour, with some evidence that higher omega-3 levels were associated with decreased levels of inattention, hyperactivity, emotional and conduct difficulties and increased levels of prosocial behaviour. These findings are discussed in relation to previous findings from omega-3 supplementation studies with children. PMID:20172688

  1. Complete doping in solid-state by silica-supported perchloric acid as dopant solid acid: Synthesis and characterization of the novel chiral composite of poly [(±)-2-(sec-butyl) aniline

    NASA Astrophysics Data System (ADS)

    Farrokhzadeh, Abdolkarim; Modarresi-Alam, Ali Reza

    2016-05-01

    Poly [(±)-2-(sec-butyl) aniline]/silica-supported perchloric acid composites were synthesized by combination of poly[(±)-2-sec-butylaniline] base (PSBA) and the silica-supported perchloric acid (SSPA) as dopant solid acid in solid-state. The X-ray photoelectron spectroscopy (XPS) and CHNS results confirm nigraniline oxidation state and complete doping for composites (about 75%) and non-complete for the PSBA·HCl salt (about 49%). The conductivity of samples was (≈0.07 S/cm) in agreement with the percent of doping obtained of the XPS analysis. Also, contact resistance was determined by circular-TLM measurement. The morphology of samples by the scanning electron microscopy (SEM) and their coating were investigated by XPS, SEM-map and energy-dispersive X-ray spectroscopy (EDX). The key benefits of this work are the preparation of conductive chiral composite with the delocalized polaron structure under green chemistry and solid-state condition, the improvement of the processability by inclusion of the 2-sec-butyl group and the use of dopant solid acid (SSPA) as dopant.

  2. Plasma ascorbic acid level and erythrocyte fragility in preeclampsia and eclampsia.

    PubMed

    Ozan, H; Esmer, A; Kolsal, N; Copur, O U; Ediz, B

    1997-01-01

    An imbalance between oxidants and antioxidants in the circulation is blamed to cause preeclampsia and eclampsia. In this study plasma ascorbic acid level was analysed in 13 eclamptic, 14 mild preeclamptic, 12 severe preeclamptic and 20 uncomplicated pregnancies to see whether there is any correlation with blood pressure, proteinuria, serum triglyceride level, erythrocyte fragility and leukocyte count. Plasma ascorbic acid level was normal and had no significant difference among the groups. Fasting serum triglyceride level was significantly higher in the study group than in the control group but it did not differ among the three study groups. Erythrocyte fragility was found to be increased in all three study groups. Blood leukocyte count was increased in the study groups, especially in the eclampsia group. However, plasma ascorbic acid level and erythrocyte fragility were found to have no significant correlation with blood pressure and proteinuria. It was concluded that though the ascorbic acid levels were normal in both the study and the control groups, erythrocyte fragility increased probably due to an elevation in peroxide and free radical levels in preeclampsia and eclampsia groups, but without any correlation with the severity of the clinical picture. PMID:9031958

  3. Fecal levels of short-chain fatty acids and bile acids as determinants of colonic mucosal cell proliferation in humans.

    PubMed

    Dolara, Piero; Caderni, Giovanna; Salvadori, Maddalena; Morozzi, Guido; Fabiani, Roberto; Cresci, Alberto; Orpianesi, Carla; Trallori, Giacomo; Russo, Antonio; Palli, Domenico

    2002-01-01

    We studied the correlation between fecal levels of short-chain fatty acids (SCFA), bile acids (BA), and colonic mucosal proliferation in humans on a free diet. Subjects [n = 43: 27 men and 16 women; 61 +/- 7 and 59 +/- 6 (SE) yr old, respectively] were outpatients who previously underwent resection of at least two sporadic colon polyps. Mucosal proliferation was determined by [3H]thymidine incorporation in vitro in three colorectal biopsies obtained without cathartics and was expressed as labeling index (LI). BA were analyzed in feces by mass spectrometry and SCFA by gas chromatography. We found that increasing levels of BA in feces did not correlate with higher LI. On the contrary, higher levels of SCFA were significantly associated with lower LI in the colonic mucosa (P for trend = 0.02). In conclusion, in humans on a free diet, intestinal proliferation seems to be regulated by the levels of SCFA in feces and not by BA. Because a lower intestinal proliferation is associated with a decreased colon cancer risk, treatments or diets that increase colonic levels of SCFA might be beneficial for colonic mucosa. PMID:12416258

  4. Spectra, energy levels, and energy transition of lanthanide complexes with cinnamic acid and its derivatives.

    PubMed

    Zhou, Kaining; Feng, Zhongshan; Shen, Jun; Wu, Bing; Luo, Xiaobing; Jiang, Sha; Li, Li; Zhou, Xianju

    2016-04-01

    High resolution spectra and luminescent lifetimes of 6 europium(III)-cinnamic acid complex {[Eu2L6(DMF)(H2O)]·nDMF·H2O}m (L=cinnamic acid I, 4-methyl-cinnamic acid II, 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV, 4-hydroxy-cinnamic acid V, 4-nitro-cinnamic acid VI; DMF=N, N-dimethylformamide, C3H7NO) were recorded from 8 K to room temperature. The energy levels of Eu(3+) in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu(3+) ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p-π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I. While the other complexes show poorer matching because the gap of (5)D0 and triplet state contracts. PMID:26802538

  5. Spectra, energy levels, and energy transition of lanthanide complexes with cinnamic acid and its derivatives

    NASA Astrophysics Data System (ADS)

    Zhou, Kaining; Feng, Zhongshan; Shen, Jun; Wu, Bing; Luo, Xiaobing; Jiang, Sha; Li, Li; Zhou, Xianju

    2016-04-01

    High resolution spectra and luminescent lifetimes of 6 europium(III)-cinnamic acid complex {[Eu2L6(DMF)(H2O)]·nDMF·H2O}m (L = cinnamic acid I, 4-methyl-cinnamic acid II, 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV, 4-hydroxy-cinnamic acid V, 4-nitro-cinnamic acid VI; DMF = N, N-dimethylformamide, C3H7NO) were recorded from 8 K to room temperature. The energy levels of Eu3 + in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu3 + ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p-π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I. While the other complexes show poorer matching because the gap of 5D0 and triplet state contracts.

  6. Infantile Refsum Disease: Influence of Dietary Treatment on Plasma Phytanic Acid Levels.

    PubMed

    Sá, Maria João Nabais; Rocha, Júlio C; Almeida, Manuela F; Carmona, Carla; Martins, Esmeralda; Miranda, Vasco; Coutinho, Miguel; Ferreira, Rita; Pacheco, Sara; Laranjeira, Francisco; Ribeiro, Isaura; Fortuna, Ana Maria; Lacerda, Lúcia

    2016-01-01

    Infantile Refsum disease (IRD) is one of the less severe of Zellweger spectrum disorders (ZSDs), a group of peroxisomal biogenesis disorders resulting from a generalized peroxisomal function impairment. Increased plasma levels of very long chain fatty acids (VLCFA) and phytanic acid are biomarkers used in IRD diagnosis. Furthermore, an increased plasma level of phytanic acid is known to be associated with neurologic damage. Treatment of IRD is symptomatic and multidisciplinary.The authors report a 3-year-old child, born from consanguineous parents, who presented with developmental delay, retinitis pigmentosa, sensorineural deafness and craniofacial dysmorphisms. While the relative level of plasma C26:0 was slightly increased, other VLCFA were normal. Thus, a detailed characterization of the phenotype was essential to point to a ZSD. Repeatedly increased levels of plasma VLCFA, along with phytanic acid and pristanic acid, deficient dihydroxyacetone phosphate acyltransferase activity in fibroblasts and identification of the homozygous pathogenic mutation c.2528G>A (p.Gly843Asp) in the PEX1 gene, confirmed this diagnosis. Nutritional advice and follow-up was proposed aiming phytanic acid dietary intake reduction. During dietary treatment, plasma levels of phytanic acid decreased to normal, and the patient's development evaluation showed slow progressive acquisition of new competences.This case report highlights the relevance of considering a ZSD in any child with developmental delay who manifests hearing and visual impairment and of performing a systematic biochemical investigation, when plasma VLCFA are mildly increased. During dietary intervention, a biochemical improvement was observed, and the long-term clinical effect of this approach needs to be evaluated. PMID:26303611

  7. Heterogeneous interaction of carboxylic acids with pure ice and HNO3-doped ice surfaces at upper tropospheric/lower stratospheric temperatures

    NASA Astrophysics Data System (ADS)

    Papagiannakopoulos, P.; Pettersson, J. B. C.; Papadimitriou, V. C.; Romanias, M. N.

    2012-04-01

    The heterogeneous interaction of atmospheric trace gases with ice surfaces plays an important role in the chemistry of the upper troposphere and lower stratosphere (UT/LS) region. In particular, the uptakes of carboxylic acids, such as formic (HC(O)OH), acetic (CH3C(O)OH), propionic (CH3CH2C(O)OH), and butyric (CH3CH2CH2C(O)OH) acids, on pure ice or HNO3-doped ice particles in dense cirrus clouds or polar stratospheric clouds may be significant in removing these acids from the UT/LS. The aim of the present study was to investigate the adsorption of gaseous carboxylic acids on thin ice and HNO3-doped ice films over the temperature range 195-208 K and at low gaseous pressures, using a Knudsen flow reactor combined with a quadrupole mass spectrometer. The initial uptake coefficients, γo, were measured as a function of temperature and at low surface coverage; the inverse temperature dependence of γo indicates that the uptake proceeds via the formation of an intermediate precursor state. The uptakes of formic and acetic acids were well represented by Langmuir adsorption model, and the temperature independent saturation surface coverage, Nmax, on pure ice films were (2.94 ± 0.67)×1014 molecule cm-2, and (2.11 ± 0.16)×1014 molecule cm-2, respectively; in excellent agreement with coated-wall laminar flow tube (CWLFT) technique values. Light nitration (1.96 and 7.69 wt%) of ice films resulted in more efficient uptakes and larger Nmax values that may be attributed to in-bulk diffusion or change in nature of gas-ice surface interaction. The uptake profiles of propionic and butyric acids on pure ice and HNO3-doped ice films over the temperature range 195-206 K were unsaturated, which indicated high solubility and rapid diffusion of these acids into the ice bulk. The kinetics of these uptakes γ(t) were very well represented by the diffusion non-dissociating resistor model, and H*d(D)1/2 values were independent of concentration and in the range 1 to 20 m s-1/2; H*d is the

  8. Dietary alpha-linolenic acid increases brain but not heart and liver docosahexaenoic acid levels.

    PubMed

    Barceló-Coblijn, Gwendolyn; Collison, Lauren W; Jolly, Christopher A; Murphy, Eric J

    2005-08-01

    Fish oil-enriched diets increase n-3 FA in tissue phospholipids; however, a similar effect by plant-derived n-3 FA is poorly defined. To address this question, we determined mass changes in phospholipid FA, individual phospholipid classes, and cholesterol in the liver, heart, and brain of rats fed diets enriched in flax oil (rich in 18:3n-3), fish oil (rich in 22:6n-3 and 20:5n-3), or safflower oil (rich in 18:2n-6) for 8 wk. In the heart and liver phospholipids, 22:6n-3 levels increased only in the fish oil group, although rats fed flax oil accumulated 20:5n-3 and 22:5n-3. However, in the brain, the flax and fish oil diets increased the phospholipid 22:6n-3 mass. In all tissues, these diets decreased the 20:4n-6 mass, although the effect was more marked in the fish oil than in the flax oil group. Although these data do not provide direct evidence for 18:3n-3 elongation and desaturation by the brain, they demonstrate that 18:3n-3-enriched diets reduced tissue 20:4n-6 levels and increased cellular n-3 levels in a tissue-dependent manner. We hypothesize, based on the lack of increased 22:6n-3 but increased 18:3n-3 in the liver and heart, that the flax oil diet increased circulating 18:3n-3, thereby presenting tissue with this EFA for further elongation and desaturation. PMID:16296397

  9. Plasma levels of acetylsalicylic acid and salicylic acid after oral ingestion of plain and buffered acetylsalicylic acid in relation to bleeding time and thrombocyte function.

    PubMed

    Proost, J H; Van Imhoff, G W; Wesseling, H

    1983-02-25

    Buffered acetylsalicylic acid (Alka Seltzer, B-ASA) and plain aspirin (P-ASA) tablets were compared as to their effects on bleeding time and platelet function in eight healthy male volunteers. Two doses (500 and 1000 mg) of each preparation were investigated in a cross-over design, each volunteer being his own control in each dose group (n=4). Both preparations disturbed platelet aggregation to the same extent. Bleeding time increased after both preparations, though significantly more after the buffered preparation than after plain acetylsalicylic acid, irrespective of the dosage. The 1000 mg dose prolonged bleeding time significantly more than the 500 mg dose, irrespective of the preparation. Kinetic analysis showed that B-ASA gave higher peak plasma levels of acetylsalicylic acid (ASA) and accordingly salicylic acid peak levels were also higher after the buffered preparation. It is concluded that B-ASA in equi-analgesic doses prolongs bleeding time more than the plain preparation. Since it is less agressive on the gastro-intestinal mucosa, its use may be advantageous in situations where acetylsalicylic acid induced loss of platelet aggregation is desired. However, the risk of prolonged bleeding--e.g. after tooth extractions--is probably higher after the buffered preparation. PMID:6844122

  10. Total and free valproic acid: plasma level/dose ratio in monotherapy.

    PubMed

    Abadín, J A; Durán, J A; Sánchez, A; Serrano, J S

    1991-04-01

    Free plasma level/dose ratio of valproic acid (L/D-F) can be more effective than total plasma level/dose ratio (L/D-T) in adjusting dosage regimens. The influence of age, dose, and plasma concentration have been studied on L/D-T and L/D-F ratios. L/D-T and L/D-F ratios from 67 outpatients under long-term monotherapy were obtained. Analytical data was carried out by fluorescent polarized immunoassay. L/D-T and L/D-F ratios do not vary according to age. L/D-T and L/D-F ratios decreased while the dosage increased; both ratios increased with an increase in total plasma level of valproic acid. Significant differences were found between L/D-T and L/D-F ratios. Dose and interindividual variations are the factors which most influence L/D ratios of valproic acid. PMID:2051846

  11. Alterations in the levels of plasma amino acids in polycystic ovary syndrome- A pilot study

    PubMed Central

    Unni, C. Sumithra N.; Lakshman, Lakshmi R.; Vaidyanathan, Kannan; Subhakumari, K.N.; Menon, N. Leela

    2015-01-01

    Background & objectives: Plasma amino acid levels are known to be altered in conditions like sepsis and burns which are situations of metabolic stress. Polycystic ovary syndrome (PCOS), a condition which affects a woman throughout her life, is said to be associated with metabolic stress. This study was undertaken to assess if there were significant alterations in the levels of plasma amino acids in women with PCOS. Methods: Sixty five women with PCOS along with the similar number of age matched normal controls were included in this study. Levels of 14 amino acids were determined using reverse phase high performance liquid chromatography. Results: The levels of methionine, cystine, isoleucine, phenylalanine, valine, tyrosine, proline, glycine, lysine and histidine were found to be significantly (P<0.001) lower in cases than in controls. Arginine and alanine levels were found to be significantly (P<0.001) higher in cases compared with controls. Interpretation & conclusions: Our findings showed significant derangement in the levels of plasma amino acids in women with PCOS which might be due to the oxidative and metabolic stress associated with it. Further studies need to be done to confirm the findings. PMID:26658589

  12. The relationship between low leucocyte ascorbic-acid levels and tyrosine metabolism in the elderly.

    PubMed

    Windsor, A C; Hobbs, C B; Treby, D A; Gupta, C B

    1975-11-01

    Twenty-seven elderly men aged 69-94 years had tyrosine tolerance tests measured before and after receiving ascorbic acid 1 g daily for four days. There was a significant rise in the fasting and half-hourly mean plasma tyrosine levels after ascorbic acid administration in those subjects with an initial leucocyte ascorbic-acid level (LAA) below 15 micrograms/10(8) w.c.c. The peak of the tyrosine tolerance curve was also advanced following administration of ascorbic acid in those subjects with an initial LAA below 15 micrograms/10(8) w.c.c. A further ten elderly men aged 73-89 years had simultaneous measurements of the circadian rhythms of LAA, plasma cortisol and plasma tyrosine levels before and after receiving ascorbic acid 1 g daily for four days. All ten subjects showed a peak LAA level at 5 p.m. when saturated with vitamin C but there was no significant correlation between plasma cortisol changes and plasma tyrosine changes. Possible explanations for the results are discussed. PMID:803133

  13. Acute ischemic non-embolic stroke and serum level of uric acid

    PubMed Central

    Sheykholeslami, Nazanin Zia; Gadari, Faranak; Ahmady, Jafar

    2012-01-01

    Background Impact of high level of uric acid on stroke is still controversial. We conducted this study to investigate the relationship between acute ischemic non-embolic stroke and serum levels of uric acid. Methods This was a case-control study on patients with acute ischemic non-embolic stroke in Rafsanjan, Iran. The control group consisted of normal persons who were similar to the case group in terms of age and gender. Serum level of uric acid in the first 24 hours of admission was measured with photometry method. Results In a total of 130 patients (59 mens), hyperuricemia was seen in 13.0% of subjects in the control group and 10.7% of subjects in the case group. Nine patients in case group and 7 patients in control group with hyperuricemia were women. No significant relationship was found between acute ischemic non-embolic stroke and serum level of uric acid. Conclusion There was no relationship between uric acid and acute ischemic non-embolic stroke. PMID:24250850

  14. Serum phytanic and pristanic acid levels and prostate cancer risk in Finnish smokers.

    PubMed

    Wright, Margaret E; Albanes, Demetrius; Moser, Ann B; Weinstein, Stephanie J; Snyder, Kirk; Männistö, Satu; Gann, Peter H

    2014-12-01

    Phytanic acid is a saturated branched-chain fatty acid found predominantly in red meat and dairy products, and may contribute to the elevated risks of prostate cancer associated with higher consumption of these foods. Pristanic acid is formed during peroxisomal oxidation of phytanic acid, and is the direct substrate of α-Methyl-CoA-Racemase (AMACR)--an enzyme that is consistently overexpressed in prostate tumors relative to benign tissue. We measured phytanic and pristanic acids as percentages of total fatty acids by gas chromatography-mass spectrometry in prediagnostic blood samples from 300 prostate cancer cases and 300 matched controls, all of whom were participants in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study supplementation trial and follow-up cohort. In addition to providing a fasting blood sample at baseline, all men completed extensive diet, lifestyle, and medical history questionnaires. Among controls, the strongest dietary correlates of serum phytanic and pristanic acids were saturated fat, dairy fat, and butter (r = 0.50 and 0.40, 0.46 and 0.38, and 0.40 and 0.37, respectively; all P-values <0.001). There was no association between serum phytanic acid and risk of total or aggressive prostate cancer in multivariate logistic regression models (for increasing quartiles, odds ratios (OR) and 95% confidence intervals (CI) for aggressive cancer were 1.0 (referent), 1.62 (0.97-2.68), 1.12 (0.66-1.90), and 1.14 (0.67-1.94), P(trend) = 0.87). Pristanic acid was strongly correlated with phytanic acid levels (r = 0.73, P < 0.0001), and was similarly unrelated to prostate cancer risk. Significant interactions between phytanic and pristanic acids and baseline circulating β-carotene concentrations were noted in relation to total and aggressive disease among participants who did not receive β-carotene supplements as part of the original ATBC intervention trial. In summary, we observed no overall association between serum phytanic and

  15. Serum phytanic and pristanic acid levels and prostate cancer risk in Finnish smokers

    PubMed Central

    Wright, Margaret E; Albanes, Demetrius; Moser, Ann B; Weinstein, Stephanie J; Snyder, Kirk; Männistö, Satu; Gann, Peter H

    2014-01-01

    Phytanic acid is a saturated branched-chain fatty acid found predominantly in red meat and dairy products, and may contribute to the elevated risks of prostate cancer associated with higher consumption of these foods. Pristanic acid is formed during peroxisomal oxidation of phytanic acid, and is the direct substrate of α-Methyl-CoA-Racemase (AMACR)—an enzyme that is consistently overexpressed in prostate tumors relative to benign tissue. We measured phytanic and pristanic acids as percentages of total fatty acids by gas chromatography-mass spectrometry in prediagnostic blood samples from 300 prostate cancer cases and 300 matched controls, all of whom were participants in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study supplementation trial and follow-up cohort. In addition to providing a fasting blood sample at baseline, all men completed extensive diet, lifestyle, and medical history questionnaires. Among controls, the strongest dietary correlates of serum phytanic and pristanic acids were saturated fat, dairy fat, and butter (r = 0.50 and 0.40, 0.46 and 0.38, and 0.40 and 0.37, respectively; all P-values <0.001). There was no association between serum phytanic acid and risk of total or aggressive prostate cancer in multivariate logistic regression models (for increasing quartiles, odds ratios (OR) and 95% confidence intervals (CI) for aggressive cancer were 1.0 (referent), 1.62 (0.97–2.68), 1.12 (0.66–1.90), and 1.14 (0.67–1.94), Ptrend = 0.87). Pristanic acid was strongly correlated with phytanic acid levels (r = 0.73, P < 0.0001), and was similarly unrelated to prostate cancer risk. Significant interactions between phytanic and pristanic acids and baseline circulating β-carotene concentrations were noted in relation to total and aggressive disease among participants who did not receive β-carotene supplements as part of the original ATBC intervention trial. In summary, we observed no overall association between serum phytanic and

  16. Regulation of plasma lipoprotein levels by dietary triglycerides enriched with different fatty acids.

    PubMed

    Nicolosi, R J; Rogers, E J

    1997-11-01

    Saturated vegetable oils (coconut, palm, and palm kernel oil) containing predominantly saturated fatty acids, lauric (12:0) or myristic (14:0 and palmitic (16:0), raise plasma total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) levels in animals and humans, presumably by decreasing LDL receptor activity and/or increasing LDL-C production rate. Although stearic acid (18:0) is chemically a saturated fatty acid, both human and animal studies suggest it is biologically neutral (neither raising nor lowering) blood cholesterol levels. Although earlier studies indicated that medium chain fatty acids (8:0-10:0) were also thought to be neutral, more recent studies in animals and humans suggest otherwise. Unsaturated vegetable oils such as corn, soybean, olive, and canola oil, by virtue of their predominant levels of either linoleic acid (18:2) or oleic acid (18:1), are hypocholesterolemic, probably as a result of their ability to upregulate LDL receptor activity and/or decrease LDL-C production rate. Whether trans fatty acids such as trans oleate (t18:1), in hydrogenated products such as margarine, are hypercholesterolemic remains controversial. Studies in humans suggest that their cholesterol-raising potential falls between the native nonhydrogenated vegetable oil and the more saturated dairy products such as butter. Assessment of the magnitude of the cholesterolemic response of trans 18:1 is difficult because in most diet studies its addition is often at the expense of cholesterol-lowering unsaturated fatty acids, making an independent evaluation almost impossible. PMID:9372477

  17. Association of the folic acid consumption and its serum levels with preeclampsia in pregnant women

    PubMed Central

    Salehi-PourMehr, Hanieh; Mohamad-Alizadeh, Sakineh; Malakouti, Jamileh; Farshbaf-Khalili, Azizeh

    2012-01-01

    Background and Objectives: Preeclampsia is one of the main causes of maternal and fetal mortality. Despite numerous studies, its etiology is unknown. Recently there has been attention towards Folic acid. This study examined the association of Folic acid consumption and its serum levels with Preeclampsia. Materials and Methods: A case-control study conducted in Tabriz- Alzahra hospital. 52 preeclamptic women in 34-42 weeks and 52 normotensive pregnant women were studied from Jun to Nov 2009. Data was gathered through interview with the women and review of their medical records. Folic acid serum levels were measured by electrochemiluminescence method on Elecsys-2010 system using the Roche brand kit. Data were analyzed by t-test, chi-square, exact fisher and logistic regression. Results: 46% of women in the case group and 71% in the control group regularly consumed Folic acid supplements before and during the first trimester of pregnancy. Frequency of correct pattern of Folic acid consumption in the case group were significantly lower than control group (P = 0.02). Findings about frequency of main food groups’ consumption containing folic acid indicated that the only mean difference between two groups was in relation to fruits (P = 0.002). The mean of Folic Acid serum levels in preeclamptic group was significantly lower than non- preeclamptic group [10.9 (3.9) vs. 13.6 (4.0) ng/ml, P = 0.001]. Conclusion: it is recommended all health care providers educate clients especially high risk women about regular and timely consumption of supplements as well as food groups containing Folic acid specially fruits and its possible role in prevention of preeclampsia. PMID:23922590

  18. Dual Mode Fluorophore-Doped Nickel Nitrilotriacetic Acid-Modified Silica Nanoparticles Combine Histidine-Tagged Protein Purification with Site-Specific Fluorophore Labeling

    PubMed Central

    Kim, Sung Hoon; Jeyakumar, M.; Katzenellenbogen, John A.

    2008-01-01

    We present the first example of a fluorophore-doped nickel chelate surface- modified silica nanoparticle that functions in a dual mode, combining histidine-tagged protein purification with site-specific fluorophore labeling. Tetramethylrhodamine (TMR)-doped silica nanoparticles, estimated to contain 700–900 TMRs per ca. 23-nm particle, were surface modified with nitrilotriacetic acid (NTA), producing TMR-SiO2-NTA-Ni+2. Silica-embedded TMR retains very high quantum yield, is resistant to quenching by buffer components and is modestly quenched and only to a certain depth (ca. 2 nm) by surface-attached Ni+2. When exposed to a bacterial lysate containing estrogen receptor α ligand binding domain (ERα) as a minor component, these beads showed very high specificity binding, enabling protein purification in one step. The capacity and specificity of these beads for binding a his-tagged protein were characterized by electrophoresis, radiometric counting, and MALDI-TOF MS. ERα, bound to TMR-SiO2-NTA-Ni++ beads in a site-specific manner, exhibited good activity for ligand binding and for ligand-induced binding to coactivators in solution FRET experiments and protein microarray fluorometric and FRET assays. This dual-mode type TMR-SiO2-NTA-Ni++ system represents a powerful combination of one-step histidine-tagged protein purification and site-specific labeling with multiple fluorophore species. BRIEFS Tetramethylrhodamine-doped silica nanoparticles surface modified with nitrilotriacetic acid are dual-mode agents that can be used to purify and site-specifically fluorophore label his-tagged proteins in one step for fluorometric and FRET experiments. PMID:17910454

  19. Serum uric acid level in normal pregnant and preeclamptic ladies: a comparative study.

    PubMed

    Pramanik, T; Khatiwada, B; Pradhan, P

    2014-09-01

    Preeclampsia is a serious pregnancy complication characterized by hypertension, proteinuria with or without pathological edema. According to some studies, serum uric acid lacks sensitivity and specificity as a diagnostic tool whereas another group of the researchers indicated uricemia as a predictor of preeclampsia in pregnant ladies. The present study was designed to assess whether serum uric acid can be used as a biochemical indicator or not in preeclamptic patients. Pre-eclamptic patients admitted in Nepal Medical College Teaching Hospital from June 2012 to June 2013 were included in this study. Age matched normal healthy pregnant ladies served as control. The record of their blood pressure and serum uric acid level was evaluated. Results showed significantly high blood pressure [SBP 149.42±12.35 vs 109.00±7.93 mm Hg; DBP 96.85±8.32 vs 72.5±7.10 mm Hg], and serum uric acid level [6.27±1.37 vs 4.27±0.61 mg/dl] in pre-eclamptic patients compared to their healthy counterparts. Uric acid is a terminal metabolite of the degradation of nucleotides, which increases their blood levels in patients with preeclampsia increasing its synthesis by damage and death of trophoblastic cells and proliferation. Uricemia in preeclampsia likely results from reduced uric acid clearance from diminished glomerular filtration, increased tubular reabsorption and decreased secretion. Results of the present study indicated association of elevated serum uric acid level with preeclampsia which could be used as a biochemical indicator of preeclampsia in pregnant women. PMID:25799807

  20. Electrochemical Sensor Based on Fe Doped Hydroxyapatite-Carbon Nanotubes Composite for L-Dopa Detection in the Presence of Uric Acid.

    PubMed

    Kanchana, P; Radhakrishnan, S; Navaneethan, M; Arivanandhan, M; Hayakawa, Y; Sekar, C

    2016-06-01

    A novel amperometric sensor based on iron doped hydroxyapatite (Fe-HA) and multiwalled carbon nanotubes (CNT) composite immobilized on a glassy carbon electrode (GCE) has been fabricated. The hybrid composite made of Fe-HA nanoparticles and CNT promotes electron transfer kinetics between the analyte levodopa (L-dopa) and the modified GC electrode. Under optimum conditions, the fabricated sensor gave a linear response range of 1.0 x 10(-7)-1.1 x 10(-6) M with the detection limit as low as 62 nM. The Fe-HA/CNT modified electrode showed good selectivity towards the determination of L-dopa in the presence of ascorbic acid (AA), uric acid (UA) and other common interferents. The sensor displays a high sensitivity, good reproducibility and long-term stability and it was successfully applied for the detection of L-dopa in pharmaceutical and medicinal plant samples. PMID:27427688

  1. Energy-level matching of Fe(III) ions grafted at surface and doped in bulk for efficient visible-light photocatalysts.

    PubMed

    Liu, Min; Qiu, Xiaoqing; Miyauchi, Masahiro; Hashimoto, Kazuhito

    2013-07-10

    Photocatalytic reaction rate (R) is determined by the multiplication of light absorption capability (α) and quantum efficiency (QE); however, these two parameters generally have trade-off relations. Thus, increasing α without decreasing QE remains a challenging issue for developing efficient photocatalysts with high R. Herein, using Fe(III) ions grafted Fe(III) doped TiO2 as a model system, we present a novel method for developing visible-light photocatalysts with efficient R, utilizing the concept of energy level matching between surface-grafted Fe(III) ions as co-catalysts and bulk-doped Fe(III) ions as visible-light absorbers. Photogenerated electrons in the doped Fe(III) states under visible-light efficiently transfer to the surface grafted Fe(III) ions co-catalysts, as the doped Fe(III) ions in bulk produced energy levels below the conduction band of TiO2, which match well with the potential of Fe(3+)/Fe(2+) redox couple in the surface grafted Fe(III) ions. Electrons in the surface grafted Fe(III) ions efficiently cause multielectron reduction of adsorbed oxygen molecules to achieve high QE value. Consequently, the present Fe(III)-FexTi1-xO2 nanocomposites exhibited the highest visible-light R among the previously reported photocatalysts for decomposition of gaseous organic compounds. The high R can proceed even under commercial white-light emission diode irradiation and is very stable for long-term use, making it practically useful. Further, this efficient method could be applied in other wide-band gap semiconductors, including ZnO or SrTiO3, and may be potentially applicable for other photocatalysis systems, such as water splitting, CO2 reduction, NOx removal, and dye decomposition. Thus, this method represents a strategic approach to develop new visible-light active photocatalysts for practical uses. PMID:23768256

  2. The use of imidazolium ionic liquid/copper complex as novel and green catalyst for chemiluminescent detection of folic acid by Mn-doped ZnS nanocrystals.

    PubMed

    Azizi, Seyed Naser; Shakeri, Parmis; Chaichi, Mohammad Javad; Bekhradnia, Ahmadreza; Taghavi, Mehdi; Ghaemy, Mousa

    2014-03-25

    A novel chemiluminescence (CL) method using water-soluble Mn-doped ZnS quantum dots (QDs) as CL emitter is proposed for the chemiluminometric determination of folic acid in pharmaceutical formulation. Water-soluble Mn-doped ZnS QDs were synthesized by using L-cysteine as stabilizer in aqueous solutions. The nanoparticles were structurally and optically characterized by X-ray powder diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectroscopy and photoluminescence (PL) emission spectroscopy. The CL of ZnS QDs induced by directly chemical oxidation and its ionic liquid-sensitized effect in aqueous solution were then investigated. It was found that oxidants, especially hydrogen peroxide, could directly oxidize ZnS QDs to produce weak CL emission in basic conditions. In the presence of 1,3-dipropylimidazolium bromide/copper a drastic light emission enhancement is observed, related to a strong interaction between Cu(2+) and the imidazolium ring. Therefore, a new CL analysis system was developed for the determination of folic acid. Under the optimum conditions, there is a good linear relationship between the relative CL intensity and the concentration of folic acid in the range of 1×10(-9)-1×10(-)(6) M of folic acid with a correlation coefficient (R(2)) of 0.9991. The limit of detection of this system was found to be 1×10(-)(10) M. This method is not only simple, sensitive and low cost, but also reliable for practical applications. PMID:24322762

  3. Growth temperature dependence of Si doping efficiency and compensating deep level defect incorporation in Al{sub 0.7}Ga{sub 0.3}N

    SciTech Connect

    Armstrong, Andrew M. Moseley, Michael W.; Allerman, Andrew A.; Crawford, Mary H.; Wierer, Jonathan J.

    2015-05-14

    The growth temperature dependence of Si doping efficiency and deep level defect formation was investigated for n-type Al{sub 0.7}Ga{sub 0.3}N. It was observed that dopant compensation was greatly reduced with reduced growth temperature. Deep level optical spectroscopy and lighted capacitance-voltage were used to understand the role of acceptor-like deep level defects on doping efficiency. Deep level defects were observed at 2.34 eV, 3.56 eV, and 4.74 eV below the conduction band minimum. The latter two deep levels were identified as the major compensators because the reduction in their concentrations at reduced growth temperature correlated closely with the concomitant increase in free electron concentration. Possible mechanisms for the strong growth temperature dependence of deep level formation are considered, including thermodynamically driven compensating defect formation that can arise for a semiconductor with very large band gap energy, such as Al{sub 0.7}Ga{sub 0.3}N.

  4. Crossover between magnetism and superconductivity in LaFeAsO with low H-doping level

    NASA Astrophysics Data System (ADS)

    Lamura, G.; Shiroka, T.; Bonfà, P.; Sanna, S.; De Renzi, R.; Caglieris, F.; Cimberle, M. R.; Iimura, S.; Hosono, H.; Putti, M.

    2014-07-01

    By making a systematic study of the hydrogen-doped LaFeAsO system by means of dc resistivity, dc magnetometry, and muon-spin spectroscopy, we addressed the question of universality of the phase diagram of rare-earth-1111 pnictides. In many respects, the behaviour of LaFeAsO1-xHx resembles that of its widely studied F-doped counterpart, with H- realizing a similar (or better) electron doping in the LaO planes. In an x = 0.01 sample we found a long-range spin-density wave (SDW) order with TN = 119 K, while at x = 0.05 the SDW establishes only at 38 K and, below Tc = 10 K, it coexists at a nanoscopic scale with bulk superconductivity. Unlike the abrupt magnetic-superconducting transition found in the La-1111 compound, the presence of a crossover region makes the H-doped system qualitatively similar to other Sm-1111, Ce-1111, and Nd-1111 families.

  5. Pyruvic acid levels in serum and saliva: A new course for oral cancer screening?

    PubMed Central

    Bhat, Manohara A; Prasad, KVV; Trivedi, Dheeraj; Rajeev, BR; Battur, Hemanth

    2016-01-01

    Objective: Cancerous cells show increased glycolysis rate. This will increase overall levels of pyruvate as it is one of the end products of glycolysis. The present on-going study is to estimate the levels of pyruvate in saliva and serum among healthy and oral cancer subjects. Settings and Design: Hospital-based cross-sectional comparative study. Methodology: A total of 50 subjects among healthy and oral cancer subjects were selected based on clinical and histological criteria. Saliva and serum samples were collected and subjected to pyruvate level estimation using biochemical analysis. Statistical Analysis: Descriptive analysis and Mann-Whitney test were used to find the statistical difference between the two independent groups. Results: Serum pyruvic acid levels of the healthy group were 1.09 ± 0.14 and for oral cancer, it was 2.95 ± 0.59 and salivary level were 3.49 ± 0.47 and 1.32 ± 0.10 respectively. Mann-Whitney test showed statistically significant difference in serum and salivary pyruvate level in between two groups (P < 0.000 respectively). Conclusion: The present study showed noticeable variation in the level of pyruvic acid among healthy and oral cancer subjects. This generates the hypothesis that estimation of the pyruvic acid can be a new tool to screening of the cancer. PMID:27194870

  6. The GLUT9 Gene Is Associated with Serum Uric Acid Levels in Sardinia and Chianti Cohorts

    PubMed Central

    Maschio, Andrea; Busonero, Fabio; Usala, Gianluca; Mulas, Antonella; Lai, Sandra; Dei, Mariano; Orrù, Marco; Albai, Giuseppe; Bandinelli, Stefania; Schlessinger, David; Lakatta, Edward; Scuteri, Angelo; Najjar, Samer S; Guralnik, Jack; Naitza, Silvia; Crisponi, Laura; Cao, Antonio; Abecasis, Gonçalo; Ferrucci, Luigi; Uda, Manuela; Chen, Wei-Min; Nagaraja, Ramaiah

    2007-01-01

    High serum uric acid levels elevate pro-inflammatory–state gout crystal arthropathy and place individuals at high risk for cardiovascular morbidity and mortality. Genome-wide scans in the genetically isolated Sardinian population identified variants associated with serum uric acid levels as a quantitative trait. They mapped within GLUT9, a Chromosome 4 glucose transporter gene predominantly expressed in liver and kidney. SNP rs6855911 showed the strongest association (p = 1.84 × 10−16), along with eight others (p = 7.75 × 10−16 to 6.05 × 10−11). Individuals homozygous for the rare allele of rs6855911 (minor allele frequency = 0.26) had 0.6 mg/dl less uric acid than those homozygous for the common allele; the results were replicated in an unrelated cohort from Tuscany. Our results suggest that polymorphisms in GLUT9 could affect glucose metabolism and uric acid synthesis and/or renal reabsorption, influencing serum uric acid levels over a wide range of values. PMID:17997608

  7. Large lead/acid batteries for frequency regulation, load levelling and solar power applications

    NASA Astrophysics Data System (ADS)

    Wagner, R.

    Lead/acid batteries are suitable for a multitude of utility applications. This paper presents some examples where large lead/acid batteries have been used for frequency regulation, load levelling and solar power applications. The operational experiences are given together with a discussion about the design and technical specialities of these batteries. In 1986, a 17 MW/14 MWh battery was installed at BEWAG in Berlin which, at that time, was the largest lead/acid battery in the world. Designed to strengthen Berlin's 'island' system, it was used since the beginning of 1987 for frequency regulation and spinning reserve. In December 1993, when Berlin was connected to the electricity grid, frequency regulation was no longer required but the battery was still used for spinning reserve. For many years, the industrial battery plant of Hagen in Soest has used a large lead/acid battery for load levelling. The experience gained during more than ten years shows that load levelling and peak shaving can be a marked benefit for customers and utilities with regard to reducing their peak demand. In the summer of 1992, a 216 V and 2200 Ah lead/acid battery with positive tubular plates and gelled electrolyte was installed at a solar power plant in Flanitzhutte, a small village in the south of Germany which is not connected to the electricity grid. A report is given of the first years of use and includes a discussion about the best charge strategy for such gel batteries when used for solar power applications.

  8. Salicylic Acid Treatment Increases the Levels of Triterpene Glycosides in Black Cohosh (Actaea Racemosa) Rhizomes.

    PubMed

    De Capite, Annette; Lancaster, Tyler; Puthoff, David

    2016-01-01

    Black cohosh (Actaea racemosa) serves as the host plant for the Appalachian azure butterfly, Celastrina neglectamajor. Overharvesting of Black cohosh for the dietary supplement industry may result in its extirpation, and may also cause the elimination of the dependent butterfly. One way to increase or maintain the number of host plants in forested environments would be to reduce the number harvested, for example by increasing the levels of the desired metabolites in Black cohosh rhizomes. The secondary metabolites actein and deoxyactein are triterpene glycosides and are among the compounds associated with the putative activity of Black cohosh extracts. Acetein and deoxyacetein are used to standardize Black cohosh supplements. To gain an understanding of mechanisms that may control actein and deoxyactein accumulation, Black cohosh rhizomes were treated with exogenous salicylic acid, jasmonic acid, or ethylene, or were mechanically wounded. Salicylic acid treatment significantly increased the levels of actein and deoxyactein in the rhizome of Black cohosh, suggesting that the synthesis of triterpene glycosides is controlled in part by salicylic acid. Using salicylic acid or related chemicals to increase the levels of actein and deoxyactein in rhizomes may help supply the supplement industry and, simultaneously, help conserve Black cohosh and species dependent upon it. PMID:26634573

  9. Understanding of how Propionibacterium acidipropionici respond to propionic acid stress at the level of proteomics

    PubMed Central

    Guan, Ningzi; Shin, Hyun-dong; Chen, Rachel R.; Li, Jianghua; Liu, Long; Du, Guocheng; Chen, Jian

    2014-01-01

    Propionic acid (PA) is an important platform chemical in the food, agriculture, and pharmaceutical industries and is mainly biosynthesized by propionibacteria. Acid tolerance in PA-producing strains is crucial. In previous work, we investigated the acid tolerance mechanism of Propionibacterium acidipropionici at microenvironmental levels by analyzing physiological changes in the parental strain and three PA-tolerant mutants obtained by genome shuffling. However, the molecular mechanism of PA tolerance in P. acidipropionici remained unclear. Here, we performed a comparative proteomics study of P. acidipropionici CGMCC 1.2230 and the acid-tolerant mutant P. acidipropionici WSH1105; MALDI-TOF/MS identified 24 proteins that significantly differed between the parental and shuffled strains. The differentially expressed proteins were mainly categorized as key components of crucial biological processes and the acid stress response. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was used to confirm differential expression of nine key proteins. Overexpression of the secretory protein glyceraldehyde-3-phosphate dehydrogenase and ATP synthase subunit α in Escherichia coli BL21 improved PA and acetic acid tolerance; overexpression of NADH dehydrogenase and methylmalonyl-CoA epimerase improved PA tolerance. These results provide new insights into the acid tolerance of P. acidipropionici and will facilitate the development of PA production through fermentation by propionibacteria. PMID:25377721

  10. Cerebrospinal fluid levels of phenylacetic acid in mental illness: behavioral associations and response to neuroleptic treatment.

    PubMed

    Sharma, R P; Faull, K; Javaid, J I; Davis, J M

    1995-05-01

    Cerebrospinal fluid levels of phenylacetic acid (CSF PAA) were obtained from normal controls and from drug-free psychiatric inpatients (schizophrenia, major depression, mania, and schizoaffective disorder). Post-treatment CSF PAA levels were obtained from 16 patients after 4 weeks of neuroleptic treatment. Phenylacetic acid levels were higher in women and were significantly correlated with age. There were no differences in CSF PAA levels between the various diagnostic groups and no difference between the paranoid and the nonparanoid subtypes of schizophrenia. CSF PAA was significantly correlated with several measures of psychopathology, especially the Brief Psychiatric Rating Scale hostility/suspiciousness factor. Neuroleptic treatment did not result in significant PAA changes. These findings are discussed in light of the amphetamine-like role ascribed to phenylethylamine, the precursor of PAA. PMID:7639084

  11. Temporal variability in urinary levels of drinking water disinfection byproducts dichloroacetic acid and trichloroacetic acid among men

    SciTech Connect

    Wang, Yi-Xin; Zeng, Qiang; Wang, Le; Huang, Yue-Hui; Lu, Zhi-Wei; Wang, Peng; He, Meng-Jie; Huang, Xin; Lu, Wen-Qing

    2014-11-15

    Urinary haloacetic acids (HAAs), such as dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA), have been suggested as potential biomarkers of exposure to drinking water disinfection byproducts (DBPs). However, variable exposure to and the short elimination half-lives of these biomarkers can result in considerable variability in urinary measurements, leading to exposure misclassification. Here we examined the variability of DCAA and TCAA levels in the urine among eleven men who provided urine samples on 8 days over 3 months. The urinary concentrations of DCAA and TCAA were measured by gas chromatography coupled with electron capture detection. We calculated the intraclass correlation coefficients (ICCs) to characterize the within-person and between-person variances and computed the sensitivity and specificity to assess how well single or multiple urine collections accurately determined personal 3-month average DCAA and TCAA levels. The within-person variance was much higher than the between-person variance for all three sample types (spot, first morning, and 24-h urine samples) for DCAA (ICC=0.08–0.37) and TCAA (ICC=0.09–0.23), regardless of the sampling interval. A single-spot urinary sample predicted high (top 33%) 3-month average DCAA and TCAA levels with high specificity (0.79 and 0.78, respectively) but relatively low sensitivity (0.47 and 0.50, respectively). Collecting two or three urine samples from each participant improved the classification. The poor reproducibility of the measured urinary DCAA and TCAA concentrations indicate that a single measurement may not accurately reflect individual long-term exposure. Collection of multiple urine samples from one person is an option for reducing exposure classification errors in studies exploring the effects of DBP exposure on reproductive health. - Highlights: • We evaluated the variability of DCAA and TCAA levels in the urine among men. • Urinary DCAA and TCAA levels varied greatly over a 3-month

  12. The effect of doping density and injection level on minority-carrier lifetime as applied to bifacial dendritic web silicon solar cells

    NASA Astrophysics Data System (ADS)

    Meier, Daniel L.; Hwang, Jeong-Mo; Campbell, Robert B.

    1988-01-01

    The decrease of minority-carrier lifetime with resistivity and with illumination level in bifacial dendritic web silicon solar cells is addressed. This variation of lifetime is shown to be consistent with the presence of a distribution of defect levels in the bandgap that arise from extended defects in the we material. The extended defects are precipitates, recently shown to be oxide precipitates, that decorate dislocation cores. It follows that the sensitivity to this background distribution of defect levels increases with doping because the Fermi level moves closer to the majority-carrier band edge. Good agreement is obtained between calculated and measured values of short-circuit current and quantum efficiency for bifacial cells covering a range of doping density and illumination level, with illumination from either back or front of the cell. The implications of this approach extend to concentrator cells and to other devices in which minority-carrier lifetime is an important parameter. This includes devices made using Czochralski-grown silicon, where oxygen and oxide precipitates likewise play an important role in determining lifetime.

  13. Intrauterine bacterial inoculation and level of dietary methionine alter amino acid metabolism in nulliparous yearling ewes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using an intrauterine bacterial inoculation method, our objective was to determine the effects of acute sepsis and level of dietary metabolizable-methionine on splanchnic metabolism of amino acids in ewes. Twenty-five nulliparous yearling Rambouillet-cross ewes (initial BW = 65.1 ± 0.6 kg), surgical...

  14. Elevated carbon dioxide levels enhance rosmarinic acid production in spearmint plantlets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The C20 diterpene rosmarinic acid (RA) is synthesized in the phenylpropanoid pathway and is constitutively expressed in spearmint (Mentha spicata L.) plantlets grown in vitro. RA levels within plantlet leaves were found to be readily manipulated by the nutritional and physical environments. Higher...

  15. A `Clicked' Tetrameric Hydroxamic Acid Glycopeptidomimetic Antagonizes Sugar-Lectin Interactions On The Cellular Level

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Lin; Zang, Yi; Xie, Juan; Li, Jia; Chen, Guo-Rong; He, Xiao-Peng; Tian, He

    2014-07-01

    A tetrameric N-acetyl galactosaminyl (GalNAc) peptidomimetic was constructed by N-acetylation of repeating proline-based hydroxamic acid units, followed by a convergent `click chemistry' coupling. This novel glycopeptidomimetic was determined to effectively antagonize the interaction between a transmembrane hepatic lectin and GalNAc on the cellular level.

  16. Ileal apical sodium-dependent bile acid transporter protein levels are down-regulated through ubiquitin-dependent protein degradation induced by bile acids.

    PubMed

    Miyata, Masaaki; Yamakawa, Hiroki; Hayashi, Kenjiro; Kuribayashi, Hideaki; Yamazoe, Yasushi; Yoshinari, Kouichi

    2013-08-15

    The ileal apical sodium-dependent bile acid transporter (ASBT or SLC10A2) has a crucial role in intestinal bile acid absorption. We previously reported that enterobacteria-mediated bile acid conversion was involved in the alteration of ileal ASBT expression levels. In the present study, to investigate the hypothesis that ileal ASBT protein levels are post-translationally regulated by enterobacteria-associated bile acids, alteration of ileal ASBT protein levels was analysed in mice 12 h and 24 h after anti-bacterial drug ampicillin (ABPC) treatment (100 mg/kg, single shot) that altered bile acid composition in the intestinal lumen. In ABPC-treated mice, enterobacteria-biotransformed bile acid, taurodeoxycholic acid (TDCA) and cholic acid (CA) levels were decreased, whereas taurocholic acid (TCA) and tauro-β-muricholic acid levels were increased in the intestinal lumen. Ileal ASBT protein levels in brush-border membrane vesicles (BBMVs), but not ileal Asbt mRNA levels, were significantly increased in the ABPC-treated mice, and the extent of ubiquitination of the ileal ASBT protein was reduced in the ABPC-treated mice. Treatment of ABPC-pretreated mice with CA or TDCA, but not TCA, significantly decreased ileal ASBT protein levels and increased the extent of ubiquitination of ileal ASBT protein. Treatment of mice with the lysosome inhibitor, chloroquine, or the proteasome inhibitor, MG132, increased ileal ASBT protein levels in BBMVs. CA-mediated reduction of ASBT protein levels in the ABPC-pretreated mice was attenuated by co-treatment with chloroquine or MG132. These results suggest that ileal ASBT protein is degraded by a ubiquitin-dependent pathway in response to enterobacteria-associated bile acids. PMID:23872411

  17. LED and low level laser therapy association in tooth bleaching using a novel low concentration H2O2/N-doped TiO2 bleaching agent

    NASA Astrophysics Data System (ADS)

    Bezerra Dias, Hércules; Teixeira Carrera, Emanuelle; Freitas Bortolatto, Janaína; Ferrarezi de Andrade, Marcelo; Nara de Souza Rastelli, Alessandra

    2016-01-01

    Since low concentration bleaching agents containing N-doped TiO2 nanoparticles have been introduced as an alternative to conventional agents, it is important to verify their efficacy and the hypersensitivity effect in clinical practice. Six volunteer patients were evaluated for color change and hypersensitivity after bleaching using 35% H2O2 (one session of two 12 min applications) and 6% H2O2/N-doped TiO2 (one session of three 12 min applications) and after low level laser therapy application (LLLT) (780 nm, 40 mW, 10 J.cm-2, 10 s). Based on this case study, the nanobleaching agent provided better or similar aesthetic results than the conventional agent under high concentration, and its association with LLLT satisfactorily decreased the hypersensitivity. The 6% H2O2/N-doped TiO2 agent could be used instead of conventional in-office bleaching agents under high concentrations to fulfill the rising patient demand for aesthetics.

  18. Effects of different fatty acid chain lengths on fatty acid oxidation-related protein expression levels in rat skeletal muscles.

    PubMed

    Ishizawa, Rie; Masuda, Kazumi; Sakata, Susumu; Nakatani, Akira

    2015-01-01

    Skeletal muscles can adapt to dietary interventions that affect energy metabolism. Dietary intake of medium-chain fatty acids (MCFAs) enhances mitochondrial oxidation of fatty acids (FAO) in type IIa skeletal muscle fibers. However, the effect of MCFAs diet on mitochondrial or cytoplasmic FAO-related protein expression levels in different types of muscle fibers remains unclear. This study aims to examine the effects of a high-fat diet, containing MCFAs, on mitochondrial enzyme activities and heart-type fatty acid-binding protein (H-FABP) levels in different types of skeletal muscle fibers. Five-week-old male Wistar rats were assigned to one of the following three dietary conditions: standard chow (SC, 12% of calories from fat), high-fat MCFA, or high-fat long-chain fatty acids (LCFAs) diet (60% of calories from fat for both). The animals were provided food and water ad libitum for 4 weeks, following which citrate synthase (CS) activity and H-FABP concentration were analyzed. The epididymal fat pads (EFP) were significantly smaller in the MCFA group than in the LCFA group (p < 0.05). MCFA-fed group displayed an increase in CS activity compared with that observed in SC-fed controls in all types of skeletal muscle fibers (triceps, surface portion of gastrocnemius (gasS), deep portion of gastrocnemius (gasD), and soleus; p < 0.05,). H-FABP concentration was significantly higher in the LCFA group than in both the SC-fed and MCFA-fed groups (triceps, gasS, gasD, and soleus; p < 0.05,). However, no significant difference was observed in the H-FABP concentrations between the SC-fed and MCFA-fed groups. The results of this study showed that the MCFA diet can increase the expression of the mitochondrial enzyme CS, but not that of H-FABP, in both fast- and slow-twitch muscle fibers, suggesting that H-FABP expression is dependent on the chain length of fatty acids in the cytoplasm of skeletal muscles cells. PMID:25766930

  19. Inverse Association Between Serum Uric Acid Levels and Alzheimer's Disease Risk.

    PubMed

    Du, Na; Xu, Donghua; Hou, Xu; Song, Xuejia; Liu, Cancan; Chen, Ying; Wang, Yangang; Li, Xin

    2016-05-01

    The association between Alzheimer's disease and uric acid levels had gained great interest in recent years, but there was still lack of definite evidence. A systematic review and meta-analysis of relevant studies was performed to comprehensively estimate the association. Relevant studies published before October 26, 2014, were searched in PubMed, Embase, and China Biology Medicine (CBM) databases. Study-specific data were combined using random-effects or fixed-effects models of meta-analysis according to between-study heterogeneity. Twenty-four studies (21 case-control and 3 cohort studies) were finally included into the meta-analysis. Those 21 case-control studies included a total of 1128 cases of Alzheimer's disease and 2498 controls without Alzheimer's disease. Those 3 cohort studies included a total of 7327 participants. Meta-analysis showed that patients with Alzheimer's disease had lower levels of uric acid than healthy controls (weighted mean difference (WMD) = -0.77 mg/dl, 95 % CI -2.28 to -0.36, P = 0.0002). High serum uric acid levels were significantly associated with decreased risk of Alzheimer's disease (risk ratio (RR) = 0.66, 95 % CI 0.52-0.85, P = 0.001). There was low risk of publication bias in the meta-analysis. There is an inverse association between serum uric acid levels and Alzheimer's disease. High serum uric acid level is a protective factor of Alzheimer's disease. PMID:26084440

  20. Low Serum Levels of Uric Acid are Associated With Development of Poststroke Depression

    PubMed Central

    Gu, Yingying; Han, Bin; Wang, Liping; Chang, Yaling; Zhu, Lin; Ren, Wenwei; Yan, Mengjiao; Zhang, Xiangyang; He, Jincai

    2015-01-01

    Abstract Poststroke depression (PSD) is a frequent complication of stroke that has been associated with poorer outcome of stroke patients. This study sought to examine the possible association between serum uric acid levels and the development of PSD. We recruited 196 patients with acute ischemic stroke and 100 healthy volunteers. Serum uric acid levels were tested by uricase-PAP method within 24 hr after admission. Neuropsychological evaluations were conducted at 3-month poststroke. The 17-item Hamilton Depression Scale was used to assess depressive symptoms. Diagnosis of PSD was made in accordance with DSM-IV criteria for depression. Multivariate analyses were conducted using logistic regression models. Fifty-six patients (28.6%) were diagnosed as having PSD at 3 months. PSD patients showed significantly lower levels of uric acid at baseline as compared to non-PSD patients (237.02 ± 43.43 vs 309.10 ± 67.44 μmol/L, t = −8.86, P < 0.001). In multivariate analyses, uric acid levels (≤239.0 and ≥328.1 μmol/L) were independently associated with the development of PSD (OR, 7.76; 95% confidence interval [CI], 2.56–23.47, P < 0.001 and OR, 0.05; 95% CI, 0.01–0.43, P = 0.01, respectively) after adjustment for possible variables. Serum uric acid levels at admission are found to be correlated with PSD and may predict its development at 3 months after stroke. PMID:26559256

  1. 17β-estradiol increases liver and serum docosahexaenoic acid in mice fed varying levels of α-linolenic acid.

    PubMed

    Mason, Julie K; Kharotia, Shikhil; Wiggins, Ashleigh K A; Kitson, Alex P; Chen, Jianmin; Bazinet, Richard P; Thompson, Lilian U

    2014-08-01

    Docosahexaenoic acid (DHA) is considered to be important for cardiac and brain function, and 17β-estradiol (E2) appears to increase the conversion of α-linolenic acid (ALA) into DHA. However, the effect of varying ALA intake on the positive effect of E2 on DHA synthesis is not known. Therefore, the objective of this study was to investigate the effects of E2 supplementation on tissue and serum fatty acids in mice fed a low-ALA corn oil-based diet (CO, providing 0.6 % fatty acids as ALA) or a high ALA flaxseed meal-based diet (FS, providing 11.2 % ALA). Ovariectomized mice were implanted with a slow-release E2 pellet at 3 weeks of age and half the mice had the pellet removed at 7 weeks of age. Mice were then randomized onto either the CO or FS diet. After 4 weeks, the DHA concentration was measured in serum, liver and brain. A significant main effect of E2 was found for liver and serum DHA, corresponding to 25 and 15 % higher DHA in livers of CO and FS rats, respectively, and 19 and 13 % in serum of CO and FS rats, respectively, compared to unsupplemented mice. There was no effect of E2 on brain DHA. E2 results in higher DHA in serum and liver, at both levels of dietary ALA investigated presently, suggesting that higher ALA intake may result in higher DHA in individuals with higher E2 status. PMID:24913495

  2. Residual mitochondrial transmembrane potential decreases unsaturated fatty acid level in sake yeast during alcoholic fermentation

    PubMed Central

    Sawada, Kazutaka

    2016-01-01

    Oxygen, a key nutrient in alcoholic fermentation, is rapidly depleted during this process. Several pathways of oxygen utilization have been reported in the yeast Saccharomyces cerevisiae during alcoholic fermentation, namely synthesis of unsaturated fatty acid, sterols and heme, and the mitochondrial electron transport chain. However, the interaction between these pathways has not been investigated. In this study, we showed that the major proportion of unsaturated fatty acids of ester-linked lipids in sake fermentation mash is derived from the sake yeast rather than from rice or koji (rice fermented with Aspergillus). Additionally, during alcoholic fermentation, inhibition of the residual mitochondrial activity of sake yeast increases the levels of unsaturated fatty acids of ester-linked lipids. These findings indicate that the residual activity of the mitochondrial electron transport chain reduces molecular oxygen levels and decreases the synthesis of unsaturated fatty acids, thereby increasing the synthesis of estery flavors by sake yeast. This is the first report of a novel link between residual mitochondrial transmembrane potential and the synthesis of unsaturated fatty acids by the brewery yeast during alcoholic fermentation. PMID:26839744

  3. Residual mitochondrial transmembrane potential decreases unsaturated fatty acid level in sake yeast during alcoholic fermentation.

    PubMed

    Sawada, Kazutaka; Kitagaki, Hiroshi

    2016-01-01

    Oxygen, a key nutrient in alcoholic fermentation, is rapidly depleted during this process. Several pathways of oxygen utilization have been reported in the yeast Saccharomyces cerevisiae during alcoholic fermentation, namely synthesis of unsaturated fatty acid, sterols and heme, and the mitochondrial electron transport chain. However, the interaction between these pathways has not been investigated. In this study, we showed that the major proportion of unsaturated fatty acids of ester-linked lipids in sake fermentation mash is derived from the sake yeast rather than from rice or koji (rice fermented with Aspergillus). Additionally, during alcoholic fermentation, inhibition of the residual mitochondrial activity of sake yeast increases the levels of unsaturated fatty acids of ester-linked lipids. These findings indicate that the residual activity of the mitochondrial electron transport chain reduces molecular oxygen levels and decreases the synthesis of unsaturated fatty acids, thereby increasing the synthesis of estery flavors by sake yeast. This is the first report of a novel link between residual mitochondrial transmembrane potential and the synthesis of unsaturated fatty acids by the brewery yeast during alcoholic fermentation. PMID:26839744

  4. A rapid microwave synthesis of nitrogen-sulfur co-doped carbon nanodots as highly sensitive and selective fluorescence probes for ascorbic acid.

    PubMed

    Duan, Junxia; Yu, Jie; Feng, Suling; Su, Li

    2016-06-01

    A ultrafast one-step microwave-assisted method was developed for the synthesis of nitrogen-sulfur co-doped carbon nanodots (N,S-CDs) by using ethylenediamine as the carbon source and sulfamic acid as the surface passivation reagent. The morphology and the properties of N,S-CDs were explored by a series of techniques, such as high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, UV-vis absorption and fluorescence spectroscopy. The prepared N,S-CDs exhibit bright blue photoluminescence with a high fluorescence quantum yield (FLQY) up to 28%, and high stability and excellent water solubility. A N,S-CDs-based fluorescent probe was developed for sensitive detection ascorbic acid (AA) in the presence of Cu(2+), based on the mechanism that AA reduces Cu(2+) to Cu(+), then Cu(+) quenches the fluorescence of N,S-CDs through electron or energy transfer due to the interaction between Cu(+) and thiol ligand on the N,S-CDs surface. The observed linear response concentration range was from 0.057 to 4.0μM to AA with a detection limit as low as 18nM. The probe exhibited a highly selective response toward AA even in the presence of possible interfering substances, such as uric acid and citric acid. Moreover, these promising features made the sensing system used for the analysis of human serum and urine samples. PMID:27130124

  5. Life-history evolution at the molecular level: adaptive amino acid composition of avian vitellogenins

    PubMed Central

    Hughes, Austin L.

    2015-01-01

    Avian genomes typically encode three distinct vitellogenin (VTG) egg yolk proteins (VTG1, VTG2 and VTG3), which arose by gene duplication prior to the most recent common ancestor of birds. Analysis of VTG sequences from 34 avian species in a phylogenetic framework supported the hypothesis that VTG amino acid composition has co-evolved with embryo incubation time. Embryo incubation time was positively correlated with the proportions of dietary essential amino acids (EAAs) in VTG1 and VTG2, and with the proportion of sulfur-containing amino acids in VTG3. These patterns were seen even when only semi-altricial and/or altricial species were considered, suggesting that the duration of embryo incubation is a major selective factor on the amino acid composition of VTGs, rather than developmental mode alone. The results are consistent with the hypothesis that the level of EAAs provided to the egg represents an adaptation to the loss of amino acids through breakdown over the course of incubation and imply that life-history phenotypes and VTG amino acid composition have co-evolved throughout the evolutionary history of birds. PMID:26224713

  6. Serum levels of short-chain fatty acids in cirrhosis and hepatic coma.

    PubMed

    Clausen, M R; Mortensen, P B; Bendtsen, F

    1991-12-01

    Short-chain fatty acids cause reversible coma in animals and may contribute to the pathogenesis of the hepatic coma in humans. The concentrations of short-chain fatty acids in peripheral venous blood were significantly elevated in 15 patients with hepatic encephalopathy caused by cirrhosis (362 +/- 83 mumol/L; mean +/- S.E.M.) compared with 17 cirrhotic patients without encephalopathy (178 +/- 57 mumol/L) and 11 normal individuals (60 +/- 8 mumol/L). However, no correlation between the depth of coma and the level of short-chain fatty acids was found after repetitive measurements in the coma group. Compared with normal individuals, all short-chain fatty acids, except valerate, were elevated in patients with hepatic encephalopathy, whereas only the concentrations of isobutyrate and isovalerate were significantly elevated in cirrhotic patients without encephalopathy. The concentrations of short-chain fatty acids in 21 nonencephalopathic cirrhotic patients who underwent catheterization were equally distributed in the aorta (187 +/- 56 mumol/L), the hepatic vein (212 +/- 75 mumol/L), the azygos vein (140 +/- 37 mumol/L) and the renal vein (135 +/- 43 mumol/L) compared with peripheral venous blood (178 +/- 57 mumol/L). This study does not support the idea that short-chain fatty acids are of major importance in the pathogenesis of hepatic coma in patients with cirrhosis. PMID:1959851

  7. Investigation of catalytic activity towards oxygen reduction reaction of Pt dispersed on boron doped graphene in acid medium.

    PubMed

    Pullamsetty, Ashok; Sundara, Ramaprabhu

    2016-10-01

    Boron doped graphene was prepared by a facile method and platinum (Pt) decoration over boron doped graphene was done in various chemical reduction methods such as sodium borohydride (NaBH4), polyol and modified polyol. X-ray diffraction analysis indicates that the synthesized catalyst particles are present in a nanocrystalline structure and transmission and scanning electron microscopy were employed to investigate the morphology and particle distribution. The electrochemical properties were investigated with the help of the rotating disk electrode (RDE) technique and cyclic voltammetry. The results show that the oxygen reduction reaction (ORR) takes place by a four-electron process. The kinetics of the ORR was evaluated using K-L and Tafel plots. The electrocatalyst obtained in modified polyol reduction method has shown the better catalytic activity compared to other two electrocatalysts. PMID:27393888

  8. Modification of birefringence properties of nanostructured silicon with a change in the level of substrate doping with boron

    SciTech Connect

    Piskunov, N. A. Zabotnov, S. V.; Mamichev, D. A.; Golovan', L. A.; Timoshenko, V. Yu.; Kashkarov, P. K.

    2007-07-15

    Birefringence of porous-silicon films prepared by electrochemical etching of boron-doped Si(110) wafers with a resistivity of 25-45 m{theta} cm has been studied. The samples are found to exhibit the properties of a negative uniaxial crystal with the optical axis oriented along the [11-bar0] crystallographic direction. The possibility of using porous-silicon films as phase plates for light-polarization control in the near and mid-IR ranges is demonstrated.

  9. Effect of acidity on the energy level of curcumin dye extracted from Curcuma longa L.

    NASA Astrophysics Data System (ADS)

    Agustia, Yuda Virgantara; Suyitno, Arifin, Zainal; Sutanto, Bayu

    2016-03-01

    The purpose of this research is to investigate the effect of acidity on the energy level of curcumin dye. The natural dye, curcumin, was synthesized from Curcuma longa L. using a simple extraction technique. The purification of curcumin dye was conducted in a column of chromatography and its characteristics were studied. Next, the purified curcumin dye was added by benzoic acids until various acidities of 3.0, 3.5, 4.0, 4.5, and 5.0. The absorbance spectra and the functionality groups found in the dyes were detected by ultraviolet-visible spectroscopy and Fourier-transform infrared spectroscopy, respectively. Meanwhile, the energy level of the dyes, EHOMO and ELUMO was measured by cyclic voltammetry. The best energy level of curcumin dye was achieved at pH 3.5 where Ered = -0.37V, ELUMO = -4.28 eV, Eox = 1.15V, EHOMO = -5.83 eV, and Eband gap = 1.55 eV. Therefore, the purified curcumin dye added by benzoic acid was promising for sensitizing the dye-sensitized solar cells.

  10. ZnO:Al Doping Level and Hydrogen Growth Ambient Effects on CIGS Solar Cell Performance: Preprint

    SciTech Connect

    Duenow, J. N.; Gessert, T. A.; Wood, D. M.; Egaas, B.; Noufi, R.; Coutts,T. J.

    2008-05-01

    Cu(In,Ga)Se2 (CIGS) photovoltaic (PV) cells require a highly conducting and transparent electrode for optimum device performance. ZnO:Al films grown from targets containing 2.0 wt.% Al2O3 are commonly used for this purpose. Maximum carrier mobilities of these films grown at room temperature are ~20-25 cm2V-1s-1. Therefore, relatively high carrier concentrations are required to achieve the desired conductivity, which leads to free carrier absorption in the near infrared (IR). Lightly doped films (0.05 - 0.2 wt.% Al2O3), which show less IR absorption, reach mobility values greater than 50 cm2V-1s-1 when deposited in H2 partial pressure. We incorporate these lightly doped ZnO:Al layers into CIGS PV cells produced at the National Renewable Energy Laboratory (NREL). Preliminary results show quantum efficiency values of these cells rival those of a past world-record cell produced at NREL that used 2.0 wt.% Al-doped ZnO films. The highest cell efficiency obtained in this trial was 18.1%.

  11. Peanut consumption increases levels of plasma very long chain fatty acids in humans.

    PubMed

    Lam, Christina; Wong, Derek; Cederbaum, Stephen; Lim, Bennie; Qu, Yong

    2012-11-01

    Peanut consumption has been suspected of raising plasma very long chain fatty acid (VLCFA) levels in humans. The effect of peanut consumption on VLCFAs was studied in six human subjects. After 3 to 4h of peanut butter ingestion, plasma C26:0 and C26:0/C22:0 were found to be significantly elevated to levels seen in patients with peroxisomal disorders. These levels returned to normal within 12h. Peanut consumption needs to be accounted for when interpreting VLCFAs. PMID:22864056

  12. Fatty Acid Status and Its Relationship to Cognitive Decline and Homocysteine Levels in the Elderly

    PubMed Central

    Baierle, Marília; Vencato, Patrícia H.; Oldenburg, Luiza; Bordignon, Suelen; Zibetti, Murilo; Trentini, Clarissa M.; Duarte, Marta M. M. F.; Veit, Juliana C.; Somacal, Sabrina; Emanuelli, Tatiana; Grune, Tilman; Breusing, Nicolle; Garcia, Solange C.

    2014-01-01

    Polyunsaturated fatty acids (PUFAs), especially the n-3 series, are known for their protective effects. Considering that cardiovascular diseases are risk factors for dementia, which is common at aging, the aim of this study was to evaluate whether fatty acid status in the elderly was associated with cognitive function and cardiovascular risk. Forty-five elderly persons (age ≥60 years) were included and divided into two groups based on their Mini-Mental Status Examination score adjusted for educational level: the case group (n = 12) and the control group (n = 33). Serum fatty acid composition, homocysteine (Hcy), hs-CRP, lipid profile and different cognitive domains were evaluated. The case group, characterized by reduced cognitive performance, showed higher levels of 14:0, 16:0, 16:1n-7 fatty acids and lower levels of 22:0, 24:1n-9, 22:6n-3 (DHA) and total PUFAs compared to the control group (p < 0.05). The n-6/n-3 ratio was elevated in both study groups, whereas alterations in Hcy, hs-CRP and lipid profile were observed in the case group. Cognitive function was positively associated with the 24:1n-9, DHA and total n-3 PUFAs, while 14:0, 16:0 and 16:1n-7 fatty acids, the n-6/n-3 ratio and Hcy were inversely associated. In addition, n-3 PUFAs, particularly DHA, were inversely associated with cardiovascular risk, assessed by Hcy levels in the elderly. PMID:25221976

  13. The effects of different thermal treatments and organic acid levels on nutrient digestibility in broilers.

    PubMed

    Goodarzi Boroojeni, F; Mader, A; Knorr, F; Ruhnke, I; Röhe, I; Hafeez, A; Männer, K; Zentek, J

    2014-05-01

    Poultry feed is a potential vector for pathogens. Heat processing and organic acid treatments may decontaminate feed and can affect bird performance as well as feed digestibility. The present study was performed to investigate the effect of different thermal treatments including pelleting (P), long-term conditioning at 85°C for 3 min (L), or expanding at 110°C (E110) and 130°C for 3 to 5 s (E130) without or with 0.75 and 1.5% organic acid supplementation (63.75% formic acid, 25.00% propionic acid, and 11.25% water) on performance, nutrient digestibility, and organ weights of broilers. In total, 960 one-day-old broiler chicks were randomly assigned to 8 replicates using a 3 × 4 factorial arrangement. Performance variables were determined, and the relative organ weights and ileal and total amino acid (AA) digestibilities were measured at d 35. The organic acid inclusion linearly improved feed efficiency in the first week (P ≤ 0.05). The acid inclusion levels and thermal treatments had no significant effect on the performance variables at later intervals of the growing period of the birds. The L group showed the lowest ileal AA and CP digestibility. The inclusion of organic acids had a quadratic effect on total and ileal digestibility of isoleucine (P ≤ 0.05), whereas it had no significant effect on the ileal digestibility of other AA and nutrients. The relative weights of the jejunum and small intestine were significantly higher in the E130 group compared with P and L (P ≤ 0.05). In conclusion, our study demonstrated that long-term heat conditioning can decrease ileal nutrient digestibility, whereas pelleting and expansion, independently of organic acid addition, seemed to have no negative impact on broiler performance and nutrient digestibilities. Moreover, adding a blend of organic acids to broiler diets had neither positive nor negative effects on nutrient digestibility and final broiler performance. This indicates the feasibility of short-term thermal

  14. Uric acid or 1-methyl uric acid in the urinary bladder increases serum glucose, insulin, true triglyceride, and total cholesterol levels in Wistar rats.

    PubMed

    Balasubramanian, T

    2003-10-01

    In animals deprived of food for a long period, a drop in the fat mass below 5% of the total body mass results in an increase in blood glucocorticoids and uric acid levels, followed by foraging activity. Since the glucocorticoids increase the uric acid excretion, an increase in the level of uric acid in the bladder urine could be the signal for this feeding behaviour and subsequent fat storage. Accumulation of fat is associated with hyperglycaemia, hyperinsulinaemia, hyperlipidaemia, and hypercholesterolaemia as seen in the metabolic syndrome or hibernation. It is hypothesized that uric acid or its structurally related compound, 1-methyl uric acid (one of the metabolites of the methyl xanthines namely caffeine, theophylline, and theobromine present in coffee, tea, cocoa, and some drugs), can act on the urinary bladder mucosa and increases the blood glucose, insulin, triglyceride, and cholesterol levels. In rats, perfusion of the urinary bladder with saturated aqueous solution of uric acid or 1-methyl uric acid results in a significant increase in the serum levels of glucose, insulin, true triglyceride, and total cholesterol in comparison with perfusion of the bladder with distilled water at 20, 40, and 80 min. The uric acid or the 1-methyl uric acid acts on the urinary bladder mucosa and increases the serum glucose, insulin, true triglyceride, and total cholesterol levels. PMID:15241498

  15. Cochlear ablation effects on amino acid levels in the chinchilla cochlear nucleus.

    PubMed

    Godfrey, D A; Chen, K; Godfrey, M A; Lee, A C; Crass, S P; Shipp, D; Simo, H; Robinson, K T

    2015-06-25

    Inner ear damage can lead to hearing disorders, including tinnitus, hyperacusis, and hearing loss. We measured the effects of severe inner ear damage, produced by cochlear ablation, on the levels and distributions of amino acids in the first brain center of the auditory system, the cochlear nucleus. Measurements were also made for its projection pathways and the superior olivary nuclei. Cochlear ablation produces complete degeneration of the auditory nerve, which provides a baseline for interpreting the effects of partial damage to the inner ear, such as that from ototoxic drugs or intense sound. Amino acids play a critical role in neural function, including neurotransmission, neuromodulation, cellular metabolism, and protein construction. They include major neurotransmitters of the brain - glutamate, glycine, and γ-aminobutyrate (GABA) - as well as others closely related to their metabolism and/or functions - aspartate, glutamine, and taurine. Since the effects of inner ear damage develop over time, we measured the changes in amino acid levels at various survival times after cochlear ablation. Glutamate and aspartate levels decreased by 2weeks in the ipsilateral ventral cochlear nucleus and deep layer of the dorsal cochlear nucleus, with the largest decreases in the posteroventral cochlear nucleus (PVCN): 66% for glutamate and 63% for aspartate. Aspartate levels also decreased in the lateral part of the ipsilateral trapezoid body, by as much as 50%, suggesting a transneuronal effect. GABA and glycine levels showed some bilateral decreases, especially in the PVCN. These results may represent the state of amino acid metabolism in the cochlear nucleus of humans after removal of eighth nerve tumors, which may adversely result in destruction of the auditory nerve. Measurement of chemical changes following inner ear damage may increase understanding of the pathogenesis of hearing impairments and enable improvements in their diagnosis and treatment. PMID:25839146

  16. The effects of dietary omega fatty acids on pregnancy rate, plasma prostaglandin metabolite levels, serum progesterone levels, and milk fatty-acid profile in beef cows.

    PubMed

    Richardson, Gavin F; McNiven, Mary A; Petit, Hélène V; Duynisveld, John L

    2013-10-01

    The objectives were to determine the effects of feeding supplements rich in omega-6 or omega-3 fatty acids (FA) during the late gestation to the early postpartum and breeding periods on reproduction and milk FA profile in beef cows. For each of two years, at the beginning of period 1 (mid-December), 72 beef cows, calving in January or February, were assigned to diets supplemented with roasted flaxseed (Flax) or roasted soybean (Soybean). For each of two years, after 11 wk (end of period 1), 18 cows of 36 in the Flax group were switched to the soybean supplement and 18 cows of 36 in the Soybean group were switched to the flax supplement (start of Period 2). Cows were bred by timed artificial insemination (TAI) in week 5 of period 2. The FA composition of the milk reflected the FA profile of the oilseed supplements. There were no differences in pregnancy rates among the 4 groups. The treatments had no effect on plasma prostaglandin metabolite levels or ratios at 4 to 11 d postpartum. At 5 to 6 d post- TAI, pregnant cows fed Flax in period 1 had lower (P < 0.05) plasma prostaglandin F metabolite (PGFM) levels and PGFM to prostaglandin E metabolite (PGEM) ratio than cows fed Soybean, but there were no significant differences at 19 to 20 d post-TAI. Cows pregnant from TAI and fed Flax in period 2 had higher (P < 0.05) serum progesterone levels at 5 to 6 d post-TAI than cows fed Soybean, but there was no difference at 19 to 20 d post-TAI. The dietary treatments had no effect on pregnancy rates, but there were some effects on plasma PGFM levels, PGFM to PGEM ratios, and serum progesterone levels. The FA supplements influenced the FA composition of milk. PMID:24124276

  17. Preoperative serum docosahexaenoic acid level predicts prognosis of renal cell carcinoma

    PubMed Central

    TASAKI, SHINSUKE; HORIGUCHI, AKIO; ASANO, TAKAKO; KURODA, KENJI; SATO, AKINORI; ASAKUMA, JUNICHI; ITO, KEIICHI; ASANO, TOMOHIKO; ASAKURA, HIROTAKA

    2016-01-01

    The recent discovery and clinical development of targeted agents have expanded treatment options in metastatic renal cell carcinoma (RCC). However, metastatic RCC remains a lethal disease. Complete response is rare and treatment with targeted agents eventually fails in the majority of the patients. Therefore, there is a need for developing a prognostic tool and a novel therapeutic agent for RCC to improve the follow-up strategy after surgical treatment. Clinical data, including patient characteristics, serum fatty acid profile, clinicopathological parameters and clinical outcome, were obtained from 112 patients with RCC prior to surgical treatment. Preoperative fatty acid levels were grouped according to patient characteristics, such as performance status, body mass index or pathological parameters, and were analyzed using the Mann-Whitney U test. Cancer-specific survival in the high and low docosahexaenoic acid (DHA) level groups were compared using the Kaplan-Meier method. Cox proportional hazards models were applied to determine the independent prognostic factors associated with shortened cancer-specific survival. The serum DHA level in patients with metastasis was significantly lower compared with that in patients without metastasis (P=0.047). Low serum DHA level, presence of metastasis and cachexia were independent predictors of shortened cancer-specific survival in a multivariate Cox proportional hazard model (P=0.033, hazard ratio = 4.43). Patients with a serum DHA level below the median value exhibited significantly shorter cancer-specific survival compared with those with a higher serum DHA level (P=0.008). Thus, according to our results, the preoperative serum DHA level may be able to predict the surgical outcome of RCC. However, this finding requires validation by large-scale prospective studies. PMID:27330769

  18. Effects of Alterations of Plasma Free Fatty Acid Levels on Pancreatic Glucagon Secretion in Man

    PubMed Central

    Gerich, John E.; Langlois, Maurice; Schneider, Victor; Karam, John H.; Noacco, Claudio

    1974-01-01

    The present investigation was undertaken to ascertain whether alterations in plasma free fatty acids (FFA) affect pancreatic glucagon secretion in man since FFA have been reported to influence pancreatic alpha cell function in other species. Elevation of plasma FFA from a mean (±SE) basal level of 0.478±0.036 mM to 0.712±0.055 mM after heparin administration caused plasma glucagon levels to fall approximately 50%, from a basal value of 122±15 pg/ml to 59±14 pg/ml (P < 0.001). Lowering of plasma FFA from a basal level of 0.520±0.046 mM to 0.252±0.041 mM after nicotinic acid administration raised plasma glucagon from a basal level of 113±18 pg/ml to 168±12 pg/ml (P < 0.005). Infusion of glucose elevated plasma glucose levels to the same degree that heparin raised plasma FFA levels. This resulted in suppression of plasma glucagon despite the fact that plasma FFA levels also were suppressed. Glucagon responses to arginine were diminished after elevation of plasma FFA (P < 0.01) and during infusion of glucose (P < 0.01). Diminution of plasma FFA by nicotinic acid did not augment glucagon responses to arginine. These results thus demonstrate that rather small alterations in plasma FFA within the physiologic range have a significant effect on glucagon secretion in man. Although the effects of glucose appear to predominate over those of FFA, alterations in plasma FFA may nevertheless exert an important physiologic influence over human pancreatic alpha cell function, especially in the postabsorptive state. PMID:4825225

  19. The effects of changing dairy intake on trans and saturated fatty acid levels- results from a randomized controlled study

    PubMed Central

    2014-01-01

    Background Dairy food is an important natural source of saturated and trans fatty acids in the human diet. This study evaluates the effect of dietary advice to change dairy food intake on plasma fatty acid levels known to be present in milk in healthy volunteers. Methods Twenty one samples of whole fat dairy milk were analyzed for fatty acids levels. Changes in levels of plasma phospholipid levels were evaluated in 180 healthy volunteers randomized to increase, not change or reduce dairy intake for one month. Fatty acids were measured by gas chromatography–mass spectrometry and levels are normalized to d-4 alanine. Results The long chain fatty acids palmitic (13.4%), stearic (16.7%) and myristic (18.9%) acid were most common saturated fats in milk. Four trans fatty acids constituted 3.7% of the total milk fat content. Increased dairy food intake by 3.0 (± 1.2) serves/ day for 1 month was associated with small increases in plasma levels of myristic (+0.05, 95% confidence level-0.08 to 0.13, p = 0.07), pentadecanoic (+0.014, 95% confidence level -0.016 to 0.048, p = 0.02) and margaric acid (+0.02, -0.03 to 0.05, p = 0.03). There was no significant change in plasma levels of 4 saturated, 4 trans and 10 unsaturated fatty acids. Decreasing dairy food intake by 2.5 (± 1.2) serves per day was not associated with change in levels of any plasma fatty acid levels. Conclusion Dietary advice to change dairy food has a minor effect on plasma fatty acid levels. Trial registration ACTRN12612000574842. PMID:24708591

  20. Amino acid and vascular endothelial growth factor levels in subretinal fluid in rhegmatogenous retinal detachment

    PubMed Central

    Buyukuysal, Rifat Levent; Gelisken, Oner; Buyukuysal, Cagatay; Can, Basak

    2014-01-01

    Purpose To study the concentrations of amino acids and vascular endothelial growth factor (VEGF) in subretinal fluid (SRF) of cases with rhegmatogenous retinal detachment (RRD). The relevance of the results with postoperative anatomic and functional success in RRD was investigated. Methods Fifty-three patients were included in this prospective study. The study group consisted of 46 patients who had scleral buckling surgery with the diagnosis of RRD, and SRF was obtained during the surgery. The control specimens consisted of vitreous samples of seven patients who were diagnosed with pars plana vitrectomy without RRD. Study cases were divided into three groups, corresponding to the duration of retinal detachment. Clinical characteristics, including best corrected visual acuity (BCVA) and anatomic status at month 6, were recorded. Concentrations of 15 selected amino acids were quantified by using high performance liquid chromatography, and VEGF levels were measured with enzyme immunoassay. Results When compared with the control group, SRF concentrations of aspartate, citrulline, glutamate, and glycine increased significantly in the study group (p<0.05). Statistical analysis showed that concentrations of alanine, isoleucine, leucine, methionine, phenylalanine, threonine, tyrosine, and valine decreased (p<0.05). SRF levels of glutamine, taurine, and serine had no significant change. SRF VEGF levels were significantly higher than the vitreous samples of the controls (p<0.001). Time-dependent changes and interactions between VEGF and amino acids were observed. There was no correlation between the concentrations of amino acids or VEGF with the parameters of BCVA and anatomical success. Conclusions Significant changes occur in concentrations of amino acids and VEGF in SRF of cases with RRD. Our results suggest that several mechanisms contribute to the pathophysiology. PMID:25352742

  1. Genome-Wide Analysis of Branched-Chain Amino Acid Levels in Arabidopsis Seeds[W

    PubMed Central

    Angelovici, Ruthie; Lipka, Alexander E.; Deason, Nicholas; Gonzalez-Jorge, Sabrina; Lin, Haining; Cepela, Jason; Buell, Robin; Gore, Michael A.; DellaPenna, Dean

    2013-01-01

    Branched-chain amino acids (BCAAs) are three of the nine essential amino acids in human and animal diets and are important for numerous processes in development and growth. However, seed BCAA levels in major crops are insufficient to meet dietary requirements, making genetic improvement for increased and balanced seed BCAAs an important nutritional target. Addressing this issue requires a better understanding of the genetics underlying seed BCAA content and composition. Here, a genome-wide association study and haplotype analysis for seed BCAA traits in Arabidopsis thaliana revealed a strong association with a chromosomal interval containing two BRANCHED-CHAIN AMINO ACID TRANSFERASES, BCAT1 and BCAT2. Linkage analysis, reverse genetic approaches, and molecular complementation analysis demonstrated that allelic variation at BCAT2 is responsible for the natural variation of seed BCAAs in this interval. Complementation analysis of a bcat2 null mutant with two significantly different alleles from accessions Bayreuth-0 and Shahdara is consistent with BCAT2 contributing to natural variation in BCAA levels, glutamate recycling, and free amino acid homeostasis in seeds in an allele-dependent manner. The seed-specific phenotype of bcat2 null alleles, its strong transcription induction during late seed development, and its subcellular localization to the mitochondria are consistent with a unique, catabolic role for BCAT2 in BCAA metabolism in seeds. PMID:24368787

  2. Evaluation of Warm Acid Strike Treatment for Silicon Analysis in High Level Waste

    SciTech Connect

    Pennebaker, F.M.

    2003-03-20

    Savannah River Technology Center (SRTC) has developed a simpler, faster and more accurate method of analysis for the measurement of silicon in High Level Waste (HLW) supernate samples prior to evaporation. The warm acid strike method compared favorably to the current filtration method in the measurement of five samples from three different waste tanks. The technical enhancement of the warm acid strike method is that it will help dissolve small solid particles of silicon-bearing materials that contribute to the scatter in measurements. The method is not intended to measure silicon in samples that have significant quantities of entrained waste tank sludge or DWPF frit particles. Since the method is simple, multiple waste tank samples can be prepared and analyzed at the same time. This improvement should significantly reduce turnaround time for Evaporator Qualification samples at SRTC. Enhanced QC and blind standards have been incorporated into the method for better traceability and overall accuracy. ADS recommends that High Level Waste switch to the Acid Strike Methodology using 3 M acid and 4 hours of heating for Evaporator Qualification samples as soon as possible. Extra work is necessary before transfer of the method to C-Lab for routine measurements.

  3. Mutations in a novel 9-stearoyl-ACP-desaturase gene are associated with enhanced stearic acid levels in soybean seeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stearic acid (18:0) is typically a minor component of soybean [Glycine max (L.) Merr.] oil, accounting for only 2-4 % of the total fatty acid content. Increasing stearic acid levels of soybean oil would lead to enhanced oxidative stability, potentially reducing the need for hydrogenation, a process...

  4. Identification of 11-Nor-delta9-tetrahydrocannabinol-9-carboxylic acid in urine by ion trap GC-MS-MS in the context of doping analysis.

    PubMed

    Caballero, Gerardo M; D'Angelo, Carlos; Fraguío, Mariá Sol; Centurión, Osvaldo Teme

    2004-01-01

    The purpose of this study is to develop a sensitive and specific alternative to current gas chromatography (GC)-mass spectrometry (MS) selected ion monitoring confirmation methods of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (cTHC) in human urine samples, in the context of doping analysis. An identification procedure based on the comparison, among suspicious and control samples, of the relative abundances of cTHC selected product ions obtained by GC-tandem MS in an ion trap is presented. The method complies with the identification criteria for qualitative assays established by sports authorities; the comparison procedure is precise, reproducible, specific, and sensitive, thus indicating that it is fit for the purpose of identification accordingly to World Antidoping Agency requirements. PMID:15768841

  5. Postoperative enteral hyperalimentation results in earlier elevation of serum branched-chain amino acid levels.

    PubMed

    Moss, G; Naylor, E D

    1994-07-01

    To objectively document the immediate maintenance and successful exploitation of postoperative gastrointestinal (GI) function, elemental diet was infused into the more distal duodenum of 30 cholecystectomy patients at 300 kcal per hour, beginning on arrival at the recovery room. Approximately 4,600 kcal and 190 grams of amino acids were absorbed during the initial 16 hours. Serum branched-chain amino acids (BCAAs) had risen above basal levels at 4 hours, statistically significant only for leucine (+64%). The higher concentrations had reached statistical significance for all BCAAs by 6 hours, when leucine had risen by 83%, isoleucine by 54%, and valine by 47%. The elevated BCAA and glucose levels sustained throughout the hyperalimentation period objectively verify that postoperative GI function can be safely exploited, and may contribute to improved wound healing and sepsis resistance. PMID:8024096

  6. Controlling of group velocity via terahertz signal radiation in a defect medium doped by four-level InGaN/GaN quantum dot nanostructure

    NASA Astrophysics Data System (ADS)

    Jafarzadeh, Hossein; Sangachin, Elnaz Ahmadi; Asadpour, Seyyed Hossein

    2015-07-01

    In this paper, we propose a novel scheme for controlling the group velocity of transmitted and reflected pulse from defect medium doped with four-level InGaN/GaN quantum dot nanostructure. Quantum dot nanostructure is designed numerically by Schrödinger and Poisson equations which solve self consistently. By size control of quantum dot and external voltage, one can design a four-level quantum dot with appropriate energy levels which can be suitable for controlling the group velocity of pulse transmission and reflection from defect slab with terahertz signal field. It is found that in the presence and absence of terahertz signal field the behaviors of transmission and reflection pulses are completely different. Moreover, it is shown that for strong terahertz signal field, by changing the thickness of the slab, simultaneous peak and dip for transmission and reflection pulse are obtained.

  7. Highly selective and effective solid phase microextraction of benzoic acid esters using ionic liquid functionalized multiwalled carbon nanotubes-doped polyaniline coating.

    PubMed

    Ai, Youhong; Wu, Mian; Li, Lulu; Zhao, Faqiong; Zeng, Baizhao

    2016-03-11

    The present work reports the electrochemical fabrication of an ionic liquid functionalized multiwalled carbon nanotubes-polyaniline (MWCNT@IL/PANI) nanocomposite coating and its application in the headspace-solid phase microextraction (HS-SPME) and gas chromatography (GC) determination of benzoic acid esters (i.e., methyl benzoate, ethyl benzoate, propyl benzoate and butyl benzoate). The MWCNTs was firstly functionalized with amine-terminated IL (MWCNT@IL) through chemical reduction, and then was doped in PANI during the electropolymerization of aniline. The resulting coating was characterized by infrared spectroscopy, field emission scanning electron microscopy and thermo gravimetry. It showed net-like structure and had high thermal stability (up to 330°C). Furthermore, it presented high selectivity for the four benzoic acid esters and thus suited for their HS-SPME-GC determination. Results showed that under optimized extraction conditions, the detection limits were less than 6.1ngL(-1) (S/N=3) and the linear detection ranges were 0.012-50μgL(-1) (R≥0.9957) for these analytes. The relative standard deviations (RSDs) were lower than 6.4% for five successive measurements with one fiber, and the RSDs for fiber-to-fiber were 4.4-9.6% (n=5). The developed method was successfully applied to the determination of these benzoic acid esters in perfume samples. PMID:26852620

  8. Nanocrystalline semiconductor doped rare earth oxide for the photocatalytic degradation studies on Acid Blue 113: A di-azo compound under UV slurry photoreactor.

    PubMed

    Suganya Josephine, G A; Mary Nisha, U; Meenakshi, G; Sivasamy, A

    2015-11-01

    Preventive measures for the control of environmental pollution and its remediation has received much interest in recent years due to the world-wide increase in the contamination of water bodies. Contributions of these harmful effluents are caused by the leather processing, pharmaceutical, cosmetic, textile, agricultural and other chemical industries. Nowadays, advanced oxidation processes considered to be better option for the complete destruction of organic contaminants in water and wastewater. Acid Blue 113 is a most widely used di-azo compound in leather, textile, dying and food industry as a color rending compound. In the present study, we have reported the photo catalytic degradation of Acid Blue 113 using a nanocrystalline semiconductor doped rare earth oxide as a photo catalyst under UV light irradiation. The photocatalyst was prepared by a simple precipitation technique and were characterized by XRD, FT-IR, UV-DRS and FE-SEM analysis. The experimental results proved that the prepared photo catalyst was nanocrystalline and highly active in the UV region. The UV-DRS results showed the band gap energy was 3.15eV for the prepared photo catalyst. The photodegradation efficiency was analyzed by various experimental parameters such as pH, catalyst dosage, variation of substrate concentration and effect of electrolyte addition. The photo degradation process followed a pseudo first order kinetics and was continuously monitored by UV-visible spectrophotometer. The experimental results proved the efficacy of the nanocrystalline zinc oxide doped dysprosium oxide which are highly active under UV light irradiations. It is also suggested that the prepared material would find wider applications in environmental remediation technologies to remove the carcinogenic and toxic moieties present in the industrial effluents. PMID:26025644

  9. Increased tachykinin levels in induced sputum from asthmatic and cough patients with acid reflux

    PubMed Central

    Patterson, Robert N; Johnston, Brian T; Ardill, Joy E S; Heaney, Liam G; McGarvey, Lorcan P A

    2007-01-01

    Background Acid reflux may aggravate airway disease including asthma and chronic cough. One postulated mechanism concerns a vagally‐mediated oesophageal‐tracheobronchial reflex with airway sensory nerve activation and tachykinin release. Aim To test the hypothesis that patients with airways disease and reflux have higher airway tachykinin levels than those without reflux. Methods Thirty‐two patients with airways disease (16 with mild asthma and 16 non‐asthmatic subjects with chronic cough) underwent 24 h oesophageal pH monitoring. Acid reflux was defined as increased total oesophageal acid exposure (% total time pH <4 of >4.9% at the distal probe). All subjects underwent sputum induction. Differential cell counts and concentrations of substance P (SP), neurokinin A (NKA), albumin and α2‐macroglobulin were determined. Results SP and NKA levels were significantly higher in patients with reflux than in those without (SP: 1434 (680) pg/ml vs 906 (593) pg/ml, p = 0.026; NKA: 81 (33) pg/ml vs 52 (36) pg/ml, p = 0.03). Significantly higher tachykinin levels were also found in asthmatic patients with reflux than in asthmatic patients without reflux (SP: 1508 (781) pg/ml vs 737 (512) pg/ml, p = 0.035; NKA: median (interquartile range 108 (85–120) pg/ml vs 75 (2–98) pg/ml, p = 0.02). In patients with asthma there was a significant positive correlation between distal oesophageal acid exposure and SP levels (r = 0.59, p = 0.01) and NKA levels (r = 0.56, p = 0.02). Non‐significant increases in SP and NKA were measured in patients with cough with reflux (SP: 1534.71 (711) pg/ml vs 1089 (606) pg/ml, p = 0.20; NKA: 56 (43) pg/ml vs 49 (17) pg/ml, p = 0.71). No significant difference in differential cell counts or any other biochemical parameter was noted between study groups. Conclusion This study demonstrates increased airway tachykinin levels in patients with asthma and cough patients with

  10. Ascorbic acid serum levels are reduced in patients with hematological malignancies

    PubMed Central

    Huijskens, Mirelle J.A.J.; Wodzig, Will K.W.H.; Walczak, Mateusz; Germeraad, Wilfred T.V.; Bos, Gerard M.J.

    2016-01-01

    In this paper we demonstrate that patients treated with chemotherapy and/or hematopoietic stem cell transplantation (HSCT) have highly significant reduced serum ascorbic acid (AA) levels compared to healthy controls. We recently observed in in vitro experiments that growth of both T and NK cells from hematopoietic stem cells is positively influenced by AA. It might be of clinical relevance to study the function and recovery of immune cells after intensive treatment, its correlation to AA serum levels and the possible effect of AA supplementation. PMID:27014565

  11. Association of androgen with gender difference in serum adipocyte fatty acid binding protein levels

    PubMed Central

    Hu, Xiang; Ma, Xiaojing; Pan, Xiaoping; Luo, Yuqi; Xu, Yiting; Xiong, Qin; Bao, Yuqian; Jia, Weiping

    2016-01-01

    Clinical investigations have indicated women have higher levels of adipocyte fatty acid binding protein (A-FABP) than men. The present study aimed to identify factors related to gender difference in serum A-FABP levels. A total of 507 participants (194 men, 132 premenopausal women, and 181 postmenopausal women) were enrolled in the present study. Serum A-FABP levels increased in the order from men to premenopausal women to postmenopausal women in both body mass index categories (<25.0 and ≥25.0 kg/m2; all P < 0.05). Multiple stepwise regression analyses showed that after adjustment for factors related to serum A-FABP levels, the trunk fat mass was an independent and positive factor of serum A-FABP levels. For men, total testosterone was associated independently and inversely with serum A-FABP levels. For pre- and postmenopausal women, bioavailable testosterone and total testosterone were independent and positive factors associated with serum A-FABP levels, respectively. The present study demonstrated that the androgen was correlated with the serum A-FABP levels negatively in men, but positively in women. With these effects on the fat content, especially trunk fat, androgen might contribute to the gender difference in serum A-FABP levels. PMID:27270834

  12. Association of androgen with gender difference in serum adipocyte fatty acid binding protein levels.

    PubMed

    Hu, Xiang; Ma, Xiaojing; Pan, Xiaoping; Luo, Yuqi; Xu, Yiting; Xiong, Qin; Bao, Yuqian; Jia, Weiping

    2016-01-01

    Clinical investigations have indicated women have higher levels of adipocyte fatty acid binding protein (A-FABP) than men. The present study aimed to identify factors related to gender difference in serum A-FABP levels. A total of 507 participants (194 men, 132 premenopausal women, and 181 postmenopausal women) were enrolled in the present study. Serum A-FABP levels increased in the order from men to premenopausal women to postmenopausal women in both body mass index categories (<25.0 and ≥25.0 kg/m(2); all P < 0.05). Multiple stepwise regression analyses showed that after adjustment for factors related to serum A-FABP levels, the trunk fat mass was an independent and positive factor of serum A-FABP levels. For men, total testosterone was associated independently and inversely with serum A-FABP levels. For pre- and postmenopausal women, bioavailable testosterone and total testosterone were independent and positive factors associated with serum A-FABP levels, respectively. The present study demonstrated that the androgen was correlated with the serum A-FABP levels negatively in men, but positively in women. With these effects on the fat content, especially trunk fat, androgen might contribute to the gender difference in serum A-FABP levels. PMID:27270834

  13. Serum uric acid levels in patients with infections of central nervous system.

    PubMed

    Liu, Jia; Li, Min; Wang, Xuan; Yi, Huan; Xu, Li; Zhong, Xiu-Feng; Peng, Fu-Hua

    2016-09-01

    The lower levels of serum uric acid (UA) correlated with meningitis have been reported. However, comparison of UA levels among different kinds of infections of central nervous system (CNS) and changes of UA levels before and after treatment are unknown. Our study aimed to investigate the antioxidant status of serum UA in five common types of CNS infections. We retrospectively evaluated serum UA levels of 399 patients with different types of CNS infections including viral meningitis or meningoencephalitis (VM), brain cysticercosis (BC), tuberculous meningitis or meningoencephalitis (TM), cryptococcus meningitis or meningoencephalitis (CM) and bacterial meningitis or meningoencephalitis (BM), and 119 healthy controls. The changes of serum UA were examined and analyzed. The serum levels of UA in patients with CNS infections were significantly lower than those in normal subjects and among in TM, CM and BM groups were apparently lower when compared with VM and BC groups; otherwise, after effective therapy, serum UA levels were obviously higher than before. Our findings showed that patients with CNS infections had lower serum UA levels, which was independent of the classification and the serum UA levels increased obviously after valid treatment, the variation of UA levels might be considered as an indicator of clinical curative effect in patients with CNS infections. PMID:26612048

  14. Association between delta-aminolevulinic acid dehydratase polymorphism and placental lead levels.

    PubMed

    Kayaaltı, Zeliha; Sert, Selda; Kaya-Akyüzlü, Dilek; Söylemez, Esma; Söylemezoğlu, Tülin

    2016-01-01

    Lead inhibits the delta-aminolevulinic acid dehydratase (ALAD) activity and results in neurotoxic aminolevulinic acid accumulation in the blood. During pregnancy, lead in the maternal blood can easily cross the placenta. The aim of this study was to determine whether the maternal ALAD G177C polymorphism (rs1800435) was related to the placental lead levels. The study population comprised 97 blood samples taken from mothers to investigate ALAD G177C polymorphism and their placentas to measure lead levels. ALAD G177C polymorphism was detected by standard polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) technique and atomic absorption spectrometry (AAS) equipped with a graphite furnace and Zeeman background correction system was used for lead determination. The median placental lead levels for ALAD1-1, ALAD1-2 and ALAD2-2 genotypes were 7.54 μg/kg, 11.78 μg/kg and 18.53 μg/kg, respectively. Statistically significant association was found between the maternal ALAD G177C polymorphism and placental lead levels (p<0.05). This study suggested that maternal ALAD G177C polymorphism was associated with placental lead levels. PMID:26701682

  15. Impact of HIV Infection and Zidovudine Therapy on RBC Parameters and Urine Methylmalonic Acid Levels

    PubMed Central

    Adediran, Adewumi; Osunkalu, Vincent; Wakama, Tamunomieibi; John-Olabode, Sarah; Akinbami, Akinsegun; Uche, Ebele; Akanmu, Sulaimon

    2016-01-01

    Background. Anaemia is a common complication of human immunodeficiency virus (HIV) infection. The aim of this study was to investigate the impact of HIV infection and zidovudine on red blood cells (RBC) parameters and urine methylmalonic acid (UMMA) levels in patients with HIV infection. Material and Methods. A cross-sectional study involving 114 subjects, 94 of which are HIV-infected nonanaemic and 20 HIV negative subjects (Cg) as control. Full blood count parameters and urine methylmalonic acid (UMMA) level of each subject were determined. Associations were determined by Chi-square test and logistic regression statistics where appropriate. Results. Subjects on zidovudine-based ART had mean MCV (93 fL) higher than that of control group (82.9 fL) and ART-naïve (85.9 fL) subjects and the highest mean RDW. Mean UMMA level, which reflects vitamin B12 level status, was high in all HIV-infected groups but was significantly higher in ART-naïve subjects than in ART-experienced subjects. Conclusion. Although non-zidovudine therapy may be associated with macrocytosis (MCV > 95 fL), zidovudine therapy and ART naivety may not. Suboptimal level of vitamin B12 as measured by high UMMA though highest in ART-naïve subjects was common in all HIV-infected subjects. PMID:26989408

  16. Impact of HIV Infection and Zidovudine Therapy on RBC Parameters and Urine Methylmalonic Acid Levels.

    PubMed

    Adediran, Adewumi; Osunkalu, Vincent; Wakama, Tamunomieibi; John-Olabode, Sarah; Akinbami, Akinsegun; Uche, Ebele; Akanmu, Sulaimon

    2016-01-01

    Background. Anaemia is a common complication of human immunodeficiency virus (HIV) infection. The aim of this study was to investigate the impact of HIV infection and zidovudine on red blood cells (RBC) parameters and urine methylmalonic acid (UMMA) levels in patients with HIV infection. Material and Methods. A cross-sectional study involving 114 subjects, 94 of which are HIV-infected nonanaemic and 20 HIV negative subjects (Cg) as control. Full blood count parameters and urine methylmalonic acid (UMMA) level of each subject were determined. Associations were determined by Chi-square test and logistic regression statistics where appropriate. Results. Subjects on zidovudine-based ART had mean MCV (93 fL) higher than that of control group (82.9 fL) and ART-naïve (85.9 fL) subjects and the highest mean RDW. Mean UMMA level, which reflects vitamin B12 level status, was high in all HIV-infected groups but was significantly higher in ART-naïve subjects than in ART-experienced subjects. Conclusion. Although non-zidovudine therapy may be associated with macrocytosis (MCV > 95 fL), zidovudine therapy and ART naivety may not. Suboptimal level of vitamin B12 as measured by high UMMA though highest in ART-naïve subjects was common in all HIV-infected subjects. PMID:26989408

  17. Blood levels of ammonia and nitrogen scavenging amino acids in patients with inherited hyperammonemia.

    PubMed

    Tuchman, M; Yudkoff, M

    1999-01-01

    Plasma levels of glutamine (456 determinations), alanine (434 determinations), and asparagine (431 determinations) and corresponding ammonia levels (260 determinations) were retrospectively analyzed in 30 patients with hyperammonemia secondary to urea cycle disorders (including 3 patients with amino acid transport defects) and 5 patients with propionic acidemia (PA). All patients had elevated glutamine levels on one or more testing except for 2 patients with severe PA and 1 patient with a mild urea cycle disorder. All but 4 patients with urea cycle disorders showed a maximal glutamine level higher than 100 micromol/dl, and 3 patients had a maximal glutamine level of higher than 200 micromol/dl. The only exceptions were 2 asymptomatic ornithine transcarbamylase (OTC)-deficient females, 1 male with mild OTC deficiency, and 1 patient with citrullinemia (CIT) whose plasma glutamine levels were never above 100 micromol/L. Patients with CIT and argininosuccinic aciduria (ASA) showed statistically significant lower levels of glutamine than patients with other urea cycle disorders. However, the maximal glutamine level did not directly correlate with severity of the disorder and within disorders correlated inversely with severity of outcome. Patients with PA showed statistically significant lower glutamine, alanine, and asparagine levels than patients with urea cycle disorders and the severity of this disorder correlated inversely with plasma glutamine levels. Plasma ammonia levels showed a positive correlation with glutamine in patients with carbamyl phosphate synthetase I and OTC deficiency and a negative correlation in patients with PA. Although, most patients also showed elevated levels of alanine and asparagine, their levels generally did not show a good correlation with glutamine (R2 = 0.25 and 0.34, respectively). PMID:9973542

  18. Effects of folic acid supplementation on serum homocysteine and lipoprotein (a) levels during pregnancy

    PubMed Central

    Hekmati Azar Mehrabani, Zohreh; Ghorbanihaghjo, Amir; Sayyah Melli, Manizheh; Hamzeh-Mivehroud, Maryam; Fathi Maroufi, Nazila; Bargahi, Nasrin; Bannazadeh Amirkhiz, Maryam; Rashtchizadeh, Nadereh

    2015-01-01

    Introduction:There are many ideas concerning the etiology and pathogenesis of preeclampsia including endothelial dysfunction, inflammation and angiogenesis. Elevated levels of total homocysteine (Hcy) and lipoprotein (a) [Lp(a)] are risk factors for endothelial dysfunction. This study aimed to evaluate the effect of high dose folic acid (FA) on serum Hcy and Lp(a) concentrations with respect to methylenetetrahydrofolate reductase (MTHFR) polymorphisms 677C→T during pregnancy. Methods: In a prospective uncontrolled intervention, 90 pregnant women received 5 mg FA supplementation before pregnancy till 36th week of pregnancy. The MTHFR polymorphisms 677C→T, serum lactate dehydrogenase activity, urine protein and creatinine concentrations were measured before starting folic acid administration. Serum levels of Hcy and Lp(a) were determined before and after completion of folic acid supplementation period. Results: Supplementation of the patients with FA for 36 week decreased the median (minimum– maximum) levels of serum Hcy from 11.40 μmol/L (4.40-28.70) to 9.70 (1.60-20.80) μmol/L (p=0.001). There was no significant change in serum Lp(a) after FA supplementation (p=0.17). The overall prevalence of genotypes in pregnant women that were under study for MTHFR C677T polymorphism was 53.3% CC, 26.7% CT and 20.0% TT. There was no correlation between decreasing level of serum Hcy in the patients receiving FA and MTHFR polymorphisms. Conclusion:Although FA supplementation decreased serum levels of Hcy in different MTHFR genotypes, serum Lp(a) was not changed by FA supplements. Our data suggests that FA supplementation effects on serum Hcy is MTHFR genotype independent in pregnant women. PMID:26929921

  19. Recombination luminescence and trap levels in undoped and Al-doped ZnO thin films on quartz and GaSe (0 0 0 1) substrates

    SciTech Connect

    Evtodiev, I.; Caraman, I.; Leontie, L.; Rusu, D.-I.; Dafinei, A.; Nedeff, V.; Lazar, G.

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer ZnO films on GaSe create electron trapping states and PL recombination levels. Black-Right-Pointing-Pointer Zn and Al diffusion in GaSe produces low-energy widening of its PL emission. Black-Right-Pointing-Pointer ZnO:Al films on GaSe lamellas are suitable for gas-discharge lamp applications. -- Abstract: Photoluminescence spectra of ZnO and ZnO:Al (1.00, 2.00 and 5.00 at.%) films on GaSe (0 0 0 1) lamellas and amorphous quartz substrates, obtained by annealing, at 700 K, of undoped and Al-doped metal films, are investigated. For all samples, the nonequilibrium charge carriers recombine by radiative band-to-band transitions with energy of 3.27 eV, via recombination levels created by the monoionized oxygen atoms, forming the impurity band laying in the region 2.00 - 2.70 eV. Al doping induces an additional recombination level at 1.13 eV above the top of the valence band of ZnO films on GaSe substrates. As a result of thermal diffusion of Zn and Al into the GaSe interface layer from ZnO:Al/GaSe heterojunction, electron trap levels located at 0.22 eV and 0.26 eV below the conduction band edge of GaSe, as well as a deep recombination level, responsible for the luminescent emission in the region 1.10 - 1.40 eV, are created.

  20. Acid-labile mPEG-Vinyl Ether-1,2-Dioleylglycerol Lipids with Tunable pH Sensitivity: Synthesis and Structural Effects on Hydrolysis Rates, DOPE Liposome Release Performance and Pharmacokinetics

    PubMed Central

    Shin, Junhwa; Shum, Pochi; Grey, Jessica; Fujiwara, Shin-ichi; Malhotra, Guarov S.; González-Bonet, Andres; Hyun, Seok-Hee; Moase, Elaine; Allen, Theresa M.; Thompson, David H.

    2012-01-01

    A family of 3-methoxypoly(ethylene glycol)-vinyl ether-1,2-dioleylglycerol (mPEG-VE-DOG) lipopolymer conjugates, designed on the basis of DFT calculations to possess a wide range of proton affinities, was synthesized and tested for their hydrolysis kinetics in neutral and acidic buffers. Extruded ~100 nm liposomes containing these constructs in ≥90 mol% 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) produced dispersions that retained their calcein cargo for more than 2 days at pH 7.5, but released the encapsulated contents over a wide range of timescales as a function of the electronic properties of the vinyl ether linkage, the solution pH and the mPEG-VE-DOG composition in the membrane. The in vivo performance of two different 90:10 DOPE:mPEG-VE-DOG compositions was also evaluated for blood circulation time and biodistribution in mice, using 125I-tyraminylinulin as a label. The pharmacokinetic profiles gave a T1/2 of 7 h and 3 h for 90:10 DOPE:ST302 and 90:10 DOPE:ST502, respectively, with the liposomes being cleared predominantly by liver and spleen uptake. The behavior of these DOPE:mPEG-VE-DOG formulations is consistent with their relative rates of vinyl ether hydrolysis, i.e., the more acid-sensitive mPEG-VE-DOG derivatives produce faster leakage rates from DOPE:mPEG-VE-DOG liposomes, but decreased the blood circulation times in mice. These findings suggest that the vinyl ether-based PEG-lipid derivatives are promising agents for stabilizing acid-sensitive DOPE liposomes to produce formulations with a priori control over their pH-responsiveness in vitro. Our data also suggest, however, that the same factors that contribute to enhanced acid-sensitivity of the DOPE:mPEG-VE-DOG dispersions are also likely responsible for their reduced pharmacokinetic profiles. PMID:23030381

  1. Acid-labile mPEG-vinyl ether-1,2-dioleylglycerol lipids with tunable pH sensitivity: synthesis and structural effects on hydrolysis rates, DOPE liposome release performance, and pharmacokinetics.

    PubMed

    Shin, Junhwa; Shum, Pochi; Grey, Jessica; Fujiwara, Shin-ichi; Malhotra, Guarov S; González-Bonet, Andres; Hyun, Seok-Hee; Moase, Elaine; Allen, Theresa M; Thompson, David H

    2012-11-01

    A family of 3-methoxypoly(ethylene glycol)-vinyl ether-1,2-dioleylglycerol (mPEG-VE-DOG) lipopolymer conjugates, designed on the basis of DFT calculations to possess a wide range of proton affinities, was synthesized and tested for their hydrolysis kinetics in neutral and acidic buffers. Extruded ∼100 nm liposomes containing these constructs in ≥90 mol % 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) produced dispersions that retained their calcein cargo for more than 2 days at pH 7.5, but released the encapsulated contents over a wide range of time scales as a function of the electronic properties of the vinyl ether linkage, the solution pH, and the mPEG-VE-DOG composition in the membrane. The in vivo performance of two different 90:10 DOPE:mPEG-VE-DOG compositions was also evaluated for blood circulation time and biodistribution in mice, using (125)I-tyraminylinulin as a label. The pharmacokinetic profiles gave a t(1/2) of 7 and 3 h for 90:10 DOPE:ST302 and 90:10 DOPE:ST502, respectively, with the liposomes being cleared predominantly by liver and spleen uptake. The behavior of these DOPE:mPEG-VE-DOG formulations is consistent with their relative rates of vinyl ether hydrolysis, i.e., the more acid-sensitive mPEG-VE-DOG derivatives produced faster leakage rates from DOPE:mPEG-VE-DOG liposomes, but decreased the blood circulation times in mice. These findings suggest that the vinyl ether-based PEG-lipid derivatives are promising agents for stabilizing acid-sensitive DOPE liposomes to produce formulations with a priori control over their pH responsiveness in vitro. Our data also suggest, however, that the same factors that contribute to enhanced acid sensitivity of the DOPE:mPEG-VE-DOG dispersions are also likely responsible for their reduced pharmacokinetic profiles. PMID:23030381

  2. Low-ppm-Level colorimetric acid detection using gold nanoparticles with electro-steric stabilization.

    PubMed

    Bae, Doo Ri; Lee, You-Jin; Lee, Sung Woo; Han, Young-Kyu; Yoon, Jae-Sik; Lee, Ji-Hyun; Lee, Sang-Gil; Chang, Ki Soo; Yi, Gi-Ra; Lee, Gaehang

    2014-12-01

    Electro-sterically stabilized gold suspensions were employed in a colorimetric system for the detection of strong acid in water. Using oleyamine and oleic acid as steric stabilizer in 1,2-dichlorobenzene, hydrophobic gold nanoparticles were first synthesized by a reduction reaction of gold salts and were then transferred into water with a cationic surfactant. When the hydrochlo- ric acid solution higher than critical concentration was injected, particles were quickly aggregated and precipitated, creating a clear solution from the colored suspension. The particles were stable against chemical etching by corrosive ion such as chloride. Critical concentration was dependent of the size and concentration of the particles. The minimum concentration of dramatic color change was at 5 ppm level of hydrochloric acid, in which the largest colloidal gold nanoparticles (54 nm) were used. Furthermore, because of their steric repulsive soft layer on particles, particles could be reused for further detection experiments after regeneration by the simple pH-neutralization and washing process. PMID:25971086

  3. Association of elevated levels of cellular lipoteichoic acids of group B streptococci with human neonatal disease.

    PubMed Central

    Nealon, T J; Mattingly, S J

    1983-01-01

    Cell-associated lipoteichoic acids (LTAs) from late-exponential-phase cultures (serotypes Ia, Ib, Ic, II, and III) of group B streptococci isolated from infected and asymptomatically colonized infants were quantitated and characterized by growing the organisms in a chemically defined medium containing [3H]glycerol and [14C]acetate. Cell pellets were extracted with 45% aqueous phenol and chloroform-methanol and subjected to DEAE-Sephacel anion-exchange chromatography. Elution profiles resolved three major peaks, I, II, and III, with glycerol and phosphate present in a 1:1 molar ratio in each peak, and results obtained by Ouchterlony immunodiffusion analysis confirmed the presence of poly(glycerol phosphate). Saponification indicated that [14C]acetate was incorporated into fatty acids of peaks I and II only, suggesting that these were cell-associated LTAs. Peak II was of small molecular weight (less than 10,000) and probably represented another species of LTA. Peaks I and II were further demonstrated to be LTA by their ability to sensitize human type O erythrocytes. Peak III lacked fatty acids and was shown to probably be deacylated LTA. Quantitation of cell-associated teichoic acid material produced by the group B streptococcal strains indicated that the clinical isolates from infants with early- or late-onset disease possessed significantly higher levels than did the asymptomatic (clinical isolates from infants without symptoms of disease) group B streptococcal strains. Images PMID:6341233

  4. Postprandial Levels of Branch Chained and Aromatic Amino Acids Associate with Fasting Glycaemia.

    PubMed

    Ottosson, Filip; Ericson, Ulrika; Almgren, Peter; Nilsson, Jeanette; Magnusson, Martin; Fernandez, Céline; Melander, Olle

    2016-01-01

    High fasting plasma concentrations of isoleucine, phenylalanine, and tyrosine have been associated with increased risk of hyperglycaemia and incidence of type 2 diabetes. Whether these associations are diet or metabolism driven is unknown. We examined how the dietary protein source affects the postprandial circulating profile of these three diabetes associated amino acids (DMAAs) and tested whether the postprandial DMAA profiles are associated with fasting glycaemia. We used a crossover design with twenty-one healthy individuals and four different isocaloric test meals, containing proteins from different dietary sources (dairy, fish, meat, and plants). Analysis of the postprandial DMAAs concentrations was performed using targeted mass spectrometry. A DMAA score was defined as the sum of all the three amino acid concentrations. The postprandial area under the curve (AUC) of all the three amino acids and the DMAA score was significantly greater after intake of the meal with dairy protein compared to intake of the three other meals. The postprandial AUC for the DMAA score and all the three amino acids strongly associated with fasting glucose level and insulin resistance. This indicates the importance of the postprandial kinetics and metabolism of DMAAs in understanding the overall association between DMAAs and glycaemia. PMID:27274867

  5. Increased tissue levels of omega-3 polyunsaturated fatty acids prevents pathological preterm birth.

    PubMed

    Yamashita, Aki; Kawana, Kei; Tomio, Kensuke; Taguchi, Ayumi; Isobe, Yosuke; Iwamoto, Ryo; Masuda, Koji; Furuya, Hitomi; Nagamatsu, Takeshi; Nagasaka, Kazunori; Arimoto, Takahide; Oda, Katsutoshi; Wada-Hiraike, Osamu; Yamashita, Takahiro; Taketani, Yuji; Kang, Jing X; Kozuma, Shiro; Arai, Hiroyuki; Arita, Makoto; Osuga, Yutaka; Fujii, Tomoyuki

    2013-01-01

    Omega-3 polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) have anti-inflammatory effects. Preterm birth is an important problem in modern obstetrics and one of the main causes is an inflammation. We here showed that abundance of omega-3 fatty acids reduced the incidence of preterm birth induced by LPS with fat-1 mice, capable of converting omega-6 to omega-3 fatty acids. We also indicated that the gene expression of IL-6 and IL-1β in uteruses and the number of cervical infiltrating macrophages were reduced in fat-1 mice. The analyses of lipid metabolomics showed the high level of 18-hydroxyeicosapentaenoate in fat-1 mice, which was derived from EPA and was metabolized to anti-inflammatory product named resolvin E3 (RvE3). We finally showed that the administration of RvE3 to LPS-exposed pregnant wild type mice lowered the incidence of preterm birth. Our data suggest that RvE3 could be a potential new therapeutic for the prevention of preterm birth. PMID:24177907

  6. Increased tissue levels of omega-3 polyunsaturated fatty acids prevents pathological preterm birth

    PubMed Central

    Yamashita, Aki; Kawana, Kei; Tomio, Kensuke; Taguchi, Ayumi; Isobe, Yosuke; Iwamoto, Ryo; Masuda, Koji; Furuya, Hitomi; Nagamatsu, Takeshi; Nagasaka, Kazunori; Arimoto, Takahide; Oda, Katsutoshi; Wada-Hiraike, Osamu; Yamashita, Takahiro; Taketani, Yuji; Kang, Jing X.; Kozuma, Shiro; Arai, Hiroyuki; Arita, Makoto; Osuga, Yutaka; Fujii, Tomoyuki

    2013-01-01

    Omega-3 polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) have anti-inflammatory effects. Preterm birth is an important problem in modern obstetrics and one of the main causes is an inflammation. We here showed that abundance of omega-3 fatty acids reduced the incidence of preterm birth induced by LPS with fat-1 mice, capable of converting omega-6 to omega-3 fatty acids. We also indicated that the gene expression of IL-6 and IL-1β in uteruses and the number of cervical infiltrating macrophages were reduced in fat-1 mice. The analyses of lipid metabolomics showed the high level of 18-hydroxyeicosapentaenoate in fat-1 mice, which was derived from EPA and was metabolized to anti-inflammatory product named resolvin E3 (RvE3). We finally showed that the administration of RvE3 to LPS-exposed pregnant wild type mice lowered the incidence of preterm birth. Our data suggest that RvE3 could be a potential new therapeutic for the prevention of preterm birth. PMID:24177907

  7. Postprandial Levels of Branch Chained and Aromatic Amino Acids Associate with Fasting Glycaemia

    PubMed Central

    Ottosson, Filip; Ericson, Ulrika; Almgren, Peter; Nilsson, Jeanette; Magnusson, Martin; Fernandez, Céline; Melander, Olle

    2016-01-01

    High fasting plasma concentrations of isoleucine, phenylalanine, and tyrosine have been associated with increased risk of hyperglycaemia and incidence of type 2 diabetes. Whether these associations are diet or metabolism driven is unknown. We examined how the dietary protein source affects the postprandial circulating profile of these three diabetes associated amino acids (DMAAs) and tested whether the postprandial DMAA profiles are associated with fasting glycaemia. We used a crossover design with twenty-one healthy individuals and four different isocaloric test meals, containing proteins from different dietary sources (dairy, fish, meat, and plants). Analysis of the postprandial DMAAs concentrations was performed using targeted mass spectrometry. A DMAA score was defined as the sum of all the three amino acid concentrations. The postprandial area under the curve (AUC) of all the three amino acids and the DMAA score was significantly greater after intake of the meal with dairy protein compared to intake of the three other meals. The postprandial AUC for the DMAA score and all the three amino acids strongly associated with fasting glucose level and insulin resistance. This indicates the importance of the postprandial kinetics and metabolism of DMAAs in understanding the overall association between DMAAs and glycaemia. PMID:27274867

  8. Changes in intramuscular amino acid levels in submaximally exercised horses - a pilot study.

    PubMed

    van den Hoven, R; Bauer, A; Hackl, S; Zickl, M; Spona, J; Zentek, J

    2010-08-01

    The time-dependent changes in intramuscular amino acid (AA) levels caused by exercise and by feeding a protein/AA supplement were analysed in nine horses. Horses were submitted to a total of four standardized exercise tests (SETs). Amino acid concentrations were determined prior to, immediately after, 4 and 18 h after exercise. The experiment was subdivided into two consecutive periods of 3 weeks. In each period two SETs were performed. In the second period, horses were given a protein/AA supplement within 1 h after exercise. Significant changes in mean plasma AA levels similar to previous studies were noted to be time-dependent and to be associated with feeding the supplement. The intramuscular concentrations of the free AA in relation to pre-exercise levels showed significant time-dependent changes for alanine, asparagine, aspartate, citrulline, glutamine, glycine, isoleucine, leucine, methionine, serine, taurine, threonine, tyrosine and valine. Feeding the supplement significantly increased the 4 h post-exercise intramuscular concentration of alanine, isoleucine, methionine and tyrosine. At 18 h after exercise, apart from isoleucine and methionine, levels were still increased and also those of asparagine, histidine and valine in relation to none treatment. Hence, it was concluded that AA mixtures administered orally to horses within 1 h after exercise increased intramuscular AA pool. PMID:19663973

  9. Acid Secretion and Serum Gastrin Levels in the Zollinger-Ellison Syndrome

    PubMed Central

    Sanchez, R. Edward; Longmire, William P.; Passaro, Edward

    1972-01-01

    Thirteen cases of patients with the Zollinger-Ellison syndrome were reviewed. In two cases the diagnosis was made by incidental biopsy of small liver nodules at operation for peptic ulcer disease. Seven patients had gastric secretory tests which showed a basal acid output to maximum acid output ratio of more than 65 percent. Five patients had bao:mao ratios less than 50 percent. A 30-month interval between incidental discovery of tumor and clinically evident disease was observed in two patients. Recurrence of symptoms after excision of tumor was noted after a similar interval in another case. Serum gastrin levels, before total gastrectomy, were elevated in all cases. The lowest preoperative level in this series of patients was 550 picograms per ml (normal 100 to 150 picograms). They were diagnostic in two patients with normal gastric secretory studies. The levels fell to normal following total gastrectomy in six patients. Two patients still had elevated levels five years and 14 years after total gastrectomy. One was discovered to have a parathyroid adenoma with hypercalcemia. Total gastrectomy was curative in all the patients with the Zollinger-Ellison syndrome; lesser operations were not. ImagesFigure 1.Figure 2.Figure 3.Figure 3.Figure 4. PMID:5031740

  10. Is Serum Uric Acid Level Correlated with Erectile Dysfunction in Coronary Artery Disease Patients?

    PubMed

    Salavati, Alborz; Mehrsai, Abdolrasoul; Allameh, Farzad; Alizadeh, Farimah; Namdari, Farshad; Hosseinian, Mehdi; Salimi, Elaheh; Heidari, Fariba; Pourmand, Gholamreza

    2016-03-01

    Coronary artery disease (CAD) and vascular insufficiency are consequences of modern lifestyle, and vasogenic erectile dysfunction (ED) is one of the leading causes of sexual dysfunction which could be prevented like ischemic heart disease if the risk factors are discovered and managed. Seventy-five men scheduled for coronary angiography were asked to fill out the IIEF5 questionnaire and underwent serum lipoprotein-a, uric acid, lipid profile, testosterone, Sex Hormone Binding Globulin (SHBG), dehyderoepiandrostendion sulfate (DHEAS) tests; and the results were compared with those of erectile dysfunction patients with and without coronary artery disease. Ten out of 32 CAD patients (30%) and 6 of 43 normal coronary men had ED Prevalence (P=0.04). The average serum uric acid in ED patients with normal coronary was 5.6 (± 0.68) 6.5 ±078 mg/dl in ED patients of CAD group P=0.034. Men with both ED and CAD had significantly higher levels of lipoprotein-a compared to those CAD patients with normal sexual function. Higher uric acid and lipoprotein-a levels are correlated with the presence of ED in patients with CAD. PMID:27107521

  11. Ethanol exposure affects gene expression in the embryonic organizer and reduces retinoic acid levels.

    PubMed

    Yelin, Ronit; Schyr, Racheli Ben-Haroush; Kot, Hadas; Zins, Sharon; Frumkin, Ayala; Pillemer, Graciela; Fainsod, Abraham

    2005-03-01

    Fetal Alcohol Spectrum Disorder (FASD) is a set of developmental malformations caused by alcohol consumption during pregnancy. Fetal Alcohol Syndrome (FAS), the strongest manifestation of FASD, results in short stature, microcephally and facial dysmorphogenesis including microphthalmia. Using Xenopus embryos as a model developmental system, we show that ethanol exposure recapitulates many aspects of FAS, including a shortened rostro-caudal axis, microcephally and microphthalmia. Temporal analysis revealed that Xenopus embryos are most sensitive to ethanol exposure between late blastula and early/mid gastrula stages. This window of sensitivity overlaps with the formation and early function of the embryonic organizer, Spemann's organizer. Molecular analysis revealed that ethanol exposure of embryos induces changes in the domains and levels of organizer-specific gene expression, identifying Spemann's organizer as an early target of ethanol. Ethanol also induces a defect in convergent extension movements that delays gastrulation movements and may affect the overall length. We show that mechanistically, ethanol is antagonistic to retinol (Vitamin A) and retinal conversion to retinoic acid, and that the organizer is active in retinoic acid signaling during early gastrulation. The model suggests that FASD is induced in part by an ethanol-dependent reduction in retinoic acid levels that are necessary for the normal function of Spemann's organizer. PMID:15708568

  12. High levels of retinal membrane docosahexaenoic acid increase susceptibility to stress-induced degeneration.

    PubMed

    Tanito, Masaki; Brush, Richard S; Elliott, Michael H; Wicker, Lea D; Henry, Kimberly R; Anderson, Robert E

    2009-05-01

    The fat-1 gene cloned from C. elegans encodes an n-3 fatty acid desaturase that converts n-6 to n-3 PUFA. Mice carrying the fat-1 transgene and wild-type controls were fed an n-3-deficient/n-6-enriched diet [fat-1- safflower oil (SFO) and wt-SFO, respectively]. Fatty acid profiles of rod outer segments (ROS), cerebellum, plasma, and liver demonstrated significantly lower n-6/n-3 ratios and higher docosahexaenoic acid (DHA) levels in fat-1-SFO compared with wt-SFO. When mice were exposed to light stress: 1) the outer nuclear layer (ONL) thickness was reduced; 2) amplitudes of the electroretinogram (ERG) were lower; 3) the number of apoptotic photoreceptor cells was greater; and 4) modification of retinal proteins by 4-hydroxyhexenal (4-HHE), an end-product of n-3 PUFA oxidation was increased in both fat-1-SFO and wt mice fed a regular lab chow diet compared with wt-SFO. The results indicate a positive correlation between the level of DHA, the degree of n-3 PUFA lipid peroxidation, and the vulnerability of the retina to photooxidative stress. In mice not exposed to intense light, the reduction in DHA resulted in reduced efficacy in phototransduction gain steps, while no differences in the retinal morphology or retinal biochemistry. These results highlight the dual roles of DHA in cellular physiology and pathology. PMID:19023138

  13. 40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., strontium salt(1:1:2), dysprosium and europium-doped. 721.9511 Section 721.9511 Protection of Environment...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new..., strontium salt(1:1:2), dysprosium and europium-doped. (PMN P-98-848; CAS No.181828-07-9) is subject...

  14. 40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., strontium salt(1:1:2), dysprosium and europium-doped. 721.9511 Section 721.9511 Protection of Environment...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new..., strontium salt(1:1:2), dysprosium and europium-doped. (PMN P-98-848; CAS No.181828-07-9) is subject...

  15. 40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., strontium salt(1:1:2), dysprosium and europium-doped. 721.9511 Section 721.9511 Protection of Environment...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new..., strontium salt(1:1:2), dysprosium and europium-doped. (PMN P-98-848; CAS No.181828-07-9) is subject...

  16. 40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., strontium salt(1:1:2), dysprosium and europium-doped. 721.9511 Section 721.9511 Protection of Environment...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new..., strontium salt(1:1:2), dysprosium and europium-doped. (PMN P-98-848; CAS No.181828-07-9) is subject...

  17. Serum uric acid levels in patients with myasthenia gravis are inversely correlated with disability

    PubMed Central

    Yang, Dehao; Weng, Yiyun; Lin, Haihua; Xie, Feiyan; Yin, Fang; Lou, Kangliang; Zhou, Xuan; Han, Yixiang; Li, Xiang

    2016-01-01

    Uric acid (UA), the final product of purine metabolism, has been reported to be reduced in patients with various neurological disorders and is considered to be a possible indicator for monitoring the disability and progression of multiple sclerosis. However, it remains unclear whether there is a close relationship between UA and myasthenia gravis (MG), or whether UA is primarily deficient or secondarily reduced because of its peroxynitrite scavenging activity. We investigated the correlation between serum UA levels and the clinical characteristics of MG. We assessed 338 serum UA levels obtained in 135 patients with MG, 47 patients with multiple sclerosis, and 156 healthy controls. In addition, we compared serum UA levels when MG patients were stratified according to disease activity and classifications performed by the Myasthenia Gravis Foundation of America, age of onset, duration, and thymus histology (by means of MRI or computed tomography). MG patients had significantly lower serum UA levels than the controls (P<0.001). Moreover, UA levels in patients with MG were inversely correlated with disease activity and disease progression (P=0.013). However, UA levels did not correlate significantly with disease duration, age of onset, and thymus histology. Our findings suggest that serum level of UA was reduced in patients with MG and serum UA might be considered a surrogate biomarker of MG disability and progression. PMID:26836463

  18. Boronic acid functionalized N-doped carbon quantum dots as fluorescent probe for selective and sensitive glucose determination

    NASA Astrophysics Data System (ADS)

    Jiang, Guohua; Jiang, Tengteng; Li, Xia; Wei, Zheng; Du, Xiangxiang; Wang, Xiaohong

    2014-04-01

    Nitrogen doped carbon quantum dots (NCQDs) of about 10 nm in diameter have been obtained by hydrothermal reaction from collagen. Because of the superiority of water dispersion, low toxicity and ease of functionlization, the NCQDs were designed as a glucose sensor after covalent grafting by 3-aminophenylboronic (APBA) (APBA-NCQDs). The as-prepared APBA-NCQDs were imparted with glucose sensitivity and selectivity from other saccharides via fluorescence (FL) quenching effect at physiological pH and at room temperature, which show high sensitivity and specificity for glucose determination with a wide range from 1 mM to 14 mM. FL quenching mechanism of APBA-NCQDs was also investigated by adding an external quencher. The APBA-NCQDs-based platform is an environmentally friendly way to substitute inorganic quantum dots containing heavy metals which offer a facile and low cost detection method.

  19. Watt-level erbium-doped all-fiber laser at 3.44 μm.

    PubMed

    Fortin, Vincent; Maes, Frédéric; Bernier, Martin; Bah, Souleymane Toubou; D'Auteuil, Marc; Vallée, Réal

    2016-02-01

    We demonstrate a 3.44 μm all-fiber laser emitting a maximum of 1.5 W at room temperature, the highest continuous power ever generated from a mid-IR fiber oscillator clearly beyond 3 μm. The laser operates on the 4F(9/2)→4I(9/2) transition of erbium-doped fluoride glasses and relies on a dual pumping scheme at 974 and 1976 nm. By combining a dichroic mirror deposited on the input fiber tip and a fiber Bragg grating as an output coupler, a stable laser emission is produced with a FWHM bandwidth of less than 0.6 nm. The laser cavity has an efficiency of 19% with respect to the launched pump power at 1976 nm and no saturation is observed provided 974 nm co-pumping is sufficient. The joint effect of the two pumps is also investigated. PMID:26907423

  20. A 100 mW-level single-mode switchable dual-wavelength erbium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Cheng, Jianqun; Zhang, Liaolin; Sharafudeen, Kaniyarakkal; Qiu, Jianrong

    2013-10-01

    A switchable dual-wavelength CW erbium-doped fiber laser with two cascaded fiber Bragg gratings has been proposed and demonstrated experimentally at room temperature. The laser uses a linear resonant cavity configuration incorporating a Sagnac loop with a polarization controller (PC) and can switch flexibly to output a single wavelength or dual wavelengths based on the polarization hole burning (PHB) effect. The slope efficiency and maximum output power can reach 23% and 96 mW, respectively. The two lasing peaks of the laser, with a narrow linewidth output and an optical signal-to-noise ratio of more than 50 dB, are located in the C and L bands of the optical communication window, respectively. The laser shows good stability with respect to the wavelength and output power.

  1. [Uric acid and purine plasma levels as plausible markers for placental dysfunction in pre-eclampsia].

    PubMed

    Escudero, Carlos; Bertoglia, Patricio; Muñoz, Felipe; Roberts, James M

    2013-07-01

    Uric acid is the final metabolite of purine break down, such as ATP, ADP, AMP, adenosine, inosine and hypoxanthine. The metabolite has been used broadly as a renal failure marker, as well as a risk factor for maternal and neonatal morbidity during pre-eclamptic pregnancies. High purine levels are observed in pre-eclamptic pregnancies, but the sources of these purines are unknown. However, there is evidence that pre-eclampsia (mainly severe pre-eclampsia) is associated with an increased release of cellular fragments (or microparticles) from the placenta to the maternal circulation. These in fact could be the substrate for purine metabolism. Considering this background, we propose that purines and uric acid are part of the same physiopathological phenomenon in pre-eclampsia (i.e., placental dysfunction) and could become biomarkers for placental dysfunction and postnatal adverse events. PMID:24356738

  2. Air and blood lead levels in lead acid battery recycling and manufacturing plants in Kenya.

    PubMed

    Were, Faridah H; Kamau, Geoffrey N; Shiundu, Paul M; Wafula, Godfrey A; Moturi, Charles M

    2012-01-01

    The concentration of airborne and blood lead (Pb) was assessed in a Pb acid battery recycling plant and in a Pb acid battery manufacturing plant in Kenya. In the recycling plant, full-shift area samples taken across 5 days in several production sections showed a mean value ± standard deviation (SD) of 427 ± 124 μg/m(3), while area samples in the office area had a mean ± SD of 59.2 ± 22.7 μg/m(3). In the battery manufacturing plant, full-shift area samples taken across 5 days in several production areas showed a mean value ± SD of 349 ± 107 μg/m(3), while area samples in the office area had a mean ± SD of 55.2 ± 33.2 μg/m(3). All these mean values exceed the U.S. Occupational Safety and Health Administration's permissible exposure limit of 50 μg/m(3) as an 8-hr time-weighted average. In the battery recycling plant, production workers had a mean blood Pb level ± SD of 62.2 ± 12.7 μg/dL, and office workers had a mean blood Pb level ± SD of 43.4 ± 6.6 μg/dL. In the battery manufacturing plant, production workers had a mean blood Pb level ± SD of 59.5 ± 10.1 μg/dL, and office workers had a mean blood Pb level ± SD of 41.6 ± 7.4 μg/dL. All the measured blood Pb levels exceeded 30 μg/dL, which is the maximum blood Pb level recommended by the ACGIH(®). Observations made in these facilities revealed numerous sources of Pb exposure due to inadequacies in engineering controls, work practices, respirator use, and personal hygiene. PMID:22512792

  3. Nature and properties of pure and Nb-doped TiO sub 2 ceramic membranes affecting the photocatalytic degradation of 3-chlorosalicylic acid as a model of halogenated organic compounds

    SciTech Connect

    Sabate, J.; Anderson, M.A.; Kikkawa, H.; Xu, Q.; Hill, C.G. Jr. ); Cervera-March, S. )

    1992-03-01

    Pure and Nb-doped TiO{sub 2} ceramic membranes supported on glass were prepared by sol-gel techniques. When irradiated with near-UV light, these membranes brought about the photocatalytic degradation of 3-chlorosalicylic acid (3-CSA). Relationships between preparation conditions and the characteristics and efficiencies of the different membranes have been inferred. The changes in the physical-chemical characteristics of these membranes when they are fired at high temperatures are retarded by both the Nb-doping and the coating on glass supports. Doping does not improve the rate of degradation of 3-CSA, despite the fact that light absorbance is higher. The increase of firing temperature causes an increase in the size of membrane particles and a remarkable drop in the specific surface area, resulting in a substantial decrease in photochemical efficiency. A discussion based on the hypothesis of e/h recombination at grain boundaries and point defects of the membranes is presented.

  4. False in vitro and in vivo elevations of uric acid levels in mouse blood.

    PubMed

    Watanabe, Tamaki; Tomioka, Naoko H; Watanabe, Shigekazu; Tsuchiya, Masao; Hosoyamada, Makoto

    2014-01-01

    Uric acid (UA) levels in mouse blood have been reported to range widely from 0.1 μM to 760 μM. The aim of this study was to demonstrate false in vitro and in vivo elevations of UA levels in mouse blood. Male ICR mice were anesthetized with pentobarbital (breathing mice) or sacrificed with overdose ether (non-breathing mice). Collected blood was dispensed into MiniCollect® tubes and incubated in vitro for 0 or 30 min at room temperature. After separation of plasma or serum, the levels of UA and hypoxanthine were determined using HPLC. From the non-incubated plasma of breathing mice, the true value of UA level in vivo was 13.5±1.4 μM. However, UA levels in mouse blood increased by a factor of 3.9 following incubation in vitro. This "false in vitro elevation" of UA levels in mouse blood after blood sampling was inhibited by allopurinol, a xanthine oxidase inhibitor. Xanthine oxidase was converted to UA in mouse serum from hypoxanthine which was released from blood cells during incubation. Plasma UA levels from non-breathing mice were 19 times higher than those from breathing mice. This "false in vivo elevation" of UA levels before blood sampling was inhibited by pre-treatment with phentolamine, an α-antagonist. Over-anesthesia with ether might induce α-vasoconstriction and ischemia and thus degrade intracellular ATP to UA. For the accurate measurement of UA levels in mouse blood, the false in vitro and in vivo elevations of UA level must be avoided by immediate separation of plasma after blood sampling from anesthetized breathing mice. PMID:24940669

  5. Palladium Nanoparticles Supported on Nitrogen and Sulfur Dual-Doped Graphene as Highly Active Electrocatalysts for Formic Acid and Methanol Oxidation.

    PubMed

    Zhang, Xin; Zhu, Jixin; Tiwary, Chandra Sekhar; Ma, Zhongyuan; Huang, Huajie; Zhang, Jianfeng; Lu, Zhiyong; Huang, Wei; Wu, Yuping

    2016-05-01

    Optimized designing of highly active electrocatalysts has been regarded as a critical point to the development of portable fuel cell systems with high power density. Here we report a facile and cost-effective strategy to synthesis of ultrafine Pd nanoparticles (NPs) supported on N and S dual-doped graphene (NS-G) nanosheets as multifunctional electrocatalysts for both direct formic acid fuel cell and direct methanol fuel cell. The incorporation of N and S atoms into graphene frameworks is achieved by a thermal treatment process, followed by the controlled growth of Pd NPs via a solvothermal approach. Owning to the unique structural features as well as the strong synergistic effects, the resulting Pd/NS-G hybrid exhibits outstanding electrocatalytic performance toward both formic acid and methanol electro-oxidation, such as higher anodic peak current densities and more exceptional catalytic stability than those of Pd/Vulcan XC-72R and Pd/undoped graphene catalysts. These findings open up new possibility in the construction of advanced Pd-based catalysts, which is conducive to solving the current bottlenecks of fuel cell technologies. PMID:27082661

  6. Enhancement of periodate-hydrogen peroxide chemiluminescence by nitrogen doped carbon dots and its application for the determination of pyrogallol and gallic acid.

    PubMed

    Shah, Syed Niaz Ali; Li, Haifang; Lin, Jin-Ming

    2016-06-01

    A new sensitized chemiluminescence (CL) was developed to broaden the analytical application of KIO4-H2O2 system. The nitrogen doped carbon dots (N-CDs) dramatically boosted the CL intensity of KIO4-H2O2 system which was further enriched by basic medium. In light of EPR analysis, free radical scavenging studies and CL spectra the detail mechanism for the enhancement was conferred in the presence of N-CDs and NaOH. The results suggested that CL of KIO4-H2O2 system in the presence and absence of N-CDs and NaOH proceeds via radical pathway. The enhanced CL was used for the determination of pyrogallol and gallic acid in range of 1.0×10(-4)-1.0×10(-7)M with 4.6×10(-8) and 6.1×10(-8)M limit of detection respectively. The relative standard deviation (RSD) at a concentration of 10(-5) for gallic acid and pyrogallol was 1.4% and 2.3% respectively (n=11). The attained results unveil that the present method is sensitive, faster, simpler and less costly compared to other methods and could be applied to determine polyphenols in real samples. PMID:27130085

  7. Microwave-assisted synthesis of biocompatible europium-doped calcium hydroxyapatite and fluoroapatite luminescent nanospindles functionalized with poly(acrylic acid).

    PubMed

    Escudero, Alberto; Calvo, Mauricio E; Rivera-Fernández, Sara; de la Fuente, Jesús M; Ocaña, Manuel

    2013-02-12

    Europium-doped calcium hydroxyapatite and fluoroapatite nanophosphors functionalized with poly(acrylic acid) (PAA) have been synthesized through a one-pot microwave-assisted hydrothermal method from aqueous basic solutions containing calcium nitrate, sodium phosphate monobasic, and PAA, as well as sodium fluoride in the case of the fluoroapatite particles. In both cases a spindlelike morphology was obtained, resulting from an aggregation process of smaller subunits which also gave rise to high specific surface area. The size of the nanospindles was 191 (32) × 40 (5) nm for calcium hydroxyapatite and 152 (24) × 38 (6) nm for calcium fluoroapatite. The luminescent nanoparticles showed the typical red luminescence of Eu(3+), which was more efficient for the fluoroapatite particles than for the hydroxyapatite. This is attributed to the presence of OH(-) quenchers in the latter. The nanophosphors showed negligible toxicity for Vero cells. Both PAA-functionalized nanophosphors showed a very high (up to at least 1 week) colloidal stability in 2-(N-morpholino)ethanesulfonic acid (MES) at pH 6.5, which is a commonly used buffer for physiological pH. All these features make both kinds of apatite-based nanoparticles promising tools for biomedical applications, such as luminescent biolabels and tracking devices in drug delivery systems. PMID:23317411

  8. Mechanisms of optical losses in the 5D4 and 5D3 levels in Tb3+ doped low silica calcium aluminosilicate glasses

    NASA Astrophysics Data System (ADS)

    dos Santos, J. F. M.; Terra, I. A. A.; Astrath, N. G. C.; Guimarães, F. B.; Baesso, M. L.; Nunes, L. A. O.; Catunda, T.

    2015-02-01

    Trivalent Tb-doped materials exhibit strong emission in the green and weak emission in the UV-blue levels. Usually, this behavior is attributed to the cross relaxation (CR) process. In this paper, the luminescence properties of Tb3+-doped low silica calcium aluminosilicate glasses are analyzed for UV (λexc = 325 nm) and visible (488 nm) excitations. Under 325 nm excitation, the intensity of green luminescence increases proportionally to Tb3+ concentration. However, the blue luminescence intensity is strongly reduced with the increase of concentration from 0.5-15.0 wt. %. In the case of 488 nm excitation, a saturation behavior of the green emission is observed at intensities two orders of magnitude smaller than expected for bleaching of the ground state population. Using a rate equation model, we showed that this behavior can be explained by an excited state absorption cross section two orders of magnitude larger than the ground state absorption. The blue emission is much weaker than expected from our rate equations (325 nm and 488 nm excitation). We concluded that only the CR process cannot explain the overall feature of measured luminescence quenching in the wide range of Tb3+ concentrations. Cooperative upconversion from a pair of excited ions (5D3:5D3 or 5D3:5D4) and other mechanisms involving upper lying states (4f5d, charge transfer, host matrix, defects, etc.) may play a significant role.

  9. Humidity sensing with doped polyaniline

    NASA Astrophysics Data System (ADS)

    Jain, Shilpa; Chakane, Sanjay D. S.; Bhoraskar, S. V.; Samui, A. B.; Krishnamurthy, V. N.

    2001-03-01

    Polyaniline (PANI) was doped with different dopants like camphosulphoric acid (CSA), diphenyl phosphate (DPPH), Sulphonic acid (S) and Maleic acid (MAC) by chemical method. The samples were prepared in the form of pellets as well as films. Polyaniline doped with Maleic acid was found to be mechanically and chemically stable as compared to other dopants and therefore the effect of humidity on conductivity was further investigated. Films prepared out of styrene buryl acrylate copolymer with different concentrations of PANI Maleic acid were used for sensing humidity ranging between 20% to 90% relative humidity. A maximum change in the conductivity of three to four orders of magnitude was obtained for the Maleic acid doped polyaniline pellet while two orders of magnitude change was obtained for the film samples over the range of humidity measured.

  10. Sex differences in lipid peroxidation and fatty acid levels in recent onset schizophrenia.

    PubMed

    Ramos-Loyo, Julieta; Medina-Hernández, Virginia; Estarrón-Espinosa, Mirna; Canales-Aguirre, Alejandro; Gómez-Pinedo, Ulises; Cerdán-Sánchez, Luis F

    2013-07-01

    Sex differences in the symptomatology and course of illness have been reported among schizophrenic patients. Hence, the principal objective of the present study was to investigate sex differences in the concentrations of the lipid peroxidation metabolites MDA and 4-HNE, and in the membrane phospholipid levels of ARA, EPA and DHA in patients with schizophrenia. A total of 46 paranoid schizophrenics (25 women) with short-term evolution who were in an acute psychotic stage and 40 healthy controls (23 women) participated in the study. Psychopathology was evaluated by BPRS and PANSS. Lipid peroxidation sub-products (MDA, 4-HNE) and fatty acid levels (ARA, EPA, DHA) were determined in erythrocyte membranes. The men in both groups showed higher lipid peroxidation levels and those values were higher in schizophrenic patients than controls, with only EPA fatty acid concentrations found to be lower in the former than the latter. These results suggest that men may suffer greater oxidative neuronal damage than women, and that this could worsen the course of illness and result in greater disease severity. PMID:23421976

  11. Engineered doped and codoped polyaniline gas sensors synthesized in N,N,dimethylformamide media

    NASA Astrophysics Data System (ADS)

    Arenas, M. C.; Sánchez, Gabriela; Nicho, M. E.; Elizalde-Torres, Josefina; Castaño, V. M.

    2012-03-01

    Conducting Polyaniline films (Pani) on Corning glass substrates, produced using either an in-situ doping process or a co-doping process, were prepared by the oxidative polymerization of aniline in N,N,dimethylformamide. Bicyclic aliphatic camphorsulfonic acid (CSA), aromatic toluenesulfonic acid (TSA) and carboxylic trifluoroacetic acid (TFA) were employed as doping agents, and CSA mixed with TSA and CSA mixed with TFA were employed as the co-doping materials. The topography of the Pani films was analyzed by atomic-force microscopy (AFM), and their doping and oxidizing states were characterized by Fourier-transform infrared (FT-IR) spectroscopy and optical (UV-Vis) spectroscopy. Flower-like clusters, microfibers, and nanofibers were obtained by doping with CSA, TSA, and the mix of both (CSATSA), respectively. The flower-like morphology limits the conductivity of the film while the microfiber morphology leads to a highly conductive film. The conductivity of the films increases with the doping level, coil-like conformation of the chain and the protonation of the imine in quinoid units. The codoped process reduces the roughness of the CSA-doped films by 50%, but the conductivity depends on the acid type used for this process (TSA or TFA). The optical gas sensor response of the films is related to both the morphology and the degree of protonation. In this study, Pani with a microfiber morphology obtained from TSA-doping is the most sensitive to ammonia gas sensing, and Pani with flower-like morphology is the least sensitive.

  12. Ingestion of a single serving of saury alters postprandial levels of plasma n-3 polyunsaturated fatty acids and long-chain monounsaturated fatty acids in healthy human adults

    PubMed Central

    2012-01-01

    Background Saury oil contains considerable amounts of n-3 polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA) with long aliphatic tails (>18C atoms). Ingestion of saury oil reduces the risk of developing metabolic syndrome concomitant with increases in n-3 PUFA and long-chain MUFA in plasma and organs of mice. We therefore evaluated changes in postprandial plasma fatty acid levels and plasma parameters in healthy human subjects after ingestion of a single meal of saury. Findings Five healthy human adults ingested 150 g of grilled saury. Blood was collected before the meal and at 2, 6, and 24 hr after the meal, and plasma was prepared. Plasma levels of eicosapentaenoic acid, docosahexaenoic acid, and long-chain MUFA (C20:1 and C22:1 isomers combined) increased significantly throughout the postprandial period compared with the pre-meal baseline. Postprandial plasma insulin concentration increased notably, and plasma levels of glucose and free fatty acids decreased significantly and subsequently returned to the pre-meal levels. Conclusions Our study suggests that a single saury meal may alter the postprandial plasma levels of n-3 PUFA and long-chain MUFA in healthy human subjects. PMID:22846384

  13. Fatty acid ethanolamide levels are altered in borderline personality and complex posttraumatic stress disorders.

    PubMed

    Schaefer, Carola; Enning, Frank; Mueller, Juliane K; Bumb, J Malte; Rohleder, Cathrin; Odorfer, Thorsten M; Klosterkötter, Joachim; Hellmich, Martin; Koethe, Dagmar; Schmahl, Christian; Bohus, Martin; Leweke, F Markus

    2014-08-01

    Borderline personality (BPD) and complex posttraumatic stress disorders (PTSD) are both powerfully associated with the experience of interpersonal violence during childhood and adolescence. The disorders frequently co-occur and often result in pervasive problems in, e.g., emotion regulation and altered pain perception, where the endocannabinoid system is deeply involved. We hypothesize an endocannabinoid role in both disorders. We investigated serum levels of the endocannabinoids anandamide and 2-arachidonoylglycerol and related fatty acid ethanolamides (FAEs) in BPD, PTSD, and controls. Significant alterations were found for both endocannabinoids in BPD and for the FAE oleoylethanolamide in PTSD suggesting a respective link to both disorders. PMID:24253425

  14. Fabrication of ion doped WO3 photocatalysts through bulk and surface doping.

    PubMed

    Wang, Xiaoying; Pang, Laixue; Hu, Xiuying; Han, Nianfeng

    2015-09-01

    Na(+) doped WO3 nanowire photocatalysts were prepared by using post-treatment (surface doping) and in situ (bulk doping) doping methods. Photocatalytic degradation of Methyl Blue was tested under visible light irradiation, the results showed that 1wt.% Na(+) bulk-doped WO3 performed better, with higher photoactivity than surface-doped WO3. Photoelectrochemical characterization revealed the differences in the photocatalytic process for surface doping and bulk doping. Uniform bulk doping could generate more electron-hole pairs, while minimizing the chance of electron-hole recombination. Some bulk properties such as the bandgap, Fermi level and band position could also be adjusted by bulk doping, but not by surface doping. PMID:26354695

  15. Association Between Serum Levels of Adipocyte Fatty Acid-binding Protein and Free Thyroxine

    PubMed Central

    Tseng, Fen-Yu; Chen, Pei-Lung; Chen, Yen-Ting; Chi, Yu-Chao; Shih, Shyang-Ron; Wang, Chih-Yuan; Chen, Chi-Ling; Yang, Wei-Shiung

    2015-01-01

    Abstract Adipocyte fatty acid-binding protein (AFABP) has been shown to be a biomarker of body weight change and atherosclerosis. Changes in thyroid function are associated with changes in body weight and risks of cardiovascular diseases. The association between AFABP and thyroid function status has been seldom evaluated. The aim of this study was to compare the serum AFABP concentrations in hyperthyroid patients and those in euthyroid individuals, and to evaluate the associations between serum AFABP and free thyroxine (fT4) levels. For this study, 30 hyperthyroid patients and 30 euthyroid individuals at a referral medical center were recruited. The patients with hyperthyroidism were treated with antithyroid regimens as clinically indicated. No medication was given to the euthyroid individuals. The body weight, body mass index, thyroid function, serum levels of AFABP, and biochemical data of both groups at baseline and at the 6th month were compared. Associations between AFABP and fT4 levels were also analyzed. At the baseline, the hyperthyroid patients had significantly higher serum AFABP levels than the euthyroid individuals (median [Q1, Q3]: 22.8 [19.4, 30.6] ng/mL vs 18.6 [15.3, 23.2] ng/mL; P = 0.038). With the antithyroid regimens, the AFABP serum levels of the hyperthyroid patients decreased to 16.6 (15.0, 23.9) ng/mL at the 6th month. No difference in the AFABP level was found between the hyperthyroid and the euthyroid groups at the 6th month. At baseline, sex (female vs male, ß = 7.65, P = 0.022) and fT4 level (ß = 2.51, P = 0.018) were significantly associated with AFABP levels in the univariate regression analysis. At the 6th month, sex and fT4 level (ß = 8.09, P < 0.001 and ß = 3.61, P = 0.005, respectively) were also significantly associated with AFABP levels. The associations between sex and fT4 level with AFABP levels remained significant in the stepwise multivariate regression analysis, both at baseline and at

  16. Doping dependence of electrical and thermal conductivity of nanoscale polyaniline thin films

    NASA Astrophysics Data System (ADS)

    Jin, Jiezhu; Wang, Qing; Haque, M. A.

    2010-05-01

    We performed simultaneous characterization of electrical and thermal conductivity of 55 nm thick polyaniline (PANI) thin films doped with different levels of camphor sulfonic acids (CSAs). The effect of the doping level is more pronounced on electrical conductivity than on thermal conductivity of PANIs, thereby greatly affecting their ratio that determines the thermoelectric efficiency. At the 60% (the molar ratio of CSA to phenyl-N repeat unit of PANI) doping level, PANI exhibited the maximum electrical and thermal conductivity due to the formation of mostly delocalized structures. Whereas polarons are the charge carriers responsible for the electrical conduction, phonons are believed to play a dominant role in the heat conduction in nanoscale doped PANI thin films.

  17. System-level understanding of the potential acid-tolerance components of Acidithiobacillus thiooxidans ZJJN-3 under extreme acid stress.

    PubMed

    Feng, Shoushuai; Yang, Hailin; Wang, Wu

    2015-09-01

    In previous study, two extremely acidophilic strains Acidithiobacillus thiooxidans ZJJN-3 (collection site: bioleaching leachate) and ZJJN-5 (collection site: bioleaching wastewater) were isolated from a typical industrial bio-heap in China. Here, we unraveled the potential acid-tolerance components of ZJJN-3 by comparing the physiological differences with ZJJN-5 under different acid stresses. The parameters used for comparison included intracellular pH (pHin), capsule morphology, fatty acid composition of cell membrane, transcription of key molecular chaperones, H(+)-ATPase activities and NAD(+)/NADH ratio. It was indicated that the acid-tolerance of A. thiooxidans ZJJN-3 was systematically regulated. Capsule first thickened and then shed off along with increased acid stress. Cell membrane maintained the intracellular stability by up-regulating the proportion of unsaturated fatty acid and cyclopropane fatty acids. Meanwhile, the transcription of key repair molecular chaperones (GrpE-DnaK-DnaJ) was up-regulated by 2.2-3.5 folds for ensuring the proper folding of peptide. Moreover, low pHin promoted ZJJN-3 to biosynthesize more H(+)-ATPase for pumping H(+) out of cells. Furthermore, the NAD(+)/NADH ratio increased due to the decreased H(+) concentration. Based on the above physiological analysis, the potential acid-tolerance components of A. thiooxidans ZJJN-3 were first proposed and it would be useful for better understanding how these extremophiles responded to the high acid stress. PMID:26264736

  18. Justification for Selecting Level A vs. Level B Personal Protective Equipment to Remediate a Room Containing Concentrated Acids, Bases and Radiological Constituents

    SciTech Connect

    Hylko, J. M.; Thompson, A. L.; Walter, J. F.; Deecke, T. A.

    2002-02-25

    Selecting the appropriate personal protective equipment (PPE) is based on providing an adequate level of employee protection relative to the task-specific conditions and hazards. PPE is categorized into four ensembles, based on the degree of protection afforded; e.g., Levels A (most restrictive), B, C, and D (least restrictive). What is often overlooked in preparing an ensemble is that the PPE itself can create significant worker hazards; i.e., the greater the level of PPE, the greater the associated risks. Furthermore, there is confusion as to whether a more ''conservative approach'' should always be taken since Level B provides the same level of respiratory protection as Level A but less skin protection. This paper summarizes the Occupational Safety and Health Administration regulations addressing Level A versus Level B, and provides justification for selecting Level B over Level A without under-protecting the employee during a particular remediation scenario. The scenario consisted of an entry team performing (1) an initial entry into a room containing concentrated acids (e.g., hydrofluoric acid), bases, and radiological constituents; (2) sampling and characterizing container contents; and (3) retrieving characterized containers. The invasive nature of the hydrofluoric acid sampling and characterization scenario created a high potential for splash, immersion, and exposure to hazardous vapors, requiring additional skin protection. The hazards associated with this scenario and the chemical nature of hydrofluoric acid provided qualitative evidence to justify Level A. Once the hydrofluoric acid was removed from the room, PPE performance was evaluated against the remaining chemical inventory. If chemical breakthrough from direct contact was not expected to occur and instrument readings confirmed the absence of any hazardous vapors, additional skin protection afforded by wearing a vapor-tight, totally-encapsulated suit was not required. Therefore, PPE performance and

  19. Human Insulin Resistance Is Associated With Increased Plasma Levels of 12α-Hydroxylated Bile Acids

    PubMed Central

    Haeusler, Rebecca A.; Astiarraga, Brenno; Camastra, Stefania; Accili, Domenico; Ferrannini, Ele

    2013-01-01

    Bile acids (BAs) exert pleiotropic metabolic effects, and physicochemical properties of different BAs affect their function. In rodents, insulin regulates BA composition, in part by regulating the BA 12α-hydroxylase CYP8B1. However, it is unclear whether a similar effect occurs in humans. To address this question, we examined the relationship between clamp-measured insulin sensitivity and plasma BA composition in a cohort of 200 healthy subjects and 35 type 2 diabetic (T2D) patients. In healthy subjects, insulin resistance (IR) was associated with increased 12α-hydroxylated BAs (cholic acid, deoxycholic acid, and their conjugated forms). Furthermore, ratios of 12α-hydroxylated/non–12α-hydroxylated BAs were associated with key features of IR, including higher insulin, proinsulin, glucose, glucagon, and triglyceride (TG) levels and lower HDL cholesterol. In T2D patients, BAs were nearly twofold elevated, and more hydrophobic, compared with healthy subjects, although we did not observe disproportionate increases in 12α-hydroxylated BAs. In multivariate analysis of the whole dataset, controlling for sex, age, BMI, and glucose tolerance status, higher 12α-hydroxy/non–12α-hydroxy BA ratios were associated with lower insulin sensitivity and higher plasma TGs. These findings suggest a role for 12α-hydroxylated BAs in metabolic abnormalities in the natural history of T2D and raise the possibility of developing insulin-sensitizing therapeutics based on manipulations of BA composition. PMID:23884887

  20. Three conazoles increase hepatic microsomal retinoic acid metabolism and decrease mouse hepatic retinoic acid levels in vivo

    SciTech Connect

    Chen, P.-J.; Padgett, William T.; Moore, Tanya; Winnik, Witold; Lambert, Guy R.; Thai, Sheau-Fung; Hester, Susan D.; Nesnow, Stephen

    2009-01-15

    Conazoles are fungicides used in agriculture and as pharmaceuticals. In a previous toxicogenomic study of triazole-containing conazoles we found gene expression changes consistent with the alteration of the metabolism of all trans-retinoic acid (atRA), a vitamin A metabolite with cancer-preventative properties (Ward et al., Toxicol. Pathol. 2006; 34:863-78). The goals of this study were to examine effects of propiconazole, triadimefon, and myclobutanil, three triazole-containing conazoles, on the microsomal metabolism of atRA, the associated hepatic cytochrome P450 (P450) enzyme(s) involved in atRA metabolism, and their effects on hepatic atRA levels in vivo. The in vitro metabolism of atRA was quantitatively measured in liver microsomes from male CD-1 mice following four daily intraperitoneal injections of propiconazole (210 mg/kg/d), triadimefon (257 mg/kg/d) or myclobutanil (270 mg/kg/d). The formation of both 4-hydroxy-atRA and 4-oxo-atRA were significantly increased by all three conazoles. Propiconazole-induced microsomes possessed slightly greater metabolizing activities compared to myclobutanil-induced microsomes. Both propiconazole and triadimefon treatment induced greater formation of 4-hydroxy-atRA compared to myclobutanil treatment. Chemical and immuno-inhibition metabolism studies suggested that Cyp26a1, Cyp2b, and Cyp3a, but not Cyp1a1 proteins were involved in atRA metabolism. Cyp2b10/20 and Cyp3a11 genes were significantly over-expressed in the livers of both triadimefon- and propiconazole-treated mice while Cyp26a1, Cyp2c65 and Cyp1a2 genes were over-expressed in the livers of either triadimefon- or propiconazole-treated mice, and Cyp2b10/20 and Cyp3a13 genes were over-expressed in the livers of myclobutanil-treated mice. Western blot analyses indicated conazole induced-increases in Cyp2b and Cyp3a proteins. All three conazoles decreased hepatic atRA tissue levels ranging from 45-67%. The possible implications of these changes in hepatic atRA levels

  1. Plasma Circulating Nucleic Acids Levels Increase According to the Morbidity of Plasmodium vivax Malaria

    PubMed Central

    Franklin, Bernardo S.; Vitorino, Barbara L. F.; Coelho, Helena C.; Menezes-Neto, Armando; Santos, Marina L. S.; Campos, Fernanda M. F.; Brito, Cristiana F.; Fontes, Cor J.; Lacerda, Marcus V.; Carvalho, Luzia H.

    2011-01-01

    Background Given the increasing evidence of Plasmodium vivax infections associated with severe and fatal disease, the identification of sensitive and reliable markers for vivax severity is crucial to improve patient care. Circulating nucleic acids (CNAs) have been increasingly recognized as powerful diagnostic and prognostic tools for various inflammatory diseases and tumors as their plasma concentrations increase according to malignancy. Given the marked inflammatory status of P. vivax infection, we investigated here the usefulness of CNAs as biomarkers for malaria morbidity. Methods and Findings CNAs levels in plasma from twenty-one acute P. vivax malaria patients from the Brazilian Amazon and 14 malaria non-exposed healthy donors were quantified by two different methodologies: amplification of the human telomerase reverse transcriptase (hTERT) genomic sequence by quantitative real time PCR (qPCR), and the fluorometric dsDNA quantification by Pico Green. CNAs levels were significantly increased in plasma from P. vivax patients as compared to healthy donors (p<0.0001). Importantly, plasma CNAs levels were strongly associated with vivax morbidity (p<0.0001), including a drop in platelet counts (p = 0.0021). These findings were further sustained when we assessed CNAS levels in plasma samples from 14 additional P. vivax patients of a different endemic area in Brazil, in which CNAS levels strongly correlated with thrombocytopenia (p = 0.0072). We further show that plasma CNAs levels decrease and reach physiological levels after antimalarial treatment. Although we found both host and parasite specific genomic sequences circulating in plasma, only host CNAs clearly reflected the clinical spectrum of P. vivax malaria. Conclusions Here, we provide the first evidence of increased plasma CNAs levels in malaria patients and reveal their potential as sensitive biomarkers for vivax malaria morbidity. PMID:21611202

  2. Levels of polyunsaturated fatty acids correlate with growth rate in plant cell cultures

    PubMed Central

    Meï, Coline; Michaud, Morgane; Cussac, Mathilde; Albrieux, Catherine; Gros, Valérie; Maréchal, Eric; Block, Maryse A.; Jouhet, Juliette; Rébeillé, Fabrice

    2015-01-01

    In higher plants, fatty acids (FAs) with 18 carbons (18C) represent about 70% of total FAs, the most abundant species being 18:2 and 18:3. These two polyunsaturated FAs (PUFAs) represent about 55% of total FAs in Arabidopsis cell suspension cultures, whereas 18:1 represents about 10%. The level of PUFAs may vary, depending on ill-defined factors. Here, we compared various sets of plant cell cultures and noticed a correlation between the growth rate of a cell population and the level of unsaturation of 18C FAs. These observations suggest that the final level of PUFAs might depend in part on the rate of cell division, and that FAD2 and FAD3 desaturases, which are respectively responsible for the formation of 18:2 and 18:3 on phospholipids, have limiting activities in fast-growing cultures. In plant cell culture, phosphate (Pi) deprivation is known to impair cell division and to trigger lipid remodeling. We observed that Pi starvation had no effect on the expression of FAD genes, and that the level of PUFAs in this situation was also correlated with the growth rate. Thus, the level of PUFAs appears as a hallmark in determining cell maturity and aging. PMID:26469123

  3. The relationship between serum uric acid levels and β-cell functions in nondiabetic subjects.

    PubMed

    Shimodaira, M; Niwa, T; Nakajima, K; Kobayashi, M; Hanyu, N; Nakayama, T

    2014-12-01

    High serum uric acid (UA) levels are believed to be an independent risk factor for the development of diabetes. We aimed to investigate the relationship between serum UA concentrations and early-phase insulin secretion following a 75 g oral glucose tolerance test (OGTT) in nondiabetic subjects. We enrolled 570 Japanese subjects (354 males and 216 females, aged 50.5 ± 8.9 years and 52.6 ± 7.3 years, respectively), who underwent the 75 g OGTT during their annual health examination. The OGTT confirmed their nondiabetic status. Insulin secretion was estimated by the disposition index (DI) [(Δ insulin/Δ glucose (0-30 min) × (1/HOMA-IR)], which is an adjusted measure of β-cell function relative to variations in insulin sensitivity. Simple linear regression analysis showed negative correlations between serum UA levels and DI, when examined in the whole study population and female subjects only (r = -0.209, p < 0.001 and r = -0.232, p < 0.001, respectively). However, in male subjects, UA levels did not correlate with DI. In females, multivariate linear regression analysis revealed that serum UA levels were the major predictors of DI, explaining 16.4% of its variation (p < 0.001). Serum UA levels significantly correlate with early-phase insulin secretion in nondiabetic Japanese women. It may be an independent risk factor for predicting β-cell function in women. PMID:25295417

  4. Rhabdomere biogenesis in Drosophila photoreceptors is acutely sensitive to phosphatidic acid levels

    PubMed Central

    Coessens, Elise; Manifava, Maria; Georgiev, Plamen; Pettitt, Trevor; Wood, Eleanor; Garcia-Murillas, Isaac; Okkenhaug, Hanneke; Trivedi, Deepti; Zhang, Qifeng; Razzaq, Azam; Zaid, Ola; Wakelam, Michael; O'Kane, Cahir J; Ktistakis, Nicholas

    2009-01-01

    Phosphatidic acid (PA) is postulated to have both structural and signaling functions during membrane dynamics in animal cells. In this study, we show that before a critical time period during rhabdomere biogenesis in Drosophila melanogaster photoreceptors, elevated levels of PA disrupt membrane transport to the apical domain. Lipidomic analysis shows that this effect is associated with an increase in the abundance of a single, relatively minor molecular species of PA. These transport defects are dependent on the activation state of Arf1. Transport defects via PA generated by phospholipase D require the activity of type I phosphatidylinositol (PI) 4 phosphate 5 kinase, are phenocopied by knockdown of PI 4 kinase, and are associated with normal endoplasmic reticulum to Golgi transport. We propose that PA levels are critical for apical membrane transport events required for rhabdomere biogenesis. PMID:19349583

  5. Cypermethrin alters Glial Fibrillary Acidic Protein levels in the rat brain.

    PubMed

    Malkiewicz, Katarzyna; Koteras, Marcin; Folkesson, Ronnie; Brzezinski, Jacek; Winblad, Bengt; Szutowski, Miroslaw; Benedikz, Eirikur

    2006-01-01

    Pyrethroids, widely used insecticides, are biologically active in neurons. Whether they act on the non-neuronal brain cells remains an open question. Thus, the aim of this study was to examine whether Cypermethrin intoxication affects astroglial cells in the rat brain. The levels of Glial Fibrillary Acidic Protein (GFAP) in different brain regions were measured by ELISA following oral treatment with 5 or 10% of LD(50) of Cypermethrin per day for 6 days. A significant decrease of GFAP was observed in different brain regions of treated animals. The cerebral cortex showed the most pronounced effect with GFAP levels reduced to 81% of the controls 2 days after treatment and 77% 21 days after treatment. Although we did not find profound changes in the morphology of astrocytes in Cypermethrin treated animals, the decrease in GFAP suggests that astrocytes were affected by low doses of pyrethroids. The possible consequences were discussed. PMID:21783638

  6. Effect of fill-pulse parameters on deep-level transient spectroscopy peaks in highly doped p-type InP

    NASA Astrophysics Data System (ADS)

    Darwich, R.; Massarani, B.

    2000-07-01

    The effect of different fill-pulse parameters on the characteristics of deep-level transient spectroscopy (DLTS) peaks has been studied in the example of the hole traps H4F and H5 in electron-irradiated highly doped p-type InP. It is shown that the saturation peak height, the temperature of the peak maximum and its full width at half maximum depend on the applied reverse bias, the pulse amplitude, its frequency and duration. Our results show that the origin of this dependence is the electric field present in the space charge region (SCR). The experimental results are analyzed in terms of the effect of the electric field on the refilled traps in the SCR. The appropriate experimental conditions for the correct extraction of information from the DLTS spectrum are defined.

  7. The structure and band gap design of high Si doping level Ag1-xGa1-xSixSe2 (x=1/2)

    NASA Astrophysics Data System (ADS)

    Zhang, Shiyan; Mei, Dajiang; Du, Xin; Lin, Zheshuai; Zhong, Junbo; Wu, Yuandong; Xu, Jingli

    2016-06-01

    Ag1-xGa1-xSixSe2 solutions with high Si doping level (x=1/2) are considered and new compound AgGaSiSe4 has been synthesized. It crystallizes in space group Aea2 and possesses very long axis of a=63.06(1)Å. The three-dimensional framework in AgGaSiSe4 is composed of AgSe3 trigonal planar units, AgSe4 tetrahedra and MSe4(M=Si, Ga) tetrahedra. AgGaSiSe4 is a congruently melting compound with the melt temperature of 759 °C. The diffuse reflectance measurements reveal the band gap of 2.63 eV in AgGaSiSe4 and the value is 0.33 eV larger than that of Ag3Ga3SiSe8 (2.30 eV).

  8. Modification of the surface pathways in alkane oxidation by selective doping of Bronsted acid sites of vanadyl pyrophosphate

    SciTech Connect

    Centi, G.; Golinelli, G.; Busca, G. )

    1990-08-23

    The modification of Bronsted POH groups of (VO){sub 2}P{sub 2}O{sub 7} by selective doping with K in an anhydrous medium causes a considerable modification of the surface oxidation pathways in C{sub 4}- and C{sub 5}-alkane oxidative transformation, with (i) a considerable decrease in the selective formation of maleic anhydride from n-butane and of maleic and phthalic anhydrides from n-pentane, (ii) an increase in the relative formation of C-containing surface residues. It is suggested that these effects are due to an inhibition of the catalyzed transformation of furan-like intermediates to corresponding lactones and then to anhydrides in the presence of gaseous O{sub 2} and to a change in the relative rates of O-insertion and H-abstraction on these surface intermediates. The role of the dynamics of competitive surface transformations of adsorbed intermediates on the overall behavior of vanadyl pyrophosphate in C{sub 4}- and C{sub 5}-alkane selective oxidation is also discussed.

  9. Influence of the counter ion on the properties of organic and inorganic acid doped polyaniline and their Schottky diodes

    NASA Astrophysics Data System (ADS)

    Ashokan, S.; Ponnuswamy, V.; Jayamurugan, P.; Chandrasekaran, J.; Subba Rao, Y. V.

    2015-09-01

    Pure and doped Polyaniline (PANI) was prepared by chemical oxidative polymerization of aniline. The FT-IR spectrum confirms the presence of dopants in PANI functional groups of SO32- groups in PANI. SEM morphology reveals the various shapes and size of the PANI. UV-Vis spectra confirm the absorption peaks at 270 and 340 nm is due to the π-π∗ transition of the benzenoid rings. The strong absorption peak around 603 nm showed extension of polymer chains. PL studies of PANI reveal the emission peaks around 325 nm and 510 nm of PANI. The conductivity measurements are carried out for the prepared PANI's pellets. The heterojunction device structure In/PANI-DBSA/Al and In/PANI-HCl/Al was made to fabricate by thermal evaporation method. The current voltage (I-V) characteristics of these devices are weak rectifying behavior with the non-linear nature. The diode parameters such as ideality factor, barrier height and saturation current densities were calculated using the modified Shockley equation.

  10. Observation of a Hidden Hole-Like Band Approaching the Fermi Level in K-Doped Iron Selenide Superconductor

    NASA Astrophysics Data System (ADS)

    Sunagawa, Masanori; Terashima, Kensei; Hamada, Takahiro; Fujiwara, Hirokazu; Fukura, Tetsushi; Takeda, Aya; Tanaka, Masashi; Takeya, Hiroyuki; Takano, Yoshihiko; Arita, Masashi; Shimada, Kenya; Namatame, Hirofumi; Taniguchi, Masaki; Suzuki, Katsuhiro; Usui, Hidetomo; Kuroki, Kazuhiko; Wakita, Takanori; Muraoka, Yuji; Yokoya, Takayoshi

    2016-07-01

    One of the ultimate goals of the study of iron-based superconductors is to identify the common feature that produces the high critical temperature (Tc). In the early days, based on a weak-coupling viewpoint, the nesting between hole- and electron-like Fermi surfaces (FSs) leading to the so-called s± state was considered to be one such key feature. However, this theory has faced a serious challenge ever since the discovery of alkali-metal-doped FeSe (AFS) superconductors, in which only electron-like FSs with a nodeless superconducting gap are observed. Several theories have been proposed, but a consistent understanding is yet to be achieved. Here we show experimentally that a hole-like band exists in KxFe2-ySe2, which presumably forms a hole-like Fermi surface. The present study suggests that AFS can be categorized in the same group as iron arsenides with both hole- and electron-like FSs present. This result provides a foundation for a comprehensive understanding of the superconductivity in iron-based superconductors.

  11. Effect of fluoride exposure on serum glycoprotein pattern and sialic acid level in rabbits.

    PubMed

    Ciftci, Gulay; Cenesiz, Sena; Yarim, Gul Fatma; Nisbet, Ozlem; Nisbet, Cevat; Cenesiz, Metin; Guvenc, Dilek

    2010-01-01

    This study describes the effects of fluoride exposure on the protein profile, glycoprotein pattern, and total sialic acid concentration of serum in rabbits. For this aim; 20 healthy New Zealand rabbits were used. The rabbits were divided into two equal groups each with ten animals according to their weighing: control group and experimental group. The rabbits in control group were given drinking tap water containing 0.29 mg/l sodium fluoride and experimental group received the same tap water to which was added 40 mg/l sodium fluoride for 70 days. Blood samples were taken from each rabbit on day 70. Serum fluoride concentrations were measured by a fluoride-specific ion electrode in serum. The fluoride levels in the serum were found as 18.4 (+/-1.58) microg/L in control and 301.3 (+/-52.18) microg/L in fluoride exposed rabbits. The sialic acid levels were found as 69.2 (+/-0.32) mg/dL in control and 43.4 (+/-0.13) mg/dL in fluoride exposed group. The electrophoretic patterns of serum proteins, glycoproteins, and total sialic acid concentration were determined. Fifteen different protein fractions with molecular weights ranging from 22 to 249 kDa were displayed in the serum protein electrophoretic gel of both groups. The raw concentrations of the protein fractions decreased in fluoride exposed rabbits as compared with the control rabbits. The serum glycoprotein pattern revealed seven major protein bands from 47 to 167 kDa in experimental and control groups. The slight decrease of raw concentration of the protein bands in glycoprotein pattern of serum was observed in fluoride toxication comparing to control. The results suggest that serum TSA determination and serum protein electrophoresis can be used to evaluate prognosis of fluoride exposure as a supplementary laboratory test in combination with clinical and other laboratory findings of fluorosis. PMID:19904501

  12. Salicylic acid enhances antioxidant system in Brassica juncea grown under different levels of manganese.

    PubMed

    Parashar, Akshaya; Yusuf, Mohammad; Fariduddin, Qazi; Ahmad, Aqil

    2014-09-01

    The aim was to explore the responses of varied doses of manganese in mustard plants and also to test the proposition that salicylic acid induced up-regulation of antioxidant system which protect photosynthetic apparatus. Seeds were sown in pots and allowed to germinate under natural environmental conditions. At 10 days stage, soils in the pots were enriched with different levels (0, 3, 6, or 9 mM) of Mn for three days and allowed to grow till 30 day stage. At 31st day, foliage of plants was sprayed with 10 μM of salicylic acid (SA) and then allowed to grow till 45 days. Then plants were harvested to assess various growth, leaf gas exchange traits and biochemical parameters. Mn-treated plants had diminished growth, water relations and photosynthetic attributes along with carbonic anhydrase activity whereas; the level of lipid peroxidation, electrolyte leakage, accumulation of H2O2 along with proline accumulation and antioxidant enzymes increased in a concentration dependent manner. Follow-up application of SA to the Mn-stressed plants improved growth, water relations and photosynthetic traits, accelerated the activity of antioxidant enzymes and also the accumulation of proline. SA mediated tolerance to Mn-stressed plants could have due to up-regulation of antioxidant enzymes and proline accumulation. PMID:25036598

  13. Gut microbiota regulates bile acid metabolism by reducing the levels of tauro-beta-muricholic acid, a naturally occurring FXR antagonist.

    PubMed

    Sayin, Sama I; Wahlström, Annika; Felin, Jenny; Jäntti, Sirkku; Marschall, Hanns-Ulrich; Bamberg, Krister; Angelin, Bo; Hyötyläinen, Tuulia; Orešič, Matej; Bäckhed, Fredrik

    2013-02-01

    Bile acids are synthesized from cholesterol in the liver and further metabolized by the gut microbiota into secondary bile acids. Bile acid synthesis is under negative feedback control through activation of the nuclear receptor farnesoid X receptor (FXR) in the ileum and liver. Here we profiled the bile acid composition throughout the enterohepatic system in germ-free (GF) and conventionally raised (CONV-R) mice. We confirmed a dramatic reduction in muricholic acid, but not cholic acid, levels in CONV-R mice. Rederivation of Fxr-deficient mice as GF demonstrated that the gut microbiota regulated expression of fibroblast growth factor 15 in the ileum and cholesterol 7α-hydroxylase (CYP7A1) in the liver by FXR-dependent mechanisms. Importantly, we identified tauro-conjugated beta- and alpha-muricholic acids as FXR antagonists. These studies suggest that the gut microbiota not only regulates secondary bile acid metabolism but also inhibits bile acid synthesis in the liver by alleviating FXR inhibition in the ileum. PMID:23395169

  14. Plasma hyaluronic acid level as a prognostic and monitoring marker of metastatic breast cancer.

    PubMed

    Peng, Cike; Wallwiener, Markus; Rudolph, Anja; Ćuk, Katarina; Eilber, Ursula; Celik, Muhabbet; Modugno, Caroline; Trumpp, Andreas; Heil, Jörg; Marmé, Frederik; Madhavan, Dharanija; Nees, Juliane; Riethdorf, Sabine; Schott, Sarah; Sohn, Christof; Pantel, Klaus; Schneeweiss, Andreas; Chang-Claude, Jenny; Yang, Rongxi; Burwinkel, Barbara

    2016-05-15

    Conventional tumor markers have limited value for prognostication and treatment monitoring in metastatic breast cancer (MBC) patients and novel circulating tumor markers therefore need to be explored. Hyaluronic acid (HA) is a major macropolysaccharide in the extracellular matrix and is reported to be associated with tumor progression. In our study, we investigated plasma HA level with respect to progression free survival (PFS) and overall survival (OS), as well as the treatment monitoring value in MBC patients. The prognostic value of plasma HA level was investigated in a discovery cohort of 212 MBC patients with 2.5-year follow-up and validated in an independent validation cohort of 334 patients with 5-year follow-up. The treatment monitoring value of plasma HA level was investigated in 61 MBC patients from discovery cohort who had been radiographically examined after first complete cycle of chemo therapy. We found a robust association between high plasma HA level and poor prognosis of MBC patients in both discovery (pPFS  = 7.92 × 10(-6) and pOS  = 5.27 × 10(-5) ) and validation studies (pPFS  = 3.66 × 10(-4) and pOS  = 1.43 × 10(-4) ). In the discovery cohort, the plasma HA level displayed independent prognostic value after adjusted for age and clinicopathological factors, with respect to PFS and OS. Further, the decrease of plasma HA level displayed good concordance with treatment response evaluated by radiographic examination (AUC = 0.79). Plasma HA level displays prognostic value, as well as treatment monitoring value for MBC patients. PMID:26686298

  15. Polybenzimidazole film containing phosphoric acid as proton exchange membrane (PEM)

    NASA Astrophysics Data System (ADS)

    Ameri, Roya

    Polybenzimidazole is a linear polymer with a very high glass transition temperature. It has exceptional properties at elevated temperature such as stability, retention of stiffness, and toughness. PBI containing phosphoric acid has high proton conductivity and low water vapor permeability. A new way of direct film casting of PBI containing phosphoric acid, has been found. The use of trifluoroacetic acid as a solvent resulted in a new and quick way to prepare PBI film containing phosphoric acid which showed about four times more conductivity at a given doping level than PBI doped with phosphoric acid from DMAc solution. Mechanical property studies of different molecular weight PBI films etasb{inh} = 0.91 to 142 dl/g) have shown that increasing molecular weight linearly improved mechanical properties of PBI films with pronounced effect on toughness. As PBI film was doped with sulfuric acid, mechanical properties decreased with very sharp drop in toughness. More reduction in mechanical properties was observed as the concentration of sulfuric acid in the film increased. Doping PBI film with low concentrations of phosphoric acid improved modulus and strength at break while lowering the toughness. Increasing the concentration of acid in these films lowered the strength and modulus of PBI film. However, toughness first increased up to concentration of 200-300M% phosphoric acid and then decreased. Comparison of phosphoric acid doped PBI film and PBI film cast from PBI/TFA/Hsb3POsb4 solution reveals that phosphoric acid doped PBI film has at least three times better mechanical properties: toughness, modulus, and strength. X-ray photographs of PBI film cast from PBI/TFA/Hsb3POsb4 solution shows a crystalline pattern with a monoclinic unit cell of dimensions: a = 15.8 A, b = 13.23 A, c = 16.83 A, and gamma = 79.1sp0. On the other hand, phosphoric acid doped PBI film has relatively low crystallinity. PBI can cocrystallize with some complexing agent like trifluoroacetic acid

  16. The Relationship between Uric Acid Levels and Huntington’s Disease Progression

    PubMed Central

    Auinger, Peggy; Kieburtz, Karl; McDermott, Michael P.

    2009-01-01

    Uric acid (UA) may be associated with the progression of Parkinson’s disease and related neurodegenerative conditions; however, its association with Huntington’s disease (HD) progression has not been explored. A secondary analysis of 347 subjects from the CARE-HD clinical trial was performed to examine the relationship between baseline UA levels and the level of functional decline in HD. Outcomes included change in scores at 30 months for the Unified Huntington’s Disease Rating Scale components. There was less worsening of total functional capacity over time with increasing baseline UA levels (adjusted mean worsening in scores: 3.17, 2.99, 2.95, 2.28, 2.21, from lowest to highest UA quintile, p=0.03). These data suggest a possible association between higher UA levels and slower HD progression, particularly as measured by total functional capacity. If confirmed, UA could be an important predictor and potentially modifiable factor affecting the rate of HD progression. PMID:20063429

  17. Synthesis and role of salicylic acid in wheat varieties with different levels of cadmium tolerance.

    PubMed

    Kovács, Viktória; Gondor, Orsolya K; Szalai, Gabriella; Darkó, Eva; Majláth, Imre; Janda, Tibor; Pál, Magda

    2014-09-15

    Wheat genotypes with different endogenous SA contents were investigated, in order to reveal how cadmium influences salicylic acid (SA) synthesis, and to find possible relationships between SA and certain protective compounds (members of the antioxidants and the heavy metal detoxification system) and between the SA content and the level of cadmium tolerance. Cadmium exposure induced SA synthesis, especially in the leaves, and it is suggested that the phenyl-propanoid synthesis pathway is responsible for the accumulation of SA observed after cadmium stress. Cadmium influenced the synthesis and activation of protective compounds to varying extents in wheat genotypes with different levels of tolerance; the roots and leaves also responded differently to cadmium stress. Although a direct relationship was not found between the initial SA levels and the degree of cadmium tolerance, the results suggest that the increase in the root SA level during cadmium stress in the Mv varieties could be related with the enhancement of the internal glutathione cycle, thus inducing the antioxidant and metal detoxification systems, which promote Cd stress tolerance in wheat seedlings. The positive correlation between certain SA-related compounds and protective compounds suggests that SA-related signalling may also play a role in the acclimation to heavy metal stress. PMID:25113613

  18. Sulforaphane reduces the alterations induced by quinolinic acid: modulation of glutathione levels.

    PubMed

    Santana-Martínez, R A; Galván-Arzáte, S; Hernández-Pando, R; Chánez-Cárdenas, M E; Avila-Chávez, E; López-Acosta, G; Pedraza-Chaverrí, J; Santamaría, A; Maldonado, P D

    2014-07-11

    Glutamate-induced excitotoxicity involves a state of acute oxidative stress, which is a crucial event during neuronal degeneration and is part of the physiopathology of neurodegenerative diseases. In this work, we evaluated the ability of sulforaphane (SULF), a natural dietary isothiocyanate, to induce the activation of transcription factor Nrf2 (a master regulator of redox state in the cell) in a model of striatal degeneration in rats infused with quinolinic acid (QUIN). Male Wistar rats received SULF (5mg/kg, i.p.) 24h and 5min before the intrastriatal infusion of QUIN. SULF increased the reduced glutathione (GSH) levels 4h after QUIN infusion, which was associated with its ability to increase the activity of glutathione reductase (GR), an antioxidant enzyme capable to regenerate GSH levels at 24h. Moreover, SULF treatment increased glutathione peroxidase (GPx) activity, while no changes were observed in γ-glutamyl cysteine ligase (GCL) activity. SULF treatment also prevented QUIN-induced oxidative stress (measured by oxidized proteins levels), the histological damage and the circling behavior. These results suggest that the protective effect of SULF could be related to its ability to preserve GSH levels and increase GPx and GR activities. PMID:24814729

  19. Association of Serum Uric Acid Levels in Psoriasis: A Systematic Review and Meta-Analysis.

    PubMed

    Li, Xin; Miao, Xiao; Wang, Hongshen; Wang, Yifei; Li, Fulun; Yang, Qiong; Cui, Rutao; Li, Bin

    2016-05-01

    High levels of serum uric acid (SUAC) are frequently detected in patients with psoriasis. However, the relationship between psoriasis and hyperuricemia remains unknown. Here we conducted a meta-analysis to identify the SUAC levels in subjects with psoriasis and to determine whether there is an associated risk between psoriasis and hyperuricemia.A comprehensive search of the literature from January 1980 to November 2014 across 7 databases (MEDLINE, Embase, Cochrane Central Register, and 4 Chinese databases) was conducted to determine whether there is an associated risk between psoriasis and hyperuricemia.Among the 170 identified reports, 14 observational studies were included in this meta-analysis. We found a significant higher SUAC level (MD 0.68, 95% CI 0.26-1.09; P = 0.002) in patients with psoriasis in Western Europe, but no significant differences were found between the East Asia and India subgroup (MD 1.22, 95% CI -0.13-2.56; P = 0.08) or the Middle East subgroup (MD 0.48, 95% CI -0.49-1.44; P = 0.33). Similar results were obtained from the meta-analysis of SUAC levels in subjects with severe psoriasis.Our meta-analysis showed that the correlation between psoriasis and hyperuricemia was either ethnicity- or region-dependent and that patients with psoriasis in Western Europe were more likely to have hyperuricemia. PMID:27175702

  20. The deposition of conjugated linoleic acids in eggs of laying hens fed diets varying in fat level and fatty acid profile.

    PubMed

    Raes, Katleen; Huyghebaert, Gerard; De Smet, Stefaan; Nollet, Lode; Arnouts, Sven; Demeyer, Daniel

    2002-02-01

    The objective of this study was to investigate the incorporation of conjugated linoleic acid (CLA) into eggs and its effect on the fatty acid metabolism when layers are fed diets with different fat sources and fat levels. Layers were fed either a low fat diet (LF) or one of three high fat diets based on soybean oil (SB), animal fat (AF) or flaxseed oil (FSO). CLA was added at a concentration of 1 g/100 g feed from two different CLA premixes with a different CLA profile. For the trial, 144 laying hens were allocated to 12 treatments (4 basal fat sources x 3 CLA treatments) with 3 replicates of 4 hens each. No significant differences were observed in feed intake, egg weight, feed conversion or laying rate between chickens fed control and CLA-supplemented diets. Differences in yolk fat, cholesterol or yolk color were not clearly related to the dietary CLA. However, the supplementation of CLA to the diets had clear effects on the fatty acid composition, i.e., a decrease in monounsaturated fatty acids (MUFA) and an increase in saturated fatty acids (SFA) was observed, whereas the polyunsaturated fatty acids (PUFA) content were essentially unaffected. The results suggest that CLA may influence the activity of the desaturases to a different extent in the synthesis of (n-6) and (n-3) long-chain fatty acids. These effects of CLA depend on the level of (n-6) and (n-3) fatty acids available in the feed. The apparent deposition rate (%) is clearly higher for the c9, t11 isomer than for the t10, c12 isomer. Adding CLA to layers diets rich in (n-3) fatty acids produces eggs that could promote the health of the consumer in terms of a higher intake of (n-3) fatty acids and CLA. PMID:11823576

  1. Acid and Alkaline Phosphatase Levels in GCF during Orthodontic Tooth Movement

    PubMed Central

    Farahani, Mohammad; Safavi, Seyed Mohammadreza; Dianat, Omid; Khoramian Tusi, Somayeh; Younessian, Farnaz

    2015-01-01

    Statement of the Problem The present constituents of gingival crevicular fluid (GCF) can reflect the changes occurring in underlying tissues. Considering variety of biologic bone markers, alkaline phosphatase and acid phosphatase have been examined as bone turn over markers in orthodontic tooth movement. Purpose The current study designed in a longitudinal pattern to determine the changes of acid and alkaline phosphatase (ACP & ALP) in GCF during orthodontic tooth movement. Materials and Method An upper canines from twelve patients (mean age: 14±2 years) undergoing extraction orthodontic treatment for distal movement served as the test tooth (DC), and its contralateral (CC) and antagonist (AC) canines were used as controls. The CC was included in orthodontic appliance without orthodontic force; the AC was free from any orthodontic appliance. The GCF around the experimental teeth was harvested from mesial and distal tooth sites immediately before appliance placement (T0), and 14 (T2) and 28 days (T3) after it and ALP and ACP concentration were determined spectrophotometrically. Results ALP concentration was elevated significantly in DC and CC groups at days 14 and 28 compared with the AC. In DC group, the ALP was significantly greater in mesial sites than distal site, while no significant changes were found between both sites of CC. The peak level of ALP was observed in mesial sites of DC at T2. Regarding ACP, significant elevation of this enzyme was seen in DC group both in mesial and distal sites at T2 and T3. The peak level of this enzyme was seen at T2. Conclusion Monitoring simultaneous changes of ALP and ACP levels in GCF can reflect the tissue responses occur in periodontium during bone formation and bone resorption during orthodontic tooth movement, respectively. PMID:26535403

  2. Airplane dopes and doping

    NASA Technical Reports Server (NTRS)

    Smith, W H

    1919-01-01

    Cellulose acetate and cellulose nitrate are the important constituents of airplane dopes in use at the present time, but planes were treated with other materials in the experimental stages of flying. The above compounds belong to the class of colloids and are of value because they produce a shrinking action on the fabric when drying out of solution, rendering it drum tight. Other colloids possessing the same property have been proposed and tried. In the first stages of the development of dope, however, shrinkage was not considered. The fabric was treated merely to render it waterproof. The first airplanes constructed were covered with cotton fabric stretched as tightly as possible over the winds, fuselage, etc., and flying was possible only in fine weather. The necessity of an airplane which would fly under all weather conditions at once became apparent. Then followed experiments with rubberized fabrics, fabrics treated with glue rendered insoluble by formaldehyde or bichromate, fabrics treated with drying and nondrying oils, shellac, casein, etc. It was found that fabrics treated as above lost their tension in damp weather, and the oil from the motor penetrated the proofing material and weakened the fabric. For the most part the film of material lacked durability. Cellulose nitrate lacquers, however were found to be more satisfactory under varying weather conditions, added less weight to the planes, and were easily applied. On the other hand, they were highly inflammable, and oil from the motor penetrated the film of cellulose nitrate, causing the tension of the fabric to be relaxed.

  3. Multifunctional electroactive electrospun nanofiber structures from water solution blends of PVA/ODA–MMT and poly(maleic acid-alt-acrylic acid): effects of Ag, organoclay, structural rearrangement and NaOH doping factors

    NASA Astrophysics Data System (ADS)

    Şimşek, Murat; Rzayev, Zakir M. O.; Bunyatova, Ulviya

    2016-06-01

    Novel multifunctional colloidal polymer nanofiber electrolytes were fabricated by green reactive electrospinning nanotechnology from various water solution/dispersed blends of poly (vinyl alcohol-co-vinyl acetate) (PVA)/octadecyl amine-montmorillonite (ODA–MMT) as matrix polymer nanocomposite and poly(maleic acid-alt-acrylic acid) (poly(MAc-alt-AA) and/or its Ag-carrying complex as partner copolymers. Polymer nanofiber electrolytes were characterized using FTIR, XRD, thermal (DSC, TGA–DTG), SEM, and electrical analysis methods. Effects of partner copolymers, organoclay, in situ generated silver nanoparticles (AgNPs), and annealing procedure on physical and chemical properties of polymer composite nanofibers were investigated. The electrical properties (resistance, conductivity, activation energy) of nanofibers with/without NaOH doping agent were also evaluated. This work presented a structural rearrangement of nanofiber mats by annealing via decarboxylation of anhydride units with the formation of new conjugated double bond sites onto partner copolymer main chains. It was also found that the semiconductor behaviors of nanofiber structures were essentially improved with increasing temperature and fraction of partner copolymers as well as presence of organoclay and AgNPs in nanofiber composite.

  4. LC-MS/MS quantification of N-acetylneuraminic acid, N-glycolylneuraminic acid and ketodeoxynonulosonic acid levels in the urine and potential relationship with dietary sialic acid intake and disease in 3- to 5-year-old children.

    PubMed

    Chen, Yue; Pan, Lili; Liu, Ni; Troy, Frederic A; Wang, Bing

    2014-01-28

    Red meat and dairy products contain high sialic acid (Sia) levels, but the metabolic fate and health impact in children remain unknown. The aims of the present study were to quantify the levels of urinary Sia N-acetylneuraminic acid (Neu5Ac), N-glycolylneuraminic acid (Neu5Gc) and ketodeoxynonulosonic acid (KDN) and to determine their relationship with dietary Sia intake. Spot urine samples were collected from 386 healthy children aged 3 (n 108), 4 (n 144) and 5 (n 134) years at 06.30-07.00, 11.30-12.00 and 16.30-17.00 hours. Food intake levels were recorded on the day of urine sample collection. Sia levels were quantified using LC-MS/MS with [13C3]Sia as an internal standard. We found that (1) total urinary Sia levels in healthy pre-school children ranged from 40 to 79 mmol Sia/mol creatinine; (2) urinary Sia levels were independent of age and consisted of conjugated Neu5Ac (approximately 70·8 %), free Neu5Ac (approximately 21·3 %), conjugated KDN (approximately 4·2 %) and free KDN (approximately 3·7 %); Neu5Gc was detected in the urine of only one 4-year-old girl; (3) total urinary Sia levels were highest in the morning and declined over time in 4- and 5-year-old children (P< 0·05), but not in 3-year-old children; (4) Sia intake levels at breakfast and lunch were approximately 2·5 and 0·16 mg Sia/kg body weight; and (5) there was no significant correlation between dietary Sia intake levels and urinary Sia levels. Urinary Sia levels varied with age and time of day, but did not correlate with Sia intake in 3- to 5-year-old children. The difference in urinary Sia levels in children of different age groups suggests that the metabolism and utilisation rates of dietary Sia are age dependent. PMID:23915700

  5. Chlorogenic acid increased 5-hydroxymethylfurfural formation when heating fructose alone or with aspartic acid at two pH levels.

    PubMed

    Zhang, Zhenhua; Zou, Yueyu; Wu, Taigang; Huang, Caihuan; Pei, Kehan; Zhang, Guangwen; Lin, Xiaohua; Bai, Weibin; Ou, Shiyi

    2016-01-01

    Chlorogenic acid (CGA) is a phenolic acid that ubiquitously exists in fruits. This work aims to investigate whether and how CGA influences HMF formation during heating fructose alone, or with an amino acid. The results showed that that CGA increased 5-hydroxymethylfurfural (HMF) formation. At pH 5.5 and 7.0, the addition of 5.0 μmol/ml CGA increased HMF formation by 49.4% and 25.2%, respectively when heating fructose alone, and by 9.0% and 16.7%, respectively when heating fructose with aspartic acid. CGA significantly increased HMF formation by promoting 3-deoxosone formation, and its conversion to HMF by inhibiting HMF elimination, especially in the Maillard reaction system. A comparison of the catalytic capacity of CGA with its six analogous compounds showed that both its di-hydroxyphenyl and carboxyl groups function in increasing HMF formation. PMID:26213045

  6. Erythrocyte membrane docosapentaenoic acid levels are associated with islet autoimmunity: The Diabetes Autoimmunity Study in the Young

    PubMed Central

    Norris, Jill M.; Kroehl, Miranda; Fingerlin, Tasha E.; Frederiksen, Brittni N.; Seifert, Jennifer; Wong, Randall; Clare-Salzler, Michael; Rewers, Marian

    2013-01-01

    Aims/hypotheses We previously reported that lower n-3 fatty acid intake and levels in erythrocyte membranes were associated with increased risk of islet autoimmunity (IA) but not progression to type 1 diabetes in children at increased risk for diabetes. We hypothesise that specific n-3 fatty acids and genetic markers contribute synergistically to this increased risk of IA in the Diabetes Autoimmunity Study in the Young (DAISY). Methods DAISY is following 2547 children at increased risk for type 1 diabetes for the development of IA, defined as being positive for glutamic acid decarboxylase (GAD)65, IA-2 or insulin autoantibodies on two consecutive visits. Using a case-cohort design, erythrocyte membrane fatty acids and dietary intake were measured prospectively in 58 IA-positive children and 299 IA-negative children. Results Lower membrane levels of the n-3 fatty acid, docosapentaenoic acid (DPA), were predictive of IA (HR 0.23; 95% CI 0.09,0.55), while alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were not, adjusting for HLA and diabetes family history. We examined whether the effect of dietary intake of the n-3 fatty acid ALA on IA risk was modified by fatty acid elongation and desaturation genes. Adjusting for HLA, diabetes family history, ethnicity, energy intake and questionnaire type, ALA intake was significantly more protective for IA in the presence of an increasing number of minor alleles at FADS1 rs174556 (pinteraction=0.017), at FADS2 rs174570 (pinteraction=0.016) and at FADS2 rs174583 (pinteraction=0.045). Conclusions/interpretation The putative protective effect of n-3 fatty acids on IA may result from a complex interaction between intake and genetically-controlled fatty acid desaturation. PMID:24240437

  7. What is the safe upper intake level of folic acid for the nervous system? Implications for folic acid fortification policies.

    PubMed

    Reynolds, E H

    2016-05-01

    Between 1945 and 1959 it was convincingly documented that folic acid can precipitate or aggravate the neurological and haematological consequences of vitamin B12 deficiency by increasing the demand for vitamin B12. Since then there has been much misunderstanding of the issues, mainly by advocates of folic acid fortification who have been inclined to minimise or even dismiss the risks by misinterpreting the evidence as only a 'masking' of the anaemia of pernicious anaemia. Recent studies in the era of fortification are rediscovering the risks to the nervous system, especially cognitive function, of excess folate in the presence of vitamin B12 deficiency. I have reviewed the Reports of four Expert Advisory Committees in Europe and the USA, which suggest that the safe upper tolerable limit (UL) for folic acid is 1 mg in adults. These reports are unsound and there is already evidence of neurological harm from long-term exposure to doses of folic acid between 0.5 and 1 mg in the presence of vitamin B12 deficiency. There is an urgent need to review the safe UL for folic acid and to consider the addition of vitamin B12 to folic acid fortification policies. PMID:26862004

  8. Milk production responses to dietary stearic acid vary by production level in dairy cattle.

    PubMed

    Piantoni, P; Lock, A L; Allen, M S

    2015-03-01

    Effects of stearic acid supplementation on feed intake and metabolic and production responses of dairy cows with a wide range of milk production (32.2 to 64.4 kg/d) were evaluated in a crossover design experiment with a covariate period. Thirty-two multiparous Holstein cows (142±55 d in milk) were assigned randomly within level of milk yield to treatment sequence. Treatments were diets supplemented (2% of diet dry matter) with stearic acid (SA; 98% C18:0) or control (soyhulls). The diets were based on corn silage and alfalfa and contained 24.5% forage neutral detergent fiber, 25.1% starch, and 17.3% crude protein. Treatment periods were 21 d with the final 4 d used for data and sample collection. Compared with the control, SA increased dry matter intake (DMI; 26.1 vs. 25.2 kg/d) and milk yield (40.2 vs. 38.5 kg/d). Stearic acid had no effect on the concentration of milk components but increased yields of fat (1.42 vs. 1.35 kg/d), protein (1.19 vs. 1.14 kg/d), and lactose (1.96 vs. 1.87 kg/d). The SA treatment increased 3.5% fat-corrected milk (3.5% FCM; 40.5 vs. 38.6 kg/d) but did not affect feed efficiency (3.5% FCM/DMI, 1.55 vs. 1.53), body weight, or body condition score compared with the control. Linear interactions between treatment and level of milk yield during the covariate period were detected for DMI and yields of milk, fat, protein, lactose, and 3.5% FCM; responses to SA were positively related to milk yield of cows. The SA treatment increased crude protein digestibility (67.4 vs. 65.5%), tended to increase neutral detergent fiber digestibility (43.6 vs. 42.3%), decreased fatty acid (FA) digestibility (56.6 vs. 76.1%), and did not affect organic matter digestibility. Fatty acid yield response, calculated as the additional FA yield secreted in milk per unit of additional FA intake, was only 13.3% for total FA and 8.2% for C18:0 plus cis-9 C18:1. Low estimated digestibility of the SA supplement was at least partly responsible for the low FA yield response

  9. Lysine-doped polypyrrole/spider silk protein/poly(l-lactic) acid containing nerve growth factor composite fibers for neural application.

    PubMed

    Zhang, Hong; Wang, Kefeng; Xing, Yiming; Yu, Qiaozhen

    2015-11-01

    Lysine-doped polypyrrole (PPy)/regenerated spider silk protein (RSSP)/poly(l-lactic) acid (PLLA)/nerve growth factor (NGF) (L-PRPN) composite scaffold was fabricated by co-axial electrospraying and electrospinning. This L-PRPN composite scaffold had a structure of microfibers with a core-shell structure as the stems and nanofibers as branches. Assessment in vitro demonstrated that the L-PRPN composite micro/nano-fibrous scaffold could maintain integrated structure for at least 4months and the pH value of PBS at about 7.28. It had good biocompatibility and cell adhesion and relatively stable conductivity. PC 12 cells cultured on this scaffold, anisotropic cell-neurite-cell-neurite or neurite-neurite sheets were formed after being cultured for 6days. Evaluations in vivo also showed that L-PRPN composite fibrous conduit was effective at bridging 2.0cm sciatic nerve gap in adult rat within 10months. This conduit and electrical stimulation (ES) through it promoted Schwann cell migration and axonal regrowth. PMID:26249628

  10. Aptameric Recognition-Modulated Electroactivity of Poly(4-Styrenesolfonic Acid)-Doped Polyaniline Films for Single-Shot Detection of Tetrodotoxin

    PubMed Central

    Fomo, Gertrude; Waryo, Tesfaye T.; Sunday, Christopher E.; Baleg, Abd A.; Baker, Priscilla G.; Iwuoha, Emmanuel I.

    2015-01-01

    The work being reported is the first electrochemical sensor for tetrodotoxin (TTX). It was developed on a glassy carbon electrodes (C) that was modified with poly(4-styrenesolfonic acid)-doped polyaniline film (PANI/PSSA). An amine-end functionalized TTX-binding aptamer, 5′-NH2-AAAAATTTCACACGGGTGCCTCGGCTGTCC-3′ (NH2-Apt), was grafted via covalent glutaraldehyde (glu) cross-linking. The resulting aptasensor (C//PANI+/PSSA-glu-NH2-Apt) was interrogated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in sodium acetate buffer (NaOAc, pH 4.8) before and after 30 min incubation in standard TTX solutions. Both CV and EIS results confirmed that the binding of the analyte to the immobilized aptamer modulated the electrochemical properties of the sensor: particularly the charge transfer resistance (Rct) of the PANI+/PSSA film, which served as a signal reporter. Based on the Rct calibration curve of the TTX aptasensor, the values of the dynamic linear range (DLR), sensitivity and limit of detection (LOD) of the sensor were determined to be 0.23–1.07 ng·mL−1 TTX, 134.88 ± 11.42 Ω·ng·mL−1 and 0.199 ng·mL−1, respectively. Further studies are being planned to improve the DLR as well as to evaluate selectivity and matrix effects in real samples. PMID:26370994

  11. High-Performance Flexible Solid-State Carbon Cloth Supercapacitors Based on Highly Processible N-Graphene Doped Polyacrylic Acid/Polyaniline Composites

    NASA Astrophysics Data System (ADS)

    Wang, Yongguang; Tang, Shaochun; Vongehr, Sascha; Ali Syed, Junaid; Wang, Xiangyu; Meng, Xiangkang

    2016-02-01

    Improving the solubility of conductive polymers to facilitate processing usually decreases their conductivity, and they suffer from poor cycling stability due to swelling-shrinking during charging cycles. We circumvent these problems with a novel preparation method for nitrogen-doped graphene (NG) enhanced polyacrylic acid/polyaniline (NG-PAA/PANI) composites, ensuring excellent processibility for scalable production. The content of PANI is maximized under the constraint of still allowing defect-free coatings on filaments of carbon cloth (CC). The NG content is then adjusted to optimize specific capacitance. The optimal CC electrodes have 32 wt.% PANI and 1.3 wt.% NG, thus achieving a high capacitance of 521 F/g at 0.5 F/g. A symmetric supercapacitor made from 20 wt.% PANI CC electrodes has more than four times the capacitance (68 F/g at 1 A/g) of previously reported flexible capacitors based on PANI-carbon nanotube composites, and it retains the full capacitance under large bending angles. The capacitor exhibits high energy and power densities (5.8 Wh/kg at 1.1 kW/kg), a superior rate capability (still 81% of the 1 A/g capacitance at 10 A/g), and long-term electrochemical stability (83.2% retention after 2000 cycles).

  12. Poly(acrylic acid) modified lanthanide-doped GdVO4 hollow spheres for up-conversion cell imaging, MRI and pH-dependent drug release.

    PubMed

    Kang, Xiaojiao; Yang, Dongmei; Dai, Yunlu; Shang, Mengmeng; Cheng, Ziyong; Zhang, Xiao; Lian, Hongzhou; Ma, Ping'an; Lin, Jun

    2013-01-01

    In this study, multifunctional poly(acrylic acid) modified lanthanide-doped GdVO(4) nanocomposites [PAA@GdVO(4): Ln(3+) (Ln = Yb/Er, Yb/Ho, Yb/Tm)] were constructed by filling PAA hydrogel into GdVO(4) hollow spheres via photoinduced polymerization. The up-conversion (UC) emission colors (green, red and blue) can be tuned by changing the codopant compositions in the matrices. The composites have potential applications as bio-probes for cell imaging. Meanwhile, the hybrid spheres can act as T(1) contrast agents for magnetic resonance imaging (MRI) owing to the existence of Gd(3+) ions on the surface of composites. Due to the nature of PAA, DOX-loaded PAA@GdVO(4):Yb(3+)/Er(3+) system exhibits pH-dependent drug releasing kinetics. A lower pH offers a faster drug release rate. Such character makes the loaded DOX easily released at cancer cells. The cell uptake process of drug-loaded composites was observed by using confocal laser scanning microscopy (CLSM). The results indicate the potential application of the multifunctional composites as theragnostics (effective bimodal imaging probes and pH-responsive drug carriers). PMID:23154448

  13. N-doped carbon dots derived from bovine serum albumin and formic acid with one- and two-photon fluorescence for live cell nuclear imaging.

    PubMed

    Tan, Mingqian; Li, Xintong; Wu, Hao; Wang, Beibei; Wu, Jing

    2015-12-01

    Carbon dots with both one- and two-photon fluorescence have drawn great attention for biomedical imaging. Herein, nitrogen-doped carbon dots were facilely developed by one-pot hydrothermal method using bovine serum albumin and formic acid as carbon sources. They are highly water-soluble with strong fluorescence when excited with ultraviolet or near infrared light. The carbon dots have a diameter of ~8.32 nm and can emit strong two-photon induced fluorescence upon excitation at 750 nm with a femtosecond laser. X-ray photoelectron spectrometer analysis revealed that the carbon dots contained three components, C, N and O, corresponding to the peak at 285, 398 and 532 eV, respectively. The Fourier-transform infrared spectroscopy analysis revealed that there are carboxyl and carboxylic groups on the surface, which allowed further linking of functional molecules. pH stability study demonstrated that the carbon dots are able to be used in a wide range of pH values. The fluorescence mechanism is also discussed in this study. Importantly, these carbon dots are biocompatible and highly photostable, which can be directly applied for both one- and two-photon living cell imaging. After proper surface functionalization with TAT peptide, they can be used as fluorescent probes for live cell nuclear-targeted imaging. PMID:26381697

  14. Cobalt carbonate dumbbells for high-capacity lithium storage: A slight doping of ascorbic acid and an enhancement in electrochemical performances

    NASA Astrophysics Data System (ADS)

    Zhao, Shiqiang; Wei, Shanshan; Liu, Rui; Wang, Yuxi; Yu, Yue; Shen, Qiang

    2015-06-01

    Synthesis of materials with desirable nanostructures is a hot research topic owing to their enhanced performances in contrast to the bulk counterparts. Herein, dumbbell-shaped cobalt carbonate (CoCO3) nano architectures and the bulk counterpart of CoCO3 rhombohedra are prepared via a facile hydrothermal route in the presence and absence of ascorbic acid (AA), respectively. By comparison, it has been found that: the addition of AA in the hydrothermal crystallization system changes the shape of the building blocks from Co2CO3(OH)2 nanosheets to CoCO3 nanoparticles, and then further influences the final configuration of the products. When applied as anodes of lithium ion batteries, CoCO3 dumbbells deliver a 100th capacity of 1042 mAh g-1 at 200 mA g-1 and even exhibit a long-term value of 824 mAh g-1 over 500 cycles at 1000 mA g-1, which are much higher than the rhombohedral counterparts with corresponding 540 and 481 mAh g-1 respectively. The much higher capacity, better cycling stability and enhanced rate performance of CoCO3 dumbbells can be attributed to the higher specific surface area, smaller charge transport resistance and better structure stability resulting from the slight doping (∼4.6 wt%) of AA, and also relate with a novel lithium storage mechanism in CoCO3.

  15. An ultrasensitive electrochemical sensor for simultaneous determination of xanthine, hypoxanthine and uric acid based on Co doped CeO2 nanoparticles.

    PubMed

    Lavanya, N; Sekar, C; Murugan, R; Ravi, G

    2016-08-01

    A novel electrochemical sensor has been fabricated using Co doped CeO2 nanoparticles for selective and simultaneous determination of xanthine (XA), hypoxanthine (HXA) and uric acid (UA) in a phosphate buffer solution (PBS, pH5.0) for the first time. The Co-CeO2 NPs have been prepared by microwave irradiation method and characterized by Powder XRD, Raman spectroscopy, HRTEM and VSM measurements. The electrochemical behaviours of XA, HXA and UA at the Co-CeO2 NPs modified glassy carbon electrode (GCE) were studied by cyclic voltammetry and square wave voltammetry methods. The modified electrode exhibited remarkably well-separated anodic peaks corresponding to the oxidation of XA, HXA and UA over the concentration range of 0.1-1000, 1-600 and 1-2200μM with detection limits of 0.096, 0.36, and 0.12μM (S/N=3), respectively. For simultaneous detection by synchronous change of the concentrations of XA, HXA and UA, the linear responses were in the range of 1-400μM each with the detection limits of 0.47, 0.26, and 0.43μM (S/N=3), respectively. The fabricated sensor was further applied to the detection of XA, HXA and UA in human urine samples with good selectivity and high reproducibility. PMID:27157753

  16. Metal ions doped chitosan-poly(acrylic acid) nanospheres: Synthesis and their application in simultaneously electrochemical detection of four markers of pancreatic cancer.

    PubMed

    Rong, Qinfeng; Feng, Feng; Ma, Zhanfang

    2016-01-15

    In this work, a one-pot method was designed to synthesize copper ions, cadmium ions, lead ions and zinc ions doped chitosan-poly(acrylic acid) nanospheres. Those nanospheres can not only produce independent electrochemical signals, but also react with glutaraldehyde (GA) to immobilize different labeled antibodies. Using the modified nanospheres as immunoprobes, a sandwich-type immunosensor was fabricated to simultaneous detection of four tumor markers (CEA, CA199, CA125 and CA242) of pancreatic cancer. This designed immunosensor exhibited good linear relationships in range from 0.1 to 100ng mL(-1) for CEA, 1 to 150UmL(-1) for CA199, CA125 and CA242, corresponding detection limits 0.02ng mL(-1), 0.4UmL(-1), 0.3UmL(-1) and 0.4UmL(-1), respectively. Meanwhile, the immunosensor was applied in analysis of clinical serum samples, whose results were well agreed with the enzyme-linked immunosorbent assay (ELISA), indicating that the proposed immunosensor gave a hope for the identification and validation of specific early cancer. PMID:26318783

  17. High-Performance Flexible Solid-State Carbon Cloth Supercapacitors Based on Highly Processible N-Graphene Doped Polyacrylic Acid/Polyaniline Composites.

    PubMed

    Wang, Yongguang; Tang, Shaochun; Vongehr, Sascha; Syed, Junaid Ali; Wang, Xiangyu; Meng, Xiangkang

    2016-01-01

    Improving the solubility of conductive polymers to facilitate processing usually decreases their conductivity, and they suffer from poor cycling stability due to swelling-shrinking during charging cycles. We circumvent these problems with a novel preparation method for nitrogen-doped graphene (NG) enhanced polyacrylic acid/polyaniline (NG-PAA/PANI) composites, ensuring excellent processibility for scalable production. The content of PANI is maximized under the constraint of still allowing defect-free coatings on filaments of carbon cloth (CC). The NG content is then adjusted to optimize specific capacitance. The optimal CC electrodes have 32 wt.% PANI and 1.3 wt.% NG, thus achieving a high capacitance of 521 F/g at 0.5 F/g. A symmetric supercapacitor made from 20 wt.% PANI CC electrodes has more than four times the capacitance (68 F/g at 1 A/g) of previously reported flexible capacitors based on PANI-carbon nanotube composites, and it retains the full capacitance under large bending angles. The capacitor exhibits high energy and power densities (5.8 Wh/kg at 1.1 kW/kg), a superior rate capability (still 81% of the 1 A/g capacitance at 10 A/g), and long-term electrochemical stability (83.2% retention after 2000 cycles). PMID:26883179

  18. High-Performance Flexible Solid-State Carbon Cloth Supercapacitors Based on Highly Processible N-Graphene Doped Polyacrylic Acid/Polyaniline Composites

    PubMed Central

    Wang, Yongguang; Tang, Shaochun; Vongehr, Sascha; Ali Syed, Junaid; Wang, Xiangyu; Meng, Xiangkang

    2016-01-01

    Improving the solubility of conductive polymers to facilitate processing usually decreases their conductivity, and they suffer from poor cycling stability due to swelling-shrinking during charging cycles. We circumvent these problems with a novel preparation method for nitrogen-doped graphene (NG) enhanced polyacrylic acid/polyaniline (NG-PAA/PANI) composites, ensuring excellent processibility for scalable production. The content of PANI is maximized under the constraint of still allowing defect-free coatings on filaments of carbon cloth (CC). The NG content is then adjusted to optimize specific capacitance. The optimal CC electrodes have 32 wt.% PANI and 1.3 wt.% NG, thus achieving a high capacitance of 521 F/g at 0.5 F/g. A symmetric supercapacitor made from 20 wt.% PANI CC electrodes has more than four times the capacitance (68 F/g at 1 A/g) of previously reported flexible capacitors based on PANI-carbon nanotube composites, and it retains the full capacitance under large bending angles. The capacitor exhibits high energy and power densities (5.8 Wh/kg at 1.1 kW/kg), a superior rate capability (still 81% of the 1 A/g capacitance at 10 A/g), and long-term electrochemical stability (83.2% retention after 2000 cycles). PMID:26883179

  19. A simple synthesis of nitrogen doped porous graphitic carbon: Electrochemical determination of paracetamol in presence of ascorbic acid and p-aminophenol.

    PubMed

    Biswas, Sudip; Chakraborty, Dipanjan; Das, Rashmita; Bandyopadhyay, Rajib; Pramanik, Panchanan

    2015-08-26

    Graphite paste electrode modified with nitrogen doped porous carbon (NDPC) is used for the detections of paracetamol (PCM), ascorbic acid (AA) and p-aminophenol (PAP) at relatively low concentration. NDPC is synthesized by direct carbonization of Zn(OAc)2 incorporated melamine-formaldehyde resin microsphere. The NDPC shows small pore diameters centered at 3.14 nm and 8.12 nm and has a pseudo graphitic structure with reasonable porous matrix. The lower limit of detections (S/N = 3) for PCM, AA, and PAP are found to be 30 nM, 720 nM and 10 nM respectively. Under optimized experimental condition, the linear ranges of determination for PCM and AA are 1-400 μM, 10-2700 μM respectively in mixture. Similarly for PCM and PAP mixture, the linear ranges of determination are found to be 1-90 μM. It is also used for the analysis of urine and pharmaceutical products with better sensitivity. PMID:26347171

  20. Non-redox modulated fluorescence strategy for sensitive and selective ascorbic acid detection with highly photoluminescent nitrogen-doped carbon nanoparticles via solid-state synthesis.

    PubMed

    Zhu, Xiaohua; Zhao, Tingbi; Nie, Zhou; Liu, Yang; Yao, Shouzhuo

    2015-08-18

    Highly photoluminescent nitrogen-doped carbon nanoparticles (N-CNPs) were prepared by a simple and green route employing sodium alginate as a carbon source and tryptophan as both a nitrogen source and a functional monomer. The as-synthesized N-CNPs exhibited excellent water solubility and biocompatibility with a fluorescence quantum yield of 47.9%. The fluorescence of the N-CNPs was intensively suppressed by the addition of ascorbic acid (AA). The mechanism of the fluorescence suppression of the N-CNPs was investigated, and the synergistic action of the inner filter effect (IFE) and the static quenching effect (SQE) contributed to the intensive fluorescence suppression, which was different from those reported for the traditional redox-based fluorescent probes. Owing to the spatial effect and hydrogen bond between the AA and the groups on the N-CNP surface, excellent sensitivity and selectivity for AA detecting was obtained in a wide linear relationship from 0.2 μM to 150 μM. The detection limit was as low as 50 nM (signal-to-noise ratio of 3). The proposed sensing systems also represented excellent sensitivity and selectivity for AA analysis in human biological fluids, providing a valuable platform for AA sensing in clinic diagnostic and drug screening. PMID:26202861

  1. Kinetic study of formic acid degradation by Fe3+ doped TiO2 self-cleaning nanostructure surfaces prepared by cold spray

    NASA Astrophysics Data System (ADS)

    Sayyar, Zahra; Akbar Babaluo, Ali; Shahrouzi, Javad Rahbar

    2015-04-01

    A self-cleaning solution was introduced in this paper based on sol-gel and was applied for preparing self-cleaning TiO2. Fe3+ ions have been doped into the TiO2 crystal lattice. XRD analysis indicated that the obtained TiO2 powder contains mainly the anatase phase and TiO2 powder has a crystallite size distribution of 10-12 nm. SEM micrographs have also confirmed nanometric distribution of the obtained powder. A series of uniform and transparent TiO2 and Fe/TiO2 films were prepared by cold spray technique which may result in high uniformity in the final coated surfaces. Photocatalytic activity of the thin films was investigated through degradation of aqueous formic acid under UV-visible light. The Langmuir-Hinshelwood kinetic model was used to interpret quantitatively the observed kinetic experimental result. Comparative study of the obtained coated surfaces with those of uncoated surfaces, demonstrated a remarkable performance. The Fe/TiO2 films and their calcination at 650 °C demonstrated the highest photocatalytic activity.

  2. Regulation of auxin, abscisic acid and salicylic acid levels by ascorbate application under heat stress in sensitive and tolerant maize leaves.

    PubMed

    Dinler, Burcu Seckin; Demir, Emel; Kompe, Yasemin Ozdener

    2014-12-01

    In the present study, the effect of ascorbic acid (5 mM) on some physiological parameters and three hormones (auxin, abscisic acid, salicylic acid) was determined under heat stress (40 °C) in maize tolerant cv. (MAY 69) and sensitive cv. SHEMAL (SH) at 0 h, 4 h and 8 h. Heat stress reduced total chlorophyll content (CHL), relative water content (RWC) and stomatal conductance (gs) in SH but did not lead to changes in MAY 69 at 4 h and 8 h. However, pretreatment with ascorbic acid increased (CHL), (RWC) and (gs) in SH under heat stress while it reduced MDA content significantly in both cv. We also observed that heat stress led to a reduction in SA level but increased ABA and IAA levels in SH, whereas it increased SA and IAA levels but did not change ABA level in MAY 69 at 4 h. Furthermore, in SH, ASC application under heat stress increased SA level and decreased IAA and ABA levels at 4 h, but it had no effect on SA and ABA at 8 h. PMID:25475985

  3. Uric acid blood levels and relationship with the components of metabolic syndrome in hypertensive patients.

    PubMed

    Papavasileiou, M V; Karamanou, A G; Kalogeropoulos, P; Moustakas, G; Patsianis, S; Pittaras, A

    2016-07-01

    Associations between high serum uric acid (SUA) levels and high blood pressure (BP), as well as between SUA levels and metabolic syndrome (MetS) have already been reported. The aim of the study was to investigate the relationship between the components of MetS with the SUA levels as also between SUA and apolipoproteins A1 and B (apoA1 and apoB) ratio in hypertensive patients. A total of 2577 consecutive hypertensive patients (1193 male and 1384 female) aged 57.5±13.3 years, were enrolled in our research. Samples were taken to measure SUA, glucose, triglycerides, high density lipoprotein (HDL-C), components of the MetS and apoA1 and apoB. The study population was divided into two groups: group A: SUA levels above normal range (men ⩾7 mg dl(-1), women ⩾6 mg dl(-1)) and group B: SUA levels within normal range. In the overall study population, SUA levels showed a statistically significant correlation with waist circumference (WC; r=0.293, P<0.000), triglycerides (r=0.197, P<0.000), glucose (r=0.085, P<0.000), apoB/apoA1 (r=0.136, P<0.000) and HDL-C (r=-0.235, P<0,001). In newly diagnosed untreated hypertensive patients there was also a statistically significant correlation of SUA levels with WC (r=0.331, P<0.001), triglycerides (r=0.228, P<0.001) apoB/apoA1 ratio (r=0.202, P<0.001) and HDL-C (r=-0.278, P<0.001). In hyperurecemic hypertensives there was a statistically significant correlation between SUA levels with WC (r=0.168, P=0.007), apoB/apoA1 ratio (r=0.256, P=0.003) and HDL-C (r=-0.202, P<0.001). SUA levels correlate significantly with all the components of MetS, as well as with the risk factor apoB/apoA1 ratio, in hypertensive patients. PMID:26134624

  4. Phytochemicals from Tradescantia albiflora Kunth Extracts Reduce Serum Uric Acid Levels in Oxonate-induced Rats

    PubMed Central

    Wang, Wen-Ling; Sheu, Shi-Yuan; Huang, Wen-Dar; Chuang, Ya-Ling; Tseng, Han-Chun; Hwang, Tzann-Shun; Fu, Yuan-Tsung; Kuo, Yueh-Hsiung; Yao, Chun-Hsu; Kuo, Tzong-Fu

    2016-01-01

    Background: Tradescantia albiflora (TA) Kunth (Commelinaceae) has been used for treating gout and hyperuricemia as folklore remedies in Taiwan. Therefore, it is worthwhile to study the effect of TA extracts on lowering uric acid activity. The hypouricemic effects of TA extracts on potassium oxonate (PO)-induced acute hyperuricemia were investigated for the first time. Materials and Methods: All treatments at the same volume (1 ml) were orally administered to the abdominal cavity of PO-induced hyperuricemic rats. One milliliter of TA extract in n-hexane (HE), ethyl acetate (EA), n-butanol (BuOH), and water fractions has 0.28, 0.21, 0.28, and 1.03 mg TA, respectively; and the plasma uric acid (PUA) level was measured for a consecutive 4 h after administration. Results: All four fractions' extracts derived from TA were observed to significantly reduce PUA compared with the PO group. The EA-soluble fraction (TA-EA) exhibited the best xanthine oxidase (XO) inhibitory activity. Following column chromatography, 12 phytochemicals were isolated and identified from the EA fraction. The IC50 values of isolated phytochemicals indicated that bracteanolide A (AR11) showed the remarkable XO inhibitory effect (IC50 value of 76.4 μg/ml). These findings showed that the in vivo hypouricemic effect in hyperuricemic rats was consistent with in vitro XO inhibitory activity, indicating that TA extracts and derived phytochemicals could be potential candidates as hypouricemic agents. SUMMARY Tradescantia albiflora extracts possess in vivo hypouricemic action in hyperuricemic ratsT. albiflora extracts exhibited strong inhibitory activity against xanthine oxidase (XO)Butenolide may play an important role in XO inhibitionThe extract bracteanolide A was demonstrated potent XO inhibitory activity in vitro. Abbreviations used: TA: Tradescantia albiflora, PO: potassium oxonate, HE: n-hexane, EA: ethyl acetate, BuOH: n-butanol, PUA: plasma uric acid, XO: xanthine oxidase, MeOH: methanol, IP

  5. Mechanism of Enhanced Electrochemical Oxidation of 2,4-dichlorophenoxyacetic Acid with in situ Microwave Activated Boron-doped Diamond and Platinum Anodes

    NASA Astrophysics Data System (ADS)

    Gao, Junxia; Zhao, Guohua; Liu, Meichuan; Li, Dongming

    2009-09-01

    Remarkable enhancement in degradation effect is achieved at in situ activated boron-doped diamond (BDD) and Pt anodes with different extent through electrochemical oxidation (EC) of 2,4-dichlorophenoxyacetic acid (2,4-D) with microwave (MW) radiation in a flow system. Results show that when EC is activated with MW radiation, the complete mineralization time of 2,4-D at the BDD is reduced quickly from 10 to 4 h while Chemical oxygen demand (COD) removal at Pt is increased from 37.7 to 58.3% at 10 h; the initial current efficiency is both improved about 1.5 times while the pseudo-first-order rate constant is increased by 153 and 119% at the BDD and Pt, respectively. To gain insight into the higher efficiency in microwave activated EC, the mechanism has therefore been systematically evaluated from the essence of electrochemical reaction and the accumulated hydroxyl radical concentration. 2,4-Dichlorophenol, catechol, benquinone, and maleic and oxalic acids are the main intermediates on the Pt anode measured by high performance liquid chromatography (HPLC), while the intermediates on the BDD electrode include 2,4-dichlorophenol, hydroquinone, and maleic and oxalic acids. The reaction pathway with microwave radiation is the same as that in a conventional electrochemical oxidation on both electrodes. While less and lower aromatic intermediates produce at the BDD with MW, which suggests the higher ring-open ratio and the faster oxidation of carboxylic acids. With microwave radiation, the ring-open ratio at the BDD is increased to 98.8% from 85.6%; the value at Pt is increased to 67.3% from 35.9%. So microwave radiation can activate the electrochemical oxidation, which leads to the higher efficiency. This promotion is mainly due to the higher accumulated hydroxyl radical concentration and the effects by microwave radiation. All the results prove that the BDD electrode presents much better mineralization performance with MW. To the best of our knowledge, it is the first

  6. Effects of thermal annealing on deep-level defects and minority-carrier electron diffusion length in Be-doped InGaAsN

    SciTech Connect

    Xie, S.Y.; Yoon, S.F.; Wang, S.Z.

    2005-04-01

    We report the effects of ex situ thermal annealing on the deep-level defects and the minority-carrier electron diffusion length in Be-doped, p-type In{sub 0.03}Ga{sub 0.97}As{sub 0.99}N{sub 0.01} grown by solid source molecular-beam epitaxy. Deep-level transient spectroscopy measurements reveal two majority-carrier hole traps, HT1 (0.18 eV) and HT4 (0.59 eV), and two minority-carrier electron traps, ET1 (0.09 eV) and ET3 (0.41 eV), in the as-grown sample. For the sample with postgrowth thermal annealing, the overall deep-level defect-concentration is decreased. Two hole traps, HT2 (0.39 eV) and HT3 (0.41 eV), and one electron trap, ET2 (0.19 eV), are observed. We found that the minority-carrier electron diffusion length increases by {approx}30% and the leakage current of the InGaAsN/GaAs p-n junction decreases by 2-3 orders after thermal annealing. An increase of the net acceptor concentration after annealing is also observed and can be explained by a recently proposed three-center-complex model.

  7. Effect of 3-methylcholanthrene-induced increases in ascorbic acid levels on tissue. beta. -glucuronidase activity in rats

    SciTech Connect

    Calabrese, E.J.; Barrett, T.J.; Leonard, D.A.; Horton, H.M.; Kenyon, E.M.

    1988-01-01

    The interrelationship between tissue ascorbic acid levels and tissue ..beta..-glucuronidase activity was examined in rats injected with 3-methylcholanthrene, an agent which induces ascorbic acid synthesis in rats. Six Fisher 344 rats were dosed intraperitoneally (IP) with 30 mg/kg of 3-methylcholanthrene. Ascorbic acid levels and ..beta..-glucuronidase (..beta..-G) activity were determined for lung, liver and kidney tissues. In a follow-up study, rats were dosed for three consecutive days with 3-methylcholanthrene. Controls in both groups were dosed IP with Emulphor (EL-620). Animals were sacrificed one week after the final dosage and lung, liver and kidney tissues were examined.

  8. Serum Uric Acid Level and Diverse Impacts on Regional Arterial Stiffness and Wave Reflection

    PubMed Central

    Bian, Suyan; Guo, Hongyang; Ye, Ping; Luo, Leiming; Wu, Hongmei; Xiao, Wenkai

    2012-01-01

    Background: Both increased arterial stiffness and hyperuricaemia are associated with elevated cardiovascular risks. Little is known about the relations of serum uric acid (UA) level to regional arterial stiffness and wave reflection. The aim of the study was to investigate the gender-specific association of serum UA and indices of arterial function in a community-based investigation in China. Methods: Cross-sectional data from 2374 adults (mean age 58.24 years) who underwent routine laboratory tests, regional pulse wave velocity (PWV) and pulse wave analysis measurements were analyzed in a gender-specific manner. None of the participants had atherosclerotic cardiovascular disease, chronic renal failure, systemic inflammatory disease, gout, or were under treatment which would affect serum UA level. Results: Men had higher serum UA level than women. Subjects with hyperuricaemia had significantly higher carotid-ankle PWV in both genders (P< 0.05), and the carotid-femoral PWV (PWVc-f) was higher in women (P< 0.001) while the augmentation index was marginally lower in men (P = 0.049). Multiple regression analysis showed that serum UA was an independent determinant only for PWVc-f in women (β = 0.104, P = 0.027) when adjusted for atherogenic confounders. No other independent relationship was found between UA level and other surrogates of arterial stiffness. Conclusions: Serum UA levels are associated with alterations in systemic arterial stiffness that differ in men and women. Women might be more susceptible to large vascular damage associated with hyperuricaemia. PMID:23113222

  9. Lysophosphatidic Acid Level and the Incidence of Silent Brain Infarction in Patients with Nonvalvular Atrial Fibrillation

    PubMed Central

    Li, Zhen-Guang; Yu, Zhan-Cai; Yu, Yong-Peng; Ju, Wei-Ping; Wang, Dao-Zhen; Zhan, Xia; Wu, Xi-Juan; Zhou, Li

    2010-01-01

    Lysophosphatidic acid (LPA), which is proposed to play an important role in normal physiological situations such as wound healing, vascular tone, vascular integrity and reproduction, may be involved in the etiology of some diseases such as atherosclerosis, cancer, obesity or myocardial infarction. Abnormal findings, including silent brain infarction (SBI), are frequently observed by magnetic resonance imaging (MRI) in patients with nonvalvular atrial fibrillation (NVAF). However, whether there is a relationship between LPA level and the prevalence of SBI has not been extensively studied. In the present study, the association between them was investigated. 235 patients with NVAF, 116 cases of SBI without NVAF and 120 cases of healthy volunteers (control group), who did not receive any antithrombotic therapy, were enrolled in this study. Plasma LPA levels in the NVAF with SBI group were significantly higher than that in the control group (p < 0.01), NVAF without SBI group (p < 0.01) and SBI without NVAF group (p < 0.01). The LPA levels are lower in the control group than in the NVAF without SBI and SBI without NVAF groups (p < 0.01), however, the latter two groups did not significantly differ from each other for LPA levels (p > 0.05) There were significant differences in the positive rate of platelet activation between each of the groups (p < 0.01). The positive rate of platelet activation was significantly higher in the NVAF with SBI group. We suggest that LPA might be a novel marker for estimation of the status of platelet activation and the risk factor for SBI onset in NVAF patients. We expected that plasma LPA levels could predict the occurrence of SBI in NVAF patients. PMID:21152315

  10. Elevation of the level and activity of acid ceramidase in Alzheimer's disease brain.

    PubMed

    Huang, Yu; Tanimukai, Hitoshi; Liu, Fei; Iqbal, Khalid; Grundke-Iqbal, Inge; Gong, Cheng-Xin

    2004-12-01

    Protein glycosylation modifies the processing of several key proteins involved in the molecular pathogenesis of Alzheimer's disease (AD). Aberrant glycosylation of tau and down-regulation of sialyltransferase in AD brain suggest a possible dysregulation of protein glycosylation that may play a role in AD. We therefore isolated major glycoproteins from AD brain by using lectin-affinity chromatographies and ion-exchange chromatography and further separated them using SDS-polyacylamide gel electrophoresis. Mass spectrometry analysis of 11 isolated glycoproteins led to their identification as: neuronal cell adhesion molecule, beta-globin, IgM heavy chain VH1 region precursor, contactin precursor, dipeptidylpeptidase VI, CD81 partner 3, prenylcysteine lyase, adipocyte plasma-associated protein, acid ceramidase and two novel proteins. We found that the level and activity of acid ceramidase (AC), one of the major identified human brain glycoproteins, were significantly elevated in AD brain. Immunohistochemical staining indicated that AC was located mainly in the cell bodies of neurons and colocalized with neurofibrillary tangles. Our findings suggest that AC might play a role in controlling neuronal apoptosis and that AC-mediated signalling pathways might be involved in the molecular mechanism of AD. PMID:15610181

  11. Inhibition of Fatty Acid Binding Proteins Elevates Brain Anandamide Levels and Produces Analgesia

    PubMed Central

    Kaczocha, Martin; Rebecchi, Mario J.; Ralph, Brian P.; Teng, Yu-Han Gary; Berger, William T.; Galbavy, William; Elmes, Matthew W.; Glaser, Sherrye T.; Wang, Liqun; Rizzo, Robert C.; Deutsch, Dale G.; Ojima, Iwao

    2014-01-01

    The endocannabinoid anandamide (AEA) is an antinociceptive lipid that is inactivated through cellular uptake and subsequent catabolism by fatty acid amide hydrolase (FAAH). Fatty acid binding proteins (FABPs) are intracellular carriers that deliver AEA and related N-acylethanolamines (NAEs) to FAAH for hydrolysis. The mammalian brain expresses three FABP subtypes: FABP3, FABP5, and FABP7. Recent work from our group has revealed that pharmacological inhibition of FABPs reduces inflammatory pain in mice. The goal of the current work was to explore the effects of FABP inhibition upon nociception in diverse models of pain. We developed inhibitors with differential affinities for FABPs to elucidate the subtype(s) that contributes to the antinociceptive effects of FABP inhibitors. Inhibition of FABPs reduced nociception associated with inflammatory, visceral, and neuropathic pain. The antinociceptive effects of FABP inhibitors mirrored their affinities for FABP5, while binding to FABP3 and FABP7 was not a predictor of in vivo efficacy. The antinociceptive effects of FABP inhibitors were mediated by cannabinoid receptor 1 (CB1) and peroxisome proliferator-activated receptor alpha (PPARα) and FABP inhibition elevated brain levels of AEA, providing the first direct evidence that FABPs regulate brain endocannabinoid tone. These results highlight FABPs as novel targets for the development of analgesic and anti-inflammatory therapeutics. PMID:24705380

  12. Atomic-Level Characterization of the Chain-Flipping Mechanism in Fatty-Acids Biosynthesis.

    PubMed

    Colizzi, Francesco; Masetti, Matteo; Recanatini, Maurizio; Cavalli, Andrea

    2016-08-01

    During fatty acids biosynthesis the elongating acyl chain is sequestered within the core of the highly conserved acyl carrier protein (ACP). At each catalytic step, the acyl intermediates are transiently delivered from ACP to the active site of the enzymatic counterparts and, at the same time, are protected from the solvent to prevent nonselective reactivity. Yet, the molecular determinants of such a universal transition-termed chain flipping-remain poorly understood. Here we capture the atomic-level details of the chain-flipping mechanism by using metadynamics simulations. We observe the fatty-acid chain gliding through the protein-protein interface with barely 30% of its surface exposed to water molecules. The small ACP's helix III acts as gatekeeper of the process, and we find its conformational plasticity critical for a successful substrate transfer. The results are in agreement with a wide range of experimental observations and provide unprecedented insight on the molecular determinants and driving forces of the chain-flipping process. PMID:27409360

  13. Caffeic Acid Phenethyl Ester Regulates PPAR's Levels in Stem Cells-Derived Adipocytes.

    PubMed

    Vanella, Luca; Tibullo, Daniele; Godos, Justyna; Pluchinotta, Francesca Romana; Di Giacomo, Claudia; Sorrenti, Valeria; Acquaviva, Rosaria; Russo, Alessandra; Li Volti, Giovanni; Barbagallo, Ignazio

    2016-01-01

    Hypertrophic obesity inhibits activation of peroxisome proliferators-activated receptor gamma (PPARγ), considered the key mediator of the fully differentiated and insulin sensitive adipocyte phenotype. We examined the effects of Caffeic Acid Phenethyl Ester (Cape), isolated from propolis, a honeybee hive product, on Adipose Stem Cells (ASCs) differentiation to the adipocyte lineage. Finally we tested the effects of Cape on insulin-resistant adipocytes. Quantification of Oil Red O-stained cells showed that lipid droplets decreased following Cape treatment as well as radical oxygen species formation. Additionally, exposure of ASC to high glucose levels decreased adiponectin and increased proinflammatory cytokines mRNA levels, which were reversed by Cape-mediated increase of insulin sensitivity. Cape treatment resulted in decreased triglycerides synthesis and increased beta-oxidation. Exposure of ASCs to Lipopolysaccharide (LPS) induced a reduction of PPARγ, an increase of IL-6 levels associated with a well-known stimulation of lipolysis; Cape partially attenuated the LPS-mediated effects. These observations reveal the main role of PPARγ in the adipocyte function and during ASC differentiation. As there is now substantial interest in functional food and nutraceutical products, the observed therapeutic value of Cape in insulin-resistance related diseases should be taken into consideration. PMID:26904104

  14. Lactic acid bacteria affect serum cholesterol levels, harmful fecal enzyme activity, and fecal water content

    PubMed Central

    Lee, Do Kyung; Jang, Seok; Baek, Eun Hye; Kim, Mi Jin; Lee, Kyung Soon; Shin, Hea Soon; Chung, Myung Jun; Kim, Jin Eung; Lee, Kang Oh; Ha, Nam Joo

    2009-01-01

    Background Lactic acid bacteria (LAB) are beneficial probiotic organisms that contribute to improved nutrition, microbial balance, and immuno-enhancement of the intestinal tract, as well as lower cholesterol. Although present in many foods, most trials have been in spreads or dairy products. Here we tested whether Bifidobacteria isolates could lower cholesterol, inhibit harmful enzyme activities, and control fecal water content. Methods In vitro culture experiments were performed to evaluate the ability of Bifidobacterium spp. isolated from healthy Koreans (20~30 years old) to reduce cholesterol-levels in MRS broth containing polyoxyethanylcholesterol sebacate. Animal experiments were performed to investigate the effects on lowering cholesterol, inhibiting harmful enzyme activities, and controlling fecal water content. For animal studies, 0.2 ml of the selected strain cultures (108~109 CFU/ml) were orally administered to SD rats (fed a high-cholesterol diet) every day for 2 weeks. Results B. longum SPM1207 reduced serum total cholesterol and LDL levels significantly (p < 0.05), and slightly increased serum HDL. B. longum SPM1207 also increased fecal LAB levels and fecal water content, and reduced body weight and harmful intestinal enzyme activities. Conclusion Daily consumption of B. longum SPM1207 can help in managing mild to moderate hypercholesterolemia, with potential to improve human health by helping to prevent colon cancer and constipation. PMID:19515264

  15. Caffeic Acid Phenethyl Ester Regulates PPAR's Levels in Stem Cells-Derived Adipocytes

    PubMed Central

    Vanella, Luca; Tibullo, Daniele; Godos, Justyna; Pluchinotta, Francesca Romana; Di Giacomo, Claudia; Sorrenti, Valeria; Acquaviva, Rosaria; Russo, Alessandra; Li Volti, Giovanni; Barbagallo, Ignazio

    2016-01-01

    Hypertrophic obesity inhibits activation of peroxisome proliferators-activated receptor gamma (PPARγ), considered the key mediator of the fully differentiated and insulin sensitive adipocyte phenotype. We examined the effects of Caffeic Acid Phenethyl Ester (Cape), isolated from propolis, a honeybee hive product, on Adipose Stem Cells (ASCs) differentiation to the adipocyte lineage. Finally we tested the effects of Cape on insulin-resistant adipocytes. Quantification of Oil Red O-stained cells showed that lipid droplets decreased following Cape treatment as well as radical oxygen species formation. Additionally, exposure of ASC to high glucose levels decreased adiponectin and increased proinflammatory cytokines mRNA levels, which were reversed by Cape-mediated increase of insulin sensitivity. Cape treatment resulted in decreased triglycerides synthesis and increased beta-oxidation. Exposure of ASCs to Lipopolysaccharide (LPS) induced a reduction of PPARγ, an increase of IL-6 levels associated with a well-known stimulation of lipolysis; Cape partially attenuated the LPS-mediated effects. These observations reveal the main role of PPARγ in the adipocyte function and during ASC differentiation. As there is now substantial interest in functional food and nutraceutical products, the observed therapeutic value of Cape in insulin-resistance related diseases should be taken into consideration. PMID:26904104

  16. A new classification of the amino acid side chains based on doublet acceptor energy levels.

    PubMed Central

    Sneddon, S F; Morgan, R S; Brooks, C L

    1988-01-01

    We describe a new classification of the amino acid side chains based on the potential energy level at which each will accept an extra (doublet) electron. The doublet acceptor energy level, and the doublet acceptor orbital were calculated using semiempirical INDO/2-UHF molecular orbital theory. The results of these calculations show that the side chains fall into four groups. We have termed these groups repulsive, insulating, semiconducting, and attractive in accordance with where each lies on the relative energy scale. We use this classification to examine the role of residues between the donor and acceptor in modulating the rate and mechanism of electron transfer in proteins. With the calculated acceptor levels, we construct a potential barrier for those residues between the donor and acceptor. It is the area beneath this barrier that determines the decay of electronic coupling between donor and acceptor, and thus the transfer rate. We have used this schematic approach to characterize the four electron transfer pathways in myoglobin recently studied by Mayo et al. (Mayo, S.L., W.R. Ellis, R.J. Crutchley, and H.B. Gray. 1986. Science [Wash. DC]. 233:948-952). PMID:3342271

  17. Serum uric acid level in patients with relapsing-remitting multiple sclerosis.

    PubMed

    Ashtari, Fereshteh; Bahar, Mohammadali; Aghaei, Maryam; Zahed, Arash

    2013-05-01

    Uric acid (UA) is a hydrophilic antioxidant product associated with multiple sclerosis (MS). We conducted a randomized case-control study to evaluate the serum level of UA in different phases of MS in comparison with levels in a healthy control population. Serum UA was checked in 130 patients with relapsing-remitting MS (85 patients in remitting and 45 patients in relapsing phase) and 50 age-matched controls using a quantitative enzyme-linked immunosorbent assay (ELISA). The mean concentrations of UA in serum was 6.41(±3.18)mg/dL in patients with remitting MS, 4.76(±1.66)mg/dL in patients with relapsing MS and 6.33(±2.94)mg/dL in controls. There was a significant difference between mean UA concentration in relapsing MS and remitting MS (p<0.001), and between patients with relapsing MS and controls (p=0.002); however, the difference between levels for patients in the remitting phase of MS and the control group was not significant (p=0.87). It seems probable that UA has a role in the prevention of disease activity in MS. PMID:23528410

  18. Plasma Elaidic Acid Level as Biomarker of Industrial Trans Fatty Acids and Risk of Weight Change: Report from the EPIC Study

    PubMed Central

    Chajès, Véronique; Biessy, Carine; Ferrari, Pietro; Romieu, Isabelle; Freisling, Heinz; Huybrechts, Inge; Scalbert, Augustin; Bueno de Mesquita, Bas; Romaguera, Dora; Gunter, Marc J.; Vineis, Paolo; Hansen, Camilla Plambeck; Jakobsen, Marianne Uhre; Clavel-Chapelon, Françoise; Fagherazzi, Guy; Boutron-Ruault, Marie-Christine; Katzke, Verana; Neamat-Allah, Jasmine; Boeing, Heiner; Bachlechner, Ursula; Trichopoulou, Antonia; Naska, Androniki; Orfanos, Philippos; Pala, Valeria; Masala, Giovanna; Mattiello, Amalia; Skeie, Guri; Weiderpass, Elisabete; Agudo, Antonio; Huerta, Jose Maria; Ardanaz, Eva; Sánchez, Maria Jose; Dorronsoro, Miren; Quirós, Jose Ramon; Johansson, Ingegerd; Winkvist, Anna; Sonested, Emily; Key, Tim; Khaw, Kay-Tee; Wareham, Nicolas J.; Peeters, Petra H.M.; Slimani, Nadia

    2015-01-01

    Background Few epidemiological studies have examined the association between dietary trans fatty acids and weight gain, and the evidence remains inconsistent. The main objective of the study was to investigate the prospective association between biomarker of industrial trans fatty acids and change in weight within the large study European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Methods Baseline plasma fatty acid concentrations were determined in a representative EPIC sample from the 23 participating EPIC centers. A total of 1,945 individuals were followed for a median of 4.9 years to monitor weight change. The association between elaidic acid level and percent change of weight was investigated using a multinomial logistic regression model, adjusted by length of follow-up, age, energy, alcohol, smoking status, physical activity, and region. Results In women, doubling elaidic acid was associated with a decreased risk of weight loss (odds ratio (OR) = 0.69, 95% confidence interval (CI) = 0.55-0.88, p = 0.002) and a trend was observed with an increased risk of weight gain during the 5-year follow-up (OR = 1.23, 95% CI = 0.97-1.56, p = 0.082) (p-trend<.0001). In men, a trend was observed for doubling elaidic acid level and risk of weight loss (OR = 0.82, 95% CI = 0.66-1.01, p = 0.062) while no significant association was found with risk of weight gain during the 5-year follow-up (OR = 1.08, 95% CI = 0.88-1.33, p = 0.454). No association was found for saturated and cis-monounsaturated fatty acids. Conclusions These data suggest that a high intake of industrial trans fatty acids may decrease the risk of weight loss, particularly in women. Prevention of obesity should consider limiting the consumption of highly processed foods, the main source of industrially-produced trans fatty acids. PMID:25675445

  19. Structure of a Microbial Community in Soil after Prolonged Addition of Low Levels of Simulated Acid Rain

    PubMed Central

    Pennanen, Taina; Fritze, Hannu; Vanhala, Pekka; Kiikkilä, Oili; Neuvonen, Seppo; Bååth, Erland

    1998-01-01

    Humus samples were collected 12 growing seasons after the start of a simulated acid rain experiment situated in the subarctic environment. The acid rain was simulated with H2SO4, a combination of H2SO4 and HNO3, and HNO3 at two levels of moderate acidic loads close to the natural anthropogenic pollution levels of southern Scandinavia. The higher levels of acid applications resulted in acidification, as defined by humus chemistry. The concentrations of base cations decreased, while the concentrations of exchangeable H+, Al, and Fe increased. Humus pH decreased from 3.83 to 3.65. Basal respiration decreased with decreasing humus pH, and total microbial biomass, measured by substrate-induced respiration and total amount of phospholipid fatty acids (PLFA), decreased slightly. An altered PLFA pattern indicated a change in the microbial community structure at the higher levels of acid applications. In general, branched fatty acids, typical of gram-positive bacteria, increased in the acid plots. PLFA analysis performed on the bacterial community growing on agar plates also showed that the relative amount of PLFA specific for gram-positive bacteria increased due to the acidification. The changed bacterial community was adapted to the more acidic environment in the acid-treated plots, even though bacterial growth rates, estimated by thymidine and leucine incorporation, decreased with pH. Fungal activity (measured as acetate incorporation into ergosterol) was not affected. This result indicates that bacteria were more affected than fungi by the acidification. The capacity of the bacterial community to utilize 95 different carbon sources was variable and only showed weak correlations to pH. Differences in the toxicities of H2SO4 and HNO3 for the microbial community were not found. PMID:9603831

  20. Acid-Base Interactions at the Molecular Level: Adhesion and Friction Studies with Interfacial Force Microscopy

    SciTech Connect

    Burns, A.R.; Carpick, R.W.; Houston, J.E.; Michalske, T.A.

    1998-12-09

    To examine the forces of acid-base adhesive interactions at the molecular level, we utilize the scanning probe Interracial Force Microscope (IFM). Unlike cantilever-based atomic force microscopes, the EM is a non-compliant, mechanically stable probe that provides a complete adhesive profile without jump-to-contact. In this way, we are able to quantitatively measure the work of adhesion and bond energies at well-defined, nanometer-scale single asperity contacts. In particular, we will discuss the displacement-controlled adhesive forces between self-assembled monolayer of functionalized alkanethiols strongly bound to a gold substrate and a similarly functionalized tip. We also discuss a method utilizing decoupled lateral and normal force sensors to simultaneously observe the onset of both friction and chemical bond formation. Measurements show that friction can be directly attributed to bond formation and rupture well before repulsive contact.

  1. Study of dynamic process of acetic acid induced-whitening in epithelial tissues at cellular level

    NASA Astrophysics Data System (ADS)

    Wu, Tao T.; Qu, Jianan Y.; Cheung, Tak Hong; Yim, So Fan; Wong, Yick Fu

    2005-06-01

    Acetic acid, inducing transient whitening (acetowhitening) when applied to epithelial tissues, is a commonly used contrast agent for detecting early cervical cancer. The goals of this research are to investigate the temporal characteristics of acetowhitening process in cervical epithelial tissue at cellular level and develop a clear understanding of the diagnostic information carried in the acetowhitening signal. A system measuring time-resolved reflectance was built to study the rising and decay processes of acetowhitening signal from the monolayered cell cultures of normal and cancerous cervical squamous cells. It is found that the dynamic processes of acetowhitening in normal and cancerous cells are significantly different. The results of this study provide insight valuable to further understand the acetowhitening process in epithelial cells and to encourage the development of an objective procedure to detect the early cervical cancers based on quantitative monitoring of the dynamic process of acetowhitening

  2. Low levels of haptoglobin and putative amino acid sequence in Taiwanese Lanyu miniature pigs.

    PubMed

    Yueh, Sunny C H; Wang, Yao Horng; Lin, Kuan Yu; Tseng, Chi Feng; Chu, Hsien Pin; Chen, Kuen Jaw; Wang, Shih Sheng; Lai, I Hsiang; Mao, Simon J T

    2008-04-01

    Porcine haptoglobin (Hp) is an acute phase protein. Its plasma level increases significantly during inflammation and infection. One of the main functions of Hp is to bind free hemoglobin (Hb) and inhibit its oxidative activity. In the present report, we studied the Hp phenotype of Taiwanese Lanyu miniature pigs (TLY minipigs; n=43) and found their Hp structure to be a homodimer (beta-alpha-alpha-beta) similar to human Hp 1-1. Interestingly, Western blot and high performance liquid chromatographic (HPLC) analysis showed that 25% of the TLY minipigs possessed low or no plasma Hp level (<0.05 mg/ml). The Hp cDNA of these TLY minipigs was then cloned, and the translated amino acid sequence was analyzed. No sequences were found to be deficient; they showed a 99.7% identity with domestic pigs (NP_999165). The mean overall Hp level of the TLY minipigs (0.21 +/- 0.25 mg/ml; n=43) determined by enzyme-linked immunosorbent assay (ELISA) was markedly lower than that of domestic pigs (0.78 +/- 0.45 mg/ml; p<0.001), while 25% of the TLY minipigs had an Hp level that was extremely low (<0.05 mg/ml). In addition, the initial recovery rate (first 40 min) in the circulation of infused fluorescein isothiocyanate (FITC)-Hb was significantly higher in the TLY minipigs with extremely low Hp levels than those with high levels. This data suggests that the low concentration of Hp-Hb complex is responsible for the higher recovery rate of Hb in the circulation. TLY minipigs have been used as an experimental model for cardiovascular diseases; whether they can be used as a model for inflammatory diseases, with Hp as a marker, remains a topic of interest. However, since the Hp level varies significantly among individual TLY minipigs, it is necessary to prescreen the Hp levels of the animals to minimize variation in the experimental baseline. The present study may provide a reference value for future use of the TLY minipig as an animal model for inflammation-associated diseases. PMID:18460833

  3. Low and high dietary folic acid levels perturb postnatal cerebellar morphology in growing rats.

    PubMed

    Partearroyo, Teresa; Pérez-Miguelsanz, Juliana; Peña-Melián, Ángel; Maestro-de-Las-Casas, Carmen; Úbeda, Natalia; Varela-Moreiras, Gregorio

    2016-06-01

    The brain is particularly sensitive to folate metabolic disturbances, because methyl groups are critical for brain functions. This study aimed to investigate the effects of different dietary levels of folic acid (FA) on postnatal cerebellar morphology, including the architecture and organisation of the various layers. A total of forty male OFA rats (a Sprague-Dawley strain), 5 weeks old, were classified into the following four dietary groups: FA deficient (0 mg/kg FA); FA supplemented (8 mg/kg FA); FA supra-supplemented (40 mg/kg FA); and control (2 mg/kg FA) (all n 10 per group). Rats were fed ad libitum for 30 d. The cerebellum was quickly removed and processed for histological and immunohistochemical analysis. Slides were immunostained for glial fibrillary acidic protein (to label Bergmann glia), calbindin (to label Purkinje cells) and NeuN (to label post-mitotic neurons). Microscopic analysis revealed two types of defect: partial disappearance of fissures and/or neuronal ectopia, primarily in supra-supplemented animals (incidence of 80 %, P≤0·01), but also in deficient and supplemented groups (incidence of 40 %, P≤0·05), compared with control animals. The primary fissure was predominantly affected, sometimes accompanied by defects in the secondary fissure. Our findings show that growing rats fed an FA-modified diet, including both deficient and supplemented diets, have an increased risk of disturbances in cerebellar corticogenesis. Defects caused by these diets may have functional consequences in later life. The present study is the first to demonstrate that cerebellar morphological defects can arise from deficient, as well as high, FA levels in the diet. PMID:27153204

  4. Domain-level rocking motion within a polymerase that translocates on single-stranded nucleic acid

    SciTech Connect

    Li, Huiyung; Li, Changzheng; Zhou, Sufeng; Poulos, Thomas L.; Gershon, Paul David

    2013-04-01

    An X-ray crystallographic structure is described for unliganded Vaccinia virus poly(A) polymerase monomer (VP55), showing the first domain-level structural isoforms among either VP55, it’s processivity factor VP39, or the VP55-VP39 heterodimer. The occurrence of domain-level motion specifically in monomeric VP55 is consistent with the finding that the monomeric protein undergoes saltatory translocation whereas the heterodimer does not. Vaccinia virus poly(A) polymerase (VP55) is the only known polymerase that can translocate independently with respect to single-stranded nucleic acid (ssNA). Previously, its structure has only been solved in the context of the VP39 processivity factor. Here, a crystal structure of unliganded monomeric VP55 has been solved to 2.86 Å resolution, showing the first backbone structural isoforms among either VP55 or its processivity factor (VP39). Backbone differences between the two molecules of VP55 in the asymmetric unit indicated that unliganded monomeric VP55 can undergo a ‘rocking’ motion of the N-terminal domain with respect to the other two domains, which may be ‘rigidified’ upon VP39 docking. This observation is consistent with previously demonstrated experimental molecular dynamics of the monomer during translocation with respect to nucleic acid and with different mechanisms of translocation in the presence and absence of processivity factor VP39. Side-chain conformational changes in the absence of ligand were observed at a key primer contact site and at the catalytic center of VP55. The current structure completes the trio of possible structural forms for VP55 and VP39, namely the VP39 monomer, the VP39–VP55 heterodimer and the VP55 monomer.

  5. Serum uric acid levels in normal pregnancy with observations on the renal excretion of urate in pregnancy

    PubMed Central

    Boyle, James A.; Campbell, Stuart; Duncan, Anne M.; Greig, William R.; Buchanan, W. Watson

    1966-01-01

    Serum uric acid estimations were performed in 106 healthy pregnant women during early, middle, and late pregnancy, using an automated colorimetric method. The mean serum uric acid level was significantly lower during early and middle pregnancy than that of 64 age-matched female controls. The serum uric acid level was not significantly different in late pregnancy from the control group. Studies of the daily urinary urate excretion in 31 pregnant women showed normal urinary urate excretion in early pregnancy and enhanced renal loss of urate in middle and late pregnancy. It appears that the renal clearance of urate in pregnancy is high, especially in the middle period when the serum level is low in spite of the increased production of uric acid by the foetus. PMID:5919366

  6. Poly-glutamic acid modified carbon nanotube-doped carbon paste electrode for sensitive detection of L-tryptophan.

    PubMed

    Liu, Xiao; Luo, Liqiang; Ding, Yaping; Ye, Daixin

    2011-08-01

    A novel poly-glutamic acid (PGA) film modified carbon paste electrode (CPE) incorporating carbon nanotubes (CNTs) was first prepared for the determination of l-tryptophan (l-Trp). Scanning electron microscopy and Fourier transform infrared spectroscopy were applied for characterization of the surface morphology of the modified electrodes and cyclic voltammetry was used to investigate the electrochemical properties of the proposed electrode towards the oxidation of l-Trp. Optimization of the experimental parameters was performed with regard to pH, ratio of CNTs, concentration of glutamic acid, electro-polymerization cycles, accumulation time and concentration of sodium dodecylbenzene sulfonate. The linearity between the oxidation peak current and the l-Trp concentration was obtained in the range of 5.0×10(-8) to 1.0×10(-4)M with a detection limit of 1.0×10(-8)M (S/N=3) and the sensitivity was calculated to be 1143.79μA∙mM(-1)∙cm(-2). In addition, the PGA modified CPE incorporating CNTs displayed high selectivity, good stability and reproducibility, making it suitable for the routine analysis of l-Trp in clinical use. PMID:21640670

  7. Omega-3 fatty acids protect renal functions by increasing docosahexaenoic acid-derived metabolite levels in SHR.Cg-Lepr(cp)/NDmcr rats, a metabolic syndrome model.

    PubMed

    Katakura, Masanori; Hashimoto, Michio; Inoue, Takayuki; Al Mamun, Abdullah; Tanabe, Yoko; Iwamoto, Ryo; Arita, Makoto; Tsuchikura, Satoru; Shido, Osamu

    2014-01-01

    The omega-3 polyunsaturated fatty acids (ω-3 PUFAs) docosahexaenoic acid (DHA) and/or eicosapentaenoic acid (EPA) protect against diabetic nephropathy by inhibiting inflammation. The aim of this study was to assess the effects of highly purified DHA and EPA or EPA only administration on renal function and renal eicosanoid and docosanoid levels in an animal model of metabolic syndrome, SHR.Cg-Lepr(cp)/NDmcr (SHRcp) rats. Male SHRcp rats were divided into 3 groups. Control (5% arabic gum), TAK-085 (300 mg/kg/day, containing 467 mg/g EPA and 365 mg/g DHA), or EPA (300 mg/kg/day) was orally administered for 20 weeks. The urinary albumin to creatinine ratio in the TAK-085-administered group was significantly lower than that in other groups. The glomerular sclerosis score in the TAK-085-administered group was significantly lower than that in the other groups. Although DHA levels were increased in total kidney fatty acids, the levels of nonesterified DHA were not significantly different among the 3 groups, whereas the levels of protectin D1, resolvin D1, and resolvin D2 were significantly increased in the TAK-085-administered group. The results show that the use of combination therapy with DHA and EPA in SHRcp rats improved or prevented renal failure associate with metabolic syndrome with decreasing triglyceride levels and increasing ω-3 PUFA lipid mediators. PMID:24642910

  8. O2 and H2O2 transformation steps for the oxygen reduction reaction catalyzed by graphitic nitrogen-doped carbon nanotubes in acidic electrolyte from first principles calculations.

    PubMed

    Li, Yuhang; Zhong, Guoyu; Yu, Hao; Wang, Hongjuan; Peng, Feng

    2015-09-14

    It is highly challenging but extremely desirable to develop carbon catalysts with high oxygen reduction reaction (ORR) activity and stability in acidic medium for commercial application. In this paper, based on density functional theory (DFT) calculations with long range interaction correction and solvation effects, the elementary transformations of all the probable intermediates in the ORR and the hydrogen peroxide reduction reaction (HPRR) over graphitic nitrogen-doped carbon nanotubes (NCNTs) in acidic medium were evaluated, and it was found that all the rate determining steps are related to the bonding hydroxyl group because of the strong interaction between the hydroxyl group and carbon. Thus, it is hard for the direct four-electron ORR and the two-electron HPRR to proceed. Together with hydrogen peroxide disproportionation (HPD), a mixed mechanism for the ORR in acidic electrolyte was proposed, where the two-electron and three-electron ORRs and HPD dominate the electrode reaction. The experimental result for the ORR catalyzed by NCNTs in acidic electrolyte also well illustrated the rationality of the theoretical calculations. This study not only gives new insights into the effect of graphitic nitrogen doping on the ORR catalyzed by carbon, but also provides a guide to design carbon catalysts with high ORR activity in acidic electrolyte. PMID:26234475

  9. Electrical characterization of deep levels created by bombarding nitrogen-doped 4H-SiC with alpha-particle irradiation

    NASA Astrophysics Data System (ADS)

    Omotoso, Ezekiel; Meyer, Walter E.; Auret, F. Danie; Paradzah, Alexander T.; Legodi, Matshisa J.

    2016-03-01

    Deep-level transient spectroscopy (DLTS) and Laplace-DLTS were used to investigate the effect of alpha-particle irradiation on the electrical properties of nitrogen-doped 4H-SiC. The samples were bombarded with alpha-particles at room temperature (300 K) using an americium-241 (241Am) radionuclide source. DLTS revealed the presence of four deep levels in the as-grown samples, E0.09, E0.11, E0.16 and E0.65. After irradiation with a fluence of 4.1 × 1010 alpha-particles-cm-2, DLTS measurements indicated the presence of two new deep levels, E0.39 and E0.62 with energy levels, EC - 0.39 eV and EC - 0.62 eV, with an apparent capture cross sections of 2 × 10-16 and 2 × 10-14 cm2, respectively. Furthermore, irradiation with fluence of 8.9 × 1010 alpha-particles-cm-2 resulted in the disappearance of shallow defects due to a lowering of the Fermi level. These defects re-appeared after annealing at 300 °C for 20 min. Defects, E0.39 and E0.42 with close emission rates were attributed to silicon or carbon vacancy and could only be separated by using high resolution Laplace-DLTS. The DLTS peaks at EC - (0.55-0.70) eV (known as Z1/Z2) were attributed to an isolated carbon vacancy (VC).

  10. Excessive versus physiologically relevant levels of retinoic acid in embryonic stem cell differentiation.

    PubMed

    Sheikh, Bilal N; Downer, Natalie L; Kueh, Andrew J; Thomas, Tim; Voss, Anne K

    2014-06-01

    Over the past two decades, embryonic stem cells (ESCs) have been established as a valuable system to study the complex molecular events that underlie the collinear activation of Hox genes during development. When ESCs are induced to differentiate in response to retinoic acid (RA), Hox genes are transcriptionally activated in their chromosomal order, with the most 3' Hox genes activated first, sequentially followed by more 5' Hox genes. In contrast to the low levels of RA detected during gastrulation (∼33 nM), a time when Hox genes are induced during embryonic development, high levels of RA are used to study Hox gene activation in ESCs in vitro (1-10 µM). This compelled us to compare RA-induced ESC differentiation in vitro with Hox gene activation in vivo. In this study, we show that treatment of ESCs for 2 days with RA best mimics activation of Hox genes during embryonic development. Furthermore, we show that defects in Hox gene expression known to occur in embryos lacking the histone acetyltransferase MOZ (also called MYST3 or KAT6A) were masked in Moz-deficient ESCs when excessive RA (0.5-5 µM) was used. The role of MOZ in Hox gene activation was only evident when ESCs were differentiated at low concentrations of RA, namely 20 nM, which is similar to RA levels in vivo. Our results demonstrate that using RA at physiologically relevant levels to study the activation of Hox genes, more accurately reflects the molecular events during the early phase of Hox gene activation in vivo. PMID:25099890

  11. Extra virgin olive oil modulates brain docosahexaenoic acid level and oxidative damage caused by 2,4-Dichlorophenoxyacetic acid in rats.

    PubMed

    Amel, Nakbi; Wafa, Tayeb; Samia, Dabbou; Yousra, Belaid; Issam, Chargui; Cheraif, Imed; Attia, Nebil; Mohamed, Hammami

    2016-03-01

    Oxidative stress is an important pathomechanism of neurological disorders such as Alzheimer disease and Parkinson disease, cardiovascular disorders and many others. This study sought to verify whether extra-virgin olive oil (EVOO), lipophilic fraction (OOLF) and hydrophilic fraction (OOHF) exerted a brain protective effect against the oxidative stress caused by 2,4-dichlorophenoxyacetic acid (2,4-D) pesticide at a dose of 5 mg/kg body weight. 2,4-D, EVOO and its fractions were administered to rats by gavages for four consecutive weeks. Oxidative stress was assessed by measuring brain lipid peroxide level, acetylcholinesterase (AChE), antioxidant enzyme activities and fatty acid composition. 2,4-D induced a decrease in both plasma and brain acetylcholinesterase activity and a rise in Brain TBARS (Thiobarbituric acid reactive substances) level and antioxidant enzyme activities compared with the control group. These changes were partly reversed by either EVOO or its fractions oral administration to 2,4-D treated rats. EVOO enhanced a neuroprotective effect evaluated by the restoration of brain fatty acid composition especially the level of docosahexaenoic acid (DHA). Our results indicate that EVOO exerts a neuroprotective activity against oxidative damage in brain induced by 2,4-D, which could be attributed to its antioxidative property. PMID:27570270

  12. Nitrogen dioxide induced changes in level of free fatty acids, triglyceride, esterified fatty acid, ganglioside and lipase activity in the guinea pig brain

    SciTech Connect

    Farahani, H.; Hasan, M. )

    1992-02-01

    The biochemical response to controlled inhalation of nitrogen dioxide (NO2) was studied in 18 male guinea pigs. Animals were exposed to 2.5, 5.0, and 10 ppm NO2 for 2h daily for 35 consecutive days, and the results compared with six control animals exposed to filtered air for 2h daily for same period. Five biochemical parameters, including triglyceride, free fatty acids, esterified fatty acid, ganglioside and lipase activity were measured immediately after the last day of exposure. At 2.5 ppm NO2 inhalation no significant changes occurred in any region of the central nervous system (CNS). While as the dose concentration was increased to 5 and 10 ppm nitrogen dioxide, significant dose-related alteration were observed in the levels of triglyceride, free fatty acid, esterified fatty acid, ganglioside and lipase activity in the different regions of the guinea pig CNS.

  13. The Effect of Temperature on the Level and Biosynthesis of Unsaturated Fatty Acids in Diacylglycerols of Brassica napus Leaves 1

    PubMed Central

    Williams, John P.; Khan, Mobashsher U.; Mitchell, Kirk; Johnson, Geoff

    1988-01-01

    Experiments on the effects of temperature on the levels of unsaturated fatty acids and their rates of desaturation in Brassica napus leaf lipids have shown that significant differences occur in the composition of all diacylglycerols in the leaf between plants grown at high and low temperatures. In the major thylakoid diacylglycerols, monogalactosyl-diacylglycerol and digalactosyldiacylglycerol, not only is there an increase in the level of unsaturation at low temperatures, but there is a change in the balance between molecular species of chloroplastic origin (16/18C) and cytosolic origin (18/18C). Radioactivity tracer data indicate that at low temperatur