WorldWideScience

Sample records for aqueous media sintesis

  1. Synthesis and characterization of ferrous phosphate (vivianite) and its behavior in aqueous media; Sintesis y caracterizacion del fosfato ferroso (vivianita) y su comportamiento en medio acuoso

    Energy Technology Data Exchange (ETDEWEB)

    Diaz F, J.C

    2003-07-01

    The synthesis and characterization of materials that can be useful in Environmental Chemistry is very important because their characteristics are exposed and its behavior in chemical phenomena as the sorption in aqueous media is understand to use it in the human being benefit. With the object of using, in a future, the octa hydrated ferrous phosphate (vivianite) as a potential candidate for matrix confinement in contention walls for the storage of radioactive waste of long half life, it was synthesized and it characterized physico chemically and their properties of surface of this compound were evaluated. Presently work was carried out the synthesis and structural characterization of the iron phosphate II by infrared spectroscopy with having Fourier transform, high vacuum scanning electron microscopy, X-ray diffraction, thermal gravimetric analysis, the BET multipoint surface area and Moessbauer spectroscopy; as well as, the determination between aqueous media of the isoelectric point and the density of sites of surface of the compound. The octa hydrated ferrous phosphate was obtained pure. The results indicate that the product corresponds to the prospective mineral, the vivianite. The thermal gravimetric analysis demonstrated that the ferrous phosphate is a stable salt after the lost of water. The isoelectric point is since an important parameter because allows to know the behavior of the surface of the material in aqueous systems, in this case the isoelectric point, of the octa hydrated ferrous phosphate, in distilled water is of pH 4.20 and in solution of potassium nitrate 0.5 M is of pH = 3.75. This indicates that the material has an amphoteric surface depending on the pH. On the other hand, the density of active sites of surface obtained by titrations acid-base is of 20 sites by nm{sup 2}. (Author)

  2. Interfacial forces in aqueous media

    CERN Document Server

    van Oss, Carel J

    2006-01-01

    Thoroughly revised and reorganized, the second edition of Interfacial Forces in Aqueous Media examines the role of polar interfacial and noncovalent interactions among biological and nonbiological macromolecules as well as biopolymers, particles, surfaces, cells, and both polar and apolar polymers. The book encompasses Lifshitz-van der Waals and electrical double layer interactions, as well as Lewis acid-base interactions between colloidal entities in polar liquids such as water. New in this Edition: Four previously unpublished chapters comprising a new section on interfacial propertie

  3. Sintesi stereoselettiva di piridilammine

    OpenAIRE

    Chelucci, Giorgio Adolfo; Baldino, Salvatore; Pinna, Gérard Aimé; Soccolini, Francesco

    2006-01-01

    Ammino piridine chirali hanno dimostrato la loro validità come leganti per la formazione di complessi metallici utilizzati nella catalisi asimmetrica. Tra i possibili approcci alla sintesi di questi composti noi abbiamo investigato la riduzione diastereoselettiva di N-sostituite (p-totil e tert-butil) piridil chetimmine con una serie di agenti riducenti (NaBH4, L-Selectride, DIBAL, 9-BBN) in diverse condizioni di reazione.

  4. Thermometric titration of some monoprotic and diprotic acids in aqueous and non-aqueous media.

    Science.gov (United States)

    Harries, R J

    1968-12-01

    Some mono- and diprotic acids have been titrated thermometrically with strong alkalis in aqueous and non-aqueous media. Thermograms with sharp arrest points were obtained, from which heats of neutralization were measured. Heats of neutralization in the media used were compared and an effect attributable to hydrogen bonding was found.

  5. Desalination of aqueous media using ionic liquids

    NARCIS (Netherlands)

    2014-01-01

    The present invention relates to a method for extracting metal and/or metalloid ions from an aqueous medium, comprising the steps of: a) mixing the aqueous medium with an ionic liquid comprising an aliphatic carboxylate anion having at least one unsaturated carbon-carbon bond, or and/or with a

  6. Protonation site for anilines in aqueous media

    Directory of Open Access Journals (Sweden)

    INNA M. UCHAEVA

    2002-02-01

    Full Text Available By means of the PM3 method it has been shown that the protonation of 2-, 3-, 4-methoxyanilines, 4-methylthioaniline, 2-, 3-, 4-aminobenzoic acids, 2-, 3-, 4-nitroanilines in the gaseous phase proceeds via the amine nitrogen atom. The same result, attributed to the aqueous medium, was obtained for 4-methoxyaniline, 4-aminobenzoic acid and 4-nitroaniline.

  7. Clean and Efficient Synthesis of Isoxazole Derivatives in Aqueous Media

    Directory of Open Access Journals (Sweden)

    Daqing Shi

    2013-11-01

    Full Text Available A series of 5-arylisoxazole derivatives were synthesized via the reaction of 3-(dimethyl-amino-1-arylprop-2-en-1-ones with hydroxylamine hydrochloride in aqueous media without using any catalyst. This method has the advantages of easier work-up, mild reaction conditions, high yields, and an environmentally benign procedure.

  8. Reductive amination with zinc powder in aqueous media

    Directory of Open Access Journals (Sweden)

    Giovanni B. Giovenzana

    2011-08-01

    Full Text Available Zinc powder in aqueous alkaline media was employed to perform reductive amination of aldehydes with primary amines. The corresponding secondary amines were obtained in good yields along with minor amounts of hydrodimerization byproducts. The protocol is a green alternative to the use of complex hydrides in chlorinated or highly flammable solvents.

  9. Propargylamine-isothiocyanate reaction: efficient conjugation chemistry in aqueous media

    DEFF Research Database (Denmark)

    Viart, Helene Marie-France; Larsen, T. S.; Tassone, Chiara

    2014-01-01

    A coupling reaction between secondary propargyl amines and isothiocyanates in aqueous media is described. The reaction is high-yielding and affords cyclized products within 2-24 h. A functionalized ether lipid was synthesized in 8 steps, formulated as liposomes with POPC and conjugated to FITC un...

  10. Oxidation of magnetite in aerated aqueous media

    International Nuclear Information System (INIS)

    Taylor, P.; Owen, D.G.

    1993-04-01

    Metastable equilibria involving phases less stable than hematite can be significantly more oxidizing than the calculated equilibrium between well-crystallized hematite and magnetite. In this report, generalized solubility and stability relationships between magnetite and Fe 2 O 3 .xH 2 O phases are derived to describe the metastable equilibria. Experiments with synthetic magnetite powders in aerated aqueous solutions show that crystalline hematite is formed within days at temperatures above 100 C in pure water or solutions containing anions (e.g., Cl - , SO 4 2 - , HCO 3 - ) that do not form very strong surface complexes with iron oxides. In the presence of dissolved phosphate or silica, however, the dissolution-precipitation route to hematite is strongly inhibited, and maghemite is a persistent metastable product. Thus, phosphate or silica are expected to delay the approach to magnetite-hematite equilibrium in aerated groundwaters conditioned by magnetite. These findings are presented in the context of nuclear fuel waste disposal. (author). 63 refs., 1 tab., 11 figs

  11. Boric Acid Catalyzed Convenient Synthesis of Benzimidazoles in Aqueous Media

    OpenAIRE

    Poor Heravi, Mohammad Reza; Ashori, Marjan

    2013-01-01

    Synthesis of benzimidazoles has been developed by the o-phenylenediamine with aldehydes using boric acid an efficient catalyst under mild reaction conditions in aqueous media. The product is applicable to aryl and heteroaryl aldehydes. This reaction led to the formation of benzimidazoles new derivatives in good yields. The FT-IR, 19F-NMR, 1H-NMR, 13C-NMR spectra and elemental analysis confirm the structure of compounds.

  12. Boric Acid Catalyzed Convenient Synthesis of Benzimidazoles in Aqueous Media

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Poor Heravi

    2013-01-01

    Full Text Available Synthesis of benzimidazoles has been developed by the o-phenylenediamine with aldehydes using boric acid an efficient catalyst under mild reaction conditions in aqueous media. The product is applicable to aryl and heteroaryl aldehydes. This reaction led to the formation of benzimidazoles new derivatives in good yields. The FT-IR, 19F-NMR, 1H-NMR, 13C-NMR spectra and elemental analysis confirm the structure of compounds.

  13. Dissolution of metal and metal oxide nanoparticles in aqueous media

    International Nuclear Information System (INIS)

    Odzak, Niksa; Kistler, David; Behra, Renata; Sigg, Laura

    2014-01-01

    The dissolution of Ag (citrate, gelatin, polyvinylpyrrolidone and chitosan coated), ZnO, CuO and carbon coated Cu nanoparticles (with two nominal sizes each) has been studied in artificial aqueous media, similar in chemistry to environmental waters, for up to 19 days. The dissolved fraction was determined using DGT (Diffusion Gradients in Thin films), dialysis membrane (DM) and ultrafiltration (UF). Relatively small fractions of Ag nanoparticles dissolved, whereas ZnO dissolved nearly completely within few hours. Cu and CuO dissolved as a function of pH. Using DGT, less dissolved Ag was measured compared to UF and DM, likely due to differences in diffusion of organic complexes. Similar dissolved metal concentrations of ZnO, Cu and CuO nanoparticles were determined using DGT and UF, but lower using DM. The results indicate that there is a need to apply complementary techniques to precisely determine dissolution of nanoparticles in aqueous media. - Highlights: • Three different techniques used simultaneously to measure NPs dissolution. • ZnO-NPs are the most soluble, followed by CuO-NPs, carbon coated Cu-NPs and Ag-NPs. • Dissolution is an important process affecting the fate of nanoparticles. • Complementary techniques are needed to precisely determine dissolution of NPs. - Dissolution of several types of nanoparticles was examined in aqueous media using three complementary techniques

  14. Microwave-assisted synthesis of bio-active heterocycles in aqueous media

    KAUST Repository

    Polshettiwar, Vivek

    2010-01-01

    Synthesis of bio-active heterocycles and fine chemicals in aqueous media are one of the best solutions for the development of green and sustainable protocols. To illustrate the advantages of aqueous MW chemistry in heterocycle synthesis, in this chapter, various synthetic pathways developed in recent years in aqueous reaction media using microwave irradiation are described.

  15. Study of the europium behavior in aqueous media

    International Nuclear Information System (INIS)

    Fernandez R, E.; Jimenez R, M.; Solache R, M.; Martinez M, V.

    1999-01-01

    Europium as waste can produce a pollution problem in water that is in contact with it, what would has a heavy environmental impacts, because of the possibilities of diffusion of these wastes from their place of confinement or storage until the geo and biosphere. The solution of such problem requires of a lot of knowledge over the behavior of several chemical elements such as europium in aqueous solutions. In this work it was used a low ion force (0.02 M). The data set will allow extrapolate the hydrolytic behavior of europium in too much minors ion force media, such as the ground waters, including in ion force zero

  16. Microwave-assisted synthesis of bio-active heterocycles in aqueous media

    KAUST Repository

    Polshettiwar, Vivek; Varma, Rajender S.

    2010-01-01

    Synthesis of bio-active heterocycles and fine chemicals in aqueous media are one of the best solutions for the development of green and sustainable protocols. To illustrate the advantages of aqueous MW chemistry in heterocycle synthesis

  17. Towards water compatible MIPs for sensing in aqueous media.

    Science.gov (United States)

    Horemans, F; Weustenraed, A; Spivak, D; Cleij, T J

    2012-06-01

    When synthesizing molecularly imprinted polymers (MIPs), a few fundamental principles should be kept in mind. There is a strong correlation between porogen polarity, MIP microenvironment polarity and the imprinting effect itself. The combination of these parameters eventually determines the overall binding behavior of a MIP in a given solvent. In addition, it is shown that MIP binding is strongly influenced by the polarity of the rebinding solvent. Because the use of MIPs in biomedical environments is of considerable interest, it is important that these MIPs perform well in aqueous media. In this article, various approaches are explored towards a water compatible MIP for the target molecule l-nicotine. To this end, the imprinting effect together with the MIP matrix polarity is fine-tuned during MIP synthesis. The binding behavior of the resulting MIPs is evaluated by performing batch rebinding experiments that makes it possible to select the most suitable MIP/non-imprinted polymer couple for future application in aqueous environments. One method to achieve improved compatibility with water is referred to as porogen tuning, in which porogens of varying polarities are used. It is demonstrated that, especially when multiple porogens are mixed, this approach can lead to superior performance in aqueous environments. Another method involves the incorporation of polar or non-polar comonomers in the MIP matrix. It is shown that by carefully selecting these monomers, it is also possible to obtain MIPs, which can selectively bind their target in water. Copyright © 2012 John Wiley & Sons, Ltd.

  18. Cation exchange properties of zeolites in hyper alkaline aqueous media.

    Science.gov (United States)

    Van Tendeloo, Leen; de Blochouse, Benny; Dom, Dirk; Vancluysen, Jacqueline; Snellings, Ruben; Martens, Johan A; Kirschhock, Christine E A; Maes, André; Breynaert, Eric

    2015-02-03

    Construction of multibarrier concrete based waste disposal sites and management of alkaline mine drainage water requires cation exchangers combining excellent sorption properties with a high stability and predictable performance in hyper alkaline media. Though highly selective organic cation exchange resins have been developed for most pollutants, they can serve as a growth medium for bacterial proliferation, impairing their long-term stability and introducing unpredictable parameters into the evolution of the system. Zeolites represent a family of inorganic cation exchangers, which naturally occur in hyper alkaline conditions and cannot serve as an electron donor or carbon source for microbial proliferation. Despite their successful application as industrial cation exchangers under near neutral conditions, their performance in hyper alkaline, saline water remains highly undocumented. Using Cs(+) as a benchmark element, this study aims to assess the long-term cation exchange performance of zeolites in concrete derived aqueous solutions. Comparison of their exchange properties in alkaline media with data obtained in near neutral solutions demonstrated that the cation exchange selectivity remains unaffected by the increased hydroxyl concentration; the cation exchange capacity did however show an unexpected increase in hyper alkaline media.

  19. 1-N-aminoindol derivatives synthesis in no aqueous means from the 1, 4-dihydrocinnoline obtained by electrolysis in continuous flow redox cell; Sintesis de derivados del 1-N-aminoindol en medios no acuosos a partir de la 1, 4-dihidrocinolina obtenida por electrolisis en celda redox de flujo continuo

    Energy Technology Data Exchange (ETDEWEB)

    Frontana-Uribe, Bernardo A. [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico); Moinet, Claude [Laboratoire d' Electrochimie et Organometalliques UMR, Paris (France)

    1999-08-01

    This work describes the synthesis of 1-N-aminoindol derivatives in organic anhydrous media from 1, 4-dihydrocinnoline. 1, 4-dihydrocinnoline 4 is obtained by electrolysis of 2-(orto-notropheny)-ethylamine 1a in a continuous flow redox cell. The cinnoline ring contraction products are obtained in low yield, but they show the possibility to carry out the reaction in organic media without water addition, as it was noted in previous works. [Spanish] En este trabajo se describe la sintesis de derivados del 1-N-aminoindol en medios anhidros a partir de la 1, 4-dihidrocinolina 4. Esta se obtiene mediante la electrolisis de la 2-(orto-notrofenil)-etilamina 1a en celda redox de flujo continuo. Los productos de contraccion del ciclo de la cinolina en 1-N-aminoindol se obtiene en rendimiento bajo, pero demuestran la posibilidad de llevar a cabo esta reaccion en medios totalmente organicos, sin la necesidad de la adicion de agua en el medio de reaccion, como esta descrito en trabajos precedentes.

  20. Atmospheric-pressure air microplasma jets in aqueous media for the inactivation of Pseudomonas fluorescens cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xianhui; Yang, Si-ze [Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Liu, Dongping [Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, School of Physics and Mechanical and Electrical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); Song, Ying [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600 (China); School of Physics and Optoelectronic Technology, Dalian University of Technology, Dalian 116023 (China); Sun, Yue [School of Physics, Changchun University of Science and Technology, Changchun 130022 (China)

    2013-05-15

    The hollow fiber-based cold air microplasma jet array running at atmospheric pressure has been designed to inactivate Pseudomonas fluorescens (P. fluorescens) cells in vitro in aqueous media. The influences of electrode configurations, air flow rate, and applied voltage on the discharge characteristics of the single microplasma jet operating in aqueous media are presented, and the bactericidal efficiency of the hollow fibers-based and large-volume microplasma jet array is reported. Optical emission spectroscopy is utilized to identify excited species during the antibacterial testing of plasma in solutions. These well-aligned and rather stable air microplasma jets containing a variety of short-lived species, such as OH and O radicals and charged particles, are in direct contact with aqueous media and are very effective in killing P. fluorescens cells in aqueous media. This design shows its potential application for atmospheric pressure air plasma inactivation of bacteria cells in aqueous media.

  1. Dispersion of Nanomaterials in Aqueous Media: Towards Protocol Optimization.

    Science.gov (United States)

    Kaur, Inder; Ellis, Laura-Jayne; Romer, Isabella; Tantra, Ratna; Carriere, Marie; Allard, Soline; Mayne-L'Hermite, Martine; Minelli, Caterina; Unger, Wolfgang; Potthoff, Annegret; Rades, Steffi; Valsami-Jones, Eugenia

    2017-12-25

    The sonication process is commonly used for de-agglomerating and dispersing nanomaterials in aqueous based media, necessary to improve homogeneity and stability of the suspension. In this study, a systematic step-wise approach is carried out to identify optimal sonication conditions in order to achieve a stable dispersion. This approach has been adopted and shown to be suitable for several nanomaterials (cerium oxide, zinc oxide, and carbon nanotubes) dispersed in deionized (DI) water. However, with any change in either the nanomaterial type or dispersing medium, there needs to be optimization of the basic protocol by adjusting various factors such as sonication time, power, and sonicator type as well as temperature rise during the process. The approach records the dispersion process in detail. This is necessary to identify the time points as well as other above-mentioned conditions during the sonication process in which there may be undesirable changes, such as damage to the particle surface thus affecting surface properties. Our goal is to offer a harmonized approach that can control the quality of the final, produced dispersion. Such a guideline is instrumental in ensuring dispersion quality repeatability in the nanoscience community, particularly in the field of nanotoxicology.

  2. Reactive transport of aqueous protons in porous media

    KAUST Repository

    McNeece, Colin J.

    2016-10-09

    The sorption of protons determines the surface charge of natural media and is therefore a first-order control on contaminant transport. Significant effort has been extended to develop chemical models that quantify the sorption of protons at the mineral surface. To compare these models’ effect on predicted proton transport, we present analytic solutions for column experiments through silica sand. Reaction front morphology is controlled by the functional relationship between the total sorbed and total aqueous proton concentrations. An inflection point in this function near neutral pH leads to a reversal in the classic front formation mechanism under basic conditions, such that proton desorption leads to a self-sharpening front, while adsorption leads to a spreading front. A composite reaction front comprising both a spreading and self-sharpening segment can occur when the injected and initial concentrations straddle the inflection point. This behavior is unique in single component reactive transport and arises due to the auto-ionization of water rather than electrostatic interactions at the mineral surface. We derive a regime diagram illustrating conditions under which different fronts occur, highlighting areas where model predictions diverge. Chemical models are then compared and validated against a systematic set of column experiments.

  3. Smart surfaces with switchable superoleophilicity and superoleophobicity in aqueous media: Toward controllable oil/water separation

    KAUST Repository

    Zhang, L.; Zhang, Z.; Wang, Peng

    2012-01-01

    Advanced materials with surfaces that have controllable oil wettability when submerged in aqueous media have great potential for various underwater applications. Here we have developed smart surfaces on commonly used materials, including non

  4. Synthesis and functionalization of dextran-based single-chain nanoparticles in aqueous media

    OpenAIRE

    Gracia R.; Marradi M.; Cossío U.; Benito A.; Pérez-San Vicente A.; Gómez-Vallejo V.; Grande H.-J.; Llop J.; and Loinaz I.

    2017-01-01

    Water-dispersible dextran-based single-chain polymer nanoparticles (SCPNs) were prepared in aqueous media and under mild conditions. Radiolabeling of the resulting biocompatible materials allowed the study of lung deposition of aqueous aerosols after intratracheal nebulization by means of single-photon emission computed tomography (SPECT), demonstrating their potential use as imaging contrast agents.

  5. Review Dendrimer : Definisi, Sintesis, Aplikasi Dan Prospektif

    OpenAIRE

    Rahmi, Dwinna

    2013-01-01

    Dendrimer merupakan makrostruktur monodisperse dengan banyak cabang yang homogen dan degree of branching (DB) 100%. Dua cara sintesis dendrimer yaitu convergent dan divergent dilakukan. Convergent dilakukan dengan reaksi kovalen antara dua dan lebih monomer. Divergent dimulai dengan pembentukan inti dilanjutkan dengan pembentukan cabang yang merupakan group fungsional yang aktif. Sejauh ini dendrimer sudah banyak diterapkan pada bidang farmasi yaitu drug delivery dan non farmasi pada proses i...

  6. Dynamics of anion exchange of lanthanides in aqueous-organic complexing media

    International Nuclear Information System (INIS)

    Sheveleva, I.V.; Bogatyrev, I.O.

    1987-01-01

    Effect of organic solvents (ethanol, acetone, acetonitrile) on change in kinetic parameters of the anion exchange process (anion-exchange column chromatography) of r.e.e. (europium and gadolinium) in complexing nitric acid media has been studied. It is established that complex LnA 4 anion is the only sorbing form of europium and gadolinium on anionite. When the organic component content of the solution being the same, the dynamic parameters of lanthanide exchange have higher values in aqueous-acetonitrile and aqueous-acetone media in comparison with aqueous-enthanol solutions of nitric acid. Lesser mobility of complex lanthanide anions in aqueous-alcoholic solutions can be explained by stronger solvation in the presence of solvents with higher acceptor properties

  7. Pitting morphologies of zirconium base alloys in aqueous and non aqueous chloride media

    International Nuclear Information System (INIS)

    Palit, G.C.; Gadiyar, H.S.

    1988-01-01

    Pitting morphology of zirconium and Zr-Cr alloys in aqueous chloride and nonaqueous methanol + 0.4 per cent HCl solution was investigated and observed to follow different modes in these two environments. While in aqueous chloride solution pitting was transgranular and randomly oriented, in methanol-chloride solution pits were observed to initiate and propagate along the grain boundaries. In aqueous chloride solution very irregular and sponge like zirconium metal was formed inside the pit while in methanol-chloride solution the pits were crystallographic in nature. Optical microscopy has revealed that pits preferentially initiate and propagate along scratch line in aqueous chloride solution, but such was not the case in nonaqueous methanol-chloride solution. The nature and the mechanism operating in the catastropic failure of these materials are investigated. (author). 10 refs., 11 figs

  8. Reactive transport of aqueous protons in porous media

    KAUST Repository

    McNeece, Colin J.; Hesse, Marc A.

    2016-01-01

    and total aqueous proton concentrations. An inflection point in this function near neutral pH leads to a reversal in the classic front formation mechanism under basic conditions, such that proton desorption leads to a self-sharpening front, while adsorption

  9. Synthesis of iron oxide nanoparticles under oxidizing environment and their stabilization in aqueous and non-aqueous media

    International Nuclear Information System (INIS)

    Maity, D.; Agrawal, D.C.

    2007-01-01

    Synthesis of magnetite (Fe 3 O 4 ) nanoparticles under oxidizing environment by precipitation from aqueous media is not straightforward because Fe 2+ gets oxidized to Fe 3+ and thus the ratio of Fe 3+ :Fe 2+ =2:1 is not maintained during the precipitation. A molar ratio of Fe 3+ :Fe 2+ smaller than 2:1 has been used by many to compensate for the oxidation of Fe 2+ during the preparation. In this work, we have prepared iron oxide nanoparticles in air environment by the precipitation technique using initial molar ratios Fe 3+ :Fe 2+ ≤2:1. The phases of the resulting powders have been determined by several techniques. It is found that the particles consist mainly of maghemite with little or no magnetite phase. The particles have been suspended in non-aqueous and aqueous media by coating the particles with a single layer and a bilayer of oleic acid, respectively. The particle sizes, morphology and the magnetic properties of the particles and the ferrofulids prepared from these particles are reported. The average particle sizes obtained from the TEM micrographs are 14, 10 and 9 nm for the water, kerosene and dodecane-based ferrofluids, respectively, indicating a better dispersion in the non-aqueous media. The specific saturation magnetization (σ s ) value of the oleic-acid-coated particles (∼53 emu/g) is found to be lower than that for the uncoated particles (∼63 emu/g). Magnetization σ s of the dodecane-based ferrofluid is found to be 10.1 emu/g for a volume fraction of particles φ=0.019. Zero coercivity and zero remanance on the magnetization curves indicate that the particles are superparamagnetic (SPM) in nature

  10. Aqueous citric acid as green reaction media for the synthesis of octahydroxanthenes

    Directory of Open Access Journals (Sweden)

    Camilo A. Navarro D.

    2013-08-01

    Full Text Available A simple, convenient and environmentally friendly one-pot procedure for the synthesis of 1,8-dioxo-octahydroxanthenes by the reaction of dimedone and aromatic aldehydes in aqueous citric acid is described. In this green synthetic protocol promoted by the reaction media, the use of any other catalysts and hazardous organic solvents are avoided, making the work up procedure greener and easier. The isolation of the products, obtained in good yields, is readily performed by filtration and crystallization from ethanol when required and the aqueous acidic media can be easily recycled and reused several times without significant loss of catalytic activity.

  11. Uranium chemistry in blood and aqueous media. Techniques of studies

    International Nuclear Information System (INIS)

    Scapolan, St.

    1996-11-01

    The object of this report in a first step, is to understand the chemistry of uranium in aqueous phase by specifying the behavior of this element in function of several parameters such PH, concentration of present species, temperature, ionic force. In a second step, investigation techniques are reviewed: X rays diffraction, potentiometric titrations, polarography, spectrophotometry, NMR of 13 C, 31 P, 17 O, capillary electrophoresis, laser detection. The third part brings elements to understand the uranium complexation in blood medium

  12. Lignin transformations and reactivity upon ozonation in aqueous media

    Science.gov (United States)

    Khudoshin, A. G.; Mitrofanova, A. N.; Lunin, V. V.

    2012-03-01

    The reaction of ozone with lignin in aqueous acidic solutions is investigated. The Danckwerst model is used to describe the kinetics of gas/liquid processes occurring in a bubble reactor. The efficient ozonation rate of a soluble lignin analog, sodium lignosulfate, is determined. The main lines of the reaction between ozone and lignin are revealed on the basis of kinetic analysis results and IR and UV spectroscopy data.

  13. Recovery of homogeneous polyoxometallate catalysts from aqueous and organic media by a mesoporous ceramic membrane without loss of catalytic activity

    NARCIS (Netherlands)

    Roy Chowdhury, S.; Roy Chowdhury, Sankhanilay; Witte, Peter T.; Blank, David H.A.; Alsters, Paul L.; ten Elshof, Johan E.

    2006-01-01

    The recovery of homogeneous polyoxometallate (POM) oxidation catalysts from aqueous and non-aqueous media by a nanofiltration process using mesoporous γ-alumina membranes is reported. The recovery of Q12[WZn3(ZnW9O34)2] (Q=[MeN(n-C8H17)3]+) from toluene-based media was quantitative within

  14. Bioremediation techniques applied to aqueous media contaminated with mercury.

    Science.gov (United States)

    Velásquez-Riaño, Möritz; Benavides-Otaya, Holman D

    2016-12-01

    In recent years, the environmental and human health impacts of mercury contamination have driven the search for alternative, eco-efficient techniques different from the traditional physicochemical methods for treating this metal. One of these alternative processes is bioremediation. A comprehensive analysis of the different variables that can affect this process is presented. It focuses on determining the effectiveness of different techniques of bioremediation, with a specific consideration of three variables: the removal percentage, time needed for bioremediation and initial concentration of mercury to be treated in an aqueous medium.

  15. Specific acid catalysis and Lewis acid catalysis of Diels–Alder reactions in aqueous media

    NARCIS (Netherlands)

    Mubofu, Egid B.; Engberts, Jan B.F.N.

    2004-01-01

    A comparative study of specific acid catalysis and Lewis acid catalysis of Diels–Alder reactions between dienophiles (1, 4 and 6) and cyclopentadiene (2) in water and mixed aqueous media is reported. The reactions were performed in water with copper(II) nitrate as the Lewis acid catalyst whereas

  16. Specific acid catalysis and Lewis acid catalysis of Diels-Alder reactions in aqueous media

    NARCIS (Netherlands)

    Mubofu, E.B.; Engberts, J.B.F.N.

    A comparative study of specific acid catalysis and Lewis acid catalysis of Diells-Alder reactions between dienophiles (1, 4 and 6) and cyclopentadiene (2) in water and mixed aqueous media is reported. The reactions were performed in water with copper(II) nitrate as the Lewis acid catalyst whereas

  17. Smart surfaces with switchable superoleophilicity and superoleophobicity in aqueous media: Toward controllable oil/water separation

    KAUST Repository

    Zhang, L.

    2012-02-01

    Advanced materials with surfaces that have controllable oil wettability when submerged in aqueous media have great potential for various underwater applications. Here we have developed smart surfaces on commonly used materials, including non-woven textiles and polyurethane sponges, which are able to switch between superoleophilicity and superoleophobicity in aqueous media. The smart surfaces are obtained by grafting a block copolymer, comprising blocks of pH-responsive poly(2-vinylpyridine) and oleophilic/hydrophobic polydimethylsiloxane (i.e., P2VP-b-PDMS) on these materials. The P2VP block can alter its wettability and its conformation via protonation and deprotonation in response to the pH of the aqueous media, which provides controllable and switchable access of oil by the PDMS block, resulting in the switchable surface oil wettability in the aqueous media. On the other hand, the high flexibility of the PDMS block facilitates the reversible switching of the surface oil wettability. As a proof of concept, we also demonstrate that materials functionalized with our smart surfaces can be used for highly controllable oil/water separation processes.

  18. Extraction from aqueous media novocaine aliphatic alcohols using salting out agent

    Directory of Open Access Journals (Sweden)

    Y. I. Korenman

    2012-01-01

    Full Text Available The choice of rational conditions for the extraction of novocaine. Development of effective extraction systems for almost its complete removal from aqueous media. Establishing correlations between coefficients distribution (lgD novocaine and the number of C–atoms in a molecule of alcohol.

  19. Removal of Ni (II), Co (II) and Pb (II) ions from aqueous media using ...

    African Journals Online (AJOL)

    Removal of Ni (II), Co (II) and Pb (II) ions from aqueous media using Starch ... The results showed that 0.025 % loaded SSMNPs gave the optimal sorption ... constants (Lagergren and Pseudo-2nd-order) for Ni2+ and Co2+ adsorption were ... Langmuir correlation coefficients showed a better fit for the adsorption isotherms.

  20. Mechanistic and kinetic aspects of pentose dehydration towards furfural in aqueous media employing homogeneous catalysis

    NARCIS (Netherlands)

    Danon, B.; Marcotullio, G.; De Jong, W.

    2013-01-01

    In this paper both the mechanistic and kinetic aspects of furfural formation from pentoses in aqueous acidic media have been reviewed. Based on the reviewed literature, a comprehensive reaction mechanism has been proposed consisting of more than one route, all starting from acyclic xylose, and

  1. Behaviour of polycrystalline fluoride-selective membrane electrode in aqueous-organic media

    International Nuclear Information System (INIS)

    Manakova, L.I.; Bausova, N.V.; Moiseev, V.E.; Bamburov, V.G.; Sivoplyas, A.P.

    1978-01-01

    The behaviour of polycrystalline fluoride membrane electrode (RFME) in aqueous-organic media has been studied when the content of the organic component (methanol, ethanol, acetone, dioxane) has been changed from 20 to 80 mass%. Since LaF 3 is the base of the membrane, its solubility has been studied depending on the organic component content in the solution. It has been established that LaF 3 solubility decreases with increasing content of of the organic component. This explains the effect of the composition of an aqueous-organic solvent on the electrode sensitivity. The electrode sensitivity rises with increasing content of the organic component in an aqueous-organic solvent. A greater decrease of LaF 3 solubility in aqueous-organic solvents as compared with that of LaCl 3 , La(NO 3 ) 3 , and La 2 (SO 4 ) 3 causes a higher selectivity of RFME with respect to the anions under study

  2. Synthesis of Co–Al layered double hydroxide nanoclusters as reduction nanocatalyst in aqueous media

    Directory of Open Access Journals (Sweden)

    Daisuke Kino

    2017-12-01

    Full Text Available Layered double hydroxides (LDHs have attracted attention as green materials due to their catalytic ability in benign aqueous solvents. We here demonstrate the synthesis of colloidal Co–Al LDH nanoclusters with an average size of <10 nm via a facile liquid-phase reaction for the enhancement of the catalytic activity. To the best of our knowledge, the present LDH is the smallest Co–Al LDH with an extremely large surface area and stability in an aqueous solvent, forming a stable and concentrated colloidal solution as high as 40 g/L. We investigated the formation mechanism, and the catalytic activity of Co–Al LDH nanoclusters. The Co–Al LDH nanoclusters showed 47 times higher rate of the reduction of dye molecules in the aqueous media than standard Co–Al LDH particles with a micrometer size. LDH nanoclusters demonstrated here are promising green nanocatalysts for the aqueous reaction processes.

  3. Dose monitoring in large-scale flowing aqueous media

    International Nuclear Information System (INIS)

    Kuruca, C.N.

    1995-01-01

    The Miami Electron Beam Research Facility (EBRF) has been in operation for six years. The EBRF houses a 1.5 MV, 75 KW DC scanned electron beam. Experiments have been conducted to evaluate the effectiveness of high-energy electron irradiation in the removal of toxic organic chemicals from contaminated water and the disinfection of various wastewater streams. The large-scale plant operates at approximately 450 L/min (120 gal/min). The radiation dose absorbed by the flowing aqueous streams is estimated by measuring the difference in water temperature before and after it passes in front of the beam. Temperature measurements are made using resistance temperature devices (RTDs) and recorded by computer along with other operating parameters. Estimated dose is obtained from the measured temperature differences using the specific heat of water. This presentation will discuss experience with this measurement system, its application to different water presentation devices, sources of error, and the advantages and disadvantages of its use in large-scale process applications

  4. Predicting Upscaled Behavior of Aqueous Reactants in Heterogeneous Porous Media

    Science.gov (United States)

    Wright, E. E.; Hansen, S. K.; Bolster, D.; Richter, D. H.; Vesselinov, V. V.

    2017-12-01

    When modeling reactive transport, reaction rates are often overestimated due to the improper assumption of perfect mixing at the support scale of the transport model. In reality, fronts tend to form between participants in thermodynamically favorable reactions, leading to segregation of reactants into islands or fingers. When such a configuration arises, reactions are limited to the interface between the reactive solutes. Closure methods for estimating control-volume-effective reaction rates in terms of quantities defined at the control volume scale do not presently exist, but their development is crucial for effective field-scale modeling. We attack this problem through a combination of analytical and numerical means. Specifically, we numerically study reactive transport through an ensemble of realizations of two-dimensional heterogeneous porous media. We then employ regression analysis to calibrate an analytically-derived relationship between reaction rate and various dimensionless quantities representing conductivity-field heterogeneity and the respective strengths of diffusion, reaction and advection.

  5. A new polymeric adsorbent developing for uranium recovering and richment from aqueous media

    International Nuclear Information System (INIS)

    Gueler, H.; Aycik, G. A.; Sahiner, N.; Gueven, O.

    1997-01-01

    Using adsorbents is thought to be the most effective method for recovering the low concentrations of uranium in the aqueous media because of their fast and selective uptake of uranium, a sufficient adsorption capacity and high physical and chemical stability against the media. In this study, a new polymeric adsorbent bearing both hydrophilic groups providing swelling in water and amidoxime groups for chelating with uranyl ions (UO 2 ''2+) has been developed and its adsorptive ability for uranium from aqueous media has been investigated. The polymers obtained by irradiating the solution of polyethylene glycol (PEG) in acrylonitrile (AN) are defined as Interpenetrating Polymer Networks (IPNs) and the adsorbent has been obtained by applying the amidoximation reaction to the IPNs with a conversion of % 60 approximately. Kinetics of the conversion reaction of nitrile (CN) group to amidoxime (HONCNH 2 ) group has been studied by reacting with hydroxylamine (NH 2 OH) solution at a molar ratio of NH 2 OH/CN=1.25 in aqueous media at different temperatures, 30,40,50''0C, for 3-4 days. The degree of amidoximation was determined by UO 2 ''2+ ion adsorption and FTIR spectrometer and the UO 2 ''2+ ion adsorption values were found by both UV and gamma spectrometry and also by gravimetry. It was found that the polymeric adsorbent has a very high adsorption ability for uranium (∼ 540 mg U/g IPN/day)

  6. Dissolution of anodic zirconium dioxide films in aqueous media

    International Nuclear Information System (INIS)

    Merati, A.; Cox, B.

    1999-01-01

    Zirconium with a low thermal neutron cross section, good corrosion resistance in high-temperature water, and high thermal conductivity is an ideal material for nuclear reactors. Its good resistance to water and steam at reactor temperatures is of the greatest interest to nuclear fuel designers. Dissolution of zirconium dioxide (ZrO 2 ) films in aggressive media was investigated. The extent of uniform and localized dissolution was measured by ultraviolet-visible (UV-VIS) spectrometry and an alternating current (AC) impedance test, respectively. Scanning electron microscopy (SEM) showed the extent of dissolution of ZrO 2 was a function only of the fluoride ion content and pH of the medium. Cathodic polarization was used to identify the preferred sites for localized dissolution of the oxide film. In 0.1 M potassium bifluoride (KHF 2 ), both uniform thinning and local breakdown of the oxide were observed. Within the limits of the investigating techniques, no evidence of dissolution was observed in the other solutions tested: 0.5 M sulfuric acid (H 2 SO 4 ). 1.0 M nitric acid (HNO 3 ), 5 M hydrochloric acid (HCl), or 0.1 M potassium fluoride (KF). In areas around iron-containing particles, fine cracks in the anodic oxide at prior metal grain boundaries and arrays of cracks in the oxide associated with residual scratches from the initial specimen preparation were the preferred spots for localized dissolution of the oxide film. Iron precipitates immediately below the surface of the oxide layer increased the local electrical conductivity. Enrichment of iron in the oxide matrix around these precipitates during the anodization process appeared to cause prospective spots, acting as anodic sites for pH formation

  7. Detection of biologically important anions in aqueous media by dicationic azaborines bearing ammonio or phosphonio groups.

    Science.gov (United States)

    Agou, Tomohiro; Sekine, Masaki; Kobayashi, Junji; Kawashima, Takayuki

    2009-01-01

    New cationic triarylboranes bearing ammonio or phosphonio groups on the periphery were synthesized from a common intermediate, a dibromodibenzoazaborine. These cationic molecules are soluble in highly polar organic solvents as well as water, and they exhibit strong light absorption and photoluminescence emission in water. Complexation of the cationic azaborines with fluoride and cyanide ions in aqueous media proceeded and could be monitored by NMR, UV/Vis, and fluorescence spectroscopy.

  8. Ultrasonic Assisted Synthesis of Chromenes Catalyzed by Sodium Carbonate in Aqueous Media.

    Science.gov (United States)

    Sabbaghan, Maryam; Sofalgar, Pegah

    2015-01-01

    A simple, efficient, and environmentally benign procedure for the synthesis of 2-amino-4H-chromene ring has been achieved by the three-component reaction of an aromatic aldehyde, malononitrile and diverse enolizable C-H activated compound under ultrasound irradiation using sodium carbonate as a catalyst in aqueous media. Sodium carbonate as a natural salt, being available as an inexpensive catalyst combined with ultrasound method promoted this protocol in comparison to other methods and catalysts.

  9. Spontaneous and Directional Bubble Transport on Porous Copper Wires with Complex Shapes in Aqueous Media.

    Science.gov (United States)

    Li, Wenjing; Zhang, Jingjing; Xue, Zhongxin; Wang, Jingming; Jiang, Lei

    2018-01-24

    Manipulation of gas bubble behaviors is crucial for gas bubble-related applications. Generally, the manipulation of gas bubble behaviors generally takes advantage of their buoyancy force. It is very difficult to control the transportation of gas bubbles in a specific direction. Several approaches have been developed to collect and transport bubbles in aqueous media; however, most reliable and effective manipulation of gas bubbles in aqueous media occurs on the interfaces with simple shapes (i.e., cylinder and cone shapes). Reliable strategies for spontaneous and directional transport of gas bubbles on interfaces with complex shapes remain enormously challenging. Herein, a type of 3D gradient porous network was constructed on copper wire interfaces, with rectangle, wave, and helix shapes. The superhydrophobic copper wires were immersed in water, and continuous and stable gas films then formed on the interfaces. With the assistance of the Laplace pressure gradient between two bubbles, gas bubbles (including microscopic gas bubbles) in the aqueous media were subsequently transported, continuously and directionally, on the copper wires with complex shapes. The small gas bubbles always moved to the larger ones.

  10. Effect of passivation on the sensitivity and stability of pentacene transistor sensors in aqueous media

    KAUST Repository

    Khan, Hadayat Ullah

    2011-06-01

    Charge-detecting biosensors have recently become the focal point of biosensor research, especially research onto organic thin-film transistors (OTFTs), which combine compactness, a low cost, and fast and label-free detection to realize simple and stable in vivo diagnostic systems. We fabricated organic pentacene-based bottom-contact thin-film transistors with an ultra-thin insulating layer of a cyclized perfluoro polymer called CYTOP (Asahi Glass Co., Tokyo, Japan) on SiO2 for operation in aqueous media. The stability and sensitivity of these transistor sensors were examined in aqueous buffer media with solutions of variable pH levels after the passivation of perfluoro polymers with thicknesses ranging from 50 to 300nm. These transistor sensors were further modified with an ultra-thin film (5nm) functional layer for selective BSA/antiBSA detection in aqueous buffer media, demonstrating a detection capability as low as 500nM of concentrated antiBSA. The dissociation constant from the antiBSA detection results was 2.1×10-6M. Thus, this study represents a significant step forward in the development of organic electronics for a disposable and versatile chemical and bio-sensing platform. © 2011 Elsevier B.V.

  11. New chemistry of the uranyl ion in non aqueous media

    International Nuclear Information System (INIS)

    Siffredi, G.

    2008-12-01

    (M= Li, X= OTf) or [{UO 2 (py) 5 }2(M 3 X 5 )] ∞ (M= K; X= OTf). With precipitation of insoluble MX salt (TlI in pyridine for example), reactions give mononuclear species like [UO 2 (py) 5 ][I]. Once again, the results presented here highlight the advantage of handling uranyl(VI) compounds in strictly anhydrous and deoxygenated media and further demonstrate that uranyl chemistry will witness novel developments under such experimental conditions. (author)

  12. Synthesis and characterization of conditioned carbon with iron nanoparticles for the arsenic removal in aqueous phase; Sintesis y caracterizacion de carbon acondicionado con nanoparticulas de hierro para la remocion de arsenico en fase acuosa

    Energy Technology Data Exchange (ETDEWEB)

    Flores C, D. O.

    2012-07-01

    Using pineapple husks conditioned with carboxymethylcellulose, hexamine and ferric nitrate, a carbonaceous material was obtained with nanoparticles of Fe (C Fe), which was characterized and tested for arsenic removal in the aqueous phase. The microscopic study showed spheres 4 microns and filaments 100 nm wide, so as iron particles whose diameter decreases to an average of 38.81 nm, when pyrolysis time was increased to 180 min. their distribution in the carbonaceous matrix is homogeneous. According to energy dispersive X-ray spectroscopy, C Fe contains C (82.29%), O (7.23%), K (0.68%), Ca (3.77%) and Fe (6.25%) and its diffraction pattern shows the characteristic peak of Fe (0), which is not observed in the coal without iron. By neutron activation analysis were quantified Al, Br, Ce, Co, Cr, Cs, Eu, Hf, K, Mg, Mn, Na, Rb, Sb, Sc and Zn, they can be involved in the process of sorption of As (v) forming surface active sites. For C Fe and C B characterized by Fourier transform infrared spectrometry, groups C-H, C=O, C=C, -Nh, NH{sub 2}, isocyanate and isonitrile were found, the last two were formed by the present hexamine. X-ray photoelectron spectroscopy showed energy states of C 1 and O 1 in pineapple shell washed, shell conditioned with iron, C Fe at different times and the pyrolysis coal without iron (C B). The material C Fe 180 presented a specific area of 167 m{sup 2}/g and 7.12 {+-} 1 sites/nm{sup 2} isoelectric point while pH{sub i} = 11.1 C B is 98.80 m{sup 2}/g specific area and 1.5 {+-} 1 sites/nm{sup 2} and pH{sub i} = 10.6, being favorable to the sorption process. The highest removal of As(v) for both materials was at ph = 2, fitting the kinetic data to pseudo-second order model. The isotherms as a function of concentration were adjusted to Freundlich model indicating multilayer chemisorption at specific sites of a heterogeneous medium. Characterization by scanning electron microscopy after the sample sorption Fe nanoparticles remain in the carbonaceous

  13. Aqueous media treatment and decontamination of hazardous chemical and biological substances by contact plasma

    International Nuclear Information System (INIS)

    Pivovarov, A.; Kravchenko, A.; Kublanovsky, V.

    2009-01-01

    Usage of non-equilibrium contact plasma for processes of decontamination and neutralization in conditions of manifestation of chemical, biological and radiation terrorism takes on special significance due to portability of equipment and its mobility in places where toxic liquid media hazardous for people's health are located. Processes of decontamination of aqueous media, seminated with pathogenic microorganisms and viruses, treatment of water containing toxic heavy metals, cyanides, surface-active substances, and heavy radioactive elements, are investigated. Examples of activation processes in infected water and toxic aqueous solutions present convincing evidence of the way, how new quality technological approach for achievement of high enough degree of the said media treatment is used in each specific case. Among new properties of water activated as a result of action of non-equilibrium contact plasma, it is necessary to mention presence of cluster structure, confirmed by well-known spectral and physical-chemical methods, presence of peroxide compounds, active particles and radicals. Anti-microbial activity which is displayed under action of plasma in aqueous media (chemically pure water, drinking water, aqueous solutions of sodium chloride, potassium iodide, as well as other inorganic compounds) towards wide range of pathogenic and conventionally pathogenic microorganisms allows use them as reliable, accessible and low-cost preparations for increasing the degree of safety of food products. Combination of such processes with known methods of filtration and ultra-filtration gives an efficient and available complex capable of withstanding any threats, which may arise for population and living organisms. Present-day level of machine-building, electrical engineering, and electronics allows predict creation of industrial plasma installations, adapted to conditions of various terrorist threats, with minimized power consumption and optimized technological parameters

  14. Aqueous media treatment and decontamination of hazardous chemical and biological substances by contact plasma

    Energy Technology Data Exchange (ETDEWEB)

    Pivovarov, A; Kravchenko, A [Ukrainian State University of Chemical Engineering, Dnepropetrovsk (Ukraine); Kublanovsky, V [V. I. Vernadsky Institute of General and Inorganic Chemistry of National Academy of Science, Kiev (Ukraine)

    2009-07-01

    Usage of non-equilibrium contact plasma for processes of decontamination and neutralization in conditions of manifestation of chemical, biological and radiation terrorism takes on special significance due to portability of equipment and its mobility in places where toxic liquid media hazardous for people's health are located. Processes of decontamination of aqueous media, seminated with pathogenic microorganisms and viruses, treatment of water containing toxic heavy metals, cyanides, surface-active substances, and heavy radioactive elements, are investigated. Examples of activation processes in infected water and toxic aqueous solutions present convincing evidence of the way, how new quality technological approach for achievement of high enough degree of the said media treatment is used in each specific case. Among new properties of water activated as a result of action of non-equilibrium contact plasma, it is necessary to mention presence of cluster structure, confirmed by well-known spectral and physical-chemical methods, presence of peroxide compounds, active particles and radicals. Anti-microbial activity which is displayed under action of plasma in aqueous media (chemically pure water, drinking water, aqueous solutions of sodium chloride, potassium iodide, as well as other inorganic compounds) towards wide range of pathogenic and conventionally pathogenic microorganisms allows use them as reliable, accessible and low-cost preparations for increasing the degree of safety of food products. Combination of such processes with known methods of filtration and ultra-filtration gives an efficient and available complex capable of withstanding any threats, which may arise for population and living organisms. Present-day level of machine-building, electrical engineering, and electronics allows predict creation of industrial plasma installations, adapted to conditions of various terrorist threats, with minimized power consumption and optimized technological parameters

  15. Fundamental investigation of the transport properties of superacids in aqueous and non-aqueous media

    Science.gov (United States)

    Suarez, Sophia

    In the quest to develop more efficient energy providers one of the main focus of research has been on the improvement of ion transport. In lithium battery research this has led to the incorporation of various lithium salts, ceramics and plasticizers into the poly(ethylene)oxide (PEO) matrix, the polymer most used In Proton Conduction Membrane (PCM) fuel cell research this has led to the development of new membranes, which are designed with to replicate Nafion's ((c)DuPont) proton transport but also improve upon its deficiency of transporting intact fuel molecules and its dependence upon the presence of solvating water molecules. To better understand the process of ion transport, NMR was used to investigate dynamic properties such as D (self-diffusion coefficient) and T1 (spin-lattice relaxation time) of various proton and lithium ion-conducting systems. Ionic conductivity and viscosity measurements were also performed. The systems studied includes aqueous superacid solutions (trifluoromethanesulfonic (TFSA), para-toluenesulfonic (PTSA) and bis(trifluoromethanesulfonyl)imide (TFSI)); nano-porous (NP-) PCM's incorporating various ceramics and 3M fuel/2M H2SO4 solutions; and P(EO)20LiBETI (LiN(SO 2CF2CF3)2 composite incorporating SiO 2 ceramic nano particles. The objective of the study of the superacid solutions was to determine the effect of concentration on the transport. It was found that beyond the ionic conductivity maximum, fluctuations in both D and T1 supports the existence of local ordering in the ionic network, caused by the reduced solvent dielectric coefficient and increasing viscosity. Of the three superacids TFSA was the most conductive and most affected by reduced solvent concentration. For the P(EO)20LiBETI composite the aim was to determine the effect of the ceramic on the ion transport of the composite in a solvent free environment. Results show that the ceramic causes only modest increase in the lithium transport below 90°C. The objective in the

  16. Effect of Aqueous Media on the Recovery of Scandium by Selective Precipitation

    Directory of Open Access Journals (Sweden)

    Bengi Yagmurlu

    2018-05-01

    Full Text Available This research presents a novel precipitation method for scandium (Sc concentrate refining from bauxite residue leachates and the effect of aqueous media on this triple-stage successive precipitation process. The precipitation pattern and the precipitation behavior of the constituent elements was investigated using different precipitation agents in three major mineral acid media, namely, H2SO4, HNO3, and HCl in a comparative manner. Experimental investigations showed behavioral similarities between HNO3 and HCl media, while H2SO4 media was different from them because of the nature of the formed complexes. NH4OH was found to be the best precipitation agent in every leaching media to remove Fe(III with low Sc co-precipitation. To limit Sc loss from the system, Fe(III removal was divided into two steps, leading to more than 90% of Fe(III removal at the end of the process. Phosphate concentrates were produced in the final step of the precipitation process with dibasic phosphates which have a strong affinity towards Sc. Concentrates containing more than 50% of ScPO4 were produced in each case from the solutions after Fe(III removal, as described. A flow diagram of the selective precipitation process is proposed for these three mineral acid media with their characteristic parameters.

  17. Deep Eutectic Solvent Aqueous Solutions as Efficient Media for the Solubilization of Hardwood Xylans.

    Science.gov (United States)

    Morais, Eduarda S; Mendonça, Patrícia V; Coelho, Jorge F J; Freire, Mara G; Freire, Carmen S R; Coutinho, João A P; Silvestre, Armando J D

    2018-02-22

    This work contributes to the development of integrated lignocellulosic-based biorefineries by the pioneering exploitation of hardwood xylans by solubilization and extraction in deep eutectic solvents (DES). DES formed by choline chloride and urea or acetic acid were initially evaluated as solvents for commercial xylan as a model compound. The effects of temperature, molar ratio, and concentration of the DES aqueous solutions were evaluated and optimized by using a response surface methodology. The results obtained demonstrated the potential of these solvents, with 328.23 g L -1 of xylan solubilization using 66.7 wt % DES in water at 80 °C. Furthermore, xylans could be recovered by precipitation from the DES aqueous media in yields above 90 %. The detailed characterization of the xylans recovered after solubilization in aqueous DES demonstrated that 4-O-methyl groups were eliminated from the 4-O-methylglucuronic acids moieties and uronic acids (15 %) were cleaved from the xylan backbone during this process. The similar M w values of both pristine and recovered xylans confirmed the success of the reported procedure. DES recovery in four additional extraction cycles was also demonstrated. Finally, the successful extraction of xylans from Eucalyptus globulus wood by using aqueous solutions of DES was demonstrated. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Some aspects of synergistic extraction of actinides and lanthanides from mixed aqueous-organic media

    International Nuclear Information System (INIS)

    Shukla, J.P.; Subramanian, M.S.

    1981-01-01

    Various aspects of the synergistic extraction and separation of actinides and lanthanides from mixed aqueous-organic solutions (polar media) have been reviewed. Notable recent developments as well as its current status in solvent extraction systems where the aqueous acidic phase contains an organic solvent which is completely miscible with water, are presented briefly. In general, extraction increases in the presence of an organic component. The less polar the additive, the higher is the tendency to form neutral metal complexes which ultimately brings about an increase in the extraction. In a polar media, synergism has mostly been observed, though antagonism is not uncommon. An attempt has been made to classify the factors that play an important role in polar phase extractions. Also, their influence particularly on the extractability of actinides and lanthanides is discussed. The discussion is limited to the factors affecting the extraction equilibria, effect of dielectric constant of the polar medium, solvation of the extracting agent and to the composition and stability of the metal complex in the organic phase. Hydroxyl (OHsup(-)) bearing organic additives, e.g. alcohols, and solvents not containing the hydroxyl group such as acetone, dimethylsulphoxide, tetrahydrofuran, amides and acetonitrile etc. are the two major classes of organic additives considered in these studies. Generally, synergistic effect in extraction of the ion-association (TBP, TOPO, sulphoxides etc.) or anion exchange (amines etc.) type is relatively more pronounced compared to other extractions. A tabular summary concerning extraction of actinides and lanthanides from polar media is appended for ready reference. (author)

  19. A rapid method to estimate uranium using ionic liquid as extracting agent from basic aqueous media

    International Nuclear Information System (INIS)

    Prabhath Ravi, K.; Sathyapriya, R.S.; Rao, D.D.; Ghosh, S.K.

    2016-01-01

    Room temperature ionic liquids, as their name suggests are salts with a low melting point typically less than 100 °C and exist as liquid at room temperature. The common cationic parts of ionic liquids are imidazolium, pyridinium, pyrrolidinium, quaternary ammonium, or phosphonium ions, and common anionic parts are chloride, bromide, boron tetrafluorate, phosphorous hexafluorate, triflimide etc. The physical properties of ionic liquids can be tuned by choosing appropriate cations with differing alkyl chain lengths and anions. Application of ionic liquids in organic synthesis, liquid-liquid extractions, electrochemistry, catalysis, speciation studies, nuclear reprocessing is being studied extensively in recent times. In this paper a rapid method to estimate the uranium content in aqueous media by extraction with room temperature ionic liquid tricaprylammoniumthiosalicylate ((A- 336)(TS)) followed by liquid scintillation analysis is described. Re-extraction of uranium from ionic liquid phase to aqueous phase was also studied

  20. Curcumin based optical sensing of fluoride in organo-aqueous media using irradiation technique

    Science.gov (United States)

    Venkataraj, Roopa; Radhakrishnan, P.; Kailasnath, M.

    2017-06-01

    The present work describes the degradation of natural dye Curcumin in organic-aqueous media upon irradiation by a multi-wavelength source of light like mercury lamp. The presence of anions in the solution leads to degradation of Curcumin and this degradation is especially enhanced in the case of fluoride ion. The degradation of Curcumin is investigated by studying the change in its absorption and fluorescence characteristics in organoaqueous solution upon irradiation. A broad detection range of fluoride ranging from 2.3×10-6-2.22×10-3 M points to the potential of the method of visible light irradiation enabling aqueous based sensing of fluoride using Curcumin.

  1. Extraction of lithium ion from alkaline aqueous media by a liquid surfactant membrane

    International Nuclear Information System (INIS)

    Kinugasa, Takumi; Ono, Yuri; Kawamura, Yuko; Watanabe, Kunio; Takeuchi, Hiroshi.

    1995-01-01

    Extraction of lithium ion from aqueous alkaline media by a liquid surfactant membrane was performed using a mixture of LIX54 and TOPO as the extractant. Stripping of lithium from the kerosene solution to the acid solution was suppressed with increasing content of polyamine (ECA) surfactant. The extraction rate of lithium by the liquid membrane could be interpreted taking account of an interfacial resistance due to ECA. It was confirmed that swelling of the (W/O) emulsion drops by water permeation through the liquid membrane is evaluated in terms of a change in osmotic pressure gradient between the external and internal aqueous phases during the lithium extraction. In the present operation, the extraction ratio of Li + from the external feed and the uptake into the internal phase reached as high as 95%. (author)

  2. SINTESIS KOMPOSIT KITOSAN-SILIKA DAN APLIKASINYA SEBAGAI ADSORBEN ZAT WARNA TEKTIL

    Directory of Open Access Journals (Sweden)

    Warlan Sugiyo

    2011-02-01

    Full Text Available Sintesis kitosan-silika dilakukan terhadap kitosan penambahan silika dengan mengkarakteristik komposit yang dihasilkan. Penelitian ini bertujuan untuk mengkaji pengaruh penambahan silika pada larutan kitosan terhadap permeabilitas dan daya adsorpsinya terhadap zat warna tekstil Direct Blue 86. Pembuatan komposit menggunakan dua macam cara, yang pertama menggunakan media kertas saring dan yang kedua tanpa menggunakan kertas saring. Pembuatan komposit dengan menggunakan kertas saring memakai proses perendaman. Pembuatan komposit tanpa menggunakan kertas saring dilakukan dengan metode pencetakan membran. Membran komposit yang dihasilkan dikarakteristik dengan menggunakan foto SEM. Hasil penelitian menunjukkan bahwa penambahan silika pada larutan kitosan membuat komposit menjadi porogen sehingga fluks permeat dan permeabilitas air menjadi tinggi. Permeabilitas komposit secara keseluruhan dipengaruhi bagaimana pori-pori komposisi tersusun. Komposit yang terbuat dari kertas saring mempunyai daya adsorpsi yang lebih baik dibandingkan dengan komposit yang tanpa kertas saring.

  3. Polarografic study about the complex formation between indium (III) and sodium azide, in aqueous media

    International Nuclear Information System (INIS)

    Tokoro, R.; Bertotti, M.

    1988-01-01

    The present work is a branch of the main work concerned with the complex formation between several metal cations and azide ligand in aqueous media. The polarographic behavior of indium in azide system showed the tendency of complexation. Using polarographic method to determine the half potential of indium at each analytical concentration afforded experimental data to evaluate the constants. The azide concentrations was modified from 1 m to 100 m , the ionic strength held at 2,0 M with sodium perchlorate, indium concentration 7.892 x 10 -4 M, and temperature kept constant at 25,0 0 C. (author) [pt

  4. Suzuki-Miyaura cross-coupling reactions in aqueous media: Green and sustainable syntheses of biaryls

    KAUST Repository

    Polshettiwar, Vivek

    2010-02-28

    Carbon-carbon cross-coupling reactions are among the most important processes in organic chemistry, and Suzuki-Miyaura reactions are among the most widely used protocols for the formation of carbon-carbon bonds. These reactions are generally catalyzed by soluble palladium complexes with various ligands. However, the use of toxic organic solvents remains a scientific challenge and an aspect of economical and ecological relevance. This Review will summarize various recently developed significant methods by which the Suzuki-Miyaura coupling was conducted in aqueous media, and analyzes if they are "real green" protocols. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Suzuki-Miyaura cross-coupling reactions in aqueous media: green and sustainable syntheses of biaryls.

    Science.gov (United States)

    Polshettiwar, Vivek; Decottignies, Audrey; Len, Christophe; Fihri, Aziz

    2010-05-25

    Carbon-carbon cross-coupling reactions are among the most important processes in organic chemistry, and Suzuki-Miyaura reactions are among the most widely used protocols for the formation of carbon-carbon bonds. These reactions are generally catalyzed by soluble palladium complexes with various ligands. However, the use of toxic organic solvents remains a scientific challenge and an aspect of economical and ecological relevance. This Review will summarize various recently developed significant methods by which the Suzuki-Miyaura coupling was conducted in aqueous media, and analyzes if they are "real green" protocols.

  6. Stripping of uranium from Dehpa/kerosene solvents by different aqueous media

    International Nuclear Information System (INIS)

    Khorfan, S.; Stas, J.; Kassem, M.

    1998-01-01

    Stripping uranium from Dehpa/kerosene solvent is a crucial step in the recovery of uranium. Stripping was studied using different stripping media mainly ammonium carbonate, phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid. Stripping was measured at different operating conditions such as aqueous concentrations, temperatures, and Dehpa/kerosene concentrations. The results obtained showed that stripping by acid media increases with the acid concentration and follows the order: HF > H 3 PO 4 > H 2 SO 4 > HCl > HNO 3 . To achieve higher stripping by phosphoric acid it was found necessary to increase the temperature to 50 deg C, the acid concentration to 5 mol/l and to reduce the uranium to U 4+ . Stripping by basic media was found to increase with increasing concentration of the stripping media and to follow the order: Na 2 CO 3 > (NH 4 ) 2 CO 3 > NH 4 HCO 3 . Stripping by ammonium carbonate was found to increase with temperature and carbonate concentration. The stripping was optimized at 0.5 mol/l carbonate concentration and at a temperature of 50 deg C. Stripping was decreased by increasing concentration of Dehpa in kerosene and was depressed more by adding the synergant Topo to the Dehpa solvent especially at 1/4 mol/mol ratio. (author)

  7. Stripping of uranium from Dehpa/Kerosene solvents by different aqueous media

    International Nuclear Information System (INIS)

    Khorfan, S.; Stas, J.; Kassem, M.

    2000-01-01

    Stripping uranium from Dehpa/kerosene solvent is a crucial step in the recovery of uranium. Stripping was studied using different stripping media mainly ammonium carbonate, phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid. Stripping was measured at different operating conditions such as aqueous concentrations, temperatures, and Dehpa/kerosene concentrations. The results obtained showed that stripping by acid media increases with the acid concentration and follows the order: HF > H sub 3 Po sub 4 > H sub 2 S O sub 4 > HCl > HNO sub 3. To achieve higher stripping by phosphoric acid it was found necessary to increase the temperature to 50 deg C, the acid concentration to 5 mol/l and to reduce the uranium to U sup 4 sup +. Stripping by basic media was found to increase with increasing concentration of the stripping media and to follow the order: Na sub 2 CO sub 3 > (NH sub 4) sub 2 CO sub 3 > NH sub 4 HCO sub 3. Stripping by ammonium carbonate was found to increase with temperature and carbonate concentration. The stripping was optimized at 0.5 mol/l carbonate concentration and at a temperature of 50 deg C. Stripping was decreased by increasing concentration of Dehpa in kerosene and was depressed more by adding the synergant TOPO to the Dehpa solvent especially at 1/4 mol/mol ratio. (author)

  8. TiO{sub 2}-based photocatalytic disinfection of microbes in aqueous media: A review

    Energy Technology Data Exchange (ETDEWEB)

    Laxma Reddy, P.Venkata [Program in Environmental Science and Engineering, University of Texas El Paso, El Paso, TX 799038 (United States); Kavitha, Beluri [Department of Pharmacology, Kamineni Institute of Medical Sciences, Dr. NTRUHS, Vijayawada, Andhra Pradesh 520008 (India); Kumar Reddy, Police Anil [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 38541 (Korea, Republic of); Kim, Ki-Hyun, E-mail: kkim61@hanyang.ac.kr [Department of Civil & Environmental Engineering, Hanyang University, 222 Wangsimni-Ro, Seoul 04763 (Korea, Republic of)

    2017-04-15

    The TiO{sub 2} based photocatalyst has great potential for the disinfection/inactivation of harmful pathogens (such as E.coli in aqueous media) along with its well-known usefulness on various chemical pollutants. The disinfection property of TiO{sub 2} is primarily attributed to surface generation of reactive oxygen species (ROS) as well as free metal ions formation. Furthermore, its disinfection capacity and overall performance can be significantly improved through modifications of the TiO{sub 2} material. In this review, we provide a brief survey on the effect of various TiO{sub 2} materials in the disinfection of a wide range of environmentally harmful microbial pathogens (e.g., bacteria, fungi, algae, and viruses) in aqueous media. The influencing factors (such as reactor design, water chemistry, and TiO{sub 2} modifications) of such processes are discussed along with the mechanisms of such disinfection. It is believed that the combined application of disinfection and decontamination will greatly enhance the utilization of TiO{sub 2} photocatalyst as a potential alternative to conventional methods of water purification. - Highlights: • The advent of industrialization jeopardized the quality of drinking water. • TiO{sub 2} photocatalysis holds promise both in the degradation of pollutants and for disinfection. • The applicability of TiO{sub 2}-based decontamination is explored for microbial disinfection. • Here we provide a comprehensive review on titania-based photocatalysts for disinfection.

  9. Basicity comparison for di-substituted 4-nitropyridine derivatives in polar non-aqueous media

    International Nuclear Information System (INIS)

    Gurzynski, Lukasz; Puszko, Aniela; Chmurzynski, Lech

    2007-01-01

    Acid dissociation, as well as cationic homoconjugation equilibria have been studied potentiometrically in systems involving four di-substituted 4-nitropyridines and conjugate cationic acids in the polar non-aqueous solvents - aprotic protophobic acetonitrile (AN) and propylene carbonate (PC), the amphiprotic methanol (MeOH), and in the aprotic protophilic dimethyl sulfoxide (DMSO). The influence of solvent effect on the obtained acidity constants has been discussed. The acidity constants (expressed as pK a values) were compared with those previously determined in another polar protophobic aprotic solvent - acetone (AC), and obtained for the unsubstituted pyridine (Py). A comparison of the acid dissociation constants determined in all media studied has proved that the strength of the cationic acids increases on going from acetonitrile through propylene carbonate, acetone, and methanol to dimethyl sulfoxide. Furthermore, the values of acidity constants in the non-aqueous media have shown that in all the solvents studied they change according to the substituent effects. It has been also found that substituted 4-nitropyridine derivatives studied exhibit no tendency towards cationic homoconjugation in acetonitrile, propylene carbonate, and methanol and dimethyl sulfoxide. Moreover, it has been demonstrated that the acid dissociation constants determined by potentiometric titration method in all the solutions investigated correlate well with the calculated energy parameters of the protonation reactions in the gaseous phase

  10. Basicity comparison for di-substituted 4-nitropyridine derivatives in polar non-aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Gurzynski, Lukasz [Department of General and Inorganic Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Puszko, Aniela [Department of Organic Chemistry, School of Economics, Wroclaw (Poland); Chmurzynski, Lech [Department of General and Inorganic Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)], E-mail: lech@chemik.chem.univ.gda.pl

    2007-12-15

    Acid dissociation, as well as cationic homoconjugation equilibria have been studied potentiometrically in systems involving four di-substituted 4-nitropyridines and conjugate cationic acids in the polar non-aqueous solvents - aprotic protophobic acetonitrile (AN) and propylene carbonate (PC), the amphiprotic methanol (MeOH), and in the aprotic protophilic dimethyl sulfoxide (DMSO). The influence of solvent effect on the obtained acidity constants has been discussed. The acidity constants (expressed as pK{sub a} values) were compared with those previously determined in another polar protophobic aprotic solvent - acetone (AC), and obtained for the unsubstituted pyridine (Py). A comparison of the acid dissociation constants determined in all media studied has proved that the strength of the cationic acids increases on going from acetonitrile through propylene carbonate, acetone, and methanol to dimethyl sulfoxide. Furthermore, the values of acidity constants in the non-aqueous media have shown that in all the solvents studied they change according to the substituent effects. It has been also found that substituted 4-nitropyridine derivatives studied exhibit no tendency towards cationic homoconjugation in acetonitrile, propylene carbonate, and methanol and dimethyl sulfoxide. Moreover, it has been demonstrated that the acid dissociation constants determined by potentiometric titration method in all the solutions investigated correlate well with the calculated energy parameters of the protonation reactions in the gaseous phase.

  11. TiO2-based photocatalytic disinfection of microbes in aqueous media: A review.

    Science.gov (United States)

    Laxma Reddy, P Venkata; Kavitha, Beluri; Kumar Reddy, Police Anil; Kim, Ki-Hyun

    2017-04-01

    The TiO 2 based photocatalyst has great potential for the disinfection/inactivation of harmful pathogens (such as E.coli in aqueous media) along with its well-known usefulness on various chemical pollutants. The disinfection property of TiO 2 is primarily attributed to surface generation of reactive oxygen species (ROS) as well as free metal ions formation. Furthermore, its disinfection capacity and overall performance can be significantly improved through modifications of the TiO 2 material. In this review, we provide a brief survey on the effect of various TiO 2 materials in the disinfection of a wide range of environmentally harmful microbial pathogens (e.g., bacteria, fungi, algae, and viruses) in aqueous media. The influencing factors (such as reactor design, water chemistry, and TiO 2 modifications) of such processes are discussed along with the mechanisms of such disinfection. It is believed that the combined application of disinfection and decontamination will greatly enhance the utilization of TiO 2 photocatalyst as a potential alternative to conventional methods of water purification. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Spectroscopic and redox properties of curium and californium ions in concentrated aqueous carbonate-bicarbonate media

    International Nuclear Information System (INIS)

    Hobart, D.E.; Varlashkin, P.G.; Samhoun, K.; Haire, R.G.; Peterson, J.R.

    1983-01-01

    Multimilligram quantities of trivalent curium-248 and californium-249 were investigated by absorption spectroscopy, cyclic voltammetry, and bulk solution electrolysis in concentrated aqueous carbonate-bicarbonate solution. Actinide concentrations between 10 -4 and 10 -2 M were studied in 2 M sodium carbonate and 5.5 M potassium carbonate solutions at pH values from 8 to 14. The solution absorption spectra of Cm(III) and Cf(III) in carbonate media are presented for the first time and compared to literature spectra of these species in noncomplexing aqueous solution. It was anticipated that carbonate complexation of the actinide ions could provide a sufficient negative shift in the formal potentials of the M(IV)/M(III) couples of Cm and Cf to permit the generation and stabilization of their tetravalent states in aqueous carbonate-bicarbonate medium. No conclusive evidence was found in the present work to indicate the existence of any higher oxidation states of curium or californium in carbonate solution. Some possible reasons for our inability to generate and detect oxidized species of curium and californium in this medium are discussed

  13. Mechanism of laser ablation for aqueous media irradiated under confined-stress conditions

    International Nuclear Information System (INIS)

    Oraevsky, A.A.; Jacques, S.L.; Tittel, F.K.

    1995-01-01

    Pulsed laser ablation of aqueous medium irradiated under conditions of temporal confinement of thermal stress is described. Time-resolved measurements of laser-induced transient stress waves with simultaneous imaging of ablation process by laser-flash photography were performed. Stress transients induced in aqueous solution of K 2 CrO 4 by ablative nanosecond laser pulses at 355 nm were studied by a broad-band lithium niobate acoustic transducer. Recoil momentum upon material ejection was measured from the temporal profiles of the acoustic transducer signal as a function of incident laser fluence. Cavitation bubbles produced in the irradiated volume during the tensile phase of thermoelastic stress were shown to drive material ejection at temperatures substantially below 100 degree C. Experimental data are evident that nanosecond-pulse laser ablation of aqueous media (when temporal stress-confinement conditions are satisfied) include the following two main stages of material ejection: (1) ejection of water microdroplets due to expansion and rupture of subsurface cavitation bubbles; (2) ejection of liquid streams with substantial volume upon collapse of initial crater and large cavitation bubbles in the depth of irradiated volume (after coalescence of smaller bubbles). copyright 1995 American Institute of Physics

  14. Synthesis and characterization of ferrous phosphate (vivianite) and its behavior in aqueous media

    International Nuclear Information System (INIS)

    Diaz F, J.C.

    2003-01-01

    The synthesis and characterization of materials that can be useful in Environmental Chemistry is very important because their characteristics are exposed and its behavior in chemical phenomena as the sorption in aqueous media is understand to use it in the human being benefit. With the object of using, in a future, the octa hydrated ferrous phosphate (vivianite) as a potential candidate for matrix confinement in contention walls for the storage of radioactive waste of long half life, it was synthesized and it characterized physico chemically and their properties of surface of this compound were evaluated. Presently work was carried out the synthesis and structural characterization of the iron phosphate II by infrared spectroscopy with having Fourier transform, high vacuum scanning electron microscopy, X-ray diffraction, thermal gravimetric analysis, the BET multipoint surface area and Moessbauer spectroscopy; as well as, the determination between aqueous media of the isoelectric point and the density of sites of surface of the compound. The octa hydrated ferrous phosphate was obtained pure. The results indicate that the product corresponds to the prospective mineral, the vivianite. The thermal gravimetric analysis demonstrated that the ferrous phosphate is a stable salt after the lost of water. The isoelectric point is since an important parameter because allows to know the behavior of the surface of the material in aqueous systems, in this case the isoelectric point, of the octa hydrated ferrous phosphate, in distilled water is of pH 4.20 and in solution of potassium nitrate 0.5 M is of pH = 3.75. This indicates that the material has an amphoteric surface depending on the pH. On the other hand, the density of active sites of surface obtained by titrations acid-base is of 20 sites by nm 2 . (Author)

  15. Oxytetracycline recovery from aqueous media using computationally designed molecularly imprinted polymers.

    Science.gov (United States)

    Rodríguez-Dorado, Rosalía; Carro, Antonia M; Chianella, Iva; Karim, Kal; Concheiro, Angel; Lorenzo, Rosa A; Piletsky, Sergey; Alvarez-Lorenzo, Carmen

    2016-09-01

    Polymers for recovery/removal of the antimicrobial agent oxytetracycline (OTC) from aqueous media were developed with use of computational design and molecular imprinting. 2-Hydroxyethyl methacrylate, 2-acrylamide-2-methylpropane sulfonic acid (AMPS), and mixtures of the two were chosen according to their predicted affinity for OTC and evaluated as functional monomers in molecularly imprinted polymers and nonimprinted polymers. Two levels of AMPS were tested. After bulk polymerization, the polymers were crushed into particles (200-1000 μm). Pressurized liquid extraction was implemented for template removal with a low amount of methanol (less than 20 mL in each extraction) and a few extractions (12-18 for each polymer) in a short period (20 min per extraction). Particle size distribution, microporous structure, and capacity to rebind OTC from aqueous media were evaluated. Adsorption isotherms obtained from OTC solutions (30-110 mg L(-1)) revealed that the polymers prepared with AMPS had the highest affinity for OTC. The uptake capacity depended on the ionic strength as follows: purified water > saline solution (0.9 % NaCl) > seawater (3.5 % NaCl). Polymer particles containing AMPS as a functional monomer showed a remarkable ability to clean water contaminated with OTC. The usefulness of the stationary phase developed for molecularly imprinted solid-phase extraction was also demonstrated. Graphical Abstract Selection of functional monomers by molecular modeling renders polymer networks suitable for removal of pollutants from contaminated aqueous environments, under either dynamic or static conditions.

  16. Photophysical and photoprototropic characteristics of phenothiazine in aqueous and β-cyclodextrin media

    Energy Technology Data Exchange (ETDEWEB)

    Rajamohan, Rajaram, E-mail: rajmohanau@gmail.com [Department of Chemistry, S.K.P Institute of Technology, Tiruvannamalai 606611 (India); Nayaki, Sundararajulu Kothai [Chemistry Section, FEAT, Annamalai University, Annamalainagar 608002 (India); Sivakumar, Krishnamoorthy [Department of Chemistry, SCSV University, Enathur, Kanchipuram 631561 (India); Swaminathan, Meenakshisundaram [Department of Chemistry, Annamalai University, Annamalainagar 608002 (India)

    2015-12-15

    The photophysical and photoprototropic characteristics of phenothiazine (PTZ) in aqueous and β-cyclodextrin (β-CD) media have been investigated using absorption, steady state and time resolved fluorescence measurements. The absorbance and fluorescence intensities of the neutral and monocationic forms of PTZ are enhanced by the addition of β-cyclodextrin and it is due to the formation of 1:1 inclusion complex. The formation of complex is confirmed by the decay analysis and Job's continuous variation method in the liquid state while FT-IR spectral study and SEM image analysis in the solid state. The peak and pK{sub a}* values of PTZ in aqueous media are higher than in β-CD medium, which reveals that the >NH group of PTZ lies in the β-CD cavity. - Highlights: • Increase in the absorbance and fluorescence intensity of PTZ by the addition of β-CDx is confirmed the complex formation. • Biexponential decay is noticed for PTZ by the addition of β-CDx is due to the formation of inclusion complex. • FT-IR and SEM images analysis confirms complex between PTZ and β-CDx in solid state. • The pK{sub a} and pK{sub a}* values of PTZ in aqueous medium is higher than in β-CDx medium, which reveals that the >NH group of PTZ lies in the β-CDx cavity. • The orientation of the inclusion complex is proposed by PatchDock server.

  17. A nanofiber functionalized with dithizone by co-electrospinning for lead (II) adsorption from aqueous media

    International Nuclear Information System (INIS)

    Deng, Jianjun; Kang, Xuejun; Chen, Liqin; Wang, Yu; Gu, Zhongze; Lu, Zuhong

    2011-01-01

    Highlights: ► We fabricated a composite electrospun nanofiber as a selective sorbent for lead (II) in PFSPE. ► The composite nanofiber was functionalized with the dithizone by co-electrospinning of the PS solution containing unbonded dithizone. ► The nanofiber was characterized by scanning electron microscope and IR spectra. ► We applied the nanofiber by packing in a cartridge. ► The nanofiber performed well in the absorption of lead (II) and was applied successfully in aqueous samples. - Abstract: An electrospun nanofiber was utilized as a sorbent in packed fiber solid phase extraction (PFSPE) for selective separation and preconcentration of lead (II). The nanofiber had a polystyrene (PS) backbone, which was functionalized with dithizone (DZ) by co-electrospinning of a PS solution containing DZ. The nanofiber exhibited its performance in a cartridge prepared by packing 5 mg of nanofiber. The nanofiber was characterized by a scanning electron microscope and IR spectra. The diameter of the nanofiber was less than 400 nm. After being activated by 2.0 mol L −1 NaOH aqueous solution, the nanofiber quantitatively sorbed lead (II) at pH 8.5, and the metal ion could be desorbed from it by three times of elution with a small volume of 0.1 mol L −1 HNO 3 aqueous solution. The breakthrough capacity was 16 μg mg −1 . The nanofiber could be used for concentration of lead (II) from water and other aqueous media, such as plasma with stable recovery in a simple and convenient manner.

  18. The effect of aqueous media on the mechanical properties of fluorapatite-mullite glass-ceramics.

    Science.gov (United States)

    Mollazadeh, S; Ajalli, Siamak; Kashi, Tahereh S Jafarzadeh; Yekta, Bijan Eftekhai; Javadpour, Jafar; Jafari, S; Youssefi, Abbas; Fazel, Akbar

    2015-11-01

    To verify the effects of alternating thermal changes in aqueous media and chemical composition on mechanical properties of apatite-mullite glass-ceramics and to investigate concentration of ions eluted from glass-ceramics in aqueous media. The glass compositions were from SiO2Al2O3P2O5CaOTiO2BaOZrO2CaF2 system. Glass-ceramics were prepared by heat-treating at 1100°C for 3h samples alternately immersed in water at 5 and 60°C. The 3-point bending strength (n=10) were determined using 3×4×25mm/bar and a universal testing machine, at a cross-head speed of 0.1mm/min. Vickers micro hardness were evaluated by applying a total of 15-20 indentations under a 100g load for 30s. Concentrations of ions eluted from glass-ceramics immersed in 60±5°C double distilled water were determined by ion chromatography. The toxicity of glass-ceramics was assessed by seeding the osteosarcoma cells (MG63) on powder for different days and their cell proliferation assessment was investigated by MTT assay. The data were analyzed using one way analysis of variance and the means were compared by Tukey's test (5% significance level). The highest flexural strength and hardness values after thermal changes belonged to TiO2 and ZrO2 containing glass-ceramics which contained lower amount of released ions. BaO containing glass-ceramic and sample with extra amount of silica showed the highest amount of reduction in their mechanical strength values. These additives enhanced the concentration of eluted ions in aqueous media. MTT results showed that glass-ceramics were almost equivalent concerning their in-vitro biological behavior. Thermal changes and chemical compositions had significant effects on flexural strength and Vickers micro-hardness values. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  19. Radiation-induced changes of liposomes and lecithin in non-aqueous media

    International Nuclear Information System (INIS)

    Nakazawa, T.; Nagatsuka, S.; Sakurai, T.

    1981-01-01

    Radiation-induced changes of lipids in non-aqueous media were studied to elucidate the process of radiation damage in biological membranes. The lipid peroxidation progressed linearly with increasing dose and decreasing dose rate of γ-irradiation in soyabean lecithin in chloroform. The fatty acid composition of lecithin also changed, especially in linoleic and linolenic acids. Lower dose rate radiation enhanced these changes in oxic condition. Lipid peroxidation was also shown in lipids extracted from irradiated liposomes or in liposomes prepared from irradiated lecithin in chloroform. The dose-dependent glucose efflux was seen in liposomes prepared from irradiated lecithin in chloroform. These results indicate that the peroxidation of lipid molecules might cause radiation damage to the membrane conformation. (author)

  20. Formation and reactions of radical cations of substituted benzenes in aqueous media

    International Nuclear Information System (INIS)

    Holcman, J.

    1977-08-01

    Radical cations of anisole, methylated benzenes, ethylbenzene, isopropylbenzene, tert-butylbenzene and N,N-dimethylaniline were studied in aqueous media by pulse radiolytic technique. Absorption spectra and reaction kinetics of the radical cations were recorded. The radical cations are formed from the corresponding OH adducts by the elimination of OH - , either by a simple dissociation or by an acid catalyzed reaction. The rate constants of the formation of the radical cations and their reactions with water, OH - and Fe 2+ , or the reaction of a proton loss, were measured. The rate constants for the reaction with water and OH - , together with the rate constants for the dissociation of the OH adducts, are correlated with the ionization potential of the parent compound. These correlations offer a possibility of predicting the acid-base properties of radical cations of substituted benzenes, or the estimation of their ionization potential. (author)

  1. The use of biosorbents for heavy metals removal from aqueous media

    International Nuclear Information System (INIS)

    Al-Masri, M. S.; Amin, Y.

    2010-04-01

    Biomaterials, which could be adsorbed heavy metals, such bacteria, algae, yeasts, fungi and agricultural waste, is called Biomass. Recently, they are widely used for heavy metal removal from aqueous media, due to their large available quantities, low cost and good performance. The biosorbent, unlike mono functional ion exchange resins, contains variety of functional sites including carboxyl, imidazole, sulphydryl, amino, phosphate, sulfate, thioether, phenol, carbonyl, amide and hydroxyl moieties. In this paper, the biosorbents word widely and nationally used for heavy metal removal were reviewed. Their biosorption performance, their pretreatment and modification, aiming to improve their sorption capacity, and regeneration/reuse was introduced and evaluated. The potential application of biosorption and biosorbents was discussed. (author)

  2. Silver nanoparticles embedded polymer sorbent for preconcentration of uranium from bio-aggressive aqueous media

    International Nuclear Information System (INIS)

    Das, Sadananda; Pandey, Ashok K.; Athawale, Anjali A.; Subramanian, M.; Seshagiri, T.K.; Khanna, Pawan K.; Manchanda, Vijay K.

    2011-01-01

    Adsorptive sorbent for bio-aggressive natural aqueous media like seawater was developed by one pot simultaneous synthesis of silver nanoparticles (Ag nps) and poly(ethylene glycol methacrylate phosphate) (PEGMP) by UV-initiator induced photo-polymerization. The photo-polymerization was carried out by irradiating N,N'-dimethylformamide (DMF) solution containing appropriate amounts of the functional monomer (ethylene glycol methacrylate phosphate), UV initiator (α,α'-dimethoxy-α-phenyl acetophenone), and Ag + ions with 365 nm UV light in a multilamps photoreactor. To increase mechanical strength, nano-composite sorbent (Ag-PEGMP) was also reinforced with thermally bonded non-woven poly(propylene) fibrous sheet. Transmission electron microscopy (TEM) of the nano-composite sorbent showed uniform distribution of spherical Ag nanoparticles with particles size ranging from 3 to 6 nm. The maximum amount of Ag 0 that could be anchored in the form of nanoparticles were 5 ± 1 and 10 ± 1 wt.% in self-supported PEGMP and poly(propylene) reinforced PEGMP matrices, respectively. Ag-PEGMP sorbent was found to be stable under ambient conditions for a period of six months. Ag-PEGMP composite sorbent did not exhibit growth at all after incubation with pre-grown Escherichia coli cells, and showed non-adherence of this bacteria to the composite. This indicated that composite sorbent has the bio-resistivity due to bacterial repulsion and bactericidal properties of Ag nanoparticles embedded in the PEGMP. Sorption of U(VI) in PEGMP and Ag-PEGMP nano-composite sorbents from well-stirred seawater was studied to explore the possibility of using it for uranium preconcentration from bio-aggressive aqueous streams. The nano-composite sorbent was used to preconcentrate U(VI) from a process aqueous waste stream.

  3. Electrochemical behavior of meso-substituted iron porphyrins in alkaline aqueous media

    Science.gov (United States)

    Berezina, N. M.; Bazanov, M. I.; Maksimova, A. A.; Semeikin, A. S.

    2017-12-01

    The effect meso-substitution in iron porphyrin complexes has on their redox behavior in alkaline aqueous solutions is studied via cyclic voltammetry. The voltammetric features of the reduction of iron pyridylporphyrins suggest that the sites of electron transfer lie at the ligand, the metal ion, and the pyridyl moieties. The electron transfer reactions between the different forms of these compounds, including the oxygen reduction reaction they mediate, are outlined to show the sequence and potential ranges in which they occur in alkaline aqueous media. Under our experimental conditions, the iron porphyrins exist as μ-oxo dimmers whose activity for the electrocatalytic reduction of oxygen displays a considerable dependence on the nature of the substitutents and nitrogen isomerization (for pyridylporphyrins) and grows in the order (Fe( ms-Ph)4P)2O, (Fe[ ms-(Py-3)Ph3]P)2O, (Fe[ ms-(Py-4)4]P)2O, and (Fe[ ms-(Py-3)4]P)2O.

  4. Electrochemical Oxidation of Silver and Copper in Aqueous Basic Media and in Fused Hydroxide Electrolytes

    Directory of Open Access Journals (Sweden)

    Tejada-Rosales, E. M.

    2004-04-01

    Full Text Available The anodic oxidations of copper and silver electrodes in basic media are reported. Experiments were conducted both in aqueous NaOH solutions and in a flux of molten NaOH/KOH eutectic. The oxidation processes were studied by means of cyclic voltammetry and chronoamperometries and the phases obtained were systematically characterized by x-ray diffraction. The ranges of stability of each phase in the different media studied are reported. In addition to known oxides of copper or silver, a new silver oxide was isolated.

    En este trabajo se describe la oxidación anódico de electrodos de plata y de cobre en medios básicos. Se han utilizado tanto medios acuosos como hidróxidos fundidos (eutéctico NaOH/KOH. Los procesos de oxidación se han estudiado mediante voltametría cíclica y cronoamperometría, y las fases resultantes han sido caracterizadas por difracción de Rayos X. Los rangos de estabilidad encontrados para cada uno dependen del medio utilizado. Además de óxidos conocidos de cobre y de plata, se ha aislado un nuevo óxido de plata.

  5. XAS Investigation of bio-relevant cobalt complexes in aqueous media

    International Nuclear Information System (INIS)

    Bresson, C.; Lamouroux, C.; Esnouf, S.; Solari, P.L.; Den Auwer, C.

    2006-01-01

    Cobalt is an essential element of biological cycles involved in numerous metallo-biomolecules, but it becomes a toxic element at high concentration or a radio-toxic element because of its use in the nuclear industry. 'Molecular speciation' in biological media is an essential prerequisite to evaluate its chemical behaviour as well as its toxic or beneficial effects. In this scheme, we have focused on the coordination properties of the thiol-containing amino acid cysteine (Cys) and the pseudo-peptide N-(2-mercapto-propionyl) glycine (MPG) towards the Co 2+ cation in aqueous media. XAS at the Co K edge and traditional spectroscopic techniques have been coupled in order to structurally characterize the cobalt coordination sphere. Oxidation states and geometries of the bis- and tris-cysteinato Co(III) complexes are in agreement with the literature data. In addition, bond lengths between the metallic centre and the donor atoms have been determined. The structure of a new dimeric N-(2-mercapto-propionyl) glycinato Co(II) complex in solution is also reported. The coordination of MPG to Co(II) through the thiolate and carboxylate functions is ascertained. This work provides fundamental structural information about bio-relevant complexes of cobalt, which will contribute to our understanding of the chemical behaviour and the biological role of this radionuclide. (authors)

  6. Effect of alpha irradiation on UO2 surface reactivity in aqueous media

    International Nuclear Information System (INIS)

    Jegou, C.; Muzeau, B.; Broudic, V.; Poulesquen, A.; Roudil, D.; Jorion, F.; Corbel, C.

    2005-01-01

    The option of direct disposal of spent nuclear fuel in a deep geological formation raises the need to investigate the long-term behavior of the UO 2 matrix in aqueous media subjected to α-β-γ radiation. The β-γ emitters account for most of the activity of spent fuel at the moment it is removed from the reactor, but diminish within a millennial time frame by over three orders of magnitude to less than the long-term activity. The latter persists over much longer time periods and must therefore be taken into account over a geological disposal time scale. Leaching experiments with solution renewal were carried out on UO 2 pellets doped with alpha emitters ( 238 Pu and 239 Pu) to quantify the impact of alpha irradiation on UO 2 matrix alteration. Three batches of doped UO 2 pellets with different alpha flux levels (3.30 x 10 4 , 3.30 x 10 5 , and 3.2 x 10 6 α cm -2 s -1 ) were studied. The results obtained in aerated and deaerated media immediately after sample annealing or interim storage in air provide a better understanding of the UO 2 matrix alteration mechanisms under alpha irradiation. Interim storage in air of UO 2 pellets doped with alpha emitters results in variations of the UO 2 surface reactivity, which depends on the alpha particle flux at the interface and on the interim storage duration. The variation in the surface reactivity and the greater uranium release following interim storage cannot be attributed to the effect of alpha radiolysis in aerated media since the uranium release tends toward the same value after several leaching cycles for the doped UO 2 pellet batches and spent fuel. Oxygen diffusion enhanced by alpha irradiation of the extreme surface layer and/or radiolysis of the air could account for the oxidation of the surface UO 2 to UO 2+x . However, leaching experiments performed in deaerated media after annealing the samples and preleaching the surface suggest that alpha radiolysis does indeed affect the dissolution, which varies with the

  7. Effect of alpha irradiation on UO{sub 2} surface reactivity in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Jegou, C.; Muzeau, B.; Broudic, V.; Poulesquen, A.; Roudil, D. [Commissariat a l' Energie Atomique (CEA), Rhone Valley Research Center, DIEC/SESC/LMPA, Bagnols-sur-Ceze (France); Jorion, F. [Commissariat a l' Energie Atomique (CEA), Rhone Valley Research Center, DRCP/SE2A/LEMA, Bagnols-sur-Ceze (France); Corbel, C. [Commissariat a l' Energie Atomique (CEA), Saclay Research Center, DSM/DRECAM/SCM, Gif sur Yvette (France)

    2005-07-01

    The option of direct disposal of spent nuclear fuel in a deep geological formation raises the need to investigate the long-term behavior of the UO{sub 2} matrix in aqueous media subjected to {alpha}-{beta}-{gamma} radiation. The {beta}-{gamma} emitters account for most of the activity of spent fuel at the moment it is removed from the reactor, but diminish within a millennial time frame by over three orders of magnitude to less than the long-term activity. The latter persists over much longer time periods and must therefore be taken into account over a geological disposal time scale. Leaching experiments with solution renewal were carried out on UO{sub 2} pellets doped with alpha emitters ({sup 238}Pu and {sup 239}Pu) to quantify the impact of alpha irradiation on UO{sub 2} matrix alteration. Three batches of doped UO{sub 2} pellets with different alpha flux levels (3.30 x 10{sup 4}, 3.30 x 10{sup 5}, and 3.2 x 10{sup 6} {alpha} cm{sup -2} s{sup -1}) were studied. The results obtained in aerated and deaerated media immediately after sample annealing or interim storage in air provide a better understanding of the UO{sub 2} matrix alteration mechanisms under alpha irradiation. Interim storage in air of UO{sub 2} pellets doped with alpha emitters results in variations of the UO{sub 2} surface reactivity, which depends on the alpha particle flux at the interface and on the interim storage duration. The variation in the surface reactivity and the greater uranium release following interim storage cannot be attributed to the effect of alpha radiolysis in aerated media since the uranium release tends toward the same value after several leaching cycles for the doped UO{sub 2} pellet batches and spent fuel. Oxygen diffusion enhanced by alpha irradiation of the extreme surface layer and/or radiolysis of the air could account for the oxidation of the surface UO{sub 2} to UO{sub 2+x}. However, leaching experiments performed in deaerated media after annealing the samples and

  8. Synthesis and self-assembling of responsive polysaccharide-based copolymers in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Nivia do N.; Balaban, Rosangela de C. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil); Halila, Sami; Borsali, Redouane, E-mail: borsali@cermav.cnrs.fr, E-mail: halila@cermav.cnrs.fr [Centre de Recherche sur les Macromolecules Vegetales (CERMAV), Grenoble (France)

    2015-07-01

    This work reports the synthesis and the thermoresponsive self-assembly behavior of carboxymethylcellulose-g-JeffamineM2070 and carboxymethylcellulose-g-JeffamineM600 copolymers in aqueous media. They were prepared through the grafting of two different types of amino-terminated poly(ethylene oxide-co-propylene oxide) chains onto the carboxylate groups of carboxymethylcellulose, by using water-soluble carbodiimide derivative and N-hydroxysuccinimide as coupling reagents. The grafting efficiency was confirmed by infrared and the degree of substitution by {sup 1}H NMR integrations. The salt effect on cloud point temperature was evaluated into different solvents (Milli-Q water, 0.5M NaCl, synthetic sea water (SSW) and 0.5M K{sub 2}CO{sub 3}) by UV-Vis and dynamic light scattering (DLS) measurements. Both copolymers showed lower cloud point temperature in 0.5M K2CO3 than in 0.5M NaCl and in SSW, which was attributed to the higher ionic strength for K{sub 2}CO{sub 3} combined to the ability of CO{sub 3}{sup 2-} to decrease polymer-water interactions. Copolymers chains displayed higher hydrodynamic radii than CMC precursor at 25 and 60 °C in saline solutions, and self-associations changed as a function of the environment and copolymer composition. (author)

  9. Enhanced defluoridation capacity from aqueous media via hydroxyapatite decorated with carbon nanotube

    Science.gov (United States)

    Tang, Qingzi; Duan, Tongdan; Li, Peng; Zhang, Ping; Wu, Daishe

    2018-04-01

    In this work, the potential of a novel carbon nanotube-doped hydroxyapatite composite (CNT-HAP) for fluoride removal was investigated. The synthesized CNT-HAP composite was systematically characterized by X-ray diffraction(XRD), Fourier Transform infrared spectroscopy(FTIR), scanning electron microscope (SEM) and Brunauer–Emmett–Teller(BET). Batch adsorption experiments were conducted to investigate the defluorination capacity of CNT-HAP. The CNT-HAP composite has a maximum adsorption capacity of 11.05 mg·g-1 for fluoride, and the isothermal adsorption data were fitted by the Freundlich model to calculate the thermodynamic parameters. Thermodynamic analysis implies that the adsorption of fluoride on CNT-HAP is a spontaneous process. Furthermore, the adsorption of fluoride follows pseudo-second-order model. The effects of solution pH, co-existing anions and reaction temperature on defluorination efficiency were examined to optimize the operation conditions for fluoride adsorption. It is found that the optimized pH value for fluoride removal by CNT-HAP composite is 6. In addition, among five common anions studied in this work, the presence of HCO3- and PO43- could considerably affect the fluoride removal by CNT-HPA in aqueous media. Finally, the underlying mechanism for the fluoride removal by CNT-HAP is analysed, and an anion exchange process is proposed.

  10. Removal of Cd (II from Aqueous Media by Adsorption onto Chemically and Thermally Treated Rice Husk

    Directory of Open Access Journals (Sweden)

    María Camila Hoyos-Sánchez

    2017-01-01

    Full Text Available Chemically and thermally treated rice husks were evaluated as a potential decontaminant of toxic Cd (II in aqueous media. Rice husk (RH, a by-product from rice milling, was chemically treated with HCl and NaOH. Then, thermal treatments to 300, 500, and 700°C were applied. The chemical composition and morphological characteristics of RH were evaluated by different techniques. The specific surface area analysis of RH samples by BET nitrogen adsorption method provided specific surface areas ranging from 6 to 14 m2/g. SEM, FTIR, and EDX analyses of RH were carried out to determine the surface morphology, functional groups involved in metal binding mechanism, and C/O and C/Si ratios, respectively. The maximum Cd (II adsorption capacity was 28.27 mg/g at an optimum pH, 6.0. The kinetic studies revealed that adsorption process followed the pseudo-second-order kinetic model.

  11. Optical reading of contaminants in aqueous media based on gold nanoparticles.

    Science.gov (United States)

    Du, Jianjun; Zhu, Bowen; Peng, Xiaojun; Chen, Xiaodong

    2014-09-10

    With increasing trends of global population growth, urbanization, pollution over-exploitation, and climate change, the safe water supply has become a global issue and is threatening our society in terms of sustainable development. Therefore, there is a growing need for a water-monitoring platform with the capability of rapidness, specificity, low-cost, and robustness. This review summarizes the recent developments in the design and application of gold nanoparticles (AuNPs) based optical assays to detect contaminants in aqueous media with a high performance. First, a brief discussion on the correlation between the optical reading strategy and the optical properties of AuNPs is presented. Then, we summarize the principle behind AuNP-based optical assays to detect different contaminants, such as toxic metal ion, anion, and pesticides, according to different optical reading strategies: colorimetry, scattering, and fluorescence. Finally, the comparison of these assays and the outlook of AuNP-based optical detection are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. The study of CO2 absorption intensification using porous media material in aqueous AMP solution

    Directory of Open Access Journals (Sweden)

    Min Xiao

    2018-03-01

    Full Text Available In this work, the performance of CO2 absorption into aqueous 2-amino-2-methyl-propanol (AMP solution was investigated by measuring the amount of CO2 in the liquid phase during CO2 absorption process to identify initial CO2 absorption rate. Then, the porous media material named as MCM41 was introduced into the amine solution to test its influence on CO2 absorption. It was found that MCM41 increased initial CO2 absorption rate and enhanced CO2 absorption process. The physico-chemical properties of MCM41 were characterized in terms of specific surface area, average pore diameter, total pore volume and chemical properties, the amount of acidic sites and the Brϕnsted/Lewis (B/L acid sites ratio. Results showed that MCM41 was a type of Lewis acid catalyst with large specific surface area and pore volume. In addition, the pKa of AMP solution with and without MCM41 was obtained using acid titration technology to help understand the effect brought by MCM41. A mechanism illustrating how MCM41 increases the CO2 absorption rate of the AMP solution was proposed and demonstrated that MCM41 is a potential material for enhancing CO2 absorption.

  13. Spectral behaviour of eosin Y in different solvents and aqueous surfactant media

    Science.gov (United States)

    Chakraborty, Moumita; Panda, Amiya Kumar

    2011-10-01

    Photophysical behaviour of the anionic xanthene dye, eosin Y (EY) was investigated in solvents of different polarities as well as in the presence of aqueous cationic surfactants. From the correlation between ET(30) and Kosower Z values of EY in different solvents, subsequent parameters for EY were determined in the presence of surfactants. A red shift, both in the absorption and emission spectra of EY, was observed with decreasing solvent polarity. Dimerisation of EY was found to be dependent on solvent polarity. Cationic surfactants retarded the process of dimerisation, which were evident from the lower dimerisation constant ( KD) values, compared to that of in pure water. Dye-surfactant interaction constants were determined at different temperatures (298-318 K) and subsequently the thermodynamic parameters, viz., Δ G°, Δ H° and Δ S° were evaluated using the interaction constant values. The fluorescence spectra of EY followed the same trend as in the absorption spectra, although with lesser extents. Stokes shifts were calculated and correlated with the polarity of the medium. Fluorescence of EY was initially quenched by the cationic surfactants in their pre-micellar region, which then followed a red shift with intensity enhancement. Fluorescence quenching was found to be of Stern-Volmer type where the excited state lifetime of EY remained unchanged in different surfactant media. However, the anisotropy value of EY was changed in the post micellar region of surfactants.

  14. Synthesis and self-assembling of responsive polysaccharide-based copolymers in aqueous media

    International Nuclear Information System (INIS)

    Marques, Nivia do N.; Balaban, Rosangela de C.; Halila, Sami; Borsali, Redouane

    2015-01-01

    This work reports the synthesis and the thermoresponsive self-assembly behavior of carboxymethylcellulose-g-JeffamineM2070 and carboxymethylcellulose-g-JeffamineM600 copolymers in aqueous media. They were prepared through the grafting of two different types of amino-terminated poly(ethylene oxide-co-propylene oxide) chains onto the carboxylate groups of carboxymethylcellulose, by using water-soluble carbodiimide derivative and N-hydroxysuccinimide as coupling reagents. The grafting efficiency was confirmed by infrared and the degree of substitution by "1H NMR integrations. The salt effect on cloud point temperature was evaluated into different solvents (Milli-Q water, 0.5M NaCl, synthetic sea water (SSW) and 0.5M K_2CO_3) by UV-Vis and dynamic light scattering (DLS) measurements. Both copolymers showed lower cloud point temperature in 0.5M K2CO3 than in 0.5M NaCl and in SSW, which was attributed to the higher ionic strength for K_2CO_3 combined to the ability of CO_3"2"- to decrease polymer-water interactions. Copolymers chains displayed higher hydrodynamic radii than CMC precursor at 25 and 60 °C in saline solutions, and self-associations changed as a function of the environment and copolymer composition. (author)

  15. Enhanced dispersion of boron nitride nanosheets in aqueous media by using bile acid-based surfactants

    Science.gov (United States)

    Chae, Ari; Park, Soo-Jin; Min, Byunggak; In, Insik

    2018-01-01

    Facile noncovalent surface functionalization of hydroxylated boron nitride nanosheet (BNNS-OH) was attempted through the sonication-assisted exfoliation of h-BN in aqueous media in the presence of bile acid-based surfactants such as sodium cholic acid (SC) or sodium deoxycholic acid (SDC), resulting in SC- or SDC-BNNS-OH dispersion with high up to 2 mg ml-1 and enhanced dispersion stability due to the increased negative zeta potential. While prepared SC-BNNS-OH revealed multi-layered BNNS structures, the large lateral sizes of hundreds nanometers and clear h-BN lattice structures are very promising for the preparation and application of water-processable BNNS-based nanomaterials. It is regarded that noncovalent functionalization of BNNS-OH based on σ-π interaction between with σ-rich bile acid-based amphiphiles and π-rich BNNS is very effective to formulate multi-functional BNNS-based nanomaterials or hybrids that can be utilized in various applications where both the pristine properties of BNNS and the extra functions are simultaneously required.

  16. Synthesis of highly luminescent Mn:ZnSe/ZnS nanocrystals in aqueous media

    International Nuclear Information System (INIS)

    Fang Zheng; Wu Ping; Zhong Xinhua; Yang Yongji

    2010-01-01

    High-quality water-dispersible Mn 2+ -doped ZnSe core/ZnS shell (Mn:ZnSe/ZnS) nanocrystals have been synthesized directly in aqueous media. Overcoating a high bandgap ZnS shell around the Mn:ZnSe cores can bring forward an efficient energy transfer from the ZnSe host nanocrystals to the dopant Mn. The quantum yields of the dopant Mn photoluminescence in the as-prepared water-soluble Mn:ZnSe/ZnS core/shell nanocrystals can be up to 35 ± 5%. The optical features and structure of the obtained Mn:ZnSe/ZnS core/shell nanocrystals have been characterized by UV-vis, PL spectroscopy, TEM, XRD and ICP elementary analysis. The influences of various experimental variables, including the Mn concentration, the Se/Zn molar ratio as well as the kind and amount of capping ligand used in the core production and shell deposition process, on the luminescent properties of the obtained Mn:ZnSe/ZnS nanocrystals have been systematically investigated.

  17. Sintesi, modifica e caratterizzazione di polimeri da fonti rinnovabili

    OpenAIRE

    Cruciani, Letizia

    2013-01-01

    Gli argomenti trattati all’interno di questa tesi di dottorato riguardano la sintesi e la modifica di polimeri ottenuti a partire da fonti rinnovabili. L’acido polilattico (PLA) è stato modificato per ottenere film estensibili per uso alimentare. La scelta del materiale si è basata sull’analisi del suo ciclo di vita e perché è riconosciuto come sicuro per l’utilizzo nel campo alimentare. Le formulazioni testate, a base di PLA, sono state preparate con l’aggiunta di una serie di additivi u...

  18. Corrosion inhibitors for neutral aqueous media based on the products on sugar cane processing. 1.Furfural derivatives as inhibitors

    International Nuclear Information System (INIS)

    Ledovskikh, V.M.; Kamekho Khinnebra, Kh.Kh.

    1993-01-01

    A series of carboxy-, nitrogen- and nitroderivaties of furfural - the main product of sugar cane processing (furancasboxylic acid, 5-nitrofurancarboxylic acid and its salts, furfurine, furfurylamine) was studied as inhibitors of iron and copper, corrosion in aqueous-salt media. Nitrofuroates of sodium and ammonium, which decelerate anode process, intensity cathode one and provide the stable passive state, are considered to be the most effective

  19. Layered Double Hydroxides as Effective Adsorbents for U(VI and Toxic Heavy Metals Removal from Aqueous Media

    Directory of Open Access Journals (Sweden)

    G. N. Pshinko

    2013-01-01

    Full Text Available Capacities of different synthesized Zn,Al-hydrotalcite-like adsorbents, including the initial carbonate [Zn4Al2(OH12]·CO3·8H2O and its forms intercalated with chelating agents (ethylenediaminetetraacetic acid (EDTA, diethylenetriaminepentaacetic acid (DTPA, and hexamethylenediaminetetraacetic acid (HMDTA and heat-treated form Zn4Al2O7, to adsorb uranium(VI and ions of toxic heavy metals have been compared. Metal sorption capacities of hydrotalcite-like adsorbents have been shown to correlate with the stability of their complexes with the mentioned chelating agents in a solution. The synthesized layered double hydroxides (LDHs containing chelating agents in the interlayer space are rather efficient for sorption purification of aqueous media free from U(VI irrespective of its forms of natural abundance (including water-soluble bi- and tricarbonate forms and from heavy metal ions. [Zn4Al2(OH12]·EDTA·nH2O is recommended for practical application as one of the most efficient and inexpensive synthetic adsorbents designed for recovery of both cationic and particularly important anionic forms of U(VI and other heavy metals from aqueous media. Carbonate forms of LDHs turned out to be most efficient for recovery of Cu(II from aqueous media with pH0≥7 owing to precipitation of Cu(II basic carbonates and Cu(II hydroxides. Chromate ions are efficiently adsorbed from water only by calcinated forms of LDHs.

  20. Lipase in biphasic alginate beads as a biocatalyst for esterification of butyric acid and butanol in aqueous media.

    Science.gov (United States)

    Ng, Choong Hey; Yang, Kun-Lin

    2016-01-01

    Esterification of organic acids and alcohols in aqueous media is very inefficient due to thermodynamic constraints. However, fermentation processes used to produce organic acids and alcohols are often conducted in aqueous media. To produce esters in aqueous media, biphasic alginate beads with immobilized lipase are developed for in situ esterification of butanol and butyric acid. The biphasic beads contain a solid matrix of calcium alginate and hexadecane together with 5 mg/mL of lipase as the biocatalyst. Hexadecane in the biphasic beads serves as an organic phase to facilitate the esterification reaction. Under optimized conditions, the beads are able to catalyze the production of 0.16 mmol of butyl butyrate from 0.5 mmol of butyric acid and 1.5 mmol of butanol. In contrast, when monophasic beads (without hexadecane) are used, only trace amount of butyl butyrate is produced. One main application of biphasic beads is in simultaneous fermentation and esterification (SFE) because the organic phase inside the beads is very stable and does not leach out into the culture medium. SFE is successfully conducted with an esterification yield of 6.32% using biphasic beads containing iso-octane even though the solvent is proven toxic to the butanol-producing Clostridium spp. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Selective detection of Cu2 + and Co2 + in aqueous media: Asymmetric chemosensors, crystal structure and spectroscopic studies

    Science.gov (United States)

    Dogaheh, Samira Gholizadeh; Khanmohammadi, Hamid; Carolina Sañudo, E.

    2017-05-01

    Two new azo-azomethine receptors, H2L1 and H2L2, containing hydrazine, naphthalene and different electron withdrawing groups, Cl and NO2, have been designed and synthesized for qualitative and quantitative detection of Cu2 + and Co2 + in aqueous media. The crystal structure of H2L1is reported. The H2L1was used as a chemosensor for selective detection of trace amount of Cu2 + in aqueous media. H2L2 was also applied to naked-eye distinction of Cu2 + and Co2 + from other transition metal ions in aqueous media. Detection limit of Cu2 + is 1.13 μM and 1.26 μM, in water, for H2L1 and H2L2, respectively, which are lower than the World Health Organization (WHO) recommended level. The binuclear Cu2 + and Co2 + complexes of the receptors have been also prepared and characterized using spectroscopic methods and MALDI-TOF mass analysis. Furthermore, the binding stoichiometry between the receptors upon the addition Cu2 + and Co2 + has been investigated using Job's plot. Moreover, the fluorescence emission spectra of the receptors and their metal complexes are also reported.

  2. Organic Reactions in Aqueous Media (by Chao-Jun Li and Tak-Hang Chan)

    Science.gov (United States)

    Rosan, Reviewed Alan M.

    2000-06-01

    This concise book joins the series of Wiley Interscience special topic publications. In seven chapters it selectively reviews the burgeoning literature on organic reactions conducted in water or in aqueous media as a reaction cosolvent, nicely complementing another recent book on the subject by Grieco. Following a short introduction there are six chapters that vary in length from 10 to 50 pages; they cover pericyclic reactions, nucleophilic additions and substitutions, metal-mediated reactions, transition metal-catalyzed reactions, oxidation and reduction reactions, and industrial applications. These chapters, each of which is prefaced with a short provocative quotation, also vary in depth, containing from 11 to more than 180 references. The literature is complete through 1996 and commendably includes citations of original papers by Barbier, Faraday, Frankland, Grignard, Kolbe, Lapworth, and Reformatsky as well as references to selected U.S. and foreign patents and the Russian literature. There is a subject index but no author index. This book is timely and effective. From the title, one might expect a broad discussion of the unique properties of water and water-soluble components (salts, surfactants, etc.) that would be thought to bear on organic reactivity. The first chapter opens by noting that water is the most abundant volatile material in comets and briefly describes those properties that suggest its utility as a solvent or cosolvent, summarizing the potential technical, economic, and environmental advantages. Also described are the remarkable changes in density, conductance, heat capacity, dielectric constant, and ionization constant that accompany the transition to the critical point, but the emphasis here is on the effect of water under non-critical conditions. Discussion of the structure of liquid water and the role of hydrogen bonding in mediating molecular recognition events is abbreviated. In fact, the term "hydrogen bond" is surprisingly absent from

  3. Cr(VI) adsorption on functionalized amorphous and mesoporous silica from aqueous and non-aqueous media

    International Nuclear Information System (INIS)

    Perez-Quintanilla, Damian; Hierro, Isabel del; Fajardo, Mariano; Sierra, Isabel

    2007-01-01

    A mesoporous silica (SBA-15) and amorphous silica (SG) have been chemically modified with 2-mercaptopyridine using the homogeneous route. This synthetic route involved the reaction of 2-mercaptopyridine with 3-chloropropyltriethoxysilane prior to immobilization on the support. The resulting material has been characterized by powder X-ray diffraction, nitrogen gas sorption, FT-IR and MAS NMR spectroscopy, thermogravimetry and elemental analysis. The solid was employed as a Cr(VI) adsorbent from aqueous and non-aqueous solutions at room temperature. The effect of several variables (stirring time, pH, metal concentration and solvent polarity) has been studied using the batch technique. The results indicate that under the optimum conditions, the maximum adsorption value for Cr(VI) was 1.83 ± 0.03 mmol/g for MP-SBA-15, whereas the adsorption capacity of the MP-SG was 0.86 ± 0.02 mmol/g. On the basis of these results, it can be concluded that it is possible to modify chemically SBA-15 and SG with 2-mercaptopyridine and to use the resulting modified silicas as effective adsorbents for Cr(VI)

  4. Modeling reactive geochemical transport of concentrated aqueous solutions in variably saturated media

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Guoxiang; Zheng, Zuoping; Wan, Jiamin

    2004-01-28

    Concentrated aqueous solutions (CAS) have unique thermodynamic and physical properties. Chemical components in CAS are incompletely dissociated, especially those containing divalent or polyvalent ions. The problem is further complicated by the interaction between CAS flow processes and the naturally heterogeneous sediments. As the CAS migrates through the porous media, the composition may be altered subject to fluid-rock interactions. To effectively model reactive transport of CAS, we must take into account ion-interaction. A combination of the Pitzer ion-interaction and the ion-association model would be an appropriate way to deal with multiple-component systems if the Pitzer' parameters and thermodynamic data of dissolved components and the related minerals are available. To quantify the complicated coupling of CAS flow and transport, as well as the involved chemical reactions in natural and engineered systems, we have substantially extended an existing reactive biogeochemical transport code, BIO-CORE{sup 2D}{copyright}, by incorporating a comprehensive Pitzer ion-interaction model. In the present paper, the model, and two test cases against measured data were briefly introduced. Finally we present an application to simulate a laboratory column experiment studying the leakage of the high alkaline waste fluid stored in Hanford (a site of the U.S. Department of Energy, located in Washington State, USA). With the Pitzer ion-interaction ionic activity model, our simulation captures measured pH evolution. The simulation indicates that all the reactions controlling the pH evolution, including cation exchanges, mineral precipitation and dissolution, are coupled.

  5. Control of Electrostatic Interactions Between F-Actin And Genetically Modified Lysozyme in Aqueous Media

    International Nuclear Information System (INIS)

    Sanders, L.K.; Xian, W.; Guaqueta, C.; Strohman, M.; Vrasich, C.R.; Luijten, E.; Wong, G.C.L.

    2009-01-01

    The aim for deterministic control of the interactions between macroions in aqueous media has motivated widespread experimental and theoretical work. Although it has been well established that like-charged macromolecules can aggregate under the influence of oppositely charged condensing agents, the specific conditions for the stability of such aggregates can only be determined empirically. We examine these conditions, which involve an interplay of electrostatic and osmotic effects, by using a well defined model system composed of F-actin, an anionic rod-like polyelectrolyte, and lysozyme, a cationic globular protein with a charge that can be genetically modified. The structure and stability of actin-lysozyme complexes for different lysozyme charge mutants and salt concentrations are examined by using synchrotron x-ray scattering and molecular dynamics simulations. We provide evidence that supports a structural transition from columnar arrangements of F-actin held together by arrays of lysozyme at the threefold interstitial sites of the actin sublattice to marginally stable complexes in which lysozyme resides at twofold bridging sites between actin. The reduced stability arises from strongly reduced partitioning of salt between the complex and the surrounding solution. Changes in the stability of actin-lysozyme complexes are of biomedical interest because their formation has been reported to contribute to the persistence of airway infections in cystic fibrosis by sequestering antimicrobials such as lysozyme. We present x-ray microscopy results that argue for the existence of actin-lysozyme complexes in cystic fibrosis sputum and demonstrate that, for a wide range of salt conditions, charge-reduced lysozyme is not sequestered in ordered complexes while retaining its bacterial killing activity.

  6. LASERS, ACTIVE MEDIA: The aqueous-polyelectrolyte dye solution as an active laser medium

    Science.gov (United States)

    Akimov, A. I.; Saletskii, A. M.

    2000-11-01

    The spectral, luminescent, and lasing properties of aqueous solutions of a cationic dye rhodamine 6G with additions of anion polyelectrolytes — polyacrylic and polymethacrylic acids — are studied. It is found that the energy and spectral properties of lasing of these solutions depend on the ratio of concentrations of polyelectrolyte and molecules. It is also found that the lasing parameters of aqueous-polyelectrolyte dye solutions can be controlled by changing the structure of the molecular system. The variation in the structure of aqueous-polyelectrolyte dye solutions of rhodamine 6G resulted in an almost five-fold increase in the lasing efficiency compared to that in aqueous dye solutions.

  7. Synthesis in aqueous medium and organic praseodymium complexes with ligands derived from Schiff base quinolinic. Characterization and physicochemical study; Sintesis en medio acuoso y organico de complejos de praseodimio con ligantes derivados de base de Schiff quinolicos. Caracterizacion y estudio fisicoquimico

    Energy Technology Data Exchange (ETDEWEB)

    Garcia G, A.

    2015-07-01

    It was investigated the coordination ability of the quinolinic Schiff base organic tetradentate quinolinic ligand (Q Schiff-(OH){sub 2}) towards the trivalent praseodymium by UV/Vis spectrophotometric titration (St). By St, was studied the formed species between the Q Schiff-(OH){sub 2} ligand and the praseodymium nitrate salt in equimolar concentrations (5.86 x 10{sup -4} M: 5.22 x 10{sup -4} M) in methanol. The statistical analysis of the experimental results suggested three complexed species with 1Pr:3L, 1Pr:2L y 1Pr:1L stoichiometries. The predominant stoichiometries were the second and the latter. Based on these results and data from the scientific literature, the methodology for the syntheses of the complexes Q Schiff-(OH){sub 2}-Pr in aqueous-organic and organic media was established and a molar ratio M:L= 1:2 of praseodymium nitrate and the ligand was used. The new complexes were characterized by UV/Vis, Infrared, X-ray Photoelectron Spectroscopy (XP S), Diffuse Reflectance (Dr) and Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA/DSC). Elemental analysis of C, N, O and Pr by XP S suggested 1Pr:2L:1Na (PrC{sub 32}H{sub 20}N{sub 4}O{sub 4}Na) stoichiometry of the complex synthesized by the aqueous-organic medium while for the complex synthesized by the organic medium it was 1Pr:3L (PrC{sub 48}H{sub 33}N{sub 6}O{sub 6}). In the first case, the praseodymium ion charge was neutralized by the anionic ligands whose remaining charge was compensated by the sodium ion. In the second case, the ion charge was neutralized by the ligands. The minimum formula was Pr(Q Schiff){sub 2}Na for the pure coordination compound from the aqueous-organic medium and the minimum formula Pr(Q Schiff){sub 3} for that from the organic medium. XP S also indicated that the oxidation state of praseodymium ion was maintained. Both complexes were stable in methanol, ethanol and acetonitrile at least for 5 days. The photophysical properties of the studied complexes were

  8. PREPARATION AND CHARACTERIZATION OF IRON THIN FILM ELECTRODEPOSED ON A VITREOUS CARBON ELECTRODE IN AQUEOUS AND ORGANIC MEDIA: A COMPARATIVE STUDY

    Directory of Open Access Journals (Sweden)

    A LOUNAS

    2010-06-01

    studied on a vitreous carbon electrode in various aqueous and organic media. The deposit of iron was studied by cyclic voltammetry; the quantity of iron deposited was determined by integration of the cathodic and anodic peaks of Fe (0 and Fe (II of the various media.

  9. Recovery of homogeneous polyoxometallate catalysts from aqueous and organic media by a mesoporous ceramic membrane without loss of catalytic activity.

    Science.gov (United States)

    Roy Chowdhury, Sankhanilay; Witte, Peter T; Blank, Dave H A; Alsters, Paul L; Ten Elshof, Johan E

    2006-04-03

    The recovery of homogeneous polyoxometallate (POM) oxidation catalysts from aqueous and non-aqueous media by a nanofiltration process using mesoporous gamma-alumina membranes is reported. The recovery of Q(12)[WZn(3)(ZnW(9)O(34))(2)] (Q=[MeN(n-C(8)H(17))(3)](+)) from toluene-based media was quantitative within experimental error, while up to 97 % of Na(12)[WZn(3)(ZnW(9)O(34))(2)] could be recovered from water. The toluene-soluble POM catalyst was used repeatedly in the conversion of cyclooctene to cyclooctene oxide and separated from the product mixture after each reaction. The catalytic activity increased steadily with the number of times that the catalyst had been recycled, which was attributed to partial removal of the excess QCl that is known to have a negative influence on the catalytic activity. Differences in the permeability of the membrane for different liquid media can be attributed to viscosity differences and/or capillary condensation effects. The influence of membrane pore radius on permeability and recovery is discussed.

  10. SINTESIS MEMBRAN NATA ALOE VERA-ETILENDIAMIN DAN KARAKTERISASINYA

    Directory of Open Access Journals (Sweden)

    EB Susatyo

    2014-06-01

    Full Text Available Serat yang terkandung di dalam nata Aloe vera adalah selulosa sehingga dapat digunakan dalam sintesis membran. Telah dilakukan penelitian tentang sintesis membran nata Aloe vera-etilendiamin (nata-en menggunakan sistem vakum cair. Proses preparasi membran berlangsung melalui tiga tahap, yaitu preparasi nata Aloe vera, aktivasi menggunakan asam sulfat, dan modifikasi dengan menggunakan etilendiamin. Tujuan penelitian adalah untuk mempelajari teknik dalam sintesis membran nata-en kemudian melakukan karakterisasi untuk mengetahui karakter strukturnya. Hasil penelitian menunjukkan perilaku yang berbeda dalam hal sifat mekanik dan strukturnya. Membran nata murni memiliki sifat mekanik yang kuat, nata teraktivasi cenderung rapuh, sedangkan nata-en bersifat liat. Spektra infra merah dari ketiga tipe membran (nata murni, nata teraktivasi, dan nata-en secara umum tidak mengalami perubahan yang signifikan, hanya terjadi pergeseran panjang gelombang dari masing-masing membran. Berdasarkan spektra infra merah dapat diketahui bahwa masing-masing membran mempunyai gugus hidroksil, tetapi serapannya semakin melebar untuk setiap membran. Gugus alkil dan karboksil juga masih tampak, namun pada membran nata teraktivasi serapannya berkurang, sedangkan pada membran nata-en muncul puncak baru yang menunjukkan adanya gugus amin. Hal ini membuktikan bahwa telah terjadi ikatan antara nata dengan etilendiamin. Fibers contained in nata Aloe vera is cellulose that can be used in the synthesis of membrane. The research has done on the synthesis of nata Aloe vera-ethylenediamine (nata-en membrane by using liquid vacuum system. Membrane preparation process consisted of three stages, they are nata Aloe vera preparation, activation using sulfuric acid, and membrane modification by using ethylenediamine. The purpose of research is to study the technique of nata-en membrane synthesis then to perform the characterization to determine the character of their structure.The results

  11. Contribution to the study of the behavior of tetravalent technetium at tracer amounts in aqueous media

    International Nuclear Information System (INIS)

    Guennec, J.Y.

    The behavior of /sup 99m/Tc was studied first in perchloric media. Reduction of TcO 4 - by BH 4 - at pH 7 in perchloric medium leads to Tc(IV) as a radiocolloid (20 percent) and soluble TcO 2 (50 percent). Acidification of the medium oxidizes the soluble Tc(IV) fraction. Acid solutions containing only the IV species and free of radiocolloids can be studied using back extraction. Tc(IV) is extracted by the organic phases, containing or not containing TTA or HDEHP from solutions of Tc(VII) reduced by BH 4 - at pH 7. These organic phases are then contacted with aqueous phases 5 x 10 -2 to 3 M HClO 4 , and the variation of the distribution coefficient was studied as a function of the chelating agent content and of the pH. In the absence of a chelating agent, the extracted species is TcO 2 . In the presence of chelating agents, the cation TcO(OH) + is extracted in the forms TcO(OH)A and TcO(OH)A 2 H respectively with TTA and HDEHP. Hydrolysis of this cation leads to TcO 2 . Study of the reduction of Tc(VII) in hydrochloric medium is complicated by the oxychlorinated forms of Tc(IV). The hexachlorotechnetate ion, TcCl 6 , exists in HCl 12 M down to 1 M and is very inert. Addition of chloride ions to solutions containing only TcO 2 and TcO(OH) + , when [Cl - ] is less than 1 M, leads to a neutral extractable species, which could be TcOCl 2 . When the Cl - concentration is greater than 1 M, there is formation of a species with one more chlorine atoms; this could be TcOCl 3 . The behavior of technetium during the formation of the complex ''Tc-Iron-Ascorbic Acid'' used in medical scintigraphy was also studied. Ascorbic acid alone or divalent iron alone slightly reduce the pertechnetate. Addition of Fe 2+ (or BH 4 - ) to Tc(VII) and ascorbic acid produces a high percentage of Tc(IV). So it is the ascorbate of iron which reduces the Tc(VII) and the excess ascorbic acid maintains the technetium in its reduced state by formation of a weak complex

  12. Influence of enzymes on the oil extraction processes in aqueous media

    Directory of Open Access Journals (Sweden)

    Ricochon Guillaume

    2010-11-01

    Full Text Available The methods of oil aqueous extraction process (AEP assisted by enzymes are, over the last 50 years, an alternative designed to replace traditional methods of extraction using organic solvents. To extract the oil using an AEP, the use of specific enzymes, able to hydrolyze some or all components of seeds, can significantly increase the yields of extraction. Hydrolyzing the different constituents of cell walls (cellulose, hemicellulose, pectins, proteins, etc., enzymes are able to enhance the liberation of the oil. A number of physico-chemical parameters must also be considered for the better expression of the enzymatic mixture, while maintaining the quality of oils and meals. This article presents the various factors influencing the release of oil in aqueous media and the main results obtained by this process on various substrates.

  13. Mass spectrometric detection of proteins in non-aqueous media : the case of prion proteins in biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Douma, M.D.; Kerr, G.M.; Brown, R.S.; Keller, B.O.; Oleschuk, R.D. [Queen' s Univ., Kingston, ON (Canada). Dept. of Chemistry

    2008-08-15

    This paper presented a filtration method for detecting protein traces in non-aqueous media. The extraction technique used a mixture of acetonitrile, non-ionic detergent and water along with filter disks with embedded C{sub 8}-modified silica particles to capture the proteins from non-aqueous samples. The extraction process was then followed by an elution of the protein from the filter disk and direct mass spectrometric detection and tryptic digestion with peptide mapping and MS/MS fragmentation of protein-specific peptides. The method was used to detect prion proteins in spiked biodiesel samples. A tryptic peptide with the sequence YGQGSPGGNR was used for unambiguous identification. Results of the study showed that the method is suitable for the large-scale testing of protein impurities in tallow-based biodiesel production processes. 33 refs., 6 figs.

  14. Study of the europium behavior in aqueous media; Estudio sobre el comportamiento del europio en medios acuosos

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez R, E.; Jimenez R, M.; Solache R, M.; Martinez M, V. [Instituto Nacional de Investigaciones Nucleares, Departamento de Quimica, A.P. 18-1027, C.P. 11801 Mexico D.F. (Mexico)

    2000-07-01

    Europium as waste can produce a pollution problem in water that is in contact with it, what would has a heavy environmental impacts, because of the possibilities of diffusion of these wastes from their place of confinement or storage until the geo and biosphere. The solution of such problem requires of a lot of knowledge over the behavior of several chemical elements such as europium in aqueous solutions. In this work it was used a low ion force (0.02 M). The data set will allow extrapolate the hydrolytic behavior of europium in too much minors ion force media, such as the ground waters, including in ion force zero.

  15. Solvation thermodynamics of L-cystine, L-tyrosine, and L-leucine in aqueous-electrolyte media

    Science.gov (United States)

    Roy, Sanjay; Guin, Partha Sarathi; Mahali, Kalachand; Dolui, Bijoy Krishna

    2017-12-01

    Solubilities of L-cystine, L-tyrosine, and L-leucine in aqueous NaCl media at 298.15 K have been studied. Indispensable and related solvent parameters such as molar mass, molar volume, etc., were also determined. The results are used to evaluate the standard transfer Gibbs free energy, cavity forming enthalpy of transfer, cavity forming transfer Gibbs free energy and dipole-dipole interaction effects during the course of solvation. Various weak interactions involving solute-solvent or solvent-solvent molecules were characterized in order to find their role on the solvation of these amino acids.

  16. Polystyrene-Core, Silica-Shell Scintillant Nanoparticles for Low-Energy Radionuclide Quantification in Aqueous Media.

    Science.gov (United States)

    Janczak, Colleen M; Calderon, Isen A C; Mokhtari, Zeinab; Aspinwall, Craig A

    2018-02-07

    β-particle emitting radionuclides are useful molecular labels due to their abundance in biomolecules. Detection of β-emission from 3 H, 35 S, and 33 P, important biological isotopes, is challenging due to the low energies (E max ≤ 300 keV) and short penetration depths (≤0.6 mm) in aqueous media. The activity of biologically relevant β-emitters is usually measured in liquid scintillation cocktail (LSC), a mixture of energy-absorbing organic solvents, surfactants, and scintillant fluorophores, which places significant limitations on the ability to acquire time-resolved measurements directly in aqueous biological systems. As an alternative to LSC, we developed polystyrene-core, silica-shell nanoparticle scintillators (referred to as nanoSCINT) for quantification of low-energy β-particle emitting radionuclides directly in aqueous solutions. The polystyrene acts as an absorber for energy from emitted β-particles and can be loaded with a range of hydrophobic scintillant fluorophores, leading to photon emission at visible wavelengths. The silica shell serves as a hydrophilic shield for the polystyrene core, enabling dispersion in aqueous media and providing better compatibility with water-soluble analytes. While polymer and inorganic scintillating microparticles are commercially available, their large size and/or high density complicates effective dispersion throughout the sample volume. In this work, nanoSCINT nanoparticles were prepared and characterized. nanoSCINT responds to 3 H, 35 S, and 33 P directly in aqueous solutions, does not exhibit a change in scintillation response between pH 3.0 and 9.5 or with 100 mM NaCl, and can be recovered and reused for activity measurements in bulk aqueous samples, demonstrating the potential for reduced production of LSC waste and reduced total waste volume during radionuclide quantification. The limits of detection for 1 mg/mL nanoSCINT are 130 nCi/mL for 3 H, 8 nCi/mL for 35 S, and <1 nCi/mL for 33 P.

  17. Physical Removal of Anions from Aqueous Media by Means of a Macrocycle-Containing Polymeric Network

    KAUST Repository

    Ji, Xiaofan; Wu, Ren-Tsung; Long, Lingliang; Guo, Chenxing; Khashab, Niveen M.; Huang, Feihe; Sessler, Jonathan L.

    2018-01-01

    Reported here is a hydrogel-forming polymer network that contains a water-soluble tetracationic macrocycle. Upon immersion of this polymer network in aqueous solutions containing various inorganic and organic salts, changes in the physical

  18. Enhanced Ga2O3-photocatalyzed and photochemical degradation of the Fipronil insecticide by UVC irradiation in mixed aqueous/organic media under an inert atmosphere.

    Science.gov (United States)

    Hidaka, Hisao; Tsukamoto, Tohru; Mitsutsuka, Yoshihiro; Oyama, Toshiyuki; Serpone, Nick

    2015-05-01

    Agrochemicals such as the insecticide Fipronil that bear fluoro groups are generally fat-soluble and nearly insoluble in water, so that their photodegradation in a heterogeneous aqueous gallium oxide dispersion presents some challenges. This article examined the photodegradation of this insecticide by solubilizing it through the addition of organic solvents (EtOH, MeOH, THF, 1,4-dioxane and ethylene glycol) to an aqueous medium and then subjecting the insecticide to 254 nm UVC radiation under photocatalytically inert (Ga2O3/N2) and air-equilibrated (Ga2O3/O2) conditions, as well as photochemically in the absence of Ga2O3 but also under inert and air-equilibrated conditions. Defluorination, dechlorination, desulfonation and denitridation of Fipronil were examined in mixed aqueous/organic media (10, 25 and 50 vol% in organic solvent). After 3 h of UVC irradiation (50 vol% mixed media) defluorination with Ga2O3/N2 was ∼65% greater than in aqueous media, and ca. 80% greater than the direct photolysis of Fipronil under inert (N2) conditions; under air-equilibrated conditions both Ga2O3-photocatalyzed and photochemical defluorination were significantly lower than in aqueous media. Dechlorination of Fipronil was ∼160% (Ga2O3/N2) and 140% (photochemically, N2) greater than in aqueous media; under air-equilibrated conditions, both photocatalyzed and photochemical formation of Cl(-) ions in mixed media fell rather short relative to aqueous media. The photocatalyzed (Ga2O3/N2) and photochemical (N2) conversion of the sulfur group in Fipronil to SO4(2(-)) ions was ca. 20% and 30% greater, respectively, in mixed media, while under air-equilibrated conditions photocatalyzed desulfonation was nearly twofold less than in the aqueous phase; direct photolysis showed little variations in mixed media. Denitridation of the nitrogens in Fipronil occurred mostly through the formation of ammonia (as NH4(+)) under all conditions with negligible quantities of NO3(-); again mixed media

  19. Lewis Acid Pairs for the Activation of Biomass-derived Oxygenates in Aqueous Media

    Energy Technology Data Exchange (ETDEWEB)

    Roman, Yuriy [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2015-09-14

    The objective of this project is to understand the mechanistic aspects behind the cooperative activation of oxygenates by catalytic pairs in aqueous media. Specifically, we will investigate how the reactivity of a solid Lewis acid can be modulated by pairing the active site with other catalytic sites at the molecular level, with the ultimate goal of enhancing activation of targeted functional groups. Although unusual catalytic properties have been attributed to the cooperative effects promoted by such catalytic pairs, virtually no studies exist detailing the use heterogeneous water-tolerant Lewis pairs. A main goal of this work is to devise rational pathways for the synthesis of porous heterogeneous catalysts featuring isolated Lewis pairs that are active in the transformation of biomass-derived oxygenates in the presence of bulk water. Achieving this technical goal will require closely linking advanced synthesis techniques; detailed kinetic and mechanistic investigations; strict thermodynamic arguments; and comprehensive characterization studies of both materials and reaction intermediates. For the last performance period (2014-2015), two technical aims were pursued: 1) C-C coupling using Lewis acid and base pairs in Lewis acidic zeolites. Tin-, zirconium-, and hafnium containing zeolites (e.g., Sn-, Zr-, and Hf-Beta) are versatile solid Lewis acids that selectively activate carbonyl functional groups. In this aim, we demonstrate that these zeolites catalyze the cross-aldol condensation of aromatic aldehydes with acetone under mild reaction conditions with near quantitative yields. NMR studies with isotopically labeled molecules confirm that acid-base pairs in the Si-O-M framework ensemble promote soft enolization through α-proton abstraction. The Lewis acidic zeolites maintain activity in the presence of water and, unlike traditional base catalysts, in acidic solutions. 2) One-pot synthesis of MWW zeolite nanosheets for activation of bulky substrates. Through

  20. Mixed system of ionic liquid and non-ionic surfactants in aqueous media: Surface and thermodynamic properties

    International Nuclear Information System (INIS)

    Bhatt, Darshak; Maheria, Kalpana; Parikh, Jigisha

    2014-01-01

    Highlights: • Interaction of ionic liquid and ethylene oxide based non-ionic surfactants in aqueous media. • Evaluation of various surface properties and thermodynamic parameters. • Micellar growth ensues from exothermic to endothermic with increase in temperature. • Micelle formation is enthalpy driven at low temperature and entropy driven at higher temperature. • The micellization power and adsorption proficiency decreased at high IL concentrations. - Abstract: The mixed system of ionic liquid (IL) tetraethyl ammonium tetrafluoroborate [TEA(BF 4 )] and numerous ethylene oxide based non-ionic surfactants in aqueous media were studied using surface tension, viscosity and dynamic light scattering (DLS) measurements. Various surface properties like critical micelle concentration (cmc), maximum surface excess concentration (Γ max ), minimum surface area per surfactant molecule (A min ), surface tension at the cmc (γ cmc ), adsorption efficiency (pC 20 ), and effectiveness of surface tension reduction (π cmc ) as well as thermodynamic parameters of micellization have been determined. DLS and viscosity measurements revealed that the micellar growth was attributed to the bridged solvophilicity of the POE chain in surfactants at elevated temperatures. In most of the cases, the progression ensues from exothermic to endothermic with increase in temperature of the mixed system. Thermodynamic parameter indicates that the micelle formation process is enthalpy driven at low temperature and entropy driven at higher temperature

  1. New ceramics incorporated with industrial by-products as pore formers for sorption of toxic chromium from aqueous media

    Science.gov (United States)

    Domopoulou, Artemi

    2015-04-01

    The incorporation of secondary resources including various industrial wastes as pore-forming agents into clayey raw material mixtures for the development of tailored porous ceramic microstructures is currently of increasing interest. In the present research, sintered ceramic compacts were developed incorporated with industrial solid by-products as pore formers, and then used as new sorbents for chromium removal from aqueous media. The microstructures obtained were characterized through X-ray diffraction (XRD) analysis as well as scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). Sorption potential of chromium from synthetic solutions on the porous ceramics was studied by static adsorption experiments as a function of the pore-former percentage in the ceramic matrix as well as the initial heavy metal (chromium) concentration, solution pH and temperature. Kinetic studies were conducted and adsorption isotherms of chromium were determined using the Langmuir equation. Preliminary experimental results concerning the adsorption characteristics of chromium on the ceramic materials produced appear encouraging for their possible beneficial use as new sorbents for the removal of toxic chromium from aqueous media. Keywords: sorbents, ceramics, industrial solid by-products, pore-former, chromium. Acknowledgements: This research has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program ARCHIMEDES III: Investing in knowledge society through the European Social Fund.

  2. New thiamine functionalized silica microparticules as a sorbent for the removal of lead, mercury and cadmium ions in aqueous media

    Directory of Open Access Journals (Sweden)

    Deniz Sabahattin

    2017-01-01

    Full Text Available The existence of heavy metal ions in aqueous media is one of the biggest environmental pollution problems and thus the removal of heavy metals is a very important procedure. In this work, a new adsorbent was synthesized by modifying 3-aminopropyl-functionalized silica gel with thiamine (vitamin B1 and characterized. The influence of the uptake conditions, such as pH, contact time, initial feed concentration and foreign metal ions, on the binding capacity of thiamine-functionalized silica gel sorbent (M3APS were investigated. Maximum obtained adsorption capacities for Pb(II, Hg(II and Cd(II were 39.4±0.2, 30.9±0.5 and 9.54±0.4 mg g-1 M3APS, respectively, at pH 5.0. The observed selectivity of M3APS for these metal ions was the following: Pb(II > Hg(II > Cd(II. Adsorption isotherm models were also applied to the adsorption process. As a result, the Langmuir isotherm model gave the best fit for the adsorption of metal ions on M3APS. The Gibbs energy change (ΔG for the adsorption of Pb(II, Hg(II and Cd(II were calculated to predict the nature of adsorption process. Having such satisfactory adsorption results, M3APS is a potential candidate adsorbent for Pb(II and Hg(II removal from aqueous media.

  3. Formation of magnetite (Fe3O4)in aqueous media and properties of the interface magnetite/solution

    International Nuclear Information System (INIS)

    Regazzoni, A.E.

    1984-01-01

    The formation of Fe 3 O 4 particles in aqueous media and the properties of the Fe 3 O 4 /aqueous solution interface are studied. This system is of particular interest in nuclear reactor chemistry, since Fe 3 O 4 was identified as the main component of the corrosion products of nuclear power plants cooled with pressurized water, of the Atucha I and II, and Embalse type. Four methods for the synthesis of Fe 3 O 4 are described: a) controlled oxidation of Fe(OH) 2 in the presence of NaNO 3 at 25 deg C; b) controlled oxidation of Fe(OH) 2 in the presence of NaNO 3 and N 2 H 4 and at 100 deg C; c) alkalinization of a F 2+ and Fe 3+ solutions at 80 deg C; d) simultaneous oxidation and alkalinization of a Fe 2+ . The interfacial properties of Fe 3 O 4 particles suspended in aqueous solutions of indifferent electrolytes are described. These properties are essential for the activity transport associated with the corrosion products. Finally, the adsorption of H 3 BO 3 , Hsub(n)PO 4 sup(n-3) and n Co(II) in the Fe 3 O 4 /solution interface at 30 deg C. It is concluded that the adsorbed species are chemically bonded to surface metal ions. (M.E.L.) [es

  4. Miswak mediated green synthesized palladium nanoparticles as effective catalysts for the Suzuki coupling reactions in aqueous media

    Directory of Open Access Journals (Sweden)

    Mujeeb Khan

    2017-05-01

    Full Text Available Green and eco-friendly synthesis of palladium nanoparticles NPs is carried out under facile and eco-friendly conditions using an aqueous solution of Salvadora persica L. (SP root extract (RE as a bioreductant, which is commonly known as Miswak. The as-synthesized Pd NPs were characterized using various spectroscopic and microscopic techniques, including, UV–Vis spectroscopy, FT-IR spectroscopy, XRD, ICP-MS and TEM. Detailed investigations of the Pd NPs have confirmed that the polyphenolic phytomolecules present in the RE of Miswak not only act as a bioreductant by facilitating the reduction and growth of Pd NPs, but they also functionalize the surface of Pd NPs and stabilized them in various solvents. Furthermore, the catalytic activity of the green synthesized Pd NPs was also tested toward the Suzuki coupling reactions of various aryl halides in aqueous media. The as-prepared Pd NPs exhibited superior catalytic activity and reusability for the Suzuki coupling reaction in aqueous and aerobic conditions. The kinetics of the reaction studied by GC revealed that the conversion of various aryl halides to biphenyl takes place in a short time.

  5. Physical Removal of Anions from Aqueous Media by Means of a Macrocycle-Containing Polymeric Network

    KAUST Repository

    Ji, Xiaofan

    2018-02-13

    Reported here is a hydrogel-forming polymer network that contains a water-soluble tetracationic macrocycle. Upon immersion of this polymer network in aqueous solutions containing various inorganic and organic salts, changes in the physical properties are observed that are consistent with absorption of the constituent anions into the polymer network. This absorption is ascribed to host-guest interactions involving the tetracationic macrocyclic receptor. Removal of the anions may then be achieved by lifting the resulting hydrogels out of the aqueous phase. Treating the anion-containing hydrogels with dilute HCl leads to the protonation-induced release of the bound anions. This allows the hydrogels to be recycled for reuse. The present polymer network thus provides a potentially attractive approach to removing undesired anions from aqueous environments.

  6. Dissolution and Protection of Aluminium Oxide in Corrosive Aqueous Media - An Ellipsometry and Reflectometry Study

    NARCIS (Netherlands)

    Karlsson, P.M.; Postmus, B.R.; Palmqvist, A.E.C.

    2009-01-01

    Dissolution of alumina has been studied from wafers in aqueous solution by means of ellipsometry and reflectometry. It was discovered that the dissolution of aluminium oxide is promoted by ethanol amines like N,N-bis(2-hydroxyethyl)glycine and triethanolamine, and that this dissolution is retarded

  7. Efficient Microwave Assisted Syntheses of 2,5-Diketopiperazines in Aqueous Media

    Directory of Open Access Journals (Sweden)

    María Yolanda Rios

    2009-07-01

    Full Text Available Aqueous in situ one-pot N-Boc-deprotection-cyclization of Nα-Boc-dipeptidyl-tert-butyl and methyl esters under microwave irradiation afforded 2,5-diketopiperazines (DKPs in excellent yields. This protocol is rapid, safe, environmentally friendly, and highly efficient, and showed that the tert-butoxy moiety is also an excellent leaving group for these cyclizations.

  8. Plutonium scrap waste processing based on aqueous nitrate and chloride media

    International Nuclear Information System (INIS)

    Navratil, J.D.

    1985-01-01

    A brief review of plutonium scrap aqueous waste processing technology at Rocky Flats is given. Nitric acid unit operations include dissolution and leaching, anion exchange purification and precipitation. Chloride waste processing consists of cation exchange and carbonate precipitation. Ferrite and carrier precipitation waste treatment processes are also described. 3 figs

  9. A reaction-based fluorescent sensor for detection of cyanide in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shan-Teng; Sie, Yi-Wun [Department of Chemistry, National Changhua University of Education, Changhua 50058, Taiwan (China); Wan, Chin-Feng [School of Applied Chemistry, Chung Shan Medical University, Taichung City 40201, Taiwan (China); Wu, An-Tai, E-mail: antai@cc.ncue.edu.tw [Department of Chemistry, National Changhua University of Education, Changhua 50058, Taiwan (China)

    2016-05-15

    A simple boronic acid derivative was utilized as a reaction-based receptor for CN{sup −} in aqueous solution. The receptor showed a selective and sensitive response to CN{sup −} over other various anions via nucleophilic addition of CN{sup −} to the imine moiety of the boronic-based receptor.

  10. Surface grafting of cellulose nanocrystals with poly(ethylene oxide) in aqueous media.

    Science.gov (United States)

    Kloser, Elisabeth; Gray, Derek G

    2010-08-17

    Aqueous suspensions of poly(ethylene oxide)-grafted nanocrystalline cellulose (PEO-grafted NCC) were prepared in order to achieve steric instead of electrostatic stabilization. A two-step process was employed: in the first step NCC suspensions prepared by sulfuric acid hydrolysis were desulfated with sodium hydroxide, and in the second step the surfaces of the crystals were functionalized with epoxy-terminated poly(ethylene oxide) (PEO epoxide) under alkaline conditions. The PEO-grafted samples were analyzed by conductometric titration, ATR-IR, solid-state NMR, MALDI-TOF MS, SEC MALLS, and AFM. The covalent nature of the linkage was confirmed by weight increase and MALDI-TOF analysis. The PEO-grafted cellulose nanocrystals (CNCs) formed a stable colloidal suspension that remained well dispersed, while the desulfated nanoparticles aggregated and precipitated. Upon concentration of the PEO-grafted aqueous NCC suspension, a chiral nematic phase was observed.

  11. Determination of uranyl nitrate diffusion coefficients in organic and aqueous media using the porous diaphragm method

    International Nuclear Information System (INIS)

    Chierice, G.O.

    1974-01-01

    The diffusion coefficient is one of the parameters necessary for the obtention of the extraction exponential coefficients, that are contained within the H.T.U. (height of transfer unity) calculation expression, when operating with continuous organic phase. The organic phase used was tri-n-butyl-phosphate (TBP) and varsol in the 35% and 65% proportions respectively. After each experiment, the uranium content present in each compartment was spectrophotometrically determined and the quantities contained in the aqueous phases were determined by means of volumetric titration. It was found out that the uranyl ion diffusion coefficient is two and one half times less in organic phase, this just being attributed to the greater interactions of the uranyl ions in organic than in aqueous medium

  12. Synergistic extraction of transition metal cations from aqueous media by two separated organic phases

    International Nuclear Information System (INIS)

    Goldberg, I.

    1991-12-01

    We have therefore initiated novel approaches to the study of the mechanism of the synergistic extraction of metal ions by means of two separated organic phases, which are brought in contact with the same aqueous phase. The present work is concerned with the extraction of transition metals and actinides ions from nitric acid by chelating agents e.g., HTTA thenoyltrifluoroacetone in a diluent - the first organic phase, and by natural donor, e.g., TBP, tri-butyl phosphate in a diluent the second organic phase. The adduct formation was studied by means of spectrochemical and radiochemical methods. In the first approach the aqueous phase was attacked with both organic phases simultanously (the static or parallel extraction). In this method organic phase are separated one from the other. It was shown that even in the absence of mixing, synergism is observed under this experimental conditions. The results indicate, that adduct formation occurs in both organic phases. Nevertheless the enhanchment of extraction in the TBP phase is by far greater than that in the HTTA containing phase. This approach has one disadvatage, viz., the experiments are very time consuming, a typical experiment requiring over 10 days. In order to overcome this difficulty, the following experiments were carried out: the aqueous phase were first shaken with diluent containing an anionic ligand and the phases were allowed to separate. Then the aqueous solution were shaken with diluent containing a netural donor and the phase again were allowed to separate. The concentration of the metal ions in all the phases were determined. The experiments were repeated with an other diluent replacing the first diluent in one or both organic phases. In this way eight sequences of experiments were carried out for each concentration set chosen. The results thus point out that this experimental approach open new possibilities to investigate the mechanism and the kinetics of synergistic extraction processes. (author) the

  13. The use of some local plants for removal of radioactive and trace elements from aqueous media

    International Nuclear Information System (INIS)

    Al-Masri, M. S.; Amin, Y.; Al-Akel, B; Al-Naama, T.

    2008-02-01

    The removal of metal ions from aqueous solutions by biosorption plays an important role in water pollution control. In this study, dried leaves of Barbary, Jew's mallow and poplar, branches of poplar trees and creeping club as biomass for removal of toxic elements (Cd, Pb and U) and some radionuclides ( 133 Ba, 137 Cs and 226 Ra) from aqueous solution have been evaluated. The results show that all studied plants can be effectively used for removing U and Ba from aqueous solutions, while Pb was removed using branches of poplar trees. In addition, Cd was removed using Barbary, Jew's mallow and branches of poplar trees. The adsorption of U and Cd by leaves of Barbary reached 3.3 mg g -1 and 3.5 mg g -1 , respectively. Moreover, the leaves of poplar trees were the best plant for biosorping Pb, its maximum capacity reached a value 1.7 mg g -1 . On the other hand, the maximum capacity for studied radionuclide was less than 10-6 mg g -1 . Further more, the effect of many factors such as, plant pretreatment, solution temperature, pH, plant particles size and contact time, on biosorption process were performed and the best conditions of biosorption were recognized. The studied plants were used for removing 226 Ra and some trace elements from real polluted water. The results show that the method is effective.(author)

  14. DETERMINATION OF KINETICS OF DEGRADATION AND MOBILITY OF DITHIOCARBAMATES FUNGICIDES IN AQUEOUS MEDIA AND IN MOROCCAN SOIL

    Directory of Open Access Journals (Sweden)

    Said El Antri

    2010-07-01

    Full Text Available Contribution analysis of dithiocarbamates pesticides used on tomatoes treatment has been reported. The study is focused on analysis and determination of some dithiocarbamates like, Maneb, Mancozeb, Zineb and Propineb, in order to achieve accurate impact of theses pesticides on water and soil. Analysis method is based on decomposition of dithiocarbamate by heating under acidic attack to give carbon disulfide complexed with copper acetate solution in presence of diethanolamine. Complex formed is dosed spectrophotometrically at 435 nm. Degradation kinetic of dithiocarbamate in aqueous media have been realized and proved that dithiocarbamate are degraded by simple air exposition. In the other hand, pH affects also dithiocarbamate degradation by increasing hydroxyl ions to participate for dithiocarbamate instability. Dithiocarbamate mobility on Moroccan soils samples have been realised and don’t have the same degradation mode.

  15. A facile approach for cupric ion detection in aqueous media using polyethyleneimine/PMMA core-shell fluorescent nanoparticles

    International Nuclear Information System (INIS)

    Chen Jian; Zeng Fang; Wu Shuizhu; Su Junhua; Zhao Jianqing; Tong Zhen

    2009-01-01

    A facile approach was developed to produce a dye-doped core-shell nanoparticle chemosensor for detecting Cu 2+ in aqueous media. The core-shell nanoparticle sensor was prepared by a one-step emulsifier-free polymerization, followed by the doping of the fluorescent dye Nile red (9-diethylamino- 5H-benzo[alpha] phenoxazine-5-one, NR) into the particles. For the nanoparticles, the hydrophilic polyethyleneimine (PEI) chain segments serve as the shell and the hydrophobic polymethyl methacrylate (PMMA) constitutes the core of the nanoparticles. The non-toxic and biocompatible PEI chain segments on the nanoparticle surface exhibit a high affinity for Cu 2+ ions in aqueous media, and the quenching of the NR fluorescence is observed upon binding of Cu 2+ ions. This makes the core-shell nanoparticle system a water-dispersible chemosensor for Cu 2+ ion detection. The quenching of fluorescence arises through intraparticle energy transfer (FRET) from the dye in the hydrophobic PMMA core to the Cu 2+ /PEI complexes on the nanoparticle surface. The energy transfer efficiency for PEI/PMMA particles with different diameters was determined, and it is found that the smaller nanoparticle sample exhibits higher quenching efficiency, and the limit for Cu 2+ detection is 1 μM for a nanoparticle sample with a diameter of ∼30 nm. The response of the fluorescent nanoparticle towards different metal ions was investigated and the nanoparticle chemosensor displays high selectivity and antidisturbance for the Cu 2+ ion among the metal ions examined (Na + , K + , Mg 2+ , Ca 2+ , Zn 2+ , Hg 2+ , Mn 2+ , Fe 2+ , Ni 2+ , Co 2+ and Pb 2+ ). This emulsifier-free, biocompatible and sensitive fluorescent nanoparticle sensor may find applications in cupric ion detection in the biological and environmental areas.

  16. A facile approach for cupric ion detection in aqueous media using polyethyleneimine/PMMA core-shell fluorescent nanoparticles.

    Science.gov (United States)

    Chen, Jian; Zeng, Fang; Wu, Shuizhu; Su, Junhua; Zhao, Jianqing; Tong, Zhen

    2009-09-09

    A facile approach was developed to produce a dye-doped core-shell nanoparticle chemosensor for detecting Cu(2+) in aqueous media. The core-shell nanoparticle sensor was prepared by a one-step emulsifier-free polymerization, followed by the doping of the fluorescent dye Nile red (9-diethylamino- 5H-benzo[alpha] phenoxazine-5-one, NR) into the particles. For the nanoparticles, the hydrophilic polyethyleneimine (PEI) chain segments serve as the shell and the hydrophobic polymethyl methacrylate (PMMA) constitutes the core of the nanoparticles. The non-toxic and biocompatible PEI chain segments on the nanoparticle surface exhibit a high affinity for Cu(2+) ions in aqueous media, and the quenching of the NR fluorescence is observed upon binding of Cu(2+) ions. This makes the core-shell nanoparticle system a water-dispersible chemosensor for Cu(2+) ion detection. The quenching of fluorescence arises through intraparticle energy transfer (FRET) from the dye in the hydrophobic PMMA core to the Cu(2+)/PEI complexes on the nanoparticle surface. The energy transfer efficiency for PEI/PMMA particles with different diameters was determined, and it is found that the smaller nanoparticle sample exhibits higher quenching efficiency, and the limit for Cu(2+) detection is 1 microM for a nanoparticle sample with a diameter of approximately 30 nm. The response of the fluorescent nanoparticle towards different metal ions was investigated and the nanoparticle chemosensor displays high selectivity and antidisturbance for the Cu(2+) ion among the metal ions examined (Na(+), K(+), Mg(2+), Ca(2+), Zn(2+), Hg(2+), Mn(2+), Fe(2+), Ni(2+), Co(2+) and Pb(2+)). This emulsifier-free, biocompatible and sensitive fluorescent nanoparticle sensor may find applications in cupric ion detection in the biological and environmental areas.

  17. A facile approach for cupric ion detection in aqueous media using polyethyleneimine/PMMA core-shell fluorescent nanoparticles

    Science.gov (United States)

    Chen, Jian; Zeng, Fang; Wu, Shuizhu; Su, Junhua; Zhao, Jianqing; Tong, Zhen

    2009-09-01

    A facile approach was developed to produce a dye-doped core-shell nanoparticle chemosensor for detecting Cu2+ in aqueous media. The core-shell nanoparticle sensor was prepared by a one-step emulsifier-free polymerization, followed by the doping of the fluorescent dye Nile red (9-diethylamino- 5H-benzo[alpha] phenoxazine-5-one, NR) into the particles. For the nanoparticles, the hydrophilic polyethyleneimine (PEI) chain segments serve as the shell and the hydrophobic polymethyl methacrylate (PMMA) constitutes the core of the nanoparticles. The non-toxic and biocompatible PEI chain segments on the nanoparticle surface exhibit a high affinity for Cu2+ ions in aqueous media, and the quenching of the NR fluorescence is observed upon binding of Cu2+ ions. This makes the core-shell nanoparticle system a water-dispersible chemosensor for Cu2+ ion detection. The quenching of fluorescence arises through intraparticle energy transfer (FRET) from the dye in the hydrophobic PMMA core to the Cu2+/PEI complexes on the nanoparticle surface. The energy transfer efficiency for PEI/PMMA particles with different diameters was determined, and it is found that the smaller nanoparticle sample exhibits higher quenching efficiency, and the limit for Cu2+ detection is 1 µM for a nanoparticle sample with a diameter of ~30 nm. The response of the fluorescent nanoparticle towards different metal ions was investigated and the nanoparticle chemosensor displays high selectivity and antidisturbance for the Cu2+ ion among the metal ions examined (Na+, K+, Mg2+, Ca2+, Zn2+, Hg2+, Mn2+, Fe2+, Ni2+, Co2+ and Pb2+). This emulsifier-free, biocompatible and sensitive fluorescent nanoparticle sensor may find applications in cupric ion detection in the biological and environmental areas.

  18. A novel double-layer molecularly imprinted polymer film based surface plasmon resonance for determination of testosterone in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Yuan; Jing, Lijing; Ding, Yonghong; Wei, Tianxin, E-mail: txwei@bit.edu.cn

    2015-07-01

    Highlights: • The in-situ photo-grafting polymerization method was used to prepare the polymer film. • The synthesized MIF was layer stucture film. • The MIF exhibited good imprinting effect and highly selectivity. - Abstract: This work aimed to prepare a novel double-layer structure molecularly imprinted polymer film (MIF) on the surface plasmon resonance (SPR) sensor chips for detection of testosterone in aqueous media. The film was synthesized by in-situ UV photo polymerization. Firstly, the modification of gold surface of SPR chip was performed by 1-dodecanethiol. Then double-layer MIF was generated on the 1-dodecanethiol modified gold surface. The non-modified and imprinted surfaces were characterized by atomic force microscopy (AFM), fourier transform infrared (FTIR) spectroscopy and contact angle measurements. Analysis of SPR spectroscopy showed that the imprinted sensing film displayed good selectivity for testosterone compared to other analogues and the non-imprinted polymer film (NIF). Within the concentrations range of 1 × 10{sup −12}–1 × 10{sup −8} mol/L, the coupling angle changes of SPR were linear with the negative logarithm of testosterone concentrations (R{sup 2} = 0.993). Based on a signal/noise ratio of three, the detection limit was estimated to be 10{sup −12} mol/L. Finally, the developed MIF was successfully applied to the seawater detection of testosterone. The results in the experiments suggested that a combination of SPR sensing with MIF was a promising alternative method for detection of testosterone in aqueous media.

  19. A novel double-layer molecularly imprinted polymer film based surface plasmon resonance for determination of testosterone in aqueous media

    International Nuclear Information System (INIS)

    Tan, Yuan; Jing, Lijing; Ding, Yonghong; Wei, Tianxin

    2015-01-01

    Highlights: • The in-situ photo-grafting polymerization method was used to prepare the polymer film. • The synthesized MIF was layer stucture film. • The MIF exhibited good imprinting effect and highly selectivity. - Abstract: This work aimed to prepare a novel double-layer structure molecularly imprinted polymer film (MIF) on the surface plasmon resonance (SPR) sensor chips for detection of testosterone in aqueous media. The film was synthesized by in-situ UV photo polymerization. Firstly, the modification of gold surface of SPR chip was performed by 1-dodecanethiol. Then double-layer MIF was generated on the 1-dodecanethiol modified gold surface. The non-modified and imprinted surfaces were characterized by atomic force microscopy (AFM), fourier transform infrared (FTIR) spectroscopy and contact angle measurements. Analysis of SPR spectroscopy showed that the imprinted sensing film displayed good selectivity for testosterone compared to other analogues and the non-imprinted polymer film (NIF). Within the concentrations range of 1 × 10 −12 –1 × 10 −8 mol/L, the coupling angle changes of SPR were linear with the negative logarithm of testosterone concentrations (R 2 = 0.993). Based on a signal/noise ratio of three, the detection limit was estimated to be 10 −12 mol/L. Finally, the developed MIF was successfully applied to the seawater detection of testosterone. The results in the experiments suggested that a combination of SPR sensing with MIF was a promising alternative method for detection of testosterone in aqueous media

  20. Influence of additives on thermoresponsive polymers in aqueous media: a case study of poly(N-isopropylacrylamide).

    Science.gov (United States)

    Umapathi, Reddicherla; Reddy, P Madhusudhana; Rani, Anjeeta; Venkatesu, Pannuru

    2018-04-18

    Thermoresponsive polymers (TRPs) in different solvent media have been studied over a long period and are important from both scientific and technical points of view. Despite numerous studies on the behavior of TRPs with various additives, the interactions of additives with TRPs are still poorly understood. Moreover, despite the vast available literature regarding the biomolecular interactions between various TRPs and naturally occurring additives, it is not possible to provide a unifying declaration about the behavior of different additives, in particular at the phase transition temperature of the polymer. However, potential reviews that describe the behavior of additives as stimuli upon the phase transition of TRPs are also absent. A lack of sufficient knowledge regarding the responses of TRPs to additives as stimuli has hindered the expansion of the wide spectrum of applications of these polymers. Therefore, it was proposed to review the responses of TRPs in the presence of various additives in aqueous media. In-depth knowledge acquired via a literature survey has drawn our attention towards filling this gap by analyzing the interactions of TRPs with different additives. In this perspective, we have systematically examined the stability, aggregation, and phase transition behaviours of various polymers in the presence of different additives. The perspective on the influence of additives as stimuli on the behavior of TRPs in an aqueous medium will provide new reliable information about intramolecular interactions between interior polymer segments as well as intermolecular interactions between TRPs and additive molecules, which will be helpful for industrialists in the preparation of new polymeric materials for drug-delivery systems.

  1. Metal-Catalyzed Intra- and Intermolecular Addition of Carboxylic Acids to Alkynes in Aqueous Media: A Review

    Directory of Open Access Journals (Sweden)

    Javier Francos

    2017-11-01

    Full Text Available The metal-catalyzed addition of carboxylic acids to alkynes is a very effective tool for the synthesis of carboxylate-functionalized olefinic compounds in an atom-economical manner. Thus, a large variety of synthetically useful lactones and enol-esters can be accessed through the intra- or intermolecular versions of this process. In order to reduce the environmental impact of these reactions, considerable efforts have been devoted in recent years to the development of catalytic systems able to operate in aqueous media, which represent a real challenge taking into account the tendency of alkynes to undergo hydration in the presence of transition metals. Despite this, different Pd, Pt, Au, Cu and Ru catalysts capable of promoting the intra- and intermolecular addition of carboxylic acids to alkynes in a selective manner in aqueous environments have appeared in the literature. In this review article, an overview of this chemistry is provided. The synthesis of β-oxo esters by catalytic addition of carboxylic acids to terminal propargylic alcohols in water is also discussed.

  2. Graphene oxide/MnO{sub 2} nanocomposite as destructive adsorbent of nerve-agent simulants in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Šťastný, Martin, E-mail: stastny@iic.cas.cz [Materials Chemistry Department, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Husinec-Řež (Czech Republic); Faculty of the Environment, J.E. Purkyně University in Ústí nad Labem, Králova Výšina 7, 400 96 Ústí nad Labem (Czech Republic); Tolasz, Jakub; Štengl, Václav; Henych, Jiří [Materials Chemistry Department, Institute of Inorganic Chemistry AS CR v.v.i., 25068 Husinec-Řež (Czech Republic); Žižka, David [Faculty of the Environment, J.E. Purkyně University in Ústí nad Labem, Králova Výšina 7, 400 96 Ústí nad Labem (Czech Republic)

    2017-08-01

    Highlights: • Nanocomposite graphene oxide-birnessite-type MnO{sub 2} was synthesized by thermal hydrolysis. • New destructive sorbent for safe degradation of nerve-agent simulants. • 95% degradation activity for DMMP and TEP. - Abstract: Graphene oxide/MnO{sub 2} nanocomposite was prepared by thermal hydrolysis of potassium permanganate (KMnO{sub 4}) and 2-chloroacetamide aqueous solutions with graphene oxide (GO) suspension. The synthesized samples were characterized by specific surface area (BET) and porosity determination (BJH), X-ray Diffraction (XRD) and high-resolution electron microscopes (HRSEM, HRTEM). These nanocomposites were used in an experimental evaluation of their adsorption activity with nerve agent simulants dimethyl methyl phosphonate (DMMP) and triethyl phosphate (TEP) in aqueous media. The nanocomposites exhibited enhanced adsorptive degradation ability compared to pure manganese oxide (MnO{sub 2}) and GO. The GO amount in the nanocomposites affected their degradation activity substantially. The best adsorption efficiency was observed for samples with moderate GO amount. Three methods were used to observe the mechanism of the nerve-agent simulants deactivation: Gas chromatography with mass spectrometry (GC–MS), High-Performance Liquid Chromatography (HPLC) and in situ Infrared spectroscopy (FTIR). It was shown that the hydrolysis on the surface of prepared nanocomposites yields volatile primary alcohols (methanol and ethanol) as the main hydrolysis products.

  3. Functional polyaniline/multiwalled carbon nanotube composite as an efficient adsorbent material for removing pharmaceuticals from aqueous media.

    Science.gov (United States)

    Dutra, Flávia Viana Avelar; Pires, Bruna Carneiro; Nascimento, Tienne Aparecida; Borges, Keyller Bastos

    2018-09-01

    The composite polyaniline/multiwalled carbon nanotube (PAni/MWCNT, 1:0.1 w/w) was developed with the intention of binding the adsorbent properties of two materials and using it to adsorb pharmaceuticals from aqueous media. PAni/MWCNT was characterized by scanning electron microscopy, thermogravimetry, infrared spectroscopy, pH at the point of zero charge, and the effect on the surface wettability of the material. As proof of concept, adsorption studies were carried out using meloxicam (MLX) as the pharmaceutical and it was evaluated as a function of pH, temperature, ionic strength, contact time and variation in concentration. Kinetics and isothermal models were applied to evaluate the mechanism of the adsorption process. The best MLX adsorption result was at pH 2 with 6 min of contact with PAni/MWCNT. The kinetics models that fitted the experimental data were pseudo-second order and Elovich and the kinetics model was the dual-site Langmuir-Freundlich. Both models suggest that the adsorption occurs by the chemical nature of the surface and in the pores of the energetically heterogeneous composite. The PAni/MWCNT presented an adsorption capacity of 221.2 mg g -1 , a very good value when compared with the literature and can be used to remove pharmaceuticals from aqueous environments. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. DEVELOPMENT OF PROTOTYPE TITANATE ION EXCHANGE LOADED MEMBRANES FOR STRONTIUM, CESIUM AND ACTINIDE DECONTAMINATION FROM AQUEOUS MEDIA

    Energy Technology Data Exchange (ETDEWEB)

    Oji, L; Keisha Martin, K; David Hobbs, D

    2008-05-30

    We have successfully incorporated high surface area particles of titanate ion exchange materials (monosodium titanate and crystalline silicotitanate) with acceptable particle size distribution into porous and inert support membrane fibrils consisting of polytetrafluoroethylene (Teflon{reg_sign}), polyethylene and cellulose materials. The resulting membrane sheets, under laboratory conditions, were used to evaluate the removal of surrogate radioactive materials for cesium-137 and strontium-90 from high caustic nuclear waste simulants. These membrane supports met the nominal requirement for nonchemical interaction with the embedded ion exchange materials and were porous enough to allow sufficient liquid flow. Some of this 47-mm size stamped out prototype titanium impregnated ion exchange membrane discs was found to remove more than 96% of dissolved cesium-133 and strontium-88 from a caustic nuclear waste salt simulants. Since in traditional ion exchange based column technology monosodium titanate (MST) is known to have great affinity for the sorbing of other actinides like plutonium, neptunium and even uranium, we expect that the MST-based membranes developed here, although not directly evaluated for uptake of these three actinides because of costs associated with working with actinides which do not have 'true' experimental surrogates, would also show significant affinity for these actinides in aqueous media. It was also observed that crystalline silicotitanate impregnated polytetrafluoroethylene or polyethylene membranes became less selective and sorbed both cesium and strontium from the caustic aqueous salt simulants.

  5. Removal of beta-blockers from aqueous media by adsorption onto graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Kyzas, George Z. [Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Koltsakidou, Anastasia [Laboratory of Environmental Pollution Control, Department of Chemistry, Aristotle University of Thessaloniki, GR–541 24 Thessaloniki (Greece); Nanaki, Stavroula G.; Bikiaris, Dimitrios N. [Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Lambropoulou, Dimitra A., E-mail: dlambro@chem.auth.gr [Laboratory of Environmental Pollution Control, Department of Chemistry, Aristotle University of Thessaloniki, GR–541 24 Thessaloniki (Greece)

    2015-12-15

    The aim of the present study is the evaluation of graphene oxide (GhO) as adsorbent material for the removal of beta-blockers (pharmaceutical compounds) in aqueous solutions. The composition and morphology of prepared materials were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Atenolol (ATL) and propranolol (PRO) were used as model drug molecules and their behavior were investigated in terms of GhO dosage, contact time, temperature and pH. Adsorption mechanisms were proposed and the pH-effect curves after adsorption were discussed. The kinetic behavior of GhO-drugs system was analyzed after fitting to pseudo-first and -second order equations. The adsorption equilibrium data were fitted to Langmuir, Freundlich and Langmuir–Freundlich model calculating the maximum adsorption capacity (67 and 116 mg/g for PRO and ATL (25 °C), respectively). The temperature effect on adsorption was tested carrying out the equilibrium adsorption experiments at three different temperatures (25, 45, 65 °C). Then, the thermodynamic parameters of enthalpy, free energy and entropy were calculated. Finally, the desorption of drugs from GhO was evaluated by using both aqueous eluants (pH 2–10) and organic solvents. - Highlights: • Removal of beta-blockers by graphene oxide (GhO) from aqueous samples • Detailed adsorbent characterization and adsorption studies • Kinetic studies are performed and adsorption isotherms are determined and modeled. • GhO was proved to be an effective adsorbent for removal of atenolol and propranolol.

  6. Scripting Fonetico nuove risorse per leggere il greco antico mediante la sintesi vocale

    Directory of Open Access Journals (Sweden)

    Silvia Gianferrari

    2011-04-01

    Full Text Available Lo scripting fonetico da lingua italiana produce finalmente una sintesi vocale del greco antico senz’altro soddisfacente per gli usi didattici della Scuola secondaria, per l’accesso alle banche dati che raccolgono l’intero patrimonio letterario della lingua antica e per l’editoria digitale costruita secondo i parametri dell’accessibilità.

  7. Disposal of heavy metal cations in aqueous media by adsorption on coal to Ghazni

    Directory of Open Access Journals (Sweden)

    О.М. Заславський

    2008-03-01

    Full Text Available  Adsorption of Pb and Cu cations and their mixture on the surface of modified and non-modified anti-gas coal trough different time intervals have been studied. The maximum adsorption capacity of coal relative to each cations have been determined. Absence  of concurrence between cations of Pb and Cu during adsorption from mixture is explained by difference of  types of their interaction with coal surface. The high effectiveness and perspectivities of application of anti-gas coal for neutralization of heavy metal cations in aqueous solution was shown.

  8. The Homocoupling Reaction of Aromatic Terminal Alkynes by a Highly Active Palladium(II)/AgNO₃ Cocatalyst in Aqueous Media Under Aerobic Conditions.

    Science.gov (United States)

    Guo, Mengping; Chen, Bo; Lv, Meiyun; Zhou, Xiuling; Wen, Yongju; Shen, Xiuli

    2016-05-10

    A new and efficient Pd(II)/AgNO₃-cocatalyzed homocoupling of aromatic terminal alkynes is described. Various symmetrical 1,4-disubstituted-1,3-diynes are obtained in good to excellent yields. This protocol employs a loading with relatively low palladium(II) in aqueous media under aerobic conditions.

  9. Hydrolysis of Methylal Catalyzed by Ion Exchange Resins in Aqueous Media

    Science.gov (United States)

    He, Gaoyin; Dai, Fangfang; Shi, Midong; Li, Qingsong; Yu, Yingmin

    2018-05-01

    In the present work, the chemical equilibrium and kinetics of methylal (PODE1) hydrolysis catalyzed by ion-exchange resin in aqueous solutions were investigated. The study covers temperatures between 333.15 and 363.15 K at various starting compositions covering (PODE1 + MeOH)/water molar ratio ranges from 0.5 to 1.5 in a time scale. On the basis of the experimental results, a mole fraction-based model of the chemical equilibrium and a pseudohomogeneous model are proposed to fit data based on true amount of monomeric formaldehyde. It has been demonstrated that the hydrolysis of PODE1 is slightly endothermic with the enthalpy 8.19 kJ/mol and the rate determining step. Finally, a feed-forward artificial neural networks (ANN) model is developed to model the concentration change of methanol in aqueous solutions. The results showed that the predicted data from designed ANN model were in good agreement with the experimental data with the coefficient ( R 2) of 0.98. Designed ANN provides a reliable method for modeling the hydrolysis reaction of methylal (PODE1).

  10. Determination of micelle formation of ketorolac tromethamine in aqueous media by acoustic measurements

    International Nuclear Information System (INIS)

    Savaroglu, Gokhan; Genc, Lütfi

    2013-01-01

    Graphical abstract: Value of critical micelle concentration (CMC) were detected by speed of sound and determined by an analytical method based on the Phillips definition of the CMC. Highlights: ► The aim of this study was to investigate the aggregation behaviour of KT. ► Influence of KT concentration and temperature upon volumetric properties was studied. ► CMC of KT aqueous solution was determined by using speeds of sound measurements. - Abstract: Density and speed of sound of ketorolac tromethamine in aqueous solutions have been measured as a function of concentration at atmospheric pressure and in the temperature range from 293.15 to 313.15 K. Apparent molar volumes, apparent isentropic compressibility and isentropic compressibility values have also been calculated from the experimental density and speed of sound data. Partial molar volume and partial molar isentropic compressibility are obtained from fitting procedures the data on apparent molar volume, V φ , and apparent isentropic compressibility, K φ(S) . Partial molar volume, V φ 0 , and partial molar isentropic compressibility, k φ(S) 0 , are informative thermodynamic characteristics that reflect solute hydration. The critical micelle concentration (CMC) was determined from speed of sound data by an analytical method based on the Phillips definition of the CMC. Using these results, it was possible to establish the solvent–drug interactions.

  11. Removal of mercury(II) from aqueous media using eucalyptus bark: Kinetic and equilibrium studies

    International Nuclear Information System (INIS)

    Ghodbane, Ilhem; Hamdaoui, Oualid

    2008-01-01

    In this study, eucalyptus camaldulensis bark, a forest solid waste, is proposed as a novel material for the removal of mercury(II) from aqueous phase. The operating variables studied were sorbent dosage, ionic strength, stirring speed, temperature, solution pH, contact time, and initial metal concentration. Sorption experiments indicated that the sorption capacity was dependent on operating variables and the process was strongly pH-dependent. Kinetic measurements showed that the process was uniform and rapid. In order to investigate the mechanism of sorption, kinetic data were modeled using the pseudo-first-order and pseudo-second-order kinetic equations, and intraparticle diffusion model. Among the kinetic models studied, the pseudo-second-order equation was the best applicable model to describe the sorption process. Equilibrium isotherm data were analyzed using the Langmuir and the Freundlich isotherms. The Langmuir model yields a much better fit than the Freundlich model. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy, and entropy of sorption. The maximum sorption capacity was 33.11 mg g -1 at 20 deg. C and the negative value of free energy change indicated the spontaneous nature of sorption. These results demonstrate that eucalyptus bark is very effective in the removal of Hg(II) from aqueous solutions

  12. Removal of nitrate, ammonia and phosphate from aqueous solutions in packed bed filter using biochar augmented sand media

    Directory of Open Access Journals (Sweden)

    El Hanandeh Ali

    2017-01-01

    Full Text Available Nutrients from wastewater are a major source of pollution because they can cause significant impact on the ecosystem. Accordingly, it is important that the nutrient concentrations are kept to admissible levels to the receiving environment. Often regulatory limits are set on the maximum allowable concentrations in the effluent. Therefore, wastewater must be treated to meet safe levels of discharge. In this study, laboratory investigation of the efficiency of packed bed filters to remove nitrate, ammonium and phosphate from aqueous solutions were conducted. Sand and sand augmented with hydrochloric acid treated biochar (SBC were used as packing media. Synthetic wastewater solution was prepared with PO43−, NO3−, NH4+ concentrations 20, 10, 50 mg/L, respectively. Each experiment ran for a period of five days; samples from the effluent were collected on alternate days. All experiments were duplicated. Over the experiment period, the average removal efficiency of PO43−, NO3−, NH4+ were 99.2%, 72.9%, 96.7% in the sand packed columns and 99.2%, 82.3%, 97.4% in the SBC packed columns, respectively. Although, the presence of biochar in the packing media had little effect on phosphate and ammonium removal, it significantly improved nitrate removal.

  13. Polarographic studies about indium (III) behaviour in aqueous media of sodium azide

    International Nuclear Information System (INIS)

    Tokoro, R.

    1988-01-01

    The present study shows some polarographic behavior of indium (III) in azide media that is close those observed in a thiocyanate solution. The presence of azide ligand decreases the overpotential in the discharge of indium whose catalytic character can be explained by formation of an azide bridge between electrode and indium (III) increasing the speed of electron transfer. The discharge of indium in azide media is diffusion controlled. As the azide concentration is increased the half wave potential displaces in the cathodic direction. This displacement is due to complex formation. The number of electrons, n, involved in the total process was estimates by the reversible polarographic equation to be 2,7. The potentiostatic coulometry of indium in azide/hydrazoic acid buffer showed a catalytic process where the chemistry regeneration was performed by reaction of hydrazoic acid and indium amalgam. The electrochemistry evidence was the constancy of current as the electrolysis proceeded. The chemistry aspect was the presence of ammonium cation in electrolysed solution. The catalytic process with chemistry regeneration and the formation of a bridge by azide could explain the higher value of current in azide media compared to perchlorate solution. (author) [pt

  14. Silica coating of luminescent quantum dots prepared in aqueous media for cellular labeling

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yunfei; Li, Yan, E-mail: yli@ecust.edu.cn; Zhong, Xinhua, E-mail: zhongxh@ecust.edu.cn

    2014-12-15

    Graphical abstract: A facile route based on modified Stöber method was used for the synthesis of silica coated QDs (QD@SiO{sub 2}) starting from aqueously prepared CdTe/CdS QDs. The resultant QD@SiO{sub 2} exhibited a significant increase in emission efficiency compared with that of the initial QDs, along with a small size (∼5 nm in diameter), great stability and low cytotoxicity, which makes it a good candidate as robust biomarker. - Highlights: • We present a facile modified Stöber method to prepare highly luminescent QD@SiO{sub 2}. • The PL efficiency of QDs increases significantly after silica coating. • QD@SiO{sub 2} exhibits small size (∼5 nm) and great dispersibility in aqueous solution. • QD@SiO{sub 2} presents extraordinary photo and colloidal stability. • The silica shell eliminates QD cytotoxicity, providing the access of bioconjugation. - Abstract: Silica coating is an effective approach for rendering luminescent quantum dots (QDs) with water dispersibility and biocompatibility. However, it is still challenging to prepare silica-coated QDs (QD@SiO{sub 2}) with high emission efficiency, small size and great stability in favor for bioapplication. Herein, we reported a modified Stöber method for silica coating of aqueously-prepared CdTe/CdS QDs. With the coexistence of Cd{sup 2+} and thioglycolic acid (TGA), a thin silica shell was formed around QDs by the hydrolysis of tetraethyl orthosilicate (TEOS). The resultant QD@SiO{sub 2} with a small size (∼5 nm in diameter) exhibits significantly higher emission efficiencies than that of the initial QDs. Also, QD@SiO{sub 2} has extraordinary photo and colloidal stability (pH range of 5–13, 4.0 M NaCl solution). Protected by the silica shell, the cytotoxicity of QDs could be reduced. Moreover, the QD@SiO{sub 2} conjugated with folic acid (FA) presents high specific binding toward receptor-positive HeLa cells over receptor-negative A549 cells.

  15. A sigmoidal model for biosorption of heavy metal cations from aqueous media.

    Science.gov (United States)

    Özen, Rümeysa; Sayar, Nihat Alpagu; Durmaz-Sam, Selcen; Sayar, Ahmet Alp

    2015-07-01

    A novel multi-input single output (MISO) black-box sigmoid model is developed to simulate the biosorption of heavy metal cations by the fission yeast from aqueous medium. Validation and verification of the model is done through statistical chi-squared hypothesis tests and the model is evaluated by uncertainty and sensitivity analyses. The simulated results are in agreement with the data of the studied system in which Schizosaccharomyces pombe biosorbs Ni(II) cations at various process conditions. Experimental data is obtained originally for this work using dead cells of an adapted variant of S. Pombe and represented by Freundlich isotherms. A process optimization scheme is proposed using the present model to build a novel application of a cost-merit objective function which would be useful to predict optimal operation conditions. Copyright © 2015. Published by Elsevier Inc.

  16. Monolayer and multilayer adsorption isotherm models for sorption from aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Saadi, Reyhaneh; Saadi, Zahra; Fazaeli, Reza; Fard, Narges Elmi [Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2015-05-15

    Industrial wastewater polluted with various contaminants, including heavy metals, dyes, etc., endangers human health and the environment. Various separation techniques have been developed for the removal of pollutants from aqueous solutions. Adsorption process has drawn considerable attention due to its simplicity of design, high removal efficiency, even at dilute concentration, and economical aspect. We reviewed the most common two, three, four, and five parameter adsorption isotherm models corresponding to monolayer and multilayer adsorption on the basis of parameters that can be used for exploring novel adsorbents. Thermodynamic assumptions of the models give information about the surface properties, capacity of the adsorbent and adsorption mechanism. Seven error functions were investigated to evaluate the fitness quality of isotherm models with the experimental equilibrium data.

  17. Nanoscopic surfactant behavior of the porin MspA in aqueous media

    Directory of Open Access Journals (Sweden)

    Ayomi S. Perera

    2013-04-01

    Full Text Available The mycobacterial porin MspA is one of the most stable channel proteins known to date. MspA forms vesicles at low concentrations in aqueous buffers. Evidence from dynamic light scattering, transmission electron microscopy and zeta-potential measurements by electrophoretic light scattering indicate that MspA behaves like a nanoscale surfactant. The extreme thermostability of MspA allows these investigations to be carried out at temperatures as high as 343 K, at which most other proteins would quickly denature. The principles of vesicle formation of MspA as a function of temperature and the underlying thermodynamic factors are discussed here. The results obtained provide crucial evidence in support of the hypothesis that, during vesicle formation, nanoscopic surfactant molecules, such as MspA, deviate from the principles underlined in classical surface chemistry.

  18. Removal of Parathion from Aqueous Media Through p-tert-Butylcalix[4]arene Based Modified Silica

    Directory of Open Access Journals (Sweden)

    Sibghatullah Memon

    2013-12-01

    Full Text Available This study explores, adsorption efficiency of p-tert-butylcalix[4]arene based modified silica to remove parathion from aqueous environment. The adsorption parameters, i.e. pH, concentration of pesticide solution, contact time and adsorbent dosage were optimized, as 10, 1 mg L-1, 40 min and 0.04 g, respectively. Langmuir, Freundlich and Dubinin-Radushkevich (D-R isotherm models were used to evaluate the adsorption mechanism. Adsorption constants values of these models suggest that the adsorption of parathion is favorable and were found to be best fit with Freundlich isotherm. From the kinetic study it can be predicted that adsorption of parathion follows Ho and McKay model (pseudo-second order. Thermodynamic parameters, enthalpy (ΔH, entropy (ΔS and Gibbs free energy (ΔG have also been evaluated and were found as -132.25, 0.45, -4.14 Jmol-1, respectively.

  19. Development of Cellulose Acetate Microcapsules with Cyanex 923 for Phenol Removal from Aqueous Media

    Directory of Open Access Journals (Sweden)

    Irma Pérez-Silva

    2018-01-01

    Full Text Available Microcapsules of cellulose acetate with Cyanex 923 were prepared and used in this study for phenol removal from water and synthetic textile wastewater. The influence of several factors on the microcapsules extraction efficiency was studied, as well as characterization and phenol adsorption isotherm. Microcapsules characterization demonstrated the extractant reagent encapsulation, while in a batch mode procedure, good adsorption of phenol (ca. 5.5 × 10−3 mol Kg−1 has been reached. A slight decrease in phenol extraction percentage was obtained when synthetic textile wastewater was used (ca. 4.955 × 10−3 mol Kg−1, although a decrease in color was observed due to dye microcapsule extraction. Results indicate that this method is a promising alternative to conventional phenol removal technologies for aqueous samples of low phenol concentrations or in textile effluents.

  20. Solvent extraction of hafnium(IV) by dinonylnaphthalene sulfonic acid from mixed aqueous-organic media

    International Nuclear Information System (INIS)

    Hala, J.; Piperkovova, H.

    1979-01-01

    The extraction of hafnium(IV) by heptane and toluene solutions of dinonylnaphthalene sulfonic acid (HD) from mixed aqueous-organic solutions has been studied. Alcohols, ketones, carboxylic acids, cyclic ethers, dimethylsulfoxide and dimethylformamide were used as the organic component of the mixed phase. Methanol, ethanol, formic acid and dioxane increased the extractability of Hf(IV) whereas other solvents showed only an antagonistic effect. The results were discussed from the point of view of the changes in micellar structure of HD, and compared with the uptake of Hf(IV) by resinous cation exchangers. The solubilization by HD of alcohols, carboxylic acids and dimethylsulfoxide was demonstrated by using the corresponding 14 C and 35 S labelled compounds. (author)

  1. A coumarin-derived Cu2 +-fluorescent chemosensor and its direct application in aqueous media

    Science.gov (United States)

    Mergu, Naveen; Kim, Myeongjin; Son, Young-A.

    2018-01-01

    A novel coumarin-based receptor bearing a benzohydrazide (FCBH) was developed as a fluorescent chemosensor with high selectivity toward Cu2 +. The sensor was successfully applied to the monitoring of Cu2 + in aqueous solution. After the addition of Cu2 + to FCBH, the color of the solution changed from greenish-yellow to red, and the absorption band at 457 nm red-shifted to 517 nm. The fluorescent green color of FCBH disappeared and the fluorescence emission was completely quenched in the presence of Cu2 +. Upon the addition of Cu2 +, deprotonation of FCBH occurred, and a 1:1 metal-ligand complex formed. DFT theoretical investigation was carried out to understand the behavior of the sensing probe toward Cu2 +. Additionally, the quenched fluorescence of the FCBH-Cu2 + complex was restored upon the addition of CN- ions. The possible sensing mechanism of FCBH toward Cu2 + was derived from experimental and theoretical examinations.

  2. Efficient Isomerization of Glucose to Fructose over Zeolites in Consecutive Reactions in Alcohol and Aqueous Media

    DEFF Research Database (Denmark)

    Shunmugavel, Saravanamurugan; Paniagua, Marta; Melero, Juan A

    2013-01-01

    glucose isomerization to fructose and subsequent reaction with methanol to form methyl fructoside (step 1), followed by hydrolysis to re-form fructose after water addition (step 2). NMR analysis with (13)C-labeled sugars confirmed this reaction pathway. Conversion of glucose for 1 h at 120 °C with H......-USY (Si/Al = 6) gave a remarkable 55% yield of fructose after the second reaction step. A main advantage of applying alcohol media and a catalyst that combines Brønsted and Lewis acid sites is that glucose is isomerized to fructose at low temperatures, while direct conversion to industrially important...

  3. Nucleophilic addition of amines to the activated ethylene bond in non-aqueous media

    International Nuclear Information System (INIS)

    Perepichka, Igor F.; Popov, Anatolii F.

    1995-01-01

    The kinetics of addition of a number of primary and secondary aliphatic amines to trans-(2-furyl) nitro ethylene (1) has been studied in solvents of various polarities (from acetonitrile, ε 37.5, to heptane, ε 1.89). It has been shown that the reaction is catalysed both by the amine reagent and by tertiary amines. On the basis of analyzing the observed kinetic regularities a stepwise reaction mechanism has been proposed which involves formation of zwitterionic intermediate (3) at the first equilibrium step (k 1 , K 1 ) which is then converted into the reaction product by means of proton transfer in parallel routes, the non-catalytic one (k 2 ) and that catalysed by the initial (K 3 ) or tertiary (K 4 ) amine. The observed high values of the deuterium isotope effects in the reaction (K H /K D ∼ 2.3 - 8.9) confirm that proton transfer occurs in the rate-limiting step of the reaction (primary kinetic isotope effect). The third order by amine kinetic route is observed in low polar media which is due to participation of amine dimers (R 2 NH HNR 2 ) in the reaction. The observed kinetic regularities are compared with those for the nucleophilic aromatic substitution reactions in low-polar media, and the conclusion has been made that the reaction route of the third order by amine proceeds as reversible nucleophilic attack by amine dimer and following base-catalysed transformation of the intermediate into the product. (author)

  4. Protein imprinting and recognition via forming nanofilms on microbeads surfaces in aqueous media

    International Nuclear Information System (INIS)

    Lu Yan; Yan Changling; Wang Xuejing; Wang Gongke

    2009-01-01

    In this paler, we present a technique of forming nanofilms of poly-3-aminophenylboronic acid (pAPBA) on the surfaces of polystyrene (PS) microbeads for proteins (papain and trypsin) in aqueous. Papain was chosen as a model to study the feasibility of the technique and trypsin as an extension. Obtained core-shell microbeads were characterized using scanning electron microscopy (SEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and BET methods. The results show that pAPBA formed nanofilms (60-100 nm in thickness) on the surfaces of PS microbeads. The specific surface area of the papain-imprinted beads was about 180 m 2 g -1 and its pore size was 31 nm. These imprinted microbeads exhibit high recognition specificity and fast mass transfer kinetics. The specificity of these imprinted beads mainly originates from the spatial effect of imprinted sites. Because the protein-imprinted sites were located at, or close to, the surface, the imprinted beads have good site accessibility toward the template molecules. The facility of the imprinting protocol and the high recognition properties of imprinted microbeads make the approach an attractive solution to problems in the field of biotechnology.

  5. Separation and preconcentration of Arsenic(III ions from aqueous media by adsorption on MWCNTs

    Directory of Open Access Journals (Sweden)

    Nahid Tavakkoli

    2017-05-01

    Full Text Available A simple and sensitive method using mini-column packed with multi-walled carbon nanotubes (MWCNTs combined with graphite furnace atomic absorption spectrometry (GFAAS for preconcentration and determination of ultra trace amounts of As(III in an aqueous medium is proposed. The procedure is based on the solid phase extraction of the As(III-sodium diethyldithiocarbamate (As-NaDDTC chelate on MWCNTs. Various parameters such as the effect of pH, eluent type and volume, amount of sorbent, and matrix effects on the quantitative recoveries of analyte ions were evaluated. It was found that sorption is quantitative and desorption occurs with 4.0 mL of 3.0 mol L−1 HNO3 in acetone. The limit of detection of the method was 0.008 ng mL−1 for GFAAS with enrichment factor of 125 and the relative standard deviation (RSD 0.97% (n = 8, C = 10 ng mL−1. This method has been applied to the determination of ultra trace As(III in water and rice plant and its ash successfully.

  6. Microwave Assisted Organic Synthesis of Heterocycles in Aqueous Media: Recent Advances in Medicinal Chemistry.

    Science.gov (United States)

    Frecentese, Francesco; Saccone, Irene; Caliendo, Giuseppe; Corvino, Angela; Fiorino, Ferdinando; Magli, Elisa; Perissutti, Elisa; Severino, Beatrice; Santagada, Vincenzo

    2016-01-01

    Green chemistry is a discipline of great interest in medicinal chemistry. It involves all fields of chemistry and it is based on the principle to conduct chemical reactions protecting the environment at the same time, through the use of chemical procedures able to avoid pollution. In this context, water as solvent is a good choice because it is abundant, nontoxic, non-caustic, and non-combustible. Even if microwave assisted organic reactions in conventional solvents have quickly progressed, in the recent years medicinal chemists have focused their attention to processes deemed not dangerous for the environment, using nanotechnology and greener solvents as water. Several reports of reaction optimizations and selectivities, demonstrating the capability of microwave to allow the obtaining of increased yields have been recently published using water as solvent. In this review, we selected the available knowledge related to microwave assisted organic synthesis in aqueous medium, furnishing examples of the newest strategies to obtain useful scaffolds and novel derivatives for medicinal chemistry purposes. The intention of this review is to demonstrate the exclusive ability of MAOS in water as solvent or as co-solvent. For this purpose we report here the most representative applications of MAOS using water as solvent, focusing on medicinal chemistry processes leading to interesting nitrogen containing heterocycles with potential pharmaceutical applications.

  7. High energy electron beam inactivation of lactate dehydrogenase suspended in different aqueous media

    International Nuclear Information System (INIS)

    Hategan, A.; Popescu, A.; Butan, C.; Oproiu, C.; Hategan, D.; Morariu, V.V.

    1999-01-01

    The direct and indirect effects of 5 MeV electron beam irradiation in the range (0-400 Gy) at 20 degC, 0 degC, -3 degC and -196 degC, as well as the influence of the aqueous suspending medium (ultrapure water and heavy water) on the total enzymatic activity of lactate dehydrogenase (LDH) have been studied. Our results showed an exponential decrease on the enzymatic activity of irradiated LDH, at all irradiation temperatures, independently of the direct or indirect action of radiation. The temperature gradient used to lower the temperature of the samples to -196 degC drastically influences the results. Freeze-thawing in two steps down to -196 degC protects LDH to radiation, in the dose range used. The data obtained here inform on the high energy electrons effects on the enzymatic activity loss during irradiation and during thawing, when the subsequent growth of the water crystals influences the three dimensional structure of the enzyme. A 99.98% concentration of D 2 O in the suspending medium of the enzyme decreases the global enzymatic activity, but reduces the rate of radiation inactivation of the enzyme. The rate of radiation inactivation of the enzyme suspended in ultrapure water is reduced when compared to the enzyme suspended in bidistilled water, but compared to the D 2 O suspended enzyme is lightly increased. (author)

  8. Pertechnetate immobilization in aqueous media with hydrogen sulfide under anaerobic and aerobic environments

    International Nuclear Information System (INIS)

    Liu, Y.; Jurisson, S.; Terry, J.

    2007-01-01

    The basic chemistry for the immobilization of pertechnetate (TcO 4 - ) by hydrogen sulfide was investigated in aqueous solution under both aerobic and anaerobic environments. Pertechnetate immobilization was acid dependent, with accelerated rates and increased immobilization yields as the acid concentration increased. Oxygen had no effect under acidic conditions. Under anaerobic alkaline conditions, the pH, and therefore the speciation of sulfide, was the determining factor on the immobilization of pertechnetate. Only 53% of the TcO 4 - was immobilized at pH 8, while the yield increased to 83% at pH 9 as HS - became the dominant sulfide species. The immobilization yield then decreased to 73% at pH 13. No reaction was observed between TcO 4 - and sulfide under aerobic alkaline conditions, indicating that oxygen suppressed this reaction. Pertechnetate immobilization was found to be first order with respect to both sulfide and pertechnetate in acidic solutions, and in alkaline solution under anaerobic conditions. The results of stoichiometry studies and product analysis under alkaline anaerobic environments indicated that Tc 2 S 7 was obtained at pH 9. EXAFS (extended X-ray absorption fine structure) and XANES (X-ray absorption near edge structure) studies suggested that the samples obtained from acidic, aerobic solution and alkaline anaerobic solution were both Tc 2 S 7 . The stability of Tc 2 S 7 is affected by O 2 with accelerated dissolution at high pH. (orig.)

  9. Synthesis of assembled ZnO structures by precipitation method in aqueous media

    International Nuclear Information System (INIS)

    Sepulveda-Guzman, S.; Reeja-Jayan, B.; Rosa, E. de la; Torres-Castro, A.; Gonzalez-Gonzalez, V.; Jose-Yacaman, M.

    2009-01-01

    In this work, arrays of submicron ZnO structures were successfully synthesized using a one-step aqueous precipitation method. Snowflake-like and flower-like morphologies were obtained by changing the reaction temperature. X-ray diffraction (XRD) patterns indicated that the ZnO arrays have a wurtzite crystal structure. A possible growth mechanism based on the analysis done by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and high-angle annular dark field (HAADF) is proposed. Our findings suggest that the growth mechanism of the ZnO arrays is by self-aggregation, and that such an oriented aggregation is enhanced by increasing the reaction temperature. The results also revealed that the aggregation process introduces several structural defects such as differences in mass distribution and crystalline structure. In order to study the surface chemical composition the samples were also characterized by XPS. The results showed the presence of Zn(OH) 2 and absorbed carbon species on the ZnO surface. In addition, the photoluminescence characterization showed that on UV excitation (λ = 360 nm) all samples present the characteristic UV emission centered at 390 nm, and for the sample synthesized at 60 deg. C, a visible emission was also observed

  10. Synthesis of assembled ZnO structures by precipitation method in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Sepulveda-Guzman, S. [Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, UANL Km. 10 de la nueva carretera al Aeropuerto Internacional de Monterrey, PIIT Monterrey, Apodaca NL (Mexico); Facultad de Ingenieria Mecanica y Electrica de la UANL, Ciudad Universitaria San Nicolas de los Garza, Nuevo Leon C.P. 66451 (Mexico)], E-mail: ssepulveda@mail.uanl.mx; Reeja-Jayan, B. [Texas Materials Institute, University of Texas at Austin, 1 University Station C0803 (United States); Rosa, E. de la [Centro de Investigaciones en Optica, A.C. Loma del Bosque 115 Col. Lomas del Campestre, Leon Gto. C.P. 37150 (Mexico); Torres-Castro, A.; Gonzalez-Gonzalez, V. [Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, UANL Km. 10 de la nueva carretera al Aeropuerto Internacional de Monterrey, PIIT Monterrey, Apodaca NL (Mexico); Facultad de Ingenieria Mecanica y Electrica de la UANL, Ciudad Universitaria San Nicolas de los Garza, Nuevo Leon C.P. 66451 (Mexico); Jose-Yacaman, M. [Physics and Astronomy Department, University of Texas at San Antonio, 1604 Campus San Antonio, TX 78249 (United States)

    2009-05-15

    In this work, arrays of submicron ZnO structures were successfully synthesized using a one-step aqueous precipitation method. Snowflake-like and flower-like morphologies were obtained by changing the reaction temperature. X-ray diffraction (XRD) patterns indicated that the ZnO arrays have a wurtzite crystal structure. A possible growth mechanism based on the analysis done by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and high-angle annular dark field (HAADF) is proposed. Our findings suggest that the growth mechanism of the ZnO arrays is by self-aggregation, and that such an oriented aggregation is enhanced by increasing the reaction temperature. The results also revealed that the aggregation process introduces several structural defects such as differences in mass distribution and crystalline structure. In order to study the surface chemical composition the samples were also characterized by XPS. The results showed the presence of Zn(OH){sub 2} and absorbed carbon species on the ZnO surface. In addition, the photoluminescence characterization showed that on UV excitation ({lambda} = 360 nm) all samples present the characteristic UV emission centered at 390 nm, and for the sample synthesized at 60 deg. C, a visible emission was also observed.

  11. SINTESIS SILIKA AEROGEL DENGAN BAHAN DASAR ABU BAGASSE

    Directory of Open Access Journals (Sweden)

    Nazriati Nazriati

    2012-05-01

    Full Text Available SYNTHESIS OF SILICA AEROGEL FROM BAGASSE ASH. Synthesis of silica aerogel from bagasse ash was done by alkaline extraction followed by sol-gel. Bagasse ash was extracted with NaOH at its boiling temperature for one hour with continue stirring, to produce sodium silicate. Subsequently, sodium silicate was pass through ionic exchanger resin, to produces silicic acid (SA. Silicic acid solution was then added with TMCS and HMDS as surface modifier agent. In order to form gel pH must be adjusted to final pH of 8-9 by addition of NH4OH solution. The resulting gel then was aged and dried at ambient pressure and at a certain time and temperature. Characterization of products was done by measuring its pore volume, surface area, and hydrophobisity (contact angle. TMCS serves as water expeller from the pores and subsequently surface was modified by HMDS and TMCS. HMDS content will linearly increase surface area, pore volume, and the contact angle of the resulting silica aerogel. Characteristics of silica aerogel was generated by varying the composition of the SA:TMCS:HMDS resulting has a surface area of 50-488 m2/g, pore volume from 0.2 to 0.9 m3 /g, the contact angle of 48-119 and pore diameter ranging from 5.7-22.56 nm. Based on the resulting pore diameter, the synthesized of silica aerogel categorized as mesoporous.      Abstrak   Sintesis silika aerogel dari bahan dasar abu bagasse dilakukan dengan ekstraksi basa dan diikuti dengan sol-gel. Abu bagasse diekstrak dengan NaOH pada suhu didihnya sambil diaduk selama satu jam, menghasilkan sodium silikat. Selanjutnya, sodium silikat dilewatkan resin penukar ion, menghasilkan asam silicic (SA. Larutan asam silicic kemudian ditambahkan trimethy­l­chlorosilane (TMCS dan hexamethyldisilazane (HMDS sebagai agen pemodifikasi permukaan. Untuk terjadinya gel pH diatur hingga mencapai 8-9 dengan penambahan larutan NH4OH. Gel yang dihasilkan kemudian di-aging dan dikeringkan pada tekanan ambien pada suhu dan

  12. Simultaneous Extraction and Depolymerization of Fucoidan from Sargassum muticum in Aqueous Media

    Directory of Open Access Journals (Sweden)

    Elena M. Balboa

    2013-11-01

    Full Text Available The biomass components of the invasive seaweed Sargassum muticum were fractionated to allow their separate valorization. S. muticum (Sm and the solid residue remaining after alginate extraction of this seaweed (AESm were processed with hot, compressed water (hydrothermal processing to assess the effects of temperature on fucoidan solubilization. Fucose-containing oligosaccharides were identified as reaction products. Operating under optimal conditions (170 °C, up to 62 and 85 wt% of the dry mass of Sm and AESm were solubilized, respectively. The reaction media were subjected to precipitation, nanofiltration and freeze-drying. The dried products contained 50% and 85% of the fucoidan present in Sm and AESm, respectively; together with other components such as phenolics and inorganic components. The saccharidic fraction, accounting for up to 35% of the dried extracts, contained fucose as the main sugar, and also galactose, xylose, glucose and mannose. The concentrates were characterized for antioxidant activity using the TEAC assay.

  13. Extremophile mediated hydrogen production for hydrogenation of substrates in aqueous media

    Science.gov (United States)

    Anjom, Mouzhgun

    Catalytic hydrogenation reactions are pervasive throughout our economy, from production of margarine as food, liquid fuels for transportation and chiral drugs such as L-DOPA. H2 production from non-fossil fuel feedstocks is highly desirable for transition to the "Hydrogen Economy". Also, the rates of hydrogenation reactions that involve a substrate, H 2 gas and a catalyst are often limited by the solubility of H2 in solvent. The present research thus envisioned designing water-soluble catalysts that could effectively utilize biologically produced H2 in a coupled system to hydrogenate substrates in homogeneous mode (two-phase system). Biological production of H2 as an end product or byproduct of the metabolism of organisms that operate under strict anaerobic conditions has been proposed. However, contrary to what was previously observed, Thermotoga neapolitana, belonging to the order of Thermotogales efficiently produces H2 gas under microaerobic conditions (Van Ooteghem et al. 2004). For H2 production by T. neapolitana in the bacterial growth medium (DSM 5068) at an optimum temperature of 70 C, our results in batch mode show that: (1) H2 was produced from glucose though with 16% efficiency, the rest goes to biomass production, (2) H2 gas was produced even when the cultures were inoculated under microaerobic conditions (up to 8% (v/v) O2) suggesting a protective mechanism for one or more [Fe-Fe] hydrogenases in T. neapolitana, (3) H2 production was pH dependent but addition of simple, non-toxic physiological buffering additives such as Methylene succinic acid increased H2 production and (4) H2 production rate varied linearly in the 100--6800 kPa pressure range. We then screened various water-soluble metal catalysts in batch mode and selected the RhCl3.3H2O/TPPTS (TPPTS is a water-soluble ligand) system that achieved 86% hydrogenation of Methylene succinic acid (an olefin) in an aqueous medium pressurized with preformed H2. When water was replaced with the DSM 5068

  14. Chlorinated phenol removal from aqueous media by tea (Camellia sinensis) leaf waste tailored activated carbon

    Science.gov (United States)

    Joseph, C. G.; Anisuzzaman, S. M.; Daud, W. M. A. W.; Krishnaiah, D.; Ng, K. A.

    2017-06-01

    In this study, activated carbons (ACs) wereprepared from tea leaves by using a two-stage self-generated atmosphere method. The process was done by semi-carbonizing the precursor at 300 °C for 1 h, followed by the impregnation of the resulting char at 85 °C for 4 h and finally activation at 500 °C for 2 h. The semi-carbonised samples were impregnated with different ratios of zinc chloride (ZnCl2) and their physicochemical effect was studied. The prepared ACs underwent several aspects of both, chemical and physical characterizations, such as the percentage of yield, moisture content, ash content, pH, porosity, adsorption capacity of 2,4-dichlorophenol (2,4-DCP), surface area, porosity, morphology and surface chemistry studies. It was found that sample AC2, with an impregnation ratio of 2:1 was the best AC produced in this study. The maximum Brunauer, Emmett and Teller surface area of AC2 was found to be 695 m2/g. Langmuir, Freundlich and Temkin isotherm models were used to examine the experimental isotherms while the kinetic data was analyzed using the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. The 2,4-DCP adsorption isotherm results complied well to the Langmuir isotherm for the equilibrium data while the adsorption kinetic data fitted well to the pseudo-second order model, indicating that chemisorption by valency forces via the sharing (covalent bond) or exchanging of electrons between the AC and the 2,4-DCP molecules were mainly responsible for the adsorption process. From these findings, it is concluded that tea leaves can be used as a low cost precursor for the removal of 2,4-DCP in aqueous medium.

  15. Biocompatible ZnS:Mn quantum dots for reactive oxygen generation and detection in aqueous media

    Science.gov (United States)

    Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Bracho-Rincon, Dina P.; González-Feliciano, José A.; González, Carlos I.; Weiner, Brad R.; Morell, Gerardo

    2015-12-01

    We report here the versatility of Mn-doped ZnS quantum dots (ZnS:Mn QDs) synthesized in aqueous medium for generating reactive oxygen species and for detecting cells. Our experiments provide evidence leading to the elimination of Cd-based cores in CdSe/ZnS systems by substitution of Mn-doped ZnS. Advanced electron microscopy, X-ray diffraction, and optical spectroscopy were applied to elucidate the formation, morphology, and dispersion of the products. We study for the first time the ability of ZnS:Mn QDs to act as immobilizing agents for Tyrosinase (Tyr) enzyme. It was found that ZnS:Mn QDs show no deactivation of Tyr enzyme, which efficiently catalyzed the hydrogen peroxide (H2O2) oxidation and its eventual reduction (-0.063 V vs. Ag/AgCl) on the biosensor surface. The biosensor showed a linear response in the range of 12 μmol/L-0.1 mmol/L at low operation potential. Our observations are explained in terms of a catalase-cycled kinetic mechanism based on the binding of H2O2 to the axial position of one of the active copper sites of the oxy-Tyr during the catalase cycle to produce deoxy-Tyr. A singlet oxygen quantum yield of 0.62 in buffer and 0.54 in water was found when ZnS:Mn QDs were employed as a photosensitizer in the presence of a chemical scavenger and a standard dye. These results are consistent with a chemical trapping energy transfer mechanism. Our results also indicate that ZnS:Mn QDs are well tolerated by HeLa Cells reaching cell viabilities as high as 88 % at 300 µg/mL of QDs for 24 h of incubation. The ability of ZnS:Mn QDs as luminescent nanoprobes for bioimaging is also discussed.

  16. Biocompatible ZnS:Mn quantum dots for reactive oxygen generation and detection in aqueous media

    International Nuclear Information System (INIS)

    Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Bracho-Rincon, Dina P.; González-Feliciano, José A.; González, Carlos I.; Weiner, Brad R.; Morell, Gerardo

    2015-01-01

    We report here the versatility of Mn-doped ZnS quantum dots (ZnS:Mn QDs) synthesized in aqueous medium for generating reactive oxygen species and for detecting cells. Our experiments provide evidence leading to the elimination of Cd-based cores in CdSe/ZnS systems by substitution of Mn-doped ZnS. Advanced electron microscopy, X-ray diffraction, and optical spectroscopy were applied to elucidate the formation, morphology, and dispersion of the products. We study for the first time the ability of ZnS:Mn QDs to act as immobilizing agents for Tyrosinase (Tyr) enzyme. It was found that ZnS:Mn QDs show no deactivation of Tyr enzyme, which efficiently catalyzed the hydrogen peroxide (H 2 O 2 ) oxidation and its eventual reduction (−0.063 V vs. Ag/AgCl) on the biosensor surface. The biosensor showed a linear response in the range of 12 μmol/L–0.1 mmol/L at low operation potential. Our observations are explained in terms of a catalase-cycled kinetic mechanism based on the binding of H 2 O 2 to the axial position of one of the active copper sites of the oxy-Tyr during the catalase cycle to produce deoxy-Tyr. A singlet oxygen quantum yield of 0.62 in buffer and 0.54 in water was found when ZnS:Mn QDs were employed as a photosensitizer in the presence of a chemical scavenger and a standard dye. These results are consistent with a chemical trapping energy transfer mechanism. Our results also indicate that ZnS:Mn QDs are well tolerated by HeLa Cells reaching cell viabilities as high as 88 % at 300 µg/mL of QDs for 24 h of incubation. The ability of ZnS:Mn QDs as luminescent nanoprobes for bioimaging is also discussed.Graphical Abstract

  17. Biocompatible ZnS:Mn quantum dots for reactive oxygen generation and detection in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Diestra, Daysi; Beltran-Huarac, Juan, E-mail: juan.beltran1@upr.edu; Bracho-Rincon, Dina P.; González-Feliciano, José A.; González, Carlos I.; Weiner, Brad R.; Morell, Gerardo [University of Puerto Rico, Molecular Sciences Research Center (United States)

    2015-12-15

    We report here the versatility of Mn-doped ZnS quantum dots (ZnS:Mn QDs) synthesized in aqueous medium for generating reactive oxygen species and for detecting cells. Our experiments provide evidence leading to the elimination of Cd-based cores in CdSe/ZnS systems by substitution of Mn-doped ZnS. Advanced electron microscopy, X-ray diffraction, and optical spectroscopy were applied to elucidate the formation, morphology, and dispersion of the products. We study for the first time the ability of ZnS:Mn QDs to act as immobilizing agents for Tyrosinase (Tyr) enzyme. It was found that ZnS:Mn QDs show no deactivation of Tyr enzyme, which efficiently catalyzed the hydrogen peroxide (H{sub 2}O{sub 2}) oxidation and its eventual reduction (−0.063 V vs. Ag/AgCl) on the biosensor surface. The biosensor showed a linear response in the range of 12 μmol/L–0.1 mmol/L at low operation potential. Our observations are explained in terms of a catalase-cycled kinetic mechanism based on the binding of H{sub 2}O{sub 2} to the axial position of one of the active copper sites of the oxy-Tyr during the catalase cycle to produce deoxy-Tyr. A singlet oxygen quantum yield of 0.62 in buffer and 0.54 in water was found when ZnS:Mn QDs were employed as a photosensitizer in the presence of a chemical scavenger and a standard dye. These results are consistent with a chemical trapping energy transfer mechanism. Our results also indicate that ZnS:Mn QDs are well tolerated by HeLa Cells reaching cell viabilities as high as 88 % at 300 µg/mL of QDs for 24 h of incubation. The ability of ZnS:Mn QDs as luminescent nanoprobes for bioimaging is also discussed.Graphical Abstract.

  18. Dithizone as novel and efficient chromogenic probe for cyanide detection in aqueous media through nucleophilic addition into diazenylthione moiety.

    Science.gov (United States)

    Tavallali, Hossein; Deilamy-Rad, Gohar; Parhami, Abolfath; Kiyani, Sajede

    2014-01-01

    A new selective chemodosimeter probe was developed by the introduction of dithizone (DTZ) as a simple and available dye for detection of cyanide in aqueous media which enables recognition of cyanide over other competing anions such as acetate, dihydrogen phosphate, fluoride and benzoate through covalent bonding. The sensing properties of DTZ were investigated in DMSO/H2O (1:9) and have demonstrated a very high selectivity toward the cyanide anions. A reasonable recognition mechanism was suggested using UV-Vis, (1)H NMR and FTIR spectroscopy techniques. Time dependent density function theory (TDDFT) computations of UV-Vis excitation for DTZ2-CN adduct agreed well with our experimental findings. The detection limit of the new chromogenic probe was measured to be 0.48 μmol L(-1) which is much lower than most recently reported chromogenic probes for cyanide determination. The analytical utility of the method for the analysis of cyanide ions in electroplating wastewater (EPWW), human serum, tap and mineral water samples was demonstrated and the results were compared successfully with the conventional reference method. The short time response and the detection by the naked eye make the method available for the detection and quantitative determination of cyanide in a variety of real samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Electrochemical oxidation of synthetic tannery wastewater in chloride-free aqueous media

    International Nuclear Information System (INIS)

    Costa, Carla Regina; Montilla, Francisco; Morallon, Emilia; Olivi, Paulo

    2010-01-01

    The electrochemical treatment of a synthetic tannery wastewater, prepared with several compounds used by finishing tanneries, was studied in chloride-free media. Boron-doped diamond (Si/BDD), antimony-doped tin dioxide (Ti/SnO 2 -Sb), and iridium-antimony-doped tin dioxide (Ti/SnO 2 -Sb-Ir) were evaluated as anode. The influence of pH and current density on the treatment was assessed by means of the parameters used to measure the level of organic contaminants in the wastewater; i.e., total phenols, chemical oxygen demand (COD), total organic carbon (TOC), and absorbance. Results showed that faster decrease in these parameters occurred when the Si/BDD anode was used. Good results were obtained with the Ti/SnO 2 -Sb anode, but its complete deactivation was reached after 4 h of electrolysis at 25 mA cm -2 , indicating that the service life of this electrode is short. The Ti/SnO 2 -Sb-Ir anode is chemically and electrochemically more stable than the Ti/SnO 2 -Sb anode, but it is not suitable for the electrochemical treatment under the studied conditions. No significant changes were observed for electrolyses performed at different pH conditions with Si/BDD, and this electrode led to almost complete mineralization after 4 h of electrolysis at 100 mA cm -2 . The increase in current density resulted in faster wastewater oxidation, with lower current efficiency and higher energy consumption. Si/BBD proved to be the best electrodic material for the direct electrooxidation of tannery wastewaters.

  20. Detoxification of Hg(II) from aqueous and enzyme media: Pristine vs. tailored calcium alginate hydrogels.

    Science.gov (United States)

    Sarkar, Kangkana; Ansari, Zarina; Sen, Kamalika

    2016-10-01

    Calcium alginate (CA) hydrogels were tailored using phenolic compounds (PC) like, thymol, morin, catechin, hesperidin, during their preparation. The PC incorporated gels show modified surface features as indicated by scanning electron microscopic images (SEM). The rheological studies show that excepting the hesperidin incorporated gels all the other kinds including calcium alginate pristine have similar mechanical strength. The hesperidine incorporated CA gels had the maximum capacity to adsorb Hg. The Freundlich adsorption isotherms show higher values of adsorption capacity for all PC incorporated CA beads than the pristine CA (PCA). The hesperidin incorporated CA gels were found to show the best adsorption condition at neutral pH and an optimum contact time of 2.5h at 25°C. Considering the possibility of ingested Hg detoxification from human alimentary tract, the hesperidin and morin incorporated CA beads were further modified through incorporation of cod liver oil as the digestion time of fat in stomach is higher. In vitro uptake capacities of Hg in pepsin and pancreatin containing enzyme media were studied with hesperidin and morin incorporated beads and their corresponding fat incorporated beads also. In the pepsin medium, there was no uptake by hesperidin and fat-hesperidin incorporated beads, which is possibly due to the higher acidity of the medium. But in pancreatin medium Hg was taken up by both kinds of beads. Morin and morin-fat incorporated beads were efficient to uptake Hg from both the pepsin and pancreatin medium. The tailored CA beads may therefore serve as efficient scaffolds to rescue Hg ingested individuals. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Theoretical, physical and experimental study of fissile aqueous media; Etudes theorique, physique et experimentale des milieux fissiles aqueux

    Energy Technology Data Exchange (ETDEWEB)

    Caizergues, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-04-01

    This thesis consists of a set of theoretical and experimental studies. a) Theoretical calculation methods used for cross-sections and the critical parameters; b) Comparison of the theoretical and experimental results: it is shown that the agreement between these results cannot be improved above a certain limit because of the accuracy with which are known the composition and the dimensions of the media and the microscopic cross-sections; c) Determination of the ratios {eta}{sup 9}-bar / {eta}{sup 5}-bar, {eta}{sup 3}-bar / {eta}{sup 5}-bar for fissile aqueous media ({eta}-bar: number of neutrons emitted per neutron absorbed, averaged over the reactor neutron spectrum). Evaluation of the accuracy to which these ratios are known; d) Effect of {sup 240}Pu: the measurements are carried out on Pu with a {sup 240}Pu content of 1.5 per cent, 3.11 per cent and 9.95 per cent; Calculation of the resonance integral I240 using the experimental results gives values in reasonable agreement with the results obtained by other more conventional methods. e) Measurement of the spectrum indices for aqueous media containing Pu, U5 and U3. With these latter it is possible to obtain mean fission cross-section ratios {sigma}f239-bar / {sigma}f235-bar for these different spectra. A calculation-experiment comparison is carried out using various theoretical methods. (author) [French] Cette these groupe un ensemble d'etudes theoriques et experimentales. a) Methodes theoriques de calcul utilisees pour les sections efficaces et les parametres critiques; b) Comparaisons des resultats theoriques et experimentaux: on montre que l'accord entre ces resultats ne peut etre ameliore au-dela de certaines limites vu la precision avec laquelle sont connues la composition et les dimensions des milieux et les sections efficaces macroscopiques; c) Determination des rapports {eta}{sup 9}-bar / {eta}{sup 5}-bar, {eta}{sup 3}-bar / {eta}{sup 5}-bar pour les milieux fissiles aqueux ({eta}: nombre de

  2. Theoretical, physical and experimental study of fissile aqueous media; Etudes theorique, physique et experimentale des milieux fissiles aqueux

    Energy Technology Data Exchange (ETDEWEB)

    Caizergues, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-04-01

    This thesis consists of a set of theoretical and experimental studies. a) Theoretical calculation methods used for cross-sections and the critical parameters; b) Comparison of the theoretical and experimental results: it is shown that the agreement between these results cannot be improved above a certain limit because of the accuracy with which are known the composition and the dimensions of the media and the microscopic cross-sections; c) Determination of the ratios {eta}{sup 9}-bar / {eta}{sup 5}-bar, {eta}{sup 3}-bar / {eta}{sup 5}-bar for fissile aqueous media ({eta}-bar: number of neutrons emitted per neutron absorbed, averaged over the reactor neutron spectrum). Evaluation of the accuracy to which these ratios are known; d) Effect of {sup 240}Pu: the measurements are carried out on Pu with a {sup 240}Pu content of 1.5 per cent, 3.11 per cent and 9.95 per cent; Calculation of the resonance integral I240 using the experimental results gives values in reasonable agreement with the results obtained by other more conventional methods. e) Measurement of the spectrum indices for aqueous media containing Pu, U5 and U3. With these latter it is possible to obtain mean fission cross-section ratios {sigma}f239-bar / {sigma}f235-bar for these different spectra. A calculation-experiment comparison is carried out using various theoretical methods. (author) [French] Cette these groupe un ensemble d'etudes theoriques et experimentales. a) Methodes theoriques de calcul utilisees pour les sections efficaces et les parametres critiques; b) Comparaisons des resultats theoriques et experimentaux: on montre que l'accord entre ces resultats ne peut etre ameliore au-dela de certaines limites vu la precision avec laquelle sont connues la composition et les dimensions des milieux et les sections efficaces macroscopiques; c) Determination des rapports {eta}{sup 9}-bar / {eta}{sup 5}-bar, {eta}{sup 3}-bar / {eta}{sup 5}-bar pour les milieux fissiles aqueux ({eta}: nombre de neutrons emis

  3. One-Pot Synthesis of Some New Pyrido[2,3-d]pyrimidine Derivatives Catalyzed by Sodium Lauryl Sulfate in Aqueous Media

    Directory of Open Access Journals (Sweden)

    Sheng-Hui Li

    2010-01-01

    Full Text Available A series of pyrido[2,3-d]pyrimidine derivatives were synthesized by the three-component reaction of aromatic aldehyde, malononitrile and 6-amino-4-hydroxy-2-mercaptopyrimidine catalyzed by sodium lauryl sulfate (SDS in aqueous media. It was interesting that further aromatization took place automatically. This method provides several advantages such as easier work-up, milder reaction conditions and environmental friendly.

  4. An Efficient and Practical Process for Pd/Cu Cocatalyzed Homocoupling Reaction of Terminal Alkynes Using Sodium Percarbonate as a Dual Reagent in Aqueous Media

    Institute of Scientific and Technical Information of China (English)

    ZHOU, Lei; ZHAN, Hai-Ying; LIU, Hai-Ling; JIANG, Huan-Feng

    2007-01-01

    A new process for the Pd/Cu co-catalyzed homocoupling reaction of terminal alkynes was developed. The reaction was carried out in aqueous media with sodium percarbonate as both a clean oxidant and a base. Meanwhile, a palladium complex immobilized on a synthetic PS-PEG400-PPh2 resin was used as the catalyst, which may be recovered by simple filtration and reused for several times with high activity.

  5. Moessbauer spectroscopy characterization and electrochemical study of the kinetics of oxidation of iron in chlorinated aqueous media: structure and equilibrium diagram of green rust one

    International Nuclear Information System (INIS)

    Genin, J.M.R.; Rezel, D.; Bauer, Ph.; Olowe, A.; Beral, A.

    1986-01-01

    Moessbauer spectroscopy allows to precise the structure of akaganeite, lepidocrocite, green rust I and initial hydroxide of a simulated corrosion process of iron in chlorinated aqueous media. The characterization of the compounds during the process is coupled with E - pH recordings, yielding the kinetics of the various reactions (order and activation energy) as well as the Pourbaix diagram of Green Rust I by scanning the [Cl - ]/[OH - ] ratio. (author) 16 refs., 15 figs

  6. One-pot synthesis of Fe3O4@Chitosan-pSDCalix hybrid nanomaterial for the detection and removal of Hg2+ ion from aqueous media

    Science.gov (United States)

    Bhatti, Asif Ali; Oguz, Mehmet; Yilmaz, Mustafa

    2018-03-01

    New one pot mesoporous hybrid material containing iron nanoparticles fabricated with chitosan and p-sulfonato dansyl calix[4]arene composite (Fe3O4@Chitosan-pSDCalix) has been susccessfully synthesized. These mesoporous fluorescence iron nanoparticles were applied for the detection and removal of environmentally toxic Hg2+ ion from aqueous media. Different techniques were applied to confirm the preparation of Fe3O4@Chitosan-pSDCalix such as HRTEM, TGA/DTA, FTIR and XRD. Synthesized nanoparticles have average size of 17 nm with pore size of 0.19 nm as revealed from HRTEM images. Fluorescence study follow the photoinduced electron transfer process after addition of Hg2+ in the solution with decrease in intensity. Confocal microscope images were also acquired to confirm the presence of Hg2+ on nanoparticles. Adsorption study suggests that the removal of Hg2+ from aqueous media follows Langmuir adsorption isotherm. These studies suggest the synthesized Fe3O4@Chitosan-pSDCalix is an efficient hybrid material for the detection and removal of Hg2+ ion from aqueous media, and that it can also be used in biomolecules for the detection of toxic metal ions.

  7. SINTESIS DAN MODIFIKASI LAPIS TIPIS KITOSAN-TRIPOLIFOSFAT

    Directory of Open Access Journals (Sweden)

    M Alauhdin

    2014-11-01

    Full Text Available Dalam bidang medis, kitosan telah banyak digunakan yakni pada sistem penghantaran dan pelepasan obat. Pelepasan obat dengan kitosan memiliki keterbatasan karena kitosan cepat sekali menyerap air dan memiliki derajat swelling yang tinggi sehingga menyebabkan pelepasan obat terjadi dengan cepat. Diharapkan dengan memodifikasi struktur kitosan secara kimia dapat meningkatan kelarutannya dalam pelarut-pelarut organik. Telah dilakukan sintesis dan modifikasi lapis tipis kitosan. Modifikasi dilakukan melalui pembentukan ikatan silang kitosan dengan tripolifosfat (TPP pada kondisi asam untuk menghasilkan kitosan-TPP. Ikatan silang yang terbentuk diamati dengan FTIR. Sementara itu, pengaruh hasil pengikatan silang diamati dengan membandingkan rasio swelling kitosan-TPP pada kondisi pH yang berbeda-beda. Rasio swelling lapis tipis cenderung konstan setelah terjadi pengikatan silang kitosan dengan tripolifosfat. Reaksi tripolifosfat dengan kitosan melalui pembentukan ikatan silang menjadikan lapis tipis semakin rapat sehingga molekul air sulit untuk berdifusi masuk ke dalam struktur kitosan-tripolifosfat. Hasil ini menunjukkan bahwa pengikatan silang mampu mengurangi kelarutan dan meningkatkan sifat mekanik kitosan. Rasio swelling lapis tipis berkurang dengan adanya pengikatan silang. Hal ini mengindikasikan bahwa pengikatan silang oleh TPP dapat mengurangi hidrofilitas lapis tipis karena gugus amino yang reaktif telah bereaksi dengan ion tripolifosfat. In the medical field, chitosan has been widely used in the delivery systems and drug release. Drug release with chitosan has limitations because chitosan absorbs water very quickly and have a high degree of swelling that causes the release of the drug occurs rapidly. It is expected that by modifying the chemical structure of chitosan could improve its solubility in organic solvents. The synthesis and modification of chitosan thin film have been done. It was performed through the formation of crosslinked

  8. On the selection of the anode material for the electrochemical removal of methylparaben from different aqueous media

    International Nuclear Information System (INIS)

    Steter, Juliana R.; Brillas, Enric; Sirés, Ignasi

    2016-01-01

    Highlights: • Comparative performance of EO-H 2 O 2 , EF and PEF with BDD, Pt and DSA as anodes. • Poor effect of anode on methylparaben mineralization by PEF but large effect in EO-H 2 O 2 . • Pseudo-first-order decay kinetics in EO-H 2 O 2 and much quicker complex kinetics in PEF. • Beneficial effect of Cl − in EO-H 2 O 2 but slightly or significantly detrimental in EF and PEF. • Quickest degradation in PEF with BDD, yielding chlorinated and non-chlorinated by-products. - Abstract: Parabens are widely used industrial preservatives, routinely found in wastewater along with major inorganic ions like sulfate and chloride. This work investigates the oxidation ability of three electrochemical processes in tank reactors equipped with an air-diffusion cathode to electrogenerate H 2 O 2 on site, namely electro-oxidation (EO-H 2 O 2 ), electro-Fenton (EF) and UVA photoelectro-Fenton (PEF), to degrade aqueous solutions of methylparaben (MeP) at pH 3.0. Their performance using boron-doped diamond (BDD), Pt or two kinds of dimensionally stable anodes (DSA ® ) has been compared from the analysis of mineralization profiles and decay kinetics in the presence of sulfate and/or chloride ions. The use of BDD ensured the overall mineralization in all three processes according to the sequence: PEF > EF > EO-H 2 O 2 , thanks to the contribution of BDD(·OH), ·OH and UVA light. Pt and DSA ® became an interesting alternative in PEF, with slower organic matter removal but similar final mineralization percentages, being much less powerful than BDD in EO-H 2 O 2 . The presence of Cl − was beneficial in the latter process, due to the formation of active chlorine as an additional oxidant that caused a much faster decay of MeP. Conversely, it became significantly detrimental in EF due to the partial destruction of H 2 O 2 and ·OH in the bulk by active chlorine and Cl − , respectively. The oxidation power of PEF was so high that similar fast, complex decay kinetics was

  9. Ordered mesoporous carbon film as an effective solid-phase microextraction coating for determination of benzene series from aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Hui [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); School of Geography Science, Nantong University, Nantong 226001 (China); Li, Jiansheng, E-mail: lijsh@mail.njust.edu.cn [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Jiang, Mingyue; Lu, Rui; Shen, Jinyou; Sun, Xiuyun; Han, Weiqing [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Wang, Lianjun, E-mail: wanglj@mail.njust.edu.cn [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2015-08-12

    The present work reports preparation of ordered mesoporous carbon (OMC) film supported on a graphite fiber as a new type of solid-phase microextraction (SPME) fiber for determination of benzene series from aqueous media. The strategy for the supported OMC film preparation was combined dip-coating technology with solvent evaporation-induced self-assembly (EISA) approach. A graphite fiber was immersed in an ethanol solution containing phenolic resin and Pluronic triblock copolymer. Upon solvent evaporation and subsequent pyrolysis under 700 °C, the phenolic resin and the surfactant self-assembled on the surface of the graphite fiber to form smooth OMC film. X-ray diffraction (XRD), transmission electron microscopy (TEM) and nitrogen isothermal adsorption results indicate that the resultant OMC film possesses well-ordered two dimensional hexagonal mesostructure with pore diameters of 4.5 nm and BET surfaces of 630 m{sup 2}/g. Scanning electron microscopy (SEM) studies show the supported OMC film with thickness at 8.5 μm is continuous and defect-free. The SPME efficiency of the OMC fiber was evaluated by analysis of five benzene series (benzene, toluene, ethylbenzene, p-xylene and m-xylene) from water samples by gas chromatography-flame ionization detection (GC-FID). The analysis results indicate that the prepared OMC fiber has wide linear ranges (0.5–500 μg/L), low detection limits (0.01–0.05 μg/L) and good repeatabilities (4.0–5.8% for one fiber, 2.9–8.7% for fiber-to-fiber). Compared with commercial counterparts, the OMC fiber exhibits improved extraction efficiency for benzene series and PAHs. - Highlights: • Ordered mesoporous carbon film supported on graphite fiber was first reported as solid-phase microextraction coating. • The strategy for the film preparation was combined dip-coating technology with evaporation-induced self-assembly approach. • The obtained fiber showed enhanced thermal stability and organic solvents resistance. • The

  10. Thermal MEMS actuator operation in aqueous media/seawater: Performance enhancement through atomic layer deposition post processing of PolyMUMPs devices

    Energy Technology Data Exchange (ETDEWEB)

    Warnat, Stephan, E-mail: stephan.warnat@dal.ca; Forbrigger, Cameron; Hubbard, Ted [Mechanical Engineering, Dalhousie University, Halifax, Nova Scotia B3J 2X4 (Canada); Bertuch, Adam; Sundaram, Ganesh [Ultratech Inc., Waltham, Massachusetts 02453 (United States)

    2015-01-15

    A method to enhance thermal microelectromechanical systems (MEMS) actuators in aqueous media by using dielectric encapsulation layers is presented. Aqueous media reduces the available mechanical energy of the thermal actuator through an electrical short between actuator structures. Al{sub 2}O{sub 3} and TiO{sub 2} laminates with various thicknesses were deposited on packaged PolyMUMPs devices to electrically separate the actuator from the aqueous media. Atomic layer deposition was used to form an encapsulation layer around released MEMS structures and the package. The enhancement was assessed by the increase of the elastic energy, which is proportional to the mechanical stiffness of the actuator and the displacement squared. The mechanical stiffness of the encapsulated actuators compared with the noncoated actuators was increased by factors ranging from 1.45 (for 45 nm Al{sub 2}O{sub 3} + 20 nm TiO{sub 2}) to 1.87 (for 90 nm Al{sub 2}O{sub 3} + 40 nm TiO{sub 2}). Displacement measurements were made for all laminate combinations in filtered tap water and seawater by using FFT based displacement measurement technique with a repeatability of ∼10 nm. For all laminate structures, the elastic energy increased and enhanced the actuator performance: In seawater, the mechanical output energy increased by factors ranging from 5 (for 90 nm Al{sub 2}O{sub 3}) to 11 (for 90 nm Al{sub 2}O{sub 3} + 40 nm TiO{sub 2}). The authors also measured the long-term actuator stability/reliability in seawater. Samples were stored for 29 days in seawater and tested for 17 days in seawater. Laminates with TiO{sub 2} layers allowed constant operation over the entire measurement period.

  11. Comparative Studies on Conventional and Ultrasound-Assisted Synthesis of Novel Homoallylic Alcohol Derivatives Linked to Sulfonyl Dibenzene Moiety in Aqueous Media

    Directory of Open Access Journals (Sweden)

    Mohamed F. Mady

    2013-01-01

    Full Text Available Novel homoallylic alcohols incorporating sulfone moieties were synthesized by the treatment of different carbonyl compounds with allylic bromides in aqueous media via sonochemical Barbier-type reaction conditions. Sulfonation of α-bromoketones with sodium benzenesulfinate in presence of CuI/2,6-lutidine rapidly gave β-keto-sulfones in good yields. In general, ultrasound irradiation offered the advantages of high yields, short reaction times, and simplicity compared to the conventional methods. The structures of all the compounds were confirmed by analytical and spectral data.

  12. Effect of Porous Media and Fluid Properties on Dense Non-Aqueous Phase Liquid Migration and Dilution Mass Flux

    National Research Council Canada - National Science Library

    Totten, Christian T

    2005-01-01

    .... Media grain size and NAPL wettability were varied for relative comparisons. Fluid properties including density differential and interfacial tension between NAPL and water were varied for relative comparisons...

  13. Absorption mechanisms for cationic and anionic mineral species on ferric iron polymer hydroxides and oxidation products of ferrous iron in aqueous media

    International Nuclear Information System (INIS)

    Gandon, Remi

    1982-01-01

    Adsorbents obtained by hydrolysing the Fe 3+ , 6H 2 O ion are made of polymers with aquo (H 2 O), hydroxo (-OH...) and oxo (...O...) ligands. Radioactive tracers reveal the importance of chemical mechanisms in adsorption phenomena on ferric oxide in aqueous media. Zn 2+ , Co 2+ and Mn 2+ cations are exchanged with hydrogen from hydroxo groups. CrO 4 2- , SeO 3 2- and Sb(OH) 6 - anions form covalent associations in place of iron ligands. The adsorption of hydrolyzed ions results in strong oxygen bridge bonds. In fresh water, Co and Mn participate alone in physical electrostatic adsorption. Iron II oxidation products generate chemical adsorptions. Zn 2+ and Sb(OH) 6 - associate with ferric hydroxides from oxidized Fe 2+ . 60 Co, 54 Mn and 51 Cr form covalent associations between unpaired 3d iron electrons and the adsorbed element. This process is not predominant with selenium IV or VI reduced to the metallic state or fixed on ferric hydroxide in the selenite form. These conclusions can be applied to pollutant analysis and to water purification and contribute to our understanding of the role of iron in the distribution of oligo-elements in aqueous media. (author) [fr

  14. Risks of using membrane filtration for trace metal analysis and assessing the dissolved metal fraction of aqueous media - A study on zinc, copper and nickel

    International Nuclear Information System (INIS)

    Hedberg, Yolanda; Herting, Gunilla; Wallinder, Inger Odnevall

    2011-01-01

    Membrane filtration is commonly performed for solid-liquid separation of aqueous solutions prior to trace metal analysis and when assessing 'dissolved' metal fractions. Potential artifacts induced by filtration such as contamination and/or adsorption of metals within the membrane have been investigated for different membrane materials, metals, applied pressures and pre-cleaning steps. Measurements have been conducted on aqueous solutions including well-defined metal standards, ultrapure water, and on runoff water from corroded samples. Filtration using both non-cleaned and pre-cleaned filters revealed contamination and adsorption effects, in particular pronounced for zinc, evident for copper but non-significant for nickel. The results clearly show these artifacts to be non-systematic both for non-cleaned and pre-cleaned membranes. The applied pressure was of minor importance. Measurements of the labile fraction by means of stripping voltammetry clearly elucidate that membrane filtration followed by total metal analysis cannot accurately assess the labile or the dissolved metal fraction. - Highlights: → Membrane filtration for trace metal analysis can introduce significant artifacts. → The dissolved metal fraction cannot be assessed by membrane filtration. → Non-specified filtration procedures are inadequate for scientific studies. → Artifacts caused by membrane filtration need to be addressed by regulators. - Membrane filtration cannot be used to assess the dissolved metal fraction of aqueous media and needs to be defined in detail in standard tests.

  15. Development of a pH-responsive imprinted polymer for diclofenac and study of its binding properties in organic and aqueous media.

    Science.gov (United States)

    Mohajeri, Seyed Ahmad; Malaekeh-Nikouei, Bizhan; Sadegh, Hasan

    2012-05-01

    Three different molecularly imprinted polymers (MIPs) for drug delivery of diclofenac in gastrointestinal tract were synthesized employing bulk polymerization method and their binding and release properties were studied in different pH values. Methacrylic acid (MAA), methacrylamide (MAAM) and 4-vinyl pyridine (4VP) were tested as functional monomers and ethylene glycole dimethacrylate (EDMA) was used as a cross-linker monomer in polymeric feed. Binding properties and imprinting factor (IF) of MIPs were studied in comparison with their non-imprinted ones (Blank) in organic and aqueous media. Diclofenac release in aqueous solvents at pH values of 1.5, 6.0 and 8.0, simulating gastrointestinal fluids, were also studied. The results indicated the specific binding of diclofenac to imprinted polymers. Duo to the stronger non-specific bounds in aqueous solutions, IF values decreased in water compared to acetonitrile as an organic medium. Our results proved that all polymers represented pH-responsive diclofenac delivery at above conditions. The data showed that imprinted polymer, prepared by MAA had superior properties, in comparison with other polymers, for minimum release (14%) of drug in gastric acid and maximum release (90%) in basic condition. The results indicated that diclofenac imprinted polymer could be used as a pH-responsive matrix in preparation of a new drug delivery system for diclofenac.

  16. On the influence of hydronium and hydroxide ion diffusion on the hydrogen and oxygen evolution reactions in aqueous media

    DEFF Research Database (Denmark)

    Wiberg, Gustav Karl Henrik; Arenz, Matthias

    2015-01-01

    We present a study concerning the influence of the diffusion of H+ and OH- ions on the hydrogen and oxygen evolution reactions (HER and OER) in aqueous electrolyte solutions. Using a rotating disk electrode (RDE), it is shown that at certain conditions the observed current, i.e., the reaction rate...

  17. Fluorescence-based detection of nitric oxide in aqueous and methanol media using a copper(II) complex.

    Science.gov (United States)

    Mondal, Biplab; Kumar, Pankaj; Ghosh, Pokhraj; Kalita, Apurba

    2011-03-14

    The quenched fluorescent intensity of a copper(II) complex, 1, of a fluorescent ligand, in degassed methanol or aqueous (buffered at pH 7.2) solution, was found to reappear on exposure to nitric oxide. Thus, it can function as a fluorescence based nitric oxide sensor. It has been found that the present complex can be used to sense nanomolar quantities of nitric oxide in both methanol and pH 7.2 buffered-water medium.

  18. Solubility behavior of narcotic analgesics in aqueous media: solubilities and dissociation constants of morphine, fentanyl, and sufentanil.

    Science.gov (United States)

    Roy, S D; Flynn, G L

    1989-02-01

    The pH dependence of the aqueous solubility of morphine, fentanyl, and sufentanil was investigated at 35 degrees C. Dissociation constants and corresponding pKa' values of the drugs were obtained from measured free-base solubilities (determined at high pH's) and the concentrations of saturated solutions at intermediate pH's. Morphine, fentanyl, and sufentanil exhibited pKa' values of 8.08, 8.99, and 8.51, respectively. Over the pH range of 5 to 12.5 the apparent solubilities are determined by the intrinsic solubility of the free base plus the concentration of ionized drug necessary to satisfy the dissociation equilibrium at a given pH. Consequently, the drug concentrations of saturated aqueous solutions fall off precipitously as the pH is raised and ionization is suppressed. Further, at low pH's the aqueous solubility of morphine increased in a linear fashion with increases in the molar strength of citric acid which was added to acidify the medium, suggesting the formation of a soluble morphine-citrate complex.

  19. Sorption behaviour of uranium and thorium on hydrous tin oxide from aqueous and mixed-solvent HNO3 media

    International Nuclear Information System (INIS)

    Misak, N.Z.; Salama, H.N.; El-Naggar, I.M.

    1983-01-01

    In aqueous nitric acid, uranyl and thorium ions seem to be sorbed on hydrous tin oxide mainly by a cation exchange mechanism. In 10 - 3 M aqueous solutions, the hydrous oxide prefers thorium to uranium at the relative low pH values, while the reverse is true at the higher pH values. The exchange of uranium is particle diffusion controlled while that of thorium is chemically controlled, and the isotherms point to the presence of different-energy sites in the hydrous oxide. Except for the solutions containing 80% of methanol, ethanol, or acetone, cation exchange is probably still the main mechanism of sorption of uranium. Anionic sorption of thorium seems to occur in all the mixed-solvent solutions and is perhaps the main mechanism in 80% ethanol. The equilibrium distribution coefficient K sub (d) increases almost in all cases with organic solvent content, probably due to dehydration of sorbed ions and to increasing superposition on anionic sorption. Unlike the aqueous medium, large U/Th separation factors are achieved in many of the mixed-solvent solutions and separation schemes are suggested. (Authors)

  20. Solvent extraction of Zn(II) from aqueous sulphate media by di(2-ethylhexyl) phosphoric acid in kerosene

    International Nuclear Information System (INIS)

    Begum, D.A.; Alauddin, M.; Rahman, M.S.

    2009-01-01

    The extraction equilibrium studies of Zn(II) from sulphate medium by di(2-ethylhexyl) phosphoric acid (D2EHPA, H/sub 2/A/sub 2/) in kerosene revealed that the distribution ratio (D) decreased with the increase of initial (Zn(A(II) in the aqueous phase and increased with the increase of equilibrium pH and extractant concentration. The equilibration is reached within 2 min. The species extracted into the organic phase is thought to be ZnA2, HA. The pH and extractant dependencies were about 2 and 1.67, respectively. The distribution ratio decreased with the increase in sulphate ion concentration in the aqueous phase. The extraction equilibrium reaction is suggested as Zn/sup 2+/ /sub aq/ +1.5 (H/sub 2/A/sub 2/)org - (ZnA/sub 2/, HA)org +2H/sup +/ /sub aq/. The extraction equilibrium constant (kex) for the above reaction was calculated to be 10-2.26. The extraction process was endothermic in nature having positive DH value of 16.27 kJ/mol. The loading of D2EHPA by Zn(II) is about 4.50 g of Zn(II) by 0.10 M D2EHPA. Possible reaction mechanism has been suggested based on distribution data, extractant concentration and equilibrium pH of the aqueous phase. (author)

  1. On the importance of aqueous diffusion and electrostatic interactions in advection-dominated transport in saturated porous media

    DEFF Research Database (Denmark)

    Rolle, Massimo

    2015-01-01

    to multicomponent ionic dispersion: the dispersive fluxes of the different ions are cross-coupled due to the effects of Coulombic interactions. Such effects are illustrated in flow-through experiments in saturated porous media. Simple strong electrolytes were selected as tracers and their transport was studied...... under different advection-dominated conditions and in homogeneous and heterogeneous porous media. The interpretation of the experimental results requires a multicomponent modeling approach with an accurate description of local hydrodynamic dispersion and explicitly accounting for the cross-coupling...

  2. Near-infrared chemodosimetric probes based on heptamethine cyanine dyes for the “naked-eye” detection of cyanide in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Dali [College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province (China); Liu, Yijiang, E-mail: liuyijiang84@iccas.ac.cn [College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province (China); Li, Mengnan [State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Chen, Hongbiao, E-mail: chhb606@163.com [College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province (China); Li, Huaming [College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province (China)

    2017-05-15

    Two simple chemodosimetric probes (P1 and P2) based on heptamethine cyanine dyes have been synthesized for highly sensitive and selective detection of cyanide anions (CN{sup −}) in aqueous media. The probes with an immobilized indolium salt as the specifically nucleophilic addition reaction site for CN{sup −} exhibit absorption bands in the near-infrared (NIR) region (650–850 nm). Upon the addition of CN{sup −}, the probes display a blue-shifted spectrum and result in apparent color change from green to brilliant yellow that can be easily observed by the naked eye even in the presence of other interfering anions such as F{sup −}, AcO{sup −}, Br{sup −}, NO{sub 2}{sup −}, Cl{sup −}, SO{sub 4}{sup 2−} and I{sup −}. There are good linear relationships between the fluorescence intensity of the probes and CN{sup −} concentrations, and the detection limits for P1 and P2 are estimated to be 0.017 μM and 0.2 μM, respectively. The sensing mechanism of the nucleophilic addition is confirmed by {sup 1}H NMR and mass spectroscopic analysis. In addition, the probe P2 is employed for cell imaging and the detection of CN{sup −} in living cells L929 is successfully realized. - Graphical abstract: Simple chemodosimetric probes based on heptamethine cyanine dye were synthesized and applied to detect CN{sup −} in aqueous media with colorimetric and fluorescent dual channel recognition.

  3. Coupled enzyme reactions performed in heterogeneous reaction media: experiments and modeling for glucose oxidase and horseradish peroxidase in a PEG/citrate aqueous two-phase system.

    Science.gov (United States)

    Aumiller, William M; Davis, Bradley W; Hashemian, Negar; Maranas, Costas; Armaou, Antonios; Keating, Christine D

    2014-03-06

    The intracellular environment in which biological reactions occur is crowded with macromolecules and subdivided into microenvironments that differ in both physical properties and chemical composition. The work described here combines experimental and computational model systems to help understand the consequences of this heterogeneous reaction media on the outcome of coupled enzyme reactions. Our experimental model system for solution heterogeneity is a biphasic polyethylene glycol (PEG)/sodium citrate aqueous mixture that provides coexisting PEG-rich and citrate-rich phases. Reaction kinetics for the coupled enzyme reaction between glucose oxidase (GOX) and horseradish peroxidase (HRP) were measured in the PEG/citrate aqueous two-phase system (ATPS). Enzyme kinetics differed between the two phases, particularly for the HRP. Both enzymes, as well as the substrates glucose and H2O2, partitioned to the citrate-rich phase; however, the Amplex Red substrate necessary to complete the sequential reaction partitioned strongly to the PEG-rich phase. Reactions in ATPS were quantitatively described by a mathematical model that incorporated measured partitioning and kinetic parameters. The model was then extended to new reaction conditions, i.e., higher enzyme concentration. Both experimental and computational results suggest mass transfer across the interface is vital to maintain the observed rate of product formation, which may be a means of metabolic regulation in vivo. Although outcomes for a specific system will depend on the particulars of the enzyme reactions and the microenvironments, this work demonstrates how coupled enzymatic reactions in complex, heterogeneous media can be understood in terms of a mathematical model.

  4. investigations on the use of surfactants for the separation of some organics and metal ions from aqueous media

    International Nuclear Information System (INIS)

    Mahmoud, M.R.

    2007-01-01

    the copreceipitate flotation of 137 Cs from dilute aqueous solutions and simulated radioactive wastes using nickel hexacyanoferrate(11) as a co precipitant and sodium lauryl sulfate, cetyltrimethylammonium bromide,or dodecyl amine as a collect or was extensively investigated to establish the best conditions for cesium removal. under the optimal conditions, removals exceeding 99% and decontamination factors higher than 110 could be achieved for the radioactive waste simulant. the results are compared with those obtained by conventional removal methods and are discussed in terms of the collector properties and the electrical state of the co precipitate

  5. SINTESIS NANOPARTIKEL PERAK MENGGUNAKAN METODE POLIOL DENGAN AGEN STABILISATOR POLIVINILALKOHOL (PVA

    Directory of Open Access Journals (Sweden)

    DOB Apriandanu

    2014-06-01

    Full Text Available Abstrak __________________________________________________________________________________________ Nanopartikel perak merupakan produk berbasis nanoteknologi yang sedang berkembang saat ini dan dapat diaplikasikan sebagai katalis dan detektor sensor optik. Faktor yang dapat mempengaruhi ukuran nanopartikel adalah konsentrasi garam dan agen pereduksi. Nanopartikel perak bersifat tidak stabil. Oleh karena itu, perlu adanya penambahan polivinil alkohol sebagai agen stabilisator dalam sintesis nanopartikel perak. Tujuan penelitian ini adalah untuk mengetahui pengaruh rasio mol reduktor EG/Ag+ dan % PVA (b/v dalam sintesis nanopartikel perak terhadap karakteristik produk yang dihasilkan. Nanopartikel perak disintesis dengan metode poliol yaitu melarutkan AgNO3 ke dalam etilen glikol sebagai reduktor dan polivinilalkohol (PVA sebagai stabilisator. Karakterisasi dilakukan menggunakan Spek-trofotometer UV-Vis dan TEM (Transmission Electron Microscope. Analisis terhadap spektra UV-Vis menunjukkan bahwa nanopartikel yang relatif stabil pada pengukuran panjang gelombang maksimum 417 hingga 418 nm adalah nanopartikel yang disintesis menggunakan PVA 3%. Karakterisasi dengan TEM menunjukkan nanopartikel perak yang disintesis berdasarkan rasio mol etilen glikol terhadap Ag+ 50:1 memiliki ukuran terkecil dengan kisaran 10,15–27,56 nm dengan struktur kristal face centered cubic (FCC. Semakin tinggi rasio mol EG /Ag+ dalam sintesis nanopartikel perak, semakin tinggi pula peningkatan absorbansinya.   Abstract __________________________________________________________________________________________ Silver nanoparticles are nanotechnology based product which can be applied as a catalyst and optic sensor detector. The factors that can effect on nanoparticle size are salt concentration and reductor agent. Silver nanoparticles are unstable material, so polyvinylalcohol needs to be added  as a stabilizer agent in their synthesis. The aims of this research are to

  6. Effectively designed molecularly imprinted polymers for selective isolation of the antidiabetic drug metformin and its transformation product guanylurea from aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Kyzas, George Z.; Nanaki, Stavroula G. [Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Koltsakidou, Anastasia; Papageorgiou, Myrsini; Kechagia, Maria [Laboratory of Environmental Pollution Control, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Bikiaris, Dimitrios N. [Laboratory of Polymer Chemistry and Technology, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece); Lambropoulou, Dimitra A., E-mail: dlambro@chem.auth.gr [Laboratory of Environmental Pollution Control, Department of Chemistry, Aristotle University of Thessaloniki, GR-541 24 Thessaloniki (Greece)

    2015-03-25

    Highlights: • Preparation of novel MIPs with remarkable recognition properties. • Selective isolation and removal of metformin and guanylurea from aqueous media. • Detailed adsorbent characterization and adsorption studies. • Successful application of synthesized MIPs as dispersive SPE sorbents. • Estimation of expanded uncertainty following a bottom-up approach. - Abstract: In the present study, two novel molecularly imprinted polymers (MIPs) with remarkable recognition properties for metformin and its transformation product, guanylurea, have been prepared for their selective, enrichment, isolation and removal from aqueous media. The prepared adsorbents were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and swelling experiments. The performance of the prepared MIPs was evaluated by various parameters including the influence of pH, contact time, temperature and initial compound concentration. The effects on the adsorption behavior of the removal process parameters were studied and the equilibrium data were fitted by the Langmuir and Freundlich models. Due to the imprinting effect, adsorption performance of MIPs was always superior to its corresponding NIP (non-imprinted polymer), with maximum adsorption capacity ∼80 mg g{sup −1} for both MIPs. Stability and reusability of the MIPs up to the 5th cycle meant that they could be applied repeatedly without losing substantial removal ability. In the next step, the prepared MIP nanoparticles were evaluated as sorbents in a dispersive solid phase extraction (D-SPE) configuration for selective enrichment and determination of metformin and guanylurea in different aqueous matrices. Under the working extraction conditions, the D-SPE method showed good linearity in the range of 50–1000 ng L{sup −1}, repeatability of the extractions (RSD 2.1–5.1%, n = 3), and low limits of detection (1.5–3.4 ng L{sup −1}). The expanded uncertainty of the data obtained

  7. Application of Eh-pH diagram for room temperature precipitation of zinc stannate microcubes in an aqueous media

    International Nuclear Information System (INIS)

    Al-Hinai, Ashraf T.; Al-Hinai, Muna H.; Dutta, Joydeep

    2014-01-01

    Graphical abstract: - Highlights: • One pot aqueous synthesis of zinc stannate (ZnSnO 3 ) particles at low temperature. • Synthesis designed with the assistance of potential-pH diagram. • ZnSnO 3 estimated to be stable between pH 8 and 12 was used for synthesis of the particles. • ZnSnO 3 ·3H 2 O were formed during the precipitation of zinc stannate. - Abstract: Potential-pH diagram assisted-design for controlled precipitation is an attractive method to obtain engineered binary and ternary oxide particles. Aqueous synthesis conditions of zinc stannate (ZnSnO 3 ) particles at low temperature were formulated with the assistance of potential-pH diagram. The pH of a solution containing stoichiometric amounts of Zn 2+ and Sn 4+ was controlled for the precipitation in a one pot synthesis step at room temperature (25 °C). The effect of the concentration of the reactants on the particle size was studied by varying the concentration of the precursor (Zn 2+ + Sn 4+ ) solution. Scanning electron micrographs show that the particles are monodispersed micron sized cubes formed by the self-organization of nano-sized crystallites. The obtained microcubes characterized by X-ray Diffraction and thermo gravimetric analysis (TGA) show that the particles are in ZnSnO 3 ·3H 2 O form

  8. Recovery of metals from simulant spent lithium-ion battery as organophosphonate coordination polymers in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Perez, Emilie; Andre, Marie-Laure; Navarro Amador, Ricardo [ICSM, Institut de Chimie Séparative de Marcoule, UMR 5257, CEA/CNRS/ENSCM/UM, Bât 426, BP 17171, 30207 Bagnols-sur-Cèze cedex (France); Hyvrard, François; Borrini, Julien [SARPI VEOLIA, Direction Technique et Innovations, Zone portuaire de Limay-Porcheville, 427 route du Hazay, 78520 Limay (France); Carboni, Michaël, E-mail: michael.carboni@cea.fr [ICSM, Institut de Chimie Séparative de Marcoule, UMR 5257, CEA/CNRS/ENSCM/UM, Bât 426, BP 17171, 30207 Bagnols-sur-Cèze cedex (France); Meyer, Daniel [ICSM, Institut de Chimie Séparative de Marcoule, UMR 5257, CEA/CNRS/ENSCM/UM, Bât 426, BP 17171, 30207 Bagnols-sur-Cèze cedex (France)

    2016-11-05

    Highlights: • Original waste disposal strategies for battery. • Precipitation of metals as coordination polymers. • Organo-phosphonate coordination polymers. • Selective extraction of manganese or co-precipitation of manganese/cobalt. • The recycling process give a promising application on any waste solution. - Abstract: An innovative approach is proposed for the recycling of metals from a simulant lithium-ion battery (LIBs) waste aqueous solution. Phosphonate organic linkers are introduced as precipitating agents to selectively react with the metals to form coordination polymers from an aqueous solution containing Ni, Mn and Co in a hydrothermal process. The supernatant is analyzed by ICP-AES to quantify the efficiency and the selectivity of the precipitation and the materials are characterized by Scanning Electron Microscopy (SEM), Powder X-Ray Diffraction (PXRD), Thermogravimetric Analyses (TGA) and nitrogen gas sorption (BET). Conditions have been achieved to selectively precipitate Manganese or Manganese/Cobalt from this solution with a high efficiency. This work describes a novel method to obtain potentially valuable coordination polymers from a waste metal solution that can be generalized on any waste solution.

  9. Solid-phase extraction element based on epoxy polymer monolith for determination of polar organic compounds in aqueous media.

    Science.gov (United States)

    Takahashi, Tadashi; Odagiri, Kayo; Watanabe, Atsushi; Watanabe, Chuichi; Kubo, Takuya; Hosoya, Ken

    2011-10-01

    A solid-phase extraction element based on epoxy polymer monolith was fabricated for sorptive enrichment of polar compounds from liquid and gaseous samples. After ultrasonication of the element in an aqueous solution for a given period of time, the thermal desorption (TD) using a pyrolyzer with gas chromatography/mass spectrometry (GC/MS), in which TD temperature was programmed from 50 to 250 °C for the analytes absorbed in the element, was used to evaluate the element for basic extraction performance using the aqueous standard mixtures consisting of compounds having varied polarities such as hexanol, isoamyl acetate, linalool, furfural and decanoic acid, in concentrations ranging from 10 μg/L to 1 mg/L. Excellent linear relationships were observed for all compounds in the standard mixture, except decanoic acid. In the extraction of beverages such as red wine, the extraction element showed stronger adsorption characteristics for polar compounds such as alcohols and acids than a non-polar polydimethylsiloxane-based element. This feature is derived from the main polymer structure along with hydroxyl and amino groups present in the epoxy-based monolith polymer matrix. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Effects of self-aggregation on the hydration of an amphiphilic antidepressant drug in different aqueous media

    International Nuclear Information System (INIS)

    Taboada, Pablo; Gutierrez-Pichel, Manuel; Mosquera, Victor

    2004-01-01

    Apparent molal volumes and adiabatic compressibilities of aqueous solutions of the amphiphilic antidepressant drug clomipramine hydrochloride have been determined from density and ultrasound velocity measurements in the temperature range 288.15-313.15 K in buffered aqueous solution of pH 3.0 and 5.5. Critical concentrations of aggregation of this drug were obtained from inflections on the plots of the sound velocity against drug concentration. Apparent molal adiabatic compressibilities of the aggregates formed by the drug, calculated by combining the ultrasound velocity and density data, were typical of those for a stacked aggregate. From the temperature dependence of the critical concentration and using the mass action model combined with the Phillips definition of the critical concentration the thermodynamic standard quantities: free Gibbs energy, enthalpy and entropy of aggregate formation were calculated. The critical concentration and energy involved in the aggregation process of this drug have been also evaluated experimentally using isothermal titration calorimetry at 298.15 K. The solvent-drug interactions have been discussed from compressibility and calorimetry data

  11. Kinetics and mechanism of the oxidation of uranium (IV) by hypochlorous acid in aqueous acidic perchlorate media

    International Nuclear Information System (INIS)

    Silverman, R.A.; Gordon, G.

    1976-01-01

    The oxidation of uranium(IV) by hypochlorous acid has been studied in aqueous sodium perchlorate--perchloric acid solutions. The reaction U 4 + + 2HOCl = UO 2 2 + + Cl 2 (aq) + 2H + proceeds appropriate to the rate law --d[U(IV)]/dt = k 0 . [U 4+ ][HOCl][H + ] -1 . At 25 0 and 3 M ionic strength, k 0 is 1.08 +- 0.07 sec -1 . Over the 1--25 0 temperature range, ΔH 2+ is 18.4 +- 0.1 kcal mole -1 , and ΔS 2+ is 3.1 +- 0.4 eu. The inverse hydrogen ion dependence of the rate law is explained by a rapid preequilibrium, in which a proton is lost from one of the reactants. A uranyl-like activated complex, [H 2 UO 2 Cl 3+ ] 2+ , is suggested, with one proton likely to be residing on each oxygen atom. Evidence is presented that the mechanism involves a two-electron transfer, with the intermediate chloride ion rapidly reacting with hypochlorous acid to form chlorine. The uranium(IV)-hypochlorous acid reaction plays an important role in the oxidation of uranium(IV) by aqueous chlorine solutions. The magnitude of this role was seriously underestimated by previous investigators

  12. Generalized corrosion of nickel base alloys in high temperature aqueous media: a contribution to the comprehension of the mechanisms

    International Nuclear Information System (INIS)

    Marchetti-Sillans, L.

    2007-11-01

    In France, nickel base alloys, such as alloy 600 and alloy 690, are the materials constituting steam generators (SG) tubes of pressurized water reactors (PWR). The generalized corrosion resulting from the interaction between these alloys and the PWR primary media leads, on the one hand, to the formation of a thin protective oxide scale (∼ 10 nm), and on the other hand, to the release of cations in the primary circuit, which entails an increase of the global radioactivity of this circuit. The goal of this work is to supply some new comprehension elements about nickel base alloys corrosion phenomena in PWR primary media, taking up with underlining the effects of metallurgical and physico-chemical parameters on the nature and the growth mechanisms of the protective oxide scale. In this context, the passive film formed during the exposition of alloys 600, 690 and Ni-30Cr, in conditions simulating the PWR primary media, has been analyzed by a set of characterization techniques (SEM, TEM, PEC and MPEC, XPS). The coupling of these methods leads to a fine description, in terms of nature and structure, of the multilayered oxide forming during the exposition of nickel base alloys in primary media. Thus, the protective part of the oxide scale is composed of a continuous layer of iron and nickel mixed chromite, and Cr 2 O 3 nodules dispersed at the alloy / mixed chromite interface. The study of protective scale growth mechanisms by tracers and markers experiments reveals that the formation of the mixed chromite is the consequence of an anionic mechanism, resulting from short circuits like grain boundaries diffusion. Besides, the impact of alloy surface defects has also been studied, underlining a double effect of this parameter, which influences the short circuits diffusion density in oxide and the formation rate of Cr 2 O 3 nodules. The sum of these results leads to suggest a description of the nickel base alloys corrosion mechanisms in PWR primary media and to tackle some

  13. Synthesis of new annulated pyrano[2,3-d]pyrimidine derivatives using organo catalyst (DABCO in aqueous media

    Directory of Open Access Journals (Sweden)

    Ajmal R. Bhat

    2017-01-01

    Full Text Available A selective method for the synthesis of annulated pyrano[2,3-d]pyrimidines has been developed. It was shown that base catalysis is more efficient in this reaction, rather than acid catalysis as it is believed that 1,4-diazabicyclo[2.2.2]octane (DABCO is N-type base catalyst used for the synthesis of pyrano[2,3-d]pyramidine derivatives via one-pot three component condensation reactions of various aromatic aldehydes, active methylene compounds and barbituric acid in aqueous ethanol carried at normal temperature. The potential application of DABCO in organic synthesis increasing rapidly because of its reaction simplicity, less pollution, and minimum reaction time, high yields of the biological active products, uses less toxic solvents and low cost chemicals.

  14. Sorption studies of Sn(II) and Zr(IV) on pistachio shell from different aqueous media

    International Nuclear Information System (INIS)

    Abdel-Fattah, A.A.; EI-Khouly, S.H.

    2007-01-01

    Sorption of Sn(lI) and Zr(IV) on pistachio shell as a solid sorbent material of particle sizes (0.5-1 mm) has been investigated from HNO 3 , H CI, HBr, NaNO 3 , Na CI, KBr and KI aqueous solutions. Before use, this substance was subjected to characterization tools including surface area, thermogravimetric analysis, infrared spectroscopy and X-R diffraction. The effect of contact time, weight of the resin, acid and salt concentrations and equilibrium ph on K d values have been studied. Sorption of both elements was found to verify Freundlich adsorption isotherm. The effect of temperature on thc sorption processes have been investigated and the thermodynamic functions δG, δH and δS have been determined. Adsorption processes have been discussed in the light of the obtained results

  15. Sorption studies of Sn(II) and Zr(IV) on pistachio shell from different aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Fattah, A A [Nuclear Chemistry Dept., Atomic Energy Authority, Cairo (Egypt); EI-Khouly, S H [Radioisotopes and Generators Dept., Radioisotopes Prod. Division, Hot Lahoratories Center, Atomic Energy Authority, Cairo (Egypt)

    2007-07-01

    Sorption of Sn(lI) and Zr(IV) on pistachio shell as a solid sorbent material of particle sizes (0.5-1 mm) has been investigated from HNO{sub 3}, H CI, HBr, NaNO{sub 3}, Na CI, KBr and KI aqueous solutions. Before use, this substance was subjected to characterization tools including surface area, thermogravimetric analysis, infrared spectroscopy and X-R diffraction. The effect of contact time, weight of the resin, acid and salt concentrations and equilibrium ph on K{sub d} values have been studied. Sorption of both elements was found to verify Freundlich adsorption isotherm. The effect of temperature on thc sorption processes have been investigated and the thermodynamic functions {delta}G, {delta}H and {delta}S have been determined. Adsorption processes have been discussed in the light of the obtained results.

  16. Sintesis dan Karakterisasi Polianilina Doping Asam Klorida dengan Metode Interfasial

    Directory of Open Access Journals (Sweden)

    Iman Rahayu

    2016-08-01

    Full Text Available The growing interest in nanostructured conducting polymers is caused by expanding area of their practical application. Conducting polymers can be used in new electronic devices (transistors, displays, sensors, energy storage and memory cells, materials for shielding electromagnetic irradiation, inhibition of corrosion, membrane constructing, catalysis and medicine. The studies of polyaniline (PANI and other conducting polymers have shown that they possess semiconducting properties. Due to its high stability and unique complex of properties, PANI was the first among conducting polymers to be used in practice as an electrode material for batteries, as a corrosion inhibitor and detecting material for sensors. PANI without dopant material possesses controlled conductivity 10-10 S∙cm-1. PANI was synthesized by the interfacial method by oxidation of aniline with ammonium peroxydisulfate (APS as an oxidant in an immiscible organic/aqueous biphasic system, with hydrochloric acid as dopant. An organic phase contained aniline dissolved in toluene, while the oxidant was dissolved in acid. The produced PANIs have conductivities in the range 0.03-0.07 S.cm−1. Their nanofiber morphology was confirmed by scanning electron microscopy (SEM. Molecular structure of synthesized PANIs was investigated by FTIR Spectroscopy. DOI :http://dx.doi.org/10.15408/jkv.v0i0.3143

  17. Pengaruh Advance Organizer Berbasis Proyek Terhadap Kemampuan Analisis – Sintesis Siswa

    Directory of Open Access Journals (Sweden)

    Tasiwan -

    2014-01-01

    Full Text Available Penelitian ini dilakukan untuk mengetahui pengaruh model pengatur kemajuan (advance organizer berbasis proyek terhadap kemampuan analisis – sintesis siswa pada konsep Energi. Sebelum pembelajaran, diberikan tugas proyek pada siswa untuk merealisasikan bel listrik sederhana, rangkaian arus seri - paralel, dan tuas. Produk proyek digunakan sebagai advance organizer dalam pembelajaran di kelas. Penguatan kognitif dilakukan melalui diskusi kelompok dan pembuatan peta konsep, ekspositori guru di kelas, dan kegiatan eksperimen laboratorium. Data diambil melalui pretest, post test, observasi partisipatif pembelajaran oleh dua orang observer, penilaian produk, peta konsep dan laporan kegiatan eksperimen. Teknik analisis data meliputi uji prasyarat data dan uji hipotesis Hasil penelitian menunjukkan bahwa siswa mengalami peningkatan kemampuan analisis – sintesis dalam aspek menguraikan, mengkategorikan, mengidentifikasi, merumuskan pernyataan, merekonstruksi, menentukan konsep, dan menganalisis konsep dengan rata – rata peningkatan delta skor sebesar 54,46 %, uji t sebesar 6,4, dan skala gain sebesar 0,3. This study was conducted to determine the effect of project-based advance organizer model on student’s analysis - synthesis ability of the energy concept. Students were given an assignment to realize the project on simple electric bell, the series – parallel circuit, and lever, before learning. The products of project were used as an advanced organizer in the learning activity. Cognitive strengthening was done through group discussions and concept mapping, expository learning in the classroom, and laboratory experiments activities. The data were taken through a pretest, post-test, participant observation study by two observers, product assessment, concept maps and report of experiment activities. Results showed that the students’ analysis - synthesis ability increased in the aspect of describing, categorizing, identifying, statement

  18. A novel method for determining the solubility of small molecules in aqueous media and polymer solvent systems using solution calorimetry.

    Science.gov (United States)

    Fadda, Hala M; Chen, Xin; Aburub, Aktham; Mishra, Dinesh; Pinal, Rodolfo

    2014-07-01

    To explore the application of solution calorimetry for measuring drug solubility in experimentally challenging situations while providing additional information on the physical properties of the solute material. A semi-adiabatic solution calorimeter was used to measure the heat of dissolution of prednisolone and chlorpropamide in aqueous solvents and of griseofulvin and ritonavir in viscous solutions containing polyvinylpyrrolidone and N-ethylpyrrolidone. Dissolution end point was clearly ascertained when heat generation stopped. The heat of solution was a linear function of dissolved mass for all drugs (solution of 9.8 ± 0.8, 28.8 ± 0.6, 45.7 ± 1.6 and 159.8 ± 20.1 J/g were obtained for griseofulvin, ritonavir, prednisolone and chlorpropamide, respectively. Saturation was identifiable by a plateau in the heat signal and the crossing of the two linear segments corresponds to the solubility limit. The solubilities of prednisolone and chlopropamide in water by the calorimetric method were 0.23 and 0.158 mg/mL, respectively, in agreement with the shake-flask/HPLC-UV determined values of 0.212 ± 0.013 and 0.169 ± 0.015 mg/mL, respectively. For the higher solubility and high viscosity systems of griseofulvin and ritonavir in NEP/PVP mixtures, respectively, solubility values of 65 and 594 mg/g, respectively, were obtained. Solution calorimetry offers a reliable method for measuring drug solubility in organic and aqueous solvents. The approach is complementary to the traditional shake-flask method, providing information on the solid properties of the solute. For highly viscous solutions, the calorimetric approach is advantageous.

  19. Photolysis of sulfamethoxypyridazine in various aqueous media: Aerobic biodegradation and identification of photoproducts by LC-UV–MS/MS

    Energy Technology Data Exchange (ETDEWEB)

    Khaleel, Nareman D.H., E-mail: drndahshan@yahoo.com [Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Leuphana University Lüneburg, C13, DE-21335 Lüneburg (Germany); Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Suez Canal University, Ismailia 41522 (Egypt); Mahmoud, Waleed M.M. [Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Leuphana University Lüneburg, C13, DE-21335 Lüneburg (Germany); Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Suez Canal University, Ismailia 41522 (Egypt); Hadad, Ghada M.; Abdel-Salam, Randa A. [Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, Suez Canal University, Ismailia 41522 (Egypt); Kümmerer, Klaus, E-mail: Klaus.Kuemmerer@uni.leuphana.de [Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Leuphana University Lüneburg, C13, DE-21335 Lüneburg (Germany)

    2013-01-15

    Highlights: ► Sulfonamides are one of the most extensively used antibiotics in human and veterinary medicine. ► Sulfamethoxypyridazine (SMP) underwent photodegradation in three different media. ► SMP was not readily biodegradable. ► SMP and some of its degradation products were identified by LC-UV–MS/MS. -- Abstract: Sulfonamides are one of the most frequently used antibiotics worldwide. Therefore, mitigation processes such as abiotic or biotic degradation are of interest. Photodegradation and biodegradation are the potentially significant removal mechanisms for pharmaceuticals in aquatic environments. The photolysis of sulfamethoxypyridazine (SMP) using a medium pressure Hg-lamp was evaluated in three different media: Millipore water pH 6.1 (MW), effluent from sewage treatment plant pH 7.6 (STP), and buffered demineralized water pH 7.4 (BDW). Identification of transformation products (TPs) was performed by LC-UV–MS/MS. The biodegradation of SMP using two tests from the OECD series was studied: Closed Bottle test (OECD 301 D), and Manometric Respirometry test (OECD 301 F). In biodegradation tests, it was found that SMP was not readily biodegradable so it may pose a risk to the environment. The results showed that SMP was removed completely within 128 min of irradiation in the three media, and the degradation rate was different for each investigated type of water. However, dissolved organic carbon (DOC) was not removed in BDW and only little DOC removal was observed in MW and STP, thus indicating the formation of TPs. Analysis by LC-UV–MS/MS revealed new TPs formed. The hydroxylation of SMP represents the main photodegradation pathway.

  20. Photolysis of sulfamethoxypyridazine in various aqueous media: Aerobic biodegradation and identification of photoproducts by LC-UV–MS/MS

    International Nuclear Information System (INIS)

    Khaleel, Nareman D.H.; Mahmoud, Waleed M.M.; Hadad, Ghada M.; Abdel-Salam, Randa A.; Kümmerer, Klaus

    2013-01-01

    Highlights: ► Sulfonamides are one of the most extensively used antibiotics in human and veterinary medicine. ► Sulfamethoxypyridazine (SMP) underwent photodegradation in three different media. ► SMP was not readily biodegradable. ► SMP and some of its degradation products were identified by LC-UV–MS/MS. -- Abstract: Sulfonamides are one of the most frequently used antibiotics worldwide. Therefore, mitigation processes such as abiotic or biotic degradation are of interest. Photodegradation and biodegradation are the potentially significant removal mechanisms for pharmaceuticals in aquatic environments. The photolysis of sulfamethoxypyridazine (SMP) using a medium pressure Hg-lamp was evaluated in three different media: Millipore water pH 6.1 (MW), effluent from sewage treatment plant pH 7.6 (STP), and buffered demineralized water pH 7.4 (BDW). Identification of transformation products (TPs) was performed by LC-UV–MS/MS. The biodegradation of SMP using two tests from the OECD series was studied: Closed Bottle test (OECD 301 D), and Manometric Respirometry test (OECD 301 F). In biodegradation tests, it was found that SMP was not readily biodegradable so it may pose a risk to the environment. The results showed that SMP was removed completely within 128 min of irradiation in the three media, and the degradation rate was different for each investigated type of water. However, dissolved organic carbon (DOC) was not removed in BDW and only little DOC removal was observed in MW and STP, thus indicating the formation of TPs. Analysis by LC-UV–MS/MS revealed new TPs formed. The hydroxylation of SMP represents the main photodegradation pathway

  1. Effects of molybdenum additions on the corrosion resistance of stainless steels in inorganic aqueous solutions and organic media (A review)

    International Nuclear Information System (INIS)

    Charbonnier, J.-C.

    1975-01-01

    The effects of molybdenum additions on the corrosion resistance of austenitic and ferritic stainless steels are reviewed. The following types of corrosion are considered: uniform attack in inorganic and organic acids, pitting and crevice corrosion in chloride media. The survey has been conducted with particular emphasis on the recent works. The different hypotheses which have been suggested in order to clarify the role of the molybdenum additions on the improvement of the corrosion resistance of stainless steels are analyzed and discussed. A synthesis is given [fr

  2. Final report on CCQM-K27.2: Second Subsequent study: determination of ethanol in aqueous media

    Science.gov (United States)

    Schantz, Michele M.; Parris, Reenie M.; May, Willie E.; Rosso, Adriana; Puglisi, Celia; Marques Rodrigues Caixeiro, Janaína; Massiff, Gabriela; Camacho Frías, Evangelina; Pérez Urquiza, Melina; Archer, Marcellé; Visser, M. S.; deVos, Betty-Jayne

    2013-01-01

    Ethanol is important both forensically ('drunk driving' or driving while under the influence, 'DWI', regulations) and commercially (alcoholic beverages). Blood- and breath-alcohol testing can be imposed on individuals operating private vehicles such as cars, boats or snowmobiles, or operators of commercial vehicles like trucks, planes and ships. The various levels of blood alcohol that determine whether these operators are considered legally impaired vary depending on the circumstances and locality. Accurate calibration and validation of instrumentation is critical in areas of forensic testing where quantitative analysis directly affects the outcome of criminal prosecutions, as is the case with the determination of ethanol in blood and breath. Additionally, the accurate assessment of the alcoholic content of beverages is a commercially important commodity. In 2002, the CCQM conducted a key comparison (CCQM-K27) for the determination of ethanol in aqueous matrix with nine participants. A report on this project has been approved by the CCQM and can be found at the BIPM website. CCQM-K27 comprised three samples, one at low mass fraction of ethanol in water (nominal concentration of 0.8 mg/g), one at high level (nominal concentration of 120 mg/g) and one wine matrix (nominal concentration of 81 mg/g). Overall agreement among eight participants using gas chromatography with flame ionization detection (GC-FID), titrimetry, isotope dilution gas chromatography/mass spectrometry (GC-IDMS) and gas chromatography-combustion-isotope ratio mass spectrometry (ID-GC-C-IRMS) was good. The ninth participant used a headspace GC-FID method that had not been validated in an earlier pilot study (CCQM-P35). A follow-on key comparison, CCQM-K27-Subsequent, was initiated in 2003 to accommodate laboratories that had not been ready to benchmark their methods in the original CCQM-K27 study or that wished to benchmark a different method. Four levels of ethanol in water were used in the

  3. Bentonite surface modification and characterization for high selective phosphate adsorption from aqueous media and its application for wastewater treatments

    Directory of Open Access Journals (Sweden)

    S. Yaghoobi-Rahni

    2017-06-01

    Full Text Available Raw and modified bentonite has been used to develop effective sorbents to remove phosphate from aqueous solution. Acid thermoactivation, Rewoquate, Irasoft, calcium, Fe and Al were employed to treat the bentonite. Results show that samples adsorption capacity for phosphate is in the order of, unmodified bentonite = acid thermoactivation < Rewoquate < calcium ≅ Irasoft < Fe < Al ≅ Fe-Al. The phosphate adsorption with Fe-Al-bentonite (FAB modification was more than 99% and the phosphate removal reached the peak value in the initial 30 min. The phosphate adsorption of FAB was pH independent in the range of 2–10. The common coexisting ions in wastewater have no effect on the phosphate adsorption. The phosphate adsorption results were very well fitted in the Freundlich and Langmuir isotherm model and the maximum adsorption capacity was 8.33 mg P/g at pH 6.5 for 1 hour, which was better than similar modified bentonite with low time and Fe-Al consumption. FAB was characterized by scanning electron microscopy, X-ray diffraction, X-ray fluorescence and Fourier transform infrared. Therefore, the results confirm that FAB is a selective phosphate sorbent and environmentally friendly for its potential application for phosphate removal from wastewater.

  4. Sol-gel synthesis of anatase nanopowders for efficient photocatalytic degradation of herbicide Clomazone in aqueous media

    Directory of Open Access Journals (Sweden)

    Golubović Aleksandar

    2017-01-01

    Full Text Available TiO2 nanopowders were produced by sol-gel technique using TiCl4 as a starting material. For the preparation of crystalline anatase with developed surface area, this aqueous solution has been mixed with 0.05 M or 0.07 M (NH42SO4 solution in a temperature-controlled bath. The pH values of the suspension were 7, 8 or 9. According to the x-ray diffraction (XRD analysis the anatase crystallite sizes were about 12 nm, which coincided with the average particle size revealed by scanning electron microscopy (SEM. The Raman scattering measurements have shown the presence of a small amount of highly disordered brookite phase in addition to dominant anatase phase with similar nanostructure in all synthesized powders. BET measurements revealed that all synthesized catalysts were fully mesoporous, except the sample synthesized with 0.07 M (NH42SO4 at pH=9, which had small amount of micropores. The photocatalytic degradation of herbicide Clomazone was carried out for both the pure active substance and as the commercial product (GAMIT 4-EC under UV irradiation. The best photocatalytic efficiency was obtained for the catalyst with the largest specific surface area, confirming this parameter as crucial for enhanced photocatalytic degradation of the pure active substance and commercial product of herbicide Clomazone. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III45018

  5. Multivalent calix[4]arene-based fluorescent sensor for detecting silver ions in aqueous media and physiological environment.

    Science.gov (United States)

    Lotfi, Behzad; Tarlani, Aliakbar; Akbari-Moghaddam, Peyman; Mirza-Aghayan, Maryam; Peyghan, Ali Ahmadi; Muzart, Jacques; Zadmard, Reza

    2017-04-15

    A new derivative of dipodal 1,3-calix[4]arene-based chemosensor (R), which was containing several binding sites have been synthesized and characterized by NMR, IR and LC-MS spectroscopic methods. The selectivity of Rhas been investigated in aqueous methanol, resulting in fluorescence shift and selective recognition of Ag + among 20 various alkali, alkaline earth and transition metal ions. Microstructural features of R and its complex with Ag + have been investigated by Atomic Force Microscopy (AFM). AFM images can clearly differentiate R from its complex of Ag + . Moreover; the complicated binding mode of metal-ligand complex has been explored by UV-Vis, LC-MS, FIR, Fluorescence titration, Job's plot method and theoretical approaches. Density functional theory (DFT) method at B3LYP/LANL2DZ level of theory was employed for computational studies. Theoretical calculations revealed that selectivity and specificity of R toward Ag + could be attributed to structural conformation of 1,3-alternate-calix[4]arene scaffold and molecular electrostatic potential of its surface. Furthermore; the competitive experiments were carried out to test sensor's ability for practical uses. Finally, the efficiency of R in matrix of physiological cations was examined and showed gradual emission enhancement which makes R an ideal candidate for monitoring of Ag + in physiological environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. pH-dependent solubility of indomethacin-saccharin and carbamazepine-saccharin cocrystals in aqueous media.

    Science.gov (United States)

    Alhalaweh, Amjad; Roy, Lilly; Rodríguez-Hornedo, Naír; Velaga, Sitaram P

    2012-09-04

    Cocrystals constitute an important class of pharmaceutical solids for their remarkable ability to modulate solubility and pH dependence of water insoluble drugs. Here we show how cocrystals of indomethacin-saccharin (IND-SAC) and carbamazepine-saccharin (CBZ-SAC) enhance solubility and impart a pH-sensitivity different from that of the drugs. IND-SAC exhibited solubilities 13 to 65 times higher than IND at pH values of 1 to 3, whereas CBZ-SAC exhibited a 2 to 10 times higher solubility than CBZ dihydrate. Cocrystal solubility dependence on pH predicted from mathematical models using cocrystal K(sp), and cocrystal component K(a) values, was in excellent agreement with experimental measurements. The cocrystal solubility increase relative to drug was predicted to reach a limiting value for a cocrystal with two acidic components. This limiting value is determined by the ionization constants of cocrystal components. Eutectic constants are shown to be meaningful indicators of cocrystal solubility and its pH dependence. The two contributions to solubility, cocrystal lattice and solvation, were evaluated by thermal and solubility determinations. The results show that solvation is the main barrier for the aqueous solubility of these drugs and their cocrystals, which are orders of magnitude higher than their lattice barriers. Cocrystal increase in solubility is thus a result of decreasing the solvation barrier compared to that of the drug. This work demonstrates the favorable properties of cocrystals and strategies that facilitate their meaningful characterization.

  7. Novel nanoparticulate carrier system based on carnauba wax and decyl oleate for the dispersion of inorganic sunscreens in aqueous media.

    Science.gov (United States)

    Villalobos-Hernández, J R; Müller-Goymann, C C

    2005-05-01

    The purpose of this study was to characterize carrier systems for inorganic sunscreens based on a matrix composed of carnauba wax and decyl oleate. Ultraviolet radiation attenuators like barium sulfate, strontium carbonate and titanium dioxide were tested. The lipid matrices were used either as capsules or as accompanying vehicles for the pigments in aqueous dispersions. Manufacturing was performed using high pressure homogenization at 300bar and a temperature of 75 degrees C. To evaluate the effect of the pigments on the crystalline structure of the wax-oil mixture, X-ray diffraction and differential scanning calorimetry were used. Further parameters determined were particle size, polydispersity index, z-potential, viscosity and sun protection factor (SPF). Transmission electron microscopy was also applied for visualization of nanoparticles. The X-ray diffraction patterns and the melting points of the lipid mixtures remained unchanged after the pigments were added. The particle sizes of the encapsulated species ranged from 239 to 749.9nm showing polydispersity values between 0.100 and 0.425. Surface charge measurements comprising values up to -40.8mV denoted the presence of stable dispersions. The formulations could be described as ideal viscous presenting viscosities in a range of 1.40-20.5mPas. Significant increases in SPF up to about 50 were reported after the encapsulation of titanium dioxide. Freeze fracture micrographs confirmed the presence of encapsulated inorganic crystals.

  8. Quinoline group based fluorescent sensor for detecting zinc ions in aqueous media and its logic gate behaviour

    International Nuclear Information System (INIS)

    Dong, Zhengping; Guo, Yueping; Tian, Xin; Ma, Jiantai

    2013-01-01

    A highly sensitive method for quantitative determination of Zn 2+ in water has been developed by using a novel fluorescent sensor NQA: (N-Quinolin-8-yl-2-[(quinolin-8-ylcarbamoylmethyl)-amino]-acetamide). The sensor displays great selectivity for Zn 2+ in the presence of other metal ions in aqueous solution and possesses an excellent sensitivity of about 2×10 −8 M for Zn 2+ . The binding stoichiometry, binding affinity, and pH sensitivity of the sensor have also been studied. Furthermore, the fluorescent changes of NQA upon the addition of cations (Cu 2+ and Zn 2+ ) are utilized to construct an INHIBIT logic gate at the molecular level, using Cu 2+ and Zn 2+ as chemical inputs and the fluorescence intensity as output. NQA has ideal chemical and spectroscopic properties that satisfy the criteria for further biological and environmental applications. - Highlights: ► A novel fluorescent sensor for Zn 2+ in water has been synthesized. ► The sensor displays high selectivity for Zn 2+ in the presence of other ions. ► The sensor exhibits excellent sensing ability under the physiological pH window. ► The sensor can be utilized as an INHIBIT logic gate at the molecular level.

  9. Development of basic data for modelling the residual alteration rate in aqueous media of AVM nuclear glasses

    International Nuclear Information System (INIS)

    Thien, B.

    2010-01-01

    During their aqueous alteration, AVM French nuclear glasses exhibit a large range of behaviour, in spite of a small range of composition. AVM glasses alteration rates are controlled by two phenomena: (i) precipitation of secondary phases, mostly aluminous hectorites, and (ii) diffusion of water across a more or less protective gel. The magnesium contained in these glasses increases the precipitation of these secondary phases, leading to a partial or total dissolution of the gel layer. This dissolution increases the glass alteration rates. On the other hand, Mg also incorporates in the gel, increasing his passivation properties. The predominance of one of these two phenomena depends on the initial composition of the glass, the pH of the solution, and the alteration conditions. In presence of Bure geological disposal site water (Mg and Ca rich), AVM glasses undergo less alteration than in initially pure water, in spite of larger amounts of secondary phase precipitates. This results from incorporation of calcium in the gel instead of sodium and magnesium, improving its passivating properties. We have adapted the geochemical GRAAL model for AVM glasses. In spite of its limitations, this model allows us to describe the differences of behaviour between these glasses, in function of their composition. Moreover, GRAAL can be proposed as a basis of a future operational model for predicting the alteration of AVM glasses. (author) [fr

  10. Techniques and Protocols for Dispersing Nanoparticle Powders in Aqueous Media-Is there a Rationale for Harmonization?

    Science.gov (United States)

    Hartmann, Nanna B; Jensen, Keld Alstrup; Baun, Anders; Rasmussen, Kirsten; Rauscher, Hubert; Tantra, Ratna; Cupi, Denisa; Gilliland, Douglas; Pianella, Francesca; Riego Sintes, Juan M

    2015-01-01

    Selecting appropriate ways of bringing engineered nanoparticles (ENP) into aqueous dispersion is a main obstacle for testing, and thus for understanding and evaluating, their potential adverse effects to the environment and human health. Using different methods to prepare (stock) dispersions of the same ENP may be a source of variation in the toxicity measured. Harmonization and standardization of dispersion methods applied in mammalian and ecotoxicity testing are needed to ensure a comparable data quality and to minimize test artifacts produced by modifications of ENP during the dispersion preparation process. Such harmonization and standardization will also enhance comparability among tests, labs, and studies on different types of ENP. The scope of this review was to critically discuss the essential parameters in dispersion protocols for ENP. The parameters are identified from individual scientific studies and from consensus reached in larger scale research projects and international organizations. A step-wise approach is proposed to develop tailored dispersion protocols for ecotoxicological and mammalian toxicological testing of ENP. The recommendations of this analysis may serve as a guide to researchers, companies, and regulators when selecting, developing, and evaluating the appropriateness of dispersion methods applied in mammalian and ecotoxicity testing. However, additional experimentation is needed to further document the protocol parameters and investigate to what extent different stock dispersion methods affect ecotoxicological and mammalian toxicological responses of ENP.

  11. Measurement of Nitrate Concentration in Aqueous Media Using an Electrochemical Nanosensor Based on Silver Nanoparticles-Nanocellulose/Graphene Oxide

    Directory of Open Access Journals (Sweden)

    Majid Shadfar

    2017-11-01

    Full Text Available Nitrate pollution is at the forefront of groundwater contamination which poses serious environmental and public health hazards.  Nitrate is usually released in solution from agricultural activities and finds its way into groundwater resources. The objective of the present study was to determine, accurately concentrations of nitrate ions in water samples from the environment using sensitive electrochemical methods. For this purpose, a modified glassy carbon electrode modified with a nanocomposite consisting of silver nanoparticles, nanocellulose, and graphene oxide (Ag/NC/GO-GCE was used. The characterization of the nanocomposite was investigated using scanning electron microscope (SEM, X-Ray diffraction (XRD, and electrochemical impedance spectroscopy (EIS. The modified Ag/NC/GO-GCE electrode was used as nanosensor for the electrocatalytic determination of nitrate using the voltammetric method. The effects of the parameters of scan rate, pH, and different nitrate concentrations were studied and the optimum conditions were obtained. A limit of detection of 0.016 µM (S/N=3 was found in the linear range of 0.005 to 10 mM nitrate. The Ag/NC/GO-GCE electrode exhibited a synergistic effect toward voltammetric determination of nitrate in the presence of graphene oxide, nanocellulose, and silver nanocatalyst. The nanosensor developed here showed excellent sensitivity, selectivity, and stability toward nitrate determination in aqueous solutions without any significant interference.

  12. Investigation of the charge-transfer in photo-excited nanoparticles for CO2 reduction in non-aqueous media

    Directory of Open Access Journals (Sweden)

    Dimitrijević Nada M.

    2013-01-01

    Full Text Available Photoinduced charge separation in TiO2 and Cu2O semiconductor nanoparticles was examined using Electron Paramagnetic Resonance spectroscopy in order to get insight into the photocatalytic reduction of CO2 in nonaqueous media. For dissolution/grafting of CO2 we have used carboxy-PEG4-amine, and as a solvent poly(ethylene glycol 200. We have found that, in this system, reduction of CO2 starts at potential of -0.5 V vs Ag/AgCl, which is significantly more positive than the potential for electrochemical reduction of CO2 in most organic solvents and water (-2.0 V vs. Ag/AgCl. The electron transfer from excited nanoparticles to CO2 is governed both by thermodynamic and kinetic parameters, namely by the redox potential of conduction band electrons and adsorption/binding of CO2 on the surface of nanoparticles.

  13. Surface modification of imprinted polymer microspheres with ultrathin hydrophilic shells to improve selective recognition of glutathione in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Song, Renyuan, E-mail: songrenyuan0726@163.com; Hu, Xiaoling; Guan, Ping; Li, Ji; Du, Chunbao; Qian, Liwei; Wang, Chaoli

    2016-03-01

    A universal, effective approach addressing the classical limitations of hydrophobic molecularly imprinted polymer (MIP) microspheres was described. Two water-compatible MIP microspheres with ultrathin hydrophilic shells were synthesized by controllable surface-graft polymerization using a charged monomer (methacrylic acid) and uncharged monomer (N-isopropylacrylamide) as the hydrophilic functional monomers for the recognition of glutathione in the aqueous medium. The morphological and chemical characteristics of the as-prepared water-compatible MIP microspheres were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy and contact angle measurements. Their selective recognition properties were investigated by static binding tests and compared with those of the ungrafted MIP microspheres. The results of this study showed that the both as-prepared water-compatible MIP microspheres effectively decreased non-specific binding and enhanced the imprinting factor significantly, and the water-compatible MIP microspheres prepared using N-isopropylacrylamide as monomer exhibited a more remarkable recognition property. In addition, the thickness of surface-grafted hydrophilic layer was well controlled by adjusting the irradiation time to obtain the excellent recognition property. Finally, the applicability of the as-prepared water-compatible MIP microspheres as solid-phase extraction materials was investigated by competitive binding tests using a mixture of glutathione and its analogs. - Highlights: • Ultrathin hydrophilic shell was synthesized by controllable SIP approach. • Low nonspecific binding, high imprinting factor and selectivity were achieved. • Value of imprinting factor was controlled by adjusting irradiation time. • Selective solid-phase extraction of glutathione from a mixed solution of peptides.

  14. Effect of aqueous media on the copper-ion-mediated phototoxicity of CuO nanoparticles toward green fluorescent protein-expressing Escherichia coli.

    Science.gov (United States)

    Shang, Enxiang; Li, Yang; Niu, Junfeng; Guo, Huiyuan; Zhou, Yijing; Liu, Han; Zhang, Xinqi

    2015-12-01

    Quantitative comparison of different aqueous media on the phototoxicity of copper oxide nanoparticles (CuO NPs) is crucial for understanding their ecological effects. In this study, the phototoxicity of CuO NPs toward the green fluorescent protein-expressing Escherichia coli (GFP-E. coli) under UV irradiation (365 nm) was investigated in Luria-Bertani medium (LB), NaCl solution, deionized water (DI) and phosphate-buffered saline (PBS). The phototoxicity of CuO NPs toward GFP-E. coli decreased in the order of DI>NaCl>PBS>LB because of different released concentrations of Cu(2+). The 3h released Cu(2+) concentrations by 10mg/L CuO NPs in DI water, NaCl solution, LB medium, and PBS were 1946.3 ± 75.6, 1242.5 ± 47.6, 1023.4 ± 41.2, and 1162.1 ± 41.9 μg/L, respectively. Transmission electron microscope and laser scanning confocal microscope images of E. coli exposed to CuO NPs demonstrated that the released Cu(2+) resulted in fragmentation of bacterial cell walls, leakage of intracellular components, and finally death of bacteria in four media after UV light irradiation. In each medium, the bacterial mortality rate logarithmically increased with the releasing concentrations of Cu(2+) by CuO NPs (R(2)>0.90) exposed to 3h UV light. This study highlights the importance of taking into consideration of water chemistry when the phototoxicity of CuO NPs is assessed in nanotoxicity research. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Treatment of aqueous outflows by complexation in micellar media and precipitation with a sol-gel process

    International Nuclear Information System (INIS)

    Lavaud, Cyril

    2013-01-01

    Being able to deal with aqueous outflows from treatment sites in the Hague is a major environmental issue. These outflows are contaminated with organic substances and elements with residual radioactivity. This work deals with the development and optimization of the process of de-polluting, and we aim at removing all pollution from the outflow, and produce a final waste compatible with traditional conditioning matrices in the nuclear area. The separation process consists of two steps: dissolving the pollution in the surfactants micelles, and precipitating a mineral phase via sol-gel transition. Within this thesis, only pollution originating from radionuclides is studied. During the first step, our strategy is to use complexing molecules able to interact with ions and to form mainly solvable complexes at the core of surfactant micelles. Thereafter, the second step consisted to add silica precursor which, after hydrolyse and polycondensation, makes it possible to aggregate those micelles that contain complexes together, and to form a silica phase which precipitates in an in-situ fashion. The goal to de-pollute the outflow was achieved, and the final waste thus produced is a silica powder that contains the micelles and the pollution which, after calcination, is compatible with conditioning matrices such as glass or concrete. A reference system for which the separation process is optimal was defined throughout various studies. This system contains a non-ionic surfactant (P123), an ion that surrogates radionuclides (neodymium), a complexing agent (HDEHP) and a silica precursor (TEOS). Hence, this system was further studied in order to broaden the application scope of the separation process, as well as to understand the mechanisms involved, during the complexation of the ions and the micellar solubilization and during the formation of the silica powder. This study was performed using diffusion, imaging and spectrometry techniques.To conclude, the alternative de

  16. One-pot fabrication of FRET-based fluorescent probe for detecting copper ion and sulfide anion in 100% aqueous media

    Science.gov (United States)

    Lv, Kun; Chen, Jian; Wang, Hong; Zhang, Peisheng; Yu, Maolin; Long, Yunfei; Yi, Pinggui

    2017-04-01

    The design of effective tools for detecting copper ion (Cu2 +) and sulfide anion (S2 -) is of great importance due to the abnormal level of Cu2 + and S2 - has been associated with an increase in risk of many diseases. Herein, we report on the fabrication of fluorescence resonance energy transfer (FRET) based fluorescent probe PF (PEI-FITC) for detecting Cu2 + and S2 - in 100% aqueous media via a facile one-pot method by covalent linking fluorescein isothiocyanate (FITC) with branched-polyethylenimine (b-PEI). PF could selectively coordinate with Cu2 + among 10 metal ions to form PF-Cu2 + complex, resulting in fluorescence quenching through FRET mechanism. Furthermore, the in situ generated PF-Cu2 + complex can be used to selectively detect S2 - based on the displacement approach, resulting in an off-on type sensing. There is no obvious interference from other anions, such as Cl-, NO3-, ClO4-, SO42 -, HCO3-, CO32 -, Br-, HPO42 -, F- and S2O32 -. In addition, PF was successfully used to determine Cu2 + and S2 - in human serum and tap water samples. Therefore, the FRET-based probe PF may provide a new method for selective detection of multifarious analysts in biological and environmental applications, and even hold promise for application in more complicated systems.

  17. A simple, reversible, colorimetric and water-soluble fluorescent chemosensor for the naked-eye detection of Cu2 + in 100% aqueous media and application to real samples

    Science.gov (United States)

    Sun, Tao; Niu, Qingfen; Li, Tianduo; Guo, Zongrang; Liu, Haixia

    2018-01-01

    A simple, reversible, colorimetric and water-soluble fluorescent chemosensor ADA for the naked-eye detection of Cu2 + was developed. Sensor ADA showed high selectivity and sensitivity toward Cu2 + in 100% aqueous media over wide pH range. Sensor ADA exhibited a red-shift in the absorption spectra from 466 to 480 nm that is accompanied by significant color change from light yellow to yellowish brown instantaneously. The Cu2 + recognition is based on the chelation-enhanced fluorescence quenching (CHEQ) effect of the paramagnetic nature. The lowest detection limit is determined to be 15.8 nM, which is much lower than the allowable level of Cu2 + in drinking water set by U.S. Environmental Protection Agency ( 20 μM) and the World Health Organization ( 30 μM). The 1:1 binding process was confirmed by fluorescence measurements, IR analysis and DFT studies. Moreover, sensor ADA was successfully applied for determination of trace level of Cu2 + with 4 reuse cycles in various water samples, which affords promising potential in ion-detection field.

  18. Preparation of SBA-15-PAMAM as a Nano Adsorbent for Removal of Acid Red 266 from Aqueous Media: Batch Adsorption and Equilibrium Studies

    Directory of Open Access Journals (Sweden)

    Maryam Mirzaie

    2017-12-01

    Full Text Available The purpose of the present study was to increase the adsorption capacity of SBA-15 for acidic dyes. Ordered mesoporous silica SBA-15 was successfully synthesized and functionalized by polyamidoamine (PAMAM dendrimer to develop an efficient anionic dye adsorbent. The prepared materials were characterized by field emission scanning electron microscope (FE-SEM, Fourier transforms infrared spectroscope (FT-IR and N2 adsorption–desorption analysis. The study was concocted in the Science and Research Branch of Islamic Azad University of Tehran, Iran in 2016. The produced adsorbent (SBA-15-Den was applied for the removal of Acid Red 266 (AR266 from aqueous media. The effects of various operational parameters including solution pH, adsorbent dosage, contact time, and temperature on removal of AR266 using SBA-15-Den were investigated in batch adsorption mode. Within the optimum conditions, SBA-15-Den exhibited an excellent adsorptive capability of 1111.11 mg/g. Equilibrium data were best described by Langmuir model (R2 > 0.98 completely.

  19. A simple, reversible, colorimetric and water-soluble fluorescent chemosensor for the naked-eye detection of Cu2+ in ~100% aqueous media and application to real samples.

    Science.gov (United States)

    Sun, Tao; Niu, Qingfen; Li, Tianduo; Guo, Zongrang; Liu, Haixia

    2018-01-05

    A simple, reversible, colorimetric and water-soluble fluorescent chemosensor ADA for the naked-eye detection of Cu 2+ was developed. Sensor ADA showed high selectivity and sensitivity toward Cu 2+ in ~100% aqueous media over wide pH range. Sensor ADA exhibited a red-shift in the absorption spectra from 466 to 480nm that is accompanied by significant color change from light yellow to yellowish brown instantaneously. The Cu 2+ recognition is based on the chelation-enhanced fluorescence quenching (CHEQ) effect of the paramagnetic nature. The lowest detection limit is determined to be 15.8nM, which is much lower than the allowable level of Cu 2+ in drinking water set by U.S. Environmental Protection Agency (~20μM) and the World Health Organization (~30μM). The 1:1 binding process was confirmed by fluorescence measurements, IR analysis and DFT studies. Moreover, sensor ADA was successfully applied for determination of trace level of Cu 2+ with 4 reuse cycles in various water samples, which affords promising potential in ion-detection field. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Studies on the rates of exchange of Hg(II), Cd(II), La(III) and Ce(III) ions in sodium nitrite-aqueous acetone media using an anion-exchanger Dowex-1x8(NO3-)

    International Nuclear Information System (INIS)

    Bhatnagar, R.P.; Bhardwaj, Archana; Bhardwaj, S.D.

    1998-01-01

    Rate of exchange has been studied on Hg(II), Cd(II), La(III) and Ce(III) ions in sodium nitrite-aqueous acetone media using an anion exchanger Dowex-1 x 8(NO 3 - ). Acetone was used to provide solvent media of 10%, 30% and 50% and temperature was used in rate studies, carried out at 30 deg, 40 deg, 50 degC. Always 1 g. of Dowex-1x8 in nitrate form was used for distribution studies to get rate data. After suitable time intervals aliquots (1 ml) were withdrawn and metal ion concentration was found out. (author)

  1. Highly selective probe based on imine linkage for Zn{sup 2+} and HSO{sub 3}{sup −} in mixed aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Kamaljot; Chaudhary, Savita; Singh, Sukhjinder; Mehta, S.K., E-mail: skmehta@pu.ac.in

    2015-04-15

    A simple salicylaldehyde derived Schiff base N, N′- bis (p-chloro salicylidene)-1, 2- ethylenediamine (L) was synthesized and characterized. The receptor demonstrates simultaneous dual channel chromogenic and fluorogenic signaling towards HSO{sub 3}{sup −} and Zn{sup 2+} in mixed aqueous media. Solvatochromism was employed systematically for modulating its optoelectronic properties. The probe was successfully assessed to monitor HSO{sub 3}{sup −} detection via UV–vis spectroscopy. DFT calculations and {sup 1}H NMR spectroscopy further support the results based on shifting of equilibrium. Moreover, the sensor showed large fluorescence enhancement with blue-shift of 48 nm after addition of Zn{sup 2+}. The probe exhibits high selectivity over other competitive ions with high detection limit of 6.54×10{sup −5} M and 3.21×10{sup −6} M for HSO{sub 3}{sup −} and Zn{sup 2+}, respectively. Importantly, this is one of the rare reports in which Schiff base was utilized for the fabrication of chromogenic or fluorogenic sensor using solvent effect for multianalyte detection. - Highlights: • Easy synthesis of highly selective and sensitive Salicylideneaniline moiety. • Solvatochromism induced tautomerism between the enol-imine and keto-amine forms. • Computational studies revealing the effect of solvent on stability of NH form. • Discriminative detection of HSO{sub 3}{sup −} and Zn{sup 2+} by different spectroscopic techniques. • Optical feedbacks as absorption transitions with HSO{sub 3}{sup −} on bisulphite adduct formation. • Fluorescence enhancement for Zn{sup 2+} based on imine binding mechanism.

  2. Rhodamine B immobilized on hollow Au-HMS material for naked-eye detection of Hg{sup 2+} in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Na [State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology, Dalian, 116024 (China); Li, Gang, E-mail: liganghg@dlut.edu.cn [State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology, Dalian, 116024 (China); Cheng, Zhuhong [State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology, Dalian, 116024 (China); Zuo, Xiujin [Key Laboratory of Bio-organic Chemistry, College of Environmental and Chemical Engineering, Dalian University, Dalian, 116622 (China)

    2012-08-30

    Graphical abstract: Au-HMS-Probe with worm-like mesoporous framework for detection of Hg{sup 2+} in aqueous media has been simply and effectively synthesized by immobilizing a Rhodamine B derivative on Au-HMS via Au-N groups under room temperature. Highlights: Black-Right-Pointing-Pointer Au-HMS-Probe is prepared via Au-N bonds. Black-Right-Pointing-Pointer Gold nanoparticles are chosen as connectors instead of silane agents. Black-Right-Pointing-Pointer Au-HMS is chosen as carrier for the first time. Black-Right-Pointing-Pointer The immobilization method of Au-HMS-Probe is very simple and effective. Black-Right-Pointing-Pointer Au-HMS-Probe shows excellent ability for detecting Hg{sup 2+} by naked-eye. - Abstract: A simple, effective method has been demonstrated to immobilize Rhodamine B (RhB) probes on mesoporous silica (Au-HMS). The prepared chemosensor (Au-HMS-Probe) was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), UV-vis spectrum and Fourier transform infrared spectroscopy (FT-IR). Further application of Au-HMS-Probe in sensing Hg{sup 2+} was confirmed by fluorescence titration experiment. Au-HMS-Probe afforded 'turn-on' fluorescence enhancement and displayed high brightness in water, and it also showed excellent selectivity for Hg{sup 2+} over alkali (Na{sup +}, K{sup +}), alkaline earth (Mg{sup 2+}, Ca{sup 2+}) and other heavy metal ions (Ag{sup +}, Cd{sup 2+}, Co{sup 2+}, Pb{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, Fe{sup 2+}). Importantly, Au-HMS-Probe could be regenerated by treatment with tetrapropylammonium hydroxide solution.

  3. Optimization, isotherm, kinetic and thermodynamic studies of Pb(II) ions adsorption onto N-maleated chitosan-immobilized TiO2 nanoparticles from aqueous media

    Science.gov (United States)

    Shaker, Medhat A.; Yakout, Amr A.

    2016-02-01

    Chitosan, CS was chemically engineered by maleic anhydride via simple protocol to produce N-maleated chitosan, MCS which immobilized on anatase TiO2 to synthesize novel eco-friendly nanosorbent (51 ± 3.8 nm), MCS@TiO2 for cost-effective and efficient removal of Pb(II) ions from aqueous media. The chemical structure, surface properties and morphology of MCS@TiO2 were recognized by FTIR, 1H NMR, XRD, TEM, DLS and zeta-potential techniques. The relations between %removal of Pb(II) and different analytical parameters such as solution acidity (pH), MCS@TiO2 dosage, time of contact and initial Pb(II) concentration were optimized using response surface methodology (RSM) and Box-Behnken design (BBD) statistical procedures. The fitting of the experimental data to four different isotherm models at optimized conditions was carried out by various statistical treatments including the correlation coefficient (r), coefficient of determination (r2) and non-linear Chi-square (χ2) test analyses which all confirm the suitability of Langmuir model to explain the adsorption isotherm data. Also, statistics predicted that the pseudo-second-order model is the optimum kinetic model among four applied kinetic models to closely describe the rate equation of the adsorption process. Thermodynamics viewed the adsorption as endothermic and feasible physical process. EDTA could release the sorbed Pb(II) ions from MCS@TiO2 with a recovery above 92% after three sorption-desorption cycles. The novel synthesized nanosorbent is evidenced to be an excellent solid phase extractor for Pb(II) ions from wastewaters.

  4. Alternative (Potentially Green) Separations Media: Aqueous Biphasic and Related Systems Extending the Frontier Final Report For Period September 1, 2002 January 31, 2007

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Robin D

    2007-06-25

    Through the current DoE-BES funding, we have extended our fundamental understanding of the critical phase separation of aqueous polymer solutions at the molecular level, and have developed a similar understanding of their application as novel solvent systems. Our principal aims included mode of delivery of the aqueous biphasic system (ABS) solvent system and the application of this system to problems of reactive extraction. In the former case we have developed novel solid phase analogues, in the form of cross-linked polyethylene glycol hydrogels, and in the latter case we have examined the role that ABS might play in reaction engineering, with a view to greener, simpler, and safer processes. We have also developed a new salt/salt ABS and have extended our understanding of this system as well. The major outcomes are as follows: (1) Through the use of variable temperature phase diagrams, coupled with differential scanning calorimetry (DSC) measurements of the phases, a better understanding of the thermodynamics of phase formation was obtained. Evidence to the existence and role of an upper critical solution temperature (UCST) or lower critical solution temperature (LCST) (or both) in these systems was gained. With variable temperature solute partitioning, thermodynamic parameters were calculated, and inter-system comparisons were made. Through the use of Abraham's linear solvation energy regression (LSER) the solvent-solute properties of liquid/liquid ABS were examined. We have shown that ABS are indeed very tunable and LSERs have been used as a tool to compare these systems to traditional organic/water and other liquid/liquid systems. (2) We have successfully shown the development of novel reaction media for chemical synthesis and reaction; Aqueous Biphasic Reactive Extraction (ABRE). As a proof of concept, we have shown the synthesis of adipic acid from cyclohexene in an ABS, which represents an important development in the exploitation of this technology

  5. Pengaruh Penambahan Aditif Bi2O3 Terhadap Karakteristik Barium Heksaferit Hasil Sintesis dengan Metode Sol-Gel

    Directory of Open Access Journals (Sweden)

    Siti Wardiyati Siswoyo

    2017-11-01

    Full Text Available Telah dilakukan sintesis barium heksaferit (BaFe12O19 secara sol-gel menggunakan prekursor barium nitrat [Ba(NO32], besi nitrat [Fe(NO33] dan asam sitrat (C6H8O7 Penelitian ini bertujuan untuk mendapatkan BaFe12O19 fasa tunggal berukuran nano dengan koersivitas magnetik tinggi. Untuk mencapai tujuan tersebut dilakukan penambahan aditif Bi2O3 dengan berbagai variasi persentase berat terhadap BaFe12O19 dari 0,5% sampai dengan 2%. Karakterisasi BaFe12O19 hasil sintesis dilakukan dengan  menggunakan alat X-ray diffraction (XRD untuk analisis  fasa, Fourier Transmission Infra Red (FTIR untuk mengetahui tipe ikatan yang terjadi, Scanning Electron Microscope dan Energy Dispersive X-ray Spectroscopy (SEM/EDS untuk analisis struktur dan persentase atom, dan Vibrating Sample Magnetometer VSM untuk mengetahui sifat magnetik yaitu koersivitas dan saturasi magnetik. Dari hasil percobaan diperoleh BaFe12O19 fasa tunggal dengan ukuran partikel sekitar 105 nm - 130 nm, saturasi magnetik 57,86 emu/g dan koersivitas magnetik sebesar 0,38 T. 

  6. BANGUNAN TINGGI MULTI FUNGSI SEBAGAI SINTESIS ARSITEKTUR DAN STRUKTUR Studi Analisis Jin Mao Tower Grand Hyatt Shanghai

    Directory of Open Access Journals (Sweden)

    Jimmy Priatman

    2005-01-01

    Full Text Available More than two decades, after the emerging of post- modern architecture, the split between construction technology and cultural expression in architecture appeared to become wider and wider. With the exception of a few "high-tech" buildings, the unity of art and applied science (technology in design seems facing challenges. It is interesting to see how fast and unexpectedly the situation has changed. Many factors and people played a role in this reversal, many new buildings demonstrate that utilitarian artifacts do not have to be oppressive to creativity but can evoke new innovation. One of the most significant contributors was JIN MAO TOWER at Shanghai, China. The paper analyses this building as a genuine synthesis of rational intelligence with art poetry that is still possible. Abstract in Bahasa Indonesia : Lebih dari dua dekade setelah timbulnya arsitektur pasca modern, pemisahan antara tekknologi konstruksi dan ekspresi kultural dalam arsitektur menjadi semakin lebar. Dengan perkecualian beberapa gedung "high-tech", kesatuan antara seni dan teknologi dalam tahap desain terlihat menghadapi tantangan tantangan. Tetapi menarik untuk diamati bahwa situasi telah berubah. Banyak faktor dan tokoh tokoh arsitek memegang peranan penting dalam perubahan ini, banyak bangunan bangunan baru mendemontrasikan bahwa artefak fungsionil tidak bearti menindas kreativitas namun dapat membangkitkan inovasi baru. Salah satu kontributor yang sangat penting adalah JIN MAO TOWER di Shanghai-China. Makalah ini membahas bangunan tersebut sebagai sintesis orijinal yang masih memungkinkan antara kecerdasan rasional dengan puisi seni arsitektur. Kata kunci: Sintesis.

  7. A Green Synthesis of Xanthenone Derivatives in Aqueous Media Using TiO2-CNTs Nanocomposite as an Eco-Friendly and Re-Usable Catalyst.

    Science.gov (United States)

    Samani, Amir; Abdolmohammadi, Shahrzad; Otaredi-Kashani, Asieh

    2018-01-01

    The xanthene (dibenzopyran) framework constitutes the core structure of many biologically active compounds, that they have been of interest because of their pharmacological activities like antiviral, antibacterial, anti-inflammatory, and CCR1 antagonist. As heterogeneous catalysts offer several advantages over homogeneous catalysts, the performance of reactions on the surface of nanosized heterogeneous salts has received a great deal of interest in recent years. In the area of nanosized heterogeneous catalysts there is a noticeable range of reactions that are catalyzed efficiently by TiO2 NPs. Moreover, carbon nanotubes (CNTs) as a support can be used to obtain nanoparticles with modified morphology, structural, chemical, electrical, and optical properties. The catalytic activity of titanium dioxide supported on carbon nanotubes has been greatly improved. The present methodology focus on the synthesis of 7,7-dimethyl-10-aryl- 6,7,8,10-tetrahydro-9H-[1,3]dioxolo[4,5-b]xanthen-9-ones, through a condensation reaction of dimedone, aromatic aldehydes and 3,4-methylenedioxyphenol, using a catalytic amount of TiO2- CNTs nanocomposite (15 mol%) at 80 ˚C in aqueous media, within 60-90 min. The TiO2-CNTs nanocomposite was also prepared by a known simple sonochemical method. A series of 7,7-dimethyl-10-aryl-6,7,8,10-tetrahydro-9H-[1,3]dioxolo[4,5-b]xanthen-9-ones were successfully synthesized in high yields (92-98%). All synthesized compounds were well characterized by their satisfactory elemental analyses, IR, 1H and 13C NMR spectroscopy. The synthesized catalyst was fully characterized by SEM, TEM, XRD, and EDX techniques. In summary, this investigation constitutes a novel and efficient route for the synthesis of 7,7-dimethyl-10-aryl-6,7,8,10-tetrahydro-9H-[1,3]dioxolo[4,5-b]xanthen-9-ones in high yields, by a three-component reaction of dimedone, aromatic aldehydes and 3,4-methylenedioxyphenol in water and in the presence of the TiO2-CNTs nanocomposite as a green

  8. Potentiodynamic polarization studies of bulk amorphous alloy Zr57Cu15.4Ni12.6Al10Nb5 and Zr59Cu20Ni8Al10Ti3 in aqueous HNO3 media

    International Nuclear Information System (INIS)

    Sharma, Poonam; Dhawan, Anil; Jayraj, J.; Kamachi Mudali, U.

    2013-01-01

    The potentiodynamic polarization studies were carried out on Zr based bulk amorphous alloy Zr 57 Cu 15.4 Ni 12.6 Al 10 Nb 5 and Zr 59 Cu 20 Ni 8 Al 10 Ti 3 in solutions of 1 M, 6 M and 11.5 M HNO 3 aqueous media at room temperature. As received specimens of Zr 57 Cu 15.4 Ni 12.6 Al 10 Nb 5 (5 mm diameter rod) and Zr 59 Cu 20 Ni 8 Al 10 Ti 3 (3 mm diameter rod) were polished with SiC paper before testing them for potentiodynamic polarization studies. The amorphous nature of the specimens was checked by X-ray diffraction. The bulk amorphous alloy Zr 59 Cu 20 Ni 8 Al 10 Ti 3 shows the better corrosion resistance than Zr 57 Cu 15.4 Ni 12.6 Al 10 Nb 5 alloy in the aqueous HNO 3 media as the value of the corrosion current density (I corr ) for Zr 57 Cu 15.4 Ni 12.6 Al 10 Nb 5 alloy were found to be more than Zr 59 Cu 20 Ni 8 Al 10 Ti 3 alloy in aqueous HNO 3 media. The improved corrosion resistance of Zr 59 Cu 20 Ni 8 Al 10 Ti 3 alloy is possibly due to the presence of Ti and formation of TiO 2 during anodic oxidation. Both Zr based bulk amorphous alloys shows wider passive range at lower concentration of nitric acid and the passive region gets narrowed down with the increase in concentration. A comparison of data obtained from both the Zr-based bulk amorphous alloys is made and results are discussed in the paper. (author)

  9. Ultrasound promoted one-pot synthesis of 2-amino-4,8-dihydropyrano[3,2-b]pyran-3-carbonitrile scaffolds in aqueous media: a complementary 'green chemistry' tool to organic synthesis.

    Science.gov (United States)

    Banitaba, Sayed Hossein; Safari, Javad; Khalili, Shiva Dehghan

    2013-01-01

    A green and simple approach to assembling of 2-amino-4,8-dihydropyrano[3,2-b]pyran-3-carbonitrile scaffolds via three-component reaction of kojic acid, malononitrile, and aromatic aldehydes in aqueous media under ultrasound irradiation is described. The combinatorial synthesis was achieved for this methodology with applying ultrasound irradiation while making use of water as green solvent. In comparison to conventional methods, experimental simplicity, good functional group tolerance, excellent yields, short routine, and selectivity without the need for a transition metal or base catalyst are prominent features of this green procedure. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Investigation of the mechanisms of using metal complexation and cellulose nanofiber/sodium alginate layer-by-layer coating for retaining anthocyanin pigments in thermally processed blueberries in aqueous media.

    Science.gov (United States)

    Jung, Jooyeoun; Cavender, George; Simonsen, John; Zhao, Yanyun

    2015-03-25

    This study investigated the mechanisms of anthocyanin pigment retention using Fe(3+)-anthocyanin complexation and cellulose nanofiber (CNF)/sodium alginate (SA) layer-by-layer (LBL) coatings on thermally processed blueberries in aqueous media. Anthocyanin pigments were polymerized through complexation with Fe(3+) but readily degraded by heat (93 °C for 7 min) in the aqueous media because of poor stability. CNF/SA LBL coating was successful to retain anthocyanin pigments in thermally processed blueberries. Fruits coated with CNF containing CaCl2 followed by treatment in a SA bath formed a second hydrogel layer onto the CNF layer (LBL coating system) through cross-linking between Ca(2+) and alginic acid. Methyl-cellulose-modified CNF improved the interactions between CNF, the fruit surface, and the SA layer. This study demonstrated that the CNF/SA LBL coating system was effective to retain anthocyanin pigments on thermally processed whole blueberries, whereas no combined benefit of complexation with coating was observed. Results explained the mechanisms of the new approaches for developing colorful and nutritionally enhanced anthocyanin-rich fruit products.

  11. SINTESIS BIODISEL DARI MINYAK BIJI KARET DENGAN VARIASI SUHU DAN KONSENTRASI KOH UNTUK TAHAPAN TRANSESTERIFIKASI

    Directory of Open Access Journals (Sweden)

    Ratna Dewi Kusumaningtyas

    2013-05-01

    Full Text Available Bahan bakar yang paling banyak digunakan adalah bahan bakar diesel atau fatty acid methyl ester (FAME. Biodiesel berasal dari minyak nabati yang dapat diperbaharui, dapat dihasilkan secara periodik, dan mudah diperoleh. Pada penelitian ini digunakan minyak biji karet untuk sintesis FAME. Proses utama dalam pembuatan FAME adalah transesterifikasi. Penelitian ini mengkaji hasil optimum dari variasi konsentrasi katalis KOH dan suhu reaksi pada reaksi transesterifikasi. Preparasi minyak biji karet dengan menggunakan arang aktif granular diikuti dengan degumming. Reaksi esterifikasi dilaksanakan pada kondisi operasi 500 C selama 1 jam, katalis asam sulfat (98% sebesar 0,5% volume minyak, dan metanol sebesar 20% volume minyak. Reaksi transesterifikasi dilaksanakan selama 1 jam, serta perbandingan volume minyak dan metanol sebesar 4:1. Analisis kadar metil ester yang terbentuk, jumlah komponen, dan komposisinya yang terdapat pada senyawa hasil dilakukan dengan menggunakan alat GC. Kondisi operasi terbaik pada transesterifikasi minyak biji karet menjadi metil ester adalah pada katalis KOH 1% dan suhu 60 0C. Berdasarkan uji sifat-sifat fisis, metil ester yang dihasilkan belum semua memenuhi mutu sifat fisis biodiesel yang disyaratkan. The most widely used fuel is diesel fuel or fatty acid methyl ester (FAME. Biodiesel is derived from vegetable oil that can be renewed, can be produced periodically, and easy to obtain. In this research, the rubber seed was used for synthesizing the FAME. The main process in the production of FAME is transesterification. This study examined the optimum result from variations of the concentration of KOH catalyst and the reaction temperature on the transesterification reaction. Preparation of the rubber seed oil using granular activated charcoal was followed by degumming. Esterification reaction was carried out at 50 oC for 1 h with the sulfuric acid catalyst of 0.5% by volume of oil and methanol of 20% by the volume of

  12. Principles of interactions in non-aqueous electrolyte solutions

    NARCIS (Netherlands)

    Lyklema, J.

    2013-01-01

    In this paper a review is presented on the molecular interactions in non-aqueous media of low dielectric permittivity. Qualitative and quantitative distinctions with aqueous solutions are emphasized. The reviewed themes include dispersion forces, dissociation and association equilibria,

  13. Uranium chemistry in blood and aqueous media. Techniques of studies; Chimie de l`uranium en milieux aqueux et sanguin. Techniques d`etudes

    Energy Technology Data Exchange (ETDEWEB)

    Scapolan, St

    1996-11-01

    The object of this report in a first step, is to understand the chemistry of uranium in aqueous phase by specifying the behavior of this element in function of several parameters such PH, concentration of present species, temperature, ionic force. In a second step, investigation techniques are reviewed: X rays diffraction, potentiometric titrations, polarography, spectrophotometry, NMR of {sup 13}C, {sup 31}P, {sup 17}O, capillary electrophoresis, laser detection. The third part brings elements to understand the uranium complexation in blood medium.

  14. Experimental study and thermodynamic modelling of methane clathrate hydrate dissociation conditions in silica gel porous media in the presence of methanol aqueous solution

    International Nuclear Information System (INIS)

    Hashemi, Hamed; Javanmardi, Jafar; Zarifi, Mojdeh; Eslamimanesh, Ali; Mohammadi, Amir H.

    2012-01-01

    Highlights: ► Phase equilibria of hydrates of methane in confined silica gel pores are reported. ► Dissociation data in the presences of methanol aqueous solution are also measured. ► A thermodynamic model is developed for prediction of the obtained data. ► Acceptable agreement is found between the obtained data and the predicted results. - Abstract: In this work, the phase equilibria of clathrate hydrates of methane in the presence of pure water and 0.035 mass fraction of methanol aqueous solution in confined silica gel pores with (10 and 15) nm mean diameters are measured and reported. A thermodynamic model is also developed for prediction of the obtained experimental hydrate dissociation data. The Valderrama–Patel–Teja (VPT-EoS) equation of state (EoS) accompanied with the non-density dependent (NDD) mixing rules coupled with a previously developed activity model are applied to evaluate the fugacity of the species present and the activity coefficient of water in methanol aqueous solution. Acceptable agreement between the reported data and the predicted results using the proposed model and an existing method reported in the literature demonstrates the reliability of the presented model.

  15. UKURAN PARTIKEL DAN KONFORMASI KRISTAL ZEOLIT-A HASIL SINTESIS DENGAN PENAMBAHAN TETRAPROPILAMMONIUM HIDROKSIDA (TPAOH

    Directory of Open Access Journals (Sweden)

    Nurul - Widiastuti

    2014-12-01

    Full Text Available Abstract PARTICLE SIZE AND CRYSTAL CONFORMATION OF SYNTHESIZED ZEOLITE-A WITH TETRAPROPYLAMMONIUM HYDROXIDE (TPAOH ADDITION. The aims of this research is to study the effect of tetrapropylammonium hydroxide (TPAOH concentration in the synthesis of zeolite A to its physical characteristics such as crystallinity, crystal conformation and average crystal size. The zeolite A was synthesized with composition 3.165 Na2O : 1.000 Al2O3 : 1.926 SiO2 : 128 H2O : x TPAOH where x was 0; 0.0385; 0.0577; 0.0770; 0.1540 and 4.1602. The zeolite was crystalized under hydrothermal condition in a stainless steel autoclave at 100°C for 5 hours. The resulting crystal was washed with distilled water until pH 8 and then dried in an oven at 80oC for 24 hours. FT-IR and XRD analysis results show that the synthesized zeolite A at x = 4.1602 has the lowest crystallinity. It is estimated due to the mass of TPAOH was four times higger than the mass of zeolite framework components (Si and Al. SEM and PSD (Particle Size Distribution analysis results show that TPAOH concentration affected the crystal conformation and the average size of zeolite A particles. The formation of chained crystal conformation was caused by the electrostatic interactions between TPA+ and negatively charge of zeolite framework. In addition, the particel size of the synthesized zeolite A at x = 0.1540 was 2.024 µm which was smaller than the particel size of the synthesized zeolite A without TPAOH, which was 3.534 µm. Keywords: average size of particles; crystal conformation; TPAOH; zeolite A Abstrak Penelitian ini bertujuan untuk mempelajari pengaruh konsentrasi TPAOH (Tetrapropilamonium hidroksida dalam sintesis zeolit A terhadap sifat fisikanya yang meliputi kekristalan, konformasi kristal dan ukuran rata-rata kristal yang terbentuk. Pada penelitian   ini   zeolit A   disintesis    dengan komposisi 3,165 Na2O : 1 Al2O3 : 1,926 SiO2 :128 H2O: x TPAOH. Konsentrasi TPAOH divariasikan dengan

  16. SINTESIS DAN KARAKTERISASI BIODIESEL DARI MINYAK KEMIRI SUNAN (Reutealis trisperma DENGAN VARIASI KONSENTRASI KATALIS NAOH

    Directory of Open Access Journals (Sweden)

    Holilah -

    2014-06-01

    Full Text Available Sintesis biodiesel dari minyak Kemiri Sunan (Reutealis trisperma (RTO menggunakan NaOH sebagai katalis dengan variasi konsentrasi katalis yaitu 0,5; 1,0; 1,5 dan 2,0 wt% telah diteliti. Minyak kemiri sunan (Reutealis trisperma adalah bahan baku yang menarik untuk produksi biodiesel. Biodiesel disintesis dengan dua tahap reaksi yaitu esterifikasi menggunakan katalis H2SO4 dan transesterifikasi dengan menggunakan katalis NaOH. Dalam penelitian ini, diteliti pengaruh konsentrasi katalis terhadap produk biodisel serta dan karakteristiknya. Hasil penelitian menunjukkan bahwa yield biodiesel meningkat seiring dengan meningkatnya konsentrasi katalis dari 0,5-1,0 wt%, selanjutnya dengan meningkatnya konsentrasi katalis dari 1,5-2,0 wt% membuat yield menurun. Yield optimum dicapai pada 84,7%. FAME (fatty  acid  methyl  ester diperoleh dengan konsentrasi katalis 1 wt% pada kondisi reaksi 65°C, waktu reaksi 1 jam dan rasio metanol minyak 1:2 (wt/wt. Karakteristik biodiesel diamati dengan uji standart bahan bakar dan hasilnya dibandingkan dengan standart ASTM D6751-02. Karakteristik biodiesel yang disintesis dengan konsentrasi katalis NaOH 1% adalah angka asam (0,55 mg KOH/g, densitas (0,90 gr/cm3, viskositas pada 40°C (9,2 cSt, angka setana (54,5 dan residu karbon (0,24 wt%/wt. This research was investigated bio diesel synthesis of Reutealis trisperma oil (RTO by using NaOH as a catalist with variation of catalyst concentration as follow 0.5; 1.0; 1.5 and 2,0 wt% . Reutealis trisperma oil is an attractive raw material for  bio diesel production. It was produced by two steps of reactions, they are esterification by using H2SO4 catalyst and transesterification by using NaOH catalyst. This study examined the effect of catalyst concentration on the yield of biodiesel and their selected properties. The result showed, that the bio diesel yield  with catalyst concentration increasing from 0,5-1,0 wt%, increased, while increasing the concentration from 1

  17. Kinetics and mechanism of OsOsub(4) catalyzed oxidation of chalcones by Cesub(4) in aqueous acetic sulfuric acid media

    International Nuclear Information System (INIS)

    Srinivasulu, P.V.; Adinarayana, M.; Sethuram, B.; Rao, T.N.

    1985-01-01

    Kinetics of OsOsub(4) catalyzed oxidation of chalcones by Cesup(4+) was studied in aqueous acetic-sulfuric acid medium in the temperature range 313 to 338 K. The order in oxidant is zero while the order with respect to substrate and catalyst are each fractional. The rate of the reaction decreased with increase in percentage of acetic acid while [Hsup(+)] had practically no effect on the rate. The rates of various substituted chalcones are given. A mechanism in which formation of a cyclic ester between chalcone and OsOsub(4) in a fast step followed by its decomposition in a rate-determining step is envisaged. (author)

  18. Nanoparticulas basadas en complejos de Fe(II) con transicion de espin: sintesis, caracterizacion y aplicaciones en electronica molecular

    Science.gov (United States)

    Monrabal Capilla, Maria

    Esta tesis doctoral esta organizada en 5 capitulos y esta destinada al estudio de sistemas de Fe (II) que presentan el fenomeno de la transicion de espin a escala nanometrica. El capitulo 1 contiene una introduccion general sobre materiales moleculares multifuncionales, destacando aquellos ejemplos mas importantes. Por otro lado, se explicara el fenomeno de la transicion de espin, tratando aspectos conceptuales, los antecedentes mas importantes y la situacion actual. En el capitulo 2 se describen los diferentes procesos existentes para la obtencion de diferentes tipos de nanoparticulas. Ademas, se presenta la sintesis y caracterizacion de nanoparticulas del polimero de coordinacion unidimensional [Fe(Htrz)2(trz)]BF4, obtenidas mediante el metodo de micelas inversas. Estas nanoparticulas, con una estrecha distribucion de tamanos centrada alrededor de los 11 nm, presentan una transicion de espin muy abrupta, con un ancho ciclo de histeresis termica de unos 40K. En el capitulo 3 se describe el proceso de modificacion del tamano de las nanoparticulas descritas en el capitulo anterior, llevado a cabo variando la proporcion de surfactante/H2O en el medio. Ademas, con el objetivo de modificar las propiedades magneticas de las nanoparticulas obtenidas en el capitulo 2, se lleva a cabo la sintesis de nanoparticulas de polimeros de la misma familia del [Fe(Htrz)2(trz)]BF4. En concreto se sintetizaron 3 nuevos tipos de nanoparticulas basadas en el polimero [Fe(Htrz)1-x(NH2trz)x](ClO4)2, siendo x = 0.05, 0.15 y 0.3, en cada caso. Estas nanoparticulas siguen presentando una estrecha distribucion de tamanos y una transicion de espin muy abrupta y con un ancho ciclo de histeresis. Ademas, se observa que este ciclo se desplaza a temperaturas mas proximas a la temperatura ambiente a medida que se aumenta el porcentaje de 4-amino-1, 2, 4- triazol en la muestra. Pero al mismo tiempo se produce una disminucion de la anchura de este ciclo. Por ultimo, en este capitulo se presenta la

  19. Application of E{sub h}-pH diagram for room temperature precipitation of zinc stannate microcubes in an aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hinai, Ashraf T., E-mail: ashraf@squ.edu.om [Department of Chemistry, College of Science, Sultan Qaboos University, 123, Alkhoud (Oman); Al-Hinai, Muna H. [Department of Chemistry, College of Science, Sultan Qaboos University, 123, Alkhoud (Oman); Water Research Center, Sultan Qaboos University, 123, Alkhoud (Oman); Dutta, Joydeep, E-mail: dutta@squ.ed.om [Water Research Center, Sultan Qaboos University, 123, Alkhoud (Oman)

    2014-01-01

    Graphical abstract: - Highlights: • One pot aqueous synthesis of zinc stannate (ZnSnO{sub 3}) particles at low temperature. • Synthesis designed with the assistance of potential-pH diagram. • ZnSnO{sub 3} estimated to be stable between pH 8 and 12 was used for synthesis of the particles. • ZnSnO{sub 3}·3H{sub 2}O were formed during the precipitation of zinc stannate. - Abstract: Potential-pH diagram assisted-design for controlled precipitation is an attractive method to obtain engineered binary and ternary oxide particles. Aqueous synthesis conditions of zinc stannate (ZnSnO{sub 3}) particles at low temperature were formulated with the assistance of potential-pH diagram. The pH of a solution containing stoichiometric amounts of Zn{sup 2+} and Sn{sup 4+} was controlled for the precipitation in a one pot synthesis step at room temperature (25 °C). The effect of the concentration of the reactants on the particle size was studied by varying the concentration of the precursor (Zn{sup 2+} + Sn{sup 4+}) solution. Scanning electron micrographs show that the particles are monodispersed micron sized cubes formed by the self-organization of nano-sized crystallites. The obtained microcubes characterized by X-ray Diffraction and thermo gravimetric analysis (TGA) show that the particles are in ZnSnO{sub 3}·3H{sub 2}O form.

  20. Ternary rare earth sulfide CaCe2S4: Synthesis and characterization of stability, structure, and photoelectrochemical properties in aqueous media

    Science.gov (United States)

    Sotelo, Paola; Orr, Melissa; Galante, Miguel Tayar; Hossain, Mohammad Kabir; Firouzan, Farinaz; Vali, Abbas; Li, Jun; Subramanian, Mas; Longo, Claudia; Rajeshwar, Krishnan; Macaluso, Robin T.

    2018-06-01

    A red-orange rare earth ternary chalcogenide, CaCe2S4, was prepared in powder form by solid-state synthesis. The structural details of this compound were determined by powder X-ray diffraction. The optical band gap of CaCe2S4 was determined by diffuse reflectance spectroscopy (DRS) to be 2.1 eV, consistent with the observed red-orange color. Quantitative colorimetry measurements also support the observed color and band gap of CaCe2S4. Both direct and indirect optical transitions were gleaned from Tauc analyses of the DRS data. Photoelectrochemistry experiments on CaCe2S4 films showed n-type semiconductor behavior. Analyses of these data via the Butler-Gärtner model afforded a flat-band potential of - 0.33 V (vs. Ag/AgCl/KCl 4 M) in pH 9 aqueous sulfite electrolyte. The potential and limitations of this material for solar water splitting and photocatalytic environmental remediation (e.g., dye photodegradation) are finally presented against the backdrop of its photoelectrochemical stability and surface hole transfer kinetics in aqueous electrolytes.

  1. Subnanodimensional thermometrical NMR-sensors on the basis of lanthanide(III) paramagnetic complexes with EDTA for temperature control in aqueous media and magnetoresonance tomography

    International Nuclear Information System (INIS)

    Babajlov, S.P.

    2008-01-01

    It is proposed that temperature dependence of paramagnetic lanthanide-induced shifts (LIS) in NMR spectra on nuclei of EDTA type synthetic organic complexes in kinetically unstable compounds with paramagnetic lanthanide(III) cations is used for ascertaining the temperature of samples placed directly into a NMR spectrometer and formed on the basis of aqueous solutions of diverse chemical substances. It was revealed that complex [Ho III (EDTA)] can be used as an internal or an external thermometric NMR-sensor. For identification and control of temperature in a sample one can make use of LIS for individual signals from CH 2 groups (taken in relation to water or inner DCC standard signals). A higher temperature measurement accuracy (≤0.08 K) is attained by using LIS difference corresponding to the relevant nonequivalent CH 2 groups [ru

  2. Highly sensitive, colorimetric detection of mercury(II) in aqueous media by quaternary ammonium group-capped gold nanoparticles at room temperature.

    Science.gov (United States)

    Liu, Dingbin; Qu, Weisi; Chen, Wenwen; Zhang, Wei; Wang, Zhuo; Jiang, Xingyu

    2010-12-01

    We provide a highly sensitive and selective assay to detect Hg(2+) in aqueous solutions using gold nanoparticles modified with quaternary ammonium group-terminated thiols at room temperature. The mechanism is the abstraction of thiols by Hg(2+) that led to the aggregation of nanoparticles. With the assistance of solar light irradiation, the detection limit can be as low as 30 nM, which satisfies the guideline concentration of Hg(2+) in drinking water set by the WHO. In addition, the dynamic range of detection is wide (3 × 10(-8)-1 × 10(-2) M). This range, to our best knowledge, is the widest one that has been reported so far in gold nanoparticle (AuNP)-based assays for Hg(2+).

  3. Synthesis of Novel Polymeric Resins by Gamma Irradiation for Separation of In(III) ions from Cd(II) in Aqueous Media

    International Nuclear Information System (INIS)

    Massoud, A.; Abou El-Nour, F.; Killa, H.

    2012-01-01

    In this work, Zn(II)polymethacrylates and poly(acrylamide-acrylic acid) were prepared by gamma irradiation polymerization technique of the corresponding monomer at 30 kGy. The polymeric resins were mixed with Indium ions to determine its capacity in aqueous solutions using batch experiment. The adsorption efficiency of obtained polymeric resins toward In(III) and Cd(II) in different experimental conditions was established. Batch and column methods were applied for separation of indium and cadmium. The effects of various eluants such as H 2 SO 4 , NH 4 NO 3 , HNO 3 and HCl on the recovery of both metal ions were studied. The polymeric resins may be regenerated using 3M HCl solutions.

  4. Modeling seismic stimulation: Enhanced non-aqueous fluid extraction from saturated porous media under pore-pressure pulsing at low frequencies

    Science.gov (United States)

    Lo, Wei-Cheng; Sposito, Garrison; Huang, Yu-Han

    2012-03-01

    Seismic stimulation, the application of low-frequency stress-pulsing to the boundary of a porous medium containing water and a non-aqueous fluid to enhance the removal of the latter, shows great promise for both contaminated groundwater remediation and enhanced oil recovery, but theory to elucidate the underlying mechanisms lag significantly behind the progress achieved in experimental research. We address this conceptual lacuna by formulating a boundary-value problem to describe pore-pressure pulsing at seismic frequencies that is based on the continuum theory of poroelasticity for an elastic porous medium permeated by two immiscible fluids. An exact analytical solution is presented that is applied numerically using elasticity parameters and hydraulic data relevant to recent proof-of-principle laboratory experiments investigating the stimulation-induced mobilization of trichloroethene (TCE) in water flowing through a compressed sand core. The numerical results indicated that significant stimulation-induced increases of the TCE concentration in effluent can be expected from pore-pressure pulsing in the frequency range of 25-100 Hz, which is in good agreement with what was observed in the laboratory experiments. Sensitivity analysis of our numerical results revealed that the TCE concentration in the effluent increases with the porous medium framework compressibility and the pulsing pressure. Increasing compressibility also leads to an optimal stimulation response at lower frequencies, whereas changing the pulsing pressure does not affect the optimal stimulation frequency. Within the context of our model, the dominant physical cause for enhancement of non-aqueous fluid mobility by seismic stimulation is the dilatory motion of the porous medium in which the solid and fluid phases undergo opposite displacements, resulting in stress-induced changes of the pore volume.

  5. Degradation of Acid Blue 25 in aqueous media using 1700kHz ultrasonic irradiation: ultrasound/Fe(II) and ultrasound/H(2)O(2) combinations.

    Science.gov (United States)

    Ghodbane, Houria; Hamdaoui, Oualid

    2009-06-01

    In this work, the sonolytic degradation of an anthraquinonic dye, C.I. Acid Blue 25 (AB25), in aqueous phase using high frequency ultrasound waves (1700kHz) for an acoustic power of 14W was investigated. The sonochemical efficiency of the reactor was evaluated by potassium iodide dosimeter, Fricke reaction and hydrogen peroxide production yield. The three investigated methods clearly show the production of oxidizing species during sonication and well reflect the sonochemical effects of high frequency ultrasonic irradiation. The effect of operational conditions such as the initial AB25 concentration, solution temperature and pH on the degradation of AB25 was studied. Additionally, the influence of addition of salts on the degradation of dye was examined. The rate of AB25 degradation was dependent on initial dye concentration, pH and temperature. Addition of salts increased the degradation of dye. Experiments conducted using distilled and natural waters demonstrated that the degradation was more efficient in the natural water compared to distilled water. To increase the efficiency of AB25 degradation, experiments combining ultrasound with Fe(II) or H(2)O(2) were conducted. Fe(II) induced the dissociation of ultrasonically produced hydrogen peroxide, leading to additional OH radicals which enhance the degradation of dye. The combination of ultrasound with hydrogen peroxide looks to be a promising option to increase the generation of free radicals. The concentration of hydrogen peroxide plays a crucial role in deciding the extent of enhancement obtained for the combined process. The results of the present work indicate that ultrasound/H(2)O(2) and ultrasound/Fe(II) processes are efficient for the degradation of AB25 in aqueous solutions by high frequency ultrasonic irradiation.

  6. Batch adsorptive removal of Fe(III, Cu(II and Zn(II ions in aqueous and aqueous organic–HCl media by Dowex HYRW2-Na Polisher resin as adsorbents

    Directory of Open Access Journals (Sweden)

    Abdul-Aleem Soliman Aboul-Magd

    2016-09-01

    Full Text Available Of the metal ions in tap, Nile, waste and sea water samples and some ores were carried out. Removal of heavy metal ions such as Fe(III, Cd(II, Zn(II, Cu(II, Mn(II, Mg(II, and Pb(II from water and wastewater is obligatory in order to avoid water pollution. Batch shaking adsorption experiments to evaluate the performance of nitric and hydrochloric acid solutions in the removal of metal ions by cation exchange resin at the same conditions for both, such as the effect of initial metal ion concentration, different proportions of some organic solvents, H+-ion concentrations and reaction temperature on the partition coefficients. The metal adsorption for the cation exchanger was found to be significant in different media for both nitric and hydrochloric acids, i.e., the adsorption up take of metal ions presented in this work is very significant depending on the characteristics of ions and on the external concentrations of solute. The presence of low ionic strength or low concentration of acids does have a significant adsorption of metal ions on ion-exchange resin. The results show that the ion exchanger could be employed for the preconcentration, separation and the determination.

  7. Preliminary findings of the effect of surface finish and coatings on PuO2 contamination hold-up and ease of decontamination in aqueous and non-aqueous media

    International Nuclear Information System (INIS)

    Dalton, J.T.; Chamberlain, H.E.; Turner, A.D.; Dawson, R.K.

    1984-11-01

    The application of temporary and permanent coatings for the reduction of α-activity hold-up and increased ease of decontamination has been reviewed and a variety of surface treatments and coatings identified as being worthy of investigation. A range of specimens have been prepared with hard coatings and smooth surfaces. A number of adhesive films, paints and lacquers have been applied to mild and stainless steel substrates. In order to compare the different surfaces, a standard contamination technique using a mechanical wiper has been developed to reproducibly contaminate the materials with PuO 2 . A standard decontamination test using water/Decon 75 or Arklone X is being used to compare the ease of decontamination. Preliminary experiments have shown that the smoothest surface finishes have the lowest activity hold-up and are more easily cleaned. Due to the superior level of micro-smoothness attainable on metals, these showed a significantly lower activity retention than the organic coatings examined to date. A comparison of the relative efficiency of cleaning in Decon 75 and Arklone X showed that generally speaking metal surfaces were cleaned equally well by both media, while the unaged organic surfaces were decontaminated more thoroughly in Arklone X, though the differences were somewhat marginal. (author)

  8. Photocatalytic degradation of H2S aqueous media using sulfide nanostructured solid-solution solar-energy-materials to produce hydrogen fuel.

    Science.gov (United States)

    Lashgari, Mohsen; Ghanimati, Majid

    2018-03-05

    H 2 S is a corrosive, flammable and noxious gas, which can be neutralized by dissolving in alkaline media and employed as H 2 -source by utilizing inside semiconductor-assisted/photochemical reactors. Herein, through a facile hydrothermal route, a ternary nanostructured solid-solution of iron, zinc and sulfur was synthesized in the absence and presence of Ag-dopant, and applied as efficient photocatalyst of hydrogen fuel production from H 2 S media. The effect of pH on the photocatalyst performance was scrutinized and the maximum activity was attained at pH=11, where HS - concentration is high. BET, diffuse reflectance and photoluminescence studies indicated that the ternary solid-solution photocatalyst, in comparison to its solid-solvent (ZnS), has a greater surface area, stronger photon absorption and less charge recombination, which justify its superiority. Moreover, the effect of silver-dopant on the photocatalyst performance was examined. The investigations revealed that although silver could boost the absorption of photons and increase the surface area, it could not appreciably enhance the photocatalyst performance due to its weak influence on retarding the charge-recombination process. Finally, the phenomenon was discussed in detail from mechanistic viewpoint. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Bioinspired thermo- and pH-responsive polymeric amines: multimolecular aggregates in aqueous media and matrices for silica/polymer nanocomposites.

    Science.gov (United States)

    Danilovtseva, Elena N; Aseyev, Vladimir; Belozerova, Olga Yu; Zelinskiy, Stanislav N; Annenkov, Vadim V

    2015-05-15

    Polymeric amines have been intensively studied for application in smart systems and as matrices for the design of composite materials, including bioinspired substances. A new thermo- and pH-responsive polymer was obtained by radical polymerization of N-(3-(diethylamino)propyl)-N-methylacrylamide. Upon heating, the polymer precipitated from aqueous solutions above pH 9; the observed cloud point was dependent on the polymer concentration and decreased from 95°C at pH 9 to 40°C at pH 11. The basicity of the polymer decreased at elevated temperatures owing to an increase in the hydrophobicity-driven compaction of the macromolecules. Dynamic light scattering analysis demonstrated that the formation of large multimolecular associates with radius 1000-2000 nm was initiated from 1 to 2°C below the cloud point. The new polymer is demonstrated to be an effective matrix for various siliceous composite structures, including 200-300 nm solid spherical raspberry-like particles and hollow hemispherical particles of more than 1000 nm diameter. Condensation of silicic acid in the presence of polymeric amines is a model reaction in biosilicification studies, and the obtained data are also discussed from the perspective of the matrix hypothesis for biosilica formation. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Analysis of the interactions between human serum albumin/amphiphilic penicillin in different aqueous media: an isothermal titration calorimetry and dynamic light scattering study

    International Nuclear Information System (INIS)

    Barbosa, Silvia; Taboada, Pablo; Mosquera, Victor

    2005-01-01

    The complexation process of the amphiphilic penicillins sodium cloxacillin and sodium dicloxacillin with the protein human serum albumin (HSA) in aqueous buffered solutions of pH 4.5 and 7.4 at 25 o C was investigated through isothermal titration calorimetry (ITC) and dynamic light scattering. ITC experiments were carried out in the very dilute regime and showed that although hydrophobic interactions are the leading forces for complexation, electrostatic interactions also play an important role. The possibility of the formation of hydrogen bonds is also deduced from experimental data. The thermodynamic quantities of the binding mechanism, i.e, the enthalpy, ΔHITCi, entropy, ΔSITCi, Gibbs energy, ΔGITCi, binding constant, KITCi and the number of binding sites, n i , were obtained. The binding was saturable and is characterised by Langmuir adsorption isotherms. From ITC data and following a theoretical model, the number of bound and free penicillin molecules was calculated. From Scatchard plots, KITCi and n i were obtained and compared with those from ITC data. The interaction potential between the HSA-penicillin complexes and their stability were determined at pH 7.4 from the dependence of the diffusion coefficients on protein concentration by application of the DLVO colloidal stability theory. The results indicate decreasing stability of the colloidal dispersion of the drug-protein complexes with increase in the concentration of added drug

  11. Graphene Oxide-terpyridine Conjugate: A Highly Selective Colorimetric and Sensitive Fluorescence Nano-chemosensor for Fe2+ in Aqueous Media

    Directory of Open Access Journals (Sweden)

    Bagher Eftekhari-Sis

    2016-07-01

    Full Text Available A graphene oxide-terpyridine conjugate (GOTC based colorimetric and fluorescent nano-chemosensor was synthesized. It showed high selectivity and sensitivity for Fe2+ and Fe3+ ions in neutral aqueous solution over other metal ions such as Li+, Na+, Ba2+, Ca2+, Al3+, Cd2+, Co2+, Cu2+, Hg2+, Mn2+, Ni2+, Pb2+, Zn2+, Cr3+ and Ag+. In absorption spectra, upon addition of Fe2+ or Fe3+, the sensor displayed a peak at 568 nm, by changing the color of the solution from light pink for GOTC to light magenta and deep magenta for Fe3+ and Fe2+, respectively. Also, the fluorescence studies revealed that, Fe2+, Fe3+ and Co2+ quench the emission of GOTC at 473 nm, while other metal ions do not quench the fluorescence of GOTC in solution. Colorimetric and fluorescence techniques could be used for detection of Fe2+ ion concentration at least about 6-10 μM in water solution. The sensing on test paper was also investigated for the naked-eye detection of Fe2+.

  12. Carbon-dot-based fluorescent turn-on sensor for selectively detecting sulfide anions in totally aqueous media and imaging inside live cells.

    Science.gov (United States)

    Hou, Xianfeng; Zeng, Fang; Du, Fangkai; Wu, Shuizhu

    2013-08-23

    Sulfide anions are generated not only as a byproduct from industrial processes but also in biosystems. Hence, robust fluorescent sensors for detecting sulfide anions which are fast-responding, water soluble and biocompatible are highly desirable. Herein, we report a carbon-dot-based fluorescent sensor, which features excellent water solubility, low cytotoxicity and a short response time. This sensor is based on the ligand/Cu(II) approach so as to achieve fast sensing of sulfide anions. The carbon dot (CD) serves as the fluorophore as well as the anchoring site for the ligands which bind with copper ions. For this CD-based system, as copper ions bind with the ligands which reside on the surface of the CD, the paramagnetic copper ions efficiently quench the fluorescence of the CD, affording the system a turn-off sensor for copper ions. More importantly, the subsequently added sulfide anions can extract Cu(2+) from the system and form very stable CuS with Cu(2+), resulting in fluorescence enhancement and affording the system a turn-on sensor for sulfide anions. This fast-responding and selective sensor can operate in totally aqueous solution or in physiological milieu with a low detection limit of 0.78 μM. It displays good biocompatibility, and excellent cell membrane permeability, and can be used to monitor S(2-) levels in running water and living cells.

  13. In vitro erythemal UV-A protection factors of inorganic sunscreens distributed in aqueous media using carnauba wax-decyl oleate nanoparticles.

    Science.gov (United States)

    Villalobos-Hernández, J R; Müller-Goymann, C C

    2007-01-01

    This paper describes the in vitro photoprotection in the UV-A range, i.e. 320-400 nm obtained by the use of carnauba wax-decyl oleate nanoparticles either as encapsulation systems or as accompanying vehicles for inorganic sunscreens such as barium sulfate, strontium carbonate and titanium dioxide. Lipid-free inorganic sunscreen nanosuspensions, inorganic sunscreen-free wax-oil nanoparticle suspensions and wax-oil nanoparticle suspensions containing inorganic sunscreens dispersed either in their oil phase or their aqueous phase were prepared by high pressure homogenization. The in vitro erythemal UV-A protection factors (EUV-A PFs) of the nanosuspensions were calculated by means of a sun protection analyzer. EUV-A PFs being no higher than 4 were obtained by the encapsulation of barium sulfate and strontium carbonate, meanwhile by the distribution of titanium dioxide in presence of wax-oil nanoparticles, the EUV-A PFs varied between 2 and 19. The increase in the EUV-A PFs of the titanium dioxide obtained by the use of wax-oil nanoparticles demonstrated a better performance of the sun protection properties of this pigment in the UV-A region.

  14. Synthesis and self-assembly behavior of amphiphilic diblock copolymer dextran-block-poly(ε-caprolactone (DEX-b-PCL in aqueous media

    Directory of Open Access Journals (Sweden)

    2010-10-01

    Full Text Available An amphiphilic diblock copolymer, dextran-block-poly(ε-caprolactone (DEX-b-PCL, with a series of welldefined chain lengths of each block was prepared by conjugating a dextran chain with a PCL block via aza-Michael addition reaction under mild conditions. For the dextran block, samples with relatively uniform molecular weight, 3.5 and 6.0 kDa, were used, and the PCL blocks were prepared via ring-opening polymerization at defined ratios of ε-caprolactone to initiator in order to give copolymers with mass fraction of dextran (fDEX ranging from 0.16 to 0.45. When these copolymers were allowed to self-assemble in aqueous solution, the morphology of assembled aggregates varied as a function of fDEX when characterized by transmission electron microscope (TEM, fluorescence microscope (FM and dynamic laser scattering (DLS. As fDEX decreases gradually from 0.45 to 0.16, the morphology of the copolymer assembly changes from spherical micelles to worm-like micelles and eventually to polymersomes, together with an increase in particle sizes.

  15. Sorption behaviour of uranium and thorium on hydrons tin oxide from aqueous and mixed-solvent H2SO4 media

    International Nuclear Information System (INIS)

    Misak, N.Z.; Salema, H.N.; El-Naggar, J.M.

    1983-01-01

    At pH values > about 2 in 10 -3 -10 -2 M aqueous sulphate solutions, uranium seems to be sorbed by hydrous tin oxide mainly as cations, while thorium is sorced as cations and as the neutral complex. At pH values of about 1.1-1.4, both uranium and thorium seem to be mainly sorbed as the neutral complexes. while at lower pH values, sorption of anionic commplexes comes into play. The sorption of uranium generally increased progressively on addition of increasing amounts of methanol, ethanol or acetone. The sorption of thorium decreases a little at 0.01 N H 2 SO 4 and increases a little at 0.5 N H 2 SO 4 on adding the organic solvents. At 0.1 N H 2 SO 4 , the addition of 20percent of the organic solvents brings the sorption of thorium to almost negligible values, which seems to offer an attractive means for U/Th separation. (author)

  16. Extraction of molybdenum by the di-n-butyl 2.2.N.hydroxyhexanamide (tri-n-butylacetohydroxamic acid) from aqueous acidic media

    International Nuclear Information System (INIS)

    Landesman, C.

    1991-11-01

    The design of a new industrial process for the production of the fission product 99 Mo, led to study of the extraction of 99 Mo(VI) by the tri-n-butylacetohydroxamic acid (TBAH). Due to the large affinity of TBAH for Mo(VI), the study was conducted with unusual experimental conditions : the concentrations of the extracting molecule and metallic ion were very low, typically CTBAH = 10 -5 M and CMo(VI) = 10 -8 M. The overall extraction system was described using a mathematical model quite simple, which, in particular, takes into account all the Mo(VI) species present in the aqueous phase. When the extractions were carried out from a perchloric acid medium, two different extraction mechanisms of Mo(VI) were identified : for C HC10 4 3 , the extraction of Mo(VI) corresponds to a cationic exchange, whereas for C HC10 4 > 3 mol/dm 3 , a neutral Mo(VI) compound is extracted. Moreover it was found that the extracting system Mo(VI)/TBAH is extremely sensitive to the temperature. It is thus possible to change the way of the transfer of Mo(VI) between the two phases, by control of the temperature of the mixture : the extraction is carried out at room temperature and the back-extraction at elevated temperature

  17. Influence of aqueous media properties on aggregation and solubility of four structurally related meso-porphyrin photosensitizers evaluated by spectrophotometric measurements.

    Science.gov (United States)

    Sobczyński, J; Tønnesen, H H; Kristensen, S

    2013-02-01

    Porphyrin photosensitizers tend to aggregate in aqueous solutions even in the micromolar concentration range. This is a challenge during formulation of e.g., parenteral preparations for photodynamic cancer therapy, or preparations for local or topical administration in antimicrobial photodynamic therapy. Monomerization is essential to achieve biocompatible drug formulations of high bioavailability and physiological response (i.e., photoreactivity) and low toxicity. The aggregation and solubilization of four structurally related meso-tetraphenyl porphyrin photosensitizers with nonionic (4-hydroxy), anionic (4-sulphonate; 4-carboxy) and cationic (4-trimethylanilinium) substituents were evaluated in various vehicles by use of UV-Vis spectroscopy. Substituents, overall charge and charge distribution influenced the pKa-values and interaction of the porphyrins with different solvents, excipients and impurities. Modification of medium polarity and solubilization by the nonionic surfactant Tween 80 adjusted the acid-base equilibria and increased the solubility by reduction of porphyrin aggregation. The selected porphyrins were sensitive towards ionic strength, temperature and inorganic impurities to various extents. The results will be further used during development of parenteral and topical formulations of porphyrin photosensitizers for use in photodynamic therapy of cancer and bacterial infections.

  18. Synthesis of pure colloidal silver nanoparticles with high electroconductivity for printed electronic circuits: the effect of amines on their formation in aqueous media.

    Science.gov (United States)

    Natsuki, Jun; Abe, Takao

    2011-07-01

    This paper describes a practical and convenient method to prepare stable colloidal silver nanoparticles for use in printed electronic circuits. The method uses a dispersant and two kinds of reducing agents including 2-(dimethylamino) ethanol (DMAE), which play important roles in the reduction of silver ions in an aqueous medium. The effect of DMAE and dispersant, as well as the factors affecting particle size and morphology are investigated. In the formation of the silver nanoparticles, reduction occurs rapidly at room temperature and the silver particles can be separated easily from the mixture in a short time. In addition, organic solvents are not used. Pure, small and relatively uniform particles with a diameter less than 10 nm can be obtained that exhibit high electroconductivity. The silver nanoparticles are stable, and can be isolated as a dried powder that can be fully redispersed in deionized water. This method of producing colloidal silver nanoparticles will find practical use in electronics applications. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. Hemoglobin bioconjugates with surface-protected gold nanoparticles in aqueous media: The stability depends on solution pH and protein properties.

    Science.gov (United States)

    Del Caño, Rafael; Mateus, Lucia; Sánchez-Obrero, Guadalupe; Sevilla, José Manuel; Madueño, Rafael; Blázquez, Manuel; Pineda, Teresa

    2017-11-01

    The identification of the factors that dictate the formation and physicochemical properties of protein-nanomaterial bioconjugates are important to understand their behavior in biological systems. The present work deals with the formation and characterization of bioconjugates made of the protein hemoglobin (Hb) and gold nanoparticles (AuNP) capped with three different molecular layers (citrate anions (c), 6-mercaptopurine (MP) and ω-mercaptoundecanoic acid (MUA)). The main focus is on the behavior of the bioconjugates in aqueous buffered solutions in a wide pH range. The stability of the bioconjugates have been studied by UV-visible spectroscopy by following the changes in the localized surface resonance plasmon band (LSRP), Dynamic light scattering (DLS) and zeta-potential pH titrations. It has been found that they are stable in neutral and alkaline solutions and, at pH lower than the protein isoelectric point, aggregation takes place. Although the surface chemical properties of the AuNPs confer different properties in respect to colloidal stability, once the bioconjugates are formed their properties are dictated by the Hb protein corona. The protein secondary structure, as analyzed by Attenuated total reflectance infrared (ATR-IR) spectroscopy, seems to be maintained under the conditions of colloidal stability but some small changes in protein conformation take place when the bioconjugates aggregate. These findings highlight the importance to keep the protein structure upon interaction with nanomaterials to drive the stability of the bioconjugates. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Physical stability, centrifugation tests, and entrapment efficiency studies of carnauba wax-decyl oleate nanoparticles used for the dispersion of inorganic sunscreens in aqueous media.

    Science.gov (United States)

    Villalobos-Hernández, J R; Müller-Goymann, C C

    2006-06-01

    Aqueous nanoscale lipid dispersions consisting of carnauba wax-decyl oleate mixtures acting as carriers or accompanying vehicles for inorganic sunscreens such as barium sulfate, strontium carbonate, and titanium dioxide were prepared by high pressure homogenization. For the manufacture of these nanosuspensions, three pigment concentrations (%wt), namely 2, 4, and 6, and two carnauba wax-decyl oleate ratios, 1:1 and 2:1, were used, being some of these combinations chosen for stability studies. Six-month physical stability tests at 4, 20, and 40 degrees C selecting the mean particle size and the polydispersity index of the nanosuspensions as reference parameters were performed. Centrifugation tests of the nanosuspensions assessed by transmission electron microscopy and by the determination of the content of pigments and carnauba wax in the separated fractions were done. The mean particle sizes and the polydispersity indices of the nanosuspensions were not altered after six-month storages at 20 and at 40 degrees C. However, the storage of those at 4 degrees C considerably increased the particle size and polydispersity of the systems, particularly when wax-oil ratios (2:1) were used for the entrapment of the pigments. Transmission electron micrographs of centrifuged samples denoted the presence of three major fractions showing the different types of particles integrated into the nanosuspensions. Furthermore, it was observed that not all the carnauba wax participated in the entrapment of the pigment. Regarding the amount of pigment being encapsulated or bonded by the wax-oil matrices, entrapment efficiencies higher than 85.52% were reported.

  1. Iron-based magnetic molecular imprinted polymers and their application in removal and determination of di-n-pentyl phthalate in aqueous media.

    Science.gov (United States)

    Li, Jing; Zhou, Qingxiang; Yuan, Yongyong; Wu, Yalin

    2017-08-01

    Iron-based magnetic molecular imprinted polymers (Fe@SiO 2 @MIP) were synthesized for highly selective removal and recognition of di- n -pentyl phthalate (DnPP) from water. Well-defined core-shell Fe@SiO 2 nanoparticles (less than 70 nm) were decorated on MIPs reticular layers to endow DnPP-MIPs with magnetic property for the first time. Five other phthalic acid esters including dimethyl phthalate, diethyl phthalate, dipropyl phthalate, di- n -butyl phthalate and di-iso-octyl phthalate were used to investigate the adsorptive selectivity to DnPP. The designed experiments were carried out to explore the adsorption kinetics, isotherms and thermodynamics and the results demonstrated that the adsorption was a spontaneous, exothermal and physical adsorption process. The materials were proved to be excellent adsorbents in removal of DnPP with an adsorption capacity as high as 194.15 mg g -1 in optimal condition. Furthermore, a magnetic solid phase extraction with Fe@SiO 2 @MIP coupled to high-performance liquid chromatography method was successfully developed for the determination of DnPP, and the proposed method achieved a good linear range of 0.5-250 µg l -1 with a correlation coefficient ( R 2 ) of 0.999 and low limit of detection (LOD) of 0.31 µg l -1 . These materials exhibited excellent capacity in removal and highly sensitive identification of DnPP from aqueous environment samples, and opened a valuable direction for developing new adsorbents for the removal and enrichment of important pollutants.

  2. A Clean, Mild, and Efficient Preparation of Aryl 14H-benzo[a,j]xanthene leuco-dye Derivatives Via Nanocatalytic MCM-41-SO3H Under Ultrasonic Irradiation in Aqueous Media.

    Science.gov (United States)

    Fathollahi, Mostafa; Rostamizadeh, Shahnaz; Amani, Ali M

    2018-01-01

    The present study has developed an efficient and eco-friendly protocol for the synthesis of aryl-14-H-dibenzo[a,j] xanthenes through a one-pot condensation reaction of 2-naphthol and arylaldehydes in aqueous media using the nanocatalytic MCM-41-SO3H under ultrasonic illumination. Using SEM and XRD analyses, MCM-41-SO3H nanoparticles were characterized. Therefore, for high magnification, taking the SEM image, the mesoporous surface of MCM-41-SO3H nanoparticles coated with gold for 2 minutes was characterized. Moreover, at a scan rate of 0.02° (2θ)/sec, XRD analysis from 1.5° (2θ) to 10.0° (2θ) was performed. For our considered sample, some well-ordered XRD patterns with one main peak as well as three minor peaks equal to those of MCM-41 materials were observed. The suggested route demonstrates very promising properties like higher yields, decrease in the time of reaction (5-10 min), mild and straightforward conditions, low level of toxicity, and inclusion of a cost-efficient and ecofriendly catalyst having considerable reusability. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  3. Thermometric nanosize NMR-sensors for temperature determination in weakly polar non-aqueous media on the base of ion pairs of paramagnetic complexes of lanthanides(III)

    International Nuclear Information System (INIS)

    Babajlov, S.P.

    2008-01-01

    For temperature determination in solutions it is suggested that the temperature dependence of the paramagnetic lanthanide-induced shifts (LIS) in the NMR spectra on the ligand nuclei be used for [Ln(PTA) 2 (18-crown-6)] + [Ln(PTA) 4 ] - complex ion pairs formed in CCl 4 , CDCl 3 , CD 2 Cl 2 , CD 3 C 6 D 5 , and C 2 D 3 N type low-polar solvents (Ln = La, Ce, Pr, Nd, Eu; PTA is the pivalyltrifluoroacetonate anion). It was found experimentally that the [Ln(PTA) 2 (18-crown-6)] + complex cation molecules (Ln = Ce and Pr) proved most suitable for use as nanosized (∼1.1 nm) probes for temperature determinations in nonaqueous solutions. A linear dependence of the LIS on the 1 H nuclei of different groups and the difference between the LIS corresponding to the CH 2 groups of the 18-crown-6 molecules and the CH groups of the PTA anions on the reciprocal temperature (1/T) was found. The LIS of the individual signals of different groups in Ln paramagnetic complexes (relative to the signals of the diamagnetic analogs, e.g., La or Lu) may be used for temperature control in the sample, although the temperature measurement error is smaller (≤0.04 K) when the difference between the LIS of the CH 2 and CH groups is used. Due to the high thermodynamic and kinetic stability combined with small sizes of [Ln(PTA) 2 (18-crown-6)] + [Ln(PTA) 4 ] - molecules in nonaqueous solutions, these compounds may be used as thermometric NMR sensors directly in reaction media for in situ control over temperature [ru

  4. Differentiation and characterization of isotopically modified silver nanoparticles in aqueous media using asymmetric-flow field flow fractionation coupled to optical detection and mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Gigault, Julien [National Institute of Standards and Technology, Material Measurement Laboratory, 100 Bureau Drive Stop 8520, Gaithersburg, MD 20899-8520 (United States); Hackley, Vincent A., E-mail: vince.hackley@nist.gov [National Institute of Standards and Technology, Material Measurement Laboratory, 100 Bureau Drive Stop 8520, Gaithersburg, MD 20899-8520 (United States)

    2013-02-06

    Highlights: ► Isotopically modified and unmodified AgNPs characterization by A4F-DAD-MALS–DLS-ICP-MS. ► Size-resolved characterization and speciation in simple or complex media. ► Capacity to detect stable isotope enriched AgNPs in a standard estuarine sediment. ► New opportunities to monitor and study fate and transformations of AgNPs. -- Abstract: The principal objective of this work was to develop and demonstrate a new methodology for silver nanoparticle (AgNP) detection and characterization based on asymmetric-flow field flow fractionation (A4F) coupled on-line to multiple detectors and using stable isotopes of Ag. This analytical approach opens the door to address many relevant scientific challenges concerning the transport and fate of nanomaterials in natural systems. We show that A4F must be optimized in order to effectively fractionate AgNPs and larger colloidal Ag particles. With the optimized method one can accurately determine the size, stability and optical properties of AgNPs and their agglomerates under variable conditions. In this investigation, we couple A4F to optical absorbance (UV–vis spectrometer) and scattering detectors (static and dynamic) and to an inductively coupled plasma mass spectrometer. With this combination of detection modes it is possible to determine the mass isotopic signature of AgNPs as a function of their size and optical properties, providing specificity necessary for tracing and differentiating labeled AgNPs from their naturally occurring or anthropogenic analogs. The methodology was then applied to standard estuarine sediment by doping the suspension with a known quantity of isotopically enriched {sup 109}AgNPs stabilized by natural organic matter (standard humic and fulvic acids). The mass signature of the isotopically enriched AgNPs was recorded as a function of the measured particle size. We observed that AgNPs interact with different particulate components of the sediment, and also self-associate to form

  5. Synthesis and characterization of porous calcium phosphate; Sintesis y caracterizacion del fosfato de calcio poroso

    Energy Technology Data Exchange (ETDEWEB)

    Granados C, F.; Serrano G, J.; Bonifacio M, J. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)]. e-mail: fgc@nuclear.inin.mx

    2007-07-01

    The porous calcium phosphate was prepared by the continuous precipitation method using Ca(NO{sub 3}){sub 2}.4H{sub 2}O and NH{sub 4}H{sub 2}PO{sub 4} salts. The synthesized material was structurally and superficially characterized using the XRD, BET, IR TGA and SEM techniques. The obtained inorganic material was identified as calcium phosphate that presents a great specific area for what can be efficiently used as adsorbent material for adsorption studies in the radioactive wastes treatment present in aqueous solution. (Author)

  6. Ce–Fe-modified zeolite-rich tuff to remove Ba{sup 2+}-like {sup 226}Ra{sup 2+} in presence of As(V) and F{sup −} from aqueous media as pollutants of drinking water

    Energy Technology Data Exchange (ETDEWEB)

    Olguín, María Teresa, E-mail: teresa.olguin@inin.gob.mx [Department of Chemical & Materials Engineering, New Mexico State University, P.O. Box 30001, MSC 3805, Las Cruces, NM 88003 (United States); Departamento de Química, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, Col. Escandón, Delegación Miguel Hidalgo, C.P. 11801, México D.F. (Mexico); Deng, Shuguang [Department of Chemical & Materials Engineering, New Mexico State University, P.O. Box 30001, MSC 3805, Las Cruces, NM 88003 (United States)

    2016-01-25

    Graphical abstract: Ba{sup 2+}-like {sup 226}Ra{sup 2+}, As(V) and F{sup −} simultaneous removal from aqueous media by Ce–Fe-modified natural zeolites. - Highlights: • The metallic species which modified the zeolite change the textural properties. • The pH{sub pzc} is acid for ZUSCeFe and neutral for ZUSNa. • The Linear model describes the Ba{sup 2+}-like {sup 226}Ra{sup 2+} sorption by ZUSNa and ZUSCeFe. • K{sub d} is highest for Ba{sup 2+-} like {sup 226}Ra{sup 2+}-As(V)-F{sup -} solution in contact with ZUSCeFe. • The ZUSCeFe remove simultaneously Ba{sup 2+}-like {sup 226}Ra{sup 2+}, As(V) and F{sup −}. - Abstract: The sorption behavior of the Ba{sup 2+}-like {sup 226}Ra{sup 2+} in the presence of H{sub 2}AsO{sub 4}{sup −}/HAsO{sub 4}{sup 2−} and F{sup −} from aqueous media using Ce–Fe-modified zeolite-rich tuff was investigated in this work. The Na-modified zeolite-rich tuff was also considered for comparison purposes. The zeolite-rich tuff collected from Wyoming (US) was in contact with NaCl and CeCl{sub 3}–FeCl{sub 3} solutions to obtain the Na- and Ce–Fe-modified zeolite-rich tuffs (ZUSNa and ZUSCeFe). These zeolites were characterized by scanning electron microscopy and X-ray diffraction. The BET-specific surface and the points of zero charge were determined as well as the content of Na, Ce and Fe by neutron activation analysis. The textural characteristics and the point of zero charge were changed by the presence of Ce and Fe species in the zeolitic network. A linear model described the Ba{sup 2+}-like {sup 226}Ra{sup 2+} sorption isotherms and the distribution coefficients (K{sub d}) varied with respect to the metallic species present in the zeolitic material. The As(V) oxianionic chemical species and F{sup −} affected this parameter when the Ba{sup 2+}-like {sup 226}Ra{sup 2+}-As(V)-F{sup −} solutions were in contact with ZUSCeFe. The H{sub 2}AsO{sub 4}{sup −}/HAsO{sub 4}{sup 2−} and F{sup −} were adsorbed by ZUSCe

  7. Ce-Fe-modified zeolite-rich tuff to remove Ba(2+)-like (226)Ra(2+) in presence of As(V) and F(-) from aqueous media as pollutants of drinking water.

    Science.gov (United States)

    Olguín, María Teresa; Deng, Shuguang

    2016-01-25

    The sorption behavior of the Ba(2+)-like (226)Ra(2+) in the presence of H2AsO4(-)/HAsO4(2-) and F(-) from aqueous media using Ce-Fe-modified zeolite-rich tuff was investigated in this work. The Na-modified zeolite-rich tuff was also considered for comparison purposes. The zeolite-rich tuff collected from Wyoming (US) was in contact with NaCl and CeCl3-FeCl3 solutions to obtain the Na- and Ce-Fe-modified zeolite-rich tuffs (ZUSNa and ZUSCeFe). These zeolites were characterized by scanning electron microscopy and X-ray diffraction. The BET-specific surface and the points of zero charge were determined as well as the content of Na, Ce and Fe by neutron activation analysis. The textural characteristics and the point of zero charge were changed by the presence of Ce and Fe species in the zeolitic network. A linear model described the Ba(2+)-like (226)Ra(2+) sorption isotherms and the distribution coefficients (Kd) varied with respect to the metallic species present in the zeolitic material. The As(V) oxianionic chemical species and F(-) affected this parameter when the Ba(2+)-like (226)Ra(2+)-As(V)-F(-) solutions were in contact with ZUSCeFe. The H2AsO4(-)/HAsO4(2-) and F(-) were adsorbed by ZUSCeFe in the same amount, independent of the concentration of Ba(2+)-like (226)Ra(2+) in the initial solution. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Fate of Nanoparticles in Aqueous Media

    Science.gov (United States)

    Labille, Jérôme; Bottero, Jean-Yves

    The European Commission estimated the world nanotechnology market at slightly over 40 billion euros in 2001. In 2010-2015, according to the estimates of the US National Science Foundation (NSF), the worldwide economic stakes due to the advent of nanotechnology could run as high as 1 000 billion dollars per year across all sectors [1]. This growth is founded on the multitude of potential applications of nanotechnologies. Considering the exponential increase in mass production of nanomaterials that this implies, it becomes important to ask what would become of such materials should they be released into the environment. Indeed, nanoparticles are very small, comparable in size to a virus, suggesting a high level of mobility in the environment and living organisms, down to the smallest length scale, that is, internalisation by living cells. For this reason, investigations into this specific problem, underway since the beginning of the 2000s when nanotechnology came into its own, must be organised upstream if possible, but at worst in parallel with research and development, and as far as possible in collaboration with it.

  9. Chromium removal from aqueous media by superparamagnetic ...

    Indian Academy of Sciences (India)

    1. Introduction. Industrial wastewater often contains substantial amount ... sion, it is imperative that industries reduce chromium in their effluents to this ..... in standard Gibb's free energy ( Go), enthalpy ( Ho), ... ideal gas constant and T is temperature. Table 3 dis ... sequence of increase in access to functional groups afforded ...

  10. Flow of Aqueous Humor

    Science.gov (United States)

    ... Home Flow of Aqueous Humor Flow of Aqueous Humor Most, but not all, forms of glaucoma are ... remains normal when some of the fluid (aqueous humor) produced by the eye's ciliary body flows out ...

  11. REMOVAL OF LEAD(II) IONS FROM AQUEOUS SOLUTIONS ...

    African Journals Online (AJOL)

    Preferred Customer

    lung cancer, convulsion and even death if ingested at elevated levels. ... osmosis have been used for removing heavy metal ions from aqueous media [4-6]. ... organic molecules and silica surface functions, (ii) chlorination of the silica surface ...

  12. Cast iron deterioration with time in various aqueous salt solutions

    Indian Academy of Sciences (India)

    Unknown

    various aqueous salt solutions have been carried out using total immersion test ... circuit potential, Icorr, Tafel slopes, corrosion rate, have been calculated by standard methods. ..... Rao B V S 1980 in Maintenance for reliability (Bombay: Media.

  13. SOCIAL MEDIA

    Science.gov (United States)

    RESPONSIBILITY CENTCOM COALITION MEDIA SOCIAL MEDIA NEWS ARTICLES PRESS RELEASES IMAGERY VIDEOS TRANSCRIPTS VISITORS AND PERSONNEL FAMILY CENTER FAMILY READINESS CENTCOM WEBMAIL SOCIAL MEDIA SECURITY ACCOUNTABILITY HomeMEDIASOCIAL MEDIA Social Media CENTCOM'S ENGLISH SOCIAL MEDIA ACCOUNTS There are many U.S. military commands

  14. SINTESIS FOSFOLIPID MENGANDUNG ASAM LEMAK w-3 DARI FOSFOLIPID KEDELAI DAN MINYAK KAYA ASAM LEMAK w-3 DARI HASIL SAMPING PENGALENGAN TUNA

    Directory of Open Access Journals (Sweden)

    Teti Estiasih

    2013-03-01

    Full Text Available Synthesis of Phospholipid Containing w-3 Fatty Acids from Soy Phospholipidsand Fish Oil Enriched with w-3 Fatty Acids from Tuna Canning Processing Teti Estiasih, Moch. Nur, Jaya Mahar Maligan, Satrio Maulana ABSTRAK Keunggulan fosfolipid dapat ditingkatkan dengan menggabungkan asam lemak w-3, terutama EPA (eicosapentaenoicacid, C20:5w-3 dan DHA (docosahexaenoic acid, C22:6w-3, pada struktur fosfolipid sehingga diperoleh fosfolipidterstruktur. Strukturisasi fosfolipid kedelai komersial dilakukan dengan cara mengganti asam lemak dari fosfolipidkedelai dengan asam lemak w-3 dari minyak kaya asam lemak w-3 dari hasil samping pengalengan tuna. Sintesisfosfolipid terstruktur dilakukan secara asidolisis enzimatis dengan menggunakan lipase dari R. miehei. Faktor yangdikaji pada proses sintesis ini adalah konsentrasi enzim dan lama sintesis. Tingkat inkorporasi EPA dan DHA padastruktur fosfolipid dipengaruhi oleh konsentrasi enzim. Pada konsentrasi enzim yang rendah, peningkatan lama reaksisetelah tingkat inkoporasi optimum tercapai cenderung menyebabkan penurunan tingkat inkorporasi EPA+DHA. Padakonsentrasi enzim yang tinggi, lama reaksi tampaknya tidak mempengaruhi tingkat inkorporasi. Tingkat inkorporasiDHA lebih tinggi dari EPA sehingga fosfolipid terstruktur yang dihasilkan sangat sesuai digunakan untuk produk panganyang memerlukan kadar DHA tinggi. Ada preferensi inkorporasi EPA+DHA pada fosfatidiletanolamin dibandingkanjenis fosfolipid yang lain.Kata kunci: Fosfolipid terstruktur, asam lemak w-3, EPA, DHA, asidolisis enzimatis ABSTRACT The superiority of soy phospholipids could be obtained by incorporation of w-3 fatty acids into phospholipids structure,especially EPA (eicosapentaenoic acid, C20:5w-3 and DHA docosahexaenoic acid, C22:6w-3. Structurization ofcommercial soy phospholipids was conducted by replacement of natural fatty acids in soy phospholipids by w-3 fattyacids from w-3 fatty acids enriched Þ sh oil from tuna canning processing

  15. Analisis Hasil Sintesis Serbuk TiO2 / ZnO sebagai Lapisan Elektroda untuk Aplikasi Dye-sensitized Solar Cell

    Directory of Open Access Journals (Sweden)

    Lilis Retnaningsih

    2016-06-01

    Full Text Available Pada penelitian ini telah dilakukan sintesis antara serbuk partikel nano TiO2 dan serbuk partikel nano ZnO menjadi pasta yang akan diaplikasikan sebagai elektroda pada dye-sensitized solar cell (DSSC. Elektroda pada DSSC ini bekerja berdasarkan adsorbsi foton oleh pewarna, elektron yang tereksitasi ditransfer ke TiO2/ZnO yang mempunyai perbandingan berbeda. Dimensi material partikel nano TiO2/ZnO sebagai elektroda sangat penting untuk menghasilkan efisiensi yang lebih tinggi pada DSSC. Sifat ini sangat dipengaruh oleh metoda pabrikasi elektroda TiO2/ZnO dan parameternya. Pada penelitian ini digunakan metoda doctor blade untuk pabrikasi DSSC dan larutan dyes (Z907 sebagai zat pewarna. Tujuan penelitian ini adalah untuk mengetahui pengaruh pencampuran serbuk TiO2 dan serbuk ZnO sebagai elektroda. Teknik pembuatan pasta TiO2/ZnO sebagai elektroda sangat penting untuk menghasilkan efisiensi tinggi pada DSSC. Teknik ini sangat terkait dengan material TiO2/ZnO, metoda pabrikasi, dan parameter pengukurannya. Dalam penelitian ini dibahas hasil karakterisasi XRD pada kedua serbuk TiO2 dan ZnO, hasil SEM pada pencampuran kedua material, hasil pengujian IPCE serta hasil pengukuran effisiensi pada pengujian I - V.

  16. Technological development for the synthesis of Captan and Folpet in Mexico; Desarrollo tecnologico para la sintesis de Captan y Folpet en Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Haro C, Jorge A [Universidad Autonoma Metropolitana-Iztapalapa, Mexico, D.F. (Mexico); Romero M, Artemisa; James M, Guillermo [Universidad Autonoma Metropolitana-Xochimilco, Mexico, D.F. (Mexico); Santos de Flores, Elvira [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)

    1995-02-01

    A technological development is presented for the production of Captan (3a, 4, 7, 7a-tetrahydro-2-[(tri-chlo-romethyl) thio]-1 H-isoindol-1, 3 (2H)-dione) and Folpet (2-(Trichloromethyl)- thio- 1 H-isoindol-1, 3-(2H)-dione), protectan fungicides for stored cereals, starting front national raw materials made in Mexico. These compounds are used for the grain protection stored in warehouse, that count the advantage of being degradables and little toxic. [Spanish] En este trabajo presentamos la adaptacion de la tecnologia a nivel laboratorio, para la sintesis de los fungicidas Captan (3a, 4, 7, 7a- te-trahidro-2-[(triclorometril) tio]-1H-iso-indol-1, 3 (2H)-diona) y Folpet (2-(tricloro-metil)-tio-1 H-isoindol-1, 3- (2H)- diona) a partir de materias primas fabricadas en Mexico. Estos compuestos son empleados para la proteccion de granos almacenados en bodega, que cuentan con la ventaja de ser degradables y poco toxicos.

  17. La sintesi einsteiniana

    CERN Document Server

    Born, Max

    1969-01-01

    Geometria e cosmologia ; le leggi fondamentali della meccanica classica ; l'universo di Newton ; le leggi fondamentali dell'ottica ; le leggi fondamentali dell'elettrodinamica ; il principio di relatività speciale di Einstein ; la teoria della relatività generale di Einstein.

  18. Streaming: A Media Hydrography of Televisual Flows

    Directory of Open Access Journals (Sweden)

    Ghislain Thibault

    2015-09-01

    Full Text Available This paper focuses on the continuities, rather than the ruptures, between digital television and past media forms. It situates the metaphor of “streaming” in contrast to and connection with previous fluid metaphors that have been used to describe different models of media transmission. From the early use of aqueous vocabulary that shaped popular and scientific understandings of electricity transmission to the seminal studies of mass communication concerning the flows of information, images of fluidity have long shaped cultural understandings of the inner logics of media infrastructures. Building on the work of media archaeologist Erkki Huhtamo, I approach these metaphors as “recurrent topoi” in media culture.

  19. Effect of {alpha}-Particle and X-Ray Irradiation on DNA Synthesis in Tissue Cultures; Effet de l'Irradiation par les Particules a et par les Rayons X sur la Synthese de l'ADN dans des Cultures de Tissus; 0412 043b 0438 044f 0414 ; Efectos de la Irradiacion con Particulas Alfa y con Rayos X sobre la Sintesis de ADN en Cultivos de Tejidos

    Energy Technology Data Exchange (ETDEWEB)

    Smith, C. L. [Department of Radiotherapeutics, University of Cambridge, Cambridge (United Kingdom)

    1962-02-15

    lesions subies par la structure type de l'ADN (ou du phosphate de l'ADN) pendant la phase exponentielle dela synthese, les observations formulees plus haut sous 1, 2 et 3 constituent les corollaires evidents de ce phenomene. (author) [Spanish] La memoria describe los efectos de las particulas {alpha} y de los rayos X sobre la velocidad de sintesis del ADN en cultivos de tejidos de fibroblastos y de celulas de HeLa del raton. Los autores emplearon el metodo de la microautorradiografia con timidina tritiada, que les permitio evaluar la velocidad de sintesis en los cultivos de una sola capa que utilizaron. Los resultados indican que: 1) La fraccion de celulas que sintetizan ADN en un cultivo no es alterada por las particulas a. ni por los rayos X en las dosis experimentales empleadas. 2) Ambos tipos de radiaciones reducen la velocidad de sintesis del ADN en las celulas irradiadas. 3) El efecto de una dosis determinada de cualquiera de las dos radiaciones es disminuir la velocidad de sintesis de todas las celulas hasta una fraccion constante de la velocidad correspondiente a las celulas no irradiadas. 4) En. el caso de los fibroblastos del raton, la velocidad de sintesis del ADN queda reducida en un 37 por ciento (1/e) por una dosis a del orden de 25 {alpha}/{mu}{sup 2} o por una dosis de rayos X de 14 000 rad( En el caso de las celulas de HeLa, se requiere una dosis de unos 90 000 rad para alcanzar el mismo efecto. 5) La disminucion de la velocidad de sintesis se produce menos de media hora despues de la irradiacion, por lo que podria tratarse de un efecto inmediato. El resultado 4) permite calcular aproximadamente la forma del blanco. Si seo supone que es cilindrico, enoel caso de los fibroblastos, tendria un diametro aproximado de 16 A y una longitud de 16 000 A, es decir, se trataria de un cilindro extremadamente alargado con un peso molecular del orden de 5 x 10{sup 7}. Para las celulas de HeLa se obtendria un peso molecular de 10{sup 7}. Los resultados concuerdan con la

  20. Media education.

    Science.gov (United States)

    Strasburger, Victor C

    2010-11-01

    The American Academy of Pediatrics recognizes that exposure to mass media (eg, television, movies, video and computer games, the Internet, music lyrics and videos, newspapers, magazines, books, advertising) presents health risks for children and adolescents but can provide benefits as well. Media education has the potential to reduce the harmful effects of media and accentuate the positive effects. By understanding and supporting media education, pediatricians can play an important role in reducing harmful effects of media on children and adolescents.

  1. Pengaruh Variasi Temperatur Hidrotermal Pada Sintesis Lithium Mangan Oksida (Limn2o4 Spinel Terhadap Efisiensi Adsorpsi Dan Desorpsi Ion Lithium Dari Lumpur Sidoarjo

    Directory of Open Access Journals (Sweden)

    Yusuf Kurniawan

    2014-09-01

    Full Text Available Perkembangan teknologi dalam bidang material menunjukkan perkembangan yang sangat pesat dalam beberapa tahun terakhir.Salah satu material yang sangat dibutuhkan dalam berbagai aplikasi adalah lithium. Lithium sendiri bisa didapatkan dari air laut brines dan geothermal fluid. Salah satunya adalah Lumpur Sidoarjo. Lithium Mangan Oksida Spinel digunakan sebagai material absorben karena murah, tidak beracun dan mudah didapatkan. Pada penelitian ini metode hidrotermal digunakan sebagai metode sintesis pada LiMn2O4 karena dapat dilakukan pada temperatur yang relatif rendah dan menghasilkan partikel yang lebih homogen. Metode hidrotermal dilakukan pada temperatur 160 oC, 180 oC dan 200 oC selama 24 jam. Pengujian XRD dilakukan untuk mengetahui struktur kristal. Pengujian SEM dilakukan untuk mengetahui morfologi material setelah proses hidrotermal. Pengujian BET dilakukan untuk mengetahui surface area. Setelah itu metode acid treatment dilakukan untuk proses adsorpsi dan desorpsi. Adsorpsi dilakukan dengan mencelupkan Lithium Mangan Oksida Spinel yang telah disintesis kedalam Lumpur Sidoarjo.Pengujian ICP dilakukan untuk mengetahui kandungan lithium yang terdapat pada Lumpur Sidoarjo sebelum dan sesudah adsorpsi untuk mengetahui jumlah lithium yang terserap.Pengujian desorpsi dilakukan dengan mencelupkan LiMn2O4 kedalam larutan HCL. Pada uji XRD menunjukkan bahwa LiMn2O4 berstruktur kristal cubic. Dari hasil uji SEM terlihat bahwa tidak banyak perbedaan morfologi pada ketiga variasi.Partikel cenderung membentuk aglomerasi. Pada hasil uji ICP menunjukkan bahwa LiMn2O4 dengan temperatur hidrotermal 160oC memiliki efisiensi adsorpsi paling tinggi dengan 6,775 ppm. Sementara untuk desorpsi yang paling tinggi adalah 200oC sebesar 0.081 ppm

  2. Application of functionalized nano HMS type mesoporous silica with N-(2-aminoethyl-3-aminopropyl methyldimethoxysilane as a suitable adsorbent for removal of Pb (II from aqueous media and industrial wastewater

    Directory of Open Access Journals (Sweden)

    Hamedreza Javadian

    2017-01-01

    Full Text Available In this work, adsorption characteristics of nano NH2-HMS (functionalized HMS type mesoporous silica with amine groups for the removal of Pb (II ions from aqueous solutions were investigated. The adsorbent was characterized using FE-SEM, TEM, XRD, FTIR and BET. The adsorption of Pb (II ions by batch method was applied and the optimum conditions were investigated. In optimum experimental conditions, removal efficiency was 99.08%. It was found that temperature has a positive effect on the removal efficiency. The thermodynamic parameters were evaluated, as well. The evaluated thermodynamic parameters (ΔG, ΔH and ΔS showed that the adsorption of Pb (II ions onto nano NH2-HMS was feasible, spontaneous and endothermic in nature. It can be concluded that NH2-HMS is potentially able to remove Pb (II ions from aqueous solutions. Also, more than 90% of desorption efficiency was achieved using 0.01 M HNO3.

  3. Generalized corrosion of nickel base alloys in high temperature aqueous media: a contribution to the comprehension of the mechanisms; Corrosion generalisee des alliages a base nickel en milieu aqueux a haute temperature: apport a la comprehension des mecanismes

    Energy Technology Data Exchange (ETDEWEB)

    Marchetti-Sillans, L

    2007-11-15

    In France, nickel base alloys, such as alloy 600 and alloy 690, are the materials constituting steam generators (SG) tubes of pressurized water reactors (PWR). The generalized corrosion resulting from the interaction between these alloys and the PWR primary media leads, on the one hand, to the formation of a thin protective oxide scale ({approx} 10 nm), and on the other hand, to the release of cations in the primary circuit, which entails an increase of the global radioactivity of this circuit. The goal of this work is to supply some new comprehension elements about nickel base alloys corrosion phenomena in PWR primary media, taking up with underlining the effects of metallurgical and physico-chemical parameters on the nature and the growth mechanisms of the protective oxide scale. In this context, the passive film formed during the exposition of alloys 600, 690 and Ni-30Cr, in conditions simulating the PWR primary media, has been analyzed by a set of characterization techniques (SEM, TEM, PEC and MPEC, XPS). The coupling of these methods leads to a fine description, in terms of nature and structure, of the multilayered oxide forming during the exposition of nickel base alloys in primary media. Thus, the protective part of the oxide scale is composed of a continuous layer of iron and nickel mixed chromite, and Cr{sub 2}O{sub 3} nodules dispersed at the alloy / mixed chromite interface. The study of protective scale growth mechanisms by tracers and markers experiments reveals that the formation of the mixed chromite is the consequence of an anionic mechanism, resulting from short circuits like grain boundaries diffusion. Besides, the impact of alloy surface defects has also been studied, underlining a double effect of this parameter, which influences the short circuits diffusion density in oxide and the formation rate of Cr{sub 2}O{sub 3} nodules. The sum of these results leads to suggest a description of the nickel base alloys corrosion mechanisms in PWR primary

  4. Avaliação do desempenho de surfactantes para a solubilização de fases líquidas não aquosas em meio aquoso Evaluating surfactant performance as solubilizer of non-aqueous phase liquids within aqueous media

    Directory of Open Access Journals (Sweden)

    Elizabeth Fátima de Souza

    2010-01-01

    Full Text Available The presence of non-aqueous phase liquids (NAPLs in the subsurface is a threat to public health as well as a serious environmental issue. NAPLs may remain adsorbed or form lenses floating on aquifers causing long-term contaminations. Surfactants may increase NAPLs solubility, enhancing the pump-and-treatment performance. Size, shape, hydration and ionization degree of the micelles define the affinity and the space available for the solubilization of a particular contaminating agent. The tests carried out at laboratory scale, taking into account the NAPL to be removed and the medium characteristics were useful to select surfactants and evaluate their efficiency as NAPLs solubilizers.

  5. MIPs in Aqueous Environments.

    Science.gov (United States)

    Wan, Ying-chun; Ma, Hui-ting; Lu, Bin

    2015-01-01

    When organic solvent-compatible molecularly imprinted polymers (MIPs) are used in aqueous environment, how to reduce nonspecific binding is a major challenge. By modifying the binding solvents and introducing appropriate washing and elution steps, even relatively hydrophobic MIPs can gain optimal rebinding selectivity in aqueous conditions. Furthermore, water-compatible MIPs that can be used to treat aqueous samples directly have been prepared. The use of hydrophilic co-monomers, the controlled surface modification through controlled radical polymerization, and the new interfacial molecular imprinting methods are different strategies to prepare water-compatible MIPs. By combining MIPs with other techniques, both organic solvent-compatible and water-compatible MIPs can display better functional performances in aqueous conditions. Intensive studies on MIPs in aqueous conditions can provide new MIPs with much-improved compatibilities that will lead to more interesting applications in biomedicine and biotechnology.

  6. Study of 3-Ethylamino-but-2-enoic acid phenylamide as a new ligand for preconcentration of lanthanides from aqueous media by liquid-liquid extraction prior to ICP-MS analysis.

    Science.gov (United States)

    Varbanova, Evelina K; Angelov, Plamen A; Stefanova, Violeta M

    2016-11-01

    In the present work the potential of a new ligand 3-Ethylamino-but-2-enoic acid phenylamide (representing the class of enaminones) for selective preconcentration of lanthanides (La, Ce, Eu, Gd and Er) from aqueous medium is examined. Liquid-liquid extraction parameters, such as pH of the water phase, type and volume of organic solvent, quantity of ligand and reaction time are optimized on model solutions. Recovery of lanthanides by re-extraction with nitric acid makes the LLE procedure compatible with Inductively Coupled Plasma Mass Spectrometry. Spectral and non-spectral interferences are studied. Two isotopes per element are measured (with exception of La) for dynamic evaluation of the potential risk of spectral interference in variable real samples. The selectivity of complex formation reaction towards concomitant alkali and alkali-earth elements eliminates the interferences from sample matrix. Subjecting the standards to the optimized extraction procedure in combination with Re as internal standard is recommended as calibration strategy. The accuracy of developed method is approved by analysis of CRM Bush branches and leaves (NCS DC 73348) and recovery of spiked water and plant samples. The method's limits of detection for both studied objects are in the ranges from 0.2 ((158)Gd) to 3.7 ((139)La) ngl(-1) and 0.02 ((158)Gd) to 0.37((139)La) ngg(-1) for waters and plants respectively. The studied compound is an effective new ligand for preconcentration/separation of lanthanides from aqueous medium by LLE and subsequent determination by ICP-MS. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Biorelevant dissolution media

    DEFF Research Database (Denmark)

    Ilardia-Arana, David; Kristensen, Henning G; Müllertz, Anette

    2006-01-01

    Biorelevant dissolution media containing bile salt and lecithin at concentrations appropriate for fed and fasted state are useful when testing oral solid formulations of poorly water-soluble drugs. Dilution of amphiphile solutions affects the aggregation state of the amphiphiles because bile salt...... is partitioned between the aqueous phase and the aggregates. The aim of the investigation was to study the effect of dilution on the size distribution of aggregates and its effect on the solubilization capacity. Clear buffered solutions of four intestinal amphiphiles (sodium glycocholate, lecithin, monoolein...

  8. Media Komunitas dan Media Literacy

    Directory of Open Access Journals (Sweden)

    Pawito .

    2013-12-01

    Full Text Available Abstract:This essay deals with community media in relation to media literacy. After a short discussion on a number of community media characters is made the essay goes further with somewhat detail theoretical presumptions of the roles of media community with respect primarily to the development as Amartya Sen mentioned about. The author suggests that community media may play some significant roles in the development including (a disseminating information (from varieties of perspective, (b facilitating public discussion, (c helping to reach solutions of problems, (d encouraging participations, and (e encouraging the development of media literacy. Regarding the last point the author remarks that media community may have a dual-roles i.e facilitating community’s member in media participation and facilitating community’s member in media education.

  9. PENGEMBANGAN METODE SINTESIS FURFURAL BERBAHAN DASAR CAMPURAN LIMBAH PERTANIAN DALAM RANGKA MEWUJUDKAN PRINSIP GREEN CHEMISTRY (Development Of Synthesis Method Of Furfural From Compost Heap Mixture To Reach Out Green Chemistry Principles

    Directory of Open Access Journals (Sweden)

    Mitarlis Mitarlis

    2011-11-01

    Full Text Available ABSTRAK Penelitian pengembangan metode sintesis furfural dengan bahan dasar campuran limbah pertanian dilakukan dengan tujuan untuk menentukan waktu pemanasan dan konsentrasi asam optimum serta mewujudkan prinsip green chemistry. Dalam penelitian ini digunakan campuran limbah pertanian ampas tebu, limbah daun nanas dan limbah tanaman jagung dengan perbandingan 1:1:1. Proses sintesis melalui tahap hidrolisis pentosan, dehidrasi, dan siklodehidrasi untuk membentuk furfural dengan menggunakan alat refluks termodifkasi. Identifikasi furfural menggunakan uji warna dengan anilin asetat, uji indeks bias, spektrofotometer UV-Vis, dan IR, serta GC. Analisis pemenuhan prinsip green chemistry menggunakan daftar ceck 12 prinsip green chemstry. Hasil penelitian menunjukkan bahwa: Waktu pemanasan dan konsentrasi asam sulfat optimum pada pembuatan furfural dari campuran limbah pertanian adalah 5 jam dan konsentrasi asam sulfat 10% (1,876 M dengan rendemen sebesar 5,58%. Metode sintesis furfural yang dikembangkan dapat memenuhi 11 dari 12 prinsip green chemistry yang telah ditetapkan. ABSTRACT The study of developing furfural synthesis method  from  compost heap mixture had been done to determine  optimum condition for this process and  to reach out the green chemistry principles. In this research, the compost heap mixture is from three kinds of compost heap (bagasse, pineapple leaf, waste of corn plant with same amount (1:1:1. The steps of furfural production process are hydrolysis of pentose by sulfuric acid, dehydration, and cyclodehydration to form furfural. It was produced by using a modification reflux apparatus. Identify of furfural product by  using qualitative analysis color test with aniline acetate, refractive index test, UV-Vis,  IR spectrophotometer, and GC. Green chemistry principles are analyzed by using check list of 12 principles of green chemistry.  Based on this research was obtained that the optimum concentration of sulfuric acid is

  10. Magnetically Separable Fe3O4@DOPA-Pd: A Heterogeneous Catalyst for Aqueous Heck Reaction

    Science.gov (United States)

    Magnetically separable Fe3O4@DOPA-Pd catalyst has been synthesized via anchoring of palladium over dopamine-coated magnetite via non-covalent interaction and the catalyst is utilized for expeditious Heck coupling in aqueous media.

  11. Layer silicates modified with 1,4-bis(3-aminopropyl)piperazine for the removal of Th(IV), U(VI) and Eu(III) from aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Guerra, Denis L., E-mail: dlguerra@iqm.unicamp.br [Chemistry Institute, State University of Campinas, P.O. Box 6154, 13084-971 Campinas, Sao Paulo (Brazil); Pinto, Alane A. [Chemistry Institute, State University of Campinas, P.O. Box 6154, 13084-971 Campinas, Sao Paulo (Brazil); Viana, Rubia R. [Universidade Federal de Mato Grosso, UFMT, Centro de Recursos Minerais, Cuiaba, Mato Grosso 78060 900 (Brazil); Airoldi, Claudio [Chemistry Institute, State University of Campinas, P.O. Box 6154, 13084-971 Campinas, Sao Paulo (Brazil)

    2009-11-15

    Natural montmorillonite (M) and synthetic kanemite (K) have been functionalized with 1,4-bis(3-aminopropyl)piperazine reacted with methylacrylate to yield new inorganic-organic chelating materials. The original and modified materials were characterized by X-ray diffractometry, textural analysis, SEM and nuclear magnetic nuclei of carbon-13 and silicon-29. The chemically modified clay samples (M-APPMA and K-APPMA) showed modification of its physical-chemical properties including: specific area 45.0 m{sup 2} g{sup -1} (M) to 978.8 m{sup 2} g{sup -1} (M-APPMA) and 23.5 m{sup 2} g{sup -1} (K) to 898.9 m{sup 2} g{sup -1} (K-APPMA). The ability of these materials to remove thorium(IV), uranyl(VI) and europium(III) from aqueous solution was followed by a series of adsorption isotherms, which were fitted to non-linear Sips adsorption isotherm model. To achieve the best adsorption conditions the influence of pH and variation of metal concentration were investigated. The energetic effects ({Delta}{sub int}H{sup o}, {Delta}{sub int}G{sup o} and {Delta}{sub int}S{sup o}) caused by metal ions adsorption were determined through calorimetric titrations.

  12. Layer silicates modified with 1,4-bis(3-aminopropyl)piperazine for the removal of Th(IV), U(VI) and Eu(III) from aqueous media

    International Nuclear Information System (INIS)

    Guerra, Denis L.; Pinto, Alane A.; Viana, Rubia R.; Airoldi, Claudio

    2009-01-01

    Natural montmorillonite (M) and synthetic kanemite (K) have been functionalized with 1,4-bis(3-aminopropyl)piperazine reacted with methylacrylate to yield new inorganic-organic chelating materials. The original and modified materials were characterized by X-ray diffractometry, textural analysis, SEM and nuclear magnetic nuclei of carbon-13 and silicon-29. The chemically modified clay samples (M-APPMA and K-APPMA) showed modification of its physical-chemical properties including: specific area 45.0 m 2 g -1 (M) to 978.8 m 2 g -1 (M-APPMA) and 23.5 m 2 g -1 (K) to 898.9 m 2 g -1 (K-APPMA). The ability of these materials to remove thorium(IV), uranyl(VI) and europium(III) from aqueous solution was followed by a series of adsorption isotherms, which were fitted to non-linear Sips adsorption isotherm model. To achieve the best adsorption conditions the influence of pH and variation of metal concentration were investigated. The energetic effects (Δ int H o , Δ int G o and Δ int S o ) caused by metal ions adsorption were determined through calorimetric titrations.

  13. Speciation of organotin compounds by capillary electrophoresis: comparison of aqueous and mixed organic-aqueous systems

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Lei; Matysik, Frank-Michael; Glaeser, Petra [Universitaet Leipzig, Institut fuer Analytische Chemie, Leipzig (Germany)

    2004-10-01

    A capillary electrophoresis method with direct ultraviolet detection was developed for the analysis of organotin species. Despite the fact that direct detection of organotin compounds by ultraviolet absorption is difficult because most organotins possess poor chromophoric properties, the application of low wavelength ({lambda}=200 nm) and mixed organic-aqueous media enabled a significant enhancement in sensitivity. A mixed organic-aqueous system (10% methanol/40% acetonitrile/50% H{sub 2}O) containing acetic acid and tetrabutylammonium perchlorate formed the basis for rapid, efficient and sensitive determinations of organotin cations such as tripropyltin, tributyltin, triphenyltin and diphenyltin. The concentration limits of detection (LOD) for the four organotin compounds were in the range of 0.4-14 {mu}M, comparable to that obtained with the most sensitive indirect UV method reported until now, and took advantage of a stable baseline, a symmetric peak shape and an absence of disturbing system peaks. The relative standard deviations (n=7) for the relative peak time and peak area were 0.44-0.77 and 4.8-5.8%, respectively. In addition to sensitivity enhancements, the use of organic-aqueous systems instead of pure aqueous media resulted in improved selectivity and efficiency of separations. (orig.)

  14. Locative media

    CERN Document Server

    Wilken, Rowan

    2014-01-01

    Not only is locative media one of the fastest growing areas in digital technology, but questions of location and location-awareness are increasingly central to our contemporary engagements with online and mobile media, and indeed media and culture generally. This volume is a comprehensive account of the various location-based technologies, services, applications, and cultures, as media, with an aim to identify, inventory, explore, and critique their cultural, economic, political, social, and policy dimensions internationally. In particular, the collection is organized around the perception that the growth of locative media gives rise to a number of crucial questions concerning the areas of culture, economy, and policy.

  15. Media Entrepreneurship

    DEFF Research Database (Denmark)

    Khajeheian, Datis

    2017-01-01

    Media Entrepreneurship has been an ambiguous, unclear and controversial concept and despite of growing academic efforts in the last decade, it is still a poorly defined subject. This paper is an effort to fill this gap by providing a comprehensive definition of media entrepreneurship. Firstly......, a literature review conducted and entrepreneurship, media, opportunity and innovation as building blocks of media entrepreneurship explained. Then by using of a mixed of bibliographic method and a Delphi method with multi-stage analysis process, a consensual definition of media entrepreneurship proposed...... entrepreneurship....

  16. Media Framing

    DEFF Research Database (Denmark)

    Pedersen, Rasmus T.

    2017-01-01

    The concept of media framing refers to the way in which the news media organize and provide meaning to a news story by emphasizing some parts of reality and disregarding other parts. These patterns of emphasis and exclusion in news coverage create frames that can have considerable effects on news...... consumers’ perceptions and attitudes regarding the given issue or event. This entry briefly elaborates on the concept of media framing, presents key types of media frames, and introduces the research on media framing effects....

  17. Aqueous lithium air batteries

    Science.gov (United States)

    Visco, Steven J.; Nimon, Yevgeniy S.; De Jonghe, Lutgard C.; Petrov, Alexei; Goncharenko, Nikolay

    2017-05-23

    Aqueous Li/Air secondary battery cells are configurable to achieve high energy density and prolonged cycle life. The cells include a protected a lithium metal or alloy anode and an aqueous catholyte in a cathode compartment. The aqueous catholyte comprises an evaporative-loss resistant and/or polyprotic active compound or active agent that partakes in the discharge reaction and effectuates cathode capacity for discharge in the acidic region. This leads to improved performance including one or more of increased specific energy, improved stability on open circuit, and prolonged cycle life, as well as various methods, including a method of operating an aqueous Li/Air cell to simultaneously achieve improved energy density and prolonged cycle life.

  18. Sensitive Media

    Directory of Open Access Journals (Sweden)

    Malinowska Anna

    2017-12-01

    Full Text Available The paper engages with what we refer to as “sensitive media,” a concept associated with developments in the overall media environment, our relationships with media devices, and the quality of the media themselves. Those developments point to the increasing emotionality of the media world and its infrastructures. Mapping the trajectories of technological development and impact that the newer media exert on human condition, our analysis touches upon various forms of emergent affect, emotion, and feeling in order to trace the histories and motivations of the sensitization of “the media things” as well as the redefinition of our affective and emotional experiences through technologies that themselves “feel.”

  19. Media Ecology

    Directory of Open Access Journals (Sweden)

    Marina Ašković

    2015-05-01

    Full Text Available Does the trend in which electronic media are gradually becoming extension of human body have to move towards full enslavement of a human and his personality, or the same human will unpredictably, with the aid of his personal media literacy, exit the whirls of media and technological censorships? Personality crisis is closely related to the crisis of language no matter how contradicted to global ideology of transnational transhumanism it may seem. Considering the fact that recent media presentations of the world are based on commercialization of environmentalism, philosophical and aesthetic thought appears as an important subject of ecology. As media mediates, the scenery of civilized living increasingly becomes more appealing even though it derives from commercial and political background. Consequently, the future of humanity depends by large on the philosophy of media. Media have to truly ecologise returning the humanum to its essence making it into the extension of the natural world.

  20. Arenediazonium salts transformations in water media: Coming round to origins

    OpenAIRE

    Marina E. Trusova; Ksenia V. Kutonova; Victor V. Kurtukov; Victor D. Filimonov; Pavel S. Postnikov

    2016-01-01

    Aromatic diazonium salts belong to an important class of organic compounds. The chemistry of these compounds has been originally developed in aqueous media, but then chemists focused on new synthetic methods that utilize reactions of diazonium salts in organic solvents. However, according to the principles of green chemistry and resource-efficient technologies, the use of organic solvents should be avoided. This review summarizes new trends of diazonium chemistry in aqueous media that satisfy...

  1. Sintesis Ramah Lingkungan Senyawa Imina Turunan Vanilin dan 2-Hidroksi Asetofenon Serta Uji Aktivitas Biologi dan Antioksidan

    Directory of Open Access Journals (Sweden)

    Putri Pratiwi

    2015-04-01

    Full Text Available Eco-friendly synthesis of imine derivative compound from 2-hydroxy acetophenone and vanillin had been conducted by using a method of stirring (with stirrer in a water solvent. The whole experiment began with the synthesis of imine compounds, followed by purification and characterization of the synthesis products and finally analysis on their biological and antioxidant activities. The experiments showed that imine compounds could be synthesized by a chemical reaction of 4-amino antipirin aqueous solution with 2-hydroxy acetophenone and vanillin at magnetic stirrer speed of 250 and 450 rpm, respectively, which produced product A, (E-4-(1-(2-hydroxyphenyl ethylideneamino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H-one and product B, (E-4-(4-hydroxy-3-(vinyloxy benzylideneamino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H-one. Yield percentage (% obtained from the synthesis of product A and B were 40.68% and 19.76% respectively. Toxicity and antioxidant activity tests showed that the product B were toxic and more active as an antioxidant than product A. While the antibacterial activity test showed that both products had a response to Staphyllococcus aureus bacteria and Escherechia coli bacteria.

  2. Matrix-assisted laser desorption/ionization mass spectrometric analysis of poly(3,4-ethylenedioxythiophene) in solid-state dye-sensitized solar cells: comparison of in situ photoelectrochemical polymerization in aqueous micellar and organic media.

    Science.gov (United States)

    Zhang, Jinbao; Ellis, Hanna; Yang, Lei; Johansson, Erik M J; Boschloo, Gerrit; Vlachopoulos, Nick; Hagfeldt, Anders; Bergquist, Jonas; Shevchenko, Denys

    2015-04-07

    Solid-state dye-sensitized solar cells (sDSCs) are devoid of such issues as electrolyte evaporation or leakage and electrode corrosion, which are typical for traditional liquid electrolyte-based DSCs. Poly(3,4-ethylenedioxythiophene) (PEDOT) is one of the most popular and efficient p-type conducting polymers that are used in sDSCs as a solid-state hole-transporting material. The most convenient way to deposit this insoluble polymer into the dye-sensitized mesoporous working electrode is in situ photoelectrochemical polymerization. Apparently, the structure and the physicochemical properties of the generated conducting polymer, which determine the photovoltaic performance of the corresponding solar cell, can be significantly affected by the preparation conditions. Therefore, a simple and fast analytical method that can reveal information on polymer chain length, possible chemical modifications, and impurities is strongly required for the rapid development of efficient solar energy-converting devices. In this contribution, we applied matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) for the analysis of PEDOT directly on sDSCs. It was found that the PEDOT generated in aqueous micellar medium possesses relatively shorter polymeric chains than the PEDOT deposited from an organic medium. Furthermore, the micellar electrolyte promotes a transformation of one of the thiophene terminal units to thiophenone. The introduction of a carbonyl group into the PEDOT molecule impedes the growth of the polymer chain and reduces the conductivity of the final polymer film. Both the simplicity of sample preparation (only application of the organic matrix onto the solar cell is needed) and the rapidity of analysis hold the promise of making MALDI MS an essential tool for the physicochemical characterization of conducting polymer-based sDSCs.

  3. Removal of Hexavalent Chromium from Aqueous Solutions using ...

    African Journals Online (AJOL)

    The hexavalent chromium exists in aquatic media as water soluble complex anions and persist. These are concentrated in industrial waste water especially from the tannery industries and release of effluents from industries adversely affects the environment. The removal of heavy metals from aqueous solutions is carried ...

  4. A cyclo olefin polymer microfluidic chip with integrated gold microelectrodes for aqueous ans non-aqueous electrochemistry

    DEFF Research Database (Denmark)

    Illa, Xavi; Sala, Olga Ordeig; Snakenborg, Detlef

    2010-01-01

    and 24 m deep channel was fabricated via hot embossing. Cyclic voltammetric measurements were carried out in aqueous and organic media, using a solution consisting of 5 mM ferrocyanide/ferricyanide in 0.5 M KNO3 and 5 mM ferrocene in 0.1 M TBAP/acetonitrile, respectively. Experimental currents obtained...

  5. Development of a model for the anodic behavior of T60 titanium in chlorinated and oxygenated aqueous media. Application to the specific conditions of hydrothermal oxidation (1 MPa

    International Nuclear Information System (INIS)

    Frayret, C.; Jaszay, Th.; Lestienne, B.; Delville, M.H.

    2003-01-01

    This work evaluates the anodic electrochemical behavior of titanium metal in hydrothermal oxidation conditions (up to 400 deg. C and 28 MPa) in chlorinated media in order to estimate the supercritical water oxidation reactors reliability for the treatment of less than 10% organic-waste waters. The titanium room temperature dissolution mechanism in chlorinated acidic medium (pH 2 oxide formation with a very limited tetravalent dissolution). In hydrothermal oxidation (pH>1), only the second branch is effective. The titanium protection is directly related to the oxide stability in high pH systems. The mechanism model is expressed in terms of 'current-potential' laws, which provide kinetic parameters using optimization calculations. The different elementary steps reaction rates were estimated as well as the evolution of the reaction intermediates coverage ratios with the potential. The quantification of each elementary step was performed to understand and/or orient the materials behavior according to different factors (pH, chloride ions contents, potentials...)

  6. Media Flow

    DEFF Research Database (Denmark)

    Kabel, Lars

    2016-01-01

    News and other kinds of journalistic stories, 16-17 hours a day, all year round, on all platforms, also the moderated social media. The key research thesis behind this article is that the continuous and speedy stream of news stories and media content now is becoming the centre of the production...... processes and the value creation in converged multimedia newsrooms. The article identify new methods and discuss editorial challenges in handling media flow....

  7. Determinação das propriedades catalíticas em meio aquoso e orgânico da lipase de Candida rugosa imobilizada em celulignina quimicamente modificada por carbonildiimidazol Assessment of catalytic properties in aqueous and organic media of lipase from Candida rugosa immobilized on wood cellulignin activated with carbonyldiimidazole

    Directory of Open Access Journals (Sweden)

    Fabrício M. Gomes

    2006-07-01

    Full Text Available Microbial lipase from Candida rugosa was immobilized by covalent binding on wood cellulignin (Eucaliptus grandis chemically modified with carbonyldiimidazole. The immobilized system was fully evaluated in aqueous (olive oil hydrolysis and organic (ester synthesis media. A comparative study between free and immobilized lipase was carried out in terms of pH, temperature and thermal stability. A higher pH value (8.0 was found optimal for the immobilized lipase. The optimal reaction temperature shifted from 37 °C for the free lipase to 45 °C for the immobilized lipase. The pattern of heat stability indicated that the immobilization process tends to stabilize the enzyme. Kinetics tests at 37 °C following the hydrolysis of olive oil obeyed the Michaelis-Menten rate equation. Values for Km = 924.9 mM and Vmax = 198.3 U/mg were lower than for free lipase, suggesting that the affinity towards the substrate changed and the activity of the immobilized lipase decreased during the course of immobilization. The immobilized derivative was also tested in the ester synthesis from several alcohols and carboxylic acids.

  8. Radiation protection of vitamins in aqueous systems

    International Nuclear Information System (INIS)

    Kishore, K.; Moorthy, P.N.; Rao, K.N.

    1976-01-01

    A study of the radiation induced decomposition of the B-group vitamins has been carried out in aqueous media at room temperature as well as in rigid matrices at low temperature. The detailed results on the effect of glucose and oxygen as protective additives at the different temperatures are presented in the case of Thiamine (Vitamin B 1 ). Comparative data are given on the extent of decomposition of this and other vitamins of the B-group at room temperature and at 193 K. The importance of these results in connection with the radiation sterilization of pharmaceutical preparations is indicated. (author)

  9. Chemical systems in aqueous solutions for using in the holographic ionizing radiation

    International Nuclear Information System (INIS)

    Nicolau-Rebigan, S.

    1979-01-01

    Some types of chemical systems in aqueous solutions for utilization as active media in holographic ionizing radiation dosimeter are presented. One discussed some advantages of the holographic dosimeter comparatively with another existing types. It is outlined the advantages of using aqueousss solutions as active media in holographic dosimeter. (author)

  10. Instructional Media

    African Journals Online (AJOL)

    This can be summed up in a few words: Students can learn a great deal from any of the media. Under most of the conditions tested, they could learn as much as from ... Beyond physical conditions (deafness) there is little reason to expect a differential media. Scientia Militaria, South African Journal of Military Studies, Vol 13 ...

  11. Mixed Media

    Science.gov (United States)

    Peterson, Erin

    2010-01-01

    While institutions do not often have a hook as compelling as an eagerly awaited movie, great content is critical for media relations success--and coupling it with the right distribution channel can ensure the story finds the right audience. Even better, retooling it for several media platforms can extend the life and reach of a story. The changes…

  12. Media darling

    CERN Multimedia

    Chalmers, Matthew

    2008-01-01

    He is the media-friendly face of particle physics, appearing on countless TV and radio shows in the run-up to the opening of CERN's Large Hadron Collider. Matthew Chalmers discovers how Brian Cox finds the time to be both a physicist and a media personality. (2 pages)

  13. Media Art

    DEFF Research Database (Denmark)

    Ekman, Ulrik

    2015-01-01

    environments, experience time, and develop identities individually and socially. Interviews with working media artists lend further perspectives on these cultural transformations. Drawing on cultural theory, new media art studies, human-computer interaction theory, and software studies, this cutting-edge book...... critically unpacks the complex ubiquity-effects confronting us every day....

  14. Aqueous polyethylene oxide solutions

    International Nuclear Information System (INIS)

    Breen, J.

    1987-01-01

    A number of aspects concerning the reorientation of polymer, water and ion hydration complexes have been studied in aqueous solution of polyethylene oxide (PEO). The polymer dynamics are investigated by 1 H-PEO and 13 C-PEO nuclear relaxation experiments. 162 refs.; 30 figs.; 19 tabs

  15. Media violence.

    Science.gov (United States)

    Cantor, J

    2000-08-01

    Research on the effects of media violence is not well understood by the general public. Despite this fact, there is an overwhelming consensus in the scientific literature about the unhealthy effects of media violence. Meta-analyses show that media-violence viewing consistently is associated with higher levels of antisocial behavior, ranging from the trivial (imitative violence directed against toys) to the serious (criminal violence), with many consequential outcomes in between (acceptance of violence as a solution to problems, increased feelings of hostility, and the apparent delivery of painful stimulation to another person). Desensitization is another well-documented effect of viewing violence, which is observable in reduced arousal and emotional disturbance while witnessing violence, the reduced tendency to intervene in a fight, and less sympathy for the victims of violence. Although there is evidence that youth who are already violent are more likely to seek out violent entertainment, there is strong evidence that the relationship between violence viewing and antisocial behavior is bidirectional. There is growing evidence that media violence also engenders intense fear in children which often lasts days, months, and even years. The media's potential role in solutions to these problems is only beginning to be explored, in investigations examining the uses and effects of movie ratings, television ratings, and the V-chip, and the effects of media literacy programs and public education efforts. Future research should explore important individual differences in responses to media violence and effective ways to intervene in the negative effects.

  16. Progress in aqueous rechargeable batteries

    OpenAIRE

    Jilei Liu; Chaohe Xu; Zhen Chen; Shibing Ni; Ze Xiang Shen

    2018-01-01

    Over the past decades, a series of aqueous rechargeable batteries (ARBs) were explored, investigated and demonstrated. Among them, aqueous rechargeable alkali-metal ion (Li+, Na+, K+) batteries, aqueous rechargeable-metal ion (Zn2+, Mg2+, Ca2+, Al3+) batteries and aqueous rechargeable hybrid batteries are standing out due to peculiar properties. In this review, we focus on the fundamental basics of these batteries, and discuss the scientific and/or technological achievements and challenges. B...

  17. How Solid-Electrolyte Interphase Forms in Aqueous Electrolytes.

    Science.gov (United States)

    Suo, Liumin; Oh, Dahyun; Lin, Yuxiao; Zhuo, Zengqing; Borodin, Oleg; Gao, Tao; Wang, Fei; Kushima, Akihiro; Wang, Ziqiang; Kim, Ho-Cheol; Qi, Yue; Yang, Wanli; Pan, Feng; Li, Ju; Xu, Kang; Wang, Chunsheng

    2017-12-27

    Solid-electrolyte interphase (SEI) is the key component that enables all advanced electrochemical devices, the best representative of which is Li-ion battery (LIB). It kinetically stabilizes electrolytes at potentials far beyond their thermodynamic stability limits, so that cell reactions could proceed reversibly. Its ad hoc chemistry and formation mechanism has been a topic under intensive investigation since the first commercialization of LIB 25 years ago. Traditionally SEI can only be formed in nonaqueous electrolytes. However, recent efforts successfully transplanted this concept into aqueous media, leading to significant expansion in the electrochemical stability window of aqueous electrolytes from 1.23 V to beyond 4.0 V. This not only made it possible to construct a series of high voltage/energy density aqueous LIBs with unprecedented safety, but also brought high flexibility and even "open configurations" that have been hitherto unavailable for any LIB chemistries. While this new class of aqueous electrolytes has been successfully demonstrated to support diversified battery chemistries, the chemistry and formation mechanism of the key component, an aqueous SEI, has remained virtually unknown. In this work, combining various spectroscopic, electrochemical and computational techniques, we rigorously examined this new interphase, and comprehensively characterized its chemical composition, microstructure and stability in battery environment. A dynamic picture obtained reveals how a dense and protective interphase forms on anode surface under competitive decompositions of salt anion, dissolved ambient gases and water molecule. By establishing basic laws governing the successful formation of an aqueous SEI, the in-depth understanding presented in this work will assist the efforts in tailor-designing better interphases that enable more energetic chemistries operating farther away from equilibria in aqueous media.

  18. From Augmentation Media to Meme Media.

    Science.gov (United States)

    Tanaka, Yuzuru

    Computers as meta media are now evolving from augmentation media vehicles to meme media vehicles. While an augmentation media system provides a seamlessly integrated environment of various tools and documents, meme media system provides further functions to edit and distribute tools and documents. Documents and tools on meme media can easily…

  19. Tunable aqueous virtual micropore.

    Science.gov (United States)

    Park, Jae Hyun; Guan, Weihua; Reed, Mark A; Krstić, Predrag S

    2012-03-26

    A charged microparticle can be trapped in an aqueous environment by forming a narrow virtual pore--a cylindrical space region in which the particle motion in the radial direction is limited by forces emerging from dynamical interactions of the particle charge and dipole moment with an external radiofrequency quadrupole electric field. If the particle satisfies the trap stability criteria, its mean motion is reduced exponentially with time due to the viscosity of the aqueous environment; thereafter the long-time motion of particle is subject only to random, Brownian fluctuations, whose magnitude, influenced by the electrophoretic and dielectrophoretic effects and added to the particle size, determines the radius of the virtual pore, which is demonstrated by comparison of computer simulations and experiment. The measured size of the virtual nanopore could be utilized to estimate the charge of a trapped micro-object. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Aqueous liquid redox desulfurisation

    Energy Technology Data Exchange (ETDEWEB)

    Reicher, M.; Niemiec, B.; Katona, T.

    1999-12-01

    The LO-CAT II process is an aqueous liquid redox process which uses ferric and ferrous iron catalysts to oxidise hydrogen sulfide (from sour gas) to elemental sulfur: the relevant chemical equations are given. Chelating agents keep the iron in solution. The system is described under the headings of (i) LO-CAT chemistry, (ii) design parameters, (iii) startup challenges, (iv) present situation and (v) anticipated future conditions. Further improvements to the system are anticipated.

  1. Assembly of DNA Architectures in a Non-Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Thomas J. Proctor

    2012-08-01

    Full Text Available In the present work, the procedures for the creation of self-assembled DNA nanostructures in aqueous and non-aqueous media are described. DNA-Surfactant complex formation renders the DNA soluble in organic solvents offering an exciting way to bridge the transition of DNA origami materials electronics applications. The DNA retains its structural features, and these unique geometries provide an interesting candidate for future electronics and nanofabrication applications with potential for new properties. The DNA architectures were first assembled under aqueous conditions, and then characterized in solution (using circular dichroism (CD spectroscopy and on the surface (using atomic force microscopy (AFM. Following aqueous assembly, the DNA nanostructures were transitioned to a non-aqueous environment, where butanol was chosen for optical compatibility and thermal properties. The retention of DNA hierarchical structure and thermal stability in non-aqueous conditions were confirmed via CD spectroscopy. The formation and characterization of these higher order DNA-surfactant complexes is described in this paper.

  2. Crucible-Free Synthesis of Silicides and Borides; Synthese de siliciures et de borures sans creuset; Bestigel'nyj sintez silitsidov i boridov; Sintesis de siliciuros y boruros sin crisol

    Energy Technology Data Exchange (ETDEWEB)

    Ban, Z.; Sikirica, M. [Rudjer Boskovic Institute, Zagreb, Yugoslavia (Croatia)

    1963-11-15

    The laboratory method for preparing pure silicides and borides, reducing the corresponding oxides of metals, has been developed. Synthesis of silicides was carried out in the floating zone of molten silicon. The floating zone was obtained by means of electron bombardment. Synthesis of borides is similar but reactions are generally of the solid-solid type. Initial heating of the reaction mixture was also obtained by means of the electron beam but further heating was produced by the ionized gaseous products of the reaction. (author) [French] On a mis au point une methode pour la preparation en laboratoire de siliciures et de borures purs, par reduction des oxydes des metaux correspondants. La synthese des siliciures a pu etre faite dans la ''zone flottante'' du silicium fondu. Cette zone flottante a ete obtenue par bombardement electronique. La synthese des borures est analogue, mais les reactions ont lieu generalement a Tetat solide. Le chauffage initial du melange reactionnel a egalement ete obtenu pai bombardement electronique, mais le chauffage ulterieur etait assure par les electrons diffuses des produits ionises gazeux de la reaction. (author) [Spanish] Los autores idearon un metodo de laboratorio para preparar siliciuros y boruros puros por reduccion de los respectivos oxidos metalicos. La sintesis de los siliciuros se llevo a cabo en la zona flotante del silicio fundido. Esa zona se obtuvo por bombardeo electronico. La sintesis de los boruros se llevo a cabo de manera similar, pero generalmente las reacciones son del tipo solido-solido. El calentamiento inicial de la mezcla se efectuo tambien mediante un haz electronico, pero el calentamiento ulterior es producido por la dispersion electronica en los productos de reaccion ionizados en estado gaseoso. (author) [Russian] Razrabotan laboratornyj metod prigotovleniya chistykh silitsidov i boridov putem vosstanovleniya sootvetstvennykh okislov metalla. Sintez, silitsidov provodili v plavayushchej zone

  3. Sonochemical synthesis of a PdAg/C electrocatalyst for oxygen reduction reaction; Sintesis sonoquimica de un electrocatalizador de PdAg/C para la reaccion de reduccion de oxigeno

    Energy Technology Data Exchange (ETDEWEB)

    Godinez-Garcia, A.; Perez-Robles, J.F. [Centro de Investigacion y de Estudios Avanzados del IPN. Santiago de Queretaro, Queretaro (Mexico)]. E-mail: jperez@qro.cinvestav.mx; Solorza-Feria, O. [CINVESTAV-IPN, Mexico, D.F. (Mexico)

    2009-09-15

    The synthesis and characterization of nanocatalysts for fuel cells has been a primary line of research for the purpose of obtaining less expensive electrocatalysts with better activity. A large variety of methods exist to synthesize useful nanoparticles as electrocatalysts. Each method generates particles with a different surface morphology and, therefore, the catalytic activity usually varies depending on which is used in the synthesis. In this work, PdAg/C electrocatalysts are synthesized with high-intensity ultrasonic irradiation and compared to those obtained using a conventional method such as reduction by NaBH{sub 4}. The study of this technique is of interest because it produces highly dispersed carbon-supported nanoparticles with very clean surfaces. Each electrocatalyst was evaluated for its oxygen reduction reaction (ORR) in acid medium with cyclic voltamperometry (CV) and rotating disc electrode (RDE). The electrocatalyst was characterized with x-ray diffraction and transmission electron microscopy (TEM). The physical characterization reveals that the electrocatalyst is composed of nanometric bimetallic aggregates. An important characteristic of the PdAg/C alloy obtained using ultrasound is better activity than that obtained by reduction with NaBH{sub 4}. [Spanish] La sintesis y caracterizacion de nanocatalizadores para celdas de combustible ha sido una de las principales lineas de investigacion, con el objetivo de obtener electrocatalizadores mas baratos y con una mejor actividad. Existen una gran variedad de metodos para sintetizar nanoparticulas utiles como electrocatalizadores, cada metodo genera particulas con una morfologia superficial diferente por lo que la actividad catalitica suele variar dependiendo de cual se utilice en la sintesis. En este trabajo se sintetizan electrocatalizadores de PdAg/C con irradiacion ultrasonica de alta intensidad y se comparan con las obtenidas con un metodo convencional como es la reduccion por NaBH{sub 4}. Esta

  4. Aqueous CO2 vs. aqueous extraction of soils as a preparative procedure for acute toxicity testing

    International Nuclear Information System (INIS)

    Yates, G.W.; Burks, S.L.

    1994-01-01

    This study was to determine if contaminated soils extracted with supercritical CO 2 (SFE) would yield different results from soils extracted with an aqueous media. Soil samples from an abandoned oil refinery were subjected to aqueous and SFE extraction. Uncontaminated control sites were compared with contaminated sites. Each extract was analyzed for 48 hour acute Ceriodaphnia LC50s and Microtox reg-sign EC50s. Comparisons were then made between the aqueous extracts and the SFE extracts. An additional study was made with HPLC chromatographs of the SFE contaminated site extracts to determine if there was a correlation between LC50 results and peak area of different sections of the chromatograph. The 48 hour Ceriodaphnia LC50 of one contaminated site showed a significant increase in toxicity with the supercritical extract compared to the aqueous extract. All contaminated sites gave toxic responses with the supercritical procedure. The Microtox reg-sign assay showed a toxic response with 2 of the 3 contaminated sites for both aqueous and SFE extracts. Results indicate that the Ceriodaphnia assays were more sensitive than Microtox reg-sign to contaminants found in the refinery soil. SFE controls did not show adverse effects with the Ceriodaphnia, but did have a slight effect with Microtox reg-sign. The best correlation (r 2 > 0.90) between the Ceriodaphnia LC50s and the peak areas of the chromatographs was obtained for sections with an estimated log K ow of 1 to 5. SFE extraction provided a fast, efficient and inexpensive method of collecting and testing moderately non-polar to strongly non-polar organic contaminants from contaminated soils

  5. Aqueous shunts for glaucoma.

    Science.gov (United States)

    Tseng, Victoria L; Coleman, Anne L; Chang, Melinda Y; Caprioli, Joseph

    2017-07-28

    Aqueous shunts are employed to control intraocular pressure (IOP) for people with primary or secondary glaucomas who fail or are not candidates for standard surgery. To assess the effectiveness and safety of aqueous shunts for reducing IOP in glaucoma compared with standard surgery, another type of aqueous shunt, or modification to the aqueous shunt procedure. We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 8), MEDLINE Ovid (1946 to August 2016), Embase.com (1947 to August 2016), PubMed (1948 to August 2016), LILACS (Latin American and Caribbean Health Sciences Literature Database) (1982 to August 2016), ClinicalTrials.gov (www.clinicaltrials.gov); searched 15 August 2016, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 15 August 2016. We did not use any date or language restrictions in the electronic search for trials. We last searched the electronic databases on 15 August 2016. We also searched the reference lists of identified trial reports and the Science Citation Index to find additional trials. We included randomized controlled trials that compared various types of aqueous shunts with standard surgery or to each other in eyes with glaucoma. Two review authors independently screened search results for eligibility, assessed the risk of bias, and extracted data from included trials. We contacted trial investigators when data were unclear or not reported. We graded the certainty of the evidence using the GRADE approach. We followed standard methods as recommended by Cochrane. We included 27 trials with a total of 2099 participants with mixed diagnoses and comparisons of interventions. Seventeen studies reported adequate methods of randomization, and seven reported adequate allocation concealment. Data collection and follow-up times varied.Four trials compared an aqueous shunt (Ahmed or Baerveldt) with trabeculectomy, of which

  6. Radiation Synthesis of Stannous Dibromodibutyl; Synthese radiochimique de l'etain dibromopibutyle; Radiatsionno-khimicheskij sintez dibromdibutilolova; Sintesis radioquimica del dffiromodibutilestano

    Energy Technology Data Exchange (ETDEWEB)

    Abramova, L. V.; Vereshchinskij, I. V.; Kocheshkov, K. A.; Miretskij, V. Yu.; Pozdneev, V. V.; Ryabukhin, Yu. S.; Sheverdina, N. I.

    1963-11-15

    'etain dibromodibutyle en grande quantite. Les auteurs montrent que le processus comporte une periode d'amorcage dont la duree depend du degre de purete du bromure de butyle initial. Ce facteur exerce en outre une influence sensible sur la vitesse, de formation du produit final. On a constate que l'etain qui n'est pas entre dans la reaction peut etre utilise de nouveau pour la production d'etain dibromodibutyle, mais que dans ce cas la periode d'amorcage est totalement inexistante. Les particularites mentionnees creent les conditions necessaires pour la realisation d'un processus continu. Les auteurs proposent un mecanisme reactionnel pour expliquer la regularite du processus dont le rendement radiochimique est eleve. (author) [Spanish] La posibilidad de efectuar la sintesis de compuestos organicos del estafio por irradiacion con los rayos gamma del {sup 60}Co de mezclas de estano y de los respectivos haluros alquilicos fue establecida por primera vez en 1958 por Abramova, Kocheshkovy Sheverdina. Las condiciones en que se realizaron los experimentos, en aparatos de vidrio, sin agitadores, no permitieron determinar las leyes cineticas de la formacion de ese tipo de compuestos organo-metalicos. El presente trabajo sirvio para aclarar la influencia de una serie de factores sobre la velocidad de la sintesis radioquimica de los compuestos organicos del estafio tomando como ejemplo el dibromodibutilestaflo. Con ese objeto, se construyo un aparato especial que facilita la carga periodica de los reactivos y la descarga de los productos de reaccion. Dicho aparato permite estabilizar la temperatura, agitar eficazmente los reactivos y extraer periodicamente muestras para analisis. El elemento esencial es el recipiente de reaccion, de acero inoxidable, de 2-1 de capacidad, provisto de un agitador. El aparato se coloca sobre una fuente gamma de {sup 60}Co. Los experimentos se efectuaron a temperaturas de 80 {+-}5{sup o}C y a presion atmosferica. La intensidad de dosis medida con ayuda de un

  7. Media Training

    CERN Multimedia

    CERN. Geneva

    2009-01-01

    With the LHC starting up soon, the world's media are again turning their attention to CERN. We're all likely to be called upon to explain what is happening at CERN to media, friends and neighbours. The seminar will be given by BBC television news journalists Liz Pike and Nadia Marchant, and will deal with the kind of questions we're likely to be confronted with through the restart period. The training is open for everybody. Make sure you arrive early enough to get a seat - there are only 200 seats in the Globe. The session will also be webcast: http://webcast.cern.ch/

  8. Social Media Sites

    Science.gov (United States)

    Media Sites Site Registration Contact Us Search AF.mil: Home > AF Sites > Social Media Sites Social Media Welcome to the Air Force social media directory! The directory is a one-stop shop of official Air Force social media pages across various social media sites. Social media is all about

  9. Method for removing dissolved oxygen from aqueous media

    International Nuclear Information System (INIS)

    Silva, S.G. de.

    1985-01-01

    Water for use in steam generation systems, which is contained in a storage tank, is deoxygenated for use in the system by adding hydrogen to a stream of the water and intimately mixing the same, pressurizing the stream to a pressure of 60 to 150 psig, and contacting the pressurized stream with a catalyst bed of palladium or platinum dispersed on a solid carrier. The hydrogen reacts with the dissolved oxygen in the presence of the catalyst at ambient temperatures, to produce a deoxygenated stream of water containing less than 10 ppb of oxygen. The deoxygenated water can be returned to the storage tank or supplied directly to the steam generation system. (author)

  10. Electrostratic stabilization of suspensions in non-aqueous media

    NARCIS (Netherlands)

    Hoeven, van der P.C.

    1991-01-01

    Concentrated suspensions of detergent powder solids in a liquid nonionic surfactant are considered for practical application as liquid detergent products. If no precautions are taken, upon storage the viscosity of such suspensions increases and the pourability drops because the suspensions are

  11. Removal of selected pollutants from aqueous media by hardwood mulch

    International Nuclear Information System (INIS)

    Ray, Asim B.; Selvakumar, Ariamalar; Tafuri, Anthony N.

    2006-01-01

    Generic hardwood mulch, usually used for landscaping, was utilized to remove several selected pollutants (heavy metals and toxic organic compounds) typically found in urban stormwater (SW) runoff. The hardwood mulch sorbed all the selected pollutants from a spiked stormwater mixture, including copper (Cu 2+ ), cadmium (Cd 2+ ), chromium (Cr 6+ ), lead (Pb 2+ ), zinc (Zn 2+ ), 1,3 dichlorobenzene (DCB), naphthalene (NP), fluoranthene (FA), butylbenzylphthalate (BBP), and benzo(a)pyrene (B[a]P). Masses of the pollutants sorbed depended upon the pollutant species, contact time, and initial concentration which varied from 20 to 100%. Sorption rates of the metals, in general, were more rapid than those of the organics; however, mass removals (percent) of the organics, in contrast to those of the metals, were independent of their initial concentrations. With the exception of Cd, percentages (weight) of the metals removed declined as their initial concentrations decreased. None of the sorbed pollutants desorbed to any significant extent upon extended washing with water. It is quite feasible that in the presence of mulch the uptake of these pollutants by the aquatic species will be reduced significantly

  12. Microwave-Assisted Synthesis – Catalytic Applications in Aqueous Media

    Science.gov (United States)

    The development of sustainable methods directed towards the synthesis of molecules is due to the heightened awareness and recognition of alternative eco-friendly and economical protocols that have minimum impact on environment. Among others, microwave (MW)-assisted methodology ha...

  13. Alteration mechanisms of UOX spent fuel in aqueous media

    International Nuclear Information System (INIS)

    Muzeau, B.

    2007-06-01

    The mechanisms of underwater alteration of spent fuels need to be understood on the assumption of a direct disposal of the assemblies in a geological formation or for long duration storage in pool. This work is a contribution to the study of the effects of the alpha and/or beta/gamma radiolysis of water on the oxidation and the dissolution of the UO 2 matrix of UOX spent fuel. The effects of the alpha radiolysis, predominant in geological disposal conditions, were quantified using samples of UO 2 doped with plutonium. The leaching experiments highlighted two types of control for the matrix alteration according to the alpha activity. The first is based on the radiolytic oxidation of the surface and leads to a continuous release of uranium in solution whereas the second is based on a control by the solubility of uranium. An activity threshold, located between 18 MBq/g and 33 MBq/g, was defined in a carbonated water. The value of this threshold is dependent on the experimental conditions and the presence or not of electro-active species such as hydrogen in the system. The effects of the alpha/beta/gamma radiolysis in relation with the storage conditions were also quantified. The experimental data obtained on spent fuel indicate that the alteration rate of the matrix based on the behaviour of tracer elements (caesium and strontium) reached a maximum value of some mg.m -2 .d -1 , even under very oxidizing conditions. The solubility of uranium and the nature of the secondary phases depend however on the extent of the oxidizing conditions. (author)

  14. Rates of ionic reactions with charged nanoparticles in aqueous media

    NARCIS (Netherlands)

    Duval, J.F.L.; Leeuwen, van H.P.

    2012-01-01

    A theory is developed to evaluate the electrostatic correction for the rate of reaction between a small ion and a charged ligand nanoparticle. The particle is assumed to generally consist of an impermeable core and a shell permeable to water and ions. A derivation is proposed for the ion diffusion

  15. Oxidation of hydrogen peroxide by [Ni (cyclam)] in aqueous acidic ...

    Indian Academy of Sciences (India)

    Oxidation of hydrogen peroxide by tris(2,2 -bipyridine) and tris(4,4 -dimethyl-2,2 - bipyridine) complexes of osmium(III), iron(III), ruthenium(III), and nickel(III) studied in acidic and neutral aqueous media, show an inverse acid depen- dence over the pH the range 6.0–8.5.12 Kinetic mea- surements with an excess of H2O2 ...

  16. Aqueous radioactive waste bituminization

    International Nuclear Information System (INIS)

    Williamson, A.S.

    1980-08-01

    The bituminzation of decontamination and ion exchange resin stripping wastes with four grades of asphalt was investigated to determine the effects of asphalt type on the properties of the final products. All waste forms deformed readily under light loads indicating they would flow if not restrained. It was observed in all cases that product leaching rates increased as the hardness of the asphalt used to treat the waste increased. If bituminization is adopted for any Ontario Hydro aqueous radioactive wastes they should be treated with soft asphalt to obtain optimum leaching resistance and mechanical stability during interim storage should be provided by a corrosion resistant container

  17. Contrast media

    International Nuclear Information System (INIS)

    Decazes, Ph.

    2004-01-01

    The Guerbet firm, which holds 69% of the capital on the contrast media for medical imagery, could sale about 20% of this capital in order to accelerate its development in the United States, one of its next market with the Japan. (O.M.)

  18. Otitis media

    NARCIS (Netherlands)

    Rovers, MM; Schilder, AGM; Zielhuis, GA; Rosenfeld, RM

    2004-01-01

    Otitis media (OM) continues to be one of the most common childhood infections and is a major cause of morbidity in children. The pathogenesis of OM is multifactorial, involving the adaptive and native immune system, Eustachian-tube dysfunction, viral and bacterial load, and genetic and environmental

  19. Social Media

    Science.gov (United States)

    2010-05-01

    Digital Marketing and Ecommerce Professionals. 29 January 2010. 20 May 2010. <http://econsultancy.com/blog/5324-20+-mind-blowing-social- media...Statistics Revisited.” Econsultancy | Community of Digital Marketing and Ecommerce Professionals. 29 Jan. 2010. 20 May 2010. <http://econsultancy.com/blog

  20. Streaming Media

    Science.gov (United States)

    Pulley, John

    2009-01-01

    At a time when the evolutionary pace of new media resembles the real-time mutation of certain microorganisms, the age-old question of how best to connect with constituents can seem impossibly complex--even for an elite institution plugged into the motherboard of Silicon Valley. Identifying the most effective vehicle for reaching a particular…

  1. Substituent effects on an inverse electron demand hetero Diels-Alder reaction in aqueous solution and organic solvents : Cycloaddition of substituted styrenes to di(2-pyridyl)-1,2,4,5-tetrazine

    NARCIS (Netherlands)

    Wijnen, Jan W.; Zavarise, Silvia; Engberts, Jan B.F.N.; Charton, Marvin

    1996-01-01

    The kinetics of the Diels-Alder reactions of di(2-pyridyl)-1,2,4,5-tetrazine (1) with substituted styrenes 2 was investigated in aqueous media and in organic solvents. The second-order rate constants ofthis reaction increase dramatically in water-rich media. A decrease in pH accelerates the aqueous

  2. Mars aqueous chemistry experiment

    Science.gov (United States)

    Clark, Benton C.; Mason, Larry W.

    1994-06-01

    Mars Aqueous Chemistry Experiment (MACE) is designed to conduct a variety of measurements on regolith samples, encompassing mineral phase analyses, chemical interactions with H2O, and physical properties determinations. From these data, much can be learned or inferred regarding the past weathering environment, the contemporaneous soil micro-environments, and the general chemical and physical state of the Martian regolith. By analyzing both soil and duricrust samples, the nature of the latter may become more apparent. Sites may be characterized for comparative purposes and criteria could be set for selection of high priority materials on future sample return missions. The second year of the MACE project has shown significant progress in two major areas. MACE Instrument concept definition is a baseline design that has been generated for the complete MACE instrument, including definition of analysis modes, mass estimates and thermal model. The design includes multiple reagent reservoirs, 10 discrete analysis cells, sample manipulation capability, and thermal control. The MACE Measurement subsystems development progress is reported regarding measurement capabilities for aqueous ion sensing, evolved gas sensing, solution conductivity measurement, reagent addition (titration) capabilities, and optical sensing of suspended particles.

  3. Mars aqueous chemistry experiment

    Science.gov (United States)

    Clark, Benton C.; Mason, Larry W.

    1994-01-01

    Mars Aqueous Chemistry Experiment (MACE) is designed to conduct a variety of measurements on regolith samples, encompassing mineral phase analyses, chemical interactions with H2O, and physical properties determinations. From these data, much can be learned or inferred regarding the past weathering environment, the contemporaneous soil micro-environments, and the general chemical and physical state of the Martian regolith. By analyzing both soil and duricrust samples, the nature of the latter may become more apparent. Sites may be characterized for comparative purposes and criteria could be set for selection of high priority materials on future sample return missions. The second year of the MACE project has shown significant progress in two major areas. MACE Instrument concept definition is a baseline design that has been generated for the complete MACE instrument, including definition of analysis modes, mass estimates and thermal model. The design includes multiple reagent reservoirs, 10 discrete analysis cells, sample manipulation capability, and thermal control. The MACE Measurement subsystems development progress is reported regarding measurement capabilities for aqueous ion sensing, evolved gas sensing, solution conductivity measurement, reagent addition (titration) capabilities, and optical sensing of suspended particles.

  4. The IUPAC aqueous and non-aqueous experimental pKa data repositories of organic acids and bases.

    Science.gov (United States)

    Slater, Anthony Michael

    2014-10-01

    Accurate and well-curated experimental pKa data of organic acids and bases in both aqueous and non-aqueous media are invaluable in many areas of chemical research, including pharmaceutical, agrochemical, specialty chemical and property prediction research. In pharmaceutical research, pKa data are relevant in ligand design, protein binding, absorption, distribution, metabolism, elimination as well as solubility and dissolution rate. The pKa data compilations of the International Union of Pure and Applied Chemistry, originally in book form, have been carefully converted into computer-readable form, with value being added in the process, in the form of ionisation assignments and tautomer enumeration. These compilations offer a broad range of chemistry in both aqueous and non-aqueous media and the experimental conditions and original reference for all pKa determinations are supplied. The statistics for these compilations are presented and the utility of the computer-readable form of these compilations is examined in comparison to other pKa compilations. Finally, information is provided about how to access these databases.

  5. Microwave discharge electrodeless lamps (MDEL). Part VII. Photo-isomerization of trans-urocanic acid in aqueous media driven by UV light from a novel Hg-free Dewar-like microwave discharge thermally-insulated electrodeless lamp (MDTIEL). Performance evaluation.

    Science.gov (United States)

    Horikoshi, Satoshi; Sato, Tatsuro; Sakamoto, Kazutami; Abe, Masahiko; Serpone, Nick

    2011-07-01

    A novel mercury-free Dewar-like (double-walled structure) microwave discharge thermally-insulated electrodeless lamp (MDTIEL) was fabricated and its performance evaluated using the photo-isomerization of trans-urocanic acid (trans-UA) in aqueous media as a test process driven by the emitted UV light when ignited with microwave radiation. The photo-isomerization processes trans-UA → cis-UA and cis-UA → trans-UA were re-visited using light emitted from a conventional high-pressure Hg light source and examined for the influence of UV light irradiance and solution temperature; the temperature dependence of the trans → cis process displayed a negative activation energy, E(a) = -1.3 cal mol(-1). To control the photo-isomerization of urocanic acid from the heat usually dissipated by a microwave discharge electrodeless lamp (single-walled MDEL), it was necessary to suppress the microwave-initiated heat. For comparison, the gas-fill in the MDEL lamp, which typically consists of a mixture of Hg and Ar, was changed to the more eco-friendly N(2) gas in the novel MDTIEL device. The dynamics of the photo-isomerization of urocanic acid driven by the UV wavelengths of the N(2)-MDTIEL light source were compared to those from the more conventional single-walled N(2)-MDEL and Hg/Ar-MDEL light sources, and with those from the Hg lamp used to irradiate, via a fiber optic, the photoreactor located in the wave-guide of the microwave apparatus. The heating efficiency of a solution with the double-walled N(2)-MDTIEL was compared to the efficiency from the single-walled N(2)-MDEL device. Advantages of N(2)-MDTIEL are described from a comparison of the dynamics of the trans-UA → cis-UA process on the basis of unit surface area of the lamp and unit power consumption. The considerably lower temperature on the external surface of the N(2)-MDTIEL light source should make it attractive in carrying out photochemical reactions that may be heat-sensitive such as the photothermochromic

  6. Aqueous electrolytes for redox flow battery systems

    Science.gov (United States)

    Liu, Tianbiao; Li, Bin; Wei, Xiaoliang; Nie, Zimin; Wang, Wei; Liu, Jun; Sprenkle, Vincent L.

    2017-10-17

    An aqueous redox flow battery system includes an aqueous catholyte and an aqueous anolyte. The aqueous catholyte may comprise (i) an optionally substituted thiourea or a nitroxyl radical compound and (ii) a catholyte aqueous supporting solution. The aqueous anolyte may comprise (i) metal cations or a viologen compound and (ii) an anolyte aqueous supporting solution. The catholyte aqueous supporting solution and the anolyte aqueous supporting solution independently may comprise (i) a proton source, (ii) a halide source, or (iii) a proton source and a halide source.

  7. [Chronic otitis mediaChronic Otitis Media].

    Science.gov (United States)

    Kohles, N; Schulz, T; Eßer, D

    2015-11-01

    There are 2 different kinds of chronic otitis media: Otitis media chronica mesotympanalis and otitis media chronica epitympanalis (cholesteatoma). The incidence of chronic otitis media as reported in literature differs in a wide range. The incidence rates vary between 0.45 and 46%. Both, otitis media chronica mesotympanalis and cholesteatoma, lead to eardrum perforation due to lengthy and recurring inflammations. Furthermore, chronic otitis media is characterized by frequently recurring otorrhea and conductive hearing loss. Georg Thieme Verlag KG Stuttgart · New York.

  8. Non-Enzymatic biopolymerization reactions supported by heterogeneous media

    DEFF Research Database (Denmark)

    Monnard, Pierre-Alain

    2011-01-01

    Heterogeneous media, such as micro-structured aqueous environments, could offer an alternative approach to the synthesis of biopolymers with novel functions. Structured media are here defined as specialized, self-assembled structures that are formed, e.g, by amphiphiles, such as liposomes, emulsion...... compartments and lipid-bilayer lattices. Another kind of media is represented by co-existing, self-assembled phases in the reaction medium, e.g., in water-ice matrices. These media have the capacity to assemble chemical molecules or complex catalytic assemblies into unique configurations that are unstable...

  9. On Media Education

    Science.gov (United States)

    Fedorov, Alexander

    2008-01-01

    This monograph analyzes the theory and practice of media education and media literacy. The book also includes the list of Russian media education literature and addresses of websites of the associations for media education.

  10. Otitis media.

    Science.gov (United States)

    Schilder, Anne G M; Chonmaitree, Tasnee; Cripps, Allan W; Rosenfeld, Richard M; Casselbrant, Margaretha L; Haggard, Mark P; Venekamp, Roderick P

    2016-09-08

    Otitis media (OM) or middle ear inflammation is a spectrum of diseases, including acute otitis media (AOM), otitis media with effusion (OME; 'glue ear') and chronic suppurative otitis media (CSOM). OM is among the most common diseases in young children worldwide. Although OM may resolve spontaneously without complications, it can be associated with hearing loss and life-long sequelae. In developing countries, CSOM is a leading cause of hearing loss. OM can be of bacterial or viral origin; during 'colds', viruses can ascend through the Eustachian tube to the middle ear and pave the way for bacterial otopathogens that reside in the nasopharynx. Diagnosis depends on typical signs and symptoms, such as acute ear pain and bulging of the tympanic membrane (eardrum) for AOM and hearing loss for OME; diagnostic modalities include (pneumatic) otoscopy, tympanometry and audiometry. Symptomatic management of ear pain and fever is the mainstay of AOM treatment, reserving antibiotics for children with severe, persistent or recurrent infections. Management of OME largely consists of watchful waiting, with ventilation (tympanostomy) tubes primarily for children with chronic effusions and hearing loss, developmental delays or learning difficulties. The role of hearing aids to alleviate symptoms of hearing loss in the management of OME needs further study. Insertion of ventilation tubes and adenoidectomy are common operations for recurrent AOM to prevent recurrences, but their effectiveness is still debated. Despite reports of a decline in the incidence of OM over the past decade, attributed to the implementation of clinical guidelines that promote accurate diagnosis and judicious use of antibiotics and to pneumococcal conjugate vaccination, OM continues to be a leading cause for medical consultation, antibiotic prescription and surgery in high-income countries.

  11. The aqueous chemistry of oxides

    CERN Document Server

    Bunker, Bruce C

    2016-01-01

    The Aqueous Chemistry of Oxides is a comprehensive reference volume and special topics textbook that explores all of the major chemical reactions that take place between oxides and aqueous solutions. The book highlights the enormous impact that oxide-water reactions have in advanced technologies, materials science, geochemistry, and environmental science.

  12. Review Of Applied Mathematical Models For Describing The Behaviour Of Aqueous Humor In Eye Structures

    Science.gov (United States)

    Dzierka, M.; Jurczak, P.

    2015-12-01

    In the paper, currently used methods for modeling the flow of the aqueous humor through eye structures are presented. Then a computational model based on rheological models of Newtonian and non-Newtonian fluids is proposed. The proposed model may be used for modeling the flow of the aqueous humor through the trabecular meshwork. The trabecular meshwork is modeled as an array of rectilinear parallel capillary tubes. The flow of Newtonian and non-Newtonian fluids is considered. As a results of discussion mathematical equations of permeability of porous media and velocity of fluid flow through porous media have been received.

  13. Media matters.

    Science.gov (United States)

    Martinez, L M

    1995-01-01

    The impact of the mass media on woman's status was addressed at two 1995 conferences: the Fourth World Conference on Women, held in Beijing, China, and the Congress of the World Association for Christian Communication, held in Puebla, Mexico. The globalization process facilitated by the mass media has served to increase the power of patriarchy, with no advantages to the cause of women's rights. Coverage of popular movements has been suppressed out of deference to male-controlled governments. Coverage of the Beijing Conference highlighted celebrities and personal stories, to the exclusion of the economic and political issues under debate. Television has commodified women, reinforcing their oppression. On the other hand, the alternative media, which tend to be decentralized, democratic, low-cost, and low in technology, are presenting women as subjects rather than objects and deconstructing gender stereotypes. Of concern, however, is the tendency of computer technology to widen the gap between social classes and developed and developing countries. Women must use information networks to disseminate information on women's rights and strengthen the links between women throughout the world.

  14. Aqueous reprocessing - some dreams!

    International Nuclear Information System (INIS)

    Srinivasan, T.G.

    2015-01-01

    India has been pursuing a aqueous reprocessing based closed fuel cycle for both thermal and fast reactor fuels employing the PUREX process. Though the country has more than six decades of experience, the dreams or wish lists such as, a highly efficient process with textbook specifications of 99.9% recovery of U and Pu, a DF of more than 10 7 for both U and Pu from the fission products, operating with name plate capacity with high safety, low waste generation, recovery of useful fission products and minor actinides from high level waste are never ceasing and ever growing. The talk will cover safety precautions and actions to be taken in the steps listed below, to ensure a safe and successful process

  15. Aqueous chemical dosimetry

    International Nuclear Information System (INIS)

    Matthews, R.W.

    1982-01-01

    Aqueous chemical dosimetry based on ceric and ferrous sulfate solutions and on a number of fluorescence-induced systems is reviewed. Particular attention is given to the factors affecting the response of these dosimeters to radiation and the corrections necessary for more accurate dosimetry under various irradiation conditions. The effect of cerous and ceric ion, oxygen, and sulfuric acid concentration on the ceric dosimeter is discussed together with the effects of temperature, energy of radiation, degraded energy spectra, and peroxysulfuric acids. Practical aspects of ceric/cerous dosimetry are given. Although ferrous sulfate solution is the most important and widely studied reference dosimeter, general agreement has not been reached on the ''best'' value for the molar extinction coefficient of ferric ions nor on the correction necessary to the G(Fe 3 - ) value for irradiations at temperatures significantly different from 25 0 C. New data are presented which indicate that the larger temperature coefficients given in the literature are more accurate. The ferrous sulfate system has been of great importance in establishing the primary radiolytic yields for 0.4 M sulfuric acid solution; it is shown how the failure to take into account the effect of oxygen and ferrous sulfate concentrations has led to erroneously high estimates of the zero solute concentration values in acid solutions. Some of the methods for extending the dose ranges measurable with ferrous sulfate-based solutions are reviewed. Substances which on irradiation give highly fluorescent products are among the most sensitive aqueous chemical dosimeters. These include benzoate and terephthalate solutions and the more recent coumarin and trimesate solutions. Advantages and disadvantages system are discussed. (author)

  16. Media Education Initiatives by Media Organizations: The Uses of Media Literacy in Hong Kong Media

    Science.gov (United States)

    Chu, Donna; Lee, Alice Y. L.

    2014-01-01

    As more media organizations have engaged in media education, this paper investigates the goals and practices of these activities. This article coins media education initiatives by media organizations with the term "media-organization media literac"y (MOML). Four MOML projects in Hong Kong were selected for examination. Built on critical…

  17. Nonequilibrium gas absorption in rotating permeable media

    Science.gov (United States)

    Baev, V. K.; Bazhaikin, A. N.

    2016-08-01

    The absorption of ammonia, sulfur dioxide, and carbon dioxide by water and aqueous solutions in rotating permeable media, a cellular porous disk, and a set of spaced-apart thin disks has been considered. The efficiency of cleaning air to remove these impurities is determined, and their anomalously high solubility (higher than equilibrium value) has been discovered. The results demonstrate the feasibility of designing cheap efficient rotor-type absorbers to clean gases of harmful impurities.

  18. Media Matter

    Directory of Open Access Journals (Sweden)

    Holger Pötzsch

    2017-02-01

    Full Text Available The present contribution maps materialist advances in media studies. Based on the assumption that matter and materiality constitute significant aspects of communication processes and practices, I introduce four fields of inquiry - technology, political economy, ecology, and the body - and argue that these perspectives enable a more comprehensive understanding of the implications of contemporary technologically afforded forms of interaction. The article shows how each perspective can balance apologetic and apocalyptic approaches to the impact of in particular digital technologies, before it demonstrates the applicability of an integrated framework with reference to the techno-politics of NSA surveillance and the counter-practices of WikiLeaks.

  19. Media education and media influence on youth

    OpenAIRE

    LILÁK, Karel

    2011-01-01

    Bachelor´s work is focused on the questions of the medial education and the medias themselves. This work also investigate with the influence of the action of medias to the students of apprenticeship. The first part of the theoretical work has generally explains what is media education, what is its significance for society and for the benefit of education in school. They are given functions, types and objectives of media education and communications capabilities via the media. The second part ...

  20. Mars Aqueous Processing System

    Science.gov (United States)

    Berggren, Mark; Wilson, Cherie; Carrera, Stacy; Rose, Heather; Muscatello, Anthony; Kilgore, James; Zubrin, Robert

    2012-01-01

    The goal of the Mars Aqueous Processing System (MAPS) is to establish a flexible process that generates multiple products that are useful for human habitation. Selectively extracting useful components into an aqueous solution, and then sequentially recovering individual constituents, can obtain a suite of refined or semi-refined products. Similarities in the bulk composition (although not necessarily of the mineralogy) of Martian and Lunar soils potentially make MAPS widely applicable. Similar process steps can be conducted on both Mars and Lunar soils while tailoring the reaction extents and recoveries to the specifics of each location. The MAPS closed-loop process selectively extracts, and then recovers, constituents from soils using acids and bases. The emphasis on Mars involves the production of useful materials such as iron, silica, alumina, magnesia, and concrete with recovery of oxygen as a byproduct. On the Moon, similar chemistry is applied with emphasis on oxygen production. This innovation has been demonstrated to produce high-grade materials, such as metallic iron, aluminum oxide, magnesium oxide, and calcium oxide, from lunar and Martian soil simulants. Most of the target products exhibited purities of 80 to 90 percent or more, allowing direct use for many potential applications. Up to one-fourth of the feed soil mass was converted to metal, metal oxide, and oxygen products. The soil residue contained elevated silica content, allowing for potential additional refining and extraction for recovery of materials needed for photovoltaic, semiconductor, and glass applications. A high-grade iron oxide concentrate derived from lunar soil simulant was used to produce a metallic iron component using a novel, combined hydrogen reduction/metal sintering technique. The part was subsequently machined and found to be structurally sound. The behavior of the lunar-simulant-derived iron product was very similar to that produced using the same methods on a Michigan iron

  1. Rheological Properties of Aqueous Nanometric Alumina Suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chuanping [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    Colloidal processing is an effective and reliable approach in the fabrication of the advanced ceramic products. Successful colloidal processing of fine ceramic powders requires accurate control of the rheological properties. The accurate control relies on the understanding the influences of various colloidal parameters on the rheological properties. Almost all research done on the rheology paid less attention to the interactions of particle and solvent. However, the interactions of the particles are usually built up through the media in which the particles are suspended. Therefore, interactions of the particle with the media, the adsorbed layers on the particle surface, and chemical and physical properties of media themselves must influence the rheology of the suspension, especially for the dense suspensions containing nanosized particles. Relatively little research work has been reported in this area. This thesis addresses the rheological properties of nanometric alumina aqueous suspensions, and paying more attention to the interactions between particle and solvent, which in turn influence the particle-particle interactions. Dense nanometric alumina aqueous suspensions with low viscosity were achieved by environmentally-benign fructose additives. The rheology of nanometric alumina aqueous suspensions and its variation with the particle volume fraction and concentration of fructose were explored by rheometry. The adsorptions of solute (fructose) and solvent (water) on the nanometric alumina particle surfaces were measured and analyzed by TG/DSC, TOC, and NMR techniques. The mobility of water molecules in the suspensions and its variation with particle volume fractions and fructose additive were determined by the 17O NMR relaxation method. The interactions between the nanometric alumina particles in water and fructose solutions were investigated by AFM. The results indicated that a large number of water layers were physically bound on the particles

  2. Novel synthetic approach for 1, 4-dihydroxyanthraquinone and the development of its Lithiated salts as anode material for aqueous rechargeable Lithium-ion batteries

    KAUST Repository

    Gurukar, Suresh Shivappa; Rajashekara Shetty, Vijeth; Mariappa, Ramaiah; Kittappa, Mahadevan Malavalli; Nagaraju, Doddahalli H.

    2015-01-01

    of active species in the aqueous media, reasonable discharge capacity with 0.9 V average voltages and agreeable cycling performance during charge-discharge process with reproducibility are achieved. For the construction of the full cell, the anode material

  3. Aqueous chemistry of transactinides

    International Nuclear Information System (INIS)

    Schaedel, M.

    2001-01-01

    The aqueous chemistry of the first three transactinide elements is briefly reviewed with special emphasis given to recent experimental results. Short introductory remarks are discussing the atom-at-a-time situation of transactinide chemistry as a result of low production cross-sections and short half-lives. In general, on-line experimental techniques and, more specifically, the automated rapid chemistry apparatus, ARCA, are presented. Present and future developments of experimental techniques and resulting perspectives are outlined at the end. The central part is mainly focussing on hydrolysis and complex formation aspects of the superheavy group 4, 5, and 6 transition metals with F - and Cl - anions. Experimental results are compared with the behaviour of lighter homologous elements and with relativistic calculations. It will be shown that the chemical behaviour of the first superheavy elements is already strongly influenced by relativistic effects. While it is justified to place rutherfordium, dubnium and seaborgium in the Periodic Table of the Elements into group 4, 5 and 6, respectively, it is no more possible to deduce from this position in detail the chemical properties of these transactinide or superheavy elements. (orig.)

  4. Synthesis and electrochemical characterization of palladium-based cathode catalysts, resistant to the presence of methanol; Sintesis y caracterizacion electroquimica de catalizadores catodicos base paladio, resistentes a la presencia de metanol

    Energy Technology Data Exchange (ETDEWEB)

    Salvador, Jose J. [Centro de Investigacion y de Estudios Avanzados del IPN, Mexico D.F. (Mexico)] e-mail: jsalvador@cinvestav.mx; Collins, Virginia H. [Centro de Investigacion en Materiales Avanzados, Chihuahua, Chihuahua (Mexico); Solorza Feria, Omar [Centro de Investigacion y de Estudios Avanzados del IPN, Mexico D.F. (Mexico)

    2009-09-15

    This work presents the synthesis and characterization of palladium-based electrocatalysts (PdSn and PdPtSn) prepared with the salt-reduction method for oxygen reduction reaction (ORR). The compounds obtained are characterized by sweep electron microscopy, electron transmission microscopy and x-ray diffraction of powder. The electrocatalysts obtained had particle sizes less than 10 nm. The evaluation of the catalytic activity of the catalysts was performed using cyclic voltametry and rotating disc electrode. These experiments were conducted in an H{sub 2}SO{sub 4} 0.5 M solution with different methanol concentrations. The presence of methanol improved the catalytic activity of PdSn, but did not show any effect on the PdPtSn alloy. The performance of the DMFC mono cell using PdPtSn as a cathode showed a potential of 10 mW cm{sup -2} at 50 degrees Celsius. [Spanish] En este trabajo se presenta la sintesis y caracterizacion de electrocatalizadores de base Paladio (PdSn y PdPtSn) preparados mediante el metodo de reduccion de sales, para la reaccion de reduccion de oxigeno (RRO). Los compuestos obtenidos se caracterizaron por microscopia electronica de barrido, microscopia electronica de transmision y difraccion de rayos X de polvos. Los electrocatalizadores obtenidos presentaron un tamano de particula menores a 10 nm. La evaluacion de la actividad catalitica de los catalizadores se llevo a cabo mediante voltametria Ciclica y electrodo de disco rotatorio, estos experimentos fueron realizados en una solucion de H{sub 2}SO{sub 4} 0.5 M con diferentes concentraciones de metanol. La presencia de metanol mejoro la actividad catalitica de PdSn, pero no mostro ningun efecto sobre la aleacion PdPtSn. El desempeno de la monocelda de DMFC usando como catodo PdPtSn, mostro una potencia de 10 mW cm{sup -2} a 50 grados centigrados.

  5. ELECTROCHEMICAL BEHAVIOUR OF METHYLENE BLUE IN NON-AQUEOUS SOLVENTS

    International Nuclear Information System (INIS)

    Caram, J.A.; Suárez, J.F. Martínez; Gennaro, A.M.; Mirífico, M.V.

    2015-01-01

    Graphical abstract: Display Omitted - Highlights: • The dye is electro-reduced in two separated monoelectronic charge transfers. • Solvent/supporting electrolyte/acid/base modifies the electrochemical parameters. • A dissociation equilibrium of the dye in non-aqueous solvent is proposed. • The electro-generated and stable dye-radical is also chemically produced in EDA or KOH/DMF. • A new species is reversibly formed in KOH/EtOH or ACN. - Abstract: The electrochemical behaviour of methylene blue in solution of non-aqueous solvents with different supporting electrolytes was studied by cyclic voltammetry. Dye electro-reduction presents two well-defined processes of monoelectronic charge transfer yielding a free radical in the first process and an anion in the second electron transfer. Free radical and anion are long living species in some of the studied media. Effects of supporting electrolyte and solvent on the peak potentials, the peak current functions and the reversibility of the charge transfer processes are reported. A dissociation equilibrium of the dye in solution of non-aqueous solvents and the acid or base added determine markedly the electrochemical responses. In the particular cases of KOH/DMF or EDA basic media the chemical formation of the stable methylene blue radical was detected and it was characterized by EPR spectroscopy. A general reaction scheme is proposed

  6. Critical review of the chemistry and thermodynamics of technetium and some of its inorganic compounds and aqueous species

    International Nuclear Information System (INIS)

    Rard, J.A.

    1983-01-01

    Chemical and thermodynamic data for Technetium (Tc) and some of its inorganic compounds and aqueous species are reviewed here. Major emphasis is given to systems with potential geochemical applications, especially the geochemistry of radioactive waste disposal. Compounds considered include oxides, hydroxides, hydrates oxides, halides, oxyhalides, double halides, and sulfides. The aqueous species considered include those in both noncomplexing media (pertechnetates, technetates, aquo-ions, and hydrolyzed cations) and complexing media (halides, sulfates, and phosphates). Thermodynamic values are recommended for specific compounds and aqueous ions when reliable experimental data are available. Where thermodynamic data are inadequate or unavailable, the chemistry is still discussed to provide information about what needs to be measured, and which chemistry needs to be clarified. A major application of these thermodynamic data will be for chemical equilibrium modeling and for construction of potential-pH diagrams for aqueous solutions. Unfortunately, the present lack of data precludes such calculations for complexing aqueous media. The situation is much better for noncomplexing aqueous media, but the chemistry and thermodynamics of cationic Tc(V) species and hydrolyzed Tc(III) species are poorly understood. 240 references, 6 tables

  7. Managing Media: Segmenting Media Through Consumer Expectancies

    Directory of Open Access Journals (Sweden)

    Matt Eastin

    2014-04-01

    Full Text Available It has long been understood that consumers are motivated to media differently. However, given the lack of comparative model analysis, this assumption is without empirical validation, and thus, the orientation of segmentation from a media management perspective is without motivational grounds. Thus, evolving the literature on media consumption, the current study develops and compares models of media segmentation within the context of use. From this study, six models of media expectancies were constructed so that motivational differences between media (i.e., local and national newspapers, network and cable television, radio, and Internet could be observed. Utilizing higher order statistical analyses the data indicates differences across a model comparison approach for media motivations. Furthermore, these differences vary across numerous demographic factors. Results afford theoretical advancement within the literature of consumer media consumption as well as provide media planners’ insight into consumer choices.

  8. Progress in aqueous rechargeable batteries

    Directory of Open Access Journals (Sweden)

    Jilei Liu

    2018-01-01

    Full Text Available Over the past decades, a series of aqueous rechargeable batteries (ARBs were explored, investigated and demonstrated. Among them, aqueous rechargeable alkali-metal ion (Li+, Na+, K+ batteries, aqueous rechargeable-metal ion (Zn2+, Mg2+, Ca2+, Al3+ batteries and aqueous rechargeable hybrid batteries are standing out due to peculiar properties. In this review, we focus on the fundamental basics of these batteries, and discuss the scientific and/or technological achievements and challenges. By critically reviewing state-of-the-art technologies and the most promising results so far, we aim to analyze the benefits of ARBs and the critical issues to be addressed, and to promote better development of ARBs.

  9. aqueous root extract on spermatogenesis

    African Journals Online (AJOL)

    Four groups were gavaged with the whole plant or root aqueous extract in low or high doses. The male ... motility and morphology as well as chromatin integrity were evaluated. Results: Serum ... Treatment of disease began long ago with the.

  10. Geographic Media Literacy

    Science.gov (United States)

    Lukinbeal, Chris

    2014-01-01

    While the use of media permeates geographic research and pedagogic practice, the underlying literacies that link geography and media remain uncharted. This article argues that geographic media literacy incorporates visual literacy, information technology literacy, information literacy, and media literacy. Geographic media literacy is the ability…

  11. Adolescents and media literacy.

    Science.gov (United States)

    McCannon, Robert

    2005-06-01

    In the face of media industry consolidation, fewer people control media content which makes it harder for parents and citizens to know the research about media-related issues, such as video game violence, nutrition, and sexual risk-taking. Media literacy offers a popular and potentially successful way to counter the misinformation that is spread by Big Media public relations.

  12. Safety in online media – freedom of the media; safety of media actors and media education

    OpenAIRE

    Moeller, Ch

    2013-01-01

    In this paper, prepared for the international conference ‘Mass Media – Society – Education: Media Safety Problems’ at the Chelyabinsk State University’s Department for Journalism and Media Education from September 30 – October 3, 2013, I would like to address three dimensions of media safety and security in online media.

  13. SOCIAL MEDIA SECURITY

    Science.gov (United States)

    RESPONSIBILITY CENTCOM COALITION MEDIA SOCIAL MEDIA NEWS ARTICLES PRESS RELEASES IMAGERY VIDEOS TRANSCRIPTS VISITORS AND PERSONNEL FAMILY CENTER FAMILY READINESS CENTCOM WEBMAIL SOCIAL MEDIA SECURITY ACCOUNTABILITY HomeVISITORS AND PERSONNELSOCIAL MEDIA SECURITY FAQ on Security for Social Media Due to the widespread use of

  14. Measuring News Media Literacy

    Science.gov (United States)

    Maksl, Adam; Ashley, Seth; Craft, Stephanie

    2015-01-01

    News media literacy refers to the knowledge and motivations needed to identify and engage with journalism. This study measured levels of news media literacy among 500 teenagers using a new scale measure based on Potter's model of media literacy and adapted to news media specifically. The adapted model posits that news media literate individuals…

  15. Development of the Aqueous Processes for Removing NOx from Flue Gases.

    Science.gov (United States)

    Chappell, Gilford A.

    A screening study was conducted to evaluate the capability of aqueous solutions to scrub NOx from the flue gases emitted by stationary power plants fired with fossil fuels. The report summarizes the findings of this laboratory program. The experimental program studied the following media for absorption of NOx from flue gases containing no NOx:…

  16. Effect of temperature and salting-out agents on the sorption of nitrophenols from aqueous solutions

    Directory of Open Access Journals (Sweden)

    E. V. Churilina

    2013-01-01

    Full Text Available Sorption of nitrophenols from aqueous media by сrosslinked N-vinylpyrrolidone-based polymer in static conditions are studied depending on the pH of the solution and the nature of the nitrophenols. It has been established that a temperature and the introduction of salting-out agents influence on the sorption of nitrophenols.

  17. Media Literacy in Times of Media Divides

    Directory of Open Access Journals (Sweden)

    Kaja Žuran

    2013-12-01

    Full Text Available We live in a post-modern society, an information society, a society based around knowledge and participation, and above all in a media society. In a media culture where media holds a dominant position, we cannot overlook the emerging idea of a ‘media divide’ within the frame of media education, media literate individuals and the expansion of the traditional concept of media literacy. Firstly, we are in an era of technological revolution, and it is time to consider the meaning and function of media and how we experience it in our everyday life. Secondly, as a society we are subject to intense media invasion and we all need to learn how to use it to our benefit and apply a critical and autonomous perspective towards selecting media content. Otherwise the media divide between the media literate and illiterate will widen; but is there even a chance to overcome the supposed divide between those who are formally media educated and those who are not?

  18. phenylalanine and l-tyrosine as chiral micellar media for the cat

    African Journals Online (AJOL)

    polar solvents [15-18]. Hence, surfactants offer the possibility for organic reactions to occur in aqueous media, and from the viewpoint of green chemistry, water is safer, harmless and environmentally benign [19]. However, there has been limited work on the use of chiral micellar media to catalyze Diels-. Alder reactions.

  19. Studies on the behavior of plutonium(IV) in alkaline carbonate/bicarbonate media

    International Nuclear Information System (INIS)

    Charyulu, M.M.; Satao, K.J.; Sivaramakrishnan, C.K.; Patil, S.K.

    1986-01-01

    Distribution ratios of plutonium(IV) between carbonate/bicarbonate media and strong base anion exchanger Amberlyst A-26 have been measured. Distribution ratio values are much higher in case of bicarbonate medium. The equilibrium was also achieved in a very short period in this medium. These data indicate feasibility of recovery of plutonium from such aqueous media using simple ion exchange method. (author)

  20. Otitis media with effusion

    Science.gov (United States)

    OME; Secretory otitis media; Serous otitis media; Silent otitis media; Silent ear infection; Glue ear ... from the tube and is swallowed. OME and ear infections are connected in two ways: After most ear ...

  1. Mutual diffusion of sodium hyaluranate in aqueous solutions

    International Nuclear Information System (INIS)

    Veríssimo, Luís M.P.; Valada, Teresa I.C.; Sobral, Abilio J.F.N.; Azevedo, Eduarda E.F.G.; Azevedo, Maria L.G.; Ribeiro, Ana C.F.

    2014-01-01

    Highlights: • Binary diffusion coefficients for the systems containing sodium hyaluronate. • Influence of the aggregation on diffusion of the sodium hyaluronate in the aqueous media. • Estimation of the thermodynamic and mobility factors from mutual diffusion. -- Abstract: The Taylor dispersion technique has been used for measuring mutual diffusion coefficients of sodium hyaluronate in aqueous solutions at T = 298.15 K, and concentrations ranging from (0.00 to 0.50) g · dm −3 . The results are interpreted on the basis of Nernst, and Onsager and Fuoss theoretical equations. From the diffusion coefficient at infinitesimal concentration, the limiting ionic conductivity and the tracer diffusion coefficient of hyaluronate ion were estimated. These studies have been complemented by molecular mechanics calculations

  2. Intermediality and media change

    OpenAIRE

    2012-01-01

    This book is about intermediality as an approach to analysing and understanding media change. Intermediality and Media Change is critical of technological determinism that characterises 'new media discourse' about the ongoing digitalization, framed as a revolution and creating sharp contrasts between old and new media. Intermediality instead emphasises paying attention to continuities between media of all types and privileges a comparative perspective on technological changes in media over ti...

  3. Media Pembelajaran Global Warming

    OpenAIRE

    Tham, Fikri Jufri; Liliana, Liliana; Purba, Kristo Radion

    2016-01-01

    Computer based learning media is one of the media has an important role in learning. Learning media will be attractive when packaged through interactive media , such as interactive media created in paper manufacture " instructional media global warming" . The advantage gained is that it can increase knowledge, generally educate people to be more concerned about the environment , and also can be a means of entertainment. This application is focused to learn about global warming and packaged in...

  4. Advanced Aqueous Separation Systems for Actinide Partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Nash, Ken [Washington State Univ., Pullman, WA (United States); Martin, Leigh [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lumetta, Gregg [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-04-02

    One of the most challenging aspects of advanced processing of used nuclear fuel is the separation of transplutonium actinides from fission product lanthanides. This separation is essential if actinide transmutation options are to be pursued in advanced fuel cycles, as lanthanides compete with actinides for neutrons in both thermal and fast reactors, thus limiting efficiency. The separation is difficult because the chemistry of Am3+ and Cm3+ is nearly identical to that of the trivalent lanthanides (Ln3+). The prior literature teaches that two approaches offer the greatest probability of devising a successful group separation process based on aqueous processes: 1) the application of complexing agents containing ligand donor atoms that are softer than oxygen (N, S, Cl-) or 2) changing the oxidation state of Am to the IV, V, or VI state to increase the essential differences between Am and lanthanide chemistry (an approach utilized in the PUREX process to selectively remove Pu4+ and UO22+ from fission products). The latter approach offers the additional benefit of enabling a separation of Am from Cm, as Cm(III) is resistant to oxidation and so can easily be made to follow the lanthanides. The fundamental limitations of these approaches are that 1) the soft(er) donor atoms that interact more strongly with actinide cations than lanthanides form substantially weaker bonds than oxygen atoms, thus necessitating modification of extraction conditions for adequate phase transfer efficiency, 2) soft donor reagents have been seen to suffer slow phase transfer kinetics and hydro-/radiolytic stability limitations and 3) the upper oxidation states of Am are all moderately strong oxidants, hence of only transient stability in media representative of conventional aqueous separations systems. There are examples in the literature of both approaches having been described. However, it is not clear at present that any extant process is sufficiently robust for application at the scale

  5. Social media management and media environment

    Directory of Open Access Journals (Sweden)

    Šiđanin Iva

    2012-01-01

    Full Text Available The paper deals with the system of services that social media management can offer to a variety of users. As social media systems are emerging, social media management can strengthen teams in social media and help to manage numerous social channels and distribution of social information from one place. Social media management is a system of procedures that are used to manage the flow of information in the environment of social media. This involves connecting with social media like Facebook, Twitter, LinkedIn, Plaxo, Ecademy, YouTube and many others, then the aggregation and management of social data. Social media management services are analysed through various fields, such as managing multiple social media profiles, mail scheduling and filtering, reporting and analytics. Social media management enables managing personal business through social media, which contributes to a significant reduction in expenditures. The paper also discusses the importance of social media management in marketing activities and various forms of social promotion, which allow companies to easily reach their customers.

  6. Evaluation, engineering and development of advanced cyclone processes. Final separating media evaluation and test report (FSMER). Appendices

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-05-01

    This report consists of appendices pertaining to the separating media evaluation (calcium nitrate solution) and testing for an advanced cyclone process. Appendices include: materials safety data, aqueous medium regeneration, pH control strategy, and other notes and data.

  7. Aqueous organic chemistry in the atmosphere: sources and chemical processing of organic aerosols.

    Science.gov (United States)

    McNeill, V Faye

    2015-02-03

    Over the past decade, it has become clear that aqueous chemical processes occurring in cloud droplets and wet atmospheric particles are an important source of organic atmospheric particulate matter. Reactions of water-soluble volatile (or semivolatile) organic gases (VOCs or SVOCs) in these aqueous media lead to the formation of highly oxidized organic particulate matter (secondary organic aerosol; SOA) and key tracer species, such as organosulfates. These processes are often driven by a combination of anthropogenic and biogenic emissions, and therefore their accurate representation in models is important for effective air quality management. Despite considerable progress, mechanistic understanding of some key aqueous processes is still lacking, and these pathways are incompletely represented in 3D atmospheric chemistry and air quality models. In this article, the concepts, historical context, and current state of the science of aqueous pathways of SOA formation are discussed.

  8. Separation of Nanoparticles in Aqueous Multiphase Systems through Centrifugation

    KAUST Repository

    Akbulut, Ozge; Mace, Charles R.; Martinez, Ramses V.; Kumar, Ashok A.; Nie, Zhihong; Patton, Matthew R.; Whitesides, George M.

    2012-01-01

    This paper demonstrates the use of aqueous multiphase systems (MuPSs) as media for rate-zonal centrifugation to separate nanoparticles of different shapes and sizes. The properties of MuPSs do not change with time or during centrifugation; this stability facilitates sample collection after separation. A three-phase system demonstrates the separation of the reaction products (nanorods, nanospheres, and large particles) of a synthesis of gold nanorods, and enriches the nanorods from 48 to 99% in less than ten minutes using a benchtop centrifuge. © 2012 American Chemical Society.

  9. Separation of Nanoparticles in Aqueous Multiphase Systems through Centrifugation

    KAUST Repository

    Akbulut, Ozge

    2012-08-08

    This paper demonstrates the use of aqueous multiphase systems (MuPSs) as media for rate-zonal centrifugation to separate nanoparticles of different shapes and sizes. The properties of MuPSs do not change with time or during centrifugation; this stability facilitates sample collection after separation. A three-phase system demonstrates the separation of the reaction products (nanorods, nanospheres, and large particles) of a synthesis of gold nanorods, and enriches the nanorods from 48 to 99% in less than ten minutes using a benchtop centrifuge. © 2012 American Chemical Society.

  10. Benchmarking uranyl peroxide capsule chemistry in organic media

    Energy Technology Data Exchange (ETDEWEB)

    Neal, Harrison A.; Nyman, May [Department of Chemistry, Oregon State University, Corvallis, OR (United States); Szymanowski, Jennifer; Fein, Jeremy B.; Burns, Peter C. [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN (United States)

    2017-01-03

    Uranyl peroxide capsules are a recent addition to polyoxometalate (POM) chemistry. Ten years of development has ensued only in water, while transition metal POMs are commonly exploited in aqueous and organic media, controlled by counterions or ligation to render the clusters hydrophilic or hydrophobic. Here, new uranyl POM behavior is recognized in organic media, including (1) stabilization and immobilization of encapsulated hydrophilic countercations, identified by Li nuclear magnetic resonance (NMR) spectroscopy, (2) formation of new cluster species upon phase transfer, (3) extraction of uranyl clusters from different starting materials including simulated spent nuclear fuel, (4) selective phase transfer of one cluster type from a mixture, and (5) phase transfer of clusters from both acidic and alkaline media. The capsule morphology of the uranyl POMs renders accurate characterization by X-ray scattering, including the distinction of geometrically similar clusters. Compositional analysis of the aqueous phase post-extraction provided a quantitative determination of the ion exchange process that enables transfer of the clusters into the organic phase. Preferential partitioning of uranyl POMs into organic media presents new frontiers in metal ion behavior and chemical reactions in the confined space of the cluster capsules in hydrophobic media, as well as the reactivity of clusters at the organic/aqueous interface. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Benchmarking uranyl peroxide capsule chemistry in organic media

    International Nuclear Information System (INIS)

    Neal, Harrison A.; Nyman, May; Szymanowski, Jennifer; Fein, Jeremy B.; Burns, Peter C.

    2017-01-01

    Uranyl peroxide capsules are a recent addition to polyoxometalate (POM) chemistry. Ten years of development has ensued only in water, while transition metal POMs are commonly exploited in aqueous and organic media, controlled by counterions or ligation to render the clusters hydrophilic or hydrophobic. Here, new uranyl POM behavior is recognized in organic media, including (1) stabilization and immobilization of encapsulated hydrophilic countercations, identified by Li nuclear magnetic resonance (NMR) spectroscopy, (2) formation of new cluster species upon phase transfer, (3) extraction of uranyl clusters from different starting materials including simulated spent nuclear fuel, (4) selective phase transfer of one cluster type from a mixture, and (5) phase transfer of clusters from both acidic and alkaline media. The capsule morphology of the uranyl POMs renders accurate characterization by X-ray scattering, including the distinction of geometrically similar clusters. Compositional analysis of the aqueous phase post-extraction provided a quantitative determination of the ion exchange process that enables transfer of the clusters into the organic phase. Preferential partitioning of uranyl POMs into organic media presents new frontiers in metal ion behavior and chemical reactions in the confined space of the cluster capsules in hydrophobic media, as well as the reactivity of clusters at the organic/aqueous interface. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Synthesis and characterization of alanine boron hydrate for its use in thermal neutron dosimetry.; Sintesis y caracterizacion del borohidrato de alanina para su uso en dosimetria de neutrones termicos.

    Energy Technology Data Exchange (ETDEWEB)

    Yanez S, J C

    1994-07-01

    Alanine boron hydrate was synthesized for its possible use as intercomparison dosimeter for thermal neutron irradiation. The irradiations were performed in the Nuclear Reactor of the Nuclear Center of Mexico. The salt was prepared by reacting alanine and boric acid in a (1:1) stoichiometric ratio in neutral pH 7.5 aqueous solution and also in a basic pH 13 solution. The latter reaction was prepared with the addition of ammonia hydroxide (25%). Solutions were stirred and afterwards were let to evaporate. The obtained product in each reaction is a white solid. Dosimeters were prepared with the obtained reaction products and irradiated under thermal neutron flux of 5 x 10{sup 7} n/cm{sup 2} s. For 30 hours. The analysis of irradiated samples was made in a Variant E-15 Electron Paramagnetic Resonance spectrometer. The observed response of the samples prepared with the reaction product at the basic pH is approximately 50% higher than the neutral pH samples. In order to investigate the optimum signal enhancement samples were prepared in a basic pH medium in the following stoichiometric ratios: (1:0.5); (1:0.75); (1:1.25); (1:1.5) and (1:1.75). It was observed that the samples of the reaction (1:0.75) produced the higher response. The response was 2728% higher than the alanine only dosimeters. The reaction product was chemically characterized by X-ray diffraction, Nuclear Magnetic Resonance, Chromatography, Refractometry and Solubility tests. Results indicate that alanine boron hydrate is formed in basic media and in a stoichiometric ratio (1:0.75). The dosimetric characterization of alanine boron hydrate was performed, results are reported. It is concluded that alanine boron hydrate may be a good intercomparison dosimeter for thermal neutron irradiation. (Author).

  13. Media Literacy Bibliography.

    Science.gov (United States)

    Duncan, Barry

    1989-01-01

    Provides an up-to-date bibliography of resources available for teaching media literacy. Groups resources into the areas of media education methodology, mass media texts, general background, television, film, the news and medium of print, advertising, gender and the media, popular culture, popular music and rock video, periodicals, and…

  14. Understanding Social Media Logic

    OpenAIRE

    José van Dijck; Thomas Poell

    2013-01-01

    Over the past decade, social media platforms have penetrated deeply into the mech­anics of everyday life, affecting people's informal interactions, as well as institutional structures and professional routines. Far from being neutral platforms for everyone, social media have changed the conditions and rules of social interaction. In this article, we examine the intricate dynamic between social media platforms, mass media, users, and social institutions by calling attention to social media log...

  15. Social media influencer marketing

    OpenAIRE

    Isosuo, Heli

    2016-01-01

    The marketing field is changing simultaneously with the digital world. Social media is getting more and more important to marketers, and there is a need to stand out in the social media noise. Social media influencer marketing could be a good alternative to other types of marketing. A need from the consignor and the interest of the author were the motivations for conducting the study. Sääskilahti Consulting has a social media influencer network Somevaikuttajat, which is offering social media ...

  16. Synthesis and characterization of PdAg as a catalyst for oxygen reduction reaction in acid medium; Sintesis y caracterizacion de PdAg como catalizador para la reaccion de reduccion de oxigeno en medio acido

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Casillas, D. C.; Vazquez-Huerta, G.; Solorza-Feria, O. [Centro de Investigacion y de Estudios Avanzados del IPN, Mexico D.F. (Mexico)]. E-mail: dcmartinez@cinvestav.mx

    2009-09-15

    This work presents the synthesis of the binary compound PdAg and the electrochemical characterization for oxygen reduction reaction (ORR) in acid medium. The catalyst is obtained from the reduction of Pd(NO{sub 3}){sub 2}·2H{sub 2}O and AgNO{sub 3} with NaBH{sub 4} in THF. The synthesized compound was physically characterized with transmission electron microscopy (TEM), sweep electron microscopy (SEM) and x-ray diffraction (XRD) of powder. Electrochemical studies were conducted to determine the catalytic activity and intrinsic properties of the PdAg material for the ORR in acid medium using cyclic voltamperometry (CV), rotary disc electrode (RDE) and electrochemical impedance spectroscopy (EIS) in a solution of H{sub 2}SO{sub 4} 0.5 M at 25 degrees Celsius. The electrochemical current-potential responses were compared to those of palladium and platinum. The kinetic results showed an increase in the performance of the bimetallic electrocatalyst containing Ag as compared to pure Pd, but less than that obtained with nanometric Pt. The Tafel slopes obtained are roughly120 mV dec-1, similar to that reported for Pt and Pd and for other Ru-based electrocatalysts. [Spanish] En este trabajo se presentan la sintesis del compuesto binario PdAg y su caracterizacion electroquimica para la reaccion de reduccion de oxigeno (RRO) en medio acido. El catalizador se obtuvo a partir de la reduccion de Pd(NO{sub 3}){sub 2}·2H{sub 2}O y AgNO{sub 3} con NaBH{sub 4} en THF. El compuesto sintetizado se caracterizo fisicamente por microscopia electronica de transmision (MET), microscopia electronica de barrido (MEB) y difraccion de rayos X (DRX) de polvos. Se realizaron estudios electroquimicos para determinar la actividad catalitica y las propiedades intrinsecas del material de PdAg para la reaccion de reduccion de oxigeno (RRO) en medio acido, utilizando las tecnicas de voltamperometria ciclica (VC), electrodo disco rotatorio (EDR) y espectroscopia de impedancia electroquimica (EIE), en

  17. Synthesis and characterization of cobalt oxide and titanium mixtures using mechanical alloying and its response to oxygen reduction; Sintesis y caracterizacion de mezclas de oxidos de cobalto y titanio por aleado mecanico y su respuesta para la reduccion de oxigeno

    Energy Technology Data Exchange (ETDEWEB)

    Basurto S, R.; Bonifacio-Martinez, J.; Fernandez, S.M [Instituto Nacional de Investigaciones Nucleares, Ocoyoacac, Estado de Mexico (Mexico)]. E-mail: rafael.basurto@inin.gob.mx

    2009-09-15

    The synthesis of Co{sub 3}O{sub 4} and CoTiO{sub 3} oxides was conducted using mechanical alloying and combustion. Co{sub 3}O{sub 4} used was obtained using a SPEX ball mill with cobalt nitrate, Co(NO{sub 3})36H{sub 2}O plus urea, CH{sub 4}N{sub 2}O, in a molar ratio of 1:1 and a ball weight ratio of 1:4 with grinding times of 2.5 hours in an argon atmosphere. The material obtained after alloying underwent combustion at 400 degrees Celsius and 500 degrees Celsius, obtaining oxides of mixed cobalt valence. This material was mixed with TiO{sub 2} with a weight ratio of 1:1 and was mechanically alloyed with a ball weight ratio of 1:8; grinding was performed for 2.5 hours in argon atmosphere and it underwent combustion at 800 degrees Celsius. Characterization was performed using x-ray diffraction, low-vacuum sweep electron microscopy and EDS. The electrochemical performance was obtained in a galvanostat-potentiostat (Princenton Applied Research modelo 273). Both materials present electrocatalytic activity for oxygen reduction reaction in alkaline medium. [Spanish] La sintesis de los oxidos: Co{sub 3}O{sub 4} y CoTiO3 se realizo por la tecnica de aleado mecanico y combustion. El Co{sub 3}O{sub 4} utilizado, se obtuvo por con un molino de bolas SPEX, utilizando nitrato de cobalto, Co(NO{sub 3})36H{sub 2}O mas urea, CH{sub 4}N{sub 2}O, en una relacion molar 1:1.y una relacion en peso de bolas de 1:4 con tiempos de molienda de 2.5 horas, en atmosfera de argon, al termino del aleado el material obtenido se llevo a combustion a 400 grados centigrados y 500 grados centigrados, obteniendose el oxido de valencia mixta de cobalto. Este material se mezclo con TiO{sub 2}, en una relacion en peso de 1:1 y se aleo mecanicamente, con una relacion en peso de bolas de 1:8, por 2.5 horas de molienda en atmosfera de argon y llevandolo a combustion a 800 grados centigrados. La caracterizacion se hizo por: Difraccion de Rayos X, Microscopia Electronica de Barrido de Bajo Vacio y EDS El

  18. Synthesis of a red pigment from gold nanoparticles; Sintesis de un pigmento rojo a partir de nanopartIculas de oro

    Energy Technology Data Exchange (ETDEWEB)

    Mestre, S.; Palacios, M. D.; Agut, P.

    2012-07-01

    A simple method of synthesising red pigments for ceramic glazes, based on gold nanoparticles protected by a refractory oxide capsule, was developed. Gold nanoparticles of an appropriate size were obtained by reaction in an aqueous medium between an Au(III) solution and an ammonium bromide solution, keeping the Br- concentration low during the process. The gold nanoparticles were encapsulated by adding the protective oxide in colloid form and subsequently coagulating it, alkalinising the medium. Diethylen triamine was then added to encourage the interaction between the gold nanoparticles and the oxide nanoparticles. This was followed by adding carboxymethylcellulose to raise medium viscosity, and to avoid segregation and subsequent agglomeration of the gold nanoparticles during drying. The dry residue was directly usable as a glaze pigment without requiring further thermal treatments. Three protective oxides, namely SiO{sub 2}, Al{sub 2}O{sub 3}, and SnO{sub 2}, were tested. In the three cases, pigments with a high colouring strength were obtained, which gave rise to reds of different shades in the resulting test glaze. (Author)

  19. Synthesis and characterization of iron nano particles for the arsenic removal in water; Sintesis y caracterizacion de nanoparticulas de hierro para la remocion de arsenico en agua

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez M, O. E.

    2011-07-01

    The synthesis of iron nanoparticles for the removal of metallic ions in polluted waters has been during the last years study topic for different world organizations. This work presents a synthesis method of conditioned coal with iron nanoparticles starting from the use of leaves of pineapple crown, with the purpose of using it in arsenic removal processes in aqueous phase. For the synthesis of this material, the leaves of the pineapple crown were used like supports structure of the iron nanoparticles. First, the pyrolysis appropriate temperature was determined. For the preparation of the support material, this had contact with a ferric nitrate and hexamine solution, because the preparation of the material and the coal synthesis were realized during the pyrolysis process, where the hexamine molecules and the ferric nitrate react, causing the reduction of the iron particles and their dispersion on the support material, obtaining as product a conditioned coal with iron nanoparticles. For the characterization of the materials were used techniques as: Scanning electron microscopy, Transmission electron microscopy, X-Rays Diffraction), X-Ray photoelectron spectroscopy and Moessbauer spectroscopy; moreover was determined the isoelectric point and the density of surface sites. The arsenic sorption capacity of the materials was evaluated by means of the methodology type lots where was determined the sorption kinetics and isotherms in terms of arsenic concentration and mass. (Author)

  20. Enzymes from solvent-tolerant microbes: useful biocatalysts for non-aqueous enzymology.

    Science.gov (United States)

    Gupta, Anshu; Khare, S K

    2009-01-01

    Solvent-tolerant microbes are a newly emerging class that possesses the unique ability to thrive in the presence of organic solvents. Their enzymes adapted to mediate cellular and metabolic processes in a solvent-rich environment and are logically stable in the presence of organic solvents. Enzyme catalysis in non-aqueous/low-water media is finding increasing applications for the synthesis of industrially important products, namely peptides, esters, and other trans-esterification products. Solvent stability, however, remains a prerequisite for employing enzymes in non-aqueous systems. Enzymes, in general, get inactivated or give very low rates of reaction in non-aqueous media. Thus, early efforts, and even some recent ones, have aimed at stabilization of enzymes in organic media by immobilization, surface modifications, mutagenesis, and protein engineering. Enzymes from solvent-tolerant microbes appear to be the choicest source for studying solvent-stable enzymes because of their unique ability to survive in the presence of a range of organic solvents. These bacteria circumvent the solvent's toxic effects by virtue of various adaptations, e.g. at the level of the cytoplasmic membrane, by degradation and transformation of solvents, and by active excretion of solvents. The recent screening of these exotic microbes has generated some naturally solvent-stable proteases, lipases, cholesterol oxidase, cholesterol esterase, cyclodextrin glucanotransferase, and other important enzymes. The unique properties of these novel biocatalysts have great potential for applications in non-aqueous enzymology for a range of industrial processes.

  1. Recent results on aqueous electrolyte cells

    KAUST Repository

    Wessells, Colin; Huggins, Robert A.; Cui, Yi

    2011-01-01

    The improved safety of aqueous electrolytes makes aqueous lithium-ion batteries an attractive alternative to commercial cells utilizing flammable and expensive organic electrolytes. Two important issues relating to their use have been addressed

  2. Enzyme Stability and Activity in Non-Aqueous Reaction Systems: A Mini Review

    Directory of Open Access Journals (Sweden)

    Shihui Wang

    2016-02-01

    Full Text Available Enormous interest in biocatalysis in non-aqueous phase has recently been triggered due to the merits of good enantioselectivity, reverse thermodynamic equilibrium, and no water-dependent side reactions. It has been demonstrated that enzyme has high activity and stability in non-aqueous media, and the variation of enzyme activity is attributed to its conformational modifications. This review comprehensively addresses the stability and activity of the intact enzymes in various non-aqueous systems, such as organic solvents, ionic liquids, sub-/super-critical fluids and their combined mixtures. It has been revealed that critical factors such as Log P, functional groups and the molecular structures of the solvents define the microenvironment surrounding the enzyme molecule and affect enzyme tertiary and secondary structure, influencing enzyme catalytic properties. Therefore, it is of high importance for biocatalysis in non-aqueous media to elucidate the links between the microenvironment surrounding enzyme surface and its stability and activity. In fact, a better understanding of the correlation between different non-aqueous environments and enzyme structure, stability and activity can contribute to identifying the most suitable reaction medium for a given biotransformation.

  3. Unpacking New Media Literacy

    Directory of Open Access Journals (Sweden)

    Der-Thanq “victor” Chen

    2011-04-01

    Full Text Available The 21st century has marked an unprecedented advancement of new media. New media has become so pervasive that it has penetrated into every aspect of our society. New media literacy plays an essential role for any citizen to participate fully in the 21st century society. Researchers have documented that literacy has evolved historically from classic literacy (reading-writing-understanding to audiovisual literacy to digital literacy or information literacy and recently to new media literacy. A review of literature on media literacy reveals that there is a lack of thorough analysis of unique characteristics of new media and its impacts upon the notion of new media literacy. The purpose of the study is to unpack new media literacy and propose a framework for a systematic investigation of new media literacy.

  4. Parenting and Digital Media.

    Science.gov (United States)

    Coyne, Sarah M; Radesky, Jenny; Collier, Kevin M; Gentile, Douglas A; Linder, Jennifer Ruh; Nathanson, Amy I; Rasmussen, Eric E; Reich, Stephanie M; Rogers, Jean

    2017-11-01

    Understanding the family dynamic surrounding media use is crucial to our understanding of media effects, policy development, and the targeting of individuals and families for interventions to benefit child health and development. The Families, Parenting, and Media Workgroup reviewed the relevant research from the past few decades. We find that child characteristics, the parent-child relationship, parental mediation practices, and parents' own use of media all can influence children's media use, their attitudes regarding media, and the effects of media on children. However, gaps remain. First, more research is needed on best practices of parental mediation for both traditional and new media. Ideally, this research will involve large-scale, longitudinal studies that manage children from infancy to adulthood. Second, we need to better understand the relationship between parent media use and child media use and specifically how media may interfere with or strengthen parent-child relationships. Finally, longitudinal research on how developmental processes and individual child characteristics influence the intersection between media and family life is needed. The majority of children's media use takes place within a wider family dynamic. An understanding of this dynamic is crucial to understanding child media use as a whole. Copyright © 2017 by the American Academy of Pediatrics.

  5. Mass Media: The Invisible Environment.

    Science.gov (United States)

    Glessing, Robert J.; White, William P.

    This anthology for students of media consists of essays and articles grouped under four topics: media forms, media content, media environments, and "the last word." Media forms deals with the nature of these kinds of media: electronic, print, film, music, and comics, graffiti, and clothing. Media content contains articles on the news, advertising,…

  6. Media Pluralism and Diversity

    DEFF Research Database (Denmark)

    In the western world, a diverse and pluralistic media landscape is deemed essential for democracy. But how universal is media pluralism as a concept underpinning media policies? To what extent do normative approaches, regulatory dimensions and monitoring systems differ throughout the world......? Adopting a truly global, theoretical and multidisciplinary perspective, Media Pluralism and Diversity advances our understanding of media pluralism across the globe. It compares metrics developed in different parts of the world to assess levels of, or threats to, media pluralism. It identifies common...

  7. Social Media Reputation

    DEFF Research Database (Denmark)

    Etter, Michael Andreas; Ravasi, Davide; Colleoni, Elanor

    motivational drivers and contextual conditions associated with the formation of narratives in traditional news media and social media influence their content, diffusion, and impact significantly. Our analysis suggests that current theories of media reputation may provide an incomplete representation......Social media enable millions of users to create and disseminate narratives about organizations that increase their public exposure and shape public perceptions. In this paper, we draw on the sociology of news production and research on computer-mediated communication to discuss how different...... of the phenomenon, and highlight theoretically relevant differences and interrelationships between reputational dynamics involving news media and social media....

  8. AMAMM - All Media Are Mixed Media

    DEFF Research Database (Denmark)

    All Media Are Mixed Media Alle medier er blandingsmedier. Alle kunstarter er kompositte. Alle sanser er sammensatte. Alle medialiteter er miksede og mangfoldige. Alle er AMAMM. Denne påstand står centralt i ord-, billed- og medie-teoretikeren W.J.T. Mitchells forfatterskab. I hosstående bog tager...

  9. Mercury absorption in aqueous hypochlorite

    International Nuclear Information System (INIS)

    Zhao, L.L.; Rochelle, G.T.

    1999-01-01

    The absorption of elemental Hg vapor into aqueous hypochlorite was measured in a stirred tank reactor at 25 and 55C. NaOCl strongly absorbs Hg even at high pH. Low pH, high Cl - and high-temperature favor mercury absorption. Aqueous free Cl 2 was the active species that reacted with mercury. However, chlorine desorption was evident at high Cl - and pH 15 M -1 s -1 at 25C and 1.4x10 17 M -1 s -1 at 55C. Gas-phase reaction was observed between Hg and Cl 2 on apparatus surfaces. Strong mercury absorption in water was also detected with Cl 2 present. Results indicate that the chlorine concentration, moisture, and surface area contribute positively to mercury removal. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  10. Aqueous systems and geothermal energy

    International Nuclear Information System (INIS)

    Anon.

    1977-01-01

    Significant unpublished results reported include: osmotic coefficients of KCl solutions vs. molality at 109 to 201 0 C; cadmium ion diffusivities in CaCl 2 hydrous melts; a x-ray diffraction study of the uranyl complex in water; solubility of amorphous silica in aqueous NaNO 3 solutions at 100 to 300 0 C; and corrosion of carbon steel by geothermal brine

  11. Heterogeneous self-assembled media for biopolymerization

    DEFF Research Database (Denmark)

    Monnard, Pierre-Alain

    2011-01-01

    Heterogeneous media, such as micro-structured aqueous environments, could offer an alternative approach to the synthesis of biopolymers with novel functions. Structured media are here defined as specialized, self-assembled structures that are formed, e.g, by amphiphiles, such as liposomes, emulsion...... polymerization, the initial elongation rates clearly depended on the complementarity of the monomers with the templating nucleobases3. However, metal-ion catalyzed reactions deliver RNA analogs with heterogeneous linkages. Moreover, the usefulness of this medium in the form of quasi-compartmentalization extends...... beyond metal-ion catalysis reactions, as we have recently demonstrated the catalytic power of a dipeptide, SerHis, for the regioselective formation of phosphodiester bonds. These results in conjonction with the synthesis of nucleobases at -78˚C, the demonstration of ribozyme activity (RNA ligase ribozyme...

  12. Catholic Media and Youth.

    Science.gov (United States)

    Nunes, Stephen A.

    1980-01-01

    Discusses the impact of media on youth and suggests some possible directions for the Catholic media, especially in the areas of textbooks, magazines, television, movies, and radio, in responding to the needs of youth. (Author/FM)

  13. Nurses and social media.

    Science.gov (United States)

    Farrelly, Rory

    Nurses' use of social media and other electronic communications has increased significantly with growing numbers of social media opportunities, platforms and applications including blogs, social networking sites, video sites and online chat rooms and forums.

  14. Media and Crime

    DEFF Research Database (Denmark)

    Agger, Gunhild; Waade, Anne Marit

    2011-01-01

    Recent developments in the relationship between media and crime are analyzed, taking both fiction and journalism in account......Recent developments in the relationship between media and crime are analyzed, taking both fiction and journalism in account...

  15. Development of contrast media

    International Nuclear Information System (INIS)

    Krause, W.

    1993-01-01

    Description of all contrast media (ionic and nonionic monomers, ionic and nonionic dimers) was presented. Chemotoxicity, osmolality and viscosity of some contrast agents were analyzed. The main adverse reactions to ionic and nonionic contrast media were described

  16. The social media revolution.

    Science.gov (United States)

    Dubose, Cheryl

    2011-01-01

    The growing popularity and use of social media tools such as Facebook, YouTube, Twitter, blogging, and wikis have led to a social media revolution. Given this widespread influence, it is important for educators, administrators, and technologists to understand the risks of using social media in the classroom and workplace. To investigate popular social media sites and their effect on radiologic technology education and business practices. A comprehensive search of literature was performed to examine social media and its applications in education, health care, and business. Social media use is on the rise, affecting all aspects of mainstream society. Leaders in the radiologic sciences should be familiar with social media and cognizant of its risks. Future studies regarding social media use in the radiologic sciences are necessary to determine its effect on the radiologic science community. ©2011 by the American Society of Radiologic Technologists.

  17. MODERN MEDIA EDUCATION MODELS

    Directory of Open Access Journals (Sweden)

    Alexander Fedorov

    2011-03-01

    Full Text Available The author supposed that media education models can be divided into the following groups:- educational-information models (the study of the theory, history, language of media culture, etc., based on the cultural, aesthetic, semiotic, socio-cultural theories of media education;- educational-ethical models (the study of moral, religions, philosophical problems relying on the ethic, religious, ideological, ecological, protectionist theories of media education;- pragmatic models (practical media technology training, based on the uses and gratifications and ‘practical’ theories of media education;- aesthetical models (aimed above all at the development of the artistic taste and enriching the skills of analysis of the best media culture examples. Relies on the aesthetical (art and cultural studies theory; - socio-cultural models (socio-cultural development of a creative personality as to the perception, imagination, visual memory, interpretation analysis, autonomic critical thinking, relying on the cultural studies, semiotic, ethic models of media education.

  18. Aqueous shunt implantation in glaucoma

    Directory of Open Access Journals (Sweden)

    Jing Wang

    2017-01-01

    Full Text Available Aqueous shunts or glaucoma drainage devices are increasingly utilized in the management of refractory glaucoma. The general design of the most commonly-used shunts is based on the principles of the Molteno implant: ie. a permanent sclerostomy (tube, a predetermined bleb area (plate and diversion of aqueous humour to the equatorial region and away from the limbal subconjunctival space. These three factors make aqueous shunts more resistant to scarring as compared to trabeculectomy. The two most commonly used shunts are the Ahmed Glaucoma Valve, which contains a flow-restrictor, and the non-valved Baervedlt Glaucoma Implant. While the valved implants have a lower tendency to hypotony and related complications, the non-valved implants with larger, more-biocompatible end plate design, achieve lower intraocular pressures with less encapsulation. Non-valved implants require additional suturing techniques to prevent early hypotony and a number of these methods will be described. Although serious shunt-related infection is rare, corneal decompensation and diplopia are small but significant risks.

  19. Asian Media Productions

    DEFF Research Database (Denmark)

    This work consists of 12 essays on different aspects of Asian media by Japanese, European, and American scholars, many of whom have themselves been involved in the production of media forms. Working in the fields of anthropology, media and cultural studies, and on the basis of hands-on research, ......, they have written a book on the social practices and cultural attitudes of people producing, reading, watching and listening to different kinds of media in Japan, China, Taiwan, Indonesia, Vietnam, Singapore and India....

  20. Advertising on social media

    OpenAIRE

    Sumit Goyal

    2013-01-01

    This communication reports the latest trends of advertising on social media. Social media advertising means to gain traffic or attention of online users through social media sites. Today, when a user thinks about buying something, he first comes to the internet, searches for that product, compares its price with other competing brands and takes a decision, which one to buy. In this write-up, author has discussed many aspects concerning advertising through social media, viz., what is social me...

  1. Procedural Media Representation

    OpenAIRE

    Henrysson, Anders

    2002-01-01

    We present a concept for using procedural techniques to represent media. Procedural methods allow us to represent digital media (2D images, 3D environments etc.) with very little information and to render it photo realistically. Since not all kind of content can be created procedurally, traditional media representations (bitmaps, polygons etc.) must be used as well. We have adopted an object-based media representation where an object can be represented either with a procedure or with its trad...

  2. Colloid transport in dual-permeability media

    Science.gov (United States)

    Leij, Feike J.; Bradford, Scott A.

    2013-07-01

    It has been widely reported that colloids can travel faster and over longer distances in natural structured porous media than in uniform structureless media used in laboratory studies. The presence of preferential pathways for colloids in the subsurface environment is of concern because of the increased risks for disease caused by microorganisms and colloid-associated contaminants. This study presents a model for colloid transport in dual-permeability media that includes reversible and irreversible retention of colloids and first-order exchange between the aqueous phases of the two regions. The model may also be used to describe transport of other reactive solutes in dual-permeability media. Analytical solutions for colloid concentrations in aqueous and solid phases were obtained using Laplace transformation and matrix decomposition. The solutions proved convenient to assess the effect of model parameters on the colloid distribution. The analytical model was used to describe effluent concentrations for a bromide tracer and 3.2- or 1-μm-colloids that were observed after transport through a composite 10-cm long porous medium made up of a cylindrical lens or core of sand and a surrounding matrix with sand of a different grain size. The tracer data were described very well and realistic estimates were obtained for the pore-water velocity in the two flow domains. An accurate description was also achieved for most colloid breakthrough curves. Dispersivity and retention parameters were typically greater for the larger 3.2-μm-colloids while both reversible and irreversible retention rates tended to be higher for the finer sands than the coarser sand. The relatively small sample size and the complex flow pattern in the composite medium made it difficult to reach definitive conclusions regarding transport parameters for colloid transport.

  3. Media Education: Sociology Surveys

    Science.gov (United States)

    Fedorov, Alexander

    2007-01-01

    In Russia as well as in foreign countries we can witness sort of the confusion of the terms of "media education" and "media literacy". There are quite a few differences in theoretical approaches to media education, to distinguishing of the most important aims, objectives, means of introduction into the teaching process, etc.…

  4. Modern Media Education Models

    Science.gov (United States)

    Fedorov, Alexander

    2011-01-01

    The author supposed that media education models can be divided into the following groups: (1) educational-information models (the study of the theory, history, language of media culture, etc.), based on the cultural, aesthetic, semiotic, socio-cultural theories of media education; (2) educational-ethical models (the study of moral, religions,…

  5. Open Media Science

    DEFF Research Database (Denmark)

    Martiny, Kristian Møller Moltke; Pedersen, David Budtz; Hansted, Alfred Birkegaard

    2016-01-01

    and extend into a fully-fledged Open Media movement engaging with new media and non-traditional formats of science communication. We discuss two cases where experiments with open media have driven new collaborations between scientists and documentarists. We use the cases to illustrate different advantages...

  6. Children's Media Policy

    Science.gov (United States)

    Jordan, Amy B.

    2008-01-01

    Amy Jordan addresses the need to balance the media industry's potentially important contributions to the healthy development of America's children against the consequences of excessive and age-inappropriate media exposure. Much of the philosophical tension regarding how much say the government should have about media content and delivery stems…

  7. Social Media Empowerment (I)

    NARCIS (Netherlands)

    A. Cox

    2011-01-01

    full text via link. Social media stellen mensen, merken en bedrijven in staat om zichzelf te versterken. Soms wordt optimaal gebruik gemaakt van Social Media Empowerment, maar soms ook wat minder. Effectief inzetten van social media. Regel 1: Start met context en motivatie

  8. Youth media lifestyles

    NARCIS (Netherlands)

    van Kruistum, Claudia; Leseman, Paul Pm; de Haan, Mariëtte

    2014-01-01

    In this article, the concept of "media lifestyles" is adopted in order to develop a comprehensive approach toward youth engagement in communication media. We explore how 503 Dutch eighth grade students with full access to new technology combine a broad range of media by focusing on their engagement

  9. Sizing Up Social Media

    Science.gov (United States)

    Pearson, Jerold

    2010-01-01

    Most people are aware of the increasing importance of social media to institutional advancement, and many colleges and universities have started investing resources in these media. The next step is to measure the impact of social media on the institution and evaluate the success of one's efforts. Every advancement leader should understand how…

  10. The Media Reader.

    Science.gov (United States)

    Valdes, Joan; Crow, Jeanne

    An anthology of readings in the media correlates chapter-by-chapter to the authors' textbook, "The Media Works." Fifteen chapters cover the study of newspapers, magazines, comics, popular music, television, movies, and advertising. The authors included represent varied perspectives on the media. The selections were chosen with the help of a…

  11. Media and child development

    NARCIS (Netherlands)

    Piotrowski, J.T.; Vossen, H.G.M.; Valkenburg, P.M.; Wright, J.D.

    2015-01-01

    Decades of research have shown that the relationship between media and childhood is not unidirectional but reciprocal. In this article, both directions of the media-child development relationship are presented. We discuss how child development predisposes children's media use and preferences by

  12. Enumeration of sugars and sugar alcohols hydroxyl groups by aqueous-based acetylation and MALDI-TOF mass spectrometry

    Science.gov (United States)

    A method is described for enumerating hydroxyl groups on analytes in aqueous media is described, and applied to some common polyalcohols (erythritol, mannitol, and xylitol) and selected carbohydrates. The analytes were derivatized in water with vinyl acetate in presence of sodium phosphate buffer. ...

  13. Notes for media reinvention

    Directory of Open Access Journals (Sweden)

    Jesús Miguel Flores-Vivar

    2009-10-01

    Full Text Available Journalism and media are going through a change of era. This change is reflected in the transformation of journalism and media-lived and that another major in 1980 that became known as mediamorphosis, by this, professionals have to learn new roles. The impact of information technology and Internet has changed the way how you present the news and, most importantly, transform the business model that has characterized media companies. This article analyzes the current situation provides some strategic guidelines to be followed by some media-and-do and studied some of the new profiles arebeginning to emerge as a result of the reinvention of journalism and the media.

  14. Prosocial effects of media.

    Science.gov (United States)

    Hogan, Marjorie J

    2012-06-01

    Parents, teachers, health care providers, and other caring adults worry about the harmful influence of media messages and images on children and teens and wonder how to recognize and encourage positive and healthy use of media. For decades, experts have commented on the power of media. Media depictions can lead to negative attitudes and behavior in some young viewers. This article discusses whether prosocial, tolerant, and cooperative attitudes and behavior can be learned and imitated by children and adolescents and whether media can nurture or stimulate creativity or actively promote health and well-being in young consumers. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Calcium isotope fractionation in liquid chromatography with benzo-18-crown-6 resin in aqueous hydrobromic acid medium

    International Nuclear Information System (INIS)

    Sato, Takuya; Oi, Takao

    2015-01-01

    Liquid chromatography operated in a breakthrough mode was employed to study calcium isotope fractionation in the aqueous hydrobromic acid medium. Highly porous silica beads, the inner pores of which were embedded with a benzo-18-crown-6 ether resin, were used as column packing material. Enrichment of heavier isotopes of calcium was observed in the frontal part of respective calcium chromatograms. The values of the isotope fractionation coefficient were on the order of 10 -3 . The observed isotope fractionation coefficient was dependent on the concentration of hydrobromic acid in the calcium feed solution; a higher HBr concentration resulted in a smaller fractionation coefficient value. The present calcium isotope effects were most probably mass-dependent, indicating that they mostly came from isotope effects based on molecular vibration. Molecular orbital calculations supported the present experimental results in a qualitative fashion. Chromatography operated in aqueous HBr media is a better system of Ca isotope separation than that operated in aqueous HCl media. (author)

  16. Comprehension of digital media

    International Nuclear Information System (INIS)

    Kim, Ju Hwan

    2008-11-01

    This book is divided four parts. The first part describes media and mark on sign and media, what is the sign?, interpretation of sign and semiotics. The second part is for production sign theory and origin of digital revolution such as the problem of origin of digital revolution, homogeneity of producing goods and sign : triple triangle model for production sign theory, triple triangle model for producing goods, triple triangle model of producing sign and triple triangle model of art works. The third parts deals with development of the media and meaning of digital revolution with four changes : invention of letter, appearance of printed media and establishment modernity, appearance electronic media and mess media and appearance of digital media. The last part mentions ontology of world wide web.

  17. The Media Mixer

    DEFF Research Database (Denmark)

    Vestergaard, Vitus; Mortensen, Christian Hviid

    2011-01-01

    content. The media content is created by the user in the museum's physical environment, but it can be mixed with material from web archives. It is the intention that the users learn about media through participatory and creative processes with media where the borders between producing, playing......We explore how remixing and content sharing can be used as a means for user participation in a digital museum age. Remix culture is seen as a culture that allows and encourages the production of derivative works; works that are based on already existing works. This cultural practice thrives...... throughout the Internet, most notably on web 2.0 sites like YouTube. The Media Museum has embraced the remix paradigm with the development of an interactive media experience centre called the Media Mixer. Here the museum users can produce, deconstruct, reconstruct and finally publish and share digital media...

  18. Radiographic contrast media

    International Nuclear Information System (INIS)

    Golman, K.; Holtz, E.; Almen, T.

    1987-01-01

    Contrast media are used in diagnostic radiology to enhance the X-ray attenuation between a body structure of interest and the surrounding tissue. A detail becomes perceptible on a roentgenogram only when its contrast exceeds a minimum value in relation to the background. Small areas of interest must have higher contrast than the background. The contrast effect depends on concentration of the contrast media with the body. A high contrast media concentration difference thus gives rise to more morphological details in the radiographs. Contrast media can be divided into negative contrast media such as air and gas which attenuate X-rays less than the body tissues, and positive contrast materials which attenuate X-rays more than the body tissues. The positive contrast media all contain either iodine (atomic number 53) or barium (atomic number 56) and can be divided into water-insoluble and water-soluble contrast media

  19. Comprehension of digital media

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ju Hwan

    2008-11-15

    This book is divided four parts. The first part describes media and mark on sign and media, what is the sign?, interpretation of sign and semiotics. The second part is for production sign theory and origin of digital revolution such as the problem of origin of digital revolution, homogeneity of producing goods and sign : triple triangle model for production sign theory, triple triangle model for producing goods, triple triangle model of producing sign and triple triangle model of art works. The third parts deals with development of the media and meaning of digital revolution with four changes : invention of letter, appearance of printed media and establishment modernity, appearance electronic media and mess media and appearance of digital media. The last part mentions ontology of world wide web.

  20. Media:Time card stack

    NARCIS (Netherlands)

    Annemarie Wennekers; Jos de Haan; Frank Huysmans

    2016-01-01

    Original title: Media:Tijd in kaart The Dutch spend a daily average of 8 hours 33 minutes using media. Men and people aged over 50 spend most time using media, at an average of 9 hours per day. Older media users prefer traditional media and devices over new media and modern devices. Young and

  1. Equilibrium studies on aqueous polyvanadate solutions

    International Nuclear Information System (INIS)

    Tytko, K.H.; Mehmke, J.

    1983-01-01

    A reaction scheme for the hydrolysis of the vanadate ion VO 4 3 - in aqueous media derived from theoretical investigations on the formation mechanisms and structures of polymetalate ions has been tested by means of the potentiometric data (z, log c/sub OH - /, C/sub V(V)/) for the polyvanadate system given by Ingri and Brito. Whereas the set of species proposed by these authors only produced an agreement factor σ/sub Z/ = 0.0091, our model realizes σ/sub Z/ = 0.0071 at a level of the random errors of σ/sub Z/ = 0.0064 and leads to a rather more well-balanced deviation diagram δZ(Z). We thus see for the first time a self-contained and detailed picture of the polyvanadate system free of contradictions: The monomeric, tetrahedral vanadate ions polymerize on protonation at first forming an unbroken sequence of chains of VO 4 tetrahedra sharing corners as far as ring closure of the chains, mainly formation of the tetrameric ring, is possible. The driving forces for polymerization are the condensation of water molecules (an entropy effect) and the formation of π-bonds in the V-O-V bridges (strengthening of the bondings), both of them reaching a maximum in rings. The smallest possible, the trimeric ring does not occur because of unfavourable (to small) angles in the V-O-V bridges; the pentameric ring is handicapped for statistical reasons (meeting of the ends of the chain, law of mass action and others). All the species occur according to their basicity as determined mainly by the charge number and by the number of the terminal oxygen atoms in unprotonated, mono- and diprotonated form (chains) or only in unprotonated form (rings). On stronger protonation, as is well known, the V 10 O 28 6 - ion and its protonated forms as well as the VO 2+ ion composed of VO 6 octahedra appear. (author)

  2. Understanding Social Media Logic

    Directory of Open Access Journals (Sweden)

    José van Dijck

    2013-08-01

    Full Text Available Over the past decade, social media platforms have penetrated deeply into the mech­anics of everyday life, affecting people's informal interactions, as well as institutional structures and professional routines. Far from being neutral platforms for everyone, social media have changed the conditions and rules of social interaction. In this article, we examine the intricate dynamic between social media platforms, mass media, users, and social institutions by calling attention to social media logic—the norms, strategies, mechanisms, and economies—underpin­ning its dynamics. This logic will be considered in light of what has been identified as mass me­dia logic, which has helped spread the media's powerful discourse outside its institutional boundaries. Theorizing social media logic, we identify four grounding principles—programmabil­ity, popularity, connectivity, and datafication—and argue that these principles become increas­ingly entangled with mass media logic. The logic of social media, rooted in these grounding principles and strategies, is gradually invading all areas of public life. Besides print news and broadcasting, it also affects law and order, social activism, politics, and so forth. Therefore, its sustaining logic and widespread dissemination deserve to be scrutinized in detail in order to better understand its impact in various domains. Concentrating on the tactics and strategies at work in social media logic, we reassess the constellation of power relationships in which social practices unfold, raising questions such as: How does social media logic modify or enhance ex­isting mass media logic? And how is this new media logic exported beyond the boundaries of (social or mass media proper? The underlying principles, tactics, and strategies may be relat­ively simple to identify, but it is much harder to map the complex connections between plat­forms that distribute this logic: users that employ them, technologies that

  3. A critical overview of non-aqueous capillary electrophoresis. Part II: separation efficiency and analysis time.

    Science.gov (United States)

    Kenndler, Ernst

    2014-03-28

    A survey of the literature on non-aqueous capillary zone electrophoresis leaves one with the impression of a prevailing notion that non-aqueous conditions are principally more favorable than conventional aqueous media. Specifically, the application of organic solvents in capillary zone electrophoresis (CZE) is believed to provide the general advantages of superior separation efficiency, higher applicable electric field strength, and shorter analysis time. These advantages, however, are often claimed without providing any experimental evidence, or based on rather uncritical comparisons of limited sets of arbitrarily selected separation results. Therefore, the performance characteristics of non-aqueous vs. aqueous CZE certainly deserve closer scrutiny. The primary intention of Part II of this review is to give a critical survey of the literature on non-aqueous capillary electrophoresis (NACE) that has emerged over the last five years. Emphasis is mainly placed on those studies that are concerned with the aspects of plate height, plate number, and the crucial mechanisms contributing to zone broadening, both in organic and aqueous conditions. To facilitate a deeper understanding, this treatment covers also the theoretical fundamentals of peak dispersion phenomena arising from wall adsorption; concentration overload (electromigration dispersion); longitudinal diffusion; and thermal gradients. Theoretically achievable plate numbers are discussed, both under limiting (at zero ionic strength) and application-relevant conditions (at finite ionic strength). In addition, the impact of the superimposed electroosmotic flow contributions to overall CZE performance is addressed, both for aqueous and non-aqueous media. It was concluded that for peak dispersion due to wall adsorption and due to concentration overload (electromigration dispersion, leading to peak triangulation) no general conjunction with the solvent can be deduced. This is in contrast to longitudinal diffusion: the

  4. Lanthanide complexation in aqueous solutions

    International Nuclear Information System (INIS)

    Choppin, G.R.

    1984-01-01

    The lanthanide elements form an extended series of cations with the same charge, slightly varying radii and useful magnetic and spectroscopic properties. Their use in technology is growing rapidly as their properties are more fully explored. The lanthanides also offer scientists valuable and often unique probes for investigating a variety of chemical and physical phenomena. This review has attempted to call attention to these latter uses without trying to provide a thorough discussion of all the relevant literature. Hopefully, awareness of the more interesting facets of present studies of lanthanide complexes in aqueous solution will spur even more advances in the use of these elements. (Auth.)

  5. Electrochemical behavior of uranyl in anhydrous polar organic media

    Energy Technology Data Exchange (ETDEWEB)

    Burn, Adam G.; Nash, Kenneth L. [Washington State Univ., Pullmann, WA (United States). Dept. of Chemistry

    2017-09-01

    Weak complexes between pentavalent and hexavalent actinyl cations have been reported to exist in acidic, non-complexing high ionic strength aqueous media. Such ''cation-cation complexes'' were first identified in the context of actinide-actinide redox reactions in acidic aqueous media relevant to solvent extraction-based separation systems, hence their characterization is of potential interest for advanced nuclear fuel reprocessing. This chemistry could be relevant to efforts to develop advanced actinide separations based on the upper oxidation states of americium, which are of current interest. In the present study, the chemical behavior of pentavalent uranyl was examined in non-aqueous, aprotic polar organic solvents (propylene carbonate and acetonitrile) to determine whether UO{sub 2}{sup +} cations generated at the reducing working electrode surface would interact with the UO{sub 2}{sup 2+} cations in the bulk phase to form cation-cation complexes in such media. In magnesium perchlorate media, the electrolyte adsorbed onto the working electrode surface and interfered with the uranyl reduction/diffusion process through an ECE (electron transfer/chemical reaction/electron transfer) mechanism. In parallel studies of uranyl redox behavior in tetrabutylammonium hexafluorophosphate solutions, an EC (electron transfer/chemical reaction) mechanism was observed in the cyclic voltammograms. Ultimately, no conclusive electrochemical evidence demonstrated uranyl cation-cation interactions in the non-aqueous, aprotic polar organic solvent solutions, though the results reported do not completely rule out the presence of UO{sub 2}{sup +}.UO{sub 2}{sup 2+} complexes.

  6. Transport in Stochastic Media

    International Nuclear Information System (INIS)

    Haran, O.; Shvarts, D.; Thieberger, R.

    1998-01-01

    Classical transport of neutral particles in a binary, scattering, stochastic media is discussed. It is assumed that the cross-sections of the constituent materials and their volume fractions are known. The inner structure of the media is stochastic, but there exist a statistical knowledge about the lump sizes, shapes and arrangement. The transmission through the composite media depends on the specific heterogeneous realization of the media. The current research focuses on the averaged transmission through an ensemble of realizations, frm which an effective cross-section for the media can be derived. The problem of one dimensional transport in stochastic media has been studied extensively [1]. In the one dimensional description of the problem, particles are transported along a line populated with alternating material segments of random lengths. The current work discusses transport in two-dimensional stochastic media. The phenomenon that is unique to the multi-dimensional description of the problem is obstacle bypassing. Obstacle bypassing tends to reduce the opacity of the media, thereby reducing its effective cross-section. The importance of this phenomenon depends on the manner in which the obstacles are arranged in the media. Results of transport simulations in multi-dimensional stochastic media are presented. Effective cross-sections derived from the simulations are compared against those obtained for the one-dimensional problem, and against those obtained from effective multi-dimensional models, which are partially based on a Markovian assumption

  7. Zingiber officinale Roscoe aqueous extract modulates ...

    African Journals Online (AJOL)

    Zingiber officinale Roscoe aqueous extract modulates Matrixmetalloproteinases and tissue inhibitors of Metalloproteinases expressions in Dengue virus-infected cells: implications for prevention of vascular permeability.

  8. Media relations after the introduction of social media

    OpenAIRE

    Mesila, Helin

    2010-01-01

    In the light of the popularity of social media on one hand, and the contradictive relationships between journalists and public relations practitioners on the other hand, the thesis studies media relations after the introduction of social media. The study focuses on media relations in Estonian public relations scenery. The research answers to the questions: - What are media relations today? - What are the functions of social media and media relations in organizational communication? ...

  9. Media education and media enlightenment as attributes of information society

    Directory of Open Access Journals (Sweden)

    Лилия Борисовна Белоглазова

    2014-12-01

    Full Text Available The article deals with the problem of the functioning of media-education and media-enlightenment in modern society. Focuses on the impact of this socio-cultural phenomenon on consciousness of members of the Information Society. Are the main characteristics of media-education and media-education and media-enlightenment. Concludes that media-education and media-enlightenment forms unscientific and anti-scientific thinking and style speech.

  10. Organizational Communication and Media

    DEFF Research Database (Denmark)

    Tække, Jesper

      The paper reflects an interest in the relation between organizational communication and media. It tries to answer the question, how we can observe the relationship between organizational communication and media. It is a work-in-progress which tries to combine organizational studies inspired...... of Niklas Luhmann (Tække & Paulsen 2008, Tække 2008a) with analysis of how organizations communicate in and about media. Using systems theory and form theory, it puts forward a theoretical framework and a strategy for analysing organisational communication in and about media. The medium aspect is inspired...... is a possible framework to draw the two disciplines together in, because it is a theory about the relation between the social and the media it is based on. First the paper sum up the Luhmann inspired theory about organizations, fleshing out how organizations are thought to communicate in and about media and how...

  11. Social media visibility

    DEFF Research Database (Denmark)

    Uldam, Julie

    2018-01-01

    of activists remains under-researched. This article examines BP’s surveillance of activists who criticise the company’s corporate social responsibility (CSR) programme as ‘greenwashing’. In this way, it goes beyond corporations’ uses of big data and instead explores how they monitor and discuss strategies......As activists move from alternative media platforms to commercial social media platforms, they face increasing challenges in protecting their online security and privacy. While government surveillance of activists is well-documented in scholarly research and the media, corporate surveillance...... for responding to the activities of individual activists in social media. It shows that while social media afford an unprecedented level of visibility for activists, it comes with the risk of being monitored by corporations. Theoretically, it draws on conceptions of visibility in social sciences and media...

  12. The Media Mixer

    DEFF Research Database (Denmark)

    Vestergaard, Vitus; Mortensen, Christian Hviid

    In recent years many museums have experimented with different approaches to involving users through digital media. We explore how remixing and content sharing can be used as a means for user participation. Remix culture is seen as a culture that allows and encourages the production of derivative...... works; works that are based on already existing works. This cultural practice thrives throughout the Internet, most notably on web2.0 sites like YouTube. The Media Museum has embraced the remix paradigm with the development of an interactive media experience centre called the Media Mixer. Here...... the museum users can produce, deconstruct, reconstruct and finally publish and share digital media content. The media content is created by the user in the museums physical environment, but it can be mixed with material from local or global archives. In that way the gap between the analogue and the digital...

  13. Abortion in the media.

    Science.gov (United States)

    Conti, Jennifer A; Cahill, Erica

    2017-12-01

    To review updates in how abortion care is depicted and analysed though various media outlets: news, television, film, and social media. A surge in recent media-related abortion research has recognized several notable and emerging themes: abortion in the news media is often inappropriately sourced and politically motivated; abortion portrayal in US film and television is frequently misrepresented; and social media has a new and significant role in abortion advocacy. The portrayal of abortion onscreen, in the news, and online through social media has a significant impact on cultural, personal, and political beliefs in the United States. This is an emerging field of research with wide spread potential impact across several arenas: medicine, policy, public health.

  14. Internal Social Media

    DEFF Research Database (Denmark)

    Madsen, Vibeke Thøis

    2018-01-01

    Internal social media is a web-based communication arena that provides all organizational members with a communication opportunity. The media has emerged in organizations since 2004, and is increasingly seen as a way of giving employees a voice in organizations which can benefit the organization...... in terms of knowledge sharing, collaboration, and employee participation and engagement. The first wave of studies of internal social media was primarily from an information-systems perspective and focused more on its adoption, its affordances, and the outcome of its introduction. The second wave...... of studies was more concerned with studying the dynamics of communication on internal social media, in order to understand coworkers as strategic communicators and how communication on internal social media can constitute the organization. With a successful introduction of internal social media, coworkers...

  15. New Media, New Citizens?

    DEFF Research Database (Denmark)

    Ohme, Jakob

    as for different age groups, the thesis shows that digital and especially social media use can be a strong driver of citizen participation. Besides looking at immediate mobilizing effects, the book sheds light on how digital media use may shape participation patterns through a long-term change in citizenship......The use of news media is regarded as a driver for citizens’ engagement with society and their political participation. But as news media use increasingly shifts to digital platforms, it is crucial to understand the interplay between a changing media environment and recent patterns of political...... participation. Against the background of citizens’ diverse possibilities for receiving political information and being politically active nowadays, the book focuses on the impact of digital media on political participation in Denmark. By examining this relationship in election- and non-election times as well...

  16. Orchestrating the Media Collage

    Science.gov (United States)

    Ohler, Jason

    2009-01-01

    Modern literacy has always meant being able to both read and write narrative in the media forms of the day, whatever they may be. Just being able to read is not sufficient. A new dimension of literacy is now in play--namely, the ability to adapt to new media forms and fit them into the overall media collage quickly and effectively. A strong case…

  17. The digital media handbook

    CERN Document Server

    Dewdney, Andrew

    2013-01-01

    The new edition of The Digital Media Handbook presents an essential guide to the historical and theoretical development of digital media, emphasising cultural continuity alongside technological change, and highlighting the emergence of new forms of communication in contemporary networked culture.Andrew Dewdney and Peter Ride present detailed critical commentary and descriptive historical accounts, as well as a series of interviews from a range of digital media practitioners, including producers, developers, curators and artists.The Digital Media Handbook highlights key concerns of today's prac

  18. Media Monopoly in Brazil.

    Science.gov (United States)

    Amaral, Roberto; Guimaraes, Cesar

    1994-01-01

    Documents the process of broadcasting media development in Brazil, the failure of new technologies to produce democratization, and the barriers to democratization erected by monopolization and "metastasis." (SR)

  19. Overview: new media.

    Science.gov (United States)

    O'Keeffe, Gwenn Schurgin

    2012-06-01

    Pediatricians care for children's growth and development from the time they are born until they become adults. In addition, pediatricians must be vigilant for external influences. Technology influences children of all ages. Seventy-five percent of teenagers own cell phones, with 25% using them for social media. Technology can lead to an increase in skills and social benefits but there is also the potential for harm such as sexting, cyberbullying, privacy issues, and Internet addiction, all of which can affect health. Pediatricians must become well versed in the new media to provide media-oriented anticipatory guidance and advice on media-related issues. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Antennas in inhomogeneous media

    CERN Document Server

    Galejs, Janis; Fock, V A; Wait, J R

    2013-01-01

    Antennas in Inhomogeneous Media details the methods of analyzing antennas in such inhomogeneous media. The title covers the complex geometrical configurations along with its variational formulations. The coverage of the text includes various conditions the antennas are subjected to, such as antennas in the interface between two media; antennas in compressible isotropic plasma; and linear antennas in a magnetoionic medium. The selection also covers insulated loops in lossy media; slot antennas with a stratified dielectric or isotropic plasma layers; and cavity-backed slot antennas. The book wil

  1. Media multitasking in adolescence.

    Science.gov (United States)

    Cain, Matthew S; Leonard, Julia A; Gabrieli, John D E; Finn, Amy S

    2016-12-01

    Media use has been on the rise in adolescents overall, and in particular, the amount of media multitasking-multiple media consumed simultaneously, such as having a text message conversation while watching TV-has been increasing. In adults, heavy media multitasking has been linked with poorer performance on a number of laboratory measures of cognition, but no relationship has yet been established between media-multitasking behavior and real-world outcomes. Examining individual differences across a group of adolescents, we found that more frequent media multitasking in daily life was associated with poorer performance on statewide standardized achievement tests of math and English in the classroom, poorer performance on behavioral measures of executive function (working memory capacity) in the laboratory, and traits of greater impulsivity and lesser growth mindset. Greater media multitasking had a relatively circumscribed set of associations, and was not related to behavioral measures of cognitive processing speed, implicit learning, or manual dexterity, or to traits of grit and conscientiousness. Thus, individual differences in adolescent media multitasking were related to specific differences in executive function and in performance on real-world academic achievement measures: More media multitasking was associated with poorer executive function ability, worse academic achievement, and a reduced growth mindset.

  2. Open Media Science

    DEFF Research Database (Denmark)

    Møller Moltke Martiny, Kristian; Pedersen, David Budtz; Hansted, Allan Alfred Birkegaard

    2016-01-01

    In this article, we present three challenges to the emerging Open Science (OS) movement: the challenge of communication, collaboration and cultivation of scientific research. We argue that to address these challenges OS needs to include other forms of data than what can be captured in a text...... and extend into a fully-fledged Open Media movement engaging with new media and non-traditional formats of science communication. We discuss two cases where experiments with open media have driven new collaborations between scientists and documentarists. We use the cases to illustrate different advantages...... of using open media to face the challenges of OS....

  3. Neutron studies of paramagnetic fullerenols’ assembly in aqueous solutions

    Science.gov (United States)

    Lebedev, V. T.; Szhogina, A. A.; Suyasova, M. V.

    2018-03-01

    Recent results on structural studies of aqueous solutions of water-soluble derivatives of endofullerenes encapsulating 4f- and 3d-elements have been presented. Neutron small angle scattering experiments allowed recognize subtle features of fullerenols assembly as dependent on chemical nature (atomic number) of interior atom, pH-factor and temperature of solutions. It was observed a fractal-type fullerenols’ ordering at the scale of correlation radii ∼ 10-20 nm when molecules with iron atoms are integrated into branched structures at low concentrations (C ≤ 1 % wt.) and organized into globular aggregates at higher amounts (C > 1 % wt.). On the other hand, for Lanthanides captured in carbon cages the supramolecular structures are mostly globular and have larger gyration radii ∼ 30 nm. They demonstrated a good stability in acidic (pH ∼ 3) and neutral (pH ∼ 7) media that is important for forthcoming medical applications.

  4. Conformation of poly(γ-glutamic acid) in aqueous solution.

    Science.gov (United States)

    Muroga, Yoshio; Nakaya, Asami; Inoue, Atsuki; Itoh, Daiki; Abiru, Masaya; Wada, Kaori; Takada, Masako; Ikake, Hiroki; Shimizu, Shigeru

    2016-04-01

    Local conformation and overall conformation of poly(γ-DL-glutamic acid) (PγDLGA) and poly(γ-L-glutamic acid) (PγLGA) in aqueous solution was studied as a function of degree of ionization ε by (1) H-NMR, circular dichroism, and potentiometric titration. It was clarified that their local conformation is represented by random coil over an entire ε range and their overall conformation is represented by expanded random-coil in a range of ε > ε(*) , where ε(*) is about 0.3, 0.35, 0.45, and 0.5 for added-salt concentration of 0.02M, 0.05M, 0.1M, and 0.2M, respectively. In a range of ε acidic media. © 2015 Wiley Periodicals, Inc.

  5. Influence of coal properties on mercury uptake from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Lakatos, J.; Brown, S.D.; Snape, C.E. [Miskolc University, Miskolc-Egyetemvaros (Hungary). Research Inst. of Applied Chemistry

    1999-10-01

    The uptake of mercury (II) from aqueous solution by a range of coals has been studied and the results have been compared to those for a number of other sorbents, including commercial active carbons and cation-exchange resins. At pH 5 in a buffer medium, the capacities for mercury removal of the low-rank coals and the oxidized bituminous coals investigated are comparable to those of the other sorbents tested. For the lignites investigated, a high content of organic sulfur does not markedly affect the capacity for mercury uptake in relatively neutral and low chloride media, owing to redox reactions being the most likely mechanism involved. However, in highly acidic solutions, the capacities for mercury uptake are considerably greater for the high-sulfur coals investigated than for their low-sulfur counterparts due to chelation being the major sorption process involved. 36 refs., 4 figs., 7 tabs.

  6. Chemical treatment of coal by grinding and aqueous caustic leaching

    Energy Technology Data Exchange (ETDEWEB)

    Balaz, P.; LaCount, R.B.; Kern, D.G.; Turcaniova, L. [Slovak Academy of Sciences, Kosice (Slovakia). Inst. of Geotechnics

    2001-04-01

    The aim of this work has been to point out the possibility of using GACL process for chemical cleaning of brown coal Nivaky (Slovakia) and Pittsburgh coal. Simultaneous grinding and aqueous chemical leaching, which is the principle of the process, reduces the inorganic and inorganic sulfur content in both coals. Dearsenificiation nearly up to 96% is detected in GACL-treated samples of Novaky coal. The possibility of enhancing the recovery of humic acid as a consequence of GACL treatment is demonstrated. The process under study works under atmospheric pressure, temperature of 90{degree}C and NaOH consumption, which is six times lower compared with the MCL process. Further research is needed to minimize the wear of grinding media and to improve the washing step. 24 refs., 7 figs., 3 tabs.

  7. 27 CFR 21.96 - Ammonia, aqueous.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Ammonia, aqueous. 21.96 Section 21.96 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT... Ammonia, aqueous. (a) Alkalinity. Strongly alkaline to litmus. (b) Ammonia content. 27 to 30 percent by...

  8. Non-aqueous pigmented inkjet inks

    NARCIS (Netherlands)

    DEROOVER, GEERT; Bernaerts, Katrien; HOOGMARTENS, IVAN

    2009-01-01

    A non-aqueous inkjet ink comprises a benzimidazolone pigment and a polymeric dispersant according to Formula (I): wherein, T represents hydrogen or a polymerization terminating group; Z represents theA non-aqueous inkjet ink comprises a benzimidazolone pigment and a polymeric dispersant according to

  9. Comparative evaluation of aqueous humor viscosity.

    Science.gov (United States)

    Davis, Kyshia; Carter, Renee; Tully, Thomas; Negulescu, Ioan; Storey, Eric

    2015-01-01

    To evaluate aqueous humor viscosity in the raptor, dog, cat, and horse, with a primary focus on the barred owl (Strix varia). Twenty-six raptors, ten dogs, three cats, and one horse. Animals were euthanized for reasons unrelated to this study. Immediately, after horizontal and vertical corneal dimensions were measured, and anterior chamber paracentesis was performed to quantify anterior chamber volume and obtain aqueous humor samples for viscosity analysis. Dynamic aqueous humor viscosity was measured using a dynamic shear rheometer (AR 1000 TA Instruments, New Castle, DE, USA) at 20 °C. Statistical analysis included descriptive statistics, unpaired t-tests, and Tukey's test to evaluate the mean ± standard deviation for corneal diameter, anterior chamber volume, and aqueous humor viscosity amongst groups and calculation of Spearman's coefficient for correlation analyses. The mean aqueous humor viscosity in the barred owl was 14.1 centipoise (cP) ± 9, cat 4.4 cP ± 0.2, and dog 2.9 cP ± 1.3. The aqueous humor viscosity for the horse was 1 cP. Of the animals evaluated in this study, the raptor aqueous humor was the most viscous. The aqueous humor of the barred owl is significantly more viscous than the dog (P humor viscosity of the raptor, dog, cat, and horse can be successfully determined using a dynamic shear rheometer. © 2014 American College of Veterinary Ophthalmologists.

  10. Soft matter at aqueous interfaces

    CERN Document Server

    Liu, Yi

    2016-01-01

    This book covers the science of interfaces between an aqueous phase and a solid, another liquid or a gaseous phase, starting from the basic physical chemistry all the way to state-of-the-art research developments. Both experimental and theoretical methods are treated thanks to the contributions of a distinguished list of authors who are all active researchers in their respective fields. The properties of these interfaces are crucial for a wide variety of processes, products and biological systems and functions, such as the formulation of personal care and food products, paints and coatings, microfluidic and lab-on-a-chip applications, cell membranes, and lung surfactants. Accordingly, research and expertise on the subject are spread over a broad range of academic disciplines and industrial laboratories. This book brings together knowledge from these different places with the aim of fostering education, collaborations and research progress.

  11. Aqueous supercapacitors on conductive cotton

    KAUST Repository

    Pasta, Mauro; La Mantia, Fabio; Hu, Liangbing; Deshazer, Heather Dawn; Cui, Yi

    2010-01-01

    Wearable electronics offer the combined advantages of both electronics and fabrics. In this article, we report the fabrication of wearable supercapacitors using cotton fabric as an essential component. Carbon nanotubes are conformally coated onto the cotton fibers, leading to a highly electrically conductive interconnecting network. The porous carbon nanotube coating functions as both active material and current collector in the supercapacitor. Aqueous lithium sulfate is used as the electrolyte in the devices, because it presents no safety concerns for human use. The supercapacitor shows high specific capacitance (~70-80 F·g-1 at 0.1 A·g-1) and cycling stability (negligible decay after 35,000 cycles). The extremely simple design and fabrication process make it applicable for providing power in practical electronic devices. © 2010 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

  12. Aqueous supercapacitors on conductive cotton

    KAUST Repository

    Pasta, Mauro

    2010-06-01

    Wearable electronics offer the combined advantages of both electronics and fabrics. In this article, we report the fabrication of wearable supercapacitors using cotton fabric as an essential component. Carbon nanotubes are conformally coated onto the cotton fibers, leading to a highly electrically conductive interconnecting network. The porous carbon nanotube coating functions as both active material and current collector in the supercapacitor. Aqueous lithium sulfate is used as the electrolyte in the devices, because it presents no safety concerns for human use. The supercapacitor shows high specific capacitance (~70-80 F·g-1 at 0.1 A·g-1) and cycling stability (negligible decay after 35,000 cycles). The extremely simple design and fabrication process make it applicable for providing power in practical electronic devices. © 2010 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

  13. Temperature-Invariant Aqueous Microgels as Hosts for Biomacromolecules.

    Science.gov (United States)

    Mastour Tehrani, Sepehr; Lu, Yijie; Guerin, Gerald; Soleimani, Mohsen; Pichugin, Dmitry; Winnik, Mitchell A

    2015-10-12

    Immobilization of enzymes on solid supports has been widely used to improve enzyme recycling, enzyme stability, and performance. We are interested in using aqueous microgels (colloidal hydrogels) as carriers for enzymes used in high-temperature reactions. These microgels should maintain their volume and colloidal stability in aqueous media up to 100 °C to serve as thermo-stable supports for enzymes. For this purpose, we prepared poly(N-hydroxyethyl acrylamide) (PHEAA) microgels via a two-step synthesis. First, we used precipitation polymerization in water to synthesize colloidal poly(diethylene glycol-ethyl ether acrylate) (PDEGAC) particles as a precursor. PDEGAC forms solvent swollen microgels in organic solvents such as methanol and dioxane and in water at temperatures below 15 °C. In the second step, these PDEGAC particles were transformed to PHEAA microgels through aminolysis in dioxane with ethanolamine and a small amount of ethylenediamine. Dynamic laser scattering studies confirmed that the colloidal stability of microgels was maintained during the aminolysis in dioxane and subsequent transfer to water. Characterization of the PHEAA microgels indicated about 9 mol % of primary amino groups. These provide functionality for bioconjugation. As proof-of-concept experiments, we attached the enzyme horseradish peroxidase (HRP) to these aqueous microgels through (i) N-(3-(dimethylamino)propyl)-N'-ethylcarbodiimide hydrochloride (EDC) coupling to the carboxylated microgels or (ii) bis-aryl hydrazone (BAH) coupling to microgels functionalized with 6-hydrazinonicotinate acetone (PHEAA-HyNic). Our results showed that HRP maintained its catalytic activity after covalent attachment (87% for EDC coupling, 96% for BAH coupling). The microgel enhanced the stability of the enzyme to thermal denaturation. For example, the residual activity of the microgel-supported enzyme was 76% after 330 min of annealing at 50 °C, compared to only 20% for the free enzyme under these

  14. Radiation crosslinking of methylcellulose and hydroxyethylcellulose in concentrated aqueous solutions

    International Nuclear Information System (INIS)

    Wach, Radoslaw A.; Mitomo, Hiroshi; Nagasawa, Naotsugu; Yoshii, Fumio

    2003-01-01

    The effects of ionizing radiation on aqueous solutions of cellulose ethers, methylcellulose (MC) and hydroxyethylcellulose (HEC) were investigated. The well-established knowledge states that cellulose and its derivatives belong to degrading type of polymers. However, in our study intermolecular crosslinking initiated by gamma rays or electron beam leaded to the formation of insoluble gel. This is an opposite effect of irradiation to the degradation. Paste-like form of the initial specimen, i.e. concentration 20-30%, when water plasticizes the bulk of polymer; and a high dose rate were favorable for hydrogel formation. Gel fraction up to 60% and 70% was obtained from solutions of HEC and MC, respectively. Produced hydrogels swell markedly in aqueous media by imbibing and holding the solvent. Radiation parameters of irradiation, such as yields of degradation and crosslinking and the gelation dose, were evaluated by sol-gel analysis on the basis of Charlesby-Rosiak equation. Despite of the crosslinked structure, obtained hydrogels can be included into the group of biodegradable materials. They undergo decomposition by the action of cellulase enzyme or microorganisms from compost

  15. Making Media Studies

    Directory of Open Access Journals (Sweden)

    David Gauntlett

    2015-12-01

    Full Text Available This podcast is a recording of a research seminar that took place on December 3, 2015, at the University of Westminster's Communication and Media Research Institute (CAMRI. In this contribution, David Gauntlett discusses his new book, Making Media Studies, and other new work. In Making Media Studies (Peter Lang, 2015, Gauntlett proposes a vision of media studies based around doing and making – not about the acquisition of skills, as such, but an experience of building knowledge and understanding through creative hands-on engagement with all kinds of media. Gauntlett suggests that media studies scholars have failed to recognise the significance of everyday creativity – the vital drive of people to make, exchange, and learn together, supported by online networks. He argues that we should think about media in terms of conversations, inspirations, and making things happen. Media studies can be about genuine social change, he suggests, if we recognise the significance of everyday creativity, work to transform our tools, and learn to use them wisely. David Gauntlett is a Professor in the School of Media, Arts and Design at the University of Westminster, where he is also the School's Co-Director of Research. He is the author of several books, including: Creative Explorations (2007, Media, Gender and Identity: An Introduction (2nd edition 2008, Making is Connecting (2011, and Making Media Studies (2015. He has made a number of popular online resources, videos and playthings, and has pioneered creative research and workshop methods. He is external examiner for Information Experience Design at the Royal College of Art, London.

  16. Educational Potential of New Media

    Directory of Open Access Journals (Sweden)

    Maria Yu. Kazak

    2017-11-01

    Full Text Available Digitalization of the mass media, which has radically changed the information environment, creates new opportunities for self-education and upgrowth of the audience. The paper defines the communicative and cultural status of new media, characterizes the socio-cultural and technological aspects of their dynamics; substantiates the necessity of elaborating mechanisms for systematization of heterogeneous information flows and elaborating criteria for their evaluation in the era of globalization of the media sphere, what implies a qualitatively different level of media competence of the audience, provided with such factors as media education, media coverage, media criticism. The definition of concepts "media competence", "media enlightenment", "media education", "media criticism" is given and their functional areas are delineated. Social networks are considered as an important tool for media enlightenment which provides significant opportunities for promoting cultural achievements in the new media environment.

  17. Metal separations using aqueous biphasic partitioning systems

    International Nuclear Information System (INIS)

    Chaiko, D.J.; Zaslavsky, B.; Rollins, A.N.; Vojta, Y.; Gartelmann, J.; Mego, W.

    1996-01-01

    Aqueous biphasic extraction (ABE) processes offer the potential for low-cost, highly selective separations. This countercurrent extraction technique involves selective partitioning of either dissolved solutes or ultrafine particulates between two immiscible aqueous phases. The extraction systems that the authors have studied are generated by combining an aqueous salt solution with an aqueous polymer solution. They have examined a wide range of applications for ABE, including the treatment of solid and liquid nuclear wastes, decontamination of soils, and processing of mineral ores. They have also conducted fundamental studies of solution microstructure using small angle neutron scattering (SANS). In this report they review the physicochemical fundamentals of aqueous biphase formation and discuss the development and scaleup of ABE processes for environmental remediation

  18. Media Anthropology: A Theoretical Framework

    Science.gov (United States)

    Eiselein, E. B.; Topper, Martin

    1976-01-01

    Media anthropology, a diverse field, has involved nearly all the major subdisciplines of anthropology and most of the major media in five different areas of interaction: the study of media, reaching the public, gathering data, teaching with media, and applied media anthropology. (NQ)

  19. Japanese Media in English.

    Science.gov (United States)

    Tanaka, Sachiko Oda

    1995-01-01

    Describes the use of English in the media in Japan, focusing on the role and history of English-language newspapers, radio, and television programs, as well as the proliferation of English-language films shown in Japanese cinemas. Discusses the implications of English in the Japanese media. (20 references) (MDM)

  20. Advertising Pressures on Media.

    Science.gov (United States)

    Hammitt, Harry

    The majority of the media in the United States is funded through revenues derived from the sale of advertising space. The problem that arises from this situation is fundamentally an economic one: if advertisers are paying the bills for the media, how much control over content should they have? This report offers a review of instances in which…