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Sample records for synthetic ceric oxide

  1. Ruthenium carbonyl catalyst supported on ceric oxide for preparation of olefins from synthesis gas

    DOEpatents

    Pierantozzi, Ronald

    1985-01-01

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  2. Preparation of olefins from synthesis gas using ruthenium supported on ceric oxide

    DOEpatents

    Pierantozzi, Ronald

    1985-01-01

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  3. Ruthenium carbonyl catalyst supported on ceric oxide for preparation of olefins from synthesis gas

    DOEpatents

    Pierantozzi, R.

    1985-04-02

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  4. Preparation of olefins from synthesis gas using ruthenium supported on ceric oxide

    DOEpatents

    Pierantozzi, R.

    1985-04-09

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  5. Synthetic chemistry with nitrous oxide.

    PubMed

    Severin, Kay

    2015-10-01

    This review article summarizes efforts to use nitrous oxide (N2O, 'laughing gas') as a reagent in synthetic chemistry. The focus will be on reactions which are carried out in homogeneous solution under (relatively) mild conditions. First, the utilization of N2O as an oxidant is discussed. Due to the low intrinsic reactivity of N2O, selective oxidation reactions of highly reactive compounds are possible. Furthermore, it is shown that transition metal complexes can be used to catalyze oxidation reactions, in some cases with high turnover numbers. In the final part of this overview, the utilization of N2O as a building block for more complex molecules is discussed. It is shown that N2O can be used as an N-atom donor for the synthesis of interesting organic molecules such as triazenes and azo dyes. PMID:26104268

  6. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Synthetic iron oxide. 73.1200 Section 73.1200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  7. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Synthetic iron oxide. 73.1200 Section 73.1200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  8. 21 CFR 73.200 - Synthetic iron oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Synthetic iron oxide. 73.200 Section 73.200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  9. 21 CFR 73.200 - Synthetic iron oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Synthetic iron oxide. 73.200 Section 73.200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  10. 21 CFR 73.200 - Synthetic iron oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Synthetic iron oxide. 73.200 Section 73.200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  11. 21 CFR 73.200 - Synthetic iron oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Synthetic iron oxide. 73.200 Section 73.200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  12. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Synthetic iron oxide. 73.1200 Section 73.1200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  13. 21 CFR 73.200 - Synthetic iron oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Synthetic iron oxide. 73.200 Section 73.200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  14. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Synthetic iron oxide. 73.1200 Section 73.1200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  15. 21 CFR 73.1200 - Synthetic iron oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Synthetic iron oxide. 73.1200 Section 73.1200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically...

  16. Pentavalent Uranium Chemistry - Synthetic Pursuit Of A Rare Oxidation State

    SciTech Connect

    Graves, Christopher R; Kiplinger, Jaqueline L

    2009-01-01

    This feature article presents a comprehensive overview of pentavalent uranium systems in non-aqueous solution with a focus on the various synthetic avenues employed to access this unusual and very important oxidation state. Selected characterization data and theoretical aspects are also included. The purpose is to provide a perspective on this rapidly evolving field and identify new possibilities for future developments in pentavalent uranium chemistry.

  17. Synthetic Zeolites and Other Microporous Oxide Molecular Sieves

    NASA Astrophysics Data System (ADS)

    Sherman, John D.

    1999-03-01

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow "tailoring" of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol.

  18. Synthetic zeolites and other microporous oxide molecular sieves.

    PubMed

    Sherman, J D

    1999-03-30

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow "tailoring" of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol. PMID:10097059

  19. Synthetic zeolites and other microporous oxide molecular sieves

    PubMed Central

    Sherman, John D.

    1999-01-01

    Use of synthetic zeolites and other microporous oxides since 1950 has improved insulated windows, automobile air-conditioning, refrigerators, air brakes on trucks, laundry detergents, etc. Their large internal pore volumes, molecular-size pores, regularity of crystal structures, and the diverse framework chemical compositions allow “tailoring” of structure and properties. Thus, highly active and selective catalysts as well as adsorbents and ion exchangers with high capacities and selectivities were developed. In the petroleum refining and petrochemical industries, zeolites have made possible cheaper and lead-free gasoline, higher performance and lower-cost synthetic fibers and plastics, and many improvements in process efficiency and quality and in performance. Zeolites also help protect the environment by improving energy efficiency, reducing automobile exhaust and other emissions, cleaning up hazardous wastes (including the Three Mile Island nuclear power plant and other radioactive wastes), and, as specially tailored desiccants, facilitating the substitution of new refrigerants for the ozone-depleting chlorofluorocarbons banned by the Montreal Protocol. PMID:10097059

  20. A synthetic leaf: the biomimetic potential of graphene oxide

    NASA Astrophysics Data System (ADS)

    Lamb, Marilla; Koch, George W.; Morgan, Eric R.; Shafer, Michael W.

    2015-03-01

    Emerging materials such as graphene oxide (GO) have micro and nano features that are functionally similar to those in plant cell walls involved in water transport. Therefore, it may now be possible to design and build biomimetic trees to lift water via mechanisms similar to those employed by trees, allowing for potential applications such as passive water pumping, filtering, and evaporative cooling. The tallest trees can raise large volumes of water to over 100 meters using only the vapor pressure gradient between their leaves and the atmosphere. This phenomenon occurs in all terrestrial plants when capillary forces generated in the microscopic pores in the cell walls of leaves are collectively applied to large diameter xylem conduits. The design of a synthetic tree that mimics these mechanisms will allow water to be moved to heights greater than is currently possible by any engineered system that does not require the use of a positive pressure pump. We are testing the suitability of membranous GO as the leaf of a synthetic tree and present an analysis in support of this design. In addition, we include results from a preliminary design using ceramics.

  1. Ceric and ferrous dosimeters show precision for 50-5000 rad range

    NASA Technical Reports Server (NTRS)

    Frigerio, N. A.; Henry, V. D.

    1968-01-01

    Ammonium thiocyanate, added to the usual ferrous sulfate dosimeter solution, yielded a very stable, precise and temperature-independent system eight times as sensitive as the classical Fricke system in the 50 to 5000 rad range. The ceric dosimeters, promising for use in mixed radiation fields, respond nearly independently of LET.

  2. A study of synthetic and natural uranium oxides by X-ray photoelectron spectroscopy

    NASA Astrophysics Data System (ADS)

    Teterin, Yu. A.; Kulakov, V. M.; Baev, A. S.; Nevzorov, N. B.; Melnikov, I. V.; Streltsov, V. A.; Mashirov, L. G.; Suglobov, D. N.; Zelenkov, A. G.

    1981-09-01

    Synthetic and natural uranium oxides UO x (2≦×≦3) have been studied with X-ray photoelectron spectroscopy (XPS) to determine the phase composition and content of uranium ions in uraninites with a varying degree of oxidation. A strong hybridization of U6 p and O2 s orbitals has been found which permits a quantitative assessment of the U-O bond lengths. The values of such bonds in some substances have been found to be smaller than those in synthetic U(VI) oxide. The oxides U2O5 and U3O8 contain two types of uranium ions with a varying degree of oxidation.

  3. Electrochemical oxidation as a final treatment of synthetic tannery wastewater.

    PubMed

    Panizza, Marco; Cerisola, Giacomo

    2004-10-15

    Vegetable tannery wastewaters contain high concentrations of organics and other chemicals that inhibit the activity of microorganisms during biological oxidations, so biorefractory organics that are not removed by biological treatment must be eliminated by a tertiary or advanced wastewater treatment. In this paper, the applicability of electrochemical oxidation as a tertiary treatment of a vegetable tannery wastewater was investigated by performing galvanostatic electrolysis using lead dioxide (Ti/PbO2) and mixed titanium and ruthenium oxide (Ti/TiRuO2) as anodes under different experimental conditions. The experimental results showed that both the electrodes performed complete mineralization of the wastewater. In particular, the oxidation took place on the PbO2 anode by direct electron transfer and indirect oxidation mediated by active chlorine, while it occurred on the Ti/TiRuO2 anode only by indirect oxidation. Furthermore, the Ti/PbO2 gave a somewhat higher oxidation rate than that observed for the Ti/TiRuO2 anode. Although the Ti/TiRuO2 required almost the same energy consumption for complete COD removal, it was more stable and did not release toxic ions, so it was the best candidate for industrial applications. With the Ti/TiRuO2 anode, the rate of tannery wastewater oxidation increased with the current density, pH, and temperature of the solution. These results strongly indicate that electrochemical methods can be applied effectively as a final treatment of vegetable tannery wastewater allowing the complete removal of COD, tannin, and ammonium and decolorization. PMID:15543753

  4. Development of Novel Biopolymer/Synthetic-Polymer/Iron Oxide Nanocomposites

    NASA Astrophysics Data System (ADS)

    Mena Montoya, Marleth; Carranza, Sugeheidy; Hinojosa, Moisés; González, Virgilio

    2009-03-01

    In this work we report the successful development of a family of magnetic nanocomposites based on chitosan or/and polyamide 6 matrix with dispersed iron oxide nanoparticles synthesized by chemical co-precipitation. The iron oxide contents varied from 5 up to 23 wt%, the nanocomposites were studied by FTIR, UV-vis, TGA, XRD, TEM and magnetometry. The FTIR analysis demonstrates an interaction between the amide group of the polyamide 6 and the ceramic material. In formic acid, the nanocomposites absorb in the UV-Vis range, and the magnitude of the band gap (optical), calculated using the band of higher wavelength, is between 2.16 and 2.19 eV. In nanocomposites with chitosan/polyamide 6 matrix the developed morphologies are spherulites of polyamide 6 surrounded by chitosan, with the iron oxide particles presumably in the form of ferrihidryte. The measured magnetic properties revealed a superparamagnetic character on the studied specimens.

  5. Characterization of Synthetic and Natural Manganese Oxides as Martian Analogues

    NASA Technical Reports Server (NTRS)

    Fox, V. K.; Arvidson, R. E.; Jolliff, B. L.; Carpenter, P. K.; Catalano, J. G.; Hinkle, M. A. G.; Morris, R. V.

    2015-01-01

    Recent discoveries of highly concentrated manganese oxides in Gale Crater and on the rim of Endeavour Crater by the Mars Science Laboratory Curiosity and Mars Exploration Rover Opportunity, respectively, imply more highly oxidizing aqueous conditions than previously recognized. Manganese oxides are a significant environmental indicator about ancient aqueous conditions, provided the phases can be characterized reliably. Manganese oxides are typically fine-grained and poorly crystalline, making the mineral structures difficult to determine, and they generally have very low visible reflectance with few distinctive spectral features in the visible to near infrared, making them a challenge for interpretation from remote sensing data. Therefore, these recent discoveries motivate better characterization using methods available on Mars, particularly visible to near infrared (VNIR) spectroscopy, X-ray diffractometry (XRD), and compositional measurements. Both rovers have complementary instruments in this regard. Opportunity is equipped with its multispectral visible imager, Pancam, and an Alpha Particle X-ray Spectrometer (APXS), and Curiosity has the multispectral Mastcam, ChemCam (laser-induced breakdown spectroscopy and passive spectroscopy), and APXS for in situ characterization, and ChemMin (XRD) for collected samples.

  6. Oxidation of synthetic phenolic antioxidants during water chlorination.

    PubMed

    Rodil, Rosario; Quintana, José Benito; Cela, Rafael

    2012-01-15

    The degradation of seven phenolic antioxidants and metabolites during chlorination was investigated. Under strong chlorination conditions (10 mg L(-1) chlorine, 24h), five of the target compounds were significantly degraded, while only BHT-Q (2,6-di-tert-butylcyclohexa-2,5-diene-1,4-dione) and BHT-CHO (3,5-di-tert-butyl-4-hydroxybenzaldehyde) were stable. The effect of the presence of bromide to the sample was only significant for BHA (butylated hydroxyanisole) resulting in increased disappearance rate as it is increased. Moreover, the disappearance kinetics were investigated at different concentrations of chlorine and pH of sample using a factorial experimental design. It was observed that the pH of the sample was a significant factor for BHT (butylated hydroxytoluene) and BHA, and chlorine concentration was significant for BHT, resulting in increased disappearance kinetics as they are increased. The degradation of these compounds has revealed two main processes: hydroxylation and oxidation of the aromatic system. The hydroxylated derivatives in some cases (e.g. from BHT-OH (2,6-di-tert-butyl-4-(hydroxymethyl)phenol) and BHT-COOH (3,5-di-tert-butyl-4-hydroxybenzoic acid)) are formed via the chlorinated and/or brominated intermediate. Moreover, the oxidation of the aromatic system leads to the quinone derivatives. The investigation of these by-products in real samples by solid-phase extraction-gas chromatography-mass spectrometry (SPE-GC-MS) showed that derivatives of BHT, BHT-OH and/or BHT-COOH occurred in wastewater and drinking water samples analysed. PMID:22093692

  7. From formation mechanisms to synthetic methods toward shape-controlled oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Nguyen, Thanh-Dinh

    2013-09-01

    Metal oxide nanomaterials have been intensively pursued for modern science and nanotechnology. Control over the size and shape of the oxide nanoparticles enables tunability of their unique properties sought for many useful applications. This review presents a comprehensive overview of the recent advances in the shape-controlled synthesis of colloidal oxide nanoparticles. We introduce the size- and shape-dependent properties of the oxide nanoparticles along with their potential applications and subsequent descriptions of the kinetic regime concepts of the formation of the monodisperse nanocolloids. Variations of the experimental conditions including capping molecules, precursor monomer concentration, and reaction temperature/aging have been explored to control the shape of the oxide nanoparticles in wet-chemistry syntheses. The different capping molecule-assisted synthetic methods of the hydro-solvothermal route, the two-phase route, heating-up thermolysis, and reverse micelle are presented as a collection of clear examples of the regular oxide nanoparticles. We also discuss the advantages and obstacles of the synthetic methods that have proven to be controllable and reproducible. The author concludes this review with valuable portraits on working hypotheses for the shape-controlled oxide nanoparticle synthesis.

  8. Comparison of photoelectrochemical water oxidation activity of a synthetic photocatalyst system with photosystem II.

    PubMed

    Lai, Yi-Hsuan; Kato, Masaru; Mersch, Dirk; Reisner, Erwin

    2014-01-01

    This discussion describes a direct comparison of photoelectrochemical (PEC) water oxidation activity between a photosystem II (PSII)-functionalised photoanode and a synthetic nanocomposite photoanode. The semi-biological photoanode is composed of PSII from the thermophilic cyanobacterium Thermosynechococcus elongatus on a mesoporous indium tin oxide electrode (mesoITO|PSII). PSII embeds all of the required functionalities for light absorption, charge separation and water oxidation and ITO serves solely as the electron collector. The synthetic photoanode consists of a TiO(2) and NiO(x) coated nanosheet-structured WO(3) electrode (nanoWO(3)|TiO(2)|NiO(x)). The composite structure of the synthetic electrode allows mimicry of the functional key features in PSII: visible light is absorbed by WO(3), TiO(2) serves as a protection and charge separation layer and NiO(x) serves as the water oxidation electrocatalyst. MesoITO|PSII uses low energy red light, whereas nanoWO(3)|TiO(2)|NiO(x) requires high energy photons of blue-end visible and UV regions to oxidise water. The electrodes have a comparable onset potential at approximately 0.6 V vs. reversible hydrogen electrode (RHE). MesoITO|PSII reaches its saturation photocurrent at 0.84 V vs. RHE, whereas nanoWO(3)|TiO(2)NiO(x) requires more than 1.34 V vs. RHE. This suggests that mesoITO|PSII suffers from fewer limitations from charge recombination and slow water oxidation catalysis than the synthetic electrode. MesoITO|PSII displays a higher 'per active' site activity, but is less photostable and displays a much lower photocurrent per geometrical surface area and incident photon to current conversion efficiency (IPCE) than nanoWO(3)|TiO(2)|NiO(x_. PMID:25434986

  9. Dissolution of Technetium(IV) Oxide by Natural and Synthetic Organic Ligands Under both Reducing and Oxidizing Conditions

    SciTech Connect

    Gu, Baohua; Dong, W.; Liang, Liyuan; Wall, Nathalie

    2011-01-01

    Technetium-99 (Tc) in nuclear waste is a significant environmental concern due to its long half-life and high mobility in the subsurface. Reductive precipitation of Tc(IV) oxides [TcO2(s)] is an effective means of immobilizing Tc, thereby impeding its migration in groundwater. However, TcO2(s) is subject to dissolution by oxidants and/or complexing agents. In this study we ascertain the effects of a synthetic organic ligand, ethylenediaminetetraacetate (EDTA), and two natural humic isolates on the dissolution and solubility of Tc(IV) oxides. Pure synthetic TcO2(s) (0.23 mM) was used in batch experiments to determine dissolution kinetics at pH ~6 under both reducing and oxidizing conditions. All organic ligands were found to enhance the dissolution of Tc(IV) oxides, increasing their solubility from ~10-8 M (without ligands) to 4 10-7 M under strictly anoxic conditions. Reduced Tc(IV) was also found to re-oxidize rapidly under oxic conditions, with an observed oxidative dissolution rate approximately an order of magnitude higher than that of ligand-promoted dissolution under reducing conditions. Significantly, oxidative dissolution was inhibited by EDTA but enhanced by humic acid compared with experiments without any complexing agents. The redox functional properties of humics, capable of facilitating intra-molecular electron transfer, may account for this increased oxidation rate under oxic conditions. Our results highlight the importance of complex interactions for the stability and mobility of Tc, and thus for the long-term fate of Tc in contaminated environments.

  10. Phenolic mediators enhance the manganese peroxidase catalyzed oxidation of recalcitrant lignin model compounds and synthetic lignin.

    PubMed

    Nousiainen, Paula; Kontro, Jussi; Manner, Helmiina; Hatakka, Annele; Sipilä, Jussi

    2014-11-01

    Fungal oxidative enzymes, such as peroxidases and laccases, are the key catalysts in lignin biodegradation in vivo, and consequently provide an important source for industrial ligninolytic biocatalysts. Recently, it has been shown that some syringyl-type phenolics have potential as industrial co-oxidants or mediators, in laccase-catalyzed modification of lignocellulosic material. We have now studied the effect of such mediators with ligninolytic peroxidases on oxidation of the most recalcitrant lignin model compounds. We found that they are able to enhance the manganese peroxidase (MnP) catalyzed oxidation reactions of small non-phenolic compounds, veratryl alcohol and veratrylglycerol β-guaiacyl ether (adlerol), which are not usually oxidized by manganese peroxidases alone. In these experiments we compared two peroxidases from white-rot fungi, MnP from Phlebia sp. Nf b19 and versatile peroxidase (VP) from Bjerkandera adusta under two oxidation conditions: (i) the Mn(III) initiated mediated oxidation by syringyl compounds and (ii) the system involving MnP-dependent lipid peroxidation, both with production of (hydrogen) peroxides in situ to maintain the peroxidase catalytic cycle. It was found that both peroxidases produced α-carbonyl oxidation product of veratryl alcohol in clearly higher yields in reactions mediated by phenoxy radicals than in lipid-peroxyl radical system. The oxidation of adlerol, on the other hand, was more efficient in lipid-peroxidation-system. VP was more efficient than MnP in the oxidation of veratryl alcohol and showed its lignin peroxidase type activity in the reaction conditions indicated by some cleavage of Cα-Cβ-bond of adlerol. Finally, the mediator assisted oxidation conditions were applied in the oxidation of synthetic lignin (DHP) and the structural analysis of the oxidized polymers showed clear modifications in the polymer outcome, e.g. the oxidation resulted in reduced amount of aliphatic hydroxyls indicated by (31)P NMR. PMID

  11. Effect of temperature on the low-linear energy transfer radiolysis of the ceric-cerous sulfate dosimeter: a Monte Carlo simulation study.

    PubMed

    Kohan, Leila Mirsaleh; Meesungnoen, Jintana; Sanguanmith, Sunuchakan; Meesat, Ridthee; Jay-Gerin, Jean-Paul

    2014-05-01

    The stochastic modeling of the (60)Co γ/fast-electron radiolysis of the ceric-cerous chemical dosimeter has been performed as a function of temperature from 25-350°C. The system used is a dilute solution of ceric sulfate and cerous sulfate in aqueous 0.4 M sulfuric acid. In this system, H(•) (or HO2(•) in the presence of dissolved oxygen) and H2O2 produced by the radiolytic decomposition of water both reduce Ce(4+) ions to Ce(3+) ions, while (•)OH radicals oxidize the Ce(3+) present in the solution back to Ce(4+). The net Ce(3+) yield is given by G(Ce(3+)) = g(H(•)) + 2 g(H2O2) - g((•)OH), where the primary (or "escape") yields of H(•), H2O2 and (•)OH are represented by lower case g's. At room temperature, G(Ce(3+)) has been established to be 2.44 ± 0.8 molecules/100 eV. In this work, we investigated the effect of temperature on the yield of Ce(3+) and on the underlying chemical reaction kinetics using Monte Carlo track chemistry simulations. The simulations showed that G(Ce(3+)) is time dependent, a result of the differences in the lifetimes of the reactions that make up the radiolysis mechanism. Calculated G(Ce(3+)) values were found to decrease almost linearly with increasing temperature up to about 250°C, and are in excellent agreement with available experimental data. In particular, our calculations confirmed previous estimated values by Katsumura et al. (Radiat Phys Chem 1988; 32:259-63) showing that G(Ce(3+)) at ∼250°C is about one third of its value at room temperature. Above ∼250°C, our model predicted that G(Ce(3+)) would drop markedly with temperature until, instead of Ce(4+) reduction, Ce(3+) oxidation is observed. This drop is shown to occur as a result of the reaction of hydrogen atoms with water in the homogeneous chemical stage. PMID:24754561

  12. Sorption of Ferric Iron from Ferrioxamine B to Synthetic and Biogenic Layer Type Manganese Oxides

    NASA Astrophysics Data System (ADS)

    Duckworth, O.; John, B.; Sposito, G.

    2006-12-01

    Siderophores are biogenic chelating agents produced in terrestrial and marine environments to increase the bioavailablity of ferric iron. Recent work has suggested that both aqueous and solid-phase Mn(III) may affect siderophore-mediated iron transport, but no information appears to be available about the effect of solid-phase Mn(IV). To probe the effects of predominantly Mn(IV) oxides, we studied the sorption reaction of ferrioxamine B [Fe(III)HDFOB+, an Fe(III) chelate of the trihydroxamate siderophore desferrioxamine B (DFOB)] with two synthetic birnessites [layer type Mn(III, IV) oxides] and a biogenic birnessite produced by Pseudomonas putida MnB1. We found that all of these predominantly Mn(IV) oxides greatly reduced the aqueous concentration of Fe(III)HDFOB+ over at pH 8. After 72 hours equilibration time, the sorption behavior for the synthetic birnessites could be accurately described by a Langmuir isotherm; for the biogenic oxide, a Freundlich isotherm was best utilized to model the sorption data. To study the molecular nature of the interaction between the Fe(III)HDFOB+ complex and the oxide surface, Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy was employed. Analysis of the EXAFS spectra indicated that Fe(III) associated with the Mn(IV) oxides is not complexed by DFOB as in solution, but instead Fe(III) is specifically adsorbed to into the mineral structure at multiple sites with no evidence of DFOB complexation, thus indicating that the Mn(IV) oxides displaced Fe(III) from the siderophore complex. These results indicate that manganese oxides, including biominerals, may strongly sequester iron from soluble ferric complexes and thus may play a significant role in the biogeochemical cycling of iron in marine and terrestrial environments.

  13. Sorption of Ferrioxime B to Synthetic and Biogenic layer type Mn Oxides

    NASA Astrophysics Data System (ADS)

    Duckworth, O. W.; Bargar, J. R.; Sposito, G.

    2005-12-01

    Siderophores are biogenic chelating agents produced in terrestrial and marine environments to increase the bioavailablity of ferric iron. Recent work has suggested that both aqueous and solid-phase Mn(III) may affect siderophore-mediated iron transport, but no information appears to be available about the effect of solid-phase Mn(IV). To probe the effect of solid-phase Mn(IV), we studied the sorption reaction of ferrioxamine B [principally the species, Fe(III)HDFOB+, an Fe(III) chelate of the trihydroxamate siderophore, desferrioxamine B (DFOB)] with two synthetic birnessites [layer type Mn(IV) oxides] and a biogenic birnessite produced by Pseudomonas putida MnB1. We found that all of these predominantly Mn(IV) oxides greatly reduced the aqueous concentration of Fe(III)HDFOB+ over the pH range between 5 and 9. After 72 h equilibration time at pH 8, the sorption behavior for the synthetic birnessites could be accurately described by a Langmuir isotherm; for the biogenic oxide, a Freundlich isotherm was best utilized to model the sorption data. To study the molecular nature of the interaction between the Fe(III)HDFOB+ complex and the oxide surface, Fe K-edge extended X-Ray absorption fine structure (EXAFS) spectroscopy was employed. Analysis of the X-ray absorption spectra indicated that Fe(III) associated with the Mn(IV) oxides is not complexed with DFOB, but instead is incorporated into the mineral structure, thus implying that the Mn(IV) oxides displaced Fe(III) from the siderophore complex. These results indicate that manganese oxides, including biominerals, may strongly sequester iron from soluble ferric complexes and thus may play a significant role in the biogeochemical cycling of iron.

  14. Final report on international comparison CCQM-K68: Nitrous oxide in synthetic air

    NASA Astrophysics Data System (ADS)

    Lee, Jinbok; Lee, Jeongsoon; Moon, Dongmin; Seog Kim, Jin; Wessel, Rob; Aoki, Nobuyuki; Kato, Kenji; Guenther, Frank; Rhoderick, George; Konopelko, L. A.; Han, Qiao; Hall, Brad

    2011-01-01

    Nitrous oxide (N2O) is one of six greenhouse gases that are regulated by the Kyoto Protocol and has a Global Warming Potential (GWP) that is 296 times that of carbon dioxide. Global levels of nitrous oxide have increased at a rate of 0.25%/yr (0.8 ppb/yr) during the last ten years. In order to monitor levels of nitrous oxide in the atmosphere, it is necessary to use measurement standards with demonstrated equivalence at the highest level of accuracy. This report describes the results of a key comparison of standard gas mixtures of nitrous oxide in synthetic air at an amount fraction of 320 nmol/mol. This key comparison is part of the programme of the Gas Analysis Working Group (GAWG) of the CCQM to demonstrate the equivalence of the standards and measurement capabilities of the NMIs for greenhouse gases. It will support the development of measurement capability at the NMIs for nitrous oxide with uncertainties within the target set by the Global Atmospheric Watch (GAW) programme of the WMO for its global monitoring networks. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  15. Incorporation and measurement of synthetic nanosized iron oxides into soil profile for innovative agricultural applications

    NASA Astrophysics Data System (ADS)

    Guzmán, G.; Cañasveras, J. C.; Barrón, V.; Gómez, J. A.

    2012-04-01

    Iron oxides are natural constituents of soils providing them different characteristics. That differentiation has been used as in fingerprinting studies to determine sources of sediment, especially at large scales. However, there is a lack of studies that use this approach at smaller scales using iron oxides differences because these differences, among zones, are difficult to establish. The incorporation to soil profile of synthetic nanosized iron oxides could increase and improve the detection of differences in iron oxide properties among zones at plot or hillslope scales, solving problems that arise when that objective have been pursued with magnetic tracers of millimeter scale (Ventura et al. 2002). Magnetite (Fe3O4), hematite (α-Fe2O3) and goethite (FeOOH) can be commercially available as Bayferrox® 318M, 110 and 920 respectively, and traditionally used as pigments. Because of their properties, these iron oxides could fulfill all the requirements, defined by Zhang et al. 2001, for being sediment tracers. This communication describes the whole process of incorporation into the soil profile and the determination of the concentration of these iron oxides into the soil and in the transported sediment in water erosion experiments, and their use to estimate soil losses, identifying erosion and deposition areas, and quantifying the contribution to exported sediment of different zones. Their characteristics allowed a relatively easy detection by measuring the magnetic susceptibility, in the case of magnetite, and spectral properties by diffuse reflectance spectroscopy for hematite and goethite. Laboratory and field magnetic measurement techniques were set up considering bulk density variations at the soil samplings. Hematite and goethite measurements were also calibrated for the study-site soil and for different magnetite, hematite and goethite concentrations. A comparison of the measured iron oxide concentrations and a multivariate mixing model (Rhoton et al. 2008

  16. Oxidative Dissolution of UO2 in a Simulated Groundwater Containing Synthetic Nanocrystalline Mackinawite

    SciTech Connect

    Bi, Yuqiang; Hyun, Sung Pil; Kukkadapu, Ravi K.; Hayes, Kim F.

    2013-02-01

    The long-term success of in situ reductive immobilization of uranium (U) depends on the stability of U(IV) precipitates (e.g., uraninite) under oxic conditions. Field and laboratory studies have implicated iron sulfide minerals as redox buffers or oxidant scavengers that may slow oxidation of reduced U(VI) solid phases by oxygen and Fe(III). Yet, the inhibition mechanism(s) and reaction rates of uraninite (UO2) oxidative dissolution by oxic species such as oxygen in FeS-bearing systems remain largely unresolved. To address this knowledge gap, abiotic batch experiments were conducted with synthetic UO2 in the presence and absence of synthetic mackinawite (FeS) under simulated groundwater conditions of pH = 7, PO2 = 0.02 atm, and PCO2 = 0.05 atm (equivalent to total dissolved carbonate of 0.01 M). The kinetic profiles of dissolved uranium indicate that FeS inhibited UO2 dissolution for 51 hr by effectively scavenging oxygen and keeping dissolved oxygen (DO) low. During this time period, oxidation of structural Fe(II) and S(-II) of FeS were found to control the DO levels, leading to the formation of iron oxyhydroxides and elemental sulfur, respectively, as verified by X-ray diffraction (XRD), Mössbauer and X-ray absorption spectroscopy (XAS). After FeS was depleted due to oxidation, DO levels increased and UO2 oxidative dissolution occurred at an initial rate of rm = 1.2 ± 0.4 ×10-8 mol•g-1•s-1, higher than rm = 5.4 ± 0.3 ×10-9 mol•g-1•s-1 in the control experiment where FeS was absent. Soluble U(VI) products were adsorbed by iron oxyhydroxides (i.e. nanogoethite and ferrihydrite) formed from FeS oxidation, which facilitated the detachment of U(VI) surface complexes and more rapid dissolution of UO2. XAS analysis confirmed the adsorption of U(VI) species, and also showed that U(VI) was not significantly incorporated into iron oxyhydroxide structure. This work reveals that both the oxygen scavenging by FeS and the adsorption of U(VI) to FeS oxidation

  17. Synthetic effect between iron oxide and sulfate mineral on the anaerobic transformation of organic substance.

    PubMed

    Chen, Tian-Hu; Wang, Jin; Zhou, Yue-Fei; Yue, Zheng-Bo; Xie, Qiao-Qin; Pan, Min

    2014-01-01

    Synthetic effect between sulfate minerals (gypsum) and iron oxide (hematite) on the anaerobic transformation of organic substance was investigated in the current study. The results showed that gypsum was completely decomposed while hematite was partially reduced. The mineral phase analysis results showed that FeS and CaCO3 was the major mineralization product. Methane generation process was inhibited and inorganic carbon contents in the precipitates were enhanced compared to the control without hematite and gypsum. The inorganic carbon content increased with the increasing of hematite dosages. Co-addition of sulfate minerals and iron oxide would have a potential application prospect in the carbon sequestration area and reduction of the greenhouse gas release. The results would also reveal the role of inorganic mineral in the global carbon cycle. PMID:24189378

  18. Synthetic silver oxide and mercury-free zinc electrodes for silver-zinc reserve batteries

    NASA Astrophysics Data System (ADS)

    Smith, David F.; Gucinski, James A.

    Reserve activated silver oxide-zinc cells were constructed with synthetic silver oxide (Ag 2O) electrodes with Pb-treated zinc electrodes produced by a non-electrolytic process. The cells were tested before and after thermally accelerated aging. At discharge rates up to 80 mA cm -2, the discharge was limited by the Ag 2O electrode, with a coulombic efficiency between 89-99%. At higher rates, the cells are apparently zinc-limited. Test cells were artificially aged at 90°C for 19 h and discharged at 21°C at 80 mA cm -2. No capacity loss was measured, but a delayed activation rise time was noted (192 ms fresh vs. 567 ms aged). The delay is thought to be caused by zinc passivation due to the outgassing of cell materials.

  19. Sorption of ferric iron from ferrioxamine B to synthetic and biogenic layer type manganese oxides

    NASA Astrophysics Data System (ADS)

    Duckworth, Owen W.; Bargar, John R.; Sposito, Garrison

    2008-07-01

    Siderophores are biogenic chelating agents produced in terrestrial and marine environments that increase the bioavailability of ferric iron. Recent work has suggested that both aqueous and solid-phase Mn(III) may affect siderophore-mediated iron transport, but scant information appears to be available about the potential roles of layer type manganese oxides, which are relatively abundant in soils and the oligotrophic marine water column. To probe the effects of layer type manganese oxides on the stability of aqueous Fe-siderophore complexes, we studied the sorption of ferrioxamine B [Fe(III)HDFOB +, an Fe(III) chelate of the trihydroxamate siderophore desferrioxamine B (DFOB)] to two synthetic birnessites [layer type Mn(III,IV) oxides] and a biogenic birnessite produced by Pseudomonas putida GB-1. We found that all of these predominantly Mn(IV) oxides greatly reduced the aqueous concentration of Fe(III)HDFOB + at pH 8. Analysis of Fe K-edge EXAFS spectra indicated that a dominant fraction of Fe(III) associated with the Mn(IV) oxides is not complexed by DFOB as in solution, but instead Fe(III) is specifically adsorbed to the mineral structure at multiple sites, thus indicating that the Mn(IV) oxides displaced Fe(III) from the siderophore complex. These results indicate that layer type manganese oxides, including biogenic minerals, may sequester iron from soluble ferric complexes. We conclude that the sorption of iron-siderophore complexes may play a significant role in the bioavailability and biogeochemical cycling of iron in marine and terrestrial environments.

  20. CYP3A4 Mediates Oxidative Metabolism of the Synthetic Cannabinoid AKB-48.

    PubMed

    Holm, Niels Bjerre; Nielsen, Line Marie; Linnet, Kristian

    2015-09-01

    Synthetic cannabinoid designer drugs have emerged as drugs of abuse during the last decade, and acute intoxication cases are documented in the scientific literature. Synthetic cannabinoids are extensively metabolized, but our knowledge of the involved enzymes is limited. Here, we investigated the metabolism of N-(1-adamantyl)-1-pentyl-1H-indazole-3-carboxamide (AKB-48), a compound identified in herbal blends from 2012 and onwards. We screened for metabolite formation using a panel of nine recombinant cytochrome P450 (CYP) enzymes (CYP1A2, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, and 3A4) and compared the formed metabolites to human liver microsomal (HLM) incubations with specific inhibitors against CYP2D6, 2C19, and 3A4, respectively. The data reported here demonstrate CYP3A4 to be the major CYP enzyme responsible for the oxidative metabolism of AKB-48, preferentially performing the oxidation on the adamantyl moiety. Genetic polymorphisms are likely not important with regard to toxicity given the major involvement of CYP3A4. Adverse drug-drug interactions (DDIs) could potentially occur in cases with co-intake of strong CYP3A4 inhibitors, e.g., HIV antivirals and azole antifungal agents. PMID:26002511

  1. Redox potential tuning by redox-inactive cations in nature's water oxidizing catalyst and synthetic analogues.

    PubMed

    Krewald, Vera; Neese, Frank; Pantazis, Dimitrios A

    2016-04-20

    The redox potential of synthetic oligonuclear transition metal complexes has been shown to correlate with the Lewis acidity of a redox-inactive cation connected to the redox-active transition metals of the cluster via oxo or hydroxo bridges. Such heterometallic clusters are important cofactors in many metalloenzymes, where it is speculated that the redox-inactive constituent ion of the cluster serves to optimize its redox potential for electron transfer or catalysis. A principal example is the oxygen-evolving complex in photosystem II of natural photosynthesis, a Mn4CaO5 cofactor that oxidizes water into dioxygen, protons and electrons. Calcium is critical for catalytic function, but its precise role is not yet established. In analogy to synthetic complexes it has been suggested that Ca(2+) fine-tunes the redox potential of the manganese cluster. Here we evaluate this hypothesis by computing the relative redox potentials of substituted derivatives of the oxygen-evolving complex with the cations Sr(2+), Gd(3+), Cd(2+), Zn(2+), Mg(2+), Sc(3+), Na(+) and Y(3+) for two sequential transitions of its catalytic cycle. The theoretical approach is validated with a series of experimentally well-characterized Mn3AO4 cubane complexes that are structural mimics of the enzymatic cluster. Our results reproduce perfectly the experimentally observed correlation between the redox potential and the Lewis acidities of redox-inactive cations for the synthetic complexes. However, it is conclusively demonstrated that this correlation does not hold for the oxygen evolving complex. In the enzyme the redox potential of the cluster only responds to the charge of the redox-inactive cations and remains otherwise insensitive to their precise identity, precluding redox-tuning of the metal cluster as a primary role for Ca(2+) in biological water oxidation. PMID:26762578

  2. Physical characterization of magmatic liquids. [Ultrasonic and Brillouin Scattering Studies of Natural and Synthetic Silicates and Oxides

    SciTech Connect

    Manghnani, M.H.

    1992-06-05

    This report describes a research project that was conducted from August 15, 1985 to February 28, 1992. The project was based on the ultrasonic studies of natural and synthetic silicate melts, and the study of Brillouin scattering of synthetic silicates and oxides. Measurements of the compressional wave velocity and attenuation can be established using the ultrasonic methods. Temperature dependences of silicates can be established by the Brillouin scattering. (MB)

  3. Metabolic engineering of β-oxidation in Penicillium chrysogenum for improved semi-synthetic cephalosporin biosynthesis.

    PubMed

    Veiga, Tânia; Gombert, Andreas K; Landes, Nils; Verhoeven, Maarten D; Kiel, Jan A K W; Krikken, Arjen M; Nijland, Jeroen G; Touw, Hesselien; Luttik, Marijke A H; van der Toorn, John C; Driessen, Arnold J M; Bovenberg, Roel A L; van den Berg, Marco A; van der Klei, Ida J; Pronk, Jack T; Daran, Jean-Marc

    2012-07-01

    Industrial production of semi-synthetic cephalosporins by Penicillium chrysogenum requires supplementation of the growth media with the side-chain precursor adipic acid. In glucose-limited chemostat cultures of P. chrysogenum, up to 88% of the consumed adipic acid was not recovered in cephalosporin-related products, but used as an additional carbon and energy source for growth. This low efficiency of side-chain precursor incorporation provides an economic incentive for studying and engineering the metabolism of adipic acid in P. chrysogenum. Chemostat-based transcriptome analysis in the presence and absence of adipic acid confirmed that adipic acid metabolism in this fungus occurs via β-oxidation. A set of 52 adipate-responsive genes included six putative genes for acyl-CoA oxidases and dehydrogenases, enzymes responsible for the first step of β-oxidation. Subcellular localization of the differentially expressed acyl-CoA oxidases and dehydrogenases revealed that the oxidases were exclusively targeted to peroxisomes, while the dehydrogenases were found either in peroxisomes or in mitochondria. Deletion of the genes encoding the peroxisomal acyl-CoA oxidase Pc20g01800 and the mitochondrial acyl-CoA dehydrogenase Pc20g07920 resulted in a 1.6- and 3.7-fold increase in the production of the semi-synthetic cephalosporin intermediate adipoyl-6-APA, respectively. The deletion strains also showed reduced adipate consumption compared to the reference strain, indicating that engineering of the first step of β-oxidation successfully redirected a larger fraction of adipic acid towards cephalosporin biosynthesis. PMID:22525490

  4. Uranium Isotope Fractionation during Oxidation of Dissolved U(iv) and Synthetic Solid UO2

    NASA Astrophysics Data System (ADS)

    Wang, X.; Johnson, T. M.; Lundstrom, C. C.

    2013-12-01

    U isotopes (238U/235U) show promise as a tool for environmental monitoring of U contamination as well as a proxy for paleo-redox conditions. However, the isotopic fractionation mechanisms of U are still poorly understood. In groundwater systems, U(VI), a mobile contaminant, can be reduced to immobile U(IV) and thus remediated. Previous work shows that 238U/235U of the remaining U(VI) changes with the extent of reduction. Therefore, U(VI) isotope composition in groundwater can potentially be used to detect and perhaps quantify the extent of reduction. However, knowing if isotopic fractionation occurs during U(IV) oxidation is equally important. First, the reduced U(IV) (either solid or as dissolved organic complexes) potentially can be reoxidized to U(VI). If isotope fractionation occurs during oxidation, it would complicate the use of U isotope composition as a monitoring technique. Further, in natural weathering processes, U(IV) minerals are oxidized to form dissolved U(VI), which is carried to rivers and eventually to the ocean and deposited in marine sediments. The weathering cycle is thus sensitive to redox conditions, meaning the sedimentary U isotope record may serve as a paleoredox indicator, provided U isotope fractionation during oxidation and reduction are well known. We conducted experiments oxidizing 2 different U(IV) species by O2 and measuring isotopic fractionation factors. In one experiment, dissolved U(IV) in 0.1 N HCl (pH 1) was oxidized by entrained air. As oxidation proceeds at pH 1, the remaining dissolved U(IV) becomes progressively enriched in 238U in a linear trend, while the product U(VI) paralleled, but was offset to 1.0‰ lighter in 238U/235U. This linear progression of both remaining reactant and product suggests equilibrium fractionation during oxidation of dissolved U(IV) by O2. A second experiment oxidized synthetic, solid UO2 (in 20 mM NaHCO3, pH 7) with entrained air. The oxidative fractionation is very weak in this case with

  5. Novel synthetic methodology for controlling the orientation of zinc oxide nanowires grown on silicon oxide substrates.

    PubMed

    Cho, Jinhyun; Salleh, Najah; Blanco, Carlos; Yang, Sungwoo; Lee, Chul-Jin; Kim, Young-Woo; Kim, Jungsang; Liu, Jie

    2014-04-01

    This study presents a simple method to reproducibly obtain well-aligned vertical ZnO nanowire arrays on silicon oxide (SiOx) substrates using seed crystals made from a mixture of ammonium hydroxide (NH4OH) and zinc acetate (Zn(O2CCH3)2) solution. In comparison, high levels of OH(-) concentration obtained using NaOH or KOH solutions lead to incorporation of Na or K atoms into the seed crystals, destroying the c-axis alignment of the seeds and resulting in the growth of misaligned nanowires. The use of NH4OH eliminates the metallic impurities and ensures aligned nanowire growth in a wide range of OH(-) concentrations in the seed solution. The difference of crystalline orientations between NH4OH- and NaOH-based seeds is directly observed by lattice-resolved images and electron diffraction patterns using a transmission electron microscope (TEM). This study obviously suggests that metallic impurities incorporated into the ZnO nanocrystal seeds are one of the factors that generates the misaligned ZnO nanowires. This method also enables the use of silicon oxide substrates for the growth of vertically aligned nanowires, making ZnO nanostructures compatible with widely used silicon fabrication technology. PMID:24584438

  6. Cerium oxide for the destruction of chemical warfare agents: A comparison of synthetic routes.

    PubMed

    Janoš, Pavel; Henych, Jiří; Pelant, Ondřej; Pilařová, Věra; Vrtoch, Luboš; Kormunda, Martin; Mazanec, Karel; Štengl, Václav

    2016-03-01

    Four different synthetic routes were used to prepare active forms of cerium oxide that are capable of destroying toxic organophosphates: a sol-gel process (via a citrate precursor), homogeneous hydrolysis and a precipitation/calcination procedure (via carbonate and oxalate precursors). The samples prepared via homogeneous hydrolysis with urea and the samples prepared via precipitation with ammonium bicarbonate (with subsequent calcination at 500°C in both cases) exhibited the highest degradation efficiencies towards the extremely dangerous nerve agents soman (O-pinacolyl methylphosphonofluoridate) and VX (O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate) and the organophosphate pesticide parathion methyl. These samples were able to destroy more than 90% of the toxic compounds in less than 10 min. The high degradation efficiency of cerium oxide is related to its complex surface chemistry (presence of surface OH groups and surface non-stoichiometry) and to its nanocrystalline nature, which promotes the formation of crystal defects on which the decomposition of organophosphates proceeds through a nucleophilic substitution mechanism that is not dissimilar to the mechanism of enzymatic hydrolysis of organic phosphates by phosphotriesterase. PMID:26561750

  7. Laccase‐catalysed oxidations of naturally occurring phenols: from in vivo biosynthetic pathways to green synthetic applications

    PubMed Central

    Jeon, Jong‐Rok; Baldrian, Petr; Murugesan, Kumarasamy; Chang, Yoon‐Seok

    2012-01-01

    Summary Laccases are oxidases that contain several copper atoms, and catalyse single‐electron oxidations of phenolic compounds with concomitant reduction of oxygen to water. The enzymes are particularly widespread in ligninolytic basidiomycetes, but also occur in certain prokaryotes, insects and plants. Depending on the species, laccases are involved in various biosynthetic processes contributing to carbon recycling in land ecosystems and the morphogenesis of biomatrices, wherein low‐molecular‐weight naturally occurring phenols serve as key enzyme substrates. Studies of these in vivo synthetic pathways have afforded new insights into fungal laccase applicability in green synthetic chemistry. Thus, we here review fungal laccase‐catalysed oxidations of naturally occurring phenols that are particularly relevant to the synthesis of fine organic chemicals, and we discuss how the discovered synthetic strategies mimic laccase‐involved in vivo pathways, thus enhancing the green nature of such reactions. Laccase‐catalysed in vivo processes yield several types of biopolymers, including those of cuticles, lignin, polyflavonoids, humus and the melanin pigments, using natural mono‐ or poly‐phenols as building blocks. The in vivo synthetic pathways involve either phenoxyl radical‐mediated coupling or cross‐linking reactions, and can be adapted to the design of in vitro oxidative processes involving fungal laccases in organic synthesis; the laccase substrates and the synthetic mechanisms reflect in vivo processes. Notably, such in vitro synthetic pathways can also reproduce physicochemical properties (e.g. those of chromophores, and radical‐scavenging, hydration and antimicrobial activities) found in natural biomaterials. Careful study of laccase‐associated in vivo metabolic pathways has been rewarded by the discovery of novel green applications for fungal laccases. This review comprehensively summarizes the available data on laccase

  8. Laccase-catalysed oxidations of naturally occurring phenols: from in vivo biosynthetic pathways to green synthetic applications.

    PubMed

    Jeon, Jong-Rok; Baldrian, Petr; Murugesan, Kumarasamy; Chang, Yoon-Seok

    2012-05-01

    Laccases are oxidases that contain several copper atoms, and catalyse single-electron oxidations of phenolic compounds with concomitant reduction of oxygen to water. The enzymes are particularly widespread in ligninolytic basidiomycetes, but also occur in certain prokaryotes, insects and plants. Depending on the species, laccases are involved in various biosynthetic processes contributing to carbon recycling in land ecosystems and the morphogenesis of biomatrices, wherein low-molecular-weight naturally occurring phenols serve as key enzyme substrates. Studies of these in vivo synthetic pathways have afforded new insights into fungal laccase applicability in green synthetic chemistry. Thus, we here review fungal laccase-catalysed oxidations of naturally occurring phenols that are particularly relevant to the synthesis of fine organic chemicals, and we discuss how the discovered synthetic strategies mimic laccase-involved in vivo pathways, thus enhancing the green nature of such reactions. Laccase-catalysed in vivo processes yield several types of biopolymers, including those of cuticles, lignin, polyflavonoids, humus and the melanin pigments, using natural mono- or poly-phenols as building blocks. The in vivo synthetic pathways involve either phenoxyl radical-mediated coupling or cross-linking reactions, and can be adapted to the design of in vitro oxidative processes involving fungal laccases in organic synthesis; the laccase substrates and the synthetic mechanisms reflect in vivo processes. Notably, such in vitro synthetic pathways can also reproduce physicochemical properties (e.g. those of chromophores, and radical-scavenging, hydration and antimicrobial activities) found in natural biomaterials. Careful study of laccase-associated in vivo metabolic pathways has been rewarded by the discovery of novel green applications for fungal laccases. This review comprehensively summarizes the available data on laccase-catalysed biosynthetic pathways and associated

  9. Plasma electrolytic oxidation coating of synthetic Al-Mg binary alloys

    SciTech Connect

    Tarakci, Mehmet

    2011-12-15

    The binary Al-Mg synthetic alloys were prepared in a vacuum/atmosphere controlled furnace with the addition of 0.5, 1, 2, 4, 7, and 15 wt.% pure Mg into pure aluminum as substrate material. The surfaces of the Al-Mg alloys and pure aluminum were coated for 120 min by plasma electrolytic oxidation in the same electrolyte of 12 g/L sodium silicate and 2 g/L KOH in distilled water. The coating was characterized by X-ray diffraction, scanning electron microscopy, profilometry and Vickers microhardness measurements. There regions of loose outer layer, dense inner layer with precipitate like particles of {alpha}-Al{sub 2}O{sub 3} and a thin transition layer were identified for the coated samples. The coating thickness increases from 85 to 150 {mu}m with Mg contents in the alloys. The surface morphology becomes more porous and consequently surface roughness tends to increase with plasma electrolytic oxidation treatment and further with Mg content. The increase in magnesium content reduces the formation of {alpha}-Al{sub 2}O{sub 3} and crystalline mullite phases in the coating and decreases microhardness of coating. The Mg concentration is constant throughout the other loose and dense regions of coating though it gradually decreases in the thin inner region. - Research Highlights: Black-Right-Pointing-Pointer The average thickness of PEO coating of Al-Mg alloys increases with Mg content. Black-Right-Pointing-Pointer The addition of Mg reduces and prevents the formation of {alpha}-Al{sub 2}O{sub 3} and mullite. Black-Right-Pointing-Pointer The surface roughness increases with Mg content in the Al-Mg alloys. Black-Right-Pointing-Pointer The hardness values of the coating decreases with the Mg amount in the substrate. Black-Right-Pointing-Pointer The Mg concentration is constant throughout the main regions of coating.

  10. Treatment of synthetic urine by electrochemical oxidation using conductive-diamond anodes.

    PubMed

    Dbira, Sondos; Bensalah, Nasr; Bedoui, Ahmed; Cañizares, Pablo; Rodrigo, Manuel A

    2015-04-01

    In this work, the electrochemical oxidation of synthetic urine by anodic oxidation using boron-doped diamond as anode and stainless steel as cathode was investigated. Results show that complete depletion of chemical oxygen demand (COD) and total organic carbon (TOC) can be attained regardless of the current density applied in the range 20-100 mA cm(-2). Oxalic and oxamic acids, and, in lower concentrations, creatol and guanidine were identified as the main intermediates. Chloride ions play a very important role as mediators and contribute not only to obtain a high efficiency in the removal of the organics but also to obtain an efficient removal of nitrogen by the transformation of the various raw nitrogen species into gaseous nitrogen through chloramine formation. The main drawback of the technology is the formation of chlorates and perchlorates as final chlorine products. The increase of current density from 20 to 60 mA cm(-2) led to an increase in the rate of COD and TOC removals although the process becomes less efficient in terms of energy consumption (removals of COD and TOC after applying 18 Ah dm(-3) were 93.94 and 94.94 %, respectively, at 20 mA cm(-2) and 89.17 and 86.72 %, respectively, at 60 mA cm(-2)). The most efficient conditions are low current densities and high temperature reaching total mineralization at an applied charge as low as 20 kAh m(-3). This result confirmed that the electrolysis using diamond anodes is a very interesting technology for the treatment of urine. PMID:25399531

  11. Neurotoxicity by synthetic androgen steroids: oxidative stress, apoptosis, and neuropathology: A review.

    PubMed

    Pomara, Cristoforo; Neri, Margherita; Bello, Stefania; Fiore, Carmela; Riezzo, Irene; Turillazzi, Emanuela

    2015-01-01

    Anabolic-androgenic steroids (AAS) are synthetic substances derived from testosterone that are largely employed due to their trophic effect on muscle tissue of athletes at all levels. Since a great number of organs and systems are a target of AAS, their adverse effects are primarily on the following systems: reproductive, hepatic, musculoskeletal, endocrine, renal, immunological, infectious, cardiovascular, cerebrovascular, and hematological. Neuropsychiatric and behavioral effects as a result of AAS abuse are well known and described in the literature. Mounting evidence exists suggesting that in addition to psychiatric and behavioral effects, non-medical use of AAS carries neurodegenerative potential. Although, the nature of this association remains largely unexplored, recent animal studies have shown the recurrence of this AAS effect, ranging from neurotrophin unbalance to increased neuronal susceptibility to apoptotic stimuli. Experimental and animal studies strongly suggest that apoptotic mechanisms are at least in part involved in AAS-induced neurotoxicity. Furthermore, a great body of evidence is emerging suggesting that increased susceptibility to cellular oxidative stress could play a pivotal role in the pathogenesis of many neurodegenerative disorders and cognitive impairment. As in other drug-evoked encephalopathies, the key mechanisms involved in AAS - induced neuropathology could represent a target for future neuroprotective strategies. Progress in the understanding of these mechanisms will provide important insights into the complex pathophysiology of AAS-induced neurodegeneration, and will pave the way for forthcoming studies. Supplementary to abandoning the drug abuse that represents the first step in reducing the possibility of irreversible brain damage in AAS abusers, neuroprotective strategies have to be developed and implemented in future. PMID:26074748

  12. Heterogeneous oxidation of a phosphocholine on synthetic sea salt by ozone at room temperature.

    PubMed

    Dilbeck, Christopher W; Finlayson-Pitts, Barbara J

    2013-02-14

    The ozonolysis of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) adsorbed on salt mixtures as models for sea-salt particles was studied in real time using diffuse reflection infrared Fourier transform spectrometry (DRIFTS) at room temperature with and without added water vapor. The salt substrates were a mixture of MgCl(2)·6H(2)O with NaCl or a commercially available synthetic sea salt. Ozone concentrations ranged from (0.25 to 3.9) × 10(13) molecules cm(-3) (0.1-1.6 ppm). The major products identified by FTIR and confirmed using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry were the secondary ozonide (SOZ) and a phospholipid aldehyde and carboxylic acid formed by scission of the double bond. The reaction probabilities for the two substrates were similar, γ = (6-7) × 10(-7), with an estimated overall uncertainty of a factor of two. The presence of water vapor decreased the yield of SOZ relative to the products formed by C[double bond, length as m-dash]C scission, but also increased the availability of the double bond for reaction, particularly on the less hygroscopic commercial sea-salt substrate. Thus, water not only affects the mechanisms and products, but also the structure of the phospholipid on the salt in a manner that affects its reactivity. The results of these studies suggest that the reactivity and products of oxidation of unsaturated phospholipids on sea-salt particles in air will be very sensitive to the nature and phase of the substrate, the amount of water present, and whether there is phase separation between the organics and the inorganic salt mixture. PMID:23258195

  13. Neurotoxicity by Synthetic Androgen Steroids: Oxidative Stress, Apoptosis, and Neuropathology: A Review

    PubMed Central

    Pomara, Cristoforo; Neri, Margherita; Bello, Stefania; Fiore, Carmela; Riezzo, Irene; Turillazzi, Emanuela

    2015-01-01

    Anabolic-androgenic steroids (AAS) are synthetic substances derived from testosterone that are largely employed due to their trophic effect on muscle tissue of athletes at all levels. Since a great number of organs and systems are a target of AAS, their adverse effects are primarily on the following systems: reproductive, hepatic, musculoskeletal, endocrine, renal, immunological, infectious, cardiovascular, cerebrovascular, and hematological. Neuropsychiatric and behavioral effects as a result of AAS abuse are well known and described in the literature. Mounting evidence exists suggesting that in addition to psychiatric and behavioral effects, non-medical use of AAS carries neurodegenerative potential. Although, the nature of this association remains largely unexplored, recent animal studies have shown the recurrence of this AAS effect, ranging from neurotrophin unbalance to increased neuronal susceptibility to apoptotic stimuli. Experimental and animal studies strongly suggest that apoptotic mechanisms are at least in part involved in AAS-induced neurotoxicity. Furthermore, a great body of evidence is emerging suggesting that increased susceptibility to cellular oxidative stress could play a pivotal role in the pathogenesis of many neurodegenerative disorders and cognitive impairment. As in other drug-evoked encephalopathies, the key mechanisms involved in AAS – induced neuropathology could represent a target for future neuroprotective strategies. Progress in the understanding of these mechanisms will provide important insights into the complex pathophysiology of AAS-induced neurodegeneration, and will pave the way for forthcoming studies. Supplementary to abandoning the drug abuse that represents the first step in reducing the possibility of irreversible brain damage in AAS abusers, neuroprotective strategies have to be developed and implemented in future. PMID:26074748

  14. Ceric ammonium nitrate (CAN) catalyzed modification of ketones via two C-C bond cleavages with the retention of the oxo-group.

    PubMed

    Feng, Peng; Sun, Xiang; Su, Yijin; Li, Xinyao; Zhang, Li He; Shi, Xiaodong; Jiao, Ning

    2014-06-20

    A simple ceric ammonium nitrate (CAN) catalyzed functionalization of ketones through double C-C bond cleavage strategy has been disclosed. This reaction provides a mild, practical method toward carbamoyl azides, which are versatile intermediates and building blocks in organic synthesis. Based on relevant mechanistic studies, a unique and plausible C-C bond and N-O bond cleavage process is proposed, where the oxyamination intermediate plays an important role in this reaction. PMID:24906031

  15. Synthetic modeling chemistry of iron-sulfur clusters in nitric oxide signaling.

    PubMed

    Fitzpatrick, Jessica; Kim, Eunsuk

    2015-08-18

    Nitric oxide (NO) is an important signaling molecule that is involved in many physiological and pathological functions. Iron-sulfur proteins are one of the main reaction targets for NO, and the [Fe-S] clusters within these proteins are converted to various iron nitrosyl species upon reaction with NO, of which dinitrosyl iron complexes (DNICs) are the most prevalent. Much progress has been made in identifying the origin of cellular DNIC generation. However, it is not well-understood which other products besides DNICs may form during [Fe-S] cluster degradation nor what effects DNICs and other degradation products can have once they are generated in cells. Even more elusive is an understanding of the manner by which cells cope with unwanted [Fe-S] modifications by NO. This Account describes our synthetic modeling efforts to identify cluster degradation products derived from the [2Fe-2S]/NO reaction in order to establish their chemical reactivity and repair chemistry. Our intent is to use the chemical knowledge that we generate to provide insight into the unknown biological consequences of cluster modification. Our recent advances in three different areas are described. First, new reaction conditions that lead to the formation of previously unrecognized products during the reaction of [Fe-S] clusters with NO are identified. Hydrogen sulfide (H2S), a gaseous signaling molecule, can be generated from the reaction between [2Fe-2S] clusters and NO in the presence of acid or formal H• (e(-)/H(+)) donors. In the presence of acid, a mononitrosyl iron complex (MNIC) can be produced as the major iron-containing product. Second, cysteine analogues can efficiently convert MNICs back to [2Fe-2S] clusters without the need for any other reagents. This reaction is possible for cysteine analogues because of their ability to labilize NO from MNICs and their capacity to undergo C-S bond cleavage, providing the necessary sulfide for [2Fe-2S] cluster formation. Lastly, unique dioxygen

  16. Determination of a kinetic region in catalytic oxidation of carbon monoxide

    NASA Technical Reports Server (NTRS)

    Sultanov, M. Y.; Sadykhova, K. A.

    1981-01-01

    The catalytic activity of cupric oxide activated with ceric oxide in a braod interval of volumetric velocities was investigated. It was determined that for practical catalysts used in the diffuse region, dilution of the active substance by an inert diluent increases the effectiveness of the catalysts.

  17. A comparison between conductive-diamond electrochemical oxidation and other advanced oxidation processes for the treatment of synthetic melanoidins.

    PubMed

    Cañizares, P; Hernández-Ortega, M; Rodrigo, M A; Barrera-Díaz, C E; Roa-Morales, G; Sáez, C

    2009-05-15

    In this study, three technologies classified as Advanced Oxidation Processes (Conductive-Diamond Electrochemical Oxidation (CDEO), ozonation and Fenton oxidation) have been compared to treat wastes produced in fermentation processes, and characterized by a significant color and a high organic load. Results of CDEO seem to strongly depend on the addition of an electrolyte salt, not only to decrease the energy cost but also to improve efficiency. The addition of sodium chloride as supporting electrolyte improves the removal percentages of organic load, indicating the important role of mediated oxidation processes carried out by the electrogenerated oxidants (hypochlorite). Fenton oxidation and ozonation seem to be less efficient, and mainly Fenton oxidation favors the accumulation of refractory compounds. The differences observed can be explained in terms of the contribution of hydroxyl radicals and other specific oxidation mechanisms involved in each technology. PMID:18789836

  18. Possibilities of liquid-phase low-temperature deposition of manganese oxides on NaY synthetic zeolite

    SciTech Connect

    Eremeev, A.P.; Petrusevich, E.F.

    1985-05-20

    This paper studies the possibilities of low-temperature liquid-phase deposition of manganese oxides on NaY synthetic zeolite and compares the results with literature data. The experiments were conducted in accordance with a design matrix that is presented in a table. The coefficients of regression equations are presented which describe the experimental responses against the background of the errors. A summary is given of rounded-off estimates of relative errors of determination of manganese oxides on the three zeolite types studied and the average values of responses of the same type for all the zeolites. It follows that the optimal estimates of the Mn/sub 2/O/sub 3/ and MnO/sub 2/ contents are the same for all the zeolites within the averaged error limits, while the estimates of MnO contents and conversion of Mn (II) from solution on the zeolite surface are not the same for clinoptilolite as for synthetic NaY, confirming that oxidation proceeds more actively on the NaY surface, while conversion is very pronounced in the case of clinoptilolite.

  19. Effects of Wet Air and Synthetic Combustion Gas Atmospheres on the Oxidation Behavior of Mo-Si-B Alloys

    SciTech Connect

    Kramer, M.J.; Thom, A.J.; Mandal, P.; Behrani, V.; Akinc, M.

    2003-04-24

    Continuing our work on understanding the oxidation behavior of multiphase composite alloys based on the Mo-Si-B system, we investigated three alloys in the Mo-Si-B system, designated as A1, A2, and A3. The nominal phase assemblages of these alloys are: A1 = Mo{sub 5}Si{sub 3}B{sub x} (T1)-MoSi{sub 2}-MoB, A2 = T1-Mo{sub 5}SiB{sub 2} (T2)-Mo{sub 3}Si, and A3 = Mo-T2-Mo{sub 3}Si. Our previous work showed that for exposures to 1100 C, all alloys formed a protective oxide scale in dry air. Exposures to wet air containing about 150 Torr water promoted the formation of a multiphase layer near the scale/alloy interface composed of Mo and MoO{sub 2}. Interrupted mass loss measurements indicated a near zero mass change. In the present study, isothermal mass measurements were conducted in order to quantitatively determine the oxidation rate constants at 1000 C in both dry and wet air. These measurements are critical for understanding the nature of scale development during the initial exposure, as well as the nature of scale stability during the long-term exposure. Isothermal measurements were also conducted at 1600 C in dry air to make an initial determination of alloy stability with respect to Vision 21 goals. We also conducted alloy oxidation testing in a synthetic oxidizing combustion atmosphere. Alloys were exposed up to 300 hours at 1100 C to a gas mixture having an approximate gas composition of N{sub 2} - 13 CO{sub 2} - 10 H{sub 2}O - 4 O{sub 2}. This gas composition simulates oxidizing flue gas, but does not contain a sulfidizing agent that would also be present in flue gas. The oxidized samples were carefully analyzed by SEM/EDS. This analysis will be discussed to provide an understanding of the role of water vapor and the synthetic combustion atmosphere on the oxidative stability of Mo-Si-B alloys.

  20. Ascorbic acid, glutathione and synthetic antioxidants prevent the oxidation of vitamin E in platelets.

    PubMed

    Vatassery, G T; Smith, W E; Quach, H T

    1989-12-01

    An earlier report from this laboratory showed that tocopherol in human platelets is oxidized when the platelets are incubated in vitro in Tyrode medium with arachidonate (or other oxidants). Arachidonate is a more potent oxidizing agent in 50 mM potassium phosphate buffer at pH 7.4 with 0.1 mM ethylenediaminetetraacetic acid (EDTA) than in Tyrode medium. Forty to fifty percent of total platelet tocopherol was oxidized upon incubation with 40-50 microM arachidonate in the phosphate-buffered medium. The tocopherol oxidation took place within 15 min after the addition of arachidonate. Preincubation of platelets with ascorbate blocked the oxidation of tocopherol. This is one of the first direct in vitro demonstrations of the vitamin E-sparing action of vitamin C in media containing biological cellular material. Other compounds which blocked the oxidation of platelet tocopherol were ascorbyl palmitate, propyl gallate, butylated hydroxytoluene, hydroquinone and glutathione. If ascorbate or glutathione was added after the tocopherol was oxidized to the quinone there was no reversal of the oxidation. PMID:2515405

  1. Oxidation Kinetics and Textures for Natural and Synthetic MORB Glasses and Subliquidus Melts: RBS Analyses

    NASA Astrophysics Data System (ADS)

    Burgess, K.; Cooper, R. F.; Cherniak, D. J.

    2007-12-01

    The dynamics of oxidation of basaltic melts and glasses involves the diffusive motion of network-modifying cations out of the material (i.e., to the free surface) where they react with atmospheric oxygen to produce oxide precipitates or thin films. The cation flux is countered by an inward flux of electron holes; thus the material, modified by the loss of cations, experiences, too, oxidation at an internal front [e.g., Cook & Cooper, 2000]. The texture so produced is a complex, non-equilibrium one. For glasses of similar polymerization to basalts, the internal oxidation front often involves the precipitation of nanometer-scale ferrites; in the oxidation dynamic, because of the persistent, metastable texture, there is no reason to believe that these ferrites should have compositions predicted by chemical equilibrium. The effect on understanding paleomagnetic field strength recorded in MORBs could be profound: this is the long-range goal of our experiments. We report here on oxidation textures produced for three glasses and melts produced from (i) a natural MORB and (ii) mixed oxides to produce MORB analogs \\--- one free of all alkali cations. All materials were melted at ambient pressure at 1430°C in an atmosphere buffered at FMQ. Glasses so prepared had their glass-transition temperatures (Tg) characterized by thermal analysis. Oxidation experiments were performed on well- annealed glass specimens at temperatures Tg ± ~25°C as well as on crystallizing melts at 900°C; oxidation was done in dry air at ambient pressure. Ion (Rutherford) backscattering spectrometry (RBS) was used to characterize the near-surface texture (chemical distribution) of the oxidized specimens. The textures are found to be sensitive to oxidation temperature, initial melt polymerization, and the bulk chemistry (particularly as it affects the summed partial molar volumes of network-modifying oxides). A general result \\--- applicable to all compositions \\--- is that out-diffusion of ionic

  2. Immobilization, hybridization, and oxidation of synthetic DNA on gold surface: electron transfer investigated by electrochemistry and scanning tunneling microscopy

    PubMed Central

    McEwen, Gerald D.; Chen, Fan; Zhou, Anhong

    2009-01-01

    Fundamental understanding of interfacial electron transfer (ET) among electrolyte/DNA/solid-surface will facilitate the design for electrical detection of DNA molecules. In this report, the electron transfer characteristics of synthetic DNA (sequence from pathogenic Cryptosporidium parvum) self-assembled on a gold surface was electrochemically studied. The effects of immobilization order on the interface ET related parameters such as diffusion coefficient (D0), surface coverage (θR), and monolayer thickness (di) were determined by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). DNA surface density (ΓDNA) was determined by the integration of the charge of the electro-oxidation current peaks during the initial cyclic voltammetry scans. It was found that the DNA surface density at different modifications followed the order: ΓDNA (dsS-DNA/Au) > ΓDNA (MCH/dsS-DNA/Au) > ΓDNA (dsS-DNA/MCH/Au). It was also revealed that the electro-oxidation of the DNA modified gold surface would involve the oxidation of nucleotides (guanine and adenine) with a 5.51 electron transfer mechanism and the oxidative desorption of DNA and MCH molecules by a 3 electron transfer mechanism. STM topography and current image analysis indicated that the surface conductivity after each surface modification followed the order: dsS-DNA/Au < MCH/dsS-DNA/Au < oxidized MCH/dsS-DNA/Au < Hoechst/oxidized MCH/dsS-DNA/Au. The results from this study suggested a combination of variations in immobilization order may provide an alternative approach for the optimization of DNA hybridization and the further development for electrical detection of DNA. PMID:19446060

  3. Physical Stability, Autoxidation, and Photosensitized Oxidation of ω-3 Oils in Nanoemulsions Prepared with Natural and Synthetic Surfactants.

    PubMed

    Uluata, Sibel; McClements, D Julian; Decker, Eric A

    2015-10-28

    The food industry is interested in the utilization of nanoemulsions stabilized by natural emulsifiers, but little research has been conducted to determine the oxidative stability of such emulsions. In this study, two natural (lecithin and quillaja saponin) and two synthetic (Tween 80 and sodium dodecyl sulfate) surfactants were used to fabricate omega-3 nanoemulsion using high pressure homogenization (microfluidization). Initially, all the nanoemulsions contained small (d from 45 to 89 nm) and anionic (ζ-potential from -8 to -65 mV) lipid droplets (pH 7). The effect of pH, ionic strength, and temperature on the physical stability of the nanoemulsion system was examined. Nanoemulsion stabilized with Tween 80, quillaja saponin, or sodium dodecyl sulfate (SDS) exhibited no major changes in particle size or visible creaming in the pH range of 3 to 8. All nanoemulsions were relatively stable to salt addition (0 to 500 mM NaCl, pH 7.0). Nanoemulsions stabilized with SDS and quillaja saponin were stable to heating (30 to 90 °C). The impact of surfactant type on lipid oxidation was determined in the presence and absence of the singlet oxygen photosensitizers, riboflavin, and rose bengal. Riboflavin and rose bengal accelerated lipid oxidation when compare to samples without photosensitizers. Lipid hydroperoxide formation followed the order Tween 80 > SDS > lecithin > quillaja saponin, and propanal formation followed the order lecithin > Tween 80 > SDS > quillaja saponin at 37 °C for autoxidation. The same order of oxidative stability was observed in the presence of photosensitized oxidation promoted by riboflavin. Quillaja saponin consistently produced the most oxidatively stable emulsions, which could be due to its high free radical scavenging capacity. PMID:26452408

  4. Oxidative bioelectrocatalysis: From natural metabolic pathways to synthetic metabolons and minimal enzyme cascades.

    PubMed

    Minteer, Shelley D

    2016-05-01

    Anodic bioelectrodes for biofuel cells are more complex than cathodic bioelectrodes for biofuel cells, because laccase and bilirubin oxidase can individually catalyze four electron reduction of oxygen to water, whereas most anodic enzymes only do a single two electron oxidation of a complex fuel (i.e. glucose oxidase oxidizing glucose to gluconolactone while generating 2 electrons of the total 24 electrons), so enzyme cascades are typically needed for complete oxidation of the fuel. This review article will discuss the lessons learned from natural metabolic pathways about multi-step oxidation and how those lessons have been applied to minimal or artificial enzyme cascades. This article is part of a Special Issue entitled Biodesign for Bioenergetics - the design and engineering of electronic transfer cofactors, proteins and protein networks, edited by Ronald L. Koder and J.L. Ross Anderson. PMID:26334845

  5. METHOD OF MAINTAINING PLUTONIUM IN A HIGHER STATE OF OXIDATION DURING PROCESSING

    DOEpatents

    Thompson, S.G.; Miller, D.R.

    1959-06-30

    This patent deals with the oxidation of tetravalent plutonium contained in an aqueous acid solution together with fission products to the hexavalent state, prior to selective fission product precipitation, by adding to the solution bismuthate or ceric ions as the oxidant and a water-soluble dichromate as a holding oxidant. Both oxidant and holding oxidant are preferably added in greater than stoichiometric quantities with regard to the plutonium present.

  6. Nitric Oxide Synthetic Pathway in Red Blood Cells Is Impaired in Coronary Artery Disease

    PubMed Central

    Eligini, Sonia; Porro, Benedetta; Lualdi, Alessandro; Squellerio, Isabella; Veglia, Fabrizio; Chiorino, Elisa; Crisci, Mauro; Garlaschè, Anna; Giovannardi, Marta; Werba, Josè-Pablo; Tremoli, Elena; Cavalca, Viviana

    2013-01-01

    Background All the enzymatic factors/cofactors involved in nitric oxide (NO) metabolism have been recently found in red blood cells. Increased oxidative stress impairs NO bioavailability and has been described in plasma of coronary artery disease (CAD) patients. The aim of the study was to highlight a potential dysfunction of the metabolic profile of NO in red blood cells and in plasma from CAD patients compared with healthy controls. Methods We determined L-arginine/NO pathway by liquid-chromatography tandem mass spectrometry and high performance liquid chromatography methods. The ratio of oxidized and reduced forms of glutathione, as index of oxidative stress, was measured by liquid-chromatography tandem mass spectrometry method. NO synthase expression and activity were evaluated by immunofluorescence staining and ex-vivo experiments of L-[15N2]arginine conversion to L-[15N]citrulline respectively. Results Increased amounts of asymmetric and symmetric dimethylarginines were found both in red blood cells and in plasma of CAD patients in respect to controls. Interestingly NO synthase expression and activity were reduced in CAD red blood cells. In contrast, oxidized/reduced glutathione ratio was increased in CAD and was associated to arginase activity. Conclusion Our study analyzed for the first time the whole metabolic pathway of L-arginine/NO, both in red blood cells and in plasma, highlighting an impairment of NO pathway in erythrocytes from CAD patients, associated with decreased NO synthase expression/activity and increased oxidative stress. PMID:23940508

  7. Comparative assessment of synthetic strategies toward active platinum-rhodium-tin electrocatalysts for efficient ethanol electro-oxidation

    NASA Astrophysics Data System (ADS)

    Erini, Nina; Krause, Paul; Gliech, Manuel; Yang, Ruizhi; Huang, Yunhui; Strasser, Peter

    2015-10-01

    The present work explores the effect of autoclave-based autogenous-pressure vs. ambient pressure conditions on the synthesis and properties of carbon-supported Pt-Rh-Sn nanoparticle electrocatalysts. The Pt-Rh-Sn nanoparticles were characterized by X-ray spectroscopy, electron microscopy and mass spectroscopy and deployed as catalysts for the electrocatalytic ethanol oxidation reaction. Pt-Rh-Sn catalysts precipitated with carbon already present showed narrow particle size distribution around 7 nm, while catalysts supported on carbon after particle formation showed broader size distribution ranging from 8 to 16 nm, similar metal loadings between 40 and 48 wt.% and similar atomic ratios of Pt:Rh:Sn of 30:10:60. The highest ethanol oxidation activity at low overpotentials associated with exceptionally early ethanol oxidation onset potential was observed for ambient-pressure catalysts with the active ternary alloy phase formed in presence of the carbon supports. In contrast, catalysts prepared under ambient pressure in a two-step approach, involving alloy particle formation followed by particle separation and subsequent deposition on the carbon support, yielded the highest overall mass activities. Based on the observed synthesis-activity correlations, a comparative assessment is provided of the synthetic techniques at high vs. low pressures, and in presence and absence of carbon support. Plausible hypotheses in terms of particle dispersion and interparticle distance accounting for these observed differences are discussed.

  8. The oxidation of benzo[a]pyrene mediated by lipid peroxidation in irradiated synthetic diets.

    PubMed

    Gower, J D; Wills, E D

    1986-03-01

    The effect of gamma-irradiation (1000-4000 Gy) on the formation of lipid peroxides and on the oxidation of the environmental carcinogen benzo[a]pyrene (BP) has been studied in mixtures of starch/fat and BP which were used as models for natural foods. When mixtures containing polyunsaturated fats (mackerel oil and cod-liver oil which contain relatively large proportions of C20:5 and C22:6) were exposed to gamma-irradiation, large concentrations of lipid peroxide were formed and a concomitant oxidation of BP to mutagenic and toxic BP quinones took place. The rate of BP oxidation was closely related to the extent of peroxidation of the lipids in the starch mixtures and was dependent on the dose of gamma-irradiation and the presence of air. Mackerel oil also underwent peroxidation during the storage of both irradiated and unirradiated starch/mackerel oil/BP mixtures and this resulted in a significant oxidation of the BP present in these samples. Antioxidants such as vitamin E and BHA inhibited both lipid peroxidation and BP oxidation resulting from gamma-irradiation. These results demonstrate that the species generated during the peroxidation of unsaturated fats in foodstuffs can react with polycyclic aromatic hydrocarbons such as BP and convert them into active mutagenic and toxic products. This has important toxicological implications, particularly as the consumption of polyunsaturated fat in the Western world is increasing and gamma-irradiation may soon be widely used for food sterilization. PMID:3485594

  9. Evaluation of the efficiency of monopolar and bipolar BDD electrodes for electrochemical oxidation of anthraquinone textile synthetic effluent for reuse.

    PubMed

    Abdessamad, NourElHouda; Akrout, Hanene; Hamdaoui, Ghaith; Elghniji, Kais; Ksibi, Mohamed; Bousselmi, Latifa

    2013-10-01

    The efficiency of the electrochemical degradation of synthetic wastewater containing an anthraquinone dye has been comparatively studied in two electrolytic cells with a synthetic boron-doped diamond (Si/BDD) as an anode. The first is an individual cell (Cell 1) with monopolar electrode BDD and the second (Cell 2) has two bipolar electrodes BDD self-polarized. The bulk electrolysis was performed at the same initial operating conditions in order to quantify the influence of the initial pH and current density on dye discoloration and global mineralization removal. The current efficiency and the consumption energy were also evaluated. When the same solutions have been comparatively treated with the two cells, a quite good mineralization is found in Cell 2. This result supposed more fraction of the applied current is used for the electrocombustion reaction on Cell 2 if compared to Cell 1 and small amount rest for the side reaction of oxygen evolution. The HPLC analyses confirmed this hypothesis and showed that the concentration trend of intermediates (sulfanilic acid, phthalate acid and salicylic acid) with electrolysis time was different on two cells. Phototoxicity tests show that the electrochemical oxidation with BDD electrodes could be useful as a pretreatment technique for reducing hazardous wastewater toxicity. PMID:23916748

  10. Water oxidation chemistry of a synthetic dinuclear ruthenium complex containing redox-active quinone ligands.

    PubMed

    Isobe, Hiroshi; Tanaka, Koji; Shen, Jian-Ren; Yamaguchi, Kizashi

    2014-04-21

    We investigated theoretically the catalytic mechanism of electrochemical water oxidation in aqueous solution by a dinuclear ruthenium complex containing redox-active quinone ligands, [Ru2(X)(Y)(3,6-tBu2Q)2(btpyan)](m+) [X, Y = H2O, OH, O, O2; 3,6-tBu2Q = 3,6-di-tert-butyl-1,2-benzoquinone; btpyan =1,8-bis(2,2':6',2″-terpyrid-4'-yl)anthracene] (m = 2, 3, 4) (1). The reaction involves a series of electron and proton transfers to achieve redox leveling, with intervening chemical transformations in a mesh scheme, and the entire molecular structure and motion of the catalyst 1 work together to drive the catalytic cycle for water oxidation. Two substrate water molecules can bind to 1 with simultaneous loss of one or two proton(s), which allows pH-dependent variability in the proportion of substrate-bound structures and following pathways for oxidative activation of the aqua/hydroxo ligands at low thermodynamic and kinetic costs. The resulting bis-oxo intermediates then undergo endothermic O-O radical coupling between two Ru(III)-O(•) units in an anti-coplanar conformation leading to bridged μ-peroxo or μ-superoxo intermediates. The μ-superoxo species can liberate oxygen with the necessity for the preceding binding of a water molecule, which is possible only after four-electron oxidation is completed. The magnitude of catalytic current would be limited by the inherent sluggishness of the hinge-like bending motion of the bridged μ-superoxo complex that opens up the compact, hydrophobic active site of the catalyst and thereby allows water entry under dynamic conditions. On the basis of a newly proposed mechanism, we rationalize the experimentally observed behavior of electrode kinetics with respect to potential and discuss what causes a high overpotential for water oxidation by 1. PMID:24694023

  11. Crystalline nanoporous metal oxide thin films by post-synthetic hydrothermal transformation: SnO2 and TiO2.

    PubMed

    Shao, Shaofeng; Dimitrov, Momtchil; Guan, Naijia; Köhn, Ralf

    2010-10-01

    Nanostructured and nanoporous metal oxide thin films are rarely accessible by standard synthetic approaches but highly desired for many applications, e.g. as electrodes, transparent conducting coatings, sensors or surface catalysts. Template based sol–gel chemistry combined with post-synthetic hydrothermal treatment allows now the synthesis of nanocrystalline mesostructured porous thin films of metal oxides, e.g. tin oxide and titania. Even in cases where the crystallization cannot be induced highly stable thin films can be achieved, e.g. niobium oxide thin films. We demonstrate how the size of the nanocrystallites influences and stabilizes the mesostructure at temperatures as low as 100 C and thereby in the case of titania or tin dioxide even prevents it from deterioration at higher temperatures up to 400–600 C. PMID:20945539

  12. The effect of As, Co, and Ni impurities on pyrite oxidation kinetics: An electrochemical study of synthetic pyrite

    NASA Astrophysics Data System (ADS)

    Lehner, Stephen; Savage, Kaye; Ciobanu, Madalina; Cliffel, David E.

    2007-05-01

    Synthetic pyrite crystals doped with As, Co, or Ni, undoped pyrite, and natural arsenian pyrite from Leadville, Colorado were investigated with electrochemical techniques and solid-state measurements of semiconducting properties to determine the effect of impurity content on pyrite's oxidation behavior. Potential step experiments, cyclic voltammetry, and AC voltammetry were performed in a standard three-electrode electrochemical cell setup. A pH 1.78 sulfuric acid solution containing 1 mM ferric iron, open to atmospheric oxygen, was chosen to approximate water affected by acid drainage. Van der Pauw/Hall effect measurements determined resistivity, carrier concentration and carrier mobility. The anodic dissolution of pyrite and the reduction of ferric iron half-reactions are taken as proxies for natural pyrite oxidation. Pyrite containing no impurities is least reactive. Pyrite with As is more reactive than pyrite with either Ni or Co despite lower dopant concentration. As, Co, and Ni impurities introduce bulk defect states at different energy levels within the band gap. Higher reactivity of impure pyrite suggests that introduced defect levels lead to higher density of occupied surface states at the solid-solution interface and increased metallic behavior. The current density generated from potential step experiments increased with increasing As concentration. The higher reactivity of As-doped pyrite may be related to p-type conductivity and corrosion by holes. The results of this study suggest that considering the impurity content of pyrite in mining waste may lead to more accurate risk assessment of acid producing potential.

  13. Colloidal stability of magnetic iron oxide nanoparticles: influence of natural organic matter and synthetic polyelectrolytes.

    PubMed

    Ghosh, Saikat; Jiang, Wei; McClements, Julian D; Xing, Baoshan

    2011-07-01

    The colloidal behavior of natural organic matter (NOM) and synthetic poly(acrylic acid) (PAA)-coated ferrimagnetic (γFe(2)O(3)) nanoparticles (NPs) was investigated. Humic acid (HA), an important component of NOM, was extracted from a peat soil. Two different molecular weight PAAs were also used for coating. The colloidal stability of the coated magnetic NPs was evaluated as a resultant of the attractive magnetic dipolar and van der Waals forces and the repulsive electrostatic and steric-electrosteric interactions. The conformational alterations of the polyelectrolytes adsorbed on magnetic γFe(2)O(3) NPs and their role in colloidal stability were determined. Pure γFe(2)O(3) NPs were extremely unstable because of aggregation in aqueous solution, but a significant stability enhancement was observed after coating with polyelectrolytes. The steric stabilization factor induced by the polyelectrolyte coating strongly dictated the colloidal stability. The pH-induced conformational change of the adsorbed, weakly charged polyelectrolytes had a significant effect on the colloidal stability. Atomic force microscopy (AFM) revealed the stretched conformation of the HA molecular chains adsorbed on the γFe(2)O(3) NP surface at pH 9, which enhanced the colloidal stability through long-range electrosteric stabilization. The depletion of the polyelectrolyte during the dilution of the NP suspension decreased the colloidal stability under acidic solution conditions. The conformation of the polyelectrolytes adsorbed on the NP surface was altered as a function of the substrate surface charge as viewed from AFM imaging. The polyelectrolyte coating also led to a reduction in magnetic moments and decreased the coercivity of the coated γFe(2)O(3) NPs. Thus, the enhanced stabilization of the coated maghematite NPs may facilitate their delivery in the groundwater for the effective removal of contaminants. PMID:21650201

  14. Inactivation of dinoflagellate Scripsiella trochoidea in synthetic ballast water by advanced oxidation processes.

    PubMed

    Yang, Zhishan; Jiang, Wenju; Zhang, Yi; Lim, T M

    2015-01-01

    Ship-borne ballast water contributes significantly to the transfer of non-indigenous species across aquatic environments. To reduce the risk of bio-invasion, ballast water should be treated before discharge. In this study, the efficiencies of several conventional and advanced oxidation processes were investigated for potential ballast water treatment, using a marine dinoflagellate species, Scripsiella trochoidea, as the indicator organism. A stable and consistent culture was obtained and treated by ultraviolet (UV) light, ozone (O3), hydrogen peroxide (H2O2), and their various combinations. UV apparently inactivated the cells after only 10 s of irradiation, but subsequently photo-reactivation of the cells was observed for all methods involving UV. O3 exhibited 100% inactivation efficiency after 5 min treatment, while H2O2 only achieved maximum 80% inactivation in the same duration. Combined methods, e.g. UV/O3 and UV/H2O2, were found to inhibit photo-reactivation and improve treatment efficiency to some degree, indicating the effectiveness of using combined treatment processes. The total residual oxidant (TRO) levels of the methods were determined, and the results indicated that UV and O3 generated the lowest and highest TRO, respectively. The synergic effect of combined processes on TRO generation was found to be insignificant, and thus UV/O3 was recommended as a potentially suitable treatment process for ballast water. PMID:25182606

  15. Study on synthetic methods of trialkyl phosphate oxide and its extraction behavior of some acids

    SciTech Connect

    Yu, M.J.; Su, Y.F.

    1987-01-01

    Trioctyl phosphine oxide (TOPO) is useful for the extraction of many inorganic and organic compounds. A mixed trialkyl phosphine oxide (TRPO) is similar in property to TOPO. The total number of carbon atoms per molecule of TRPO ranges from 15 to 27. Three methods for synthesizing TRPO are described in this paper. When TRPO is synthesized from an alcohol mixture it is significantly cheaper than a single pure alcohol as required for the production of TOPO; tedious purification steps are eliminated. TRPO is a brown liquid which is very slightly soluble in water. Toxicological measurements of LD50, AMES test, hereditary and accumulative toxicity show that TRPO is safe for use in the extraction of some pharmaceutical and biochemical compounds. Examinations of IR and NMR show that the complex interaction of P=O bond of TRPO with extracted substances is the same as that of TOPO. The distribution coefficients of phosphoric acid, citric acid, malic acid, oxalic acid, and tartaric acid with TRPO are reported. The extraction of these acids is believed to proceed by neutral-complex mechanism.

  16. Studies of oxygen species in synthetic Todorokite-like manganese oxide octahedral molecular sieves

    SciTech Connect

    Yin, Yuan-Gen; Xu, Wen-Qing; Shen, Yan-Fei; Suib, S.L. ); O'Young, C.L. )

    1994-10-01

    Manganese oxide octahedral molecular sieves of 3 x 3 tunnel structure (OMS-1) doped with various cations possess high thermal stability and were studied by means of temperature-programmed desorption and reduction by H[sub 2] and CO. Different oxygen species can be discerned according to their peak positions in the temperature-programmed desorption and reduction and assigned to chemisorbed dioxygen, oxygen atoms bound to Mn[sup 2+], and those bound to Mn[sup 4+] ions in the framework. Differences in peak positions and availabilities of these species during TPD and TPR can be explained by creation of nascent Mn[sup 2+] ions during TPR. The effects of doping cations on the reactivity and availability of these oxygen species are demonstrated to be more pronounced in TPR in H[sub 2] or CO than in TPD. In some instances, the trends of changes in reactivity and availability of the oxygen species due to doping of Cu[sup 2+], Ni[sup 2+], Zn[sup 2+], and Mg[sup 2+] correlated with the changes in the heat of formation of oxides of these cations. Temperature-programmed reactions with methane show some reactivity of these doped OMS-1 materials. Pulse reactions with CO show higher reactivity of Cu-doped OM-1 than with butane. However, the recovery of Cu-doped OMS-1 by reoxidation with oxygen pulses seems rather incomplete at the same temperature. 27 refs., 9 figs.

  17. Lipopeptide-Coated Iron Oxide Nanoparticles as Potential Glycoconjugate-Based Synthetic Anticancer Vaccines.

    PubMed

    Sungsuwan, Suttipun; Yin, Zhaojun; Huang, Xuefei

    2015-08-12

    Although iron oxide magnetic nanoparticles (NPs) have been widely utilized in molecular imaging and drug delivery studies, they have not been evaluated as carriers for glycoconjugate-based anticancer vaccines. Tumor-associated carbohydrate antigens (TACAs) are attractive targets for the development of anticancer vaccines. Due to the weak immunogenicity of these antigens, it is highly challenging to elicit strong anti-TACA immune responses. With their high biocompatibilities and large surface areas, magnetic NPs were synthesized for TACA delivery. The magnetic NPs were coated with phospholipid-functionalized TACA glycopeptides through hydrophobic-hydrophobic interactions without the need for any covalent linkages. Multiple copies of glycopeptides were presented on NPs, potentially leading to enhanced interactions with antibody-secreting B cells through multivalent binding. Mice immunized with the NPs generated strong antibody responses, and the glycopeptide structures important for high antibody titers were identified. The antibodies produced were capable of recognizing both mouse and human tumor cells expressing the glycopeptide, resulting in tumor cell death through complement-mediated cytotoxicities. These results demonstrate that magnetic NPs can be a new and simple platform for multivalently displaying TACA and boosting anti-TACA immune responses without the need for a typical protein carrier. PMID:26200668

  18. Catalytic wet oxidation of the pretreated synthetic pulp and paper mill effluent under moderate conditions.

    PubMed

    Garg, Anurag; Mishra, I M; Chand, Shri

    2007-01-01

    In the present study, catalytic wet oxidation (CWO) was investigated for the destruction of organic pollutants in the thermally pretreated effluent from a pulp and paper mill under moderate temperature and pressure conditions. The thermal pretreatment studies were conducted at atmospheric pressure and 368K using copper sulfate as a catalyst. The thermal pretreatment reduced COD by about 61%. The filtrate of the thermal pretreatment step was used at pH 8.0 for CWO at 383-443K temperature and a total pressure of 0.85MPa for 4h. Catalysts used for the reaction include copper sulfate, 5% CuO/95% activated carbon, 60% CuO/40% MnO(2), and 60% CuO/40% CeO(2). Maximum COD reduction was found to be 89% during CWO step using 5% CuO/95% activated carbon with a catalyst loading of 8gl(-1) at 443K and 0.85MPa total pressure. Overall COD reduction for the pretreatment and the CWO was found to be 96%. Besides this, 60% CuO/40% CeO(2) catalyst also exhibited the similar activity as that of obtained with 5% CuO/95% activated carbon catalyst at 423K temperature and 0.85MPa total pressure. The pH of the solution during the experimental runs decreases initially due to the formation of carboxylic acid and then increases due to the decomposition of acids. PMID:16934854

  19. Oxidative transformation of natural and synthetic phenolic mixtures by Trametes versicolor laccase.

    PubMed

    Canfora, Loredana; Iamarino, Giuseppina; Rao, Maria Antonietta; Gianfreda, Liliana

    2008-02-27

    The efficiency of Trametes versicolor laccase in the transformation of phenols (caffeic acid, catechol, hydroxytyrosol, methylcatechol, protocatechuic acid, syringic acid, m-tyrosol, 3-hydroxybenzoic acid, 3-hydroxyphenylacetic acid, 2,6-dihydroxybenzoic acid, 4-hydroxybenzaldehyde) usually present in waste water, such as that derived from an olive oil factory, was investigated. According to their response to 24 h laccase action the 11 phenolic compounds were classified in three groups: reactive (88-100% transformation), intermediate reactive (transformation lower than 50%), and recalcitrant (not transformed at all). The enzyme was able to transform the 11 substrates even when they were present in a mixture and also toward a phenolic extract from a Moroccan olive oil mill waste water (OMW) sample. The disappearance of protocatechuic, 3-hydroxyphenylacetic, and 2,6-dihydroxybenzoic acids, and 4-hydroxybenzaldehyde was enhanced whereas that of caffeic acid and m-tyrosol was depressed when the phenols were present in the mixture. A reduction of enzyme activity occurred in single and/or complex phenolic mixtures after enzymatic oxidation. No correspondence between phenol transformation and disappearance of enzymatic activity was, however, observed. The overall results suggest that laccases are effective in the transformation of simple and complex phenolic mixtures. PMID:18205305

  20. Quinazolinones, Quinazolinthiones, and Quinazolinimines as Nitric Oxide Synthase Inhibitors: Synthetic Study and Biological Evaluation.

    PubMed

    Camacho, M Encarnación; Chayah, Mariem; García, M Esther; Fernández-Sáez, Nerea; Arias, Fabio; Gallo, Miguel A; Carrión, M Dora

    2016-08-01

    The synthesis of different compounds with a quinazolinone, quinazolinthione, or quinazolinimine skeleton and their in vitro biological evaluation as inhibitors of inducible and neuronal nitric oxide synthase (iNOS and nNOS) isoforms are described. These derivatives were obtained from substituted 2-aminobenzylamines, using diverse cyclization procedures. Furthermore, the diamines were synthesized by two routes: A conventional pathway and an efficient one-pot synthesis in a continuous-flow hydrogenator. The structures of these heterocycles were confirmed by (1) H and (13) C nuclear magnetic resonance and high-resolution mass spectroscopy data. The structure-activity relationships of the target molecules are discussed in terms of the effects of both the R radical and the X heteroatom in the 2-position. In general, the assayed compounds behave as better iNOS than nNOS inhibitors, with the quinazolinone 11e being the most active inhibitor of all tested compounds and the most iNOS/nNOS selective one. PMID:27328401

  1. Synthetic heme/copper assemblies: toward an understanding of cytochrome c oxidase interactions with dioxygen and nitrogen oxides.

    PubMed

    Hematian, Shabnam; Garcia-Bosch, Isaac; Karlin, Kenneth D

    2015-08-18

    Our long-time niche in synthetic biological inorganic chemistry has been to design ligands and generate coordination complexes of copper or iron ions or both, those reacting with dioxygen (O2) or nitrogen oxides (e.g., nitric oxide (NO(g)) and nitrite (NO2(-))) or both. As inspiration for this work, we turn to mitochondrial cytochrome c oxidase, which is responsible for dioxygen consumption and is also the predominant target for NO(g) and nitrite within mitochondria. In this Account, we highlight recent advances in studying synthetic heme/Cu complexes in two respects. First, there is the design, synthesis, and characterization of new O2 adducts whose further study will add insights into O2 reductive cleavage chemistry. Second, we describe how related heme/Cu constructs reduce nitrite ion to NO(g) or the reverse, oxidize NO(g) to nitrite. The reactions of nitrogen oxides occur as part of CcO's function, which is intimately tied to cellular O2 balance. We had first discovered that reduced heme/Cu compounds react with O2 giving μ-oxo heme-Fe(III)-O-Cu(II)(L) products; their properties are discussed. The O-atom is derived from dioxygen, and interrogations of these systems led to the construction and characterization of three distinctive classes of heme-peroxo complexes, two high-spin and one low-spin species. Recent investigations include a new approach to the synthesis of low-spin heme-peroxo-Cu complexes, employing a "naked" synthon, where the copper ligand denticity and geometric types can be varied. The result is a collection of such complexes; spectroscopic and structural features (by DFT calculations) are described. Some of these compounds are reactive toward reductants/protons effecting subsequent O-O cleavage. This points to how subtle improvements in ligand environment lead to a desired local structure and resulting optimized reactivity, as known to occur at enzyme active sites. The other sector of research is focused on heme/Cu assemblies mediating the redox

  2. Synthetic Heme/Copper Assemblies: Toward an Understanding of Cytochrome c Oxidase Interactions with Dioxygen and Nitrogen Oxides

    PubMed Central

    Hematian, Shabnam; Garcia-Bosch, Isaac; Karlin, Kenneth D.

    2016-01-01

    Conspectus Our long-time niche in synthetic biological inorganic chemistry has been to design ligands and generate coordination complexes of copper and/or iron ions, those reacting with dioxygen (O2) and/or nitrogen oxides (e.g., nitric oxide (NO(g)) and nitrite (NO2−)). As inspiration for this work, we turn to mitochondrial cytochrome c oxidase which is responsible for dioxygen consumption and is also the predominant target for NO(g) and nitrite within mitochondria. In this Account, we highlight recent advances in studying synthetic heme/Cu complexes in two respects. First, there is the design, synthesis and characterization of new O2-adducts whose further study will add insights into O2-reductive cleavage chemistry. Second, we describe how related heme/Cu constructs reduce nitrite ion to NO(g) or the reverse, oxidize NO(g) to nitrite. The reactions of nitrogen oxides occur as part of CcO’s function, which is intimately tied to cellular O2-balance. We had first discovered that reduced heme/Cu compounds react with O2 giving μ-oxo heme-FeIII-O-CuII(L) products; their properties are discussed. The O-atom is derived from dioxygen and interrogations of these systems led to the construction and characterization of three distinctive classes of heme-peroxo-complexes, two high-spin and one low-spin species. Recent investigations include a new approach to the synthesis of low-spin heme-peroxo-Cu complexes, employing a “naked” synthon, where the copper ligand denticity and geometric types can be varied. The result is a collection of such complexes; spectroscopic and structural features (by DFT calculations) are described. Some of these compounds are reactive toward reductants/protons effecting subsequent O-O cleavage. This points to how subtle improvements in ligand environment lead to a desired local structure and resulting optimized reactivity, as known to occur at enzyme active-sites. The other sector of research is focused on heme/Cu assemblies mediating the

  3. New Synthetic Triterpenoids: Potent Agents for Prevention and Treatment of Tissue Injury Caused by Inflammatory and Oxidative Stress

    PubMed Central

    2011-01-01

    We review the original rationale for the development and the chemistry of a series of new synthetic oleanane triterpenoids (SO), based on oleanolic acid (1) as a starting material. Many of the new compounds that have been made, such as 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid (“CDDO”, 8), are highly potent (activities found at levels below 1 nM) anti-inflammatory agents, as measured by their ability to block the cellular synthesis of the enzyme inducible nitric oxide synthase (iNOS) in activated macrophages. Details of the organic synthesis of new SO and their chemical mechanisms of biological activity are reviewed, as is formation of biotin conjugates for investigation of protein targets. Finally, we give a brief summary of important biological activities of SO in many organ systems in numerous animal models. Clinical investigation of a new SO (methyl 2-cyano-3,12-dioxooleana-1,9(11)dien-28-oate, “CDDO-Me”, bardoxolone methyl, 13) is currently in progress. PMID:21309592

  4. Comparison between Ag (I) and Ni (II) removal from synthetic nuclear power plant coolant water by iron oxide nanoparticles

    PubMed Central

    2013-01-01

    The impact of effective parameters such as iron oxide nanoparticles dosage, contact time and solution pH was optimized for removal of Ag(I) and Ni(II) in the nuclear cooling system and the best conditions were compared. Nearly complete removal (97%) of Ni(II) and Ag(I) were obtained at adsorbent dosage of 40 and 20 g/L, respectively. Experiments showed that 4 hours was a good choice as optimum contact time for two ions removal. The effective parameter was pH, so that maximum removal efficiency was obtained for Ag(I) in acidic pH=3 and for Ni(II) in basic pH=10. It seems that removal of Ag(I) was controlled by adsorption-reduction mechanism, but Ni(II) could place only adsorption. Langmuir and Freundlich model was more suitable for nickel and silver removal by this adsorbent, respectively. Ag(I) and Ni(II) removal efficiency trend by this adsorbent is similar at periods but different in the concentrations, pHs and equilibrium model. The obtained results were very promising, as both Ag(I) and Ni(II) were effectively removed from synthetic wastewater and there was a possibility to remove Ag(I) very fast. Hence, the idea of using nanoparticles for application of metal ions removal from wastewaters seems to be very efficient and quite promising. PMID:24499654

  5. EXPEDITIOUS SYNTHETIC TRANSFORMATIONS USING MICROWAVES

    EPA Science Inventory

    Microwave-expedited solvent-free synthetic processes will be described for the synthesis of a variety of industrially significant compounds and intermediates namely, enamines, nitroalkenes, enones, oxidized sulfur compounds and ionic liquids. This solvent-free synthetic methodolo...

  6. Incorporation of Hydrogen Bonding Functionalities into the Second Coordination Sphere of Iron-Based Water Oxidation Catalysts

    SciTech Connect

    Hoffert, Wesley A.; Mock, Michael T.; Appel, Aaron M.; Yang, Jenny Y.

    2013-08-06

    Energy storage and conversion schemes based on environmentally benign chemical fuels will require the discovery of faster, cheaper, and more robust catalysts for the oxygen evolution reaction (OER). Although pendant bases have led to enhanced turnover frequencies with non-aqueous substrates, their effect on the catalytic behavior of molecular water oxidation catalysts has received little attention. Herein, the syntheses, structures, and catalytic activities of new iron complexes with pendant bases are reported. Of these, the complex [Fe(mepydz)4(CH3CN)2](OTf)2 (mepydz = N,N'-dimethyl-N,N'-bis(pyridazin-3-ylmethyl)ethane-1,2-diamine, OTf = trifluoromethanesulonate) (8(CH3CN)22+) is the most active catalyst. Initial turnover frequencies of 141 h-1 and 24 h-1 were measured using ceric ammonium nitrate at pH 0.7 and sodium periodate at pH 4.7, respectively. At pH 4.7, 8(CH3CN)22+ the initial turnover frequency is 70% faster than the structurally analogous complex without ancillary proton relays. These results demonstrate that the incorporation of pendant bases into molecular water oxidation catalysts is a synthetic principle that should be considered in the development of new OER catalysts. This work was supported by Laboratory Directed Research and Development program at Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for the US Department of Energy.

  7. Simultaneous Determination of 6-Mercaptopurine and its Oxidative Metabolites in Synthetic Solutions and Human Plasma using Spectrophotometric Multivariate Calibration Methods

    PubMed Central

    Sorouraddin, Mohammad-Hossein; Khani, Mohammad-Yaser; Amini, Kaveh; Naseri, Abdolhossein; Asgari, Davoud; Rashidi, Mohammad-Reza

    2011-01-01

    Introduction 6-Mercaptopurine (6MP) is an important chemotherapeutic drug in the conventional treatment of childhood acute lymphoblastic leukemia (ALL). It is catabolized to 6-thiouric acid (6TUA) through 8-hydroxo-6-mercaptopurine (8OH6MP) or 6-thioxanthine (6TX) intermediates. Methods High-performance liquid chromatography (HPLC) is usually used to determine the contents of therapeutic drugs, metabolites and other important biomedical analytes in biological samples. In the present study, the multivariate calibration methods, partial least squares (PLS-1) and principle component regression (PCR) have been developed and validated for the simultaneous determination of 6MP and its oxidative metabolites (6TUA, 8OH6MP and 6TX) without analyte separation in spiked human plasma. Mixtures of 6MP, 8-8OH6MP, 6TX and 6TUA have been resolved by PLS-1 and PCR to their UV spectra. Results Recoveries (%) obtained for 6MP, 8-8OH6MP, 6TX and 6TUA were 94.5-97.5, 96.6-103.3, 95.1-96.9 and 93.4-95.8, respectively, using PLS-1 and 96.7-101.3, 96.2-98.8, 95.8-103.3 and 94.3-106.1, respectively, using PCR. The NAS (Net analyte signal) concept was used to calculate multivariate analytical figures of merit such as limit of detection (LOD), selectivity and sensitivity. The limit of detections for 6MP, 8-8OH6MP, 6TX and 6TUA were calculated to be 0.734, 0.439, 0.797 and 0.482 μmol L-1, respectively, using PLS and 0.724, 0.418, 0783 and 0.535 μmol L-1, respectively, using PCR. HPLC was also applied as a validation method for simultaneous determination of these thiopurines in the synthetic solutions and human plasma. Conclusion Combination of spectroscopic techniques and chemometric methods (PLS and PCR) has provided a simple but powerful method for simultaneous analysis of multicomponent mixtures PMID:23678408

  8. Oxidative degradation of cholesteryl esters in low-density lipoproteins: analysis by liquid chromatography-light scattering and protection by a new synthetic antioxidant, S20478.

    PubMed

    Arborati, M; Benchorba, D; Lesieur, I; Bizot-Espiard, J G; Guardiola-Lemaitre, B; Chapman, M J; Ninio, E

    1997-01-01

    Cholesteryl esters in the hydrophobic core of low-density lipoprotein (LDL) particles constitute a major molecular target during copper-mediated oxidation. To facilitate the rapid analysis and quantitation of the oxidative degradation of LDL cholesteryl esters, we describe a new approach based on light scattering detection following separation by HPLC. We have applied this approach to the evaluation of the protective capacity of a new synthetic antioxidant, S20478, during oxidation of LDL in the presence of copper ions. HPLC separation of cholesterol and the four major molecular species of cholesteryl esters (C16:0, C18:1, C18:2 and C20:4) of LDL was achieved in a single run of 20 min with high sensitivity (50 ng) and low background. Time course studies of the oxidative modification of LDL (ratio LDL protein: copper, 100 micrograms/mL: 1 microM) revealed that the content of unsaturated cholesteryl esters (C20:4 and C18:2) decreased (-30% and -15%, respectively) within 90 min of copper-mediated oxidation, while only minor degradation (up to 15%) of monounsaturated (C18:1) and saturated (C16:0) esters occurred. At 24 hours of oxidation, only traces (< 5%) of the C20:4 and C18:2 esters were detectable; whereas 52% of the C18:1 ester remained (P < 0.01). Of the saturated esters, only minor proportions (35% or less) underwent oxidative modification. In addition, some 81% of free cholesterol was conserved as the native sterol. The synthetic antioxidant, S20478 (50 microM) was capable of inhibiting the initiation and the propagation of copper-mediated LDL oxidation as determined by the time- and dose-dependent inhibition of the formation of conjugated dienes and thiobarbituric acid-reactive substances, as well as the conservation of the net electrical charge of LDL; indeed S20478 conserved cholesteryl esters in their native form up to 24 hours. However, after prolonged exposure to copper ions (48 hours), only 47% of the unsaturated esters remained (C18:2, P < 0

  9. Cr(VI) removal from synthetic wastewater using coconut shell charcoal and commercial activated carbon modified with oxidizing agents and/or chitosan.

    PubMed

    Babel, Sandhya; Kurniawan, Tonni Agustiono

    2004-02-01

    In this study, the technical feasibility of coconut shell charcoal (CSC) and commercial activated carbon (CAC) for Cr(VI) removal is investigated in batch studies using synthetic electroplating wastewater. Both granular adsorbents are made up of coconut shell (Cocos nucifera L.), an agricultural waste from local coconut industries. Surface modifications of CSC and CAC with chitosan and/or oxidizing agents, such as sulfuric acid and nitric acid, respectively, are also conducted to improve removal performance. The results of their Cr removal performances are statistically compared. It is evident that adsorbents chemically modified with an oxidizing agent demonstrate better Cr(VI) removal capabilities than as-received adsorbents in terms of adsorption rate. Both CSC and CAC, which have been oxidized with nitric acid, have higher Cr adsorption capacities (CSC: 10.88, CAC: 15.47 mg g(-1)) than those oxidized with sulfuric acid (CSC: 4.05, CAC: 8.94 mg g(-1)) and non-treated CSC coated with chitosan (CSCCC: 3.65 mg g(-1)), respectively, suggesting that surface modification of a carbon adsorbent with a strong oxidizing agent generates more adsorption sites on their solid surface for metal adsorption. PMID:14637353

  10. Anabaena sp. mediated bio-oxidation of arsenite to arsenate in synthetic arsenic (III) solution: Process optimization by response surface methodology.

    PubMed

    Jana, Animesh; Bhattacharya, Priyankari; Swarnakar, Snehasikta; Majumdar, Swachchha; Ghosh, Sourja

    2015-11-01

    Blue green algae Anabaena sp. was cultivated in synthetic arsenite solution to investigate its bio-oxidation potential for arsenic species. Response surface methodology (RSM) was employed based on a 3-level full factorial design considering four factors, viz. initial arsenic (III) concentration, algal dose, temperature and time. Bio-oxidation (%) of arsenic (III) was considered as response for the design. The study revealed that about 100% conversion of As (III) to As (V) was obtained for initial As (III) concentration of 2.5-7.5 mg/L at 30 °C for 72 h of exposure using 3 g/L of algal dose signifying a unique bio-oxidation potential of Anabaena sp. The dissolved CO2 (DCO2) and oxygen (DO) concentration in solution was monitored during the process and based on the data, a probable mechanism was proposed wherein algal cell acts like a catalytic membrane surface and expedites the bio-oxidation process. Bioaccumulation of arsenic, as well as, surface adsorption on algal cell was found considerably low. Lipid content of algal biomass grown in arsenite solution was found slightly lower than that of algae grown in synthetic media. Toxicity effects on algal cells due to arsenic exposure were evaluated in terms of comet assay and chlorophyll a content which indicated DNA damage to some extent along with very little decrease in chlorophyll a content. In summary, the present study explored the potential application of Anabaena sp. as an ecofriendly and sustainable option for detoxification of arsenic contaminated natural water with value-added product generation. PMID:26247411

  11. Insights into the mechanistic and synthetic aspects of the Mo/P-catalyzed oxidation of N-heterocycles†

    PubMed Central

    Stephens, David; Mfuh, Adelphe M.; Arman, Hadi D.; Naumova, Anastasia S.; Chavez, Gabriel; Skenderi, Behije

    2014-01-01

    A Mo/P catalytic system for an efficient gram-scale oxidation of a variety of nitrogen heterocycles to N-oxides with hydrogen peroxide as terminal oxidant has been investigated. Combined spectroscopic and crystallographic studies point to the tetranuclear Mo4P peroxo complex as one of the active catalytic species present in the solution. Based on this finding an optimized catalytic system has been developed. The utility and chemoselectivity of the catalytic system has been demonstrated by the synthesis of over 20 heterocyclic N-oxides. PMID:24643619

  12. Insights into the mechanistic and synthetic aspects of the Mo/P-catalyzed oxidation of N-heterocycles.

    PubMed

    Larionov, Oleg V; Stephens, David; Mfuh, Adelphe M; Arman, Hadi D; Naumova, Anastasia S; Chavez, Gabriel; Skenderi, Behije

    2014-05-21

    A Mo/P catalytic system for an efficient gram-scale oxidation of a variety of nitrogen heterocycles to N-oxides with hydrogen peroxide as terminal oxidant has been investigated. Combined spectroscopic and crystallographic studies point to the tetranuclear Mo4P peroxo complex as one of the active catalytic species present in the solution. Based on this finding an optimized catalytic system has been developed. The utility and chemoselectivity of the catalytic system has been demonstrated by the synthesis of over 20 heterocyclic N-oxides. PMID:24643619

  13. Metal-Free, Visible Light-Photocatalyzed Synthesis of Benzo[b]phosphole Oxides: Synthetic and Mechanistic Investigations.

    PubMed

    Quint, Valentin; Morlet-Savary, Fabrice; Lohier, Jean-François; Lalevée, Jacques; Gaumont, Annie-Claude; Lakhdar, Sami

    2016-06-15

    Highly functionalized benzo[b]phosphole oxides were synthesized from reactions of arylphosphine oxides with alkynes under photocatalytic conditions by using eosin Y as the catalyst and N-ethoxy-2-methylpyridinium tetrafluoroborate as the oxidant. The reaction works under mild conditions and has a broad substrate scope. Mechanistic investigations have been undertaken and revealed the formation of a ground state electron donor-acceptor complex (EDA) between eosin (the photocatalyst) and the pyridinium salt (the oxidation agent). This complex, which has been fully characterized both in the solid state and in solution, turned out to exhibit a dual role, i.e., the oxidation of the photocatalyst and the formation of the initiating radicals, which undergoes an intramolecular reaction avoiding the classical diffusion between the two reactants. The involvement of ethoxy and phosphinoyl radicals in the photoreaction has unequivocally been evidenced by EPR spectroscopy. PMID:27186629

  14. Sequential oxidations of thiolates and the cobalt metallocenter in a synthetic metallopeptide: Implications for the biosynthesis of nitrile hydratase

    PubMed Central

    Dutta, Arnab; Flores, Marco; Roy, Souvik; Schmitt, Jennifer C.; Hamilton, G. Alexander; Hartnett, Hilairy E.; Shearer, Jason; Jones, Anne K.

    2013-01-01

    Cobalt nitrile hydratases (Co-NHase) contain a catalytic cobalt (III) ion coordinated in an N2S3 first coordination sphere comprised of two amidate nitrogens and three cysteine-derived sulfur donors: a thiolate (-SR), a sulfenate (-S(R)O−), and a sulfinate (-S(R)O2−). The sequence of biosynthetic reactions that leads to the post-translational oxidations of the metal and the sulfur ligands is unknown, but the process is believed to be initiated directly by oxygen. Herein we utilize cobalt bound in an N2S2 first coordination sphere by a seven amino acid peptide known as SODA (ACDLPCG) to model this oxidation process. Upon exposure to oxygen, Co-SODA is oxidized in two steps. In the first fast step (seconds), magnetic susceptibility measurements demonstrated that the metallocenter remains paramagnetic, i.e. Co2+, and sulfur K-edge X-ray absorption spectroscopy (XAS) is used to show that one of the thiolates is oxidized to sulfinate. In a second process on a longer timescale (hours), magnetic susceptibility measurements and Co K-edge XAS show that the metal is oxidized to Co3+. Unlike other model complexes, additional slow oxidation of the second thiolate in Co-SODA is not observed, and a catalytically active complex is never formed. The likely reason is the absence of the axial thiolate ligand. In essence, the reactivity of Co-SODA can be described as intermediate between previously described models which either quickly convert to final product or are stable in air, and it offers a first glimpse into a possible oxidation pathway for nitrile hydratase biosynthesis. PMID:23587023

  15. Adsorption of fluoride on synthetic iron (III), zirconium(IV) and binary iron(III)-zirconium (IV) oxides: comparative assessment on pH effect and isotherm.

    PubMed

    Biswas, Krishna; Bandhopadhyay, Durjoy; Ghosh, Uday Chand

    2008-04-01

    Fluoride is an accumulative poison at high dose of intake for humans and animals. In the present study, the sorption of fluoride from aqueous solution has been investigated on synthetic hydrous ferric oxide (HFO), hydrous zirconium oxide (HZO) and hydrous zirconium(IV)-iron(III) oxide (HZFO) by batch mode experiments. Both HFO and HZFO were crystalline and HZO was amorphous in nature. The parametes studied were the effect of pH and sorption equilibriums. The results showed increase in fluoride-sorption with increasing pH from nearly 2.0 to 5.0, 4.6 and 6.8 for HFO, HZO and HZFO, respectively. Analysis of temperature dependent sorption data obtained at equilibrium solution pH 6.8 (+/- 0.2) has been described by the Langmuir, Freundlich, Temkin and Redlich-Peterson isotherm model equations. The present sorption data fit, in general, found very well with the Langmuir and Redlich-Peterson models; and the data fit for HZFO and HFO found to increase, but for HZO the data found to decrease with increasing temperature. The computed thermodynamic parameters such as deltaG0, delltaH0 and deltaS0 from the Langmuir equilibrium constant (b, L/Umg) values show that the fluoride-sorption on HZFO was more spontaneous and endothermic process compared to HFO. The deltaH0 value obtained for fluoride adsorption on HZO indicates exothermic nature. PMID:19295101

  16. Great advantages in using a natural rubber instead of a synthetic SBR in a pro-oxidant system for degradable LDPE.

    PubMed

    Khabbaz, F; Albertsson, A C

    2000-01-01

    Different pro-oxidant systems are used in degradable low-density polyethylene (LDPE). The main question is the degradation products and not the degradation time from the used materials. The pro-oxidant formulation used consisted of manganese stearate and natural rubber (NR) or manganese stearate and a synthetic, styrene-butadiene copolymer rubber (SBR). The samples were heated in air at 100 degrees C in sealed glass vials. The molecular weight changes were measured by size exclusion chromatography (SEC). The volatile and nonvolatile degradation products have been identified by gas chromatography-mass spectrometry (GC/MS). A wide variety of degradation products were identified, including ketones, carboxylic acids, keto acids, dicarboxylic acids, and furanones as a homologous series. Benzaldehyde, acetophenone, benzoic acid, benzyl benzoate, and two benzene derivative compounds were identified only in the LDPE-SBR system. These aromatic compounds originate from the styrene part of SBR. The advantages using pro-oxidant containing NR are more effective degradation of LDPE without any aromatic degradation products. PMID:11710197

  17. Synthetic fuels

    SciTech Connect

    Sammons, V.O.

    1980-01-01

    This guide is designed for those who wish to learn more about the science and technology of synthetic fuels by reviewing materials in the collections of the Library of Congress. This is not a comprehensive bibliography, it is designed to put the reader on target. Subject headings used by the Library of Congress under which books on synthetic fuels can be located are: oil-shale industry; oil-shales; shale oils; synthetic fuels; synthetic fuels industry; coal gasification; coal liquefaction; fossil fuels; hydrogen as fuel; oil sands; petroleum, synthesis gas; biomass energy; pyrolysis; and thermal oil recovery. Basic texts, handbooks, government publications, journals, etc. were included. (DP)

  18. Fe hydroxyphosphate precipitation and Fe(II) oxidation kinetics upon aeration of Fe(II) and phosphate-containing synthetic and natural solutions

    NASA Astrophysics Data System (ADS)

    van der Grift, B.; Behrends, T.; Osté, L. A.; Schot, P. P.; Wassen, M. J.; Griffioen, J.

    2016-08-01

    Exfiltration of anoxic Fe-rich groundwater into surface water and the concomitant oxidative precipitation of Fe are important processes controlling the transport of phosphate (PO4) from agricultural areas to aquatic systems. Here, we explored the relationship between solution composition, reaction kinetics, and the characteristics of the produced Fe hydroxyphosphate precipitates in a series of aeration experiments with anoxic synthetic water and natural groundwater. A pH stat device was used to maintain constant pH and to record the H+ production during Fe(II) oxidation in the aeration experiments in which the initial aqueous P/Fe ratios ((P/Fe)ini), oxygen concentration and pH were varied. In general, Fe(II) oxidation proceeded slower in the presence of PO4 but the decrease of the PO4 concentration during Fe(II) oxidation due to the formation of Fe hydroxyphosphates caused additional deceleration of the reaction rate. The progress of the reaction could be described using a pseudo-second-order rate law with first-order dependencies on PO4 and Fe(II) concentrations. After PO4 depletion, the Fe(II) oxidation rates increased again and the kinetics followed a pseudo-first-order rate law. The first-order rate constants after PO4 depletion, however, were lower compared to the Fe(II) oxidation in a PO4-free solution. Hence, the initially formed Fe hydroxyphosphates also affect the kinetics of continuing Fe(II) oxidation after PO4 depletion. Presence of aqueous PO4 during oxidation of Fe(II) led to the formation of Fe hydroxyphosphates. The P/Fe ratios of the precipitates ((P/Fe)ppt) and the recorded ratio of H+ production over decrease in dissolved Fe(II) did not change detectably throughout the reaction despite a changing P/Fe ratio in the solution. When (P/Fe)ini was 0.9, precipitates with a (P/Fe)ppt ratio of about 0.6 were formed. In experiments with (P/Fe)ini ratios below 0.6, the (P/Fe)ppt decreased with decreasing (P/Fe)ini and pH value. Aeration experiments with

  19. Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) of low molecular weight organic compounds and synthetic polymers using zinc oxide (ZnO) nanoparticles.

    PubMed

    Watanabe, Takehiro; Kawasaki, Hideya; Yonezawa, Tetsu; Arakawa, Ryuichi

    2008-08-01

    We have developed surface-assisted laser desorption/ionization mass spectrometry using zinc oxide (ZnO) nanoparticles with anisotropic shapes (ZnO-SALDI-MS). The mass spectra showed low background noises in the low m/z, i.e. less than 500 u region. Thus, we succeeded in SALDI ionization on low molecular weight organic compounds, such as verapamil hydrochloride, testosterone, and polypropylene glycol (PPG) (average molecular weight 400) without using a liquid matrix or buffers such as citric acids. In addition, we found that ZnO-SALDI has advantages in post-source decay (PSD) analysis and produced a simple mass spectrum for phospholipids. The ZnO-SALDI spectra for synthetic polymers of polyethylene glycol (PEG), polystyrene (PS) and polymethylmethacrylate (PMMA) showed the sensitivity and molecular weight distribution to be comparable to matrix-assisted laser desorption/ionization (MALDI) spectra with a 2,5-dihydroxybenzoic acid (DHB) matrix. ZnO-SALDI shows good performance for synthetic polymers as well as low molecular weight organic compounds. PMID:18286665

  20. Improving the drug delivery characteristics of graphene oxide based polymer nanocomposites through the "one-pot" synthetic approach of single-electron-transfer living radical polymerization

    NASA Astrophysics Data System (ADS)

    Gao, Peng; Liu, Meiying; Tian, Jianwen; Deng, Fengjie; Wang, Ke; Xu, Dazhuang; Liu, Liangji; Zhang, Xiaoyong; Wei, Yen

    2016-08-01

    Graphene oxide (GO) based polymer nanocomposites have attracted extensive research interest recently for their outstanding physicochemical properties and potential applications. However, surface modification of GO with synthetic polymers has demonstrated to be trouble for most polymerization procedures are occurred under non-aqueous solution, which will in turn lead to the restacking of GO. In this work, a facile and efficient "one-pot" strategy has been developed for surface modification of GO with synthetic polymers through single-electron-transfer living radical polymerization (SET-LRP). The GO based polymer nanocomposites were obtained via SET-LRP in aqueous solution using poly(ethylene glycol) methyl ether methacrylate (PEGMA) as the monomer and 11-bromoundecanoic acid as the initiator, which could be effectively adsorbed on GO through hydrophobic interaction. The successful preparation of GO based polymer nanocomposites was confirmed by a series of characterization techniques such as 1H nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. The resultant products exhibit high water disperisibility, excellent biocompatibility and high efficient drug loading capability, making these PEGylated GO nanocomposites promising candidates for biomedical applications.

  1. Adsorption and regenerative oxidation of trichlorophenol with synthetic zeolite: Ozone dosage and its influence on adsorption performance.

    PubMed

    Zhang, Yongjun; Prigent, Bastien; Geißen, Sven-Uwe

    2016-07-01

    Regeneration of loaded adsorbents is a key step for the sustainability of an adsorption process. In this study, ozone was applied to regenerate a synthetic zeolite for the adsorption of trichlorophenol (TCP) as an organic model pollutant. Three initial concentrations of TCP in water phase were used in adsorption tests. After the equilibrium, zeolite loaded different amounts of TCP was dried and then regenerated with ozone gas. It was found that the adsorption capacity of zeolite was increased through three regeneration cycles. However, the adsorption kinetics was compromised after the regeneration with slightly declined 2nd order reaction constants. The ozone demand for the regeneration was highly dependent on the TCP mass loaded onto the zeolite. It was estimated that the mass ratio of ozone to TCP was 1.2 ± 0.3 g O3/g TCP. PMID:27043379

  2. Effect Of Inorganic, Synthetic And Naturally Occurring Chelating Agents On Fe(II) Mediated Advanced Oxidation Of Chlorophenols

    EPA Science Inventory

    This study examines the feasibility and application of Advanced Oxidation Technologies (AOTs) for the treatment of chlorophenols that are included in US EPA priority pollutant list. A novel class of sulfate/hydroxyl radical-based homogeneous AOTs (Fe(II)/PS, Fe(II)/PMS, Fe(II)/H...

  3. The effect of site geometry, Ti content and Ti oxidation state on the Ti K-edge XANES spectrum of synthetic hibonite

    NASA Astrophysics Data System (ADS)

    Doyle, P. M.; Berry, A. J.; Schofield, P. F.; Mosselmans, J. F. W.

    2016-08-01

    The Al-rich oxide hibonite (CaAl12O19) is modeled to be the second mineral to condense from a gas of solar composition and is found within calcium-aluminum-rich inclusions and the matrix of chondritic meteorites. Both Ti3+ and Ti4+ are reported in meteoritic hibonite, so hibonite has been proposed as a single mineral oxybarometer that could be used to elucidate conditions within the first 0.2 Myrs of the Solar System. Synthetic hibonites with Ti3+/(Ti3+ + Ti4+) (hereafter Ti3+/ΣTi) ranging between 0 and 1 were prepared as matrix-matched standards for meteoritic hibonite. The largest yield of both Ti-free and Ti-bearing hibonite at ∼1300 and ∼1400 °C was obtained by a single sinter under reducing conditions. In situ micro-beam Ti K-edge X-ray absorption near edge structure (XANES) spectra were recorded from the synthetic hibonites, as well as from terrestrial hibonite. Spectral features in the post-crest region were shown to correlate with the Ti4+ content. Furthermore, Ti4+ on the M2 trigonal bipyramidal and the adjoining M4 octahedral sites appears to cause variability in the post-crest region as a function of orientation. For this suite of synthetic hibonites it was observed that the pre-edge peak region is not influenced by orientation, but is controlled by Ti3+/ΣTi, site geometry and/or Ti concentration. In particular, the pre-edge peak intensities reflect Ti coordination environment and distortion of the M4 octahedral site. Therefore, although pre-edge peak intensities have previously been used to determine Ti3+/ΣTi in meteoritic minerals, we excluded use of the pre-edge peak intensities for quantifying Ti valence states in hibonite. The energy of the absorption edge at a normalized intensity of 0.8 (E0.8) and the energy of the minimum between the pre-edge region and the absorption edge (Em1) were found to vary systematically with Ti3+/ΣTi. Ti3+/ΣTi in hibonite as a function of Em1 was modeled by a quadratic function that may be used to quantify Ti3

  4. Selective dissolution of magnetic iron oxides in the acid-ammonium oxalate/ferrous iron extraction method-I. Synthetic samples

    NASA Astrophysics Data System (ADS)

    van Oorschot, Ingeborg H. M.; Dekkers, Mark J.

    2001-06-01

    In soil magnetism, the magnetic parameters alone are not always sufficient to distinguish the lithogenic from the pedogenic magnetic fractions. Sequential extraction techniques have therefore been incorporated into magnetic studies to constrain the environmental interpretation. Here we report on the dissolution behaviour of magnetite and maghemite in the acid-ammonium oxalate method to see whether the method is suitable for specific dissolution of magnetic minerals from soils and sediments. To prevent changes in the extraction mechanism during the experiments (see Appendix A), we used an adapted version of the acid-ammonium oxalate (AAO) method, in which Fe2+ is added to the extraction solution prior to the experiment [the AAO-Fe(II) method]. The procedure was divided into several 30min extraction steps to check the dissolution progress. Synthetic samples containing a quartz matrix with 0.1wt per cent of iron oxides were extracted with the AAO-Fe(II) method. The iron oxides consisted of either magnetite or maghemite with grain sizes of <0.5µm (fine grained or SD/PSD) and <5µm (coarse grained or MD/PSD), or a 1:1 mixture of both minerals. Because only magnetite and maghemite were studied, the changes in magnetic characteristics could be monitored after each extraction step by analysis of the bulk susceptibility and hysteresis parameters measured at room temperature. The AAO-Fe(II) method preferentially dissolved the smaller iron oxides from the samples. For samples containing iron oxides with coarse grain size there is a preference for dissolving maghemite rather than magnetite. Extractions of the samples containing mixtures of two different grain sizes or with different mineralogy show that the method preferentially dissolves the smaller grains before attacking the coarse grains in the sample.

  5. Synthetic and Predictive Approach to Unsymmetrical Biphenols by Iron-Catalyzed Chelated Radical-Anion Oxidative Coupling.

    PubMed

    Libman, Anna; Shalit, Hadas; Vainer, Yulia; Narute, Sachin; Kozuch, Sebastian; Pappo, Doron

    2015-09-01

    An iron-catalyzed oxidative unsymmetrical biphenol coupling in 1,1,1,3,3,3-hexafluoropropan-2-ol that proceeds via a chelated radical-anion coupling mechanism was developed. Based on mechanistic studies, electrochemical methods, and density functional theory calculations, we suggest a general model that enables prediction of the feasibility of cross-coupling for a given pair of phenols. PMID:26287435

  6. Encapsulated Laccases for the Room-Temperature Oxidation of Aromatics: Towards Synthetic Low-Molecular-Weight Lignins.

    PubMed

    Pistone, Lucia; Ottolina, Gianluca; De, Sudipta; Romero, Antonio A; Martins, Lígia O; Luque, Rafael

    2016-04-01

    A new approach for the encapsulation of laccases with enhanced activity and stability by biomimetic silica mineralisation is reported. A range of lignin model compounds, which includes syringol, syringyl acid, 4-vinylphenol, gallic acid, vanillic acid and guaiacol, was oxidised to lignin-type polymers by the silica-immobilised laccase systems at room temperature. The oxidation rate of the immobilised systems was lower than that of the free enzyme counterparts, but interesting products were observed with the new bio-catalytic materials, which showed reusability and good stability. PMID:26898517

  7. New sol-gel synthetic route to transition and main-group metal oxide aerogels using inorganic salt precursors

    SciTech Connect

    Gash, A E; Tillotson, T M; Satcher Jr, J H; Hrubesh, L W; Simpson, R L

    2000-09-12

    We have developed a new sol-gel route to synthesize several transition and main-group metal oxide aerogels. The approach is straightforward, inexpensive, versatile, and it produces monolithic microporous materials with high surface areas. Specifically, we report the use of epoxides as gelation agents for the sol-gel synthesis of chromia aerogels and xerogels from simple Cr(III) inorganic salts. The dependence of both gel formation and its rate was studied by varying the solvent used, the Cr(III) precursor salt, the epoxide/Cr(III) ratio, as well as the type of epoxide employed. All of these variables were shown to affect the rate of gel formation and provide a convenient control of this parameter. Dried chromia aerogels were characterized by high-resolution transmission electron microscopy (HRTEM) and nitrogen adsorption/desorption analyses, results of which will be presented. Our studies have shown that rigid monolithic gels can be prepared from many different metal ions salts, provided the formal oxidation state of the metal ion is greater than or equal to +3. Conversely, when di-valent transition metal salts are used precipitated solids are the products.

  8. Intra- and interparticle magnetism of cobalt-doped iron-oxide nanoparticles encapsulated in a synthetic ferritin cage

    NASA Astrophysics Data System (ADS)

    Skoropata, E.; Desautels, R. D.; Falvo, E.; Ceci, P.; Kasyutich, O.; Freeland, J. W.; van Lierop, J.

    2014-11-01

    We present an in-depth examination of the composition and magnetism of cobalt (Co2 +)-doped iron-oxide nanoparticles encapsulated in Pyrococcus furiosus ferritin shells. We show that the Co2 + dopant ions were incorporated into the γ -Fe2O3/Fe3O4 core, with small paramagnetic-like clusters likely residing on the surface of the nanoparticle that were observed for all cobalt-doped samples. In addition, element-specific characterization using Mössbauer spectroscopy and polarized x-ray absorption indicated that Co2 + was incorporated exclusively into the octahedral B sites of the spinel-oxide nanoparticle. Comparable superparamagnetic blocking temperatures, coercivities, and effective anisotropies were obtained for 7%, 10%, and 12% cobalt-doped nanoparticles, and were only slightly reduced for 3% cobalt, indicating a strong effect of cobalt incorporation, with a lesser effect of cobalt content. Due to the regular particle size and separation that result from the use of the ferritin cage, a comparison of the effects of interparticle interactions on the disordered assembly of nanoparticles was also obtained that indicated significantly different behaviors between undoped and cobalt-doped nanoparticles.

  9. Cesium and cobalt adsorption on synthetic nano manganese oxide: A two dimensional infra-red correlation spectroscopic investigation

    NASA Astrophysics Data System (ADS)

    Al Lafi, Abdul G.; Al Abdullah, Jamal

    2015-08-01

    Molecular scale information is of prime importance to understand ions coordination to mineral surfaces and consequently to aid in the design of improved ion exchange materials. This paper reports on the use of two-dimensional correlation infra-red spectroscopy (2D-COS-IR) to investigate the time dependent adsorptions of cesium and cobalt ions onto nano manganese oxide (NMO). The metal ions uptake was driven mainly by inner-sphere complex formation as demonstrated by the production of new absorption bands at 1160, 1100, 585 and 525 cm-1, which were assigned to the O-O bond vibration and the coupled vibrations of M-O and Mn-O bonds. The progressive development of the 3100 cm-1 band, which is attributed to the stretching vibration of the lattice-OH group, indicates an M+/H+ ion-exchange reaction. The new bands at 700 and 755 cm-1 in the case of cobalt ion adsorption and at 800 and 810 cm-1 in the case of cesium ion adsorption, and the splitting of other bands at 1135 and 875 cm-1 indicate the presence of different O-O bond lengths. This suggests different coordination of the two metal ions with oxygen. The infrared spectroscopy combined with 2D-COS provides a powerful tool to investigate the mechanism of interaction between heavy metals and manganese oxide.

  10. Size- and composition-dependent toxicity of synthetic and soil-derived Fe oxide colloids for the nematode Caenorhabditis elegans.

    PubMed

    Höss, Sebastian; Fritzsche, Andreas; Meyer, Carolin; Bosch, Julian; Meckenstock, Rainer U; Totsche, Kai Uwe

    2015-01-01

    Colloidal iron oxides (FeOx) are increasingly released to the environment due to their use in environmental remediation and biomedical applications, potentially harming living organisms. Size and composition could affect the bioavailability and toxicity of such colloids. Therefore, we investigated the toxicity of selected FeOx with variable aggregate size and variably composed FeOx-associated organic matter (OM) toward the nematode Caenorhabditis elegans. Ferrihydrite colloids containing citrate were taken up by C. elegans with the food and accumulated inside their body. The toxicity of ferrihydrite, goethite, and akaganeite was dependent on aggregate size and specific surface area, with EC50 values for reproduction ranging from 4 to 29 mg Fe L(-1). Experiments with mutant strains lacking mitochondrial superoxide dismutase (sod-2) showed oxidative stress for two FeOx and Fe(3+)-ions, however, revealed that it was not the predominant mechanism of toxicity. The OM composition determined the toxicity of mixed OM-FeOx phases on C. elegans. FeOx associated with humic acids or citrate were less toxic than OM-free FeOx. In contrast, soil-derived ferrihydrite, containing proteins and polysaccharides from mobile OM, was even more toxic than OM-free Fh of similar aggregate size. Consequently, the careful choice of the type of FeOx and the type of associated OM may help in reducing the ecological risks if actively applied to the subsurface. PMID:25438192

  11. Asbestos Induces Oxidative Stress and Activation of Nrf2 Signaling in Murine Macrophages: Chemopreventive Role of the Synthetic Lignan Secoisolariciresinol Diglucoside (LGM2605)

    PubMed Central

    Pietrofesa, Ralph A.; Velalopoulou, Anastasia; Albelda, Steven M.; Christofidou-Solomidou, Melpo

    2016-01-01

    The interaction of asbestos fibers with macrophages generates harmful reactive oxygen species (ROS) and subsequent oxidative cell damage that are key processes linked to malignancy. Secoisolariciresinol diglucoside (SDG) is a non-toxic, flaxseed-derived pluripotent compound that has antioxidant properties and may thus function as a chemopreventive agent for asbestos-induced mesothelioma. We thus evaluated synthetic SDG (LGM2605) in asbestos-exposed, elicited murine peritoneal macrophages as an in vitro model of tissue phagocytic response to the presence of asbestos in the pleural space. Murine peritoneal macrophages (MFs) were exposed to crocidolite asbestos fibers (20 µg/cm2) and evaluated at various times post exposure for cytotoxicity, ROS generation, malondialdehyde (MDA), and levels of 8-iso Prostaglandin F2α (8-isoP). We then evaluated the ability of LGM2605 to mitigate asbestos-induced oxidative stress by administering LGM2605 (50 µM) 4-h prior to asbestos exposure. We observed a significant (p < 0.0001), time-dependent increase in asbestos-induced cytotoxicity, ROS generation, and the release of MDA and 8-iso Prostaglandin F2α, markers of lipid peroxidation, which increased linearly over time. LGM2605 treatment significantly (p < 0.0001) reduced asbestos-induced cytotoxicity and ROS generation, while decreasing levels of MDA and 8-isoP by 71%–88% and 41%–73%, respectively. Importantly, exposure to asbestos fibers induced cell protective defenses, such as cellular Nrf2 activation and the expression of phase II antioxidant enzymes, HO-1 and Nqo1 that were further enhanced by LGM2605 treatment. LGM2605 boosted antioxidant defenses, as well as reduced asbestos-induced ROS generation and markers of oxidative stress in murine peritoneal macrophages, supporting its possible use as a chemoprevention agent in the development of asbestos-induced malignant mesothelioma. PMID:26938529

  12. Analysis of the influence of synthetic paramaters on the structure and physico-chemical properties of non-spherical iron oxide nanocrystals and their biological stability and compatibility.

    PubMed

    Pardo, Alberto; Pujales, Rosa; Blanco, Mateo; Villar-Alvarez, Eva M; Barbosa, Silvia; Taboada, Pablo; Mosquera, Víctor

    2016-01-14

    In this work, we analyzed the effects of subtle changes in the synthetic conditions and synthetic parameters on the resulting size, shape, monodispersity, crystallinity and magnetic properties of iron oxide nanocrystals (IONCs) obtained through a modified one pot method for the production of mainly cubic-shaped nanoparticles (NPs). Cubic, octahedral and cuboctahedral shapes with different sizes and monodispersity could be obtained by slightly changing the stabilizer/precursor molar ratio, the precursor concentration, the reaction time and temperature and/or the heating rate. Their physical properties were evaluated using high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD), selected-area electron diffraction (SAED) and a superconducting quantum interference (SQUID) device. It was found that monodisperse cubic nanocrystals from ca. 25 to 94 nm could be obtained either by changing the precursor concentration, the heating rate or the reaction time. These cubic nanocrystals were ferrimagnetic in the whole temperature rage analyzed, with saturation magnetization values even larger than those of bulk magnetite. In addition, slightly truncated octahedral NPs could be achieved at relatively large heating ramp rates, whereas cubooctahedral NPs were derived by simply increasing the stabilizer/precursor molar ratio. The saturation magnetization of both types of NPs was slightly lower than the cubic ones, but they were still ferrimagnetic in the whole temperature range analyzed. Moreover, transfer to aqueous solution was possible by a ligand exchange with dimercaptosuccinic acid (DMSA) providing, at the same time, chemical groups for additional functionalization if required. The DMSA-coated cubic IONCs were fairly stable in culture medium, allowing their internalization by different cell types. The NPs inside the cells were located in the cytoplasm and most of them showed a perinuclear distribution. Moreover, a great cytocompatibility in a

  13. Synthetic oils

    NASA Technical Reports Server (NTRS)

    Hatton, R. E.

    1973-01-01

    Synthetic lubricants are discussed by chemical class and their general strengths and weaknesses in terms of lubrication properties are analyzed. Comparative ratings are given for 14 chemical classes and are used as a guide for lubricant selection. The effects of chemical structure on the properties of the lubricant are described with special emphasis on thermal stability. The diversity of synthetic lubricants which is provided by the wide range of properties permits many applications, some of which are reported.

  14. Effects of Surfactants and Synthetic Conditions on the Sizes and Self-Assembly of Monodisperse Iron Oxide Nanoparticles

    SciTech Connect

    Teng, X.; Yang, H.

    2004-02-17

    (B204)Monodisperse iron oxide nanoparticles made from the thermal decomposition of iron carbonyl in octyl ether in the presence of oleic and stearic acids have been examined under various reaction conditions. Monodisperse particles with diameters of 3, 5, 10, 16 and 25 nm have been made. Ostwald ripening could be the key reason for making monodisperse nanoparticles with diameters of up to 25 nm, above the largest sizes that have been reported so far for this class of materials. When stearic acid was used as surfactant, the reaction mixtures can reflux at a lower temperature than the reaction using oleic acid, and monodisperse 3 nm Fe2O3 particles can be made. By controlling the temperatures during the drop casting, different superstructures and superlattices can be created. The nanoparticles and their assembly have been characterized by transmission electron microscopy, electron diffraction, powder X-ray diffraction, and X-ray photoemission spectroscopy.

  15. Synthetic environments

    NASA Astrophysics Data System (ADS)

    Lukes, George E.; Cain, Joel M.

    1996-02-01

    The Advanced Distributed Simulation (ADS) Synthetic Environments Program seeks to create robust virtual worlds from operational terrain and environmental data sources of sufficient fidelity and currency to interact with the real world. While some applications can be met by direct exploitation of standard digital terrain data, more demanding applications -- particularly those support operations 'close to the ground' -- are well-served by emerging capabilities for 'value-adding' by the user working with controlled imagery. For users to rigorously refine and exploit controlled imagery within functionally different workstations they must have a shared framework to allow interoperability within and between these environments in terms of passing image and object coordinates and other information using a variety of validated sensor models. The Synthetic Environments Program is now being expanded to address rapid construction of virtual worlds with research initiatives in digital mapping, softcopy workstations, and cartographic image understanding. The Synthetic Environments Program is also participating in a joint initiative for a sensor model applications programer's interface (API) to ensure that a common controlled imagery exploitation framework is available to all researchers, developers and users. This presentation provides an introduction to ADS and the associated requirements for synthetic environments to support synthetic theaters of war. It provides a technical rationale for exploring applications of image understanding technology to automated cartography in support of ADS and related programs benefitting from automated analysis of mapping, earth resources and reconnaissance imagery. And it provides an overview and status of the joint initiative for a sensor model API.

  16. Synthetic catecholamine triggers β1-adrenergic receptor activation and stimulates cardiotoxicity via oxidative stress mediated apoptotic cell death in rats: Abrogating action of thymol.

    PubMed

    Meeran, M F Nagoor; Jagadeesh, G S; Selvaraj, P

    2016-05-01

    Nowadays, there are considerable interests in the studies which are more connected with the impact of natural antioxidants against the free radical mediated damage in biological systems. Cardiotoxicity is one of the lethal manifestations of cardiovascular diseases (CVDs) which have been associated with the incidence of apoptotic cell death due to oxidative stress. We evaluated the impact of thymol, a dietary monoterpene phenol on isoproterenol (ISO), a synthetic catecholamine and a β1-adrenergic receptor agonist in rats. Thymol (7.5 mg/kg body weight) was pre and co-treated into male albino Wistar rats daily for a period of 7 days. Induction of cardiotoxicity was done by the subcutaneous administration of ISO (100 mg/kg body weight) into rats on 6th and 7th day. Cardiotoxicity in rats was confirmed by the increased levels/activity of serum troponin-T and creatine kinase in the serum alongwith decreased activity of creatine kinase in the heart. ISO induced cardiotoxic rats also showed a significant increase in the concentrations of lipid peroxidation products and a significant decrease in the activities/levels of antioxidants in the myocardium whereas Reverse Transcription Polymerase Chain Reaction study revealed an increased expression of caspase-8, caspase-9 and Fas genes along with a decreased expression of Bcl-xL gene in the myocardium. Thymol pre and co-treated ISO induced cardiotoxic rats showed considerable protective effects on all the biochemical parameters studied. Histopathological and in vitro findings are found in line with our biochemical findings. Thus, the present study revealed that thymol counters ISO induced cardiotoxicity by inhibiting oxidative stress and apoptotic cell death in rats by virtue of its potent antioxidant property. PMID:26996544

  17. Synthetic Jets

    NASA Technical Reports Server (NTRS)

    Milanovic, Ivana M.

    2003-01-01

    Current investigation of synthetic jets and synthetic jets in cross-flow examined the effects of orifice geometry and dimensions, momentum-flux ratio, cluster of orifices, pitch and yaw angles as well as streamwise development of the flow field. This comprehensive study provided much needed experimental information related to the various control strategies. The results of the current investigation on isolated and clustered synthetic jets with and without cross-flow will be further analyzed and documented in detail. Presentations at national conferences and publication of peer- reviewed journal articles are also expected. Projected publications will present both the mean and turbulent properties of the flow field, comparisons made with the data available in an open literature, as well as recommendations for the future work.

  18. Thermodynamic effects of calcium and iron oxides on crystal phase formation in synthetic gasifier slags containing from 0 to 27wt.% V2O3

    DOE PAGESBeta

    Nakano, Jinichiro; Duchesne, Marc; Bennett, James; Kwong, Kyei -Sing; Nakano, Anna; Hughes, Robin

    2014-11-15

    Thermodynamic phase equilibria in synthetic slags (Al2O3–CaO–FeO–SiO2–V2O3) were investigated with 0–27 wt.% vanadium oxide corresponding to industrial coal–petroleum coke (petcoke) feedstock blends in a simulated gasifier environment. Samples encompassing coal–petcoke mixed slag compositions were equilibrated at 1500 °C in a 64 vol.% CO/36 vol.% CO2 atmosphere (Po2 ≈ 10–8 atm at 1500 °C) for 72 h, followed by rapid water quench, then analyzed by inductively coupled plasma optical emission spectrometry, X-ray diffractometry, and scanning electron microscopy with wavelength dispersive spectroscopy. With increasing CaO content, FeO content, or both; the slag homogeneity region expanded and a composition range exhibiting crystals wasmore » reduced. The mullite (Al6Si2O13) crystalline phase was not present in the slags above 9 wt.% FeO while the karelianite (V2O3) crystalline phase was always present in compositions studied if a sufficient amount of vanadium existed in the slag. Furthermore, based on the present experimental equilibrium evaluation, a set of isothermal phase diagrams showing effects of CaO and FeO on thermodynamic phase stabilities in the vanadium-bearing slags is proposed. Some uses of the diagrams for potential industrial practice are discussed.« less

  19. Anode regeneration following carbon depositions in an industrial-sized anode supported solid oxide fuel cell operating on synthetic diesel reformate

    NASA Astrophysics Data System (ADS)

    Subotić, Vanja; Schluckner, Christoph; Mathe, Jörg; Rechberger, Jürgen; Schroettner, Hartmuth; Hochenauer, Christoph

    2015-11-01

    Carbon deposition is a primary concern during operation of solid oxide fuel cells (SOFCs) fueled with carbon-containing fuels. It leads to cell degradation and thus reduces SOFC sustained operation and durability. This paper reports on an experimental investigation of carbon formation on the nickel/yttria-stabilized zirconia (Ni/YSZ) anode of an anode-supported SOFC and its regeneration. The cell was fueled with a synthetically produced diesel reformate to investigate and simulate the cell behavior under real operating conditions. For this purpose the cell was operated under load to determine the critical operating time. Rapid carbon generation, such as at open circuit voltage (OCV), can be prevented when the cell is under load. Carbon depositions were detected using scanning electron microscopy (SEM) and further analyzed by Raman spectroscopy. Industrial-size cells suitable for commercial applications were studied. This study proves the reversibility of carbon formation and the reproducibility of the regeneration process. It shows that carbon formations can be recognized and effectively, fully and cell-protecting regenerated. It indicates the excellent possibility of using SOFCs in the automotive industry as an auxiliary power unit (APU) or combined power-heat unit, operated with diesel reformate, without danger from cell degradation caused by carbon-containing fuels.

  20. Synthetic aircraft turbine oil

    SciTech Connect

    Reinhard, R.R.; Yaffe, R.

    1980-10-07

    Synthetic lubricating oil composition having improved oxidation stability comprises a major portion of an aliphatic ester base oil having lubricating properties, formed by the reaction of pentaerythritol and an organic monocarboxylic acid and containing a phenylnaphthylamine, a dialkyldiphenylamine, a hydrocarbyl phosphate ester, a polyhydroxy anthraquninone, an alkylamine salt of 3-amino-triazole-dodecenylsuccinamic acid, 2-hydroxylpropyl-n, n-dibutyldithiocarbamate, and an alkyl amine salt of a methyl acid phosphate.

  1. Synthetic Astrobiology

    NASA Technical Reports Server (NTRS)

    Rothschild, Lynn J.

    2016-01-01

    Synthetic biology - the design and construction of new biological parts and systems and the redesign of existing ones for useful purposes - has the potential to transform fields from pharmaceuticals to fuels. Our lab has focused on the potential of synthetic biology to revolutionize all three major parts of astrobiology: Where do we come from? Where are we going? and Are we alone? For the first and third, synthetic biology is allowing us to answer whether the evolutionary narrative that has played out on planet earth is likely to have been unique or universal. For example, in our lab we are re-evolving the biosynthetic pathways of amino acids in order to understand potential capabilities of an early organism with a limited repertoire of amino acids and developing techniques for the recovery of metals from spent electronics on other planetary bodies. And what about the limits for life? Can we create organisms that expand the envelope for life? In the future synthetic biology will play an increasing role in human activities both on earth, in fields as diverse as human health and the industrial production of novel bio-composites. Beyond earth, we will rely increasingly on biologically-provided life support, as we have throughout our evolutionary history. In order to do this, the field will build on two of the great contributions of astrobiology: studies of the origin of life and life in extreme environments.

  2. Synthetic Astrobiology

    NASA Technical Reports Server (NTRS)

    Rothschild, Lynn J.

    2015-01-01

    Synthetic biology - the design and construction of new biological parts and systems and the redesign of existing ones for useful purposes - has the potential to transform fields from pharmaceuticals to fuels. Our lab has focused on the potential of synthetic biology to revolutionize all three major parts of astrobiology: Where do we come from? Where are we going? and Are we alone? For the first and third, synthetic biology is allowing us to answer whether the evolutionary narrative that has played out on planet earth is likely to have been unique or universal. For example, in our lab we are re-evolving the biosynthetic pathways of amino acids in order to understand potential capabilities of an early organism with a limited repertoire of amino acids and developing techniques for the recovery of metals from spent electronics on other planetary bodies. In the future synthetic biology will play an increasing role in human activities both on earth, in fields as diverse as human health and the industrial production of novel bio-composites. Beyond earth, we will rely increasingly on biologically-provided life support, as we have throughout our evolutionary history. In order to do this, the field will build on two of the great contributions of astrobiology: studies of the origin of life and life in extreme environments.

  3. Changes in Renal Function and Oxidative Status Associated with the Hypotensive Effects of Oleanolic Acid and Related Synthetic Derivatives in Experimental Animals

    PubMed Central

    Madlala, Hlengiwe Pretty; Van Heerden, Fanie Retief; Mubagwa, Kanigula; Musabayane, Cephas Tagumirwa

    2015-01-01

    Purpose The triterpene oleanolic acid (OA) is known to possess antihypertensive actions. In the present study we to compared the effects of the triterpene on mean arterial blood pressure (MAP) and kidney function following acute administration in normotensive animals with those of its related oleanane synthetic derivatives (brominated oleanolic acid, Br-OA and oleanolic acid methyl ester, Me-OA). We also used experimental models of hypertension to further explore the effects of sub-chronic oral OA treatment and evaluated influences on oxidative status. Methods OA was extracted from dried flower buds of Syzygium aromaticum using a previously validated protocol in our laboratory. Me-OA and Br-OA were synthesized according to a method described. Rats were supplemented with lithium chloride (12 mmol L-1) prior to experimentation in order to raise plasma lithium to allow measurements of lithium clearance and fractional excretion (FELi) as indices of proximal tubular Na+ handling. Anaesthetized animals were continuously infused via the right jugular with 0.077M NaCl. MAP was measured via a cannula inserted in the carotid artery, and urine was collected through a cannula inserted in the bladder. After a 3.5 h equilibration, MAP, urine flow, electrolyte excretion rates were determined for 4 h of 1 h control, 1.5 h treatment and 1.5 h recovery periods. OA, Me-OA and Br-OA were added to the infusate during the treatment period. We evaluated sub-chronic effects on MAP and kidney function in normotensive Wistar rats and in two animal models of hypertension, spontaneously hypertensive rats (SHR) and Dahl salt-sensitive (DSS) rats, during 9-week administration of OA (p.o.). Tissue oxidative status was examined in these animals at the end of the study. Increasing evidence suggests that and renal function disturbances and oxidative stress play major roles in the pathogenesis of hypertension. Results Acute infusion OA and oleanane derivatives displayed qualitatively similar effects

  4. Synthetic chromosomes.

    PubMed

    Schindler, Daniel; Waldminghaus, Torsten

    2015-11-01

    What a living organism looks like and how it works and what are its components-all this is encoded on DNA, the genetic blueprint. Consequently, the way to change an organism is to change its genetic information. Since the first pieces of recombinant DNA have been used to transform cells in the 1970s, this approach has been enormously extended. Bigger and bigger parts of the genetic information have been exchanged or added over the years. Now we are at a point where the construction of entire chromosomes becomes a reachable goal and first examples appear. This development leads to fundamental new questions, for example, about what is possible and desirable to build or what construction rules one needs to follow when building synthetic chromosomes. Here we review the recent progress in the field, discuss current challenges and speculate on the appearance of future synthetic chromosomes. PMID:26111960

  5. Synthesis of ferromagnetic nanoparticles, formic acid oxidation catalyst nanocomposites, and late-transition metal-boride intermetallics by unique synthetic methods and single-source precursors

    NASA Astrophysics Data System (ADS)

    Wellons, Matthew S.

    The design, synthesis, and characterization of magnetic alloy nanoparticles, supported formic acid oxidation catalysts, and superhard intermetallic composites are presented. Ferromagnetic equatomic alloy nanoparticles of FePt, FePd, and CoPt were synthesized utilizing single-source heteronuclear organometallic precursors supported on an inert water-soluble matrix. Direct conversion of the precursor-support composite to supported ferromagnetic nanoparticles occurs under elevated temperatures and reducing conditions with metal-ion reduction and minimal nanoparticle coalescence. Nanoparticles were easily extracted from the support by addition of water and characterized in structure and magnetic properties. Palladium and platinum based nanoparticles were synthesized with microwave-based and chemical metal-ion reduction strategies, respectively, and tested for catalytic performance in a direct formic acid fuel cell (DFAFC). A study of palladium carbide nanocomposites with various carbonaceous supports was conducted and demonstrated strong activity comparable to commercially available palladium black, but poor catalytic longevity. Platinum-lead alloy nanocomposites synthesized with chemical reduction and supported on Vulcan carbon demonstrated strong activity, excellent catalytic longevity, and were subsequently incorporated into a prototype DFAFC. A new method for the synthesis of superhard ceramics on polymer substrates called Confined Plasma Chemical Deposition (CPCD) was developed. The CPCD method utilizes a tuned Free Electron Laser to selectively decompose the single-source precursor, Re(CO)4(B3H8), in a plasma-like state resulting in the superhard intermetallic ReB2 deposited on polymer substrates. Extension of this method to the synthesis of other hard of superhard ceramics; WB4, RuB2, and B4C was demonstrated. These three areas of research show new synthetic methods and novel materials of technological importance, resulting in a substantial advance in their

  6. Application of inorganic oxidants to the spectrophotometric determination of ribavirin in bulk and capsules.

    PubMed

    Darwish, Ibrahim A; Khedr, Alaa S; Askal, Hassan F; Mohamed, Ramadan M

    2006-01-01

    Eight spectrophotometric methods for determination of ribavirin have been developed and validated. These methods were based on the oxidation of the drug by different inorganic oxidants: ceric ammonium sulfate, potassium permanganate, ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate. The oxidation reactions were performed in perchloric acid medium for ceric ammonium sulfate and in sulfuric acid medium for the other reagents. With ceric ammonium sulfate and potassium permanganate, the concentration of ribavirin in its samples was determined by measuring the decrease in the absorption intensity of the colored reagents at 315 and 525 nm, respectively. With the other reagents, the concentration of ribavirin was determined by measuring the intensity of the developed colored reaction products at the wavelengths of maximum absorbance: 675, 780, 595, 595, 475, and 475 nm for reactions with ammonium molybdate, ammonium metavanidate, chromium trioxide, potassium dichromate, potassium iodate, and potassium periodate, respectively. Different variables affecting the reaction conditions were carefully studied and optimized. Under the optimum conditions, linear relationships with good correlation coefficients (0.9984-0.9998) were found between the absorbance readings and the concentrations of ribavirin in the range of 4-1400 microg/mL. The molar absorptivities were correlated with the oxidation potential of the oxidants used. The precision of the methods were satisfactory; the values of relative standard deviation did not exceed 1.64%. The proposed methods were successfully applied to the analysis of ribavirin in pure drug material and capsules with good accuracy and precision; the recovery values were 99.2-101.2 +/- 0.48-1.30%. The results obtained using the proposed spectrophotometric methods were comparable with those obtained with the official method stated in the United States Pharmacopeia. PMID

  7. Synthetic Cathinones ("Bath Salts")

    MedlinePlus

    ... still unknown about how synthetic cathinones affect the human brain. Researchers do know that synthetic cathinones are chemically ... of the chemicals in synthetic cathinones affect the human brain. Synthetic cathinones can cause: nosebleeds paranoia increased sociability ...

  8. A Comparison of Natural (D-α-tocopherol) and Synthetic (DL-α-tocopherol Acetate) Vitamin E Supplementation on the Growth Performance, Meat Quality and Oxidative Status of Broilers.

    PubMed

    Cheng, K; Niu, Y; Zheng, X C; Zhang, H; Chen, Y P; Zhang, M; Huang, X X; Zhang, L L; Zhou, Y M; Wang, T

    2016-05-01

    The present study was conducted to compare the supplementation of natural (D-α-tocopherol) and synthetic (DL-α-tocopherol acetate) vitamin E on the growth performance, meat quality, muscular antioxidant capacity and genes expression related to oxidative status of broilers. A total of 144 1 day-old Arbor Acres broiler chicks were randomly allocated into 3 groups with 6 replicates of 8 birds each. Birds were given a basal diet (control group), and basal diet supplemented with either 20 IU D-α-tocopherol or DL-α-tocopherol acetate for 42 days, respectively. The results indicated that treatments did not alter growth performance of broilers (p>0.05). Compared with the control group, concentration of α-tocopherol in the breast muscle was increased by the supplementation of vitamin E (p<0.05). In the thigh, α-tocopherol content was also enhanced by vitamin E inclusion, and this effect was more pronounced in the natural vitamin E group (p<0.05). Vitamin E supplementation increased the redness of breast (p<0.05). In the contrast, the inclusion of synthetic vitamin E decreased lightness of thigh (p<0.05). Dietary vitamin E inclusion reduced drip loss at 24 h of thigh muscle (p<0.05), and this effect was maintained for drip loss at 48 h in the natural vitamin E group (p<0.05). Broilers given diet supplemented with vitamin E showed decreased malondialdehyde (MDA) content in the breast (p<0.05). Additionally, natural rather than synthetic vitamin E reduced MDA accumulation in the thigh (p<0.05). Neither natural nor synthetic vitamin E supplementation altered muscular mRNA abundance of genes related to oxidative stress (p>0.05). It was concluded that vitamin E supplementation, especially the natural vitamin E, can enhance the retention of muscular α-tocopherol, improve meat quality and muscular antioxidant capacity of broilers. PMID:26954216

  9. A Comparison of Natural (D-α-tocopherol) and Synthetic (DL-α-tocopherol Acetate) Vitamin E Supplementation on the Growth Performance, Meat Quality and Oxidative Status of Broilers

    PubMed Central

    Cheng, K.; Niu, Y.; Zheng, X. C.; Zhang, H.; Chen, Y. P.; Zhang, M.; Huang, X. X.; Zhang, L. L.; Zhou, Y. M.; Wang, T.

    2016-01-01

    The present study was conducted to compare the supplementation of natural (D-α-tocopherol) and synthetic (DL-α-tocopherol acetate) vitamin E on the growth performance, meat quality, muscular antioxidant capacity and genes expression related to oxidative status of broilers. A total of 144 1 day-old Arbor Acres broiler chicks were randomly allocated into 3 groups with 6 replicates of 8 birds each. Birds were given a basal diet (control group), and basal diet supplemented with either 20 IU D-α-tocopherol or DL-α-tocopherol acetate for 42 days, respectively. The results indicated that treatments did not alter growth performance of broilers (p>0.05). Compared with the control group, concentration of α-tocopherol in the breast muscle was increased by the supplementation of vitamin E (p<0.05). In the thigh, α-tocopherol content was also enhanced by vitamin E inclusion, and this effect was more pronounced in the natural vitamin E group (p<0.05). Vitamin E supplementation increased the redness of breast (p<0.05). In the contrast, the inclusion of synthetic vitamin E decreased lightness of thigh (p<0.05). Dietary vitamin E inclusion reduced drip loss at 24 h of thigh muscle (p<0.05), and this effect was maintained for drip loss at 48 h in the natural vitamin E group (p<0.05). Broilers given diet supplemented with vitamin E showed decreased malondialdehyde (MDA) content in the breast (p<0.05). Additionally, natural rather than synthetic vitamin E reduced MDA accumulation in the thigh (p<0.05). Neither natural nor synthetic vitamin E supplementation altered muscular mRNA abundance of genes related to oxidative stress (p>0.05). It was concluded that vitamin E supplementation, especially the natural vitamin E, can enhance the retention of muscular α-tocopherol, improve meat quality and muscular antioxidant capacity of broilers. PMID:26954216

  10. RAPID MEASUREMENTS OF NEPTUNIUM OXIDATION STATES USING CHROMATOGRAPHIC RESINS

    SciTech Connect

    Diprete, D; C Diprete, C; Mira Malek, M; Eddie Kyser, E

    2009-03-24

    The Savannah River Site's (SRS) H-Canyon facility uses ceric ammonium nitrate (CAN) to separate impure neptunium (Np) from a high sulfate feed stream. The material is processed using a two-pass solvent extraction purification which relies on CAN to oxidize neptunium to Np(VI) during the first pass prior to extraction. Spectrophotometric oxidation-state analyses normally used to validate successful oxidation to Np(VI) prior to extraction were compromised by this feed stream matrix. Therefore, a rapid chromatographic method to validate successful Np oxidation was developed using Eichrom Industries TRU and TEVA{reg_sign} resins. The method was validated and subsequently transferred to existing operations in the process analytical laboratories.

  11. Gearing up for synthetic lubricants

    SciTech Connect

    Shelley, S.

    1993-07-01

    Much of today's plant machinery operates at faster speeds, closer tolerances and higher temperatures than ever before. Without the help of lubricants to reduce wear, remove heat, and prevent corrosion, the chemical process industries would grind to a halt. Traditional, petroleum-derived products--called mineral oils-- have long starred in these roles. But today, synthetics, such as polyalphaolefins, carboxylic acid esters, phosphate esters and polyglycols are stealing the limelight, thanks to their inherent resistance to oxidation and hydrolysis and their extended range of service temperatures. The paper reviews the advantages of the synthetic lubricants.

  12. Chlorination of bromide-containing waters: enhanced bromate formation in the presence of synthetic metal oxides and deposits formed in drinking water distribution systems.

    PubMed

    Liu, Chao; von Gunten, Urs; Croué, Jean-Philippe

    2013-09-15

    Bromate formation from the reaction between chlorine and bromide in homogeneous solution is a slow process. The present study investigated metal oxides enhanced bromate formation during chlorination of bromide-containing waters. Selected metal oxides enhanced the decay of hypobromous acid (HOBr), a requisite intermediate during the oxidation of bromide to bromate, via (i) disproportionation to bromate in the presence of nickel oxide (NiO) and cupric oxide (CuO), (ii) oxidation of a metal to a higher valence state in the presence of cuprous oxide (Cu2O) and (iii) oxygen formation by NiO and CuO. Goethite (α-FeOOH) did not enhance either of these pathways. Non-charged species of metal oxides seem to be responsible for the catalytic disproportionation which shows its highest rate in the pH range near the pKa of HOBr. Due to the ability to catalyze HOBr disproportionation, bromate was formed during chlorination of bromide-containing waters in the presence of CuO and NiO, whereas no bromate was detected in the presence of Cu2O and α-FeOOH for analogous conditions. The inhibition ability of coexisting anions on bromate formation at pH 8.6 follows the sequence of phosphate > sulfate > bicarbonate/carbonate. A black deposit in a water pipe harvested from a drinking water distribution system exerted significant residual oxidant decay and bromate formation during chlorination of bromide-containing waters. Energy dispersive spectroscopy (EDS) analyses showed that the black deposit contained copper (14%, atomic percentage) and nickel (1.8%, atomic percentage). Cupric oxide was further confirmed by X-ray diffraction (XRD). These results indicate that bromate formation may be of concern during chlorination of bromide-containing waters in distribution systems containing CuO and/or NiO. PMID:23866145

  13. Selective separation and determination of the synthetic colorants in beverages by magnetic solid-phase dispersion extraction based on a Fe3 O4 /reduced graphene oxide nanocomposite followed by high-performance liquid chromatography with diode array detection.

    PubMed

    Wang, Xi; Chen, Ning; Han, Qing; Yang, Zaiyue; Wu, Jinhua; Xue, Cheng; Hong, Junli; Zhou, Xuemin; Jiang, Huijun

    2015-06-01

    A facile adsorbent, a nanocomposite of Fe3 O4 and reduced graphene oxide, was fabricated for the selective separation and enrichment of synthetic aromatic azo colorants by magnetic solid-phase dispersion extraction. The nanocomposite was synthesized in a one-step reduction reaction and characterized by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction and Brunauer-Emmett-Teller analysis. The colorants in beverages were quickly adsorbed onto the surface of the nanocomposite with strong π-π interactions between colorants and reduced graphene oxide, and separated with the assistance of an external magnetic field. Moreover, the four colorants in beverages were detected at different wavelengths by high performance liquid chromatography with diode array detection. A linear dependence of peak area was obtained over 0.05-10 μg/mL with the limits of detection of 10.02, 11.90, 10.41, 15.91 ng/mL for tartrazine, allure red, amaranth, and new coccine, respectively (signal to noise = 3). The recoveries for the spiked colorants were in the range of 88.95-95.89% with the relative standard deviation less than 2.66%. The results indicated that the nanocomposite of Fe3 O4 and reduced graphene oxide could be used as an excellent selective adsorbent for aromatic compounds and has potential applications in sample pretreatment. PMID:25864558

  14. Synthetic CO.sub.2 acceptor

    DOEpatents

    Lancet, Michael S.; Curran, George P.

    1981-08-18

    A synthetic CO.sub.2 acceptor consisting essentially of at least one compound selected from the group consisting of calcium oxide and calcium carbonate supported in a refractory carrier matrix, the carrier having the general formula Ca.sub.5 (SiO.sub.4).sub.2 CO.sub.3. A method for producing the synthetic CO.sub.2 acceptor is also disclosed.

  15. Isotopic Studies of O-O Bond Formation During Water Oxidation (SISGR)

    SciTech Connect

    Roth, Justine P.

    2015-03-03

    Isotopic Studies of O-O Bond Formation During Water Oxidation (SISGR) Research during the project period focused primarily on mechanisms of water oxidation by structurally defined transition metal complexes. Competitive oxygen isotope fractionation of water, mediated by oxidized precursors or reduced catalysts together with ceric, Ce(IV), ammonium nitrate in aqueous media, afforded oxygen-18 kinetic isotope effects (O-18 KIEs). Measurement, calculation, and interpretation of O-18 KIEs, described in the accompanying report has important ramifications for the production of electricity and solar hydrogen (as fuel). The catalysis division of BES has acknowledged that understanding mechanisms of transition metal catalyzed water oxidation has major ramifications, potentially leading to transformation of the global economy and natural environment in years to come. Yet, because of program restructuring and decreased availability of funds, it was recommended that the Solar Photochemistry sub-division of BES would be a more appropriate parent program for support of continued research.

  16. The effect of the synthetic route on the structural, textural, morphological and catalytic properties of iron(iii) oxides and oxyhydroxides.

    PubMed

    Oulego, Paula; Villa-García, María A; Laca, Adriana; Diaz, Mario

    2016-06-21

    A variety of iron(iii) oxides and oxyhydroxides were synthesised and characterised using three distinct methods of preparation: microemulsion, precipitation and sol-gel. The results clearly showed that the structure, textural properties, crystal morphology and catalytic performance of the phases obtained were highly dependent on the chemical routes used for the synthesis. Precipitation and microemulsion methods allowed obtaining mesoporous nanostructured iron(iii) oxides with mean particle sizes of 4 nm (amorphous hematite) and 7 nm (ferrihydrite), which exhibited a high surface area (291.4 m(2) g(-1) and 192.3 m(2) g(-1), respectively) and a very good catalytic behaviour in the advanced oxidation of highly non-biodegradable wastewaters. The different conditions employed in the synthesis of these materials through the sol-gel method yielded two goethites with practically the same catalytic properties, but dissimilar morphologies and texture. When soft agitation and slow addition of the precipitating agent were used, the resulting material (G1) was made up of shorter and finer particles, markedly acicular, with an average length of 400 ± 50 nm and width of 15 ± 5 nm. However, vigorous agitation and rapid addition of the precipitating agent led to the formation of longer and coarser particles, moderately acicular, the average length and width being 950 ± 100 nm and 140 ± 20 nm, respectively. The use of the sol-gel technique also resulted in the formation of a solid consisting of a mixture of hematite as the main crystalline phase and goethite particles dispersed among the hematite particles. This solid presented a low specific surface area (13.2 m(2) g(-1)) and lower catalytic activity. Therefore, precipitation and microemulsion proved to be the most suitable techniques to synthesise catalytically active disordered iron(iii) oxide nanoparticles, due to the presence of highly reactive non-stoichiometric iron(iii) ions, a higher surface area and smaller particle

  17. A novel alkaloid antioxidant, Boldine and synthetic antioxidant, reduced form of RU486, inhibit the oxidation of LDL in-vitro and atherosclerosis in vivo in LDLR(-/-) mice.

    PubMed

    Santanam, N; Penumetcha, M; Speisky, H; Parthasarathy, S

    2004-04-01

    A corollary to the oxidation hypothesis of atherosclerosis is that the consumption of antioxidants is beneficial. However, the literature is divided in support of this conclusion. In this study, Boldine, an alkaloid of Peumus boldus and reduced form of RU486, was tested for their antioxidant potency both in, in vitro oxidation system and in mouse models. Boldine decreased the ex-vivo oxidation of low-density lipoprotein (LDL). Two different in vivo studies were performed to study the effect of these compounds on the atherosclerotic lesion formation in LDLR(-/-) mice. In study I, three groups of LDLR(-/-) mice (N = 12 each) were fed an atherogenic diet. Group 1 was given vehicle and group 2 and 3 were given 1mg of Boldine or Red RU per day for 12 weeks. In study II, two groups of LDLR(-/-) mice N = 10 each) were fed an atherogenic diet. Group 1 was given vehicle and group 2 was given 5mg of Boldine per day. The results indicated that there was a decrease in lesion formation reaching a 40% reduction due to Boldine and 45% reduction by Red RU compared to controls. The in vivo tolerance of Boldine in humans (has been used as an herbal medicine in other diseases) should make it an attractive alternative to Vitamin E. PMID:15064093

  18. [From synthetic biology to synthetic humankind].

    PubMed

    Nouvel, Pascal

    2015-01-01

    In this paper, we propose an historical survey of the expression "synthetic biology" in order to identify its main philosophical components. The result of the analysis is then used to investigate the meaning of the notion of "synthetic man". It is shown that both notions share a common philosophical background that can be summed up by the short but meaningful assertion: "biology is technology". The analysis allows us to distinguish two notions that are often confused in transhumanist literature: the notion of synthetic man and the notion of renewed man. The consequences of this crucial distinction are discussed. PMID:26238764

  19. Direct Synthetic Control over the Size, Composition, and Photocatalytic Activity of Octahedral Copper Oxide Materials: Correlation Between Surface Structure and Catalytic Functionality.

    PubMed

    Nguyen, Michelle A; Bedford, Nicholas M; Ren, Yang; Zahran, Elsayed M; Goodin, Robert C; Chagani, Fatima F; Bachas, Leonidas G; Knecht, Marc R

    2015-06-24

    We report a synthetic approach to form octahedral Cu2O microcrystals with a tunable edge length and demonstrate their use as catalysts for the photodegradation of aromatic organic compounds. In this particular study, the effects of the Cu(2+) and reductant concentrations and stoichiometric ratios were carefully examined to identify their roles in controlling the final material composition and size under sustainable reaction conditions. Varying the ratio and concentrations of Cu(2+) and reductant added during the synthesis determined the final morphology and composition of the structures. Octahedral particles were prepared at selected Cu(2+):glucose ratios that demonstrated a range of photocatalytic reactivity. The results indicate that material composition, surface area, and substrate charge effects play important roles in controlling the overall reaction rate. In addition, analysis of the post-reacted materials revealed photocorrosion was inhibited and that surface etching had preferentially occurred at the particle edges during the reaction, suggesting that the reaction predominately occurred at these interfaces. Such results advance the understanding of how size and composition affect the surface interface and catalytic functionality of materials. PMID:26010080

  20. Electrochemically reduced graphene oxide-modified screen-printed carbon electrodes for a simple and highly sensitive electrochemical detection of synthetic colorants in beverages.

    PubMed

    Jampasa, Sakda; Siangproh, Weena; Duangmal, Kiattisak; Chailapakul, Orawon

    2016-11-01

    A simple and highly sensitive electrochemical sensor based on an electrochemically reduced graphene oxide-modified screen-printed carbon electrode (ERGO-SPCE) for the simultaneous determination of sunset yellow (SY) and tartrazine (TZ) was proposed. An ERGO film was coated onto the electrode surface using a cyclic voltammetric method and then characterized by scanning electron microscopy (SEM). In 0.1M phosphate buffer at a pH of 6, the two oxidation peaks of SY and TZ appeared separately at 0.41 and 0.70V, respectively. Surprisingly, the electrochemical response remarkably increased approximately 90- and 20-fold for SY and TZ, respectively, using the modified electrode in comparison to the unmodified electrode. The calibration curves exhibited linear ranges from 0.01 to 20.0µM for SY and from 0.02 to 20.0µM for TZ. The limits of detection were found to be 0.50 and 4.50nM (at S/N=3) for SY and TZ, respectively. Furthermore, this detection platform provided very high selectivity for the measurement of both colorants. This electrochemical sensor was successfully applied to determine the amount of SY and TZ in commercial beverages. Comparison of the results obtained from this proposed method to those obtained by an in-house standard technique proved that this developed method has good agreement in terms of accuracy for practical applications. This sensor offers an inexpensive, rapid and sensitive determination. The proposed system is therefore suitable for routine analysis and should be an alternative method for the analysis of food colorants. PMID:27591594

  1. Nitric oxide synthetic pathway and cGMP levels are altered in red blood cells from end-stage renal disease patients.

    PubMed

    Di Pietro, Natalia; Giardinelli, Annalisa; Sirolli, Vittorio; Riganti, Chiara; Di Tomo, Pamela; Gazzano, Elena; Di Silvestre, Sara; Panknin, Christina; Cortese-Krott, Miriam M; Csonka, Csaba; Kelm, Malte; Ferdinandy, Péter; Bonomini, Mario; Pandolfi, Assunta

    2016-06-01

    Red blood cells (RBCs) enzymatically produce nitric oxide (NO) by a functional RBC-nitric oxide synthase (RBC-NOS). NO is a vascular key regulatory molecule. In RBCs its generation is complex and influenced by several factors, including insulin, acetylcholine, and calcium. NO availability is reduced in end-stage renal disease (ESRD) and associated with endothelial dysfunction. We previously demonstrated that, through increased phosphatidylserine membrane exposure, ESRD-RBCs augmented their adhesion to human cultured endothelium, in which NO bioavailability decreased. Since RBC-NOS-dependent NO production in ESRD is unknown, this study aimed to investigate RBC-NOS levels/activation, NO production/bioavailability in RBCs from healthy control subjects (C, N = 18) and ESRD patients (N = 27). Although RBC-NOS expression was lower in ESRD-RBCs, NO, cyclic guanosine monophosphate (cGMP), RBC-NOS Serine1177 phosphorylation level and eNOS/Calmodulin (CaM)/Heat Shock Protein-90 (HSP90) interaction levels were higher in ESRD-RBCs, indicating increased enzyme activation. Conversely, following RBCs stimulation with insulin or ionomycin, NO and cGMP levels were significantly lower in ESRD- than in C-RBCs, suggesting that uremia might reduce the RBC-NOS response to further stimuli. Additionally, the activity of multidrug-resistance-associated protein-4 (MRP4; cGMP-membrane transporter) was significantly lower in ESRD-RBCs, suggesting a possible compromised efflux of cGMP across the ESRD-RBCs membrane. This study for the first time showed highest basal RBC-NOS activation in ESRD-RBCs, possibly to reduce the negative impact of decreased NOS expression. It is further conceivable that high NO production only partially affects cell function of ESRD-RBCs maybe because in vivo they are unable to respond to physiologic stimuli, such as calcium and/or insulin. PMID:27206740

  2. Three Members of Polyamine Modulon under Oxidative Stress Conditions: Two Transcription Factors (SoxR and EmrR) and a Glutathione Synthetic Enzyme (GshA)

    PubMed Central

    Sakamoto, Akihiko; Terui, Yusuke; Yoshida, Taketo; Yamamoto, Taku; Suzuki, Hideyuki; Yamamoto, Kaneyoshi; Ishihama, Akira; Igarashi, Kazuei; Kashiwagi, Keiko

    2015-01-01

    Members of polyamine modulon whose synthesis is enhanced at the level of translation were looked for under oxidative stress conditions caused by 0.6 μM K2TeO3. When an Escherichia coli polyamine-requiring mutant MA261 was cultured in the presence of K2TeO3, the degree of polyamine stimulation of cell growth was greater than in cells cultured in the absence of K2TeO3. Under these conditions, synthesis of SoxR, a transcriptional factor for expression of the superoxide response regulon, EmrR, a negative transcriptional factor for expression of the genes for drug excretion proteins, EmrA and EmrB, and of GshA, γ-glutamylcysteine synthetase necessary for glutathione (GSH) synthesis, were stimulated by polyamines at the level of translation. Polyamine stimulation of SoxR and EmrR synthesis was dependent on the existence of an unusually located Shine-Dalgarno (SD) sequence in soxR and emrR mRNAs. Polyamine stimulation of GshA synthesis was due to the existence of the inefficient initiation codon UUG instead of AUG. Polyamine stimulation of the synthesis of EmrR was mainly observed at the logarithmic phase of growth, while that of the synthesis of SoxR and GshA was at the stationary phase. These results strongly suggest that polyamines are involved in easing of oxidative stress through stimulation of synthesis of SoxR, EmrR and GshA together with RpoS, previously found as a member of polyamine modulon at the stationary phase. PMID:25898225

  3. Optimization and modelling of synthetic azo dye wastewater treatment using Graphene oxide nanoplatelets: Characterization toxicity evaluation and optimization using Artificial Neural Network.

    PubMed

    Banerjee, Priya; Sau, Shubhra; Das, Papita; Mukhopadhayay, Aniruddha

    2015-09-01

    Azo dyes pose a major threat to current civilization by appearing in almost all streams of wastewater. The present investigation was carried out to examine the potential of Graphene oxide (GO) nanoplatelets as an efficient, cost-effective and non-toxic azo dye adsorbent for efficient wastewater treatment. The treatment process was optimized using Artificial Neural Network for maximum percentage dye removal and evaluated in terms of varying operational parameters, process kinetics and thermodynamics. A brief toxicity assay was also designed using fresh water snail Bellamya benghalensis to analyze the quality of the treated solution. 97.78% removal of safranin dye was obtained using GO as adsorbent. Characterization of GO nanoplatelets (using SEM, TEM, AFM and FTIR) reported the changes in its structure as well as surface morphology before and after use and explained its prospective as a good and environmentally benign adsorbent in very low quantities. The data recorded when subjected to different isotherms best fitted the Temkin isotherm. Further analysis revealed the process to be endothermic and chemisorption in nature. The verdict of the toxicity assay rendered the treated permeate as biologically safe for discharge or reuse in industrial and domestic purposes. PMID:25966335

  4. Synthetic cathinone abuse

    PubMed Central

    Capriola, Michael

    2013-01-01

    The abuse of synthetic cathinones, widely known as bath salts, has been increasing since the mid-2000s. These substances are derivatives of the naturally occurring compound cathinone, which is the primary psychoactive component of khat. The toxicity of synthetic cathinones includes significant sympathomimetic effects, as well as psychosis, agitation, aggression, and sometimes violent and bizarre behavior. Mephedrone and methylenedioxypyrovalerone are currently the predominantly abused synthetic cathinones. PMID:23869180

  5. Evolvable synthetic neural system

    NASA Technical Reports Server (NTRS)

    Curtis, Steven A. (Inventor)

    2009-01-01

    An evolvable synthetic neural system includes an evolvable neural interface operably coupled to at least one neural basis function. Each neural basis function includes an evolvable neural interface operably coupled to a heuristic neural system to perform high-level functions and an autonomic neural system to perform low-level functions. In some embodiments, the evolvable synthetic neural system is operably coupled to one or more evolvable synthetic neural systems in a hierarchy.

  6. [SYNTHETIC PEPTIDE VACCINES].

    PubMed

    Sergeyev, O V; Barinsky, I F

    2016-01-01

    An update on the development and trials of synthetic peptide vaccines is reviewed. The review considers the successful examples of specific protection as a result of immunization with synthetic peptides using various protocols. The importance of conformation for the immunogenicity of the peptide is pointed out. An alternative strategy of the protection of the organism against the infection using synthetic peptides is suggested. PMID:27145593

  7. Characterizing synthetic gypsum

    SciTech Connect

    Henkels, P.J.; Gaynor, J.C.

    1996-10-01

    Each gypsum wallboard manufacturer has developed its own general guidelines for synthetic gypsum. The guidelines vary accordingly for each manufacturer and are often modified to suite a particular source and end use. In addition, the physical and chemical properties of synthetic gypsum are characterized by several proprietary and published test methods. Characterizing a synthetic gypsum and determining its acceptability is a time consuming process and can be confusing, particularly to those outside the gypsum wallboard industry. This paper describes some of the more important characteristics and practical aspects of synthetic gypsum usage based on USG`s extensive experience in wall board manufacture.

  8. Variable Synthetic Capacitance

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L.

    1986-01-01

    Feedback amplifier circuit synthesizes electronically variable capacitance. Variable Synthetic Capacitor is amplifier circuit with follower/feedback configuration. Effective input capacitance depends on input set current. If synthetic capacitor is connected across resonant element of oscillator, oscillator frequency controlled via input set current. Circuit especially suitable for fine frequency adjustments of piezoelectric-crystal or inductor/capacitor resonant oscillators.

  9. Designing synthetic biology.

    PubMed

    Agapakis, Christina M

    2014-03-21

    Synthetic biology is frequently defined as the application of engineering design principles to biology. Such principles are intended to streamline the practice of biological engineering, to shorten the time required to design, build, and test synthetic gene networks. This streamlining of iterative design cycles can facilitate the future construction of biological systems for a range of applications in the production of fuels, foods, materials, and medicines. The promise of these potential applications as well as the emphasis on design has prompted critical reflection on synthetic biology from design theorists and practicing designers from many fields, who can bring valuable perspectives to the discipline. While interdisciplinary connections between biologists and engineers have built synthetic biology via the science and the technology of biology, interdisciplinary collaboration with artists, designers, and social theorists can provide insight on the connections between technology and society. Such collaborations can open up new avenues and new principles for research and design, as well as shed new light on the challenging context-dependence-both biological and social-that face living technologies at many scales. This review is inspired by the session titled "Design and Synthetic Biology: Connecting People and Technology" at Synthetic Biology 6.0 and covers a range of literature on design practice in synthetic biology and beyond. Critical engagement with how design is used to shape the discipline opens up new possibilities for how we might design the future of synthetic biology. PMID:24156739

  10. Synthetic facial implants.

    PubMed

    Quatela, Vito C; Chow, Jen

    2008-02-01

    This article presents a range of synthetic implant materials for use in facial plastic surgery. The authors discuss alternatives to autogenous tissue transfer in terms of biocompatibility, technique, complications, controversies, and cautions. The reader is presented information about a range of synthetic implant materials such as silicone, polyester fiber, polyamide mesh, metal, polyethylene, polyacrylamide gel, hydroxyapatite, polylactic acid, collagen, and others. PMID:18063244

  11. Cyclic thermochemical process for producing hydrogen using cerium-titanium compounds

    DOEpatents

    Bamberger, C.E.

    A thermochemical cyclic process for producing hydrogen employs the reaction between ceric oxide and titanium dioxide to form cerium titanate and oxygen. The titanate is treated with an alkali metal hydroxide to give hydrogen, ceric oxide, an alkali metal titanate and water. Alkali metal titanate and water are boiled to give titanium dioxide which, along with ceric oxide, is recycled.

  12. Cyclic thermochemical process for producing hydrogen using cerium-titanium compounds

    DOEpatents

    Bamberger, Carlos E.

    1980-01-01

    A thermochemical cyclic process for producing hydrogen employs the reaction between ceric oxide and titanium dioxide to form cerium titanate and oxygen. The titanate is treated with an alkali metal hydroxide to give hydrogen, ceric oxide, an alkali metal titanate and water. Alkali metal titanate and water are boiled to give titanium dioxide which, along with ceric oxide, is recycled.

  13. Building synthetic memory.

    PubMed

    Inniss, Mara C; Silver, Pamela A

    2013-09-01

    Cellular memory - conversion of a transient signal into a sustained response - is a common feature of biological systems. Synthetic biologists aim to understand and re-engineer such systems in a reliable and predictable manner. Synthetic memory circuits have been designed and built in vitro and in vivo based on diverse mechanisms, such as oligonucleotide hybridization, recombination, transcription, phosphorylation, and RNA editing. Thus far, building these circuits has helped us explore the basic principles required for stable memory and ask novel biological questions. Here we discuss strategies for building synthetic memory circuits, their use as research tools, and future applications of these devices in medicine and industry. PMID:24028965

  14. Building synthetic memory

    PubMed Central

    Inniss, Mara C.; Silver, Pamela A.

    2013-01-01

    Synopsis Cellular memory – conversion of a transient signal into a sustained response – is a common feature of biological systems. Synthetic biologists aim to understand and reengineer such systems in a reliable and predictable manner. Synthetic memory circuits have been designed and built in vitro and in vivo based on diverse mechanisms such as oligonucleotide hybridization, recombination, transcription, phosphorylation, and RNA editing. Thus far, building these circuits has helped us explore the basic principles required for stable memory and ask novel biological questions. Here we discuss strategies for building synthetic memory circuits, their use as research tools, and future applications of these devices in medicine and industry. PMID:24028965

  15. Synthetic Base Fluids

    NASA Astrophysics Data System (ADS)

    Brown, M.; Fotheringham, J. D.; Hoyes, T. J.; Mortier, R. M.; Orszulik, S. T.; Randles, S. J.; Stroud, P. M.

    The chemical nature and technology of the main synthetic lubricant base fluids is described, covering polyalphaolefins, alkylated aromatics, gas-to-liquid (GTL) base fluids, polybutenes, aliphatic diesters, polyolesters, polyalkylene glycols or PAGs and phosphate esters.Other synthetic lubricant base oils such as the silicones, borate esters, perfluoroethers and polyphenylene ethers are considered to have restricted applications due to either high cost or performance limitations and are not considered here.Each of the main synthetic base fluids is described for their chemical and physical properties, manufacture and production, their chemistry, key properties, applications and their implications when used in the environment.

  16. Thermodynamic effects of calcium and iron oxides on crystal phase formation in synthetic gasifier slags containing from 0 to 27wt.% V2O3

    SciTech Connect

    Nakano, Jinichiro; Duchesne, Marc; Bennett, James; Kwong, Kyei -Sing; Nakano, Anna; Hughes, Robin

    2014-11-15

    Thermodynamic phase equilibria in synthetic slags (Al2O3–CaO–FeO–SiO2–V2O3) were investigated with 0–27 wt.% vanadium oxide corresponding to industrial coal–petroleum coke (petcoke) feedstock blends in a simulated gasifier environment. Samples encompassing coal–petcoke mixed slag compositions were equilibrated at 1500 °C in a 64 vol.% CO/36 vol.% CO2 atmosphere (Po2 ≈ 10–8 atm at 1500 °C) for 72 h, followed by rapid water quench, then analyzed by inductively coupled plasma optical emission spectrometry, X-ray diffractometry, and scanning electron microscopy with wavelength dispersive spectroscopy. With increasing CaO content, FeO content, or both; the slag homogeneity region expanded and a composition range exhibiting crystals was reduced. The mullite (Al6Si2O13) crystalline phase was not present in the slags above 9 wt.% FeO while the karelianite (V2O3) crystalline phase was always present in compositions studied if a sufficient amount of vanadium existed in the slag. Furthermore, based on the present experimental equilibrium evaluation, a set of isothermal phase diagrams showing effects of CaO and FeO on thermodynamic phase stabilities in the vanadium-bearing slags is proposed. Some uses of the diagrams for potential industrial practice are discussed.

  17. Synthetic microbial communities☆

    PubMed Central

    Großkopf, Tobias; Soyer, Orkun S

    2014-01-01

    While natural microbial communities are composed of a mix of microbes with often unknown functions, the construction of synthetic microbial communities allows for the generation of defined systems with reduced complexity. Used in a top-down approach, synthetic communities serve as model systems to ask questions about the performance and stability of microbial communities. In a second, bottom-up approach, synthetic microbial communities are used to study which conditions are necessary to generate interaction patterns like symbiosis or competition, and how higher order community structure can emerge from these. Besides their obvious value as model systems to understand the structure, function and evolution of microbial communities as complex dynamical systems, synthetic communities can also open up new avenues for biotechnological applications. PMID:24632350

  18. Analysis of Synthetic Polymers.

    ERIC Educational Resources Information Center

    Smith, Charles G.; And Others

    1989-01-01

    Reviews techniques for the characterization and analysis of synthetic polymers, copolymers, and blends. Includes techniques for structure determination, separation, and quantitation of additives and residual monomers; determination of molecular weight; and the study of thermal properties including degradation mechanisms. (MVL)

  19. Models for synthetic biology

    PubMed Central

    Kaznessis, Yiannis N

    2007-01-01

    Synthetic biological engineering is emerging from biology as a distinct discipline based on quantification. The technologies propelling synthetic biology are not new, nor is the concept of designing novel biological molecules. What is new is the emphasis on system behavior. The objective is the design and construction of new biological devices and systems to deliver useful applications. Numerous synthetic gene circuits have been created in the past decade, including bistable switches, oscillators, and logic gates, and possible applications abound, including biofuels, detectors for biochemical and chemical weapons, disease diagnosis, and gene therapies. More than fifty years after the discovery of the molecular structure of DNA, molecular biology is mature enough for real quantification that is useful for biological engineering applications, similar to the revolution in modeling in chemistry in the 1950s. With the excitement that synthetic biology is generating, the engineering and biological science communities appear remarkably willing to cross disciplinary boundaries toward a common goal. PMID:17986347

  20. What Are Synthetic Cannabinoids?

    MedlinePlus

    ... those produced by marijuana: elevated mood relaxation altered perception —awareness of surrounding objects and conditions symptoms of ... those produced by marijuana: elevated mood relaxation altered perception symptoms of psychosis Synthetic cannabinoids can also cause ...

  1. Synthetic Vision Systems

    NASA Technical Reports Server (NTRS)

    Prinzel, L.J.; Kramer, L.J.

    2009-01-01

    A synthetic vision system is an aircraft cockpit display technology that presents the visual environment external to the aircraft using computer-generated imagery in a manner analogous to how it would appear to the pilot if forward visibility were not restricted. The purpose of this chapter is to review the state of synthetic vision systems, and discuss selected human factors issues that should be considered when designing such displays.

  2. Active synthetic soil

    NASA Technical Reports Server (NTRS)

    Ming, Douglas W. (Inventor); Henninger, Donald L. (Inventor); Allen, Earl R. (Inventor); Golden, Dadigamuwage C. (Inventor)

    1995-01-01

    A synthetic soil/fertilizer for horticultural application having all the agronutrients essential for plant growth is disclosed. The soil comprises a synthetic apatite fertilizer having sulfur, magnesium and micronutrients dispersed in a calcium phosphate matrix, a zeolite cation exchange medium saturated with a charge of potassium and nitrogen cations, and an optional pH buffer. Moisture dissolves the apatite and mobilizes the nutrient elements from the apatite matrix and the zeolite charge sites.

  3. Active synthetic soil

    NASA Technical Reports Server (NTRS)

    Ming, Douglas W. (Inventor); Henninger, Donald L. (Inventor); Allen, Earl R. (Inventor); Golden, Dadigamuwage C. (Inventor)

    1995-01-01

    A synthetic soil/fertilizer for horticultural application having all the agronutrients essential for plant growth is disclosed. The soil comprises a synthetic apatite fertilizer having sulfur, magnesium, and micronutrients dispersed in a calcium phosphate matrix, a zeolite cation exchange medium saturated with a charge of potassium and nitrogen cations, and an optional pH buffer. Moisture dissolves the apatite and mobilizes the nutrient elements from the apatite matrix and the zeolite charge sites.

  4. Synthetic biology and biosecurity.

    PubMed

    Robienski, Jürgen; Simon, Jürgen

    2014-01-01

    This article discusses the conflict fields and legal questions of synthetic biology, esp. concerning biosecurity. A respective jurisprudential discussion has not taken place yet in Germany apart from few statements and recommendations. But in Germany, Europe and the USA, it is generally accepted that a broad discussion is necessary. This is esp. true for the question of biosecurity and the possible dangers arising from Synthetic Biology. PMID:25845204

  5. Nanostructured manganese oxides as highly active water oxidation catalysts: a boost from manganese precursor chemistry.

    PubMed

    Menezes, Prashanth W; Indra, Arindam; Littlewood, Patrick; Schwarze, Michael; Göbel, Caren; Schomäcker, Reinhard; Driess, Matthias

    2014-08-01

    We present a facile synthesis of bioinspired manganese oxides for chemical and photocatalytic water oxidation, starting from a reliable and versatile manganese(II) oxalate single-source precursor (SSP) accessible through an inverse micellar molecular approach. Strikingly, thermal decomposition of the latter precursor in various environments (air, nitrogen, and vacuum) led to the three different mineral phases of bixbyite (Mn2 O3 ), hausmannite (Mn3 O4 ), and manganosite (MnO). Initial chemical water oxidation experiments using ceric ammonium nitrate (CAN) gave the maximum catalytic activity for Mn2 O3 and MnO whereas Mn3 O4 had a limited activity. The substantial increase in the catalytic activity of MnO in chemical water oxidation was demonstrated by the fact that a phase transformation occurs at the surface from nanocrystalline MnO into an amorphous MnOx (1oxidizing agent. Photocatalytic water oxidation in the presence of [Ru(bpy)3 ](2+) (bpy=2,2'-bipyridine) as a sensitizer and peroxodisulfate as an electron acceptor was carried out for all three manganese oxides including the newly formed amorphous MnOx . Both Mn2 O3 and the amorphous MnOx exhibit tremendous enhancement in oxygen evolution during photocatalysis and are much higher in comparison to so far known bioinspired manganese oxides and calcium-manganese oxides. Also, for the first time, a new approach for the representation of activities of water oxidation catalysts has been proposed by determining the amount of accessible manganese centers. PMID:25044528

  6. Differential Synthetic Aperture Ladar

    SciTech Connect

    Stappaerts, E A; Scharlemann, E

    2005-02-07

    We report a differential synthetic aperture ladar (DSAL) concept that relaxes platform and laser requirements compared to conventional SAL. Line-of-sight translation/vibration constraints are reduced by several orders of magnitude, while laser frequency stability is typically relaxed by an order of magnitude. The technique is most advantageous for shorter laser wavelengths, ultraviolet to mid-infrared. Analytical and modeling results, including the effect of speckle and atmospheric turbulence, are presented. Synthetic aperture ladars are of growing interest, and several theoretical and experimental papers have been published on the subject. Compared to RF synthetic aperture radar (SAR), platform/ladar motion and transmitter bandwidth constraints are especially demanding at optical wavelengths. For mid-IR and shorter wavelengths, deviations from a linear trajectory along the synthetic aperture length have to be submicron, or their magnitude must be measured to that precision for compensation. The laser coherence time has to be the synthetic aperture transit time, or transmitter phase has to be recorded and a correction applied on detection.

  7. Automated synthetic scene generation

    NASA Astrophysics Data System (ADS)

    Givens, Ryan N.

    Physics-based simulations generate synthetic imagery to help organizations anticipate system performance of proposed remote sensing systems. However, manually constructing synthetic scenes which are sophisticated enough to capture the complexity of real-world sites can take days to months depending on the size of the site and desired fidelity of the scene. This research, sponsored by the Air Force Research Laboratory's Sensors Directorate, successfully developed an automated approach to fuse high-resolution RGB imagery, lidar data, and hyperspectral imagery and then extract the necessary scene components. The method greatly reduces the time and money required to generate realistic synthetic scenes and developed new approaches to improve material identification using information from all three of the input datasets.

  8. Synthetic battery cycling techniques

    NASA Technical Reports Server (NTRS)

    Leibecki, H. F.; Thaller, L. H.

    1982-01-01

    Synthetic battery cycling makes use of the fast growing capability of computer graphics to illustrate some of the basic characteristics of operation of individual electrodes within an operating electrochemical cell. It can also simulate the operation of an entire string of cells that are used as the energy storage subsystem of a power system. The group of techniques that as a class have been referred to as Synthetic Battery Cycling is developed in part to try to bridge the gap of understanding that exists between single cell characteristics and battery system behavior.

  9. Synthetic guide star generation

    DOEpatents

    Payne, Stephen A [Castro Valley, CA; Page, Ralph H [Castro Valley, CA; Ebbers, Christopher A [Livermore, CA; Beach, Raymond J [Livermore, CA

    2008-06-10

    A system for assisting in observing a celestial object and providing synthetic guide star generation. A lasing system provides radiation at a frequency at or near 938 nm and radiation at a frequency at or near 1583 nm. The lasing system includes a fiber laser operating between 880 nm and 960 nm and a fiber laser operating between 1524 nm and 1650 nm. A frequency-conversion system mixes the radiation and generates light at a frequency at or near 589 nm. A system directs the light at a frequency at or near 589 nm toward the celestial object and provides synthetic guide star generation.

  10. Synthetic guide star generation

    DOEpatents

    Payne, Stephen A.; Page, Ralph H.; Ebbers, Christopher A.; Beach, Raymond J.

    2004-03-09

    A system for assisting in observing a celestial object and providing synthetic guide star generation. A lasing system provides radiation at a frequency at or near 938 nm and radiation at a frequency at or near 1583 nm. The lasing system includes a fiber laser operating between 880 nm and 960 nm and a fiber laser operating between 1524 nm and 1650 nm. A frequency-conversion system mixes the radiation and generates light at a frequency at or near 589 nm. A system directs the light at a frequency at or near 589 nm toward the celestial object and provides synthetic guide star generation.

  11. Synthetic Aperture Radar Interferometry

    NASA Technical Reports Server (NTRS)

    Rosen, P. A.; Hensley, S.; Joughin, I. R.; Li, F.; Madsen, S. N.; Rodriguez, E.; Goldstein, R. M.

    1998-01-01

    Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristics of the surface. This paper reviews the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering.

  12. Biodegradable synthetic bone composites

    DOEpatents

    Liu, Gao; Zhao, Dacheng; Saiz, Eduardo; Tomsia, Antoni P.

    2013-01-01

    The invention provides for a biodegradable synthetic bone composition comprising a biodegradable hydrogel polymer scaffold comprising a plurality of hydrolytically unstable linkages, and an inorganic component; such as a biodegradable poly(hydroxyethylmethacrylate)/hydroxyapatite (pHEMA/HA) hydrogel composite possessing mineral content approximately that of human bone.

  13. Synthetic Vision Workshop 2

    NASA Technical Reports Server (NTRS)

    Kramer, Lynda J. (Compiler)

    1999-01-01

    The second NASA sponsored Workshop on Synthetic/Enhanced Vision (S/EV) Display Systems was conducted January 27-29, 1998 at the NASA Langley Research Center. The purpose of this workshop was to provide a forum for interested parties to discuss topics in the Synthetic Vision (SV) element of the NASA Aviation Safety Program and to encourage those interested parties to participate in the development, prototyping, and implementation of S/EV systems that enhance aviation safety. The SV element addresses the potential safety benefits of synthetic/enhanced vision display systems for low-end general aviation aircraft, high-end general aviation aircraft (business jets), and commercial transports. Attendance at this workshop consisted of about 112 persons including representatives from industry, the FAA, and other government organizations (NOAA, NIMA, etc.). The workshop provided opportunities for interested individuals to give presentations on the state of the art in potentially applicable systems, as well as to discuss areas of research that might be considered for inclusion within the Synthetic Vision Element program to contribute to the reduction of the fatal aircraft accident rate. Panel discussions on topical areas such as databases, displays, certification issues, and sensors were conducted, with time allowed for audience participation.

  14. Synthetic Bursae for Robots

    NASA Technical Reports Server (NTRS)

    Lovchik, Christopher S.

    2005-01-01

    Synthetic bursae are under development for incorporation into robot joints that are actuated by motor-driven cables in a manner similar to that of arthropod joints actuated by muscle-driven tendons. Like natural bursae, the synthetic bursae would serve as cushions and friction reducers. A natural bursa is a thin bladder filled with synovial fluid, which serves to reduce friction and provide a cushion between a bone and a muscle or a tendon. A synthetic bursa would be similar in form and function: It would be, essentially, a compact, soft roller consisting of a bladder filled with a non-Newtonian fluid. The bladder would be constrained to approximately constant volume. The synthetic bursa would cushion an actuator cable against one of the members of a robot joint and would reduce the friction between the cable and the member. Under load, the pressure in the bladder would hold the opposite walls of the bladder apart, making it possible for them to move freely past each other without rubbing.

  15. Synthetic River Valleys

    NASA Astrophysics Data System (ADS)

    Brown, R.; Pasternack, G. B.

    2011-12-01

    The description of fluvial form has evolved from anecdotal descriptions to artistic renderings to 2D plots of cross section or longitudinal profiles and more recently 3D digital models. Synthetic river valleys, artificial 3D topographic models of river topography, have a plethora of potential applications in fluvial geomorphology, and the earth sciences in general, as well as in computer science and ecology. Synthetic river channels have existed implicitly since approximately the 1970s and can be simulated from a variety of approaches spanning the artistic and numerical. An objective method of synthesizing 3D stream topography based on reach scale attributes would be valuable for sizing 3D flumes in the physical and numerical realms, as initial input topography for morphodynamic models, stream restoration design, historical reconstruction, and mechanistic testing of interactions of channel geometric elements. Quite simply - simulation of synthetic channel geometry of prescribed conditions can allow systematic evaluation of the dominant relationships between river flow and geometry. A new model, the control curve method, is presented that uses hierarchically scaled parametric curves in over-lapping 2D planes to create synthetic river valleys. The approach is able to simulate 3D stream geometry from paired 2D descriptions and can allow experimental insight into form-process relationships in addition to visualizing past measurements of channel form that are limited to two dimension descriptions. Results are presented that illustrate the models ability to simulate fluvial topography representative of real world rivers as well as how channel geometric elements can be adjusted. The testing of synthetic river valleys would open up a wealth of knowledge as to why some 3D attributes of river channels are more prevalent than others as well as bridging the gap between the 2D descriptions that have dominated fluvial geomorphology the past century and modern, more complete, 3D

  16. Synthetic plant defense elicitors

    PubMed Central

    Bektas, Yasemin; Eulgem, Thomas

    2015-01-01

    To defend themselves against invading pathogens plants utilize a complex regulatory network that coordinates extensive transcriptional and metabolic reprogramming. Although many of the key players of this immunity-associated network are known, the details of its topology and dynamics are still poorly understood. As an alternative to forward and reverse genetic studies, chemical genetics-related approaches based on bioactive small molecules have gained substantial popularity in the analysis of biological pathways and networks. Use of such molecular probes can allow researchers to access biological space that was previously inaccessible to genetic analyses due to gene redundancy or lethality of mutations. Synthetic elicitors are small drug-like molecules that induce plant defense responses, but are distinct from known natural elicitors of plant immunity. While the discovery of some synthetic elicitors had already been reported in the 1970s, recent breakthroughs in combinatorial chemical synthesis now allow for inexpensive high-throughput screens for bioactive plant defense-inducing compounds. Along with powerful reverse genetics tools and resources available for model plants and crop systems, comprehensive collections of new synthetic elicitors will likely allow plant scientists to study the intricacies of plant defense signaling pathways and networks in an unparalleled fashion. As synthetic elicitors can protect crops from diseases, without the need to be directly toxic for pathogenic organisms, they may also serve as promising alternatives to conventional biocidal pesticides, which often are harmful for the environment, farmers and consumers. Here we are discussing various types of synthetic elicitors that have been used for studies on the plant immune system, their modes-of-action as well as their application in crop protection. PMID:25674095

  17. Relative toxicity of pyrolysis products of some synthetic polymers

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Slattengren, C. L.; Furst, A.; Kourtides, D. A.; Parker, J. A.

    1976-01-01

    Nineteen samples of synthetic polymers were evaluated for relative toxicity in the course of characterizing materials intended for aircraft interior applications. The generic polymers included ABS, chlorinated PVC, polycarbonate, polyphenylene oxide, polyphenylene sulfide, polysulfone, polyaryl sulfone, polyether sulfone, polybismaleimide, and polyvinyl fluoride. Test results are presented, and compared in relative rankings with similar results on cellulosic materials and other synthetic polymers. Under these test conditions, the samples of synthetic polymers were either comparable to or significantly less toxic than the samples of commercial cellulosic materials.

  18. Engineered Asymmetric Synthetic Vesicles

    NASA Astrophysics Data System (ADS)

    Lu, Li; Chiarot, Paul

    2013-11-01

    Synthetic vesicles are small, fluid-filled spheres that are enclosed by a bilayer of lipid molecules. They can be used as models for investigating membrane biology and as delivery vehicles for pharmaceuticals. In practice, it is difficult to simultaneously control membrane asymmetry, unilamellarity, vesicle size, vesicle-to-vesicle uniformity, and luminal content. Membrane asymmetry, where each leaflet of the bilayer is composed of different lipids, is of particular importance as it is a feature of most natural membranes. In this study, we leverage microfluidic technology to build asymmetric vesicles at high-throughput. We use the precise flow control offered by microfluidic devices to make highly uniform emulsions, with controlled internal content, that serve as templates to build the synthetic vesicles. Flow focusing, dielectrophoretic steering, and interfacial lipid self-assembly are critical procedures performed on-chip to produce the vesicles. Fluorescent and confocal microscopy are used to evaluate the vesicle characteristics.

  19. Wholly Synthetic Molecular Machines.

    PubMed

    Cheng, Chuyang; Stoddart, J Fraser

    2016-06-17

    The past quarter of a century has witnessed an increasing engagement on the part of physicists and chemists in the design and synthesis of molecular machines de novo. This minireview traces the development of artificial molecular machines from their prototypes in the form of shuttles and switches to their emergence as motors and pumps where supplies of energy in the form of chemical fuel, electrochemical potential and light activation become a minimum requirement for them to function away from equilibrium. The challenge facing this rapidly growing community of scientists and engineers today is one of putting wholly synthetic molecules to work, both individually and as collections. Here, we highlight some of the recent conceptual and practical advances relating to the operation of wholly synthetic rotary and linear motors. PMID:26833859

  20. Synthetic ligaments. Current status.

    PubMed

    Funk, F J

    1987-06-01

    Many techniques for ligamentous reconstruction have been developed in recent years. In the United States, injuries of the knee have been increasingly treated with innovative methods of surgical reconstruction, most of which have used normal structures. There are obvious theoretic advantages in using synthetic materials that might simplify surgery, spare normal tissues, and possibly facilitate stronger repairs. To these ends, several synthetic substances have been used experimentally and clinically. This is a brief summary of eight of the materials that have been or are being investigated in the United States. Some are no longer in use, others are currently being used in clinical trials. As of this writing, only the Gortex ligament has received a general device release from the Food and Drug Administration (FDA). PMID:3034461

  1. Synthetic Foveal Imaging Technology

    NASA Technical Reports Server (NTRS)

    Monacos, Steve P. (Inventor); Hoenk, Michael E. (Inventor); Nikzad, Shouleh (Inventor)

    2013-01-01

    Apparatuses and methods are disclosed that create a synthetic fovea in order to identify and highlight interesting portions of an image for further processing and rapid response. Synthetic foveal imaging implements a parallel processing architecture that uses reprogrammable logic to implement embedded, distributed, real-time foveal image processing from different sensor types while simultaneously allowing for lossless storage and retrieval of raw image data. Real-time, distributed, adaptive processing of multi-tap image sensors with coordinated processing hardware used for each output tap is enabled. In mosaic focal planes, a parallel-processing network can be implemented that treats the mosaic focal plane as a single ensemble rather than a set of isolated sensors. Various applications are enabled for imaging and robotic vision where processing and responding to enormous amounts of data quickly and efficiently is important.

  2. A synthetic zero air standard

    NASA Astrophysics Data System (ADS)

    Pearce, Ruth

    2016-04-01

    A Synthetic Zero Air Standard R. E. Hill-Pearce, K. V. Resner, D. R. Worton, P. J. Brewer The National Physical Laboratory Teddington, Middlesex TW11 0LW UK We present work towards providing traceability for measurements of high impact greenhouse gases identified by the World Meteorological Organisation (WMO) as critical for global monitoring. Standards for these components are required with challengingly low uncertainties to improve the quality assurance and control processes used for the global networks to better assess climate trends. Currently the WMO compatibility goals require reference standards with uncertainties of < 100 nmolmol‑1 for CO2 (northern hemisphere) and < 2 nmolmol‑1 for CH4 and CO. High purity zero gas is required for both the balance gas in the preparation of reference standards and for baseline calibrations of instrumentation. Quantification of the amount fraction of the target components in the zero gas is a significant contributor to the uncertainty and is challenging due to limited availability of reference standard at the amount fraction of the measurand and limited analytical techniques with sufficient detection limits. A novel dilutor was used to blend NPL Primary Reference Gas Mixtures containing CO2, CH4 and CO at atmospheric amount fractions with a zero gas under test. Several mixtures were generated with nominal dilution ratios ranging from 2000:1 to 350:1. The baseline of two cavity ring down spectrometers was calibrated using the zero gas under test after purification by oxidative removal of CO and hydrocarbons to < 1 nmolmol‑1 (SAES PS15-GC50) followed by the removal of CO2 and water vapour to < 100 pmolmol‑1 (SAES MC190). Using the standard addition method.[1] we have quantified the amount fraction of CO, CO2, and CH4 in scrubbed whole air (Scott Marrin) and NPL synthetic zero air. This is the first synthetic zero air standard with a matrix of N2, O2 and Ar closely matching ambient composition with gravimetrically

  3. Raman spectrum of natural and synthetic stishovite

    USGS Publications Warehouse

    Hemley, R.J.; Mao, Ho-kwang; Chao, E.C.T.

    1986-01-01

    Raman spectra of natural and synthetic samples of stishovite have been measured with a micro-optical spectrometer system. These spectra have a pattern that is characteristic of rutile-structured oxides. The spectrum of synthetic stishovite is characterized by well-resolved bands at 231, 589, 753, and 967 cm-1, which are assigned as the B1g, Eg, A1g, and B2g fundamentals, respectively, of the first-order Raman spectrum of the ideal, ordered structure. Natural stishovite obtained from Meteor Crater, Arizona has a first-order Raman spectrum that is fully consistent with that of the synthetic material. The observed spectrum of the natural sample, however, is weaker and has bands in addition to those identified as fundamentals in the spectrum of the synthetic material. A broad band at ???475 cm-1 may be indicative of glass or contaminants derived from the extraction procedure. Alternatively, this band may arise from multiphonon scattering that is enhanced by poor crystallinity or structural disorder in the natural shocked sample. ?? 1986 Springer-Verlag.

  4. Bio-based polycarbonate as synthetic toolbox.

    PubMed

    Hauenstein, O; Agarwal, S; Greiner, A

    2016-01-01

    Completely bio-based poly(limonene carbonate) is a thermoplastic polymer, which can be synthesized by copolymerization of limonene oxide (derived from limonene, which is found in orange peel) and CO2. Poly(limonene carbonate) has one double bond per repeating unit that can be exploited for further chemical modifications. These chemical modifications allow the tuning of the properties of the aliphatic polycarbonate in nearly any direction. Here we show synthetic routes to demonstrate that poly(limonene carbonate) is the perfect green platform polymer, from which many functional materials can be derived. The relevant examples presented in this study are the transformation from an engineering thermoplastic into a rubber, addition of permanent antibacterial activity, hydrophilization and even pH-dependent water solubility of the polycarbonate. Finally, we show a synthetic route to yield the completely saturated counterpart that exhibits improved heat processability due to lower reactivity. PMID:27302694

  5. Bio-based polycarbonate as synthetic toolbox

    PubMed Central

    Hauenstein, O.; Agarwal, S.; Greiner, A.

    2016-01-01

    Completely bio-based poly(limonene carbonate) is a thermoplastic polymer, which can be synthesized by copolymerization of limonene oxide (derived from limonene, which is found in orange peel) and CO2. Poly(limonene carbonate) has one double bond per repeating unit that can be exploited for further chemical modifications. These chemical modifications allow the tuning of the properties of the aliphatic polycarbonate in nearly any direction. Here we show synthetic routes to demonstrate that poly(limonene carbonate) is the perfect green platform polymer, from which many functional materials can be derived. The relevant examples presented in this study are the transformation from an engineering thermoplastic into a rubber, addition of permanent antibacterial activity, hydrophilization and even pH-dependent water solubility of the polycarbonate. Finally, we show a synthetic route to yield the completely saturated counterpart that exhibits improved heat processability due to lower reactivity. PMID:27302694

  6. Bio-based polycarbonate as synthetic toolbox

    NASA Astrophysics Data System (ADS)

    Hauenstein, O.; Agarwal, S.; Greiner, A.

    2016-06-01

    Completely bio-based poly(limonene carbonate) is a thermoplastic polymer, which can be synthesized by copolymerization of limonene oxide (derived from limonene, which is found in orange peel) and CO2. Poly(limonene carbonate) has one double bond per repeating unit that can be exploited for further chemical modifications. These chemical modifications allow the tuning of the properties of the aliphatic polycarbonate in nearly any direction. Here we show synthetic routes to demonstrate that poly(limonene carbonate) is the perfect green platform polymer, from which many functional materials can be derived. The relevant examples presented in this study are the transformation from an engineering thermoplastic into a rubber, addition of permanent antibacterial activity, hydrophilization and even pH-dependent water solubility of the polycarbonate. Finally, we show a synthetic route to yield the completely saturated counterpart that exhibits improved heat processability due to lower reactivity.

  7. Method for producing and regenerating a synthetic CO[sub 2] acceptor

    DOEpatents

    Lancet, M. S.; Curran, G. P.; Gorin, E.

    1982-05-18

    A method is described for producing a synthetic CO[sub 2] acceptor by feeding a mixture of finely divided silica and at least one finely divided calcium compound selected from the group consisting of calcium oxide and calcium carbonate to a fluidized bed; operating the fluidized bed at suitable conditions to produce pellets of synthetic CO[sub 2] acceptor and recovering the pellets of synthetic CO[sub 2] acceptor from the fluidized bed. Optionally, spent synthetic CO[sub 2] acceptor can be charged to the fluidized bed to produce regenerated pellets of synthetic CO[sub 2] acceptor. 1 fig.

  8. Method for producing and regenerating a synthetic CO.sub.2 acceptor

    DOEpatents

    Lancet, Michael S [Pittsburgh, PA; Curran, George P [Pittsburgh, PA; Gorin, Everett [San Rafael, CA

    1982-01-01

    A method for producing a synthetic CO.sub.2 acceptor by feeding a mixture of finely divided silica and at least one finely divided calcium compound selected from the group consisting of calcium oxide and calcium carbonate to a fluidized bed; operating the fluidized bed at suitable conditions to produce pellets of synthetic CO.sub.2 acceptor and recovering the pellets of synthetic CO.sub.2 acceptor from the fluidized bed. Optionally, spent synthetic CO.sub.2 acceptor can be charged to the fluidized bed to produce regenerated pellets of synthetic CO.sub.2 acceptor.

  9. Synthesis of Pyrroloquinones via a CAN Mediated Oxidative Free Radical Reaction of 1,3-Dicarbonyl Compounds with Aminoquinones

    PubMed Central

    Nguyen, Thao; Nadkarni, Dwayaja; Dutta, Shilpa; Xu, Su; Kim, Sanghun; Murugesan, Srinivasan; Velu, Sadanandan

    2015-01-01

    Pyrroloquinone ring systems are important structural units present in many biologically active molecules including a number of marine alkaloids. For example, they are found in a series of marine metabolites, such as tsitsikammamines, zyzzyanones, wakayin, and terreusinone. Several of these alkaloids have exhibited antimicrobial, antimalarial, antifungal, antitumor, and photoprotecting activities. Synthesis of pyrroloquinone unit is the key step in the synthesis of many of these important organic molecules. Here, we present a ceric (IV) ammonium nitrate (CAN) mediated oxidative free radical cyclization reaction of 1,3-dicarbonyl compounds with aminoquinones as a facile methodology for making various substituted pyrroloquinones. 1,3-dicarbonyl compounds used in this study are ethyl acetoacetate, acetylacetone, benzoyl acetone, and N,N-dimethyl acetoacetamide. The aminoquinones used in this study are 2-(benzylamino)naphthalene-1,4-dione and 6-(benzylamino)-1-tosyl-1H-indole-4,7-dione. The yields of the synthesized pyrroloquinones ranged from 23–91%. PMID:25705550

  10. Analog synthetic biology.

    PubMed

    Sarpeshkar, R

    2014-03-28

    We analyse the pros and cons of analog versus digital computation in living cells. Our analysis is based on fundamental laws of noise in gene and protein expression, which set limits on the energy, time, space, molecular count and part-count resources needed to compute at a given level of precision. We conclude that analog computation is significantly more efficient in its use of resources than deterministic digital computation even at relatively high levels of precision in the cell. Based on this analysis, we conclude that synthetic biology must use analog, collective analog, probabilistic and hybrid analog-digital computational approaches; otherwise, even relatively simple synthetic computations in cells such as addition will exceed energy and molecular-count budgets. We present schematics for efficiently representing analog DNA-protein computation in cells. Analog electronic flow in subthreshold transistors and analog molecular flux in chemical reactions obey Boltzmann exponential laws of thermodynamics and are described by astoundingly similar logarithmic electrochemical potentials. Therefore, cytomorphic circuits can help to map circuit designs between electronic and biochemical domains. We review recent work that uses positive-feedback linearization circuits to architect wide-dynamic-range logarithmic analog computation in Escherichia coli using three transcription factors, nearly two orders of magnitude more efficient in parts than prior digital implementations. PMID:24567476

  11. Analog synthetic biology

    PubMed Central

    Sarpeshkar, R.

    2014-01-01

    We analyse the pros and cons of analog versus digital computation in living cells. Our analysis is based on fundamental laws of noise in gene and protein expression, which set limits on the energy, time, space, molecular count and part-count resources needed to compute at a given level of precision. We conclude that analog computation is significantly more efficient in its use of resources than deterministic digital computation even at relatively high levels of precision in the cell. Based on this analysis, we conclude that synthetic biology must use analog, collective analog, probabilistic and hybrid analog–digital computational approaches; otherwise, even relatively simple synthetic computations in cells such as addition will exceed energy and molecular-count budgets. We present schematics for efficiently representing analog DNA–protein computation in cells. Analog electronic flow in subthreshold transistors and analog molecular flux in chemical reactions obey Boltzmann exponential laws of thermodynamics and are described by astoundingly similar logarithmic electrochemical potentials. Therefore, cytomorphic circuits can help to map circuit designs between electronic and biochemical domains. We review recent work that uses positive-feedback linearization circuits to architect wide-dynamic-range logarithmic analog computation in Escherichia coli using three transcription factors, nearly two orders of magnitude more efficient in parts than prior digital implementations. PMID:24567476

  12. Progress toward synthetic cells.

    PubMed

    Blain, J Craig; Szostak, Jack W

    2014-01-01

    The complexity of even the simplest known life forms makes efforts to synthesize living cells from inanimate components seem like a daunting task. However, recent progress toward the creation of synthetic cells, ranging from simple protocells to artificial cells approaching the complexity of bacteria, suggests that the synthesis of life is now a realistic goal. Protocell research, fueled by advances in the biophysics of primitive membranes and the chemistry of nucleic acid replication, is providing new insights into the origin of cellular life. Parallel efforts to construct more complex artificial cells, incorporating translational machinery and protein enzymes, are providing information about the requirements for protein-based life. We discuss recent advances and remaining challenges in the synthesis of artificial cells, the possibility of creating new forms of life distinct from existing biology, and the promise of this research for gaining a deeper understanding of the nature of living systems. PMID:24606140

  13. Multidimensional synthetic estimation filter

    NASA Technical Reports Server (NTRS)

    Monroe, Stanley E., Jr.; Juday, Richard D.

    1990-01-01

    The synthetic estimation filter (SEF) crafts an affine variation into its response to a changing parameter (e.g. scale or rotation). Sets of such filters are used in an estimation correlator to reduce the number of filters required for a given tracking accuracy. By overspecifying the system (one more SEF than parameters to be tracked), the ratio of correlation responses between filters forms a robust estimator into the spanned domain of the parameters. Previous results dealt with a laboratory correlator which could track a single parameter. This paper explores the SEF and the estimator's extension to more dimensions. A 2D example is given in which a reduction of filters from 25 to 3 is demonstrated to span a 4-degree square portion of pose space.

  14. Synthetic antibiofilm peptides.

    PubMed

    de la Fuente-Núñez, César; Cardoso, Marlon Henrique; de Souza Cândido, Elizabete; Franco, Octavio Luiz; Hancock, Robert E W

    2016-05-01

    Bacteria predominantly exist as multicellular aggregates known as biofilms that are associated with at least two thirds of all infections and exhibit increased adaptive resistance to conventional antibiotic therapies. Therefore, biofilms are major contributors to the global health problem of antibiotic resistance, and novel approaches to counter them are urgently needed. Small molecules of the innate immune system called host defense peptides (HDPs) have emerged as promising templates for the design of potent, broad-spectrum antibiofilm agents. Here, we review recent developments in the new field of synthetic antibiofilm peptides, including mechanistic insights, synergistic interactions with available antibiotics, and their potential as novel antimicrobials against persistent infections caused by biofilms. This article is part of a Special Issue entitled: Antimicrobial peptides edited by Karl Lohner and Kai Hilpert. PMID:26724202

  15. Synthetic Genomics and Synthetic Biology Applications Between Hopes and Concerns

    PubMed Central

    König, Harald; Frank, Daniel; Heil, Reinhard; Coenen, Christopher

    2013-01-01

    New organisms and biological systems designed to satisfy human needs are among the aims of synthetic genomics and synthetic biology. Synthetic biology seeks to model and construct biological components, functions and organisms that do not exist in nature or to redesign existing biological systems to perform new functions. Synthetic genomics, on the other hand, encompasses technologies for the generation of chemically-synthesized whole genomes or larger parts of genomes, allowing to simultaneously engineer a myriad of changes to the genetic material of organisms. Engineering complex functions or new organisms in synthetic biology are thus progressively becoming dependent on and converging with synthetic genomics. While applications from both areas have been predicted to offer great benefits by making possible new drugs, renewable chemicals or clean energy, they have also given rise to concerns about new safety, environmental and socio-economic risks – stirring an increasingly polarizing debate. Here we intend to provide an overview on recent progress in biomedical and biotechnological applications of synthetic genomics and synthetic biology as well as on arguments and evidence related to their possible benefits, risks and governance implications. PMID:23997647

  16. Reconstitution of the water-oxidizing complex in manganese-depleted photosystem II preparations using synthetic binuclear Mn(II) and Mn(IV) complexes: production of hydrogen peroxide.

    PubMed

    Nagata, Toshi; Nagasawa, Takayuki; Zharmukhamedov, Sergei K; Klimov, Vyacheslav V; Allakhverdiev, Suleyman I

    2007-01-01

    Reconstitution of Mn-depleted PSII particles with synthetic binuclear Mn complexes (one Mn(II)(2) complex and one Mn(IV)(2) complex) was examined. In both cases the electron-transfer rates in the reconstituted systems were found to be up to 75-82% of that measured in native PSII but the oxygen evolution activity remained lower (<5-40%). However, hydrogen peroxide was also produced by the reconstituted samples. These samples therefore represent a new type of reconstituted PSII that generates hydrogen peroxide as the final product in reconstituted PSII centers. PMID:17437183

  17. Advancing Sustainable Catalysis with Magnetite Surface Modification and Synthetic Applications

    EPA Science Inventory

    This article surveys the recent developments in the synthesis, surface modification, and synthetic applications of magnetitenanoparticles. The emergence of iron(II,III) oxide (triiron tetraoxide or magnetite; Fe3O4, or FeO•Fe2O3) nanoparticles as a sustainable support in het...

  18. METAL OXIDE NANOPARTICLES

    SciTech Connect

    FERNANDEZ-GARCIA,M.; RODGRIGUEZ, J.A.

    2007-10-01

    This chapter covers the fundamental science, synthesis, characterization, physicochemical properties and applications of oxide nanomaterials. Explains fundamental aspects that determine the growth and behavior of these systems, briefly examines synthetic procedures using bottom-up and top-down fabrication technologies, discusses the sophisticated experimental techniques and state of the art theory results used to characterize the physico-chemical properties of oxide solids and describe the current knowledge concerning key oxide materials with important technological applications.

  19. A synthetic approach to abiogenesis.

    PubMed

    Attwater, James; Holliger, Philipp

    2014-05-01

    Synthetic biology seeks to probe fundamental aspects of biological form and function by construction (resynthesis) rather than deconstruction (analysis). Here we discuss how such an approach could be applied to assemble synthetic quasibiological systems able to replicate and evolve, illuminating universal properties of life and the search for its origins. PMID:24781322

  20. Synthetic Foveal Imaging Technology

    NASA Technical Reports Server (NTRS)

    Hoenk, Michael; Monacos, Steve; Nikzad, Shouleh

    2009-01-01

    Synthetic Foveal imaging Technology (SyFT) is an emerging discipline of image capture and image-data processing that offers the prospect of greatly increased capabilities for real-time processing of large, high-resolution images (including mosaic images) for such purposes as automated recognition and tracking of moving objects of interest. SyFT offers a solution to the image-data processing problem arising from the proposed development of gigapixel mosaic focal-plane image-detector assemblies for very wide field-of-view imaging with high resolution for detecting and tracking sparse objects or events within narrow subfields of view. In order to identify and track the objects or events without the means of dynamic adaptation to be afforded by SyFT, it would be necessary to post-process data from an image-data space consisting of terabytes of data. Such post-processing would be time-consuming and, as a consequence, could result in missing significant events that could not be observed at all due to the time evolution of such events or could not be observed at required levels of fidelity without such real-time adaptations as adjusting focal-plane operating conditions or aiming of the focal plane in different directions to track such events. The basic concept of foveal imaging is straightforward: In imitation of a natural eye, a foveal-vision image sensor is designed to offer higher resolution in a small region of interest (ROI) within its field of view. Foveal vision reduces the amount of unwanted information that must be transferred from the image sensor to external image-data-processing circuitry. The aforementioned basic concept is not new in itself: indeed, image sensors based on these concepts have been described in several previous NASA Tech Briefs articles. Active-pixel integrated-circuit image sensors that can be programmed in real time to effect foveal artificial vision on demand are one such example. What is new in SyFT is a synergistic combination of recent

  1. Bacterial degradation of natural and synthetic rubber.

    PubMed

    Bode, H B; Kerkhoff, K; Jendrossek, D

    2001-01-01

    The degradation of natural rubber (NR), synthetic poly(cis-1,4-isoprene) (SR), and cross-linked NR (latex gloves) by Gram-positive and Gram-negative bacteria was analyzed by weight loss, gel permeation chromatography, and determination of the protein content. Weight losses of 11-18% and an increase in protein up to 850 microg/mL after incubation of Nocardia sp. DSMZ43191, Streptomyces coelicolor, Streptomyces griseus, bacterial isolate 18a, Acinetobacter calcoaceticus, and Xanthomonas sp. with latex gloves as a carbon source indicated degradation of the polymer. An increase of protein up to 1250 microg/mL was obtained upon incubation of the bacteria with SR. No or only little weight losses and no increase in the protein content were found for nondegrading control strains such as Streptomyces lividans and Streptomyces exfoliatus and for mutants of degrading strains of S. coelicolor and S. griseus, which have been identified by their inability to produce clearing zones on opaque latex agar. Measurement of the average molecular weight of synthetic rubber before and after degradation showed a time-dependent shift to lower values for the degrading strains. Diketone derivates of oligo(cis-1,4-isoprene) were identified as metabolites of rubber degradation. An oxidative degradation pathway of poly(cis-1,4-isoprene) to acetyl-coenzymeA and propionyl-coenzymeA by beta-oxidation is suggested for bacterial degradation of isoprene rubber. PMID:11749186

  2. Synthetic cannabis and respiratory depression.

    PubMed

    Jinwala, Felecia N; Gupta, Mayank

    2012-12-01

    In recent years, synthetic cannabis use has been increasing in appeal among adolescents, and its use is now at a 30 year peak among high school seniors. The constituents of synthetic cannabis are difficult to monitor, given the drug's easy accessibility. Currently, 40 U.S. states have banned the distribution and use of some known synthetic cannabinoids, and have included these drugs in the Schedule I category. The depressive respiratory effect in humans caused by synthetic cannabis inhalation has not been thoroughly investigated in the medical literature. We are the first to report, to our knowledge, two cases of self-reported synthetic cannabis use leading to respiratory depression and necessary intubation. PMID:23234589

  3. Recent advances in synthetic biosafety

    PubMed Central

    Simon, Anna J.; Ellington, Andrew D.

    2016-01-01

    Synthetically engineered organisms hold promise for a broad range of medical, environmental, and industrial applications. Organisms can potentially be designed, for example, for the inexpensive and environmentally benign synthesis of pharmaceuticals and industrial chemicals, for the cleanup of environmental pollutants, and potentially even for biomedical applications such as the targeting of specific diseases or tissues. However, the use of synthetically engineered organisms comes with several reasonable safety concerns, one of which is that the organisms or their genes could escape their intended habitats and cause environmental disruption. Here we review key recent developments in this emerging field of synthetic biocontainment and discuss further developments that might be necessary for the widespread use of synthetic organisms. Specifically, we discuss the history and modern development of three strategies for the containment of synthetic microbes: addiction to an exogenously supplied ligand; self-killing outside of a designated environment; and self-destroying encoded DNA circuitry outside of a designated environment.

  4. Synthetic antimicrobial peptide design.

    PubMed

    Powell, W A; Catranis, C M; Maynard, C A

    1995-01-01

    To guide the design of potential plant pathogen-resistance genes, synthetic variants of naturally occurring antimicrobial gene products were evaluated. Five 20-amino acid (ESF1, ESF4, ESF5, ESF6, ESF13), one 18-amino acid (ESF12), and one 17-amino acid (ESF17) amphipathic peptide sequences were designed, synthesized, and tested with in vitro bioassays. Positive charges on the hydrophilic side of the peptide were shown to be essential for antifungal activity, yet the number of positive charges could be varied with little or no change in activity. The size could be reduced to 18 amino acids, but at 17 amino acids a significant reduction in activity was observed. ESF1, 5, 6, and 12 peptides were inhibitory to the germination of conidia from Cryphonectria parasitica, Fusarium oxysporum f. sp. lycopersici, and Septoria musiva but did not inhibit the germination of pollen from Castanea mollissima and Salix lucida. ESF12 also had no effect on the germination of Malus sylvestris and Lycopersicon esculentum pollen, but inhibited the growth of the bacteria Agrobacterium tumefaciens, Erwinia amylovora, and Pseudomonas syringae. The minimal inhibitory concentrations of the active ESF peptides were similar to those of the naturally occurring control peptides, magainin II and cecropin B. The significant differential in sensitivity between the microbes and plant cells indicated that the active ESF peptides are potentially useful models for designing plant pathogen-resistance genes. PMID:7579625

  5. Interferometric synthetic aperture microscopy

    NASA Astrophysics Data System (ADS)

    Ralston, Tyler S.; Marks, Daniel L.; Scott Carney, P.; Boppart, Stephen A.

    2007-02-01

    State-of-the-art methods in high-resolution three-dimensional optical microscopy require that the focus be scanned through the entire region of interest. However, an analysis of the physics of the light-sample interaction reveals that the Fourier-space coverage is independent of depth. Here we show that, by solving the inverse scattering problem for interference microscopy, computed reconstruction yields volumes with a resolution in all planes that is equivalent to the resolution achieved only at the focal plane for conventional high-resolution microscopy. In short, the entire illuminated volume has spatially invariant resolution, thus eliminating the compromise between resolution and depth of field. We describe and demonstrate a novel computational image-formation technique called interferometric synthetic aperture microscopy (ISAM). ISAM has the potential to broadly impact real-time three-dimensional microscopy and analysis in the fields of cell and tumour biology, as well as in clinical diagnosis where in vivo imaging is preferable to biopsy.

  6. Interferometric synthetic aperture microscopy

    NASA Astrophysics Data System (ADS)

    Ralston, Tyler S.

    State-of-the-art interferometric microscopies have problems representing objects that lie outside of the focus because the defocus and diffraction effects are not accounted for in the processing. These problems occur because of the lack of comprehensive models to include the scattering effects in the processing. In this dissertation, a new modality in three-dimensional (3D) optical microscopy, Interferometric Synthetic Aperture Microscopy (ISAM), is introduced to account for the scattering effects. Comprehensive models for interferometric microscopy, such as optical coherence tomography (OCT) are developed, for which forward, adjoint, normal, and inverse operators are formulated. Using an accurate model for the probe beam, the resulting algorithms demonstrate accurate linear estimation of the susceptibility of an object from the interferometric data. Using the regularized least squares solution, an ISAM reconstruction of underlying object structure having spatially invariant resolution is obtained from simulated and experimental interferometric data, even in regions outside of the focal plane of the lens. Two-dimensional (2D) and 3D interferometric data is used to resolve objects outside of the confocal region with minimal loss of resolution, unlike in OCT. Therefore, high-resolution details are recovered from outside of the confocal region. Models and solutions are presented for the planar-scanned, the rotationally scanned, and the full-field illuminated geometry. The models and algorithms presented account for the effects of a finite beam width, the source spectrum, the illumination and collection fields, as well as defocus, diffraction and dispersion effects.

  7. Synthetic retinoids in dermatology

    PubMed Central

    Heller, Elizabeth H.; Shiffman, Norman J.

    1985-01-01

    The potential of vitamin A, or retinol, in the treatment of a variety of skin diseases has long been recognized, but because of serious toxic effects this substance generally could not be used. The recent development and marketing of two relatively nontoxic synthetic analogues, which are known as retinoids, has made it possible to treat some of the diseases that are resistant to standard forms of therapy. Isotretinoin is very effective in cystic and conglobate acne, while etretinate is especially useful in the more severe forms of psoriasis. Good results have also been obtained in other disorders of keratinization. Vitamin A and its derivatives apparently have an antineoplastic effect as well and may come to be used in both the prevention and the treatment of epithelial cancer. In many of these diseases the retinoids act by enhancing the normal differentiation and proliferation of epidermal tissues, but the exact mechanisms are not well understood. Their influence on the intracellular polyamines that control the synthesis of nucleic acids and proteins may be an important factor. Although the retinoids have few serious systemic effects, they are teratogenic, and because they persist in the body their use in women of childbearing potential is limited. ImagesFig. 3 PMID:3158386

  8. Computing with synthetic protocells.

    PubMed

    Courbet, Alexis; Molina, Franck; Amar, Patrick

    2015-09-01

    In this article we present a new kind of computing device that uses biochemical reactions networks as building blocks to implement logic gates. The architecture of a computing machine relies on these generic and composable building blocks, computation units, that can be used in multiple instances to perform complex boolean functions. Standard logical operations are implemented by biochemical networks, encapsulated and insulated within synthetic vesicles called protocells. These protocells are capable of exchanging energy and information with each other through transmembrane electron transfer. In the paradigm of computation we propose, protoputing, a machine can solve only one problem and therefore has to be built specifically. Thus, the programming phase in the standard computing paradigm is represented in our approach by the set of assembly instructions (specific attachments) that directs the wiring of the protocells that constitute the machine itself. To demonstrate the computing power of protocellular machines, we apply it to solve a NP-complete problem, known to be very demanding in computing power, the 3-SAT problem. We show how to program the assembly of a machine that can verify the satisfiability of a given boolean formula. Then we show how to use the massive parallelism of these machines to verify in less than 20 min all the valuations of the input variables and output a fluorescent signal when the formula is satisfiable or no signal at all otherwise. PMID:25969126

  9. Synthetic biology: lessons from the history of synthetic organic chemistry.

    PubMed

    Yeh, Brian J; Lim, Wendell A

    2007-09-01

    The mid-nineteenth century saw the development of a radical new direction in chemistry: instead of simply analyzing existing molecules, chemists began to synthesize them--including molecules that did not exist in nature. The combination of this new synthetic approach with more traditional analytical approaches revolutionized chemistry, leading to a deep understanding of the fundamental principles of chemical structure and reactivity and to the emergence of the modern pharmaceutical and chemical industries. The history of synthetic chemistry offers a possible roadmap for the development and impact of synthetic biology, a nascent field in which the goal is to build novel biological systems. PMID:17710092

  10. GL-V9, a new synthetic flavonoid derivative, ameliorates DSS-induced colitis against oxidative stress by up-regulating Trx-1 expression via activation of AMPK/FOXO3a pathway.

    PubMed

    Zhao, Yue; Sun, Yang; Ding, Youxiang; Wang, Xiaoping; Zhou, Yuxin; Li, Wenjun; Huang, Shaoliang; Li, Zhiyu; Kong, Lingyi; Guo, Qinglong; Lu, Na

    2015-09-22

    GL-V9, a new synthesized flavonoid derivative, has been reported to possess anti-cancer properties in our previous studies. Uncontrolled overproduction of reactive oxygen species (ROS) has been implicated in oxidative damage of inflammatory bowel disease (IBD). In this study, we aimed to investigate the protective effect of GL-V9 against dextran sulfate sodium (DSS)-induced colitis. GL-V9 attenuated DSS-induced body weight loss, colon length shortening and colonic pathological damage. GL-V9 also inhibited inflammatory cells infiltration and decreased myeloperoxidase (MPO) and inducible nitric oxide synthase (iNOS) activities. Moreover, GL-V9 inhibited ROS and malondialdehyde (MDA) generation, but enhanced superoxide dismutase (SOD), glutathione (GSH) and total antioxidant capacity. GL-V9 reduced pro-inflammatory cytokines production in serum and colon as well. Mechanically, GL-V9 could increase Trx-1 via activation of AMPK/FOXO3a to suppress DSS-induced colonic oxidative stress. Furthermore, GL-V9 decreased pro-inflammatory cytokines and ROS production and increased the antioxidant defenses in the mouse macrophage cells RAW264.7 by promoting Trx-1 expression. In conclusion, our study demonstrated that GL-V9 attenuated DSS-induced colitis against oxidative stress by up-regulating Trx-1 via activation of AMPK/FOXO3a pathway, suggesting that GL-V9 might be a potential effective drug for colitis. PMID:26327408

  11. GL-V9, a new synthetic flavonoid derivative, ameliorates DSS-induced colitis against oxidative stress by up-regulating Trx-1 expression via activation of AMPK/FOXO3a pathway

    PubMed Central

    Ding, Youxiang; Wang, Xiaoping; Zhou, Yuxin; Li, Wenjun; Huang, Shaoliang; Li, Zhiyu; Kong, Lingyi; Guo, Qinglong; Lu, Na

    2015-01-01

    GL-V9, a new synthesized flavonoid derivative, has been reported to possess anti-cancer properties in our previous studies. Uncontrolled overproduction of reactive oxygen species (ROS) has been implicated in oxidative damage of inflammatory bowel disease (IBD). In this study, we aimed to investigate the protective effect of GL-V9 against dextran sulfate sodium (DSS)-induced colitis. GL-V9 attenuated DSS-induced body weight loss, colon length shortening and colonic pathological damage. GL-V9 also inhibited inflammatory cells infiltration and decreased myeloperoxidase (MPO) and inducible nitric oxide synthase (iNOS) activities. Moreover, GL-V9 inhibited ROS and malondialdehyde (MDA) generation, but enhanced superoxide dismutase (SOD), glutathione (GSH) and total antioxidant capacity. GL-V9 reduced pro-inflammatory cytokines production in serum and colon as well. Mechanically, GL-V9 could increase Trx-1 via activation of AMPK/FOXO3a to suppress DSS-induced colonic oxidative stress. Furthermore, GL-V9 decreased pro-inflammatory cytokines and ROS production and increased the antioxidant defenses in the mouse macrophage cells RAW264.7 by promoting Trx-1 expression. In conclusion, our study demonstrated that GL-V9 attenuated DSS-induced colitis against oxidative stress by up-regulating Trx-1 via activation of AMPK/FOXO3a pathway, suggesting that GL-V9 might be a potential effective drug for colitis. PMID:26327408

  12. Distributed and collaborative synthetic environments

    NASA Technical Reports Server (NTRS)

    Bajaj, Chandrajit L.; Bernardini, Fausto

    1995-01-01

    Fast graphics workstations and increased computing power, together with improved interface technologies, have created new and diverse possibilities for developing and interacting with synthetic environments. A synthetic environment system is generally characterized by input/output devices that constitute the interface between the human senses and the synthetic environment generated by the computer; and a computation system running a real-time simulation of the environment. A basic need of a synthetic environment system is that of giving the user a plausible reproduction of the visual aspect of the objects with which he is interacting. The goal of our Shastra research project is to provide a substrate of geometric data structures and algorithms which allow the distributed construction and modification of the environment, efficient querying of objects attributes, collaborative interaction with the environment, fast computation of collision detection and visibility information for efficient dynamic simulation and real-time scene display. In particular, we address the following issues: (1) A geometric framework for modeling and visualizing synthetic environments and interacting with them. We highlight the functions required for the geometric engine of a synthetic environment system. (2) A distribution and collaboration substrate that supports construction, modification, and interaction with synthetic environments on networked desktop machines.

  13. Spicing thing up: Synthetic cannabinoids

    PubMed Central

    Spaderna, Max; Addy, Peter H; D’Souza, Deepak Cyril

    2013-01-01

    Rationale Recently, products containing synthetic cannabinoids, collectively referred to as Spice, are increasingly being used recreationally. Objectives The availability, acute subjective effects—including self-reports posted on Erowid—laboratory detection, addictive potential, and regulatory challenges of the Spice phenomenon are reviewed. Results Spice is sold under the guise of potpourri or incense. Unlike THC, the synthetic cannabinoids present in Spice are high-potency, high-efficacy, cannabinoid-receptor full agonists. Since standard urine toxicology does not test for the synthetic cannabinoids in Spice, it is often used by those who want to avoid detection of drug use. These compounds have not yet been subjected to rigorous testing in humans. Acute psychoactive effects include changes in mood, anxiety, perception, thinking, memory, and attention. Adverse effects include anxiety, agitation, panic, dysphoria, psychosis, and bizarre behavior. Psychosis outcomes associated with Spice provide additional data linking cannabinoids and psychosis. Adverse events necessitating intervention by Poison Control Centers, law enforcement, emergency responders, and hospitals are increasing. Despite statutes prohibiting the manufacture, distribution, and sale of Spice products, manufacturers are replacing banned compounds with newer synthetic cannabinoids that are not banned. Conclusions There is an urgent need for better research on the effects of synthetic cannabinoids to help clinicians manage adverse events and to better understand cannabinoid pharmacology in humans. The reported psychosis outcomes associated with synthetic cannabinoids contribute to the ongoing debate on the association between cannabinoids and psychosis. Finally, drug-detection tests for synthetic cannabinoids need to become clinically available. PMID:23836028

  14. Bistatic synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Yates, Gillian

    Synthetic aperture radar (SAR) allows all-weather, day and night, surface surveillance and has the ability to detect, classify and geolocate objects at long stand-off ranges. Bistatic SAR, where the transmitter and the receiver are on separate platforms, is seen as a potential means of countering the vulnerability of conventional monostatic SAR to electronic countermeasures, particularly directional jamming, and avoiding physical attack of the imaging platform. As the receiving platform can be totally passive, it does not advertise its position by RF emissions. The transmitter is not susceptible to jamming and can, for example, operate at long stand-off ranges to reduce its vulnerability to physical attack. This thesis examines some of the complications involved in producing high-resolution bistatic SAR imagery. The effect of bistatic operation on resolution is examined from a theoretical viewpoint and analytical expressions for resolution are developed. These expressions are verified by simulation work using a simple 'point by point' processor. This work is extended to look at using modern practical processing engines for bistatic geometries. Adaptations of the polar format algorithm and range migration algorithm are considered. The principal achievement of this work is a fully airborne demonstration of bistatic SAR. The route taken in reaching this is given, along with some results. The bistatic SAR imagery is analysed and compared to the monostatic imagery collected at the same time. Demonstrating high-resolution bistatic SAR imagery using two airborne platforms represents what I believe to be a European first and is likely to be the first time that this has been achieved outside the US (the UK has very little insight into US work on this topic). Bistatic target characteristics are examined through the use of simulations. This also compares bistatic imagery with monostatic and gives further insight into the utility of bistatic SAR.

  15. Synthetic inhibitors of elastase.

    PubMed

    Edwards, P D; Bernstein, P R

    1994-03-01

    For more than two decades investigators around the world, in both academic and industrial institutions, have been developing inhibitors of human neutrophil elastase. A number of very elegant and insightful strategies have been reported. In the case of reversible peptidic inhibitors, this has resulted in the identification of some extremely potent compounds with dissociation constants in the 10(-11) M range. This is quite an accomplishment considering that these low molecular-weight inhibitors are only tri- and tetrapeptides. In the case of the heterocyclic-based inhibitors, the challenge of balancing the heterocycle's inherent reactivity and aqueous stability with the stability of the enzyme-inhibitor adduct has been meet by either using a latent, reactive functionality which is only activated within the enzyme, or by incorporating features which selectively obstruct deacylation but have little effect on the enzyme acylation step. The underlying goal of this research has been the identification of agents to treat diseases associated with HNE. Several animal models have been developed for evaluating the in vivo activity of elastase inhibitors, and compounds have been shown to be effective in all of these models by the intravenous, intratrachael or oral routes of administration. However, only a very small percentage of compounds have possessed all the necessary properties, including lack of toxicity, for progression into the clinic. The peptidyl TFMK ICI 200,880 (25-12) has many of the desired characteristics of a drug to treat the diseases associated with HNE: chemical stability, in vitro and in vivo activity, a long duration of action, and adequate metabolic stability. Currently ICI 200,880 is the only low molecular-weight HNE inhibitor known to be undergoing clinical trials, and may be the compound which finally demonstrates the clinical utility of a synthetic HNE inhibitor. PMID:8189835

  16. SYNTHETIC BIOLOGY. Emergent genetic oscillations in a synthetic microbial consortium.

    PubMed

    Chen, Ye; Kim, Jae Kyoung; Hirning, Andrew J; Josić, Krešimir; Bennett, Matthew R

    2015-08-28

    A challenge of synthetic biology is the creation of cooperative microbial systems that exhibit population-level behaviors. Such systems use cellular signaling mechanisms to regulate gene expression across multiple cell types. We describe the construction of a synthetic microbial consortium consisting of two distinct cell types—an "activator" strain and a "repressor" strain. These strains produced two orthogonal cell-signaling molecules that regulate gene expression within a synthetic circuit spanning both strains. The two strains generated emergent, population-level oscillations only when cultured together. Certain network topologies of the two-strain circuit were better at maintaining robust oscillations than others. The ability to program population-level dynamics through the genetic engineering of multiple cooperative strains points the way toward engineering complex synthetic tissues and organs with multiple cell types. PMID:26315440

  17. Synthetic Fillers for Facial Rejuvenation.

    PubMed

    Lee, Johnson C; Lorenc, Z Paul

    2016-07-01

    Soft tissue filler procedures have increased dramatically in popularity in the United States. Synthetic fillers such as calcium hydroxyapatite (CaHA), polymethyl methacrylate (PMMA), and poly-l-lactic acid (PLLA), and silicone provide initial volume replacement but have an additional biostimulatory effect to supplement facial volumization. Indications include human immunodeficiency virus lipoatrophy and nasolabial folds for CaHA and PLLA and atrophic acne scars for PMMA. Most clinical use of these synthetic fillers is in an off-label fashion. Beyond the proper choice of a synthetic filler, careful consideration of dilution, injection method, and postprocedural care allows for successful and consistent results. PMID:27363763

  18. Synthetic Biology for Therapeutic Applications

    PubMed Central

    2015-01-01

    Synthetic biology is a relatively new field with the key aim of designing and constructing biological systems with novel functionalities. Today, synthetic biology devices are making their first steps in contributing new solutions to a number of biomedical challenges, such as emerging bacterial antibiotic resistance and cancer therapy. This review discusses some synthetic biology approaches and applications that were recently used in disease mechanism investigation and disease modeling, drug discovery and production, as well as vaccine development and treatment of infectious diseases, cancer, and metabolic disorders. PMID:25098838

  19. Degradation, metabolism and toxicity of synthetic pyrethroids.

    PubMed Central

    Miyamoto, J

    1976-01-01

    Synthetic pyrethroidal compounds undergo biodegradation in mammals both oxidatively and hydrolytically, and depending on the type of compound, either of the pathways may predominate. Thus, (+) - or (+/-) -trans isomers of the chrysanthemumate ester of primary alcohols such as fenothrin, furamethrin, proparthrin, resmethrin, and tetramethrin (and possibly permethrin, too) are metabolized mainly through hydrolysis of the ester linkage, with subsequent oxidation and/or conjugation of the component alcohol and acid moieties. On the other hand, the corresponding (+)-cis enantiometers and chrysanthemumate of secondary alcohols like allethrin are resistant to hydrolytic attack, and biodegraded via oxidation at various sites of the molecule. These rapid metabolic degradations, together with the presumable incomplete absorption from the gastrointestinal tract, would generally contribute to the low acute toxicity of synthetic pyrethroids. These compounds are neither skin irritants nor skin sensitizers, and inhalation toxicity as well as dermal toxicity are fairly low. Neither is teratogenic in rats, mice, and/or rabbits or mutagenic on various bacterial strains. Subacute and chronic feeding of higher amounts of the compounds to rats invariably causes some histopathological changes in liver; however, these are neither indicative nor suggestive of tumorigenicity. Based on existing toxicological information, the present recommended use patterns might afford sufficient safety margin on human population. However, in extending usage to agricultural pest control, much more extensive investigations should be forthcoming from both chemical and biological aspects, since there is scant information on the fate of these pyrethroids in the environment. Also several of the compounds may be very toxic to certain kinds of fish and arthropods. Images FIGURE 2. PMID:789062

  20. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Iron oxides. 73.2250 Section 73.2250 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron oxides consist of any one or any combination of synthetically prepared iron oxides, including...

  1. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Iron oxides. 73.2250 Section 73.2250 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron oxides consist of any one or any combination of synthetically prepared iron oxides, including...

  2. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Iron oxides. 73.2250 Section 73.2250 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron oxides consist of any one or any combination of synthetically prepared iron oxides, including...

  3. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Iron oxides. 73.2250 Section 73.2250 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron oxides consist of any one or any combination of synthetically prepared iron oxides, including...

  4. 21 CFR 73.2250 - Iron oxides.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Iron oxides. 73.2250 Section 73.2250 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron oxides consist of any one or any combination of synthetically prepared iron oxides, including...

  5. Thermal Property Evaluation of Cerium Dioxide and Cerium Dioxide Magnesium Oxide Powders for Testing Plutonium

    SciTech Connect

    HOYT, R C

    2002-06-01

    Ceric oxide (CeO{sub 2}) and mixtures of CeO{sub 2} -magnesium oxide (MgO) have been utilized at the Plutonium Finishing Plant (PFP) as surrogate materials to represent plutonium dioxide (PuO{sub 2}) and impure PuO{sub 2} containing impurities such as MgO during verification tests on PFP's stabilization furnaces. Magnesium oxide was selected during furnace testing as the impurity of interest since much of the impure PuO{sub 2} to be stabilized and packaged at the PFP contains significant amounts of MgO from solution stabilization work. The issue being addressed in this study is whether or not heating the surrogate materials to 950 C adequately simulates heating PuO{sub 2} powders to 950 C. This paper evaluates some of the thermal properties of these oxides, as related to the heating of powders of these materials where heat transfer within the powders is governed primarily by conduction. Detailed heat transfer modeling was outside the scope of this paper.

  6. A Course on Synthetic Fuels.

    ERIC Educational Resources Information Center

    Kimmel, Howard S.; Tomkins, Reginald P. T.

    1985-01-01

    A senior-level, elective course on synthetic fuels was developed for chemistry and chemical engineering majors. The topics covered in this course, instructional strategies used, and independent student projects are described. (JN)

  7. Is synthetic biology mechanical biology?

    PubMed

    Holm, Sune

    2015-12-01

    A widespread and influential characterization of synthetic biology emphasizes that synthetic biology is the application of engineering principles to living systems. Furthermore, there is a strong tendency to express the engineering approach to organisms in terms of what seems to be an ontological claim: organisms are machines. In the paper I investigate the ontological and heuristic significance of the machine analogy in synthetic biology. I argue that the use of the machine analogy and the aim of producing rationally designed organisms does not necessarily imply a commitment to mechanical biology. The ideal of applying engineering principles to biology is best understood as expressing recognition of the machine-unlikeness of natural organisms and the limits of human cognition. The paper suggests an interpretation of the identification of organisms with machines in synthetic biology according to which it expresses a strategy for representing, understanding, and constructing living systems that are more machine-like than natural organisms. PMID:26205204

  8. Synthetic Turf Multiplies Stadium Use.

    ERIC Educational Resources Information Center

    Leach, Richard

    1979-01-01

    The high school stadium in Flint, Michigan, once was used only for varsity football games. After the installation of synthetic turf, an average of 332 events have been staged there each year. (Author/MLF)

  9. Toward Engineering Synthetic Microbial Metabolism

    PubMed Central

    McArthur, George H.; Fong, Stephen S.

    2010-01-01

    The generation of well-characterized parts and the formulation of biological design principles in synthetic biology are laying the foundation for more complex and advanced microbial metabolic engineering. Improvements in de novo DNA synthesis and codon-optimization alone are already contributing to the manufacturing of pathway enzymes with improved or novel function. Further development of analytical and computer-aided design tools should accelerate the forward engineering of precisely regulated synthetic pathways by providing a standard framework for the predictable design of biological systems from well-characterized parts. In this review we discuss the current state of synthetic biology within a four-stage framework (design, modeling, synthesis, analysis) and highlight areas requiring further advancement to facilitate true engineering of synthetic microbial metabolism. PMID:20037734

  10. Programming languages for synthetic biology.

    PubMed

    Umesh, P; Naveen, F; Rao, Chanchala Uma Maheswara; Nair, Achuthsankar S

    2010-12-01

    In the backdrop of accelerated efforts for creating synthetic organisms, the nature and scope of an ideal programming language for scripting synthetic organism in-silico has been receiving increasing attention. A few programming languages for synthetic biology capable of defining, constructing, networking, editing and delivering genome scale models of cellular processes have been recently attempted. All these represent important points in a spectrum of possibilities. This paper introduces Kera, a state of the art programming language for synthetic biology which is arguably ahead of similar languages or tools such as GEC, Antimony and GenoCAD. Kera is a full-fledged object oriented programming language which is tempered by biopart rule library named Samhita which captures the knowledge regarding the interaction of genome components and catalytic molecules. Prominent feature of the language are demonstrated through a toy example and the road map for the future development of Kera is also presented. PMID:22132053

  11. Compounding in synthetic aperture imaging.

    PubMed

    Hansen, Jens Munk; Jensen, Jørgen Arendt

    2012-09-01

    A method for obtaining compound images using synthetic aperture data is investigated using a convex array transducer. The new approach allows spatial compounding to be performed for any number of angles without reducing the frame rate or temporal resolution. This important feature is an intrinsic property of how the compound images are constructed using synthetic aperture data and an improvement compared with how spatial compounding is obtained using conventional methods. The synthetic aperture compound images are created by exploiting the linearity of delay-and-sum beamformation for data collected from multiple spherical emissions to synthesize multiple transmit and receive apertures, corresponding to imaging the tissue from multiple directions. The many images are added incoherently, to produce a single compound image. Using a 192-element, 3.5-MHz, λ-pitch transducer, it is demonstrated from tissue-phantom measurements that the speckle is reduced and the contrast resolution improved when applying synthetic aperture compound imaging. At a depth of 4 cm, the size of the synthesized apertures is optimized for lesion detection based on the speckle information density. This is a performance measure for tissue contrast resolution which quantifies the tradeoff between resolution loss and speckle reduction. The speckle information density is improved by 25% when comparing synthetic aperture compounding to a similar setup for compounding using dynamic receive focusing. The cystic resolution and clutter levels are measured using a wire phantom setup and compared with conventional application of the array, as well as to synthetic aperture imaging without compounding. If the full aperture is used for synthetic aperture compounding, the cystic resolution is improved by 41% compared with conventional imaging, and is at least as good as what can be obtained using synthetic aperture imaging without compounding. PMID:23007781

  12. Superresolution and Synthetic Aperture Radar

    SciTech Connect

    DICKEY,FRED M.; ROMERO,LOUIS; DOERRY,ARMIN W.

    2001-05-01

    Superresolution concepts offer the potential of resolution beyond the classical limit. This great promise has not generally been realized. In this study we investigate the potential application of superresolution concepts to synthetic aperture radar. The analytical basis for superresolution theory is discussed. The application of the concept to synthetic aperture radar is investigated as an operator inversion problem. Generally, the operator inversion problem is ill posed. A criterion for judging superresolution processing of an image is presented.

  13. SYNTHETIC SLING FAILURE - EVALUATIONS & RECOMMENDATIONS

    SciTech Connect

    MACKEY TC; HENDERSON CS

    2009-10-26

    The information and evaluations provided in this report were compiled to address the recurring problem of synthetic sling failure. As safety is the number one priority in all work aspects, a solution must be devised to prevent accidents from occurring. A total of thirteen cases regarding synthetic sling failure were evaluated in order to determine their causes, effects, and preventative measures. From the collected data, it was found that all cases in which the synthetic sling contacted the edge of its load resulted in sling failure. It is required that adequate synthetic sling protection devices be used to protect slings in any lift where the sling comes in direct contact with the edge or corner of its load. However, there are no consensus codes or standards stating the type, material, or purpose of the type of protective device used to protect the sling from being cut. Numerous industry standards and codes provide vague descriptions on how to protect synthetic slings. Without a clear, concise statement of how to protect synthetic slings, it is common for inadequate materials and sling protection devices to be used in an attempt to meet the intent of these requirements. The use of an inadequate sling protection device is the main cause of synthetic sling failure in all researched cases. Commercial sling protection devices come in many shapes and sizes, and have a variety of names, as well as advertised uses. 'Abrasion pads' and 'wear protectors' are two different names for products with the same intended purpose. There is no distinguishable way to determine the extent of sling protection which these devices will provide, or what specific scenarios they are made for. This creates room for error in a field where error is unacceptable. This report provides a recommended action for hoisting and rigging activities which require synthetic slings to contact a load, as well as recommended changes to industry standards which will benefit overall industry safety.

  14. Symmetry-Driven Strategy for the Assembly of the Core Tetracycle of (+)-Ryanodine: Synthetic Utility of a Cobalt-Catalyzed Olefin Oxidation and α-Alkoxy Bridgehead Radical Reaction.

    PubMed

    Nagatomo, Masanori; Hagiwara, Koji; Masuda, Kengo; Koshimizu, Masaki; Kawamata, Takahiro; Matsui, Yuki; Urabe, Daisuke; Inoue, Masayuki

    2016-01-01

    Ryanodine (1) is a potent modulator of intracellular calcium release channels, designated as ryanodine receptors. The exceptionally complex molecular architecture of 1 comprises a highly oxygenated pentacyclic system with eleven contiguous stereogenic centers, which makes it a formidable target for organic synthesis. We identified the embedded C2 -symmetric tricyclic substructure within 1. This specific recognition permitted us to design a concise synthetic route to enantiopure tricycle 9 by utilizing a series of pairwise functionalizations. The four tetrasubstituted carbon centers of 9 were effectively constructed by three key reactions, a dearomatizing Diels-Alder reaction, the kinetic resolution of the obtained racemic 14 through asymmetric methanolysis, and the transannular aldol reaction of the eight-membered diketone 10. A new combination of cobalt-catalyzed hydroperoxidation and NfF-promoted elimination enabled conversion of the hindered olefin of 9 into the corresponding ketone, thus realizing the desymmetrization. Finally, the tetrasubstituted carbon was stereospecifically installed by utilizing the α-alkoxy bridgehead radical to deliver the core tetracycle 7 with the six contiguous tetrasubstituted carbon centers. Consequently, the present work not only accomplishes efficient assembly of four out of the five fused rings of 1, but also develops two new powerful methodologies: two-step ketone formation and bridgehead radical reaction. PMID:26616151

  15. Synthetic Eelgrass Oil Barrier

    NASA Astrophysics Data System (ADS)

    Curtis, T. G.

    2013-05-01

    Although surviving in situ micro-organisms eventually consume spilled oil, extensive inundation of shore biota by oil requires cleanup to enable ecological recovery within normal time scales. Although effective in calm seas and quiet waters, oil is advected over and under conventional curtain oil booms by wave actions and currents when seas are running. Most sorbent booms are not reusable, and are usually disposed of in landfills, creating excessive waste. A new concept is proposed for a floating oil barrier, to be positioned off vulnerable coasts, to interdict, contain, and sequester spilled oil, which can then be recovered and the barrier reused. While conventional oil boom designs rely principally on the immiscibility of oil in water and its relative buoyancy, the new concept barrier avoids the pitfalls of the former by taking advantage of the synergistic benefits of numerous fluid and material properties, including: density, buoyancy, elasticity, polarity, and surface area to volume ratio. Modeled after Zostera marina, commonly called eelgrass, the new barrier, referred to as synthetic eelgrass (SE), behaves analogously. Eelgrass has very long narrow, ribbon-like, leaves which support periphyton, a complex matrix of algae and heterotrophic microbes, which position themselves there to extract nutrients from the seawater flowing past them. In an analogous fashion, oil on, or in, seawater, which comes in contact with SE, is adsorbed on the surface and sequestered there. Secured to the bottom, in shoal waters, SE rises to the surface, and, if the tide is low enough, floats on the sea surface down wind, or down current to snare floating oil. The leaves of SE, called filaments, consist of intrinsically buoyant strips of ethylene methyl acrylate, aka EMA. EMA, made of long chain, saturated, hydrocarbon molecules with nearly homogeneous electron charge distributions, is a non-polar material which is oleophilic and hydrophobic. Oil must be in close proximity to the

  16. Freedom and Responsibility in Synthetic Genomics: The Synthetic Yeast Project.

    PubMed

    Sliva, Anna; Yang, Huanming; Boeke, Jef D; Mathews, Debra J H

    2015-08-01

    First introduced in 2011, the Synthetic Yeast Genome (Sc2.0) PROJECT is a large international synthetic genomics project that will culminate in the first eukaryotic cell (Saccharomyces cerevisiae) with a fully synthetic genome. With collaborators from across the globe and from a range of institutions spanning from do-it-yourself biology (DIYbio) to commercial enterprises, it is important that all scientists working on this project are cognizant of the ethical and policy issues associated with this field of research and operate under a common set of principles. In this commentary, we survey the current ethics and regulatory landscape of synthetic biology and present the Sc2.0 Statement of Ethics and Governance to which all members of the project adhere. This statement focuses on four aspects of the Sc2.0 PROJECT: societal benefit, intellectual property, safety, and self-governance. We propose that such project-level agreements are an important, valuable, and flexible model of self-regulation for similar global, large-scale synthetic biology projects in order to maximize the benefits and minimize potential harms. PMID:26272997

  17. Freedom and Responsibility in Synthetic Genomics: The Synthetic Yeast Project

    PubMed Central

    Sliva, Anna; Yang, Huanming; Boeke, Jef D.; Mathews, Debra J. H.

    2015-01-01

    First introduced in 2011, the Synthetic Yeast Genome (Sc2.0) Project is a large international synthetic genomics project that will culminate in the first eukaryotic cell (Saccharomyces cerevisiae) with a fully synthetic genome. With collaborators from across the globe and from a range of institutions spanning from do-it-yourself biology (DIYbio) to commercial enterprises, it is important that all scientists working on this project are cognizant of the ethical and policy issues associated with this field of research and operate under a common set of principles. In this commentary, we survey the current ethics and regulatory landscape of synthetic biology and present the Sc2.0 Statement of Ethics and Governance to which all members of the project adhere. This statement focuses on four aspects of the Sc2.0 Project: societal benefit, intellectual property, safety, and self-governance. We propose that such project-level agreements are an important, valuable, and flexible model of self-regulation for similar global, large-scale synthetic biology projects in order to maximize the benefits and minimize potential harms. PMID:26272997

  18. Synthetic genomics and the construction of a synthetic bacterial cell.

    PubMed

    Glass, John I

    2012-01-01

    The first synthetic cellular organism was created in 2010 and based on a very small, very simple bacterium called Mycoplasma mycoides. The bacterium was called synthetic because its DNA genome was chemically synthesized rather than replicated from an existing template DNA, as occurs in all other known cellular life on Earth. The experiment was undertaken in order to develop a system that would allow creation of a minimal bacterial cell that could lead to a better understand of the first principles of cellular life. The effort resulted in new synthetic genomics techniques called genome assembly and genome transplantation. The ability of scientists to design and build bacteria opens new possibilities for creating microbes to solve human problems. PMID:23502559

  19. Molecular recognition of surface-immobilized carbohydrates by a synthetic lectin

    PubMed Central

    Rauschenberg, Melanie; Fritz, Eva-Corrina; Schulz, Christian; Kaufmann, Tobias

    2014-01-01

    Summary The molecular recognition of carbohydrates and proteins mediates a wide range of physiological processes and the development of synthetic carbohydrate receptors (“synthetic lectins”) constitutes a key advance in biomedical technology. In this article we report a synthetic lectin that selectively binds to carbohydrates immobilized in a molecular monolayer. Inspired by our previous work, we prepared a fluorescently labeled synthetic lectin consisting of a cyclic dimer of the tripeptide Cys-His-Cys, which forms spontaneously by air oxidation of the monomer. Amine-tethered derivatives of N-acetylneuraminic acid (NANA), β-D-galactose, β-D-glucose and α-D-mannose were microcontact printed on epoxide-terminated self-assembled monolayers. Successive prints resulted in simple microarrays of two carbohydrates. The selectivity of the synthetic lectin was investigated by incubation on the immobilized carbohydrates. Selective binding of the synthetic lectin to immobilized NANA and β-D-galactose was observed by fluorescence microscopy. The selectivity and affinity of the synthetic lectin was screened in competition experiments. In addition, the carbohydrate binding of the synthetic lectin was compared with the carbohydrate binding of the lectins concanavalin A and peanut agglutinin. It was found that the printed carbohydrates retain their characteristic selectivity towards the synthetic and natural lectins and that the recognition of synthetic and natural lectins is strictly orthogonal. PMID:24991289

  20. Synthetic applications of pseudocyclic hypervalent iodine compounds.

    PubMed

    Yoshimura, Akira; Yusubov, Mekhman S; Zhdankin, Viktor V

    2016-06-01

    Hypervalent iodine compounds have found wide practical application as versatile, efficient, and sustainable reagents for organic synthesis. Pseudocyclic hypervalent iodine derivatives are characterized by the presence of additional intramolecular non-covalent coordination at the iodine center, which leads to significant alteration of their physical and chemical properties. In comparison with common hypervalent iodine reagents, these pseudocyclic compounds have higher thermal stability, better solubility, and improved reactivity. In recent years, pseudocyclic hypervalent iodine reagents are increasingly used in organic synthesis as environmentally friendly selective oxidants and electrophiles. Furthermore, numerous enantioselective reactions mediated by chiral pseudocyclic hypervalent iodine species have been recently developed. In the present review, the preparation and structural features of pseudocyclic iodine(iii) and iodine(v) derivatives are discussed, and recent developments in their synthetic applications are summarized. PMID:27143521

  1. Synthetic magnetoelectric coupling in a nanocomposite multiferroic

    DOE PAGESBeta

    Jain, P.; Wang, Q.; Roldan, M.; Glavic, A.; Lauter, V.; Urban, C.; Bi, Z.; Ahmed, T.; Zhu, J.; Varela, M.; et al

    2015-03-13

    Given the paucity of single phase multiferroic materials (with large ferromagnetic moment), composite systems seem an attractive solution to realize magnetoelectric coupling between ferromagnetic and ferroelectric order parameters. Despite having antiferromagnetic order, BiFeO₃ (BFO) has nevertheless been a key material due to excellent ferroelectric properties at room temperature. We studied a superlattice composed of 8 repetitions of 6 unit cells of La₀.₇Sr₀.₃MnO₃ (LSMO) grown on 5 unit cells of BFO. Significant net uncompensated magnetization in BFO, an insulating superlattice, is demonstrated using polarized neutron reflectometry. Remarkably, the magnetization enables magnetic field to change the dielectric properties of the superlattice, whichmore » we cite as an example of synthetic magnetoelectric coupling. Importantly, controlled creation of magnetic moment in BFO is a much needed path toward design and implementation of integrated oxide devices for next generation magnetoelectric data storage platforms.« less

  2. Synthetic magnetoelectric coupling in a nanocomposite multiferroic.

    PubMed

    Jain, P; Wang, Q; Roldan, M; Glavic, A; Lauter, V; Urban, C; Bi, Z; Ahmed, T; Zhu, J; Varela, M; Jia, Q X; Fitzsimmons, M R

    2015-01-01

    Given the paucity of single phase multiferroic materials (with large ferromagnetic moment), composite systems seem an attractive solution to realize magnetoelectric coupling between ferromagnetic and ferroelectric order parameters. Despite having antiferromagnetic order, BiFeO3 (BFO) has nevertheless been a key material due to excellent ferroelectric properties at room temperature. We studied a superlattice composed of 8 repetitions of 6 unit cells of La0.7Sr0.3MnO3 (LSMO) grown on 5 unit cells of BFO. Significant net uncompensated magnetization in BFO, an insulating superlattice, is demonstrated using polarized neutron reflectometry. Remarkably, the magnetization enables magnetic field to change the dielectric properties of the superlattice, which we cite as an example of synthetic magnetoelectric coupling. Importantly, controlled creation of magnetic moment in BFO is a much needed path toward design and implementation of integrated oxide devices for next generation magnetoelectric data storage platforms. PMID:25766205

  3. Synthetic retinoids: structure-activity relationships.

    PubMed

    Barnard, Jonathan H; Collings, Jonathan C; Whiting, Andrew; Przyborski, Stefan A; Marder, Todd B

    2009-11-01

    Retinoid signalling pathways are involved in numerous processes in cells, particularly those mediating differentiation and apoptosis. The endogenous ligands that bind to the retinoid receptors, namely all-trans-retinoic acid (ATRA) and 9-cis-retinoic acid, are prone to double-bond isomerisation and to oxidation by metabolic enzymes, which can have significant and deleterious effects on their activities and selectivities. Many of these problems can be overcome through the use of synthetic retinoids, which are often much more stable, as well as being more active. Modification of their molecular structures can result in retinoids that act as antagonists, rather than agonists, or exhibit a large degree of selectivity for particular retinoid-receptor isotypes. Several such selective retinoids are likely to be of value as pharmaceutical agents with reduced toxicities, particularly in cancer therapy, as reagents for controlling cell differentiation, and as tools for elucidating the precise roles that specific retinoid signalling pathways play within cells. PMID:19821467

  4. Meeting Report: Synthetic Biology Jamboree for Undergraduates

    ERIC Educational Resources Information Center

    Campbell, A. Malcolm

    2005-01-01

    The field of synthetic biology (the name is derived from an analogy to synthetic chemistry) has recognized itself as a "field" only since about 2002. Synthetic biology has gotten some high-profile attention recently, but most people are not aware the field even exists. Synthetic biologists apply engineering principles to genomic circuits to…

  5. Control theory meets synthetic biology.

    PubMed

    Del Vecchio, Domitilla; Dy, Aaron J; Qian, Yili

    2016-07-01

    The past several years have witnessed an increased presence of control theoretic concepts in synthetic biology. This review presents an organized summary of how these control design concepts have been applied to tackle a variety of problems faced when building synthetic biomolecular circuits in living cells. In particular, we describe success stories that demonstrate how simple or more elaborate control design methods can be used to make the behaviour of synthetic genetic circuits within a single cell or across a cell population more reliable, predictable and robust to perturbations. The description especially highlights technical challenges that uniquely arise from the need to implement control designs within a new hardware setting, along with implemented or proposed solutions. Some engineering solutions employing complex feedback control schemes are also described, which, however, still require a deeper theoretical analysis of stability, performance and robustness properties. Overall, this paper should help synthetic biologists become familiar with feedback control concepts as they can be used in their application area. At the same time, it should provide some domain knowledge to control theorists who wish to enter the rising and exciting field of synthetic biology. PMID:27440256

  6. Control theory meets synthetic biology

    PubMed Central

    2016-01-01

    The past several years have witnessed an increased presence of control theoretic concepts in synthetic biology. This review presents an organized summary of how these control design concepts have been applied to tackle a variety of problems faced when building synthetic biomolecular circuits in living cells. In particular, we describe success stories that demonstrate how simple or more elaborate control design methods can be used to make the behaviour of synthetic genetic circuits within a single cell or across a cell population more reliable, predictable and robust to perturbations. The description especially highlights technical challenges that uniquely arise from the need to implement control designs within a new hardware setting, along with implemented or proposed solutions. Some engineering solutions employing complex feedback control schemes are also described, which, however, still require a deeper theoretical analysis of stability, performance and robustness properties. Overall, this paper should help synthetic biologists become familiar with feedback control concepts as they can be used in their application area. At the same time, it should provide some domain knowledge to control theorists who wish to enter the rising and exciting field of synthetic biology. PMID:27440256

  7. Advances in Synthetic Applications of Hypervalent Iodine Compounds.

    PubMed

    Yoshimura, Akira; Zhdankin, Viktor V

    2016-03-01

    The preparation, structure, and chemistry of hypervalent iodine compounds are reviewed with emphasis on their synthetic application. Compounds of iodine possess reactivity similar to that of transition metals, but have the advantage of environmental sustainability and efficient utilization of natural resources. These compounds are widely used in organic synthesis as selective oxidants and environmentally friendly reagents. Synthetic uses of hypervalent iodine reagents in halogenation reactions, various oxidations, rearrangements, aminations, C-C bond-forming reactions, and transition metal-catalyzed reactions are summarized and discussed. Recent discovery of hypervalent catalytic systems and recyclable reagents, and the development of new enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important achievement in the field of hypervalent iodine chemistry. One of the goals of this Review is to attract the attention of the scientific community as to the benefits of using hypervalent iodine compounds as an environmentally sustainable alternative to heavy metals. PMID:26861673

  8. Copper(II)-mediated oxidative transformation of vic-dioxime to furoxan: evidence for a copper(II)-dinitrosoalkene intermediate.

    PubMed

    Das, Oindrila; Paria, Sayantan; Zangrando, Ennio; Paine, Tapan Kanti

    2011-11-21

    The mononuclear copper(II) complex [Cu(H(2)L(1))(2)(H(2)O)](ClO(4))(2) (1) (where H(2)L(1) = 1,10-phenanthroline-5,6-dioxime) reacts with copper(II) perchlorate in acetonitrile at ambient conditions in the presence of triethylamine to afford a copper(II) complex, [Cu(L(3))(2)(H(2)O)](ClO(4))(2) (2a), of 1,10-phenanthroline furoxan. A similar complex [Cu(L(3))(2)Cl](ClO(4)) (2) is isolated from the reaction of H(2)L(1) with copper(II) chloride, triethylamine, and sodium perchlorate in acetonitrile. The two-electron oxidation of the vic-dioxime to furoxan is confirmed from the X-ray single crystal structure of 2. An intermediate species, showing an absorption band at 608 nm, is observed at -20 °C during the conversion of 1 to 2a. A similar blue intermediate is formed during the reaction of [Cu(HDMG)(2)] (H(2)DMG = dimethylglyoxime) with ceric ammonium nitrate, but H(2)DMG treated with ceric ammonium nitrate does not form any intermediate. This suggests the involvement of a copper(II) complex in the intermediate step. The intermediate species is also observed during the two-electron oxidation of other vic-dioximes. On the basis of the spectroscopic evidence and the nature of the final products, the intermediate is proposed to be a mononuclear copper(II) complex ligated by a vic-dioxime and a dinitrosoalkene. The dinitrosoalkene is generated upon two-electron oxidation of the dioxime. The transient blue color of the dioxime-copper(II)-dinitrosoalkene complex may be attributed to the ligand-to-ligand charge transfer transition. The intermediate species slowly decays to the corresponding two-electron oxidized form of vic-dioxime, i.e. furoxan and [Cu(CH(3)CN)(4)](ClO(4)). The formation of two isomeric furoxans derived from the reaction of an asymmetric vic-dioxime, hexane-2,3-dioxime, and copper(II) perchlorate supports the involvement of a dinitrosoalkene species in the intermediate step. In addition, the oxidation of 2,9-dimethyl-1,10-phenanthroline-5,6-dioxime (H(2)L

  9. Synthetic neurosteroids on brain protection

    PubMed Central

    Rey, Mariana; Coirini, Héctor

    2015-01-01

    Neurosteroids, like allopregnanolone and pregnanolone, are endogenous regulators of neuronal excitability. Inside the brain, they are highly selective and potent modulators of GABAA receptor activity. Their anticonvulsant, anesthetics and anxiolytic properties are useful for the treatments of several neurological and psychiatric disorders via reducing the risks of side effects obtained with the commercial drugs. The principal disadvantages of endogenous neurosteroids administration are their rapid metabolism and their low oral bioavailability. Synthetic steroids analogues with major stability or endogenous neurosteroids stimulation synthesis might constitute promising novel strategies for the treatment of several disorders. Numerous studies indicate that the 3α-hydroxyl configuration is the key for binding and activity, but modifications in the steroid nucleus may emphasize different pharmacophores. So far, several synthetic steroids have been developed with successful neurosteroid-like effects. In this work, we summarize the properties of various synthetic steroids probed in trials throughout the analysis of several neurosteroids-like actions. PMID:25788907

  10. Synthetic Peptides as Protein Mimics

    PubMed Central

    Groß, Andrea; Hashimoto, Chie; Sticht, Heinrich; Eichler, Jutta

    2016-01-01

    The design and generation of molecules capable of mimicking the binding and/or functional sites of proteins represents a promising strategy for the exploration and modulation of protein function through controlled interference with the underlying molecular interactions. Synthetic peptides have proven an excellent type of molecule for the mimicry of protein sites because such peptides can be generated as exact copies of protein fragments, as well as in diverse chemical modifications, which includes the incorporation of a large range of non-proteinogenic amino acids as well as the modification of the peptide backbone. Apart from extending the chemical and structural diversity presented by peptides, such modifications also increase the proteolytic stability of the molecules, enhancing their utility for biological applications. This article reviews recent advances by this and other laboratories in the use of synthetic protein mimics to modulate protein function, as well as to provide building blocks for synthetic biology. PMID:26835447