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Sample records for aqueous chemical growth

  1. Aqueous chemical growth of alpha-Fe2O3-alpha-Cr203 nanocompositethin films

    Energy Technology Data Exchange (ETDEWEB)

    Vayssieres, Lionel; Guo, Jinghua; Nordgren, Joseph

    2001-06-30

    We are reporting here on the inexpensive fabrication and optical properties of an iron(III) oxide chromium(III) oxide nanocomposite thin film of corundum crystal structure. Its novel and unique-designed architecture consists of uniformed, well-defined and oriented nanorods of Hematite (alpha-Fe2O3) of 50 nm in diameter and 500nm in length and homogeneously distributed nonaggregated monodisperse spherical nanoparticles of Eskolaite (alpha-Cr2O3) of 250 nm in diameter. This alpha-Fe2O3 alpha-Cr2O3 nanocomposite thin film is obtained by growing, directly onto transparent polycrystalline conducting substrate, an oriented layer of hematite nanorods and growing subsequently, the eskolaite layer. The synthesis is carried out by a template-free, low-temperature, multilayer thin film coating process using aqueous solution of metal salts as precursors. Almost 100 percent of the light is absorbed by the composite film between 300 and 525 nm and 40 percent at 800 nm which yields great expectations as photoanode materials for photovoltaic cells and photocatalytic devices.

  2. Chemical reactions at aqueous interfaces

    Science.gov (United States)

    Vecitis, Chad David

    2009-12-01

    Interfaces or phase boundaries are a unique chemical environment relative to individual gas, liquid, or solid phases. Interfacial reaction mechanisms and kinetics are often at variance with homogeneous chemistry due to mass transfer, molecular orientation, and catalytic effects. Aqueous interfaces are a common subject of environmental science and engineering research, and three environmentally relevant aqueous interfaces are investigated in this thesis: 1) fluorochemical sonochemistry (bubble-water), 2) aqueous aerosol ozonation (gas-water droplet), and 3) electrolytic hydrogen production and simultaneous organic oxidation (water-metal/semiconductor). Direct interfacial analysis under environmentally relevant conditions is difficult, since most surface-specific techniques require relatively `extreme' conditions. Thus, the experimental investigations here focus on the development of chemical reactors and analytical techniques for the completion of time/concentration-dependent measurements of reactants and their products. Kinetic modeling, estimations, and/or correlations were used to extract information on interfacially relevant processes. We found that interfacial chemistry was determined to be the rate-limiting step to a subsequent series of relatively fast homogeneous reactions, for example: 1) Pyrolytic cleavage of the ionic headgroup of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) adsorbed to cavitating bubble-water interfaces during sonolysis was the rate-determining step in transformation to their inorganic constituents carbon monoxide, carbon dioxide, and fluoride; 2) ozone oxidation of aqueous iodide to hypoiodous acid at the aerosol-gas interface is the rate-determining step in the oxidation of bromide and chloride to dihalogens; 3) Electrolytic oxidation of anodic titanol surface groups is rate-limiting for the overall oxidation of organics by the dichloride radical. We also found chemistry unique to the interface, for example: 1

  3. Aqueous chemical growth of alpha-Fe2O3-alpha-Cr2O3 nanocomposite thin films.

    Science.gov (United States)

    Vayssieres, L; Guo, J; Nordgren, J

    2001-12-01

    We are reporting here on the inexpensive fabrication and optical properties of an iron(III) oxide-chromium(III) oxide nanocomposite thin film of corundum crystal structure. Its novel and unique-designed architecture consists of uniformed, well-defined and oriented nanorods of Hematite (alpha-Fe2O3) of 50 nm in diameter and 500 nm in length and homogeneously distributed nonaggregated monodisperse spherical nanoparticles of Eskolaite (alpha-Cr2O3) of 250 nm in diameter. This alpha-Fe2O3-alpha-Cr2O3 nanocomposite thin film is obtained by growing, directly onto transparent polycrystalline conducting substrate, an oriented layer of hematite nanorods and growing subsequently, the eskolaite layer. The synthesis is carried out by a template-free, low-temperature, multilayer thin film coating process using aqueous solution of metal salts as precursors. Almost 100% of the light is absorbed by the composite film between 300 and 525 nm and 40% at 800 nm which yields great expectations as photoanode materials for photovoltaic cells and photocatalytic devices. PMID:12914078

  4. The Inorganic-organic Hybrid Junction with n-ZnO Nanorods/p-polyfluorene Structure Grown with Low-temperature Aqueous Chemical Growth Method

    Institute of Scientific and Technical Information of China (English)

    WU Wei; BIAN Jiming; SUN Yinglan; CHENG Chuanhui; SUN Jingchang; LLANG Hongwei; LUO Yingmin; DU Guotong

    2012-01-01

    The inorganic-organic hybrid junction was synthesized on ITO glass substrate,which was consisted of an n-type ZnO nanorods (NRs) grown by low-temperature aqueous chemical growth method and a p-type polyfluorene (PF) organic film fabricated by spin-coating.The experimental results indicate that densely and uniformly distributed ZnO nanorods are successfully grown on the PF layer.The thickness of the PF layer plays a dominant role for the current-voltage (Ⅰ-Ⅴ) characteristic of the ZnO NRs/PF inorganic-organic hybrid junction device,and a p-n junction with obviously rectifying behavior is achieved with optimal PF layer thickness.The photoluminescence (PL) spectrum coveting the broad visible range was obtained from the n-ZnO nanorods/p-polyfluorene (PF) structure,which was originated from the combination of the PF-related blue emission and the ZnO-related deep level emission.

  5. Chemical Control of Plant Growth.

    Science.gov (United States)

    Agricultural Research Center (USDA), Beltsville, MD.

    Seven experiments are presented in this Science Study Aid to help students investigate the control of plant growth with chemicals. Plant growth regulators, weed control, and chemical pruning are the topics studied in the experiments which are based on investigations that have been and are being conducted at the U. S. Agricultural Research Center,…

  6. Aqueous chemical growth of free standing vertical ZnO nanoprisms, nanorods and nanodiskettes with improved texture co-efficient and tunable size uniformity

    Energy Technology Data Exchange (ETDEWEB)

    Ram, S.D.G. [Bharath Niketan Engineering College, Department of Physics, Aundipatti (India); Ravi, G.; Mahalingam, T. [Alagappa University, Department of Physics, Karaikudi (India); Athimoolam, A. [Fatima Michael College of Engineering and Technology, Department of Physics, Madurai (India); Kulandainathan, M.A. [Central Electro Chemical Research Institute, Karaikudi (India)

    2011-12-15

    Tuning the morphology, size and aspect ratio of free standing ZnO nanostructured arrays by a simple hydrothermal method is reported. Pre-coated ZnO seed layers of two different thicknesses ({approx}350 nm or 550 nm) were used as substrates to grow ZnO nanostructures for the study. Various parameters such as chemical ambience, pH of the solution, strength of the Zn{sup 2+} atoms and thickness of seed bed are varied to analyze their effects on the resultant ZnO nanostructures. Vertically oriented hexagonal nanorods, multi-angular nanorods, hexagonal diskette and popcorn-like nanostructures are obtained by altering the experimental parameters. All the produced nanostructures were analysed by X-ray powder diffraction analysis and found to be grown in the (002) orientation of wurtzite ZnO. The texture co-efficient of ZnO layer was improved by combining a thick seed layer with higher cationic strength. Surface morphological studies reveal various nanostructures such as nanorods, diskettes and popcorn-like structures based on various preparation conditions. The optical property of the closest packed nanorods array was recorded by UV-VIS spectrometry, and the band gap value simulated from the results reflect the near characteristic band gap of ZnO. The surface roughness profile taken from the Atomic Force Microscopy reveals a roughness of less than 320 nm. (orig.)

  7. Aqueous fractionation yields chemically stable lupin protein isolates

    NARCIS (Netherlands)

    Berghout, J.A.M.; Marmolejo-Garcia, C.; Berton-Carabin, C.C.; Nikiforidis, C.V.; Boom, R.M.; Goot, van der A.J.

    2015-01-01

    The chemical stability of lupin protein isolates (LPIs) obtained through aqueous fractionation (AF, i.e. fractionation without the use of an organic solvent) at 4 °C or 20 °C was assessed. AF of lupin seeds results in LPIs containing 2 wt.% oil. This oil is composed of mono- and poly-unsaturated fat

  8. Chemical precipitation processes for the treatment of aqueous radioactive waste

    International Nuclear Information System (INIS)

    Chemical precipitation by coagulation-flocculation and sedimentation has been commonly used for many years to treat liquid (aqueous) radioactive waste. This method allows the volume of waste to be substantially reduced for further treatment or conditioning and the bulk of the waste to de discharged. Chemical precipitation is usually applied in combination with other methods as part of a comprehensive waste management scheme. As with any other technology, chemical precipitation is constantly being improved to reduce cost to increase the effectiveness and safety on the entire waste management system. The purpose of this report is to review and update the information provided in Technical Reports Series No. 89, Chemical Treatment of Radioactive Wastes, published in 1968. In this report the chemical methods currently in use for the treatment of low and intermediate level aqueous radioactive wastes are described and illustrated. Comparisons are given of the advantages and limitations of the processes, and it is noted that good decontamination and volume reduction are not the only criteria according to which a particular process should be selected. Emphasis has been placed on the need to carefully characterize each waste stream, to examine fully the effect of segregation and the importance of looking at the entire operation and not just the treatment process when planning a liquid waste treatment facility. This general approach includes local requirements and possibilities, discharge authorization, management of the concentrates, ICRP recommendations and economics. It appears that chemical precipitation process and solid-liquid separation techniques will continue to be widely used in liquid radioactive waste treatment. Current research and development is showing that combining different processes in one treatment plant can provide higher decontamination factors and smaller secondary waste arisings. Some of these processes are already being incorporated into new and

  9. The crystal growth of barium flouride in aqueous solution

    Science.gov (United States)

    Barone, J. P.; Svrjcek, D.; Nancollas, G. H.

    1983-06-01

    The kinetics of growth of barium flouride seed crystals were investigated in aqueous solution at 25°C using a constant composition method, in which the supersaturation and ionic strength were maintained constant by the addition of titrants consisting of barium nitrate and potassium flouride solutions. The rates of reaction, studied over a range of supersaturation (σ ≈ 0.4 to 1.0), were interpreted in terms of crystal growth models. A spiral growth mechanism best describes the data, and scanning electron microscopy indicates a three-dimensional growth. In the presence of inorganic additives such as phosphate, however, induction periods precede a morphological two-dimensional crystallization. Coulter Counter results show little crystal agglomeration.

  10. Controlled growth of iron oxide nanoparticles in the aqueous microdroplets.

    Science.gov (United States)

    Jeon, Bong-sik; Lee, Seung-Jun; Kim, Jong-Duk

    2008-09-01

    Magnetite nanoparticles were synthesized by chemical coprecipitation of ferric and ferrous aqueous solutions via regulation of the microenvironment at ambient conditions. Nanocrystals having an average diameter of 6 to 12 nm were obtained by picoliter droplets, whereas only 9 nm diameter nanocrystals were prepared by microliter droplets. The size of the nanocrystals was controlled by a precise balance of reactions of hydroxide ions with positive ions at the surface layer and inner layers of the droplets. The crystal structure and average size were analyzed by X-ray diffraction pattern and transmission electron microscope images. The field dependence and temperature dependence on magnetization measured by a superconducting quantum interference device demonstrate that the as-synthesized particles are superparamagnetic at room temperature and have a size-dependent magnetic property. The anisotropy constant calculated by the blocking temperature and particle size was found to decrease with increasing particle size.

  11. Surface oxide growth on platinum electrode in aqueous trifluoromethanesulfonic acid

    Science.gov (United States)

    Furuya, Yoshihisa; Mashio, Tetsuya; Ohma, Atsushi; Dale, Nilesh; Oshihara, Kenzo; Jerkiewicz, Gregory

    2014-10-01

    Platinum in the form of nanoparticles is the key and most expensive component of polymer electrolyte membrane fuel cells, while trifluoromethanesulfonic acid (CF3SO3H) is the smallest fluorinated sulfonic acid. Nafion, which acts as both electrolyte and separator in fuel cells, contains -CF2SO3H groups. Consequently, research on the electrochemical behaviour of Pt in aqueous CF3SO3H solutions creates important background knowledge that can benefit fuel cell development. In this contribution, Pt electro-oxidation is studied in 0.1 M aqueous CF3SO3H as a function of the polarization potential (Ep, 1.10 ≤ Ep ≤ 1.50 V), polarization time (tp, 100 ≤ tp ≤ 104 s), and temperature (T, 278 ≤ T ≤ 333 K). The critical thicknesses (X1), which determines the applicability of oxide growth theories, is determined and related to the oxide thickness (dox). Because X1 > dox for the entire range of Ep, tp, and T values, the formation of Pt surface oxide follows the interfacial place-exchange or the metal cation escape mechanism. The mechanism of Pt electro-oxidation is revised and expanded by taking into account possible interactions of cations, anions, and water molecules with Pt. A modified kinetic equation for the interfacial place exchange is proposed. The application of the interfacial place-exchange and metal cation escape mechanisms leads to an estimation of the Ptδ+-Oδ- surface dipole (μPtO), and the potential drop (Vox) and electric field (Eox) within the oxide. The Pt-anion interactions affect the oxidation kinetics by indirectly influencing the electric field within the double layer and the surface oxide.

  12. Linking algal growth inhibition to chemical activity

    DEFF Research Database (Denmark)

    Schmidt, Stine N.; Mayer, Philipp

    2015-01-01

    Recently, high-quality data were published on the algal growth inhibition caused by 50 non-polar narcotic compounds, of which 39 were liquid compounds with defined water solubility. In the present study, the toxicity data for these liquids were applied to challenge the chemical activity range for...

  13. Phytotoxic activity and chemical composition of aqueous volatile fractions from Eucalyptus species.

    Directory of Open Access Journals (Sweden)

    Jinbiao Zhang

    Full Text Available The essential oils from four Eucalyptus species (E. spathulata, E. salubris, E. brockwayii and E. dundasii have been previously confirmed to have stronger inhibitory effects on germination and seedling growth of silverleaf nightshade (Solanum elaeagnifolium Cav.. The aqueous volatile fractions (AVFs were the water soluble volatile fractions produced together with the essential oils (water insoluble fractions during the steam distillation process. The aim of this study was to further assess the phytotoxicity of AVFs from the four Eucalyptus species and their chemical composition. The fresh leaves of the four Eucalyptus species were used for the extraction of AVFs. The AVFs were tested for their phytotoxic effects on the perennial weed, silverleaf nightshade under laboratory conditions. The chemical compositions of the AVFs were determined by gas chromatograph-mass spectrometry (GC-MS. Our results showed that the AVFs had strong inhibition on the germination and seedling growth of silverleaf nightshade. The inhibition index increased with the increasing concentrations of AVFs. The inhibitory effects of the AVFs varied between different Eucalyptus species. The AVF from E. salubris demonstrated the highest inhibitory activity on the weed tested, with complete inhibition on germination and seedling growth at a concentration of 75%. The GC-MS analysis revealed that 1,8-cineole, isopentyl isovalerate, isomenthol, pinocarvone, trans-pinocarveol, alpha-terpineol and globulol were the main compounds in the AVFs. These results indicated that all AVFs tested had differential inhibition on the germination and seedling growth of silverleaf nightshade, which could be due to the joint effects of compounds present in the AVFs as these compounds were present in different quantities and ratio between Eucalyptus species.

  14. Allelopathic interference of aqueous extracts of chinaberry on the germination and initial growth of tomato

    Directory of Open Access Journals (Sweden)

    Lindamir Hernandez Pastorini

    2012-09-01

    Full Text Available Allelopathy effects vegetative development and is caused by chemical substances produced and released by surrounding plants. The objective of this work was to investigate the allelopathic activity of aqueous extracts of fresh and dried leaves and fruits of chinaberry (Melia azedarach L. – Meliaceae on the germination and initial growth of tomato. The extracts were prepared at concentrations of 1, 2 and 4% and analyzed for their pH and osmotic potential. The experiment consisted of four replications of 25 tomato seeds that were distributed in Petri dishes containing two sheets of germitest paper. Each plate received 2mL of an extract. The seeds were evaluated for percentage of germination (PG, germination rate (VG and germination speed index (IVG. The initial growth was assessed based on the length of the radicle, hypocotyl and leaf, and fresh and dry weight. All concentrations of the extracts exhibited inhibitory activity on germination and radicle growth, and the inhibitory effect increased as the concentration of the extract increased. Extracts from dried leaves had the greatest effects. The osmotic potential and pH of the extracts did not vary significantly compared to the control, indicating that the allelopathic effect was due to the allelochemicals in the extracts.

  15. Aqueous organic chemistry in the atmosphere: sources and chemical processing of organic aerosols.

    Science.gov (United States)

    McNeill, V Faye

    2015-02-01

    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.

  16. Commodity chemical growth to slow in 1993

    International Nuclear Information System (INIS)

    In their latest chemical outlook, DRI/McGraw-Hill economists characterize 1992 as a peak year for U.S. commodity chemical demand growth, at 4.2%, tapering off to a compound 2.2% between 1993 and 1995. Just as operating rates begin to reach higher levels in 1995, however, DRI forecasts slowing GNP growth. DRI's Ramunas J. Svarcas expects a decline in exports. Those plastics promising the rosiest consumption outlook include melamine-formaldehyde resin, up 9.9% in 1992, from 155 million lbs in 1991, and projected to grow 8.6%/year through 1995; styrene acrylonitrile resin, up 23% this year, from 58 million lbs last year, and growing 8.2%/year through 1995; and unsaturated polyester, up 11.7% this year, from 1.07 billion lbs in 1991, and increasing at 6.5%/year. Methanol is a bright spot, with consumption growing 4.7%, from 11.2 billion lbs in 1991 and 12%/year thereafter. Ortho-xylene managed an impressive 21% rebound from a depressed 1991 level of 783 million lbs, and is expected to continue its recovery at 7.7%/year

  17. Lignin solubilization and aqueous phase reforming for the production of aromatic chemicals and hydrogen

    NARCIS (Netherlands)

    Zakzeski, J.; Weckhuysen, B.M.

    2011-01-01

    The solubilization and aqueous phase reforming of lignin, including kraft, soda, and alcell lignin along with sugarcane bagasse, at low temperatures (T≤498 K) and pressures (P≤29 bar) is reported for the first time for the production of aromatic chemicals and hydrogen. Analysis of lignin model compo

  18. Chemical behaviour of plutonium in aqueous chloride solutions

    International Nuclear Information System (INIS)

    The chemical behaviour of Plutonium has been investigated in concentrated NaCl solutions in the neutral pH range. The α-radiation induced radiolysis reactions oxidize the Cl--ion to Cl2, HClO, ClO- and other species, which produce a strongly oxidizing medium. Under these conditions the Pu ions of lower oxidation states are readily oxidized to Pu(VI), which then undergo depending on the pH of the solution, various chemical reactions to produce PuO2Cln, PuO2(ClO)m or PuO2(OH)x species. In addition to primary radiolysis reactions taking place in NaCl solutions, the reactions leading to the PuO2(Cl)n and PuO2(ClO)m species have been characterized and quantified systematically by spectroscopic and thermodynamic evaluation. The redox and complexation reactions of Pu ions under varying NaCl concentration, specific α-activity and pH are discussed. (orig.)

  19. UV Spectral Analysis of the Chemical Modification and Photolysis of Acetylacetone Modified Alumina Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    Chengbin JING; Xiujian ZHAO; Haizheng TAO; Xina WANG; Aiyun LIU

    2004-01-01

    Acetylacetone was firstly introduced into the aqueous media with the presence of aluminum sec-butoxide and peptizator. It was confirmed that the UV (ultraviolet) absorption band of acetylacetone underwent 14 nm of red-shift due to the formation of the six-membered ring of the complex between alumina and acetylacetone in the aqueous solution. It was also found that the chemical modification can be dissociated by the UV irradiation with a wavelength shorter than 286 nm as a result of the excitation of π-π* transition in the complex.

  20. Heterogeneous Catalytic Conversion of Biobased Chemicals into Liquid Fuels in the Aqueous Phase.

    Science.gov (United States)

    Wu, Kejing; Wu, Yulong; Chen, Yu; Chen, Hao; Wang, Jianlong; Yang, Mingde

    2016-06-22

    Different biobased chemicals are produced during the conversion of biomass into fuels through various feasible technologies (e.g., hydrolysis, hydrothermal liquefaction, and pyrolysis). The challenge of transforming these biobased chemicals with high hydrophilicity is ascribed to the high water content of the feedstock and the inevitable formation of water. Therefore, aqueous-phase processing is an interesting technology for the heterogeneous catalytic conversion of biobased chemicals. Different reactions, such as dehydration, isomerization, aldol condensation, ketonization, and hydrogenation, are applied for the conversion of sugars, furfural/hydroxymethylfurfural, acids, phenolics, and so on over heterogeneous catalysts. The activity, stability, and reusability of the heterogeneous catalysts in water are summarized, and deactivation processes and several strategies are introduced to improve the stability of heterogeneous catalysts in the aqueous phase. PMID:27158985

  1. Chemical modification of amino acids by atmospheric-pressure cold plasma in aqueous solution

    Science.gov (United States)

    Takai, Eisuke; Kitamura, Tsuyoshi; Kuwabara, Junpei; Ikawa, Satoshi; Yoshizawa, Shunsuke; Shiraki, Kentaro; Kawasaki, Hideya; Arakawa, Ryuichi; Kitano, Katsuhisa

    2014-07-01

    Plasma medicine is an attractive new research area, but the principles of plasma modification of biomolecules in aqueous solution remain elusive. In this study, we investigated the chemical effects of atmospheric-pressure cold plasma on 20 naturally occurring amino acids in aqueous solution. High-resolution mass spectrometry revealed that chemical modifications of 14 amino acids were observed after plasma treatment: (i) hydroxylation and nitration of aromatic rings in tyrosine, phenylalanine and tryptophan; (ii) sulfonation and disulfide linkage formation of thiol groups in cysteine; (iii) sulfoxidation of methionine and (iv) amidation and ring-opening of five-membered rings in histidine and proline. A competitive reaction experiment using 20 amino acids demonstrated that sulfur-containing and aromatic amino acids were preferentially decreased by the plasma treatment. These data provide fundamental information for elucidating the mechanism of protein inactivation for biomedical plasma applications.

  2. Chemical Modification of Porous Alumina for Nanowire Templating and NEXAFS Spectroscopy of Aqueous ATP

    OpenAIRE

    Kelly, Daniel Nicholas

    2010-01-01

    Part One: Chemical Modification of Porous Alumina for Nanowire Templating: A modified sol-gel technique and subsequent polymer coating technique was used to modify the size of nanowires grown via electrodeposition in porous alumina templates. The porous alumina film is initially soaked in a water-containing solution prior to exposure to a different solution of 3-aminopropyltriethoxysilane in toluene. The amount of water in the aqueous solution correlates with the thickness of silane coating ...

  3. Growth Mechanisms of CdS Nanocrystals in Aqueous Media

    Directory of Open Access Journals (Sweden)

    Loredana Latterini

    2012-06-01

    Full Text Available CdS nanocrystals were prepared in water-in-oil microemulsions. The nanocrystal properties, absorption and luminescence spectra and size distributions, were monitored at different times after mixing the microemulsions of the two precursors to obtain information on their growth mechanism. In particular, CdS nanocrystals were prepared using water-in-heptane or water-in-nonane microemulsions. The results obtained from the investigation of nanocrystals prepared using heptane as the organic phase, confirmed that nanocrystal nucleation is fast while their growth is determined by droplet exchange content rate. Size distribution histograms obtained from the sample at early time points after mixing presented a bimodal population having average sizes of 3.0 ± 0.1 and 5.8 ± 0.1 nm, thus indicating that surface process controls the nanocrystal growth. With longer reaction times the occurrence of water droplet coalescence is likely responsible for the formation of nanocrystal agglomerates. Using a water-in-nonane microemulsion, the droplet exchange rate can be modified, thus leading to smaller CdS nanocrystals. However, the development of structural defects cannot be excluded, as evidenced by the luminescence spectra of the suspension. In general, aging of the nanocrystal in the pristine microemulsion resulted in the development of cubic semiconductor nanostructures.

  4. Correlation of 1H NMR Chemical Shift for Aqueous Solutions by Statistical Associating Fluid Theory Association Model

    Institute of Scientific and Technical Information of China (English)

    许波; 李浩然; 王从敏; 许映杰; 韩世钧

    2005-01-01

    1H NMR chemical shifts of binary aqueous mixtures of acylamide, alcohol, dimethyl sulphoxide (DMSO), and acetone are correlated by statistical associating fluid theory (SAFT) association model. The comparison between SAFT association model and Wilson equation shows that the former is better for dealing with aqueous solutions. Finally, the specialties of both models are discussed.

  5. Effect of Aqueous Extracts from Weed Species on Germination and Initial Growth in Raphanus sativus L.

    Directory of Open Access Journals (Sweden)

    Anisoara STRATU

    2015-12-01

    Full Text Available The current paper presents the results of a study on the effects of aqueous extracts from five weed species (Amaranthus retroflexus, Cirsium arvense, Convolvulus arvensis, Echinochloa crus-galii, Setaria verticillata on germination and initial growth in Raphanus sativus L. The following indicators have been analyzed: indices of germination (the germination percentage; the speed of germination; the speed of accumulated germination and the coefficient of germination rate, the length of the root and hypocotyls, the pH of aqueous extracts, the UV-Vis absorption spectra of aqueous extracts. The results of the investigations showed the following aspects: the aqueous extracts reduced the values of calculated germination indices and root growth in the first ontogenetic stages of the test species; the pH of the extracts was slightly acid to neutral. Qualitative spectrophotometric analysis indicated the possible presence of phenolic and organic compounds in the extracts. C. arvense, S. verticillata and E. crus-galii presented the most pronounced effect on germination and growth processes.

  6. Transparent conducting oxide films of group V doped titania prepared by aqueous chemical solution deposition

    Energy Technology Data Exchange (ETDEWEB)

    Elen, Ken [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Strategisch Initiatief Materialen (SIM), SoPPoM Program (Belgium); Capon, Boris [Strategisch Initiatief Materialen (SIM), SoPPoM Programm (Belgium); Coating and Contacting of Nanostructures, Ghent University, Krijgslaan 281 S1, B-9000 Ghent (Belgium); De Dobbelaere, Christopher [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Dewulf, Daan [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Peys, Nick [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw, Kapeldreef 75, B-3001 Heverlee (Belgium); Detavernier, Christophe [Coating and Contacting of Nanostructures, Ghent University, Krijgslaan 281 S1, B-9000 Ghent (Belgium); Hardy, An [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium); Van Bael, Marlies K., E-mail: marlies.vanbael@uhasselt.be [Inorganic and Physical Chemistry, Institute for Materials Research, Hasselt University, Agoralaan Building D, B-3590 Diepenbeek (Belgium); IMEC vzw division IMOMEC, Agoralaan Building D, B-3590 Diepenbeek (Belgium)

    2014-03-31

    Transparent conducting oxide (TCO) films of titania doped with vanadium (V), niobium (Nb) and tantalum (Ta) are obtained by aqueous Chemical Solution Deposition (CSD). The effect of the dopant on the crystallization and microstructure of the resulting films is examined by means of X-ray diffraction and electron microscopy. During annealing of the thin films, in-situ characterization of the crystal structure and sheet resistance is carried out. Niobium doped anatase films, obtained after annealing in forming gas, show a resistivity of 0,28 Ohm cm, which is the lowest resistivity reported for a solution deposited anatase-based TCO so far. Here, we demonstrate that aqueous CSD may provide a strategy for scalable TCO production in the future. - Highlights: • Aqueous chemical solution deposition of doped titanium dioxide • Doping delays the phase transition from anatase to rutile • Lowest resistivity after doping with niobium and annealing in Forming Gas • Transparency higher than 80% in the visible range of optical spectrum.

  7. Transparent conducting oxide films of group V doped titania prepared by aqueous chemical solution deposition

    International Nuclear Information System (INIS)

    Transparent conducting oxide (TCO) films of titania doped with vanadium (V), niobium (Nb) and tantalum (Ta) are obtained by aqueous Chemical Solution Deposition (CSD). The effect of the dopant on the crystallization and microstructure of the resulting films is examined by means of X-ray diffraction and electron microscopy. During annealing of the thin films, in-situ characterization of the crystal structure and sheet resistance is carried out. Niobium doped anatase films, obtained after annealing in forming gas, show a resistivity of 0,28 Ohm cm, which is the lowest resistivity reported for a solution deposited anatase-based TCO so far. Here, we demonstrate that aqueous CSD may provide a strategy for scalable TCO production in the future. - Highlights: • Aqueous chemical solution deposition of doped titanium dioxide • Doping delays the phase transition from anatase to rutile • Lowest resistivity after doping with niobium and annealing in Forming Gas • Transparency higher than 80% in the visible range of optical spectrum

  8. On the effect of aqueous Ca on magnesite growth - Insight into trace element inhibition of carbonate mineral precipitation

    Science.gov (United States)

    Berninger, Ulf-Niklas; Jordan, Guntram; Lindner, Michael; Reul, Alexander; Schott, Jacques; Oelkers, Eric H.

    2016-04-01

    Motivated by the strong effect of aqueous Mg on calcite growth rates, this study used hydrothermal atomic force microscopy (HAFM) and hydrothermal mixed-flow reactor (HMFR) experiments to explore the effect of aqueous Ca on magnesite growth kinetics at 100 °C and pH ∼7.7. Obtuse step velocities on (1 0 4) surfaces during magnesite growth were measured to be 4 ± 3 nm/s at fluid saturation states, equal to the ion activity quotient divided by the equilibrium constant for the magnesite hydrolysis reaction, of 86-117. These rates do not vary systematically with aqueous Ca concentration up to 3 × 10-3 mol/kg. Magnesite growth rates determined by HAFM are found to be negligibly affected by the presence of aqueous Ca at these saturation states and are largely consistent with those previously reported in aqueous Ca-free systems by Saldi et al. (2009) and Gautier et al. (2015). Similarly, magnesite growth rates measured by HMFR exhibit no systematic variation on aqueous Ca concentrations. Rates in this study, however, were extended to higher degrees of fluid supersaturation with respect to magnesite than previous studies. All measured HMFR rates can be accurately described taking account the combined effects of both the spiral growth and two dimensional nucleation/growth mechanisms. Despite the lack of a clear effect of aqueous Ca on magnesite growth rates, Raman spectroscopy confirmed the incorporation of up to 8 mol percent of Ca2+ into the growing magnesite structure.

  9. Geological pattern formation by growth and dissolution in aqueous systems

    Energy Technology Data Exchange (ETDEWEB)

    Paul Meakin

    2010-03-01

    Although many geological processes take place on time scales that are very long compared with the human experience, essentially all geological processes, fast or slow, are far from equilibrium processes. Surprisingly often, geological processes lead to the formation of quite simple and distinctive patterns, which hint at an underlying simplicity in many complex geological systems.. The ability to predict the seasons was critically important to early human society, and Halley’s prediction of the return of the comet that bears his name is still considered to be a scientific milestone. Spatial patterns have also attracted attention because of their aesthetic appeal, which depends in subtle ways on a combination of regularity and irregularity. In recent decades, rapid growth in the capabilities of digital computers has facilitated the simulation of pattern formation processes, and computer simulations have become an important tool for evaluating theoretical concepts and for scientific discovery. Computer technology in combination with other technologies such as high resolution digital cameras, scanning microprobes (atomic force microscopy AFM), confocal microscopy, and scanning tunneling microscopy (STM), for example) has facilitated the quantitative characterization of patterns over a wide range of scales and has enabled rapid advances in our ability to understand the links between large scale pattern formation and microscopic processes. The ability to quantitatively characterize patterns is important because it enables a more rigorous comparison between the predictions of computer models and real world patterns and their formation.In some cases, the idea that patterns with a high degree of regularity have simple origins appears to be justified, but in other cases, such as the formation of almost perfectly circular stone rings due to freeze-thaw cycles simple patterns appear to be the consequence of quite complex processes. In other cases, it has been shown that

  10. A review of chemical, electrochemical and biological methods for aqueous Cr(VI) reduction.

    Science.gov (United States)

    Barrera-Díaz, Carlos E; Lugo-Lugo, Violeta; Bilyeu, Bryan

    2012-07-15

    Hexavalent chromium is of particular environmental concern due to its toxicity and mobility and is challenging to remove from industrial wastewater. It is a strong oxidizing agent that is carcinogenic and mutagenic and diffuses quickly through soil and aquatic environments. It does not form insoluble compounds in aqueous solutions, so separation by precipitation is not feasible. While Cr(VI) oxyanions are very mobile and toxic in the environment, Cr(III) cations are not. Like many metal cations, Cr(III) forms insoluble precipitates. Thus, reducing Cr(VI) to Cr(III) simplifies its removal from effluent and also reduces its toxicity and mobility. In this review, we describe the environmental implications of Cr(VI) presence in aqueous solutions, the chemical species that could be present and then we describe the technologies available to efficiently reduce hexavalent chromium. PMID:22608208

  11. Highly-acidic aqueous solution as a medium for radiation chemical studies: redox chemistry of phenol

    International Nuclear Information System (INIS)

    Although the aqueous medium is a common choice for radiation induced generation of a variety of transients (radicals), typically a non-aqueous solvent (or even a frozen matrix) is employed to study a transient with a labile H+ (TrH.+), mainly to maintain low propensity of its deprotonation reaction TrH.+→Tr. + H+, that otherwise occur promptly in an aqueous type medium. However, in addition to the relative difficulty encountered in routine handling of such specific non-aqueous reaction media, low transient yield (GTrH.+) therein also restrict their use. Furthermore, any comparative study of the two species TrH.+ and Tr. remains unattainable. In this context we have probed the highly acidic aqueous solution as an alternative medium for radiation induced generation and subsequent chemical studies of acidic radical cation, TrH.+ vis-a-vis the de-protonated radical Tr.. This presentation highlights these results in three parts deals with (a) measurement of oxidizing and reducing radical yields for reactions in H2SO4 and HClO4 solutions, with highest acidity maintained at ∼14 M or Hammett acidity constant H0 - 7 in case of former and ∼10 M or H0 -5.2 in case of the latter; (b) measurement of the H-atom (the sole reducing radical) scavenging efficiency of dissolved O2 in such solution for maintaining exclusive oxidizing condition; and (c) employing these results, oxidation of phenol (C6H5OH) in such medium was probed and the reactions of its radical cation C6H5OH.+ against the phenoxyl radical C6H5O. were compared. Consequently, these studies also revealed an error in the previous measurement of the C6H5OH.+ pKa value (-2.0) which was corrected to -2.75. Details of these studies will be presented to show the efficacy of highly-acidic aqueous solutions as a regular medium for radiation chemical studies. (authors)

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

    International Nuclear Information System (INIS)

    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

  13. Biosorption of heavy metal ions from aqueous solutions by short hemp fibers: Effect of chemical composition.

    Science.gov (United States)

    Pejic, Biljana; Vukcevic, Marija; Kostic, Mirjana; Skundric, Petar

    2009-05-15

    Sorption potential of waste short hemp fibers for Pb(2+), Cd(2+) and Zn(2+) ions from aqueous media was explored. In order to assess the influence of hemp fiber chemical composition on their heavy metals sorption potential, lignin and hemicelluloses were removed selectively by chemical modification. The degree of fiber swelling and water retention value were determined in order to evaluate the change in accessibility of the cell wall components to aqueous solutions due to the fiber modification. The effects of initial ion concentration, contact time and cosorption were studied in batch sorption experiments. The obtained results show that when the content of either lignin or hemicelluloses is progressively reduced by chemical treatment, the sorption properties of hemp fibers are improved. Short hemp fibers are capable of sorbing metal ions (Pb(2+), Cd(2+) and Zn(2+)) from single as well as from ternary metal ion solutions. The maximum total uptake capacities for Pb(2+), Cd(2+) and Zn(2+) ions from single solutions are the same, i.e. 0.078mmol/g, and from ternary mixture 0.074, 0.035 and 0.035mmol/g, respectively.

  14. REMOVAL OF Pb (II FROM AQUEOUS SOLUTION WITH ORANGE SUB-PRODUCTS CHEMICALLY MODIFIED AS BIOSORBENT

    Directory of Open Access Journals (Sweden)

    João Valdir Tadioto Miranda De Souza,

    2012-02-01

    Full Text Available The effects of chemical modification of orange peel, bagasse, and a mixture of peel and bagasse for lead ion removal from aqueous medium were evaluated. The chemical modification of biomass was carried out with sodium hydroxide and citric acid to introduce carboxylate groups on the surface of the biomass. Infrared spectra confirmed the presence of carboxylate groups at 1735 cm-1. Adsorption isotherms performed by static adsorption experiments fitted very well to the linear Langmuir and Freundlich models. The experiments were carried out at pH 5 during 500 min of shaking time. Orange modified peel (O-MP presented the highest adsorption capacity (84.5 mg g-1, notably higher than other biosorbents described in the literature. The kinetic studies showed that the process obeyed a pseudo-second-order rate expression, thus indicating a strong interaction between the biosorbent and adsorbate. It was found that the chemical modifications of sorbents promoted an adsorption energetically more spontaneous, as indicated by negative values of Gibbs free energy. On the other hand, desorption studies showed low leaching of lead ions from the biosorbent, thus confirming the strong interaction of lead ions and the biosorbent. The satisfactory maximum adsorption capacity obtained and negligible cost of biosorbent makes the sub-products of orange a reliable natural material for the removal of lead ions from aqueous effluents.

  15. Determination of the antioxidant activity of limoniastrum feei aqueous extract by chemical and electrochemical methods

    OpenAIRE

    Fatah Keffous; Nasser Belboukhari; Khaled Sekkoum; Houria Djeradi; Abdelkrim Cheriti; Aboul-Enein, Hassan Y.

    2016-01-01

    The total flavonoids, total phenolics and antioxidant activity of Limoniastrum feei aqueous extract were investigated. The results show that Limoniastrum feei contain 200.28±2.75 μg of total phenolic in 1 mg of dry extract, expressed as gallic acid equivalents. The total flavonoids represent 54.77±3.21 μg/mg, expressed as quercetin equivalents. The antioxidant activity of extracts has been evaluated by chemical and electrochemical methods. In the reducing power, and total antioxidant capacity...

  16. Influence of aqueous chemistry on the chemical composition of fog water and interstitial aerosol in Fresno

    Science.gov (United States)

    Kim, Hwajin; Ge, Xinlei; Collier, Sonya; Xu, Jianzhong; Sun, Yele; Wang, Youliang; Herckes, Pierre; Zhang, Qi

    2015-04-01

    A measurement study was conducted in the Central Valley (Fresno) of California in January 2010, during which radiation fog events were frequently observed. Fog plays important roles in atmospheric chemistry by scavenging aerosol particles and trace gases and serving as a medium for various aqueous-phase reactions. Understanding the effects of fog on the microphysical and chemical processing of aerosol particles requires detailed information on their chemical composition. In this study, we characterized the chemical composition of fog water and interstitial aerosol particles to study the effects of fog processing on aerosol properties. Fog water samples were collected during the 2010 Fresno campaigns with a Caltech Active Strand Cloud water Collector (CASCC) while interstitial submicron aerosols were characterized in real time with an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) and a scanning Mobility Particle Sizer (SMPS). The fog water samples were later analyzed using the HR-ToF-AMS, ion chromatography, and a total carbon analyzer. The chemical composition and characteristics of interstitial particles during the fog events were compared to those of dissolved inorganic and organic matter in fog waters. Compared to interstitial aerosols, fog water is composed of a higher fraction of ammonium nitrate and oxygenated organics, due to aqueous formation of secondary aerosol species as well as enhanced gas-to-particle partitioning of water soluble species under water rich conditions. Sulfate is formed most efficiently in fog water although its contribution to total dissolved mass is relatively low. The HR-ToF-AMS mass spectra of organic matter in fog water (FOM) are very similar to that of oxygenated organic aerosols (OOA) derived from positive matrix factorization (PMF) of the HR-ToF-AMS spectra of ambient aerosol (r2 = 0.96), but FOM appears to contain a large fraction of acidic functional groups than OOA. FOM is also enriched of

  17. Determination of the antioxidant activity of limoniastrum feei aqueous extract by chemical and electrochemical methods

    Directory of Open Access Journals (Sweden)

    Fatah Keffous

    2016-05-01

    Full Text Available The total flavonoids, total phenolics and antioxidant activity of Limoniastrum feei aqueous extract were investigated. The results show that Limoniastrum feei contain 200.28±2.75 μg of total phenolic in 1 mg of dry extract, expressed as gallic acid equivalents. The total flavonoids represent 54.77±3.21 μg/mg, expressed as quercetin equivalents. The antioxidant activity of extracts has been evaluated by chemical and electrochemical methods. In the reducing power, and total antioxidant capacity tests, the antioxidant activity of extracts was expressed as Ascorbic acid equivalents where the aqueous extract has an equivalent capacity of 233.39±4.23 and 112.4±1.97 μg for 1 mg respectively. In DPPH• radical trapping test, the IC 50 was equal to 0.58±0.03 mg / ml. The cyclic voltammetry (CV of the extract indicates one oxidation irreversible peak at approximately 300–320 mV/ (Ag / AgCl. The superoxide scavenging assay of Limoniastrum feei aqueous extract showed an average activity of order 61.46±2.51% at 0.5mg/ml doses.

  18. Linking algal growth inhibition to chemical activity

    DEFF Research Database (Denmark)

    Schmidt, Stine N.; Mayer, Philipp

    . High-quality toxicity data are carefully selected from peer-reviewed scientific literature and QSAR databases. This presentation shows how the chemical activity concept can be used to compare and combine toxicity data across compounds and species in order to characterize toxicity – and further how...

  19. Chemical characterization and anaerobic biodegradability of hydrothermal liquefaction aqueous products from mixed-culture wastewater algae.

    Science.gov (United States)

    Tommaso, Giovana; Chen, Wan-Ting; Li, Peng; Schideman, Lance; Zhang, Yuanhui

    2015-02-01

    This study examined the chemical characteristics and the anaerobic degradability of the aqueous product from hydrothermal liquefaction (HTL-ap) from the conversion of mixed-culture algal biomass grown in a wastewater treatment system. The effects of the HTL reaction times from 0 to 1.5 h, and reaction temperatures from 260 °C to 320 °C on the anaerobic degradability of the HTL-ap were quantified using biomethane potential assays. Comparing chemical oxygen demand data for HTL-ap from different operating conditions, indicated that organic matter may partition from organic phase to aqueous phase at 320 °C. Moderate lag phase and the highest cumulative methane production were observed when HTL-ap was obtained at 320 °C. The longest lag phase and the smallest production rate were observed in the process fed with HTL-ap obtained at 300 °C. Nevertheless, after overcoming adaptation issues, this HTL-ap led to the second highest accumulated specific methane production. Acetogenesis was identified as a possible rate-limiting pathway. PMID:25455086

  20. Chemically modified biochar produced from conocarpus waste increases NO3 removal from aqueous solutions.

    Science.gov (United States)

    Usman, Adel R A; Ahmad, Mahtab; El-Mahrouky, Mohamed; Al-Omran, Abdulrasoul; Ok, Yong Sik; Sallam, Abdelazeem Sh; El-Naggar, Ahmed H; Al-Wabel, Mohammad I

    2016-04-01

    Biochar has emerged as a universal sorbent for the removal of contaminants from water and soil. However, its efficiency is lower than that of commercially available sorbents. Engineering biochar by chemical modification may improve its sorption efficiency. In this study, conocarpus green waste was chemically modified with magnesium and iron oxides and then subjected to thermal pyrolysis to produce biochar. These chemically modified biochars were tested for NO3 removal efficiency from aqueous solutions in batch sorption isothermal and kinetic experiments. The results revealed that MgO-biochar outperformed other biochars with a maximum NO3 sorption capacity of 45.36 mmol kg(-1) predicted by the Langmuir sorption model. The kinetics data were well described by the Type 1 pseudo-second-order model, indicating chemisorption as the dominating mechanism of NO3 sorption onto biochars. Greater efficiency of MgO-biochar was related to its high specific surface area (391.8 m(2) g(-1)) and formation of strong ionic complexes with NO3. At an initial pH of 2, more than 89 % NO3 removal efficiency was observed for all of the biochars. We conclude that chemical modification can alter the surface chemistry of biochar, thereby leading to enhanced sorption capacity compared with simple biochar. PMID:26100325

  1. In situ growth BaTiO3 nanocubes and their superlattice from an aqueous process

    Science.gov (United States)

    Dang, Feng; Mimura, Kenichi; Kato, Kazumi; Imai, Hiroaki; Wada, Satoshi; Haneda, Hajime; Kuwabara, Makoto

    2012-02-01

    Ordered aggregated BaTiO3 nanocubes with a narrow size distribution were obtained in an aqueous process by using bis(ammonium lactate) titanium dihydroxide (TALH) as Ti source in the presence of oleic acid and tert-butylamine. Kinetics of the formation of BaTiO3 nanocubes indicated that an in situ growth mechanism was dominant and the superlattice of nanocubes formed in situ through the growth of BaTiO3 nanoparticles in Ti-based hydrous gel. The size and morphology of nanocubes were controlled by tuning the concentration and molar ratio of surfactants. A novel growth model dependant on the structure of Ti precursor for the formation and morphology control of BaTiO3 nanocubes and their superlattice was demonstrated.Ordered aggregated BaTiO3 nanocubes with a narrow size distribution were obtained in an aqueous process by using bis(ammonium lactate) titanium dihydroxide (TALH) as Ti source in the presence of oleic acid and tert-butylamine. Kinetics of the formation of BaTiO3 nanocubes indicated that an in situ growth mechanism was dominant and the superlattice of nanocubes formed in situ through the growth of BaTiO3 nanoparticles in Ti-based hydrous gel. The size and morphology of nanocubes were controlled by tuning the concentration and molar ratio of surfactants. A novel growth model dependant on the structure of Ti precursor for the formation and morphology control of BaTiO3 nanocubes and their superlattice was demonstrated. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11594h

  2. Aqueous suspension of anise "Pimpinella anisum" protects rats against chemically induced gastric ulcers

    Institute of Scientific and Technical Information of China (English)

    Ibrahim A Al Mofleh; Abdulqader A Alhaider; Jaber S Mossa; Mohammed O Al-Soohaibani; Syed Rafatullah

    2007-01-01

    AIM:To substantiate the claims of Unani and Arabian traditional medicine practitioners on the gastroprotective potential effect of a popular spice anise,"Pimpinella anisum L." on experimentally-induced gastric ulceration and secretion in rats.METHODS:Acute gastric ulceration in rats was produced by various noxious chemicals including 80% ethanol,0.2 mol/L NaOH,25% NaCl and indomethacin.Anti-secretory studies were undertaken using pylorusligated Shay rat technique.Levels of gastric non-protein sulfhydryls(NP-SH)and wall mucus were estimated and gastric tissue was also examined histologically.Anise aqueous suspension was used in two doses(250 and 500 mg/kg body weight)in all experiments.RESULTS:Anise significantly inhibited gastric mucosal damage induced by necrotizing agents and indomethacin.The anti-ulcer effect was further confirmed histologically.In pylorus-ligated Shay rats,anise suspension significantly reduced the basal gastric acid secretion,acidity and completely inhibited the rumenal ulceration.On the other hand,the suspension significantly replenished ethanol-induced depleted levels of gastric mucosal NP-SH and gastric wall mucus concentration.CONCLUSION:Anise aqueous suspension possesses significant cytoprotective and anti-ulcer activities against experimentally-induced gastric lesions.The anti-ulcer effect of anise is possibly prostaglandin-mediated and/or through its anti-secretory and antioxidative properties.

  3. Evaluation of batch biosorption of chromium (vi) from aqueous solution by chemically modified polyalthia longifolia leaves

    International Nuclear Information System (INIS)

    Removal of toxic metals from surface water is a significant matter of concern. Biosorption is emerging as an economical and eco friendly methodology for the removal of toxic chemicals from waste water. Optimization of operating conditions has a large impact on the efficiency of this process. Simple untreated and chemically modified Polyalthia longifolia leaves were used to study biosorption of Cr (VI) from aqueous media within various experimental conditions and their efficiency of biosorption were compared. The effects of different conditions, such as contact time of solution with bio sorbent, temperature, pH, biosorbent dose and agitation speed for the removal of Cr (VI) were studied. It is found that acid treated Polyalthia longifolia leaves have greater biosorption capacity as compared to untreated and base treated leaves. Langmuir and Freundlich isotherms were also applied to evaluate maximum biosorption capacity of simple untreated and chemically modified Polyalthia longifolia leaves for Cr (VI). This research work is of great importance in regard of practical waste water treatment by biosorption. (author)

  4. Chemical characterization and bioactive properties of aqueous and organic extracts of Geranium robertianum L.

    Science.gov (United States)

    Graça, V C; Barros, Lillian; Calhelha, Ricardo C; Dias, Maria Inês; Carvalho, Ana Maria; Santos-Buelga, Celestino; Santos, P F; Ferreira, Isabel C F R

    2016-09-14

    Geranium robertianum L. has been used in folk medicine and herbalism practice for the treatment of various conditions, but the study of its bioactivity has been barely addressed. Although its phytochemical composition has received some attention, contributions to the nutritional composition are practically unknown. Herein, G. robertianum gathered in Trás-os-Montes, Northeastern Portugal, was chemically characterized regarding nutritional parameters, and the antioxidant activity and cytotoxicity against several human tumor cell lines and non-tumor porcine liver primary cells of several aqueous and organic extracts were evaluated. G. robertianum showed to be an equilibrated valuable herb, rich in carbohydrates and proteins, and poor in fat, providing sugars, tocopherols, organic and essential fatty acids. Amongst the extracts, the acetone one showed the highest total phenol and total flavonoid contents, as well as the greatest antioxidant and cytotoxic activities. This extract showed to contain hydrolysable tannins (e.g. geraniin and castalagin/vescalagin), as the main phenolic compounds. PMID:27603422

  5. Chemical Bonding in Aqueous Ferrocyanide: Experimental and Theoretical X-ray Spectroscopic Study

    CERN Document Server

    Engel, Nicholas; Suljoti, Edlira; Garcia-Diez, Raul; Lange, Kathrin M; Atak, Kaan; Golnak, Ronny; Kothe, Alexander; Dantz, Marcus; Kühn, Oliver; Aziz, Emad F

    2013-01-01

    Resonant inelastic X-ray scattering (RIXS) and X-ray absorption (XA) experiments at the iron L- and nitrogen K-edge are combined with high-level first principles restricted active space self-consistent field (RASSCF) calculations for a systematic investigation of the nature of the chemical bond in potassium ferrocyanide in aqueous solution. The atom- and site-specific RIXS excitations allow for direct observation of ligand-to-metal (Fe L-edge) and metal-to-ligand (N K-edge) charge transfer bands and thereby evidence for strong {\\sigma}-donation and {\\pi}-back-donation. The effects are identified by comparing experimental and simulated spectra related to both the unoccupied and occupied molecular orbitals in solution.

  6. Secondary organic aerosol (trans)formation through aqueous phase guaiacol photonitration: chemical characterization of the products

    Science.gov (United States)

    Grgić, Irena; Kitanovski, Zoran; Kroflič, Ana; Čusak, Alen

    2014-05-01

    One of the largest primary sources of organic aerosol in the atmosphere is biomass burning (BB) (Laskin et al. 2009); in Europe its contribution to annual mean of PM10 is between 3 and 14 % (Maenhaut et al. 2012). During the process of wood burning many different products are formed via thermal degradation of wood lignin. Hardwood burning produces mainly syringol (2,6-dimetoxyphenol) derivatives, while softwood burning exclusively guaiacol (2-methoxyphenol) and its derivatives. Taking into account physical properties of methoxyphenols only, their concentrations in atmospheric waters might be underestimated. So, their aqueous phase reactions can be an additional source of SOA, especially in regions under significant influence of wood combustion. An important class of compounds formed during physical and chemical aging of the primary BBA in the atmosphere is nitrocatechols, known as strong absorbers of UV and Vis light (Claeys et al. 2012). Very recently, methyl-nitrocatechols were proposed as suitable markers for highly oxidized secondary BBA (Iinuma et al. 2010, Kitanovski et al. 2012). In the present work, the formation of SOA through aqueous phase photooxidation and nitration of guaiacol was examined. The key objective was to chemically characterize the main low-volatility products and further to check their possible presence in the urban atmospheric aerosols. The aqueous phase reactions were performed in a thermostated reactor under simulated sunlight in the presence of H2O2 and nitrite. Guaiacol reaction products were first concentrated by solid-phase extraction (SPE) and then subjected to semi-preparative liquid chromatography.The main product compounds were fractionated and isolated as pure solids and their structure was further elucidated by using nuclear magnetic resonance spectroscopy (1H, 13C and 2D NMR) and direct infusion negative ion electro-spray ionization tandem mass spectrometry (( )ESI-MS/MS). The main photonitration products of guaiacol (4

  7. Identification of the Chemical Constituents in Aqueous Extract of Zhi-Qiao and Evaluation of Its Antidepressant Effect

    Directory of Open Access Journals (Sweden)

    Ming Wu

    2015-04-01

    Full Text Available The immature fruit of Citrus aurantium L. (Zhi-Qiao, ZQ has been used as a traditional medicine in China. Our previous study has shown that ZQ decoction may contribute to the antidepressant-like action of Chaihu-Shu-Gan-San. However, there are no reports on the chemical constituents of ZQ aqueous extract or its anti-depression effects. Firstly, this research reported the on-line identification of the chemical constituents in the aqueous extract of ZQ by coupling ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC-Q-TOF/MS. A total of 31 chemical constituents were identified in ZQ aqueous extract, including one tannic acid, five flavones, 13 flavanones, one limonoid, three coumarins, three cyclic peptides, and five polymethoxylated flavonoids. The antidepressant effect of ZQ aqueous extract was evaluated in vivo and the results indicated that the mice immobility time during the forced swimming test and the tail suspension test were significantly reduced with ZQ treatment. MTT assays showed both ZQ aqueous extract and its major constituents (naringin, hesperidin, neohesperidin, and nobiletin had neuroprotective effect on corticosterone-induced neurotoxicity in PC12 cells. The in vivo and in vitro results suggest that ZQ has an antidepressant effect.

  8. Chemical Bond Calculations of Crystal Growth of KDP and ADP

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A novel method was proposed to calculate the crystal morphology (or growth habit) on the basis of chemical bond analysis. All constituent chemical bonds were distinguished as relevant and independent bonds according to their variations during the crystallization process. By employing the current method, the influence of specific growth conditions on the crystal morphology can be considered in the structure analysis process. The ideal morphologies of both KDP (KH2PO4) and ADP (NH4H2PO4) crystals were calculated and compared with our obtained crystallites at room temperature, which validates the present calculation method very well.

  9. Nanoscale carbon materials from hydrocarbons pyrolysis: Structure, chemical behavior, utilisation for non-aqueous supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Savilov, Serguei V., E-mail: savilov@chem.msu.ru [Lomonosov Moscow State University, Chemistry Department (Russian Federation); Strokova, Natalia E.; Ivanov, Anton S.; Arkhipova, Ekaterina A. [Lomonosov Moscow State University, Chemistry Department (Russian Federation); Desyatov, Andrey V. [D. Mendeleyev University of Chemical Technology of Russia (Russian Federation); Hui, Xia [Herbert Gleiter Institute of Nanoscience, School of Materials Science and Engineering, Nanjing University of Science and Technology (China); Aldoshin, Serguei M. [Lomonosov Moscow State University, Faculty of Fundamental Physical and Chemical Engineering (Russian Federation); Lunin, Valery V. [Lomonosov Moscow State University, Chemistry Department (Russian Federation)

    2015-09-15

    Highlights: • N-doped and regular carbon nanomaterials were obtained by pyrolitic technique. • Dynamic vapor sorption of different solvents reveals smaller S{sub BET} values. • Steric hindrance and specific chemical interactions are the reasons for this. • Nitrogen doping leads to raise of capacitance and coulombic efficiency with non-aqueous N-containing electrolyte. - Abstract: This work systematically studies adsorption properties of carbon nanomaterials that are synthesized through hydrocarbons that is a powerful technique to fabricate different kinds of carbon materials, e.g., nanotubes, nanoshells, onions, including nitrogen substituted. The adsorption properties of the as-synthesized carbons are achieved by low temperature nitrogen adsorption and organic vapors sorption. Heptane, acetonitrile, water, ethanol, benzene and 1-methylimidazole, which are of great importance for development of supercapacitors, are used as substrates. It is discovered that while nitrogen adsorption reveals a high specific surface area, this parameter for most of organic compounds is rather small depending not only on the size of its molecule but also on chemical interactions for a pair adsorbent–adsorbate. The experimental values of heat of adsorption for carbon and N-substituted structures, when Coulomb cross-coupling of nitrogen atoms in adsorbent and adsorbate takes place, confirms this supposition.

  10. Physical and Chemical Transformation of Hydroxyapatite Nanoparticles in Aqueous Sol after Preparation and in vitro

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The co-precipitation method followed by ultrasound and heat treatment is a common way to prepare below 100 nm sized hydroxyapatite nanoparticles for biomedical studies and applications. The size and pH value of the obtained calcium phosphate nanoparticles in aqueous sol have a strong impact on the interactions with cells and tissue. The physical and chemical properties of material samples for in vitro and in vivo studies are often assumed to remain constant from the time after fabrication to the actual use. Only little attention is paid to eventual changes of the material over time or due to the different in vitro conditions. In this study, the physical and chemical transformation of calcium phosphate nanoparticles after preparation and in vitro was investigated. As the result showed, dispersed nano sized amorphous calcium phosphate precipitation as well as crystallized hydroxyapatite nanoparticles continue to crystallize even when kept at 4 ℃ leading to declining pH values and particle sizes.Due to the pH buffer in the medium the pH value of the cell culture remained stable after adding 20% nanoparticle sol in vitro. However, hydroxyapatite nanoparticles immediately became unstable in the presents of cell culture medium. The resulting loose agglomerations showed a size of above 500 nm.

  11. Aqueous dispersions of few-layer-thick chemically modified magnesium diboride nanosheets by ultrasonication assisted exfoliation

    Science.gov (United States)

    Das, Saroj Kumar; Bedar, Amita; Kannan, Aadithya; Jasuja, Kabeer

    2015-01-01

    The discovery of graphene has led to a rising interest in seeking quasi two-dimensional allotropes of several elements and inorganic compounds. Boron, carbon’s neighbour in the periodic table, presents a curious case in its ability to be structured as graphene. Although it cannot independently constitute a honeycomb planar structure, it forms a graphenic arrangement in association with electron-donor elements. This is exemplified in magnesium diboride (MgB2): an inorganic layered compound comprising boron honeycomb planes alternated by Mg atoms. Till date, MgB2 has been primarily researched for its superconducting properties; it hasn’t been explored for the possibility of its exfoliation. Here we show that ultrasonication of MgB2 in water results in its exfoliation to yield few-layer-thick Mg-deficient hydroxyl-functionalized nanosheets. The hydroxyl groups enable an electrostatically stabilized aqueous dispersion and create a heterogeneity leading to an excitation wavelength dependent photoluminescence. These chemically modified MgB2 nanosheets exhibit an extremely small absorption coefficient of 2.9 ml mg−1 cm−1 compared to graphene and its analogs. This ability to exfoliate MgB2 to yield nanosheets with a chemically modified lattice and properties distinct from the parent material presents a fundamentally new perspective to the science of MgB2 and forms a first foundational step towards exfoliating metal borides. PMID:26041686

  12. Chemical equilibrium of hydrogen and aqueous solutions of 1 : 1 bicarbonate and formate salts with a common cation

    NARCIS (Netherlands)

    Engel, D.C.; Versteeg, G.F.; Swaaij, W.P.M. van

    1997-01-01

    The chemical equilibrium of hydrogen and aqueous solutions of 1:1 bicarbonate and formate salts with a common cation has been investigated in an intensively stirred batch reactor: MHCO3(aq) + H2(aq) ↔ MOOCH(aq) + H2O(l) This was accomplished for the sodium (M = Na), potassium (M = K) and ammonium (M

  13. Optical techniques for nanoscale probing and chemical detection in aqueous environments

    Science.gov (United States)

    Pristinski, Denis

    substrates from aqueous solution. We have shown that the coverage density of Ag nanoparticles on the glass substrates correlates with the amount of adsorbed PAH. The SERS-active substrates were robust and stable in 0.5 M NaCl solutions, as well in extreme acidic and basic conditions. Rhodamine 6G dye (R6G) was chosen as a model molecule for SERS spectra acquisition. The glass substrates with immobilized non-aggregated Ag nanoparticles exhibited SERS enhancement and provided in situ detection sensitivity of R6G at 5 ppt level, with estimated surface coverage of 2 to 4 R6G molecules per silver particle. The results will improve the design of SERS-active photonic crystal fibers for highly sensitive chemical and biological detection.

  14. Chemical Bond Analysis of Single Crystal Growth of Magnesium Oxide

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Starting from the crystallographic structure of magnesium oxide (MgO), both the chemical bond model of solids and Pauling's third rule (polyhedral sharing rule) were employed to quantitatively analyze the chemical bonding structure of constituent atoms and single crystal growth. Our analytical results show that MgO single crystals prefer to grow along the direction and the growth rate of the {100} plane is the slowest one. Therefore, the results show that the {100} plane of MgO crystals can be the ultimate morphology face, which is in a good agreement with our previous experimental results. The study indicate that the structure analysis is an effective tool to control the single-crystal growth.

  15. Optical properties of TiO{sub 2} thin films prepared by chemical spray pyrolysis from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Ayouchi, R.; Casteleiro, C.; Schwarz, R. [Departamento de Fisica, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Barrado, J.R.; Martin, F. [Laboratorio de Materiales y Superficie (Unidad Asociada al CSIC), Departamento de Fisica Aplicada I e Departamento de Ingenieria Quimica, Universidad de Malaga, 29071 Malaga (Spain)

    2010-04-15

    Titanium dioxide (TiO{sub 2}) is known to have three different kinds of polymorphous crystalline forms: rutile, anatase, and brookite. The rutile phase is always formed at higher temperatures, while the anatase phase is formed at lower temperatures and transformed into rutile phase above 800 C. Various deposition techniques have been developed for depositing TiO{sub 2} thin films, including evaporation, sputtering, chemical vapour deposition and thermal oxidation of titanium. Among them, the Chemical Spray Pyrolysis (CSP) technique has many advantages, such as good conformal coverage, the possibility of epitaxial growth and the application to large area deposition. Also, this method is low cost and it is easy to control the deposition growth parameters. In the present work, TiO{sub 2} thin films have been deposited on p-Si(001) and fused silica substrates by Chemical Spray Pyrolysis (CSP) method from aqueous solution containing titanium (IV) isopropoxide (Ti[OCH(CH{sub 3}){sub 2}]{sub 4}). As-deposited thin films show anatase polycrystalline structure, and rutile phase formed for films annealed at 750 C. SEM images have confirmed a smooth and crack-free surface with low surface roughness. X-ray photoelectron spectroscopy (XPS) combined with 4 keV Ar{sup +} depth profiling has shown that crystallized films correspond to TiO{sub 2}. Residual carbon coming from the organic precursor solution is only detected at the surface of the film. Thin films deposited on fused silica were highly transparent (more than 85%), with an indirect optical band gap of 3,43 and 3,33 eV for as-deposited and annealed films, respectively, and refractive indexes in the range between 2.01-2.29. Spectroscopic Ellipsometry (SE) also has been used to extract optical parameters. SE data fitted to triple-layer physical model revealed the same tendency to increase refractive index in annealed films. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Optimizing cyanobacteria growth conditions in a sealed environment to enable chemical inhibition tests with volatile chemicals.

    Science.gov (United States)

    Johnson, Tylor J; Zahler, Jacob D; Baldwin, Emily L; Zhou, Ruanbao; Gibbons, William R

    2016-07-01

    Cyanobacteria are currently being engineered to photosynthetically produce next-generation biofuels and high-value chemicals. Many of these chemicals are highly toxic to cyanobacteria, thus strains with increased tolerance need to be developed. The volatility of these chemicals may necessitate that experiments be conducted in a sealed environment to maintain chemical concentrations. Therefore, carbon sources such as NaHCO3 must be used for supporting cyanobacterial growth instead of CO2 sparging. The primary goal of this study was to determine the optimal initial concentration of NaHCO3 for use in growth trials, as well as if daily supplementation of NaHCO3 would allow for increased growth. The secondary goal was to determine the most accurate method to assess growth of Anabaena sp. PCC 7120 in a sealed environment with low biomass titers and small sample volumes. An initial concentration of 0.5g/L NaHCO3 was found to be optimal for cyanobacteria growth, and fed-batch additions of NaHCO3 marginally improved growth. A separate study determined that a sealed test tube environment is necessary to maintain stable titers of volatile chemicals in solution. This study also showed that a SYTO® 9 fluorescence-based assay for cell viability was superior for monitoring filamentous cyanobacterial growth compared to absorbance, chlorophyll α (chl a) content, and biomass content due to its accuracy, small sampling size (100μL), and high throughput capabilities. Therefore, in future chemical inhibition trials, it is recommended that 0.5g/L NaHCO3 is used as the carbon source, and that culture viability is monitored via the SYTO® 9 fluorescence-based assay that requires minimum sample size. PMID:27196637

  17. Effect of aqueous extracts of Mentha arvensis (mint) and Piper betle (betel) on growth and citrinin production from toxigenic Penicillium citrinum.

    Science.gov (United States)

    Panda, Pragyanshree; Aiko, Visenuo; Mehta, Alka

    2015-06-01

    Due to growing concern of consumers about chemical residues in food products, the demand for safe and natural food is increasing greatly. The use of natural additives such as spices and herbal oil as seasoning agents for their antimicrobial activity has been extensively investigated. This paper discusses the efficacy of the aqueous extract of mint (Mentha arvensis) and betel (Piper betle) on the mycelial growth and citrinin production of Penicillium citrinum. The present investigation revealed that mint extract inhibited citrinin production up to 73 % without inhibiting the mycelium growth. The citrinin production decreased with increase in the concentration of mint extract as observed from the data obtained from High pressure liquid chromatography. The samples also showed reduced cytotoxicity on HeLa cells. On the other hand betel extract resulted in stimulatory effect on citrinin production and mycelial growth. The study showed that mint extract has the potential to be used safely for restraining citrinin contamination.

  18. Supercritical carbon dioxide extractions of agricultural chemicals from aqueous solutions; Chorinkai nisankatanso ni yoru suiyoeki karano noyaku no chushitsu

    Energy Technology Data Exchange (ETDEWEB)

    Nakai, T.; Sato, Y.; Takahashi, N.; Kato, Y. [National Inst. for Resources and Environment, Tsukuba (Japan). Advanced Water Treatment Division

    1999-12-10

    Examination was made on the supercritical carbon dioxide extraction of agricultural chemicals from aqueous solutions. In the case of the semi batch extraction blowing supercritical carbon dioxide into the aqueous solutions at a concentration of 5 mg L{sup -1}, the dependencies of the removal ratios of four kinds of agricultural chemicals on temperature and pressure were shown in different patterns depending on the agricultural chemicals. For simazin (CAT), no unusual phenomena were observed. On the other hand, isoprothiolane (IPT) exhibited unusual phenomena. That is, the removal ratios decreased, as the pressure increased above 100 kg cm{sup -2} at temperatures of 45 degree C and 50 degree C. A similar phenomenon was observed for fenitrothion (MEP) or napropamide (NPP). Complicate pattern was shown for MEP. The removal ratios at pressures of 80 kg cm{sup -2} and 90 kg cm{sup -2} had maxima at 40 degree C and 45 degree C, respectively. These phenomena were discussed in terms of equilibrium and mass transfer. It was referred to that consideration should be given to such phenomena when the extraction technique is used for analysis. The order of the easiness of the separation of agricultural chemical from aqueous solution (that was estimated by the removal ratio at temperature of 35 degree C and pressure of 100 kg cm{sup -2}) was IPT>NPP>MEP>CAT. Correlation was seen between the removal ratio and the solubility of agricultural chemical in water, and in hexane or the melting point. (author)

  19. Controlling condensation and frost growth with chemical micropatterns.

    Science.gov (United States)

    Boreyko, Jonathan B; Hansen, Ryan R; Murphy, Kevin R; Nath, Saurabh; Retterer, Scott T; Collier, C Patrick

    2016-01-01

    In-plane frost growth on chilled hydrophobic surfaces is an inter-droplet phenomenon, where frozen droplets harvest water from neighboring supercooled liquid droplets to grow ice bridges that propagate across the surface in a chain reaction. To date, no surface has been able to passively prevent the in-plane growth of ice bridges across the population of supercooled condensate. Here, we demonstrate that when the separation between adjacent nucleation sites for supercooled condensate is properly controlled with chemical micropatterns prior to freezing, inter-droplet ice bridging can be slowed and even halted entirely. Since the edge-to-edge separation between adjacent supercooled droplets decreases with growth time, deliberately triggering an early freezing event to minimize the size of nascent condensation was also necessary. These findings reveal that inter-droplet frost growth can be passively suppressed by designing surfaces to spatially control nucleation sites and by temporally controlling the onset of freezing events. PMID:26796663

  20. Controlling condensation and frost growth with chemical micropatterns

    Science.gov (United States)

    Boreyko, Jonathan B.; Hansen, Ryan R.; Murphy, Kevin R.; Nath, Saurabh; Retterer, Scott T.; Collier, C. Patrick

    2016-01-01

    In-plane frost growth on chilled hydrophobic surfaces is an inter-droplet phenomenon, where frozen droplets harvest water from neighboring supercooled liquid droplets to grow ice bridges that propagate across the surface in a chain reaction. To date, no surface has been able to passively prevent the in-plane growth of ice bridges across the population of supercooled condensate. Here, we demonstrate that when the separation between adjacent nucleation sites for supercooled condensate is properly controlled with chemical micropatterns prior to freezing, inter-droplet ice bridging can be slowed and even halted entirely. Since the edge-to-edge separation between adjacent supercooled droplets decreases with growth time, deliberately triggering an early freezing event to minimize the size of nascent condensation was also necessary. These findings reveal that inter-droplet frost growth can be passively suppressed by designing surfaces to spatially control nucleation sites and by temporally controlling the onset of freezing events. PMID:26796663

  1. Bismuth oxide aqueous colloidal nanoparticles inhibit Candida albicans growth and biofilm formation

    Directory of Open Access Journals (Sweden)

    Hernandez-Delgadillo R

    2013-04-01

    Full Text Available Rene Hernandez-Delgadillo,1 Donaji Velasco-Arias,3 Juan Jose Martinez-Sanmiguel,2 David Diaz,3 Inti Zumeta-Dube,3 Katiushka Arevalo-Niño,1 Claudio Cabral-Romero2 1Facultad de Ciencias Biológicas, Instituto de Biotecnologia, Universidad Autonoma de Nuevo Leon, UANL, Monterrey, Mexico; 2Facultad de Odontología, Universidad Autonoma de Nuevo Leon, UANL, Monterrey, México; 3Facultad de Quimica, Universidad Nacional Autonoma de Mexico, UNAM, Distrito Federal, México Abstract: Multiresistance among microorganisms to common antimicrobials has become one of the most significant concerns in modern medicine. Nanomaterials are a new alternative to successfully treat the multiresistant microorganisms. Nanostructured materials are used in many fields, including biological sciences and medicine. Recently, it was demonstrated that the bactericidal activity of zero-valent bismuth colloidal nanoparticles inhibited the growth of Streptococcus mutans; however the antimycotic potential of bismuth nanostructured derivatives has not yet been studied. The main objective of this investigation was to analyze the fungicidal activity of bismuth oxide nanoparticles against Candida albicans, and their antibiofilm capabilities. Our results showed that aqueous colloidal bismuth oxide nanoparticles displayed antimicrobial activity against C. albicans growth (reducing colony size by 85% and a complete inhibition of biofilm formation. These results are better than those obtained with chlorhexidine, nystatin, and terbinafine, the most effective oral antiseptic and commercial antifungal agents. In this work, we also compared the antimycotic activities of bulk bismuth oxide and bismuth nitrate, the precursor metallic salt. These results suggest that bismuth oxide colloidal nanoparticles could be a very interesting candidate as a fungicidal agent to be incorporated into an oral antiseptic. Additionally, we determined the minimum inhibitory concentration for the synthesized

  2. Ciprofloxacin adsorption from aqueous solution onto chemically prepared carbon from date palm leaflets

    Institute of Scientific and Technical Information of China (English)

    El-Said Ibrahim El-Shafey; Haider Al-Lawati; Asmaa Soliman Al-Sumri

    2012-01-01

    A chemically prepared carbon was synthesized from date palm leaflets via sulphuric acid carbonization at 160℃.Adsorption of ciprofloxacin (CIP) from aqueous solution was investigated in terms of time,pH,concentration,temperature and adsorbent status (wet and dry).The equilibrium time was found to be 48 hr.The adsorption rate was enhanced by raising the temperature for both adsorbents,with adsorption data fitting a pseudo second-order model well.The activation energy,Ea,was found to be 17 kJ/mol,indicating a diffusion-controlled,physical adsorption process.The maximum adsorption was found at initial pH 6.The wet adsorbent showed faster removal with higher uptake than the dry adsorbent,with increased performance as temperature increased (25-45℃ ).The equilibrium data were found to fit the Langmuir model better than the Freundlich model.The thermodynamic parameters showed that the adsorption process is spontaneous and endothermic.The adsorption mechanism is mainly related to cation exchange and hydrogen bonding.

  3. Removal of Cu(II) from aqueous solutions using chemically modified chitosan

    International Nuclear Information System (INIS)

    Chemically modified chitosan namely epichlorohydrin cross-linked xanthate chitosan (ECXCs) has been used for the removal of Cu(II) ions from aqueous medium. The influence of various operating parameters such as pH, temperature, sorbent dosage, initial concentration of Cu(II) ions and contact time on the adsorption capacity of ECXCs has been investigated. Thermodynamic parameters namely ΔGo, ΔHo and ΔSo of the Cu(II) adsorption process have been calculated. Differential anodic stripping voltammetric technique was used to determine the concentration of Cu(II) in the test solution before and after adsorption. The nature of the possible adsorbent-metal ion interactions was studied by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The studies showed that the adsorption of Cu(II) on ECXCs strongly depends on pH and temperature. The maximum adsorption capacity was observed at pH 5.0 and the adsorption capacity of ECXCs increased with increasing temperature indicating the endothermic nature of adsorption process. Langmuir and Freundlich adsorption equations were used to fit the experimental data. The adsorption process is found to follow the pseudo-second-order kinetic model. The maximum adsorption capacity was found to be 43.47 mg g-1 from the Langmuir isotherm model at 50 deg. C. During desorption studies 97-100% of adsorbed copper ion is released into solution in presence of 1N EDTA, HCl and H2SO4.

  4. Potential of plant growth promoting rhizobacteria and chemical fertilizers on soil enzymes and plant growth

    International Nuclear Information System (INIS)

    The present investigation deals with the role of Plant Growth Promoting Rhizobacteria and chemical fertilizers alone or in combination on urease, invertase and phosphatase activities of rhizospheric soil and also on general impact on growth of safflower cvv. Thori and Saif-32. The PGPR (Azospirillum brasilense and Azotobacter vinelandii) were applied at 10/sup 6/ cells/mL as seed inoculation prior to sowing. Chemical fertilizers were applied at full (Urea 60 Kg ha/sup -1/ and Diammonium phosphate (DAP) 30 Kg ha/sup -1/), half (Urea 30 Kg ha/sup -1/ and DAP 15 Kg ha/sup -1/) and quarter doses (Urea 15 Kg ha-1 and DAP 7.5 Kg ha/sup -1/) during sowing. The chemical fertilizers and PGPR enhanced urease and invertase activities of soil. Presence of PGPR in combination with quarter and half doses of chemical fertilizers further augmented their effect on soil enzymes activities. The soil phosphatase activity was greater in Azospirillum and Azotobacter in combination with half dose of chemical fertilizers. Maximum increase in leaf melondialdehyde content was recorded in full dose of chemical fertilizers whereas coinoculation treatment exhibited significant reduction in cv. Thori. Half and quarter dose of chemical fertilizers increased the shoot length of safflower whereas maximum increase in leaf protein was recorded in Azotobacter in combination with full dose of chemical fertilizers. Root length was improved by Azospirillum and Azotobacter in combination with quarter dose of chemical fertilizers. Leaf area and chlorophyll contents were significantly improved by Azotobacter in combination with half dose of chemical fertilizers. It is inferred that PGPR can supplement 50 % chemical fertilizers for better plant growth and soil health. (author)

  5. Fundamental studies of chemical vapor deposition diamond growth processes

    International Nuclear Information System (INIS)

    We are developing laser spectroscopic techniques to foster a fundamental understanding of diamond film growth by hot filament chemical vapor deposition (CVD). Several spectroscopic techniques are under investigation to identify intermediate species present in the bulk reactor volume, the thin active volume immediately above the growing film, and the actual growing surface. Such a comprehensive examination of the overall deposition process is necessary because a combination of gas phase and surface chemistry is probably operating. Resonantly enhanced multiphoton ionization (REMPI) techniques have been emphasized. A growth rector that permits through-the-substrate gas sampling for REMPI/time-of-flight mass spectroscopy has been developed. 7 refs., 2 figs

  6. In situ AFM crystal growth and dissolution study of calcite in the presence of aqueous fluoride

    Science.gov (United States)

    Vavouraki, A.; Putnis, C. V.; Putnis, A.; Koutsoukos, P. G.

    2009-04-01

    Fluoride is naturally abundant, encountered in rocks, soil and fresh and ocean water. Calcite crystals, during crystal growth may incorporate fluoride ions into their lattice (Okumura et al., 1983). In situ atomic force microscopy (AFM) has been used to study the growth and dissolution of calcite {104} surfaces in aqueous solutions in the presence of fluoride, using a fluid cell in which the supersaturated and the understaturated solutions respectively, flow over a freshly cleaved calcite crystal. For growth experiments, supersaturation index (S.I.) with respect to calcite was equal to 0.89 and the initial solution pH 10.2. The crystal growth rates were measured from the closure of the rhombohedral etch pits along the [010] direction induced by an initial dissolution step using pure water. The spreading rate of 2-dimensional nuclei was also measured along the same direction. In the presence of low fluoride concentrations (≤0.33 mM), the crystal growth rate of calcite was unaffected. At higher concentrations (up to 5 mM) growth rate decreased substantially to 50% of the rate in the absence of fluoride. Potential fluoride sorption over the calcite surface may ascribe the decrease of growth rates. Dissolution experiments were conducted at pH= 7.2 and dissolution rates of calcite were measured from the spreading of rhombohedral etch pits along both [010] and [42] directions. The presence of low concentrations of fluoride (≤1.1 mM) in the undersaturated solutions enhanced the dissolution rate along the [42] direction by 50% in comparison with pure water. The morphology of rhombohedral etch pits changed to hexagonal in the presence of fluoride in the undersaturated solutions. The AFM dissolution experiments suggested that the fluoride ions adsorbed onto the calcite surface. Further increase of fluoride concentrations (up to 1.6 mM) resulted in the decrease of the calcite dissolution rate by 60% in both [010] and [42] directions. Reference: Okumura, M, Kitano, Y

  7. Graphene growth from reduced graphene oxide by chemical vapour deposition: seeded growth accompanied by restoration

    OpenAIRE

    Sung-Jin Chang; Moon Seop Hyun; Sung Myung; Min-A Kang; Jung Ho Yoo; Lee, Kyoung G.; Bong Gill Choi; Youngji Cho; Gaehang Lee; Tae Jung Park

    2016-01-01

    Understanding the underlying mechanisms involved in graphene growth via chemical vapour deposition (CVD) is critical for precise control of the characteristics of graphene. Despite much effort, the actual processes behind graphene synthesis still remain to be elucidated in a large number of aspects. Herein, we report the evolution of graphene properties during in-plane growth of graphene from reduced graphene oxide (RGO) on copper (Cu) via methane CVD. While graphene is laterally grown from R...

  8. Activation of Cassava Stem Biochar by Physico-Chemical Method for Stimulating Cadmium Removal Efficiency from Aqueous Solution

    OpenAIRE

    Songkrit Prapagdee; Somkiat Piyatiratitivorakul; Amorn Petsom

    2014-01-01

    Removal of Cadmium (Cd) from aqueous solution using biochar was considered a cost effective sorbent. Biochar quality and specification depend on its carbonization processes. In this study, the cassava stem biochars were produced at temperature of 300, 400 and 500 °C with slow pyrolysis technique. The biochar in each carbonization temperature was activated with physico-chemical treatments, pre-activated by 1.63M KOH solution then activated with second pyrolysis as same as first pyrolysis condi...

  9. chemical studies on the extraction of certain metal ions from aqueous solution by liquid emulsion membrane

    International Nuclear Information System (INIS)

    In this thesis four systems are addressed related to the use of liquid emulsion membranes (ELM) based on Co(III)dicarbiolide and. The system was dedicated for permeation of cadmium , cobalt Nickel and lead for use of this system for preconcentration and separation of cadmium, cobalt, nickel and lead. The work carried out in this thesis is presented in three parts, namely; introduction, experimental and results and discussion.The first chapter is the introduction which includes aim of work, basic concepts of liquid membranes; liquid emulsion membranes; different models of emulsion permeation, literature survey of extraction chemistry of cadmium, cobalt, nickel and lead. Chapter two includes the experimental part. In this part detailed outlines on the chemicals and different elements used were given. Different instruments as well as analytical techniques were outlines. The preparation of liquid emulsion membrane and the permeation techniques were presented in details. The third chapter deals with the results and discussion. This chapter is divided into four main parts, the four parts is concerned with cadmium/Co(III) dicarbolide/NTA, EDTA, DPTA and DCTA systems. In this part the permeation of Cd(II) aqueous solution by the membrane used was experimented based on liquid-liquid extraction studies of cadmium from different sodium chloride molarities (from 0.01 to 0.1 M) by 0.01 M Cobalt(III) dicarbolides. It was found that the extraction of with cadmium is higher following in the first system, the permeation of the toxic elements, Cd(II) from HCl/sodium chloride medium was carried out using liquid emulsion membrane containing Co(III)dicarbiolide in xylene as carrier, Spain 80/ Spain 85(1:3) as surfactant and NTA, EDTA, DPTA and DCTA as a stripping solutions.

  10. Effect of 20 % EDTA Aqueous Solution on Defective Tubes (Alloy600) in High Temperature Chemical Cleaning Environments

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Hyuk Chul [KHNP-CRI, Daejeon (Korea, Republic of)

    2016-04-15

    The transport and deposition of corrosion products in pressurized water nuclear reactor (PWR) steam generators have led to corrosion (SCC, denting etc.) problems. Lancing, mechanical cleaning and chemical cleaning have been used to reduce these problems. The methods of lancing and mechanical cleaning have limitations in removing corrosion products due to the structure of steam generator tubes. But high temperature chemical cleaning (HTCC) with EDTA is the most effective method to remove corrosion products regardless of the structure. However, EDTA in chemical cleaning aqueous solution and chemical cleaning environments affects the integrity of materials used in steam generators. The nuclear power plants have to perform the pre-test (also called as qualification test (QT)) that confirms the effect on the integrity of materials after HTCC. This is one of the series studies that assess the effect, and this study determines the effects of 20 % EDTA aqueous solution on defective tubes in high temperature chemical cleaning environments. The depth and magnitude of defects in steam generator (SG) tubes were measured by eddy current test (ECT) signals. Surface analysis and magnitude of defects were performed by using SEM/EDS. Corrosion rate was assessed by weight loss of specimens. The ECT signals (potential and depth %) of defective tubes increased marginally. But the lengths of defects, oxides on the surface and weights of specimens did not change. The average corrosion rate of standard corrosion specimens was negligible. But the surfaces on specimens showed traces of etching. The depth of etching showed a range on the nanometer. After comprehensive evaluation of all the results, it is concluded that 20 % EDTA aqueous solution in high temperature chemical cleaning environments does not have a negative effect on defective tubes.

  11. Chemical effects associated to (n, γ) nuclear reactions in diluted aqueous solutions of liquid or frozen organic halogenides

    International Nuclear Information System (INIS)

    Chemical effects associated to nuclear transformation 37Cl (n, γ) 38Cl or 127I (n, γ) 128I in solid or liquid aqueous solutions of ethyl iodide, trichloro-ethylene, thyroxine or DDT irradiated in a nuclear reactor are studied. The retention of radiohalogen under its initial chemical shape decrease with solute concentration in liquid phase but is almost constant with solute dilution in the solid phase. Potential applications in neutron activation analysis evidencing halogenated molecules in irradiated media are discussed. 57 refs

  12. Growth of fluorescence gold clusters using photo-chemically activated ligands

    Science.gov (United States)

    Mishra, Dinesh; Aldeek, Fadi; Michael, Serge; Palui, Goutam; Mattoussi, Hedi

    2016-03-01

    Ligands made of lipoic acid (LA) appended with a polyethylene glycol (PEG) chain have been used in the aqueous phase growth of luminescent gold clusters with distinct emission from yellow to near-IR, using two different routes. In the first route, the gold-ligand complex was chemically reduced using sodium borohydride in alkaline medium, which gave near- IR luminescent gold clusters with maximum emission around 745 nm. In the second method, LA-PEG ligand was photochemically modified to a mixture of thiols, oligomers and oxygenated species under UV-irradiation, which was then used as both reducing agent and stabilizing ligand. By adjusting the pH, temperature, and time of the reaction, we were able to obtain clusters with two distinct emission properties. Refluxing the gold-ligand complex in alkaline medium in the presence of excess ligand gave yellow emission within the first two hours and the emission shifted to red after overnight reaction. Mass spectrometry and chemical assay were used to understand the photo-chemical transformation of Lipoic Acid (LA). Mass spectroscopic studies showed the photo-irradiated product contains thiols, oligomers (dimers, trimers and tetramers) as well as oxygenated species. The amount of thiol formed under different conditions of irradiation was estimated using Ellman's assay.

  13. Exploring Atmospheric Aqueous Chemistry (and Secondary Organic Aerosol Formation) through OH Radical Oxidation Experiments, Droplet Evaporation and Chemical Modeling

    Science.gov (United States)

    Turpin, B. J.; Kirkland, J. R.; Lim, Y. B.; Ortiz-Montalvo, D. L.; Sullivan, A.; Häkkinen, S.; Schwier, A. N.; Tan, Y.; McNeill, V. F.; Collett, J. L.; Skog, K.; Keutsch, F. N.; Sareen, N.; Carlton, A. G.; Decesari, S.; Facchini, C.

    2013-12-01

    Gas phase photochemistry fragments and oxidizes organic emissions, making water-soluble organics ubiquitous in the atmosphere. My group and others have found that several water-soluble compounds react further in the aqueous phase forming low volatility products under atmospherically-relevant conditions (i.e., in clouds, fogs and wet aerosols). Thus, secondary organic aerosol can form as a result of gas followed by aqueous chemistry (aqSOA). We have used aqueous OH radical oxidation experiments coupled with product analysis and chemical modeling to validate and refine the aqueous chemistry of glyoxal, methylglyoxal, glycolaldehyde, and acetic acid. The resulting chemical model has provided insights into the differences between oxidation chemistry in clouds and in wet aerosols. Further, we conducted droplet evaporation experiments to characterize the volatility of the products. Most recently, we have conducted aqueous OH radical oxidation experiments with ambient mixtures of water-soluble gases to identify additional atmospherically-important precursors and products. Specifically, we scrubbed water-soluble gases from the ambient air in the Po Valley, Italy using four mist chambers in parallel, operating at 25-30 L min-1. Aqueous OH radical oxidation experiments and control experiments were conducted with these mixtures (total organic carbon ≈ 100 μM-C). OH radicals (3.5E-2 μM [OH] s-1) were generated by photolyzing H2O2. Precursors and products were characterized using electrospray ionization mass spectrometry (ESI-MS), ion chromatography (IC), IC-ESI-MS, and ultra high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Chemical modeling suggests that organic acids (e.g., oxalate, pyruvate, glycolate) are major products of OH radical oxidation at cloud-relevant concentrations, whereas organic radical - radical reactions result in the formation of oligomers in wet aerosols. Products of cloud chemistry and droplet evaporation have

  14. Orange pectin mediated growth and stability of aqueous gold and silver nanocolloids

    Science.gov (United States)

    Nigoghossian, Karina; dos Santos, Molíria V.; Barud, Hernane S.; da Silva, Robson R.; Rocha, Lucas A.; Caiut, José M. A.; de Assunção, Rosana M. N.; Spanhel, Lubomir; Poulain, Marcel; Messaddeq, Younes; Ribeiro, Sidney J. L.

    2015-06-01

    The role of orange based pectin in the nucleation and growth of silver and gold nanoparticles is addressed. Pectin is a complex polysaccharide found in fruits such as oranges, lemons, passion fruits or apples. It displays smooth and hairy chain regions containing hydroxyl-, ester-, carboxylate- and eventually amine groups that can act as surface ligands interacting under various pH conditions more or less efficiently with growing nanometals. Here, a high methoxy pectin (>50% esterified) was used as a stabilizer/reducing agent in the preparation of gold, silver and silver-gold nanoparticles. Commercial pectin (CP) and pectin extracted from orange bagasse (OP) were used. Optionally, trisodium citrate or oxalic acid we used to reduce AgNO3 and HAuCl4 in aqueous environment. Characterization methods included UV-vis absorption spectroscopy, transmission electron microscopy, electron diffraction and energy-dispersive X-ray spectroscopy. The results show that under different pH conditions, pectin and reducing agents allow producing various nanostructures shapes (triangles, spheres, rods, octahedrons and decahedrons) often with high polydispersity and sizes ranging between 5 nm and 30 nm. In addition, depending on Ag/Au-ratio and pH, the surface plasmon bands can be continuously shifted between 410 nm and 600 nm. Finally, pectin seems to be a highly efficient stabilizer of the colloidal systems that show a remarkable stability and unchanged optical spectral response even after five years.

  15. GROWTH PERFORMANCE OF COBB BROILERS GIVEN VARYING CONCENTRATIONS OF MALUNGGAY (Moringa oleifera Lam. AQUEOUS LEAF EXTRACT

    Directory of Open Access Journals (Sweden)

    H.P. PORTUGALIZA

    2012-11-01

    Full Text Available A study was conducted to determine the growth performance of Cobb broilers supplemented with varying concentrations of Moringa oleifera Aqueous Leaf Extract (MoALE via the drinking water. A total of four hundred day-old chicks were randomly distributed into four treatment groups, replicated four times with twenty-five broilers per replicate. The growth performance of broilers was evaluated based on their feed consumption, live weight, feed conversion ratio (FCR and return of investment (ROI. Results of the study showed that at 90 mL MoALE (T3, the feed consumption of broilers was consistently lower than the control group (T0 and this was statistically significant (P<0.01. The live weight of broilers given 30 mL (T1, 60 mL (T2 and 90 mL (T3 MoALEs were significantly higher than the control group (T0 and this was also statistically significant (P<0.01. In terms of feed conversion ratio (FCR, the MoALE treated broilers (T1-T3 were more efficient converter of feeds into meat than the control group (T0 and this was statistically significant (P<0.01. Furthermore, the return of investment (ROI of MoALE treated broilers (T1-T3 was significantly higher (P<0.01 than the control group (T0 with a revenue per peso invested of Php 0.62 in T1 and T2, and Php 0.63 in T3 compared to Php 0.50 in T0.

  16. Epoxidized natural rubber toughened aqueous resole type liquefied EFB resin: Physical and chemical characterization

    Science.gov (United States)

    Amran, Umar Adli; Zakaria, Sarani; Chia, Chin Hua

    2013-11-01

    A preliminary study on the reaction between aqueous resole type resinified liquefied palm oil empty fruit bunches fibres (RLEFB) with epoxidized natural rubber (ENR). Liquefaction of empty fruit bunches (EFB) is carried out at different ratio of phenol to EFB (P:EFB). Resole type phenolic resin is prepared using sodium hydroxide (NaOH) as the catalyst with the ratio of liquefied EFB (LEFB) to formaldehyde (LEFB:F) of 1:1.8. 50% epoxidation of epoxidized natural rubber (ENR-50) is used to react with resole resin by mixing with ENR with aqueous resole resin. The cured resin is characterized with FT-IR and SEM. Aqueous system have been found to be unsuitable medium in the reaction between resin and ENR. This system produced a highly porous product when RLEFB/ENR resin is cured.

  17. Biofilm supported increase of chemical weathering and decrease of chemical denudation in pine growth experiments

    Science.gov (United States)

    Balogh, Z.; Keller, C.; Gill, R. A.

    2006-12-01

    Vascular plants and associated microbial communities produced biofilm coatings increase weathering by extending contact periods of minerals with low pH liquids. We performed an experiment to isolate the effects of ectomycorrhiza-forming fungi and ectomycorrhiza- helper bacteria on chemical weathering and chemical denudation (i.e. chemical erosion), and their effects on these fluxes in association with red pine as a host. The study was conducted in a growth chamber using sandy growth medium in replicated flow-through columns. Biotite and anorthite supplied Ca, Mg and K. Concentrations of these cations were measured in input and output solutions, in tree biomass and on exchangeable cation sites of the growth medium; then weathering and denudation fluxes were estimated by mass-balance. In addition, mineral surface changes, biofilm cover and microbial attachment to surfaces were investigated with scanning electron microscopy. The column experiment demonstrated that both bacteria and fungi had a large weathering potential for Ca- bearing minerals, but the microbial communities were not able to regulate denudation losses without a vascular host. Chemical weathering and denudation were about equal in each microbe-only treatment. By the second 6 months of the experiment treatment effects became significant for the seedling systems (pplant without allowing loss to the bulk soil solution. On the other hand, the non-ectomycorrhizal treatment produced more root hairs and fine roots, which partially compensated for hyphal absorbing surfaces in the biofilm cover. The present study supports our proposition that microbial biofilms can not only accelerate the weathering process, but also regulate denudation losses by acting as a protective layer covering the mineral-water-hyphal/root hair interface in the mycorrhizosphere and rhizosphere of vascular plants.

  18. Orange pectin mediated growth and stability of aqueous gold and silver nanocolloids

    Energy Technology Data Exchange (ETDEWEB)

    Nigoghossian, Karina; Santos, Molíria V. dos; Barud, Hernane S.; Silva, Robson R. da [Institute of Chemistry, São Paulo State University – UNESP, 14801-970 Araraquara, SP (Brazil); Rocha, Lucas A. [Departamento de Quimica, Universidade de Franca, Franca, SP (Brazil); Caiut, José M.A. [Departamento de Química, FFCLRP, USP, Ribeirão Preto, SP (Brazil); Assunção, Rosana M.N. de [Faculdade de Ciências Integradas do Pontal, Universidade Federal de Uberlândia, 38302-000 Ituiutaba, MG (Brazil); Spanhel, Lubomir [CEITEC-Central European Institute of Technology, Masaryk University Brno (Czech Republic); Institute of Chemical Sciences, University of Rennes 1, Campus Beaulieu, 35 042 Rennes (France); Poulain, Marcel [Institute of Chemical Sciences, University of Rennes 1, Campus Beaulieu, 35 042 Rennes (France); Messaddeq, Younes [Institute of Chemistry, São Paulo State University – UNESP, 14801-970 Araraquara, SP (Brazil); Ribeiro, Sidney J.L., E-mail: sidney@iq.unesp.br [Institute of Chemistry, São Paulo State University – UNESP, 14801-970 Araraquara, SP (Brazil)

    2015-06-30

    Graphical abstract: - Highlights: • Pectin from orange was used as stabilizer of Ag, Au and Ag–Au nanoparticles. • Sodium citrate, oxalic acid or pectin were used as reducing agents. • Colloids spanning all visible region were obtained depending on Ag/Au-ratio and pH. • Pectin is a highly efficient stabilizer of nanocolloidal solutions for years. - Abstract: The role of orange based pectin in the nucleation and growth of silver and gold nanoparticles is addressed. Pectin is a complex polysaccharide found in fruits such as oranges, lemons, passion fruits or apples. It displays smooth and hairy chain regions containing hydroxyl-, ester-, carboxylate- and eventually amine groups that can act as surface ligands interacting under various pH conditions more or less efficiently with growing nanometals. Here, a high methoxy pectin (>50% esterified) was used as a stabilizer/reducing agent in the preparation of gold, silver and silver–gold nanoparticles. Commercial pectin (CP) and pectin extracted from orange bagasse (OP) were used. Optionally, trisodium citrate or oxalic acid we used to reduce AgNO{sub 3} and HAuCl{sub 4} in aqueous environment. Characterization methods included UV–vis absorption spectroscopy, transmission electron microscopy, electron diffraction and energy-dispersive X-ray spectroscopy. The results show that under different pH conditions, pectin and reducing agents allow producing various nanostructures shapes (triangles, spheres, rods, octahedrons and decahedrons) often with high polydispersity and sizes ranging between 5 nm and 30 nm. In addition, depending on Ag/Au-ratio and pH, the surface plasmon bands can be continuously shifted between 410 nm and 600 nm. Finally, pectin seems to be a highly efficient stabilizer of the colloidal systems that show a remarkable stability and unchanged optical spectral response even after five years.

  19. Radiation chemical behavior of aqueous butanal oxime solutions irradiated with helium ion beams

    Science.gov (United States)

    Costagliola, A.; Venault, L.; Deroche, A.; Garaix, G.; Vermeulen, J.; Omnee, R.; Duval, F.; Blain, G.; Vandenborre, J.; Fattahi-Vanani, M.; Vigier, N.

    2016-02-01

    Samples of butanal oxime in aqueous solution have been irradiated with the helion (4He2+) beam of the ARRONAX (Nantes) and the CEMHTI (Orléans) cyclotrons. The consumption yield of butanal oxime has been measured by gas-chromatography coupled with mass spectrometry. Yields of gaseous products (mainly H2) have also been measured by micro-gas-chromatography. Butanal oxime can react with H• radicals by abstraction mechanism to enhance H2 production. Yields of liquid phase products (hydrogen peroxide and nitrite ion) have been measured by colorimetric methods. Butanal oxime acts as a scavenger of OH• radical to inhibit the production of H2O2. The observation of the radiolytic products allows then to discuss a degradation mechanism of butanal oxime in aqueous solutions.

  20. Quantum Chemical and Molecular Dynamics Study of the Coordination of Th(IV) in Aqueous Solvent

    OpenAIRE

    Réal, Florent; Trumm, Michael; Vallet, Valérie; Schimmelpfennig, Bernd; Masella, Michel; Flament, Jean-Pierre

    2010-01-01

    In this work, we investigate the solvation of tetravalent thorium Th(IV) in aqueous solution using classical molecular dynamics simulations at the 10 ns scale and based on polarizable force-field approaches, which treat explicitly the covalent character of the metal−water interaction (and its inherent cooperative character). We have carried out a thorough analysis of the accuracy of the ab initio data that we used to adjust the force-field parameters. In particular, we show that large atomic ...

  1. Localized Chemical Redistribution During Aqueous Alteration in CR2 Carbonaceous Chondrites EET 87770 and EET 92105

    Science.gov (United States)

    Burger, Paul V.; Brearley, Adrian J.

    2005-01-01

    Carbonaceous chondrites are primitive meteorites that are valuable because they preserve evidence of processes that occurred in the solar nebula and on asteroidal parent bodies. Among the carbonaceous chondrite groups, the CR group appears to contain a particularly pristine record of early solar system processes. Distinguishing characteristics of CR2 chondrites include a high abundance of chondrules (50-60 vol.%) and Fe, Ni metal (5-8 vol. %). These meteorites preserve evidence for varying degrees of aqueous alteration, manifested by progressive replacement of chondrule mesostasis by phyllosilicates. Recent studies have suggested that even in weakly altered chondrites, mass transfer occurred between chondrules and fine-grained matrices, implying that aqueous alteration must have followed lithification of the final meteorite parent body. Although petrographic characteristics of alteration in CR chondrites have been documented, mechanisms of alteration are still only poorly understood. For example, the relative rates and scales of elemental mobility as well as the sources and sinks for key elements are currently not constrained. An improved knowledge of these issues will contribute to an increased understanding of aqueous alteration reactions on meteorite parent bodies. This study expands on research conducted on Type IIA chondrules and chondrule fragments from two CR2 chondrites, EET 87770 and EET 92105. These chondrites have been weakly altered; chondrule mesostases show incipient alteration primarily where they are in direct contact with fine-grained matrices.

  2. Growth of graphene underlayers by chemical vapor deposition

    Directory of Open Access Journals (Sweden)

    Mopeli Fabiane

    2013-11-01

    Full Text Available We present a simple and very convincing approach to visualizing that subsequent layers of graphene grow between the existing monolayer graphene and the copper catalyst in chemical vapor deposition (CVD. Graphene samples were grown by CVD and then transferred onto glass substrates by the bubbling method in two ways, either direct-transfer (DT to yield poly (methyl methacrylate (PMMA/graphene/glass or (2 inverted transfer (IT to yield graphene/PMMA/glass. Field emission scanning electron microscopy (FE-SEM and atomic force microscopy (AFM were used to reveal surface features for both the DT and IT samples. The results from FE-SEM and AFM topographic analyses of the surfaces revealed the underlayer growth of subsequent layers. The subsequent layers in the IT samples are visualized as 3D structures, where the smaller graphene layers lie above the larger layers stacked in a concentric manner. The results support the formation of the so-called “inverted wedding cake” stacking in multilayer graphene growth.

  3. Growth of graphene underlayers by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Fabiane, Mopeli; Khamlich, Saleh; Bello, Abdulhakeem; Dangbegnon, Julien; Momodu, Damilola; Manyala, Ncholu, E-mail: ncholu.manyala@up.ac.za [Department of Physics, Institute of Applied Materials, SARChI Chair in Carbon Technology and Materials, University of Pretoria, Pretoria 0028 (South Africa); Charlie Johnson, A. T. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104 (United States)

    2013-11-15

    We present a simple and very convincing approach to visualizing that subsequent layers of graphene grow between the existing monolayer graphene and the copper catalyst in chemical vapor deposition (CVD). Graphene samples were grown by CVD and then transferred onto glass substrates by the bubbling method in two ways, either direct-transfer (DT) to yield poly (methyl methacrylate) (PMMA)/graphene/glass or (2) inverted transfer (IT) to yield graphene/PMMA/glass. Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) were used to reveal surface features for both the DT and IT samples. The results from FE-SEM and AFM topographic analyses of the surfaces revealed the underlayer growth of subsequent layers. The subsequent layers in the IT samples are visualized as 3D structures, where the smaller graphene layers lie above the larger layers stacked in a concentric manner. The results support the formation of the so-called “inverted wedding cake” stacking in multilayer graphene growth.

  4. Computational insight into the chemical space of plant growth regulators.

    Science.gov (United States)

    Bushkov, Nikolay A; Veselov, Mark S; Chuprov-Netochin, Roman N; Marusich, Elena I; Majouga, Alexander G; Volynchuk, Polina B; Shumilina, Daria V; Leonov, Sergey V; Ivanenkov, Yan A

    2016-02-01

    An enormous technological progress has resulted in an explosive growth in the amount of biological and chemical data that is typically multivariate and tangled in structure. Therefore, several computational approaches have mainly focused on dimensionality reduction and convenient representation of high-dimensional datasets to elucidate the relationships between the observed activity (or effect) and calculated parameters commonly expressed in terms of molecular descriptors. We have collected the experimental data available in patent and scientific publications as well as specific databases for various agrochemicals. The resulting dataset was then thoroughly analyzed using Kohonen-based self-organizing technique. The overall aim of the presented study is to investigate whether the developed in silico model can be applied to predict the agrochemical activity of small molecule compounds and, at the same time, to offer further insights into the distinctive features of different agrochemical categories. The preliminary external validation with several plant growth regulators demonstrated a relatively high prediction power (67%) of the constructed model. This study is, actually, the first example of a large-scale modeling in the field of agrochemistry.

  5. Activation of Cassava Stem Biochar by Physico-Chemical Method for Stimulating Cadmium Removal Efficiency from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Songkrit Prapagdee

    2014-06-01

    Full Text Available Removal of Cadmium (Cd from aqueous solution using biochar was considered a cost effective sorbent. Biochar quality and specification depend on its carbonization processes. In this study, the cassava stem biochars were produced at temperature of 300, 400 and 500 °C with slow pyrolysis technique. The biochar in each carbonization temperature was activated with physico-chemical treatments, pre-activated by 1.63M KOH solution then activated with second pyrolysis as same as first pyrolysis conditions. Adsorption study by using biochar adsorb Cd ion from Cd(NO32 solution by batch static method. The results indicated that the removal efficiency of activated biochar produced at pyrolysis temperature 300 °C can be increased from 10.46 to 24.88 mg/g and was selected for adsorption characteristic and biochar properties. Adsorption isotherm of non-activated and activated biochar were fitted both Langmuir and Freundlich isotherm (r2>0.95. The BET surface area of activated biochar was increased from 6.8818 to 9.4964 m2/g, while, pore size and chemical properties could be preserved. In summary, our results suggest that KOH pre-activated and second pyrolysis could increase Cd removal efficiency from aqueous solution.

  6. Extraction of Phthalic Acid from Aqueous Solution by Using Ionic Liquids: A Quantum Chemical Approach

    OpenAIRE

    Pilli, S; Mohanty, Kaustubha; Banerjee, Tamal

    2014-01-01

    Phthalic acid is an industrial chemical and it comes under the domain of endocrine disrupting chemicals (EDCs). Green solvents such as ionic liquids (ILs) posses good extractable capabilities for EDCs. COSMO–RS methodology is a widely accepted method for the design or selection of ionic liquids. COSMO–RS is a quantum chemical based method based on COSMO polarization charge densities. In this work the model has been used to screen the potential ionic liquids for the removal of phthalic acid fr...

  7. Calculations of physical and chemical reactions with DNA in aqueous solution from Auger cascades

    International Nuclear Information System (INIS)

    Monte Carlo calculations are performed of the physical and chemical interactions in liquid water by electrons produced during Auger cascades resulting from the decay of various radionuclides. Estimates are also made of the number of direct physical and indirect chemical interactions that would be produced on DNA located near the decay site. 13 refs., 8 figs

  8. Multiscale approach to CO2 hydrate formation in aqueous solution: phase field theory and molecular dynamics. Nucleation and growth.

    Science.gov (United States)

    Tegze, György; Pusztai, Tamás; Tóth, Gyula; Gránásy, László; Svandal, Atle; Buanes, Trygve; Kuznetsova, Tatyana; Kvamme, Bjorn

    2006-06-21

    A phase field theory with model parameters evaluated from atomistic simulations/experiments is applied to predict the nucleation and growth rates of solid CO(2) hydrate in aqueous solutions under conditions typical to underwater natural gas hydrate reservoirs. It is shown that under practical conditions a homogeneous nucleation of the hydrate phase can be ruled out. The growth rate of CO(2) hydrate dendrites has been determined from phase field simulations as a function of composition while using a physical interface thickness (0.85+/-0.07 nm) evaluated from molecular dynamics simulations. The growth rate extrapolated to realistic supersaturations is about three orders of magnitude larger than the respective experimental observation. A possible origin of the discrepancy is discussed. It is suggested that a kinetic barrier reflecting the difficulties in building the complex crystal structure is the most probable source of the deviations.

  9. Comparison of the Chemical Composition and Pharmacological Effects of the Aqueous and Ethanolic Extracts from a Tibetan “Snow Lotus” (Saussurea laniceps Herb

    Directory of Open Access Journals (Sweden)

    Zhijun Yang

    2012-06-01

    Full Text Available To understand the impacts of different processing methods on the composition and effects of the herb Saussurea laniceps (SL, the present study report the first comparison of the chemical constituents of aqueous and ethanolic SL extracts using chromatographic analysis, and to compare their pharmacological effects in a mouse anti-inflammatory, anti-nociceptive model and an in vitro anti-oxidant test. Chemical comparison demonstrated that the types of chemicals in the two extracts were identical, but the contents of the main constituents in the aqueous extract were lower than those of the ethanolic extract. A transesterification of dicaffeoylquinic acids took place in the aqueous extract during boiling. As for pharmacological effects, oral administration of aqueous and ethanolic SL extracts significantly inhibited croton oil-induced mice ear edema, and significantly inhibited acetic acid-induced mice writhings, respectively. In the DPPH anti-oxidant activity test, the IC50 values were calculated as 409.6 mg/L and 523.4 mg/L for the ethanolic and aqueous extracts, respectively. The inhibitory effects of the ethanolic extract were more potent than those of the aqueous extract in all pharmacological tests, although there was no significant difference. This study suggests that the two preparations should be distinguished when used.

  10. Mechanism for the formation of elemental sulfur from aqueous sulfide in chemical and microbiological desulfurization processes

    Energy Technology Data Exchange (ETDEWEB)

    Steudel, R. [Technische Univ. Berlin (Germany). Inst. fuer Anorganische und Analytische Chemie

    1996-04-01

    A detailed reaction mechanism is proposed for the formation of crystalline elemental sulfur from aqueous sulfide by oxidation with transition-metal ions like V{sup 5}, Fe{sup 3}, Cu{sup 2}, etc. The first step is the formation of HS{center_dot} radicals by one-electron oxidation of HS{sup {minus}} ions. These radicals exist at pH values near 7 mainly as S{center_dot}{sup {minus}}. Their spontaneous decay results in the formation of the disulfide ion S{sub 2}{sup 2{minus}}. The further oxidation of disulfide either by S{center_dot}{sup {minus}} radicals or by the transition-metal ions yields higher polysulfide ions from which the homocyclic sulfur molecules S{sub 6}, S{sub 7}, and S{sub 8} are formed. In water these hydrophobic molecules form clusters which grow to droplets of liquid sulfur (sulfur sol). Depending on the composition of the aqueous phase, crystallization of the liquid sulfur as either {alpha}- or {beta}-S{sub 8} is rapid or delayed. Surfactants delay this solidification, while certain cations promote it. All these reactions are proposed to take place in desulfurization plants working by the Stretford, Sulfolin, Lo-Cat, SulFerox, or Bio-SR processes. In addition, the sulfur produced from sulfide by oxidizing sulfur bacteria is formed by the same mechanism, which now explains many observations made previously (including the formation of the byproducts thiosulfate, polythionates, and sulfate).

  11. Physical and chemical interactions at the interface between atmospheric pressure plasmas and aqueous solutions

    Science.gov (United States)

    Lindsay, Alexander; Byrns, Brandon; Knappe, Detlef; Graves, David; Shannon, Steven

    2014-10-01

    Transport and reactions of charged species, neutrals, and photons at the interface between plasmas and liquids must be better quantified. The work presented here combines theoretical and experimental investigations of conditions in the gas and liquid phases in proximity to the interface for various discharges. OES is used to determine rotational and vibrational temperatures of OH, NO, and N2+; the relationship between these temperatures that characterize the distribution of internal energy states and gas and electron kinetic temperatures is considered. The deviation of OH rotational states from equilibrium under high humidity conditions is also presented. In contradiction with findings of other groups, high energy rotational states appear to become underpopulated with increasing humidity. In the aqueous phase, concentrations of longer-lived species such as nitrate, nitrite, hydrogen peroxide, and ozone are determined using ion chromatography and colorimetric methods. Spin-traps and electron paramagnetic resonance (EPR) are investigated for characterization of short-lived aqueous radicals like OH, O2-, NO, and ONOO-. Finally, experimental results are compared to a numerical model which couples transport and reactions within and between the bulk gas and liquid phases.

  12. Atomistic Mechanisms of Chemical Mechanical Polishing of a Cu Surface in Aqueous H2O2: Tight-Binding Quantum Chemical Molecular Dynamics Simulations.

    Science.gov (United States)

    Kawaguchi, Kentaro; Ito, Hiroshi; Kuwahara, Takuya; Higuchi, Yuji; Ozawa, Nobuki; Kubo, Momoji

    2016-05-11

    We applied our original chemical mechanical polishing (CMP) simulator based on the tight-binding quantum chemical molecular dynamics (TB-QCMD) method to clarify the atomistic mechanism of CMP processes on a Cu(111) surface polished with a SiO2 abrasive grain in aqueous H2O2. We reveal that the oxidation of the Cu(111) surface mechanically induced at the friction interface is a key process in CMP. In aqueous H2O2, in the first step, OH groups and O atoms adsorbed on a nascent Cu surface are generated by the chemical reactions of H2O2 molecules. In the second step, at the friction interface between the Cu surface and the abrasive grain, the surface-adsorbed O atom intrudes into the Cu bulk and dissociates the Cu-Cu bonds. The dissociation of the Cu-Cu back-bonds raises a Cu atom from the surface that is mechanically sheared by the abrasive grain. In the third step, the raised Cu atom bound to the surface-adsorbed OH groups is removed from the surface by the generation and desorption of a Cu(OH)2 molecule. In contrast, in pure water, there are no geometrical changes in the Cu surface because the H2O molecules do not react with the Cu surface, and the abrasive grain slides smoothly on the planar Cu surface. The comparison between the CMP simulations in aqueous H2O2 and pure water indicates that the intrusion of a surface-adsorbed O atom into the Cu bulk is the most important process for the efficient polishing of the Cu surface because it induces the dissociation of the Cu-Cu bonds and generates raised Cu atoms that are sheared off by the abrasive grain. Furthermore, density functional theory calculations show that the intrusion of the surface-adsorbed O atoms into the Cu bulk has a high activation energy of 28.2 kcal/mol, which is difficult to overcome at 300 K. Thus, we suggest that the intrusion of surface-adsorbed O atoms into the Cu bulk induced by abrasive grains at the friction interface is a rate-determining step in the Cu CMP process. PMID:27092706

  13. Chemical characterization of the main secondary organic aerosol (SOA products formed through aqueous-phase photonitration of guaiacol

    Directory of Open Access Journals (Sweden)

    Z. Kitanovski

    2014-04-01

    Full Text Available Guaiacol (2-methoxyphenol and its derivatives can be emitted into the atmosphere by thermal degradation (i.e. burning of wood lignins. Due to its volatility, guaiacol is predominantly distributed in the atmospheric gaseous phase. Recent studies have shown the importance of aqueous-phase reactions in addition to the dominant gas-phase and heterogeneous reactions of guaiacol, in the formation of secondary organic aerosol (SOA in the atmosphere. The main objectives of the present study were to chemically characterize the low-volatility SOA products of the aqueous-phase photonitration of guaiacol and examine their possible presence in urban atmospheric aerosols. The aqueous-phase reactions were carried out under simulated sunlight and in the presence of H2O2 and nitrite. The formed guaiacol reaction products were concentrated by using solid-phase extraction (SPE and then purified by means of semi-preparative high-performance liquid chromatography (HPLC. The fractionated individual compounds were isolated as pure solids and further analyzed with liquid-state 1H, 13C and 2D nuclear magnetic resonance (NMR spectroscopy and direct infusion negative ion electrospray ionization tandem mass spectrometry ((–ESI-MS/MS. The NMR and product ion (MS2 spectra were used for unambiguous product structure elucidation. The main products of guaiacol photonitration are 4-nitroguaiacol (4NG, 6-nitroguaiacol (6NG, and 4,6-dinitroguaiacol (4,6DNG. Using the isolated compounds as standards, 4NG and 4,6DNG were unambiguously identified in winter PM10 aerosols from the city of Ljubljana (Slovenia by means of HPLC/(–ESI-MS/MS. Owing to the strong absorption of UV and visible light, 4,6DNG could be an important constituent of atmospheric "brown" carbon, especially in regions affected by biomass burning.

  14. Chemical reactivity of self-organized alumina nanopores in aqueous medium

    Energy Technology Data Exchange (ETDEWEB)

    Rocca, E., E-mail: emmanuel.rocca@lcsm.uhp-nancy.fr [Institut Jean Lamour UMR CNRS 7198, Department CP2S, Nancy University, BP 70239, 54506 Vandoeuvre-les-Nancy (France); Vantelon, D. [Synchrotron Soleil, l' Orme des Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex (France); Gehin, A. [Institut Jean Lamour UMR CNRS 7198, Department CP2S, Nancy University, BP 70239, 54506 Vandoeuvre-les-Nancy (France); Augros, M.; Viola, A. [Messier-Bugatti (Safran Group), 5 Rue Antoine St Exupery, 67129 Molsheim (France)

    2011-02-15

    This work is devoted to the characterization of the structure and chemistry of small self-organized nanopores of aluminum oxide in aqueous medium (diameter <20 nm). A structural model based on AlO{sub 4}/AlO{sub 6} clusters is proposed to describe the amorphous oxide constituting the walls of the nanostructure. X-ray absorption near edge spectroscopy measurements, electrokinetic measurements and O{sup 18} tracer experiments bring to light the structural changes and the specific diffusion mechanism in the nanometer network. Immersion in boiling water induces both the transformation of AlO{sub 4} to AlO{sub 6} clusters and the release of sulfate species by hydrolysis. Water molecules rapidly diffuse in the nanostructure, but ion diffusion is selective because of surface positive charges and overlap of the surface electric field in very small pores.

  15. Chemical treatment of aqueous radioactive Cesium-137 waste using Ferri Chloride

    International Nuclear Information System (INIS)

    Ferric Chloride 6H2O was used for treatment of liquid radioactive wastes containing Cesium-137. Various concentration of ferric chloride 6H2O have been added into the waste at different pH and speed of stirrer. The treatment was based on the coagulans-flocculation and coprecipitation mechanisms. The best result of this experiment was achieved by adding 300 ppm of Ferric chloride 6 H2O into liquid waste on following condition the rate Stirrer was 250 rpm. At this condition, it was found that the separation efficiency and the decontamination factor were 83.32 % and 5.99. The activity of decreasing of aqueous radioactive Cesium-137 waste was 2.10 x 10-4 Ci/l to 3.50 x 10-5 Ci/l

  16. Experimental and Quantum Chemical Calculations of Imidazolium Appended Naphthalene Hybrid in Different Biomimicking Aqueous Interfaces.

    Science.gov (United States)

    Yenupuri, Tej Varma; Mydlova, Lucia; Agarwal, Devesh S; Sharma, Ritika; Sakhuja, Rajeev; Makowska-Janusik, Malgorzata; Pant, Debi D

    2016-08-25

    The effect of solvent polarity and micellar headgroup on a newly designed imidazolium based ionic liquid (IL) conjugated with naphthalene, 1,2-dimethyl-3-((6-(octyloxy)naphthalen-2-yl)methyl)-1H-imidazol-3-ium chloride (IN-O8-Cl), was studied using steady state and time-resolved fluorescence techniques. We observed that the dipole moment in the excited state is remarkably higher than the ground state. The effect of micellar surface charge on the photophysics of IN-O8-Cl in aqueous phase at room temperature was investigated. Formation of premicellar aggregates in sodium dodecylsulfate (SDS) was perceived; further the microenvironment of IN-O8-Cl was examined using steady-state fluorescence spectroscopy. Micropolarity of the micellar environment of SDS was found to be lower than that of cetyltrimethylammonium bromide (CTAB) and triton X-100 (TX100) following the order SDS < TX-100 < CTAB. The binding constant (Kb) and edge excitation red shift (EERS) from the emission maximum suggest that the probe binds strongly to the micelles. Multiexponential behavior was observed in time-resolved fluorescence lifetime studies in all micellar environments. We have observed an increase in rotational correlation time as we move from pure aqueous phase to solution containing surfactants of different head charge. Varieties of spectral parameters were used to justify the region in which the probe is present. The experimentally obtained dipole moment data were justified and explained by the DFT calculations of the electronic properties of IN-O8-Cl molecules in gas phase and in selected solvents. PMID:27486828

  17. Physical and chemical effects of direct aqueous advanced oxidation processing on green sand foundry mold materials

    Science.gov (United States)

    Clobes, Jason Kenneth

    Iron foundries using the common green sand molding process have increasingly been incorporating aqueous advanced oxidation (AO) systems to reduce the consumption of sand system bentonite clay and coal raw materials by and to decrease their volatile organic compound (VOC) emissions. These AO systems typically use a combination of sonication, ozone aeration, and hydrogen peroxide to treat and recycle slurries of sand system baghouse dust, which is rich in clay and coal. While the overall effects of AO on raw material consumption and organic emissions are known, the mechanisms behind these effects are not well understood. This research examined the effects of bench-scale direct aqueous AO processing on green sand mold materials at the micro level. Bench-scale AO processing, including acoustic sonication, ozone/oxygen aeration, and hydrogen peroxide dramatically decreased the particle sizes of both western bentonite and foundry sand system baghouse dust. Bench-scale AO processing was shown to effectively separate the clay material from the larger silica and coal particles and to extensively break up the larger clay agglomerates. The acoustic sonication component of AO processing was the key contributor to enhanced clay recovery. Acoustic sonication alone was slightly more effective than combined component AO in reducing the particle sizes of the baghouse dust and in the recovery of clay yields in the supernatant during sedimentation experiments. Sedimentation separation results correlated well with the increase in small particle concentrations due to AO processing. Clay suspension viscosity decreased with AO processing due to enhanced dispersion of the particles. X-ray diffraction of freeze-dried baghouse dust indicated that AO processing does not rehydrate calcined montmorillonite and does not increase the level of interlayer water hydration in the dry clays. Zeta potential measurements indicated that AO processing also does not produce any large changes in the

  18. Nanofiltration and sensing of picomolar chemical residues in aqueous solution using an optical porous resonator in a microelectrofluidic channel

    Science.gov (United States)

    Huang, Lei; Guo, Zhixiong

    2012-02-01

    For the first time the use of a porous microresonator placed in a microelectrofluidic system for integrated functions of nanofiltration and sensing of small biomolecules and chemical analytes in extremely dilute solution was proposed and investigated. As an example, aminoglycosides in drug residues in food and livestock products were considered as the trace chemical analyte. The filtration process of the charged analyte in aqueous solution driven by an applied electrical field and the accompanying optical whispering-gallery modes in the resonator are modeled. The dynamic process of adsorption and desorption of the analyte onto the porous matrix is studied. Deposition of the analyte inside the porous structure will alter the material refractive index of the resonator, and thus induce an optical resonance frequency shift. By measuring the optical frequency shift, the analyte concentration as well as the absorption/desorption process can be analyzed. Through an intensive numerical study, a correlation between the frequency shift and the analyte concentration and the applied electrical voltage gradient was obtained. This reveals a linear relationship between the resonance frequency shift and the analyte concentration. The applied electrical voltage substantially enhances the filtration capability and the magnitude of the optical frequency shift, pushing the porous resonator-based sensor to function at the extremely dilute picomolar concentration level for small bio/chemical molecules down to the sub-nanometer scale. Moreover, use of the second-order whispering-gallery mode is found to provide better sensitivity compared with the first-order mode.

  19. Nanofiltration and sensing of picomolar chemical residues in aqueous solution using an optical porous resonator in a microelectrofluidic channel

    International Nuclear Information System (INIS)

    For the first time the use of a porous microresonator placed in a microelectrofluidic system for integrated functions of nanofiltration and sensing of small biomolecules and chemical analytes in extremely dilute solution was proposed and investigated. As an example, aminoglycosides in drug residues in food and livestock products were considered as the trace chemical analyte. The filtration process of the charged analyte in aqueous solution driven by an applied electrical field and the accompanying optical whispering-gallery modes in the resonator are modeled. The dynamic process of adsorption and desorption of the analyte onto the porous matrix is studied. Deposition of the analyte inside the porous structure will alter the material refractive index of the resonator, and thus induce an optical resonance frequency shift. By measuring the optical frequency shift, the analyte concentration as well as the absorption/desorption process can be analyzed. Through an intensive numerical study, a correlation between the frequency shift and the analyte concentration and the applied electrical voltage gradient was obtained. This reveals a linear relationship between the resonance frequency shift and the analyte concentration. The applied electrical voltage substantially enhances the filtration capability and the magnitude of the optical frequency shift, pushing the porous resonator-based sensor to function at the extremely dilute picomolar concentration level for small bio/chemical molecules down to the sub-nanometer scale. Moreover, use of the second-order whispering-gallery mode is found to provide better sensitivity compared with the first-order mode. (paper)

  20. NMR chemical shift analysis of the conformational transition between the monomer and tetramer of melittin in an aqueous solution.

    Science.gov (United States)

    Miura, Yoshinori

    2016-05-01

    It is known that melittin in an aqueous solution undergoes a conformational transition between the monomer and tetramer by variation in temperature. The transition correlates closely with isomers of the proline residue; monomeric melittin including a trans proline peptide bond (trans-monomer) is involved directly in the transition, whereas monomeric melittin having a cis proline peptide bond (cis-monomer) is virtually not. The transition has been explored by using nuclear magnetic resonance spectroscopy in order to clarify the stability of the tetrameric conformation and the cooperativity of the transition. In the light of temperature dependence of chemical shifts of resonances from the isomeric monomers, we qualitatively estimate the temperature-, salt-, and concentration-dependence of the relative equilibrium populations of the trans-monomer and tetramer, and show that the tetramer has a maximum conformational stability at 30-45 °C and that the transition cooperativity is very low. PMID:26658745

  1. Pharmacokinetics of recombinant human basic fibroblast growth factor in rabbits and mice serum and rabbits aqueous humor

    Institute of Scientific and Technical Information of China (English)

    Qi ZHANG; Guang-ji WANG; Jian-guo SUN

    2004-01-01

    AIM: To study the pharmacokinetics of recombinant human basic fibroblast growth factor (rhbFGF) in rabbits and mice after iv and postocular administration, and the changes of rhbFGF in rabbits aqueous humor after postocular administration. METHODS: After iv or postocular administration three doses of rhbFGF in rabbits and mice,rhbFGF concentration in serum and rabbit aqueous humor was determined by enzyme-linked immunosorbent .assay. RESULTS: Serum concentration-time data of rabbits after iv administration of rhbFGF 1, 2, and 4 μg/kg were fitted to bi-exponential equations with half-lives of 0.9, 0.9, and 0.6 min for T1/2α and 7, 8, and 4.7 min for T1/2β.Plasma concentration-time data of mice after iv administration of rhbFGF 2.5, 5 and 10 μg/kg were fitted to biexponential equations with half-lives of 0.4, 0.6, and 0.9 min for T1/2α and 6, 5, and 7 min for T1/2β. The AUCs were linearly correlated to doses in both cases (rrabbit=0.997, rmouse=0.999). The serum concentrations of rhbFGF were very low, near to the background after postocular administration of 2 or 5 μg/kg, in both rabbits and mice. The rhbFGF levels in rabbits aqueous humor were higher than control 8 h postdose (P<0.01). CONCLUSION: rhbFGF within the examined doses had a linear pharmacokinetics in rabbits and mice. High concentration of rhbFGF was found in rabbits aqueous humor after postocular administration.

  2. Model Experiments on Chemical Properties of Superheavy Elements in Aqueous Solutions

    CERN Document Server

    Szeglowski, Z

    2003-01-01

    This paper presents a brief review of model experiments on investigation of chemical properties of transactinide elements, ranging from 104 to 116. The possibilities of isolation of the nuclei of these elements from nuclear reaction products, using the ion-exchange method, are also considered.

  3. The effects of crude aqueous and alcohol extracts of Aloe vera on growth and abdominal viscera of suckling rats.

    Science.gov (United States)

    Beya, Wabeya; Davidson, Bruce; Erlwanger, Kennedy H

    2012-01-01

    The gastrointestinal tract of neonates is sensitive to dietary manipulations. When nursing mothers use Aloe vera, their babies are at risk of indirect exposure to Aloe vera via breast feeding or directly as health supplements. The effects of orally administered extracts of Aloe vera in unweaned rats were investigated. Six day old Sprague-Dawley rats were gavaged with aqueous or alcohol extracts of Aloe vera (low dose 50mg. kg⁻¹ or high dose 500mg. kg⁻¹) daily for eight days. All data were expressed as mean ± SD and analyzed by one way ANOVA. Pups receiving high doses of either extract had a significantly higher body mass gain than the group receiving lower dose (p Aloe vera extracts resulted in growth promotion, enhanced hepatic storage of metabolic substrates, increased ALP possibly in relation to bone growth and caused hypertrophy of the caecum of neonatal rats. These effects need to be explored further to enhance animal production and health.

  4. Allelopathy of aqueous leaf extracts from the invasive alien tree Pittosporum undulatum on germination and growth of barnyard grass

    Directory of Open Access Journals (Sweden)

    Fernando Bertol Carpanezzi

    2014-09-01

    Full Text Available Barnyard grass (Echinochloa crusgalli (L. P. Beauv. is a herbicide-resistant weed that brings negative impacts to rice crops and threatens floodplains biodiversity worldwide. This study aimed to investigate allelopathic influences of extracts from Pittosporum undulatum Vent. (cheesewood leaves on barnyard grass. Leachates in concentrations of 20%, 15%, 10%, 5% and 2.5% (w/v, aqueous extracts from powdered leached and non-leached leaves (10%, 7,5%, 5%, 2.5% and 1.25% for both, coumarin solution at 0.6 mM and original Roundup ® in concentration according to the label information were prepared. Petri-dishes germination bioassays, with counting at each 12 hours, allowed to determinate both germinability and germination rate; polyethylene glycol (PEG 6000 solutions were prepared to evaluate osmotic effects. In growth tests, seedlings were exposed for seven days, when root and shoot lengths were measured. Germination was sensitive to extracts from powdered leaves. In regard to growth, roots showed dose-dependent length reduction and necrosis. Inhibitory effects from different aqueous extracts suggest action of both internal and external leaf allelochemicals, raising the possibility of Pittosporum undulatum use for barnyard grass control.

  5. Biosorption of heavy metals from aqueous solutions by chemically modified orange peel

    International Nuclear Information System (INIS)

    Equilibrium, thermodynamic and kinetic studies were carried out for the biosorption of Pb2+, Cd2+ and Ni2+ ions from aqueous solution using the grafted copolymerization-modified orange peel (OPAA). Langmuir and Freundlich isotherm models were applied to describe the biosorption of the metal ions onto OPAA. The influences of pH and contact time of solution on the biosorption were studied. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. According to the Langmuir equation, the maximum uptake capacities for Pb2+, Cd2+ and Ni2+ ions were 476.1, 293.3 and 162.6 mg g-1, respectively. Compared with the unmodified orange peel, the biosorption capacity of the modified biomass increased 4.2-, 4.6- and 16.5-fold for Pb2+, Cd2+ and Ni2+, respectively. The kinetics for Pb2+, Cd2+ and Ni2+ ions biosorption followed the pseudo-second-order kinetics. The free energy changes (ΔGo) for Pb2+, Cd2+ and Ni2+ ions biosorption process were found to be -3.77, -4.99 and -4.22 kJ mol-1, respectively, which indicates the spontaneous nature of biosorption process. FTIR demonstrated that carboxyl and hydroxyl groups were involved in the biosorption of the metal ions. Desorption of Pb2+, Cd2+ and Ni2+ ions from the biosorbent was effectively achieved in a 0.05 mol L-1 HCl solution.

  6. Pyrite oxidation by hexavalent chromium: investigation of the chemical processes by monitoring of aqueous metal species.

    Science.gov (United States)

    Demoisson, Frédéric; Mullet, Martine; Humbert, Bernard

    2005-11-15

    Pyrite, an iron sulfide, occurs in many soils and sediments, making it an important natural reductant of toxic metal pollutants. This study investigated the processes leading to aqueous Cr(VI) reduction by pyrite in a closed thermostated (25 +/- 0.1 degrees C) system and under an argon atmosphere. Synthetic pyrite suspensions were reacted with a range of Cr(VI) solutions from 0 to 7 x 10(-4) M and at pH 2-8. Metal species concentrations were continuously monitored during a period lasting approximately 20 h. Preliminary experiments carried out in acidic media without Cr(VI) have shown that some pyrite dissolution occurred. Then, metal species concentration changes with time during pyrite oxidation by Cr(VI) solutions exhibited two distinct trends depending on the complete or incomplete Cr(VI) removal. As long as chromate existed in solution, the Cr-(Ill) to Fe(lIl) ratio was found to be an effective parameter to investigate the pyrite reaction stoichiometry with Cr(VI). Experimental values close to 2 suggest that sulfur compounds with oxidation states between 0 and 2 should be formed during pyrite oxidation by Cr(VI). If Cr(VI) was completely reduced from solution, then the pyrite oxidation by Fe(lll) ions took place to generate ferrous ions. PMID:16323772

  7. Structural, chemical and optical evaluation of Cu-doped ZnO nanoparticles synthesized by an aqueous solution method

    Energy Technology Data Exchange (ETDEWEB)

    Iribarren, A., E-mail: augusto@imre.oc.uh.cu [Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, Vedado, Plaza, La Habana 10400 (Cuba); Hernández-Rodríguez, E. [Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, Vedado, Plaza, La Habana 10400 (Cuba); Maqueira, L. [Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, Vedado, Plaza, La Habana 10400 (Cuba); Facultad de Química, Universidad de La Habana, Zapata y G, Vedado, Plaza, La Habana 10400 (Cuba)

    2014-12-15

    Highlights: • Cu-doped ZnO nanoparticles obtained by chemical synthesis. • Substitutional or interstitial Cu into ZnO lead specific structural, chemical, and optical changes. • Incorporation efficiency of Cu atoms in ZnO as a function of the Cu concentration in the precursor dissolution. - Abstract: In this work a study of ZnO and Cu-doped ZnO nanoparticles obtained by chemical synthesis in aqueous media was carried out. Structural analysis gave the dominant presence of wurtzite ZnO phase forming a solid solution Zn{sub 1−x}Cu{sub x}O. For high Cu doping CuO phase is also present. For low Cu concentration the lattice shrinks due to Cu atoms substitute Zn atoms. For high Cu concentration the lattice enlarges due to predominance of interstitial Cu. From elemental analysis we determined and analyzed the incorporation efficiency of Cu atoms in Zn{sub 1−x}Cu{sub x}O as a function of the Cu concentration in the precursor dissolution. Combining structural and chemical results we described the Cu/Zn precursor concentrations r{sub w} in which the solid solution of Cu in ZnO is predominant. In the region located at r{sub w} ≈ 0.2–0.3 it is no longer valid. For Cu/Zn precursor concentration r{sub w} > 0.3 interstitial Cu dominates, and some amount of copper oxide appears. As the Cu concentration increases, the effective size of nanoparticles decreases. Photoluminescence (PL) measurements of the Cu-doped ZnO nanoparticles were carried out and analyzed.

  8. Elaboration of colloidal silica sols in aqueous medium: functionalities, optical properties and chemical detection of coating

    International Nuclear Information System (INIS)

    The aim of this work was to study surface reactivity of silica nanoparticles through physical and chemical properties of sols and coatings. Applications are numerous and they are illustrated in this work by optical coating preparation for laser components and chemical gas sensor development for nitroaromatics detection. On one hand, protocol synthesis of colloidal silica sols has been developed in water medium using sol-gel process (0 to 100 w%). These sols, so-called BLUESIL, are time-stable during at least one year. Homogeneous coatings having thickness fixed to 200 nm, have been prepared on silica substrate and show high porosity and high transparence. Original films have been developed using catalytic curing in gas atmosphere (ammonia curing) conferring good abrasive resistance to the coating without significant properties modification. In order to reduce film sensitivity to molecular adsorption (water, polluting agents... ), specific BLUESIL coatings have been prepared showing hydrophobic property due to apolar species grafting onto silica nanoparticles. Using this route, coatings having several functional properties such as transparence, hydrophobicity, high porosity and good abrasive resistance have been elaborated. On the other hand, we show that colloidal silica is a material specifically adapted to the detection of nitro aromatic vapors (NAC). Indeed, the use of colloidal silica as chemical gas sensor reveals very high sensitivity, selectivity to NAC compared to Volatile Organic Compound (V.O.C) and good detection performances during one year. Moreover, chemical sensors using functionalized colloidal silica have exhibited good results of detection, even in high humidity medium (≥70 %RH). (author)

  9. Charting the known chemical space for non-aqueous Lithium-air battery electrolyte solvents

    CERN Document Server

    Husch, Tamara

    2015-01-01

    The Li-Air battery is a very promising candidate for powering future mobility, but finding a suitable electrolyte solvent for this technology turned out to be a major problem. We present a systematic computational investigation of the known chemical space for possible Li-Air electrolyte solvents. It is shown that the problem of finding better Li-Air electrolyte solvents is not only - as previously suggested - about maximizing Li+ and O2- solubilities, but about finding the optimal balance of these solubilities with the viscosity of the solvent. As our results also show that trial-and-error experiments on known chemicals are unlikely to succeed, full chemical sub-spaces for the most promising compound classes are investigated, and suggestions are made for further experiments. The proposed screening approach is transferable and robust and can readily be applied to optimize electrolytes for other electrochemical devices. It goes beyond the current state-of-the-art both in width (considering the number of compoun...

  10. Biosorption of heavy metals from aqueous solutions by chemically modified orange peel

    Energy Technology Data Exchange (ETDEWEB)

    Feng Ningchuan [School of Basic Medical Science, Ningxia Medical University, Yinchuan 750004 (China); Guo Xueyi, E-mail: xyguo@mail.csu.edu.cn [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Liang Sha [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Zhu Yanshu; Liu Jianping [School of Basic Medical Science, Ningxia Medical University, Yinchuan 750004 (China)

    2011-01-15

    Equilibrium, thermodynamic and kinetic studies were carried out for the biosorption of Pb{sup 2+}, Cd{sup 2+} and Ni{sup 2+} ions from aqueous solution using the grafted copolymerization-modified orange peel (OPAA). Langmuir and Freundlich isotherm models were applied to describe the biosorption of the metal ions onto OPAA. The influences of pH and contact time of solution on the biosorption were studied. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. According to the Langmuir equation, the maximum uptake capacities for Pb{sup 2+}, Cd{sup 2+} and Ni{sup 2+} ions were 476.1, 293.3 and 162.6 mg g{sup -1}, respectively. Compared with the unmodified orange peel, the biosorption capacity of the modified biomass increased 4.2-, 4.6- and 16.5-fold for Pb{sup 2+}, Cd{sup 2+} and Ni{sup 2+}, respectively. The kinetics for Pb{sup 2+}, Cd{sup 2+} and Ni{sup 2+} ions biosorption followed the pseudo-second-order kinetics. The free energy changes ({Delta}G{sup o}) for Pb{sup 2+}, Cd{sup 2+} and Ni{sup 2+} ions biosorption process were found to be -3.77, -4.99 and -4.22 kJ mol{sup -1}, respectively, which indicates the spontaneous nature of biosorption process. FTIR demonstrated that carboxyl and hydroxyl groups were involved in the biosorption of the metal ions. Desorption of Pb{sup 2+}, Cd{sup 2+} and Ni{sup 2+} ions from the biosorbent was effectively achieved in a 0.05 mol L{sup -1} HCl solution.

  11. Saffron Aqueous Extract Inhibits the Chemically-induced Gastric Cancer Progression in the Wistar Albino Rat

    Directory of Open Access Journals (Sweden)

    S. Zahra Bathaie

    2013-01-01

    Full Text Available Objective(s: Gastric cancer is the first and second leading cause of cancer related death in Iranian men and women, respectively. Gastric cancer management is based on the surgery, radiotherapy and chemotherapy. In the present study, for the first time, the beneficial effect of saffron (Crocus sativus L. aqueous extract (SAE on the 1-Methyl-3-nitro-1-nitrosoguanidine (MNNG-induced gastric cancer in rat was investigated. Materials and Methods: MNNG was used to induce gastric cancer and then, different concentrations of SAE were administered to rats. After sacrificing, the stomach tissue was investigated by both pathologist and flow cytometry, and several biochemical parameters was determined in the plasma (or serum and stomach of rats. Results: Pathologic data indicated the induction of cancer at different stages from hyperplasia to adenoma in rats; and the inhibition of cancer progression in the gastric tissue by SAE administration; so that, 20% of cancerous rats treated with higher doses of SAE was completely normal at the end of experiment and there was no rat with adenoma in the SAE treated groups. In addition, the results of the flow cytometry/ propidium iodide staining showed that the apoptosis/proliferation ratio was increased due to the SAE treatment of cancerous rats. Moreover, the significantly increased serum LDH and decreased plasma antioxidant activity due to cancer induction fell backwards after treatment of rats with SAE. But changes in the other parameters (Ca2+, tyrosine kinase activity and carcino-embryonic antigen were not significant. Conclusion: SAE inhibits the progression of gastric cancer in rats, in a dose dependent manner.

  12. Quantum Chemical and Molecular Dynamics Study of the Coordination of Th(IV) in Aqueous Solvent

    International Nuclear Information System (INIS)

    In this work, we investigate the solvation of tetravalent thorium Th(IV) in aqueous solution using classical molecular dynamics simulations at the 10 ns scale and based on polarizable force-field approaches, which treat explicitly the covalent character of the metal-water interaction (and its inherent cooperative character). We have carried out a thorough analysis of the accuracy of the ab initio data that we used to adjust the force-field parameters. In particular, we show that large atomic basis sets combined with wave function based methods (such as the MP2 level) have to be preferred to density functional theory when investigating Th(IV)/water aggregates in gas phase. The information extracted from trajectories in solution shows a well structured Th(IV) first hydration shell formed of 8.25 ± 0.2 water molecules and located at about 2.45 ± 0.02 Angstroms and a second shell of 17.5±0.5 water molecules at about 4.75 Angstroms. Concerning the first hydration sphere, our results correspond to the lower bounds of experimental estimates (which range from 8 to 12.7); however, they are in very good agreement with the average of existing experimental data, 2.45 ± 0.02 Angstroms. All our results demonstrate the predictable character of the proposed approach, as well as the need of accounting explicitly for the cooperative character of charge-transfer phenomena affecting the Th(IV)/water interaction to build up reliable and accurate force-field approaches devoted to such studies. (authors)

  13. Quantum chemical and molecular dynamics study of the coordination of Th(IV) in aqueous solvent.

    Science.gov (United States)

    Réal, Florent; Trumm, Michael; Vallet, Valérie; Schimmelpfennig, Bernd; Masella, Michel; Flament, Jean-Pierre

    2010-12-01

    In this work, we investigate the solvation of tetravalent thorium Th(IV) in aqueous solution using classical molecular dynamics simulations at the 10 ns scale and based on polarizable force-field approaches, which treat explicitly the covalent character of the metal-water interaction (and its inherent cooperative character). We have carried out a thorough analysis of the accuracy of the ab initio data that we used to adjust the force-field parameters. In particular, we show that large atomic basis sets combined with wave function-based methods (such as the MP2 level) have to be preferred to density functional theory when investigating Th(IV)/water aggregates in gas phase. The information extracted from trajectories in solution shows a well-structured Th(IV) first hydration shell formed of 8.25 ± 0.2 water molecules and located at about 2.45 ± 0.02 Å and a second shell of 17.5 ± 0.5 water molecules at about 4.75 Å. Concerning the first hydration sphere, our results correspond to the lower bounds of experimental estimates (which range from 8 to 12.7); however, they are in very good agreement with the average of existing experimental data, 2.45 ± 0.02 Å. All our results demonstrate the predictable character of the proposed approach, as well as the need of accounting explicitly for the cooperative character of charge-transfer phenomena affecting the Th(IV)/water interaction to build up reliable and accurate force-field approaches devoted to such studies. PMID:21070066

  14. Hyphenation of sequential- and flow injection analysis with FTIR-spectroscopy for chemical analysis in aqueous solutions

    Science.gov (United States)

    Lendl, B.; Schindler, R.; Kellner, R.

    1998-06-01

    A survey of the principles of sequential (SIA)-and flow injection analysis (FIA) systems with FTIR spectroscopic detection is presented to introduce these hyphenations as powerful techniques for performing chemical analysis in aqueous solution. The strength of FIA/SIA-FTIR systems lies in the possibility to perform highly reproducible and automated sample manipulations such as sample clean-up and/or chemical reactions prior to spectrum acquisition. It is shown that the hyphenation of FIA/SIA systems with an FTIR spectrometer enhances the problem solving capabilities of the FTIR spectrometer as also parameters which can not be measured directly (e.g. enzyme activities) can be determined. On the other hand application of FTIR spectroscopic detection in FIA or SIA is also of advantage as it allows to shorten conventional analysis procedures (e.g. sucrose or phosphate analysis) or to establish and apply a multivariate calibration model for simultaneous determinations (e.g. glucose, fructose and sucrose analysis). In addition to these examples two recent instrumental developments in miniaturized FIA/SIA-FTIR systems, a μ-Flow through cell based on IR fiber optics and a micromachined SI-enzyme reactor are presented in this paper.

  15. Radium removal from aqueous solutions by adsorption on non-treated and chemically modified biomass by-product

    International Nuclear Information System (INIS)

    The adsorption efficiency of a biomass by-product (olive cake) regarding the removal of radium (226Ra) from aqueous solutions has been investigated prior and after its chemical treatment. The chemical treatment of the biomass by-product included phosphorylation and MnO2-coating. The separation/removal efficiency has been studied as a function of pH, salinity (NaCl) and calcium ion concentration (Ca2+) in solution. Evaluation of the experimental data shows clearly that the phosphorylated biomass by-product presents the highest adsorption capacity and efficiency followed by the MnO2-coated material and the non-treated biomass by-product. However, regarding the effect of salinity and the presence of competitive cations (e.g. Ca2+) on the adsorption/removal efficiency, the MnO2-coated material shows the lowest decline in efficiency (only 2 % of the relative adsorption efficiency) followed by the non-treated and the phosphorylated biomass by-product. The results of the present study indicate that depending on the physicochemical characteristics of the radium-contaminated water, all three types of the biomass by-product could be effectively used for the treatment of radium-contaminated waters. Nevertheless, the MnO2-coated material is expected to be the most effective adsorbent and an alternative to MnO2 resins for the treatment of environmentally relevant waters. (author)

  16. Chemical surface deposition of cds thin films from CdI2 aqueous solution

    Directory of Open Access Journals (Sweden)

    G. Il’chuk

    2009-01-01

    Full Text Available For the first time using CdI2 solution CdS films on glass and ITO coated glass substrates were produced by the method of layerwise chemical surface deposition (ChSD. CdS thin films with the widths from 40 nm to 100 nm were obtained for windows in solar cells based on CdS/CdTe heterojunctions. Changes of the structural and optical properties of CdS films due to air annealing are shown.

  17. Chemically and biologically modified activated carbon sorbents for the removal of lead ions from aqueous media.

    Science.gov (United States)

    Mahmoud, Mohamed E; Abdel-Fattah, Tarek M; Osman, Maher M; Ahmed, Somia B

    2012-01-01

    A method is described for hybridization of the adsorption and biosorption characteristics of chemically treated commercial activated carbon and baker's yeast, respectively, for the formation of environmental friendly multifunctional sorbents. Activated carbon was loaded with baker's yeast after acid-base treatment. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) Spectroscopy were used to characterize these sorbents. Moreover, the sorption capabilities for lead (II) ions were evaluated. A value of 90 μmol g(-1) was identified as the maximum sorption capacity of activated carbon. Acid-base treatment of activated carbon was found to double the sorption capacity (140-180 μmol g(-1)). Immobilization of baker's yeast on the surface of activated carbon sorbents was found to further improve the sorption capacity efficiency of lead to 360, 510 and 560 μmol g(-1), respectively. Several important factors such as pH, contact time, sorbent dose, lead concentration and interfering ions were examined. Lead sorption process was studied and evaluated by several adsorption isotherms and found to follow the Langmuir and BET models. The potential applications of various chemically and biologically modified sorbents and biosorbents for removal of lead from real water matrices were also investigated via multistage micro-column technique and the results referred to excellent recovery values of lead (95.0-99.0 ± 3.0-5.0 %).

  18. Identification of chemical contamination in an aqueous sample using liquid chromatography with mass spectrometry during 2nd NATO mixed samples laboratory exercise

    International Nuclear Information System (INIS)

    Biological and radiological screening was conducted to determine the type of biological and radiological contamination for a sample and the reference sample. Biological screening confirmed the presence of biological contamination. Radiological screening confirmed the presence of 235U. Preliminary chemical screening military confirmed the presence of volatile chemicals (chemical warfare agents, CWA), but refute the presence of non-volatile CWA and their degradation products and precursors (1,2,3 directory Organization for the Prohibition of Chemical Weapons, OPCW). To carry out further analysis it was necessary to adjust the aqueous sample so that it minimizes the possibility of radiological contamination, while maintaining chemical contamination. To remove 235U from the water sample for selective extraction of chemical contamination SCX cartridges (strong cation exchange) by solid phase extraction were used. To identify chemical contamination (from the list of substances 1, 2, 3 OPCW) GC-MS and LC-MS were used. LC-ESI-MS analysis has demonstrated the presence of unknown substance designated as Chemical A in an aqueous sample. LC-ESI-MS chromatograms of the reference sample, water sample and standard were compared. Unknown substance was identified on the basis of the correlation of retention times and MS spectra of unknown substance Chemical A and standard such as triethanolamine (TEA, a breakdown product of nitrogen mustard - HN3 fabric from the list 3B17Y OPCW).

  19. Identification of chemical contamination in an aqueous sample using liquid chromatography with mass spectrometry during 2nd NATO mixed samples laboratory exercise

    International Nuclear Information System (INIS)

    Biological and radiological screening was conducted on a sample and reference sample to determine the type of biological and radiological contamination. Biological screening confirmed the presence of biological contamination. Radiological screening confirmed the presence of 235U. Preliminary chemical military screening confirmed the presence of volatile chemicals (chemical warfare agents, CWA), but refute the presence of non-volatile CWA and their degradation products and precursors (1,2,3 directory Organization for the Prohibition of Chemical Weapons, OPCW). To carry out further analysis it was necessary to adjust aqueous sample so that it minimizes the possibility of radiological contamination, while maintaining chemical contamination. To remove of 235U from the water sample for selective extraction of chemical contamination by solid phase extraction (solid phase extraction - SPE) using SCX (strong cation exchange) cartridges were used. To identify chemical contamination (from the list of substances 1, 2, 3 OPCW) GC-MS and LC-MS were used. LC-ESI-MS analysis has demonstrated the presence of an unknown substance designated as Chemical A in an aqueous sample. LC-ESI-MS chromatograms of the reference sample, water sample and standard were compared. Unknown substance has been identified on the basis of the correlation of retention times and MS spectra of unknown substances - chemical A and standard such as triethanolamine (TEA, a breakdown product of nitrogen mustard - HN3 fabric from the list 3B17Y OPCW).

  20. Effect of solid and aqueous extract of vermicompost on growth characteristics of tomato and greenhouse whitefly (Trialeurodes vaporariorum

    Directory of Open Access Journals (Sweden)

    A. Peimani Foroushani

    2016-09-01

    Full Text Available Considering the increase of using vermicompost fertilizers in greenhouse cultivation, effect of vermicompost application on growth characteristics of tomato and one of its major pests [greenhouse whitefly, Trialeurodes vaporariorum (Hem:Aleyrodidae] was investigated. The experiment consisted of five treatments: control (without vermicompost, 30% and 60% solid vermicompost fertilizer, and 40% and 20% aqueous extracts of vermicompost. Effect of vermicompost on greenhouse whitefly was tested for two different cases of with-choice and no-choice. Results showed that significant increase in shoot dry weight and root dry weight of tomato in vermicompost treatments. The highest increase (18 and 12 fold, respectively was observed in plants treated with 60% solid vermicompost. The highest amount of nitrogen (0.43 mg/kg, potassium (14.56 mg/kg and phenol (1130.46 ppm was recorded in60% solid vermicompost treatment. Also, application of vermicompost reduced the percentage of infested leaves to whitefly, such that the lowest amounts were 6.67% and 8.97% in 60% and 30% solid vermicompost treatments, respectively, and 10.53% in 40% aqueous extract of vermicompost. The mortality of the second instar nymph of greenhouse whitefly-the stage that insects become fixed to the leaves by their sucking mouthparts- was increased (about 10% by application of  vermicompost.

  1. Aqueous and organic extracts of Trigonellafoenum-graecum L. Inhibit the mycelia growth of fungi

    Institute of Scientific and Technical Information of China (English)

    R. HAOUALA; S. HAWALA; A. EL-AYEB; R. KHANFIR; N. BOUGHANMI

    2008-01-01

    Aqueous extracts from various plant parts of fenugreek (3%) (aerial parts: leaves and stems (LS), roots (R), ground seeds (GS) and not ground seeds (NGS)) and petroleum ether, ethyl acetate and methanolic fractions of the aerial parts were assayed to determine their antifungal potential against Botrytis cinema, Fusarium graminearum, Alternaria sp., Pythium aphanidermatum, and Rhizoctinia solani. All fenugreek plant parts showed antifungal potential and the magnitude of their inhibitory effects was species and plant parts dependent. R extract was shown less toxic (30.38%), whereas NGS extract expressed the strongest inhibition, with an average of 71.44%, followed by GS (58.56%) and LS (57.1%). Screening indicated that P. aphanidermatum was the most resistant species, with an average inhibition of 34.5%. E graminearum, Alternaria sp. and R. solani were the most sensitive species, and were similarly inhibited (63.5%). The stability test indicated that the aqueous extracts of all plant parts lost approximately 50% of their relative activity after one month of storage at 4℃, whilst they lost 60%-90% of their activity when stored at ambient temperature for one month. The antifungal activity resided mainly in the methanol fraction and the minimum inhibitory concentration (MIC) of methanol fraction witch caused total inhibition of R. solani and Alternaria sp. was 60 μg/ml. Results of current study suggested that the constituents of Trigonella foenum-graecum have potential against harmful pathogenic fungi. Therefore, fenugreek could be an important source of biologically active compounds useful for developing better new antifungal drugs.

  2. Edge-controlled growth and kinetics of single-crystal graphene domains by chemical vapor deposition

    OpenAIRE

    Ma, Teng; Ren, Wencai; Zhang, Xiuyun; Liu, Zhibo; Gao, Yang; Yin, Li-Chang; Ma, Xiu-Liang; Ding, Feng; Cheng, Hui-Ming

    2013-01-01

    Controlled synthesis of wafer-sized single crystalline high-quality graphene is a great challenge of graphene growth by chemical vapor deposition because of the complicated kinetics at edges that govern the growth process. Here we report the synthesis of single-crystal graphene domains with tunable edges from zigzag to armchair via a growth–etching–regrowth process. Both growth and etching of graphene are strongly dependent on the edge structure. This growth/etching behavior is well explained...

  3. Removal of heavy metals from aqueous phases using chemically modified waste Lyocell fiber.

    Science.gov (United States)

    Bediako, John Kwame; Wei, Wei; Kim, Sok; Yun, Yeoung-Sang

    2015-12-15

    In this study, an outstanding performance of chemically modified waste Lyocell for heavy metals treatment is reported. The sorbent, which was prepared by a simple and concise method, was able to bind heavy metals such as Pb(II), Cu(II) and Cd(II), with very high efficiencies. The binding mechanisms were studied through adsorption and standard characterization tests such as scanning electron microscopy, energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analyses. Adsorption kinetics was very fast and attained equilibrium within 5 min in all metals studied. The maximum single metal uptakes were 531.29±0.28 mg/g, 505.64±0.21 mg/g, and 123.08±0.26 mg/g for Pb(II), Cd(II) and Cu(II), respectively. In ternary metal systems, Cu(II) selectivity was observed and the underlying factors were discussed. The sorbent by its nature, could be very effective in treating large volumes of wastewater with the contact of very little amount.

  4. Kirkwood-Buff Integrals for Aqueous Urea Solutions Based upon the Quantum Chemical Electrostatic Potential and Interaction Energies.

    Science.gov (United States)

    Chiba, Shuntaro; Furuta, Tadaomi; Shimizu, Seishi

    2016-08-11

    Cosolvents, such as urea, affect protein folding and binding, and the solubility of solutes. The modeling of cosolvents has been facilitated significantly by the rigorous Kirkwood-Buff (KB) theory of solutions, which can describe structural thermodynamics over the entire composition range of aqueous cosolvent mixtures based only on the solution density and the KB integrals (KBIs), i.e., the net excess radial distribution functions from the bulk. Using KBIs to describe solution thermodynamics has given rise to a clear guideline that an accurate prediction of KBIs is equivalent to accurate modeling of cosolvents. Taking urea as an example, here we demonstrate that an improvement in the prediction of KBIs comes from an improved reproduction of high-level quantum chemical (QC) electrostatic potential and molecular pairwise interaction energies. This rational approach to the improvement of the KBI prediction stems from a comparison of existing force fields, AMOEBA, and the generalized AMBER force field, as well as the further optimization of the former to enable better agreement with QC interaction energies. Such improvements would pave the way toward a rational and systematic determination of the transferable force field parameters for a number of important small molecule cosolvents. PMID:27434200

  5. A phantom study on bladder and rectum dose measurements in brachytherapy of cervix cancer using FBX aqueous chemical dosimeter.

    Science.gov (United States)

    Bansal, Anil K; Semwal, Manoj K; Arora, Deepak; Sharma, D N; Julka, P K; Rath, G K

    2013-06-01

    The ferrous sulphate-benzoic acid-xylenol orange (FBX) chemical dosimeter, due to its aqueous form can measure average volume doses and hence may overcome the limitations of point dosimetry. The present study was undertaken to validate the use of FBX dosimeter for rectum and bladder dose measurement during intracavitary brachytherapy (ICBT) and transperineal interstitial brachytherapy (TIB). We filled cylindrical polypropylene tubes (PT) and Foley balloons (FB) with FBX solution and used them as substitutes for rectum and bladder dose measurements respectively. A water phantom was fabricated with provision to place the Fletcher-type ICBT and MUPIT template applicators, and FBX filled PT and FB within the phantom. The phantom was then CT scanned for treatment planning and subsequent irradiation. Our results show that the average difference between DVH derived dose value and FBX measured dose is 3.5% (PT) and 13.7% (FB) for ICBT, and 9% (PT) and 9.9% (FB) for TIB. We believe that the FBX system should be able to provide accuracy and precision sufficient for routine quality assurance purposes. The advantage of the FBX system is its water equivalent composition, average volume dose measuring capability, and energy and temperature independent response as compared to TLD or semiconductor dosimeters. However, detailed studies will be needed with regards to its safety before actual in-vivo dose measurements are possible with the FBX dosimeter. PMID:22687710

  6. Effects of Aqueous Solutions on the Slow Crack Growth of Soda-Lime-Silicate Glass

    Science.gov (United States)

    Hausmann, Bronson D.; Salem, Jonathan A.

    2016-01-01

    The slow crack growth (SCG) parameters of soda-lime-silicate were measured in distilled and saltwater of various concentrations in order to determine if the presence of salt and the contaminate formation of a weak sodium film affects stress corrosion susceptibility. Past research indicates that solvents affect the rate of crack growth; however, the effects of salt have not been studied. The results indicate a small but statistically significant effect on the SCG parameters A and n at high concentrations; however, for typical engineering purposes, the effect can be ignored.

  7. A chemical probe technique for the determination of reactive halogen species in aqueous solution: Part 2 – chloride solutions and mixed bromide/chloride solutions

    Directory of Open Access Journals (Sweden)

    C. Anastasio

    2006-02-01

    Full Text Available Although reactive halogen species (X*=X●, ●X2−, X2 and HOX, where X=Br, Cl, or I are important environmental oxidants, relatively little is known about their kinetics in condensed phases such as seawater and sea-salt particles. Here we describe a new technique to determine reactive chlorine and bromine species in aqueous solutions by using allyl alcohol (CH2=CHCH2OH as a chemical probe. This probe is combined with competition kinetics in order to determine steady state concentrations of X*(aq. In some cases the technique also can be used to determine the rates of formation and lifetimes of X* in aqueous solution. In a companion paper we reported the results of our method development for aqueous solutions containing only bromide (Br−. In this paper, we discuss method development for solutions containing chloride (Cl− alone, and for solutions containing both bromide and chloride.

  8. Growth and shape transformations of giant phospholipid vesicles upon interaction with an aqueous oleic acid suspension

    CERN Document Server

    Peterlin, Primoz; Kogej, Ksenija; Svetina, Sasa; Walde, Peter

    2009-01-01

    The interaction of two types of vesicle systems was investigated: micrometer-sized, giant unilamellar vesicles (GUVs) formed from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and submicrometer-sized, large unilamellar vesicles (LUVs) formed from oleic acid and oleate, both in a buffered aqueous solution (pH=8.8). Individual POPC GUVs were transferred with a micropipette into a suspension of oleic acid/oleate LUVs, and the shape changes of the GUVs were monitored using optical microscopy. The behavior of POPC GUVs upon transfer into a 0.8 mM suspension of oleic acid, in which oleic acid/oleate forms vesicular bilayer structures, was qualitatively different from the behavior upon transfer into a 0.3 mM suspension of oleic acid/oleate, in which oleic acid/oleate is predominantly present in the form of monomers and possibly non-vesicular aggregates. In both cases, changes in vesicle morphology were observed within tens of seconds after the transfer. Vesicle initially started to evaginate. In 60% of the...

  9. Growth and properties of few-layer graphene prepared by chemical vapor deposition

    OpenAIRE

    Park, Hye Jin; Meyer, Jannik; Roth, Siegmar; Skakalova, Viera

    2009-01-01

    The structure, and electrical, mechanical and optical properties of few-layer graphene (FLG) synthesized by chemical vapor deposition (CVD) on a Ni coated substrate were studied. Atomic resolution transmission electron microscope (TEM) images show highly crystalline single layer parts of the sample changing to multilayer domains where crystal boundaries are connected by chemical bonds. This suggests two different growth mechanisms. CVD and carbon segregation participate in the growth process ...

  10. STUDIES ON FOLIAR APPLICATION OF GROWTH REGULATORS AND CHEMICALS ON SEEDLING GROWTH OF MANGO VARIETIES

    Directory of Open Access Journals (Sweden)

    B. M. MULALIDHARA

    2014-03-01

    Full Text Available A field experiment was carried out to study the effect of foliar application of growth regulators and chemicals on seedling growth of mango varieties. Among the varieties used Bappakkai recorded the maximum seedling height (30.4 cm, girth (0.83 cm, number of leaves (15.0, leaf area (460.4 cm2, fresh weight (36.55 g, dry weight (14.38 g, internode elongation (4.49 cm and per cent of graftable seedlings (86.6 % and minimum was in variety Olour (22.3 cm, 0.62 cm, and 13.9, 196.2 cm2, 15.86 g, 5.62 g, 4.49 cm and 39.1 % respectively. Among the treatments, the maximum plant height (32.1 cm, intermodal length (9.26 cm and dry weight (11.57 g was recorded in GA3 300 ppm while the other treatment nitrophoska 0.2 per cent noticed maximum leaf area (408.5 cm2 and fresh weight (30.25 g. The number of leaves (16.4, stem girth (0.78 cm and per cent of graftable seedlings (73.3 % was maximum in benzyl adenine 50 ppm, GA3 200 ppm and benzyl adenine 75 ppm respectively and minimum was noticed in control. In interaction the variety Bappakkai seedlings sprayed with GA3 300 ppm recorded maximum plant height (35.9 cm, girth (0.93 cm and per cent of graftable seedlings (100 % whereas Bappakkai seedlings sprayed with GA3 200 ppm noticed maximum fresh (48.7 g and dry weight (18.2 g and the Olour seedlings sprayed with benzyl adenine 50 ppm and GA3 300 ppm recorded the maximum number of leaves (18.0 and intermodal length (9.46 cm respectively. The GA3 200 and 300 ppm spray helps to obtain more graftable seedlings in the varieties Olour and Bappakai respectively.

  11. Chemical strategies for the presentation and delivery of growth factors

    NARCIS (Netherlands)

    Cabanas Danés, Jordi; Huskens, Jurriaan; Jonkheijm, Pascal

    2014-01-01

    Since the first demonstration of employing growth factors (GFs) to control cell behaviour in vitro, the spatiotemporal availability of GFs in vivo has received continuous attention. In particular, the ability to physically confine the mobility of GFs has been used in various tissue engineering appli

  12. Insights into Aqueous-phase processing through Comparison of the Organic Chemical Composition of Atmospheric Particles and Cloud Water in the Southeast United States

    Science.gov (United States)

    Boone, E.; Laskin, J.; Laskin, A.; Wirth, C.; Shepson, P. B.; Stirm, B. H.; Pratt, K.

    2014-12-01

    Organic compounds comprise a significant mass fraction of submicron atmospheric particles with considerable contribution from secondary organic aerosol (SOA), a large fraction of which is formed from the oxidation of biogenic volatile organic compounds. Aqueous-phase reactions in particles and cloud droplets are suggested to increase SOA mass and change the chemical composition the particles following cloud evaporation. Aqueous-phase processing may also explain discrepancies between measurements and models. To gain a better understanding of these processes, cloud water and below-cloud atmospheric particles were collected onboard a research aircraft during the Southeast Oxidants and Aerosol Study (SOAS) over Alabama in June 2013. Nanospray desorption electrospray ionization (nano-DESI) and direct electrospray ionization (ESI) coupled with high resolution mass spectrometry were utilized to compare the organic molecular composition of the particle and cloud water samples, respectively. Several hundred unique compounds have been identified in the particle and cloud water samples, allowing possible aqueous-phase reactions to be examined. Hydrolysis of organosulfate compounds, aqueous-phase formation of nitrogen-containing compounds, and possible fragmentation of oligomeric compounds will be discussed, with comparisons to previous laboratory studies. This study provides insights into aqueous-phase reactions in ambient cloud droplets.

  13. Phase Characterization of Cucumber Growth: A Chemical Gel Model

    Directory of Open Access Journals (Sweden)

    Bo Li

    2016-01-01

    Full Text Available Cucumber grows with complex phenomena by changing its volume and shape, which is not fully investigated and challenges agriculture and food safety industry. In order to understand the mechanism and to characterize the growth process, the cucumber is modeled as a hydrogel in swelling and its development is studied in both preharvest and postharvest stages. Based on thermodynamics, constitutive equations, incorporating biological quantities, are established. The growth behavior of cucumber follows the classic theory of continuous or discontinuous phase transition. The mechanism of bulged tail in cucumber is interpreted by phase coexistence and characterized by critical conditions. Conclusions are given for advances in food engineering and novel fabrication techniques in mechanical biology.

  14. Density-controlled growth of well-aligned ZnO nanowires using chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Well-aligned ZnO nanowires were grown on Si substrate by chemical vapor deposition.The experimental results showed that the density of nanowires was related to the heating process and growth temperature.High-density ZnO nanowires were obtained under optimal conditions.The growth mechanism of the ZnO nanowires was presented as well.

  15. Graphene growth with giant domains using chemical vapor deposition

    OpenAIRE

    Yong, Virginia; Hahn, H. Thomas

    2011-01-01

    We report the first demonstration of the growth of giant graphene domains on platinum (Pt), which results in a uniform bilayer graphene film with domain sizes of millimetre scale. These giant graphene domains are attributed to the giant Pt grains attained in post-deposition annealed Pt thin films that exhibit a strong dependency on the Pt film thickness. Giant grains have been claimed to occur in other metallic materials under appropriate film thicknesses and processing conditions. Our findin...

  16. Simple growth patterns can create complex trajectories for the ontogeny of constitutive chemical defences in seaweeds.

    Directory of Open Access Journals (Sweden)

    Nicholas A Paul

    Full Text Available All of the theory and most of the data on the ecology and evolution of chemical defences derive from terrestrial plants, which have considerable capacity for internal movement of resources. In contrast, most macroalgae--seaweeds--have no or very limited capacity for resource translocation, meaning that trade-offs between growth and defence, for example, should be localised rather than systemic. This may change the predictions of chemical defence theories for seaweeds. We developed a model that mimicked the simple growth pattern of the red seaweed Asparagopsis armata which is composed of repeating clusters of somatic cells and cells which contain deterrent secondary chemicals (gland cells. To do this we created a distinct growth curve for the somatic cells and another for the gland cells using empirical data. The somatic growth function was linked to the growth function for defence via differential equations modelling, which effectively generated a trade-off between growth and defence as these neighbouring cells develop. By treating growth and defence as separate functions we were also able to model a trade-off in growth of 2-3% under most circumstances. However, we found contrasting evidence for this trade-off in the empirical relationships between growth and defence, depending on the light level under which the alga was cultured. After developing a model that incorporated both branching and cell division rates, we formally demonstrated that positive correlations between growth and defence are predicted in many circumstances and also that allocation costs, if they exist, will be constrained by the intrinsic growth patterns of the seaweed. Growth patterns could therefore explain contrasting evidence for cost of constitutive chemical defence in many studies, highlighting the need to consider the fundamental biology and ontogeny of organisms when assessing the allocation theories for defence.

  17. Chemical Compositional Indications of Aqueous Alteration for Whitewater Lake Boxworks, Veneers and Veins at Cape York, Mars

    Science.gov (United States)

    Clark, Benton; Gellert, R.; Squyres, S.; Arvidson, R.; Yen, A.; Rice, J.; Athena Science Team

    2013-10-01

    An area of partially-veneered, flat-lying rocks which also includes boxwork and linear veins contains a variety of compositions which are each indicative of minor to major aqueous alteration processes in the Cape York rim of Endeavour Crater. As analyzed by APXS x-ray fluorescence spectroscopy, the sets of unique elemental compositions correspond variously to Al-Si rich clays in boxwork veins, with Fe- and Cl-enriched salt veneers (Esperance samples); swarms of Ca sulfate veins (Ortiz samples); and, as indicated by remote sensing, mafic smectite alteration products in veneers (Chelmsford covering Azilda samples). Multiple offset analyses by APXS reveal clear trends and associations of certain elements, allowing inferences of mineralogies. In contrast to the acidic environment deduced for the genesis of the multiple-sulfate Burns formation sediments and shallow ferric-rich sulfate deposits beneath soils, these alteration products formed at more near-neutral pH, often with major chemical segregations and requiring high water-rock ratios comparable to a wide range of eminently habitable terrestrial environments. Several of these compositions are also rated high with respect to their potential for preservation of organic materials and biomarkers. Within distances of just tens of meters inside this so-called Whitewater Lake unit, this broad diversity exemplifies the tantalizing opportunities as well as challenges for future sample return missions to the red planet, which in this case could also be expanded to include nearby samples of Burns Fm sandstones, hematite concretions, light-toned spherules (Kirkwood), large gypsum veins (Homestake), martian global soils and surface dust.

  18. Optimum synthesis conditions of nanometric Fe50Ni50 alloy formed by chemical reduction in aqueous solution

    Indian Academy of Sciences (India)

    Marwa A Mohamed; Azza H El-Maghraby; Mona M Abd El-Latif; Hassan A Farag

    2013-10-01

    In the present article, various nanometric Fe50Ni50 alloys were synthesized by chemical reduction of the corresponding metal ions, with hydrazine in an aqueous solution. Process variables of reaction temperature, pH of the hydrazine solution and concentration of metal ions were varied in order to determine the optimum synthesis conditions regarding quality, productivity and cost. It is found that pH of hydrazine solution, at low concentration of metal ions, is the most crucial variable affecting the reaction rate, average crystallite and particle sizes of the synthesized nanometric Fe50Ni50 alloy, followed by the total concentration of metal ions. Thus, increase of pH of hydrazine solution acts as an efficient stabilizer in reducing the particle size. On the contrary, at high concentration of metal ions, the structural characteristics of the nanometric Fe50Ni50 alloy are almost insensitive to reaction temperature and pH of hydrazine solution, but the reduction rate is remarkably sensitive to reaction temperature. Based on these results, it is decided that a reaction temperature of 80 °C, pH of the hydrazine solution of 12.5 and concentration of metal ions of 0.6 M represent the optimum synthesis conditions. The role of pH of hydrazine solution in reducing the alloy’s average particle size as well as efficient stabilizer confirms tremendous effect of synthesis conditions on the alloy structure and therefore, the importance of this study for industrial production of nanometric Fe50Ni50 alloy.

  19. Chronic uranium exposure and growth toxicity for phytoplankton. Dose-effect relationship: first comparison of chemical and radiological toxicity

    International Nuclear Information System (INIS)

    The bioavailability of uranium for freshwater organisms, as for other dissolved metals, is closely linked to chemical speciation in solution (U aqueous speciation undergoes tremendous changes in the presence of ligands commonly found in natural waters e.g. carbonate, phosphate, hydroxide and natural organic matter). For the studied chemical domain, short-term uranium uptake experiments have already shown that the free uranyl ion concentration [UO22+] is a good predictor of uranium uptake by the green algae Chlamydomonas reinhardtii, as predicted by the Free Ion Activity Model. In agreement with these results, acidic pH and low ligands concentrations in water enhance uranium bioavailability and consequently its potential chronic effects on phytoplankton. Moreover, uranium is known to be both radio-toxic and chemo-toxic. The use of different isotopes of uranium allows to expose organisms to different radiological doses for the same molar concentration: e.g. for a given element concentration (chemical dose), replacing depleted U by U-233 obviously leads to an enhanced radiological delivered dose to organisms (x104). In this work we established relationships between uranium doses (depleted uranium and 233-U ) and effect on the growth rate of the green algae Chlamydomonas reinhardtii. Uranium bioaccumulation was also monitored. Growth rate was measured both in classical batch (0-72 hrs) and continuous (turbidostat) cultures, the latter protocol allowing medium renewal to diminish exudates accumulation and speciation changes in the medium. The differences in effects will be, if possible, related to the development of defence mechanisms against the formation of reactive oxygen species (forms of glutathione) and the production of phyto-chelatins (small peptides rich in cystein that play an important role in the homeostasis and the detoxication of metals in cells). (author)

  20. Chronic uranium exposure and growth toxicity for phytoplankton. Dose-effect relationship: first comparison of chemical and radiological toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Gilbin, R.; Pradines, C.; Garnier-Laplace, J. [CEA Cadarache (DEI/SECRE/LRE), Laboratory of Radioecology and Ecotoxicology, Institute for Radioprotection and Nuclear Safety, 13 - Saint-Paul-lez-Durance (France)

    2004-07-01

    The bioavailability of uranium for freshwater organisms, as for other dissolved metals, is closely linked to chemical speciation in solution (U aqueous speciation undergoes tremendous changes in the presence of ligands commonly found in natural waters e.g. carbonate, phosphate, hydroxide and natural organic matter). For the studied chemical domain, short-term uranium uptake experiments have already shown that the free uranyl ion concentration [UO{sub 2}{sup 2+}] is a good predictor of uranium uptake by the green algae Chlamydomonas reinhardtii, as predicted by the Free Ion Activity Model. In agreement with these results, acidic pH and low ligands concentrations in water enhance uranium bioavailability and consequently its potential chronic effects on phytoplankton. Moreover, uranium is known to be both radio-toxic and chemo-toxic. The use of different isotopes of uranium allows to expose organisms to different radiological doses for the same molar concentration: e.g. for a given element concentration (chemical dose), replacing depleted U by U-233 obviously leads to an enhanced radiological delivered dose to organisms (x10{sup 4}). In this work we established relationships between uranium doses (depleted uranium and 233-U ) and effect on the growth rate of the green algae Chlamydomonas reinhardtii. Uranium bioaccumulation was also monitored. Growth rate was measured both in classical batch (0-72 hrs) and continuous (turbidostat) cultures, the latter protocol allowing medium renewal to diminish exudates accumulation and speciation changes in the medium. The differences in effects will be, if possible, related to the development of defence mechanisms against the formation of reactive oxygen species (forms of glutathione) and the production of phyto-chelatins (small peptides rich in cystein that play an important role in the homeostasis and the detoxication of metals in cells). (author)

  1. Template-free non-aqueous electrochemical growth of CdO nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Henriquez, R., E-mail: rodrigo.henriquez@ucv.cl [Instituto de Quimica, Facultad de Ciencias, Pontificia Universidad Catolica de Valparaiso, Casilla 4059, Valparaiso (Chile); Grez, P.; Munoz, E. [Instituto de Quimica, Facultad de Ciencias, Pontificia Universidad Catolica de Valparaiso, Casilla 4059, Valparaiso (Chile); Dalchiele, E.A.; Marotti, R.E. [Instituto de Fisica, Facultad de Ingenieria, Herrera y Reissig 565, C.C. 30, 11000 Montevideo (Uruguay); Gomez, H. [Instituto de Quimica, Facultad de Ciencias, Pontificia Universidad Catolica de Valparaiso, Casilla 4059, Valparaiso (Chile)

    2011-10-31

    The direct template-free synthesis and characterization of CdO nanorods (NRs) obtained through electrochemical reduction process of molecular oxygen (O{sub 2}) in a dimethylsulfoxide solution containing CdCl{sub 2}are reported. X-ray diffraction characterization of the NRs shows that the CdO phase was obtained without the presence of any other secondary phases. In agreement with the aspect ratio of a typical nanorod structure, CdO NRs presented average diameters of ca. 170 nm and average lengths of ca. 920 nm. Current results also demonstrate that the employed electrochemical synthesis route favors the growth of NRs with a preferred crystallographic orientation along the [200] axis direction. The synthesized CdO NRs exhibited a n-type semiconductor character with a donor carrier concentration of N{sub D} = 4.3 x 10{sup 19} cm{sup -3}.

  2. Calculation of liquid-liquid equilibrium of aqueous two-phase systems using a chemical-theory-based excess Gibbs energy model

    Directory of Open Access Journals (Sweden)

    Pessôa Filho P. A.

    2004-01-01

    Full Text Available Mixtures containing compounds that undergo hydrogen bonding show large deviations from ideal behavior. These deviations can be accounted for through chemical theory, according to which the formation of a hydrogen bond can be treated as a chemical reaction. This chemical equilibrium needs to be taken into account when applying stability criteria and carrying out phase equilibrium calculations. In this work, we illustrate the application of the stability criteria to establish the conditions under which a liquid-phase split may occur and the subsequent calculation of liquid-liquid equilibrium using a chemical-theory-modified Flory-Huggins equation to describe the non ideality of aqueous two-phase systems composed of poly(ethylene glycol and dextran. The model was found to be able to correlate ternary liquid-liquid diagrams reasonably well by simple adjustment of the polymer-polymer binary interaction parameter.

  3. SAFT缔合模型关联含水体系的1H NMR%Correlation of 1H NMR Chemical Shift for Aqueous Solutions by Statistical Associating Fluid Theory Association Model

    Institute of Scientific and Technical Information of China (English)

    许波; 李浩然; 王从敏; 许映杰; 韩世钧

    2005-01-01

    1H NMR chemical shifts of binary aqueous mixtures of acylamide, alcohol, dimethyl sulphoxide (DMSO), and acetone are correlated by statistical associating fluid theory (SAFT) association model. The comparison between SAFT association model and Wilson equation shows that the former is better for dealing with aqueous solutions. Finally, the specialties of both models are discussed.

  4. Effect of vapor-phase oxygen on chemical vapor deposition growth of graphene

    Science.gov (United States)

    Terasawa, Tomo-o.; Saiki, Koichiro

    2015-03-01

    To obtain a large-area single-crystal graphene, chemical vapor deposition (CVD) growth on Cu is considered the most promising. Recently, the surface oxygen on Cu has been found to suppress the nucleation of graphene. However, the effect of oxygen in the vapor phase was not elucidated sufficiently. Here, we investigate the effect of O2 partial pressure (PO2) on the CVD growth of graphene using radiation-mode optical microscopy. The nucleation density of graphene decreases monotonically with PO2, while its growth rate reaches a maximum at a certain pressure. Our results indicate that PO2 is an important parameter to optimize in the CVD growth of graphene.

  5. The chemical stability of L-isoleucine, L-threonine, and L-serine in aqueous solutions of KCl at 298.15 K

    Science.gov (United States)

    Roy, Sanjay; Dolui, Bijoy Krishna

    2016-06-01

    The experimental saturated solubilities of L-isoleucine, L-threonine, and L-serine in aqueous mixtures of a KCl solution at 298.15 K are presented in this article. The solubilities are measured by gravimetric method. In the present study the theoretical calculation of the standard transfer Gibbs free energy, cavity forming enthalpy of transfer, cavity forming transfer Gibbs free energy, dipole-dipole interaction effect have been computed. The chemical effects of the transfer Gibbs energies for the present amino acids have been obtained by subtracting the cavity effects and dipole-dipole interaction effects from the Δ G t 0 ( i). The stability of the experimental amino acids in aqueous KCl in terms of thermodynamic parameters is explained.

  6. Chemical stability of ecomustine, a new antitumor agent in aqueous and biological media as assessed by high-performance liquid chromatography.

    Science.gov (United States)

    el Abed, I; Roger, P; Gosse, C; Atassi, G; Gouyette, A

    1991-01-01

    Ecomustine, or CY233 (NSC-609224), is a new water-soluble nitrosoureido sugar derived from acosamine. A high-performance liquid chromatographic assay (HPLC) developed to quantify the unchanged drug in aqueous solutions and biological specimens enabled us to study the chemical stability as a function of pH, light, and temperature. In buffered aqueous solutions, the kinetics of degradation of CY233 is a first-order process. The log k-pH profile demonstrated hydroxide ion-catalyzed solvolysis. The drug is most stable at pH 4, more stable than some other nitrosoureas in 5% glucose (t1/2, 62-67 h) and in 0.9% isotonic saline (t1/2, 25-37 h) solutions. Based on these findings, blood samples should be collected in cold tubes (4 degrees C) containing citrate buffer (pH 4) and all manipulations should be protected from heat and light. PMID:1998985

  7. A model for the growth of cdte by metal organic chemical vapor deposition

    Science.gov (United States)

    Nemirovsky, Y.; Goren, D.; Ruzin, A.

    1991-10-01

    A kinetic model for the metalorganic chemical vapor deposition (MOCVD) growth of CdTe over a wide temperature range is presented. The model yields the growth rate as a function of the gas-phase concentrations of the constituents. The model is corroborated with experimental results obtained by the MOCVD growth of CdTe at 380° C. The major features of the model are the observed two-step surface-controlled pyrolysis and surface saturation, leading initially to a growth rate that increases with the square root of the concentrations of the reacting species and subsequently to a decrease of the growth rate as the concentrations increase. At even higher concentrations, an additional increase of growth rate is observed and modeled.

  8. A chemical pollen suppressant inhibits auxin-induced growth in maize coleoptile sections

    Energy Technology Data Exchange (ETDEWEB)

    Vesper, M.J. (Univ. of Dayton, OH (USA)); Cross, J.W. (Sogetal, Inc., Hayward, CA (USA))

    1990-05-01

    Chemical inhibitors of pollen development having a phenylcinnoline carboxylate structure were found to inhibit IAA- and 1-NAA-induced growth in maize coleoptile sections. The inhibitor (100 {mu}M) used in these experiments caused approx. 35% reduction in auxin-induced growth over the auxin concentration range of 0.3 to 100 {mu}M. Growth inhibition was noted as a lengthening of the latent period and a decrease in the rate of an auxin-induced growth response. An acid growth response to pH 5 buffer in abraded sections was not impaired. The velocity of basipetal transport of ({sup 3}H)IAA through the coleoptile sections also was not inhibited by the compound, nor was uptake of ({sup 3}H)IAA. Similarly, the inhibitor does not appear to alter auxin-induced H{sup +} secretion. We suggest that the agent targets some other process necessary for auxin-dependent growth.

  9. Metal Oxide Nanoparticle Growth on Graphene via Chemical Activation with Atomic Oxygen

    OpenAIRE

    Johns, James E.; Alaboson, Justice M. P.; Patwardhan, Sameer; Ryder, Christopher R.; Schatz, George C.; Hersam, Mark C.

    2013-01-01

    Chemically interfacing the inert basal plane of graphene with other materials has limited the development of graphene-based catalysts, composite materials, and devices. Here, we overcome this limitation by chemically activating epitaxial graphene on SiC(0001) using atomic oxygen. Atomic oxygen produces epoxide groups on graphene, which act as reactive nucleation sites for zinc oxide nanoparticle growth using the atomic layer deposition precursor diethyl zinc. In particular, exposure of epoxid...

  10. Chemical insights, explicit chemistry, and yields of secondary organic aerosol from OH radical oxidation of methylglyoxal and glyoxal in the aqueous phase

    Directory of Open Access Journals (Sweden)

    Y. B. Lim

    2013-09-01

    Full Text Available Atmospherically abundant, volatile water-soluble organic compounds formed through gas-phase chemistry (e.g., glyoxal (C2, methylglyoxal (C3, and acetic acid have great potential to form secondary organic aerosol (SOA via aqueous chemistry in clouds, fogs, and wet aerosols. This paper (1 provides chemical insights into aqueous-phase OH-radical-initiated reactions leading to SOA formation from methylglyoxal and (2 uses this and a previously published glyoxal mechanism (Lim et al., 2010 to provide SOA yields for use in chemical transport models. Detailed reaction mechanisms including peroxy radical chemistry and a full kinetic model for aqueous photochemistry of acetic acid and methylglyoxal are developed and validated by comparing simulations with the experimental results from previous studies (Tan et al., 2010, 2012. This new methylglyoxal model is then combined with the previous glyoxal model (Lim et al., 2010, and is used to simulate the profiles of products and to estimate SOA yields. At cloud-relevant concentrations (~ 10−6 − ~ 10−3 M; Munger et al., 1995 of glyoxal and methylglyoxal, the major photooxidation products are oxalic acid and pyruvic acid, and simulated SOA yields (by mass are ~ 120% for glyoxal and ~ 80% for methylglyoxal. During droplet evaporation oligomerization of unreacted methylglyoxal/glyoxal that did not undergo aqueous photooxidation could enhance yields. In wet aerosols, where total dissolved organics are present at much higher concentrations (~ 10 M, the major oxidation products are oligomers formed via organic radical–radical reactions, and simulated SOA yields (by mass are ~ 90% for both glyoxal and methylglyoxal. Non-radical reactions (e.g., with ammonium could enhance yields.

  11. Growth mechanism of a gas clathrate hydrate from a dilute aqueous gas solution: a molecular dynamics simulation of a three-phase system.

    Science.gov (United States)

    Nada, Hiroki

    2006-08-24

    A molecular dynamics simulation of a three-phase system including a gas clathrate, liquid water, and a gas was carried out at 298 K and high pressure in order to investigate the growth mechanism of the clathrate from a dilute aqueous gas solution. The simulation indicated that the clathrate grew on interfaces between the clathrate and the liquid water, after transfer of the gas molecules from the gas phase to the interfaces. The results suggest a two-step process for growth: first, gas molecules are arranged at cage sites, and second, H(2)O molecules are ordered near the gas molecules. The results also suggest that only the H(2)O molecules, which are surrounded or sandwiched by the gas molecules, form the stable polygons that constitute the cages of the clathrate. In addition, the growth of the clathrate from a concentrated aqueous gas solution was also simulated, and the results suggested a growth mechanism in which many H(2)O and gas molecules correctively form the structure of the clathrate. The clathrate grown from the concentrated solution contained some empty cages, whereas the formation of empty cages was not observed during the growth from the dilute solution. The results obtained by both simulations are compared with the results of an experimental study, and the growth mechanism of the clathrate in a real system is discussed.

  12. Estimation of octanol/water partition coefficient and aqueous solubility of environmental chemicals using molecular fingerprints and machine learning methods

    Science.gov (United States)

    Octanol/water partition coefficient (logP) and aqueous solubility (logS) are two important parameters in pharmacology and toxicology studies, and experimental measurements are usually time-consuming and expensive. In the present research, novel methods are presented for the estim...

  13. Evaluation of chemical parameters and ecotoxicity of a soil developed on gossan following application of polyacrylates and growth of Spergularia purpurea.

    Science.gov (United States)

    Santos, Erika S; Abreu, Maria Manuela; de Varennes, Amarilis; Macías, Felipe; Leitão, Sara; Cerejeira, Maria José

    2013-09-01

    The aim of this study was to evaluate the chemical characteristics and ecotoxicity of a mine soil developed on gossan materials and amended with hydrophilic polyacrylate polymers after a growth cycle of Spergularia purpurea. Different acute bioassays (Daphnia magna immobilization; microalgae growth inhibition; germination and growth of lettuce and oat) were carried out with simulated leachates, pore water and soil samples. The germination and growth of native shrubs (Cistus ladanifer and Lavandula sampaioana) were also evaluated in the lysimeters where S. purpurea had grown. The soil had high total concentrations (g/kg) of Al (3.50-8.60), As (2.55-2.73), Cu (0.13-0.91) and Pb (4.48-6.16). However, the percentages of elements in aqueous extracts (simulating leachates, pore water, and the conditions of the rhizosphere soil) were small when compared to their total soil concentrations (less than 9% except for Na in leachates). Growth of S. purpurea and other natural colonization of plant species (Poaceae, Fabaceae and Asteraceae families) improved chemical characteristics but the application of the polyacrylate polymers contributed to a further improvement of soil quality. However, this was not sufficient to ensure the growth of a large number of shrubs despite a great germination rate. Among the several species used on the ecotoxicological assessment, the D. magna test was the only bioassay that showed a clear toxicity of soil leachates, suggesting the importance of using several ecotoxicological tests to assess the environmental risk of soil contamination and its rehabilitation. Although the studied soil can be considered contaminated taking into account the total soil concentrations of Al, As, Cu and Pb, the low concentrations of the same chemical elements in extractable solutions, that simulated the fractions really available for organisms, did not demonstrate a substantial toxic effects in the organisms and, consequently, negative impact on the environment. PMID

  14. Growth characteristics of graphene synthesized via chemical vapor deposition using carbon tetrabromide precursor

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Taejin; Jung, Hanearl; Lee, Chang Wan [Nanodevice Laboratory, School of Electrical and Electronics Engineering, Yonsei University, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Mun, Ki-Yeung; Kim, Soo-Hyun [Nano-Devices and Process Laboratory, School of Materials Science and Engineering, Yeungnam University, Dae-Dong, Gyeongsan-Si 712-749 (Korea, Republic of); Park, Jusang [Nanodevice Laboratory, School of Electrical and Electronics Engineering, Yonsei University, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Kim, Hyungjun, E-mail: hyungjun@yonsei.ac.kr [Nanodevice Laboratory, School of Electrical and Electronics Engineering, Yonsei University, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of)

    2015-07-15

    Highlights: • Carbon tetrabromide (CBr{sub 4}) precursor and Cu foil can be used for chemical vapor deposition (CVD) of graphene. • High yield and controllable growth are possible via CVD used with a CBr{sub 4} precursor. • CBr{sub 4} precursor is a new alternative for use in the mass production of graphene. • Low bond dissociation energy of CBr{sub 4} allows lower temperature growth (800 °C) of high-quality graphene film, compared to that (1000 °C) of methane used CVD. - Abstract: A carbon tetrabromide (CBr{sub 4}) precursor was employed for the chemical vapor deposition (CVD) of graphene, and the graphene growth characteristics as functions of the following key factors were then investigated: growth time, growth temperature, and the partial pressure of the precursor. The graphene was transferred onto a SiO{sub 2}/Si substrate and characterized using transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy, and the electrical properties were measured through the fabrication of field-effect transistors. Our results show that high yield and controllable growth are possible via CVD used with a CBr{sub 4} precursor. Thus, CBr{sub 4} precursor is a new alternative candidate for use in the mass production of graphene.

  15. Growth characteristics of graphene synthesized via chemical vapor deposition using carbon tetrabromide precursor

    International Nuclear Information System (INIS)

    Highlights: • Carbon tetrabromide (CBr4) precursor and Cu foil can be used for chemical vapor deposition (CVD) of graphene. • High yield and controllable growth are possible via CVD used with a CBr4 precursor. • CBr4 precursor is a new alternative for use in the mass production of graphene. • Low bond dissociation energy of CBr4 allows lower temperature growth (800 °C) of high-quality graphene film, compared to that (1000 °C) of methane used CVD. - Abstract: A carbon tetrabromide (CBr4) precursor was employed for the chemical vapor deposition (CVD) of graphene, and the graphene growth characteristics as functions of the following key factors were then investigated: growth time, growth temperature, and the partial pressure of the precursor. The graphene was transferred onto a SiO2/Si substrate and characterized using transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy, and the electrical properties were measured through the fabrication of field-effect transistors. Our results show that high yield and controllable growth are possible via CVD used with a CBr4 precursor. Thus, CBr4 precursor is a new alternative candidate for use in the mass production of graphene

  16. Soybean yield and chemical attributes in soil after five-year surface application of slag, aqueous lime and sewage sludge

    OpenAIRE

    Büll, Leonardo Theodoro; Freitag, Elisa Eni; Corrêa, Juliano Corulli; Fernandes, Dirceu Maximino

    2008-01-01

    The agricultural use of industrial residues and sewage sludge in order to provide essential nutrients to a plant and soil liming, will be one of the most promising alternative options of soil fertilization and liming management in a very near future, as far as these applications follow the prevailing technical norms to prevent eventual environmental contamination. The aim of this study was to evaluate the effect of slag, aqueous lime, sewage sludge and limestone, under surface app...

  17. Adsorption of Hexavalent Chromium from Aqueous Solution Using Chemically Activated Carbon Prepared from Locally Available Waste of Bamboo (Oxytenanthera abyssinica)

    OpenAIRE

    Dula, Tamirat; Siraj, Khalid; Kitte, Shimeles Addisu

    2014-01-01

    This study reports on the adsorption of Hexavalent Chromium from aqueous solutions using activated carbon prepared from bamboo (Oxytenanthera abyssinica) waste by KOH activation heating in an electrical furnace at 1073 K for 3 hrs. Batch adsorption experiments were also carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage, and temperature of the solution. Kinetic studies of the data showed that the adsorption follows the pseudo-second-order k...

  18. Phyto-Chemical Evaluation and Anti-oxidant potentiality of Cycas beddomei Dyer Male cone aqueous Extract

    Directory of Open Access Journals (Sweden)

    Mahendra Nath Mitta

    2014-06-01

    Full Text Available Cycas beddomei Dyer, an endemic and critically endangered, tropical, dry deciduous, dioecious gymnosperm present in varied region of adjunct areas of Tirumala Hillocks, Seshachalam Biosphere Reserve, Eastern ghats, India. The objective of the study was to investigate antioxidant capacity of aqueous extracts of microsporophylls of male cones of Cycas beddomei. This study deals with the quantitative estimation of phytoconstituents viz., Total Phenolic Content (TPC, Total Flavonoid Content (TFC, Total Flavonols (TF, Total Proanthocyanidins (TPA, Extraction Yield (EY , Quantitative analysis soluble carbohydrates, Starch, Crude fibre, Proteins, Moisture, Ash and Mineral composition of aqueous extract of male cone of cycas beddomei has been carried out. Moreover, the assessment of antioxidant capacity by standard established calorimetric methods viz., DPPH assay, TAC and ABTS assay. Entire data has evaluated statistically. Results depicted High contents of TPC, TFC, TF and TPA and exerted anti-radical aptitude. Significant correlation has been found between quantities of phyto-constituents and anti-oxidant assays. With the results, it is confirmed that the logistics of aqueous cone extract of Cycas beddomei as potential anti-oxidant by evaluating the bioavailability of phytoconstituents and provided scientific base as a valuable natural antioxidant and therapeutic agent.

  19. Effect of molecular weight on radiation chemical degradation yield of chain scission of γ-irradiated chitosan in solid state and in aqueous solution

    International Nuclear Information System (INIS)

    Chitosan A1, A2 and A3 with molecular weight of 471, 207 and 100 kDa respectively, produced from squid pen chitin was degraded by gamma rays in the solid state and in aqueous solution with various doses in air at ambient temperature. Effect of molecular weight on radiation chemical degradation yield of chain scission and degradation rate constants of γ-irradiated chitosan in solid state and in aqueous solution was investigated. The radiation chemical degradation yield G(s) and degradation rate values were calculated. The molecular weight changes were monitored by capillary viscometry method and the chemical structure changes were followed by UV analysis. The results showed that, the degradation of chitosan was faster in solution, than in solid state. The values of G(s) in solid state and in aqueous solution were respectively 1.1×10−8 mol/J and 0.074×10−7 mol/J for A1, 4.42×10−8 mol/J and 0.28×10−7 mol/J for A2 and 6.08×10−8 mol/J and 0.38×10−7 mol/J for A3. Degradation rate constants values ranged from 0.41×10−5 to 2.1×10−5 kGy−1 in solid state, whereas in solution they ranged from 13×10−5 to 68×10−5 kGy−1. The chitosan A3 was more sensitive to radiolysis than A1 and A2. The chain scission yield, G(s) and degradation rate constants seems to be greatly influenced by the initial molecular weight of the chitosan. Structural changes in irradiated chitosan are revealed by the apparition of absorption peaks at 261 and 295 nm, which could be attributed to the formation of carbonyl groups. In both conditions the peak intensity was higher in chitosan A3 than in A1 and A2, the oxidative products decreased with increasing molecular weight of chitosan. - Highlights: ► We investigated the effects of MW on G(s) value of γ-irradiated chitosan in solid and aqueous state. ► Chitosan with low molecular weight was more sensitive to radiolysis than high molecular weight. ► G(s) value and degradation rate seems to be greatly influenced by the

  20. Quantum chemical analysis of the energy of proton transfer from phenol and chlorophenols to H2O in the gas phase and in aqueous solution

    Science.gov (United States)

    Schüürmann, Gerrit

    1998-12-01

    Proton transfer energies of phenol and 14 chlorophenols with H2O as a base are analyzed in the gas phase and in solution using quantum chemical methods at the semiempirical and ab initio level of computation. The effect of aqueous solution was accounted for by applying the density functional theory (DFT) implementation of the conductor-like screening model (COSMO) as well as semiempirical continuum-solvation models. The results reveal substantial and systematic overestimations of the free energies of proton transfer as derived from experimental solution-phase pKa data. This can be traced back to both deficiencies in the current model parameterization as well as to limitations of the underlying gas-phase quantum chemical models, which is further illustrated by additional complete-basis-set (CBS) calculations for the proton transfer reaction with phenol. In contrast, the relative pKa trend is reflected well by COSMO-DFT calculations with correlation coefficients (adjusted for degrees of freedom) of 0.96. Decomposition of the dissociation energy in aqueous solution into a gas-phase term and a term summarizing the solvation contributions provides new insights into the effect of solvation on proton transfer energies, and yields mechanistic explanations for the observed differences in the gas-phase and solution-phase acidity orders of various subgroups of the compounds.

  1. Allelopathic influence of aqueous extracts from the leaves of Morus alba L. on seed germination and seedling growth of Cucumis sativus L. and Sinapsis alba L.

    Directory of Open Access Journals (Sweden)

    Katarzyna Możdżeń

    2014-04-01

    Full Text Available The aim of the present study was to elucidate impact of the aqueous extracts from leaves of Morus alba L. on germination, growth and photosynthetic activity of Cucumis sativus L. and Sinapis alba L. Plants were grown for 21 days at the temperature 25°C (day and 18°C (night, within 12/12 hours photoperiod, light intensity 150 μmol·m-2·s-1 and relative humidity 60-70% (day/night. Our experiments proved that allelopathic compounds in aqueous extracts of the leaves M. alba at high concentrations, reduce power and energy of germination. Biometric analysis of seedlings and adult plants grown showed that allelopathic substances have stimulating or inhibiting function depending on the stage of treatment. Moreover, they cause changes in chlorophyll contents and activity of photosystem II (PS II.

  2. Effect of Gamma Rays and Salinity on Growth and Chemical Composition of Ambrosia maritima L. Plant

    International Nuclear Information System (INIS)

    This work achieved to study the effects of, mixture of salt 2:2:1 (Na Cl-CaCl2 and Mg SO4), concentration of (0, 2000, 4000 and 6000 ppm). on growth characters, some chemical components and some active ingredients in shoots of Ambrosia maritima plants, at different stages of growth, during two seasons. Pots 30 cm in diameter were filled of sand-loamy soils in appropriate concentration, all pots were irrigated with tap water. The exposed damsisa seeds to gamma rays, doses (0, 20, 40, and 80 Gy) before sowing together with control non irradiated seeds were sown in saline soils (0, 2000, 4000 and 6000 ppm). Soil salinity treatments caused a decrease in plant height, number of leaves, content of damsin, and an increase in fresh weigh, dry weight, total sugars, total chlorophyll, amino acids and ambrosine content. Also, Gamma rays caused an increase in most of growth parameters and most of chemical composition. It was observed that 40 or 80 Gy was more effective. We investigated the combined effect of levels of salinity and doses of radiation used, this interference improve growth parameters and chemical composition in ambrosia maritima plants and caused ascertain the role of gamma irradiation in plants tolerance to soil salinity and alleviation their harmful effect on plants.

  3. Modeling of Scale-Dependent Bacterial Growth by Chemical Kinetics Approach

    Directory of Open Access Journals (Sweden)

    Haydee Martínez

    2014-01-01

    Full Text Available We applied the so-called chemical kinetics approach to complex bacterial growth patterns that were dependent on the liquid-surface-area-to-volume ratio (SA/V of the bacterial cultures. The kinetic modeling was based on current experimental knowledge in terms of autocatalytic bacterial growth, its inhibition by the metabolite CO2, and the relief of inhibition through the physical escape of the inhibitor. The model quantitatively reproduces kinetic data of SA/V-dependent bacterial growth and can discriminate between differences in the growth dynamics of enteropathogenic E. coli, E. coli  JM83, and Salmonella typhimurium on one hand and Vibrio cholerae on the other hand. Furthermore, the data fitting procedures allowed predictions about the velocities of the involved key processes and the potential behavior in an open-flow bacterial chemostat, revealing an oscillatory approach to the stationary states.

  4. Effects of growth pressure on morphology of ZnO nanostructures by chemical vapor transport

    Science.gov (United States)

    Babu, Eadi Sunil; Kim, Sungjin; Song, Jung-Hoon; Hong, Soon-Ku

    2016-08-01

    The effect of growth pressure on the morphology of the ZnO nanostructures in chemical vapor transport by using Zn powder and oxygen as source materials has been investigated. Highly uniform aligned ZnO nanorods or multifaceted tripod structures were grown depending on the growth pressure. The mechanism governing the morphology change was explained by the relative concentration of Zn vapor and supersaturation based on experimental observations. It was concluded that heterogeneous nucleation on the substrate is enhanced at low growth pressure, while homogeneous nucleation from vapor phase is enhanced at high growth pressure. The difference resulted in different morphology of ZnO nanostructures. ZnO nanorods grown at optimized condition were used for the fabrication of gas sensor for the detection of H2 gas.

  5. Spiral growth of few-layer MoS2 by chemical vapor deposition

    Science.gov (United States)

    Dong, X.; Yan, C.; Tomer, D.; Li, C. H.; Li, L.

    2016-08-01

    Growth spirals exhibit appealing properties due to a preferred layer stacking and lack of inversion symmetry. Here, we report spiral growth of MoS2 during chemical vapor deposition on SiO2/Si and epitaxial graphene/SiC substrates, and their physical and electronic properties. We determine the layer-dependence of the MoS2 bandgap, ranging from 2.4 eV for the monolayer to a constant of 1.3 eV beyond the fifth layer. We further observe that spirals predominantly initiate at the step edges of the SiC substrate, based on which we propose a growth mechanism driven by screw dislocation created by the coalescence of two growth fronts at steps.

  6. Growth and characterization of the ZnO/ZnS bilayer obtained by chemical spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, M.C. [Laboratorio de Materiales y Superficie (Unidad Asociada al CSIC), Dptos Fisica Aplicada and Dpto Ingenieria Quimica, Facultad de Ciencias, Universidad de Malaga, E29071 Malaga (Spain); Espinos, J.P. [Instituto de Ciencias de Materiales de Sevilla (CSIC), Avda. Americo Vespucio s/n, E41092 Sevilla (Spain); Leinen, D.; Martin, F. [Laboratorio de Materiales y Superficie (Unidad Asociada al CSIC), Dptos Fisica Aplicada and Dpto Ingenieria Quimica, Facultad de Ciencias, Universidad de Malaga, E29071 Malaga (Spain); Centeno, S.P. [Departamento de Quimica-Fisica, Facultad de Ciencias, Universidad de Malaga, E29071 Malaga (Spain); Romero, R. [Laboratorio de Materiales y Superficie (Unidad Asociada al CSIC), Dptos Fisica Aplicada and Dpto Ingenieria Quimica, Facultad de Ciencias, Universidad de Malaga, E29071 Malaga (Spain); Ramos-Barrado, J.R. [Laboratorio de Materiales y Superficie (Unidad Asociada al CSIC), Dptos Fisica Aplicada and Dpto Ingenieria Quimica, Facultad de Ciencias, Universidad de Malaga, E29071 Malaga (Spain)], E-mail: barrado@uma.es

    2008-12-30

    ZnO/ZnS bilayer antireflection coatings have been prepared by spray pyrolysis using aqueous solutions of zinc acetate and thiourea or zinc chloride and thiourea. The structure, surface morphology, chemical composition and optical transmittance of the bilayer have been examined as a function of the composition of the initial solution. X-ray photoelectron spectroscopy analysis and Ar ion-beam sputter etching was carried out to obtain a depth profile of bilayer. Neither carbon nor other by-products, which could alter the optical transmittance of the bilayer were found in either the interface or bulk. The differences between the bilayers arise from the annealing of the ZnS underlayer, as well as the precursor used to prepare it.

  7. Influence of chemical liquids on the fatigue crack growth of the AZ31 magnesium alloy

    Science.gov (United States)

    Wang, Zhang-Zhong; He, Xian-Cong; Bai, Yun-Qiang; Ba, Zhi-Xin; Dai, Yu-Ming; Zhou, Heng-Zhi

    2012-03-01

    The fatigue crack growth behavior of an AZ31 magnesium alloy was investigated by comparing the effect of zirconate and phosphate chemical liquids. The morphology, components, and phase compositions of the chemical depositions at the fatigue crack tip were analyzed by employing scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD), respectively. For samples with and without the chemical liquids, their stress-intensity factor values at the fatigue crack tip were compared by using a stress-strain gauge. The results demonstrated that a zirconate film (Zr x O y ·Zn x O y ) and a phosphate film (Zn3(PO4)2·4H2O and MgZnP2O7) could be formed on the fatigue crack-surface at the fatigue crack tip. The stress distribution was changed because of the chemical depositions and the causticity of the chemical liquids. This could decrease the stress-intensity factor value and thus effectively cause fatigue crack closure, which reduces the fatigue crack growth rate. Moreover, it was found that the fatigue crack closure effect of zirconates was more positive than that of phosphates.

  8. Time variant layer control in atmospheric pressure chemical vapor deposition based growth of graphene

    KAUST Repository

    Qaisi, Ramy M.

    2013-04-01

    Graphene is a semi-metallic, transparent, atomic crystal structure material which is promising for its high mobility, strength and transparency - potentially applicable for radio frequency (RF) circuitry and energy harvesting and storage applications. Uniform (same number of layers), continuous (not torn or discontinuous), large area (100 mm to 200 mm wafer scale), low-cost, reliable growth are the first hand challenges for its commercialization prospect. We show a time variant uniform (layer control) growth of bi- to multi-layer graphene using atmospheric chemical vapor deposition system. We use Raman spectroscopy for physical characterization supported by electrical property analysis. © 2013 IEEE.

  9. Collaborative Project: Understanding the Chemical Processes tat Affect Growth rates of Freshly Nucleated Particles

    Energy Technology Data Exchange (ETDEWEB)

    McMurry, Peter [Univ. of Minnesota, Minneapolis, MN (United States); Smuth, James [University Corporation for Atmospheric Research, Irvine, CA (United States)

    2015-11-12

    This final technical report describes our research activities that have, as the ultimate goal, the development of a model that explains growth rates of freshly nucleated particles. The research activities, which combine field observations with laboratory experiments, explore the relationship between concentrations of gas-phase species that contribute to growth and the rates at which those species are taken up. We also describe measurements of the chemical composition of freshly nucleated particles in a variety of locales, as well as properties (especially hygroscopicity) that influence their effects on climate.

  10. Laser-chemical modification of nucleation barriers for area-selective thin film growth

    Science.gov (United States)

    Tsao, J. Y.; Ehrlich, D. J.

    1984-09-01

    The use of laser radiation to locally modify nucleation barriers to thin film growth is discussed. Examples are described in which UV laser photodeposition is used to directly pattern surface-altering monolayer or submonolayer films. The surface-altering films can then be used to promote or both physical condensation as well as surface chmistry. A qualitative is made of two kinds of processes: those relying on physical, and those relying on chemical, barriers. A figure of merit is defined and discussed, which measures the selectivity of a given process for patterned growth.

  11. Size-dependent mobility of gold nano-clusters during growth on chemically modified graphene

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Gavin R., E-mail: gavin.bell@warwick.ac.uk; Dawson, Peter M.; Pandey, Priyanka A.; Wilson, Neil R. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Mulheran, Paul A. [Department of Chemical and Process Engineering, University of Strathclyde, James Weir Building, 75 Montrose St., Glasgow G1 1XJ (United Kingdom)

    2014-01-01

    Gold nano-clusters were grown on chemically modified graphene by direct sputter deposition. Transmission electron microscopy of the nano-clusters on these electron-transparent substrates reveals an unusual bimodal island size distribution (ISD). A kinetic Monte Carlo model of growth incorporating a size-dependent cluster mobility rule uniquely reproduces the bimodal ISD, providing strong evidence for the mobility of large clusters during surface growth. The cluster mobility exponent of −5/3 is consistent with cluster motion via one-dimensional diffusion of gold atoms around the edges of the nano-clusters.

  12. Growth of 2D black phosphorus film from chemical vapor deposition

    Science.gov (United States)

    Smith, Joshua B.; Hagaman, Daniel; Ji, Hai-Feng

    2016-05-01

    Phosphorene, a novel 2D material isolated from bulk black phosphorus (BP), is an intrinsic p-type material with a variable bandgap for a variety of applications. However, these applications are limited by the inability to isolate large films of phosphorene. Here we present an in situ chemical vapor deposition type approach that demonstrates progress towards growth of large area 2D BP with average areas >3 μm2 and thicknesses representing samples around four layers and thicker samples with average areas >100 μm2. Transmission electron microscopy and Raman spectroscopy have confirmed successful growth of 2D BP from red phosphorus.

  13. Growth of 2D black phosphorus film from chemical vapor deposition.

    Science.gov (United States)

    Smith, Joshua B; Hagaman, Daniel; Ji, Hai-Feng

    2016-05-27

    Phosphorene, a novel 2D material isolated from bulk black phosphorus (BP), is an intrinsic p-type material with a variable bandgap for a variety of applications. However, these applications are limited by the inability to isolate large films of phosphorene. Here we present an in situ chemical vapor deposition type approach that demonstrates progress towards growth of large area 2D BP with average areas >3 μm(2) and thicknesses representing samples around four layers and thicker samples with average areas >100 μm(2). Transmission electron microscopy and Raman spectroscopy have confirmed successful growth of 2D BP from red phosphorus. PMID:27087456

  14. Size-dependent mobility of gold nano-clusters during growth on chemically modified graphene

    Directory of Open Access Journals (Sweden)

    Gavin R. Bell

    2014-01-01

    Full Text Available Gold nano-clusters were grown on chemically modified graphene by direct sputter deposition. Transmission electron microscopy of the nano-clusters on these electron-transparent substrates reveals an unusual bimodal island size distribution (ISD. A kinetic Monte Carlo model of growth incorporating a size-dependent cluster mobility rule uniquely reproduces the bimodal ISD, providing strong evidence for the mobility of large clusters during surface growth. The cluster mobility exponent of −5/3 is consistent with cluster motion via one-dimensional diffusion of gold atoms around the edges of the nano-clusters.

  15. Combined effects of ionising gamma radiation and some chemical substances on the Allium sativum growth

    International Nuclear Information System (INIS)

    Co 60 - gamma ionising radiations act in different doses and flows on Allium sativum. They accelerate the germination of bulblets with a couple of days by comparison with the sample. The 10 Gy dose stimulates the plants growth. The 30 Gy dose or 'shock dose' related to the radiation flow and with chemicals used in the treatment, produces strong decays or raises of biological parameter values. The growth region which is implied in growing regulators synthesis is perturbed. The calculation of nuclear and cytoplasmic volumes of nucleus-cytoplasm ratio confirms the perturbation at this level. (Author)

  16. Effects of aqueous leaf extracts of Populus tomentosa at different ages on the growth and photosynthetic characteristics of its own seedlings

    Institute of Scientific and Technical Information of China (English)

    Meiqiu ZHU; Ying WANG; Bingxiang LIU; Lili ZHANG; Hui WANG; Yuxin YUAN; Kejiu DU

    2009-01-01

    Through the outdoor potted plant trials, the allelopathic potential of Populus tomentosa was tested against its species in the growth, chlorophyll content, and photosynthetic and chlorophyll fluorescence characteristics with aqueous extracts (0.01,0.02,0.05, and 0.1 g · mL-1) obtained from leaves at different individual ages (1, 20, and 45 years old). The results showed that seedling height, basal diameter, fresh and dry weights, quantity of chlorophyll, the ratio of chlorophyll a/b, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), efficiency of primary conversion of light energy of PSII (Fv/Fm), potential activity of PSII (Fv/Fo), and photochemical quenching (qP) of the seedlings gradually decreased with the increase of extract concentration of all three ages when compared with the controls. The older the P. tomentosa used for extract preparation, the greater the percentage declined in the aforementioned parameters. Moreover, at the four concentrations used, there was a significant difference between treatments with the extracts from 1- and 45-year-old plants (except for qP), but occasionally, the effects were not obvious between the 1-and the 20-year-old plants, or the 20- and 45-year-old plants. The intercellular CO2 concentration (Ci) treated with the extracts from the 1-year-old decreased at the lowest concentration, whereas it increased at higher concentrations. The C, treated with aqueous leaf extracts from the 20-year-old decreased at the lower concentrations and increased to similar levels to that of the control at the higher concentrations. C, was always close to control levels in 45-year-old extract treatments. All the aqueous leaf extracts of P. tomentosa at all ages caused an increase of the initial fluorescence (Fo). The older P. tomentosa used for the preparation of aqueous leaf extracts caused a greater percentage decline in Fo. The nonphotochemical quenching (qN) increased significantly at lower concentrations of

  17. Kinetic measurements and quantum chemical calculations on low spin Ni(II)/(III) macrocyclic complexes in aqueous and sulphato medium

    Indian Academy of Sciences (India)

    Anuradha Sankaran; E J Padma Malar; Venkatapuram Ramanujam Vijayaraghavan

    2015-07-01

    Cu(II) ion catalyzed kinetics of oxidation of H2O2 by [NiIIIL2] (L2 = 1,8-bis(2-hydroxyethyl)-1,3,6,8,10,13-hexaazacyclotetradecane) was studied in aqueous acidic medium in the presence of sulphate ion. The rate of oxidation of H2O2 by [NiIIIL2] is faster than that by [NiIIIL1] (L1 = 1,4,8,11-tetraazacyclote-tradecane) in sulphate medium. DFT calculations at BP86/def2-TZVP level lead to different modes of bonding between [NiL]II/III and water ligands (L = L1 and L2). In aqueous medium, two water molecules interact with [NiL]II through weak hydrogen bonds with L and are tilted by ∼23° from the vertical axis forming the dihydrate [NiL]2+.2H2O. However, there is coordinate bond formation between [NiL1]III and two water molecules in aqueous medium and an aqua and a sulphato ligand in sulphate medium leading to the octahedral complexes [NiL1(H2O)2]3+ and [NiL1(SO4)(H2O)]+. In the analogous [NiL2]III, the water molecules are bound by hydrogen bonds resulting in [NiL2]3+.2H2O and [NiL2(SO4)]+.H2O. As the sulphato complex [NiL2(SO4)]+.H2O is less stable than [NiL1(SO4)(H2O)]+ in view of the weak H-bonding interactions in the former it can react faster. Thus the difference in the mode of bonding between Ni(III) and the water ligand can explain the rate of oxidation of H2O2 by [NiIIIL] complexes.

  18. Probing the solvent shell with 195Pt chemical shifts: density functional theory molecular dynamics study of Pt(II) and Pt(IV) anionic complexes in aqueous solution.

    Science.gov (United States)

    Truflandier, Lionel A; Autschbach, Jochen

    2010-03-17

    Ab initio molecular dynamics (aiMD) simulations based on density functional theory (DFT) were performed on a set of five anionic platinum complexes in aqueous solution. (195)Pt nuclear magnetic shielding constants were computed with DFT as averages over the aiMD trajectories, using the two-component relativistic zeroth-order regular approximation (ZORA) in order to treat relativistic effects on the Pt shielding tensors. The chemical shifts obtained from the aiMD averages are in good agreement with experimental data. For Pt(II) and Pt(IV) halide complexes we found an intermediate solvent shell interacting with the complexes that causes pronounced solvent effects on the Pt chemical shifts. For these complexes, the magnitude of solvent effects on the Pt shielding constant can be correlated with the surface charge density. For square-planar Pt complexes the aiMD simulations also clearly demonstrate the influence of closely coordinated non-equatorial water molecules on the Pt chemical shift, relating the structure of the solution around the complex to the solvent effects on the metal NMR chemical shift. For the complex [Pt(CN)(4)](2-), the solvent effects on the Pt shielding constant are surprisingly small. PMID:20166712

  19. Chemically modified olive stone: A low-cost sorbent for heavy metals and basic dyes removal from aqueous solutions

    International Nuclear Information System (INIS)

    In the present work, we have investigated the sorption efficiency of treated olive stones (TOS) towards cadmium and safranine removal from their respective aqueous solutions. TOS material was prepared by treatment of olive stones with concentrated sulfuric acid at room temperature followed up by a subsequent neutralization with 0.1 M NaOH aqueous solution. The resulting material has been thoroughly characterized by SEM, energy-dispersive X-ray (EDX), MAS 13C NMR, FTIR and physicochemical parameters were calculated. The sorption study of TOS at the solid-liquid interface was investigated using kinetics, sorption isotherms, pH effect and thermodynamic parameters. The preliminary results indicate that TOS exhibit a better efficiency in terms of sorption capacities toward the two pollutants (128.2 and 526.3 mg/g for cadmium and safranine, respectively) than those reported so far in the literature. Moreover, the sorption process is ascertained to occur fast enough so that the equilibrium is reached in less than 15 min of contact time. The results found in the course of this study suggest that ion exchange mechanism is the most appropriate mechanism involved in cadmium and safranine removal. Finally, the sorption efficiency of TOS is compared to those of other low-cost sorbents materials yet described in the literature

  20. Growth of ZnO Single Crystal by Chemical Vapor Transport Method

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    ZnO crystals were grown by CVT method in closed quartz tube under seeded condition. Carbon was used as a transport agent to enhance the chemical transport of ZnO in the growth process. ZnO single crystals were grown by using GaN/sapphire and GaN/Si wafer as seeds. The property and crystal quality of the ZnO single crystals was studied by photoluminescence spectroscopy and X-ray diffraction technique.

  1. Evaluation of different chemical preservatives to control Zygosaccharomyces rouxii growth in high sugar culture media

    OpenAIRE

    Rojo, María Cecilia; Arroyo López, Francisco Noé; Lerena, M. C.; Mercado, Laura A.; Torres, Álvaro; Combina, M.

    2014-01-01

    © 2014 Elsevier Ltd. Zygosaccharomyces rouxii is an osmophilic yeast responsible for a large amount of economic loss in high sugar food production. Statistical modelling techniques were used in the present study to assess the individual effects of different chemical preservatives (potassium sorbate, sodium benzoate, dimethyldicarbonate, vanillin, ferulic, p-coumaric and caffeic acids) to control the growth of a cocktail of five yeast strains belonging to this species and isolated from spoilt ...

  2. Rapid and highly efficient growth of graphene on copper by chemical vapor deposition of ethanol

    Energy Technology Data Exchange (ETDEWEB)

    Lisi, Nicola, E-mail: nicola.lisi@enea.it [ENEA, Materials Technology Unit, Surface Technology Laboratory, Casaccia Research Centre, Via Anguillarese 301, 00123 Rome (Italy); Buonocore, Francesco; Dikonimos, Theodoros; Leoni, Enrico [ENEA, Materials Technology Unit, Surface Technology Laboratory, Casaccia Research Centre, Via Anguillarese 301, 00123 Rome (Italy); Faggio, Giuliana; Messina, Giacomo [Dipartimento di Ingegneria dell' Informazione, delle Infrastrutture e dell' Energia Sostenibile (DIIES), Università “Mediterranea” di Reggio Calabria, 89122 Reggio Calabria (Italy); Morandi, Vittorio; Ortolani, Luca [CNR-IMM Bologna, Via Gobetti 101, 40129 Bologna (Italy); Capasso, Andrea [ENEA, Materials Technology Unit, Surface Technology Laboratory, Casaccia Research Centre, Via Anguillarese 301, 00123 Rome (Italy)

    2014-11-28

    The growth of graphene by chemical vapor deposition on metal foils is a promising technique to deliver large-area films with high electron mobility. Nowadays, the chemical vapor deposition of hydrocarbons on copper is the most investigated synthesis method, although many other carbon precursors and metal substrates are used too. Among these, ethanol is a safe and inexpensive precursor that seems to offer favorable synthesis kinetics. We explored the growth of graphene on copper from ethanol, focusing on processes of short duration (up to one min). We investigated the produced films by electron microscopy, Raman and X-ray photoemission spectroscopy. A graphene film with high crystalline quality was found to cover the entire copper catalyst substrate in just 20 s, making ethanol appear as a more efficient carbon feedstock than methane and other commonly used precursors. - Highlights: • Graphene films were grown by fast chemical vapor deposition of ethanol on copper. • High-temperature/short-time growth produced highly crystalline graphene. • The copper substrate was entirely covered by a graphene film in just 20 s. • Addition of H{sub 2} had a negligible effect on the crystalline quality.

  3. Surface morphology stabilization by chemical sputtering in carbon nitride film growth

    Energy Technology Data Exchange (ETDEWEB)

    Buijnsters, J G [Institute for Molecules and Materials (IMM), Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen (Netherlands); Vazquez, L [Instituto de Ciencia de Materiales de Madrid (CSIC), C/Sor Juana Ines de la Cruz 3, 28049 Madrid (Spain)

    2008-01-07

    We have studied the influence of chemical sputtering effects on the morphology of carbon nitride films grown on silicon substrates by electron cyclotron resonance chemical vapour deposition. This study has been performed by comparing the evolution of their morphology with that of hydrogenated amorphous carbon films grown under similar conditions, where these effects are not present. When chemical sputtering effects operate we observe a film surface stabilization for length scales in the 60-750 nm range after a threshold roughness of about 3-4 nm has been developed. This stabilization is explained on the basis of the re-emission of nitrogen etching species, which is confirmed by growth experiments on microstructured substrates. (fast track communication)

  4. On the Growth and Microstructure of Carbon Nanotubes Grown by Thermal Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Handuja Sangeeta

    2010-01-01

    Full Text Available Abstract Carbon nanotubes (CNTs were deposited on various substrates namely untreated silicon and quartz, Fe-deposited silicon and quartz, HF-treated silicon, silicon nitride-deposited silicon, copper foil, and stainless steel mesh using thermal chemical vapor deposition technique. The optimum parameters for the growth and the microstructure of the synthesized CNTs on these substrates are described. The results show that the growth of CNTs is strongly influenced by the substrate used. Vertically aligned multi-walled CNTs were found on quartz, Fe-deposited silicon and quartz, untreated silicon, and on silicon nitride-deposited silicon substrates. On the other hand, spaghetti-type growth was observed on stainless steel mesh, and no CNT growth was observed on HF-treated silicon and copper. Silicon nitride-deposited silicon substrate proved to be a promising substrate for long vertically aligned CNTs of length 110–130 μm. We present a possible growth mechanism for vertically aligned and spaghetti-type growth of CNTs based on these results.

  5. What are the active carbon species during graphene chemical vapor deposition growth?

    Science.gov (United States)

    Shu, Haibo; Tao, Xiao-Ming; Ding, Feng

    2015-02-01

    The dissociation of carbon feedstock is a crucial step for understanding the mechanism of graphene chemical vapor deposition (CVD) growth. Using first-principles calculations, we performed a comprehensive theoretical study for the population of various active carbon species, including carbon monomers and various radicals, CHi (i = 1, 2, 3, 4), on four representative transition-metal surfaces, Cu(111), Ni(111), Ir(111) and Rh(111), under different experimental conditions. On the Cu surface, which is less active, the population of CH and C monomers at the subsurface is found to be very high and thus they are the most important precursors for graphene CVD growth. On the Ni surface, which is more active than Cu, C monomers at the subsurface dominate graphene CVD growth under most experimental conditions. In contrast, on the active Ir and Rh surfaces, C monomers on the surfaces are found to be very stable and thus are the main precursors for graphene growth. This study shows that the mechanism of graphene CVD growth depends on the activity of catalyst surfaces and the detailed graphene growth process at the atomic level can be controlled by varying the temperature or partial pressure of hydrogen.

  6. Growth temperature dependence of partially Fe filled MWCNT using chemical vapor deposition

    Science.gov (United States)

    Sengupta, Joydip; Jacob, Chacko

    2009-12-01

    This investigation deals with the effect of growth temperature on the growth behavior of Fe filled multi-walled carbon nanotubes (MWCNTs). Carbon nanotube (CNT) synthesis was carried out in a thermal chemical vapor deposition (CVD) reactor in the temperature range 650-950 °C using propane as the carbon source, Fe as the catalyst material, and Si as the catalyst support. Atomic force microscopy (AFM) analysis of the catalyst exhibits that at elevated temperature clusters of catalyst coalesce and form macroscopic islands. Field emission scanning electron microscopy (FESEM) results show that with increased growth temperature the average diameter of the nanotubes increases but their density decreases. High-resolution transmission electron microscopy (HRTEM) studies suggest that the nanotubes have multi-walled structure with partial Fe filling for all growth temperatures. The X-ray diffraction (XRD) pattern of the grown materials indicates that they are graphitic in nature. The characterization of nanotubes by Raman spectroscopy reveals that the optimized growth temperature for Fe filled CNTs is 850 °C, in terms of quality. A simple model for the growth of Fe filled carbon nanotubes is proposed.

  7. Final Report: "Collaborative Project. Understanding the Chemical Processes That Affect Growth Rates of Freshly Nucleated Particles"

    Energy Technology Data Exchange (ETDEWEB)

    Smith, James N. [NCAR, Boulder, CO (United States); McMurry, Peter H. [NCAR, Boulder, CO (United States)

    2015-11-12

    This final technical report describes our research activities that have, as the ultimate goal, the development of a model that explains growth rates of freshly nucleated particles. The research activities, which combine field observations with laboratory experiments, explore the relationship between concentrations of gas-phase species that contribute to growth and the rates at which those species are taken up. We also describe measurements of the chemical composition of freshly nucleated particles in a variety of locales, as well as properties (especially hygroscopicity) that influence their effects on climate. Our measurements include a self-organized, DOE-ARM funded project at the Southern Great Plains site, the New Particle Formation Study (NPFS), which took place during spring 2013. NPFS data are available to the research community on the ARM data archive, providing a unique suite observations of trace gas and aerosols that are associated with the formation and growth of atmospheric aerosol particles.

  8. Effect of nitrogen and fish manure fertilization on growth and chemical composition of lettuce

    Science.gov (United States)

    Yildirim, Ertan; Kul, Raziye; Turan, Metin; Ekinci, Melek; Alak, Gonca; Atamanalp, Muhammet

    2016-04-01

    Present experiment was designed to determine the response of various dozes of fish manure (FM) and commercial fertilizers on plant growth, yield and nutrient content of lettuce. The treatments consisted of fish manure, commercial fertilizer and the combination of fish manure and commercial fertilizer with four dozes of nitrogen (0 kg/ha, 100 kg/ha, 150 kg/ha and 200 kg/ha). The results of the study showed that treatments significantly affected the growth and chemical characteristics of lettuce. The best results in regard to plant growth and yield were obtained from 100 and 150 kg kg/ha nitrogen dozes of the combination of fish manure and commercial fertilizer.

  9. Controlling nucleation of monolayer WSe2 during metal-organic chemical vapor deposition growth

    Science.gov (United States)

    Eichfeld, Sarah M.; Oliveros Colon, Víctor; Nie, Yifan; Cho, Kyeongjae; Robinson, Joshua A.

    2016-06-01

    Tungsten diselenide (WSe2) is a semiconducting, two-dimensional (2D) material that has gained interest in the device community recently due to its electronic properties. The synthesis of atomically thin WSe2, however, is still in its infancy. In this work we elucidate the requirements for large selenium/tungsten precursor ratios and explain the effect of nucleation temperature on the synthesis of WSe2 via metal-organic chemical vapor deposition (MOCVD). The introduction of a nucleation-step prior to growth demonstrates that increasing nucleation temperature leads to a transition from a Volmer-Weber to Frank-van der Merwe growth mode. Additionally, the nucleation step prior to growth leads to an improvement of WSe2 layer coverage on the substrate. Finally, we note that the development of this two-step technique may allow for improved control and quality of 2D layers grown via CVD and MOCVD processes.

  10. CdS thin films growth by ammonia free chemical bath deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Jaber, A.Y.; Alamri, S.N.; Aida, M.S., E-mail: aida_salah2@yahoo.fr

    2012-02-29

    Cadmium Sulfide CdS thin films were deposited by chemical bath deposition technique using ethanolamine as complexing agent instead of commonly used ammonia to avoid its toxicity and volatility during film preparation. In order to investigate the film growth mechanism samples were prepared with different deposition times. A set of substrates were dropped in the same bath and each 30 minutes a sample is withdrawn from the bath, by this way all the obtained films were grown in the same condition. The films structure was analyzed by X rays diffraction. In early stage of growth the obtained films are amorphous, with increasing the deposition time, the films exhibits a pure hexagonal structure with (101) preferential orientation. The film surface morphology was studied by atomic force microscopy. From these observations we concluded that the early growth stage starts in the 3D Volmer-Weber mode, followed by a transition to the Stransky-Krastanov mode with increasing deposition time. The critical thickness of this transition is 120 nm. CdS quantum dots were formed at end of the film growth. The optical transmittance characterization in the UV-Visible range shows that the prepared films have a high transparency ranging from 60 to 80% for photons having wavelength greater than 600 nm. - Highlights: Black-Right-Pointing-Pointer CdS thin films are deposited by ammonia-free chemical bath deposition. Black-Right-Pointing-Pointer Films have hexagonal structure with (101) preferential orientation. Black-Right-Pointing-Pointer Growth begins in the Volmer-Weber mode and changes to the Stransky-Krastanov mode. Black-Right-Pointing-Pointer CdS quantum dots are formed in the late stage of growth.

  11. Comparison between Chemical Senses Thresholds for Capsaicin and Dihydrocapsaicin in Aqueous Solutions and Identification of the Area of Burning Sensation

    Directory of Open Access Journals (Sweden)

    D.J. Schneider

    2014-01-01

    Full Text Available In the present study, the pungency detection thresholds for capsaicin and dihydrocapsaicin in aqueous solutions containing an emulsifier (polysorbate 80 were determined and compared. Thresholds were measured for 21 students (12 chili “users” and 9 “non users” using a 3-Alternative Forced Choice sensory test with ascending concentrations of capsaicin and dihydrocapsaicin (0.025, 0.045, 0.090, 0.180 and 0.360 ppm, respectively. In addition, the panelists were asked where the irritation occurred (throat, tongue or both. The group Best Estimate Thresholds were 0.080 and 0.049 ppm for capsaicin and dihydrocapsaicin, respectively and differed significantly. Chili “users” and “non users” did not differ significantly in their perception of capsaicin and dihydrocapsaicin, suggesting that no desensitization effects occur. In accordance with previous studies, in most cases the first irritation was experienced in the throat.

  12. Standard Gibbs free energies of reactions of ozone with free radicals in aqueous solution: quantum-chemical calculations.

    Science.gov (United States)

    Naumov, Sergej; von Sonntag, Clemens

    2011-11-01

    Free radicals are common intermediates in the chemistry of ozone in aqueous solution. Their reactions with ozone have been probed by calculating the standard Gibbs free energies of such reactions using density functional theory (Jaguar 7.6 program). O(2) reacts fast and irreversibly only with simple carbon-centered radicals. In contrast, ozone also reacts irreversibly with conjugated carbon-centered radicals such as bisallylic (hydroxycylohexadienyl) radicals, with conjugated carbon/oxygen-centered radicals such as phenoxyl radicals, and even with nitrogen- oxygen-, sulfur-, and halogen-centered radicals. In these reactions, further ozone-reactive radicals are generated. Chain reactions may destroy ozone without giving rise to products other than O(2). This may be of importance when ozonation is used in pollution control, and reactions of free radicals with ozone have to be taken into account in modeling such processes.

  13. Growth mechanism of NaClO3 and NaBrO3 crystals from aqueous solutions

    Indian Academy of Sciences (India)

    V Surender; N Arundhathi; K Kishan Rao

    2006-10-01

    A study of growth rates of NaClO3 and NaBrO3 has been carried out using a small growth cell by in situ observation. Normal growth rates of {100} faces of NaClO3 and {111} faces of NaBrO3 along $\\langle 110 \\rangle$ direction are measured under relatively high supersaturation ranging from 3–8%. In the initial stages of growth, {100}, {110} and {111} faces develop in NaClO3 and gradually all the faces are replaced by the {100} faces only. In the case of NaBrO3, mostly {111} faces develop with occasional occurrence of small {100} faces at the intersection of {111} faces. The growth mechanisms are investigated from growth rate vs supersaturation plots and from the observations of surface features. In the present supersaturation range, the growth mechanism appears to be due to two-dimensional growth mechanism.

  14. Chemical Reactions of Portland Cement with Aqueous CO2 and Their Impacts on Cement's Mechanical Properties under Geologic CO2 Sequestration Conditions.

    Science.gov (United States)

    Li, Qingyun; Lim, Yun Mook; Flores, Katharine M; Kranjc, Kelly; Jun, Young-Shin

    2015-05-19

    To provide information on wellbore cement integrity in the application of geologic CO2 sequestration (GCS), chemical and mechanical alterations were analyzed for cement paste samples reacted for 10 days under GCS conditions. The reactions were at 95 °C and had 100 bar of either N2 (control condition) or CO2 contacting the reaction brine solution with an ionic strength of 0.5 M adjusted by NaCl. Chemical analyses showed that the 3.0 cm × 1.1 cm × 0.3 cm samples were significantly attacked by aqueous CO2 and developed layer structures with a total attacked depth of 1220 μm. Microscale mechanical property analyses showed that the hardness and indentation modulus of the carbonated layer were 2-3 times greater than for the intact cement, but those in the portlandite-dissolved region decreased by ∼50%. The strength and elastic modulus of the bulk cement samples were reduced by 93% and 84%, respectively. The properties of the microscale regions, layer structure, microcracks, and swelling of the outer layers combined to affect the overall mechanical properties. These findings improve understanding of wellbore integrity from both chemical and mechanical viewpoints and can be utilized to improve the safety and efficiency of CO2 storage. PMID:25893278

  15. Influence of the pore structure and surface chemical properties of activated carbon on the adsorption of mercury from aqueous solutions

    International Nuclear Information System (INIS)

    Highlights: • Activated carbons with different pore structure and surface chemical properties were prepared by modification process. • HgCl2 as a pollution target to evaluate the adsorption performance. • Influence of pore structure and surface chemical properties of activated carbon on adsorption of mercury was investigated. -- Abstract: Reactivation and chemical modification were used to obtain modified activated carbons with different pore structure and surface chemical properties. The samples were characterized by nitrogen absorption–desorption, Fourier transform infrared spectroscopy and the Bothem method. Using mercury chloride as the target pollutant, the Hg2+ adsorption ability of samples was investigated. The results show that the Hg2+ adsorption capacity of samples increased significantly with increases in micropores and acidic functional groups and that the adsorption process was exothermic. Different models and thermodynamic parameters were evaluated to establish the mechanisms. It was concluded that the adsorption occurred through a monolayer mechanism by a two-speed process involving both rapid adsorption and slow adsorption. The adsorption rate was determined by chemical reaction

  16. Use of chemically derivatized n-type silicon photoelectrodes in aqueous media: photooxidation of iodide, hexacyanoiron(II), and hexaammineruthenium(II) at ferrocene-derivatized photoanodes

    Energy Technology Data Exchange (ETDEWEB)

    Bocarsly, A.B.; Walton, E.G.; Wrighton, M.S.

    1980-05-07

    A procedure is described for the chemical derivatization of the surface of n-type semiconductor photoanodes to yield photosensitive interfaces for use in a large number of thermodynamically uphill oxidation processes. (1,1'-ferrocenediyl)dichlorosilane was used to derivatize n-type Si to yield a photoanode that can be used under conditions where the naked (nonderivatized) n-type Si undergoes photoanodic corrosion yielding an insulating SiO/sub x/ surface layer. The results of use of this derivatized n-type Si in aqueous solutions to investigate the photooxidation of iodide, hexacyanoiron(II), and hexaammineruthenium(II) are reported. This type photoelectrode has an operation range that is nearly ideal from the point of solar energy conversion. (BLM)

  17. Facile aqueous growth of 150 nm ZnO nanowires for energy harvester: Enhanced output voltage using Pt sputtered electrode

    Directory of Open Access Journals (Sweden)

    Mansoor Ahmad

    2016-03-01

    Full Text Available Facile aqueous growth technique was adopted to grow diameter controlled 150 nm ZnO nanowires on an ITO (indium tin oxide coated PET (poly ethylene terephthalate substrate. Prior to nanowire growth, a pure wurtazite structured ZnO seed layer was grown on PET substrates. Surface morphology and elemental composition were investigated by SEM (scanning electron microscopy and EDS (energy dispersive spectroscopy respectively. An enhanced output piezoelectric potential of 1.858 with an output power density 215.4 mW/cm2 was achieved using a Pt sputtered electrode. We have obtained enhanced values of output voltage compared to our previously reported voltage values of 1.34 V (Ahmad et al. 2014.

  18. Growth kinetics for the precipitation of zirconium hydroxide from aqueous zirconium and tin bearing solutions by the addition of ammonium hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Carleson, T.E. [Idaho Univ., Moscow, ID (United States). Dept. of Chemical Engineering; Chipman, N.A. [Westinghouse Idaho Nuclear Co., Inc., Idaho Falls, ID (United States)

    1989-09-11

    The precipitation of zirconium hydroxide from an aqueous solution of ammonium hexafluorozirconate occurs rapidly upon addition of ammonium hydroxide. Experimental data indicate growth and nucleation rates between 0.06 and 0.28 microns/minute and around 10 {times} 107 number/L-min, respectively. Experiments with a mixed suspension mixed product removal crystallizer for concentrations of reactants of about 0.05 M ammonium hexafluorozirconate precipitating with 0.002 M ammonium hydroxide showed apparent nonlinear growth rates in some cases but not others. Batch studies indicated that growth rate dispersion is probably not present. When the AFL nonlinear model was used to fit the data, the power coefficient obtained was greater than 1, in disagreement with theory. In addition, for some of the data ``S`` shaped curves of the logarithm of the cumulative number greater than versus size were obtained. These curves can not be fit by the AFL model. A program developed at the University of Arizona was used to simulate the crystallization runs. The program results indicated that some of the nonlinear behavior may be attributed to transient conditions. Experimental data also illustrated this behavior. The effect of trace amounts of tin fluoride (0.008 M) on the nucleation and growth kinetics was also evaluated. For some residence times, the presence of tin resulted in reduced median particle diameters, higher growth rates, and lower number counts.

  19. Development of a new laser heating system for thin film growth by chemical vapor deposition.

    Science.gov (United States)

    Fujimoto, Eiji; Sumiya, Masatomo; Ohnishi, Tsuyoshi; Lippmaa, Mikk; Takeguchi, Masaki; Koinuma, Hideomi; Matsumoto, Yuji

    2012-09-01

    We have developed a new laser heating system for thin film growth by chemical vapor deposition (CVD). A collimated beam from a high-power continuous-wave 808 nm semiconductor laser was directly introduced into a CVD growth chamber without an optical fiber. The light path of the heating laser inside the chamber was isolated mechanically from the growth area by bellows to protect the optics from film coating. Three types of heat absorbers, (10 × 10 × 2 mm(3)) consisting of SiC, Ni/NiO(x), or pyrolytic graphite covered with pyrolytic BN (PG/PBN), located at the backside of the substrate, were tested for heating performance. It was confirmed that the substrate temperature could reach higher than 1500 °C in vacuum when a PG/PBN absorber was used. A wide-range temperature response between 400 °C and 1000 °C was achieved at high heating and cooling rates. Although the thermal energy loss increased in a H(2) gas ambient due to the higher thermal conductivity, temperatures up to 1000 °C were achieved even in 200 Torr H(2). We have demonstrated the capabilities of this laser heating system by growing ZnO films by metalorganic chemical vapor deposition. The growth mode of ZnO films was changed from columnar to lateral growth by repeated temperature modulation in this laser heating system, and consequently atomically smooth epitaxial ZnO films were successfully grown on an a-plane sapphire substrate.

  20. Controllable chemical vapor deposition growth of few layer graphene for electronic devices.

    Science.gov (United States)

    Wei, Dacheng; Wu, Bin; Guo, Yunlong; Yu, Gui; Liu, Yunqi

    2013-01-15

    Because of its atomic thickness, excellent properties, and widespread applications, graphene is regarded as one of the most promising candidate materials for nanoelectronics. The wider use of graphene will require processes that produce this material in a controllable manner. In this Account, we focus on our recent studies of the controllable chemical vapor deposition (CVD) growth of graphene, especially few-layer graphene (FLG), and the applications of this material in electronic devices. CVD provides various means of control over the morphologies of the produced graph ene. We studied several variables that can affect the CVD growth of graphene, including the catalyst, gas flow rate, growth time, and growth temperature and successfully achieved the controlled growth of hexagonal graphene crystals. Moreover, we developed several modified CVD methods for the controlled growth of FLGs. Patterned CVD produced FLGs with desired shapes in required areas. By introducing dopant precursor in the CVD process, we produced substitutionally doped FLGs, avoiding the typically complicated post-treatment processes for graphene doping. We developed a template CVD method to produce FLG ribbons with controllable morphologies on a large scale. An oxidation-activated surface facilitated the CVD growth of polycrystalline graphene without the use of a metal catalyst or a complicated postgrowth transfer process. In devices, CVD offers a controllable means to modulate the electronic properties of the graphene samples and to improve device performance. Using CVD-grown hexagonal graphene crystals as the channel materials in field-effect transistors (FETs), we improved carrier mobility. Substitutional doping of graphene in CVD opened a band gap for efficient FET operation and modulated the Fermi energy level for n-type or p-type features. The similarity between the chemical structure of graphene and organic semiconductors suggests potential applications of graphene in organic devices. We

  1. Valorisation of Vietnamese Rice Straw Waste: Catalytic Aqueous Phase Reforming of Hydrolysate from Steam Explosion to Platform Chemicals

    Directory of Open Access Journals (Sweden)

    Cao Huong Giang

    2014-12-01

    Full Text Available A family of tungstated zirconia solid acid catalysts were synthesised via wet impregnation and subsequent thermochemical processing for the transformation of glucose to 5-hydroxymethylfurfural (HMF. Acid strength increased with tungsten loading and calcination temperature, associated with stabilisation of tetragonal zirconia. High tungsten dispersions of between 2 and 7 W atoms·nm−2 were obtained in all cases, equating to sub-monolayer coverages. Glucose isomerisation and subsequent dehydration via fructose to HMF increased with W loading and calcination temperature up to 600 °C, indicating that glucose conversion to fructose was favoured over weak Lewis acid and/or base sites associated with the zirconia support, while fructose dehydration and HMF formation was favoured over Brönsted acidic WOx clusters. Aqueous phase reforming of steam exploded rice straw hydrolysate and condensate was explored heterogeneously for the first time over a 10 wt% WZ catalyst, resulting in excellent HMF yields as high as 15% under mild reaction conditions.

  2. Adsorption of Procion Blue MX-R dye from aqueous solutions by lignin chemically modified with aluminium and manganese.

    Science.gov (United States)

    Adebayo, Matthew A; Prola, Lizie D T; Lima, Eder C; Puchana-Rosero, M J; Cataluña, Renato; Saucier, Caroline; Umpierres, Cibele S; Vaghetti, Julio C P; da Silva, Leandro G; Ruggiero, Reinaldo

    2014-03-15

    A macromolecule, CML, was obtained by purifying and carboxy-methylating the lignin generated from acid hydrolysis of sugarcane bagasse during bioethanol production from biomass. The CMLs complexed with Al(3+) (CML-Al) and Mn(2+) (CML-Mn) were utilised for the removal of a textile dye, Procion Blue MX-R (PB), from aqueous solutions. CML-Al and CML-Mn were characterised using Fourier transform infrared spectroscopy (FTIR), scanning differential calorimetry (SDC), scanning electron microscopy (SEM) and pHPZC. The established optimum pH and contact time were 2.0 and 5h, respectively. The kinetic and equilibrium data fit into the general order kinetic model and Liu isotherm model, respectively. The CML-Al and CML-Mn have respective values of maximum adsorption capacities of 73.52 and 55.16mgg(-1) at 298K. Four cycles of adsorption/desorption experiments were performed attaining regenerations of up to 98.33% (CML-Al) and 98.08% (CML-Mn) from dye-loaded adsorbents, using 50% acetone+50% of 0.05molL(-1) NaOH. The CML-Al removed ca. 93.97% while CML-Mn removed ca. 75.91% of simulated dye house effluents. PMID:24462989

  3. Chemical Processing in High-Pressure Aqueous Environments. 9. Process Development for Catalytic Gasification of Algae Feedstocks

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Douglas C.; Hart, Todd R.; Neuenschwander, Gary G.; Rotness, Leslie J.; Olarte, Mariefel V.; Zacher, Alan H.

    2012-07-26

    Through the use of a metal catalyst, gasification of wet algae slurries can be accomplished with high levels of carbon conversion to gas at relatively low temperature (350 C). In a pressurized-water environment (20 MPa), near-total conversion of the organic structure of the algae to gases has been achieved in the presence of a supported ruthenium metal catalyst. The process is essentially steam reforming, as there is no added oxidizer or reagent other than water. In addition, the gas produced is a medium-heating value gas due to the synthesis of high levels of methane, as dictated by thermodynamic equilibrium. As opposed to earlier work, biomass trace components were removed by processing steps so that they did not cause processing difficulties in the fixed catalyst bed tubular reactor system. As a result, the algae feedstocks, even those with high ash contents, were much more reliably processed. High conversions were obtained even with high slurry concentrations. Consistent catalyst operation in these short-term tests suggested good stability and minimal poisoning effects. High methane content in the product gas was noted with significant carbon dioxide captured in the aqueous byproduct in combination with alkali constituents and the ammonia byproduct derived from proteins in the algae. High conversion of algae to gas products was found with low levels of byproduct water contamination and low to moderate loss of carbon in the mineral separation step.

  4. Chemical relevance of the copper(II)— L-carnosine system in aqueous solution: A thermodynamic and spectrophotometric study

    Science.gov (United States)

    Daniele, Pier G.; Prenesti, Enrico; Zelano, Vincenzo; Ostacoli, Giorgio

    1993-08-01

    The copper(II)— L-carnosine (L -) system has been re-investigated in aqueous solution, at I = 0.1 mol dm -1, different temperatures (5⩽ t⩽45°C) and with metal to ligand ratios ranging from 3:1 to 1:3. Both potentiometry and visible spectrophotometry were employed. From an overall consideration of all experiments, [CuLH] 2+, [CuL] +, [CuLH -1]°, [Cu 2L 2H -2]° and [Cu 2LH -1] 2+ were recognized as the species which provide the best interpretation of experimental data. The complex formation constants, determined at different temperatures, allowed us to obtain reliable values of Δ H° and good estimates of Δ C° p. From visible spectrophotometric measurements, carried out at different pH and metal to ligand ratios, it was possible to calculate the electronic spectrum of each complex formed in solution. A structure is also proposed for each species, on the basis of thermodynamic and spectral results.

  5. Studies on chemical protectors against radiation, 34; Survival effects of aqueous extracts of various Chinese traditional medicines on radiation injury

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cheng-Ming; Ohta, Setsuko; Shinoda, Masato (Hoshi Univ., Tokyo (Japan))

    1991-06-01

    In order to develop a nontoxic radioprotector, 60 kinds of Chinese traditional medicines were chosen, and their aqueous extracts tested for their survival effects against the lethal effect of X-irradiation in mice. Radiation factors used were as follows: soft X-rays, 2100 R (5.418x10{sup -1}Ckg{sup -1}), 70 kVp, 10 mA, 10 mm acrylic filter, 70 R (1.806x10{sup -2} Ckg{sup -1})/min. Among 60 medicines tested by intraperitoneal injection immediately before the irradiation, 15 are shown to have the significant survival effect. These 15 effective medicines were also tested by intraperitoneal injection after the irradiation, and the survival effect was recognized in Keisi-syakuyaku-chimo-to, Keigai-rengyo-to, Shimotu-to, Syakuyaku-kanzo-to and Hange-syasin-to. On the other hand, the survival effects of 25 medicines including the above-mentioned 15 medicines were investigated by the oral administration at various times before or after the irradiation. As the results of these studies, only Keigai-rengyo-to and Bukuryo-in are shown to have the significant survival effect when administered 2 h before the irradiation. (author).

  6. Chemical enrichment and separation of uranyl ions in aqueous media using novel polyurethane foam chemically grafted with different basic dyestuff sorbents.

    Science.gov (United States)

    El-Shahat, M F; Moawed, E A; Farag, A B

    2007-01-15

    The new type of the grafted polyurethane foam sorbents were prepared by coupling polyether polyol, toluene diisocyanate and basic dyestuff (Methylene blue, Rhodamine B and Brilliant green). The Me.B-PUF, Rh.B-PUF and Br.G-PUF were characterized using UV/vis, IR and TGA. The adsorption properties and chromatographic behaviour of these new adsorbents for preconcentration and separation of uranium(VI) ions at low concentrations from aqueous thiocyanate media were investigated by a batch process. The maximum sorption of U(VI) was in the pH ranges 1-4. The kinetics of sorption of the U(VI) by the Grafted-PUF were found to be fast with half life of sorption (t(1/2)) in 2.43min. The average sorption capacity of different sorbents 0.124meqg(-1) for uranyl ions, enrichment factors approximately 40 and the recovery 98-100% were achieved (R.S.D. approximately 0.73%). The basic dyestuff Grafted-PUF could be used many times without decreasing their capacities significantly. The value of the Gibbs free energy (DeltaG) for the sorbents is -7.3kJmol(-1), which reflects the spontaneous nature of sorption process. The sorption mechanism of the metal ion onto Grafted-PUF was also discussed. PMID:19071294

  7. The Development of Ionophore-Selective Based optical chemical sensors for the determination of heavy metal ions in aqueous environments

    OpenAIRE

    Li, Li

    2010-01-01

    The development of optical sensors for in-situ, real-time and low-cost monitoring of heavy metal ions is a tremendously and fast growing area of research. This work presents several novel sensing strategies for developing optical chemical sensors that can be used as early warning devices for heavy metal pollution in water. The optical sensors that are comprised of metal chelating reagent, together with an ion carrier immobilised within polymeric thin films, i.e. hybrid sol-gel ...

  8. Chemical diversity of microbial volatiles and their potential for plant growth and productivity

    Directory of Open Access Journals (Sweden)

    CHIDANANDA NAGAMANGALA KANCHISWAMY

    2015-03-01

    Full Text Available Microbial volatile organic compounds (MVOCs are produced by a wide array of microorganisms ranging from bacteria to fungi. A growing body of evidence indicates that MVOCs are ecofriendly and can be exploited as a cost-effective sustainable strategy for use in agricultural practice as agents that enhance plant growth, productivity and disease resistance. As naturally occurring chemicals, MVOCs have potential as possible alternatives to harmful pesticides, fungicides and bactericides as well as genetic modification. Recent studies performed under open field conditions demonstrate that efficiently adopting MVOCs may contribute to sustainable crop protection and production. We review here the chemical diversity of MVOCs and their potential physiological effects on crops and analyze potential and actual limitations for MVOC use as a sustainable strategy for improving productivity and reducing pesticide use.

  9. Effects of Surface Modification of Nanodiamond Particles for Nucleation Enhancement during Its Film Growth by Microwave Plasma Jet Chemical Vapour Deposition Technique

    Directory of Open Access Journals (Sweden)

    Chii-Ruey Lin

    2014-01-01

    Full Text Available The seedings of the substrate with a suspension of nanodiamond particles (NDPs were widely used as nucleation seeds to enhance the growth of nanostructured diamond films. The formation of agglomerates in the suspension of NDPs, however, may have adverse impact on the initial growth period. Therefore, this paper was aimed at the surface modification of the NDPs to enhance the diamond nucleation for the growth of nanocrystalline diamond films which could be used in photovoltaic applications. Hydrogen plasma, thermal, and surfactant treatment techniques were employed to improve the dispersion characteristics of detonation nanodiamond particles in aqueous media. The seeding of silicon substrate was then carried out with an optimized spin-coating method. The results of both Fourier transform infrared spectroscopy and dynamic light scattering measurements demonstrated that plasma treated diamond nanoparticles possessed polar surface functional groups and attained high dispersion in methanol. The nanocrystalline diamond films deposited by microwave plasma jet chemical vapour deposition exhibited extremely fine grain and high smooth surfaces (~6.4 nm rms on the whole film. These results indeed open up a prospect of nanocrystalline diamond films in solar cell applications.

  10. Temperature control and characterization of silicon-germanium growth by rapid thermal chemical vapor deposition

    Science.gov (United States)

    Hwang, Sung-Bo

    Rapid thermal chemical vapor deposition (RTCVD) is an emerging technology to utilize low thermal budgets required to grow silicon-germanium alloys in a coherent way. However, the current state-of-the-art in RTCVD technique lacks some key elements required for acceptance of RTCVD in mainstream IC fabrication. These shortcomings include adequate control of wafer temperature during processing, and sufficient understanding of the growth kinetics. This dissertation describes and discusses the temperature control in RTCVD, the growth, and characterization of silicon-germanium alloys. The RTCVD system provides very reliable temperature-measurements, for a range of 480˜820°C, based on infrared-light (1.3 or 1.55mum) absorption in the silicon wafer during the growth of silicon-germanium alloys. A wafer heat transfer model developed using the view-factor analysis is used to investigate temperature distributions with respect to lamp configurations in RTCVD system. For a precise temperature control, a neural model-based controller in single-input-single-output (SISO) system is proposed, and compared with other controllers. Silicon-germanium alloys, in various semiconductor structures including dots, have been grown by RTCVD where temperature is well-controlled by the model-based controller. The structural and chemical properties of silicon-germanium alloys are characterized by X-ray diffraction, atomic force microscopy (AFM), transmission electron microscopy (TEM), and secondary ion mass spectrometry (SIMS). The different growth characteristics dominated by a silicon-source gas are exploited, and their process models are developed with the experimental data utilizing neural networks employed the Bayesian framework to accurately describe the process behaviors such as growth rate and Ge fraction in alloys with respect to process variables (to capture the process nonlinearity). By controlling growth rate and Ge fraction, a uniform and a grading Ge profile in silicon

  11. Selective growth of graphene in layer-by-layer via chemical vapor deposition

    Science.gov (United States)

    Park, Jaehyun; An, Hyosub; Choi, Dong-Chul; Hussain, Sajjad; Song, Wooseok; An, Ki-Seok; Lee, Won-Jun; Lee, Naesung; Lee, Wan-Gyu; Jung, Jongwan

    2016-07-01

    Selective and precise control of the layer number of graphene remains a critical issue for the practical applications of graphene. First, it is highly challenging to grow a continuous and uniform few-layer graphene since once the monolayer graphene fully covers a copper (Cu) surface, the growth of the second layer stops, resulting in mostly nonhomogeneous films. Second, from the selective adlayer growth point of view, there is no clear pathway for achieving this. We have developed the selective growth of a graphene adlayer in layer-by-layer via chemical vapor deposition (CVD) which makes it possible to stack graphene on a specific position. The key idea is to deposit a thin Cu layer (~40 nm thick) on pre-grown monolayer graphene and to apply additional growth. The thin Cu atop the graphene/Cu substrate acts as a catalyst to decompose methane (CH4) gas during the additional growth. The adlayer is grown selectively on the pre-grown graphene, and the thin Cu is removed through evaporation during CVD, eventually forming large-area and uniform double layer graphene. With this technology, highly uniform graphene films with precise thicknesses of 1 to 5 layers and graphene check patterns with 1 to 3 layers were successfully demonstrated. This method provides precise LBL growth for a uniform graphene film and a technique for the design of new graphene devices.Selective and precise control of the layer number of graphene remains a critical issue for the practical applications of graphene. First, it is highly challenging to grow a continuous and uniform few-layer graphene since once the monolayer graphene fully covers a copper (Cu) surface, the growth of the second layer stops, resulting in mostly nonhomogeneous films. Second, from the selective adlayer growth point of view, there is no clear pathway for achieving this. We have developed the selective growth of a graphene adlayer in layer-by-layer via chemical vapor deposition (CVD) which makes it possible to stack graphene

  12. Growth of straight carbon nanotubes by simple thermal chemical vapor deposition

    Institute of Scientific and Technical Information of China (English)

    ZOU Xiao-ping; H. ABE; T. SHIMIZU; A. ANDO; H. TOKUMOTO; ZHU Shen-ming; ZHOU Hao-shen

    2006-01-01

    Straight carbon nanotubes (CNTs) were achieved by simple thermal chemical vapor deposition(STCVD) catalyzed by Mo-Fe alloy catalyst on silica supporting substrate at 700 ℃. High-resolution transmission electron microscopy images show that the straight CNTs are well graphitized with no attached amorphous carbon. Mo-Fe alloy catalyst particles play a very crucial role in the growth of straight CNTs. The straight carbon nanotubes contain much less defects than the curved nanotubes and might have potential applications for nanoelectrical devices in the future. The simple synthesis of straight CNTs may have benefit for large-scale productions.

  13. Growth of Saccharina and Palmaria compared to chemical and physical parameters in the inner Danish waters

    DEFF Research Database (Denmark)

    Holdt, Susan Løvstad; Grandorf, U. S.; Angelidaki, Irini;

    Information System ArcGIS on the obtained field data compared to the chemical and physical parameters (e.g. salinity (halocline), nutrient availability, currents, and cultivation areas for organic macroalgae). The macroalgal growth, biomass composition, the arcGIS, and the field samples on the variables...... will give a map of suitable areas for S. latissima and P. palmata cultivation in the inner Danish waters. The hypothesis is that the macroalgae perform better at higher salinities (further North and/or below the halocline) and in nutrient rich areas where light is not limited....

  14. Differential growth responses of soil bacterial taxa to carbon substrates of varying chemical recalcitrance

    Directory of Open Access Journals (Sweden)

    Katherine C Goldfarb

    2011-05-01

    Full Text Available Soils are immensely diverse microbial habitats with thousands of co-existing bacterial, archaeal and fungal species. Across broad spatial scales, factors such as pH and soil moisture appear to determine the diversity and structure of soil bacterial communities. Within any one site however, bacterial taxon diversity is high and factors maintaining this diversity are poorly resolved. Candidate factors include organic substrate availability and chemical recalcitrance, and given that they appear to structure bacterial communities at the phylum-level, we examine whether these factors might structure bacterial communities at finer levels of taxonomic resolution. Analyzing 16S rRNA gene composition of nucleotide analog-labeled DNA by PhyloChip microarrays, we compare relative growth rates on organic substrates of increasing chemical recalcitrance of >2,200 bacterial taxa across 43 divisions/phyla. Taxa that increase in relative abundance with labile organic substrates (i.e. glycine, sucrose are numerous (>500, phylogenetically-clustered, and occur predominantly in two phyla (Proteobacteria and Actinobacteria including orders Actinomycetales, Enterobacterales, Burkholderiales, Rhodocyclales, Alteromonadales and Pseudomonadales. Taxa increasing in relative abundance with more chemically recalcitrant substrates (i.e. cellulose, lignin or tannin-protein are fewer (168 but more phylogenetically-dispersed, occurring across 8 phyla and including Clostridiales, Sphingomonadalaes, Desulfovibrionales. Just over 6% of detected taxa, including many Burkholderiales increase in relative abundance with both labile and chemically recalcitrant substrates. Estimates of median rRNA copy number per genome of responding taxa demonstrate that these patterns are broadly consistent with bacterial growth strategies. Taken together, these data suggest that changes in availability of intrinsically labile substrates may result in predictable shifts in soil bacterial composition.

  15. Differential growth responses of soil bacterial taxa to carbon substrates of varying chemical recalcitrance

    Energy Technology Data Exchange (ETDEWEB)

    Goldfarb, K.C.; Karaoz, U.; Hanson, C.A.; Santee, C.A.; Bradford, M.A.; Treseder, K.K.; Wallenstein, M.D.; Brodie, E.L.

    2011-04-18

    Soils are immensely diverse microbial habitats with thousands of co-existing bacterial, archaeal, and fungal species. Across broad spatial scales, factors such as pH and soil moisture appear to determine the diversity and structure of soil bacterial communities. Within any one site however, bacterial taxon diversity is high and factors maintaining this diversity are poorly resolved. Candidate factors include organic substrate availability and chemical recalcitrance, and given that they appear to structure bacterial communities at the phylum level, we examine whether these factors might structure bacterial communities at finer levels of taxonomic resolution. Analyzing 16S rRNA gene composition of nucleotide analog-labeled DNA by PhyloChip microarrays, we compare relative growth rates on organic substrates of increasing chemical recalcitrance of >2,200 bacterial taxa across 43 divisions/phyla. Taxa that increase in relative abundance with labile organic substrates (i.e., glycine, sucrose) are numerous (>500), phylogenetically clustered, and occur predominantly in two phyla (Proteobacteria and Actinobacteria) including orders Actinomycetales, Enterobacteriales, Burkholderiales, Rhodocyclales, Alteromonadales, and Pseudomonadales. Taxa increasing in relative abundance with more chemically recalcitrant substrates (i.e., cellulose, lignin, or tannin-protein) are fewer (168) but more phylogenetically dispersed, occurring across eight phyla and including Clostridiales, Sphingomonadalaes, Desulfovibrionales. Just over 6% of detected taxa, including many Burkholderiales increase in relative abundance with both labile and chemically recalcitrant substrates. Estimates of median rRNA copy number per genome of responding taxa demonstrate that these patterns are broadly consistent with bacterial growth strategies. Taken together, these data suggest that changes in availability of intrinsically labile substrates may result in predictable shifts in soil bacterial composition.

  16. The Role of Plasma in Plasma Enhanced Chemical Vapour Deposition of Nanostructure Growth

    Science.gov (United States)

    Hash, David B.; Meyyappan, M.; Teo, Kenneth B. K.; Lacerda, Rodrigo G.; Rupesinghe, Nalin L.

    2004-01-01

    Chemical vapour deposition (CVD) has become the preferred process for high yield growth of carbon nanotubes and nanofibres because of its ability to pattern growth through lithographic positioning of transition metal catalysts on substrates. Many potential applications of nanotubes such as field emitters [1] require not only patterned growth but also vertical alignment. Some degree of ali,ment in thermal CVD processes can be obtained when carbon nanotubes are grown closely together as a result of van der Waals interactions. The ali,onment however is marginal, and the van der Waals prerequisite makes growth of freestanding nanofibres with thermal CVD unrealizable. The application of electric fields as a means of ali,onment has been shown to overcome this limitation [2-5], and highly aligned nanostructures can be grown if electric fields on the order of 0.5 V/microns are employed. Plasma enhanced CVD in various configurations including dc, rf, microwave, inductive and electron cyclotron resonance has been pursued as a means of enabling alignment in the CVD process. However, the sheath fields for the non-dc sources are in general not sufficient for a high degree of ali,pment and an additional dc bias is usually applied to the growth substrate. This begs the question as to the actual role of the plasma. It is clear that the plasma itself is not required for aligned growth as references [3] and [4] employed fields through small applied voltages (3-20 V) across very small electrode spacings (10-100 microns) and thus avoided striking a discharge.

  17. Adsorption of Procion Blue MX-R dye from aqueous solutions by lignin chemically modified with aluminium and manganese

    Energy Technology Data Exchange (ETDEWEB)

    Adebayo, Matthew A. [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, Postal Box 15003, 91501-970 Porto Alegre, RS (Brazil); Department of Chemical Sciences, Ajayi Crowther University, PMB 1066 Oyo, Oyo State (Nigeria); Prola, Lizie D.T. [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, Postal Box 15003, 91501-970 Porto Alegre, RS (Brazil); Lima, Eder C., E-mail: eder.lima@ufrgs.br [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, Postal Box 15003, 91501-970 Porto Alegre, RS (Brazil); Puchana-Rosero, M.J.; Cataluña, Renato; Saucier, Caroline; Umpierres, Cibele S.; Vaghetti, Julio C.P. [Institute of Chemistry, Federal University of Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, Postal Box 15003, 91501-970 Porto Alegre, RS (Brazil); Silva, Leandro G. da; Ruggiero, Reinaldo [Institute of Chemistry, Federal University of Uberlândia (UFU), AV. João Naves de Ávila 2121 block 1D—Campus Santa Mônica, 38400-902 Uberlândia, MG (Brazil)

    2014-03-01

    Graphical abstract: - Highlights: • Complexes of carboxy-methylated lignin with Al and Mn were used as adsorbents. • The optimum adsorption conditions were achieved at pH 2 and 298 K. • Maximum adsorption capacities are 73.52 mg g{sup −1} (CML-Al) and 55.16 mg g{sup −1} (CML-Mn). • CML-Al could remove ca. 95.83% of dye-contaminated industrial effluents. • CML-Al and CML-Mn are effective for treatment of simulated dye-house effluents. - Abstract: A macromolecule, CML, was obtained by purifying and carboxy-methylating the lignin generated from acid hydrolysis of sugarcane bagasse during bioethanol production from biomass. The CMLs complexed with Al{sup 3+} (CML-Al) and Mn{sup 2+} (CML-Mn) were utilised for the removal of a textile dye, Procion Blue MX-R (PB), from aqueous solutions. CML-Al and CML-Mn were characterised using Fourier transform infrared spectroscopy (FTIR), scanning differential calorimetry (SDC), scanning electron microscopy (SEM) and pH{sub PZC}. The established optimum pH and contact time were 2.0 and 5 h, respectively. The kinetic and equilibrium data fit into the general order kinetic model and Liu isotherm model, respectively. The CML-Al and CML-Mn have respective values of maximum adsorption capacities of 73.52 and 55.16 mg g{sup −1} at 298 K. Four cycles of adsorption/desorption experiments were performed attaining regenerations of up to 98.33% (CML-Al) and 98.08% (CML-Mn) from dye-loaded adsorbents, using 50% acetone + 50% of 0.05 mol L{sup −1} NaOH. The CML-Al removed ca. 93.97% while CML-Mn removed ca. 75.91% of simulated dye house effluents.

  18. Study on patterns and chemical features of NO effect on marine phytoplankton growth

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Zhengbin; LIN; Cai; LIU; Chunying; XING; Lei; WU; Zh

    2005-01-01

    This article discusses the patterns of NO effect on marine phytoplankton growth from chemical perspective.The experimental results of four algae, which are Platymonas halgolandica var.tsingtaoensis, Platymonas subcordiformis, Skeletonema costatum and Nitzschia closterium farma minutissima, are as follows: (i) In f/2 medium or f/50 medium, the growth of these four algae was obviously promoted or inhibited when nitric oxide of different concentrations was added once or twice each day during the cultivation; (ii) The NO effects on the growth of marine phytoplankton are in normal distribution.Different phytoplankton has different optimum NO concentration, which is consistent with the influence of NO on the growth of high plants; (iii) The effect of NO on Platymonas halgolandica var.tsingtaoensi, which is a food alga, is different from that on the red tide algae Skeletonema costatum and Nitzschia closterium farma minutissima.The authors put forward a new opinion that every alga has its own NO threshold concentration.All the above results may provide new clues to understand the formation of red tide.

  19. Essential Oils from Ugandan Aromatic Medicinal Plants: Chemical Composition and Growth Inhibitory Effects on Oral Pathogens

    Directory of Open Access Journals (Sweden)

    Francis Ocheng

    2015-01-01

    Full Text Available The study assessed the growth inhibitory effects of essential oils extracted from ten Ugandan medicinal plants (Bidens pilosa, Helichrysum odoratissimum, Vernonia amygdalina, Hoslundia opposita, Ocimum gratissimum, Cymbopogon citratus, Cymbopogon nardus, Teclea nobilis, Zanthoxylum chalybeum, and Lantana trifolia used traditionally in the management of oral diseases against oral pathogens. Chemical compositions of the oils were explored by GC-MS. Inhibitory effects of the oils were assessed on periodontopathic Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans and cariogenic Streptococcus mutans and Lactobacillus acidophilus using broth dilution methods at concentrations of 1%, 0.1%, and 0.01%. The most sensitive organism was A. actinomycetemcomitans. Its growth was markedly inhibited by six of the oils at all the concentrations tested. Essential oil from C. nardus exhibited the highest activity with complete growth inhibition of A. actinomycetemcomitans and P. gingivalis at all the three concentrations tested, the major constituents in the oil being mainly oxygenated sesquiterpenes. Most of the oils exhibited limited effects on L. acidophilus. We conclude that essential oils from the studied plants show marked growth inhibitory effects on periodontopathic A. actinomycetemcomitans and P. gingivalis, moderate effects on cariogenic S. mutans, and the least effect on L. acidophilus. The present study constitutes a basis for further investigations and development of certain oils into alternative antiplaque agents.

  20. Hydrogen-free spray pyrolysis chemical vapor deposition method for the carbon nanotube growth: Parametric studies

    Energy Technology Data Exchange (ETDEWEB)

    Ionescu, Mihnea Ioan; Zhang Yong; Li Ruying [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON. N6A 5B9 (Canada); Sun Xueliang, E-mail: xsun@eng.uwo.ca [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON. N6A 5B9 (Canada); Abou-Rachid, Hakima; Lussier, Louis-Simon [Defense Research and Development Canada - Valcartier, 2459 Boulevard Pie-XI Nord, Quebec, QC. G3J 1X5 (Canada)

    2011-05-15

    Spray pyrolysis chemical vapor deposition (CVD) in the absence of hydrogen at low carrier gas flow rates has been used for the growth of carbon nanotubes (CNTs). A parametric study of the carbon nanotube growth has been conducted by optimizing various parameters such as temperature, injection speed, precursor volume, and catalyst concentration. Experimental observations and characterizations reveal that the growth rate, size and quality of the carbon nanotubes are significantly dependent on the reaction parameters. Scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy techniques were employed to characterize the morphology, structure and crystallinity of the carbon nanotubes. The synthesis process can be applied to both semiconducting silicon wafer and conducting substrates such as carbon microfibers and stainless steel plates. This approach promises great potential in building various nanodevices with different electron conducting requirements. In addition, the absence of hydrogen as a carrier gas and the relatively low synthesis temperature (typically 750 deg. C) qualify the spray pyrolysis CVD method as a safe and easy way to scale up the CNT growth, which is applicable in industrial production.

  1. Hydrogen-free spray pyrolysis chemical vapor deposition method for the carbon nanotube growth: Parametric studies

    International Nuclear Information System (INIS)

    Spray pyrolysis chemical vapor deposition (CVD) in the absence of hydrogen at low carrier gas flow rates has been used for the growth of carbon nanotubes (CNTs). A parametric study of the carbon nanotube growth has been conducted by optimizing various parameters such as temperature, injection speed, precursor volume, and catalyst concentration. Experimental observations and characterizations reveal that the growth rate, size and quality of the carbon nanotubes are significantly dependent on the reaction parameters. Scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy techniques were employed to characterize the morphology, structure and crystallinity of the carbon nanotubes. The synthesis process can be applied to both semiconducting silicon wafer and conducting substrates such as carbon microfibers and stainless steel plates. This approach promises great potential in building various nanodevices with different electron conducting requirements. In addition, the absence of hydrogen as a carrier gas and the relatively low synthesis temperature (typically 750 deg. C) qualify the spray pyrolysis CVD method as a safe and easy way to scale up the CNT growth, which is applicable in industrial production.

  2. The influence of a non-aqueous phase liquid (NAPL) and chemical oxidant application on perfluoroalkyl acid (PFAA) fate and transport.

    Science.gov (United States)

    McKenzie, Erica R; Siegrist, Robert L; McCray, John E; Higgins, Christopher P

    2016-04-01

    One dimensional column experiments were conducted using saturated porous media containing residual trichloroethylene (TCE) to understand the effects of non-aqueous phase liquids (NAPLs) and chemical oxidation on perfluoroalkyl acid (PFAA) fate and transport. Observed retardation factors and data from supporting batch studies suggested that TCE provides additional sorption capacity that can increase PFAA retardation (i.e., decreased mobility), though the mechanisms remain unclear. Treatment with persulfate activated with FeCl2 and citric acid, catalyzed hydrogen peroxide (CHP), or permanganate did not result in oxidative transformations of PFAAs. However, impacts on PFAA sorption were apparent, and enhanced sorption was substantial in the persulfate-treated columns. In contrast, PFAA transport was accelerated in permanganate- and CHP-treated columns. Ultimately, PFAA transport in NAPL contaminated groundwater is likely influenced by porous media properties, NAPL characteristics, and water quality properties, each of which can change due to chemical oxidant treatment. For contaminated sites for which ISCO is a viable treatment option, changes to PFAA transport and the implications thereof should be included as a component of the remediation evaluation and selection process. PMID:26854608

  3. Effects of ferrous iron on the precipitation and growth of CaCO3 in slightly basic aqueous solutions, from macro to nanoscale

    Science.gov (United States)

    Di Lorenzo, Fulvio; Burgos-Cara, Alejandro; Ruiz-Agudo, Encarnación; Putnis, Christine V.; Prieto, Manuel

    2016-04-01

    The precipitation of CaCO3 and further growth of calcite has been studied in aqueous solutions containing ferrous iron (Fe2+). Two different types of bulk experiments have been carried out. Nucleation experiments have been conducted at pH 9 with five different CaTOT/FeTOT ratios: 10, 5, 2.5, 1.25 and 0.625. As well, calcite growth experiments have been conducted at pH 8.5 (following the constant composition method) with CaTOT/FeTOT ratios: 100, 50 and 25; this higher dilution partially reduces the impact of inhibition on growth of calcite occurring when CaTOT/FeTOT ≤ 25. Parameters such as the solution pH, [Ca2+], conductivity, solution transmittance (610 nm), and volume added were continuously monitored by a Titrino 905 system (Metrohm, Switzerland). After the experiments, the CaCO3 precipitates were collected, filtered, dried and characterized by powder-XRD, HRTEM, FESEM-EDX, EMPA. Solution composition was determined by ICP-MS. Additionally, in-situ Atomic Force Microscopy (AFM) flow-through growth experiments were conducted in a sealed fluid cell using freshly cleaved natural calcite (Iceland spar). The solution composition in AFM experiments was analogous to the bulk growth experiments. The results of these experiments reveal the significant influence of ferrous iron on nucleation and growth in the CaCO3-H2O system, reflected as well in polymorphic selection in this system.Finally, thermodynamic considerations for the system Ca-Fe-CO2-H2O are discussed that allow the modelling of geochemical processes involving this system, such as geological carbon storage in basaltic rocks.

  4. The Influence of an Intensive In-Service Workshop on Pedagogical Content Knowledge Growth among Novice Chemical Demonstrators.

    Science.gov (United States)

    Clermont, Christian P.; And Others

    1993-01-01

    Study examined the influence of an intensive chemical demonstration workshop on fostering pedagogical content knowledge growth among science teachers identified as novice chemical demonstrators (n=8). The two-week workshop was designed around four training elements considered important for effective teacher inservicing: theory, modeling, practice,…

  5. Chemical constraints governing the origin of metabolism: the thermodynamic landscape of carbon group transformations under mild aqueous conditions

    Science.gov (United States)

    Weber, Arthur L.

    2002-01-01

    The thermodynamics of organic chemistry under mild aqueous conditions was examined in order to begin to understand its influence on the structure and operation of metabolism and its antecedents. Free energies (deltaG) were estimated for four types of reactions of biochemical importance carbon-carbon bond cleavage and synthesis, hydrogen transfer between carbon groups, dehydration of alcohol groups, and aldo-keto isomerization. The energies were calculated for mainly aliphatic groups composed of carbon, hydrogen, and oxygen. The energy values showed (1) that generally when carbon-carbon bond cleavage involves groups from different functional group classes (i.e., carboxylic acids, carbonyl groups, alcohols, and hydrocarbons), the transfer of the shared electron-pair to the more reduced carbon group is energetically favored over transfer to the more oxidized carbon group, and (2) that the energy of carbon-carbon bond transformation is primarily determined by the functional group class of the group that changes oxidation state in the reaction (i.e., the functional group class of the group that donates the shared electron-pair during cleavage, or that accepts the incipient shared electron-pair during synthesis). In contrast, the energy of hydrogen transfer between carbon groups is determined by the functional group class of both the hydrogen-donor group and the hydrogen-acceptor group. From these and other observations we concluded that the chemistry involved in the origin of metabolism (and to a lesser degree modern metabolism) was strongly constrained by (1) the limited redox-based transformation energy of organic substrates that is readily dissipated in a few energetically favorable irreversible reactions; (2) the energy dominance of a few transformation half-reactions that determines whether carbon-carbon bond transformation (cleavage or synthesis) is energetically favorable (deltaG +3.5 kcal/mol); and (3) the dependence of carbon group transformation energy on the

  6. Graphene-assisted growth of high-quality AlN by metalorganic chemical vapor deposition

    Science.gov (United States)

    Zeng, Qing; Chen, Zhaolong; Zhao, Yun; Wei, Tongbo; Chen, Xiang; Zhang, Yun; Yuan, Guodong; Li, Jinmin

    2016-08-01

    High-quality AlN films were directly grown on graphene/sapphire substrates by metalorganic chemical vapor deposition (MOCVD). The graphene layers were directly grown on sapphire by atmospheric-pressure chemical vapor deposition (APCVD), a low-cost catalyst-free method. We analyzed the influence of the graphene layer on the nucleation of AlN at the initial stage of growth and found that sparse AlN grains on graphene grew and formed a continuous film via lateral coalescence. Graphene-assisted AlN films are smooth and continuous, and the full width at half maximum (FWHM) values for (0002) and (10\\bar{1}2) reflections are 360 and 622.2 arcsec, which are lower than that of the film directly grown on sapphire. The high-resolution TEM images near the AlN/sapphire interface for graphene-assisted AlN films clearly show the presence of graphene, which kept its original morphology after the 1200 °C growth of AlN.

  7. Effects of prevalent freshwater chemical contaminants on in vitro growth of Escherichia coli and Klebsiella pneumoniae

    Energy Technology Data Exchange (ETDEWEB)

    Higgins, James [USDA-ARS, Bldg 173, 10300 Baltimore Ave., Beltsville, MD 20705 (United States)], E-mail: tarbandu12@juno.com; Hohn, Christina [NCSU College of Veterinary Medicine, Raleigh, NC 27606 (United States)

    2008-03-15

    Many surface and ground waters in the continental US are contaminated with a variety of chemical pollutants, which are usually present in concentrations in the ppm and ppb range. The effects of these pollutants on coliform bacteria, which are prominent members of the aquatic flora, are poorly understood. Using a microtiter plate assay, isolates of Escherichia coli (from chicken intestine and fresh water), and an isolate of Klebsiella pneumoniae (from bovine milk) were exposed to varying concentrations of common pollutants over a 24 h period. The herbicides/pesticides simazine, atrazine, and diazinon; the VOCs trichloroethene and MTBE; the estrogens estradiol and estrone; and caffeine, all failed to inhibit bacterial growth at ppm levels. Only ethylene glycol, and the herbicide 2,4-D, significantly inhibited bacterial growth compared to controls. These results suggest that the replication of coliform bacteria in fresh waters is not adversely impacted by many common pollutants. - Using a microtiter plate assay, E. coli and Klebsiella bacteria were exposed to a panel of common chemical pollutants of fresh water; only ethylene glycol and 2,4-D inhibited bacterial replication.

  8. Species transport and chemical reaction in a MOCVD reactor and their influence on the GaN growth uniformity

    Science.gov (United States)

    Zhang, Zhi; Fang, Haisheng; Yao, Qingxia; Yan, Han; Gan, Zhiyin

    2016-11-01

    Fluid flow, heat transfer, and species transport with chemical reactions have been investigated for gallium nitride (GaN) growth in a commercial metal-organic chemical vapor deposition (MOCVD) reactor. Both the growth rate and the growth uniformity are investigated zone by zone, as the wafers are divided into three zones/groups according to their distances to the susceptor center. The results show that species transport in the reactor is affected by the inlet conditions, i.e., the premixed or non-premixed inlet, the inlet temperature, the total gas flow rate, and the V/III component ratio, and reveal that the premixed inlet condition is preferred for uniform growth. Especially, a large total flow rate or a low V/III ratio results in both increase of the growth rate and improvement of the growth uniformity.

  9. Aqueous phase synthesis of upconversion nanocrystals through layer-by-layer epitaxial growth for in vivo X-ray computed tomography

    KAUST Repository

    Li, Feifei

    2013-05-21

    Lanthanide-doped core-shell upconversion nanocrystals (UCNCs) have tremendous potential for applications in many fields, especially in bio-imaging and medical therapy. As core-shell UCNCs are mostly synthesized in organic solvents, tedious organic-aqueous phase transfer processes are usually needed for their use in bio-applications. Herein, we demonstrate the first example of one-step synthesis of highly luminescent core-shell UCNCs in the "aqueous" phase under mild conditions using innocuous reagents. A microwave-assisted approach allowed for layer-by-layer epitaxial growth of a hydrophilic NaGdF4 shell on NaYF4:Yb, Er cores. During this process, surface defects of the nanocrystals could be gradually passivated by the homogeneous shell deposition, resulting in obvious enhancement in the overall upconversion emission efficiency. In addition, the up-down conversion dual-mode luminescent NaYF4:Yb, Er@NaGdF4:Ce, Ln (Eu, Tb, Sm, Dy) nanocrystals were also synthesized to further validate the successful formation of the core-shell structure. More significantly, based on their superior solubility and stability in water solution, high upconversion efficiency and Gd-doped predominant X-ray absorption, the as-prepared NaYF4:Yb, Er@NaGdF4 core-shell UCNCs exhibited high contrast in in vitro cell imaging and in vivo X-ray computed tomography (CT) imaging, demonstrating great potential as multiplexed luminescent biolabels and CT contrast agents.

  10. Amorphous inclusions during Ge and GeSn epitaxial growth via chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gencarelli, F., E-mail: federica.gencarelli@imec.be [imec, Kapeldreef 75, 3001 Leuven (Belgium); Dept. of Metallurgy and Materials Engineering, KU Leuven, B-3001 Leuven (Belgium); Shimura, Y. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Nuclear and Radiation Physics Section, KU Leuven, B-3001 Leuven (Belgium); Kumar, A. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Nuclear and Radiation Physics Section, KU Leuven, B-3001 Leuven (Belgium); Vincent, B.; Moussa, A.; Vanhaeren, D.; Richard, O.; Bender, H. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Vandervorst, W. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Nuclear and Radiation Physics Section, KU Leuven, B-3001 Leuven (Belgium); Caymax, M.; Loo, R. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Heyns, M. [imec, Kapeldreef 75, 3001 Leuven (Belgium); Dept. of Metallurgy and Materials Engineering, KU Leuven, B-3001 Leuven (Belgium)

    2015-09-01

    In this work, we discuss the characteristics of particular island-type features with an amorphous core that are developed during the low temperature epitaxial growth of Ge and GeSn layers by means of chemical vapor deposition with Ge{sub 2}H{sub 6}. Although further investigations are needed to unambiguously identify the origin of these features, we suggest that they are originated by the formation of clusters of H and/or contaminants atoms during growth. These would initially cause the formation of pits with crystalline rough facets over them, resulting in ring-shaped islands. Then, when an excess surface energy is overcome, an amorphous phase would nucleate inside the pits and fill them. Reducing the pressure and/or increasing the growth temperature can be effective ways to prevent the formation of these features, likely due to a reduction of the surface passivation from H and/or contaminant atoms. - Highlights: • Island features with amorphous cores develop during low T Ge(Sn) CVD with Ge{sub 2}H{sub 6.} • These features are thoroughly characterized in order to understand their origin. • A model is proposed to describe the possible evolution of these features. • Lower pressures and/or higher temperatures avoid the formation of these features.

  11. Pilot scale study of a chemical treatment process for decontamination of aqueous radioactive waste of pakistan research reactor-1

    International Nuclear Information System (INIS)

    Chemical treatment process for the low level liquid radioactive waste generated at PINSTECH was previously optimized on lab-scale making use of coprecipitation of hydrous oxides of iron in basic medium. Ferrous sulfate was used as coagulant. Batch wise application of this procedure on pilot scale has been tested on a 1200 L batch volume of typical PINSTECH liquid waste. Different parameters and unit operations have been evaluated. The required data for the construction of a small size treatment plant envisioned can be used for demonstration/teaching purpose as well as for the decontamination of the waste effluents of the Institute. The lab-scale process parameters were verified valid on pilot scale. It was observed that reagent doses can further be economized with out any deterioration of the Decontamination Factors (DF) achieved or of any other aspect of the process. This simple, cost- effective, DF-efficient and time-smart batch wise process could be coupled with an assortment of other treatment operations thus affording universal application. Observations recorded during this study are presented. (author)

  12. Selective Chemical Conversion of Sugars in Aqueous Solutions without Alkali to Lactic Acid Over a Zn-Sn-Beta Lewis Acid-Base Catalyst

    Science.gov (United States)

    Dong, Wenjie; Shen, Zheng; Peng, Boyu; Gu, Minyan; Zhou, Xuefei; Xiang, Bo; Zhang, Yalei

    2016-05-01

    Lactic acid is an important platform molecule in the synthesis of a wide range of chemicals. However, in aqueous solutions without alkali, its efficient preparation via the direct catalysis of sugars is hindered by a side dehydration reaction to 5-hydroxymethylfurfural due to Brønsted acid, which originates from organic acids. Herein, we report that a previously unappreciated combination of common two metal mixed catalyst (Zn-Sn-Beta) prepared via solid-state ion exchange synergistically promoted this reaction. In water without a base, a conversion exceeding 99% for sucrose with a lactic acid yield of 54% was achieved within 2 hours at 190 °C under ambient air pressure. Studies of the acid and base properties of the Zn-Sn-Beta zeolite suggest that the introduction of Zn into the Sn-Beta zeolite sequentially enhanced both the Lewis acid and base sites, and the base sites inhibited a series of side reactions related to fructose dehydration to 5-hydroxymethylfurfural and its subsequent decomposition.

  13. Removal of Zn(II) and Hg(II) from aqueous solution on a carbonaceous sorbent chemically prepared from rice husk

    International Nuclear Information System (INIS)

    A carbonaceous sorbent was prepared from rice husk via sulfuric acid treatment. Sorption of Zn(II) and Hg(II) from aqueous solution was studied varying time, pH, metal concentration, temperature and sorbent status (wet and dry). Zn(II) sorption was found fast reaching equilibrium within ∼2 h while Hg(II) sorption was slow reaching equilibrium within ∼120 h with better performance for the wet sorbent than for the dry. Kinetics data for both metals were found to follow pseudo-second order model. Sorption rate of both metals was enhanced with temperature rise. Activation energy, Ea, for Zn(II) sorption, was ∼13.0 kJ/mol indicating a diffusion-controlled process ion exchange process, however, for Hg(II) sorption, Ea was ∼54 kJ/mol indicating a chemically controlled process. Sorption of both metals was low at low pH and increased with pH increase. Sorption was much higher for Hg(II) than for Zn(II) with higher uptake for both metals by rising the temperature. Hg(II) was reduced to Hg(I) on the sorbent surface. This was confirmed from the identification of Hg2Cl2 deposits on the sorbent surface by scanning electron microscopy and X-ray diffraction. However, no redox processes were observed in Zn(II) sorption. Sorption mechanism is discussed.

  14. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Alnoor, Hatim, E-mail: hatim.alnoor@liu.se; Chey, Chan Oeurn; Pozina, Galia; Willander, Magnus; Nur, Omer [Department of Science and Technology (ITN), Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden); Liu, Xianjie; Khranovskyy, Volodymyr [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-583 81 Linköping (Sweden)

    2015-08-15

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  15. Sodium Borohydride Reduction of Aqueous Silver-Iron-Nickel Solutions: a Chemical Route to Synthesis of Low Thermal Expansion-High Conductivity Ag-Invar Alloys

    Science.gov (United States)

    Sterling, E. A.; Stolk, J.; Hafford, L.; Gross, M.

    2009-07-01

    Thermal management is a critical concern in the design and performance of electronics systems. If heat extraction and thermal expansion are not properly addressed, the thermal mismatch among dissimilar materials may give rise to high thermal stresses or interfacial shear strains, and ultimately to premature system failure. In this article, we present a chemical synthesis process that yields Ag-Invar (64Fe-36Ni) alloys with a range of attractive properties for thermal management applications. Sodium borohydride reduction of an aqueous Ag-Fe-Ni metal salt solution produces nanocrystalline powders, and conventional powder processing converts this powder to fine-grained alloys. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy, thermomechanical analysis, and electrical conductivity measurements; thermal conductivity is estimated using the Wiedemann-Franz law. Sintering of Ag-Fe-Ni powders leads to the formation of two-phase silver-Invar alloys with low coefficients of thermal expansion (CTEs) and relatively high electrical conductivities. A sample of 50Ag-50Invar exhibits a CTE of 8.76 μm/(m· °C) and an estimated thermal conductivity of 236 W/(m·K). The Ag-Invar alloys offer thermodynamic stability and tailorable properties, and they may help address the need for improved packaging materials.

  16. Evaluating the potential for quantitative monitoring of in situ chemical oxidation of aqueous-phase TCE using in-phase and quadrature electrical conductivity

    Science.gov (United States)

    Hort, R. D.; Revil, A.; Munakata-Marr, J.; Mao, D.

    2015-07-01

    Electrical resistivity measurements can potentially be used to remotely monitor fate and transport of ionic oxidants such as permanganate (MnO4-) during in situ chemical oxidation (ISCO) of contaminants like trichloroethene (TCE). Time-lapse two-dimensional bulk conductivity and induced polarization surveys conducted during a sand tank ISCO simulation demonstrated that MnO4- plume movement could be monitored in a qualitative manner using bulk conductivity tomograms, although chargeability was below sensitivity limits. We also examined changes to in-phase and quadrature electrical conductivity resulting from ion injection, MnO2 and Cl- production, and pH change during TCE and humate oxidation by MnO4- in homogeneous aqueous solutions and saturated porous media samples. Data from the homogeneous samples demonstrated that inversion of the sand tank resistivity data using a common Tikhonov regularization approach was insufficient to recover an accurate conductivity distribution within the tank. While changes to in-phase conductivity could be successfully modeled, quadrature conductivity values could not be directly related to TCE oxidation product or MnO4- concentrations at frequencies consistent with field induced polarization surveys, limiting the utility of quadrature conductivity for monitoring ISCO.

  17. Crystal growth rates and optical resolution of DL-methionine hydrochloride by preferential crystallization from aqueous solution

    Science.gov (United States)

    Srimahaprom, Watcharakarn; Flood, Adrian E.

    2013-01-01

    Optical resolution of DL-methionine hydrochloride (DL-met·HCl) by preferential crystallization was studied for the purification of L-met·HCl (the desired enantiomer) from supersaturated solutions of DL-met·HCl. The nucleation thresholds (NT) of DL-met·HCl affect the maximum resolution time suitable for preferential crystallization and also the percentage purity of the product crystals. Crystal growth rates of L-met·HCl single crystals both in supersaturated solutions of DL-met·HCl and in supersaturated solutions of pure L-met·HCl were measured in order to model the preferential crystallization more effectively. Results showed that the growth rate depends strongly on the relative supersaturation (especially from pure L-met·HCl solutions), that there is a wide crystal growth rate distribution in growth from both types of solution, and that the growth is faster from pure L-met·HCl solutions, as expected. A batch crystallizer seeded with L-met·HCl crystals was used to study the preferential crystallization, and to study the behavior of purity decrease of the product crystals during the crystallization process. The purity of the L-met·HCl product decreased to the equilibrium value over time, with almost no plateau at 100% purity (as is hoped for in preferential crystallizations). This is explainable by the very short induction times for nucleation in these solutions, and also that the L-met·HCl seed crystals may act as a template for the nucleation of the counter-enantiomer.

  18. Effect of Reaction Time and Temperature on Chemical, Structural, Optical, and Photoelectrical Properties of PbS Thin Films Chemically Deposited from the Pb(OAc)2-NaOH-TU-TEA Aqueous System

    Science.gov (United States)

    Castelo-González, O. A.; Sotelo-Lerma, M.; García-Valenzuela, J. A.

    2016-08-01

    Lead sulfide (PbS) thin films have been deposited on float glass substrates by the chemical bath deposition technique using a Pb(CH3COO)2-NaOH-(NH2)2CS-N(CH2CH2OH)3 definite aqueous system. The chemical and structural characteristics, as well as the variation of the optical and photoelectrical properties, were studied as functions of reaction time and temperature. For this purpose, the following characterization techniques were employed: x-ray diffraction analysis, x-ray photoelectron spectroscopy, ultraviolet-visible-near infrared spectrophotometry, and dark and light current measurements. Based on the results, it was observed that increase in the reaction temperature increased the deposition rate of the PbS thin film (associated with the cubic crystalline structure); increase of this parameter from 40°C to 70°C (with reaction time of 60 min) led to an increase of the thickness from ˜129 nm to ˜459 nm and the crystallite size (D) from 15.3 nm to 20.2 nm; on the other hand, increase in temperature decreased the energy bandgap (E g) from 1.66 eV to 0.51 eV and the relative photosensitivity factor (S ph) from 0.468 to 0.032. A similar effect was obtained with increase of the reaction time for given temperature.

  19. Synthesis and Growth Mechanism of Carbon Filaments by Chemical Vapor Deposition without Catalyst

    Institute of Scientific and Technical Information of China (English)

    Shuhe Liu; Feng Li; Shuo Bai

    2009-01-01

    Carbon filaments with diameter from several to hundreds micrometers were synthesized by chemical vapor deposition of methane without catalyst. The morphology, microstructure and mechanical properties of the carbon filament were investigated by scanning electronic microscopy, optical microscopy, X-ray diffraction and mechanical testing. The results show that the carbon filament is inverted cone shape and grows up along the gas flow direction. The stem of it is formed of annular carbon layers arranged in a tree ring structure while the head is made up of concentrical layers. The tensile strength of the carbon filament is increased after graphitization for the restructuring and growing large of graphene. The growth mechanism of carbon filament was proposed according to the results of two series of experiments with different deposition time and intermittent deposition cycles.

  20. Al-Induced Crystallization Growth of Si Films by Inductively Coupled Plasma Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    LI Jun-Shuai; WANG Jin-Xiao; YIN Min; GAO Ping-Qi; HE De-Yan

    2006-01-01

    Polycrystalline Si (poly-Si) films are in situ grown on Al-coated glass substrates by inductively coupled plasma chemical vapour deposition at a temperature as low as 350 C. Compared to the traditional annealing crystallization of amorphous Si/Al-layer structures, no layer exchange is observed and the resultant poly-Si film is much thicker than Al layer. By analysing the depth profiles of the elemental composition, no remains of Al atoms are detected in Si layer within the limit (< 0.01 at. %) of the used evaluations. It is indicated that the poly-Si material obtained by Al-induced crystallization growth has more potential applications than that prepared by annealing the amorphous Si/Al-layer structures.

  1. Steam bubble growth in the bulk of overheated N2O4-NO chemically reacting solution

    International Nuclear Information System (INIS)

    A mathematical model and numerical investigation of the vapour bubble growth that begins from the bubble critical size at the positive radius fluctuation during the initial moment in the bulk of the overheated N2O4-NO liquid solution are presented. The mathematical model has been stated under the following assumptions: the movement of a bubble wall and surrounding liquid is spherically symmetrical; thermal parameters in the bubble are distributed uniformly; the vapour phase follows the ideal gas law; heat transfer is not affected by the compressibility of liquid; if dissolution of light components is determined by Henry's law, then Hertz-Knudsen's equation determines the velocity of phase transition for a N2O4 component. The mathematical model presented can be applied to another fluids, including chemically reacting ones

  2. Growth of GaN micro/nanolaser arrays by chemical vapor deposition

    Science.gov (United States)

    Liu, Haitao; Zhang, Hanlu; Dong, Lin; Zhang, Yingjiu; Pan, Caofeng

    2016-09-01

    Optically pumped ultraviolet lasing at room temperature based on GaN microwire arrays with Fabry-Perot cavities is demonstrated. GaN microwires have been grown perpendicularly on c-GaN/sapphire substrates through simple catalyst-free chemical vapor deposition. The GaN microwires are [0001] oriented single-crystal structures with hexagonal cross sections, each with a diameter of ˜1 μm and a length of ˜15 μm. A possible growth mechanism of the vertical GaN microwire arrays is proposed. Furthermore, we report room-temperature lasing in optically pumped GaN microwire arrays based on the Fabry-Perot cavity. Photoluminescence spectra exhibit lasing typically at 372 nm with an excitation threshold of 410 kW cm-2. The result indicates that these aligned GaN microwire arrays may offer promising prospects for ultraviolet-emitting micro/nanodevices.

  3. Chemical vapor deposition polymerization the growth and properties of parylene thin films

    CERN Document Server

    Fortin, Jeffrey B

    2004-01-01

    Chemical Vapor Deposition Polymerization - The Growth and Properties of Parylene Thin Films is intended to be valuable to both users and researchers of parylene thin films. It should be particularly useful for those setting up and characterizing their first research deposition system. It provides a good picture of the deposition process and equipment, as well as information on system-to-system variations that is important to consider when designing a deposition system or making modifications to an existing one. Also included are methods to characterizae a deposition system's pumping properties as well as monitor the deposition process via mass spectrometry. There are many references that will lead the reader to further information on the topic being discussed. This text should serve as a useful reference source and handbook for scientists and engineers interested in depositing high quality parylene thin films.

  4. Growth and characterization of boron doped graphene by Hot Filament Chemical Vapor Deposition Technique (HFCVD)

    Science.gov (United States)

    Jafari, A.; Ghoranneviss, M.; Salar Elahi, A.

    2016-03-01

    Large-area boron doped graphene was synthesized on Cu foil (as a catalyst) by Hot Filament Chemical Vapor Deposition (HFCVD) using boron oxide powder and ethanol vapor. To investigate the effect of different boron percentages, grow time and the growth mechanism of boron-doped graphene, scanning electron microscopy (SEM), Raman scattering and X-ray photoelectron spectroscopy (XPS) were applied. Also in this experiment, the I-V characteristic carried out for study of electrical property of graphene with keithley 2361 system. Nucleation of graphene domains with an average domain size of ~20 μm was observed when the growth time is 9 min that has full covered on the Cu surface. The Raman spectroscopy show that the frequency of the 2D band down-shifts with B doping, consistent with the increase of the in-plane lattice constant, and a weakening of the B-C in-plane bond strength relative to that of C-C bond. Also the shifts of the G-band frequencies can be interpreted in terms of the size of the C-C ring and the changes in the electronic structure of graphene in the presence of boron atoms. The study of electrical property shows that by increasing the grow time the conductance increases which this result in agree with SEM images and graphene grain boundary. Also by increasing the boron percentage in gas mixer the conductance decreases since doping graphene with boron creates a band-gap in graphene band structure. The XPS results of B doped graphene confirm the existence of boron in doped graphene, which indicates the boron atoms doped in the graphene lattice are mainly in the form of BC3. The results showed that boron-doped graphene can be successfully synthesized using boron oxide powder and ethanol vapor via a HFCVD method and also chemical boron doping can be change the electrical conductivity of the graphene.

  5. A facile aqueous strategy for the synthesis of high-brightness LaPO{sub 4}:Eu nanocrystals via controlling the nucleation and growth process

    Energy Technology Data Exchange (ETDEWEB)

    Che, Dongchen; Zhu, Xiaoxu [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201602 (China); Liu, Peifeng; Duan, Yourong [Cancer Institute of Shanghai Jiao Tong University, Shanghai 200032 (China); Wang, Hongzhi, E-mail: wanghz@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201602 (China); Zhang, Qinghong [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201602 (China); Li, Yaogang, E-mail: yaogang_li@dhu.edu.cn [Engineering Research Center of Advanced Glass Manufacturing Technology, Ministry of Education, Donghua University, Shanghai 201602 (China)

    2014-09-15

    Ellipsoidal nanocrystalline LaPO{sub 4}:Eu has been realized through an aqueous method by using microwave irradiation and microfluidic system. Through this method, we can control the nucleation and growth process. The as-prepared nanoparticles are pure monazite phase and water-dispersible and monodisperse, with a mean diameter of 4 nm and length of 6 nm. Luminescence data indicate the samples have a strong orange–red emission corresponding to {sup 5}D{sub 0}→{sup 7}F{sub 1} transition. Under the optimized conditions, the quantum yield is 21%. According to MTT assay, the nanoparticles are non-toxic materials and good biocompatibility. Therefore the LaPO{sub 4}:Eu nanoparticles may possess the potential to serve as a luminescent bioimaging probe. - Highlights: • We synthesize LaPO{sub 4}:Eu nanocrystals by controlling the nucleation and growth process. • The LaPO{sub 4}:Eu nanocrystals are obtained from a microfluidic reactor using microwave. • The LaPO{sub 4}:Eu nanocrystals are water-dispersible and monodisperse. • The LaPO{sub 4}:Eu nanocrystals show superior fluorescence with low cytotoxicity.

  6. High-Rate Growth and Nitrogen Distribution in Homoepitaxial Chemical Vapour Deposited Single-crystal Diamond

    Institute of Scientific and Technical Information of China (English)

    LI Hong-Dong; ZOU Guang-Tian; WANG Qi-Liang; CHENG Shao-Heng; LI Bo; L(U) Jian-Nan; L(U) Xian-Yi; JIN Zeng-Sun

    2008-01-01

    High rate (> 50 μm/h) growth of homoepitaxial single-crystal diamond (SCD) is carried out by microwave plasma chemical vapour deposition (MPCVD) with added nitrogen in the reactant gases of methane and hydrogen,using a polycrystalline-CVD-diamond-film-made seed holder. Photoluminescence results indicate that the nitrogen concentration is spatially inhomogeneous in a large scale,either on the top surface or in the bulk of those as-grown SCDs.The presence of N-distribution is attributed to the facts: (I) a difference in N-incorporation efficiency and (ii) N-diffusion,resulting from the local growth temperatures changed during the high-rate deposition process.In addition,the formed nitrogen-vacancy centres play a crucial role in N-diffusion through the growing crystal.Based on the N-distribution observed in the as-grown crystals,we propose a simple method to distinguish natural diamonds and man-made CVD SCDs.Finally,the disappearance of void defect on the top surface of SCDs is discussed to be related to a filling-in mechanism.

  7. Effect of Chemical Structure on Polymer-Templated Growth of Graphitic Nanoribbons.

    Science.gov (United States)

    Liu, Nan; Kim, Kwanpyo; Jeong, Hu Young; Hsu, Po-Chun; Cui, Yi; Bao, Zhenan

    2015-09-22

    Graphene nanoribbon (GNR) is an important candidate for future nanoelectronics due to its high carrier mobility and dimension-controlled band gap. Polymer-templated growth is a promising method toward high quality and massive production of GNRs. However, the obtained GNRs so far are still quite defective. In order to rationally control the crystallinity of the synthesized GNRs, herein we systematically investigate the effect of polymer chemical structure on their templated growth of GNRs. We studied the morphology/dimensions, composition, graphitization degree, and electrical conductivity of GNRs derived from four different types of electrospun polymers. The four polymers polystyrene (PS), poly(vinyl alcohol) (PVA), polyvinylphenol (PVP), and Novolac (a phenolic resin) are chosen to investigate the effect of metal binding and the effect of aromatic moieties. We found that metal-binding functional groups are crucial for obtaining uniform and continuous GNRs. On the other hand, a polymer with aromatic moieties leads to a higher sp(2) percentage in the resulting GNRs, showing a higher graphitization degree and electrical conductivity. PMID:26267798

  8. Ultrasmooth metallic foils for growth of high quality graphene by chemical vapor deposition

    Science.gov (United States)

    Procházka, Pavel; Mach, Jindřich; Bischoff, Dominik; Lišková, Zuzana; Dvořák, Petr; Vaňatka, Marek; Simonet, Pauline; Varlet, Anastasia; Hemzal, Dušan; Petrenec, Martin; Kalina, Lukáš; Bartošík, Miroslav; Ensslin, Klaus; Varga, Peter; Čechal, Jan; Šikola, Tomáš

    2014-05-01

    Synthesis of graphene by chemical vapor deposition is a promising route for manufacturing large-scale high-quality graphene for electronic applications. The quality of the employed substrates plays a crucial role, since the surface roughness and defects alter the graphene growth and cause difficulties in the subsequent graphene transfer. Here, we report on ultrasmooth high-purity copper foils prepared by sputter deposition of Cu thin film on a SiO2/Si template, and the subsequent peeling off of the metallic layer from the template. The surface displays a low level of oxidation and contamination, and the roughness of the foil surface is generally defined by the template, and was below 0.6 nm even on a large scale. The roughness and grain size increase occurred during both the annealing of the foils, and catalytic growth of graphene from methane (≈1000 °C), but on the large scale still remained far below the roughness typical for commercial foils. The micro-Raman spectroscopy and transport measurements proved the high quality of graphene grown on such foils, and the room temperature mobility of the graphene grown on the template stripped foil was three times higher compared to that of one grown on the commercial copper foil. The presented high-quality copper foils are expected to provide large-area substrates for the production of graphene suitable for electronic applications.

  9. Triggering the Growth of Large Single Crystal Graphene by Chemical Vapor Deposition

    Science.gov (United States)

    Wu, Tianru; Wang, Haomin; Ding, Guqiao; Jiang, Da; Xie, Xiaoming; Jiang, Mianheng

    2013-03-01

    Graphene, a monolayer of sp2 carbon atoms, has been attracting great interests as an ideal two dimensional crystalline material. Fabrication technique for wafer scale graphene via chemical vapor deposition (CVD) was developed several years ago. However, large scale graphene films from CVD method so far are found to be polycrystalline, consisting of numerous grain boundaries, which greatly degrade the electrical and mechanical properties of graphene. Recently, we obtained hexagonal-shaped single-crystal monolayer graphene domains (~1.2 mm). We adapted a strategy to synthesize larger size single crystal grains by regulating the supply of reactants and hytrogen. Nucleation density can be decreased to less than 1000 nuclei /m2. Gradually increase in the supply of reactants could break the equilibrium of growth and etching at the edge of hexagonal-shaped graphene grains. It drives the reaction toward quick growth of graphene domains during the whole CVD process. The graphene grains we obtained show high crystalline quality with high mobility of ~13000 cm2V-1s-1, which is comparable to that of exfoliated graphene. The results achieved will definitely benefit for further practical application of graphene electronics.

  10. Synthesis of SiC nanostructures through chemical vapor growth route

    Energy Technology Data Exchange (ETDEWEB)

    Chiew, Y.L. [Energy Efficiency and Sustainable Semiconductor Research Group, School of Materials and Mineral Resources Engineering, Engineering Campus, University Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Cheong, K.Y.

    2012-05-15

    In this study, SiC nanorods and nanocolumns were synthesized using a catalyst-free method with activated carbon powder and oxidized silicon wafer (oxidation time of the wafer varied from 1 to 12 min to produce different SiO{sub 2} thickness) as source materials. SiC nanorods were mostly found at the center of silicon wafer that was exposed to activated carbon powder while SiC nanocolumns were mostly found at the side of the wafer where it was in direct contact with graphite crucible. When thicker SiO{sub 2} was used, SiC nanorods at the center tended to agglomerate together into particles. SiC nanocolumns at the side of the wafer were also increased in amount as the oxidation time increased. Growth of SiC nanorods and nanocolumns could be attributed to chemical vapor growth via vapor-solid mechanism. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Analysis of Puerarin and Chemical Compositions Changes in Kudzu Root during Growth Period

    Directory of Open Access Journals (Sweden)

    Yiguo Zhao

    2014-01-01

    Full Text Available The kudzu root is one of the earliest medicinal plants listed in traditional Chinese medicine. In this paper, chemical compositions changes of kudzu roots from one year old to five years old were analyzed with respect to puerarin, acid-insoluble polysaccharides, acid-soluble polysaccharides, reducing sugar, protein, free amino acids, and lipid. In addition, the puerarin content was determined by high performance liquid chromatography (HPLC method. The results showed that acid-soluble polysaccharides content of kudzu root increased with each growth period. In contrast, the acid-insoluble polysaccharides decreased significantly. The contents of reducing sugar and puerarin in kudzu root decreased significantly during its growth period. Beyond that, the contents of protein, free amino acids, and lipid in kudzu root ranged from 31.8 to 45.8 g/kg, 2.21 to 4.33 g/kg, and 32.2 to 76.9 g/kg, respectively. The trend of protein content coincided with the total content of free amino acids, in contrast to lipid. This paper provides a set of data and the select of kudzu root for the processing and development of new products of kudzu root.

  12. Basic fibroblast growth factor protects against excitotoxicity and chemical hypoxia in both neonatal and adult rats.

    Science.gov (United States)

    Kirschner, P B; Henshaw, R; Weise, J; Trubetskoy, V; Finklestein, S; Schulz, J B; Beal, M F

    1995-07-01

    Basic fibroblast growth factor (bFGF) is a polypeptide growth factor that promotes neuronal survival. We recently found that systemic administration of bFGF protects against both excitotoxicity and hypoxia-ischemia in neonatal animals. In the present study, we examined whether systemically administered bFGF could prevent neuronal death induced by intrastriatal injection of N-methyl-D-aspartate (NMDA) or chemical hypoxia induced by intrastriatal injection of malonate in adult rats and 1-methyl-4-phenylpyridinium (MPP+) in neonatal rats. Systemic administration of bFGF (100 micrograms/kg) for three doses both before and after intrastriatal injection of either NMDA or malonate in adult rats produced a significant neuroprotective effect. In neonatal rats, bFGF produced dose-dependent significant neuroprotective effects against MPP+ neurotoxicity, with a maximal protection of approximately 50% seen with either a single dose of bFGF of 300 micrograms/kg or three doses of 100 micrograms/kg. These results show that systemic administration of bFGF is effective in preventing neuronal injury under circumstances in which the blood-brain barrier may be compromised, raising the possibility that this strategy could be effective in stroke.

  13. Application of high resolution Chemical Ionization Mass Spectrometry (CI-ToFMS to study SOA composition: focus on formation of oxygenated species via aqueous phase processing

    Directory of Open Access Journals (Sweden)

    D. Aljawhary

    2013-07-01

    Full Text Available This paper demonstrates the capabilities of Chemical Ionization Mass Spectrometry (CIMS to study secondary organic aerosol (SOA composition with a high resolution (HR time-of-flight mass analyzer (aerosol-CI-ToFMS. In particular, by studying aqueous oxidation of Water Soluble Organic Compounds (WSOC extracted from α-pinene ozonolysis SOA, we assess the capabilities of three common CIMS reagent ions: (a protonated water clusters (H2OnH+, (b acetate CH3C(OO− and (c iodide water clusters I(H2On− to monitor SOA composition. As well, we report the relative sensitivity of these reagent ions to a wide range of common organic aerosol constituents. We find that (H2OnH+ is more selective to the detection of less oxidized species, so that the range of O/C and OSC (carbon oxidation state in the SOA spectra is considerably lower than those measured using CH3C(OO− and I(H2On−. Specifically, (H2OnH+ ionizes organic compounds with OSC ≤ 1.3, whereas CH3C(OO− and I(H2On− both ionize highly oxygenated organics with OSC up to 4 with I(H2On− being more selective towards multi-functional organic compounds. In the bulk O/C and H/C space, i.e. in a Van Krevelen plot, there is a remarkable agreement in both absolute magnitude and oxidation trajectory between CI-ToFMS data and those from a high resolution aerosol mass spectrometer (HR-AMS. This indicates that the CI-ToFMS data captures much of the chemical change occurring in the particle and that gas phase species, which are not detected by the HR-AMS, do not dominate the overall ion signal. Finally, the data illustrate the capability of aerosol-CI-ToFMS to monitor specific chemical change, including the fragmentation and functionalization reactions that occur during organic oxidation, and the oxidative conversion of dimeric SOA species into monomers. Overall, aerosol-CI-ToFMS is a valuable, selective complement to some common SOA characterization methods, such as AMS and spectroscopic techniques. Both

  14. Growth process conditions of tungsten oxide thin films using hot-wire chemical vapor deposition

    International Nuclear Information System (INIS)

    Highlights: ► Process parameters to control hot-wire CVD of WO3−x are categorized. ► Growth time, oxygen partial pressure, filament and substrate temperature are varied. ► Chemical and crystal structure, optical bandgap and morphology are determined. ► Oxygen partial pressure determines the deposition rate up to as high as 36 μm min−1. ► Nanostructures, viz. wires, crystallites and closed crystallite films, are controllably deposited. - Abstract: We report the growth conditions of nanostructured tungsten oxide (WO3−x) thin films using hot-wire chemical vapor deposition (HWCVD). Two tungsten filaments were resistively heated to various temperatures and exposed to an air flow at various subatmospheric pressures. The oxygen partial pressure was varied from 6.0 × 10−6 to 1.0 mbar and the current through the filaments was varied from 4.0 to 9.0 A, which constitutes a filament temperature of 1390–2340 °C in vacuum. It is observed that the deposition rate of the films is predominantly determined by the oxygen partial pressure; it changes from about 1 to about 36,000 nm min−1 in the investigated range. Regardless of the oxygen partial pressure and filament temperature used, thin films with a nanogranular morphology are obtained, provided that the depositions last for 30 min or shorter. The films consist either of amorphous or partially crystallized WO3−x with high averaged transparencies of over 70% and an indirect optical band gap of 3.3 ± 0.1 eV. A prolonged deposition time entails an extended exposure of the films to thermal radiation from the filaments, which causes crystallization to monoclinic WO3 with diffraction maxima due to the (0 0 2), (2 0 0) and (0 2 0) crystallographic planes, furthermore the nanograins sinter and the films exhibit a cone-shaped growth. By simultaneously influencing the surface mobility, by heating the substrates to Tsurface = 700 ± 100 °C, and the deposition rate, a very good control of the morphology of the

  15. Sonoran propolis and some of its chemical constituents inhibit in vitro growth of Giardia lamblia trophozoites.

    Science.gov (United States)

    Alday-Provencio, Samuel; Diaz, Gabriela; Rascon, Lucila; Quintero, Jael; Alday, Efrain; Robles-Zepeda, Ramón; Garibay-Escobar, Adriana; Astiazaran, Humberto; Hernandez, Javier; Velazquez, Carlos

    2015-06-01

    Propolis is a cereus resin with a complex chemical composition that possesses a wide range of biological activities. The aim of this study was to evaluate the in vitro anti-Giardia lamblia activity of Sonoran propolis collected from three different areas of Sonoran Desert in northwestern Mexico (Caborca, Pueblo de Alamos, and Ures) and some of its chemical constituents. Additionally, we also analyzed the seasonal effect on the anti-G. lamblia activity of propolis. G. lamblia trophozoite cultures were treated with different concentrations of Sonoran propolis or chemical compounds during 48 h cell proliferation and cell viability were determined. Ures propolis showed the highest inhibitory activity against G. lamblia (IC50 63.8 ± 7.1 µg/mL) in a dose-dependent manner (Ures > Pueblo de Alamos > Caborca). Season had a significant effect on the in vitro anti-G. lamblia activity of Ures propolis. Summer propolis showed the highest inhibitory effect on the G. lamblia trophozoite growth (IC50 23.8 ± 2.3 µg/mL), followed by propolis collected during winter (IC50 59.2 ± 34.7 µg/mL), spring (IC50 102.5 ± 15.3 µg/mL), and autumn (IC50 125.0 ± 3.1 µg/mL). Caffeic acid phenethyl ester, an Ures propolis exclusive constituent, had the highest growth-inhibitory activity towards G. lamblia [IC50 63.1 ± 0.9 µg/mL (222.1 ± 3.2 µM)]. To our knowledge, this is the first study showing that caffeic acid phenethyl ester possesses antiparasitic activity against G. lamblia. Naringenin [IC50 125.7 ± 20.7 µg/mL (461.8 ± 76.3 µM)], hesperetin [IC50 149.6 ± 24.8 µg/mL (494.9 ± 82.2 µM)], and pinocembrin [IC50 174.4 ± 26.0 µg/mL (680.6 ± 101.7 µM)] showed weak anti-G. lamblia activity. On the other hand, chrysin and rutin did not show significant antiparasitic activity. In conclusion, our results suggest that Sonoran propolis and some of its chemical constituents had inhibitory effects on the

  16. Influence of vitamin c and e enriched feeding on growth and chemical composition of red tilapia (Oreochromis spp.

    Directory of Open Access Journals (Sweden)

    Adrianyela NORIEGA- SALAZAR

    2014-08-01

    Full Text Available The objective of this study was determining the influence of enriched feeding with vitamin C and E on growth and chemical composition of red tilapia (Oreochromis spp.. A completely randomized design was used in this experiment. No statistically significant differences were observed for humidity, while all other parameters evaluated in this study showed differences. The results obtained showed enhanced growth in terms of size, weight and growth rate, and a 100% survival in the fish using the combination of vitamin C and E. The chemical characterization indicated that protein ranged from 20.36% to 21.56%, humidity from 73.04% to 76.52%, ash from 1.29% to 3.27% and ether extract from1.83% to 3.23% for treatments 1 and 4. The obtained results suggest that the fish growth increased and red tilapia steaks have high nutritional value using the fodder in combination with vitamin C and E.

  17. Controllable Growth of the Graphene from Millimeter-Sized Monolayer to Multilayer on Cu by Chemical Vapor Deposition

    Science.gov (United States)

    Liu, Jinyang; Huang, Zhigao; Lai, Fachun; Lin, Limei; Xu, Yangyang; Zuo, Chuandong; Zheng, Weifeng; Qu, Yan

    2015-11-01

    As is well established, mastery to precise control of the layer number, stacking order of graphene, and the size of single-crystal monolayer graphene is very important for both fundamental interest and practical applications. In this report, millimeter-sized single-crystal monolayer graphene has been synthesized to multilayer graphene on Cu by chemical vapor deposition. The relationship of the growth process between monolayer graphene and multilayer graphene is investigated carefully. Besides the general multilayer graphene with Bernal stacking order, parts of multilayer graphene with non-Bernal stacking order were modulated under optimized growth conditions. The oxide nanoparticle on the Cu surface derived from annealing has been found to play the key role in nucleation. In addition, the hydrogen concentration impacts significantly on the layer number and shape of the graphene. Moreover, a possible mechanism was proposed to understand the growth process discussed above, which may provide an instruction to graphene growth on Cu by chemical vapor deposition.

  18. Meta-code for systematic analysis of chemical addition (SACHA): application to fluorination of C70 and carbon nanostructure growth.

    Science.gov (United States)

    Ewels, Christopher P; Lier, Gregory Van; Geerlings, Paul; Charlier, Jean-Christophe

    2007-01-01

    We present a new computer program able to systematically study chemical addition to and growth or evolution of carbon nanostructures. SACHA is a meta-code able to exploit a wide variety of pre-existing molecular structure codes, automating the otherwise onerous task of constructing, running, and analyzing the large number of input files that are required when exploring structural isomers and addition paths. By way of examples we consider fluorination of the fullerene cage C70 and carbon nanostructure growth through C2 addition. We discuss the possibilities for extension of this technique to rapidly and efficiently explore structural energy landscapes and application to other areas of chemical and materials research.

  19. Physical and Chemical Properties of Water Treatment Residue and the Characteristics of Red Pepper Growth by Using it

    OpenAIRE

    Park, Seok-Gon; Yahata, Hisashi; Kurosawa, Kiyoshi; Shin, Hyun-Tak

    2010-01-01

    Physical and chemical properties of the water treatment residue (WTR) and the WTR_, which contained compost (CP), were measured, and the effect of the properties on growth of the red pepper (Capsicum annuum‘Takanotsume’) was studied to reuse the WTR as an alternative material for decomposed granite soil (DGS). The physical properties of relative gas diffusivity (D/D_0), saturated hydraulic conductivity (K_s), water retention curve, porosity and plant-available water, and the chemical propert...

  20. Chemical allergens stimulate human epidermal keratinocytes to produce lymphangiogenic vascular endothelial growth factor

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Ok-Nam [College of Pharmacy, Institute of Pharmaceutical Science and Technology, Hanyang University, Ansan 426-791 (Korea, Republic of); Ahn, Seyeon; Jin, Sun Hee; Hong, Soo Hyun; Lee, Jinyoung [College of Pharmacy, Natural Products Research Institute, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, Eun-Sun [College of Pharmacy, Institute of Pharmaceutical Science and Technology, Hanyang University, Ansan 426-791 (Korea, Republic of); Jeong, Tae Cheon [College of Pharmacy, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Chun, Young-Jin [College of Pharmacy, Chung-Ang University, Seoul 156-756 (Korea, Republic of); Lee, Ai-Young, E-mail: leeay@duih.org [Department of Dermatology, Dongguk University Ilsan Hospital, Goyang 410-773 (Korea, Republic of); Noh, Minsoo, E-mail: minsoo@alum.mit.edu [College of Pharmacy, Natural Products Research Institute, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2015-03-01

    Allergic contact dermatitis (ACD) is a cell-mediated immune response that involves skin sensitization in response to contact with various allergens. Angiogenesis and lymphangiogenesis both play roles in the allergic sensitization process. Epidermal keratinocytes can produce vascular endothelial growth factor (VEGF) in response to UV irradiation and during wound healing. However, the effect of haptenic chemical allergens on the VEGF production of human keratinocytes, which is the primary contact site of toxic allergens, has not been thoroughly researched. We systematically investigated whether immune-regulatory cytokines and chemical allergens would lead to the production of VEGF in normal human keratinocytes (NHKs) in culture. VEGF production significantly increased when NHKs were treated with IFNγ, IL-1α, IL-4, IL-6, IL-17A, IL-22 or TNFα. Among the human sensitizers listed in the OECD Test Guideline (TG) 429, we found that CMI/MI, DNCB, 4-phenylenediamine, cobalt chloride, 2-mercaptobenzothiazole, citral, HCA, cinnamic alcohol, imidazolidinyl urea and nickel chloride all significantly upregulated VEGF production in NHKs. In addition, common human haptenic allergens such as avobenzone, formaldehyde and urushiol, also induced the keratinocyte-derived VEGF production. VEGF upregulation by pro-inflammatory stimuli, IFNγ, DNCB or formaldehyde is preceded by the production of IL-8, an acute inflammatory phase cytokine. Lymphangiogenic VEGF-C gene transcription was significantly increased when NHKs were treated with formaldehyde, DNCB or urushiol, while transcription of VEGF-A and VEGF-B did not change. Therefore, the chemical allergen-induced VEGF upregulation is mainly due to the increase in lymphangiogenic VEGF-C transcription in NHKs. These results suggest that keratinocyte-derived VEGF may regulate the lymphangiogenic process during the skin sensitization process of ACD. - Highlights: • Pro-inflammatory cytokines induced VEGF production in normal human

  1. Chemical allergens stimulate human epidermal keratinocytes to produce lymphangiogenic vascular endothelial growth factor

    International Nuclear Information System (INIS)

    Allergic contact dermatitis (ACD) is a cell-mediated immune response that involves skin sensitization in response to contact with various allergens. Angiogenesis and lymphangiogenesis both play roles in the allergic sensitization process. Epidermal keratinocytes can produce vascular endothelial growth factor (VEGF) in response to UV irradiation and during wound healing. However, the effect of haptenic chemical allergens on the VEGF production of human keratinocytes, which is the primary contact site of toxic allergens, has not been thoroughly researched. We systematically investigated whether immune-regulatory cytokines and chemical allergens would lead to the production of VEGF in normal human keratinocytes (NHKs) in culture. VEGF production significantly increased when NHKs were treated with IFNγ, IL-1α, IL-4, IL-6, IL-17A, IL-22 or TNFα. Among the human sensitizers listed in the OECD Test Guideline (TG) 429, we found that CMI/MI, DNCB, 4-phenylenediamine, cobalt chloride, 2-mercaptobenzothiazole, citral, HCA, cinnamic alcohol, imidazolidinyl urea and nickel chloride all significantly upregulated VEGF production in NHKs. In addition, common human haptenic allergens such as avobenzone, formaldehyde and urushiol, also induced the keratinocyte-derived VEGF production. VEGF upregulation by pro-inflammatory stimuli, IFNγ, DNCB or formaldehyde is preceded by the production of IL-8, an acute inflammatory phase cytokine. Lymphangiogenic VEGF-C gene transcription was significantly increased when NHKs were treated with formaldehyde, DNCB or urushiol, while transcription of VEGF-A and VEGF-B did not change. Therefore, the chemical allergen-induced VEGF upregulation is mainly due to the increase in lymphangiogenic VEGF-C transcription in NHKs. These results suggest that keratinocyte-derived VEGF may regulate the lymphangiogenic process during the skin sensitization process of ACD. - Highlights: • Pro-inflammatory cytokines induced VEGF production in normal human

  2. Growth and chemical composition of chicory and performance of lambs grazing chicory relative to grass–clover mixtures

    OpenAIRE

    Kidane, Alemayehu; Sørheim, Kristin; Eik, Lars Olav; Steinshamn, Håvard

    2014-01-01

    We report results from trials on chicory growth (experiment 1) and lamb growth on chicory (experiment 2). In experiment 1, we assessed yield and chemical composition on swards established under organic conditions as perennial ryegrass/red clover, perennial ryegrass/chicory, chicory/red clover (CHRC), pure perennial ryegrass (RG-alone) and pure chicory (CHalone) over two years. Chicory/red clover and CH-alone showed improved crude protein, Ca, Mg, P, Cu and net energy contents comp...

  3. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Directory of Open Access Journals (Sweden)

    Hatim Alnoor

    2015-08-01

    Full Text Available Hexagonal c-axis oriented zinc oxide (ZnO nanorods (NRs with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL spectra were collected for all samples. Cathodoluminescence (CL spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE to the deep-level emission (DLE peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h, which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  4. Chemically driven growth of tungsten grains during liquid phase sintering of W-Ni-Fe alloys

    International Nuclear Information System (INIS)

    In the alloys where the solid grains immersed in liquid matrix grow by Ostwald ripening process, the growth rate can be suddenly altered by changing the matrix composition. In this study, W-Ni-(Fe) specimens have been sintered and annealed at the temperatures around 15000C until the grains have coarsened, and then annealed further after adding Fe or Ni. After adding Fe or Ni and further annealing treatments, strong etching has revealed that a new solid phase in equilibrium with the changed matrix composition has been deposited preferentially on the larger grains. The smaller grains, which would be dissolving continuously, have maintained the old composition. This composition difference between the new solid phase on the larger grains and the old solid phase on the smaller ones can provide a driving force for grain coarsening in addition to that arising from the size difference. When Fe is added to sintered W-Ni, the grain coarsening rate during further annealing momentarily increases. The calculation shows that the molar free energy of the new solid phase should be lower than that of the old solid phase. Therefore, the solution reprecipitation process is ascelerated by this chemical free energy difference. If, on the other hand, Ni is added to sintered W-Ni-Fe, the coarsening rate decreases during further annealing. The calculation shows indeed that in this case the new solid phase should have higher molar free energy than the old. It is therefore demonstrated that if the matrix composition is altered during Ostwald ripening, the grain coarsening can be accelerated or retarded because of the chemical composition difference between the old grains and the newly precipitated solid phase on the larger grains. (author)

  5. Growth of Mg-doped InN by Metal Organic Chemical Vapor Deposition

    Science.gov (United States)

    Khan, N.; Nepal, N.; Lin, J. Y.; Jiang, H. X.

    2007-03-01

    InN with an energy gap of ˜ 0.7 eV, has recently attracted extensive attention due to its potential applications in semiconductor devices such as light emitting diodes, lasers, and high efficiency solar cells. However the ability to grow both p-type and n-type InN is essential to realize these devices. All as grown unintentionally doped InN are n-type. The tendency of native defects in InN to form donors manifests itself severely at surfaces where high levels of electron accumulation are observed. The highly n-type conductive layer at the surface of InN films creates difficulties in the demonstration of p-type InN. Nevertheless it is important to investigate the optical and structural properties of Mg-doped InN. We report here on the growth of Mg-doped InN epilayers by metal organic chemical vapor deposition. Photoluminescence (PL) was employed to study the effects of different growth conditions of Mg-doped InN. PL studies revealed that in addition to emission peak at ˜ 0.82 eV in undoped InN layers, Mg-doped InN layers exhibit an emission peak at ˜ 0.75 eV. The peak at ˜ 0.75eV for Mg-doped InN could be related to defects generated by Mg doping in InN. Various other measurements such as Hall effect measurement, X-ray diffraction and atomic force microscopy were carried out to provide further understanding.

  6. Effects of Organic and Chemical Fertilizations and Microbe Inoculation on Physiology and Growth ofSweet Corn Plants

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A pot culture experiment was carried out in a glasshouse to compare the physiology and growth of sweet corn plants (Zea mays L. cv. Honey Bantam) grown under organic and chemical fertilizations with or without microbial inoculation (MI). The organic fertilizer used was fermented mainly using rice bran and oil mill sludge, and the MI was a liquid product containing many beneficial microbes such as lactic acid bacteria, yeast, photosynthetic bacteria and actinomycetes. The application amounts of the organic fertilizer and chemical fertilizers were based on the same rate of nitrogen, phosphorus and potassium. Sweet corn plants fertilized with organic materials inoculated with beneficial microbes grew better than those without inoculation. There were no significant differences in physiology and growth of the sweet corn plants between treatments of chemical fertilizers with and without MI. Among the organic fertilization treatments, only the sweet corn plants with organic fertilizer and MI applied 4 weeks before sowing had similar photosynthetic capacity, total dry matter yield and ear yield to those with chemical fertilizers. Sweet corn plants in other organic fertilization treatments were weaker in physiology and growth than those in chemical fertilization treatments. There was no significant variance among chemical fertilization treatments at different time. It is concluded from this research that this organic fertilizer would be more effective if it was inoculated with the beneficial microbes. Early application of the organic fertilizer with beneficial microbes before sowing was recommended to make the nutrients available before the rapid growth at the early stage and obtain a yield similar to or higher than that with chemical fertilizations.

  7. Effect of aqueous extract of Melia azedarach L. leaves on the growth and development of ovary and histological structure of the mid gut in the housefly, Musca domestica L. (Diptera : Muscidae

    Directory of Open Access Journals (Sweden)

    N. S. Gorgees

    2008-01-01

    Full Text Available Four sub lethal concentrations 0.5, 1, 2.5, 5% of aqueous extract of Melia azedarach L. were used against the second instars larvae of the housefly, Musca domestica L.. The results of the microscopical preparations and statistical analysis have shown that this aqueous extract had a significant inhibitory effect on the growth and development on the ovaries and ovarian follicles of the adult flies obtained from previously treated larvae with four stage of age, 24, 48, 72, 96 hour after birth. The extract also led decreased in the numbers of ovarian follicles and their degradation. In some instances the microscopically preparations of the mid gut of the housefly have also shown that this aqueous extract has seriously affected the histological structure of the alimentary canal particularly the mid gut. It has led to the separation of the muscular layer from the epithelial lining.

  8. Water-compatible dummy molecularly imprinted resin prepared in aqueous solution for green miniaturized solid-phase extraction of plant growth regulators.

    Science.gov (United States)

    Wang, Mingyu; Chang, Xiaochen; Wu, Xingyu; Yan, Hongyuan; Qiao, Fengxia

    2016-08-01

    A water-compatible dummy molecularly imprinted resin (MIR) was synthesized in water using melamine, urea, and formaldehyde as hydrophilic monomers of co-polycondensation. A triblock copolymer (PEO-PPO-PEO, P123) was used as porogen to dredge the network structure of MIR, and N-(1-naphthyl) ethylenediamine dihydrochloride, which has similar shape and size to the target analytes, was the dummy template of molecular imprinting. The obtained MIR was used as the adsorbent in a green miniaturized solid-phase extraction (MIR⬜mini-SPE) of plant growth regulators, and there was no organic solvent used in the entire MIR⬜mini-SPE procedure. The calibration linearity of MIR⬜mini-SPE⬜HPLC method was obtained in a range 5⬜250ngmL(↙1) for IAA, IPA, IBA, and NAA with correlation coefficient (r) Ⱕ0.9998. Recoveries at three spike levels are in the range of 87.6⬜100.0% for coconut juice with relative standard deviations Ⱔ8.1%. The MIR⬜mini-SPE method possesses the advantages of environmental friendliness, simple operation, and high efficiency, so it is potential to apply the green pretreatment strategy to extraction of trace analytes in aqueous samples. PMID:27378249

  9. Water-compatible dummy molecularly imprinted resin prepared in aqueous solution for green miniaturized solid-phase extraction of plant growth regulators.

    Science.gov (United States)

    Wang, Mingyu; Chang, Xiaochen; Wu, Xingyu; Yan, Hongyuan; Qiao, Fengxia

    2016-08-01

    A water-compatible dummy molecularly imprinted resin (MIR) was synthesized in water using melamine, urea, and formaldehyde as hydrophilic monomers of co-polycondensation. A triblock copolymer (PEO-PPO-PEO, P123) was used as porogen to dredge the network structure of MIR, and N-(1-naphthyl) ethylenediamine dihydrochloride, which has similar shape and size to the target analytes, was the dummy template of molecular imprinting. The obtained MIR was used as the adsorbent in a green miniaturized solid-phase extraction (MIR⬜mini-SPE) of plant growth regulators, and there was no organic solvent used in the entire MIR⬜mini-SPE procedure. The calibration linearity of MIR⬜mini-SPE⬜HPLC method was obtained in a range 5⬜250ngmL(↙1) for IAA, IPA, IBA, and NAA with correlation coefficient (r) Ⱕ0.9998. Recoveries at three spike levels are in the range of 87.6⬜100.0% for coconut juice with relative standard deviations Ⱔ8.1%. The MIR⬜mini-SPE method possesses the advantages of environmental friendliness, simple operation, and high efficiency, so it is potential to apply the green pretreatment strategy to extraction of trace analytes in aqueous samples.

  10. Effect of different growth stages of Ziziphora clinopodioides Lam. on its chemical composition

    Directory of Open Access Journals (Sweden)

    Wenhuan Ding

    2014-01-01

    Full Text Available Aims: The aim of this study is to monitor the changes in the chemical composition of Ziziphora clinopodioides Lam. throughout nine different growth stages. Materials and Methods: Volatile components such as essential oils were analyzed using the gas chromatography (GC and GC-mass spectrometry, and the contents of non-volatile components were determined by a visible spectrophotometer. Results: Hydro-distilled essential oil content ranged from a minimum of 1.1% (in the post-flowering stage to a maximum of 1.8% (in the flowering stage. The essential oils included pulegone, which was the most abundant component (77.48-87.3%, p-menthanone (2.79-12.39%, trans-isopulegone (1.04-2.06%, d-limonene (0.51-3.03% and eucarvone (1.5-4.48%. The contents of non-volatile components, such as that of total phenolics (TPC, total flavonoids (TFC, total triterpenoids content (TTC and total free amino acids content (TFAAC were measured using visible spectrophotometry. In the growing stage, TPC, TFC, TTC and TFAAC were 9.91-12.80 mg/g, 29.84-50.63 mg/g, 0.57-1.41 mg/g and 13.33-28.56 mg/g, respectively. Conclusion: These data can be used as a basis to determine the optimal harvest time of Z. clinopodioide Lam.

  11. Growth of High TcYBaCuO Thin Films by Metalorganic Chemical Vapor Deposition

    Science.gov (United States)

    Kirlin, Peter S.; Binder, R.; Gardiner, R.; Brown, Duncan W.

    1990-03-01

    Thin films of YBa2Cu3O7-x were grown on MgO(100) by metalorganic chemical vapor deposition (MOCVD). Low pressure growth studies were carried out between 400 and 600°C using metal β-diketonate complexes as source reagents for Y, Ba, and Cu. As-deposited films were amorphous and a two stage annealing protocol was used in which fluorine was first removed in a Ar/H20 stream between 700 and 850°C, followed by calcination in flowing oxygen between 500 and 950°C. Scanning electron microscopy, X-ray diffraction and energy dispersive analysis indicate that good compositional and dimensional uniformity could be achieved. The temperature of the oxygen annealing step was shown to have a dramatic impact on the physical and electrical properties of the YBa2Cu307-x thin films. Annealing temperatures exceeding 910°C gave large crystallites and semiconducting resistivity above Tc; annealing temperatures below 910°C yielded films with metallic conductivity whose density and superconducting transition varied inversely with maximum annealing temperature. Optimized deposition/annealing protocols yielded films with a preferred c-axis orientation, R273/R100 ratios of 2, onsets as high as 94K and zero resistance exceeding 90K.

  12. Growth of titanium silicate thin films by photo-induced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Z.M.; Fang, Q.; Zhang, J.-Y.; Wu, J.X.; Di, Y.; Chen, W.; Chen, M.L.; Boyd, Ian W

    2004-04-01

    Titanium silicate thin films have been grown on Si substrates by photo-induced chemical vapor deposition using 222-nm ultraviolet excimer lamps. Titanium tetraisopropoxide (TTIP) and tetraethoxysilane (TEOS) were used as precursors. TTIP and TEOS were dissolved together in cyclohexane and introduced into the photochemical reaction chamber through a droplet injector vaporizer. The composition of the film was controlled by changing the ratio of TTIP to TEOS in the precursor solution. High quality titanium silicate films with various Ti/Si ratios and low carbon content have been achieved as revealed by X-ray photoelectron spectroscopy measurements. The atomic percentage of Ti content in the grown silicate films is significantly larger than that in the precursor solution. The films were measured to be 30-80 nm in thickness and 1.91-2.31 in refractive index by ellipsometry. Both the growth rate and refractive index increase with increasing Ti percentage in the silicate films. The evolution of Fourier transform infrared spectra of the silicate films with solution composition shows that the Ti-O-Si absorption at approximately 920 cm{sup -1} becomes stronger, while the Ti-O absorption at approximately 430 cm{sup -1} becomes weaker with decreasing Ti percentage in the solution. A small feature at {approx}1035 cm{sup -1} related to Si-O-Si bonds is also observed in the SiO{sub 2}-rich Ti silicate film.

  13. Support effect on carbon nanotube growth by methane chemical vapor deposition on cobalt catalysts

    International Nuclear Information System (INIS)

    The influence of the support on carbon nanotube production by methane chemical vapor deposition (CVD) on cobalt catalysts was investigated. N2 physisorption, X-ray diffractometry (XRD), temperature programmed reduction (TPR) and H2 and CO chemisorption techniques were used to characterize the structure of cobalt catalysts supported on different metal oxides (Al2O3, SiO2, Nb2O5 and TiO2). Raman spectroscopy, temperature programmed oxidation (TPO) and scanning electron microscopy (SEM) were used for the characterization and quantification of produced carbon species. On carbon nanotube growth, the catalyst produced three main carbon species: amorphous carbon, single walled carbon nanotubes (SWNT) and multi walled carbon nanotubes (MWNT). The characterization techniques showed that the catalyst selectivity to each kind of nanotube depended on the cobalt particle size distribution, which was influenced by the textural properties of the support. Co/TiO2 showed the highest selectivity towards single wall nanotube formation. This high selectivity results from the narrow size distribution of cobalt particles on TiO2. (author)

  14. Growth and characterization of bismuth selenide thin films by chemical vapor deposition

    Science.gov (United States)

    Brom, Joseph E.

    Topological insulators are a recently discovered class of materials that have garnered much interest due to their unique surface states. With its relatively high band gap (0.3eV) and nearly ideal band structure, Bi2Se 3 has been a primary material of interest in the study of topological insulating behavior. However, several factors have made this study difficult. Bi2Se3 typically has a high native selenium vacancy concentration, and selenium vacancies act as donors in the material, leading to a high bulk electron concentration. The surface of Bi2Se 3 has also been shown to be susceptible to environmental doping when exposed to ambient air. Combining these two factors means that Bi2Se 3 is usually highly n-type doped, making it difficult to study the surface conducting states by transport measurements. This study investigated the use of two different chemical vapor deposition (CVD) techniques for the growth of Bi2Se3 thin films on sapphire (001): hybrid physicalchemical vapor deposition (HPCVD) and metal-organic chemical vapor deposition (MOCVD). HPCVD is a process which combines the evaporation of elemental selenium with the thermal decomposition of trimethylbismuth (TMBi). The use of elemental selenium immediately around the substrate provides a high overpressure of selenium, allowing for reduction of the selenium vacancy concentration. Bi2Se3 films grown on sapphire were epitaxial and highly oriented parallel to the substrate giving rise to narrow X-ray rocking curves (full-width-at-half-maximum=160 arcsecs for (006) reflection) and 6-fold rotational symmetry as determined by phi scans. The structural properties were consistent with deposition via a van der Waals epitaxy process. The selenium to bismuth ratio (VI/V) ratio proved important for achieving a reduced electron concentration of TMBi) dimethylselenide (DMSe) as precursors. Epitaxial Bi 2Se3 films were also produced by MOCVD on sapphire, however, the electron concentrations were generally higher (1- 3x

  15. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  16. Tannin (Polyphenol) Stability in Aqueous Solutions

    Science.gov (United States)

    Understanding the chemical stability of tannins (polyphenolics) in soils is critical to understanding their biological activities and fate. We examined the stability of chemically defined tannins in aqueous solutions under conditions simulating natural and laboratory conditions. We evaluated tanni...

  17. Control of transport and magnetism in ferromagnetic semiconducting superlattices through growth conditions and chemical surface effects

    Science.gov (United States)

    Kreutz, Theodore Carlton

    2003-10-01

    Within the emerging area of spintronics, magnetic semiconductors have been the subject of many recent studies. Advances in magnetizing traditional semiconductors like GaAs, through the introduction of Mn, have been the focus of many experiments. Recently, studies have focused on ferromagnetic semiconducting superlattices, where half-monolayer MnAs planes are separated by GaAs spacers. These structures have only recently been grown, and it is of particular interest to discover the properties of this material, and if it can be used in future spintronic devices. We have studied changes in the magnetic and transport properties of ferromagnetic semiconducting superlattices as a function of temperature, superlattice period and substrate growth temperature. We have measured the resistance, Hall resistance and magnetoresistance over a wide range of temperatures. We see that as the period of the superlattice increases, the per-layer resistance and the Curie temperature reach saturation values at approximately the same value. We also find that electrical transport is predominantly through hopping conduction. The anomalous Hall effect dominates the Hall resistance. With the period fixed, we vary the substrate temperature during growth and observe that higher substrate temperatures lead to less resistive samples. Also, for samples with high substrate temperatures, we find that the anomalous Hall coefficient can flip in sign. We also observe changes in the magnetic anisotropy as we vary the period of the superlattice and the substrate temperature. We observe this change with planar Hall effect as well as SQUID magnetometry measurements. Samples with short periods show cubic magnetic anisotropy whereas samples with larger period show uniaxial anisotropy. We then determine the anisotropy constants for this material. We also see that the switching is dominated by domain pinning processes. Finally, we are able to change the Curie temperature of ½ ML MnAs planes in GaAs through the

  18. Slit2 promotes tumor growth and invasion in chemically induced skin carcinogenesis.

    Science.gov (United States)

    Qi, Cuiling; Lan, Haimei; Ye, Jie; Li, Weidong; Wei, Ping; Yang, Yang; Guo, Simei; Lan, Tian; Li, Jiangchao; Zhang, Qianqian; He, Xiaodong; Wang, Lijing

    2014-07-01

    Slit, a neuronal guidance cue, binds to Roundabout (Robo) receptors to modulate neuronal, leukocytic, and endothelial migration. Slit has been reported to have an important effect on tumor growth and metastasis. In the current study, we evaluated the role of Slit2 in skin tumor growth and invasion in mice using a two-step chemical carcinogenesis protocol. We found that Slit2 expression correlated with the loss of basement membrane in the samples of human skin squamous cell carcinoma at different stages of disease progression. Slit2-Tg mice developed significantly more skin tumors than wild-type mice. Furthermore, the skin tumors that occurred in Slit2-Tg mice were significantly larger than those in the wild-type mice 10 weeks after 7,12-dimethylbenz[a]anthracene initiation until the end of the experiment. We also found that pathological development of the wild-type mice was delayed compared with that of Slit2-Tg mice. To further investigate the mechanism of increasing tumors in Slit2-Tg mice, we analyzed the expression of 5-bromo-2'-deoxyuridine (BrdU) in mouse skin lesions and found that the number of BrdU-positive cells and microvessel density in skin lesions were significantly higher in Slit2-Tg mice than in wild-type mice. Histological staining of PAS and type IV collagen and the colocalization of Slit2 and type IV collagen demonstrated varying degrees of loss of the basement membrane in the skin lesions from Slit2-Tg mice that were at the stage of carcinoma in situ. However, the basement membrane was well defined in the wild-type mice. In addition, MMP2, but not MMP9, was upregulated in the skin tissue of Slit2-Tg mice. Interruption of Slit2-Robo1 signaling by the antibody R5 significantly repressed the invasive capability of the squamous cell carcinoma cell line A431. Taken together, our findings reveal that Slit2 promotes DMBA/TPA-induced skin tumorigenesis by increasing cell proliferation, microvessel density, and invasive behavior of cutaneous squamous

  19. Late Chondritic Additions and Planet and Planetesimal Growth: Evaluation of Physical and Chemical Mechanisms

    Science.gov (United States)

    Righter, Kevin

    2013-01-01

    Studies of terrestrial peridotite and martian and achondritic meteorites have led to the conclusion that addition of chondritic material to growing planets or planetesimals, after core formation, occurred on Earth, Mars, asteroid 4 Vesta, and the parent body of the angritic meteorites [1-4]. One study even proposed that this was a common process in the final stages of growth [5]. These conclusions are based almost entirely on the highly siderophile elements (HSE; Re, Au, Pt, Pd, Rh, Ru, Ir, Os). The HSE are a group of eight elements that have been used to argue for late accretion of chondritic material to the Earth after core formation was complete (e.g., [6]). This idea was originally proposed because the D(metal/silicate) values for the HSE are so high, yet their concentration in the mantle is too high to be consistent with such high Ds. The HSE also are present in chondritic relative abundances and hence require similar Ds if this is the result of core-mantle equilibration. Since the work of [6] there has been a realization that core formation at high PT conditions can explain the abundances of many siderophile elements in the mantle (e.g., [7]), but such detailed high PT partitioning data are lacking for many of the HSE to evaluate whether such ideas are viable for all four bodies. Consideration of other chemical parameters reveals larger problems that are difficult to overcome, but must be addressed in any scenario which calls on the addition of chondritic material to a reduced mantle. Yet these problems are rarely discussed or emphasized, making the late chondritic (or late veneer) addition hypothesis suspect.

  20. Growth

    Science.gov (United States)

    Waag, Andreas

    This chapter is devoted to the growth of ZnO. It starts with various techniques to grow bulk samples and presents in some detail the growth of epitaxial layers by metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), and pulsed laser deposition (PLD). The last section is devoted to the growth of nanorods. Some properties of the resulting samples are also presented. If a comparison between GaN and ZnO is made, very often the huge variety of different growth techniques available to fabricate ZnO is said to be an advantage of this material system. Indeed, growth techniques range from low cost wet chemical growth at almost room temperature to high quality MOCVD growth at temperatures above 1, 000∘C. In most cases, there is a very strong tendency of c-axis oriented growth, with a much higher growth rate in c-direction as compared to other crystal directions. This often leads to columnar structures, even at relatively low temperatures. However, it is, in general, not straight forward to fabricate smooth ZnO thin films with flat surfaces. Another advantage of a potential ZnO technology is said to be the possibility to grow thin films homoepitaxially on ZnO substrates. ZnO substrates are mostly fabricated by vapor phase transport (VPT) or hydrothermal growth. These techniques are enabling high volume manufacturing at reasonable cost, at least in principle. The availability of homoepitaxial substrates should be beneficial to the development of ZnO technology and devices and is in contrast to the situation of GaN. However, even though a number of companies are developing ZnO substrates, only recently good quality substrates have been demonstrated. However, these substrates are not yet widely available. Still, the situation concerning ZnO substrates seems to be far from low-cost, high-volume production. The fabrication of dense, single crystal thin films is, in general, surprisingly difficult, even when ZnO is grown on a ZnO substrate. However

  1. Electrochemical studies of Copper, Tantalum and Tantalum Nitride surfaces in aqueous solutions for applications in chemical-mechanical and electrochemical-mechanical planarization

    Science.gov (United States)

    Sulyma, Christopher Michael

    This report will investigate fundamental properties of materials involved in integrated circuit (IC) manufacturing. Individual materials (one at a time) are studied in different electrochemical environmental solutions to better understand the kinetics associated with the polishing process. Each system tries to simulate a real CMP environment in order to compare our findings with what is currently used in industry. To accomplish this, a variety of techniques are used. The voltage pulse modulation technique is useful for electrochemical processing of metal and alloy surfaces by utilizing faradaic reactions like electrodeposition and electrodissolution. A theoretical framework is presented in chapter 4 to facilitate quantitative analysis of experimental data (current transients) obtained in this approach. A typical application of this analysis is demonstrated for an experimental system involving electrochemical removal of copper surface layers, a relatively new process for abrasive-free electrochemical mechanical planarization of copper lines used in the fabrication of integrated circuits. Voltage pulse modulated electrodissolution of Cu in the absence of mechanical polishing is activated in an acidic solution of oxalic acid and hydrogen peroxide. The current generated by each applied voltage step shows a sharp spike, followed by a double-exponential decay, and eventually attains the rectangular shape of the potential pulses. For the second system in chapter 5, open-circuit potential measurements, cyclic voltammetry and Fourier transform impedance spectroscopy have been used to study pH dependent surface reactions of Cu and Ta rotating disc electrodes (RDEs) in aqueous solutions of succinic acid (SA, a complexing agent), hydrogen peroxide (an oxidizer), and ammonium dodecyl sulfate (ADS, a corrosion inhibitor for Cu). The surface chemistries of these systems are relevant for the development of a single-slurry approach to chemical mechanical planarization (CMP) of Cu

  2. Selective-Area Growth of Thick Diamond Films Using Chemically Stable Masks of Ru/Au and Mo/Au

    Science.gov (United States)

    Nagase, Masanori; Watanabe, Katsumi; Umezawa, Hitoshi; Shikata, Shinichi

    2012-07-01

    Selective-area growth of diamond films in microwave-plasma chemical vapor deposition was performed using newly developed masks. By forming chemically stable masks made of Ru/Au or Mo/Au, which have high melting points, good adhesion to diamond, and difficulty in forming carbide compounds, patterned diamond films with a large thickness of 50 µm, a large area of 5 mm2, and a high orientation in the [001] direction were successfully grown on (001) diamond substrates without degradation of the crystal quality of masked areas.

  3. The influence of plasma technology coupled to chemical grafting on the cell growth compliance of 3D hydroxyapatite scaffolds.

    Science.gov (United States)

    Russo, Laura; Zanini, Stefano; Giannoni, Paolo; Landi, Elena; Villa, Anna; Sandri, Monica; Riccardi, Claudia; Quarto, Rodolfo; Doglia, Silvia M; Nicotra, Francesco; Cipolla, Laura

    2012-11-01

    The development of advanced materials with biomimetic features in order to elicit desired biological responses and to guarantee tissue biocompatibility is recently gaining attention for tissue engineering applications. Bioceramics, such as hydroxyapatite-based biomaterials are now used in a number of different applications throughout the body, covering all areas of the skeleton, due to their biological and chemical similarity to the inorganic phases of bones. When bioactive sintered hydroxyapatite (HA) is desired, biomolecular modification of these materials is needed. In the present work, we investigated the influence of plasma surface modification coupled to chemical grafting on the cell growth compliance of HA 3D scaffolds.

  4. A plug flow model for chemical reactions and aerosol nucleation and growth in an alkali-containing flue gas

    DEFF Research Database (Denmark)

    Christensen, K. A.; Livbjerg, Hans

    2000-01-01

    multicomponent growth models are treated. The local gas phase composition is determined from a gas phase chemical equilibrium calculation combined with finite reaction rate kinetics for slower reactions. The model is useful in the analysis of boiler operation with respect to the formation of particles, HCl, SO2......The paper presents a numerical model for the simulation of gas to particle conversion and the chemical changes during cooling of a flue gas from the combustion of fuels rich in volatile alkali species. For the homogeneous nucleation of alkali species the model uses the classical theory modified...

  5. Versatile electron-collecting interfacial layer by in situ growth of silver nanoparticles in nonconjugated polyelectrolyte aqueous solution for polymer solar cells.

    Science.gov (United States)

    Yuan, Kai; Chen, Lie; Chen, Yiwang

    2014-10-01

    Novel PEIE-Ag composites by in situ growth of silver nanoparticles in poly(ethylenimine)-ethoxylated (PEIE) aqueous solution are explored as an efficient interfacial layer for improving inverted polymer solar cells (PSCs) performance. The hybrid PEIE-Ag interfacial material is simple to fabricate only via ultraviolet irradiation with good water-solubility and unique film formation. The generated Ag nanoparticles can anchor in the PEIE polymer chains to form a conductive continuous interpenetrating network structure. Combining of the advantages of PEIE and Ag nanoparticles, the PEIE-Ag shows enhanced charge transport, electron selective and collection, and improved light-harvesting, mainly due to the surface plasmon resonance effect, better energy alignment induced by the formation of ideal dipole layer, as well as the improved conductivity. These distinguished interfacial properties result in the power conversion efficiency of inverted PSCs based on poly[4,8-bis(2-ethyl-hexyl-thiophene-5-yl)-benzo[1,2-b:4,5-b]dithiophene-2,6-diyl]-alt-[2-(2-ethyl-hexanoyl)-thieno[3,4-b]thiophen-4,6-diyl] (PBDTTT-C-T) and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) photoactive layer substantially improved up to 7.66% from 6.11%. Moreover, the device performance is insensitively dependent on the thickness of the PEIE-Ag interfacial layer, broadening the thicknesses selection window for interfacial materials. These results demonstrate that PEIE-Ag is a potential interfacial material compatible with roll-to-roll techniques and suitable for printed electronic devices. PMID:25207753

  6. Growth enhancement of the halotolerant Brevibacterium sp. JCM 6894 by methionine externally added to a chemically defined medium.

    Science.gov (United States)

    Mimura, Haruo

    2014-01-01

    We examined amino acid requirements for the growth of the halotolerant Brevibacterium sp. JCM 6894 in the absence and presence of 1.2 M NaCl in a chemically defined medium. The experiment was also carried out in the presence of 1.2 M KCl. As a result, growth was highly enhanced by methionine in the absence and presence of KCl as well as NaCl up to 1.2 M. However, growth in the presence of 150 mM methionine was repressed by leucine (up to 100 mM)and valine (up to 100 mM). Concentration-dependent growth inhibition was observed in the presence of isoleucine (up to 150 mM) and threonine (up to 300 mM). When the cells were incubated in the absence of externally added K+, growth was strongly repressed, even in the presence of 150 mM methionine. The growth, however, recovered drastically by the addition of 1 mM KCl, regardless of the presence and absence of 1.2 M NaCl. These results indicate that methionine, which seems to be symported into cytoplasm with K+, plays an important role in the growth of the strain under salt stress. PMID:25252648

  7. Initial stages of growth and the influence of temperature during chemical vapor deposition of sp{sup 2}-BN films

    Energy Technology Data Exchange (ETDEWEB)

    Chubarov, Mikhail; Pedersen, Henrik; Högberg, Hans; Henry, Anne, E-mail: anne.henry@liu.se [Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Czigány, Zsolt [Institute of Technical Physics and Materials Science, Centre for Energy Research of Hungarian Academy of Sciences, Konkoly-Thege Miklós út 29-33, H-1121 Budapest (Hungary)

    2015-11-15

    Knowledge of the structural evolution of thin films, starting by the initial stages of growth, is important to control the quality and properties of the film. The authors present a study on the initial stages of growth and the temperature influence on the structural evolution of sp{sup 2} hybridized boron nitride (BN) thin films during chemical vapor deposition (CVD) with triethyl boron and ammonia as precursors. Nucleation of hexagonal BN (h-BN) occurs at 1200 °C on α-Al{sub 2}O{sub 3} with an AlN buffer layer (AlN/α-Al{sub 2}O{sub 3}). At 1500 °C, h-BN grows with a layer-by-layer growth mode on AlN/α-Al{sub 2}O{sub 3} up to ∼4 nm after which the film structure changes to rhombohedral BN (r-BN). Then, r-BN growth proceeds with a mixed layer-by-layer and island growth mode. h-BN does not grow on 6H-SiC substrates; instead, r-BN nucleates and grows directly with a mixed layer-by-layer and island growth mode. These differences may be caused by differences in substrate surface temperature due to different thermal conductivities of the substrate materials. These results add to the understanding of the growth process of sp{sup 2}-BN employing CVD.

  8. INTERACTION-MEDIATED GROWTH OF CARBON NANOTUBES ON ACICULAR SILICA-COATED α-Fe CATALYST BY CHEMICAL VAPOR DEPOSITION

    Institute of Scientific and Technical Information of China (English)

    Qixiang Wang; Guoqing Ning; Fei Wei; Guohua Luo

    2003-01-01

    Multi-walled carbon nanotubes (MWNTs) with 20 nm outer diameter were prepared by chemical vapor deposition of ethylene using ultrafine surface-modified acicular α-Fe catalyst particles. The growth mechanism of MWNTs on the larger catalyst particles are attributed to the interaction between the Fe nanoparticles with the surface-modified silica layer. This interaction-mediated growth mechanism is illustrated by studying the electronic, atomic and crystal properties of surface-modified catalysts and MWNTs products by characterization with X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), thermal gravimetric analysis (TGA) and Raman spectra.

  9. Van der Waals epitaxial growth of MoS2 on SiO2/Si by chemical vapor deposition

    KAUST Repository

    Cheng, Yingchun

    2013-01-01

    Recently, single layer MoS2 with a direct band gap of 1.9 eV has been proposed as a candidate for two dimensional nanoelectronic devices. However, the synthetic approach to obtain high-quality MoS2 atomic thin layers is still problematic. Spectroscopic and microscopic results reveal that both single layers and tetrahedral clusters of MoS2 are deposited directly on the SiO2/Si substrate by chemical vapor deposition. The tetrahedral clusters are mixtures of 2H- and 3R-MoS2. By ex situ optical analysis, both the single layers and tetrahedral clusters can be attributed to van der Waals epitaxial growth. Due to the similar layered structures we expect the same growth mechanism for other transition-metal disulfides by chemical vapor deposition. © 2013 The Royal Society of Chemistry.

  10. Growth of thick MgB{sub 2} films by impinging-jet hybrid physical-chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lamborn, D.R. [Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Wilke, R.H.T.; Li, Q. [Department of Physics, The Pennsylvania State University, University Park, PA 16802 (United States); Xi, X. [Department of Physics, Department of Materials Science and Engineering, Materials Research Institute, The Pennsylvania State University, University Park, PA 16801 (United States); Snyder, D.W. [Applied Research Laboratory, The Pennsylvania State University, University Park, PA 16802 (United States); Redwing, J.M. [Department of Materials Science and Engineering, Materials Research Institute, The Pennsylvania State University, University Park, PA 16801 (United States)

    2008-01-18

    Thick MgB{sub 2} films are grown using a novel impinging-jet hybrid physical-chemical vapor deposition process. An increased amount of the boron source gas generates high growth rates. Superconducting properties of the thick films are comparable to previous results from other processes, which indicate that this is a promising new process for MgB{sub 2} deposition for coated conductor applications, such as wires and tapes for MRI magnets. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  11. INFLUENCE OF BIOFERTILIZERS, VERMICOMPOST AND CHEMICAL FERTILIZRS ON GROWTH, NODULATION, NUTRIENT UPTAKE, SEED YIELD AND ECONOMICS OF BLACK GRAM

    OpenAIRE

    Harish Kumar Mehta; R Subhash Reddy; P Jayamma; Naveen Kumar, R.

    2015-01-01

    The experiment was conducted during rabi season in medium black soil at College Farm, College of Agriculture, Rajendranagar, ANGRAU, Hyderabad, Andhra Pradesh to study the influence of biofertilizers, vermicompost and chemical fertilizers on growth, nodulation, nutrient uptake, seed yield and economics of Black gram. From the data, it was observed that 50%RDF + Vermicompost + Rhizobium + Pseudomonas significantly increased the plant height, root length, leaf area index and leaf chlorophyll co...

  12. The role of hydrogen in oxygen-assisted chemical vapor deposition growth of millimeter-sized graphene single crystals

    Science.gov (United States)

    Zhao, Pei; Cheng, Yu; Zhao, Dongchen; Yin, Kun; Zhang, Xuewei; Song, Meng; Yin, Shaoqian; Song, Yenan; Wang, Peng; Wang, Miao; Xia, Yang; Wang, Hongtao

    2016-03-01

    Involving oxygen in the traditional chemical vapor deposition (CVD) process has proven a promising approach to achieve large-scale graphene single crystals (GSCs), but its many relevant fundamental aspects are still not fully understood. Here we report a systematic study on the role of hydrogen in the growth of millimeter-sized GSCs using enclosure-like Cu structures via the oxygen-assisted CVD process. Results show that GSCs have different first layer growth behaviors on the inside and outside surfaces of a Cu enclosure when the H2 environment is varied, and these behaviors will consequently and strongly influence the adlayer formation in these GSCs, leading to two entirely different growth modes. Low H2 partial pressure (PH2) tends to result in fast growth of dendritically shaped GSCs with multiple small adlayers, but high PH2 can modify the GSC shape into hexagons with single large adlayer nuclei. This difference of adlayers is attributed to the different C diffusion paths determined by the shapes of their host GSCs. On the basis of these observations, we developed an isothermal two-step method to obtain GSCs with significantly improved growth rate and sample quality, in which low PH2 is first set to accelerate the growth rate followed by high PH2 to restrict the adlayer nuclei. Our results prove that the growth of GSCs can reach a reasonable optimization between their growth rates and sample quality by simply adjusting the CVD H2 environment, which we believe will lead to more improvements in graphene synthesis and fundamental insight into the related growth mechanisms.Involving oxygen in the traditional chemical vapor deposition (CVD) process has proven a promising approach to achieve large-scale graphene single crystals (GSCs), but its many relevant fundamental aspects are still not fully understood. Here we report a systematic study on the role of hydrogen in the growth of millimeter-sized GSCs using enclosure-like Cu structures via the oxygen-assisted CVD

  13. A vapor-liquid-solid model for chemical vapor deposition growth of carbon nanotubes.

    Science.gov (United States)

    Jiang, Kaili; Feng, Chen; Liu, Kai; Fan, Shoushan

    2007-01-01

    Although carbon nanotubes (CNTs) with a variety of morphologies have been successfully synthesized, there is no clear physical picture of the growth process. Correspondingly, the growth mechanism is still not clear up to now. Here we suggest a VLS model for the growth process of CNTs, which involves a liquid or liquid-like state catalyst. The basic idea is that, due to the high thermal conductivity and nanometer size of the catalyst and the fast diffusion of carbon atoms in it, both the temperature and the carbon atom distribution across it are uniform. The supersaturation level can be expressed as a function of the carbon concentration and temperature, which determines the nucleation dynamics and growth kinetics. Based on this model, the growth rate equation was obtained to describe the growth kinetics of carbon nanotubes, which shows good accordance with the experimental results.

  14. Modelling the growth/no growth boundary of Zygosaccharomyces bailii in acidic conditions: a contribution to the alternative method to preserve foods without using chemical preservatives.

    Science.gov (United States)

    Dang, T D T; Mertens, L; Vermeulen, A; Geeraerd, A H; Van Impe, J F; Debevere, J; Devlieghere, F

    2010-01-31

    The aim of the study was to develop mathematical models describing growth/no growth (G/NG) boundaries of the highly resistant food spoilage yeast-Zygosaccharomyces bailii-in different environmental conditions, taking acidified sauces as the target product. By applying these models, the stability of products with characteristics within the investigated pH, a(w) and acetic acid ranges can be evaluated. Besides, the well-defined no growth regions can be used in the development of guidelines regarding formulation of new shelf-stable foods without using chemical preservatives, which would facilitate the innovation of additive-free products. Experiments were performed at different temperatures and periods (22 degrees C for 45 and 60days, 30 degrees C for 45days) in 150 modified Sabouraud media characterized by high amount of sugars (glucose and fructose, 15% (w/v)), acetic acid (0.0-2.5% (v/v), 6 levels), pH (3.0-5.0, 5 levels) and a(w) (0.93-0.97, 5 levels). These time and temperature combinations were chosen as they are commonly applied for shelf-stable foods. The media were inoculated with ca. 4.5 log CFU/ml and yeast growth was monitored daily using optical density measurements. Every condition was examined in 20 replicates in order to yield accurate growth probabilities. Three separate ordinary logistic regression models were developed for different tested temperatures and incubation time. The total acetic acid concentration was considered as variable for all models. In general, when one intrinsic inhibitory factor became more stringent, the G/NG boundary shifted to less stressful conditions of the other two factors, resulting in enlarged no growth zones. Abrupt changes of growth probability often occurred around the transition zones (between growth and no growth regions), which indicates that minor variations in environmental conditions near the G/NG boundaries can cause a significant impact on the growth probability. When comparing growth after 45days between the

  15. Noble metals as permanent chemical modifiers for the determination of mercury in environmental reference materials using solid sampling graphite furnace atomic absorption spectrometry and calibration against aqueous standards

    Science.gov (United States)

    da Silva, Alessandra Furtado; Welz, Bernhard; Curtius, Adilson J.

    2002-12-01

    Iridium, palladium, rhodium and ruthenium, thermally deposited on the platform, were investigated as permanent modifiers for the determination of mercury in ash, sludge, marine and river sediment reference materials, ground to a particle size of 50 μm, using solid sampling graphite furnace atomic absorption spectrometry. A total mass of 250 μg of each modifier was applied using 25 injections of 20 μl of modifier solution (500 mg l -1), and executing a temperature program for modifier conditioning after each injection. The performance of palladium was found to be most consistent, taking the characteristic mass as the major criterion, resulting in an excellent correlation between the measured integrated absorbance values and the certified mercury contents. Mercury was found to be lost in part from aqueous solutions during the drying stage in the presence of all the investigated permanent modifiers, as well as in the presence of the palladium and magnesium nitrates modifier added in solution. A loss-free determination of mercury in aqueous solutions could be reached only after the addition of potassium permanganate, which finally made possible the use of aqueous standards for the direct analysis of solid samples. A characteristic mass of 55-60 pg Hg was obtained for the solid samples, using Pd as a permanent modifier, and also in aqueous solutions after the addition of permanganate. The results obtained for mercury in ash, sludge and sediment reference materials, using direct solid sapling and calibration against aqueous standards, as well as the detection limit of 0.2 mg kg -1 were satisfactory for a routine procedure.

  16. Noble metals as permanent chemical modifiers for the determination of mercury in environmental reference materials using solid sampling graphite furnace atomic absorption spectrometry and calibration against aqueous standards

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Alessandra Furtado da; Welz, Bernhard; Curtius, Adilson J

    2002-12-02

    Iridium, palladium, rhodium and ruthenium, thermally deposited on the platform, were investigated as permanent modifiers for the determination of mercury in ash, sludge, marine and river sediment reference materials, ground to a particle size of 50 {mu}m, using solid sampling graphite furnace atomic absorption spectrometry. A total mass of 250 {mu}g of each modifier was applied using 25 injections of 20 {mu}l of modifier solution (500 mg l{sup -1}), and executing a temperature program for modifier conditioning after each injection. The performance of palladium was found to be most consistent, taking the characteristic mass as the major criterion, resulting in an excellent correlation between the measured integrated absorbance values and the certified mercury contents. Mercury was found to be lost in part from aqueous solutions during the drying stage in the presence of all the investigated permanent modifiers, as well as in the presence of the palladium and magnesium nitrates modifier added in solution. A loss-free determination of mercury in aqueous solutions could be reached only after the addition of potassium permanganate, which finally made possible the use of aqueous standards for the direct analysis of solid samples. A characteristic mass of 55-60 pg Hg was obtained for the solid samples, using Pd as a permanent modifier, and also in aqueous solutions after the addition of permanganate. The results obtained for mercury in ash, sludge and sediment reference materials, using direct solid sapling and calibration against aqueous standards, as well as the detection limit of 0.2 mg kg{sup -1} were satisfactory for a routine procedure.

  17. Controlled growth of large area multilayer graphene on copper by chemical vapour deposition

    Science.gov (United States)

    Kaya, Ismet I.; Kasap, Sibel; Khaksaran, Hadi; Celik, Suleyman; Ozkaya, Hasan; Yanik, Cenk; Faculty of Engineering; Natural Sciences Team; Nanotechnology Research; Application Center Team

    2015-03-01

    The growth of multilayer graphene on the surface of a copper foil is studied experimentally. It has been shown that the average film thickness can be controlled by the growth time with a linear trend and the growth can be extended until nearly full coverage of multilayer graphene over the copper surface. It is observed that the impurity particles on the copper surface mediate the multilayer growth. The formation of large multilayer islands is explained by a qualitative model which takes into account the interplay between the length scales governed by the molecular mean free path of gas molecules and the distribution of the impurities.

  18. PHYSICO-CHEMICAL LIMITATIVE FACTORS FOR GROWTH AND DEVELOPMENT IN STERLET (ACIPENSER RUTHENUS LINNAEUS, 1758 IN EXTENSIVELY SYSTEM

    Directory of Open Access Journals (Sweden)

    R. C. DIMA

    2013-07-01

    Full Text Available The oldest and most common method of increasing fish is a fish breeding ponds in which the supervision of nutrition and growth of biological material. Sterlet (Acipenser ruthenus ruthenus Linnaeus 1785 is the 4th of sturgeon scale and economic importance as a share of production of these fish .Monitoring of physicochemical parameters of sturgeons ponds has a crucial role to obtain satisfactory yields both in qualitative and quantitative. Chemical characteristics of water were determined in laboratory ecosystems Chemistry of the Institute of Research and Development for Ecology Aquaculture, Fisheries and Aquaculture Galaţi for the samples have been taken of the total water. Determination of the chemical characteristics was performed by standardized methods. Physic-chemical parameters of water were determined according to norm on the classification of surface water quality in order to establish the ecological status of water (Order no. 161/2006, for Class II of quality.

  19. Effects of chemical contaminants on growth, age-structure, and reproduction of Mytilus edulis complex from Puget sound, Washington.

    Science.gov (United States)

    Kagley, Anna N; Kardong, Kyle E; Snider, Robert G; Casillas, Edmundo

    2014-07-01

    Bivalves are used as sentinel species to detect chemical contaminants in the marine environment, but biological effects on indigenous populations that result from chemical exposure are largely unknown. We assessed age-weight, length-weight relationships, age structure, and reproductive status (i.e. fecundity, egg size) of the blue mussel Mytilus edulis complex from six sites in central Puget Sound, Washington, and one site in the relatively pristine area of northern Puget Sound. Results of this study suggest that mussels from urban areas of Puget Sound exhibit a lower growth rate, altered population age-structure, and potential reproductive impairment as a result of exposure to chemical contaminants. These findings support the use of mussels as sentinel species to assess the biological effects of contaminants on invertebrate populations.

  20. Evaluation of effectiveness of chemical disinfectants in reducing bacterial growth on orthodontic instruments.

    Science.gov (United States)

    Reddy, R Vamshidhar; Tanveer, K; Sharma, K Dinesh; Kokkula, Naveen; Suresh, P L; Sudhakar, Meher

    2013-11-01

    Infection control requires serious effort in all fields of dentistry including orthodontics. Though there are various means of sterilization and disinfection in dental office, chemical disinfection is the most preferred method among orthodontists. The purpose of this study is to evaluate different chemical sterilization and disinfection methods used in orthodontic offices, which would guide the orthodontists in infection control.

  1. Role of plant growth regulators as chemical signals in plant-microbe interactions: a double edged sword.

    Science.gov (United States)

    Spence, Carla; Bais, Harsh

    2015-10-01

    Growth regulators act not only as chemicals that modulate plant growth but they also act as signal molecules under various biotic and abiotic stresses. Of all growth regulators, abscisic acid (ABA) is long known for its role in modulating plants response against both biotic and abiotic stress. Although the genetic information for ABA biosynthesis in plants is well documented, the knowledge about ABA biosynthesis in other organisms is still in its infancy. It is known that various microbes including bacteria produce and secrete ABA, but the overall functional significance of why ABA is synthesized by microbes is not known. Here we discuss the functional involvement of ABA biosynthesis by a pathogenic fungus. Furthermore, we propose that ABA biosynthesis in plant pathogenic fungi could be targeted for novel fungicidal discovery.

  2. Effect of methionine and cysteine deprivation on growth of different natural isolates of Lactobacillus spp. in chemically defined media

    Directory of Open Access Journals (Sweden)

    Lozo Jelena

    2008-01-01

    Full Text Available The purpose of this study was to determine the ability of natural isolates of lactobacilli from different ecological niches to grow in a chemically defined medium in the presence or absence of sulphur-containing amino acids, methionine and/or cysteine. The obtained results indicate that cysteine is essential for growth of L. paracasei subsp. paracasei BGHN14 and BGSJ2-8, while methionine is essential for isolates BGHN40, BGCG31, and BGHV54T of the species L. plantarum. Methionine is also essential for growth of L. rhamnosus BGHV58T. Other analyzed strains, such as L. plantarum BGSJ3-18, BGZB19, BGHV52Ta, and BGHV43T, require the presence of both amino acids for their growth.

  3. The multiscale simulation of metal organic chemical vapor deposition growth dynamics of GaInP thin film

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    As a Group III–V compound, GaInP is a high-efficiency luminous material. Metal organic chemical vapor deposition (MOCVD) technology is a very efficient way to uniformly grow multi-chip, multilayer and large-area thin film. By combining the computational fluid dynamics (CFD) and the kinetic Monte Carlo (KMC) methods with virtual reality (VR) technology, this paper presents a multiscale simulation of fluid dynamics, thermodynamics, and molecular dynamics to study the growth process of GaInP thin film in a vertical MOCVD reactor. The results of visualization truly and intuitively not only display the distributional properties of the gas’ thermal and flow fields in a MOCVD reactor but also display the process of GaInP thin film growth in a MOCVD reactor. The simulation thus provides us with a fundamental guideline for optimizing GaInP MOCVD growth.

  4. Modeling of the self-limited growth in catalytic chemical vapor deposition of graphene

    Science.gov (United States)

    Kim, HoKwon; Saiz, Eduardo; Chhowalla, Manish; Mattevi, Cecilia

    2013-05-01

    The development of wafer-scale continuous single-crystal graphene layers is key in view of its prospective applications. To this end, in this paper, we pave the way towards a graphene growth model in the framework of the Langmuir adsorption theory and two-dimensional crystallization. In particular, we model the nucleation and growth of graphene on copper using methane as a carbon precursor. The model leads to the identification of the range of growth parameters (temperature and gas pressures) that uniquely entails the final surface coverage of graphene. This becomes an invaluable tool to address the fundamental problems of continuity of polycrystalline graphene layers and crystalline grain dimensions. The model shows agreement with the existing experimental data in the literature. On the basis of the ‘contour map’ for graphene growth developed here and existing evidence of optimized growth of large graphene grains, new insights for engineering wafer-scale continuous graphene films are provided.

  5. Molecular recognition studies on supramolecular systems (XXIV)——Conformations and complexation abilities of chemically modified cyclodextrins in aqueous solution

    Institute of Scientific and Technical Information of China (English)

    刘育; 尤长城

    2000-01-01

    Circular dichroism spectral and fluorescence decay methods have been employed to determine the conformations of mono[6-(p-tolylseleno)-6-deoxy]-p-CD(1), mono(6-anilino-6-deoxy) β -CD (2) and mono[6-(L-tryptophan)-6-deoxy]-β-CD (3) in phosphate buffer solution (pH 7.2, 0.1 mol dm-3) at 298.15 K. The results indicate that compounds 2 and 3 formed self-inclusion complexes in aqueous buffer solution, while the substituent of compound 1 was not included into cyclodextrin cavity at all. Furthermore, the complex stability constant (logKs) and Gibbs free energy change (-ΔG° ) of these three cylcodextrin derivatives with several cycloalkanols have been determined by circular dichroism spectral titration in phosphate buffer solution at 298.15 K. It is found that the location of the substituent affects the stability of host-guest complex in aqueous solution.

  6. Comparison of diamond growth with different gas mixtures in microwave plasma asssited chemical vapor deposition (MWCVD

    Directory of Open Access Journals (Sweden)

    Corat Evaldo J.

    2003-01-01

    Full Text Available In this work we study the influence of oxygen addition to several halocarbon-hydrogen gas systems. Diamond growth have been performed in a high power density MWCVD reactor built in our laboratory. The growth experiments are monitored by argon actinometry as a reference to plasma temperature and atomic hydrogen production, and by mass spectrometry to compare the exhaust gas composition. Atomic hydrogen actinometry revealed that the halogen presence in the gas phase is responsible for a considerable increase of atomic hydrogen concentration in the gas phase. Mass spectrometry shows similar results for all gas mixtures tested. Growth studies with oxygen addition to CF4/H2, CCl4/H2, CCl2F2/H2 and CH3Cl/H2 reveals that oxygen increases the carbon solubility in the gas phase but no better diamond growth conditions were found. Halogens are not, per se, eligible for diamond growth. All the possible advantages, as the higher production of atomic hydrogen, have been suppressed by the low carbon solubility in the gas phase, even when oxygen is added. The diamond growth with small amount of CF4 added to CH4/H2 mixture is not aggressive to the apparatus but brings several advantages to the process.

  7. Cobalt sulfide thin films: Chemical growth, reaction kinetics and microstructural analysis

    International Nuclear Information System (INIS)

    Highlights: • CoS thin films were deposited from an aqueous alkaline bath. • The CoS thin films are polycrystalline with hexagonal crystal structure. • Microstructure consists of multifaceted webbed network of elongated CoS crystallites. • MFM images revealed presence of magnetic regions mimicking surface topography. • Influence of the complexing agents is also stressed by the bandgap measurements. - Abstract: CoS thin films were successfully deposited from an aqueous alkaline bath containing ammonia and TEA as the complexing agents. Under the pre-optimized conditions (temperature = 80 ± 0.5 °C, speed of the substrate rotation = 65 ± 2 rpm and deposition period = 90 min), ammonia and TEA quantities in the reaction bath were found to play a decisive role in the final product yield. Highly uniform, dark sea-green colored and tightly adherent deposits were obtained at our experimental conditions. As-obtained CoS thin films were polycrystalline in nature with hexagonal class of crystal system as derived from the X-ray diffraction analysis. Complex multifaceted webbed network of as-grown CoS crystals elongated and threaded into each other were observed through a scanning electron microscope. Atomic force micrographs revealed collapsing of the hillocks and filling of the valleys triggering decrease in the RMS roughness for increased TEA and NH3 quantities. Magnetic force microscopy (MFM) was employed to study surface topography in terms of magnetic mapping. MFM images highlighted the existence of the magnetic clusters imitating topography. Broad absorption edge with high absorption coefficient (α ≈ 104 cm−1) was observed for as-grown CoS thin films. Determined values of the optical bandgaps revealed influence of complexing environment on the final product

  8. Cobalt sulfide thin films: Chemical growth, reaction kinetics and microstructural analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kamble, S.S. [Thin Film and Solar Studies Research Laboratory, Solapur University, Solapur 413 255, M.S. (India); Sikora, Andrzej [Electrotechnical Institute, Division of Electrotechnology and Materials Science, ul. M Skłodowskiej-Curie 55/61, 50-369 Wroclaw (Poland); Pawar, S.T. [Thin Film and Solar Studies Research Laboratory, Solapur University, Solapur 413 255, M.S. (India); Maldar, N.N. [Polymer Chemistry Department, Solapur University, Solapur 413 255, M.S. (India); Deshmukh, L.P., E-mail: laldeshmukh@gmail.com [Thin Film and Solar Studies Research Laboratory, Solapur University, Solapur 413 255, M.S. (India)

    2015-02-25

    Highlights: • CoS thin films were deposited from an aqueous alkaline bath. • The CoS thin films are polycrystalline with hexagonal crystal structure. • Microstructure consists of multifaceted webbed network of elongated CoS crystallites. • MFM images revealed presence of magnetic regions mimicking surface topography. • Influence of the complexing agents is also stressed by the bandgap measurements. - Abstract: CoS thin films were successfully deposited from an aqueous alkaline bath containing ammonia and TEA as the complexing agents. Under the pre-optimized conditions (temperature = 80 ± 0.5 °C, speed of the substrate rotation = 65 ± 2 rpm and deposition period = 90 min), ammonia and TEA quantities in the reaction bath were found to play a decisive role in the final product yield. Highly uniform, dark sea-green colored and tightly adherent deposits were obtained at our experimental conditions. As-obtained CoS thin films were polycrystalline in nature with hexagonal class of crystal system as derived from the X-ray diffraction analysis. Complex multifaceted webbed network of as-grown CoS crystals elongated and threaded into each other were observed through a scanning electron microscope. Atomic force micrographs revealed collapsing of the hillocks and filling of the valleys triggering decrease in the RMS roughness for increased TEA and NH{sub 3} quantities. Magnetic force microscopy (MFM) was employed to study surface topography in terms of magnetic mapping. MFM images highlighted the existence of the magnetic clusters imitating topography. Broad absorption edge with high absorption coefficient (α ≈ 10{sup 4} cm{sup −1}) was observed for as-grown CoS thin films. Determined values of the optical bandgaps revealed influence of complexing environment on the final product.

  9. [Effects of different perlite additions on physical and chemical properties of sewage sludge compost and growth of Tagetes patula].

    Science.gov (United States)

    Hu, Yu-Tong; Shi, Lian-Hui; Liu, Deng-Min; Tong, Shao-Wei; Wei, Mei-Yan; Sun, Jie

    2014-07-01

    In order to resolve the problem of poor permeability of sewage sludge compost (SSC) which was used as the substitution of peat, perlite was used to regulate the permeability of the sewage. The pure SSC was used as control. The proportions of perlite in the mixtures with SSC were 20%, 40%, 60%, 80% and 100% (V/V), respectively. The effects of different perlite ratios on the physical and chemical properties and the growth of Tagetes patula were studied. The bulk density, water holding porosity and water holding porosity to aeration porosity decreased, but the total porosity and aeration porosity increased with the increasing addition of perlite to the SSC. For the chemical properties, the pH increased, and the EC and nutrient contents decreased with the increasing addition of perlite to the SSC. The aboveground biomass and flowers of T. patula were the highest in the 60% perlite treatment, and the lowest in the pure SSC treatment. The root morphology and activity were the best in the 40%, 60% and 80% perlite treatments. Aeration was the strongest factor to impact the maximum root length and average root diameter. Perlite promoted the growth of T. patula mainly through impacting the physical properties of the SSC. The addition of 60% perlite to the SSC could significantly improve the poor aeration and decrease the high salinity greatly in the SSC and regulate the growth of the root and aboveground of T. patula.

  10. Development of multi-residue and selective methods for the ultra-sensitive determination of endocrine disrupting chemicals in aqueous samples

    OpenAIRE

    Van Hoeck, Els

    2009-01-01

    Since World War II, the world has witnessed a large increase in the production of chemicals. Some of these chemicals, like pesticides, were designed for wide spread use. Others, like polychlorinated biphenyls (PCBs), were rather accidentally released into the environment by leakages or waste dumping. At that time, little or no attention was paid to the possible consequences that could result from the use, misuse and distribution of these chemicals. This ignorance changed with the publicati...

  11. Effect of gamma radiation on some chemical constituents and growth of mint plants

    International Nuclear Information System (INIS)

    The effectiveness of 0.5, 1.0, 2.0 and 4.0 K-rad gamma rays on peppermint (Mentha piperiata L.) growth, essential oil, nitrogen and pigments content was investigated. Pre-planting radiation dose of 1.0 K-rad was the best stimulant rather than other doses. It improved growth expressed as dry matter accumulation and essential oil yield. The effectiveness of applied gamma radiation on enhancing total oil content is a function of the enhanced plant growth rather than the oil per cent. High contents (mg/plant) of chlorophyll and carotenoids were resulted from plants pre-treated with 1.0 K-rad. Exposure to 1.0 and 2.0 K-rad induced maximum N contents. On the other hand, relatively higher dose (4 K-rad) induced slight effect on the studied parameters

  12. Effect of gamma radiation on some chemical constituents and growth of mint plants

    Energy Technology Data Exchange (ETDEWEB)

    Ragab, M.A.; Abou-Elsoud, M.A. (Agriculture Department for Soil and Water Researches, Nuclear Research Centre, A.E.A., Cairo (Egypt)); Khalil, M.M. (Horticulture Dept., College of Agriculture, Tanta Univ. (Egypt))

    1983-01-01

    The effectiveness of 0.5, 1.0, 2.0 and 4.0 K-rad gamma rays on peppermint (Mentha piperiata L.) growth, essential oil, nitrogen and pigments content was investigated. Pre-planting radiation dose of 1.0 K-rad was the best stimulant rather than other doses. It improved growth expressed as dry matter accumulation and essential oil yield. The effectiveness of applied gamma radiation on enhancing total oil content is a function of the enhanced plant growth rather than the oil per cent. High contents (mg/plant) of chlorophyll and carotenoids were resulted from plants pre-treated with 1.0 K-rad. Exposure to 1.0 and 2.0 K-rad induced maximum N contents. On the other hand, relatively higher dose (4 K-rad) induced slight effect on the studied parameters.

  13. Wavy membranes and the growth rate of a planar chemical garden: Enhanced diffusion and bioenergetics

    CERN Document Server

    Ding, Yang; Steinbock, Oliver; Cartwright, Julyan H E; Cardoso, Silvana S S

    2016-01-01

    In order to model ion transport across protocell membranes in Hadean hydrothermal vents, we consider both theoretically and experimentally the planar growth of a precipitate membrane formed at the interface between two parallel fluid streams in a two-dimensional microfluidic reactor. The growth rate of the precipitate is found to be proportional to the square root of time, which is characteristic of diffusive transport. However, the dependence of the growth rate on the concentrations of hydroxide and metal ions is approximately linear and quadratic, respectively. We show that such a difference in ionic transport dynamics arises from the enhanced transport of metal ions across a thin gel layer present at the surface of the precipitate. The fluctuations in transverse velocity in this wavy porous gel layer allow an enhanced transport of the cation, so that the effective diffusivity is about an order of magnitude higher than that expected from molecular diffusion alone. Our theoretical predictions are in excellen...

  14. Large-Area Growth of Uniform Single-Layer MoS2 Thin Films by Chemical Vapor Deposition.

    Science.gov (United States)

    Baek, Seung Hyun; Choi, Yura; Choi, Woong

    2015-12-01

    We report the largest-size thin films of uniform single-layer MoS2 on sapphire substrates grown by chemical vapor deposition based on the reaction of gaseous MoO3 and S evaporated from solid sources. The as-grown thin films of single-layer MoS2 were continuous and uniform in thickness for more than 4 cm without the existence of triangular-shaped MoS2 clusters. Compared to mechanically exfoliated crystals, the as-grown single-layer MoS2 thin films possessed consistent chemical valence states and crystal structure along with strong photoluminescence emission and optical absorbance at high energy. These results demonstrate that it is possible to scale up the growth of uniform single-layer MoS2 thin films, providing potentially important implications on realizing high-performance MoS2 devices.

  15. Change of chemical states of niobium in the oxide layer of zirconium–niobium alloys with oxide growth

    International Nuclear Information System (INIS)

    The change of chemical states of niobium with oxide growth was examined in the oxide layers of Zr–2.5Nb around the first kinetic transition by the conversion electron yield – X-ray absorption near-edge structure measurements. The detailed depth profiles of niobium chemical states were obtained in both the pre- and the post-transition oxide layers of Zr–2.5Nb formed in water at 663 K for 40–280 d. The depth profiling revealed that the inner oxide layer remained protective to oxidizing species even though in the post-transition region and this excellent stability of barrierness would be attributed the suppression of hydrogen pickup. (author)

  16. Chemical Composition and Biological Activity of Essential Oils of Origanum vulgare L. subsp. vulgare L. under Different Growth Conditions

    Directory of Open Access Journals (Sweden)

    Enrica De Falco

    2013-12-01

    Full Text Available This research was aimed at investigating the essential oil production, chemical composition and biological activity of a crop of pink flowered oregano (Origanum vulgare L. subsp. vulgare L. under different spatial distribution of the plants (single and binate rows. This plant factor was shown to affect its growth, soil covering, fresh biomass, essential oil amount and composition. In particular, the essential oil percentage was higher for the binate row treatment at the full bloom. The chemical composition of the oils obtained by hydrodistillation was fully characterized by GC and GC-MS. The oil from plants grown in single rows was rich in sabinene, while plants grown in double rows were richer in ocimenes. The essential oils showed antimicrobial action, mainly against Gram-positive pathogens and particularly Bacillus cereus and B. subtilis.

  17. Chemical characterization of SOA formed from aqueous-phase reactions of phenols with the triplet excited state of carbonyl and hydroxyl radical

    Science.gov (United States)

    Yu, L.; Smith, J.; Laskin, A.; Anastasio, C.; Laskin, J.; Zhang, Q.

    2014-12-01

    Phenolic compounds, which are emitted in significant amounts from biomass burning, can undergo fast reactions in atmospheric aqueous phases to form secondary organic aerosol (aqSOA). In this study, we investigate the reactions of phenol (compound with formula C6H5OH)), guaiacol (2-methoxyphenol), and syringol (2,6-dimethoxyphenol) with two major aqueous-phase oxidants - the triplet excited states of an aromatic carbonyl (3C*) and hydroxyl radical (· OH). We thoroughly characterize the low-volatility species produced from these reactions and interpret their formation mechanisms using aerosol mass spectrometry (AMS), nanospray desorption electrospray ionization mass spectrometry (nano-DESI MS), and ion chromatography (IC). A large number of oxygenated molecules are identified, including oligomers containing up to six monomer units, functionalized monomer and oligomers with carbonyl, carboxyl, and hydroxyl groups, and small organic acid anions (e.g., formate, acetate, oxalate, and malate). The average atomic oxygen-to-carbon (O / C) ratios of phenolic aqSOA are in the range of 0.85-1.23, similar to those of low-volatility oxygenated organic aerosol (LV-OOA) observed in ambient air. The aqSOA compositions are overall similar for the same precursor, but the reactions mediated by 3C* are faster than · OH-mediated reactions and produce more oligomers and hydroxylated species at the point when 50% of the phenolic compound has reacted. Profiles determined using a thermodenuder indicate that the volatility of phenolic aqSOA is influenced by both oligomer content and O / C ratio. In addition, the aqSOA shows enhanced light absorption in the UV-visible region, suggesting that aqueous-phase reactions of phenols may contribute to formation of secondary brown carbon in the atmosphere, especially in regions influenced by biomass burning.

  18. Chemical characterization of SOA formed from aqueous-phase reactions of phenols with the triplet excited state of carbonyl and hydroxyl radical

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Lu; Smith, Jeremy; Laskin, Alexander; Anastasio, Cort N.; Laskin, Julia; Zhang, Qi

    2014-01-01

    Phenolic compounds, which are emitted in significant amounts from biomass burning, can undergo fast reactions in atmospheric aqueous phases to form secondary organic aerosol (aqSOA). In this study, we investigate the reactions of phenol and two methoxy-phenols (syringol and guaiacol) with two major aqueous phase oxidants – the triplet excited states of an aromatic carbonyl (3C*) and hydroxyl radical (•OH). We thoroughly characterize the low-volatility species produced from these reactions and interpret their formation mechanisms using aerosol mass spectrometry (AMS), desorption electrospray ionization mass spectrometry (DESIMS), and ion chromatography (IC). A large number of oxygenated molecules are identified, including oligomers containing up to six monomer units, functionalized monomer and oligomers with carbonyl, carboxyl, and hydroxyl groups, and small organic acid anions (e.g., formate, acetate, oxalate, and malate). The average atomic oxygen-to-carbon (O/C) ratios of phenolic aqSOA are in the range of 0.85-1.23, similar to those of low-volatility oxygenated organic aerosol (LV-OOA) observed in ambient air. The aqSOA compositions are overall similar for the same precursor, but the reactions mediated by 3C* are faster than •OH-mediated reactions and produce more oligomers and hydroxylated species at the point when 50% of the phenol had reacted. Profiles determined using a thermodenuder indicate that the volatility of phenolic aqSOA is influenced by both oligomer content and O/C ratio. In addition, the aqSOA shows enhanced light absorption in the UV-vis region, suggesting that aqueous-phase reactions of phenols are likely an important source of brown carbon in the atmosphere, especially in regions influenced by biomass burning.

  19. [Effect of physico-chemical properties of polyacrylamide gel media on the growth of Escherichia coli colonies].

    Science.gov (United States)

    Rodin, V B; Bulatova, R F; Domotenko, L V; Inkovskaia, T E; Artiukhin, V I

    1992-01-01

    We studied the growth of Escherichia coli LE-392 colonies on polyacrylamide gels (PAAG) depending on the physico-chemical properties of the latter, i.e. polymer concentration in the gel, swelling degree, bound water content (fm), spin-lattice relaxation and spin-spin relaxation times of water molecule protons, and modulus of elasticity (G0). S- or R-type colonies formed depending on gel properties; the diametral growth rate of S colonies was 3 times less compared with that on the control agar medium (Tryptose broth). The procedure is proposed for preparation of PAAG which rules out syneresis. Functional relations between the polymer concentrations in uniformly swelling gels and concentrations of copolymers in the reaction mixture, fm and G0 were revealed. The fm and G0 parameters can be used for controlling the quality of PAAG.

  20. Growth of a Novel Periodic Structure of SiC/AlN Multilayers by Low Pressure Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yong-Mei; SUN Guo-Sheng; LI Jia-Ye; LIU Xing-Fang; WANG Lei; ZHAO Wan-Shun; LI Jin-Min

    2007-01-01

    A novel 10-period SiC/AlN multilayered structure with a SiC cap layer is prepared by low pressure chemical vapour deposition (LPCVD). The structure with total Sim thickness of about 1.45μm is deposited on a Si (111) substrate and shows good surface morphology with a smaller rms surface roughness of 5.3 nm. According to the secondary ion mass spectroscopy results, good interface of the 10 period SiC/AlN structure and periodic changes of depth profiles of C, Si, Al, N components are obtained by controlling the growth procedure. The structure exhibits the peak reflectivity close to 30% near the wavelength of 322 nm. To the best of our knowledge, this is the first report of growth of the SiC/AlN periodic structure using the home-made LPCVD system.

  1. Morphological and chemical study of the initial growth of CdS thin films deposited using an ammonia-free chemical process

    Energy Technology Data Exchange (ETDEWEB)

    Mazon-Montijo, D.A.; Sotelo-Lerma, M.; Quevedo-Lopez, M. [Centro de Investigacion en Polimeros y Materiales, Universidad de Sonora, Apdo. Postal 130, 83190 Hermosillo, Son. (Mexico); El-Bouanani, M. [Department of Materials Science and Engineering, University of North Texas, P.O. Box 305310 Denton, TX 76203-5310 (United States); Alshareef, H.N. [SEMATECH, 2706 Montopolis Drive, Austin, TX 78741 (United States); Espinoza-Beltran, F.J. [Centro de Investigacion y Estudios Avanzados del IPN, Unidad Queretaro, Apdo. Postal 1-798, 76001 Queretaro, Qro. (Mexico); Ramirez-Bon, R. [Centro de Investigacion y Estudios Avanzados del IPN, Unidad Queretaro, Apdo. Postal 1-798, 76001 Queretaro, Qro. (Mexico)], E-mail: rrbon@qro.cinvestav.mx

    2007-11-15

    We study the initial growth stages of CdS thin films deposited by an ammonia-free chemical bath deposition process. This ammonia-free process is more environmentally benign because it reduces potential ammonia release to the environment due to its high volatility. Instead of ammonia, sodium citrate was used as the complexing agent. We used atomic force microscopy (AFM), Rutherford backscattering (RBS) and X-ray photoelectron spectroscopy (XPS) to investigate the morphological and chemical modifications at the substrate surface during the first initial stages of the CdS deposition process. Additionally, X-ray diffraction (XRD) and optical transmission spectroscopy measurements were carried out to compliment the study. XPS results show that the first nucleation centers are composed by Cd(OH){sub 2} which agglomerate in patterns of bands, as demonstrated by AFM results. It is also observed that the conversion to CdS (by anionic exchange) of the first nucleus begins before the substrate surface is completely covered by a homogenous film.

  2. Effects of salinity and manganese on growth and chemical composition of pistachio )Pistacia vera L.) seedlings in perlite medium

    OpenAIRE

    Z Asadollahi; V. Mozaffari

    2013-01-01

    To investigate the effect of manganese (Mn) and salinity on some growth traits and chemical composition of pistachio (Pistacia vera L.) seedlings, a factorial experiment was carried out with two factors of salinity (0, 75, 150, 225 and 300 mM NaCl) and Mn (0, 12, 24 and 36 µM Mn from MnSO4 source) as completely randomized design with four replicates, in greenhouse in perlite medium. Results showed that salinity stress decreased leaf number, leaf area, dry weight of root and dry weight of shoo...

  3. Influence of density on radiation-chemical yield of molecular hydrogen formed at radiolysis of aqueous solution of NaOH

    International Nuclear Information System (INIS)

    Full text : In atom and nuclear energy the specialists knowledge about radiation-chemical yield of the initial products formed under the influence of ionizing rays on water is of great importance from the point of security. The radiation-chemical yields of molecular hydrogen have been defined according to the graph and the obtained results

  4. Initiated-chemical vapor deposition of organosilicon layers: Monomer adsorption, bulk growth, and process window definition

    NARCIS (Netherlands)

    Aresta, G.; Palmans, J.; M. C. M. van de Sanden,; Creatore, M.

    2012-01-01

    Organosilicon layers have been deposited from 1,3,5-trivinyl-1,3,5-trimethylcyclotrisiloxane (V3D3) by means of the initiated-chemical vapor deposition (i-CVD) technique in a deposition setup, ad hoc designed for the engineering of multilayer moisture permeation barriers. The application of Fourier

  5. Silicon nitride at high growth rate using hot wire chemical vapor deposition

    NARCIS (Netherlands)

    Verlaan, V.

    2008-01-01

    Amorphous silicon nitride (SiNx) is a widely studied alloy with many commercial applications. This thesis describes the application of SiNx deposited at high deposition rate using hot wire chemical vapor deposition (HWCVD) for solar cells and thin film transistors (TFTs). The deposition process of H

  6. Growth of InAs Quantum Dots on Germanium Substrate Using Metal Organic Chemical Vapor Deposition Technique

    Directory of Open Access Journals (Sweden)

    Tyagi Renu

    2009-01-01

    Full Text Available Abstract Self-assembled InAs quantum dots (QDs were grown on germanium substrates by metal organic chemical vapor deposition technique. Effects of growth temperature and InAs coverage on the size, density, and height of quantum dots were investigated. Growth temperature was varied from 400 to 450 °C and InAs coverage was varied between 1.40 and 2.35 monolayers (MLs. The surface morphology and structural characteristics of the quantum dots analyzed by atomic force microscope revealed that the density of the InAs quantum dots first increased and then decreased with the amount of InAs coverage; whereas density decreased with increase in growth temperature. It was observed that the size and height of InAs quantum dots increased with increase in both temperature and InAs coverage. The density of QDs was effectively controlled by growth temperature and InAs coverage on GaAs buffer layer.

  7. Effects of chemical stress and food limitation on the energy reserves and growth of turbot, Scophthalmus maximus.

    Science.gov (United States)

    Kerambrun, E; Henry, F; Rabhi, K; Amara, R

    2014-12-01

    The objective of the present study is to examine the growth and energetic performance of juvenile turbot after exposure to contaminated sediment and during the subsequent recovery period with or without food limitation. We designed a two-step experiment by first exposing juvenile turbot to harbour sediment for 26 days and then transferring them to clean sea water with different frequencies of feeding for 35 days. Without food limitation, fish previously exposed to contaminated sediment compensated for weight, length and lipid reserve losses; we did not record any differences in size, Fulton's K condition index and triacylglycerol/sterol (TAG/ST) ratio after the 35-day depuration period compared to the reference fish. This result could be related to the compensatory growth mechanism observed in a wide range of fish species following a period of growth depression. With food limitation during the 35-day depuration period, recovery growth was not sufficient to restore length and weight values similar to the reference fish. Moreover, turbot previously exposed to contaminated sediment and subsequently fed twice or once a week exhibited extremely low TAG/ST ratios, but the reference fish submitted to the same restrictive feeding conditions did not. This study indicates that juvenile fish affected by chemical pollution can improve their biological performance if pollution events are followed by a period of abundant food. However, if pollution events occur during periods of food scarcity, e.g. in winter, storage of energy reserves will be compromised. PMID:25015714

  8. Layer-Controlled Chemical Vapor Deposition Growth of MoS2 Vertical Heterostructures via van der Waals Epitaxy.

    Science.gov (United States)

    Samad, Leith; Bladow, Sage M; Ding, Qi; Zhuo, Junqiao; Jacobberger, Robert M; Arnold, Michael S; Jin, Song

    2016-07-26

    The fascinating semiconducting and optical properties of monolayer and few-layer transition metal dichalcogenides, as exemplified by MoS2, have made them promising candidates for optoelectronic applications. Controllable growth of heterostructures based on these layered materials is critical for their successful device applications. Here, we report a direct low temperature chemical vapor deposition (CVD) synthesis of MoS2 monolayer/multilayer vertical heterostructures with layer-controlled growth on a variety of layered materials (SnS2, TaS2, and graphene) via van der Waals epitaxy. Through precise control of the partial pressures of the MoCl5 and elemental sulfur precursors, reaction temperatures, and careful tracking of the ambient humidity, we have successfully and reproducibly grown MoS2 vertical heterostructures from 1 to 6 layers over a large area. The monolayer MoS2 heterostructure was verified using cross-sectional high resolution transmission electron microscopy (HRTEM) while Raman and photoluminescence spectroscopy confirmed the layer-controlled MoS2 growth and heterostructure electronic interactions. Raman, photoluminescence, and energy dispersive X-ray spectroscopy (EDS) mappings verified the uniform coverage of the MoS2 layers. This reaction provides an ideal method for the scalable layer-controlled growth of transition metal dichalcogenide heterostructures via van der Waals epitaxy for a variety of optoelectronic applications.

  9. Growth mechanism of planar or nanorod structured tungsten oxide thin films deposited via aerosol assisted chemical vapour deposition (AACVD)

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Min; Blackman, Chris [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2015-07-15

    Aerosol assisted chemical vapour deposition (AACVD) is used to deposit tungsten oxide thin films from tungsten hexacarbonyl (W(CO){sub 6}) at 339 to 358 C on quartz substrate. The morphologies of as-deposited thin films, which are comprised of two phases (W{sub 25}O{sub 73} and W{sub 17}O{sub 47}), vary from planar to nanorod (NR) structures as the distance from the inlet towards the outlet of the reactor is traversed. This is related to variation of the actual temperature on the substrate surface (ΔT = 19 C), which result in a change in growth mode due to competition between growth rate (perpendicular to substrate) and nucleation rate (parallel to substrate). When the ratio of perpendicular growth rate to growth rate contributed by nucleation is higher than 7.1, the as-deposited tungsten oxide thin film forms as NR. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Effects of growth altitude on chemical constituents and delayed luminescence properties in medicinal rhubarb.

    Science.gov (United States)

    Sun, Mengmeng; Li, Li; Wang, Mei; van Wijk, Eduard; He, Min; van Wijk, Roeland; Koval, Slavik; Hankemeier, Thomas; van der Greef, Jan; Wei, Shengli

    2016-09-01

    To improve the quality control of herbal drugs, there has been a major shift from evaluating individual chemicals to evaluating multiple-constituent chemicals, given the multi-pharmacology nature of herbal drugs. Therefore, rapid, systematic assays are needed in order to assess the quality of medicinal herbs using a comprehensive, integrated approach. Light-induced delayed luminescence (DL) is used to measure decaying long-term ultra-weak photon emissions following excitation with light. DL is considered to be a sensitive indicator for characterizing the properties of biological systems and herbal medicines with various therapeutic properties. The aim of this study was to examine the feasibility of using DL as a novel quality-assessment tool using rhubarb material as a model system, and to establish the correlation between DL parameters and the chemical constituents of rhubarb. Raw roots and rhizomes were collected from rhubarb (Rheum palmatum L.) at various elevations in western China. HPLC analysis was used to identify fourteen bioactive constituents. Five DL parameters were calculated from the DL decay curves of the rhubarb samples. Statistical tools, including principal component analysis, were used to classify the rhubarb samples using data obtained using two different assays. Finally, Spearman's correlation coefficient was calculated to quantify the correlation between the bioactive compounds and corresponding DL parameters. We found that both the chemical analysis and DL measurements reflect variations in the quality of rhubarb due to environment factor. The DL parameters were correlated significantly with the bioactive chemical constituents. Our results indicate that DL is a promising tool for evaluating multiple constituents and for assessing the therapeutic properties of herbal medicines. Thus, DL may be used as part of a comprehensive system for assessing the quality and/or therapeutic properties of herbal medicines. PMID:27327125

  11. Controlled growth of superhydrophobic films without any low-surface-energy modification by chemical displacement on zinc substrates

    Energy Technology Data Exchange (ETDEWEB)

    Xu Wenguo, E-mail: xuwg60@bit.edu.cn [Key Laboratory of Cluster Science of Ministry of Education, School of Science, Beijing Institute of Technology, 5 South Street of Zhongguancun, Beijing 100081 (China); Shi Xiaofeng [Key Laboratory of Cluster Science of Ministry of Education, School of Science, Beijing Institute of Technology, 5 South Street of Zhongguancun, Beijing 100081 (China); Lu Shixiang, E-mail: shixianglu@bit.edu.cn [Key Laboratory of Cluster Science of Ministry of Education, School of Science, Beijing Institute of Technology, 5 South Street of Zhongguancun, Beijing 100081 (China)

    2011-10-03

    Graphical abstract: The nano-grains on the micro-pillars are formed at the most thermodynamically active sites for saturation, precipitation of the zinc atoms and the surface effect of the micro structure in the process of heat treatment. The micro sized pillars and the nano sized grain composed a micro-nano binary structure, which is analogous to that of the lotus leaf. Highlights: {yields} Cu-Zn alloy formed via chemical displacement at a perpendicular way. {yields} Crystal CuZn{sub 5} and ZnO formed via anneal treatment in humidity. {yields} Micro-pillars and nano-grain composed a micro-nano binary structure. {yields} Micro-nano surfaces prepared exhibited good superhydrophobicity. - Abstract: Superhydrophobic surface was prepared via immersing the clean perpendicular zinc substrate into aqueous copper (II) chloride (CuCl{sub 2}) solution and followed by anneal under the humid condition. The prepared samples were characterized by powder X-ray diffraction analysis, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy (XPS), and scanning electron microscopy (SEM), and energy-dispersive X-ray spectrometry analysis (EDX). SEM images of the films showed that the resulted surfaces exhibit micro-nano binary structures. The resulting surfaces had a high water contact angle (CA) of larger than 150{sup o} as well as a small sliding angle (SA) of less than 6{sup o}. Cu-Zn alloy formed by chemical displacement. Crystal CuZn{sub 5} formed via crystal transition via anneal treatment. Crystal ZnO formed in air or under the humid condition. The CuZn{sub 5}-ZnO micro-nano binary structures leads to the surface superhydrophobicity.

  12. Functional, genetic and chemical characterization of biosurfactants produced by plant growth-promoting Pseudomonas putida 267

    NARCIS (Netherlands)

    Kruijt, M.; Tran, H.; Raaijmakers, J.M.

    2009-01-01

    Aims: Plant growth-promoting Pseudomonas putida strain 267, originally isolated from the rhizosphere of black pepper, produces biosurfactants that cause lysis of zoospores of the oomycete pathogen Phytophthora capsici. The biosurfactants were characterized, the biosynthesis gene(s) partially identif

  13. Growth of Aligned Carbon Nanotubes through Microwave Plasma Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    王升高; 汪建华; 马志斌; 王传新; 满卫东

    2005-01-01

    Aligned carbon nanotubes (CNTs) were synthesized on glass by microwave plasma chemical vapor deposition (MWPCVD) with a mixture of methane and hydrogen gases at the low temperature of 550 ℃. The experimental results show that both the self-bias potential and the density of the catalyst particles are responsible for the alignment of CNTs. When the catalyst particle density is high enough, strong interactions among the CNTs can inhibit CNTs from growing randomly and result in parallel alignment.

  14. High Yield Chemical Vapor Deposition Growth of High Quality Large-Area AB Stacked Bilayer Graphene

    OpenAIRE

    Liu, Lixin; Zhou, Hailong; Cheng, Rui; Yu, Woo Jong; Liu, Yuan; Chen, Yu; Shaw, Jonathan; Zhong, Xing; Huang, Yu; Duan, Xiangfeng

    2012-01-01

    Bernal stacked (AB stacked) bilayer graphene is of significant interest for functional electronic and photonic devices due to the feasibility to continuously tune its band gap with a vertical electrical field. Mechanical exfoliation can be used to produce AB stacked bilayer graphene flakes but typically with the sizes limited to a few micrometers. Chemical vapor deposition (CVD) has been recently explored for the synthesis of bilayer graphene but usually with limited coverage and a mixture of...

  15. Growth of Boron-Rich Nanowires by Chemical Vapor Deposition (CVD

    Directory of Open Access Journals (Sweden)

    H. J. Kleebe

    2006-11-01

    Full Text Available B-rich nanowires are grown on Ni coated oxidized Si(111 substrate using diborane as the gas precursor in a CVD process at 20 torr and 900C∘. These nanowires have diameters around 20–100 nanometers and lengths up to microns. Icosahedron B12 is shown to be the basic building unit forming the amorphous B-rich nanowires as characterized by EDAX, XRD, XPS, and Raman spectroscopies. The gas chemistry at low [B2H6]/ [N2] ratio is monitored by the in situ mass spectroscopy, which identified N2 as an inert carrier gas leading to formation of the B-rich compounds. A nucleation controlled growth mechanism is proposed to explain the rugged nanowire growth of boron. The role of the Ni catalyst in the synthesis of the B-rich nanostructures is also discussed.

  16. Effect of naturally occurring antimicrobials and chemical preservatives on the growth of Aspergillus Parasiticus.

    Science.gov (United States)

    Pillai, Prathesha; Ramaswamy, K

    2012-04-01

    Effect of water activity (aw, 0.99), pH (4.5) and their interaction on the growth inhibition of Aspergillus parasiticus was studied on potato dextrose agar (PDA) using various antimicrobial agents (citral, carvacrol, eugenol, cineole, thymol guaiacol, vanillin, anethol, potassium sorbate and sorbic acid). The results demonstrate that colony diameter (mm) exhibited a constant increase with time (zero order kinetics) for all antimicrobials evaluated. Eugenol and sorbic acid inhibited the test fungi at 300 and 600 ppm, respectively. Radial growth rate (RGR) of A. parasiticus was significantly (p potassium sorbate, cineole, anethol and guaiacol were least effective. Thymol, eugenol and carvacrol were more effective in inhibiting A. parasiticus even with low concentration (150 ppm) as their mean RGR was zero even after 20 days of incubation (pH 4.5). PMID:23572846

  17. Sesame oil in diets for lambari: Effects on growth parameters, corporal chemical composition and physiological alterations

    OpenAIRE

    Mariene Miyoko Natori; Rachel Cristina Prehl Alves; Ricardo Henrique Franco de Oliveira; Julio Guerra Segura; Elisabete Maria Macedo Viegas

    2016-01-01

    ABSTRACT: The inclusion of sesame oil associated with soybean, linseed and freshwater fish residue oil in the diets fed to Lambaris Astyanax altiparanaewas evaluated by the growth performance parameters, body composition and possible physiological changes (GARUTTI & BRISTSKI, 2000). The experiment was a completely randomized design in two factorial parameters tested: three oil types (soy oil (SO), linseed oil (LO) and freshwater fish residue oil (FRO)), combined or not with sesame oil (SEO), ...

  18. Growth control, structure, chemical state, and photoresponse of CuO-CdS core-shell heterostructure nanowires.

    Science.gov (United States)

    El Mel, A A; Buffière, M; Bouts, N; Gautron, E; Tessier, P Y; Henzler, K; Guttmann, P; Konstantinidis, S; Bittencourt, C; Snyders, R

    2013-07-01

    The growth of single-crystal CuO nanowires by thermal annealing of copper thin films in air is studied. We show that the density, length, and diameter of the nanowires can be controlled by tuning the morphology and structure of the copper thin films deposited by DC magnetron sputtering. After identifying the optimal conditions for the growth of CuO nanowires, chemical bath deposition is employed to coat the CuO nanowires with CdS in order to form p-n nanojunction arrays. As revealed by high-resolution TEM analysis, the thickness of the polycrystalline CdS shell increases when decreasing the diameter of the CuO core for a given time of CdS deposition. Near-edge x-ray absorption fine-structure spectroscopy combined with transmission x-ray microscopy allows the chemical analysis of isolated nanowires. The absence of modification in the spectra at the Cu L and O K edges after the deposition of CdS on the CuO nanowires indicates that neither Cd nor S diffuse into the CuO phase. We further demonstrate that the core-shell nanowires exhibit the I-V characteristic of a resistor instead of a diode. The electrical behavior of the device was found to be photosensitive, since increasing the incident light intensity induces an increase in the collected electrical current. PMID:23732175

  19. Growth control, structure, chemical state, and photoresponse of CuO-CdS core-shell heterostructure nanowires.

    Science.gov (United States)

    El Mel, A A; Buffière, M; Bouts, N; Gautron, E; Tessier, P Y; Henzler, K; Guttmann, P; Konstantinidis, S; Bittencourt, C; Snyders, R

    2013-07-01

    The growth of single-crystal CuO nanowires by thermal annealing of copper thin films in air is studied. We show that the density, length, and diameter of the nanowires can be controlled by tuning the morphology and structure of the copper thin films deposited by DC magnetron sputtering. After identifying the optimal conditions for the growth of CuO nanowires, chemical bath deposition is employed to coat the CuO nanowires with CdS in order to form p-n nanojunction arrays. As revealed by high-resolution TEM analysis, the thickness of the polycrystalline CdS shell increases when decreasing the diameter of the CuO core for a given time of CdS deposition. Near-edge x-ray absorption fine-structure spectroscopy combined with transmission x-ray microscopy allows the chemical analysis of isolated nanowires. The absence of modification in the spectra at the Cu L and O K edges after the deposition of CdS on the CuO nanowires indicates that neither Cd nor S diffuse into the CuO phase. We further demonstrate that the core-shell nanowires exhibit the I-V characteristic of a resistor instead of a diode. The electrical behavior of the device was found to be photosensitive, since increasing the incident light intensity induces an increase in the collected electrical current.

  20. From aqueous metal-solutions to sub-micron powders by a chemical reduction process and ods-products by co-precipitation

    International Nuclear Information System (INIS)

    Different metal-powders like Cu, Ni and precious metals like Ag, Au, Pt or Pd can be produced by adding a suitable reducing agent to an aqueous metal solution. In some cases it is also possible to produce homogeneous solid solution powders. The particle-sizes can be varied in dependence of the reducing parameters like dilution of the solutions and temperature. Submicron powders far below 1 μm as well as particle-sizes up to 5 μm can be produced. A simultaneous co-precipitation of solutions containing the dissolved metal as well as Zr-, or Y-compounds is possible to obtain ODS-materials thereof. Subsequent conventional PM-processing like sintering with simultaneous transformation into oxides and subsequent deformation produces e.g. Zr-, or Y-oxide stabilized materials with suitable mechanical properties. (author)

  1. Effects of chemical and biological pesticides on plant growth parameters and rhizospheric bacterial community structure in Vigna radiata

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Sunil; Gupta, Rashi; Sharma, Shilpi, E-mail: shilpi@dbeb.iitd.ac.in

    2015-06-30

    Highlights: • Non-target effects of pesticides employing qualitative and quantitative approaches. • Qualitative shifts in resident and active bacterial community structure. • Abundance of 16S rRNA gene and transcripts were reduced significantly. • Effects of biological pesticide similar to chemical pesticides on rhizospheric bacteria. - Abstract: With increasing application of pesticides in agriculture, their non-target effects on soil microbial communities are critical to soil health maintenance. The present study aimed to evaluate the effects of chemical pesticides (chlorpyrifos and cypermethrin) and a biological pesticide (azadirachtin) on growth parameters and the rhizospheric bacterial community of Vigna radiata. Qualitative and quantitative analysis by PCR-denaturing gradient gel electrophoresis (DGGE) and q-PCR, respectively, of the 16S rRNA gene and transcript were performed to study the impact of these pesticides on the resident and active rhizospheric bacterial community. While plant parameters were not affected significantly by the pesticides, a shift in the bacterial community structure was observed with an adverse effect on the abundance of 16S rRNA gene and transcripts. Chlorpyrifos showed almost complete degradation toward the end of the experiment. These non-target impacts on soil ecosystems and the fact that the effects of the biopesticide mimic those of chemical pesticides raise serious concerns regarding their application in agriculture.

  2. CHEMICAL COMPOSITION OF JATOBÁ-DO-CERRADO (HYMENAEA STIGONOCARPA Mart. FLOUR AND ITS EFFECT ON GROWTH OF RATS

    Directory of Open Access Journals (Sweden)

    Ângela Giovana BATISTA

    2011-04-01

    Full Text Available The aim of this study was to evaluate the chemical composition of jatobá-do-cerrado fl our and its effects on rat´s growth. The chemical composition of the fl our was determined according to AOAC. The PER, NPR, food effi ciency ratio (FER, food conversion ratio (FCR, dry matter digestibility (DMD and fecal output were evaluated by an assay in which animals were fed according the AIN- 93 diet: casein (CAS diet and another having 50% of its protein source from jatobá fl our (JAT. Chemical analysis showed signifi cant amounts of crude fi bre and minerals (potassium, magnesium, calcium and zinc in the fl our. The CAS group ate more and gained more weight than JAT group (p0.05. Faeces moisture and dried weight for JAT were higher, which corroborated its lower DMD (p<0.05. Although JAT group had to intake more diet to promote weight gain, the protein utilization was acceptable. Therefore, further studies are necessary for better understand nutrient and phytochemical composition, their bioavailability, and metabolic effects of jatobá-do-cerrado fl our.

  3. Effects of chemical and biological pesticides on plant growth parameters and rhizospheric bacterial community structure in Vigna radiata

    International Nuclear Information System (INIS)

    Highlights: • Non-target effects of pesticides employing qualitative and quantitative approaches. • Qualitative shifts in resident and active bacterial community structure. • Abundance of 16S rRNA gene and transcripts were reduced significantly. • Effects of biological pesticide similar to chemical pesticides on rhizospheric bacteria. - Abstract: With increasing application of pesticides in agriculture, their non-target effects on soil microbial communities are critical to soil health maintenance. The present study aimed to evaluate the effects of chemical pesticides (chlorpyrifos and cypermethrin) and a biological pesticide (azadirachtin) on growth parameters and the rhizospheric bacterial community of Vigna radiata. Qualitative and quantitative analysis by PCR-denaturing gradient gel electrophoresis (DGGE) and q-PCR, respectively, of the 16S rRNA gene and transcript were performed to study the impact of these pesticides on the resident and active rhizospheric bacterial community. While plant parameters were not affected significantly by the pesticides, a shift in the bacterial community structure was observed with an adverse effect on the abundance of 16S rRNA gene and transcripts. Chlorpyrifos showed almost complete degradation toward the end of the experiment. These non-target impacts on soil ecosystems and the fact that the effects of the biopesticide mimic those of chemical pesticides raise serious concerns regarding their application in agriculture

  4. Growth of CdS nanoparticles by chemical method and its characterization

    Indian Academy of Sciences (India)

    R Bhattacharya; S Saha

    2008-07-01

    In the present work a simple chemical reduction method is followed to grow CdS nanoparticles at room temperature. The grown sample is ultrasonicated in acetone. The dispersed sample is characterized using electron diffraction technique. Simultaneously optical absorption of this sample is studied in the range of 400–700 nm. The photoluminescence spectrum of the sample is also studied. Results show the formation of nanoparticles. Hence an increase in band gap compared to bulk CdS and the as-prepared CdS nanoparticles have surface sulphur vacancies.

  5. Growth and characterization of Bi2Se3 crystals by chemical vapor transport

    Directory of Open Access Journals (Sweden)

    W. H. Jiao

    2012-06-01

    Full Text Available Regularly-shaped high-quality Bi2Se3 crystals were grown by a chemical vapor transport using iodine as the transport agent. In addition to exhibiting a characteristic Dirac cone for a topological insulator, the Bi2Se3 crystals show some outstanding properties including additional crystallographic surfaces, large residual resistance ratio (∼10, and high mobility (∼8000 cm2·V−1·s−1. The low-temperature resistivity abnormally increases with applying pressures up to 1.7 GPa, and no superconductivity was observed down to 0.4 K.

  6. Physical and chemical analyses on single source precursor growth CdSe semiconductor nanomaterials

    International Nuclear Information System (INIS)

    CdSe nanocrystals (NCs) are synthesized by the single source precursor thermal method. The use of a temperature ramp allows to obtain faster elaboration and smaller nano-particles in size. A cross-disciplinary study between chemical analyses and physical techniques provides consistent data for these small size NCs. Joint mass spectroscopy, transmission electron microscopy and optical spectrometry techniques give a coherent picture about average size and size dispersion of the NCs, as well as their optical spectral response in correlation with their size via quantum confinement effects.

  7. Direct Growth of Bismuth Film as Anode for Aqueous Rechargeable Batteries in LiOH, NaOH and KOH Electrolytes

    Directory of Open Access Journals (Sweden)

    Wenhua Zuo

    2015-10-01

    Full Text Available As promising candidates for next-generation energy storage devices, aqueous rechargeable batteries are safer and cheaper than organic Li ion batteries. But due to the narrow voltage window of aqueous electrolytes, proper anode materials with low redox potential and high capacity are quite rare. In this work, bismuth electrode film was directly grown by a facile hydrothermal route and tested in LiOH, NaOH and KOH electrolytes. With low redox potential (reduction/oxidation potentials at ca. −0.85/−0.52 V vs. SCE, respectively and high specific capacity (170 mAh·g−1 at current density of 0.5 A·g−1 in KOH electrolyte, Bi was demonstrated as a suitable anode material for aqueous batteries. Furthermore, by electrochemical impedance spectroscopy (EIS analysis, we found that with smaller Rs and faster ion diffusion coefficient, Bi electrode film in KOH electrolyte exhibited better electrochemical performance than in LiOH and NaOH electrolytes.

  8. Effects of salinity and manganese on growth and chemical composition of pistachio Pistacia vera L. seedlings in perlite medium

    Directory of Open Access Journals (Sweden)

    Z. Asadollahi

    2013-03-01

    Full Text Available To investigate the effect of manganese (Mn and salinity on some growth traits and chemical composition of pistachio (Pistacia vera L. seedlings, a factorial experiment was carried out with two factors of salinity (0, 75, 150, 225 and 300 mM NaCl and Mn (0, 12, 24 and 36 µM Mn from MnSO4 source as completely randomized design with four replicates, in greenhouse in perlite medium. Results showed that salinity stress decreased leaf number, leaf area, dry weight of root and dry weight of shoots. Application of 300 mM NaCl, decreased leaf number, leaf area, dry weight of root and dry weight of shoots by 40, 30, 92 and 92 percent in comparison with control (zero level of salinity, respectively. But application of 12 and 24 µM Mn increased dry weight of shoots and leaf number by 29 and 24 percent in comparison with zero level of Mn, respectively. Since salinity reduced leaf area and dry weight of leaf, thus, because of dilution effect, the concentration of Mn, Zn and P was increased in shoots and roots and that of K was decreased. Application of Mn increased Mn, Zn, P and K concentration. Overall results of this research showed that salinity reduced vegetative growth, and since Mn has positive effects on some growth traits, it could probably increase the tolerance of pistachio to saline environments.

  9. A chemical energy approach of avascular tumor growth: multiscale modeling and qualitative results.

    Science.gov (United States)

    Ampatzoglou, Pantelis; Dassios, George; Hadjinicolaou, Maria; Kourea, Helen P; Vrahatis, Michael N

    2015-01-01

    In the present manuscript we propose a lattice free multiscale model for avascular tumor growth that takes into account the biochemical environment, mitosis, necrosis, cellular signaling and cellular mechanics. This model extends analogous approaches by assuming a function that incorporates the biochemical energy level of the tumor cells and a mechanism that simulates the behavior of cancer stem cells. Numerical simulations of the model are used to investigate the morphology of the tumor at the avascular phase. The obtained results show similar characteristics with those observed in clinical data in the case of the Ductal Carcinoma In Situ (DCIS) of the breast. PMID:26558163

  10. Efficacy of aqueous garlic extract on growth, aflatoxin B1 production, and cyto-morphological aberrations of Aspergillus flavus, causing human ophthalmic infection: topical treatment of A. flavus keratitis.

    Science.gov (United States)

    Ismaiel, Ahmed A; Rabie, Gamal H; Kenawey, Saied E M; Abd El-Aal, Marwa A

    2012-10-01

    By using agar well diffusion assay, antifungal activity of aqueous extract prepared from Egyptian garlic (Allium sativum L.) was evaluated in vitro against two strains of Aspergillus flavus (OC1 and OC10) causing human ocular infection. The recorded minimum inhibitory concentration (MIC) for growth inhibition of both strains was 3.60 mg/ml. Aqueous garlic extract (AGE) was used in successive in vivo tests as an attempt to cure rabbit's fungal keratitis caused by A. flavus OC1. Findings showed that diluted preparation of AGE was effective topical antifungal agent and succeeded to cure severe A. flavus keratitis in a time course less than 10 days without any observable side effects. Microscopic examination showed that AGE induced deleterious cyto-morphological aberrations in A. flavus target cells. AGE applied to Czapek's broth via contact method was more effective on growth, spores and aflatoxin B1 production than AGE applied to the same broth at the same concentration via fumigation method. PMID:24031964

  11. Integrated use of plant growth promoting rhizobacteria, biogas slurry and chemical nitrogen for sustainable production of maize under salt-affected conditions

    International Nuclear Information System (INIS)

    Salinity is one of the most critical constraints hampering agricultural production throughout the world, including Pakistan. Some plant growth promoting rhizobacteria (PGPR) have the ability to reduce the deleterious effect of salinity on plants due to the presence of ACC-deaminase enzyme along with some other mechanisms. The integrated use of organic, chemical and biofertilizers can reduce dependence on expensive chemical inputs. To sustain high crop yields without deterioration of soil fertility, it is important to work out optimal combination of chemical and biofertilizers, and manures in the cropping system. A pot trial was conducted to study the effect of integrated use of PGPR, chemical nitrogen, and biogas slurry for sustainable production of maize under salt-stressed conditions and for good soil health. Results showed that sole application of PGPR, chemical nitrogen and biogas slurry enhanced maize growth but their combined application was more effective. Maximum improvement in maize growth, yield, ionic concentration in leaves and nutrient concentration in grains was observed in the treatment where PGPR and biogas slurry was used in the presence of 100% recommended nitrogen as chemical fertilizer. It also improved the soil pH, ECe, and available N, P and K contents. It is concluded that integrated use of PGPR, biogas slurry and chemical nitrogen not only enhanced maize growth, yield and quality but also improved soil health. So, it may be evaluated under field conditions to get sustained yield of maize from salt-affected soils. (author)

  12. Chemical repair of base lesions, AP-sites, and strand breaks on plasmid DNA in dilute aqueous solution by ascorbic acid

    Energy Technology Data Exchange (ETDEWEB)

    Hata, Kuniki [Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakatashirane, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Urushibara, Ayumi; Yamashita, Shinichi; Shikazono, Naoya; Yokoya, Akinari [Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakatashirane, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Katsumura, Yosuke, E-mail: katsu@n.t.u-tokyo.ac.jp [Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nuclear Professional School, School of Engineering, The University of Tokyo, 2-22 Shirakatashirane, Tokai-mura, Naka-gun, Ibaraki 319-1188 (Japan)

    2013-05-03

    Highlights: •We report a novel mechanism of radiation protection of DNA by chemical activity of ascorbic acid. •The “chemical repair” of DNA damage was revealed using biochemical assay and chemical kinetics analysis. •We found that ascorbic acid significantly repairs precursors of nucleobase lesions and abasic sites. •However, ascorbic acid seldom repairs precursors of DNA-strand breaks. -- Abstract: We quantified the damage yields produced in plasmid DNA by γ-irradiation in the presence of low concentrations (10–100 μM) of ascorbic acid, which is a major antioxidant in living systems, to clarify whether it chemically repairs radiation damage in DNA. The yield of DNA single strand breaks induced by irradiation was analyzed with agarose gel electrophoresis as conformational changes in closed circular plasmids. Base lesions and abasic sites were also observed as additional conformational changes by treating irradiated samples with glycosylase proteins. By comparing the suppression efficiencies to the induction of each DNA lesion, in addition to scavenging of the OH radicals derived from water radiolysis, it was found that ascorbic acid promotes the chemical repair of precursors of AP-sites and base lesions more effectively than those of single strand breaks. We estimated the efficiency of the chemical repair of each lesion using a kinetic model. Approximately 50–60% of base lesions and AP-sites were repaired by 10 μM ascorbic acid, although strand breaks were largely unrepaired by ascorbic acid at low concentrations. The methods in this study will provide a route to understanding the mechanistic aspects of antioxidant activity in living systems.

  13. Chemical repair of base lesions, AP-sites, and strand breaks on plasmid DNA in dilute aqueous solution by ascorbic acid

    International Nuclear Information System (INIS)

    Highlights: •We report a novel mechanism of radiation protection of DNA by chemical activity of ascorbic acid. •The “chemical repair” of DNA damage was revealed using biochemical assay and chemical kinetics analysis. •We found that ascorbic acid significantly repairs precursors of nucleobase lesions and abasic sites. •However, ascorbic acid seldom repairs precursors of DNA-strand breaks. -- Abstract: We quantified the damage yields produced in plasmid DNA by γ-irradiation in the presence of low concentrations (10–100 μM) of ascorbic acid, which is a major antioxidant in living systems, to clarify whether it chemically repairs radiation damage in DNA. The yield of DNA single strand breaks induced by irradiation was analyzed with agarose gel electrophoresis as conformational changes in closed circular plasmids. Base lesions and abasic sites were also observed as additional conformational changes by treating irradiated samples with glycosylase proteins. By comparing the suppression efficiencies to the induction of each DNA lesion, in addition to scavenging of the OH radicals derived from water radiolysis, it was found that ascorbic acid promotes the chemical repair of precursors of AP-sites and base lesions more effectively than those of single strand breaks. We estimated the efficiency of the chemical repair of each lesion using a kinetic model. Approximately 50–60% of base lesions and AP-sites were repaired by 10 μM ascorbic acid, although strand breaks were largely unrepaired by ascorbic acid at low concentrations. The methods in this study will provide a route to understanding the mechanistic aspects of antioxidant activity in living systems

  14. Flow of Aqueous Humor

    Science.gov (United States)

    ... Facebook Twitter Google Plus Email Print this page Flow of Aqueous Humor Most, but not all, forms ... aqueous humor) produced by the eye's ciliary body flows out freely (follow blue arrow). Aqueous humor flows ...

  15. Growth and characterization of large, high quality single crystal diamond substrates via microwave plasma assisted chemical vapor deposition

    Science.gov (United States)

    Nad, Shreya

    Single crystal diamond (SCD) substrates can be utilized in a wide range of applications. Important issues in the chemical vapor deposition (CVD) of such substrates include: shrinking of the SCD substrate area, stress and cracking, high defect density and hence low electronic quality and low optical quality due to high nitrogen impurities. The primary objective of this thesis is to begin to address these issues and to find possible solutions for enhancing the substrate dimensions and simultaneously improving the quality of the grown substrates. The deposition of SCD substrates is carried out in a microwave cavity plasma reactor via the microwave plasma assisted chemical vapor deposition technique. The operation of the reactor was first optimized to determine the safe and efficient operating regime. By adjusting the matching of the reactor cavity with the help of four internal tuning length variables, the system was further matched to operate at a maximum overall microwave coupling efficiency of ˜ 98%. Even with adjustments in the substrate holder position, the reactor remains well matched with a coupling efficiency of ˜ 95% indicating good experimental performance over a wide range of operating conditions. SCD substrates were synthesized at a high pressure of 240 Torr and with a high absorbed power density of 500 W/cm3. To counter the issue of shrinking substrate size during growth, the effect of different substrate holder designs was studied. An increase in the substrate dimensions (1.23 -- 2.5 times) after growth was achieved when the sides of the seeds were shielded from the intense microwave electromagnetic fields in a pocket holder design. Using such pocket holders, high growth rates of 16 -- 32 mum/hr were obtained for growth times of 8 -- 72 hours. The polycrystalline diamond rim deposition was minimized/eliminated from these growth runs, hence successfully enlarging the substrate size. Several synthesized CVD SCD substrates were laser cut and separated

  16. Microwave plasma-enhanced chemical vapour deposition growth of carbon nanostructures

    Directory of Open Access Journals (Sweden)

    Shivan R. Singh

    2010-05-01

    Full Text Available The effect of various input parameters on the production of carbon nanostructures using a simple microwave plasma-enhanced chemical vapour deposition technique has been investigated. The technique utilises a conventional microwave oven as the microwave energy source. The developed apparatus is inexpensive and easy to install and is suitable for use as a carbon nanostructure source for potential laboratory-based research of the bulk properties of carbon nanostructures. A result of this investigation is the reproducibility of specific nanostructures with the variation of input parameters, such as carbon-containing precursor and support gas flow rate. It was shown that the yield and quality of the carbon products is directly controlled by input parameters. Transmission electron microscopy and scanning electron microscopy were used to analyse the carbon products; these were found to be amorphous, nanotubes and onion-like nanostructures.

  17. Low temperature regulated growth of PbS quantum dots by wet chemical method

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Hitanshu, E-mail: hitanshuminhas@gmail.com; Barman, P. B.; Singh, Ragini Raj [Department of Physics and Materials Science, Jaypee University of Information Technology, Waknaghat, Solan-173234, H.P. (India); Bind, Umesh Chandra [Centre of Nanotechnology, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2015-08-28

    Narrow size distribution with regulated synthesis of lead sulfide (PbS) quantum dots (QDs) was achieved through wet chemical method. Different concentrations of 2-mercaptoethanol (capping agent) were used for tailoring the QDs size. Transmission electron microscopy and X-ray diffraction studies revealed that the QDs have mean diameters between 6 to 15 nm. The optical absorption spectra were compared to the predictions of a theoretical model for the electronic structure. The theory agrees well with experiment for QDs larger than 7 nm, but for smaller dots there is some deviation from the theoretical predictions. Consequently, the produced particles are having monodispersity, good water solubility, stability and may be good arguments to be biologically compatible due to the use of 2-mercaptoethanol.

  18. Growth of well-oriented VACNTs using thermal chemical vapor deposition method

    Science.gov (United States)

    Yousefi, Amin Termeh; Mahmood, Mohamad Rusop; Ikeda, Shoichiro

    2016-07-01

    The remarkable properties of carbon nanotubes (CNTs) make them attractive for biosensor applications, especially for medical detecting devices. In this paper, we describe a process to grow high oriented ratio CNT arrays to improve the electrical properties of the devices based on CNTs. Chemical vapor deposition (CVD) was used to grow highly oriented CNT using camphor as the carbon source, and argon and hydrogen as carrier gases to grow perpendicular CNTs on the surface of the silicon substrate in presence of ferrocene as a metallic catalyst. Images were revealed by FESEM indicates that the formation mechanism of oriented CNTs with high morphological purity nanotubes, which is depends significantly on deposition time and applied temperature to the furnaces. This method might be an effective method to produce oriented MWCNT in different length.

  19. Identification and Quantification of Volatile Chemical Spoilage Indexes Associated with Bacterial Growth Dynamics in Aerobically Stored Chicken.

    Science.gov (United States)

    Mikš-Krajnik, Marta; Yoon, Yong-Jin; Ukuku, Dike O; Yuk, Hyun-Gyun

    2016-08-01

    Volatile organic compounds (VOCs) as chemical spoilage indexes (CSIs) of raw chicken breast stored aerobically at 4, 10, and 21 °C were identified and quantified using solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS). The growth dynamics of total viable count (TVC), psychrotrophs, Pseudomonas spp., lactic acid bacteria (LAB), Brochothrix thermosphacta and H2 S producing bacteria were characterized based on maximum growth rates (μmax ), maximal microbial concentration (Nmax ) and at the moment of microbial shelf life (Svalues ), calculated from Gompertz-fitted growth curves. Pseudomonas spp. was predominant species, while B. thermosphacta was characterized by the highest μmax . The microbiological and sensory shelf lives were estimated based on TVC, Pseudomonas spp., and B. thermosphacta counts and sensory evaluation, respectively. Among 27 VOCs identified by GC-MS in spoiled chicken samples, ethanol (EtOH), 1-butanol-3-methyl (1But-3M), and acetic acid (C2 ) achieved the highest Pearson's correlation coefficients of 0.66, 0.61, and 0.59, respectively, with TVC, regardless of storage temperature. Partial least squares (PLS) regression revealed that the synthesis of 1But-3M and C2 was most likely induced by the metabolic activity of B. thermosphacta and LAB, while EtOH was attributed to Pseudomonas spp. The increase in concentration of selected volatile spoilage markers (EtOH, 1But-3M, and C2 ) in the headspace over spoiled chicken breast was found to be statistically significant (P < 0.05) with TVC growth. These findings highlight the possibility of analyzing the combination of 3 selected spoilage markers: EtOH, 1But-3M, and C2 as rapid evaluation for poultry quality testing using SPME-GC-MS.

  20. Growth of AlGaSb Compound Semiconductors on GaAs Substrate by Metalorganic Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    A. H. Ramelan

    2010-01-01

    Full Text Available Epitaxial AlxGa1-xSb layers on GaAs substrate have been grown by atmospheric pressure metalorganic chemical vapour deposition using TMAl, TMGa, and TMSb. We report the effect of V/III flux ratio and growth temperature on growth rate, surface morphology, electrical properties, and composition analysis. A growth rate activation energy of 0.73 eV was found. For layers grown on GaAs at 580∘C and 600∘C with a V/III ratio of 3 a high quality surface morphology is typical, with a mirror-like surface and good composition control. It was found that a suitable growth temperature and V/III flux ratio was beneficial for producing good AlGaSb layers. Undoped AlGaSb grown at 580∘C with a V/III flux ratio of 3 at the rate of 3.5 μm/hour shows p-type conductivity with smooth surface morphology and its hole mobility and carrier concentration are equal to 237 cm2/V.s and 4.6 × 1017 cm-3, respectively, at 77 K. The net hole concentration of unintentionally doped AlGaSb was found to be significantly decreased with the increased of aluminium concentration. All samples investigated show oxide layers (Al2O3, Sb2O3, and Ga2O5 on their surfaces. In particular the percentage of aluminium-oxide was very high compared with a small percentage of AlSb. Carbon content on the surface was also very high.

  1. Identification and Quantification of Volatile Chemical Spoilage Indexes Associated with Bacterial Growth Dynamics in Aerobically Stored Chicken.

    Science.gov (United States)

    Mikš-Krajnik, Marta; Yoon, Yong-Jin; Ukuku, Dike O; Yuk, Hyun-Gyun

    2016-08-01

    Volatile organic compounds (VOCs) as chemical spoilage indexes (CSIs) of raw chicken breast stored aerobically at 4, 10, and 21 °C were identified and quantified using solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS). The growth dynamics of total viable count (TVC), psychrotrophs, Pseudomonas spp., lactic acid bacteria (LAB), Brochothrix thermosphacta and H2 S producing bacteria were characterized based on maximum growth rates (μmax ), maximal microbial concentration (Nmax ) and at the moment of microbial shelf life (Svalues ), calculated from Gompertz-fitted growth curves. Pseudomonas spp. was predominant species, while B. thermosphacta was characterized by the highest μmax . The microbiological and sensory shelf lives were estimated based on TVC, Pseudomonas spp., and B. thermosphacta counts and sensory evaluation, respectively. Among 27 VOCs identified by GC-MS in spoiled chicken samples, ethanol (EtOH), 1-butanol-3-methyl (1But-3M), and acetic acid (C2 ) achieved the highest Pearson's correlation coefficients of 0.66, 0.61, and 0.59, respectively, with TVC, regardless of storage temperature. Partial least squares (PLS) regression revealed that the synthesis of 1But-3M and C2 was most likely induced by the metabolic activity of B. thermosphacta and LAB, while EtOH was attributed to Pseudomonas spp. The increase in concentration of selected volatile spoilage markers (EtOH, 1But-3M, and C2 ) in the headspace over spoiled chicken breast was found to be statistically significant (P < 0.05) with TVC growth. These findings highlight the possibility of analyzing the combination of 3 selected spoilage markers: EtOH, 1But-3M, and C2 as rapid evaluation for poultry quality testing using SPME-GC-MS. PMID:27332555

  2. The Effects of Burning and Mold Growth on the Chemical Composition of Firelog Fuels.

    Science.gov (United States)

    Winters, Kelsey; Evans, Michelle

    2016-07-01

    Firelogs consist of a cellulosic material, such as sawdust or wood particles, and a combustible binder (fuel). Historically, the fuel typically consisted of a petroleum-based (paraffin) wax; however, some manufacturers now include vegetable oils in their firelog fuels. To determine fuel composition, fuels from various brands of firelogs were extracted and analyzed by high-temperature gas chromatography-mass spectrometry (HTGC-MS) and a GC-MS with a polar column specific for the analysis of fatty acid methyl esters (FAMEs). Firelogs were also burned, allowed to grow mold, and analyzed by GC-MS to determine the effects that burning and mold growth have on firelog fuel composition. Mold did not tend to preferentially degrade any of the fatty acids. Burning caused a decrease in the relative amount of all of the fatty acids present in the vegetable oil fuel, with a greater effect on unsaturated fatty acids than saturated ones. PMID:27364292

  3. A flow-through passive dosing system for continuously supplying aqueous solutions of hydrophobic chemicals to bioconcentration and aquatic toxicity tests

    DEFF Research Database (Denmark)

    Adolfsson-Erici, Margaretha; Åkerman, Gun; Jahnke, Annika;

    2012-01-01

    A continuous supply of water with defined stable concentrations of hydrophobic chemicals is a requirement in a range of laboratory tests such as the OECD 305 protocol for determining the bioconcentration factor in fish. Satisfying this requirement continues to be a challenge, particularly for hyd...

  4. Growth of 2 um Crack-Free GaN on Si(111)Substrates by Metal Organic Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    WEI Meng; WANG Xiao-Liang; XIAO Hong-Ling; WANG Cui-Mei; PAN Xu; HOU Qi-Feng; WANG Zhan-Guo

    2011-01-01

    A 2μm high quality crack-free GaN film was successfully grown on 2-inch Si(111) substrates by metal organic chemical vapor deposition with a high temperature AlN/graded-AlGaN multibuffer and an AlN/GaN superlattice interlayer. It is found that the structures, as well as the thicknesses of the multibuffer and interlayer, are crucial for the growth of a crack-free GaN epilayer. The GaN(0002) XRD FWHM of the crack-free sample is 479.8 arcsec, indicating good crystal quality. An AlGaN/GaN heterostructure was grown and tested by Van der Pauw Hall measurement. The electron mobility of two-dimensional electron gas increases from 1928 cm2/V·s to 12277cm2/V·s when the test-temperature decreases from room temperature to liquid nitrogen temperature. The electron mobility is comparable to that of AlGaN/GaN heterostructures grown on sapphire, and the largest value is obtained for an AlGaN/GaN/Si(111) heterostructure grown by metal organic chemical vapor deposition.%@@ A 2pm high quality crack-free GaN film was successfully grown on 2-inch Si(111)substrates by metal organic chemical vapor deposition with a high temperature AIN/graded-AIGaN multibuffer and an AIN/GaN superlattice interlayer.It is found that the structures, as well as the thicknesses of the multibuffer and interlayer, are crucial for the growth of a crack-free GaN epilayer.The GaN(0002)XRD FWHM of the crack-free sample is 479.8arcsec, indicating good crystal quality.An AIGaN/GaN heterostructure was grown and tested by Van der Pauw Hall measurement.The electron mobility of two-dimensional electron gas increases from 1928 cm 2/V.S to 12277cm2/V s when the test-temperature decreases from room temperature to liquid nitrogen temperature.The electron mobility is comparable to that of AIGaN/GaN heterostructures grown on sapphire, and the largest value is obtained for an A]GaN/GaN/Si(111)heterostructure grown by metal organic chemical vapor deposition.

  5. A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions.

    Science.gov (United States)

    Brack, Paul; Dann, Sandie; Wijayantha, K G Upul; Adcock, Paul; Foster, Simon

    2016-01-01

    There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) hydrogen fuel cells. Researchers seeking to develop such systems require a method of measuring the generated hydrogen. Herein, we describe a simple, low-cost, and robust method to measure the hydrogen generated from the reaction of solids with aqueous solutions. The reactions are conducted in a conventional one-necked round-bottomed flask placed in a temperature controlled water bath. The hydrogen generated from the reaction in the flask is channeled through tubing into a water-filled inverted measuring cylinder. The water displaced from the measuring cylinder by the incoming gas is diverted into a beaker on a balance. The balance is connected to a computer, and the change in the mass reading of the balance over time is recorded using data collection and spreadsheet software programs. The data can then be approximately corrected for water vapor using the method described herein, and parameters such as the total hydrogen yield, the hydrogen generation rate, and the induction period can also be deduced. The size of the measuring cylinder and the resolution of the balance can be changed to adapt the setup to different hydrogen volumes and flow rates. PMID:27584581

  6. Aqueous extracts of the edible Gracilaria tenuistipitata are protective against H₂O₂-induced DNA damage, growth inhibition, and cell cycle arrest.

    Science.gov (United States)

    Yang, Jing-Iong; Yeh, Chi-Chen; Lee, Jin-Ching; Yi, Szu-Cheng; Huang, Hurng-Wern; Tseng, Chao-Neng; Chang, Hsueh-Wei

    2012-06-13

    Potential antioxidant properties of an aqueous extract of the edible red seaweed Gracilaria tenuistipitata (AEGT) against oxidative DNA damage were evaluated. The AEGT revealed several antioxidant molecules, including phenolics, flavonoids and ascorbic acid. In a cell-free assay, the extract exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity that significantly reduced H₂O₂-induced plasmid DNA breaks in a dose-response manner (P Gracilaria water extract can prevent H₂O₂-induced oxidative DNA damage and its related cellular responses.

  7. Growth of large size diamond single crystals by plasma assisted chemical vapour deposition: Recent achievements and remaining challenges

    Science.gov (United States)

    Tallaire, Alexandre; Achard, Jocelyn; Silva, François; Brinza, Ovidiu; Gicquel, Alix

    2013-02-01

    Diamond is a material with outstanding properties making it particularly suited for high added-value applications such as optical windows, power electronics, radiation detection, quantum information, bio-sensing and many others. Tremendous progresses in its synthesis by microwave plasma assisted chemical vapour deposition have allowed obtaining single crystal optical-grade material with thicknesses of up to a few millimetres. However the requirements in terms of size, purity and crystalline quality are getting more and more difficult to achieve with respect to the forecasted applications, thus pushing the synthesis method to its scientific and technological limits. In this paper, after a short description of the operating principles of the growth technique, the challenges of increasing crystal dimensions both laterally and vertically, decreasing and controlling point and extended defects as well as modulating crystal conductivity by an efficient doping will be detailed before offering some insights into ways to overcome them.

  8. Role of VI/II ratio on the growth of ZnO nanostructures using chemical bath deposition

    Energy Technology Data Exchange (ETDEWEB)

    Urgessa, Z.N., E-mail: zelalem.urgessa@nmmu.ac.za [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa); Oluwafemi, O.S. [Department of Chemistry and Chemical Technology, Walter Sisulu University, Mthatha Campus, Private Bag XI, 5117 (South Africa); Botha, J.R. [Department of Physics, P.O. Box 77000, Nelson Mandela Metropolitan University, Port Elizabeth 6031 (South Africa)

    2012-05-15

    In this paper the growth process and morphological evolution of ZnO nanostructures were investigated in a series of experiments using chemical bath deposition. The experimental results indicate that the morphological evolution depends on the reaction conditions, particularly on OH{sup -} to Zn{sup 2+} ratio (which directly affects the pH). For low VI/II ratios, quasi-spherical nanoparticles of an average diameter 30 nm are obtained, whereas for larger VI/II ratios, nanorods with an average diameter less than 100 nm are produced, which indicates that by systematically controlling the VI/II ratio, it is possible to produce different shapes and sizes of ZnO nanostructures. A possible mechanism for the nanostructural change of the as-synthesized ZnO from particle to rod was elucidated based on the relative densities of H{sup +} and OH{sup -} in the solution.

  9. Role of VI/II ratio on the growth of ZnO nanostructures using chemical bath deposition

    International Nuclear Information System (INIS)

    In this paper the growth process and morphological evolution of ZnO nanostructures were investigated in a series of experiments using chemical bath deposition. The experimental results indicate that the morphological evolution depends on the reaction conditions, particularly on OH− to Zn2+ ratio (which directly affects the pH). For low VI/II ratios, quasi-spherical nanoparticles of an average diameter 30 nm are obtained, whereas for larger VI/II ratios, nanorods with an average diameter less than 100 nm are produced, which indicates that by systematically controlling the VI/II ratio, it is possible to produce different shapes and sizes of ZnO nanostructures. A possible mechanism for the nanostructural change of the as-synthesized ZnO from particle to rod was elucidated based on the relative densities of H+ and OH− in the solution.

  10. Formation of Graphene Grain Boundaries on Cu(100) Surface and a Route Towards Their Elimination in Chemical Vapor Deposition Growth

    Science.gov (United States)

    Yuan, Qinghong; Song, Guangyao; Sun, Deyan; Ding, Feng

    2014-10-01

    Grain boundaries (GBs) in graphene prepared by chemical vapor deposition (CVD) greatly degrade the electrical and mechanical properties of graphene and thus hinder the applications of graphene in electronic devices. The seamless stitching of graphene flakes can avoid GBs, wherein the identical orientation of graphene domain is required. In this letter, the graphene orientation on one of the most used catalyst surface -- Cu(100) surface, is explored by density functional theory (DFT) calculations. Our calculation demonstrates that a zigzag edged hexagonal graphene domain on a Cu(100) surface has two equivalent energetically preferred orientations, which are 30 degree away from each other. Therefore, the fusion of graphene domains on Cu(100) surface during CVD growth will inevitably lead to densely distributed GBs in the synthesized graphene. Aiming to solve this problem, a simple route, that applies external strain to break the symmetry of the Cu(100) surface, was proposed and proved efficient.

  11. Formation of graphene grain boundaries on Cu(100) surface and a route towards their elimination in chemical vapor deposition growth.

    Science.gov (United States)

    Yuan, Qinghong; Song, Guangyao; Sun, Deyan; Ding, Feng

    2014-01-01

    Grain boundaries (GBs) in graphene prepared by chemical vapor deposition (CVD) greatly degrade the electrical and mechanical properties of graphene and thus hinder the applications of graphene in electronic devices. The seamless stitching of graphene flakes can avoid GBs, wherein the identical orientation of graphene domain is required. In this letter, the graphene orientation on one of the most used catalyst surface - Cu(100) surface, is explored by density functional theory (DFT) calculations. Our calculation demonstrates that a zigzag edged hexagonal graphene domain on a Cu(100) surface has two equivalent energetically preferred orientations, which are 30 degree away from each other. Therefore, the fusion of graphene domains on Cu(100) surface during CVD growth will inevitably lead to densely distributed GBs in the synthesized graphene. Aiming to solve this problem, a simple route, that applies external strain to break the symmetry of the Cu(100) surface, was proposed and proved efficient. PMID:25286970

  12. INFLUENCE OF BIOFERTILIZERS, VERMICOMPOST AND CHEMICAL FERTILIZRS ON GROWTH, NODULATION, NUTRIENT UPTAKE, SEED YIELD AND ECONOMICS OF BLACK GRAM

    Directory of Open Access Journals (Sweden)

    Harish Kumar Mehta

    2015-07-01

    Full Text Available The experiment was conducted during rabi season in medium black soil at College Farm, College of Agriculture, Rajendranagar, ANGRAU, Hyderabad, Andhra Pradesh to study the influence of biofertilizers, vermicompost and chemical fertilizers on growth, nodulation, nutrient uptake, seed yield and economics of Black gram. From the data, it was observed that 50%RDF + Vermicompost + Rhizobium + Pseudomonas significantly increased the plant height, root length, leaf area index and leaf chlorophyll content at 25 and 50 DAS over the other treatments including control. The same treatment recorded highest seed yield (707 kg ha-1 and haulm yield (7067 kg ha-1 as compared to the control. Nutrient uptake recorded significantly highest in the treatment supplied with biofertilizers along with Vermicompost and 50%RDF. Treatment supplied with 50%RDF + Vermicompost + Rhizobium + Pseudomonas recorded highest net return (17784 Rs ha-1 but highest B: C ratio (2.11 was recorded in the treatment supplied with 50%RDF + Rhizobium + Pseudomonas.

  13. Optical monitoring of surface processes relevant to thin film growth by chemical vapour deposition

    International Nuclear Information System (INIS)

    This thesis reports on the investigation of the use of reflectance anisotropy spectroscopy (RAS) as an in-situ monitor for the preparation and oxidation of GaAs(100) c(4x4) surfaces using a CVD 2000 MOCVD reactor. These surfaces were oxidised using air. It was found that it was possible to follow surface degradation using RA transients at 2.6eV and 4eV. From this data it was possible to speculate on the nature of the surface oxidation process. A study was performed into the rate of surface degradation under different concentrations of air, it was found that the relation between the air concentration and the surface degradation was complicated but that the behaviour of the first third of the degradation approximated a first order behaviour. An estimation of the activation energy of the process was then made, and an assessment of the potential use of the glove-box for STM studies which is an integral part of the MOCVD equipment was also made. Following this, a description is given of the construction of an interferometer for monitoring thin film growth. An investigation is also described into two techniques designed to evaluate the changes in reflected intensity as measured by an interferometer. The first technique uses an iteration procedure to determine the film thickness from the reflection data. This is done using a Taylor series expansion of the thin film reflection function to iterate for the thickness. Problems were found with the iteration when applied to noisy data, these were solved by using a least squares fit to smooth the data. Problems were also found with the iteration at the turning points these were solved using the derivative of the function and by anticipating the position of the turning points. The second procedure uses the virtual interface method to determine the optical constants of the topmost deposited material, the virtual substrate, and the growth rate. This method is applied by using a Taylor series expansion of the thin film reflection

  14. Characterization, feasibility and optimization of Agaricus subrufescens growth based on chemical elements on casing layer

    Science.gov (United States)

    Cunha Zied, D.; Pardo-Giménez, A.; de Almeida Minhoni, M.T.; Villas Boas, R.L.; Alvarez-Orti, M.; Pardo-González, J.E.

    2012-01-01

    The aim of this study was to analyze yields, biological efficiency, earliness (expressed as days to first harvest), and precociousness and establish models for the mushroom growing according to these parameters. The experiment followed a double factorial design with four sources of calcium (calcitic limestone, calcitic limestone + gypsum, dolomitic limestone and dolomitic limestone + gypsum) and 2 application times (25 days before casing and at the moment of casing), with 4 replicates for each treatment. Different calcium sources influenced differently Agaricus subrufescens production, especially as regards earliness, which showed significantly higher values when dolomitic limestone with gypsum was applied. Yield and biological efficiency were negatively correlated with H + AL, organic matter and Mg amount. Furthermore, earliness was positively correlated with H + Al, organic matter, and the amount of Mg and Fe. Finally, negative correlations were observed between precociousness and the amount of Ca, SB (sum of base), CEC (cation exchange capacity) and V% (percentage of base saturation). The models presented in this work are extremely important for predicting the agronomic performance of Agaricus subrufescens on the basis of chemical analysis provided by the casing soil. PMID:23961195

  15. Growth of epitaxial sodium-bismuth-titanate films by metal-organic chemical vapor phase deposition

    Energy Technology Data Exchange (ETDEWEB)

    Schwarzkopf, J., E-mail: schwarzkopf@ikz-berlin.de [Leibniz Institute for Crystal Growth, Max-Born-Strasse 2, 12489 Berlin (Germany); Schmidbauer, M.; Duk, A.; Kwasniewski, A. [Leibniz Institute for Crystal Growth, Max-Born-Strasse 2, 12489 Berlin (Germany); Anooz, S. Bin [Leibniz Institute for Crystal Growth, Max-Born-Strasse 2, 12489 Berlin (Germany); Physics Department, Faculty of Science, Hadhramout University of Science and Technology, Mukalla 50511, Republic of Yemen (Yemen); Wagner, G. [Leibniz Institute for Crystal Growth, Max-Born-Strasse 2, 12489 Berlin (Germany); Devi, A. [Inorganic Materials Chemistry, Ruhr-University Bochum, Universitaetsstr. 150, 44801 Bochum (Germany); Fornari, R. [Leibniz Institute for Crystal Growth, Max-Born-Strasse 2, 12489 Berlin (Germany)

    2011-10-31

    The liquid-delivery spin metal-organic chemical vapor phase deposition method was used to grow epitaxial sodium-bismuth-titanate films of the system Bi{sub 4}Ti{sub 3}O{sub 12} + xNa{sub 0.5}Bi{sub 0.5}TiO{sub 3} on SrTiO{sub 3}(001) substrates. Na(thd), Ti(O{sup i}Pr){sub 2}(thd){sub 2} and Bi(thd){sub 3}, solved in toluene, were applied as source materials. Depending on the substrate temperature and the Na/Bi ratio in the gas phase several structural phases of sodium-bismuth-titanate were detected. With increasing temperature and/or Na/Bi ratio, phase transitions from an Aurivillius phase with m = 3 to m = 4 via an interleaved state with m = 3.5, and, finally, to Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} with perovskite structure (m = {infinity}) were established. These phase transitions proceed at remarkably lower temperatures than in ceramics or bulk crystals for which they had been exclusively observed so far.

  16. Heteroepitaxial growth of wafer scale highly oriented graphene using inductively coupled plasma chemical vapor deposition

    Science.gov (United States)

    Gao, Libo; Xu, Hai; Li, Linjun; Yang, Yang; Fu, Qiang; Bao, Xinhe; Loh, Kian Ping

    2016-06-01

    The chemical vapor deposition (CVD) of graphene on Cu has attracted much attention because of its industrial scalability. Herein, we report inductively coupled plasma-assisted CVD of epitaxially grown graphene on (111)-textured Cu film alloyed with a small amount of Ni, where large area high quality graphene film can be grown in less than 5 min at 800 °C, thus affording industrial scalability. The epitaxially grown graphene films on (111)-textured Cu contain grains which are predominantly aligned with the Cu lattice and about 10% of 30°-rotated grains (anti-grains). Such graphene films are exclusively monolayer and possess good electrical conductivity, high carrier mobility, and room temperature quantum Hall effect. Magnetoresistance measurements reveal that the reduction of the grain sizes from 150 nm to 50 nm produce increasing Anderson localization and the appearance of a transport gap. Owing to the presence of grain boundaries in these anti-grains, epitaxially grown graphene films possess n-type characteristics and exhibit ultra-high sensitivity to adsorbates.

  17. Bioactivity of chemically transformed humic matter from vermicompost on plant root growth.

    Science.gov (United States)

    Dobbss, Leonardo Barros; Pasqualoto Canellas, Luciano; Lopes Olivares, Fábio; Oliveira Aguiar, Natália; Peres, Lázaro Eustáquio Pereira; Azevedo, Mariana; Spaccini, Riccardo; Piccolo, Alessandro; Façanha, Arnoldo R

    2010-03-24

    Chemical reactions (hydrolysis, oxidation, reduction, methylation, alkyl compounds detachment) were applied to modify the structure of humic substances (HS) isolated from vermicompost. Structural and conformational changes of these humic derivatives were assessed by elemental analyses, size exclusion chromatography (HPSEC), solid-state nuclear magnetic resonance ((13)C CPMAS-NMR), and diffusion ordered spectroscopy (DOSY-NMR), whereas their bioactivity was evaluated by changes in root architecture and proton pump activation of tomato and maize. All humic derivatives exhibited a large bioactivity compared to original HS, both KMnO(4)-oxidized and methylated materials being the most effective. Whereas no general relationship was found between bioactivity and humic molecular sizes, the hydrophobicity index was significantly related with proton pump stimulation. It is suggested that the hydrophobic domain can preserve bioactive molecules such as auxins in the humic matter. In contact with root-exuded organic acids the hydrophobic weak forces could be disrupted, releasing bioactive compounds from humic aggregates. These findings were further supported by the fact that HS and all derivatives used in this study activated the auxin synthetic reporter DR5::GUS. PMID:20232906

  18. The Destruction of Protogalaxies by Pop III Supernovae: Prompt Chemical Enrichment and Supermassive Black Hole Growth

    CERN Document Server

    Whalen, Daniel J; Smidt, Joseph; Meiksin, Avery; Heger, Alexander; Even, Wesley; Fryer, Chris L

    2013-01-01

    The first primitive galaxies formed from accretion and mergers by z ~ 15, and were primarily responsible for cosmological reionization and the chemical enrichment of the early cosmos. But a few of these galaxies may have formed in the presence of strong Lyman-Werner UV fluxes that sterilized them of H_2, preventing them from forming stars or expelling heavy elements into the IGM prior to assembly. At masses of 10^8 Ms and virial temperatures of 10^4 K, these halos began to rapidly cool by atomic lines, perhaps forming 10^4 - 10^6 Ms Pop III stars and, later, the seeds of supermassive black holes. We have modeled the explosion of a supermassive Pop III star in the dense core of a line-cooled protogalaxy with the ZEUS-MP code. We find that the supernova (SN) expands to a radius of ~ 1 kpc, briefly engulfing the entire galaxy, but then collapses back into the potential well of the dark matter. Fallback fully mixes the interior of the protogalaxy with metals, igniting a violent starburst and fueling the rapid gro...

  19. Use of simple body measurements and allometry to predict the chemical growth and feed intake in pigs

    Directory of Open Access Journals (Sweden)

    Andrea Piva

    2010-01-01

    Full Text Available The paper provides a practical procedure to estimate the chemical composition of pigs, their compositional growth and the expected feed intake from measurements of body weight (BW and backfat thickness (P2 serially performed in vivo. A farm data set provided information on 920 individuals including BW, measured at 71 ± 4 (t1, 126 ± 5 (t2 and 184 ± 5 (t3 days of age, of P2 at t2 and t3, and of voluntary daily feed intake (FI, recorded over the period from t2 to t3 by automated IVOG feeders. Body lipid mass was estimated as L= (9.17 + 0.70*P2 *BW/100 and the other chemical constituents were predicted from fat free empty body mass using Gompertz growth functions and allometry. Using individual changes of body composition from age t2 to t3, energy requirements for maintenance and growth and the corresponding predicted feed intakes (PFI were estimated. Measured FI were analysed for the effects of month, batch (within month, BWt2, P2t2, average metabolic weight, average daily gain and variation of P2 from t2 to t3. The same model was run again replacing the direct simple body measurements (BW and P2 with the estimated values of PFI as source of variation. Results. The Gompertz estimates of mature protein mass (Pm, relative growth rate parameter (B and lipid to protein ratio at maturity were 43.5 ± 5.8 kg, 0.0116 ± 0.0011 d-1 and 1.81 ± 0.30, respectively. The current protein mass averaged 18.5 + 1.6 kg and the daily retentions of protein and lipid were 177 ± 21 and 239 ± 62 g/d, respectively. FI and PFI averaged 2.824 ± 0.448 and 2.814 ± 0.393 kg/d, respectively. In the ANOVA of the FI data, the replacement of direct body measurements by PFI did not change the proportion of variance explained (83% and the RSD (0.199 g/d. The two sets of residual feed intake values obtained from the two ANOVA were highly correlated (RSD = 0.043 kg/d; R2= 0.961. Agreement between predicted and determined feed intakes provided a reasonable guarantee to the

  20. Depletion of tumor associated macrophages slows the growth of chemically-induced mouse lung adenocarcinomas

    Directory of Open Access Journals (Sweden)

    Jason M. Fritz

    2014-11-01

    Full Text Available Chronic inflammation is a risk factor for lung cancer, and low dose aspirin intake reduces lung cancer risk. However, the roles that specific inflammatory cells and their products play in lung carcinogenesis have yet to be fully elucidated. In mice, alveolar macrophage numbers increase as lung tumors progress, and pulmonary macrophage programming changes within 2 weeks of carcinogen exposure. To examine how macrophages specifically affect lung tumor progression, they were depleted in mice bearing urethane-induced lung tumors using clodronate-encapsulated liposomes. Alveolar macrophage populations decreased to ≤ 50% of control levels after 4-6 weeks of liposomal clodronate treatment. Tumor burden decreased by 50% compared to vehicle treated mice, and tumor cell proliferation, as measured by Ki67 staining, was also attenuated. Pulmonary fluid levels of IGF-I, CXCL1, IL-6 and CCL2 diminished with clodronate liposome treatment. Tumor associated macrophages expressed markers of both M1 and M2 programming in vehicle and clodronate liposome treated mice. Mice lacking CCR2 (the receptor for macrophage chemotactic factor CCL2 had comparable numbers of alveolar macrophages and showed no difference in tumor growth rates when compared to similarly treated wild-type mice suggesting that while CCL2 may recruit macrophages to lung tumor microenvironments, redundant pathways can compensate when CCL2/CCR2 signaling is inactivated. Depletion of pulmonary macrophages rather than inhibition of their recruitment may be an advantageous strategy for attenuating lung cancer progression.

  1. Quantum-chemical modeling of the adsorption of 2-aminopropanoic acid on iron depending on the active acidity of an aqueous solution

    Directory of Open Access Journals (Sweden)

    Andrei Sikachina

    2015-01-01

    Full Text Available In research attempt to simulate passing of reaction (on an example of 2-aminopropanic acids with the iron cluster is made, and to identify that reaction with representation about adsorption nitroorganic substance on iron. That is a key to understanding of the corrosion-preventive inhibitor protection. Changes of value following quanto -chemical descriptors are examined: partial efficient charges by Mulliken, energy boundary of orbitals.

  2. An investigation on the chemical stability and a novel strategy for long-term stabilization of diphenylalanine nanostructures in aqueous solution

    OpenAIRE

    H. Nezammahalleh; Amoabediny, G.; F. Kashanian; M.H. Foroughi Moghaddam

    2015-01-01

    The stability of diphenylalanine (FF) microwires and microtubes in phosphate buffer solution was investigated and a novel strategy was developed for their chemical stabilization. This stability investigation was carried out by optical microscopy and by high performance liquid chromatography (HPLC). These microstructures dissolve in the solution depending upon their degree of FF saturation. The dissolution mechanisms of the structures in kinetically limited processes were found by accurately f...

  3. An investigation on the chemical stability and a novel strategy for long-term stabilization of diphenylalanine nanostructures in aqueous solution

    Science.gov (United States)

    Nezammahalleh, H.; Amoabediny, G.; Kashanian, F.; Foroughi Moghaddam, M. H.

    The stability of diphenylalanine (FF) microwires and microtubes in phosphate buffer solution was investigated and a novel strategy was developed for their chemical stabilization. This stability investigation was carried out by optical microscopy and by high performance liquid chromatography (HPLC). These microstructures dissolve in the solution depending upon their degree of FF saturation. The dissolution mechanisms of the structures in kinetically limited processes were found by accurately fitting the experimental dissolution data to a theoretical kinetic equation. The dissolution data were well fitted to the particular Avrami-Erofe'ev kinetic expression (R2 > 0.98). These findings suggest that the structures can be stabilized by a decrease in the hydration of the constituent molecules thorough a chemical conformational induced transition upon heat treatment. The stable microtubes were fabricated in a novel three step procedure consisting of the reduction of silver ions in unstable FF microtubes by a citrate reductant, the stabilization by chemical conformational induced transition upon heat treatment, and the consequent oxidation of the reduced silver by a persulfate oxidant. These materials were characterized by electron microscopy and powder X-ray diffraction techniques. The long-term stability of both structures was also confirmed by optical microscopy and HPLC.

  4. An investigation on the chemical stability and a novel strategy for long-term stabilization of diphenylalanine nanostructures in aqueous solution

    Directory of Open Access Journals (Sweden)

    H. Nezammahalleh

    2015-01-01

    Full Text Available The stability of diphenylalanine (FF microwires and microtubes in phosphate buffer solution was investigated and a novel strategy was developed for their chemical stabilization. This stability investigation was carried out by optical microscopy and by high performance liquid chromatography (HPLC. These microstructures dissolve in the solution depending upon their degree of FF saturation. The dissolution mechanisms of the structures in kinetically limited processes were found by accurately fitting the experimental dissolution data to a theoretical kinetic equation. The dissolution data were well fitted to the particular Avrami-Erofe’ev kinetic expression (R2 > 0.98. These findings suggest that the structures can be stabilized by a decrease in the hydration of the constituent molecules thorough a chemical conformational induced transition upon heat treatment. The stable microtubes were fabricated in a novel three step procedure consisting of the reduction of silver ions in unstable FF microtubes by a citrate reductant, the stabilization by chemical conformational induced transition upon heat treatment, and the consequent oxidation of the reduced silver by a persulfate oxidant. These materials were characterized by electron microscopy and powder X-ray diffraction techniques. The long-term stability of both structures was also confirmed by optical microscopy and HPLC.

  5. Effects of chemical and biological pesticides on plant growth parameters and rhizospheric bacterial community structure in Vigna radiata.

    Science.gov (United States)

    Singh, Sunil; Gupta, Rashi; Sharma, Shilpi

    2015-06-30

    With increasing application of pesticides in agriculture, their non-target effects on soil microbial communities are critical to soil health maintenance. The present study aimed to evaluate the effects of chemical pesticides (chlorpyrifos and cypermethrin) and a biological pesticide (azadirachtin) on growth parameters and the rhizospheric bacterial community of Vigna radiata. Qualitative and quantitative analysis by PCR-denaturing gradient gel electrophoresis (DGGE) and q-PCR, respectively, of the 16S rRNA gene and transcript were performed to study the impact of these pesticides on the resident and active rhizospheric bacterial community. While plant parameters were not affected significantly by the pesticides, a shift in the bacterial community structure was observed with an adverse effect on the abundance of 16S rRNA gene and transcripts. Chlorpyrifos showed almost complete degradation toward the end of the experiment. These non-target impacts on soil ecosystems and the fact that the effects of the biopesticide mimic those of chemical pesticides raise serious concerns regarding their application in agriculture. PMID:25791643

  6. Chemical Composition of the Fruits of Several Apple Cultivars Growth as Biological Crop

    Directory of Open Access Journals (Sweden)

    Gheorghe CAMPEANU

    2009-11-01

    Full Text Available To obtain a better quality of fruits and to adapt to the requirements of consumers needs, the researchers regard the content of fruits attentively, especially the content of sugar, vitamins and mineral substances. The aims of the research were to test ten apple cultivars from the point of view of sugars, water content, proteins, acidity, vitamin C and also mineral elements: N, P, K, Ca, Mg, Fe. Results obtain for sugars show a higher content of sugar between 9.53 and 12.34%. The higher sugar content was registered for H3/73 hybrid (12.34%. Total acidity (% falls between 0.127 and 0.345%, a small content registered at all cultivars determining a good quality of fruits and a good taste. The highest value was obtained for Jonathan apple variety. Vitamin C varied between 25.75 and 77 mg/100g. Mutzu and Jonathan cultivars registered the highest value for vitamin C. Mineral elements, respectively macro elements N, P and K varied within the apple varieties. Total nitrogen form varied between 0.67 and 0.111 %, phosphorous between 0.15 and 0.235 % and potassium between 0.40 and 0.75 %. The values for Ca varied between 2.5 and 7.8 mg/100g and Fe between 0.2 and 0.28 mg/100g. The atmosphere and soil in the studied zone of apple culture were unpolluted, so there was no risk of food contamination. The chemical values of fruits showed a higher content of mineral elements and also a good quality for the products obtained from the apple industry, so the apple production could be used in obtaining juice and pulp without any risk of illness.

  7. Growth of novel ceramic layers on metals via chemical and heat treatments for inducing various biological functions

    Directory of Open Access Journals (Sweden)

    Tadashi eKokubo

    2015-10-01

    Full Text Available The present authors’ systematic studies on growth of novel ceramic layers on Ti metal and its alloys by chemical and heat treatments for inducing bone-bonding bioactivity and some other biological functions are reviewed. Ti metal formed an apatite on its surface in a simulated body fluid (SBF, when heat-treated after exposure to strong acid solutions to form rutile surface layer, or to strong alkali solutions to form sodium titanate surface layer. Both types of Ti metal tightly bonded to the living bone.The alkali and heat treatment was applied to the surface Ti metal of an artificial hip joint and successfully used in the clinic since 2007. The acid and heat treatments was applied to porous Ti metal to induce osteoconductivity as well as osteoinductivity. The resulting product was successfully used in clinical trials for spinal fusion devices. For the Ti-based alloys, the alkali and heat treatment was a little modified to form calcium titanate surface layer. Bone-growth promoting Mg, Sr, and Zn ions as well as the antibacterial Ag ion were successfully incorporated into the calcium titanate layer.

  8. Growth of Novel Ceramic Layers on Metals via Chemical and Heat Treatments for Inducing Various Biological Functions.

    Science.gov (United States)

    Kokubo, Tadashi; Yamaguchi, Seiji

    2015-01-01

    The present authors' systematic studies on growth of novel ceramic layers on Ti metal and its alloys by chemical and heat treatments for inducing bone-bonding bioactivity and some other biological functions are reviewed. Ti metal formed an apatite on its surface in a simulated body fluid, when heat-treated after exposure to strong acid solutions to form rutile surface layer, or to strong alkali solutions to form sodium titanate surface layer. Both types of Ti metal tightly bonded to the living bone. The alkali and heat treatment was applied to the surface Ti metal of an artificial hip joint and successfully used in the clinic since 2007. The acid and heat treatments was applied to porous Ti metal to induce osteoconductivity as well as osteoinductivity. The resulting product was successfully used in clinical trials for spinal fusion devices. For the Ti-based alloys, the alkali and heat treatment was little modified to form calcium titanate surface layer. Bone-growth promoting Mg, Sr, and Zn ions as well as the antibacterial Ag ion were successfully incorporated into the calcium titanate layer. PMID:26579517

  9. Role of Duty Ratio in Diamond Growth by Pulsed DC-Bias Enhanced Hot Filament Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    MENG Liang; ZHOU Haiyang; ZHU Xiaodong

    2007-01-01

    In this study, the role of the pulse duty ratio was investigated during the deposition of diamond films in a hot filament chemical vapour deposition reactor with a pulsed-dc biased substrate positively relative to the hot filaments. The voltage-current characteristics showed that the discharge current rose with the increase of biasing voltage, which was modified by the duty ratio. Before deposition, two approaches were adopted for the pre-treatment of the silicon substrates, respectively, and the substrates were scratched by diamond paste or seeded by diamond powders using the so-called 'soft dry polished' technique. Diamond films were deposited under a fixed discharge power by changing the duty ratios. In the first group with scratched substrates, it was found that under a high duty ratio the diamond grew slowly with quite poor nucleation, while in the second case a high duty ratio induced a high deposition rate and good diamond quality. Reactive hydrocarbon species with high energy are essential for the initial nucleation process, which is more effectively achieved at a high biasing voltage in the condition of a low duty ratio. In the film growth process, the large discharge current at a high duty ratio represents an increased concentration of electrons and reactive species as well, promoting the growth of diamond films.

  10. Growth of Ge Layer on Relaxed Ge-Rich SiGe by Ultrahigh Vacuum Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The paper describes the growth of a germanium (Ge) film on a thin relaxed Ge-rich SiGe buffer.The thin Ge-rich SiGe buffer layer was achieved through a combination of ultrahigh vacuum chemical vapor deposition (UHVCVD) SiGe epitaxial growth and SiGe oxidation. A lower Ge content strained SiGe layer was first grown on the Si (001) substrate and then the Ge mole fraction was increased by oxidation. After removal of the surface oxide, a higher Ge content SiGe layer was grown and oxidized again. The Ge mole fraction was increased to 0.8 in the 50 nm thick SiGe layer. Finally a 150 nm thick pure Ge film was grown on the SiGe buffer layer using the UHVCVD system. This technique produces a much thinner buffer than the conventional compositionally graded relaxed SiGe method with the same order of magnitude threading dislocation density.

  11. Growth-substrate induced performance degradation in chemically synthesized monolayer MoS2 field effect transistors

    International Nuclear Information System (INIS)

    We report on the electronic transport properties of single-layer thick chemical vapor deposition (CVD) grown molybdenum disulfide (MoS2) field-effect transistors (FETs) on Si/SiO2 substrates. MoS2 has been extensively investigated for the past two years as a potential semiconductor analogue to graphene. To date, MoS2 samples prepared via mechanical exfoliation have demonstrated field-effect mobility values which are significantly higher than that of CVD-grown MoS2. In this study, we will show that the intrinsic electronic performance of CVD-grown MoS2 is equal or superior to that of exfoliated material and has been possibly masked by a combination of interfacial contamination on the growth substrate and residual tensile strain resulting from the high-temperature growth process. We are able to quantify this strain in the as-grown material using pre- and post-transfer metrology and microscopy of the same crystals. Moreover, temperature-dependent electrical measurements made on as-grown and transferred MoS2 devices following an identical fabrication process demonstrate the improvement in field-effect mobility

  12. Growth-substrate induced performance degradation in chemically synthesized monolayer MoS{sub 2} field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Amani, Matin; Chin, Matthew L.; Mazzoni, Alexander L.; Burke, Robert A.; Dubey, Madan, E-mail: madan.dubey.civ@mail.mil [Sensors and Electron Devices Directorate, US Army Research Laboratory, Adelphi, Maryland 20723 (United States); Najmaei, Sina; Ajayan, Pulickel M.; Lou, Jun [Department of Materials Science and Nanoengineering, Rice University, Houston, Texas 77005 (United States)

    2014-05-19

    We report on the electronic transport properties of single-layer thick chemical vapor deposition (CVD) grown molybdenum disulfide (MoS{sub 2}) field-effect transistors (FETs) on Si/SiO{sub 2} substrates. MoS{sub 2} has been extensively investigated for the past two years as a potential semiconductor analogue to graphene. To date, MoS{sub 2} samples prepared via mechanical exfoliation have demonstrated field-effect mobility values which are significantly higher than that of CVD-grown MoS{sub 2}. In this study, we will show that the intrinsic electronic performance of CVD-grown MoS{sub 2} is equal or superior to that of exfoliated material and has been possibly masked by a combination of interfacial contamination on the growth substrate and residual tensile strain resulting from the high-temperature growth process. We are able to quantify this strain in the as-grown material using pre- and post-transfer metrology and microscopy of the same crystals. Moreover, temperature-dependent electrical measurements made on as-grown and transferred MoS{sub 2} devices following an identical fabrication process demonstrate the improvement in field-effect mobility.

  13. Growth-substrate induced performance degradation in chemically synthesized monolayer MoS2 field effect transistors

    Science.gov (United States)

    Amani, Matin; Chin, Matthew L.; Mazzoni, Alexander L.; Burke, Robert A.; Najmaei, Sina; Ajayan, Pulickel M.; Lou, Jun; Dubey, Madan

    2014-05-01

    We report on the electronic transport properties of single-layer thick chemical vapor deposition (CVD) grown molybdenum disulfide (MoS2) field-effect transistors (FETs) on Si/SiO2 substrates. MoS2 has been extensively investigated for the past two years as a potential semiconductor analogue to graphene. To date, MoS2 samples prepared via mechanical exfoliation have demonstrated field-effect mobility values which are significantly higher than that of CVD-grown MoS2. In this study, we will show that the intrinsic electronic performance of CVD-grown MoS2 is equal or superior to that of exfoliated material and has been possibly masked by a combination of interfacial contamination on the growth substrate and residual tensile strain resulting from the high-temperature growth process. We are able to quantify this strain in the as-grown material using pre- and post-transfer metrology and microscopy of the same crystals. Moreover, temperature-dependent electrical measurements made on as-grown and transferred MoS2 devices following an identical fabrication process demonstrate the improvement in field-effect mobility.

  14. Amphoteric Aqueous Hafnium Cluster Chemistry.

    Science.gov (United States)

    Goberna-Ferrón, Sara; Park, Deok-Hie; Amador, Jenn M; Keszler, Douglas A; Nyman, May

    2016-05-17

    Selective dissolution of hafnium-peroxo-sulfate films in aqueous tetramethylammonium hydroxide enables extreme UV lithographic patterning of sub-10 nm HfO2 structures. Hafnium speciation under these basic conditions (pH>10), however, is unknown, as studies of hafnium aqueous chemistry have been limited to acid. Here, we report synthesis, crystal growth, and structural characterization of the first polynuclear hydroxo hafnium cluster isolated from base, [TMA]6 [Hf6 (μ-O2 )6 (μ-OH)6 (OH)12 ]⋅38 H2 O. The solution behavior of the cluster, including supramolecular assembly via hydrogen bonding is detailed via small-angle X-ray scattering (SAXS) and electrospray ionization mass spectrometry (ESI-MS). The study opens a new chapter in the aqueous chemistry of hafnium, exemplifying the concept of amphoteric clusters and informing a critical process in single-digit-nm lithography. PMID:27094575

  15. Petrological cannibalism: the chemical and textural consequences of incremental magma body growth

    Science.gov (United States)

    Cashman, Kathy; Blundy, Jon

    2013-09-01

    The textures of minerals in volcanic and plutonic rocks testify to a complexity of processes in their formation that is at odds with simple geochemical models of igneous differentiation. Zoning in plagioclase feldspar is a case in point. Very slow diffusion of the major components in plagioclase means that textural evidence for complex magmatic evolution is preserved, almost without modification. Consequently, plagioclase affords considerable insight into the processes by which magmas accumulate in the crust prior to their eventual eruption or solidification. Here, we use the example of the 1980-1986 eruptions of Mount St. Helens to explore the causes of textural complexity in plagioclase and associated trapped melt inclusions. Textures of individual crystals are consistent with multiple heating and cooling events; changes in total pressure ( P) or volatile pressure () are less easy to assess from textures alone. We show that by allying textural and chemical analyses of plagioclase and melt inclusions, including volatiles (H2O, CO2) and slow-diffusing trace elements (Sr, Ba), to published experimental studies of Mount St. Helens magmas, it is possible to disambiguate the roles of pressure and temperature to reconstruct magmatic evolutionary pathways through temperature-pressure-melt fraction ( T-- F) space. Our modeled crystals indicate that (1) crystallization starts at > 300 MPa, consistent with prior estimates from melt inclusion volatile contents, (2) crystal cores grow at = 200-280 MPa at F = 0.65-0.7, (3) crystals are transferred to = 100-130 MPa (often accompanied by 10-20 °C of heating), where they grow albitic rims of varying thicknesses, and (4) the last stage of crystallization occurs after minor heating at ~ 100 MPa to produce characteristic rim compositions of An50. We hypothesize that modeled decreases in excess of ~50 MPa most likely represent upward transport through the magmatic system. Small variations in modeled , in contrast, can be effected by

  16. Application of Chemical Doping and Architectural Design Principles To Fabricate Nanowire Co2Ni3ZnO8 Arrays for Aqueous Asymmetric Supercapacitors.

    Science.gov (United States)

    Liu, Qi; Yang, Bin; Liu, Jingyuan; Yuan, Yi; Zhang, Hongsen; Liu, Lianhe; Wang, Jun; Li, Rumin

    2016-08-10

    Electrode materials derived from transition metal oxides have a serious problem of low electron transfer rate, which restricts their practical application. However, chemically doped graphene transforms the chemical bonding configuration to enhance electron transfer rate and, therefore, facilitates the successful fabrication of Co2Ni3ZnO8 nanowire arrays. In addition, the Co2Ni3ZnO8 electrode materials, considered as Ni and Zn ions doped into Co3O4, have a high electron transfer rate and electrochemical response capability, because the doping increases the degree of crystal defect and reaction of Co/Ni ions with the electrolyte. Hence, the Co2Ni3ZnO8 electrode exhibits a high rate property and excellent electrochemical cycle stability, as determined by electrochemical analysis of the relationship between specific capacitance, IR drop, Coulomb efficiency, and different current densities. From the results of a three-electrode system of electrochemical measurement, the Co2Ni3ZnO8 electrode demonstrates a specific capacitance of 1115 F g(-1) and retains 89.9% capacitance after 2000 cycles at a current density of 4 A g(-1). The energy density of the asymmetric supercapacitor (AC//Co2Ni3ZnO8) is 54.04 W h kg(-1) at the power density of 3200 W kg(-1).

  17. The Standard Chemical-Thermodynamic Properties of Phosphorus and Some of its Key Compounds and Aqueous Species: An Evaluation of Differences between the Previous Recommendations of NBS/NIST and CODATA

    Energy Technology Data Exchange (ETDEWEB)

    Rard, J A; Wolery, T J

    2007-01-30

    The aqueous chemistry of phosphorus is dominated by P(V), which under typical environmental conditions (and depending on pH and concentration) can be present as the orthophosphate ions H{sub 3}PO{sub 4}{sup 0}(aq), H{sub 2}PO{sub 4}{sup -}(aq), HPO{sub 4}{sup 2-}(aq), or PO{sub 4}{sup 3-}(aq). Many divalent, trivalent, and tetravalent metal ions form sparingly soluble orthophosphate phases that, depending on the solution pH and concentrations of phosphate and metal ions, can be solubility limiting phases. Geochemical and chemical engineering modeling of solubilities and speciation requires comprehensive thermodynamic databases that include the standard thermodynamic properties for the aqueous species and solid compounds. The most widely used sources for standard thermodynamic properties are the NBS (now NIST) Tables (from 1982 and earlier; with a 1989 erratum) and the final CODATA evaluation (1989). However, a comparison of the reported enthalpies of formation and Gibbs energies of formation for key phosphate compounds and aqueous species, especially H{sub 2}PO{sub 4}{sup -}(aq) and HPO{sub 4}{sup 2-}(aq), shows a systematic and nearly constant difference of 6.3 to 6.9 kJ {center_dot} mol{sup -1} per phosphorus atom between these two evaluations. The existing literature contains numerous studies (including major data summaries) that are based on one or the other of these evaluations. In this report we examine and identify the origin of this difference and conclude that the CODATA evaluation is more reliable. Values of the standard entropies of the H{sub 2}PO{sub 4}{sup -}(aq), HPO{sub 4}{sup 2-}(aq), and PO{sub 4}{sup 3-}(aq) ions at 298.15 K and p{sup o} = 1 bar were re-examined in the light of more recent information and data not considered in the CODATA review, and a slightly different value of S{sub m}{sup o}(H{sub 2}PO{sub 4}{sup -}, aq, 298.15 K) = 90.6 {+-} 1.5 J {center_dot} K{sup -1} mol{sup -1} was obtained.

  18. Allelopathic Effects of Aqueous Extract of Leaf Stem and Root of Sorghum bicolor on Seed Germination and Seedling Growth of Vigna radiata L.

    Directory of Open Access Journals (Sweden)

    Amir MOOSAVI

    2011-05-01

    Full Text Available Seed germination under field conditions is highly influenced by the presence of other plants. Allelopathy is an important mechanism of plant competition, by producing phytotoxins to the plant environment in order to decline other plants� growth. Soil sickness problem in farm lands is also known as an allelopathic effect or even autotoxicity. The toxicity of released allelochemicals by a plant in the environment is attributed to its function of concentration, age and metabolic stage. In this study we investigate the effect (5, 20, 35 and 50 g l-1 of leaf, stem and root water extract of sorghum on seed germination and seedling growth of mung bean. The results of the experiment showed that allelopathic effect of different concentrations was not significant for germination percentage, but germination rate and mean germination time decreased significantly by increasing the concentration of allelopathic extracts; also, there was a clear allelopathic effect of sorghum extract on seedling growth of mung bean. 50 g l-1 sorghum stem extract exhibited the highest inhibitory effect on root and shoot growth of mung bean. Among all parts of sorghum, stem extracts showed the highest allelopatic effect on seedling growth. Root extract showed higher inhibitory effect than leaf extracts.

  19. Parameters study on the growth of GaAs nanowires on indium tin oxide by metal-organic chemical vapor deposition

    Science.gov (United States)

    Wu, Dan; Tang, Xiaohong; Wang, Kai; Olivier, Aurelien; Li, Xianqiang

    2016-03-01

    After successful demonstration of GaAs nanowire (NW) epitaxial growth on indium tin oxide (ITO) by metal organic chemical vapor deposition, we systematically investigate the effect of growth parameters' effect on the GaAs NW, including temperature, precursor molar flow rates, growth time, and Au catalyst size. 40 nm induced GaAs NWs are observed with zinc-blende structure. Based on vapor-liquid-solid mechanism, a kinetic model is used to deepen our understanding of the incorporation of growth species and the role of various growth parameters in tuning the GaAs NW growth rate. Thermally activated behavior has been investigated by variation of growth temperature. Activation energies of 40 nm Au catalyst induced NWs are calculated at different trimethylgallium (TMGa) molar flow rates about 65 kJ/mol. The GaAs NWs growth rates increase with TMGa molar flow rates whereas the growth rates are almost independent of growth time. Due to Gibbs-Thomson effect, the GaAs NW growth rates increase with Au nanoparticle size at different temperatures. Critical radius is calculated as 2.14 nm at the growth condition of 430 °C and 1.36 μmol/s TMGa flow rate. It is also proved experimentally that Au nanoparticle below the critical radius such as 2 nm cannot initiate the growth of NWs on ITO. This theoretical and experimental growth parameters investigation enables great controllability over GaAs NWs grown on transparent conductive substrate where the methodology can be expanded to other III-V material NWs and is critical for potential hybrid solar cell application.

  20. Optimisation of hybridoma cell growth and monoclonal antibody secretion in a chemically defined, serum- and protein-free culture medium.

    Science.gov (United States)

    Schneider, Y J

    1989-01-01

    Monoclonal antibodies (MAbs), for human use require chemical and biological purity. The best approach seems in vitro cultivation in a serum-, protein-free medium. A basal defined culture medium has been developed to sustain optimal hybridoma cell growth and MAb secretion. It consists of Iscove's Dulbecco's modified, Eagle's, Ham's F12 and NCTC 135 media in a 5:5:1 mixture (v/v/v), to which glucose is added to reach a final concentration of 25 mM, glutamine to 4-6 mM, 2-mercaptoethanol to 50 microM, Pluronic F68 to 0.01-0.1% (w/v), Hepes to 25 mM and NaHCO3 to 3 g/l. Hybridoma cells, derived from Sp 2/0 myeloma and secreting a MAb to a human milk fat globule membrane-associated high molecular weight glycoprotein, were cloned in this medium containing 1% (v/v) fetal calf serum and then sequentially adapted in serum-free medium further supplemented with transferrin and insulin, both at 10 micrograms/ml. Clones producing immunoreactive MAbs secrete a mean of 50 micrograms IgG/ml, i.e., ca. 80% of the concentration reached in Dulbecco's modified Eagle's medium containing 10% serum. When cells were cultured in spinner flasks with a semi-continuous mode of cultivation (with a daily removal of 20% of the volume and its replacement by fresh culture medium), in serum-free medium further supplemented with 10 nM estradiol, a mixture of trace elements and albumin (at 30 micrograms/ml) complexed to linoleic acid, MAb secretion reached 100 micrograms/ml and became equal or higher to that obtained in serum-containing medium. MAb secretion was not decreased and was even significantly increased during the growth phase, when transferrin was replaced by another iron source, i.e., ferric citrate at 500 microM associated with 20 microM ascorbic acid. Finally, deletion of insulin and of albumin-linoleic acid did not affect significantly cell density nor MAb secretion. In conclusion, it appears from this study that semi-continuous cultivation in spinner flasks of hybridoma cells, after

  1. Wet chemical synthesis of soluble gold nanogaps

    DEFF Research Database (Denmark)

    Jain, Titoo; Tang, Qingxin; Bjørnholm, Thomas;

    2014-01-01

    with little variation in the interface between molecule and electrode (AuNR). In this Account, we highlight recent progress in using chemically synthesized AuNRs as building blocks for molecular electronic applications. We outline the general synthesis and properties of AuNRs and describe the aqueous growth...... of dimeric AuNR structures from an insulating molecule linked to AuNR precursors (gold seeds). Conjugated, electronically active molecules are typically not soluble under the conditions required for the bottom-up growth of AuNRs. Therefore, we present a strategy that utilizes host-guest chemistry in order...

  2. Synthesis of Aqueous CdTe/CdS/ZnS Core/shell/shell Quantum Dots by a Chemical Aerosol Flow Method

    Directory of Open Access Journals (Sweden)

    Chen Dong

    2009-01-01

    Full Text Available Abstract This work described a continuous method to synthesize CdTe/CdS/ZnS core/shell/shell quantum dots. In an integrated system by flawlessly combining the chemical aerosol flow system working at high temperature (200–300°C to generate CdTe/CdS intermediate products and an additional heat-up setup at relatively low temperature to overcoat the ZnS shells, the CdTe/CdS/ZnS multishell structures were realized. The as-synthesized CdTe/CdS/ZnS core/shell/shell quantum dots are characterized by photoluminescence spectra, X-ray diffraction (XRD, energy-dispersive X-ray spectra (EDS, transmission electron microscopy (TEM, and high-resolution transmission electron microscopy (HRTEM. Fluorescence and XRD results confirm that the obtained quantum dots have a core/shell/shell structure. It shows the highest quantum yield above 45% when compared to the rhodamine 6G. The core/shell/shell QDs were more stable via the oxidation experiment by H2O2.

  3. Novel biosorbent with high adsorption capacity prepared by chemical modification of white pine (Pinus durangensis) sawdust. Adsorption of Pb(II) from aqueous solutions.

    Science.gov (United States)

    Salazar-Rabago, J J; Leyva-Ramos, R

    2016-03-15

    The natural sawdust (NS) from white pine (Pinus durangensis) was chemically modified by a hydrothermal procedure using citric, malonic and tartaric acids. The adsorption capacity of modified sawdust (MS) towards Pb(II) was considerably enhanced due to the introduction of carboxylic groups on the surface of MS during the modification, and the adsorption capacity was almost linearly dependent on the concentration of carboxylic sites. The NS surface was acidic, and the MS surface became more acidic after the modification. At T = 25 °C and pH = 5, the maximum adsorption capacity of the optimal MS towards Pb(II) was 304 mg/g, which is exceptionally high compared to NS and other MS reported previously. The adsorption capacity of MS was considerably reduced from 304 to 154 mg/g by decreasing the solution pH from 5 to 3 due to electrostatic interactions. The adsorption of Pb(II) on MS was reversible at pH = 2, but not at pH = 5. The contribution percentage of ion exchange to the overall adsorption capacity ranged from 70 to 99% and 10-66% at the initial pH of 3 and 5, respectively. Hence, the adsorption of Pb(II) on MS was mainly due to ion exchange at pH = 3 and to both ion exchange and electrostatic attraction at pH = 5.

  4. a Study of Volatile Precursors for the Growth of Cadmium Sulphide and Cadmium Selenide by Metal Organic Chemical Vapour Deposition.

    Science.gov (United States)

    Beer, Michael P.

    Available from UMI in association with The British Library. The wide-band-gap semiconductors, cadmium sulphide and cadmium selenide, may be grown by Metal Organic Chemical Vapour Deposition (MOCVD). This method typically involves the reaction of gaseous streams of Me_2 Cd and H_2Y (Y = S, Se) over a heated substrate (usually gallium arsenide) on which the desired compound is grown as an epitaxial layer. Unfortunately, the precursors start to react in the cold zone of the reactor, that is before they reach the heated substrate. This problem is known as prereaction. The problem of prereaction is partially reduced by the use of adducts of dimethyl cadmium in place of the free dialkyl compound although the mechanism by which such adducts block prereaction is unknown. Accordingly, a study of adducts of dimethyl cadmium was undertaken with a view to determining their properties in all phases. The adduct of Me_2Cd with 2,2^ '-bipyridyl was found to be monomeric in the solid state while that with 1,4-dioxane, a volatile compound used for prereaction reduction, was found to be polymeric. A study of adducts in the gas phase using mass spectrometry and gas phase Fourier transform infrared spectroscopy gave no evidence to suggest there is any gas phase association between 1,4-dioxane and dimethyl cadmium. With the 2,2 ^'-bipyridyl adduct some evidence for partial retention of coordinate bonds upon sublimation was obtained. The solid adduct of Me _2Cd with N,N,N^' ,N^'-tetramethylethylenediamine (TMEDA) was prepared as it was hoped that the flexibility of the aliphatic Lewis base would permit the formation of an adduct containing strong co-ordinate bonds which would remain intact upon sublimation. Using gas phase electron diffraction, the structure of the adduct of Me_2Cd and TMEDA was determined. It was shown to exist in the gas phase purely as the associated monomeric species. The adduct was then employed for the growth of CdS and CdSe in an industrial MOCVD apparatus. The

  5. Growth of Ag-nanoparticles in an aqueous solution and their antimicrobial activities against Gram positive, Gram negative bacterial strains and Candida fungus.

    Science.gov (United States)

    Aazam, Elham Shafik; Zaheer, Zoya

    2016-04-01

    Silver nanoparticles (AgNPs) were synthesized using Ocimum sanctum (Tulsi) leaves aqueous extract as reducing as well as a capping agent in absence and presence of cetyltrimethylammonium bromide (CTAB). The resulting nanomaterials were characterized by UV-visible spectrophotometer, and transmission electron microscope. The UV-Vis spectroscopy revealed the formation of AgNPs at 400-450 nm. TEM photographs indicate that the truncated triangular silver nanoplates and/or spherical morphology of the AgNPs with an average diameter of 25 nm have been distorted markedly in presence of CTAB. The AgNPs were almost mono disperse in nature. Antimicrobial activities of AgNPs were determined by using two bacteria (Gram positive Staphylococcus aureus MTCC-3160), Gram negative Escherichia coli MTCC-450) and one species of Candida fungus (Candida albicans ATCC 90030) with Kirby-Bauer or disc diffusion method. The zone of inhibition seems extremely good showing a relatively large zone of inhibition in both Staphylococcus aureus, Escherichia coli, and Candida albicans strains. PMID:26796584

  6. Fatigue of tooth-colored restoratives in aqueous environment.

    Science.gov (United States)

    Kawakami, Yoshiko; Takeshige, Fumio; Hayashi, Mikako; Ebisu, Shigeyuki

    2007-01-01

    The purpose of this study was to investigate the interaction between mechanical and chemical fatigue in resin composites and dental ceramics, and the effects thereof on fatigue resistance of tooth-colored restoratives. To this end, the fatigue fracture resistance of restoratives under dry and aqueous conditions were analyzed by a dynamic fatigue crack propagation test using beam-shaped specimens with a precrack. Fatigue crack propagation characteristics were expressed by the correlation between fatigue crack growth rate (da/dN) and stress intensity factor range (deltaK). In addition, fatigue crack growth threshold (deltaKth) was calculated. Following the fatigue test, a fractographic examination was performed using scanning electron microscopy. Fatigue crack initiation was retarded in resin composites under aqueous condition, but dental ceramics were susceptible to slow crack growth after crack initiation. SEM images of the fatigue facture surfaces reflected inorganic and organic filler particles of different sizes in composites and the bonding at crystal-glass interface in ceramics. It was concluded that water exerted different effects on the fatigue resistance of composites and ceramics.

  7. Undoped and in-situ B doped GeSn epitaxial growth on Ge by atmospheric pressure-chemical vapor deposition

    DEFF Research Database (Denmark)

    Vincent, B.; Gencarelli, F.; Bender, H.;

    2011-01-01

    In this letter, we propose an atmospheric pressure-chemical vapor deposition technique to grow metastable GeSn epitaxial layers on Ge. We report the growth of defect free fully strained undoped and in-situ B doped GeSn layers on Ge substrates with Sit contents up to 8%. Those metastable layers stay...

  8. Benefits of chemical fibre industry down evidently in the first half of 2008 Industrial production growth rate dropped slightly, imports decreased evidently while exports grew steadily

    Institute of Scientific and Technical Information of China (English)

    Gracie; Guo

    2008-01-01

    Production From January to May, China’s chemical fiber production rose 7.4 percent from a year earlier to 10.04 million tons, but that was 10.49 percentage points less than the growth rate during the same five- month period last year,the China National Textile and Apparel

  9. A Comparative Study of Three Different Chemical Vapor Deposition Techniques of Carbon Nanotube Growth on Diamond Films

    Directory of Open Access Journals (Sweden)

    Betty T. Quinton

    2013-01-01

    Full Text Available This paper compares between the methods of growing carbon nanotubes (CNTs on diamond substrates and evaluates the quality of the CNTs and the interfacial strength. One potential application for these materials is a heat sink/spreader for high-power electronic devices. The CNTs and diamond substrates have a significantly higher specific thermal conductivity than traditional heat sink/spreader materials making them good replacement candidates. Only limited research has been performed on these CNT/diamond structures and their suitability of different growth methods. This study investigates three potential chemical vapor deposition (CVD techniques for growing CNTs on diamond: thermal CVD (T-CVD, microwave plasma-enhanced CVD (MPE-CVD, and floating catalyst thermal CVD (FCT-CVD. Scanning electron microscopy (SEM and high-resolution transmission electron microscopy (TEM were used to analyze the morphology and topology of the CNTs. Raman spectroscopy was used to assess the quality of the CNTs by determining the ID/IG peak intensity ratios. Additionally, the CNT/diamond samples were sonicated for qualitative comparisons of the durability of the CNT forests. T-CVD provided the largest diameter tubes, with catalysts residing mainly at the CNT/diamond interface. The MPE-CVD process yielded non uniform defective CNTs, and FCT-CVD resulted in the smallest diameter CNTs with catalyst particles imbedded throughout the length of the nanotubes.

  10. Thickness dependence of grain growth orientation in MgB2 films fabricated by hybrid physical-chemical vapor deposition

    International Nuclear Information System (INIS)

    We have investigated the effect of thickness of the MgB2 film on the grain growth direction as well as on their superconducting properties. MgB2 films of various thicknesses were fabricated on c-cut Al2O3 substrates at a temperature of 540 degree by using hybrid physical-chemical vapor deposition (HPCVD) technique. The superconducting transition temperature (Tc) was found to increase with increase in the thickness of the MgB2 film. X-ray diffraction analysis revealed that the orientation of grains changed from c-axis to a-axis upon increasing the thickness of the MgB2 film from 0.6 to 2.0 μm. MgB2 grains of various orientations were observed in the microstructures of the films examined by scanning electron microscopy. It is observed that at high magnetic fields the 2.0-μm-thick film exhibit considerably larger critical current density (Jc) as compared to 0.6-μm-thick film. The results are discussed in terms of an intrinsic-pinning in MgB2 similarly as intrinsic-pinning occurring in high-Tc cuprate superconductors with layered structure.

  11. Influence of humidity on the growth characteristics and properties of chemical bath-deposited ZnS thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yi-Cheng; Chao, Yen-Tai [Department of Mechatronics Engineering, National Changhua University of Education, Changhua 50007, Taiwan (China); Yao, Pin-Chuan, E-mail: pcyao@mail.dyu.edu.tw [Department of Materials Science and Engineering, Da-Yeh University, Dacun, Changhua 51591, Taiwan (China)

    2014-07-01

    In this study, the effect of humidity on the growth characteristics and properties of chemical bath-deposited ZnS thin films was systematically investigated. All deposition was conducted by an open CBD system under various relative humidity levels (RH) or by a hermetic CBD system as a comparison. It shows, for films deposited by an open system, the ambient humidity plays an important role in the quality of the resultant films. Damp environments lead to powdery films. Generally, all films prepared in this study using NH{sub 3} and hydrazine hydrate as the complexing agents were amorphous or poorly crystalline. For an open system, the [H{sup +}] from the dissolved carbon dioxide in the air competes with the ammonium ions in the bath solution. According to Le Châtelier's principle, more ammonia was consumed, which favors the free [Zn{sup +2}] in the solution, facilitating the homogeneous precipitation of Zn(OH){sub 2} and giving rise to a powdery film. The x-ray photoelectron spectrum shows, for an open system, the content of Zn–O compounds in the form of Zn(OH){sub 2} and ZnO, etc., is increased by the relative humidity of the environment. The visible transmittance is reduced by RH. The higher optical band gap of the as-deposited films could be attributed to the quantum confinement effects due to the small grain size of the polycrystalline ZnS films over the substrates.

  12. Allelopathic Potential of Cucumber Tissues Aqueous Extracts

    Institute of Scientific and Technical Information of China (English)

    DONG Lin-lin; HAO Zhi-peng; ZUO Yuan-mei; LI Xiao-lin; WANG Qian

    2011-01-01

    [ Objective] The aim of this study was to explore allelopathic effects of the water-extracted crude of cucumber plant parts on seed germination and seedling growth of lettuce ( Lactuca sativa L. ), cabbage ( Brassica pekinensis L. ), radish ( Raphanus sativus L. ) and scallion ( Allium fistulosum L. ). [ Method] The allelopathic effects of different cucumber tissues aqueous extracts were investigated on lettuce, cabbage,radish and scallion using the water-soluble allelopathic principle by seedling bioassay tests. [ Result] The trends of inhibitory effects of different cucumber parts increased with increasing extract concentrations. The inhibition effects and the inhibition rate of three aqueous extracts were more significant on root growth than shoot length. Leaf aqueous extracts represented the most exhibited and root aqueous extracts representing the least inhibitory on seed germination, shoot length and root length of lettuce, cabbage, radish and scallion. [Conclusion] This study had provided basis for allelopathic character of different cucumber plant parts.

  13. Efficient Computational Research Protocol to Survey Free Energy Surface for Solution Chemical Reaction in the QM/MM Framework: The FEG-ER Methodology and Its Application to Isomerization Reaction of Glycine in Aqueous Solution.

    Science.gov (United States)

    Takenaka, Norio; Kitamura, Yukichi; Nagaoka, Masataka

    2016-03-01

    In solution chemical reaction, we often need to consider a multidimensional free energy (FE) surface (FES) which is analogous to a Born-Oppenheimer potential energy surface. To survey the FES, an efficient computational research protocol is proposed within the QM/MM framework; (i) we first obtain some stable states (or transition states) involved by optimizing their structures on the FES, in a stepwise fashion, finally using the free energy gradient (FEG) method, and then (ii) we directly obtain the FE differences among any arbitrary states on the FES, efficiently by employing the QM/MM method with energy representation (ER), i.e., the QM/MM-ER method. To validate the calculation accuracy and efficiency, we applied the above FEG-ER methodology to a typical isomerization reaction of glycine in aqueous solution, and reproduced quite satisfactorily the experimental value of the reaction FE. Further, it was found that the structural relaxation of the solute in the QM/MM force field is not negligible to estimate correctly the FES. We believe that the present research protocol should become prevailing as one computational strategy and will play promising and important roles in solution chemistry toward solution reaction ergodography. PMID:26794718

  14. 房水培养对牛角膜内皮细胞生长的影响%Influence of aqueous humor on growth of bovine corneal endothelial cell in vitro

    Institute of Scientific and Technical Information of China (English)

    李善义; 戴应; 谭美华; 丁勇; 钟敬祥; 陈建苏

    2013-01-01

    in the control group,showing a significant difference (t =-5.729,P=0.005).The scratch test showed that the healing area of the cell signal layer was (0.116±0.019) mm2 in the 10.0% aqueous humors group and (0.358 ±0.049) mm2 in the control group,showing a significant difference (t =13.842,P =0.000).The density of cells in the 10.0% aqueous humor group was (1439± 1 10)/field,which was more than (1162±45)/field in the control group (t =-11.020,P=0.000).Conclusions Aqueous humor at the concentration of 10.0% promote the growth and proliferation of bovine CECs.The result suggests that 10.0% aqueous humor can be used as a promoting agent during the culture of CECs.%背景 组织工程角膜内皮层的构建需要有活性的角膜内皮细胞(CECs),因此如何在体外培养出大量有生理功能的角膜内皮种子细胞是迫切需要解决的问题. 目的 观察房水对体外培养的牛CECs生长的影响. 方法 从新鲜牛眼球前房抽取1.2 ml房水,经消毒过滤后取上清备用.从牛眼角膜组织分离牛CECs并用含质量分数10%胎牛血清的低糖DMEM培养液进行培养传代.分别在培养液中加入不同体积的房水,使房水终体积分数分别为2.5%、5.0%、10.0%、15.0%、20.0%,对照组不加房水,利用细胞计数试剂盒-8(CCK-8)比色法检测各组细胞在450 nm处的吸光度(A450)值.流式细胞仪分析10.0%房水培养对CECs细胞周期的影响.待培养细胞融合成单层后,1 ml塑料枪头尖端在培养皿底划痕并用含10%胎牛血清的DMEM培养液中加入10.0%房水培养24 h,未加入房水的培养液作为对照组,检测细胞单层的愈合情况.将细胞以6×105个/ml密度接种到培养皿中,分别用含10.0%房水的培养液和无房水的培养液孵育5d,利用DAPI荧光染色技术分析细胞密度. 结果 培养的CECs呈六角形、铺路石样的扁平状.CCK-8比色法检测表明,各培养组细胞的A450值总体比

  15. Kinetics and equilibrium studies on biosorption of cadmium, lead, and nickel ions from aqueous solutions by intact and chemically modified brown algae

    International Nuclear Information System (INIS)

    Research highlights: → The present study deals with the evaluation of biosorptive removal of Cd (II), Ni (II) and Pb (II) ions by both intact and pre-treated brown marine algae: Cystoseira indica, Sargassum glaucescens, Nizimuddinia zanardini and Padina australis treated with formaldehyde (FA), glutaraldehyde (GA), polyethylene imine (PEI), calcium chloride (CaCl2) and hydrochloric acid (HCl). From the results obtained, chemically modification leads to higher capacity of biosorption. → The equilibrium experimental data were tested using the most common isotherms. The results are best fitted by the Freundlich model among two-parameter models and the Toth, Khan and Radke-Prausnitz models among three-parameter isotherm models for Cd (II), Ni (II) and Pb (II), respectively. → One-way ANOVA and one sample t-tests were performed on experimental data to evaluate the statistical significance of biosorption capacities after five cycles of sorption and desorption. → The kinetic data were fitted by models including pseudo-first-order and pseudo-second-order. From the results obtained, the pseudo-second-order kinetic model describes best the biosorption of cadmium, nickel and lead ions. - Abstract: The present study deals with the evaluation of biosorptive removal of Cd (II), Ni (II) and Pb (II) ions by both intact and pre-treated brown marine algae: Cystoseira indica, Sargassum glaucescens, Nizimuddinia zanardini and Padina australis treated with formaldehyde (FA), glutaraldehyde (GA), polyethylene imine (PEI), calcium chloride (CaCl2) and hydrochloric acid (HCl). Batch shaking adsorption experiments were performed in order to examine the effects of pH, contact time, biomass concentration, biomass treatment and initial metal concentration on the removal process. The optimum sorption conditions for each heavy metal are presented. One-way ANOVA and one sample t-tests were performed on experimental data to evaluate the statistical significance of biosorption capacities

  16. Development of Prediction Models for the Reactivity of Organic Compounds with Ozone in Aqueous Solution by Quantum Chemical Calculations: The Role of Delocalized and Localized Molecular Orbitals.

    Science.gov (United States)

    Lee, Minju; Zimmermann-Steffens, Saskia G; Arey, J Samuel; Fenner, Kathrin; von Gunten, Urs

    2015-08-18

    Second-order rate constants (kO3) for the reaction of ozone with micropollutants are essential parameters for the assessment of micropollutant elimination efficiency during ozonation in water and wastewater treatment. Prediction models for kO3 were developed for aromatic compounds, olefins, and amines by quantum chemical molecular orbital calculations employing ab initio Hartree-Fock (HF) and density functional theory (B3LYP) methods. The kO3 values for aromatic compounds correlated well with the energy of a delocalized molecular orbital first appearing on an aromatic ring (i.e., the highest occupied molecular orbital (HOMO) or HOMO-n (n ≥ 0) when the HOMO is not located on the aromatic ring); the number of compounds tested (N) was 112, and the correlation coefficient (R(2)) values were 0.82-1.00. The kO3 values for olefins and amines correlated well with the energy of a localized molecular orbital (i.e., the natural bond orbital (NBO)) energy of the carbon-carbon π bond of olefins (N = 45, R(2) values of 0.82-0.85) and the NBO energy of the nitrogen lone-pair electrons of amines (N = 59, R(2) values of 0.81-0.83), respectively. Considering the performance of the kO3 prediction model and the computational costs, the HF/6-31G method is recommended for all aromatic groups and olefins investigated herein, whereas the HF/MIDI!, HF/6-31G*, or HF/6-311++G** methods are recommended for amines. Based on their mean absolute errors, the above models could predict kO3 within a factor of 4, on average, relative to the experimentally determined values. Overall, good correlations were also observed (R(2) values of 0.77-0.96) between kO3 predictions by quantum molecular orbital descriptors in this study and by the Hammett (σ) and Taft (σ*) constants from previously developed quantitative structure-activity relationship (QSAR) models. Hence, the quantum molecular orbital descriptors are an alternative to σ and σ*-values in QSAR applications and can also be utilized to

  17. Kinetics and equilibrium studies on biosorption of cadmium, lead, and nickel ions from aqueous solutions by intact and chemically modified brown algae

    Energy Technology Data Exchange (ETDEWEB)

    Montazer-Rahmati, Mohammad Mehdi, E-mail: mrahmati@ut.ac.ir [School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box: 11155-4563, Tehran 4563 (Iran, Islamic Republic of); Rabbani, Parisa; Abdolali, Atefeh [School of Chemical Engineering, College of Engineering, University of Tehran, P.O. Box: 11155-4563, Tehran 4563 (Iran, Islamic Republic of); Keshtkar, Ali Reza [Nuclear Science and Technology Research Institute, Atomic Energy Organization of Iran, P.O. Box: 11365-8486, Tehran (Iran, Islamic Republic of)

    2011-01-15

    Research highlights: {yields} The present study deals with the evaluation of biosorptive removal of Cd (II), Ni (II) and Pb (II) ions by both intact and pre-treated brown marine algae: Cystoseira indica, Sargassum glaucescens, Nizimuddinia zanardini and Padina australis treated with formaldehyde (FA), glutaraldehyde (GA), polyethylene imine (PEI), calcium chloride (CaCl{sub 2}) and hydrochloric acid (HCl). From the results obtained, chemically modification leads to higher capacity of biosorption. {yields} The equilibrium experimental data were tested using the most common isotherms. The results are best fitted by the Freundlich model among two-parameter models and the Toth, Khan and Radke-Prausnitz models among three-parameter isotherm models for Cd (II), Ni (II) and Pb (II), respectively. {yields} One-way ANOVA and one sample t-tests were performed on experimental data to evaluate the statistical significance of biosorption capacities after five cycles of sorption and desorption. {yields} The kinetic data were fitted by models including pseudo-first-order and pseudo-second-order. From the results obtained, the pseudo-second-order kinetic model describes best the biosorption of cadmium, nickel and lead ions. - Abstract: The present study deals with the evaluation of biosorptive removal of Cd (II), Ni (II) and Pb (II) ions by both intact and pre-treated brown marine algae: Cystoseira indica, Sargassum glaucescens, Nizimuddinia zanardini and Padina australis treated with formaldehyde (FA), glutaraldehyde (GA), polyethylene imine (PEI), calcium chloride (CaCl{sub 2}) and hydrochloric acid (HCl). Batch shaking adsorption experiments were performed in order to examine the effects of pH, contact time, biomass concentration, biomass treatment and initial metal concentration on the removal process. The optimum sorption conditions for each heavy metal are presented. One-way ANOVA and one sample t-tests were performed on experimental data to evaluate the statistical

  18. Development of chemical dosimeters

    International Nuclear Information System (INIS)

    A chemical dosimeter is a system that measures the energy by virtue of chemical changes from ionizing absorbed radiation produced unit when it is exposed to ionizing radiation. In all chemical dosimeters radiation induced chemical reaction produces at least one, initially absent species, which is properties long lived enough to determine its quantity or the change in the initial systems. Different types of chemical dosimeters were discussed such as aqueous, gaseous and solid, but the great consideration was given to aqueous systems because of their vital role in setting many processes.(Author)

  19. Effects of soil water conditions and organic and chemical fertilizers on growth characteristics and water use efficiency of rice in an alkaline non-calcareous soil

    Directory of Open Access Journals (Sweden)

    M. Abbasi

    2012-12-01

    Full Text Available In a greenhouse research, the effects of soil water conditions, sewage sludge and chemical fertilizers on growth characteristics and water use efficiency of rice (Oryza sativa L. cv. Ali Kazemi were studied in a loamy sand alkaline non-calcareous soil. The study was performed as a factorial experiment in a randomized complete blocks design including soil water conditions in three levels (continuous submergence, alternate submergence and alternate saturation and source and amount of organic and chemical fertilizers in 10 levels [control, 100% chemical fertilizers (434.8 mg urea, 66.1 mg KH2PO4, 40 mg KCl, 50 mg FeSO4.7H2O, 38.5 mg FeSO4.7H2O, 21.3 mg ZnSO4.7H2O and 7.9 mg CuSO4.5H2O per kg of soil, 20 g sewage sludge per kg of soil with and without 50% of chemical fertilizers, 40 g sewage sludge per kg of soil with and without 50% of chemical fertilizers, 20 g poultry manure per kg of soil with and without 50% of chemical fertilizers and 40 g poultry manure per kg of soil with and without 50% of chemical fertilizers] with three replications. At the end of growth period, tiller and leaf number per plant, length and diameter of stem, length and volume of roots, and shoot and root dry matter were measured and water use efficiency (WUE was calculated. The results showed that application of 20 and 40 g poultry manure per kg of soil prevented the growth of rice due to increase of soil salinity. Application of 20 and 40 g sewage sludge per kg of soil increased significantly tiller and leaf number per plant, length and diameter of stem, length and volume of roots, shoot and root dry matter and WUE compared to control and 100% chemical fertilizers treatments. Addition of 50% chemical fertilizers to 40 g sewage sludge per kg of soil did not significantly affect tiller and leaf number per plant, stem length, volume of roots, shoot dry matter and WUE of rice. The highest tiller number per plant, stem diameter, root length and the ratio of shoot dry matter to

  20. Synthesis of human pancreatic growth hormone-releasing factor and two omission analogs by segment-coupling method in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Blake, J.; Westphal, M.; Li, C.H. (Laboratory of Molecular Endocrinology, University of California, San Francisco, USA)

    1984-01-01

    The human growth hormone-releasing factor (GRF) peptides (GlyS/sup 15/)-GRF-(1-15) (IV), trifluoroacetyl-GRF-(20-44) (VI), trifluoroacetyl-GRF-(18-44) (VIII), and trifluoroacetyl-GRF-(16-44) (X) were synthesized by the solidphase method. Each of the peptides was reacted with citraconic anhydride and the trifluoroacetyl group was removed by reaction with 10% hydrazine in water. The citraconylated GRF-(1-15) peptide was coupled to the (20-44), (18-44) or (16-44) peptides by reaction with silver nitrate/N-hydroxysuccinimide to give GRF-(1-15)-(20-44) (XII), GRF-(1-15)-(18-44) (XIII), or GRF-(1-44), respectively. GRF-(1-44) was shown to stimulate the release of rat growth hormone from rat pituitary cells with an ED/sub 50/=8.8 x 10/sup -11/M. Peptides XII and XIII were inactive, either as agonists or as antagonists of the action of GRF-(1-44).

  1. Synthesis of human pancreatic growth hormone-releasing factor and two omission analogs by segment-coupling method in aqueous solution

    International Nuclear Information System (INIS)

    The human growth hormone-releasing factor (GRF) peptides [GlyS15]-GRF-(1-15) (IV), trifluoroacetyl-GRF-(20-44) (VI), trifluoroacetyl-GRF-(18-44) (VIII), and trifluoroacetyl-GRF-(16-44) (X) were synthesized by the solidphase method. Each of the peptides was reacted with citraconic anhydride and the trifluoroacetyl group was removed by reaction with 10% hydrazine in water. The citraconylated GRF-(1-15) peptide was coupled to the (20-44), (18-44) or (16-44) peptides by reaction with silver nitrate/N-hydroxysuccinimide to give GRF-(1-15)-(20-44) (XII), GRF-(1-15)-(18-44) (XIII), or GRF-(1-44), respectively. GRF-(1-44) was shown to stimulate the release of rat growth hormone from rat pituitary cells with an ED50=8.8 x 10-11M. Peptides XII and XIII were inactive, either as agonists or as antagonists of the action of GRF-(1-44). (author)

  2. An analysis of the growth of silver catalyzed InxGa1-xAs nanowires on Si (100) by metal organic chemical vapor deposition

    Science.gov (United States)

    Sarkar, K.; Palit, M.; Chattopadhyay, S.; Banerji, P.

    2016-08-01

    A model is proposed here to understand the nucleation of III-V semiconductor nanowires (NW). Whereas the classical nucleation theory is not adequately sufficient in explaining the evolution of the shape of the NWs under different chemical environment such as flow rate or partial pressure of the precursors, the effect of adsorption and desorption mediated growth, and diffusion limited growth are taken into account to explain the morphology and the crystal structure of InxGa1-xAs nanowires (NW) on Silicon (100) substrates grown by a metalorganic chemical vapor deposition technique. It is found that the monolayer nucleus that originates at the triple phase line covers the entire nucleus-substrate (NS) region at a specific level of supersaturation and there are cases when the monolayer covers a certain fraction of the NS interface. When the monolayer covers the total NS interface, NWs grow with perfect cylindrical morphology and whenever a fraction of the interface is covered by the nucleus, the NWs become curved as observed from high resolution transmission electron microscopy images. The supersaturation, i.e., the chemical potential is found to be governed by the concentration of precursors into the molten silver which in the present case is taken as a catalyst. Our study provides new insights into the growth of ternary NWs which will be helpful in understanding the behavior of growth of different semiconducting NWs.

  3. The effects of dietary administration with chemical treated Saccharomyces cerevisiae strain YG3-1 on the growth of aquatic invertebrates in Artemia

    Directory of Open Access Journals (Sweden)

    Behnam Shekarchi

    2016-02-01

    Full Text Available Objective: To investigate the biological effects of β-glucans in cell wall of new identified strain Saccharomyces cerevisiae strain YG3-1 on the growth of aquatic invertebrates, in Artemia as model organism. Methods: All yeasts used in the present study were isolated from Rainbow trout intestine and then cultured in yeast extract-peptone-glycerol medium. Activation of β-glucan in yeasts was performed by chemical treatment with 2-mercaptoethanol (2ME (3.5% v/v. Then nauplii and larvae individuals of Artemia urmiana and Artemia franciscana (two different species of Artemia as test organisms were fed with 2ME-treated yeasts during the culture. At the end of experiment, after feeding individual length (total length and growth rate in adult individuals of Artemia was measured. Results: Following this administration, growth in both species of Artemia was improved (P < 0.05. So, the results showed that Artemia urmiana adults individuals that fed with 2MEtreated yeasts had the highest growth and total length. These results were confirmed with growth measurement in adult individuals of Artemia. Conclusions: This study suggested that 2ME-treated Saccharomyces cerevisiae strain YG3-1 yeasts can be used for enhancing the growth of other aquatic invertebrates like shrimps as probiotic supplement and growth promoter.

  4. Analysis of the surface photoabsorption signal during self-limited submonolayer growth of InP in metalorganic chemical vapor deposition

    CERN Document Server

    Lee, T W; Moon, Y B; Yoon, E J; Kim, Y D

    1999-01-01

    In situ, real-time monitoring of InP atomic layer epitaxy (ALE) was performed in low-pressure metalorganic chemical vapor deposition (LP-MOCVD) by surface photoabsorption (SPA). A self-limiting adsorption condition was obtained from the trimethylindium (TMIn) decomposition experiment at various conditions. It was found that the growth rate was less than 1 monolayer (ML)/cycle. From the in situ, real-time SPA measurement during InP ALE, the incomplete PH sub 3 decomposition on the methyl-terminated In surface was attributed to the self-limiting submonolayer growth per cycle.

  5. Reliable Growth of Vertically Aligned Carbon Nanotube Arrays by Chemical Vapor Deposition and In-situ Measurement of Fundamental Growth Kinetics in Oxygen-free Conditions

    OpenAIRE

    IN, JUNG BIN

    2011-01-01

    Vertically-aligned carbon nanotube (VACNT) arrays are both an important technological system, and a fascinating system for studying basic principles of nanomaterial synthesis. However, despite continuing efforts for the past decade, important questions about this process remain largely unexplained. Recently, nanotube research investigations have been conducted, aiming at revealing the underlying growth mechanisms, rather than merely studying the feasibility on new growth methods. Nonetheless,...

  6. Influence of ZnO seed layer precursor molar ratio on the density of interface defects in low temperature aqueous chemically synthesized ZnO nanorods/GaN light-emitting diodes

    Science.gov (United States)

    Alnoor, Hatim; Pozina, Galia; Khranovskyy, Volodymyr; Liu, Xianjie; Iandolo, Donata; Willander, Magnus; Nur, Omer

    2016-04-01

    Low temperature aqueous chemical synthesis (LT-ACS) of zinc oxide (ZnO) nanorods (NRs) has been attracting considerable research interest due to its great potential in the development of light-emitting diodes (LEDs). The influence of the molar ratio of the zinc acetate (ZnAc): KOH as a ZnO seed layer precursor on the density of interface defects and hence the presence of non-radiative recombination centers in LT-ACS of ZnO NRs/GaN LEDs has been systematically investigated. The material quality of the as-prepared seed layer as quantitatively deduced by the X-ray photoelectron spectroscopy is found to be influenced by the molar ratio. It is revealed by spatially resolved cathodoluminescence that the seed layer molar ratio plays a significant role in the formation and the density of defects at the n-ZnO NRs/p-GaN heterostructure interface. Consequently, LED devices processed using ZnO NRs synthesized with molar ratio of 1:5 M exhibit stronger yellow emission (˜575 nm) compared to those based on 1:1 and 1:3 M ratios as measured by the electroluminescence. Furthermore, seed layer molar ratio shows a quantitative dependence of the non-radiative defect densities as deduced from light-output current characteristics analysis. These results have implications on the development of high-efficiency ZnO-based LEDs and may also be helpful in understanding the effects of the ZnO seed layer on defect-related non-radiative recombination.

  7. The influence of H2O2 concentration to the structure of silicon nanowire growth by metal-assisted chemical etching

    Science.gov (United States)

    Omar, Hafsa; Jani, Abdul Mutalib Md.; Rusop, Mohamad; Abdullah, Saifollah

    2016-07-01

    A simple and low cost method to produce well aligned silicon nanowires at large areas using Ag-assisted chemical etching at room temperature were presented. The structure of silicon nanowires growth by metal-assisted chemical etching was observed. Prior to the etching, the silicon nanowires were prepared by electroless metal deposited (EMD) in solution containing hydrofluoric acid and hydrogen peroxide in Teflon vessel. The silver particle was deposited on substrate by immersion in hydrofluoric acid and silver nitrate solution for sixty second. The silicon nanowires were growth in different hydrogen peroxide concentration which are 0.3M, 0.4M, 0.5M and 0.6M and 0.7M.The influence of hydrogen peroxide concentration to the formation of silicon nanowires was studied. The morphological properties of silicon nanowires were investigated using field emission scanning electron microscopy (FESEM) and Energy Dispersive X-Ray Spectroscopy (EDS).

  8. Growth, carcass characteristics, chemical composition and fatty acid profile of the longissimus dorsi muscle in goat kids fed diets with castor oil

    OpenAIRE

    Michelle de Oliveira Maia; Ivanete Susin; Alexandre Vaz Pires; Renato Shinkai Gentil; Evandro Maia Ferreira; Clayton Quirino Mendes; Severino Matias de Alencar

    2012-01-01

    The objective in this study was to determine growth, carcass characteristics, chemical composition and fatty acid profile of the longissimus dorsi of crossbred Boer × Saanen kids fed castor oil. Twenty-four kids (12 males and 12 females) were assigned in a randomized complete block design with two treatments and twelve replications. Blocks were defined according to weight, gender and initial age of animals for the evaluation of performance. The experimental treatments consisted of two diets c...

  9. Efeito de extratos aquosos de estruturas de grama-seda no desenvolvimento inicial de plântulas de arroz, milho e trigo Effects of aqueous extracts of bermudagrass structures on initial growth of rice, corn and wheat seedlings

    Directory of Open Access Journals (Sweden)

    Maria do Carmo de Salvo Soares Novo

    2009-09-01

    Full Text Available Objetivou-se verificar os efeitos de extratos aquosos de estruturas de grama-seda (Cynodon dactylon (L. Pers e de exsudatos radiculares presentes no solo no qual a planta se desenvolveu, sobre a germinação e o crescimento inicial de arroz, trigo e milho. O extrato aquoso das estruturas da parte aérea, subterrâneas e da planta inteira, assim como do estolão, da folha + colmo, estolão + folha + colmo, rizoma, raiz e de rizoma + raiz de grama-seda foi elaborado a partir de 100 g L-1 de material seco. Foram avaliados a protrusão da radícula e os crescimentos da radícula e da plúmula de cada espécie. A inibição ou o estímulo do desenvolvimento inicial de plântulas foi dependente da espécie avaliada e da estrutura vegetal empregada na elaboração do extrato. A protrusão da radícula foi mais inibida que os crescimentos da radícula e da plúmula. O estímulo do desenvolvimento da radícula e da plúmula foi mais evidente quando o extrato foi elaborado a partir das estruturas do sistema radicular, da parte aérea e da planta inteira que de estruturas individualizadas de grama-seda. De modo geral, o arroz e o milho foram mais inibidos por extratos elaborados a partir da parte aérea e subterrânea, respectivamente. Para o trigo, a inibição ou o estímulo foi dependente da variável analisada. O desenvolvimento da radícula e da plúmula de arroz, milho e trigo foi estimulado por extrato elaborado a partir da planta inteira. O extrato produzido a partir da fração argila + silte estimulou o desenvolvimento da radícula do milho e da plúmula do trigo.The objective of this work was to study the effects of aqueous extracts of Bermudagrass structures (Cynodon dactylon (L. Pers and soil exudates, on the germination and initial growth of rice, corn and wheat seedlings. The aqueous extracts of above-ground and subterranean parts and of the whole plant, as well as of stolons, leaves + culm, stolons + leaves + culm, rhizome, root and rhizome

  10. Efeito do extrato aquoso de leucena na germinação e no desenvolvimento do milho Effect of aqueous extract of leucaena on germination and growth of corn

    Directory of Open Access Journals (Sweden)

    HÉLIO TEIXEIRA PRATES

    2000-05-01

    Full Text Available Foram desenvolvidos bioensaios, na Embrapa-Centro Nacional de Pesquisa de Milho e Sorgo (CNPMS, para avaliar o efeito de extratos aquosos, a frio e a quente, da parte aérea de leucena (Leucaena leucocephala (Lam. De Wit., sobre a germinação e o desenvolvimento das plantas de milho (Zea mays L.. Os extratos foram preparados na concentração 20% (p/v, e avaliados em solo e papel- germiteste, em casa de vegetação, e em papel-filtro em laboratório. O extrato obtido com água fria (EF e aplicado ao solo não causou nenhum efeito fitotóxico sobre a germinação e o desenvolvimento das plantas de milho. O extrato obtido com água quente (EQ, quando aplicado em papel-germiteste ou papel-filtro, causou redução no comprimento da raiz seminal, mas não interferiu na germinação das sementes de milho. O comprimento da raiz seminal foi um indicador mais sensível aos efeitos do EQ do que a germinação.Bioassays were carried out at Embrapa-Centro Nacional de Pesquisa de Milho e Sorgo (CNPMS, to evaluate the effect of leucaena (Leucaena leucocephala (Lam. De Wit. cold and hot aqueous extracts on germination and growth of corn (Zea mays L.. Extracts at 20% (w/v concentration were used in greenhouse on soil and germitest paper, and on filter paper under laboratory conditions. Results indicated that extract obtained with cold water (EC when applied in soil had no phytotoxic effect on germination and plant growth. Extraction with hot water (EH caused reduction in root length, but had no effect on maize seeds germination. The root length was more efficient as a sensitive indicator to EH than germination.

  11. Aspergillus parasiticus growth and aflatoxin production on black and white pepper and the inhibitory action of their chemical constituents.

    OpenAIRE

    Madhyastha, M S; Bhat, R V

    1984-01-01

    Aspergillus parasiticus Speare NRRL 2999 growth and aflatoxin production in black and white pepper and the penetration of the fungus in black pepper corn over various incubation periods were studied. Also, the effects of piperine and pepper oil on growth and aflatoxin production were studied. Under laboratory conditions, black and white pepper supported aflatoxin production (62.5 and 44 ppb (ng/g), respectively) over 30 days of incubation. Fungal growth measured in terms of chitin was conside...

  12. A green heterogeneous synthesis of N-doped carbon dots and their photoluminescence applications in solid and aqueous states

    Science.gov (United States)

    Xu, Minghan; He, Guili; Li, Zhaohui; He, Fengjiao; Gao, Feng; Su, Yanjie; Zhang, Liying; Yang, Zhi; Zhang, Yafei

    2014-08-01

    Compared with traditional semiconductor quantum dots (QDs) and organic dyes, photoluminescent carbon dots (CDs) are superior because of their high aqueous solubility, robust chemical inertness, facile functionalization, high resistance to photobleaching, low toxicity and good biocompatibility. Herein, a green, large-scale and high-output heterogeneous synthesis of N-doped CDs was developed by reacting calcium citrate and urea under microwave irradiation without the use of any capping agents. The obtained N-doped CDs with a uniform size distribution exhibit good aqueous solubility and yellowish-green fluorescence in the solid and aqueous states. These unique luminescence properties of N-doped CDs inspire new thoughts for applications as fluorescent powders, fluorescent inks, the growth of fluorescent bean sprouts, and fingerprint detection tools.Compared with traditional semiconductor quantum dots (QDs) and organic dyes, photoluminescent carbon dots (CDs) are superior because of their high aqueous solubility, robust chemical inertness, facile functionalization, high resistance to photobleaching, low toxicity and good biocompatibility. Herein, a green, large-scale and high-output heterogeneous synthesis of N-doped CDs was developed by reacting calcium citrate and urea under microwave irradiation without the use of any capping agents. The obtained N-doped CDs with a uniform size distribution exhibit good aqueous solubility and yellowish-green fluorescence in the solid and aqueous states. These unique luminescence properties of N-doped CDs inspire new thoughts for applications as fluorescent powders, fluorescent inks, the growth of fluorescent bean sprouts, and fingerprint detection tools. Electronic supplementary information (ESI) available: The photos of different precursors under daylight and 365 nm UV beam; 1H-NMR and Raman spectrum of N-doped CDs; toxicity study of bean sprouts; the correlation between length of bean sprouts and the concentration of N-doped CDs

  13. Effects of growth temperature on the properties of InGaN channel heterostructures grown by pulsed metal organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yachao; Zhou, Xiaowei; Xu, Shengrui; Wang, Zhizhe; Chen, Zhibin; Zhang, Jinfeng; Zhang, Jincheng, E-mail: jchzhang@xidian.edu.cn, E-mail: xd-zhangyachao@163.com; Hao, Yue, E-mail: jchzhang@xidian.edu.cn, E-mail: xd-zhangyachao@163.com [School of Microelectronics, Xidian University, No.2 South TaiBai Road, Xi’an, China 710071 (China); Key Laboratory of Wide Band Gap Semiconductor Materials and Devices (China)

    2015-12-15

    Pulsed metal organic chemical vapor deposition (P-MOCVD) is introduced into the growth of high quality InGaN channel heterostructures. The effects of InGaN channel growth temperature on the structural and transport properties of the heterostructures are investigated in detail. High resolution x-ray diffraction (HRXRD) and Photoluminescence (PL) spectra indicate that the quality of InGaN channel strongly depends on the growth temperature. Meanwhile, the atomic force microscopy (AFM) results show that the interface morphology between the InGaN channel and the barrier layer also relies on the growth temperature. Since the variation of material properties of InGaN channel has a significant influence on the electrical properties of InAlN/InGaN heterostructures, the optimal transport properties can be achieved by adjusting the growth temperature. A very high two dimension electron gas (2DEG) density of 1.92 × 10{sup 13} cm{sup −2} and Hall electron mobility of 1025 cm{sup 2}/(V⋅s) at room temperature are obtained at the optimal growth temperature around 740 °C. The excellent transport properties in our work indicate that the heterostructure with InGaN channel is a promising candidate for the microwave power devices, and the results in this paper will be instructive for further study of the InGaN channel heterostructures.

  14. Particle hygroscopicity during atmospheric new particle formation events: implications for the chemical species contributing to particle growth

    Directory of Open Access Journals (Sweden)

    Z. Wu

    2013-07-01

    Full Text Available This study examines the hygroscopicity of newly formed particles (diameters range 25–45 nm during two atmospheric new particle formation (NPF events in the German mid-level mountains during the Hill Cap Cloud Thuringia 2010 (HCCT-2010 field experiment. At the end of the NPF event involving clear particle growth, we measured an unusually high soluble particle fraction of 58.5% at 45 nm particle size. The particle growth rate contributed through sulfuric acid condensation only accounts for around 6.5% of the observed growth rate. Estimations showed that sulfuric acid condensation explained, however, only around 10% of that soluble particle fraction. Therefore, the formation of additional water-soluble matter appears imperative to explain the missing soluble fraction. Although direct evidence is missing, we consider water-soluble organics as candidates for this mechanism. For the case with clear growth process, the particle growth rate was determined by two alternative methods based on tracking the mode diameter of the nucleation mode. The mean particle growth rate obtained from the inter-site data comparison using Lagrangian consideration is 3.8 (± 2.6 nm h−1. During the same period, the growth rate calculated based on one site data is 5.0 nm h−1 using log-normal distribution function method. In light of the fact that considerable uncertainties could be involved in both methods, we consider both estimated growth rates consistent.

  15. Cyclopiazonic acid degradation by aqueous ozone

    OpenAIRE

    Silva, Otniel Freitas; Venâncio, Armando

    2011-01-01

    Ozone is a chemical agent with great potential to reduce mycotoxins, it was effective against to reduce some mycotoxins. In view of this it was aimed of this work study the Cyclopiazonic acid (CPA) degradation by aqueous ozone. The degradation of exogenously CPA introduced in mobile phase was confirmed by High performance liquid Chromatography (HPLC). In parallel it was tested the effect of sodium formate (SF), to evaluate the influence of this chemical to neutralize ...

  16. FORMATION OF POLYCYCLIC AROMATIC HYDROCARBONS AND THEIR GROWTH TO SOOT -A REVIEW OF CHEMICAL REACTION PATHWAYS. (R824970)

    Science.gov (United States)

    The generation by combustion processes of airborne species of current health concern such as polycyclic aromatic hydrocarbons (PAH) and soot particles necessitates a detailed understanding of chemical reaction pathways responsible for their formation. The present review discus...

  17. Chemical Peels

    Science.gov (United States)

    ... resources Meet our partners Español Donate Diseases and treatments Acne and rosacea Bumps and growths Color problems Contagious skin diseases ... Chemical peels public SPOT Skin Cancer™ Diseases and treatments Acne and rosacea Bumps and growths Color problems Contagious skin diseases ...

  18. The effects of dietary administration with chemical treated Saccharomyces cerevisiae strain YG3-1 on the growth of aquatic invertebrates in Artemia

    Institute of Scientific and Technical Information of China (English)

    Behnam Shekarchi; Ali Nekuiefard; Ramin Manaffar

    2016-01-01

    Objective: To investigate the biological effects of β-glucans in cell wall of new identified strain Saccharomyces cerevisiae strain YG3-1 on the growth of aquatic invertebrates, in Artemia as model organism. Methods: All yeasts used in the present study were isolated from Rainbow trout intestine and then cultured in yeast extract-peptone-glycerol medium. Activation of β-glucan in yeasts was performed by chemical treatment with 2-mercaptoethanol (2ME) (3.5% v/v). Then nauplii and larvae individuals of Artemia urmiana and Artemia franciscana (two different species of Artemia as test organisms) were fed with 2ME-treated yeasts during the culture. At the end of experiment, after feeding individual length (total length and growth rate) in adult individuals of Artemia was measured. Results: Following this administration, growth in both species of Artemia was improved (P Conclusions: This study suggested that 2ME-treated Saccharomyces cerevisiae strain YG3-1 yeasts can be used for enhancing the growth of other aquatic invertebrates like shrimps as probiotic supplement and growth promoter.

  19. EFFECT OF DIETARY LEVELS OF LIPID AND CARBOHYDRATE ON GROWTH PERFORMANCE, CHEMICAL CONTENTS AND DIGESTIBILITY IN RAINBOW TROUT, ONCORHYNCHUS MYKISS WALBAUM, 1792

    Directory of Open Access Journals (Sweden)

    E. GÜMÜŞ AND R. İKİZ

    2009-05-01

    Full Text Available The present study was carried out to determine the effects of four rations on growth, chemical composition and digestibility of the Rainbow trout (Oncorhynchus mykiss Walbaum, 1792. Four test diets were formulated to have the same levels of protein (40% and energy (gross energy: around 4800 cal/g, however, these test diets were composed of basic diet with different carbohydrate (0, 3, 12 and 18% to lipid (0, 6, 15 and 18% ratios (Diet 1: 0/18; Diet 2: 3/15; Diet 3: 12/6 and Diet 4: 18/0. Fifty fish weighing 99.0 ± 0.65g were placed in each of the four experimental tanks and were fed with one of the experimental diets for 13 weeks consisting of two trial periods (Periods I and II. Growth parameters and chemical composition of fish flesh were monitored. Effects of the diets on apparent digestibility coefficients (ADC were also determined. At the end of the study, the fish growth was affected significantly (P0.05 changes in specific growth rate, although higher values were observed in fish fed with Diets 1 and 3. The experimental group fed with Diet 4 showed a lower (P0.05 changes in experimental groups fed with the diets. The percentage of water, protein and ash of fish flesh did not show any (P>0.05 change. However, the muscle lipid content of fish significantly (P<0.05 decreased as carbohydrate level increased. The ADC values were also affected (P<0.05 with carbohydrate and lipid levels in the diets. The ADC of lipid was lowest in the experimental group fed with Diet 1. The ADC values for dry matter, proteins and energy were lowest for fish fed on Diet 4, while for ash it was lowest for Diet 2. These results indicate that the best balance between the dietary lipid and carbohydrate levels was obtained on Diet 3, without lower growth.

  20. Aqueous Synthesis of Ru Doped Hematite Nanostructures: A Morphological, Structural, Optical, and Magnetic Study

    Directory of Open Access Journals (Sweden)

    Ceboliyozakha Leonard Ndlangamandla

    2015-01-01

    Full Text Available Hematite nanorods doped with ruthenium were successfully deposited on fluorine doped tin oxide (FTO glass substrates using aqueous chemical growth. Using complementary surface/interface investigation techniques, the Ru incorporation in the Ru-α-Fe2O3 nanorods was evidenced. The optical band gap was found to be Ru doping concentration dependent: varying from 2.32 (2 to 2.47 (2 eV. These band gap values are well suited for the targeted water splitting process without application of an external bias.

  1. Aqueous Extract of Gumiganghwal-tang, a Traditional Herbal Medicine, Reduces Pulmonary Fibrosis by Transforming Growth Factor-β1/Smad Signaling Pathway in Murine Model of Chronic Asthma

    Science.gov (United States)

    Shin, In-Sik; Shin, Hyeun-Kyoo; Jin, Seong Eun; Lee, Mee-Young

    2016-01-01

    Gumiganghwal-tang is a traditional herbal prescription that is used widely for the treatment of the common cold and inflammatory diseases in Korea and other Asian countries. In this study, we investigated the protective effects of a Gumiganghwal-tang aqueous extract (GGTA) against airway inflammation and pulmonary fibrosis using a mouse model of chronic asthma. Chronic asthma was modeled in BALB/c mice via sensitization/challenge with an intraperitoneal injection of 1% ovalbumin (OVA) and inhalation of nebulized 1% OVA for 4 weeks. GGTA (100 mg/kg or 200 mg/kg) was also administered by oral gavage once a day for 4 weeks. We investigated the number of inflammatory cells, production of T-helper type 2 (Th2) cytokines, chemokine and the total transforming growth factor-β1 (TGF-β1) in bronchoalveolar lavage fluid (BALF); the levels of immunoglobulin E (IgE) in the plasma; the infiltration of inflammatory cells in lung tissue; and the expression of TGF-β1, Smad-3, and collagen in lung tissue. Our results revealed that GGTA lowered the recruitment of inflammatory cells (particularly, lymphocyte); and decreased the production of Th2 cytokines, chemokine and total TGF-β1; and attenuated the levels of total and OVA-specific IgE; and decreased the infiltration of inflammatory cells. Moreover, GGTA significantly reduced the expression of TGF-β1 and Smad-3, and lowered collagen deposition. These results indicate that GGTA reduces airway inflammation and pulmonary fibrosis by regulating Th2 cytokines production and the TGF-β1/Smad-3 pathway, thus providing a potential treatment for chronic asthma. PMID:27741312

  2. Controlled growth of epitaxial CeO2 thin films with self-organized nanostructure by chemical solution method

    DEFF Research Database (Denmark)

    Yue, Zhao; Grivel, Jean-Claude

    2013-01-01

    Chemical solution deposition is a versatile technique to grow oxide thin films with self-organized nanostructures. Morphology and crystallographic orientation control of CeO2 thin films grown on technical NiW substrates by a chemical solution deposition method are achieved in this work. Based...... a fluorite structure but exhibits an alternative in-plane texture with eight fold symmetry on the surface. According to phase and texture stability studies, these off-stoichiometric phases gradually transform back to fully oxidized CeO2 with a 45° rotated cube texture during storage in ambient air. Moreover...

  3. Hemp raw materials: The effect of cultivar, growth conditions and pretreatment on the chemical composition of the fibres

    OpenAIRE

    Thomsen, A.B.; Rasmussen, S.K.; Bohn, V.; Nielsen, K.V.; Thygesen, A.

    2005-01-01

    Hemp raw materials were analyzed chemically to determine their content of cellulose, hemicellulose, lignin and ashes. Correction for ashes was only necessary in the first step of the chemical analysis: the Neutral Detergent Fibre step. The hemp fiberscontained 73-77% w/w cellulose, 7-9% w/w hemicellulose and 4-6% w/w lignin, while the hemp shives contained 48% w/w cellulose, 21-25% w/w hemicellulose and 17-19% w/w lignin. Among the four investigated cultivars, Felina contained least lignin, w...

  4. Aqueous foam toxicology evaluation and hazard review

    Energy Technology Data Exchange (ETDEWEB)

    Archuleta, M.M.

    1995-10-01

    Aqueous foams are aggregates of bubbles mechanically generated by passing air or other gases through a net, screen, or other porous medium that is wetted by an aqueous solution of surface-active foaming agents (surfactants). Aqueous foams are important in modem fire-fighting technology, as well as for military uses for area denial and riot or crowd control. An aqueous foam is currently being developed and evaluated by Sandia National Laboratories (SNL) as a Less-Than-Lethal Weapon for the National Institute of Justice (NIJ). The purpose of this study is to evaluate the toxicity of the aqueous foam developed for the NIJ and to determine whether there are any significant adverse health effects associated with completely immersing individuals without protective equipment in the foam. The toxicity of the aqueous foam formulation developed for NIJ is determined by evaluating the toxicity of the individual components of the foam. The foam is made from a 2--5% solution of Steol CA-330 surfactant in water generated at expansion ratios ranging from 500:1 to 1000:1. SteoI CA-330 is a 35% ammonium laureth sulfate in water and is produced by Stepan Chemical Company and containing trace amounts (<0.1%) of 1,4-dioxane. The results of this study indicate that Steol CA-330 is a non-toxic, mildly irritating, surfactant that is used extensively in the cosmetics industry for hair care and bath products. Inhalation or dermal exposure to this material in aqueous foam is not expected to produce significant irritation or systemic toxicity to exposed individuals, even after prolonged exposure. The amount of 1,4-dioxane in the surfactant, and subsequently in the foam, is negligible and therefore, the toxicity associated with dioxane exposure is not significant. In general, immersion in similar aqueous foams has not resulted in acute, immediately life-threatening effects, or chronic, long-term, non-reversible effects following exposure.

  5. 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.

  6. Chickpea (Cicer arietinum L.) physiological, chemical and growth responses to irrigation with saline water

    DEFF Research Database (Denmark)

    Hirich, Abdelaziz; Omari, Halima El; Jacobsen, Sven-Erik;

    2014-01-01

    water salinity has negatively affected growth and biomass accumulation and led to reduced grain yield, water uptake and water productivity. In contrast, proline, soluble sugars, Na+ and Na+: K+ ratio increased with increasing irrigation water salinity. The findings highlighted the role of proline...... was carried out on pot experiments. Differences in water uptake and plant growth; as well as proline, soluble sugar, and Na+ and K+ contents of the plant were quantified. The results showed a negative relationship between increasing water salinity and most of the measured plant growth parameters. Irrigation...... and soluble sugars as osmolytes produced by chickpea to mitigate the effect of salinity stress. The added value of these results is that the crop's responses to salinity are quantified. The obtained values can be used to determine 'threshold values'; should the salinity of the irrigation water go above...

  7. Combinatorial growth of Mg{sub x}Zn{sub 1-x}O epilayers by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lautenschlaeger, Stefan; Sann, Joachim; Klar, Peter J.; Piechotka, M.; Meyer, Bruno K. [Justus-Liebig-University Giessen, I. Physics Institute, Giessen (Germany)

    2009-02-15

    It was our aim to explore the growth of Mg{sub x} Zn{sub 1-x}O epilayers on ZnO substrates using CVD at substrate temperatures around 650 C which is considerably lower than necessary for the MOCVD growth which requires substrate temperatures above 900 C. Metallic precursors (Zn, Mg) were used together with NO{sub 2} as oxygen precursor. The Mg content was determined from the shift of longitudinal optical phonon line as a function of the Mg composition. The properties of the films were investigated by low temperature photoluminescence. Epitaxial Mg{sub x}Zn{sub 1-x}O films with fixed Mg compositions required an individual adjustment of the Mg reservoir temperature. We, therefore, explored the possibility of a combinatorial growth i.e. achieving a Mg gradient within one sample. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Multiple shoot cultures of Atropa belladonna: Effect of physico-chemical factors on growth and alkaloid formation

    International Nuclear Information System (INIS)

    Multiple shoot cultures were established from shoot tip and axillary meristem of the plant Atropa belladonna. The cultures were initially raised on agar medium and subsequently maintained on liquid medium of Murashige and Skoog (1962) supplemented with BA. These cultures were subjected to different doses of -y-irradiation. Recovery from the radiation effects was observed in tissues subjected to 29 Gy during four successive passages. Plant growth regulators influenced the growth and morphogenetic events of the tissues. The precursors of tropane alkaloids marginally increased the alkaloid synthesis during the stationary phase of growth. Shoot cultures, established from different field grown plants varying in alkaloid content, were morphologically similar and did not exhibit the parental characteristics with respect to alkaloid formation

  9. Research on the chemical speciation of actinides

    International Nuclear Information System (INIS)

    A demand for the safe and effective management of spent nuclear fuel and radioactive waste generated from nuclear power plant draws increasing attention with the growth of nuclear power industry. The objective of this project is to establish the basis of research on the actinide chemistry by using advanced laser-based highly sensitive spectroscopic systems. Researches on the chemical speciation of actinides are prerequisite for the development of technologies related to nuclear fuel cycles, especially, such as the safe management of high level radioactive wastes and the chemical examination of irradiated nuclear fuels. For supporting these technologies, laser-based spectroscopies have been performed for the chemical speciation of actinide in an aqueous solutions and the quantitative analysis of actinide isotopes in spent nuclear fuels. In this report, results on the following subjects have been summarized. (1) Development of TRLFS technology for chemical speciation of actinides, (2) Development of LIBD technology for measuring solubility of actinides, (3) Chemical speciation of plutonium complexes by using a LWCC system, (4) Development of LIBS technology for the quantitative analysis of actinides, (5) Development of technology for the chemical speciation of actinides by CE, (6) Evaluation on the chemical reactions between actinides and humic substances, (7) Chemical speciation of actinides adsorbed on metal oxides surfaces, (8) Determination of actinide source terms of spent nuclear fuel

  10. Effects of vegetable oil residue after soil extraction on physical-chemical properties of sandy soil and plant growth.

    Science.gov (United States)

    Gong, Zongqiang; Li, Peijun; Wilke, B M; Alef, Kassem

    2008-01-01

    Vegetable oil has the ability to extract polycyclic aromatic hydrocarbons (PAHs) from contaminated sandy soil for a remediation purpose, with some of the oil remaining in the soil. Although most of the PAHs were removed, the risk of residue oil in the soil was not known. The objective of this study was to evaluate the effects of the vegetable oil residue on higher plant growth and sandy soil properties after soil extraction for a better understanding of the soil remediation. Addition of sunflower oil and column experiment were performed on a PAH contaminated soil and/or a control soil, respectively. Soils were incubated for 90 d, and soil pH was measured during the soil incubation. Higher plant growth bioassays with Avena sativa L. (oat) and Brassica rapa L. (turnip) were performed after the incubation, and then soil organic carbon contents were measured. The results show that both the nutrient amendment and the sunflower oil degradation resulted in the decrease of soil pH. When these two process worked together, their effects were counteracted due to the consumption of the nutrients and oil removal, resulting in different pH profiles. Growth of A. sativa was adversely affected by the sunflower oil, and the nutrient amendments stimulated the A. sativa growth significantly. B. rapa was more sensitive to the sunflower oil than A. sativa. Only 1% sunflower oil addition plus nutrient amendment stimulated B. rapa growth. All the other treatments on B. rapa inhibited its growth significantly. The degradation of the sunflower oil in the soils was proved by the soil organic carbon content.

  11. Effects of vegetable oil residue after soil extraction on physical-chemical properties of sandy soil and plant growth

    Institute of Scientific and Technical Information of China (English)

    GONG Zongqiang; LI Peijun; B.M.Wilke; Kassem Alef

    2008-01-01

    Vegetable oil has the ability to extract polycyclic aromatic hydrocarbons (PAHs) from contaminated sandy soft for a remediation purpose, with some of the oft remaining in the soil. Although most of the PAHs were removed, the risk of residue oil in the soft was not known. The objective of this study was to evaluate the effects of the vegetable oil residue on higher plant growth and sandy soft properties after soil extraction for a better understanding of the soil remediation. Addition of sunflower oil and column experiment were performed on a PAH contaminated soil and/or a control soft, respectively. Soils were incubated for 90 d, and soil pH was measured during the soil incubation. Higher plant growth bioassays with Avena sativa L. (oat) and Brassica rapa L. (turnip) were performed after the incubation, and then soil organic carbon contents were measured. The results show that both the nutrient amendment and the sunflower oil degradation resulted in the decrease of soil pH. When these two process worked together, their effects were counteracted due to the consumption of the nutrients and oil removal, resulting in different pH profiles. Growth ofA. sativa was adversely affected by the sunflower oil, and the nutrient amendments stimulated the A. sativa growth significantly. B. rapa was more sensitive to the sunflower oil than A. sativa. Only 1% sunflower oft addition plus nutrient amendment stimulated B. rapa growth. All the other treatments on B. rapa inhibited its growth significantly. The degradation of the sunflower oft in the soils was proved by the soft organic carbon content.

  12. Testing phenotypic trade-offs in the chemical defence strategy of Scots pine under growth-limiting field conditions.

    Science.gov (United States)

    Villari, Caterina; Faccoli, Massimo; Battisti, Andrea; Bonello, Pierluigi; Marini, Lorenzo

    2014-09-01

    Plants protect themselves from pathogens and herbivores through fine-tuned resource allocation, including trade-offs among resource investments to support constitutive and inducible defences. However, empirical research, especially concerning conifers growing under natural conditions, is still scarce. We investigated the complexity of constitutive and induced defences in a natural Scots pine (Pinus sylvestris L.) stand under growth-limiting conditions typical of alpine environments. Phenotypic trade-offs at three hierarchical levels were tested by investigating the behaviour of phenolic compounds and terpenoids of outer bark and phloem. We tested resource-derived phenotypic correlations between (i) constitutive and inducible defences vs tree ring growth, (ii) different constitutive defence metabolites and (iii) constitutive concentration and inducible variation of individual metabolites. Tree ring growth was positively correlated only with constitutive concentration of total terpenoids, and no overall phenotypic trade-offs between different constitutive defensive metabolites were found. At the lowest hierarchical level tested, i.e., at the level of relationship between constitutive and inducible variation of individual metabolites, we found that different compounds displayed different behaviours; we identified five different defensive metabolite response types, based on direction and strength of the response, regardless of tree age and growth rate. Therefore, under growth-limiting field conditions, Scots pine appears to utilize varied and complex outer bark and phloem defence chemistry, in which only part of the constitutive specialized metabolism is influenced by tree growth, and individual components do not appear to be expressed in a mutually exclusive manner in either constitutive or inducible metabolism.

  13. Direct growth of Ge1-xSnx films on Si using a cold-wall ultra-high-vacuum chemical-vapor-deposition system

    Directory of Open Access Journals (Sweden)

    Aboozar eMosleh

    2015-04-01

    Full Text Available Germanium tin alloys were grown directly on Si substrate at low temperatures using a cold-wall ultra-high vacuum chemical vapor deposition system. Epitaxial growth was achieved by adopting commercial gas precursors of germane and stannic chloride without any carrier gases. The X-ray diffraction analysis showed the incorporation of Sn and that the Ge1-xSnx films are fully epitaxial and strain relaxed. Tin incorporation in the Ge matrix was found to vary from 1% to 7%. The scanning electron microscopy images and energy dispersive X-ray spectra maps show uniform Sn incorporation and continuous film growth. Investigation of deposition parameters shows that at high flow rates of stannic chloride the films were etched due to the production of HCl. The photoluminescence study shows the reduction of bandgap from 0.8 eV to 0.55 eV as a result of Sn incorporation.

  14. Comparison of physical Characteristics and cell culture test of hydroxyapatite/collagen composite coating on NiTi SMA: electrochemical deposition and chemically biomimetic growth

    Institute of Scientific and Technical Information of China (English)

    HU Kai; YANG Xianjin; CAI Yanli; CUI Zhenduo; WEI Qiang

    2007-01-01

    A hydroxyapatite(HA)/collagen(COL)composite coating on NiTi shape memory alloy (SMA)was prepared by electrochemical deposition(ELD)in modified simulated body fluid (MSBF).To draw comparisons of physical characteristics and bioactivity of the composite coating,the HA/COL composite coating was also prepared by chemically biomimetic growth (BG)and the ELD coating was re-soaked in MSBF again for further biomimetic growth(called EBG method in this paper).It was indicated that the c-axis of HA crystals was oriented parallel to the longitudinal direction of the COL fibril in BG and EBG coating,which could not found in ELD coating.The EBG method could induce a denser,thicker and better crystallized HA/COL coating.The cell culture test indicated that the BG coating presented better cell biocompatibility.

  15. Screw-Dislocation-Driven Growth of Two-Dimensional Few-Layer and Pyramid-Like WSe2 by Sulfur-Assisted Chemical Vapor Deposition

    OpenAIRE

    Chen, Liang; Liu, Bilu; Abbas, Ahmad N.; Ma, Yuqiang; Fang, Xin; Liu, Yihang; Zhou, Chongwu

    2014-01-01

    Two-dimensional (2D) layered tungsten diselenides (WSe2) material has recently drawn a lot of attention due to its unique optoelectronic properties and ambipolar transport behavior. However, direct chemical vapor deposition (CVD) synthesis of 2D WSe2 is not as straightforward as other 2D materials due to the low reactivity between reactants in WSe2 synthesis. In addition, the growth mechanism of WSe2 in such CVD process remains unclear. Here we report the observation of a screw-dislocation-dr...

  16. Controlled Growth of Non-Uniform Arsenic Profiles in Silicon Reduced-Pressure Chemical Vapor Deposition Epitaxial Layers

    NARCIS (Netherlands)

    Popadic, M.; Scholtes, T.L.M.; De Boer, W.; Sarubbi, F.; Nanver, L.K.

    2009-01-01

    An empirical model of As surface segregation during reduced-pressure chemical vapor deposition Si epitaxy is presented. This segregation mechanism determines the resulting doping profile in the grown layer and is here described by a model of simultaneous and independent As adsorption and segregation

  17. Chemical characterization of submicron aerosol and particle growth events at a national background site (3295 m a.s.l. in the Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    W. Du

    2015-05-01

    Full Text Available Atmospheric aerosols exert highly uncertain impacts on radiative forcing and also have detrimental effects on human health. While aerosol particles are widely characterized in megacities in China, aerosol composition, sources and particle growth in rural areas in the Tibetan Plateau remain less understood. Here we present the results from an autumn study that was conducted from 5 September to 15 October 2013 at a national background monitoring station (3295 m a.s.l. in the Tibetan Plateau. The submicron aerosol composition and particle number size distributions were measured in situ with an Aerodyne Aerosol Chemical Speciation Monitor (ACSM and a Scanning Mobility Particle Sizer (SMPS. The average mass concentration of submicron aerosol (PM1 is 11.9 μg m−3 (range: 1.0–78.4 μg m−3 for the entire study, which is much lower than those observed at urban and rural sites in eastern China. Organics dominated PM1 on average accounting for 43%, followed by sulfate (28% and nitrate (1%. Positive matrix factorization analysis of ACSM organic aerosol (OA mass spectra identified an oxygenated OA (OOA and a biomass burning OA (BBOA. The OOA dominated OA composition accounting for 85% on average, 17% of which was inferred from aged BBOA. The BBOA contributed a considerable fraction of OA (15% due to the burning of cow dung and straws in September. New particle formation and growth events were frequently observed (80% of time throughout the study. The average particle growth rate is 2.0 nm h−1 (range: 0.8–3.2 nm h−1. By linking the evolution of particle number size distribution to aerosol composition, we found an elevated contribution of organics during particle growth periods and also a positive relationship between the growth rate and the fraction of OOA in OA, which potentially indicates an important role of organics in particle growth in the Tibetan Plateau.

  18. Weed host specificity of the aphid, Aphis spiraecola: developmental and reproductive performance of aphids in relation to plant growth and leaf chemicals of the Siam weed, Chromolaena odorata.

    Science.gov (United States)

    Agarwala, B K; Das, Jhuma

    2012-01-01

    Density, distribution, and nutritional quality of plants are the causal basis of host plant selection in aphids. Nutritional qualities of a plant vary according to its growth stage and also in response to seasonal variation. How host plant growth stages shape aphid performance was studied in Aphis spiraecola Patch (Homoptera: Aphididae) on the perennial Siam weed, Chromolaena odorata (L.) King and Robinson (Asterales: Asteraceae). This plant species is the preferred host in the hot and humid tropical parts of northeast and southern India. Variations in developmental and reproductive performances in apterous viviparous female aphids were recorded in relation to differences in leaf chemicals in different growth stages of C. odorata. Aphids reproduced at higher rates in the vegetative stage of C. odorata when developmental time was shortest, and fecundity was higher in a longer reproductive time. Intrinsic rate of increase and net reproductive rate were also recorded to be higher in the vegetative stage of the weed host. In the vegetative stage, leaves contained higher quantity of proteins and nitrogen, which are vital for insect reproduction. Results of this study have demonstrated that A spiraecola showed synchronization of its developmental and reproductive performances to growth stages of C. odorata, which occur in high abundance in the study area. PMID:22950746

  19. Role of ZnO thin film in the vertically aligned growth of ZnO nanorods by chemical bath deposition

    Science.gov (United States)

    Son, Nguyen Thanh; Noh, Jin-Seo; Park, Sungho

    2016-08-01

    The effect of ZnO thin film on the growth of ZnO nanorods was investigated. ZnO thin films were sputter-deposited on Si substrate with varying the thickness. ZnO nanorods were grown on the thin film using a chemical bath deposition (CBD) method at 90 °C. The ZnO thin films showed granular structure and vertical roughness on the surface, which facilitated the vertical growth of ZnO nanorods. The average grain size and the surface roughness of ZnO film increased with an increase in film thickness, and this led to the increase in both the average diameter and the average length of vertically grown ZnO nanorods. In particular, it was found that the average diameter of ZnO nanorods was very close to the average grain size of ZnO thin film, confirming the role of ZnO film as a seed layer for the vertical growth of ZnO nanorods. The CBD growth on ZnO seed layers may provide a facile route to engineering vertically aligned ZnO nanorod arrays.

  20. Influence of growth transients on interface and composition uniformity of ultra thin In(As,P) and (In,Al,Ga)As epilayers grown by chemical beam epitaxy

    International Nuclear Information System (INIS)

    In this work, measurements of epitaxial growth rate transients for multiple quantum wells (MQWs) in chemical beam epitaxy (CBE) have been made. Mass spectrometry measurements of typical growth conditions were made of gas source species of the InAsxP1-x/InP system, while reflection high-energy electron diffraction (RHEED) measurements were made for the GaAs/AlxGa1-xAs and InxGa1-xAs/GaAs systems. The results of these experiments went directly into predicting the transient growth rate of thin layers for multi-quantum well photovoltaic devices. The data obtained using these techniques resulted in an improved growth interruption sequence for MQW structures in the InAsxP1-x/InP system. Improvements in overall material quality have been observed by high resolution X-ray diffraction (HRXRD). HRXRD measurements of the InAsxP1-x/InP structures yield sharp satellite peaks revealing the possibility of achieving nearly perfect interfaces. From low temperature photoluminescence, narrow emission linewidths from quantum wells indicate an enhanced compositional uniformity, and room temperature photocurrent spectroscopy reveals an improvement in device performance

  1. Effect of Growth Pressure on Epitaxial Graphene Grown on 4H-SiC Substrates by Using Ethene Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Shuxian Cai

    2015-08-01

    Full Text Available The Si(0001 face and C(000-1 face dependences on growth pressure of epitaxial graphene (EG grown on 4H-SiC substrates by ethene chemical vapor deposition (CVD was studied using atomic force microscopy (AFM and micro-Raman spectroscopy (μ-Raman. AFM revealed that EGs on Si-faced substrates had clear stepped morphologies due to surface step bunching. However, This EG formation did not occur on C-faced substrates. It was shown by μ-Raman that the properties of EG on both polar faces were different. EGs on Si-faced substrates were relatively thinner and more uniform than on C-faced substrates at low growth pressure. On the other hand, D band related defects always appeared in EGs on Si-faced substrates, but they did not appear in EG on C-faced substrate at an appropriate growth pressure. This was due to the μ-Raman covering the step edges when measurements were performed on Si-faced substrates. The results of this study are useful for optimized growth of EG on polar surfaces of SiC substrates.

  2. Effect of pretreatment bias on the nucleation and growth mechanisms of ultrananocrystalline diamond films via bias-enhanced nucleation and growth: An approach to interfacial chemistry analysis via chemical bonding mapping

    International Nuclear Information System (INIS)

    The effect of pretreatment bias on the nucleation and growth mechanisms of the ultrananocrystalline diamond (UNCD) films on the Si substrate via bias-enhanced nucleation and bias-enhanced growth (BEN-BEG) was investigated using cross-sectional high-resolution transmission electron microscopy, chemical bonding mapping, and Raman spectroscopy. The mirror-polished substrate surface showed the formation of a triangular profile produced by a dominant physical sputtering mechanism induced by ion bombardment of ions from the hydrogen plasma accelerated toward the substrate due to biasing and a potential hydrogen-induced chemical reaction component before synthesizing the UNCD films. The BEN-BEG UNCD films grown on the Si substrate with biased and unbiased pretreatments in the hydrogen plasma were compared. In the case of the bias-pretreated substrate, the SiC phases were formed at the peaks of the Si surface triangular profile due to the active unsaturated Si bond and the enhanced local electrical field. The UNCD grains grew preferentially at the peaks of the triangular substrate surface profile and rapidly covered the amorphous carbon (a-C) and oriented graphite phases formed in the valley of the surface profile. In the case of the substrate with unbiased pretreatment, the SiC phases were formed via the reactions between the hydrocarbon species and the active Si atoms released from the substrate with assistance of the hydrogen plasma. The UNCD grains nucleated on the nucleating sites consisting of the SiC, a-C, and graphite phases. Growth mechanisms for the BEN-BEG UNCD films on both Si substrates were proposed to elucidate the different nucleation processes. Applying bias on the Si substrate pretreated in the hydrogen plasma optimized the nucleation sites for growth of UNCD grains, resulting in the low content of the nondiamond phases in UNCD films

  3. Effects of aqueous extract of four mosses on seed germination and early seedling growth of two Polygonaceae plants%四种苔藓植物提取液对二种蓼科植物种子萌发和幼苗生长的影响

    Institute of Scientific and Technical Information of China (English)

    俞英; 郭水良; 陈建华; 方芳

    2009-01-01

    研究卵叶泥炭藓(Sphagnum ovatum),卷叶凤尾藓(Fissidens cristatus),弯叶灰藓(Hypnum callichroum)和大金发藓(Polytrichum commune)的水粗提取液对维管植物虎杖和皱叶酸模种子萌发和幼苗生长的影响.结果显示:四种苔藓植物的粗提取液对两种植物的种子萌发率并没有显著影响.然而,弯叶灰藓,、卵叶泥炭藓和卷叶凤尾藓的提取液抑制了皱叶酸模种子的活力指数.除此之外,卷叶凤尾藓还显著地抑制了它幼苗的干重.四种藓类的提取液对虎杖的种子活力指数和干重,但是卷叶凤尾藓的提取液对幼苗的生长有显著的影响.苔藓植物粗提取液对种子萌发和幼苗生长的影响的机制并不清楚,有待进一步研究.%In this paper,the possible influences of the aqueous extracts of four bryophytes(Sphagnum ovatum,Fissidens cristatus,Hypnum callichroum and Polytrichum commune)on the seed germination and young seedling growth of two vascular plants(Rumex crispus,Polygonum cuspidatum)were investigated.The results showed that the aqueous extracts of these four mosses didn't affect seed germination.However,the crude aqueous extracts of H.callichroum,S.ovatum and F.cristatus inhibited the vigor indices of R.crispus.Furthermore,the crude aqueous extract of F.cristatus significantly enhanced its dry seedling mass,and F.cristatus and S.ovatum significantly inhibited its seedling elongation.For P.cuspidatum,the crude aqueous extracts of four mosses had little effects on its vigor indices and dry mass,but the aqueous extract of F.cristatu had significantly negative influences on its seedling elongation.The possible mechanism that the aqueous extracts of these four bryophytes influencing seed germination and seedling growth of these two vascular plants was not determined.More studies are needed.

  4. A multiphase model for chemically- and mechanically- induced cell differentiation in a hollow fibre membrane bioreactor: minimising growth factor consumption.

    Science.gov (United States)

    Pearson, Natalie C; Oliver, James M; Shipley, Rebecca J; Waters, Sarah L

    2016-06-01

    We present a simplified two-dimensional model of fluid flow, solute transport, and cell distribution in a hollow fibre membrane bioreactor. We consider two cell populations, one undifferentiated and one differentiated, with differentiation stimulated either by growth factor alone, or by both growth factor and fluid shear stress. Two experimental configurations are considered, a 3-layer model in which the cells are seeded in a scaffold throughout the extracapillary space (ECS), and a 4-layer model in which the cell-scaffold construct occupies a layer surrounding the outside of the hollow fibre, only partially filling the ECS. Above this is a region of free-flowing fluid, referred to as the upper fluid layer. Following previous models by the authors (Pearson et al. in Math Med Biol, 2013, Biomech Model Mechanbiol 1-16, 2014a, we employ porous mixture theory to model the dynamics of, and interactions between, the cells, scaffold, and fluid in the cell-scaffold construct. We use this model to determine operating conditions (experiment end time, growth factor inlet concentration, and inlet fluid fluxes) which result in a required percentage of differentiated cells, as well as maximising the differentiated cell yield and minimising the consumption of expensive growth factor. PMID:26276678

  5. Different isotope and chemical patterns of pyrite oxidation related to lag and exponential growth phases of Acidithiobacillus ferrooxidans reveal a microbial growth strategy

    Science.gov (United States)

    Brunner, Benjamin; Yu, Jae-Young; Mielke, Randall E.; MacAskill, John A.; Madzunkov, Stojan; McGenity, Terry J.; Coleman, Max

    2008-06-01

    The solution chemistry during the initial (slow increase of dissolved iron and sulfate) and main stage (rapid increase of dissolved iron and sulfate) of pyrite leaching by Acidithiobacillus ferrooxidans (Af) at a starting pH of 2.05 shows significant differences. During the initial stage, ferrous iron (Fe2+) is the dominant iron species in solution and the molar ratio of produced sulfate (SO42-) and total iron (Fetot) is 1.1, thus does not reflect the stoichiometry of pyrite (FeS2). During the main stage, ferric iron (Fe3+) is the dominant iron species in solution and the SO42-:Fetot ratio is with 1.9, close to the stoichiometry of FeS2. Another difference between initial and main stage is an initial trend to slightly higher pH values followed by a drop during the main stage to pH 1.84. These observations raise the question if there are different modes of bioleaching of pyrite, and if there are, what those modes imply in terms of leaching mechanisms. Different oxygen and sulfur isotope trends of sulfate during the initial and main stages of pyrite oxidation confirm that there are two pyrite bioleaching modes. The biochemical reactions during initial stage are best explained by the net reaction FeS2 + 3O2 ⇒ Fe2+ + SO42- + SO2(g). The degassing of sulfur dioxide (SO2) acts as sink for sulfur depleted in 34S compared to pyrite, and is the cause of the SO42-:Fetot ratio of 1.1 and the near constant pH. During the exponential phase, pyrite sulfur is almost quantitatively converted to sulfate, according to the net reaction FeS2 + 15/4O2 + 1/2H2O ⇒ Fe3+ + 2SO42- + H+. We hypothesize that the transition between the modes of bioleaching of pyrite is due to the impact of the accumulation of ferrous iron, which induces changes in the metabolic activity of Af and may act as an inhibitor for the oxidation of sulfur species. This transition defines a fundamental change in the growth strategy of Af. A mode, where bacteria gain energy by oxidation of elemental sulfur to

  6. Microwave assisted rapid growth of Mg(OH){sub 2} nanosheet networks for ethanol chemical sensor application

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hazmi, Faten [Department of Physics, College of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21569 (Saudi Arabia); Umar, Ahmad, E-mail: ahmadumar786@gmail.com [Promising Centre for Sensors and Electronic Devices (PCSED) and Centre for Advanced Materials and Nano-Research (CAMNR), Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Dar, G.N. [Promising Centre for Sensors and Electronic Devices (PCSED) and Centre for Advanced Materials and Nano-Research (CAMNR), Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Al-Ghamdi, A.A.; Al-Sayari, S.A. [Department of Physics, College of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21569 (Saudi Arabia); Al-Hajry, A. [Promising Centre for Sensors and Electronic Devices (PCSED) and Centre for Advanced Materials and Nano-Research (CAMNR), Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Department of Physics, College of Science and Arts, Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Kim, S.H. [Promising Centre for Sensors and Electronic Devices (PCSED) and Centre for Advanced Materials and Nano-Research (CAMNR), Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Al-Tuwirqi, Reem M. [Department of Physics, College of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21569 (Saudi Arabia); Alnowaiserb, Fowzia [Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); El-Tantawy, Farid [Department of Physics, Faculty of Science, Suez Canal University, Ismailia (Egypt)

    2012-04-05

    Highlights: Black-Right-Pointing-Pointer A facile microwave-assisted synthesis and characterizations of magnesium hydroxide (Mg(OH){sub 2}) nanosheet networks. Black-Right-Pointing-Pointer Fabrication of ethanol sensor based on (Mg(OH){sub 2}) nanosheet networks. Black-Right-Pointing-Pointer Good sensitivity ({approx}3.991 {mu}A cm{sup -2} mM{sup -1}) and lower detection limit (5 {mu}M). Black-Right-Pointing-Pointer This research opens a way to utilize Mg(OH){sub 2} nanostructures for chemical sensors applications. - Abstract: This paper reports a facile microwave-assisted synthesis of magnesium hydroxide (Mg(OH){sub 2}) nanosheet networks and their utilization for the fabrication of efficient ethanol chemical sensor. The synthesized nanosheets networks were characterized in terms of their morphological, structural and optical properties using various analysis techniques such as field emission scanning electron microscopy (FESEM), X-ray diffraction pattern (XRD), Fourier transform infrared (FTIR) and UV-Vis spectroscopy. The detailed morphological and structural investigations reveal that the synthesized (Mg(OH){sub 2}) products are nanosheet networks, grown in high density, and possessing hexagonal crystal structure. The optical band gap of as-synthesized Mg(OH){sub 2} nanosheet networks was examined by UV-Vis absorption spectrum, and found to be 5.76 eV. The synthesized nanosheet networks were used as supporting matrices for the fabrication of I-V technique based efficient ethanol chemical sensor. The fabricated ethanol sensor based on nanosheet networks exhibits good sensitivity ({approx}3.991 {mu}A cm{sup -2} mM{sup -1}) and lower detection limit (5 {mu}M), with linearity (R = 0.9925) in short response time (10.0 s). This work demonstrate that the simply synthesized Mg(OH){sub 2} nanosheet networks can effectively be used for the fabrication of efficient ethanol chemical sensors.

  7. Formation of Graphene Grain Boundaries on Cu(100) Surface and a Route Towards Their Elimination in Chemical Vapor Deposition Growth

    OpenAIRE

    Qinghong Yuan; Guangyao Song; Deyan Sun; Feng Ding

    2014-01-01

    Grain boundaries (GBs) in graphene prepared by chemical vapor deposition (CVD) greatly degrade the electrical and mechanical properties of graphene and thus hinder the applications of graphene in electronic devices. The seamless stitching of graphene flakes can avoid GBs, wherein the identical orientation of graphene domain is required. In this letter, the graphene orientation on one of the most used catalyst surface — Cu(100) surface, is explored by density functional theory (DFT) calculatio...

  8. The Growth of InGaAsN for High Efficiency Solar Cells by Metalorganic Chemical Vapor Deposition

    International Nuclear Information System (INIS)

    InGaAsN alloys are a promising material for increasing the efficiency of multi-junction solar cells now used for satellite power systems. However, the growth of these dilute N containing alloys has been challenging with further improvements in material quality needed before the solar cell higher efficiencies are realized. Nitrogen/V ratios exceeding 0.981 resulted in lower N incorporation and poor surface morphologies. The growth rate was found to depend on not only the total group III transport for a fixed N/V ratio but also on the N/V ratio. Carbon tetrachloride and dimethylzinc were effective for p-type doping. Disilane was not an effective n-type dopant while SiCl4 did result in n-type material but only a narrow range of electron concentrations (2-5e17cm(sup -3)) were achieved

  9. Productivity in physical and chemical science predicts the future economic growth of developing countries better than other popular indices.

    Science.gov (United States)

    Jaffe, Klaus; Caicedo, Mario; Manzanares, Marcos; Gil, Mario; Rios, Alfredo; Florez, Astrid; Montoreano, Claudia; Davila, Vicente

    2013-01-01

    Scientific productivity of middle income countries correlates stronger with present and future wealth than indices reflecting its financial, social, economic or technological sophistication. We identify the contribution of the relative productivity of different scientific disciplines in predicting the future economic growth of a nation. Results show that rich and poor countries differ in the relative proportion of their scientific output in the different disciplines: countries with higher relative productivity in basic sciences such as physics and chemistry had the highest economic growth in the following five years compared to countries with a higher relative productivity in applied sciences such as medicine and pharmacy. Results suggest that the economies of middle income countries that focus their academic efforts in selected areas of applied knowledge grow slower than countries which invest in general basic sciences.

  10. Productivity in physical and chemical science predicts the future economic growth of developing countries better than other popular indices.

    Directory of Open Access Journals (Sweden)

    Klaus Jaffe

    Full Text Available Scientific productivity of middle income countries correlates stronger with present and future wealth than indices reflecting its financial, social, economic or technological sophistication. We identify the contribution of the relative productivity of different scientific disciplines in predicting the future economic growth of a nation. Results show that rich and poor countries differ in the relative proportion of their scientific output in the different disciplines: countries with higher relative productivity in basic sciences such as physics and chemistry had the highest economic growth in the following five years compared to countries with a higher relative productivity in applied sciences such as medicine and pharmacy. Results suggest that the economies of middle income countries that focus their academic efforts in selected areas of applied knowledge grow slower than countries which invest in general basic sciences.

  11. Effect of Irrigation Timing on Root Zone Soil Temperature, Root Growth and Grain Yield and Chemical Composition in Corn

    Directory of Open Access Journals (Sweden)

    Xuejun Dong

    2016-05-01

    Full Text Available High air temperatures during the crop growing season can reduce harvestable yields in major agronomic crops worldwide. Repeated and prolonged high night air temperature stress may compromise plant growth and yield. Crop varieties with improved heat tolerance traits as well as crop management strategies at the farm scale are thus needed for climate change mitigation. Crop yield is especially sensitive to night-time warming trends. Current studies are mostly directed to the elevated night-time air temperature and its impact on crop growth and yield, but less attention is given to the understanding of night-time soil temperature management. Delivering irrigation water through drip early evening may reduce soil temperature and thus improve plant growth. In addition, corn growers typically use high-stature varieties that inevitably incur excessive respiratory carbon loss from roots and transpiration water loss under high night temperature conditions. The main objective of this study was to see if root-zone soil temperature can be reduced through drip irrigation applied at night-time, vs. daytime, using three corn hybrids of different above-ground architecture in Uvalde, TX where day and night temperatures during corn growing season are above U.S. averages. The experiment was conducted in 2014. Our results suggested that delivering well-water at night-time through drip irrigation reduced root-zone soil temperature by 0.6 °C, increase root length five folds, plant height 2%, and marginally increased grain yield by 10%. However, irrigation timing did not significantly affect leaf chlorophyll level and kernel crude protein, phosphorous, fat and starch concentrations. Different from our hypothesis, the shorter, more compact corn hybrid did not exhibit a higher yield and growth as compared with taller hybrids. As adjusting irrigation timing would not incur an extra cost for farmers, the finding reported here had immediate practical implications for farm

  12. Effect of Irrigation Timing on Root Zone Soil Temperature, Root Growth and Grain Yield and Chemical Composition in Corn

    OpenAIRE

    Xuejun Dong; Wenwei Xu; Yongjiang Zhang; Daniel I. Leskovar

    2016-01-01

    High air temperatures during the crop growing season can reduce harvestable yields in major agronomic crops worldwide. Repeated and prolonged high night air temperature stress may compromise plant growth and yield. Crop varieties with improved heat tolerance traits as well as crop management strategies at the farm scale are thus needed for climate change mitigation. Crop yield is especially sensitive to night-time warming trends. Current studies are mostly directed to the elevated night-time ...

  13. Productivity in Physical and Chemical Science Predicts the Future Economic Growth of Developing Countries Better than Other Popular Indices

    OpenAIRE

    Jaffe, Klaus; Caicedo, Mario; Manzanares, Marcos; Gil, Mario; Rios, Alfredo; Florez, Astrid; Montoreano, Claudia; Davila, Vicente

    2013-01-01

    Scientific productivity of middle income countries correlates stronger with present and future wealth than indices reflecting its financial, social, economic or technological sophistication. We identify the contribution of the relative productivity of different scientific disciplines in predicting the future economic growth of a nation. Results show that rich and poor countries differ in the relative proportion of their scientific output in the different disciplines: countries with higher rel...

  14. The environment recording unit in coral skeletons: structural and chemical evidences of a biochemically driven stepping-growth process in coral fibres

    Directory of Open Access Journals (Sweden)

    Y. Dauphin

    2004-09-01

    Full Text Available To improve our understanding of the environment recording by scleractinian corals, a detailed study of the skeleton microstructure has been carried out. A series of physico-chemical in situ characterizations was made, an approach that provides us with structural and biochemical information at the micrometric and nanometric scales. Gathering of these data results in a significant change in our concept of the growth of coral skeletons. In contrast to the usual view of an aggregate of purely mineral units (the coral fibres independently growing by a simple chemical precipitation, coral skeletons appear to be biochemically controlled structures. Both structural and biochemical data reveal the micron-scaled stepping growth-mode of fibres, and its global coordination. In this process, sulfated acidic proteoglycans probably play a major role, due to their ability to create polymeric frameworks. Atomic force microscopy confirms the close relationship of organic and mineral phases at the nanometric scale. A new microstructural model of coral skeleton formation is proposed, that places coral skeletons among the typical "matrix mediated structures". From a practical standpoint, these results may contribute to develop a new high resolution approach in the study of paleoenvironments.

  15. Comparison of two chemical cleavage methods for preparation of a truncated form of recombinant human insulin-like growth factor I from a secreted fusion protein.

    Science.gov (United States)

    Forsberg, G; Baastrup, B; Brobjer, M; Lake, M; Jörnvall, H; Hartmanis, M

    1989-12-01

    We have produced a naturally occurring variant of human insulin-like growth factor I, truncated by three amino acids at the amino terminus. The polypeptide is obtained as a fusion protein in Escherichia coli. The fusion partner is a synthetic IgG-binding peptide. During fermentation the fusion protein is secreted into the medium, and is purified on IgG--Sepharose prior to cleavage. Two different genes for the fusion protein were used, allowing chemical cleavage at either a tryptophan linker or a methionine linker between the fusion partner and the growth factor, using N-chlorosuccinimide (NCS) or cyanogen bromide (CNBr) respectively. A partial CNBr cleavage yielded the native peptide, whereas the NCS cleavage yielded a product in which the single methionine had been oxidized to the sulfoxide. The forms from both cleavage methods exhibited biological activity and were characterized after purification to homogeneity. Both cleavage methods gave products having correct N- and C-terminal ends. The purified product had a biological activity equal to that of corresponding material from natural sources, 15 000 U/mg. Modified forms of truncated IGF-I were also identified, purified and characterized. Modifications such as proteolysis and misincorporation of norleucine for methionine occurred during biosynthesis, while oxidation of methionine took place during both fermentation and chemical cleavage. PMID:2696476

  16. Epitaxial Growth of beta-Silicon Carbide (SiC) on a Compliant Substrate via Chemical Vapor Deposition (CVD)

    Science.gov (United States)

    Mitchell, Sharanda L.

    1996-01-01

    Many lattice defects have been attributed to the lattice mismatch and the difference in the thermal coefficient of expansion between SiC and silicon (Si). Stacking faults, twins and antiphase boundaries are some of the lattice defects found in these SiC films. These defects may be a partial cause of the disappointing performance reported for the prototype devices fabricated from beta-SiC films. The objective of this research is to relieve some of the thermal stress due to lattice mismatch when SiC is epitaxially grown on Si. The compliant substrate is a silicon membrane 2-4 microns thick. The CVD process includes the buffer layer which is grown at 1360 C followed by a very thin epitaxial growth of SiC. Then the temperature is raised to 1500 C for the subsequent growth of SiC. Since silicon melts at 1415 C, the SiC will be grown on molten Silicon which is absorbed by a porous graphite susceptor eliminating the SiC/Si interface. We suspect that this buffer layer will yield less stressed material to help in the epitaxial growth of SiC.

  17. Effects of Dietary Vitamin C Supplementation on Growth Performance and Tissue Chemical Composition of Silurus Glanis (Linnaeus, 1578

    Directory of Open Access Journals (Sweden)

    Sandita (Placinta Ion

    2012-10-01

    Full Text Available The present study was conducted to quantify the effect of Ascorbic acid (Vitamin C at the following inclusion levels: 0 mg AA per kg feed (V0, 50 mg AA per kg feed (V1, 100 mg AA per kg feed (V2 and 150 mg AA per kg of feed (V3, on growth performance and feed utilization efficiency of juvenile Silurus glanis, reared in a recirculating aquaculture system. The European catfish, with initial mean body weight of 118.96±0.43g, was fed with 1.8 percentage of their body weight, 3 times per day. After feeding with supplemented diets for 4 weeks, growth performance, feed utilization and health status were assessed. The results of the current study showed that supplementation with Vitamin C at 50 mg AA per kg (V1 of feed had a positive effect over FCR, SGR, PER, comparing with the control group (V0 and the V2 and V3 experimental variants. Thus, it is demonstrated that the appropriate doze of Vitamin C should be established before applying it to intensive aquaculture, in order to obtain high growth performance and a good health condition of fish.

  18. Effect of rare earth elements from monazite on growth-vigor and chemical composition of Phaseolus vulgaris

    Energy Technology Data Exchange (ETDEWEB)

    Sharoubeem, H.H.; Milad, N.E.

    1966-01-01

    This investigation deals with the effect of different concentrations of rare earth elements (as monazite extract containing Th, Ce, La, Pr, and Nd in the form of nitrates) on the growth and nutritional status of Phaseolus vulgaris. Phaseolus vulgaris plants were grown in sand cultures to which rare earths were added to supply 2.5, 5, 7.5, and 10 ppm. Growth of both tops and roots showed a marked response to rare earths application, especially in the development of tops. The addition of rare earths to the culture solution resulted in better development of plant tops and roots up to 5 ppm; above 5 ppm there was less growth but always more than tops and roots of plants grown in culture medium without rare earths. The application of rare earth elements increased the water content of roots, but not of tops, to a maximum at the level of 5 ppm. In response to rare earth elements the dry matter of tops increases more in proportion than does the dry matter of their roots; top/root ratios are, consequently, higher in the presence or rare earths. The application of rare earths increased the nitrogen, potassium, and sodium contents of the experimental plant tops up to a maximum at the level of 5 ppm rare earths. With further increase of rare earths these contents were decreased. The reverse was true with regard to calcium, magnesium, and phosphorus contents.

  19. Electrochemical, Chemical and Enzymatic Oxidations of Phenothiazines

    NARCIS (Netherlands)

    Blankert, B.; Hayen, H.; Leeuwen, van S.M.; Karst, U.; Bodoki, E.; Lotrean, S.; Sandulescu, R.; Mora Diaz, N.; Dominguez, O.; Arcos, J.; Kauffmann, J.-M.

    2005-01-01

    The oxidation of several phenothiazine drugs (phenothiazine, promethazine hydrochloride, promazine hydrochloride, trimeprazine hydrochloride and ethopropazine hydrochloride) has been carried out in aqueous acidic media by electrochemical, chemical and enzymatic methods. The chemical oxidation was pe

  20. Chemical Vapor Deposition of MoS2: Insight Into the Growth Mechanism by Separated Gas Flow Experiments.

    Science.gov (United States)

    Yanase, Takashi; Watanabe, Sho; Weng, Mengting; Nagahama, Taro; Shimada, Toshihiro

    2016-04-01

    We report detailed experiments on chemical vapor deposition of an atomic' layer semiconductor MoS2. We developed a new type of CVD system in which MoO3 and S sources are separately supplied to the substrates. It has become possible to precisely control the supply of the materials separately in the order of seconds. Raman and XPS analysis of the films grown under various conditions revealed that the initially obtained films are S-deficient and complete stoichiometry is reached after several minutes under S vapor flow. PMID:27451608

  1. Influence of complexing agent on the growth of chemically deposited Ni3Pb2S2 thin films

    Directory of Open Access Journals (Sweden)

    Ho Soonmin

    2014-09-01

    Full Text Available Ni3Pb2S2 thin films were prepared by chemical bath deposition method. Here, the objective of this research was to investigate the influence of complexing agent on the properties of films.These films were characterized using atomic force microscopy, UV-Visible spectro photometer and X-ray diffraction. It was found that, as the concentration of tartaric acid increased, film thickness increased, but, the band gap reduced. For the films prepared using 0.1M of tartaric acid, the films were uniform and completely covered the substrates.

  2. Growth of AlGaN Epitaxial Film with High Al Content by Metalorganic Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Lan; ZHAO De-Gang; YANG Hui; LIANG Jun-Wu

    2007-01-01

    A high-Al-content AlCaN epilayer is grown on a low-temperature-deposited AlN buffer on (0001) sapphire bylow pressure metalorganic chemical vapour deposition. The dependence of surface roughness, tilted mosaicity,and twisted mosaicity on the conditions of the AlCaN epilayer deposition is evaluated. An AlCaN epilayer withfavourable surface morphology and crystal quality is deposited on a 20nm low-temperature-deposited AlN buffer at a low Ⅴ/Ⅲ flow ratio of 783 and at a low reactor pressure of 100 Torr, and the adduct reaction between trimethylaluminium and NH3 is considered.

  3. Effect of MoO3 constituents on the growth of MoS2 nanosheets by chemical vapor deposition

    Science.gov (United States)

    Wang, Xuan; Zhang, Yong Ping; Qian Chen, Zhi

    2016-06-01

    The highly crystalline and uniform MoS2 film was grown on Si substrate by a low-pressure chemical vapor deposition method using S and MoO3 as precursors at an elevated temperature. The structures and properties of MoS2 nanosheets vary greatly with the content of MoO3 constituents in the films. The nanostructured MoS2 film exhibits strong photoluminescence in the visible range. This work may provide a pathway to synthesizing MoS2 nanosheets and facilitate the development of applicable devices.

  4. Rock fracture processes in chemically reactive environments

    Science.gov (United States)

    Eichhubl, P.

    2015-12-01

    Rock fracture is traditionally viewed as a brittle process involving damage nucleation and growth in a zone ahead of a larger fracture, resulting in fracture propagation once a threshold loading stress is exceeded. It is now increasingly recognized that coupled chemical-mechanical processes influence fracture growth in wide range of subsurface conditions that include igneous, metamorphic, and geothermal systems, and diagenetically reactive sedimentary systems with possible applications to hydrocarbon extraction and CO2 sequestration. Fracture processes aided or driven by chemical change can affect the onset of fracture, fracture shape and branching characteristics, and fracture network geometry, thus influencing mechanical strength and flow properties of rock systems. We are investigating two fundamental modes of chemical-mechanical interactions associated with fracture growth: 1. Fracture propagation may be aided by chemical dissolution or hydration reactions at the fracture tip allowing fracture propagation under subcritical stress loading conditions. We are evaluating effects of environmental conditions on critical (fracture toughness KIc) and subcritical (subcritical index) fracture properties using double torsion fracture mechanics tests on shale and sandstone. Depending on rock composition, the presence of reactive aqueous fluids can increase or decrease KIc and/or subcritical index. 2. Fracture may be concurrent with distributed dissolution-precipitation reactions in the hostrock beyond the immediate vicinity of the fracture tip. Reconstructing the fracture opening history recorded in crack-seal fracture cement of deeply buried sandstone we find that fracture length growth and fracture opening can be decoupled, with a phase of initial length growth followed by a phase of dominant fracture opening. This suggests that mechanical crack-tip failure processes, possibly aided by chemical crack-tip weakening, and distributed solution-precipitation creep in the

  5. The role of catalytic nanoparticle pretreatment on the growth of vertically aligned carbon nanotubes by hot-filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Hwan; Gohier, Aurélien; Bourée, Jean Eric; Châtelet, Marc; Cojocaru, Costel-Sorin, E-mail: costel-sorin.cojocaru@polytechnique.edu

    2015-01-30

    The effect of atomic hydrogen assisted pre-treatment on the growth of vertically aligned carbon nanotubes using hot-filament chemical vapor deposition was investigated. Iron nanoparticle catalysts were formed on an aluminum oxide support layer by spraying of iron chloride salt solutions as catalyst precursor. It is found that pre-treatment time and process temperature tune the density as well as the shape and the structure of the grown carbon nanotubes. An optimum pre-treatment time can be found for the growth of long and well aligned carbon nanotubes, densely packed to each other. To provide insight on this behavior, the iron catalytic nanoparticles formed after the atomic hydrogen assisted pre-treatment were analyzed by atomic force microscopy. The relations between the size and the density of the as-formed catalyst and the as-grown carbon nanotube's structure and density are discussed. - Highlights: • Effect of the atomic hydrogen assisted pre-treatment on the growth of VACNT using hot-filament CVD. • Pre-treatment time and process temperature tune the density, the shape and the structure of the CNTs. • Correlations between size and density of the as-formed catalyst and the CNT’s structure and density. • Carbon nanotubes synthesized at low temperature down to 500 °C using spayed iron chloride salts. • Density of the CNT carpet adjusted by catalytic nanoparticle engineering.

  6. SOIL CHEMICAL PROPERTIES AND GROWTH OF SUNFLOWER (HELIANTHUS ANNUUS L. AS AFFECTED BY THE APPLICATION OF ORGANIC FERTILIZERS AND INOCULATION WITH ARBUSCULAR MYCORRHIZAL FUNGI

    Directory of Open Access Journals (Sweden)

    Apolino José Nogueira da Silva

    2015-02-01

    Full Text Available The use of organic fertilizers and the inoculation of mycorrhizal fungi in the cultivation of oil crops is essential to reduce production costs and minimize negative impacts on natural resources. A field experiment was conducted in an Argissolo Amarelo (Ultisol with the aim of evaluating the effects of fertilizer application and inoculation of arbuscular mycorrhizal fungi on the growth attributes of sunflower (Helianthus annuus L. and on soil chemical properties. The experiment was conducted at the Federal University of Rio Grande do Norte, Brazil, using a randomized block design with three replicates in a 4 × 2 factorial arrangement consisting of four treatments in regard to application of organic fertilizer (liquid biofertilizer, cow urine, mineral fertilizer, and unfertilized control and two treatments in regard to arbuscular mycorrhizal fungi (with and without mycorrhizal fungi. The results showed that the physiological attributes of relative growth rate and leaf weight ratio were positively influenced by fertilization, compared to the control treatment, likely brought about by the supply of nutrients from the fertilizers applied. The growth and productivity attributes were positively affected by mycorrhization.

  7. Effect of Group-III precursors on unintentional gallium incorporation during epitaxial growth of InAlN layers by metalorganic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeomoh, E-mail: jkim610@gatech.edu; Ji, Mi-Hee; Detchprohm, Theeradetch [Center for Compound Semiconductors and School of Electrical and Computer Engineering, Georgia Institute of Technology, 777Atlantic Dr. NW, Atlanta, Georgia 30332-0250 (United States); Dupuis, Russell D. [Center for Compound Semiconductors and School of Electrical and Computer Engineering, Georgia Institute of Technology, 777Atlantic Dr. NW, Atlanta, Georgia 30332-0250 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Fischer, Alec M.; Ponce, Fernando A. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); Ryou, Jae-Hyun [Department of Mechanical Engineering, Materials Science and Engineering Program, and Texas Center for Superconductivity at the University of Houston (TcSUH), University of Houston, Houston, Texas 77204-4006 (United States)

    2015-09-28

    Unintentional incorporation of gallium (Ga) in InAlN layers grown with different molar flow rates of Group-III precursors by metalorganic chemical vapor deposition has been experimentally investigated. The Ga mole fraction in the InAl(Ga)N layer was increased significantly with the trimethylindium (TMIn) flow rate, while the trimethylaluminum flow rate controls the Al mole fraction. The evaporation of metallic Ga from the liquid phase eutectic system between the pyrolized In from injected TMIn and pre-deposited metallic Ga was responsible for the Ga auto-incorporation into the InAl(Ga)N layer. The theoretical calculation on the equilibrium vapor pressure of liquid phase Ga and the effective partial pressure of Group-III precursors based on growth parameters used in this study confirms the influence of Group-III precursors on Ga auto-incorporation. More Ga atoms can be evaporated from the liquid phase Ga on the surrounding surfaces in the growth chamber and then significant Ga auto-incorporation can occur due to the high equilibrium vapor pressure of Ga comparable to effective partial pressure of input Group-III precursors during the growth of InAl(Ga)N layer.

  8. Prediction of TiO2 thin film growth on the glass beads in a rotating plasma chemical vapor deposition reactor.

    Science.gov (United States)

    Kim, Dong-Joo; Kim, Kyo-Seon

    2010-05-01

    We calculated the concentration profiles of important chemical species for TiO2 thin film growth on the glass beads in the TTIP + O2 plasmas and compared the predicted growth rates of thin films with the experimental measurements. The film thickness profile depends on the concentration profile of TiO(OC3H7)3 precursors in the gas phase because TiO(OC3H7)3 is the main precursor of the thin film. The TTIP concentration decreases with time, while the TiO(OC3H7)3 concentration increases, and they reach the steady state about 2 approximately 3 sec. The growth rate of TiO2 film predicted in this study was 9.2 nm/min and is in good agreements with the experimental result of 10.5 nm/min under the same process conditions. This study suggests that a uniform TiO2 thin film on particles can be obtained by using a rotating cylindrical PCVD reactor. PMID:20358924

  9. Effect of Group-III precursors on unintentional gallium incorporation during epitaxial growth of InAlN layers by metalorganic chemical vapor deposition

    International Nuclear Information System (INIS)

    Unintentional incorporation of gallium (Ga) in InAlN layers grown with different molar flow rates of Group-III precursors by metalorganic chemical vapor deposition has been experimentally investigated. The Ga mole fraction in the InAl(Ga)N layer was increased significantly with the trimethylindium (TMIn) flow rate, while the trimethylaluminum flow rate controls the Al mole fraction. The evaporation of metallic Ga from the liquid phase eutectic system between the pyrolized In from injected TMIn and pre-deposited metallic Ga was responsible for the Ga auto-incorporation into the InAl(Ga)N layer. The theoretical calculation on the equilibrium vapor pressure of liquid phase Ga and the effective partial pressure of Group-III precursors based on growth parameters used in this study confirms the influence of Group-III precursors on Ga auto-incorporation. More Ga atoms can be evaporated from the liquid phase Ga on the surrounding surfaces in the growth chamber and then significant Ga auto-incorporation can occur due to the high equilibrium vapor pressure of Ga comparable to effective partial pressure of input Group-III precursors during the growth of InAl(Ga)N layer

  10. Effects of humic acid-based buffer + cation on chemical characteristics of saline soils and maize growth

    Directory of Open Access Journals (Sweden)

    W. Mindari

    2014-10-01

    Full Text Available Humic acid is believed to maintain the stability of the soil reaction, adsorption / fixation / chelate of cation, thereby increasing the availability of water and plant nutrients. On the other hand, the dynamics of saline soil cation is strongly influenced by the change of seasons that disrupt water and plant nutrients uptake. This experiment was aimed to examine the characteristics of the humic acid from compost, coal, and peat and its function in the adsorption of K+ and NH4+ cations, thus increasing the availability of nutrients and of maize growth. Eighteen treatments consisted of three humic acid sources (compost, peat and coal, two cation additives (K+ and NH4+, and three doses of humic acid-based buffer (10, 20, and 30 g / 3kg, were arranged in a factorial completely randomized with three replicates. The treatments were evaluated against changes in pH, electric conductivity (EC, cation exchange capacity (CEC, chlorophyll content, plant dry weight and plant height. The results showed that the addition of K+ and NH4+ affected pH, CEC, K+, NH4+, and water content of the buffer. Application of humic acid-based buffer significantly decreased soil pH from > 7 to about 6.3, decreased soil EC to 0.9 mS / cm, and increased exchangeable Na from 0.40 to 0.56 me / 100g soil, Ca from 15.57 to 20.21 me/100 g soil, Mg from 1.76 to 6.52 me/100 g soil, and K from 0.05-0.51 me / 100g soil. Plant growth (plant height, chlorophyll content, leaf area, and stem weight at 35 days after planting increased with increasing dose of humic acid. The dose of 2.0g peat humic acid + NH4+ / 3 kg of soil or 30g peat humic acid + K+ / 3 kg of oil gave the best results of maize growth.

  11. Rapidly induced chemical defenses in maize stems and their effects on short-term growth of Ostrinia nubilalis.

    Science.gov (United States)

    Dafoe, Nicole J; Huffaker, Alisa; Vaughan, Martha M; Duehl, Adrian J; Teal, Peter E; Schmelz, Eric A

    2011-09-01

    Plants damaged by insect herbivory often respond by inducing a suite of defenses that can negatively affect an insect's growth and fecundity. Ostrinia nubilalis (European corn borer, ECB) is one of the most devastating insect pests of maize, and in the current study, we examined the early biochemical changes that occur in maize stems in response to ECB herbivory and how these rapidly induced defenses influence the growth of ECB. We measured the quantities of known maize defense compounds, benzoxazinoids and the kauralexin class of diterpenoid phytoalexins. ECB herbivory resulted in decreased levels of the benzoxazinoid, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one)-β-D-glucopyranose (DIMBOA-Glc), and a corresponding increase in 2-(2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one)-β-D-glucopyranose (HDMBOA-Glc). Total quantities of benzoxazinoids and kauralexins were increased as early as 24 h after the initiation of ECB feeding. The plant hormones, jasmonic acid (JA) and ethylene (ET), and the transcripts encoding their key biosynthetic enzymes also accumulated in response to ECB herbivory, consistent with a role in defense regulation. The combined pharmacological application of JA and the ET precursor, 1-aminocyclopropane-1-carboxylic acid to stem internode tissue likewise resulted in changes in benzoxazinoids similar to that observed with ECB damage. Despite the fact that maize actively mounts a defense response to ECB stem feeding, no differences in percent weight gain were observed between ECB larvae that fed upon non-wounded control tissues compared to tissues obtained from plants previously subjected to 24 h ECB stem herbivory. These rapid defense responses in maize stems do not appear to negatively impact ECB growth, thus suggesting that ECB have adapted to these induced biochemical changes. PMID:21833765

  12. Effects of Dietary Vitamin C Supplementation on Growth Performance and Tissue Chemical Composition of Silurus Glanis (Linnaeus, 1578)

    OpenAIRE

    Sandita (Placinta) Ion; Victor Cristea; Mirela Mocanu; Alina Antache; Marian Tiberiu Coadă; Stefan Mihai Petrea

    2012-01-01

    The present study was conducted to quantify the effect of Ascorbic acid (Vitamin C) at the following inclusion levels: 0 mg AA per kg feed (V0), 50 mg AA per kg feed (V1), 100 mg AA per kg feed (V2) and 150 mg AA per kg of feed (V3), on growth performance and feed utilization efficiency of juvenile Silurus glanis, reared in a recirculating aquaculture system. The European catfish, with initial mean body weight of 118.96±0.43g, was fed with 1.8 percentage of their body weight, 3 times per day....

  13. Hemp raw materials: The effect of cultivar, growth conditions and pretreatment on the chemical composition of the fibres

    DEFF Research Database (Denmark)

    Thomsen, A.B.; Rasmussen, S.K.; Bohn, V.;

    2005-01-01

    Hemp raw materials were analyzed chemically to determine their content of cellulose, hemicellulose, lignin and ashes. Correction for ashes was only necessary in the first step of the chemical analysis: the Neutral Detergent Fibre step. The hemp fiberscontained 73-77% w/w cellulose, 7-9% w....../w hemicellulose and 4-6% w/w lignin, while the hemp shives contained 48% w/w cellulose, 21-25% w/w hemicellulose and 17-19% w/w lignin. Among the four investigated cultivars, Felina contained least lignin, whileFutura and Fasamo contained least cellulose. Hemp yarn had the same color as retted hemp fibers...... but was more cellulose rich. Steam explosion, wet oxidation and hydrothermal treatment were used for defibration of retted hemp fibers. These pretreatmentsremoved lignin and hemicellulose resulting in loss of dry matter of 15-73% w/w and in loss of cellulose of 0-69% w/w. Steam explosion treatment generally...

  14. Influence of chemical and organic fertilizer on growth, yield and essential oil of dragonhead (Dracocephalum moldavica L. plant

    Directory of Open Access Journals (Sweden)

    Mohsen JANMOHAMMADI

    2015-12-01

    Full Text Available Two field experiments were carried out to study the response of Dracocephalum moldavica L. to NPK fertilizer and different application techniques of MOG organic fertilizer in two regions of Iran (Piranshahr with cold Mediterranean climate and clay loam soil,  Maragheh with cool sub-humid temperate climate and sandy loam  soil. MOG is bio-organic fertilizer with plant origin and contains different natural enzymes and amino acids. In current study following treatments have been applied: NPK (a complete NPK 20-20-20, 90 kg fertilizer ha-1; MOG1 (soil application of MOG organic fertilizer at sowing stage; MOG2 (foliar application of MOG organic fertilizer at early stage of flowering; MOG3 (soil application of MOG organic fertilizer at sowing and at 5 to 6 leaf stage; MOG4 (soil application of MOG organic fertilizer at sowing and at 5 to 6 leaf stage with foliar application at early stage of flowering. Results indicated that all MOG treatments overcome the chemical fertilizers in both locations. However, plants grown in Piranshahr were more responsive to MOG fertilizer treatments than those grown in Mragheh. Overall, it could be concluded that utilization of MOG fertilizer as both soil and foliar application (MOG4 may increase content and yield of essential oil, which could be suggested as a suitable alternative for chemical fertilizers.

  15. [Chemical composition of volatile oil from Chromolaena odorata and its effect on plant, fungi and insect growth].

    Science.gov (United States)

    Ling, Bing; Zhang, Maoxin; Kong, Chuihua; Pang, Xiongfei; Liang, Guangwen

    2003-05-01

    The volatile oil from C. odorata had a significant effect on the growth of plants, fungi and insects. The result showed that the seedling growth of five test plants was obviously inhibited, in the order of ryegrass > Chinese cabbage > radish > snap been > rice. The inhibitory effect of the oil at its middle concentration (800 mg.L-1) for Pyricularia grisea was the strongest, the next was to Phytophthora nicotianae, and the weakest was to Fusarium axysporum. The inhibitory percentage was 61.40%, 29.27% and 14.44%, respectively. The volatile oil from C. odorata at the dose of 10-20 microliters.plant-1 had a significant oviposition deterrent effect on Phyllotreta striolata and Plutella xylostella. The volatile oil from C. odorata was analyzed by GC/MS and thirty components were identified. Terpenoids compounds were major components of the volatile oil, such as trans-caryophyllene (16.58%), delta-cadinene (15.85%), alpha-copaene (11.58%), caryophyllene oxide (9.63%), germacrene-D (4.96%), and delta-humulene (4.32%). PMID:12924132

  16. All Chemical Vapor Deposition Growth of MoS2:h-BN Vertical van der Waals Heterostructures.

    Science.gov (United States)

    Wang, Shanshan; Wang, Xiaochen; Warner, Jamie H

    2015-05-26

    Vertical van der Waals heterostructures are formed when different 2D crystals are stacked on top of each other. Improved optical properties arise in semiconducting transition metal dichalcogenide (TMD) 2D materials, such as MoS2, when they are stacked onto the insulating 2D hexagonal boron nitride (h-BN). Most work to date has required mechanical exfoliation of at least one of the TMDs or h-BN materials to form these semiconductor:insulator structures. Here, we report a direct all-CVD process for the fabrication of high-quality monolayer MoS2:h-BN vertical heterostructured films with isolated MoS2 domains distributed across 1 cm. This is enabled by the use of few-layer h-BN films that are more robust against decomposition than monolayer h-BN during the MoS2 growth process. The MoS2 domains exhibit different growth dynamics on the h-BN surfaces compared to bare SiO2, confirming that there is strong interaction between the MoS2 and underlying h-BN. Raman and photoluminescence spectroscopies of CVD-grown MoS2 are compared to transferred MoS2 on both types of substrates, and our results show directly grown MoS2 on h-BN films have smaller lattice strain, lower doping level, cleaner and sharper interfaces, and high-quality interlayer contact. PMID:25895108

  17. Predicting Fecundity of Fathead Minnows (Pimephales promelas) Exposed to Endocrine-Disrupting Chemicals Using a MATLAB®-Based Model of Oocyte Growth Dynamics.

    Science.gov (United States)

    Watanabe, Karen H; Mayo, Michael; Jensen, Kathleen M; Villeneuve, Daniel L; Ankley, Gerald T; Perkins, Edward J

    2016-01-01

    Fish spawning is often used as an integrated measure of reproductive toxicity, and an indicator of aquatic ecosystem health in the context of forecasting potential population-level effects considered important for ecological risk assessment. Consequently, there is a need for flexible, widely-applicable, biologically-based models that can predict changes in fecundity in response to chemical exposures, based on readily measured biochemical endpoints, such as plasma vitellogenin (VTG) concentrations, as input parameters. Herein we describe a MATLAB® version of an oocyte growth dynamics model for fathead minnows (Pimephales promelas) with a graphical user interface based upon a previously published model developed with MCSim software and evaluated with data from fathead minnows exposed to an androgenic chemical, 17β-trenbolone. We extended the evaluation of our new model to include six chemicals that inhibit enzymes involved in steroid biosynthesis: fadrozole, ketoconazole, propiconazole, prochloraz, fenarimol, and trilostane. In addition, for unexposed fathead minnows from group spawning design studies, and those exposed to the six chemicals, we evaluated whether the model is capable of predicting the average number of eggs per spawn and the average number of spawns per female, which was not evaluated previously. The new model is significantly improved in terms of ease of use, platform independence, and utility for providing output in a format that can be used as input into a population dynamics model. Model-predicted minimum and maximum cumulative fecundity over time encompassed the observed data for fadrozole and most propiconazole, prochloraz, fenarimol and trilostane treatments, but did not consistently replicate results from ketoconazole treatments. For average fecundity (eggs•female(-1)•day(-1)), eggs per spawn, and the number of spawns per female, the range of model-predicted values generally encompassed the experimentally observed values. Overall, we

  18. Growth of aligned single-walled carbon nanotubes under ac electric fields through floating catalyst chemical vapour deposition

    Institute of Scientific and Technical Information of China (English)

    Dou Xin-Yuan; Luo Shu-Dong; Zhang Zeng-Xing; Liu Dong-Fang; Wang Jian-Xiong; Gao Yan; Zhou Wei-Ya; Wang Gang; Zhou Zhen-Ping; Tan Ping-Heng; Zhou Jian-Jun; Song Li; Sun Lian-Feng; Jiang Peng; Liu Li-Feng; Zhao Xiao-Wei

    2005-01-01

    Through floating catalyst chemical vapour deposition(CVD) method, well-aligned isolated single-walled carbon nanotubes (SWCNTs) and their bundles were deposited on the metal electrodes patterned on the SiO2/Si surface under ac electric fields at relatively low temperature(280℃). It was indicated that SWCNTs were effectively aligned under ac electric fields after they had just grown in the furnace. The time for a SWCNT to be aligned in the electric field and the effect of gas flow were estimated. Polarized Raman scattering was performed to characterize the aligned structure of SWCNTs. This method would be very useful for the controlled fabrication and preparation of SWCNTs in practical applications.

  19. Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

    Institute of Scientific and Technical Information of China (English)

    XU Qiu-jin; NIAN Yue-gang; JIN Xiang-can; YAN Chang-zhou; LIU Jin; Jiang Gao-ming

    2007-01-01

    Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. verticillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.

  20. Resonant and nonresonant vibrational excitation of ammonia molecules in the growth of gallium nitride using laser-assisted metal organic chemical vapour deposition

    Science.gov (United States)

    Golgir, Hossein Rabiee; Zhou, Yun Shen; Li, Dawei; Keramatnejad, Kamran; Xiong, Wei; Wang, Mengmeng; Jiang, Li Jia; Huang, Xi; Jiang, Lan; Silvain, Jean Francois; Lu, Yong Feng

    2016-09-01

    The influence of exciting ammonia (NH3) molecular vibration in the growth of gallium nitride (GaN) was investigated by using an infrared laser-assisted metal organic chemical vapor deposition method. A wavelength tunable CO2 laser was used to selectively excite the individual vibrational modes. Resonantly exciting the NH-wagging mode (v2) of NH3 molecules at 9.219 μm led to a GaN growth rate of 84 μm/h, which is much higher than the reported results. The difference between the resonantly excited and conventional thermally populated vibrational states was studied via resonant and nonresonant vibrational excitations of NH3 molecules. Resonant excitation of various vibrational modes was achieved at 9.219, 10.35, and 10.719 μm, respectively. Nonresonant excitation was conducted at 9.201 and 10.591 μm, similar to conventional thermal heating. Compared to nonresonant excitation, resonant excitation noticeably promotes the GaN growth rate and crystalline quality. The full width at half maximum value of the XRD rocking curves of the GaN (0002) and GaN (10-12) diffraction peaks decreased at resonant depositions and reached its minimum value of 45 and 53 arcmin, respectively, at the laser wavelength of 9.219 μm. According to the optical emission spectroscopic studies, resonantly exciting the NH3 v2 mode leads to NH3 decomposition at room temperature, reduces the formation of the TMGa:NH3 adduct, promotes the supply of active species in GaN formation, and, therefore, results in the increased GaN growth rate.