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Sample records for aqueous environment revealed

  1. Fabrication and characterization of ultrathin dextran layers: Time dependent nanostructure in aqueous environments revealed by OWLS.

    Science.gov (United States)

    Saftics, Andras; Kurunczi, Sándor; Szekrényes, Zsolt; Kamarás, Katalin; Khánh, Nguyen Quoc; Sulyok, Attila; Bősze, Szilvia; Horvath, Robert

    2016-10-01

    Surface coatings of the polysaccharide dextran and its derivatives are key ingredients especially in label-free biosensors for the suppression of non-specific binding and for receptor immobilization. Nevertheless, the nanostructure of these ultrathin coatings and its tailoring by the variation of the preparation conditions have not been profoundly characterized and understood. In this work carboxymethylated dextran (CMD) was prepared and used for fabricating ultrathin surface coatings. A grafting method based on covalent coupling to aminosilane- and epoxysilane-functionalized surfaces was applied to obtain thin CMD layers. The carboxyl moiety of the CMD was coupled to the aminated surface by EDC-NHS reagents, while CMD coupling through epoxysilane molecules was performed without any additional reagents. The surface analysis following the grafting procedures consisted of X-ray photoelectron spectroscopy (XPS), attenuated total reflection infrared spectroscopy (ATR-IR), spectroscopic ellipsometry, atomic force microscopy (AFM) and optical waveguide lightmode spectroscopy (OWLS). The XPS and AFM measurements showed that the grafting resulted in a very thin dextran layer of a few nanometers. The OWLS method allowed devising the structure of the interfacial dextran layers by the evaluation of the optogeometrical parameters. The alteration in the nanostructure of the CMD layer with the chemical composition of the silane coverage and the pH of the grafting solution was revealed by in situ OWLS, specifically, lain down chains were found to be prevalent on the surface under neutral and basic conditions on epoxysilylated surfaces. The developed methodologies allowed to design and fabricate nanometer scale CMD layers with well-controlled surface structure, which are very difficult to characterize in aqueous environments using present instrumentations and highly hydrated surface layers. PMID:27455406

  2. Selective plasmon-driven catalysis for para-nitroaniline in aqueous environments

    Science.gov (United States)

    Cui, Lin; Wang, Peijie; Li, Yuanzuo; Sun, Mengtao

    2016-02-01

    The plasmon-driven oxidation of amine (-NH2) groups and the reduction of nitro (-NO2) groups on a nanostructured metal surface in an aqueous environment have been reported experimentally and theoretically. The question of which process occurs first in the aqueous environment is an interesting question in the field of plasmon-related photochemistry. Para-nitroaniline (PNA), with both nitro (-NO2) and amine (-NH2) groups, is the best candidate for studying the priority of the plasmon-driven oxidation and the reduction reactions in an aqueous environment. Using surface-enhanced Raman scattering (SERS) spectroscopy, our experimental results and theoretical simulations reveal that PNA is selectively catalyzed to 4,4‧-diaminoazobenzene (DAAB) through the plasmon-assisted dimerization of the nitro (-NO2) group into an azo group in an aqueous environment. This indicates that the plasmon-driven reduction of the nitro (-NO2) group clearly occurs before the oxidation of the amine (-NH2) group in an aqueous environment. The plasmon-driven reduction of PNA to DAAB is a selective surface catalytic reduced reaction in aqueous environment.

  3. DESIGN OF ROBOTIC COLONIZER CONTROL SYSTEM FOR AQUEOUS ENVIRONMENT

    OpenAIRE

    C Venkatesh; C.CHANDRA SEKHAR

    2013-01-01

    Now a days there is a huge interest on underwater communication systems for various applications in order to explore aqueous environments. Intelligent robots and cooperative multi- agent robotic systems can be very efficient tools to speed up search and research operations in remote areas. Robots are also useful to do jobs inareas and in situations that are hazardous for human, they can go anywhere that is not reachable my humans and can go into gaps and move trough small holes that are impos...

  4. Proton NMR studies of functionalized nanoparticles in aqueous environments

    Science.gov (United States)

    Tataurova, Yulia Nikolaevna

    Nanoscience is an emerging field that can provide potential routes towards addressing critical issues such as clean and sustainable energy, environmental remediation and human health. Specifically, porous nanomaterials, such as zeolites and mesoporous silica, are found in a wide range of applications including catalysis, drug delivery, imaging, environmental protection, and sensing. The characterization of the physical and chemical properties of nanocrystalline materials is essential to the realization of these innovative applications. The great advantage of porous nanocrystals is their increased external surface area that can control their biological, chemical and catalytic activities. Specific functional groups synthesized on the surface of nanoparticles are able to absorb heavy metals from the solution or target disease cells, such as cancer cells. In these studies, three main issues related to functionalized nanomaterials will be addressed through the application of nuclear magnetic resonance (NMR) techniques including: 1) surface composition and structure of functionalized nanocrystalline particles; 2) chemical properties of the guest molecules on the surface of nanomaterials, and 3) adsorption and reactivity of surface bound functional groups. Nuclear magnetic resonance (NMR) is one of the major spectroscopic techniques available for the characterization of molecular structure and conformational dynamics with atomic level detail. This thesis deals with the application of 1H solution state NMR to porous nanomaterial in an aqueous environment. Understanding the aqueous phase behavior of functionalized nanomaterials is a key factor in the design and development of safe nanomaterials because their interactions with living systems are always mediated through the aqueous phase. This is often due to a lack of fundamental knowledge in interfacial chemical and physical phenomena that occur on the surface of nanoparticles. The use of solution NMR spectroscopy results

  5. DESIGN OF ROBOTIC COLONIZER CONTROL SYSTEM FOR AQUEOUS ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    C.VENKATESH

    2013-05-01

    Full Text Available Now a days there is a huge interest on underwater communication systems for various applications in order to explore aqueous environments. Intelligent robots and cooperative multi- agent robotic systems can be very efficient tools to speed up search and research operations in remote areas. Robots are also useful to do jobs inareas and in situations that are hazardous for human, they can go anywhere that is not reachable my humans and can go into gaps and move trough small holes that are impossible for humans and even trained dogs. in this paper, a wireless underwater mobile robot system is designed in order to study the behavior of artemia group. anew idea has been presented for underwater mobile robot system which is consists of two parts, first is the underwater mechanical robot and the second is ZigBee wireless based mobile robot which controls and moves the first part. by this system different patterns motion control (linear, circular, zigzag, etc. has been performed and proved the ability to control group of robot by controlling the group of artemia and monitoring the underwater mobile robot control with the help of water proof RF wireless camera and also explore the details present around the mobile robot

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

    Energy Technology Data Exchange (ETDEWEB)

    Maity, D. [Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Agrawal, D.C. [Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016 (India)]. E-mail: agrwald@iitk.ac.in

    2007-01-15

    Synthesis of magnetite (Fe{sub 3}O{sub 4}) nanoparticles under oxidizing environment by precipitation from aqueous media is not straightforward because Fe{sup 2+} gets oxidized to Fe{sup 3+} and thus the ratio of Fe{sup 3+}:Fe{sup 2+}=2:1 is not maintained during the precipitation. A molar ratio of Fe{sup 3+}:Fe{sup 2+} smaller than 2:1 has been used by many to compensate for the oxidation of Fe{sup 2+} during the preparation. In this work, we have prepared iron oxide nanoparticles in air environment by the precipitation technique using initial molar ratios Fe{sup 3+}:Fe{sup 2+}{<=}2:1. The phases of the resulting powders have been determined by several techniques. It is found that the particles consist mainly of maghemite with little or no magnetite phase. The particles have been suspended in non-aqueous and aqueous media by coating the particles with a single layer and a bilayer of oleic acid, respectively. The particle sizes, morphology and the magnetic properties of the particles and the ferrofulids prepared from these particles are reported. The average particle sizes obtained from the TEM micrographs are 14, 10 and 9 nm for the water, kerosene and dodecane-based ferrofluids, respectively, indicating a better dispersion in the non-aqueous media. The specific saturation magnetization ({sigma}{sub s}) value of the oleic-acid-coated particles ({approx}53 emu/g) is found to be lower than that for the uncoated particles ({approx}63 emu/g). Magnetization {sigma}{sub s} of the dodecane-based ferrofluid is found to be 10.1 emu/g for a volume fraction of particles {phi}=0.019. Zero coercivity and zero remanance on the magnetization curves indicate that the particles are superparamagnetic (SPM) in nat0009u.

  7. Creating Nanoscale Pits on Solid Surfaces in Aqueous Environment with Scanning Tunnelling Microscopy

    DEFF Research Database (Denmark)

    Chi, Qijin; Zhang, Jingdong; Friis, Esben P.;

    2000-01-01

    A novel method has been developed to fabricate nanoscale pits on Au(111) in aqueous environments by in situ scanning tunnelling microscopy (STM), based on critical interactions between tip and substrate. The most striking advantages of the present method are that the dimension and position of the...... pits can be controlled well in aqueous environments, and the operations are simple. Parameters affecting the pit formation and size have been systematically characterized to show that pit formation is dominated by bias voltage. A mechanism is proposed based on local surface reconstruction induced by...

  8. Controlling wear failure of graphite-like carbon film in aqueous environment: Two feasible approaches

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yongxin [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Science, Lanzhou 730000 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Wang Liping, E-mail: lpwang@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Science, Lanzhou 730000 (China); Xue Qunji [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Science, Lanzhou 730000 (China)

    2011-02-15

    Friction and wear behaviors of graphite-like carbon (GLC) films in aqueous environment were investigated by a reciprocating sliding tribo-meter with ball-on-disc contact. Film structures and wear scars were studied by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and a non-contact 3D surface profiler. A comprehensive wear model of the GLC film in aqueous environment was established, and two feasible approaches to control critical factor to the corresponding wear failure were discussed. Results showed that wear loss of GLC films in aqueous environment was characterized by micro-plough and local delamination. Due to the significant material loss, local delamination of films was critical to wear failure of GLC film in aqueous environment if the film was not prepared properly. The initiation and propagation of micro-cracks within whole films closely related to the occurrence of the films delamination from the interface between interlayer and substrate. The increase of film density by adjusting the deposition condition would significantly reduce the film delamination from substrate, meanwhile, fabricating a proper interlayer between substrate and GLC films to prevent the penetration of water molecules into the interface between interlayer and substrate could effectively eliminate the delamination.

  9. Stability of artemisinin in aqueous environments : Impact on its cytotoxic action to Ehrlich ascites tumour cells

    NARCIS (Netherlands)

    Beekman, AC; Woerdenbag, HJ; Van Uden, W; Pras, N; Konings, AWT; Wikstrom, HV

    1997-01-01

    We have recently shown artemisinin to be cytotoxic against Ehrlich ascites tumour cells. The aim of this study was to investigate the stability of this compound in the aqueous environment of the in-vitro Ehrlich ascites tumour cell system (RPMI 1640 cell culture medium supplemented with 10% foetal b

  10. Stability studies of CdSe nanocrystals in an aqueous environment

    DEFF Research Database (Denmark)

    Xi, Lifei; Lek, Jun Yan; Liang, Yen Nan;

    2011-01-01

    -generated holes oxidize CdSe to Cd2 + and elemental Se. The dissolution was accelerated in an acidic medium while moderate alkalinity (pH = 10.3) can slow down the dissolution possibly due to precipitation of nanocrystals. This study has strong implications for the use of these crystals in aqueous environments...

  11. Stability of titania nanotube arrays in aqueous environment and the related factors

    OpenAIRE

    Can Cao; Jun Yan; Yumei Zhang; Lingzhou Zhao

    2016-01-01

    Titania nanotube arrays (NTAs) on titanium (Ti) fabricated by electrochemical anodization have attracted tremendous interest for diverse applications, of which most perform in aqueous environment or related to interaction with water. The NTAs are widely studied however the related factor of stability of NTAs when applied in such environment has rarely been concerned. We report that the annealed anatase NTAs are stable but the non-annealed amorphous NTAs are unstable to undergo specific struct...

  12. Mid-Infrared Sensing of Organic Pollutants in Aqueous Environments

    Directory of Open Access Journals (Sweden)

    Andrew Ross

    2009-08-01

    Full Text Available The development of chemical sensors for monitoring the levels of organic pollutants in the aquatic environment has received a great deal of attention in recent decades. In particular, the mid-infrared (MIR sensor based on attenuated total reflectance (ATR is a promising analytical tool that has been used to detect a variety of hydrocarbon compounds (i.e., aromatics, alkyl halides, phenols, etc. dissolved in water. It has been shown that under certain conditions the MIR-ATR sensor is capable of achieving detection limits in the 10-100 ppb concentration range. Since the infrared spectral features of every single organic molecule are unique, the sensor is highly selective, making it possible to distinguish between many different analytes simultaneously. This review paper discusses some of the parameters (i.e., membrane type, film thickness, conditioning that dictate MIR ATR sensor response. The performance of various chemoselective membranes which are used in the fabrication of the sensor will be evaluated. Some of the challenges associated with long-term environmental monitoring are also discussed.

  13. Prevalence and sunlight photolysis of controlled and chemotherapeutic drugs in aqueous environments

    International Nuclear Information System (INIS)

    This study addresses the occurrences and natural fates of chemotherapeutics and controlled drugs when found together in hospital effluents and surface waters. The results revealed the presence of 11 out of 16 drugs in hospital effluents, and the maximum detected concentrations were at the μg L−1 level in the hospital effluents and the ng L−1 level in surface waters. The highest concentrations corresponded to meperidine, morphine, 5-fluorouracil and cyclophosphamide. The sunlight photolysis of the target compounds was investigated, and the results indicated that morphine and codeine can be significantly attenuated, with half-lives of 0.27 and 2.5 h, respectively, in natural waters. Photolysis can lower the detected environmental concentrations, also lowering the estimated environmental risks of the target drugs to human health. Nevertheless, 5-fluorouracil and codeine were found to have a high risk quotient (RQ), demonstrating the high risks of directly releasing hospital wastewater into the environment. - Highlights: • High occurrence of chemotherapeutics and controlled substances in aqueous systems. • Photolysis lowers the detected concentrations of morphine and codeine. • 5-fluorouracil and codeine in hospital effluents have high risk quotients. - Chemotherapeutics and controlled drugs occur at significant levels in hospital effluents and surface waters. Natural sunlight photolysis reduces their environmental occurrence

  14. Environmental barcoding reveals massive dinoflagellate diversity in marine environments.

    Directory of Open Access Journals (Sweden)

    Rowena F Stern

    Full Text Available BACKGROUND: Dinoflagellates are an ecologically important group of protists with important functions as primary producers, coral symbionts and in toxic red tides. Although widely studied, the natural diversity of dinoflagellates is not well known. DNA barcoding has been utilized successfully for many protist groups. We used this approach to systematically sample known "species", as a reference to measure the natural diversity in three marine environments. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we assembled a large cytochrome c oxidase 1 (COI barcode database from 8 public algal culture collections plus 3 private collections worldwide resulting in 336 individual barcodes linked to specific cultures. We demonstrate that COI can identify to the species level in 15 dinoflagellate genera, generally in agreement with existing species names. Exceptions were found in species belonging to genera that were generally already known to be taxonomically challenging, such as Alexandrium or Symbiodinium. Using this barcode database as a baseline for cultured dinoflagellate diversity, we investigated the natural diversity in three diverse marine environments (Northeast Pacific, Northwest Atlantic, and Caribbean, including an evaluation of single-cell barcoding to identify uncultivated groups. From all three environments, the great majority of barcodes were not represented by any known cultured dinoflagellate, and we also observed an explosion in the diversity of genera that previously contained a modest number of known species, belonging to Kareniaceae. In total, 91.5% of non-identical environmental barcodes represent distinct species, but only 51 out of 603 unique environmental barcodes could be linked to cultured species using a conservative cut-off based on distances between cultured species. CONCLUSIONS/SIGNIFICANCE: COI barcoding was successful in identifying species from 70% of cultured genera. When applied to environmental samples, it revealed a

  15. Spectroelectrochemical photoluminescence of titanium dioxide nanosheets and nanoparticles in aqueous and nonaqueous environments

    Science.gov (United States)

    Rex, Riley E.; Knorr, Fritz J.; McHale, Jeanne L.

    2014-09-01

    Spectroelectrochemical photoluminescence (SEPL) is used to investigate surface electron and hole traps on anatase nanoparticles, anatase nanosheets and rutile nanowires in aqueous and nonaqueous environments. In aqueous environment there is an overvoltage for occupying surface electron traps in rutile and anatase samples. For anatase, this overvoltage is larger on (101) nanoparticles than on (001) nanosheets. The electrochemical energy levels of electron traps determined by SEPL in acetonitrile are consistent with emitted photon energies as determined by the photoluminescence spectrum. Our results show how the contacting solvent and particle morphology can influence the redox potential of surface electron traps and thus guide further research on improving the performance of nano- TiO2 in applications such as dye-sensitized solar cells and solar water splitting.

  16. Crystallization of Probucol in Nanoparticles Revealed by AFM Analysis in Aqueous Solution.

    Science.gov (United States)

    Egami, Kiichi; Higashi, Kenjirou; Yamamoto, Keiji; Moribe, Kunikazu

    2015-08-01

    The crystallization behavior of a pharmaceutical drug in nanoparticles was directly evaluated by atomic force microscopy (AFM) force curve measurements in aqueous solution. A ternary spray-dried sample (SPD) was prepared by spray drying the organic solvent containing probucol (PBC), hypromellose (HPMC), and sodium dodecyl sulfate (SDS). The amorphization of PBC in the ternary SPD was confirmed by powder X-ray diffraction (PXRD) and solid-state 13C NMR measurements. A nanosuspension containing quite small particles of 25 nm in size was successfully prepared immediately after dispersion of the ternary SPD into water. Furthermore, solution-state 1H NMR measurements revealed that a portion of HPMC coexisted with PBC as a mixed state in the freshly prepared nanosuspension particles. After storing the nanosuspension at 25 °C, a gradual increase in the size of the nanoparticles was observed, and the particle size changed to 93.9 nm after 7 days. AFM enabled the direct observation of the morphology and agglomeration behavior of the nanoparticles in water. Moreover, AFM force-distance curves were changed from (I) to (IV), depending on the storage period, as follows: (I) complete indentation within an applied force of 1 nN, (II) complete indentation with an applied force of 1-5 nN, (III) partial indentation with an applied force of 5 nN, and (IV) nearly no indentation with an applied force of 5 nN. This stiffness increase of the nanoparticles was attributed to gradual changes in the molecular state of PBC from the amorphous to the crystal state. Solid-state 13C NMR measurements of the freeze-dried samples demonstrated the presence of metastable PBC Form II crystals in the stored nanosuspension, strongly supporting the AFM results. PMID:26106951

  17. Enhancement of hybridoma formation, clonability and cell proliferation in a nanoparticle-doped aqueous environment

    Directory of Open Access Journals (Sweden)

    Karnieli Ohad

    2008-01-01

    Full Text Available Abstract Background The isolation and production of human monoclonal antibodies is becoming an increasingly important pursuit as biopharmaceutical companies migrate their drug pipelines away from small organic molecules. As such, optimization of monoclonal antibody technologies is important, as this is becoming the new rate-limiting step for discovery and development of new pharmaceuticals. The major limitations of this system are the efficiency of isolating hybridoma clones, the process of stabilizing these clones and optimization of hybridoma cell secretion, especially for large-scale production. Many previous studies have demonstrated how perturbations in the aqueous environment can impact upon cell biology. In particular, radio frequency (RF irradiation of solutions can have dramatic effects on behavior of solutions, cells and in particular membrane proteins, although this effect decays following removal of the RF. Recently, it was shown that nanoparticle doping of RF irradiated water (NPD water produced a stabilized aqueous medium that maintained the characteristic properties of RF irradiated water for extended periods of time. Therefore, the ordering effect in water of the RF irradiation can now be studied in systems that required prolonged periods for analysis, such as eukaryotic cell culture. Since the formation of hybridoma cells involves the formation of a new membrane, a process that is affected by the surrounding aqueous environment, we tested these nanoparticle doped aqueous media formulations on hybridoma cell production. Results In this study, we tested the entire process of isolation and production of human monoclonal antibodies in NPD water as a means for further enhancing human monoclonal antibody isolation and production. Our results indicate an overall enhancement of hybridoma yield, viability, clonability and secretion. Furthermore, we have demonstrated that immortal cells proliferate faster whereas primary human fibroblasts

  18. Heavy metals removal from aqueous environments by electrocoagulation process- a systematic review.

    Science.gov (United States)

    Bazrafshan, Edris; Mohammadi, Leili; Ansari-Moghaddam, Alireza; Mahvi, Amir Hossein

    2015-01-01

    Heavy metals pollution has become a more serious environmental problem in the last several decades as a result releasing toxic materials into the environment. Various techniques such as physical, chemical, biological, advanced oxidation and electrochemical processes were used for the treatment of domestic, industrial and agricultural effluents. The commonly used conventional biological treatments processes are not only time consuming but also need large operational area. Accordingly, it seems that these methods are not cost-effective for effluent containing toxic elements. Advanced oxidation techniques result in high treatment cost and are generally used to obtain high purity grade water. The chemical coagulation technique is slow and generates large amount of sludge. Electrocoagulation is an electrochemical technique with many applications. This process has recently attracted attention as a potential technique for treating industrial wastewater due to its versatility and environmental compatibility. This process has been applied for the treatment of many kinds of wastewater such as landfill leachate, restaurant, carwash, slaughterhouse, textile, laundry, tannery, petroleum refinery wastewater and for removal of bacteria, arsenic, fluoride, pesticides and heavy metals from aqueous environments. The objective of the present manuscript is to review the potential of electrocoagulation process for the treatment of domestic, industrial and agricultural effluents, especially removal of heavy metals from aqueous environments. About 100 published studies (1977-2016) are reviewed in this paper. It is evident from the literature survey articles that electrocoagulation are the most frequently studied for the treatment of heavy metal wastewater. PMID:26512324

  19. Stability of titania nanotube arrays in aqueous environment and the related factors

    Science.gov (United States)

    Cao, Can; Yan, Jun; Zhang, Yumei; Zhao, Lingzhou

    2016-01-01

    Titania nanotube arrays (NTAs) on titanium (Ti) fabricated by electrochemical anodization have attracted tremendous interest for diverse applications, of which most perform in aqueous environment or related to interaction with water. The NTAs are widely studied however the related factor of stability of NTAs when applied in such environment has rarely been concerned. We report that the annealed anatase NTAs are stable but the non-annealed amorphous NTAs are unstable to undergo specific structural change accompanied with a process of amorphous TiO2 dissolution and anatase TiO2 recrystallization. Quite unexpectedly, the non-annealed NTAs still show good stability without structural change in the cell culture media, possibly due to the presence of inorganics that may interfere with the TiO2 dissolution/redeposition process. The pH value of the aqueous environment is not a determinant factor for the structural change for non-annealed NTAs or not, while the temperature and the existence of F− can accelerate the structural change process. F− may play a very important role in the change process. PMID:26960922

  20. Stability of titania nanotube arrays in aqueous environment and the related factors

    Science.gov (United States)

    Cao, Can; Yan, Jun; Zhang, Yumei; Zhao, Lingzhou

    2016-03-01

    Titania nanotube arrays (NTAs) on titanium (Ti) fabricated by electrochemical anodization have attracted tremendous interest for diverse applications, of which most perform in aqueous environment or related to interaction with water. The NTAs are widely studied however the related factor of stability of NTAs when applied in such environment has rarely been concerned. We report that the annealed anatase NTAs are stable but the non-annealed amorphous NTAs are unstable to undergo specific structural change accompanied with a process of amorphous TiO2 dissolution and anatase TiO2 recrystallization. Quite unexpectedly, the non-annealed NTAs still show good stability without structural change in the cell culture media, possibly due to the presence of inorganics that may interfere with the TiO2 dissolution/redeposition process. The pH value of the aqueous environment is not a determinant factor for the structural change for non-annealed NTAs or not, while the temperature and the existence of F‑ can accelerate the structural change process. F‑ may play a very important role in the change process.

  1. Stress Corrosion Cracking of ferrito-pearlitic steel in aqueous environment containing dissolved CO2

    OpenAIRE

    Vancostenoble, Alix; Duret-Thual, C.; Bosch, Cédric; Delafosse, David

    2014-01-01

    A confined aqueous environment is defined by a very low water-volume to exposed steel-area ratio. In such media containing dissolved CO2, siderite is formed and acts as a protective film. An addition of applied stress and/or environmental fluctuation can disturb the balance between the steel and this protective film, causing the fracture of the latter and leading to Stress Corrosion Cracking (SCC). The material studied is a cold drawn and rolled high strength steel composed of ferrite and sph...

  2. Robust magnetic/polymer hybrid nanoparticles designed for crude oil entrapment and recovery in aqueous environments.

    Science.gov (United States)

    Pavía-Sanders, Adriana; Zhang, Shiyi; Flores, Jeniree A; Sanders, Jonathan E; Raymond, Jeffery E; Wooley, Karen L

    2013-09-24

    Well-defined, magnetic shell cross-linked knedel-like nanoparticles (MSCKs) with hydrodynamic diameters ca. 70 nm were constructed through the co-assembly of amphiphilic block copolymers of PAA20-b-PS280 and oleic acid-stabilized magnetic iron oxide nanoparticles using tetrahydrofuran, N,N-dimethylformamide, and water, ultimately transitioning to a fully aqueous system. These hybrid nanomaterials were designed for application as sequestering agents for hydrocarbons present in crude oil, based upon their combination of amphiphilic organic domains, for aqueous solution dispersibility and capture of hydrophobic guest molecules, with inorganic core particles for magnetic responsivity. The employment of these MSCKs in a contaminated aqueous environment resulted in the successful removal of the hydrophobic contaminants at a ratio of 10 mg of oil per 1 mg of MSCK. Once loaded, the crude oil-sorbed nanoparticles were easily isolated via the introduction of an external magnetic field. The recovery and reusability of these MSCKs were also investigated. These results suggest that deployment of hybrid nanocomposites, such as these, could aid in environmental remediation efforts, including at oil spill sites, in particular, following the bulk recovery phase. PMID:23987122

  3. Contact corrosion of aluminum and its alloys in aqueous environment of nuclear facilities

    International Nuclear Information System (INIS)

    The paper presents processes occurring during contact corrosion of structural materials of nuclear facilities, namely aluminium, its alloy SAV-1 with zirconium alloy E110 and stainless steel Cr18ni10ti. The results of electrochemical and autoclave testing of examined contact pairs showed that in all cases the anode is aluminum (or SAV-1), which oxidizes more intensively in comparison with E110 and Cr18ni10ti. During of aluminum and SAV-1 oxidation in an aqueous environment, corrosion products dissolve in the corrosion environment. Pre- oxidation of cathode material (E110) to oxide film thickness 1-1.5 microns virtually eliminates galvanic corrosion component of SAV-1 in the contact pair with E110, which is confirmed by the measurement results of corrosion current density and other indicators characterizing the reliability of the elements and safety of the entire facility

  4. Effects of Linear Alkylbenzene Sulfonate on Aggregation Behaviors of Titanium Dioxide Nanoparticles in Aqueous Environment

    Institute of Scientific and Technical Information of China (English)

    Xiuheng Wang

    2015-01-01

    In aqueous environment, organic matters may exert impacts on the aggregation behaviors of titanium dioxide nanoparticles ( TiO2⁃NPs). Owing to the deficiency of studies on the aggregation of TiO2⁃NPs in the presence of synthetic organic compound, this study used linear alkylbenzene sulfonate ( LAS) as a representative to evaluate the effects of TiO2⁃NPs concentration (1⁃10 mg/L), LAS concentration (0-1 mg/L), pH (4-8) and ionic strength ( NaCl, CaCl2; 5-20 mM ) during aggregation of TiO2⁃NPs suspensions based on the detection of hydrodynamic diameters and electrophoretic mobilities and the calculation of interaction energies. The results showed that the TiO2⁃NPs in the presence of LAS are more stable than that in the absence of LAS. With the increase of ionic strength, the hydrodynamic diameter of NPs decreases, and the existence of LAS changes the point of zero charge from 5�4 to a lower value and thus alteres the aggregation behaviors of TiO2⁃NPs. The present study suggests that the LAS has a significant impact to the transportation and transformation of nanoparticles in aqueous environment.

  5. Environmental Barcoding Reveals Massive Dinoflagellate Diversity in Marine Environments

    Czech Academy of Sciences Publication Activity Database

    Stern, R. F.; Horák, Aleš; Andrew, R. L.; Coffroth, M. A.; Andersen, R. A.; Kupper, F. C.; Jameson, I.; Hoppenrath, M.; Véron, B.; Kasai, F.; Brand, J.; James, E. R.; Keeling, P. J.

    2010-01-01

    Roč. 5, č. 11 (2010), e13991. E-ISSN 1932-6203 Keywords : RIBOSOMAL-RNA GENE * FREE-LIVING STRAIN * SP-NOV DINOPHYCEAE * TOXIC DINOFLAGELLATE * MOLECULAR PHYLOGENY * COASTAL WATERS * NATURAL-ENVIRONMENT * RDNA SEQUENCES * SYMBIODINIUM Impact factor: 4.411, year: 2010

  6. Corrosion behavior of technetium waste forms exposed to various aqueous environments

    Energy Technology Data Exchange (ETDEWEB)

    Kolman, David Gary [Los Alamos National Laboratory; Jarvinen, Gordon [Los Alamos National Laboratory; Mausolf, Edward [UNIV OF NEVADA; Czerwinski, Ken [UNIV OF NEVADA; Poineau, Frederic [UNIV OF NEVADA

    2009-01-01

    Technetium is a long-lived beta emitter produced in high yields from uranium as a waste product in spent nuclear fuel and has a high degree of environmental mobility as pertechnetate. It has been proposed that Tc be immobilized into various metallic waste forms to prevent Tc mobility while producing a material that can withstand corrosion exposed to various aqueous medias to prevent the leachability of Tc to the environment over long periods of time. This study investigates the corrosion behavior of Tc and Tc alloyed with 316 stainless steel and Zr exposed to a variety of aqueous media. To date, there is little investigative work related to Tc corrosion behavior and less related to potential Tc containing waste forms. Results indicate that immobilizing Tc into stainless steel-zirconium alloys can be a promising technique to store Tc for long periods of time while reducing the need to separately store used nuclear fuel cladding. Initial results indicate that metallic Tc and its alloys actively corrode in all media. We present preliminary corrosion rates of 100% Tc, 10% Tc - 90% SS{sub 85%}Zr{sub 15%}, and 2% Tc - 98% SS{sub 85%}Zr{sub 15%} in varying concentrations of nitric acid and pH 10 NaOH using the resistance polarization method while observing the trend that higher concentrations of Tc alloyed to the sample tested lowers the corrosion rate of the proposed waste package.

  7. Optimization of liquid scintillation measurements applied to smears and aqueous samples collected in industrial environments

    Science.gov (United States)

    Chapon, Arnaud; Pigrée, Gilbert; Putmans, Valérie; Rogel, Gwendal

    Search for low-energy β contaminations in industrial environments requires using Liquid Scintillation Counting. This indirect measurement method supposes a fine control from sampling to measurement itself. Thus, in this paper, we focus on the definition of a measurement method, as generic as possible, for both smears and aqueous samples' characterization. That includes choice of consumables, sampling methods, optimization of counting parameters and definition of energy windows, using the maximization of a Figure of Merit. Detection limits are then calculated considering these optimized parameters. For this purpose, we used PerkinElmer Tri-Carb counters. Nevertheless, except those relative to some parameters specific to PerkinElmer, most of the results presented here can be extended to other counters.

  8. Investigation of oxide film formation on 316L stainless steel in high-temperature aqueous environments

    International Nuclear Information System (INIS)

    Highlights: → Oxide films formed in high temperature and high pressure aqueous environment (250 deg. C and 7 MPa) is much thicker than air-formed films (25 deg. C). → Oxide films formed at 250 deg. C have higher charge transfer resistance and smaller passive current density than air-formed films. → Fe exists in the form of FeO, Fe2O3 and FeOOH, Cr of Cr2O3, Cr(OH)3 and CrO3 and Ni of Ni(OH)2 in oxide films formed at 250 deg. C. - Abstract: Oxide films were grown on the surface of 316L stainless steel subjected to high temperatures and a high-pressure aqueous environment (250 deg. C and 7 MPa). The morphology, chemical compositions and corrosion properties of oxide films were investigated by scanning electron microscopy (SEM), auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. The results indicated that oxide films formed at 250 deg. C were more corrosion resistant and thicker than were oxide films formed in air at room temperature (25 deg. C). These distinctions are correlated with the structure and chemical compositions of oxide films. It was found that both films contained a double-layer structure comprised of mixed iron-nickel oxides and chromium oxides. Iron was present as FeO, Fe2O3 and FeOOH; Cr was present as Cr2O3, Cr(OH)3 and CrO3; and Ni existed as Ni(OH)2 within the oxide films formed at 250 deg. C.

  9. Optical characterization of ultrasmall, hydrogen-terminated and carboxyl-functionalized silicon nanoparticles in aqueous environments

    Science.gov (United States)

    Eckhoff, Dean Alan

    The primary theme of this dissertation is to characterize the optical and chemical properties of ultrasmall (˜1 nm) silicon nanoparticles (Si-np) in aqueous environments, focusing on their potential for use as luminescent markers in biophysical and biological applications. Two systems are presented in detail: hydrogen-terminated Si-np prepared through electrochemical dispersion of a crystalline Si wafer and carboxyl-functionalized Si-np prepared via thermal hydrosilylation of surface Si-H bonds with an o-ester 1-alkene. Chemical and physical characterizations are done using nuclear magnetic resonance, size exclusion chromatography, and infrared spectroscopy. Optical characterization is done via absorption and steady-state photoluminescence (PL) and using capillary electrophoresis coupled with laser-induced fluorescence detection. The behavior of the hydrogen-terminated Si-np is studied over time as-prepared in isopropanol and during treatments with water, NaOH, HCl, and H2O 2. The PL spectra show three distinct, near-Gaussian states with a FWHM ˜0.45 eV and their respective emissions in the UV-B (˜305 nm), UV-A (˜340 nm), and 'hard-blue' (˜400 nm) regions of the spectrum. The 'hard-blue' emission is shown to have a simple pH dependence with a pKa ˜3, demonstrating the possibility of using Si-np as environmental probes. These results offer some promise for tailoring the PL properties of ultrasmall Si-np through control of their surface chemistry. In the second part, three central elements establish that the carboxyl-functionalized Si-np have excellent potential for use as a luminescent marker in aqueous systems. First, they are shown to be ultrasmall, with a diameter of ˜1 nm, comparable to that of common organic fluorophores. Second, they are shown to have narrow PL in the near-UV with a nearly-symmetric lineshape and a FWHM as small as 30 nm. Third, it is shown that standard chemical means can be used to functionalize the Si-np with carboxyl groups, giving

  10. Engineered metal based nanomaterials in aqueous environments: Interactions, transformations and implications

    Science.gov (United States)

    Mudunkotuwa, Imali Ama

    Nanoscience and nanotechnology offer potential routes towards addressing critical issues such as clean and sustainable energy, environmental protection and human health. Specifically, metal and metal oxide nanomaterials are found in a wide range of applications and therefore hold a greater potential of possible release into the environment or for the human to be exposed. Understanding the aqueous phase behavior of metal and metal oxide nanomaterials is a key factor in the safe design of these materials because their interactions with living systems are always mediated through the aqueous phase. Broadly the transformations in the aqueous phase can be classified as dissolution, aggregation and adsorption which are dependent and linked processes to one another. The complexity of these processes at the liquid-solid interface has therefore been one of the grand challenges that has persisted since the beginning of nanotechnology. Although classical models provide guidance for understanding dissolution and aggregation of nanoparticles in water, there are many uncertainties associated with the recent findings. This is often due to a lack of fundamental knowledge of the surface structure and surface energetics for very small particles. Therefore currently the environmental health and safety studies related to nanomaterials are more focused on understanding the surface chemistry that governs the overall processes in the liquid-solid interfacial region at the molecular level. The metal based nanomaterials focused on in this dissertation include TiO2, ZnO, Cu and CuO. These are among the most heavily used in a number of applications ranging from uses in the construction industry to cosmetic formulation. Therefore they are produced in large scale and have been detected in the environment. There is debate within the scientific community related to their safety as a result of the lack of understanding on the surface interactions that arise from the detailed nature of the surfaces

  11. Environment friendly chemoselective deprotection of acetonides and cleavage of acetals and ketals in aqueous medium without using any catalyst or organic solvent

    Indian Academy of Sciences (India)

    S Mukherjee; A Sengupta; S C Roy

    2013-11-01

    Highly chemoselective environment friendly deprotection of acetonides and cleavage of acetals and ketones has been achieved by heating in aqueous medium without using any catalyst and organic solvent.

  12. Enhanced stability and dissolution of CuO nanoparticles by extracellular polymeric substances in aqueous environment

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Lingzhan; Wang, Chao; Hou, Jun, E-mail: hhuhjyhj@126.com; Wang, Peifang; Ao, Yanhui; Li, Yi; Lv, Bowen; Yang, Yangyang; You, Guoxiang; Xu, Yi [Hohai University, Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education (China)

    2015-10-15

    Stability of engineered nanoparticles in aquatic environment is an essential parameter to evaluate their fate, bioavailability, and potential toxic effects toward living organisms. As CuO NPs enter the wastewater systems, they will encounter extracellular polymeric substances (EPS) from microbial community before directly interacting with bacterial cells. EPS may play an important role in affecting the stability and the toxicity of CuO NPs in aquatic environment. In this study, the influences of flocculent sludge-derived EPS, as well as model protein (BSA) and natural polysaccharides (alginate) on the dissolution kinetics and colloidal stability of CuO NPs were investigated. Results showed that the presence of NOMs strongly suppressed CuO NPs aggregation, confirmed by DLS, zeta potentials, and TEM analysis. The enhanced stability of CuO NPs in the presence of EPS and alginate were attributed to the electrostatic combined with steric repulsion, while the steric-hindrance effect may be the predominant mechanism retarding nano-CuO aggregation for BSA. Higher degrees of copper release were achieved with the increasing concentrations of NOMs. EPS are more effective than alginate and BSA in releasing copper, probably due to the abundant functional groups and the excellent metal-binding capacity. The ratio of free-Cu{sup 2+}/total dissolved Cu significantly decreased in the presence of EPS, indicating that EPS may affect the speciation and Cu bioavailability in aqueous environment. These results may be important for assessing the fate and transport behaviors of CuO NPs in the environment as well as for setting up usage regulation and treatment strategy.

  13. Enhanced stability and dissolution of CuO nanoparticles by extracellular polymeric substances in aqueous environment

    International Nuclear Information System (INIS)

    Stability of engineered nanoparticles in aquatic environment is an essential parameter to evaluate their fate, bioavailability, and potential toxic effects toward living organisms. As CuO NPs enter the wastewater systems, they will encounter extracellular polymeric substances (EPS) from microbial community before directly interacting with bacterial cells. EPS may play an important role in affecting the stability and the toxicity of CuO NPs in aquatic environment. In this study, the influences of flocculent sludge-derived EPS, as well as model protein (BSA) and natural polysaccharides (alginate) on the dissolution kinetics and colloidal stability of CuO NPs were investigated. Results showed that the presence of NOMs strongly suppressed CuO NPs aggregation, confirmed by DLS, zeta potentials, and TEM analysis. The enhanced stability of CuO NPs in the presence of EPS and alginate were attributed to the electrostatic combined with steric repulsion, while the steric-hindrance effect may be the predominant mechanism retarding nano-CuO aggregation for BSA. Higher degrees of copper release were achieved with the increasing concentrations of NOMs. EPS are more effective than alginate and BSA in releasing copper, probably due to the abundant functional groups and the excellent metal-binding capacity. The ratio of free-Cu2+/total dissolved Cu significantly decreased in the presence of EPS, indicating that EPS may affect the speciation and Cu bioavailability in aqueous environment. These results may be important for assessing the fate and transport behaviors of CuO NPs in the environment as well as for setting up usage regulation and treatment strategy.

  14. Sulphur Kβ emission spectra reveal protonation states of aqueous sulfuric acid

    Science.gov (United States)

    Niskanen, Johannes; Sahle, Christoph J.; Ruotsalainen, Kari O.; Müller, Harald; Kavčič, Matjaž; Žitnik, Matjaž; Bučar, Klemen; Petric, Marko; Hakala, Mikko; Huotari, Simo

    2016-02-01

    In this paper we report an X-ray emission study of bulk aqueous sulfuric acid. Throughout the range of molarities from 1 M to 18 M the sulfur Kβ emission spectra from H2SO4 (aq) depend on the molar fractions and related deprotonation of H2SO4. We compare the experimental results with results from emission spectrum calculations based on atomic structures of single molecules and structures from ab initio molecular dynamics simulations. We show that the S Kβ emission spectrum is a sensitive probe of the protonation state of the acid molecules. Using non-negative matrix factorization we are able to extract the fractions of different protonation states in the spectra, and the results are in good agreement with the simulation for the higher part of the concentration range.

  15. Preparation of Crumpled Graphite Oxide from Recycled Graphite Using Plasma Electrolysis and Its Application for Adsorption of Cadmium in Aqueous Environment

    Science.gov (United States)

    Hong, Phan Ngoc; Tuoi, Tran Thi; Ngan, Nguyen Thi Kim; Trang, Bui Thi; Minh, Phan Ngoc; Lam, Tran Dai; Hanh, Nguyen Thi; Van Thanh, Dang

    2016-05-01

    Household battery waste is considered hazardous and needs to be collected, managed, and recycled appropriately. In this study, using a plasma electrolysis method, we recycled graphite electrodes of exhausted dry batteries to prepare crumpled graphite oxide (CGO). Scanning electron microscopy revealed that the CGO possessed spherical morphology with average dimensions of 0.5 μm to 5 μm. The as-prepared CGO was then applied to absorb cadmium in aqueous environment. The results showed that CGO appears to be a promising adsorbent for removal of toxic waste from polluted water.

  16. Effects of frequency and temperature on short fatigue crack growth in aqueous environments

    Science.gov (United States)

    Nakai, Y.; Alavi, A.; Wei, R. P.

    1988-03-01

    The growth of short fatigue cracks in a NiCrMoV steel forging was examined, under constant applied stress intensity range (ΔK = 31 MPa-m1/2) in deaerated deionized water and 0.3 M Na2SO4 solution, as a function of frequency and temperature. Measurements were also made of the kinetics of electrochemical reactions of bare steel surfaces with the deaerated 0.3 M Na2SO4 solution, under free corrosion, to provide for comparison and correlation. Fatigue crack growth rate increased with reductions in frequency and with increases in temperature. The maximum amount of crack growth enhancement by the different environments appeared to be equal, although the crack growth response in deionized water appeared to be consistent with a faster reaction rate. The temperature and frequency dependence for corrosion fatigue crack growth corresponded directly with that for charge transfer between the “bare” and “filmed” metal surfaces under free corrosion. The results showed that shortcrack growth in the aqueous environments is controlled by the rate of electrochemical reactions, and is thermally activated with an apparent activation energy of about 40 kJ/M.

  17. Novel Method for Breakthrough Removal of Azo Dye from Aqueous Environment Using Integrated Coagulation and Fenton Process

    OpenAIRE

    Sherine Awad; Usama Eldemerdash

    2014-01-01

    Fenton process has proven to be efficient in the removal of color and chemical oxygen demand (COD) from the aqueous environment. However, the environment, health, and economic constraints on the dosage of hydrogen peroxide represent a limitation towards a wide practical use of this approach. In this study, a novel approach is proposed; this includes the treatment with ferrous oxide through coagulation followed by integrated Fenton process. However, the excess ferrous and ferric ions from the ...

  18. Zn/ZnO core/shell nanoparticles synthesized by laser ablation in aqueous environment: Optical and structural characterizations

    Indian Academy of Sciences (India)

    S C Singh; R K Swarnkar; R Gopal

    2010-02-01

    Zn/ZnO core/shell nanoparticles are synthesized by pulsed laser ablation (PLA) of Zn metal plate in the aqueous environment of sodium dodacyl sulfate (SDS). Solution of nanoparticles is found stable in the colloidal form for a long time, and is characterized by UV-visible absorption, transmission electron microscopy (TEM), photoluminescence (PL) and Raman spectroscopic techniques. UV-visible absorption spectrum has four peaks at 231, 275, 356, and 520 nm, which provides primary information about the synthesis of core-shell and elongated nanoparticles. TEM micrographs reveal that synthesized nanoparticles are monodispersed with three different average sizes and size distributions. Colloidal solution of nanoparticles has significant absorption in the green region, therefore, it absorbs 514.7 nm light of Ar+ laser and emits in the blue region centred at 350 and 375 nm, violet at 457 nm and green at 550 nm regions. Raman shift is observed at 300 cm-1 with PL spectrum, which corresponds to ${}^{3}$2N and 3L mode of vibrations of ZnO shell layer. Synthesis mechanism of Zn/ZnO core/shell nanoparticles is discussed.

  19. Effects of aqueous environment on long-term durability of phosphate-bonded ceramic waste forms

    International Nuclear Information System (INIS)

    Over the last few years, Argonne National Laboratory has been developing room-temperature-setting chemically-bonded phosphate ceramics for solidifying and stabilizing low-level mixed wastes. This technology is crucial for stabilizing waste streams that contain volatile species and off-gas secondary waste streams generated by high-temperature treatment of such wastes. Magnesium phosphate ceramic has been developed to treat mixed wastes such as ash, salts, and cement sludges. Waste forms of surrogate waste streams were fabricated by acid-base reactions between the mixtures of magnesium oxide powders and the wastes, and phosphoric acid or acid phosphate solutions. Dense and hard ceramic waste forms are produced in this process. The principal advantage of this technology is that the contaminants are immobilized by both chemical stabilization and subsequent microencapsulation of the reaction products. This paper reports the results of durability studies conducted on waste forms made with ash waste streams spiked with hazardous and radioactive surrogates. Standard leaching tests such as ANS 16.1 and TCLP were conducted on the final waste forms. Fates of the contaminants in the final waste forms were established by electron microscopy. In addition, stability of the waste forms in aqueous environments was evaluated with long-term water-immersion tests

  20. PERFORMANCE EVALUATION OF ELECTROCOAGULATION PROCESS FOR DIAZINON REMOVAL FROM AQUEOUS ENVIRONMENTS BY USING IRON ELECTRODES

    Directory of Open Access Journals (Sweden)

    E. Bazrafshan, A. H. Mahvi, S. Nasseri, M. Shaieghi

    2007-04-01

    Full Text Available The present study investigates the removal of pesticide by electrocoagulation process. A glass tank in 1.56 L volume with four iron plate electrodes was used to perform the experiments. The electrodes connected to a DC power supply (bipolar mode. The tank was filled with synthetic wastewater were which contained diazinon pesticide in concentration of 10, 50 and 100 mg/L. The percent of diazinon removal was measured at pH= 3, 7 and 10 and in electric potential range of 20-40V by thin layer chromatography method. The results indicated that initial concentration of diazinon can affect efficiency removal and for higher concentrations of diazinon, higher electrical potential or more reaction time is needed. The results showed that for a given time, the removal efficiency increased significantly with increase of voltage. The highest electrical potential (40V produced the quickest treatment with >99% diazinon reduction occurring after 60 min. The final pH for iron electrodes was always higher than initial pH. Finally it can be concluded that electrocoagulation process (using iron electrodes is a reliable, efficient and cost-effective method for removal of diazinon from aqueous environments, especially designed for pH=3 and voltage=40V.

  1. Adsorptive removal of nickel(II) ions from aqueous environment: A review.

    Science.gov (United States)

    Raval, Nirav P; Shah, Prapti U; Shah, Nisha K

    2016-09-01

    Among various methods adsorption can be efficiently employed for the treatment of heavy metal ions contaminated wastewater. In this context the authors reviewed variety of adsorbents used by various researchers for the removal of nickel(II) ions from aqueous environment. One of the objectives of this review article is to assemble the scattered available enlightenment on a wide range of potentially effective adsorbents for nickel(II) ions removal. This work critically assessed existing knowledge and research on the uptake of nickel by various adsorbents such as activated carbon, non-conventional low-cost materials, nanomaterials, composites and nanocomposites. The system's performance is evaluated with respect to the overall metal removal and the adsorption capacity. In addition, the equilibrium adsorption isotherms, kinetics and thermodynamics data as well as various optimal experimental conditions (solution pH, equilibrium contact time and dosage of adsorbent) of different adsorbents towards Ni(II) ions were also analyzed. It is evident from a literature survey of more than 190 published articles that agricultural solid waste materials, natural materials and biosorbents have demonstrated outstanding adsorption capabilities for Ni(II) ions. PMID:27149285

  2. Context of ancient aqueous environments on Mars from in situ geologic mapping at Endeavour Crater

    Science.gov (United States)

    Crumpler, L. S.; Arvidson, R. E.; Bell, J.; Clark, B. C.; Cohen, B. A.; Farrand, W. H.; Gellert, R.; Golombek, M.; Grant, J. A.; Guinness, E.; Herkenhoff, K. E.; Johnson, J. R.; Jolliff, B.; Ming, D. W.; Mittlefehldt, D. W.; Parker, T.; Rice, J. W., Jr.; Squyres, S. W.; Sullivan, R.; Yen, A. S.

    2015-03-01

    Using the Mars Exploration Rover Opportunity, we have compiled one of the first field geologic maps on Mars while traversing the Noachian terrain along the rim of the 22 km diameter Endeavour Crater (Latitude -2°16'33", Longitude -5°10'51"). In situ mapping of the petrographic, elemental, structural, and stratigraphic characteristics of outcrops and rocks distinguishes four mappable bedrock lithologic units. Three of these rock units predate the surrounding Burns formation sulfate-rich sandstones and one, the Matijevic Formation, represents conditions on early Mars predating the formation of Endeavour Crater. The stratigraphy assembled from these observations includes several geologic unconformities. The differences in lithologic units across these unconformities record changes in the character and intensity of the Martian aqueous environment over geologic time. Water circulated through fractures in the oldest rocks over periods long enough that texturally and elementally significant alteration occurred in fracture walls. These oldest pre-Endeavour rocks and their network of mineralized and altered fractures were preserved by burial beneath impact ejecta and were subsequently exhumed and exposed. The alteration along joints in the oldest rocks and the mineralized veins and concentrations of trace metals in overlying lithologic units is direct evidence that copious volumes of mineralized and/or hydrothermal fluids circulated through the early Martian crust. The wide range in intensity of structural and chemical modification from outcrop to outcrop along the crater rim shows that the ejecta of large (>8 km in diameter) impact craters is complex. These results imply that geologic complexity is to be anticipated in other areas of Mars where cratering has been a fundamental process in the local and regional geology and mineralogy.

  3. Humic Acid Degradation via Solar Photo-Fenton Process in Aqueous Environment

    Directory of Open Access Journals (Sweden)

    Seyed Ali Sajjadi

    2015-08-01

    Full Text Available Control of mutagenic and carcinogenic disinfection by-products, particularly Trihalomethanes (THMs and Halo Acetic Acids (HAAs in water treatment process is critical, due to their adverse effects on human health. Generally, reducing the toxicity of these by-products hinges on prior removal of the precursor materials, such as Humic Acid (HA in drinking water. This study was conducted to investigate the role of some parameters that could affect the removal of HA, including HA (5 and 10 ppm and H2O2 (20, 40, 60, and 80 ppm initial concentrations, Iron (II, sulfate heptahydrate dosage (4, 8, 12, and 16 ppm, pH (2, 3, 4 and 5, Oxidation time (5, 10, 15 and 30 min, and Sunlight levels (322±13 kWm-2. To accelerate the process of HA removal, the Solar Photo-Fenton (SPF process was employed by direct irradiation of converged sunlight in a Parabolic Trough Collectors (PTC, with 3m2 effective area. HA levels were measured via quantifying Dissolved Organic Carbon (DOC concentrations by means of a TOC Analyzer method. The results showed that the SPF process is under control of the Fe & H2O2 ratio, the Fe2+ dosage and especially the pH quantity. In optimal condition, (pH: 4, oxidation time: 30min, initial HA levels: 50 ppm, H2O2 concentrations: 20 ppm Fe+2 levels: 4 ppm, the study found more than 98% DOC removal. In conclusion, the SPF, as an economically effective technique, could be applied for the removal of HA in aqueous environments.

  4. Preferred conformation of endomorphin-1 in aqueous and membrane-mimetic environments.

    Science.gov (United States)

    Fiori, S; Renner, C; Cramer, J; Pegoraro, S; Moroder, L

    1999-08-01

    The newly discovered endomorphin-1 (Tyr-Pro-Trp-Phe-NH2) and endomorphin-2 (Tyr-Pro-Phe-Phe-NH2) are potent opioid peptides with the highest affinity and selectivity for the mu receptor among all known endogenous ligands. To investigate a possible correlation between these biological properties and the conformational preferences of the small peptides, a comparative structural analysis was performed of endomorphin-1 in aqueous buffer and in membrane-mimicking SDS and AOT normal and reverse micelles by the use of CD, FT-IR, fluorescence and(1)H-NMR spectroscopy. It is well established for opioid peptides that, independently of the receptor selectivity, the Tyr1 residue plays the role of the primary pharmacophore and that the orientation of the second aromatic pharmacophore relative to the tyrosine side-chain dictates the mu or delta-receptor selectivity. By varying the environment of endomorphin-1 from water to the amphipathic SDS micelles and even more efficiently to the AOT reverse micelles, the display of the aromatic side-chains changes from an interaction of the Tyr1 and Phe4 residues to a switch of the Trp3 indole group into close contact with the phenolic moiety to prevent this type of interaction and to force an orientation of the Phe4 side-chain into the opposite direction. This conformational switch is accompanied by a stabilization of the cis -Pro2 isomer and the resulting spatial array of the pharmacophoric groups correlate well with the structural model of mu receptor-bound opioid peptides. The results indicate that AOT reverse micelles with a woof 10, where almost exclusively ordered water is secluded in the cavity, constitute with their electrostatic and hydrophobic potential an excellent mimetic of amphipathic surfaces as present on lipid bilayers and on ligand-recognition and ligand-binding sites of proteins. PMID:10438613

  5. Defect effect on tribological behavior of diamond-like carbon films deposited with hydrogen diluted benzene gas in aqueous environment

    Science.gov (United States)

    Yi, Jin Woo; Park, Se Jun; Moon, Myoung-Woon; Lee, Kwang-Ryeol; Kim, Seock-Sam

    2009-05-01

    This study examined the friction and wear behavior of diamond-like carbon (DLC) films deposited from a radio frequency glow discharge using a hydrogen diluted benzene gas mixture. The DLC films were deposited on Si (1 0 0) and polished stainless steel substrates by radio frequency plasma-assisted chemical vapor deposition (r.f.-PACVD) at hydrogen to benzene ratios, or the hydrogen dilution ratio, ranging from 0 to 2.0. The wear test was carried out in both ambient and aqueous environments using a homemade ball-on-disk type wear rig. The stability of the DLC coating in an aqueous environment was improved by diluting the benzene precursor gas with hydrogen, suggesting that hydrogen dilution during the deposition of DLC films suppressed the initiation of defects in the film and improved the adhesion of the coating to the interface.

  6. Mineralogy and chemistry of altered Icelandic basalts: Application to clay mineral detection and understanding aqueous environments on Mars

    OpenAIRE

    Ehlmann, B. L.; Bish, D. L.; Ruff, S. W.; Mustard, J. F.

    2012-01-01

    We used a suite of techniques, including those emulating compositional data sets obtained from Mars orbit and obtainable at the Mars surface, to examine aqueous alteration of basaltic rocks from Iceland as a mineralogic and geochemical analog for Noachian environments on Mars. A sample suite was collected for laboratory measurement of (1) whole-rock visible/near-infrared (VNIR) reflectance and thermal infrared (TIR) emission spectra; (2) VNIR and TIR reflectance spectra of particle-size separ...

  7. Structural Evolution of Molybdenum Carbides in Hot Aqueous Environments and Impact on Low-Temperature Hydroprocessing of Acetic Acid

    OpenAIRE

    Jae-Soon Choi; Viviane Schwartz; Eduardo Santillan-Jimenez; Mark Crocker; Samuel A. Lewis; Michael J. Lance; Meyer, Harry M.; More, Karren L.

    2015-01-01

    We investigated the structural evolution of molybdenum carbides subjected to hot aqueous environments and their catalytic performance in low-temperature hydroprocessing of acetic acid. While bulk structures of Mo carbides were maintained after aging in hot liquid water, a portion of carbidic Mo sites were converted to oxidic sites. Water aging also induced changes to the non-carbidic carbon deposited during carbide synthesis and increased surface roughness, which in turn affected carbide pore...

  8. Characterization of complex non-aqueous phase liquids (NAPLs) in the subsurface environment: partitioning and interfacial tracer tests and numerical dissolution assessment

    OpenAIRE

    Piepenbrink, Matthias

    2007-01-01

    Contamination of the subsurface environment by complex organic non-aqueous phase liquids (NAPLs) and the resulting release of carcinogenic or mutagenic organic compounds impose a serious risk on groundwater quality. Due to the low aqueous solubilities of the individual organic components the rate of mass transfer from the non-aqueous phase to the water phase is very slow, thus NAPL source zones typically represent long-term contamination problems with organic compounds leaching into the...

  9. Removal of Cr(VI from Aqueous Environments Using Micelle-Clay Adsorption

    Directory of Open Access Journals (Sweden)

    Mohannad Qurie

    2013-01-01

    Full Text Available Removal of Cr(VI from aqueous solutions under different conditions was investigated using either clay (montmorillonite or micelle-clay complex, the last obtained by adsorbing critical micelle concentration of octadecyltrimethylammonium ions onto montmorillonite. Batch experiments showed the effects of contact time, adsorbent dosage, and pH on the removal efficiency of Cr(VI from aqueous solutions. Langmuir adsorption isotherm fitted the experimental data giving significant results. Filtration experiments using columns filled with micelle-clay complex mixed with sand were performed to assess Cr(VI removal efficiency under continuous flow at different pH values. The micelle-clay complex used in this study was capable of removing Cr(VI from aqueous solutions without any prior acidification of the sample. Results demonstrated that the removal effectiveness reached nearly 100% when using optimal conditions for both batch and continuous flow techniques.

  10. Surface Hydrophilicity and Functional Group-Driven Iron(III) Hydroxide Nucleation on Organic-Coated Substrates in Aqueous Environments

    Science.gov (United States)

    Ray, J.; Lee, B.; Baltrusaitis, J.; Jun, Y.

    2012-12-01

    Homogeneous and heterogeneous iron hydroxide nanoparticle nucleation can occur continuously in both natural and complex aqueous systems. Iron oxide nanoparticles can act as sinks and/or carriers for heavy metal contaminants; therefore, it is important to develop a better understanding of factors affecting their formation. Organic coatings are ubiquitous in aqueous environments where they can exist on mineral surfaces (e.g., biofilm), as nanoparticle surface coatings (e.g., natural organic matter), or be introduced as coagulants in water treatment systems. These surface coatings could influence the formation of iron oxide nanoparticles and thus, the mobility of aqueous contaminants. Therefore, to better understand the fate and transport of contaminants in complex aqueous environments, we need more accurate information about mechanisms governing heterogeneous and homogeneous nucleation and growth of iron(III) hydroxide nanoparticles in the presence of organic surface coatings. In this work, we used a unique measurement technique allowing for simultaneous small-angle X-ray scattering (SAXS) and grazing incidence (GISAXS) analysis to monitor nanoparticle nucleation in solution and at substrate surfaces. Clean quartz, and polyaspartate- and alginate-coated substrates were chosen as model substrates to represent mineral coatings, engineered organic coatings and natural organic coatings. Polyaspartate was determined to be the most negatively charged substrate and quartz to be the least negatively charged substrate; however, after 2 h of reaction, the total nanoparticle volume calculations—determined from GISAXS—indicate that precipitation of positively-charged iron(III) hydroxide nanoparticles is 10 times higher on the quartz substrate than on the polyaspartate substrate. This implies that electrostatics do not govern iron(III) hydroxide nucleation. Furthermore, homogeneous nucleation approximately 250 μm above the substrate surface was highest in the presence of the

  11. Performance of Cement-Based Materials in Aggressive Aqueous Environments State-of-the-Art Report, RILEM TC 211 - PAE

    CERN Document Server

    Bertron, Alexandra; Belie, Nele

    2013-01-01

    Concrete and cement-based materials must operate in increasingly aggressive aqueous environments, which may be either natural or industrial.  These materials may suffer degradation in which ion addition and/or ion exchange reactions occur, leading to a breakdown of the matrix microstructure and consequent weakening.  Sometimes this degradation can be extremely rapid and serious such as in acidic environments, while in other cases degradation occurs over long periods.  Consequences of material failure are usually severe – adversely affecting the health and well-being of human communities and disturbing ecological balances. There are also large direct costs of maintaining and replacing deteriorated infrastructure and indirect costs from loss of production during maintenance work, which place a great burden on society. The focus of this book is on addressing issues concerning performance of cement-based materials in aggressive aqueous environments , by way of this State-of-the-Art Report. The book represe...

  12. A CALPHAD study on the thermodynamic stability of calcium-, zinc-, and yttrium-doped magnesium in aqueous environments

    International Nuclear Information System (INIS)

    Highlights: ► Execution of CALPHAD thermodynamic study and hydrolysis reactions of Mg-alloys. ► CALPHAD and ab-initio studies demonstrate very similar results in pure water. ► Alloying of Mg with Ca and Y promote hydrolysis, while Zn resists the hydrolysis. ► Mg-(Ca, Y, Zn) alloys yield similar stability effects in water and in bio-solution. ► Kinetic aspects are vital for aqueous stability studies of biodegradable Mg-alloys. - Abstract: Magnesium has attracted the attention of the biomaterials community as a potential biodegradable metallic candidate for use in stents and orthopedic applications. Alloying of Mg with metals such as Ca, Y and Zn, etc., to form alloy precursors is important to optimize its corrosion rate in electrolytic and aqueous environments to understand the alloy response in body fluid environments. In the current study, the chemical reactions of Mg–Me alloys (Me = Ca, Y, and Zn) with pure water have been investigated using the CALPHAD technique. A qualitative agreement between CALPHAD and first-principles results has been obtained. The CALPHAD method has also been employed to study the reactions of Mg alloys in the human blood fluid environment. The effects of alloying elements and compositions on the reaction enthalpies, reaction products, amount of gas release and gas compositions as well as the pH of the fluids have been systematically discussed and reported.

  13. Molecular dynamics simulation study on zwitterionic structure to maintain the natural behavior of polyalanine13 in aqueous environment

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Molecular dynamics simulations are applied to the initial stage of polyalanine13 conformational transition from α-helix to random coil in aqueous environment and the interaction of polyalanine13 with zwitterionic and hydrophobic surfaces respectively in the same condition. The analysis of secondary structure, hydrogen bonds, RMSD, dihedral distribution, and the degree of adsorption are performed. The results show that zwitterionic structure maintains the natural behavior of polyalanine13 in water to a better extent, which should be an indirect proof of the hypothesis of "maintain of normal structure."

  14. Mineralogy and chemistry of altered Icelandic basalts: Application to clay mineral detection and understanding aqueous environments on Mars

    Science.gov (United States)

    Ehlmann, B. L.; Bish, D. L.; Ruff, S. W.; Mustard, J. F.

    2012-10-01

    We used a suite of techniques, including those emulating compositional data sets obtained from Mars orbit and obtainable at the Mars surface, to examine aqueous alteration of basaltic rocks from Iceland as a mineralogic and geochemical analog for Noachian environments on Mars. A sample suite was collected for laboratory measurement of (1) whole-rock visible/near-infrared (VNIR) reflectance and thermal infrared (TIR) emission spectra; (2) VNIR and TIR reflectance spectra of particle-size separates derived from the bulk rock and from materials extracted from fractures/vesicles; (3) X-ray diffraction (XRD) patterns for determination of quantitative modal mineralogy; (4) major element chemistry using flux fusion of whole-rock powders; and (5) electron microprobe analyses of minerals in thin sections. Conclusions about aqueous alteration can be influenced by technique. For these basalts, whole-rock chemical data showed scant evidence for chemical fractionation, but TIR, VNIR, and XRD measurements identified distinctive assemblages of hydrous silicate minerals, differing by sample. XRD provided the most complete and accurate quantitative determination of sample mineralogy. However, VNIR spectroscopy was the technique most useful for determining composition of low-abundance smectite clays, and TIR spectroscopy was the most useful for recognizing hydrated silicates in thin surface coatings. High spatial resolution mineralogical and chemical data sets were useful for understanding the texture and distribution of alteration products and variations in fluid chemistry. No single approach provides a complete assessment of the environment of alteration, demonstrating the importance of employing multiple, synergistic mineralogical and geochemical techniques and instruments in exploration of rock strata from aqueous paleoenvironments on Mars.

  15. The effect of molybdenum on the corrosion behaviour of the high-entropy alloys Co1.5CrFeNi1.5Ti0.5Mox in aqueous environments

    International Nuclear Information System (INIS)

    The purpose of this study is to investigate the electrochemical properties of the Co1.5CrFeNi1.5Ti0.5Mox high-entropy alloys in three aqueous environments which simulate acidic, marine, and basic environments at ambient temperature (∼25 oC). The potentiodynamic polarisation curves of the Co1.5CrFeNi1.5Ti0.5Mox alloys, obtained in aqueous solutions of H2SO4 and NaOH, clearly revealed that the corrosion resistance of the Mo-free alloy was superior to that of the Mo-containing alloys. On the other hand, the lack of hysteresis in cyclic polarisation tests and SEM micrographs confirmed that the Mo-containing alloys are not susceptible to pitting corrosion in NaCl solution.

  16. Synchrotron X-ray bio-imaging of natural and synthetic bone-graft materials in an aqueous environment

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yong-Gun [Kyungpook National University, Daegu (Korea, Republic of); Bark, Chung-Wung [Gachon University, Seongnam (Korea, Republic of)

    2014-11-15

    Bone-graft materials in dentistry have osteoinductive and osteoconductive abilities, which depend on their microstructural characteristics, such as their porosity, particle size, micro channels, and absorption. These characteristics have been observed using various imaging techniques, such as optical microscopy and scanning electron microscopy (SEM). However, most techniques cannot provide images in water, even though graft materials in vivo are invariably in contact with different water-based fluids. Synchrotron X-ray imaging allows sample micro environments to be controlled as X-ray beams easily penetrate air and water. In this report, we used the synchrotron X-ray imaging technique to provide in-situ images of various bone-graft materials in aqueous environments. We observed internal microstructural images of bone-graft materials in real-time in 0.9% saline solution and interactions between bone-graft materials and saline, that is, hydration patterns and bone-graft expansion.

  17. Synchrotron X-ray bio-imaging of natural and synthetic bone-graft materials in an aqueous environment

    International Nuclear Information System (INIS)

    Bone-graft materials in dentistry have osteoinductive and osteoconductive abilities, which depend on their microstructural characteristics, such as their porosity, particle size, micro channels, and absorption. These characteristics have been observed using various imaging techniques, such as optical microscopy and scanning electron microscopy (SEM). However, most techniques cannot provide images in water, even though graft materials in vivo are invariably in contact with different water-based fluids. Synchrotron X-ray imaging allows sample micro environments to be controlled as X-ray beams easily penetrate air and water. In this report, we used the synchrotron X-ray imaging technique to provide in-situ images of various bone-graft materials in aqueous environments. We observed internal microstructural images of bone-graft materials in real-time in 0.9% saline solution and interactions between bone-graft materials and saline, that is, hydration patterns and bone-graft expansion.

  18. Nondisruptive Dissolution of Hyperpolarized (129) Xe into Viscous Aqueous and Organic Liquid Crystalline Environments.

    Science.gov (United States)

    Truxal, Ashley E; Slack, Clancy C; Gomes, Muller D; Vassiliou, Christophoros C; Wemmer, David E; Pines, Alexander

    2016-04-01

    Studies of hyperpolarized xenon-129 (hp-(129) Xe) in media such as liquid crystals and cell suspensions are in demand for applications ranging from biomedical imaging to materials engineering but have been hindered by the inability to bubble Xe through the desired media as a result of viscosity or perturbations caused by bubbles. Herein a device is reported that can be reliably used to dissolve hp-(129) Xe into viscous aqueous and organic samples without bubbling. This method is robust, requires small sample volumes (<60 μL), is compatible with existing NMR hardware, and is made from readily available materials. Experiments show that Xe can be introduced into viscous and aligned media without disrupting molecular order. We detected dissolved xenon in an aqueous liquid crystal that is disrupted by the shear forces of bubbling, and we observed liquid-crystal phase transitions in (MBBA). This tool allows an entirely new class of samples to be investigated by hyperpolarized-gas NMR spectroscopy. PMID:26954536

  19. Surface Changes and Impurity Release Kinetics of Titanium Dioxide Nanoparticles in Aqueous Environment

    Science.gov (United States)

    Previous studies have found the significant role of impurities (i.e., silicon, phosphorus) in the aggregation and sedimentation of TiO2 nanoparticles in water environment. However, it is not understood whether dissolution of the impurities potentially impacts the environment or t...

  20. Corrosion properties of HVOF cermet coatings with bond coats in an aqueous chloride environment

    International Nuclear Information System (INIS)

    WC-17Co coatings with Ni-5Al bonding layers were deposited on Al-7075 by HVOF spraying. The top-coat consisted of layers comprising tungsten carbide particles embedded in a Co(W,C) matrix of varied composition.The coated specimens were subjected to potentiodynamic polarization in 3.5% aqueous NaCl at 25, 35 and 45 deg. C. The coatings exhibited pseudopassivity caused by the oxidation of tungsten, carbon and possibly cobalt. Chronoamperometric measurements indicated that the inhomogeneous binder composition induced active corrosion processes taking place simultaneously with pseudopassivity. Cyclic polarization suggested that the coatings were not susceptible to pit corrosion in the temperature range of 25-45 deg. C. The likely 'critical pitting' temperature of the coatings was 60 deg. C. Higher testing temperatures led to lower corrosion potentials and faster corrosion kinetics

  1. Fabrication of ZnO:Mn nanoparticles with organic shell in a highly alkaline aqueous environment

    Science.gov (United States)

    Chawla, Santa; Sharda; Jayanthi, K.

    2011-01-01

    Synthesis of undoped and Mn doped ZnO nanoparticles by an inclusive co precipitation method and in situ capping with heteromultifunctional organic stabilizer mercaptosuccinic acid (MSA) in a core shell structure, in highly alkaline aqueous matrix have been accomplished. Near room temperature synthesis resulted in high quality monophasic wurtzite hexagonal structure of rod shaped nanoparticles of bare ZnO:Mn with no signature of dopant as separate phase. MSA capping resulted in nanoball like formation. Thermo gravimetric analysis (TGA) and FTIR confirmed MSA capping. ZnO: Mn particles emit in orange and red when excited by UV and blue light. Surface modification makes the nanoparticles hydrophilic with active organic surface easy for bioconjugation with any ligand and can have applications in drug delivery or as nanoscale fluorescent probe in a biological system.

  2. Atomistic Simulations of Functional Au-144(SR)(60) Gold Nanoparticles in Aqueous Environment

    DEFF Research Database (Denmark)

    Heikkila, E.; Gurtovenko, A. A.; Martinez-Seara, H.;

    2012-01-01

    Charged monolayer-protected gold nanoparticles (AuNPs) have been studied in aqueous solution by performing atomistic molecular dynamics simulations at physiological temperature (310 K). Particular attention has been paid to electrostatic properties that modulate the formation of a complex comprised...... of the nanoparticle together with surrounding ions and water. We focus on Au-144 nanoparticles that comprise a nearly spherical Au core (diameter similar to 2 nm), a passivating Au-S interface, and functionalized alkanethiol chains. Cationic and anionic AuNPs have been modeled with amine and carboxyl...... electrostatic potential displays a minimum for AuNP- at 1.9 nm from the center of the nanoparticle, marking a preferable location for Na+, while the AuNP+ potential (affecting the distribution of Cl-) rises almost monotonically with a local maximum. Comparison to Debye-Huckel theory shows very good agreement...

  3. Multi-Scale Studies of Transport and Adsorption Phenomena of Cement-based Materials in Aqueous and Saline Environment

    Science.gov (United States)

    Yoon, Se Yoon

    The transport and adsorption phenomena in cement-based materials are the most important processes in the durability of concrete structures or nuclear waste containers, as they are precursors to a number of deterioration processes such as chloride-induced corrosion, sulfate attack, carbonation, etc. Despite this importance, our understanding of these processes remains limited because the pore structure and composition of concrete are complex. In addition, the range of the pore sizes, from nanometers to millimeters, requires the multi-scale modeling of the transport and adsorption processes. Among the various environments that cement-based materials are exposed to, aqueous and saline environments represent the most common types. Therefore, this dissertation investigates the adsorption and transport phenomena of cement-based materials exposed to an aqueous and saline environment from atomic to macro-scales using different arrays of novel spectroscopic techniques and simulation methods, such as scanning transmission X-ray microscopy (STXM), X-ray absorption near edge structure (XANES), molecular dynamics (MD), and finite element method (FEM). The structure and transport of water molecules through interlayer spacing of tobermorite was investigated using MD simulations because the interlayer water of calcium silicate hydrate (C-S-H) gel influences various material properties of concrete. The adsorption processes of cementitious phases interacting with sodium and chloride ions at the nano-scale were identified using STXM and XANES measurements. A mathematical model and FEM procedure were developed to identify the effect of surface treatments at macro-scale on ionic transport phenomena of surface-treated concrete. Finally, this dissertation introduced a new material, calcined layered double hydroxide (CLDH), to prevent chloride-induced deterioration.

  4. The effect of aqueous environments upon the initiation and propagation of fatigue cracks in low-alloy steels

    International Nuclear Information System (INIS)

    The effect of elevated temperature aqueous environments upon the initiation and propagation of fatigue cracks in low-alloy steels is discussed in terms of the several parameters which influence such behavior. These parameters include water chemistry, impurities within the steels themselves, as well as factors such as the water flow rate, loading waveform and loading rates. Some of these parameters have similar effects upon both crack initiation and propagation, while others exhibit different effects in the two stages of cracking. In the case of environmentally-assisted crack (EAC) growth, the most important impurities within the steel are metallurgical sulfide inclusions which dissolve upon contact with the water. A ''critical'' concentration of sulfide ions at the crack tip can then induce environmentally-assisted cracking which proceeds at significantly increased crack growth rates over those observed in air. The occurrence, or non-occurrence, of EAC is governed by the mass-transport of sulfide ions to and from the crack-tip region, and the mass-transport is discussed in terms of diffusion, ion migration, and convection induced within the crack enclave. Examples are given of convective mass-transport within the crack enclave resulting from external free stream flow. The initiation of fatigue cracks in elevated temperature aqueous environments, as measured by the S-N fatigue lifetimes, is also strongly influenced by the parameters identified above. The influence of sulfide inclusions does not appear to be as strong on the crack initiation process as it is on crack propagation. The oxygen content of the environment appears to be the dominant factor, although loading frequency (strain rate) and temperature are also important factors

  5. Pattern recognition and data mining software based on artificial neural networks applied to proton transfer in aqueous environments

    International Nuclear Information System (INIS)

    In computational physics proton transfer phenomena could be viewed as pattern classification problems based on a set of input features allowing classification of the proton motion into two categories: transfer ‘occurred’ and transfer ‘not occurred’. The goal of this paper is to evaluate the use of artificial neural networks in the classification of proton transfer events, based on the feed-forward back propagation neural network, used as a classifier to distinguish between the two transfer cases. In this paper, we use a new developed data mining and pattern recognition tool for automating, controlling, and drawing charts of the output data of an Empirical Valence Bond existing code. The study analyzes the need for pattern recognition in aqueous proton transfer processes and how the learning approach in error back propagation (multilayer perceptron algorithms) could be satisfactorily employed in the present case. We present a tool for pattern recognition and validate the code including a real physical case study. The results of applying the artificial neural networks methodology to crowd patterns based upon selected physical properties (e.g., temperature, density) show the abilities of the network to learn proton transfer patterns corresponding to properties of the aqueous environments, which is in turn proved to be fully compatible with previous proton transfer studies. (condensed matter: structural, mechanical, and thermal properties)

  6. Olivine alteration and H2 production in carbonate-rich, low temperature aqueous environments

    Science.gov (United States)

    Neubeck, Anna; Duc, Nguyen Thanh; Hellevang, Helge; Oze, Christopher; Bastviken, David; Bacsik, Zoltán; Holm, Nils G.

    2014-06-01

    Hydrous alteration of olivine is capable of producing molecular hydrogen (H2) under a wide variety of hydrothermal conditions. Although olivine hydrolysis (i.e., serpentinization) has commonly been assessed at elevated temperatures (>100 °C), the nature of these reactions in relation to H2 production at lower temperatures has not been systematically evaluated, especially with regard to carbonate-rich fluids. Specifically, carbonate formation may kinetically infringe on geochemical routes related to serpentinization and H2 production at lower temperatures. Here time-dependent interactions of solid, liquid, and gaseous phases with respect to olivine hydrolysis in a carbonate-rich solution (20 mM HCO3-) at 30, 50 and 70 °C for 315 days is investigated experimentally. Within the first two months, amorphous Si-rich (i.e., talc-like) and carbonate phases precipitated; however, no inhibition of olivine dissolution is observed at any temperature based on surface chemistry analyses. High-resolution surface analyses confirm that precipitates grew as spheroids or vertically to form topographic highs allowing further dissolution of the free olivine surfaces and exposing potential catalysts. Despite no magnetite (Fe3O4) being detected, H2 increased with time in experiments carried out at 70 °C, indicating an alternative coupled route for Fe oxidation and H2 production. Spectrophotometry analyses show that aqueous Fe(II) is largely converted to Fe(III) potentially integrating into other phases such as serpentine and talc, thus providing a viable pathway for H2 production. No increase in H2 production was observed in experiments carried out at 30 and 50 °C supporting observations that incorporation of Fe(II) into carbonates occurred faster than the intertwined processes of olivine hydrolysis and Fe(III) oxidation. Overall, carbonate formation is confirmed to be a major influence related to H2 production in low-temperature serpentinization systems. We studied low temperature

  7. The properties and transport phenomena in oxide films on iron, nickel, chromium and their alloys in aqueous environments

    Energy Technology Data Exchange (ETDEWEB)

    Laitinen, T.; Bojinov, M.; Betova, I.; Maekelae, K.; Saario, T. [VTT Manufacturing Technology, Espoo (Finland)

    1999-01-01

    The construction materials used in coolant systems in nuclear power plants become covered with oxide films as a result of exposure to the aqueous environment. The susceptibility of the materials to different forms of corrosion, as well as the extent of the incorporation of radioactive species on the surfaces of the primary circuit, are greatly influenced by the physical and chemical properties of these oxide films. The composition and characteristics of the oxide films in turn depend on the applied water chemistry. This work was undertaken in order to collect and evaluate the present views on the structure and behaviour of oxide films formed on iron- and nickel-based materials in aqueous environments. This survey should serve to recognise the areas in which more understanding and research effort is needed. The review begins with a discussion on the bulk oxides of iron, nickel and chromium, as well as their mixed oxides. In addition to bulk oxides, the structure and properties of oxide films forming on pure iron, nickel and chromium and on iron- and nickel-based engineering alloys are considered. General approaches to model the structure and growth of oxide films on metals are discussed in detail. The specific features of the oxide structures, properties and growth at high temperatures are presented with special focus on the relevance of existing models. Finally, the role of oxide films in localised corrosion, oxide breakdown pitting. Stress corrosion cracking and related phenomena is considered. The films formed on the surfaces of iron- and nickel-based alloys in high-temperature aqueous environments generally comprise two layers, i.e. the so-called duplex structure. The inner part is normally enriched in chromium and has a more compact structure, while the outer part is enriched in iron and has a cracked or porous structure. The information collected clearly indicates the effect of the chemical environment on the properties of oxide films growing on metal surfaces

  8. Activities of microorganisms and enzymes in water-restricted environments: biological activities in aqueous compartments at micron scale

    Science.gov (United States)

    Hoppert, Michael; Mlejnek, Klaus; Seiffert, Beatrix; Mayer, Frank

    1997-07-01

    In water-in-oil microemulsions, microdroplets of water, surrounded by a layer of surfactant molecules (reversed micelles), are dispersed in an organic solvent. Various microorganisms (unicellular algae and cyanobacteria) and isolated enzymes were dispersed in microemulsions without loss of biological activity. Each biological system needed a defined quantity of water in the microemulsion for maximum activity. Under optimum conditions, microbial enzymes for various sources (hydrogenases, dehydrogenases) exhibited, besides ten-fold increase in specific activity, a temperature optimum up to 16 degree(s)C higher as compared to aqueous solutions. These experimental findings, together with theoretical considerations, imply that water structure inside reversed micelles is very different from free water, but similar to water in narrow compartments with polar or ionic surfaces. These compartments may represent a model system for environments, where (liquid) water is not available in bulk amounts, but embedded in an anhydrous matrix.

  9. The properties and transport phenomena in oxide films on iron, nickel, chromium and their alloys in aqueous environments

    International Nuclear Information System (INIS)

    The construction materials used in coolant systems in nuclear power plants become covered with oxide films as a result of exposure to the aqueous environment. The susceptibility of the materials to different forms of corrosion, as well as the extent of the incorporation of radioactive species on the surfaces of the primary circuit, are greatly influenced by the physical and chemical properties of these oxide films. The composition and characteristics of the oxide films in turn depend on the applied water chemistry. This work was undertaken in order to collect and evaluate the present views on the structure and behaviour of oxide films formed on iron- and nickel-based materials in aqueous environments. This survey should serve to recognise the areas in which more understanding and research effort is needed. The review begins with a discussion on the bulk oxides of iron, nickel and chromium, as well as their mixed oxides. In addition to bulk oxides, the structure and properties of oxide films forming on pure iron, nickel and chromium and on iron- and nickel-based engineering alloys are considered. General approaches to model the structure and growth of oxide films on metals are discussed in detail. The specific features of the oxide structures, properties and growth at high temperatures are presented with special focus on the relevance of existing models. Finally, the role of oxide films in localised corrosion, oxide breakdown pitting. Stress corrosion cracking and related phenomena is considered. The films formed on the surfaces of iron- and nickel-based alloys in high-temperature aqueous environments generally comprise two layers, i.e. the so-called duplex structure. The inner part is normally enriched in chromium and has a more compact structure, while the outer part is enriched in iron and has a cracked or porous structure. The information collected clearly indicates the effect of the chemical environment on the properties of oxide films growing on metal surfaces

  10. Effect of silty sand with different sizes on corrosion behavior of 3Cr steel in CO2 aqueous environment

    Science.gov (United States)

    Liu, Wei; Lu, Songle; Zhang, Peng; Dou, Juanjuan; Zhao, Qinghe

    2016-08-01

    Corrosion behavior of 3Cr steel in CO2 aqueous environment containing silty sand was investigated by immersion test. The results show that CO2 corrosion rate and morphology of 3Cr steel were obviously affected by the size of silty sand. 5000 mesh silty sand mixed with corrosion products, forming compact Cr-rich corrosion scale and resulting in low corrosion rate and uniform corrosion. 1000 mesh silty sand mixed with corrosion products, forming porous corrosion scale without Cr enrichment and resulting in high corrosion rate and pitting corrosion. 5000 mesh silty sand enhanced Cr enrichment in corrosion scale, leading to low anodic current. However, 1000 mesh silty sand deteriorated Cr enrichment in corrosion scale, leading to high anodic current. Cathodic current was reduced by silty sand, but was not affected by two sizes of silty sand. Cr enrichment in corrosion scale of 3Cr steel was obviously affected by separation effect of silty sand.

  11. Uptake of permanganate from aqueous environment by surfactant modified montmorillonite batch and fixed bed studies

    Indian Academy of Sciences (India)

    N Mahadevaiah; B Vijayakumar; K Hemalatha; B S Jai Prakash

    2011-12-01

    Organo-clay was prepared by incorporating different amounts (in terms of CEC, ranging from 134–840 mg of quaternary ammonium cation (QACs) such as hexadecytrimethylammonium bromide ([C19H42N]Br) into the montmorillonite clay. Prepared organo-clays are characterized by CHN analyser and XRD to measure the amount of elemental content and interlayer spacing of surfactant modified clay. The batch experiments of sorption of permanganate from aqueous media by organo-clays was studied at different acidic strengths (pH 1–7). The experimental results show that the rate and amount of adsorption of permanganate was higher at lower pH compared to raw montmorillonite. Laboratory fixed bed experiments were conducted to evaluate the breakthrough time and nature of breakthrough curves. The shape of the breakthrough curves shows that the initial cationic surfactant loadings at 1.0 CEC of the clay is enough to enter the permanganate ions in to the interlamellar region of the surfactant modified smectile clays. These fixed bed studies were also applied to quantify the effect of bed-depth and breakthrough time during the uptake of permanganate. Calculation of thermodynamic parameters shows that the sorption of permanganate is spontaneous and follows the first order kinetics.

  12. Molecular Modeling of Ammonium, Calcium, Sulfur, and Sodium Lignosulphonates in Acid and Basic Aqueous Environments

    Science.gov (United States)

    Salazar Valencia, P. J.; Bolívar Marinez, L. E.; Pérez Merchancano, S. T.

    2015-12-01

    Lignosulphonates (LS), also known as lignin sulfonates or sulfite lignin, are lignins in sulfonated forms, obtained from the "sulfite liquors," a residue of the wood pulp extraction process. Their main utility lies in its wide range of properties, they can be used as additives, dispersants, binders, fluxing, binder agents, etc. in fields ranging from food to fertilizer manufacture and even as agents in the preparation of ion exchange membranes. Since they can be manufactured relatively easy and quickly, and that its molecular size can be manipulated to obtain fragments of very low molecular weight, they are used as transport agents in the food industry, cosmetics, pharmaceutical and drug development, and as molecular elements for the treatment of health problems. In this paper, we study the electronic structural and optical characteristics of LS incorporating ammonium, sulfur, calcium, and sodium ions in acidic and basic aqueous media in order to gain a better understanding of their behavior and the very interesting properties exhibit. The studies were performed using the molecular modeling program HyperChem 5 using the semiempirical method PM3 of the NDO Family (neglect of differential overlap), to calculate the structural properties. We calculated the electronic and optical properties using the semiempirical method ZINDO / CI.

  13. Development of a continuous flow hydride generation laser-induced breakdown spectroscopic system: Determination of tin in aqueous environments

    Energy Technology Data Exchange (ETDEWEB)

    Unal, Semira [Izmir Institute of Technology, Faculty of Science, Chemistry Department, 35430 Izmir (Turkey); Yalcin, Serife, E-mail: serifeyalcin@iyte.edu.t [Izmir Institute of Technology, Faculty of Science, Chemistry Department, 35430 Izmir (Turkey)

    2010-08-15

    The design, construction and optimization studies of a continuous flow hydride generation laser-induced breakdown spectroscopic system, HG-LIBS, for the determination of tin in aqueous environments is presented. Optimization of the Laser Induced Breakdown Spectroscopy (LIBS) signal with respect to carrier gas flow rate, analyte, acid (HCl) and reductant (NaBH{sub 4}) concentrations and flow rates was performed by using spectral emission intensity from the neutral Sn(I) line at 284.0 nm under atmospheric pressures. With flow rates of 5.0 mL/min for NaBH{sub 4} and 2.5 mL/min for HCl, optimum NaBH{sub 4} and HCl concentrations were determined as 2.0% (w/v) and 1.0% (v/v), respectively. The hydride generation efficiency of the system was tested for tin hydride, stannane (SnH{sub 4}), by inductively coupled plasma mass spectrometer (ICP-MS). It was found that higher than 99% of the analyte was released into the gaseous phase. Upon optimization, the minimum detectable Sn concentration was found as 0.3 mg/L in water samples. That corresponds to more than two orders of increase in sensitivity compared to methods that employ common sample introduction techniques in liquids analysis by LIBS. Over 90% recoveries were obtained from spiking experiments with river, tap and drinking water samples. Results illustrate potential use of the continuous flow HG-LIBS system for monitoring of Sn concentrations in aqueous environments.

  14. Electrochemistry in aqueous solution at high temperature and under pressure: study of nickel in a highly alkaline environment

    International Nuclear Information System (INIS)

    This research thesis reports the study of the corrosion resistance and anodic behaviour of various metals and alloys used in conventional thermal or nuclear power stations, more particularly the case of nickel in a highly alkaline environment (KOH 5 N) which is widely used for hydrogen production by water electrolysis. The author studied the influence of temperature and pressure on the electrochemical behaviour of nickel, and more particularly the first-oxidation kinetics. The report discusses the physicochemical and thermodynamic properties of aqueous systems at high temperature and under pressure, presents the general techniques of high-temperature electrochemistry, describes the experimental installation, and reports the development of a reference electrode which can operate in those experimental conditions. The author reports the study of the electrochemical behaviour of nickel in alkaline environment and at high temperature, reports a surface analysis performed by Auger spectroscopy, electron spectroscopy for chemical analysis or ESCA, and scanning electronic microscopy, reports the study of the electrochemical behaviour of nickel in a potassium hydroxide solution under normal temperature and pressure, but also in acid environment. Results are interpreted with respect to temperature

  15. Heavy metals removal from aqueous environments by electrocoagulation process– a systematic review

    OpenAIRE

    Bazrafshan, Edris; Mohammadi, Leili; Ansari-Moghaddam, Alireza; MAHVI, Amir Hossein

    2015-01-01

    Heavy metals pollution has become a more serious environmental problem in the last several decades as a result releasing toxic materials into the environment. Various techniques such as physical, chemical, biological, advanced oxidation and electrochemical processes were used for the treatment of domestic, industrial and agricultural effluents. The commonly used conventional biological treatments processes are not only time consuming but also need large operational area. Accordingly, it seems...

  16. Community Lenses Revealing the Role of Sociocultural Environment on Physical Activity

    Science.gov (United States)

    Belon, Ana Paula; Nieuwendyk, Laura M.; Vallianatos, Helen; Nykiforuk, Candace I. J.

    2016-01-01

    Purpose To identify perceptions of how sociocultural environment enabled and hindered physical activity (PA) participation. Design Community-based participatory research. Setting Two semirural and two urban communities located in Alberta, Canada. Participants Thirty-five people (74.3% females, 71.4% aged 25–64 years) across the four communities. Method PhotoVoice activities occurred over 3 months during the spring of 2009. Participants were asked to document perceived environmental attributes that might foster or inhibit PA in their community. Photographs and narratives were shared in one-on-one interviews. Line-by-line coding of the transcripts was independently conducted by two researchers using an inductive approach. Codes were arranged into themes and subthemes, which were then organized into the Analysis Grid for Environments Linked to Obesity (ANGELO) framework. Results Six main themes (accompanied by subthemes) emerged: sociocultural aesthetics, safety, social involvement, PA motivation, cultural ideas of recreation, and car culture. Representative quotes and photographs illustrate enablers and obstacles identified by participants. Conclusion This PhotoVoice study revealed how aspects of participants’ sociocultural environments shaped their decisions to be physically active. Providing more PA resources is only one step in the promotion of supportive environments. Strategies should also account for the beautification and maintenance of communities, increasing feelings of safety, enhancement of social support among community members, popularization of PA, and mitigating car culture, among others. PMID:25973966

  17. Influence of Shot Peening on Failure of an Aluminum Alloy Exposed to Aggressive Aqueous Environments

    Science.gov (United States)

    Lv, Shengli; Cu, You; Zhang, Wei; Tong, Xiaoyan; Srivatsan, T. S.; Gao, Xiaosheng

    2013-06-01

    Pre-corrosion damage tests were performed on the high strength aluminum alloy (Al-Zn-Mg-Cu) that was subject to shot peening surface treatment. The tests were performed for different time levels and compared one-on-one with the performance and characteristics of the non-shot-peened alloy. The residual stress induced by the shot peening surface treatment for two different intensity levels was measured using the method of incremental drilling of holes. Based on an observation of morphology of corrosion experienced by the aluminum alloy the depth of corrosion was measured using a laser displacement sensor. The surface of the aluminum alloy that was shot peened revealed an overall better resistance to pitting while concurrently revealing evidence of partial degradation. The depth of degradation is related to the residual stress that is induced in the aluminum alloy sample by the shot peening treatment. The key mechanisms that control damage during corrosion of the shot-peened aluminum alloy can be divided into the distinct stages of (a) initial occurrence of uniform corrosion followed by (b) the generation of degradation, and (c) culminating in the initiation of pitting once the depth of degradation reaches a certain level.

  18. Core microbial functional activities in ocean environments revealed by global metagenomic profiling analyses.

    KAUST Repository

    Ferreira, Ari J S

    2014-06-12

    Metagenomics-based functional profiling analysis is an effective means of gaining deeper insight into the composition of marine microbial populations and developing a better understanding of the interplay between the functional genome content of microbial communities and abiotic factors. Here we present a comprehensive analysis of 24 datasets covering surface and depth-related environments at 11 sites around the world\\'s oceans. The complete datasets comprises approximately 12 million sequences, totaling 5,358 Mb. Based on profiling patterns of Clusters of Orthologous Groups (COGs) of proteins, a core set of reference photic and aphotic depth-related COGs, and a collection of COGs that are associated with extreme oxygen limitation were defined. Their inferred functions were utilized as indicators to characterize the distribution of light- and oxygen-related biological activities in marine environments. The results reveal that, while light level in the water column is a major determinant of phenotypic adaptation in marine microorganisms, oxygen concentration in the aphotic zone has a significant impact only in extremely hypoxic waters. Phylogenetic profiling of the reference photic/aphotic gene sets revealed a greater variety of source organisms in the aphotic zone, although the majority of individual photic and aphotic depth-related COGs are assigned to the same taxa across the different sites. This increase in phylogenetic and functional diversity of the core aphotic related COGs most probably reflects selection for the utilization of a broad range of alternate energy sources in the absence of light.

  19. Core microbial functional activities in ocean environments revealed by global metagenomic profiling analyses.

    Directory of Open Access Journals (Sweden)

    Ari J S Ferreira

    Full Text Available Metagenomics-based functional profiling analysis is an effective means of gaining deeper insight into the composition of marine microbial populations and developing a better understanding of the interplay between the functional genome content of microbial communities and abiotic factors. Here we present a comprehensive analysis of 24 datasets covering surface and depth-related environments at 11 sites around the world's oceans. The complete datasets comprises approximately 12 million sequences, totaling 5,358 Mb. Based on profiling patterns of Clusters of Orthologous Groups (COGs of proteins, a core set of reference photic and aphotic depth-related COGs, and a collection of COGs that are associated with extreme oxygen limitation were defined. Their inferred functions were utilized as indicators to characterize the distribution of light- and oxygen-related biological activities in marine environments. The results reveal that, while light level in the water column is a major determinant of phenotypic adaptation in marine microorganisms, oxygen concentration in the aphotic zone has a significant impact only in extremely hypoxic waters. Phylogenetic profiling of the reference photic/aphotic gene sets revealed a greater variety of source organisms in the aphotic zone, although the majority of individual photic and aphotic depth-related COGs are assigned to the same taxa across the different sites. This increase in phylogenetic and functional diversity of the core aphotic related COGs most probably reflects selection for the utilization of a broad range of alternate energy sources in the absence of light.

  20. A predictive model of iron oxide nanoparticles flocculation tuning Z-potential in aqueous environment for biological application

    Energy Technology Data Exchange (ETDEWEB)

    Baldassarre, Francesca, E-mail: francesca.baldassarre@unisalento.it [University of Salento, Department of Cultural Heritage (Italy); Cacciola, Matteo, E-mail: matteo.cacciola@unirc.it [University “Mediterranea” of Reggio Calabria, DICEAM (Italy); Ciccarella, Giuseppe, E-mail: giuseppe.ciccarella@unisalento.it [University of Salento, Department of Innovation Engineering (Italy)

    2015-09-15

    Iron oxide nanoparticles are the most used magnetic nanoparticles in biomedical and biotechnological field because of their nontoxicity respect to the other metals. The investigation of iron oxide nanoparticles behaviour in aqueous environment is important for the biological applications in terms of polydispersity, mobility, cellular uptake and response to the external magnetic field. Iron oxide nanoparticles tend to agglomerate in aqueous solutions; thus, the stabilisation and aggregation could be modified tuning the colloids physical proprieties. Surfactants or polymers are often used to avoid agglomeration and increase nanoparticles stability. We have modelled and synthesised iron oxide nanoparticles through a co-precipitation method, in order to study the influence of surfactants and coatings on the aggregation state. Thus, we compared experimental results to simulation model data. The change of Z-potential and the clusters size were determined by Dynamic Light Scattering. We developed a suitable numerical model to predict the flocculation. The effects of Volume Mean Diameter and fractal dimension were explored in the model. We obtained the trend of these parameters tuning the Z-potential. These curves matched with the experimental results and confirmed the goodness of the model. Subsequently, we exploited the model to study the influence of nanoparticles aggregation and stability by Z-potential and external magnetic field. The highest Z-potential is reached up with a small external magnetic influence, a small aggregation and then a high suspension stability. Thus, we obtained a predictive model of Iron oxide nanoparticles flocculation that will be exploited for the nanoparticles engineering and experimental setup of bioassays.

  1. A predictive model of iron oxide nanoparticles flocculation tuning Z-potential in aqueous environment for biological application

    International Nuclear Information System (INIS)

    Iron oxide nanoparticles are the most used magnetic nanoparticles in biomedical and biotechnological field because of their nontoxicity respect to the other metals. The investigation of iron oxide nanoparticles behaviour in aqueous environment is important for the biological applications in terms of polydispersity, mobility, cellular uptake and response to the external magnetic field. Iron oxide nanoparticles tend to agglomerate in aqueous solutions; thus, the stabilisation and aggregation could be modified tuning the colloids physical proprieties. Surfactants or polymers are often used to avoid agglomeration and increase nanoparticles stability. We have modelled and synthesised iron oxide nanoparticles through a co-precipitation method, in order to study the influence of surfactants and coatings on the aggregation state. Thus, we compared experimental results to simulation model data. The change of Z-potential and the clusters size were determined by Dynamic Light Scattering. We developed a suitable numerical model to predict the flocculation. The effects of Volume Mean Diameter and fractal dimension were explored in the model. We obtained the trend of these parameters tuning the Z-potential. These curves matched with the experimental results and confirmed the goodness of the model. Subsequently, we exploited the model to study the influence of nanoparticles aggregation and stability by Z-potential and external magnetic field. The highest Z-potential is reached up with a small external magnetic influence, a small aggregation and then a high suspension stability. Thus, we obtained a predictive model of Iron oxide nanoparticles flocculation that will be exploited for the nanoparticles engineering and experimental setup of bioassays

  2. Corrosion characteristics of seven metals in three aqueous environments for forensic applications

    Science.gov (United States)

    Tong, Tianqi

    Corrosion characteristics of seven varieties of metals---zinc, brass C260, stainless steel 302, stainless steel 316, stainless steel 420, stainless steel 430, and stainless steel 440---in three aqueous media---Atlantic Ocean, Charles River, and deionized waters---were assessed via mass loss methods over 32 weeks, with supplemental data in the form of photomicrographic records. Concurrently, tests were conducted to determine the degree of measurement error resulting from the analytical scale used during corrosion assessment. This was accomplished by using reference samples of each type of metal and a glass vial as the container that held the metal and water samples. These error tests indicated that while the mass error associated with the metal samples was low, the error in mass associated with the vial displayed error margins two orders of magnitude larger than the error margins for the smaller metal samples. Further, control tests and statistical analysis indicated that this variation was the result of some quality inherent to the vial. The metal samples involved in the corrosion assessment experiment generally displayed corrosion characteristics in agreement with trends reported in the literature. Zinc produced the greatest quantity of corrosion residues out of all the metals studied. Brass C260 also developed visible corrosion. For example, brass C260 developed dark green/brown adherent residue and whitish blue-tinted nonadherent residue in Atlantic Ocean water, faint greenish tarnishing and some dark green spots and dots over time in Charles River water, and only faint greenish tarnish in deionized water. In contrast with zinc and brass C260, the stainless steels did not exhibit signs of significant corrosion rates excepting stainless steel 420 (SS420), which displayed pitted features surrounded by multi-colored rings on all of its Atlantic Ocean immersion samples and 25% of its Charles River immersion samples. Atlantic Ocean water generally caused the greatest

  3. Tungstate as a synergist to phosphonate-based formulation for corrosion control of carbon steel in nearly neutral aqueous environment

    Indian Academy of Sciences (India)

    B V Appa Rao; M Venkateswara Rao; S Srinivasa Rao; B Sreedhar

    2010-07-01

    Synergistic inhibition of corrosion of carbon steel in low chloride aqueous medium using tungstate as a synergist in combination with ,-(phosphonomethyl) glycine (BPMG) and zinc ions is presented. The synergistic action of tungstate has been established through the present studies. The new ternary inhibitor formulation is effective in neutral and slightly acidic as well as slightly alkaline media. Potentiodynamic polarisation studies inferred that the formulation functions as a mixed inhibitor. Impedance studies of the metal/solution interface revealed that the surface film is highly protective. Characterisation by X-ray photoelectron spectroscopy (XPS) of the surface film formed in presence of the inhibitor revealed the presence of iron, phosphorus, nitrogen, oxygen, carbon, zinc and tungsten in the surface film. The chemical shifts in the binding energies of these elements inferred that the surface film is composed of iron oxides/hydroxides, zinc hydroxide, heteropolynuclear complex [Fe(III), Zn(II)-BPMG] and WO3. Reflection absorption FTIR spectroscopic studies also supported the presence of these compounds in the surface film. Morphological features of the metal surface studied in the absence and presence of the inhibitor by scanning electron microscopy (SEM) are also presented. Based on all these results, a plausible mechanism of corrosion inhibition is proposed.

  4. Design of a Multisensory Probe for Measuring Carbon Cycle Processes in Aqueous Subterranean Environments

    Energy Technology Data Exchange (ETDEWEB)

    McIntyre, Timothy J [ORNL; Kisner, Roger [ORNL; Woodworth, Ken [ORNL; Lenarduzzi, Roberto [ORNL; Frank, Steven Shane [ORNL; McKnight, Timothy E [ORNL

    2015-01-01

    The global carbon cycle describes the exchange of carbon between the atmosphere, terrestrial vegetation, oceans, and soil. Mechanisms involving carbon in sub-terrestrial ecosystems and their impact on climate are not well understood. This lack of understanding limits current climate models and prevents accurate soil-carbon storage predications for future climate conditions. To address the lack of instrumentation for conducting high fidelity measurements of appropriate parameters in the field, a multi-sensory probe using a mix of optical, fiber optic, and electronic technologies to measure CO2, temperature, dissolved oxygen, redox potential, and water level in subsurface environments has been developed. Details of the design, fabrication and laboratory performance verification are presented. Use cases and the anticipated impacts of such measurements on climate models are discussed.

  5. Uranium(VI) remediation from aqueous environment using impregnated cellulose beads

    International Nuclear Information System (INIS)

    Use of cellulose based adsorbents for post treatment of contaminated water provides significant removal and recovery of trace quantities of radioactive and highly toxic U(VI) ions. Efficiency of the adsorbent was enhanced by impregnation of nano Fe2O3. Variables considered for obtaining optimized process conditions were solution pH, adsorbent dosage, initial metal ion concentration, additive content and contact time. The batch adsorption study revealed highly pH dependent adsorption with 100% adsorption efficiency at pH 7 using 1.5 g of adsorbent impregnated with 6 wt% Fe2O3 for 50 mL solution capacity in 150 min. The adsorption capacity was noted to be 7.6 mg/g. The adsorption mechanism was studied at pH 7 maintained using dilute ammonia solution to prevent the effect of any interfering cation. Uptake of U(VI) was found to be predominately via an intraparticle diffusion mechanism following pseudo second-order kinetic model, which is clearly reflected from the non-spontaneous thermodynamics yielding a positive free energy value. Recovery of the adsorbed U(VI) ions was highly feasible using 0.05 N HNO3 and the regeneration of the adsorbent using 0.01 N NaOH. - Highlights: • Effective removal of U(VI) in 2 h • Chemisorption following Langmuir and Freundlich Isotherm. • Pseudo second-order and intraparticle diffusion controls sorption kinetics. • Cost effective adsorbents for batch process

  6. Fatigue Crack Propagation from Notched Specimens of 304 SS in elevated Temperature Aqueous Environment

    Energy Technology Data Exchange (ETDEWEB)

    Wire, G. L.; Mills, W. J.

    2002-08-01

    Fatigue crack propagation (FCP) rates for 304 stainless steel (304SS) were determined in 24 degree C and 288 degree C air and 288 degree C water using double-edged notch (DEN) specimens of 304 stainless steel (304 SS). Test performed at matched loading conditions in air and water at 288 degree C with 20-6- cc h[sub]2/kg h[sub]2O provided a direct comparison of the relative crack growth rates in air and water over a wide range of crack growth rates. The DEN crack extension ranged from short cracks (0.03-0.25 mm) to long cracks up to 4.06 mm, which are consistent with conventional deep crack tests. Crack growth rates of 304 SS in water were about 12 times the air rate. This 12X environmental enhancement persisted to crack extensions up to 4.06 mm, far outside the range associated with short crack effects. The large environmental degradation for 304 SS crack growth is consistent with the strong reduction of fatigue life in high hydrogen water. Further, very similar environmental effects w ere reported in fatigue crack growth tests in hydrogen water chemistry (HWC). Most literature data in high hydrogen water show only a mild environmental effect for 304 SS, of order 2.5 times air or less, but the tests were predominantly performed at high cyclic stress intensity or equivalently, high air rates. The environmental effect in low oxygen environments at low stress intensity depends strongly on both the stress ratio, R, and the load rise time, T[sub]r, as recently reported for austenitic stainless steel in BWR water. Fractography was performed for both tests in air and water. At 288 degree C in water, the fracture surfaces were crisply faceted with a crystallographic appearance, and showed striations under high magnification. The cleavage-like facets on the fracture surfaces suggest that hydrogen embrittlement is the primary cause of accelerated cracking.

  7. A microfluidic device for the continuous culture and analysis of Caenorhabditis elegans in a toxic aqueous environment

    International Nuclear Information System (INIS)

    The nematode Caenorhabditis elegans (C. elegans) receives attention as a bioindicator, and the C. elegans condition has been recently analyzed using microfluidic devices equipped with an imaging system. To establish a method without an imaging system, we have proposed a novel microfluidic device with which to analyze the condition of C. elegans from the capacitance change using a pair of micro-electrodes. The device was designed to culture C. elegans, to expose C. elegans to an external stimulus, such as a chemical or toxicant, and to measure the capacitance change which indicates the condition of C. elegans. In this study, to demonstrate the capability of our device in a toxic aqueous environment, the device was applied to examine the effect of cadmium on C. elegans. Thirty L4 larval stage C. elegans were divided into three groups. One group was a control group and the other groups were exposed to cadmium solutions with concentrations of 5% and 10% LC50 for 24 h. The capacitance change and the body volume of C. elegans as a reference were measured four times and we confirmed the correlation between them. It shows that our device can analyze the condition of C. elegans without an imaging system. (paper)

  8. Structural Evolution of Molybdenum Carbides in Hot Aqueous Environments and Impact on Low-Temperature Hydroprocessing of Acetic Acid

    Directory of Open Access Journals (Sweden)

    Jae-Soon Choi

    2015-03-01

    Full Text Available We investigated the structural evolution of molybdenum carbides subjected to hot aqueous environments and their catalytic performance in low-temperature hydroprocessing of acetic acid. While bulk structures of Mo carbides were maintained after aging in hot liquid water, a portion of carbidic Mo sites were converted to oxidic sites. Water aging also induced changes to the non-carbidic carbon deposited during carbide synthesis and increased surface roughness, which in turn affected carbide pore volume and surface area. The extent of these structural changes was sensitive to the initial carbide structure and was lower under actual hydroprocessing conditions indicating the possibility of further improving the hydrothermal stability of Mo carbides by optimizing catalyst structure and operating conditions. Mo carbides were active in acetic acid conversion in the presence of liquid water, their activity being comparable to that of Ru/C. The results suggest that effective and inexpensive bio-oil hydroprocessing catalysts could be designed based on Mo carbides, although a more detailed understanding of the structure-performance relationships is needed, especially in upgrading of more complex reaction mixtures or real bio-oils.

  9. 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.

  10. Photovoice as a Method for Revealing Community Perceptions of the Built and Social Environment

    Science.gov (United States)

    Nykiforuk, Candace I.J.; Vallianatos, Helen; Nieuwendyk, Laura M.

    2016-01-01

    Over the last number of years there has been growing interest in the use of community-based participatory research (CBPR) for preventing and controlling complex public health problems. Photovoice is one of several qualitative methods utilized in CBPR, as it is a participatory method that has community participants use photography, and stories about their photographs, to identify and represent issues of importance to them. Over the past several years photovoice methodology has been frequently used to explore community health and social issues. One emerging opportunity for the utilization of photovoice methodology is research on community built and social environments, particularly when looking at the context of the neighbourhood. What is missing from the current body of photovoice literature is a critique of the strengths and weaknesses of photovoice as a method for health promotion research (which traditionally emphasizes capacity-building, community-based approaches) and as a method for revealing residents’ perceptions of community as a source of health opportunities or barriers. This paper will begin to address this gap by discussing the successes and challenges of using the photovoice methodology in a recent CBPR project to explore community perceptions of the built and social environment (with the ultimate goal of informing community-based chronic disease prevention initiatives). The paper concludes with methodological recommendations and directions for future research.

  11. The electromagnetic environment of Magnetic Resonance Imaging systems. Occupational exposure assessment reveals RF harmonics

    Science.gov (United States)

    Gourzoulidis, G.; Karabetsos, E.; Skamnakis, N.; Kappas, C.; Theodorou, K.; Tsougos, I.; Maris, T. G.

    2015-09-01

    Magnetic Resonance Imaging (MRI) systems played a crucial role in the postponement of the former occupational electromagnetic fields (EMF) European Directive (2004/40/EC) and in the formation of the latest exposure limits adopted in the new one (2013/35/EU). Moreover, the complex MRI environment will be finally excluded from the implementation of the new occupational limits, leading to an increased demand for Occupational Health and Safety (OHS) surveillance. The gradient function of MRI systems and the application of the RF excitation frequency result in low and high frequency exposures, respectively. This electromagnetic field exposure, in combination with the increased static magnetic field exposure, makes the MRI environment a unique case of combined EMF exposure. The electromagnetic field levels in close proximity of different MRI systems have been assessed at various frequencies. Quality Assurance (QA) & safety issues were also faced. Preliminary results show initial compliance with the forthcoming limits in each different frequency band, but also revealed peculiar RF harmonic components, of no safety concern, to the whole range detected (20-1000MHz). Further work is needed in order to clarify their origin and characteristics.

  12. Adaptations to a Subterranean Environment and Longevity Revealed by the Analysis of Mole Rat Genomes

    Directory of Open Access Journals (Sweden)

    Xiaodong Fang

    2014-09-01

    Full Text Available Subterranean mammals spend their lives in dark, unventilated environments that are rich in carbon dioxide and ammonia and low in oxygen. Many of these animals are also long-lived and exhibit reduced aging-associated diseases, such as neurodegenerative disorders and cancer. We sequenced the genome of the Damaraland mole rat (DMR, Fukomys damarensis and improved the genome assembly of the naked mole rat (NMR, Heterocephalus glaber. Comparative genome analyses, along with the transcriptomes of related subterranean rodents, revealed candidate molecular adaptations for subterranean life and longevity, including a divergent insulin peptide, expression of oxygen-carrying globins in the brain, prevention of high CO2-induced pain perception, and enhanced ammonia detoxification. Juxtaposition of the genomes of DMR and other more conventional animals with the genome of NMR revealed several truly exceptional NMR features: unusual thermogenesis, an aberrant melatonin system, pain insensitivity, and unique processing of 28S rRNA. Together, these genomes and transcriptomes extend our understanding of subterranean adaptations, stress resistance, and longevity.

  13. Investigation the Efficiency of Electrolysis Process using 3 Dimensional Graphite Electrodes for Decolonization of Phenolphthalein and Phenol red from Aqueous Environments

    Directory of Open Access Journals (Sweden)

    Mohmmad Reza Massoudinejad

    2012-10-01

    Full Text Available Background and Objectives: The presence of chemical dyes in the water resources not only pollutes them, but also brings about death of organisms and serious indemnities to the environment through stopping oxygen production and preventing penetration of the sunlight. In this study, we investigated the efficiency of the electrolysis process for decolonization of phenolphthalein and phenol red from aqueous environment. Materials and Methods: The experiments were conducted in an electrochemical reactor having a working volume of 1 liter equipped with 2 graphite electrodes. This study was conducted at laboratory scale. Samples were prepared by dissolving two phenol red and phenolphthalein dyes in drinking water. Then, the effect of operating parameters such as voltage, inter-electrode distance, and NaCl concentration on the complete dye removal was determined considering optimum retention time using  Factorial variance analyses and the graphs were plotted using MS Excel software.Results: the results showed that the optimum conditions for completely removal of phenolphthalein was achieved applying a voltage of 48 V, the retention time of 9 minutes, 5 cm inter-electrode distance, and the salt concentration of 1.5 g/l, whereas, complete removal of phenol red was achieved applying a voltage of 48 V, the retention time of 8 minutes, 5 cm inter-electrode distance, and the salt concentration of 2 g/l. Under these conditions, COD removal efficiency for phenol red and phenolphthalein was 85 and 80 percent respectively.Conclusion: This study revealed that electrolysis process is an effective method to remove both phenolphthalein and phenol red dyes from effluent, because it can completely remove the dyes in a short time.

  14. Water structure at aqueous solution surfaces of atmospherically relevant dimethyl sulfoxide and methanesulfonic acid revealed by phase-sensitive sum frequency spectroscopy.

    Science.gov (United States)

    Chen, Xiangke; Allen, Heather C

    2010-11-25

    Interfacial water structures of aqueous dimethyl sulfoxide (DMSO) and methanesulfonic acid (MSA) were studied by Raman, infrared, and conventional and phase-sensitive vibrational sum frequency generation (VSFG) spectroscopies. Through isotopic dilution, we probed bulk water hydrogen bonding strength using the vibrational frequency of dilute OD in H(2)O. As indicated by the frequency shift of the OD frequency, it is shown that DMSO has little influence on the average water hydrogen bonding strength at low concentrations in contrast with an overall weakening effect for MSA. For the water structure at the surface of aqueous solutions, although conventional VSFG spectra suggest only slight structural changes with DMSO and a red shift of hydrogen-bonded water OH frequency, phase-sensitive VSFG reveals more thoroughly structural changes in the presence of both DMSO and MSA. In the case of DMSO, reorientation of interfacial water molecules with their hydrogens pointing up toward the oxygen of the S=O group is observed. For MSA, the interfacial water structure is affected by both the dissociated methanesulfonate anions and the hydronium ions residing at the surface. Both the methanesulfonate anions and the hydronium ions have surface preference; therefore, the electric double layer (EDL) formed at the surface is relatively thin, which leads to partial reorientation of interface water molecules with net orientation of water hydrogens up. Surface DMSO molecules are more effective at reorienting surface water relative to MSA molecules. PMID:21047087

  15. Chemistry variations of the secondary circuit aqueous environment reflected in the characteristics of the superficial films formed on the carbon steel components

    International Nuclear Information System (INIS)

    The aim of this paper is to establish correlations between the characteristics of the superficial films formed on the carbon steel components in operation conditions of the secondary circuit of the Cernavoda Nuclear Power Station (NPS) and the specific parameters of the aqueous environment in which these films were formed. The main parameters studied in this paper, specific to a secondary circuit environment, are: the value of pH and the substances used to control it and the oxygen concentration dissolved in the aqueous environment, respectively. These filmed samples by autoclaving were studied by: 1. X rays diffraction method; 2. metallographic microscopy and 3. electrochemical methods such as: potentiodynamic and electrochemical impedance spectroscopy (E.I.S). to establish the correlations between the characteristics of the superficial films and the chemistry of the aqueous environment from the secondary circuit. To create films on the carbon steel samples similarly with those formed on the components during the operation of the NPS secondary circuit, some samples of three types of carbon steel - SA106, SA508 and SA516 - were filmed by autoclaving at 260 deg. C (51 atm) in aqueous environments with given physical and chemical characteristics. Using descaling and gravimetric method, there were established the corrosion kinetics of the carbon steel samples, which include: 1. the global corrosion rate (mg/dm2/day); 2. the global corrosion products formed (mg/dm2); 3. the adherent corrosion film (mg/dm2); 4. the non-adherent corrosion products (mg/dm2), etc. (authors)

  16. The environment of the fast rotating star Achernar. III. Photospheric parameters revealed by the VLTI

    Science.gov (United States)

    Domiciano de Souza, A.; Kervella, P.; Moser Faes, D.; Dalla Vedova, G.; Mérand, A.; Le Bouquin, J.-B.; Espinosa Lara, F.; Rieutord, M.; Bendjoya, P.; Carciofi, A. C.; Hadjara, M.; Millour, F.; Vakili, F.

    2014-09-01

    Context. Rotation significantly impacts on the structure and life of stars. In phases of high rotation velocity (close to critical), the photospheric structure can be highly modified, and present in particular geometrical deformation (rotation flattening) and latitudinal-dependent flux (gravity darkening). The fastest known rotators among the nondegenerate stars close to the main sequence, Be stars, are key targets for studying the effects of fast rotation on stellar photospheres. Aims: We seek to determine the purely photospheric parameters of Achernar based on observations recorded during an emission-free phase (normal B phase). Methods: Several recent works proved that optical/IR long-baseline interferometry is the only technique able to sufficiently spatially resolve and measure photospheric parameters of fast rotating stars. We thus analyzed ESO-VLTI (PIONIER and AMBER) interferometric observations of Achernar to measure its photospheric parameters by fitting our physical model CHARRON using a Markov chain Monte Carlo method. This analysis was also complemented by spectroscopic, polarimetric, and photometric observations to investigate the status of the circumstellar environment of Achernar during the VLTI observations and to cross-check our model-fitting results. Results: Based on VLTI observations that partially resolve Achernar, we simultaneously measured five photospheric parameters of a Be star for the first time: equatorial radius (equatorial angular diameter), equatorial rotation velocity, polar inclination, position angle of the rotation axis projected on the sky, and the gravity darkening β coefficient (effective temperature distribution). The close circumstellar environment of Achernar was also investigated based on contemporaneous polarimetry, spectroscopy, and interferometry, including image reconstruction. This analysis did not reveal any important circumstellar contribution, so that Achernar was essentially in a normal B phase at least from mid

  17. Multiple oxygen tension environments reveal diverse patterns of transcriptional regulation in primary astrocytes.

    Directory of Open Access Journals (Sweden)

    Wayne Chadwick

    Full Text Available The central nervous system normally functions at O(2 levels which would be regarded as hypoxic by most other tissues. However, most in vitro studies of neurons and astrocytes are conducted under hyperoxic conditions without consideration of O(2-dependent cellular adaptation. We analyzed the reactivity of astrocytes to 1, 4 and 9% O(2 tensions compared to the cell culture standard of 20% O(2, to investigate their ability to sense and translate this O(2 information to transcriptional activity. Variance of ambient O(2 tension for rat astrocytes resulted in profound changes in ribosomal activity, cytoskeletal and energy-regulatory mechanisms and cytokine-related signaling. Clustering of transcriptional regulation patterns revealed four distinct response pattern groups that directionally pivoted around the 4% O(2 tension, or demonstrated coherent ascending/decreasing gene expression patterns in response to diverse oxygen tensions. Immune response and cell cycle/cancer-related signaling pathway transcriptomic subsets were significantly activated with increasing hypoxia, whilst hemostatic and cardiovascular signaling mechanisms were attenuated with increasing hypoxia. Our data indicate that variant O(2 tensions induce specific and physiologically-focused transcript regulation patterns that may underpin important physiological mechanisms that connect higher neurological activity to astrocytic function and ambient oxygen environments. These strongly defined patterns demonstrate a strong bias for physiological transcript programs to pivot around the 4% O(2 tension, while uni-modal programs that do not, appear more related to pathological actions. The functional interaction of these transcriptional 'programs' may serve to regulate the dynamic vascular responsivity of the central nervous system during periods of stress or heightened activity.

  18. Photolytic fate and genotoxicity of benzophenone-derived compounds and their photodegradation mixtures in the aqueous environment.

    Science.gov (United States)

    Kotnik, Kristina; Kosjek, Tina; Žegura, Bojana; Filipič, Metka; Heath, Ester

    2016-03-01

    This study investigates the environmental fate of eight benzophenone derivatives (the pharmaceutical ketoprofen, its phototransformation products 3-ethylbenzophenone and 3-acetylbenzophenone, and five benzophenone-type UV filters) by evaluating their photolytic behaviour. In addition, the genotoxicity of these compounds and the produced photodegradation mixtures was studied. Laboratory-scale irradiation experiments using a medium pressure UV lamp revealed that photodegradation of benzophenones follows pseudo-first-order kinetics. Ketoprofen was the most photolabile (t1/2 = 0.8 min), while UV filters were more resistant to UV light with t1/2 between 17 and 99 h. The compounds were also exposed to irradiation by natural sunlight and showed similar photostability as predicted under laboratory conditions. Solar photodegradation experiments were performed in distilled water, lake and seawater, and revealed that photosensitizers present in natural waters significantly affect the photolytic behaviour of the investigated compounds. In this case, the presence of lake water resulted in accelerated photodecomposition, while seawater showed different effects on photodegradation, depending on a compound. Further, it was shown that the transformation products of ketoprofen 3-ethylbenzophenone and 3-acetylbenzophenone were formed under environmental conditions when ketoprofen was exposed to natural sunlight. Genotoxicity testing of parent benzophenone compounds using the SOS/umuC assay revealed that UV filters exhibited weak genotoxic activity in the presence of a metabolic activation system, however the concentrations tested were much higher than found in the environment (≥125 μg mL(-1)). After irradiation of benzophenones, the produced photodegradation mixtures showed that, with the exception of benzophenone that exhibited weak genotoxic activity, all the other compounds tested did not elicit any activity when exposed to UV light. PMID:26766022

  19. Design of a Wireless Sensor Network for Long-term, In-Situ Monitoring of an Aqueous Environment

    Directory of Open Access Journals (Sweden)

    Craig A. Grimes

    2002-11-01

    Full Text Available An aqueous sensor network is described consisting of an array of sensor nodes that can be randomly distributed throughout a lake or drinking water reservoir. The data of an individual node is transmitted to the host node via acoustic waves using intermediate nodes as relays. Each node of the sensor network is a data router, and contains sensors capable of measuring environmental parameters of interest. Depending upon the required application, each sensor node can be equipped with different types of physical, biological or chemical sensors, allowing long-term, wide area, in situ multi-parameter monitoring. In this work the aqueous sensor network is described, with application to pH measurement using magnetoelastic sensors. Beyond ensuring drinking water safety, possible applications for the aqueous sensor network include advanced industrial process control, monitoring of aquatic biological communities, and monitoring of waste-stream effluents.

  20. Probing the elastic response of microalga Scenedesmus dimorphus in dry and aqueous environments through atomic force microscopy

    International Nuclear Information System (INIS)

    With the re-emergence of microalgae as a replacement feedstock for petroleum-derived oils, researchers are working to understand its chemical and mechanical behavior. In this work, the mechanical properties of microalgae, Scenedesmus dimorphus, were investigated at the subcellular level to determine the elastic response of cells that were in an aqueous and dried state using nano-scale indentation through atomic force microscopy. The elastic modulus of single-celled S. dimorphus cells increased over tenfold from an aqueous state to a dried state, which allows us to better understand the biophysical response of microalgae to stress.

  1. Probing the elastic response of microalga Scenedesmus dimorphus in dry and aqueous environments through atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Warren, K. M.; Mpagazehe, J. N.; Higgs, C. F., E-mail: prl@andrew.cmu.edu, E-mail: higgs@andrew.cmu.edu [Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213 (United States); LeDuc, P. R., E-mail: prl@andrew.cmu.edu, E-mail: higgs@andrew.cmu.edu [Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, Pennsylvania 15213 (United States); Departments of Biomedical Engineering and Biological Sciences, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213 (United States)

    2014-10-20

    With the re-emergence of microalgae as a replacement feedstock for petroleum-derived oils, researchers are working to understand its chemical and mechanical behavior. In this work, the mechanical properties of microalgae, Scenedesmus dimorphus, were investigated at the subcellular level to determine the elastic response of cells that were in an aqueous and dried state using nano-scale indentation through atomic force microscopy. The elastic modulus of single-celled S. dimorphus cells increased over tenfold from an aqueous state to a dried state, which allows us to better understand the biophysical response of microalgae to stress.

  2. Garlic, from Remedy to Stimulant: Evaluation of Antifungal Potential Reveals Diversity in Phytoalexin Allicin Content among Garlic Cultivars; Allicin Containing Aqueous Garlic Extracts Trigger Antioxidants in Cucumber.

    Science.gov (United States)

    Hayat, Sikandar; Cheng, Zhihui; Ahmad, Husain; Ali, Muhammad; Chen, Xuejin; Wang, Mengyi

    2016-01-01

    Garlic has the charisma of a potent remedy and holds its repute of a therapeutic panacea since the dawn of civilization. An integrated approach was adopted to evaluate the genetic diversity among Chinese garlic cultivars for their antifungal potency as well as allicin content distribution and, furthermore; a bioassay was performed to study the bio-stimulation mechanism of aqueous garlic extracts (AGE) in the growth and physiology of cucumber (Cucumis sativus). Initially, 28 garlic cultivars were evaluated against four kinds of phytopathogenic fungi; Fusarium oxysporum, Botrytis cinerea, Verticillium dahliae and Phytophthora capsici, respectively. A capricious antifungal potential among the selected garlic cultivars was observed. HPLC fingerprinting and quantification confirmed diversity in allicin abundance among the selected cultivars. Cultivar G025, G064, and G074 had the highest allicin content of 3.98, 3.7, and 3.66 mg g(-1), respectively, whereas G110 was found to have lowest allicin content of 0.66 mg g(-1). Cluster analysis revealed three groups on the basis of antifungal activity and allicin content among the garlic cultivars. Cultivar G025, G2011-4, and G110 were further evaluated to authenticate the findings through different solvents and shelf life duration and G025 had the strongest antifungal activity in all conditions. minimum inhibitory concentration and minimum fungicidal concentration of Allicin aqueous standard (AAS) and AGE showed significant role of allicin as primary antifungal substance of AGE. Leaf disk bioassay against P. capsici and V. dahliae to comparatively study direct action of AGE and AAS during infection process employing eggplant and pepper leaves showed a significant reduction in infection percentage. To study the bioactivity of AGE, a bioassay was performed using cucumber seedlings and results revealed that AGE is biologically active inside cucumber seedlings and alters the defense mechanism of the plant probably activating

  3. What the Cited and Citing Environments Reveal of "Advances in Atmospheric Sciences"?

    OpenAIRE

    Aolan, Shi; Leydesdorff, Loet

    2010-01-01

    The networking ability of journals reflects their academic influence among peer journals. This paper analyzes the cited and citing environments of the journal--Advances in Atmospheric Sciences--using methods from social network analysis. The journal has been actively participating in the international journal environment, but one has a tendency to cite papers published in international journals. Advances in Atmospheric Sciences is intensely interrelated with international peer journals in ter...

  4. Mechanisms of Copper Corrosion in Aqueous Environments. A report from the Swedish National Council for Nuclear Waste's scientific workshop, on November 16, 2009

    International Nuclear Information System (INIS)

    In 2010 the Swedish Nuclear Fuel and Waste Management Company, SKB, plans to submit its license application for the final repository of spent nuclear fuel. The proposed method is the so-called KBS-3 method and implies placing the spent nuclear fuel in copper canisters, surrounded by a buffer of bentonite clay, at 500 m depth in the bedrock. The site selected by SKB to host the repository is located in the municipality of Oesthammar on the Swedish east coast. The copper canister plays a key role in the design of the repository for spent nuclear fuel in Sweden. The long-term physical and chemical stability of copper in aqueous environments is fundamental for the safety evolution of the proposed disposal concept. However, the corrosion resistance of copper has been questioned by results obtained under anoxic conditions in aqueous solution. These observations caused some head-lines in the Swedish newspapers as well as public and political concerns. Consequently, the Swedish National Council for Nuclear Waste organized a scientific workshop on the issue 'Mechanisms of Copper Corrosion in Aqueous Environments'. The purpose of the workshop was to address the fundamental understanding of the corrosion characteristics of copper regarding oxygen-free environments, and to identify what additional information is needed to assess the validity of the proposed corrosion mechanism and its implication on the containment of spent nuclear fuel in a copper canister. This seminar report is based on the presentations and discussions at the workshop. It also includes written statements by the members of the expert panel

  5. Mechanisms of Copper Corrosion in Aqueous Environments. A report from the Swedish National Council for Nuclear Waste's scientific workshop, on November 16, 2009

    Energy Technology Data Exchange (ETDEWEB)

    2010-07-01

    In 2010 the Swedish Nuclear Fuel and Waste Management Company, SKB, plans to submit its license application for the final repository of spent nuclear fuel. The proposed method is the so-called KBS-3 method and implies placing the spent nuclear fuel in copper canisters, surrounded by a buffer of bentonite clay, at 500 m depth in the bedrock. The site selected by SKB to host the repository is located in the municipality of Oesthammar on the Swedish east coast. The copper canister plays a key role in the design of the repository for spent nuclear fuel in Sweden. The long-term physical and chemical stability of copper in aqueous environments is fundamental for the safety evolution of the proposed disposal concept. However, the corrosion resistance of copper has been questioned by results obtained under anoxic conditions in aqueous solution. These observations caused some head-lines in the Swedish newspapers as well as public and political concerns. Consequently, the Swedish National Council for Nuclear Waste organized a scientific workshop on the issue 'Mechanisms of Copper Corrosion in Aqueous Environments'. The purpose of the workshop was to address the fundamental understanding of the corrosion characteristics of copper regarding oxygen-free environments, and to identify what additional information is needed to assess the validity of the proposed corrosion mechanism and its implication on the containment of spent nuclear fuel in a copper canister. This seminar report is based on the presentations and discussions at the workshop. It also includes written statements by the members of the expert panel

  6. Design of a Wireless Sensor Network for Long-term, In-Situ Monitoring of an Aqueous Environment

    OpenAIRE

    Grimes, Craig A.; Casey S. Mungle; Kefeng Zeng; William R. Dreschel; Ong, Keat G.; Xiping Yang

    2002-01-01

    An aqueous sensor network is described consisting of an array of sensor nodes that can be randomly distributed throughout a lake or drinking water reservoir. The data of an individual node is transmitted to the host node via acoustic waves using intermediate nodes as relays. Each node of the sensor network is a data router, and contains sensors capable of measuring environmental parameters of interest. Depending upon the required application, each sensor node can be equipped with different ty...

  7. An efficient and sensitive fluorescent pH sensor based on amino functional metal-organic frameworks in aqueous environment.

    Science.gov (United States)

    Xu, Xiao-Yu; Yan, Bing

    2016-04-19

    A pH sensor is fabricated via a reaction between an Al(III) salt and 2-aminoterephthalic acid in DMF which leads to a MOF (Al-MIL-101-NH2) with free amino groups. The Al-MIL-101-NH2 samples show good luminescence and an intact structure in aqueous solutions with pH ranging from 4.0 to 7.7. Given its exceptional stability and pH-dependent fluorescence intensity, Al-MIL-101-NH2 has been applied to fluorescent pH sensing. Significantly, in the whole experimental pH range (4.0-7.7), the fluorescence intensity almost increases with increasing pH (R(2) = 0.99688) which can be rationalized using a linear equation: I = 2.33 pH + 26.04. In addition, error analysis and cycling experiments have demonstrated the accuracy and utilizability of the sensor. In practical applications (PBS and lake water), Al-MIL-101-NH2 also manifests its analytical efficiency in pH sensing. And the samples can be easily isolated from an aqueous solution by incorporating Fe3O4 nanoparticles. Moreover, the possible sensing mechanism based on amino protonation is discussed in detail. This work is on of the few cases for integrated pH sensing systems in aqueous solution based on luminescent MOFs. PMID:27002862

  8. How Revealing Rankings Affects Student Attitude and Performance in a Peer Review Learning Environment

    DEFF Research Database (Denmark)

    Papadopoulos, Pantelis M.; Lagkas, Thomas D.; Demetriadis, Stavros N.

    2016-01-01

    This paper investigates the possible benefits as well as the overall impact on the behaviour of students within a learning environment, which is based on double-blinding reviewing of freely selected peer works. Fifty-six sophomore students majoring in Informatics and Telecommunications Engi-neeri...

  9. How Revealing Rankings Affects Student Attitude and Performance in a Peer Review Learning Environment

    DEFF Research Database (Denmark)

    Papadopoulos, Pantelis M.; Lagkas, Thomas D.; Demetriadis, Stavros N.

    2015-01-01

    This paper investigates the possible benefits as well as the overall impact on the behaviour of students within a learning environment, which is based on double-blinding reviewing of freely selected peer works. Fifty-six sophomore students majoring in Informatics and Telecommunications Engi......-neering volunteered to participate in the study. The experiment was conducted in a controlled environment, according to which students were divided into three groups of different conditions: control, usage data, usage and ranking data. No additional information was made available to students in the control condition....... The students that participated in the other two conditions were provided with their usage information (logins, peer work viewed/reviewed, etc.), while members of the last group could also have access to ranking information about their positioning in their group, based on their usage data. According to...

  10. Salt resistance genes revealed by functional metagenomics from brines and moderate-salinity rhizosphere within a hypersaline environment

    OpenAIRE

    Salvador eMirete; Mora-Ruiz, Merit R.; María eLamprecht-Grandío; de Figueras, Carolina G.; Ramon eRosselló-Móra; José Eduardo González-Pastor

    2015-01-01

    Hypersaline environments are considered one of the most extreme habitats on earth and microorganisms have developed diverse molecular mechanisms of adaptation to withstand these conditions. The present study was aimed at identifying novel genes involved in salt resistance from the microbial communities of brines and the rhizosphere from the Es Trenc saltern (Mallorca, Spain). The microbial diversity assessed by pyrosequencing of 16S rRNA gene libraries revealed the presence of communities tha...

  11. Azospirillum genomes reveal transition of bacteria from aquatic to terrestrial environments.

    OpenAIRE

    Florence Wisniewski-Dyé; Kirill Borziak; Gurusahai Khalsa-Moyers; Gladys Alexandre; Sukharnikov, Leonid O.; Kristin Wuichet; Gregory B Hurst; W Hayes McDonald; Robertson, Jon S.; Valérie Barbe; Alexandra Calteau; Zoé Rouy; Sophie Mangenot; Claire Prigent-Combaret; Philippe Normand

    2011-01-01

    International audience Fossil records indicate that life appeared in marine environments ∼3.5 billion years ago (Gyr) and transitioned to terrestrial ecosystems nearly 2.5 Gyr. Sequence analysis suggests that "hydrobacteria" and "terrabacteria" might have diverged as early as 3 Gyr. Bacteria of the genus Azospirillum are associated with roots of terrestrial plants; however, virtually all their close relatives are aquatic. We obtained genome sequences of two Azospirillum species and analyze...

  12. Azospirillum Genomes Reveal Transition of Bacteria from Aquatic to Terrestrial Environments

    OpenAIRE

    Wisniewski-Dye, Florence; Borziak, Kirill; Khalsa-Moyers, Gurusahai; Alexandre, Gladys; O.Sukharnikov, Leonid; Wuichet, Kristin; B. Hurst, Gregory; Hayes Mcdonald, W.; S. Robertson, Jon; Barbe, Valerie; Calteau, Alexandra; Rouy, Zoe; Mangenot, Sophie; Prigent-Combaret, Claire; Normand, Philippe

    2011-01-01

    Fossil records indicate that life appeared in marine environments ∼3.5 billion years ago (Gyr) and transitioned to terrestrial ecosystems nearly 2.5 Gyr. Sequence analysis suggests that "hydrobacteria" and "terrabacteria" might have diverged as early as 3 Gyr. Bacteria of the genus Azospirillum are associated with roots of terrestrial plants; however, virtually all their close relatives are aquatic. We obtained genome sequences of two Azospirillum species and analyzed their gene origins. Whil...

  13. Comparative Genomics Analysis of Streptomyces Species Reveals Their Adaptation to the Marine Environment and Their Diversity at the Genomic Level

    Science.gov (United States)

    Tian, Xinpeng; Zhang, Zhewen; Yang, Tingting; Chen, Meili; Li, Jie; Chen, Fei; Yang, Jin; Li, Wenjie; Zhang, Bing; Zhang, Zhang; Wu, Jiayan; Zhang, Changsheng; Long, Lijuan; Xiao, Jingfa

    2016-01-01

    Over 200 genomes of streptomycete strains that were isolated from various environments are available from the NCBI. However, little is known about the characteristics that are linked to marine adaptation in marine-derived streptomycetes. The particularity and complexity of the marine environment suggest that marine streptomycetes are genetically diverse. Here, we sequenced nine strains from the Streptomyces genus that were isolated from different longitudes, latitudes, and depths of the South China Sea. Then we compared these strains to 22 NCBI downloaded streptomycete strains. Thirty-one streptomycete strains are clearly grouped into a marine-derived subgroup and multiple source subgroup-based phylogenetic tree. The phylogenetic analyses have revealed the dynamic process underlying streptomycete genome evolution, and lateral gene transfer is an important driving force during the process. Pan-genomics analyses have revealed that streptomycetes have an open pan-genome, which reflects the diversity of these streptomycetes and guarantees the species a quick and economical response to diverse environments. Functional and comparative genomics analyses indicate that the marine-derived streptomycetes subgroup possesses some common characteristics of marine adaptation. Our findings have expanded our knowledge of how ocean isolates of streptomycete strains adapt to marine environments. The availability of streptomycete genomes from the South China Sea will be beneficial for further analysis on marine streptomycetes and will enrich the South China Sea’s genetic data sources. PMID:27446038

  14. Typification of Natural Seasonal Dynamics of Vegetation to Reveal Impact of Land Surface Change on Environment (by Satellite Data)

    Science.gov (United States)

    Shevyrnogov, A.; Vysotskaya, G.; Sidko, A.; Dunaev, K.

    Deep insight into types of vegetation variability provided by AVHRR space scanner images of vegetation index spatial distribution helps reveal impact of land surface changes on environment.The Institute of Computational Modeling SB RAS has developed nonparametric algorithms of automatic to classify and recognize patterns of these images which helped to reveal: (1) major variability types (generally connected); (2) areas belonging to small classes, which can be used to reveal deviations from ``normal'' (e.g., forest fires, etc.); (3) deviation from a certain type of dynamics indicative of changes in condition of plants, which can be used to diagnose pathology at early stages; (4) impact of economical activities on vegetation in Norilsk area. The authors provide biological interpretation of the satellite data. Computer-animated dynamics and color maps are presented. Nonparametric algorithms of an automatic classification and pattern recognition were provided by the Institute of Computational Modeling SB RAS

  15. Electrochemical, computational and spectroscopic investigation on local environment of plutonium in ionic liquid and aqueous medium. A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, Arijit; Murali, Mallekav S.; Mohapatra, Prasanta Kumar [Bhabha Atomic Research Centre Trombay, Mumbai (India). Radiochemistry Div.; Ali, Sk. Musharaf; Shenoy, Kalsanka Trivikram [Bhabha Atomic Research Centre Trombay, Mumbai (India). Chemical Engineering Div.

    2016-07-01

    With an aim to understand the nature of species, cyclic voltammetry (CV) of Pu(IV) in dilute HBr and in a room temperature ionic liquid (RTIL), 1-octyl-3-methylimidazolium bromide (C{sub 8}mimBr) was carried out. Shifts of cathodic and anodic peak potentials of Pu(IV) cyclic voltammograms were observed towards negative potentials in the extended electrochemical window for ionic liquid medium compared to 2 M HBr. The diffusion coefficient of the most likely species of Pu(IV) in aqueous medium was found to be greater than that of the corresponding species in ionic liquid while the activation energy showed reverse trend. The Pu(IV)/Pu(III) redox reaction was found to be exothermic in aqueous medium while it was endothermic in C{sub 8}mimBr. The redox reaction was found to be quasi reversible for both the media while the extent of irreversibility was more in ionic liquid. UV-Vis spectroscopy of Pu in these media showed significant differences in the peak positions and their relative intensities, indicating the possible differences in the interactions of Pu(IV) with the solvent molecules resulting in speciation differences. A new prominent peak was observed in RTIL which could be for a new species of Pu(IV). Computational studies were also carried out to understand the solvation of Pu and the possibility of thermodynamic conversion from Pu(IV) to Pu(III).

  16. Electrochemical, computational and spectroscopic investigation on local environment of plutonium in ionic liquid and aqueous medium. A comparative study

    International Nuclear Information System (INIS)

    With an aim to understand the nature of species, cyclic voltammetry (CV) of Pu(IV) in dilute HBr and in a room temperature ionic liquid (RTIL), 1-octyl-3-methylimidazolium bromide (C8mimBr) was carried out. Shifts of cathodic and anodic peak potentials of Pu(IV) cyclic voltammograms were observed towards negative potentials in the extended electrochemical window for ionic liquid medium compared to 2 M HBr. The diffusion coefficient of the most likely species of Pu(IV) in aqueous medium was found to be greater than that of the corresponding species in ionic liquid while the activation energy showed reverse trend. The Pu(IV)/Pu(III) redox reaction was found to be exothermic in aqueous medium while it was endothermic in C8mimBr. The redox reaction was found to be quasi reversible for both the media while the extent of irreversibility was more in ionic liquid. UV-Vis spectroscopy of Pu in these media showed significant differences in the peak positions and their relative intensities, indicating the possible differences in the interactions of Pu(IV) with the solvent molecules resulting in speciation differences. A new prominent peak was observed in RTIL which could be for a new species of Pu(IV). Computational studies were also carried out to understand the solvation of Pu and the possibility of thermodynamic conversion from Pu(IV) to Pu(III).

  17. Aging of TiO2 nanocomposites used in sunscreen. Dispersion and fate of the degradation products in aqueous environment

    International Nuclear Information System (INIS)

    Aging in water of a TiO2-based nanocomposite used in sunscreen cosmetics has been studied as a function of light and time. It consisted initially in a TiO2 core, coated with Al(OH)3 and polydimethylsiloxane (PDMS) layers. Size measurement, coating alteration, and surface charge were followed by laser diffraction, TEM/EDS, ICP-AES and electrophoretic mobility measurement. The nanocomposite rapidly underwent progressive dispersion in the aqueous phase, enabled by the dissolution of the PDMS layer. A stable suspension of colloidal byproducts from 50 to 700 nm in size was formed. Their positively charged Al(OH)3 surface was evidenced with an isoelectric point around 7-8, controlling the dispersion stability. The critical coagulation concentrations measured with NaCl and CaCl2 was 2 x 10-2 and 8 x 10-3 M respectively. The presence of natural organic matter affected the colloidal stability according to the NOM/byproduct ratio. A 2 wt% ratio favored bridging flocculation, whereas a 20 wt% ratio induced sterical stabilization. - Aging in aqueous conditions of TiO2 nanocomposite used in sunscreens induces rapid generation of nanometric byproducts remaining stable in suspension.

  18. Genotype × Environment Interactions for Agronomic Traits of Rice Revealed by Association Mapping

    Institute of Scientific and Technical Information of China (English)

    XU Fei-fei; TANG Fu-fu; SHAO Ya-fang; CHEN Ya-ling; TONG Chuan; BAO Jin-song

    2014-01-01

    Agronomic traits are important determinants to rice yield, which are controlled by complex genetic factors as well as genotype by environment (G × E) interaction effects. The G × E effects for agronomic traits of rice have been dissected with various approaches, but not with the current available approach, the association studies. In this study, a total of 32 655 single nucleotide polymorphisms were used to carry out associations with 14 agronomic traits among 20 rice accessions in two environments. The G × E interaction effects for all the agronomic traits were at highly significant levels (P<0.01), accounting for 3.4%-22.3% of the total sum of squares except for the length of brown rice. Twenty three putative quantitative trait loci (QTLs), including five previously known and several new promising associations, were identified for 10 of 14 traits. Analysis of the relationships between the traits for which QTLs and the genotype effects could be identified suggested that the higher the genotypic effect, the higher the possibility to identify QTLs for the given trait. The new QTLs detected in this study will facilitate dissection of the complex agronomic traits and may give insight into the G × E effects with association mapping.

  19. Azospirillum genomes reveal transition of bacteria from aquatic to terrestrial environments.

    Directory of Open Access Journals (Sweden)

    Florence Wisniewski-Dyé

    2011-12-01

    Full Text Available Fossil records indicate that life appeared in marine environments ∼3.5 billion years ago (Gyr and transitioned to terrestrial ecosystems nearly 2.5 Gyr. Sequence analysis suggests that "hydrobacteria" and "terrabacteria" might have diverged as early as 3 Gyr. Bacteria of the genus Azospirillum are associated with roots of terrestrial plants; however, virtually all their close relatives are aquatic. We obtained genome sequences of two Azospirillum species and analyzed their gene origins. While most Azospirillum house-keeping genes have orthologs in its close aquatic relatives, this lineage has obtained nearly half of its genome from terrestrial organisms. The majority of genes encoding functions critical for association with plants are among horizontally transferred genes. Our results show that transition of some aquatic bacteria to terrestrial habitats occurred much later than the suggested initial divergence of hydro- and terrabacterial clades. The birth of the genus Azospirillum approximately coincided with the emergence of vascular plants on land.

  20. Culture-dependent and culture-independent methods reveal diverse methylotrophic communities in terrestrial environments.

    Science.gov (United States)

    Eyice, Özge; Schäfer, Hendrik

    2016-01-01

    One-carbon compounds such as methanol, dimethylsulfide (DMS) and dimethylsulfoxide (DMSO) are significant intermediates in biogeochemical cycles. They are suggested to affect atmospheric chemistry and global climate. Methylotrophic microorganisms are considered as a significant sink for these compounds; therefore, we analyzed the diversity of terrestrial bacteria that utilize methanol, DMS and DMSO as carbon and energy source using culture-dependent and culture-independent methods. The effect of habitat type on the methylotrophic community structure was also investigated in rhizosphere and bulk soil. While thirteen strains affiliated to the genera Hyphomicrobium, Methylobacterium, Pseudomonas, Hydrogenophaga, Rhodococcus, Flavobacterium and Variovorax were isolated, denaturing gradient gel electrophoresis revealed the dominance of Thiobacillus, Rhodococcus, Flavobacterium and Bacteroidetes species. Furthermore, methylotrophic communities that degrade methanol or DMS are not shaped by terrestrial habitat type. Rhizosphere and soil samples showed dominance of Methylophilus spp. and Methylovorus spp. for methanol enrichments; Cytophaga spp., Pseudomonas tremae and Thiobacillus thioparus for DMS enrichments. PMID:26475353

  1. Genome sequence of the pattern forming Paenibacillus vortex bacterium reveals potential for thriving in complex environments

    Directory of Open Access Journals (Sweden)

    Leshkowitz Dena

    2010-12-01

    Full Text Available Abstract Background The pattern-forming bacterium Paenibacillus vortex is notable for its advanced social behavior, which is reflected in development of colonies with highly intricate architectures. Prior to this study, only two other Paenibacillus species (Paenibacillus sp. JDR-2 and Paenibacillus larvae have been sequenced. However, no genomic data is available on the Paenibacillus species with pattern-forming and complex social motility. Here we report the de novo genome sequence of this Gram-positive, soil-dwelling, sporulating bacterium. Results The complete P. vortex genome was sequenced by a hybrid approach using 454 Life Sciences and Illumina, achieving a total of 289× coverage, with 99.8% sequence identity between the two methods. The sequencing results were validated using a custom designed Agilent microarray expression chip which represented the coding and the non-coding regions. Analysis of the P. vortex genome revealed 6,437 open reading frames (ORFs and 73 non-coding RNA genes. Comparative genomic analysis with 500 complete bacterial genomes revealed exceptionally high number of two-component system (TCS genes, transcription factors (TFs, transport and defense related genes. Additionally, we have identified genes involved in the production of antimicrobial compounds and extracellular degrading enzymes. Conclusions These findings suggest that P. vortex has advanced faculties to perceive and react to a wide range of signaling molecules and environmental conditions, which could be associated with its ability to reconfigure and replicate complex colony architectures. Additionally, P. vortex is likely to serve as a rich source of genes important for agricultural, medical and industrial applications and it has the potential to advance the study of social microbiology within Gram-positive bacteria.

  2. Salt resistance genes revealed by functional metagenomics from brines and moderate-salinity rhizosphere within a hypersaline environment.

    Science.gov (United States)

    Mirete, Salvador; Mora-Ruiz, Merit R; Lamprecht-Grandío, María; de Figueras, Carolina G; Rosselló-Móra, Ramon; González-Pastor, José E

    2015-01-01

    Hypersaline environments are considered one of the most extreme habitats on earth and microorganisms have developed diverse molecular mechanisms of adaptation to withstand these conditions. The present study was aimed at identifying novel genes from the microbial communities of a moderate-salinity rhizosphere and brine from the Es Trenc saltern (Mallorca, Spain), which could confer increased salt resistance to Escherichia coli. The microbial diversity assessed by pyrosequencing of 16S rRNA gene libraries revealed the presence of communities that are typical in such environments and the remarkable presence of three bacterial groups never revealed as major components of salt brines. Metagenomic libraries from brine and rhizosphere samples, were transferred to the osmosensitive strain E. coli MKH13, and screened for salt resistance. Eleven genes that conferred salt resistance were identified, some encoding for well-known proteins previously related to osmoadaptation such as a glycerol transporter and a proton pump, whereas others encoded proteins not previously related to this function in microorganisms such as DNA/RNA helicases, an endonuclease III (Nth) and hypothetical proteins of unknown function. Furthermore, four of the retrieved genes were cloned and expressed in Bacillus subtilis and they also conferred salt resistance to this bacterium, broadening the spectrum of bacterial species in which these genes can function. This is the first report of salt resistance genes recovered from metagenomes of a hypersaline environment. PMID:26528268

  3. Last glacial maximum environments in northwestern Patagonia revealed by fossil small mammals

    Science.gov (United States)

    Tammone, Mauro N.; Hajduk, Adan; Arias, Pablo; Teta, Pablo; Lacey, Eileen A.; Pardiñas, Ulyses F. J.

    2014-07-01

    Comparisons of historical and modern assemblages of mammals can yield important insights into patterns and processes of environmental change. Here, we present the first analyses of small mammal assemblages present in northern Patagonia during the last glacial maximum (LGM). Using remains obtained from owl pellets excavated from an archeological cave site (Arroyo Corral I, levels VII-V, carbon dates of 22,400-21,530 cal yr BP), we generate estimates of the minimum number of individuals for all species detected; these estimates, in turn are used to determine relative species abundances. Comparisons of these data with similar analyses of small mammal remains obtained from a second archeological site (ACoII, levels IV-V, carbon dates of 10,010-9220 cal yr BP) as well as from modern owl pellets reveal pronounced changes in relative species abundance since the LGM. In particular, Euneomys chinchilloides and Ctenomys sociabilis - the predominant species during the LGM - declined markedly, suggesting a change from open, bare habitat punctuated by patches of wet meadows and shrubs to the more densely vegetated mosaic of ecotone habitats found in this region today. These data provide important new insights into the environmental changes that have occurred in northern Patagonia over the last 20,000 years.

  4. Effect of urea on bovine serum albumin in aqueous and reverse micelle environments investigated by small angle X-ray scattering, fluorescence and circular dichroism

    International Nuclear Information System (INIS)

    The influence that urea has on the conformation of water-soluble globular protein, bovine serum albumin (BSA), exposed directly to the aqueous solution as compared to the condition where the macromolecule is confined in the Aerosol-OT (AOT - sodium bis-2-ethylhexyl sulfosuccinate)/n-hexane/water reverse micelle (RM) is addressed. Small angle X-ray scattering (SAXS), tryptophan (Trp) fluorescence emission and circular dichroism (CD) spectra of aqueous BSA solution in the absence and in the presence of urea (3M and 5M) confirm the known denaturing effect of urea in proteins. The loss of the globular native structure is observed by the increase in the protein maximum dimension and gyration radius, through the Trp emission increase and maximum red-shift as well as the decrease in helix content. In RMs, the Trp fluorescence and CD spectra show that BSA is mainly located in its interfacial region independently of the micellar size. Addition of urea in this BSA/RM system also causes changes in the Trp fluorescence (emission decrease and maximum red-shift) and in the BSA CD spectra (decrease in helix content), which are compatible with the denaturation of the protein and Trp exposition to a more apolar environment in the RM. The fact that urea causes changes in the protein structure when it is located in the interfacial region (evidenced by CD) is interpreted as an indication that the direct interaction of urea with the protein is the major factor to explain its denaturing effect. (author)

  5. A multidisciplinary approach to reveal the Sicily Climate and Environment over the last 20 000 years

    Science.gov (United States)

    Incarbona, Alessandro; Zarcone, Giuseppe; Agate, Mauro; Bonomo, Sergio; Stefano, Enrico; Masini, Federico; Russo, Fabio; Sineo, Luca

    2010-06-01

    We present a thorough review of the knowledge on the climate and environment in Sicily over the last 20 000 years, taking into account results of several studies carried using terrestrial and marine records. We obtain a coherent framework of the most important changes succeeded in the island, even if some points need further investigation. All the reconstructions of surface temperatures of the seas and the air surrounding Sicily point out severe climatic conditions during the last glacial period. The steppe- and semisteppe-like vegetation pattern testifies, together with additional evidence from geochemical data of lacustrine evidence, markedly arid conditions. Fi-nally, significant episodes of sea level drop connected Sicily to the Italian Peninsula and favoured the dispersion of faunal elements from southern Italy. The transition between the last glacial and the Holocene was not characterized by a gradual warming but was punctuated by two abrupt suborbital climatic fluctuations: Bølling-Allerød (warm) and Younger Dryas (cold), as recognized in the sediments recovered close to the northern and southern coast of Sicily. A denser arboreal cover is possibly indicated by the occurrence of dormouse and Arvicola remains. Finally the sensitivity of Sicily to climate perturbations is demonstrated by the occurrence of repeated subtle climatic anomalies during the Holocene, including the Little Ice Age, also known from historical chronicles. Forests, woods and Mediterranean maquis developed in the early-middle Holocene. Thereafter was a general decline of arboreal vegetation, following a general aridification trend that seems to be a common feature in southern Europe and North Africa. Science Greek colonization (7th century before Christ), the landscape was intensively modelled for agriculture and breeding, leading to a significant loss of vegetation cover.

  6. Physiological performance of the cold-water coral Dendrophyllia cornigera reveals its preference for temperate environments

    Science.gov (United States)

    Gori, Andrea; Reynaud, Stephanie; Orejas, Covadonga; Gili, Josep-Maria; Ferrier-Pagès, Christine

    2014-09-01

    Cold-water corals (CWCs) are key ecosystem engineers in deep-sea benthic communities around the world. Their distribution patterns are related to several abiotic and biotic factors, of which seawater temperature is arguably one of the most important due to its role in coral physiological processes. The CWC Dendrophyllia cornigera has the particular ability to thrive in several locations in which temperatures range from 11 to 17 °C, but to be apparently absent from most CWC reefs at temperatures constantly below 11 °C. This study thus aimed to assess the thermal tolerance of this CWC species, collected in the Mediterranean Sea at 12 °C, and grown at the three relevant temperatures of 8, 12, and 16 °C. This species displayed thermal tolerance to the large range of seawater temperatures investigated, but growth, calcification, respiration, and total organic carbon (TOC) fluxes severely decreased at 8 °C compared to the in situ temperature of 12 °C. Conversely, no significant differences in calcification, respiration, and TOC fluxes were observed between corals maintained at 12 and 16 °C, suggesting that the fitness of this CWC is higher in temperate rather than cold environments. The capacity to maintain physiological functions between 12 and 16 °C allows D. cornigera to be the most abundant CWC species in deep-sea ecosystems where temperatures are too warm for other CWC species (e.g., Canary Islands). This study also shows that not all CWC species occurring in the Mediterranean Sea (at deep-water temperatures of 12-14 °C) are currently living at their upper thermal tolerance limit.

  7. RADIO OBSERVATIONS REVEAL UNUSUAL CIRCUMSTELLAR ENVIRONMENTS FOR SOME TYPE Ibc SUPERNOVA PROGENITORS

    International Nuclear Information System (INIS)

    We present extensive radio observations of the nearby Type Ibc supernovae (SNe Ibc) 2004cc, 2004dk, and 2004gq spanning Δt ≈ 8-1900 days after explosion. Using a dynamical model developed for synchrotron emission from a slightly decelerated shock wave, we estimate the velocity and energy of the fastest ejecta and the density profile of the circumstellar medium. The shock waves of all three supernovae are characterized by non-relativistic velocities of v-bar approx. (0.1-25)c and associated energies of E ≈ (2-10) × 1047 erg, in line with the expectations for a typical homologous explosion. Smooth circumstellar density profiles are indicated by the early radio data and we estimate the progenitor mass-loss rates to be M-dot approx. (0.6-13) x 10-5 M☉ yr-1 (wind velocity, vw = 103 km s–1). These estimates approach the saturation limit ( M-dot ∼10-4 M☉ yr-1) for line-driven winds from Wolf-Rayet stars, the favored progenitors of SNe Ibc including those associated with long-duration gamma-ray bursts. Intriguingly, at later epochs all three supernovae show evidence for abrupt radio variability that we attribute to large density modulations (factor of ∼3-6) at circumstellar radii of r ≈ (1-50) × 1016 cm. If due to variable mass loss, these modulations are associated with progenitor activity on a timescale of ∼10-100 years before explosion. We consider these results in the context of variable mass-loss mechanisms including wind clumping, metallicity-independent continuum-driven ejections, and binary-induced modulations. It may also be possible that the SN shock waves are dynamically interacting with wind termination shocks; however, this requires the environment to be highly pressurized and/or the progenitor to be rapidly rotating prior to explosion. The proximity of the density modulations to the explosion sites may suggest a synchronization between unusual progenitor mass loss and the SN explosion, reminiscent of Type IIn supernovae. This study

  8. An example of transition from a corrosion process in gaseous phase to corrosion in aqueous environment: the case of Z2CN18-10 stainless steel by iodine and water in vapour phase

    International Nuclear Information System (INIS)

    This research thesis addresses an example of transition of a corrosion process in gaseous phase towards corrosion in aqueous environment, specifically in the case of the corrosion of the Z2CN18-10 stainless steel by gaseous iodine in presence of water vapour (and possibly nitrogen dioxide). This transition occurs in two steps: initiation in gaseous phase and growth in aqueous environment. This transition is due to hygroscopic properties of mostly chromium iodides and, to a lesser extent, iron iodides. Morphological, electrochemical and thermogravimetry studies have been performed by varying different parameters governing corrosion processes: corrosion temperature, iodine concentration, relative humidity, and reaction time

  9. Surface potential at the hematite (001) crystal plane in aqueous environments and the effects of prolonged aging in water

    Science.gov (United States)

    Lützenkirchen, Johannes; Preočanin, Tajana; Stipić, Filip; Heberling, Frank; Rosenqvist, Jörgen; Kallay, Nikola

    2013-11-01

    The surface potentials of a (0 0 1) terminated hematite crystal that was annealed at high-temperature were measured as a function of pH by means of the corresponding single crystal electrode. The surface potential at a given pH did not depend on the electrolyte concentration, and was found to exhibit an inflection point. The shape of the function is in phenomenological agreement with the presence of two distinct surface terminations (O and Fe) that have been previously reported for this surface. Aging of the annealed hematite surface, in aqueous electrolyte medium over 2 weeks, leads to a drastic change in the surface potential pH curve. The surface potential becomes that of the ideal O termination. While the O termination data can be modeled using the MUSIC approach, the initial sample that is expected to correspond to the two-domain surface with O and Fe terminations cannot be described within the MUSIC approach based on previously published surface diffraction data. However, the experimental data fall between the O and Fe termination limiting cases when the point of zero potential is placed at the inflection point. The fact that a surface with the two terminations cannot be modeled may be attributed to various issues, three of which are discussed: (i) the general difficulty to average the potential arising from both terminations, which furthermore are short-circuited via the crystal, (ii) the difficulty of treating patchwise heterogeneous surfaces in surface complexation models, and (iii) the incapability of surface complexation models in their present form to describe potential gradients within the solid. Conclusively, we interpret our results as a transformation from a bi-domain surface, to a single domain surface over time under conditions where bulk hematite solubility is low. Accordingly, the oxygen terminated domain should be the more stable one at this single crystal surface at our experimental conditions.

  10. Corrosion processes of austenitic stainless steels and copper-based materials in gamma-irradiated aqueous environments

    International Nuclear Information System (INIS)

    The U.S. Department of Energy is evaluating a site located at Yucca Mountain in Nye County, Nevada, as a potential high-level nuclear waste repository. The rock at the proposed repository horizon (above the water table) is densely welded, devitrified tuff, and the fluid environment in the repository is expected to be primarily air-steam. A more severe environment would be present in the unlikely case of intrusion of vadose groundwater into the repository site. For this repository location, austenitic stainless steels and copper-based materials are under consideration for waste container fabrication. This study focuses on the effects of gamma irradiation on the electrochemical mechanisms of corrosion for the prospective waste container materials. The radiolytic production of such species as hydrogen peroxide and nitric acid are shown to exert an influence on corrosion mechanisms and kinetics

  11. The corrosion behavior of Alloy 52 weld metal in cyclic hydrogenated and oxygenated water chemistry in high temperature aqueous environment

    International Nuclear Information System (INIS)

    Highlights: • Ecorr and film resistance in DO and DH periods differ largely. • Oxide film shows two types of semi conductivity in different potential ranges. • Electric and electrochemical properties are changeable during chemical fatigue. • The morphology and composition of the oxide film are unchangeable. - Abstract: The corrosion behavior of Alloy 52 weld metal in cyclic hydrogenated and oxygenated water chemistry in high temperature water is studied by in situ monitoring corrosion potential (Ecorr), contact electric resistance (CER) and electrochemical impedance measurements (EIS), and ex situ scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. The Ecorr and film resistance show large change when the environment is changed from hydrogenated water to oxygenated water and changeable with changing environment while the morphology and composition only show obvious distinction in the first cycle. The main factor controlling the electric/electrochemical properties of the oxide film is Ecorr

  12. A Submersible, Off-Axis Holographic Microscope for Detection of Microbial Motility and Morphology in Aqueous and Icy Environments

    OpenAIRE

    Lovejoy, Connie; Lindensmith, Christian A.; Rider, Stephanie; Bedrossian, Manuel; Wallace, J. Kent; Serabyn, Eugene; Showalter, G. Max; Deming, Jody W.; Nadeau, Jay L.

    2016-01-01

    Sea ice is an analog environment for several of astrobiology’s near-term targets: Mars, Europa, Enceladus, and perhaps other Jovian or Saturnian moons. Microorganisms, both eukaryotic and prokaryotic, remain active within brine channels inside the ice, making it unnecessary to penetrate through to liquid water below in order to detect life. We have developed a submersible digital holographic microscope (DHM) that is capable of resolving individual bacterial cells, and demonstrated its utility...

  13. L-Prolinamide Catalyzed Aqueous Direct Aldol Reaction: an Environment-friendly Method for the Synthesis of β-Hydroxylketones

    Institute of Scientific and Technical Information of China (English)

    PENG, Yi-Yuang; LIU, Han; CUI, Ming; CHENG, Jin-Pei

    2007-01-01

    An environment-friendly L-prolinamide catalyzed aldol reaction has been developed. The reaction exhibited broad substrate generality, and high yields with good diastereoselectivity were obtained for cyclic ketones. The simplicity of product isolation, usage of water as environmentally benign reaction medium, and the usage of cheap,readily available and recyclable catalyst make this process promising to be developed for large-scale preparation of β-hydroxyl ketones.

  14. A Submersible, Off-Axis Holographic Microscope for Detection of Microbial Motility and Morphology in Aqueous and Icy Environments

    Science.gov (United States)

    Lindensmith, Christian A.; Rider, Stephanie; Bedrossian, Manuel; Wallace, J. Kent; Serabyn, Eugene; Showalter, G. Max; Deming, Jody W.; Nadeau, Jay L.

    2016-01-01

    Sea ice is an analog environment for several of astrobiology’s near-term targets: Mars, Europa, Enceladus, and perhaps other Jovian or Saturnian moons. Microorganisms, both eukaryotic and prokaryotic, remain active within brine channels inside the ice, making it unnecessary to penetrate through to liquid water below in order to detect life. We have developed a submersible digital holographic microscope (DHM) that is capable of resolving individual bacterial cells, and demonstrated its utility for immediately imaging samples taken directly from sea ice at several locations near Nuuk, Greenland. In all samples, the appearance and motility of eukaryotes were conclusive signs of life. The appearance of prokaryotic cells alone was not sufficient to confirm life, but when prokaryotic motility occurred, it was rapid and conclusive. Warming the samples to above-freezing temperatures or supplementing with serine increased the number of motile cells and the speed of motility; supplementing with serine also stimulated chemotaxis. These results show that DHM is a useful technique for detection of active organisms in extreme environments, and that motility may be used as a biosignature in the liquid brines that persist in ice. These findings have important implications for the design of missions to icy environments and suggest ways in which DHM imaging may be integrated with chemical life-detection suites in order to create more conclusive life detection packages. PMID:26812683

  15. A Submersible, Off-Axis Holographic Microscope for Detection of Microbial Motility and Morphology in Aqueous and Icy Environments.

    Science.gov (United States)

    Lindensmith, Christian A; Rider, Stephanie; Bedrossian, Manuel; Wallace, J Kent; Serabyn, Eugene; Showalter, G Max; Deming, Jody W; Nadeau, Jay L

    2016-01-01

    Sea ice is an analog environment for several of astrobiology's near-term targets: Mars, Europa, Enceladus, and perhaps other Jovian or Saturnian moons. Microorganisms, both eukaryotic and prokaryotic, remain active within brine channels inside the ice, making it unnecessary to penetrate through to liquid water below in order to detect life. We have developed a submersible digital holographic microscope (DHM) that is capable of resolving individual bacterial cells, and demonstrated its utility for immediately imaging samples taken directly from sea ice at several locations near Nuuk, Greenland. In all samples, the appearance and motility of eukaryotes were conclusive signs of life. The appearance of prokaryotic cells alone was not sufficient to confirm life, but when prokaryotic motility occurred, it was rapid and conclusive. Warming the samples to above-freezing temperatures or supplementing with serine increased the number of motile cells and the speed of motility; supplementing with serine also stimulated chemotaxis. These results show that DHM is a useful technique for detection of active organisms in extreme environments, and that motility may be used as a biosignature in the liquid brines that persist in ice. These findings have important implications for the design of missions to icy environments and suggest ways in which DHM imaging may be integrated with chemical life-detection suites in order to create more conclusive life detection packages. PMID:26812683

  16. A Submersible, Off-Axis Holographic Microscope for Detection of Microbial Motility and Morphology in Aqueous and Icy Environments.

    Directory of Open Access Journals (Sweden)

    Christian A Lindensmith

    Full Text Available Sea ice is an analog environment for several of astrobiology's near-term targets: Mars, Europa, Enceladus, and perhaps other Jovian or Saturnian moons. Microorganisms, both eukaryotic and prokaryotic, remain active within brine channels inside the ice, making it unnecessary to penetrate through to liquid water below in order to detect life. We have developed a submersible digital holographic microscope (DHM that is capable of resolving individual bacterial cells, and demonstrated its utility for immediately imaging samples taken directly from sea ice at several locations near Nuuk, Greenland. In all samples, the appearance and motility of eukaryotes were conclusive signs of life. The appearance of prokaryotic cells alone was not sufficient to confirm life, but when prokaryotic motility occurred, it was rapid and conclusive. Warming the samples to above-freezing temperatures or supplementing with serine increased the number of motile cells and the speed of motility; supplementing with serine also stimulated chemotaxis. These results show that DHM is a useful technique for detection of active organisms in extreme environments, and that motility may be used as a biosignature in the liquid brines that persist in ice. These findings have important implications for the design of missions to icy environments and suggest ways in which DHM imaging may be integrated with chemical life-detection suites in order to create more conclusive life detection packages.

  17. Salt resistance genes revealed by functional metagenomics from brines and moderate-salinity rhizosphere within a hypersaline environment

    Directory of Open Access Journals (Sweden)

    Salvador eMirete

    2015-10-01

    Full Text Available Hypersaline environments are considered one of the most extreme habitats on earth and microorganisms have developed diverse molecular mechanisms of adaptation to withstand these conditions. The present study was aimed at identifying novel genes involved in salt resistance from the microbial communities of brines and the rhizosphere from the Es Trenc saltern (Mallorca, Spain. The microbial diversity assessed by pyrosequencing of 16S rRNA gene libraries revealed the presence of communities that are typical in such environments. Metagenomic libraries from brine and rhizosphere samples, were transferred to the osmosensitive strain Escherichia coli MKH13, and screened for salt resistance. As a result, eleven genes that conferred salt resistance were identified, some encoding for well known proteins previously related to osmoadaptation as a glycerol and a proton pump, whereas others encoded for proteins not previously related to this function in microorganisms as DNA/RNA helicases, an endonuclease III (Nth and hypothetical proteins of unknown function. Furthermore, four of the retrieved genes were cloned and expressed in Bacillus subtilis and they also exhibited salt resistance in this bacterium, broadening the spectrum of bacterial species where these genes can operate. This is the first report of salt resistance genes recovered from metagenomes of a hypersaline environment.

  18. The corrosion behavior of Alloy 52 weld metal in cyclic hydrogenated and oxygenated water chemistry in high temperature aqueous environment

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jian, E-mail: xujian@fri.niche.tohoku.ac.jp; Shoji, Tetsuo

    2015-06-15

    Highlights: • E{sub corr} and film resistance in DO and DH periods differ largely. • Oxide film shows two types of semi conductivity in different potential ranges. • Electric and electrochemical properties are changeable during chemical fatigue. • The morphology and composition of the oxide film are unchangeable. - Abstract: The corrosion behavior of Alloy 52 weld metal in cyclic hydrogenated and oxygenated water chemistry in high temperature water is studied by in situ monitoring corrosion potential (E{sub corr}), contact electric resistance (CER) and electrochemical impedance measurements (EIS), and ex situ scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analysis. The E{sub corr} and film resistance show large change when the environment is changed from hydrogenated water to oxygenated water and changeable with changing environment while the morphology and composition only show obvious distinction in the first cycle. The main factor controlling the electric/electrochemical properties of the oxide film is E{sub corr}.

  19. Susceptibility of 17-4PH stainless steel to stress corrosion cracking in aqueous environments by electrochemical techniques

    International Nuclear Information System (INIS)

    The susceptibility of a 17-4PH type steel to Stress Corrosion Cracking (SCC) in low pressure steam turbine environments was assessed using slow strain rate test at 90 Centigrade and at 1.35x10-6 seg-1. Environments tested included different concentrated solutions of NaCl, NaOH and Na2SO4. It was concluded that this steel is susceptible to SCC in 20 % NaCl and pH=3 and in 20 % NaCl pH=neutral but under cathodic polarisation. The electrochemical potential noise of the specimen was monitored during the test. The naturally fluctuations in potential were arise due to spontaneous brake protective film and were characteristics of the kind of corrosion like pit or stress corrosion cracking. After that using Fast Fourier Transformer (FFT) the noise data set were analyzed to obtain power spectral density plots which showed differences between general corrosion and localized corrosion. Polarization curves were carry out at two different rates and them showed the general behavior of the systems. (Author)

  20. Corrosion fatigue studies on A533-B, C-Mn and Ducol W30 pressure vessel steels at ambient temperature and pressure in aqueous environments

    International Nuclear Information System (INIS)

    Corrosion fatigue crack growth tests have been performed on three pressure vessel steels, A533-B, Ducol W30 and a C-Mn steel, in simulated water reactor environments at ambient temperature and pressure. A533-B and Ducol W30 had a bainitic, and the C-Mn a ferritic-pearlitic, microstructure- above a cyclic stress intensity level of 25 MN.msup(3/2), crack growth rates are in general greater for the ferritic-pearlitic material. Tests have covered a range of stress ratios and frequencies, there being a strong effect of frequency on growth rates, but a small effect of stress ratio. Examination of several specimen orientations has shown there to be no significant effect of growth rates. Mechanisms of corrosion fatigue have been discussed in the light of features observed on specimen fracture surfaces. The ferritic-pearlitic steel has shown a transition in fracture mode from transgranular quasi-cleavage to intergranular cracking on lowering the cyclic stress intensity, the transition occurring when the plastic zone size at the crack tip became less than four times the grain size. The cleavage mode indicates that this material is susceptible to hydrogen embrittlement in these aqueous environments at ambient temperature. The bainitic steels have not in general shown these fracture modes and appear less susceptible to hydrogen embrittlement. The enhancement of growth rates, above those obtained in air, is controlled by a dissolution mechanism. (author)

  1. Influence of sulfur on the passivity of inconel 600 in aqueous environment at 3000C. Relationship with stress corrosion

    International Nuclear Information System (INIS)

    Dissolution kinetics and repassivation of inconel 600 in simulated primary coolant circuits of PWR is studied by fast traction experiment under potentiostatic control. The notion of elementary electrochemical transient is introduced. The model of anodic dissolution - film rupture allows the calculation of crack growth in constant deformation rate tests. When sulfur concentration is smaller than 100 micrograms/g the current is low, above the current is high. Calculation of crack growth from high level current are consistent with experimental data. Influence of pH, temperature, solution composition are determined. A Comparative study with nickel, incoloy 690 and a 19% chromium alloy was carried out to understand fast traction phenomena. Chromium plays an important part without pollution a protecting chromium oxide is formed. In polluted environment sulfur prevent nucleation of this compound and chromium hydroxides are precipitated on the surface. With pure nickel there is no passivity in presence of sulfur

  2. Influence of aqueous environment pH on the corrosion behaviour of the CANDU steam generator tubing material

    International Nuclear Information System (INIS)

    The generalized corrosion is an undesirable process because it is accompanied by deposition of the corrosion products which affect the steam generator performances. It is very important to understand the generalized corrosion mechanism in order to evaluate the amounts of corrosion products which exist in the steam generator after a determined period of operation. The purpose of the experimental research consists in the assessment of corrosion behavior of the tube material (Incoloy-800) at normal secondary circuit parameters (temperature - 260 deg. C, pressure - 5.1 MPa). The testing environment was the demineralized water without impurities, at different pH values regulated with morpholine and cycloheyilamine (all volatile treatment). The results are presented as micrographs and graphics representing loss of metal by corrosion, corrosion rate, the total corrosion products, the adherent corrosion product, the released corrosion products and the release of the metal. (authors)

  3. Comparative metabolomic analysis reveals a reactive oxygen species-dominated dynamic model underlying chilling environment adaptation and tolerance in rice.

    Science.gov (United States)

    Zhang, Jingyu; Luo, Wei; Zhao, Yuan; Xu, Yunyuan; Song, Shuhui; Chong, Kang

    2016-09-01

    Cold, a major environmental stress for plants, has been studied intensively for decades. Its response system has been revealed, especially at the transcriptional level. The mechanisms underlying recovery growth and environmental adaptation, however, remain unknown. Taking advantage of a naturally existing system, two subspecies of Asian cultivated rice (Oryza sativa) with significant divergence in chilling tolerance, we analyzed representative japonica and indica varieties, Nipponbare and 93-11, using comparative metabolomic analysis at six time points covering chilling treatment and recovery. In total, 223 known metabolites were detected. During chilling treatment, significant biochemical changes were centered on antioxidation. During recovery, a wide-ranging chilling response was observed. Large-scale amino acid accumulation occurred, consistent with the appearance of chilling injury. At the mid-treatment stage, the accumulation of antioxidation-related compounds appeared earlier in Nipponbare than in 93-11, consistent with the higher reactive oxygen species (ROS) levels in japonica vs indica varieties. A significant contribution of ROS-mediated gene regulation, rather than the C-repeat binding factor/dehydration-responsive-element binding factor (CBF/DREB) regulon, to the more vigorous transcriptional stress response in Nipponbare was revealed by RNA-seq. Accordingly, during recovery, the induction of stress-tolerant-related metabolites was more active in the chilling-tolerant variety Nipponbare. Senescence-related compounds accumulated only in the chilling-sensitive variety 93-11. Our study uncovers the dynamic metabolic models underlying chilling response and recovery, and reveals a ROS-dominated rice adaptation mechanism to low-temperature environments. PMID:27198693

  4. Environment

    DEFF Research Database (Denmark)

    Valentini, Chiara

    2016-01-01

    The term environment refers to the internal and external context in which organizations operate. For some scholars, environment is defined as an arrangement of political, economic, social and cultural factors existing in a given context that have an impact on organizational processes and structures....... For others, environment is a generic term describing a large variety of stakeholders and how these interact and act upon organizations. Organizations and their environment are mutually interdependent and organizational communications are highly affected by the environment. This entry examines the...... origin and development of organization-environment interdependence, the nature of the concept of environment and its relevance for communication scholarships and activities....

  5. Assessing the effect of cement-steel interface on well casing corrosion in aqueous CO2 environments

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jiabin [Los Alamos National Laboratory; Carey, James W [Los Alamos National Laboratory; Zhang, Jinsuo [Los Alamos National Laboratory

    2010-01-01

    CO{sub 2} leakage is a critical safety concern for geologic storage. In wellbore environments, important leakage paths include the rock-cement and cement-casing interfaces. If the cement-casing interface is filled with escaping CO{sub 2}, the well casing directly contacts the CO{sub 2}. This can cause severe corrosion in the presence of water. This paper studies the effect of steel-cement interface gaps, ranging from 1 mm to 0 um, on casing corrosion. Corrosion kinetics were measured employing electrochemical techniques including linear polarization resistance, open circuit potential and electrochemical impedance spectroscopy. The experimental results showed that the corrosion of steel is not significant where the gap between steel and cement is small ({le} 100 {micro}m). Corrosion rates are controlled by the diffusion of corrosive species (H{sub 2}CO{sub 3} and H{sup +}) along the interface. In contrast, steel corrosion is severe in a broad gap where the corrosion process is limited only by the reaction kinetics of steel and corrosive species. The threshold leading to severe corrosion in terms of the cement-steel interface size (100 {micro}m) was determined. Our research clarifies a corrosion scenario at the cement-steel interface. Casing steel corrosion is initiated when attacked by corrosive species at the cement-steel interface. For relatively tight interfaces, this results in a slow thinning of the casing and expansion of the interface width. If the gap increases beyond the critical threshold size, the corrosion rate increases significantly, and a potentially damaging cycle of corrosion and interface expansion is developed.

  6. Aram Chaos: a Long Lived Subsurface Aqueous Environment with Strong Water Resources Potential for Human Missions on Mars

    Science.gov (United States)

    Sibille, L.; Mueller, R.; Niles, P. B.; Glotch, T.; Archer, P. D.; Bell, M. S.

    2015-01-01

    Aram Chaos, Mars is a crater 280 kilometers in diameter with elevations circa. minus 2 to minus 3 kilometers below datum that provides a compelling landing site for future human explorers as it features multiple scientific regions of interest (ROI) paired with a rich extensible Resource ROI that features poly-hydrated sulfates [1]. The geologic history of Aram Chaos suggests several past episodes of groundwater recharge and infilling by liquid water, ice, and other materials [1-3]. The creation of the fractured region with no known terrestrial equivalent may have been caused by melting of deep ice reservoirs that triggered the collapse of terrain followed by catastrophic water outflows over the region. Aram Chaos is of particular scientific interest because it is hypothesized that the chaotic terrain may be the source of water that contributed to the creation of nearby valleys such as Ares Vallis flowing toward Chryse Planitia. The liquid water was likely sourced as groundwater and therefore represents water derived from a protected subsurface environment making it a compelling astrobiological site [2]. The past history of water is also represented by high concentrations of hematite, Fe-oxyhydroxides, mono-hydrated and poly-hydrated sulfates [1, 2]. Poly-hydrated sulfates are likely to contain abundant water that evolves at temperatures below 500 degrees Centigrade thus conferring Aram Chaos a potentially high value for early in-situ resource utilization (ISRU) [4]. The geologic history also calls for future prospecting of deep ice deposits and possibly liquid water via deep drilling. The most recent stratigraphic units in the central part of Aram Chaos are not fractured, and are part of a dome-shaped formation that features bright, poorly-consolidated material that contains both hydrated sulfates and ferric oxides according to OMEGA (Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité) data [5]. These surface material characteristics are

  7. Performance Evaluation of Electrochemical Process using Iron and Aluminum Electrodes in Phenol  Removal from Synthetic Aqueous Environment 

    Directory of Open Access Journals (Sweden)

    Hamed Biglari

    2013-02-01

    Full Text Available Background and Objectives: Phenol is one of the most important organic chemicals presenting in water and other environments. It not only brings about hygienic problems but also results in forming 11 toxic priority pollutants in aqueous environments. Hence, the performance of electrocoagulation process using iron and aluminum sacrificial anodes was investigated for removal of phenol.Materials and Methods: We used a glass tank in 1.56 L volume (effective volume 1 L equipped with four iron and aluminum plate electrodes to do experiments (bipolar mode. The tank was filled with synthetic wastewater containing phenol in concentration of 5, 20, 40, and 70 mg/l and to follow the progress of the treatment, each sample was taken at 20 min intervals for up to 80 min. The percent of phenol removal was measured at pH 3, 5, 7, and 9; electrical potential range of 20, 40, and 60 volts; and electrical conductivity of 1000, 1500, 2000, and 3000 µs/cm. Results: It was found that the most effective removal capacities of phenol (95 and 98 % could be achieved when the pH was kept 7 and 5 for iron and aluminum electrodes, reaction time  80 min, electrical conductivity 3000 µs/cm, initial concentration of phenol 5 mg/l, and electrical potential in the range of 20-60 V. Conclusion: The method was found to be highly efficient and relatively fast compared with existing conventional techniques and also it can be concluded that the electrochemical process has the potential to be utilized for the cost-effective removal of phenol from water and wastewater.

  8. Preparation and Characterization of Poly(ethyl hydrazide-Grafted Oil Palm Empty Fruit Bunch Fibre for the Removal of Cu(II Ions from an Aqueous Environment

    Directory of Open Access Journals (Sweden)

    Siti Mariam Mohd Nor

    2013-07-01

    Full Text Available Poly(ethyl hydrazide-grafted oil palm empty fruit bunch fibre (peh-g-opefb was successfully prepared by heating poly(methyl acrylate-grafted opefb (pma-g-opefb at 60 °C for 4 h with a solution of hydrazine hydrate (15% v/v in ethanol. The Fourier transform infrared spectrum of the product shows a secondary amine peak at 3267 cm−1, with amide carbonyl peaks at 1729 cm−1 and 1643 cm−1. The chelating ability of peh-g-opefb was tested with copper ion in aqueous solution. A batch adsorption study revealed that maximum adsorption of copper ion was achieved at pH 5. An isotherm study showed the adsorption follows a Langmuir model, with a maximum adsorption capacity of 43.48 mg g−1 at 25 °C. A kinetic study showed that the adsorption of copper ion rapidly reaches equilibrium and follows a pseudo–second-order kinetic model, with a constant rate of 7.02 × 10−4 g mg−1 min−1 at 25 °C. The Gibbs free energy, ∆G⁰, value is negative, indicating a spontaneous sorption process. Entropy, ∆S⁰, gives a positive value, indicating that the system is becoming increasingly disordered after the adsorption of copper ion. A positive enthalpy value, ∆H⁰, shows that the endothermic process takes place during the adsorption and is more favourable at high temperatures.

  9. Preparation and characterization of poly(ethyl hydrazide)-grafted oil palm empty fruit bunch fibre for the removal of Cu(II) ions from an aqueous environment.

    Science.gov (United States)

    Johari, Ili Syazana; Yusof, Nor Azah; Haron, Md Jelas; Nor, Siti Mariam Mohd

    2013-01-01

    Poly(ethyl hydrazide)-grafted oil palm empty fruit bunch fibre (peh-g-opefb) was successfully prepared by heating poly(methyl acrylate)-grafted opefb (pma-g-opefb) at 60 °C for 4 h with a solution of hydrazine hydrate (15% v/v) in ethanol. The Fourier transform infrared spectrum of the product shows a secondary amine peak at 3267 cm⁻¹, with amide carbonyl peaks at 1729 cm⁻¹ and 1643 cm⁻¹. The chelating ability of peh-g-opefb was tested with copper ion in aqueous solution. A batch adsorption study revealed that maximum adsorption of copper ion was achieved at pH 5. An isotherm study showed the adsorption follows a Langmuir model, with a maximum adsorption capacity of 43.48 mg g-1 at 25 °C. A kinetic study showed that the adsorption of copper ion rapidly reaches equilibrium and follows a pseudo-second-order kinetic model, with a constant rate of 7.02 × 10⁻⁴ g mg⁻¹ min⁻¹ at 25 °C. The Gibbs free energy, ∆G⁰, value is negative, indicating a spontaneous sorption process. Entropy, ∆S⁰, gives a positive value, indicating that the system is becoming increasingly disordered after the adsorption of copper ion. A positive enthalpy value, ∆H⁰, shows that the endothermic process takes place during the adsorption and is more favourable at high temperatures. PMID:23873385

  10. Water distributions in PS-b-P(S-g-PEO) block grafted copolymer system in aqueous solutions revealed by contrast variation SANS study

    International Nuclear Information System (INIS)

    In this report, we present a contrast variation small angle neutron scattering (SANS) study of PS-b-P(S-g-PEO) block graft copolymers in aqueous media at a concentration of 10 mg/ml. Through varying the solvent D2O/H2O ratio, the scattering contributions from the water molecules and the micellar constituent components can be determined. Based on the commonly used core-shell model, a theoretical coherent scattering cross section incorporating the effect of water penetration is developed and used to analyze the SANS I(Q), we have successfully quantified the micellar structure and the number of - water molecules associated with the core and corona. We have found that the overall micellar hydration level increase with the increase in the molecular weight of hydrophilic PEO side chains. This study provides key information in understanding solvent distributions within self-assembled amphiphilic block grafted copolymers.

  11. Integrated multi-omics analyses reveal the biochemical mechanisms and phylogenetic relevance of anaerobic androgen biodegradation in the environment.

    Science.gov (United States)

    Yang, Fu-Chun; Chen, Yi-Lung; Tang, Sen-Lin; Yu, Chang-Ping; Wang, Po-Hsiang; Ismail, Wael; Wang, Chia-Hsiang; Ding, Jiun-Yan; Yang, Cheng-Yu; Yang, Chia-Ying; Chiang, Yin-Ru

    2016-08-01

    Steroid hormones, such as androgens, are common surface-water contaminants. However, literature on the ecophysiological relevance of steroid-degrading organisms in the environment, particularly in anoxic ecosystems, is extremely limited. We previously reported that Steroidobacter denitrificans anaerobically degrades androgens through the 2,3-seco pathway. In this study, the genome of Sdo. denitrificans was completely sequenced. Transcriptomic data revealed gene clusters that were distinctly expressed during anaerobic growth on testosterone. We isolated and characterized the bifunctional 1-testosterone hydratase/dehydrogenase, which is essential for anaerobic degradation of steroid A-ring. Because of apparent substrate preference of this molybdoenzyme, corresponding genes, along with the signature metabolites of the 2,3-seco pathway, were used as biomarkers to investigate androgen biodegradation in the largest sewage treatment plant in Taipei, Taiwan. Androgen metabolite analysis indicated that denitrifying bacteria in anoxic sewage use the 2,3-seco pathway to degrade androgens. Metagenomic analysis and PCR-based functional assays showed androgen degradation in anoxic sewage by Thauera spp. through the action of 1-testosterone hydratase/dehydrogenase. Our integrative 'omics' approach can be used for culture-independent investigations of the microbial degradation of structurally complex compounds where isotope-labeled substrates are not easily available. PMID:26872041

  12. Widely used pharmaceuticals present in the environment revealed as in vitro antagonists for human estrogen and androgen receptors.

    Science.gov (United States)

    Ezechiáš, Martin; Janochová, Jana; Filipová, Alena; Křesinová, Zdena; Cajthaml, Tomáš

    2016-06-01

    A considerable amount of scientific evidence indicates that a number of pharmaceuticals that could be detected in the environment can contribute towards the development of problems associated with human reproductive systems, as well as those of wildlife. We investigated the estrogenic and androgenic effects of select pharmaceuticals with high production volume and environmental relevance. We examined the receptor-binding activities of these pharmaceuticals in the T47D human cell line using altered secretion of cytokine CXCL12. Functional yeast-luciferase reporter gene assays were also employed to confirm the mechanism of receptor binding by estrogen and androgen. Non-steroidal anti-inflammatory drugs, namely ibuprofen, diclofenac and antiarrhythmic agent amiodarone showed strong anti-estrogenic effects in the T47D cell line. In the yeast-luciferase assay, these anti-inflammatory drugs also demonstrated anti-estrogenic potency and inhibited the E2 response in a concentration-dependent manner. Amiodarone did not exhibit any response in the yeast-luciferase assay; therefore, the endocrine disruption presumably occurred at a different level without directly involving the receptor. All the anti-inflammatory drugs considered in this study, including ketoprofen, naproxen and clofibrate, exhibited a dose-dependent antagonism towards the androgen receptor in the yeast-luciferase assays. Several other drugs, including the stimulant caffeine, did not show any response in the tests that were employed. A risk assessment analysis using 'Hazard Quotient' suggested a potential risk, especially in the cases of ibuprofen, ketoprofen, diclofenac and clofibrate. The results reveal the intrinsic endocrine disrupting nature of several pharmaceuticals and thus could contribute towards explaining a number of adverse health effects on humans and wildlife. PMID:26978704

  13. Stability characteristics and structural properties of single- and double-walled boron-nitride nanotubes under physical adsorption of Flavin mononucleotide (FMN) in aqueous environment using molecular dynamics simulations

    Science.gov (United States)

    Ansari, R.; Ajori, S.; Ameri, A.

    2016-03-01

    The non-cytotoxic properties of Boron-nitride nanotubes (BNNTs) and the ability of stable interaction with biomolecules make them so promising for biological applications. In this research, molecular dynamics (MD) simulations are performed to investigate the structural properties and stability characteristics of single- and double-walled BNNTs under physical adsorption of Flavin mononucleotide (FMN) in vacuum and aqueous environments. According to the simulation results, gyration radius increases by rising the weight percentage of FMN. Also, the results demonstrate that critical buckling force of functionalized BNNTs increases in vacuum. Moreover, it is observed that by increasing the weight percentage of FMN, critical force of functionalized BNNTs rises. By contrast, critical strain reduces by functionalization of BNNTs in vacuum. Considering the aqueous environment, it is observed that gyration radius and critical buckling force of functionalized BNNTs increase more considerably than those of functionalized BNNTs in vacuum, whereas the critical strains approximately remain unchanged.

  14. Histopathological effects of chronic aqueous exposure to bis(tri-n-butyltin)oxide (TBTO) to environmentally relevant concentrations reveal thymus atrophy in European flounder (Platichthys flesus)

    Energy Technology Data Exchange (ETDEWEB)

    Grinwis, G.C.M., E-mail: g.c.m.grinwis@uu.n [Department of Pathobiology, Faculty of Veterinary Medicine University of Utrecht, P.O. Box 80.158, 3508 TD Utrecht (Netherlands); Wester, P.W. [Laboratory for Toxicology, Pathology and Genetics, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven (Netherlands); Vethaak, A.D. [Deltares, Unit Coastal and Marine Systems, P.O. Box 177, 2600 MH Delft (Netherlands)

    2009-10-15

    Although the use of tributyltin in antifouling paints has been banned, this compound is still a serious pollutant of the marine environment. This paper describes a unique study in which European flounder (Platichthys flesus) were chronically (8 months) exposed to bis(tri-n-butyltin)oxide (TBTO) in the water under controlled laboratory conditions. Residue levels in selected tissues (liver, muscle) and general health status indices were measured and the effects on several organs (gills, liver, mesonephros, ovary/testis, spleen, and gastrointestinal tract) were examined histopathologically. Additionally, morphometric analysis of the thymus was performed. The major finding is that exposure of flounder to 5 mug TBTO/l over a period of 8 months, resulting in body burdens comparable to high field levels, induced significant reduction of thymus volume, possibly affecting immunocompetence of the animals. Chronic exposure of European flounder to tributyltin is therefore likely to affect the general health status of this species in heavily polluted aquatic environments. - Current levels of tributyltin antifouling contamination are still likely to affect the general health status of estuarine flatfish in heavily polluted environments.

  15. Pseudomonas lini Strain ZBG1 Revealed Carboxylic Acid Utilization and Copper Resistance Features Required for Adaptation to Vineyard Soil Environment: A Draft Genome Analysis

    Science.gov (United States)

    Chan, Kok-Gan; Chong, Teik-Min; Adrian, Tan-Guan-Sheng; Kher, Heng Leong; Grandclément, Catherine; Faure, Denis; Yin, Wai-Fong; Dessaux, Yves; Hong, Kar-Wai

    2016-01-01

    Pseudomonas lini strain ZBG1 was isolated from the soil of vineyard in Zellenberg, France and the draft genome was reported in this study. Bioinformatics analyses of the genome revealed presence of genes encoding tartaric and malic acid utilization as well as copper resistance that correspond to the adaptation this strain in vineyard soil environment. PMID:27512520

  16. Environment

    Czech Academy of Sciences Publication Activity Database

    Tošovská, Eva

    Prague: Charles University in Prague, Center for Economic Research and Graduate Education , 2006 - (Zemčík, P.; Žigić, K.), s. 62-66 ISBN 80-7343-110-6 Institutional research plan: CEZ:AV0Z70850503 Keywords : environment * Czech Republic Subject RIV: AH - Economics http://www.cerge-ei.cz/publications/books/

  17. Pharmaceuticals and the Environment (PiE): Evolution and impact of the published literature revealed by bibliometric analysis

    Science.gov (United States)

    The evolution and impact of the published literature surrounding the transdisciplinary, multifaceted topic of pharmaceuticals as contaminants in the environment is examined for the first time in an historical context. The preponderance of literature cited in this examination repr...

  18. Environ centrality reveals the tendency of indirect effects to homogenize the functional importance of species in ecosystems

    OpenAIRE

    Fann, Sarah L.; Borrett, Stuart R.

    2011-01-01

    Ecologists and conservation biologists need to identify the relative importance of species to make sound management decisions and effectively allocate scarce resources. We introduce a new method, termed environ centrality, to determine the relative importance of a species in an ecosystem network with respect to ecosystem energy--matter exchange. We demonstrate the uniqueness of environ centrality by comparing it to other common centrality metrics and then show its ecological significance. Spe...

  19. Salmon Migration Patterns Revealed the Temporal and Spatial Fluctuations of the Radiocesium Levels in Terrestrial and Ocean Environments

    OpenAIRE

    Arai, Takaomi

    2014-01-01

    The disabling of the Fukushima Daiichi Nuclear Power Plant (F1NPP) resulted in the release of radionuclides, including 134Cs and 137Cs, into the air and the ocean. The unpredicted nuclear accident is of global concern for human health and the ecosystem. Although investigations of radionuclides in environments were performed shortly after the accident started, the temporal and spatial impacts and fluctuations on the releasing radionuclides to natural environment remain unclear. I focused on sa...

  20. Partitioning of perfluorooctanesulfonate and perfluorohexanesulfonate in the aquatic environment after an accidental release of aqueous film forming foam at Schiphol Amsterdam Airport

    NARCIS (Netherlands)

    Kwadijk, C.J.A.F.; Kotterman, M.J.J.; Koelmans, A.A.

    2014-01-01

    In the summer of 2008, an accidental release of Aqueous Film Forming Foam (AFFF) took place at Schiphol Amsterdam Airport (The Netherlands). After the release, water, fish and sediment samples were collected and analyzed for perfluoroalkyl sulfonates (PFSA). In situ perfluorooctane sulfonate (PFOS)

  1. A comprehensive molecular phylogeny of dalytyphloplanida (platyhelminthes: rhabdocoela reveals multiple escapes from the marine environment and origins of symbiotic relationships.

    Directory of Open Access Journals (Sweden)

    Niels Van Steenkiste

    Full Text Available In this study we elaborate the phylogeny of Dalytyphloplanida based on complete 18S rDNA (156 sequences and partial 28S rDNA (125 sequences, using a Maximum Likelihood and a Bayesian Inference approach, in order to investigate the origin of a limnic or limnoterrestrial and of a symbiotic lifestyle in this large group of rhabditophoran flatworms. The results of our phylogenetic analyses and ancestral state reconstructions indicate that dalytyphloplanids have their origin in the marine environment and that there was one highly successful invasion of the freshwater environment, leading to a large radiation of limnic and limnoterrestrial dalytyphloplanids. This monophyletic freshwater clade, Limnotyphloplanida, comprises the taxa Dalyelliidae, Temnocephalida, and most Typhloplanidae. Temnocephalida can be considered ectosymbiotic Dalyelliidae as they are embedded within this group. Secondary returns to brackish water and marine environments occurred relatively frequently in several dalyeliid and typhloplanid taxa. Our phylogenies also show that, apart from the Limnotyphloplanida, there have been only few independent invasions of the limnic environment, and apparently these were not followed by spectacular speciation events. The distinct phylogenetic positions of the symbiotic taxa also suggest multiple origins of commensal and parasitic life strategies within Dalytyphloplanida. The previously established higher-level dalytyphloplanid clades are confirmed in our topologies, but many of the traditional families are not monophyletic. Alternative hypothesis testing constraining the monophyly of these families in the topologies and using the approximately unbiased test, also statistically rejects their monophyly.

  2. Four newly isolated fuselloviruses from extreme geothermal environments reveal unusual morphologies and a possible interviral recombination mechanism

    DEFF Research Database (Denmark)

    Greve, Bo Bjørn

    2009-01-01

    Spindle-shaped virus-like particles are abundant in extreme geothermal environments, from which five spindle-shaped viral species have been isolated to date. They infect members of the hyperthermophilic archaeal genus Sulfolobus, and constitute the Fuselloviridae, a family of double-stranded DNA...

  3. Grain-size features of aeolian sand on the east coast of Hainan Island and the revealed evolutionary processes of the sedimentary environment

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The Mudui stratigraphic section represents the typical records of sedimentation processes of sand dunes and interdune depressions on the east coast of Hainan Island.Based on high-density sampling and optically stimulated luminescence(OSL) dating of the strata of the section,the grain-size composition,grain-size parameters,cumulative distribution probability curve,and grain-size-sensitivity indexes(SC/D) were analyzed.The analyzed results show that the grain-size features of aeolian sand,weakly developed sandy paleosol,two-facies(aeolian and aqueous) deposits,and lagoon deposits are all different.This indicates four evolutionary phases of the sedimentary environment of the east coast of Hainan Island since 38 ka B.P.Phase I:38-22 ka B.P.;phase II:22-17 ka B.P.;phase III:17-10 ka B.P.;phase IV:10 ka B.P.-present.The climate experienced the hot-wet/hot-dry,hot-wet/hot-dry,and warm-wet/hot-wet fluctuations,and the sedimentary environment also underwent lagoon deposition,dune and interdune depression deposition,dune stabilization and soil development,shifting sand deposition,and evolutionary processes.

  4. Four newly isolated fuselloviruses from extreme geothermal environments reveal unusual morphologies and a possible interviral recombination mechanism

    DEFF Research Database (Denmark)

    Redder, Peter; Peng, Xu; Brügger, Kim;

    2009-01-01

    Spindle-shaped virus-like particles are abundant in extreme geothermal environments, from which five spindle-shaped viral species have been isolated to date. They infect members of the hyperthermophilic archaeal genus Sulfolobus, and constitute the Fuselloviridae, a family of double-stranded DNA ...... the spacers of the Sulfolobus CRISPR antiviral system are not biased to the highly similar regions of the fusellovirus genomes....

  5. Response to Comment on "Open-ocean fish reveal an omnidirectional solution to camouflage in polarized environments".

    Science.gov (United States)

    Brady, Parrish; Gilerson, Alex; Kattawar, George; Sullivan, Jim; Twardowski, Mike; Dierssen, Heidi; Cummings, Molly

    2016-08-01

    Cronin et al take issue with our evidence for polarocryptic carangid fish based on concerns of pseudoreplication, our contrast metric, and habitat. We clarify (i) the importance of camouflage in near-surface open ocean environments and (ii) the use of a Stokes contrast metric and further (iii) conduct individual-based statistics on our data set to confirm the reported polarocrypsis patterns. PMID:27493177

  6. Salt resistance genes revealed by functional metagenomics from brines and moderate-salinity rhizosphere within a hypersaline environment

    OpenAIRE

    Mirete, Salvador; Mora-Ruiz, Merit R.; Lamprecht-Grandío, María; de Figueras, Carolina G.; Rosselló-Móra, Ramon; González-Pastor, José E.

    2015-01-01

    Hypersaline environments are considered one of the most extreme habitats on earth and microorganisms have developed diverse molecular mechanisms of adaptation to withstand these conditions. The present study was aimed at identifying novel genes from the microbial communities of a moderate-salinity rhizosphere and brine from the Es Trenc saltern (Mallorca, Spain), which could confer increased salt resistance to Escherichia coli. The microbial diversity assessed by pyrosequencing of 16S rRNA ge...

  7. Have studies of the developmental regulation of behavioral phenotypes revealed the mechanisms of gene-environment interactions?

    OpenAIRE

    Hall, F Scott; Perona, Maria T. G.

    2012-01-01

    This review addresses the recent convergence of our long-standing knowledge of the regulation of behavioral phenotypes by developmental experience with recent advances in our understanding of mechanisms regulating gene expression. This review supports a particular perspective on the developmental regulation of behavioral phenotypes: That the role of common developmental experiences (e.g. maternal interactions, peer interactions, exposure to a complex environment, etc.) is to fit individuals t...

  8. Monitoring circadian rhythms of individual honey bees in a social environment reveals social influences on postembryonic ontogeny of activity rhythms.

    Science.gov (United States)

    Meshi, A; Bloch, G

    2007-08-01

    Social factors constitute an important component of the environment of many animals and have a profound influence on their physiology and behavior. Studies of social influences on circadian rhythms have been hampered by a methodological trade-off: automatic data acquisition systems obtain high-quality data but are effective only for individually isolated animals and therefore compromise by requiring a context that may not be sociobiologically relevant. Human observers can monitor animal activity in complex social environments but are limited in the resolution and quality of data that can be gathered. The authors developed and validated a method for prolonged, automatic, high-quality monitoring of focal honey bees in a relatively complex social environment and with minimal illumination. The method can be adapted for studies on other animals. The authors show that the system provides a reliable estimation of the actual path of a focal bee, only rarely misses its location for > 1 min, and removes most nonspecific signals from the background. Using this system, the authors provide the first evidence of social influence on the ontogeny of activity rhythms. Young bees that were housed with old foragers show ~24-h rhythms in locomotor activity at a younger age and with stronger rhythms than bees housed with a similar number of young bees. By contrast, the maturation of the hypopharyngeal glands was slower in bees housed with foragers, similar to findings in previous studies. The morphology and function of the hypopharyngeal glands vary along with age-based division of labor. Therefore, these findings indicate that social inhibition of task-related maturation was effective in the experimental setup. This study suggests that although the ontogeny of circadian rhythms is typically correlated with the age-based division of labor, their social regulation is different. PMID:17660451

  9. Synthesis and characterization of (zinc-layered hydroxide-hippurate) nano hybrid by direct reaction of zinc oxide under aqueous environment

    International Nuclear Information System (INIS)

    A new method for synthesis of hippurate nano hybrid has been developed. In this method, zinc oxide was added directly into aqueous solution of hippurate anions (A-). The resulting hippurate nano hybrid (HAN) is composed of the organic moieties sandwiched between zinc layered hydroxide (ZLH) inorganic interlayers. HAN synthesized using 0.2 M hippuric acid showed the best crystallinity compared to other samples synthesized in this work. X-ray powder diffraction shows the basal spacing of the HAN was 21.3 Angstrom indicating that the monolayer of A- was arranged vertically to the ZLH interlayers. (author)

  10. Preparation and Characterization of Poly(ethyl hydrazide) Grafted Oil Palm Empty Fruit Bunch for Removal of Ni(II) Ion in Aqueous Environment

    OpenAIRE

    Siti Mariam Mohd Nor; Nor Azah Yusof; Md Jelas Haron; Ili Syazana bt Johari

    2013-01-01

    Poly(ethyl hydrazide) grafted oil palm empty fruit bunch (peh-g-opefb) fiber has been successfully prepared by heating poly(methylacrylate)-g-opefb at 60 °C for 4 h in a solution of hydrazine hydrate in ethanol. The chelating ability of peh-g-opefb was evaluated based on removal of Ni(II) ions in aqueous solution. Adsorption of Ni(II) by peh-g-opefb was characterized based on effect of pH, isotherm, kinetic and thermodynamic study. This cheap sorbent based on oil palm empty fruit bunch fiber ...

  11. Resolving the infection process reveals striking differences in the contribution of environment, genetics and phylogeny to host-parasite interactions

    Directory of Open Access Journals (Sweden)

    Laforsch Christian

    2011-02-01

    Full Text Available Abstract Background Infection processes consist of a sequence of steps, each critical for the interaction between host and parasite. Studies of host-parasite interactions rarely take into account the fact that different steps might be influenced by different factors and might, therefore, make different contributions to shaping coevolution. We designed a new method using the Daphnia magna - Pasteuria ramosa system, one of the rare examples where coevolution has been documented, in order to resolve the steps of the infection and analyse the factors that influence each of them. Results Using the transparent Daphnia hosts and fluorescently-labelled spores of the bacterium P. ramosa, we identified a sequence of infection steps: encounter between parasite and host; activation of parasite dormant spores; attachment of spores to the host; and parasite proliferation inside the host. The chances of encounter had been shown to depend on host genotype and environment. We tested the role of genetic and environmental factors in the newly described activation and attachment steps. Hosts of different genotypes, gender and species were all able to activate endospores of all parasite clones tested in different environments; suggesting that the activation cue is phylogenetically conserved. We next established that parasite attachment occurs onto the host oesophagus independently of host species, gender and environmental conditions. In contrast to spore activation, attachment depended strongly on the combination of host and parasite genotypes. Conclusions Our results show that different steps are influenced by different factors. Host-type-independent spore activation suggests that this step can be ruled out as a major factor in Daphnia-Pasteuria coevolution. On the other hand, we show that the attachment step is crucial for the pronounced genetic specificities of this system. We suggest that this one step can explain host population structure and could be a key

  12. Comparative Molecular Dynamics Study on Tri-n-butyl Phosphate in Organic and Aqueous Environments and Its Relevance to Nuclear Extraction Processes.

    Science.gov (United States)

    Mu, Junju; Motokawa, Ryuhei; Williams, Christopher D; Akutsu, Kazuhiro; Nishitsuji, Shotaro; Masters, Andrew J

    2016-06-16

    A refined model for tri-n-butyl phosphate (TBP), which uses a new set of partial charges generated from our ab initio density functional theory calculations, has been proposed in this study. Molecular dynamics simulations are conducted to determine the thermodynamic properties, transport properties, and the microscopic structures of liquid TBP, TBP/water mixtures, and TBP/n-alkane mixtures. These results are compared with those obtained from four other TBP models, previously described in the literature. We conclude that our refined TBP model appears to be the only TBP model from this set that, with reasonable accuracy, can simultaneously predict the properties of TBP in bulk TBP, in organic diluents, and in aqueous solution. The other models only work well for two of the three systems mentioned above. This new TBP model is thus appropriate for the simulation of liquid-liquid extraction systems in the nuclear extraction process, where one needs to simultaneously model TBP in both aqueous and organic phases. It is also promising for the investigation of the microscopic structure of the organic phase in these processes and for the characterization of third-phase formation, where TBP again interacts simultaneously with both polar and nonpolar molecules. Because the proposed TBP model uses OPLS-2005 Lennard-Jones parameters, it may be used with confidence to model mixtures of TBP with other species whose parameters are given by the OPLS-2005 force field. PMID:27192017

  13. Aging of TiO{sub 2} nanocomposites used in sunscreen. Dispersion and fate of the degradation products in aqueous environment

    Energy Technology Data Exchange (ETDEWEB)

    Labille, Jerome, E-mail: labille@cerege.f [CEREGE UMR 6635 CNRS/Aix-Marseille Universite, Europole de l' Arbois, 13545 Aix-en-Provence (France); International Consortium for the Environmental Implications of Nanotechnology iCEINT, Europole de l' Arbois, 13545 Aix en Provence (France); Feng Jinghuan; Botta, Celine [CEREGE UMR 6635 CNRS/Aix-Marseille Universite, Europole de l' Arbois, 13545 Aix-en-Provence (France); Borschneck, Daniel [CEREGE UMR 6635 CNRS/Aix-Marseille Universite, Europole de l' Arbois, 13545 Aix-en-Provence (France); International Consortium for the Environmental Implications of Nanotechnology iCEINT, Europole de l' Arbois, 13545 Aix en Provence (France); Sammut, Magali [CEREGE UMR 6635 CNRS/Aix-Marseille Universite, Europole de l' Arbois, 13545 Aix-en-Provence (France); Cabie, Martiane [CP2M, Universite d' Aix Marseille, Case 221, 13397 Marseille cedex 20 (France); Auffan, Melanie; Rose, Jerome; Bottero, Jean-Yves [CEREGE UMR 6635 CNRS/Aix-Marseille Universite, Europole de l' Arbois, 13545 Aix-en-Provence (France); International Consortium for the Environmental Implications of Nanotechnology iCEINT, Europole de l' Arbois, 13545 Aix en Provence (France)

    2010-12-15

    Aging in water of a TiO{sub 2}-based nanocomposite used in sunscreen cosmetics has been studied as a function of light and time. It consisted initially in a TiO{sub 2} core, coated with Al(OH){sub 3} and polydimethylsiloxane (PDMS) layers. Size measurement, coating alteration, and surface charge were followed by laser diffraction, TEM/EDS, ICP-AES and electrophoretic mobility measurement. The nanocomposite rapidly underwent progressive dispersion in the aqueous phase, enabled by the dissolution of the PDMS layer. A stable suspension of colloidal byproducts from 50 to 700 nm in size was formed. Their positively charged Al(OH){sub 3} surface was evidenced with an isoelectric point around 7-8, controlling the dispersion stability. The critical coagulation concentrations measured with NaCl and CaCl{sub 2} was 2 x 10{sup -2} and 8 x 10{sup -3} M respectively. The presence of natural organic matter affected the colloidal stability according to the NOM/byproduct ratio. A 2 wt% ratio favored bridging flocculation, whereas a 20 wt% ratio induced sterical stabilization. - Aging in aqueous conditions of TiO{sub 2} nanocomposite used in sunscreens induces rapid generation of nanometric byproducts remaining stable in suspension.

  14. The expression revealing variation trend about radiation resistance of aromatic polymers serving in nuclear environment over absorbed dose

    International Nuclear Information System (INIS)

    For polymeric materials applied in nuclear environment, the macroscopic properties usually remain unchanged after irradiation for several years or decades up to a threshold dose at which the deterioration of materials begins to take place. In this paper, the general radiation response of aromatic polymers is firstly reviewed and discussed. Then percolation theory is employed innovatively to elucidate the critical phenomenon over the service life for polymeric materials with high radiation resistance. For a better quantitative evaluation, a novel two-parameter radiation resistance model is proposed by the method of analogy between two nuclear-related phenomena. Six epoxy systems are employed from the published literatures to verify the novel model and the result shows that it is reliable and helpful in not only estimating the radiation damage over the service period but also multi-objective optimum design of polymeric materials. - Highlights: • Radiation resistance of aromatic polymers was studied. • Percolation theory was employed to elucidate the critical phenomenon. • A novel two-parameter radiation resistance model was proposed and verified

  15. A new device for monitoring individual activity rhythms of honey bees reveals critical effects of the social environment on behavior.

    Science.gov (United States)

    Beer, Katharina; Steffan-Dewenter, Ingolf; Härtel, Stephan; Helfrich-Förster, Charlotte

    2016-08-01

    Chronobiological studies of individual activity rhythms in social insects can be constrained by the artificial isolation of individuals from their social context. We present a new experimental set-up that simultaneously measures the temperature rhythm in a queen-less but brood raising mini colony and the walking activity rhythms of singly kept honey bees that have indirect social contact with it. Our approach enables monitoring of individual bees in the social context of a mini colony under controlled laboratory conditions. In a pilot experiment, we show that social contact with the mini colony improves the survival of monitored young individuals and affects locomotor activity patterns of young and old bees. When exposed to conflicting Zeitgebers consisting of a light-dark (LD) cycle that is phase-delayed with respect to the mini colony rhythm, rhythms of young and old bees are socially synchronized with the mini colony rhythm, whereas isolated bees synchronize to the LD cycle. We conclude that the social environment is a stronger Zeitgeber than the LD cycle and that our new experimental set-up is well suited for studying the mechanisms of social entrainment in honey bees. PMID:27380473

  16. Genetic diversity analysis reveals that geographical environment plays a more important role than rice cultivar in Villosiclava virens population selection.

    Science.gov (United States)

    Wang, Fei; Zhang, Shu; Liu, Mei-Gang; Lin, Xian-Song; Liu, Hui-Jiang; Peng, You-Liang; Lin, Yang; Huang, Jun-Bin; Luo, Chao-Xi

    2014-05-01

    Rice false smut caused by Villosiclava virens is an economically important disease of grains worldwide. The genetic diversity of 153 isolates from six fields located in Wuhan (WH), Yichang Wangjia (YCW), Yichang Yaohe (YCY), Huanggang (HG), Yangxin (YX), and Jingzhou (JZ) in Hubei province of China were phylogenetically analyzed to evaluate the influence of environments and rice cultivars on the V. virens populations. Isolates (43) from Wuhan were from two rice cultivars, Wanxian 98 and Huajing 952, while most of the other isolates from fields YCW, YCY, HG, YX, and JZ originated from different rice cultivars with different genetic backgrounds. Genetic diversity of isolates was analyzed using random amplified polymorphic DNA (RAPD) and single-nucleotide polymorphisms (SNP). The isolates from the same cultivars in Wuhan tended to group together, indicating that the cultivars had an important impact on the fungal population. The 110 isolates from individual fields tended to cluster according to geographical origin. The values of Nei's gene diversity (H) and Shannon's information index (I) showed that the genetic diversity among isolates was higher between than within geographical populations. Furthermore, mean genetic distance between groups (0.006) was higher than mean genetic distance within groups (0.0048) according to MEGA 5.2. The pairwise population fixation index (FST) values also showed significant genetic differentiation between most populations. Higher genetic similarity of isolates from individual fields but different rice cultivars suggested that the geographical factor played a more important role in the selection of V. virens isolates than rice cultivars. This information could be used to improve the management strategy for rice false smut by adjusting the cultivation measures, such as controlling fertilizer, water, and planting density, in the rice field to change the microenvironment. PMID:24584249

  17. Pharmaceuticals and the Environment (PiE): Evolution and impact of the published literature revealed by bibliometric analysis.

    Science.gov (United States)

    Daughton, Christian G

    2016-08-15

    The evolution and impact of the published literature surrounding the transdisciplinary, multifaceted topic of pharmaceuticals as contaminants in the environment is examined for the first time in an historical context. The preponderance of literature cited in this examination represents the earlier works. As an historical chronology, the focus is on the emergence of key, specific aspects of the overall topic (often termed PiE) in the published literature and on the most highly cited works. This examination is not a conventional, technical review of the literature; as such, little attention was devoted to the more recent literature. The many dimensions involved with PiE span over 70years of published literature. Some articles began to appear in published works in the 1940s and earlier, while others only began to receive attention in the 1990s and later. Decades of early research on what at the time seemed to be disconnected topics eventually coalesced in the mid-to-late 1990s around a number of interconnected concerns and issues that now comprise PiE. Major objectives are to provide a new perspective to the topic, to facilitate more efficient and effective review of the literature by others, and to recognize the more significant, seminal contributions to the advancement of PiE as a field of research. Some of the most highly cited articles in all of environmental science now involve PiE. As of April 2015, a core group of 385 PiE articles had each received at least 200 citations; one had received 5424 citations. But hundreds of additional articles also played important roles in the evolution and advancement of the field. PMID:27104492

  18. A Reversible Pyrene-based Turn-on Luminescent Chemosensor for Selective Detection of Fe(3+) in Aqueous Environment with Logic Gate Application.

    Science.gov (United States)

    Mukherjee, Soma; Talukder, Shrabani

    2016-05-01

    A new Schiff-base, HL luminescent chemosensor of 1-amino pyrene and 8-hydroxy quinoline-2-carboxaldehyde was synthesized which demonstrates selective fluorimetric detection of Fe(3+) in aqueous medium with detection limit of 2.52 × 10(-8) M. The receptor shows selective 'turn-on' response towards Fe(3+) over other metal ions. This gradual 'turn-on' fluorescence response for Fe(3+) may be induced via CHEF (chelation-enhanced fluorescence) through close proximity of pyrene rings. The stoichiometry and binding property of HL with Fe(3+) was examined by emission studies. In presence of Fe(3+), HL also exhibits reversible change in emission pattern with EDTA and thus offers an interesting property of molecular 'INHIBIT' logic gate with Fe(3+) and EDTA as chemical inputs. PMID:27034064

  19. Preparation and Characterization of Poly(ethyl hydrazide Grafted Oil Palm Empty Fruit Bunch for Removal of Ni(II Ion in Aqueous Environment

    Directory of Open Access Journals (Sweden)

    Siti Mariam Mohd Nor

    2013-07-01

    Full Text Available Poly(ethyl hydrazide grafted oil palm empty fruit bunch (peh-g-opefb fiber has been successfully prepared by heating poly(methylacrylate-g-opefb at 60 °C for 4 h in a solution of hydrazine hydrate in ethanol. The chelating ability of peh-g-opefb was evaluated based on removal of Ni(II ions in aqueous solution. Adsorption of Ni(II by peh-g-opefb was characterized based on effect of pH, isotherm, kinetic and thermodynamic study. This cheap sorbent based on oil palm empty fruit bunch fiber has a great future potential in water treatment industries based on high adsorption capacity, biodegradability and renewability.

  20. A novel bio-adsorbent of mint waste for dyes remediation in aqueous environments: study and modeling of isotherms for removal of methylene Blue

    Directory of Open Access Journals (Sweden)

    Tarik Ainane

    2014-09-01

    Full Text Available The objective of this study was to investigate the possibility of using mint waste as a bioadsorbent for the removal of dye (Methylen Blue from aqueous solutions. Batch adsorption studies were carried out by monitoring the pH, the bio-adsorbent dose and the initial dye concentration. Attempts have also been made to monitor the adsorption process through Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin adsorption isotherm models. These results have demonstrated the immense potential of mint waste as a bioadsorbent for dyes remediation in polluted water and wastewater. Finally followed by the process of adsorption phenomenon was achieved by fourier transform infrared spectrometer (FTIR, the results shows that the adsorption is mechanical trapping.

  1. Hypersensitivity in the 4f-4f absorption spectra of tris (acetylacetonato) neodymium(III) complexes with imidazole and pyrazole in non-aqueous solutions. Effect of environment on hypersensitive transitions

    Energy Technology Data Exchange (ETDEWEB)

    Ansari, Anees A.; Ilmi, Rashid [Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Iftikhar, K., E-mail: kiftikhar.ch@jmi.ac.in [Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India)

    2012-01-15

    The optical absorption spectra of [Nd(acac){sub 3}(H{sub 2}O){sub 2}].H{sub 2}O, [Nd(acac){sub 3}(im){sub 2}] and [Nd(acac){sub 3}(pz){sub 2}] (where acac is the anion of acetylacetone, im is imidazole and pz is pyrazole) complexes in the visible region have been analyzed. The transition {sup 4}G{sub 5/2} <- {sup 4}I{sub 9/2} located near the middle of the visible region (17,500 cm{sup -1}) is hypersensitive. Its behavior is in sharp contrast to many other typically weak and consistently unvaried, normal 4f-4f transitions. It is overlapped by a less intense transition {sup 2}G{sub 7/2} <- {sup 4}I{sub 9/2}. The band shapes of the hypersensitive transition show remarkable changes on passing from aqueous solution to various non-aqueous solutions, which is the result of changes in the environment about the Nd(III) ion in the various solutions and suggests coordination of a solvent molecules. Pyridine has been found especially effective in promoting 4f-4f electric-dipole intensity. The DMSO invades the complexes and replaces the water molecules and heterocyclic amines from the coordination sphere. Two DMSO molecules coordinate and the complexes acquire similar structure, [Nd(acac){sub 3}(DMSO){sub 2}] in solution. The oscillator strength and the band shape of the hypersensitive transition of all the complexes remains the same in this solvent. The IR spectra and the NMR spectra of the complexes have also discussed. - Highlights: > Structurally similar eight-coordinate complexes of neodymium are synthesized. > The 4f-4f absorption spectra are investigated in non-aqueous solvents. > Methanol, isopropanol and acetonitrile are coordinating solvents. > Pyridine and DMSO are coordinating solvents by replacing the ancillary ligands. > Pyridine is most effective in promoting the 4f-4f intensity.

  2. Hypersensitivity in the 4f-4f absorption spectra of tris (acetylacetonato) neodymium(III) complexes with imidazole and pyrazole in non-aqueous solutions. Effect of environment on hypersensitive transitions

    International Nuclear Information System (INIS)

    The optical absorption spectra of [Nd(acac)3(H2O)2].H2O, [Nd(acac)3(im)2] and [Nd(acac)3(pz)2] (where acac is the anion of acetylacetone, im is imidazole and pz is pyrazole) complexes in the visible region have been analyzed. The transition 4G5/2 4I9/2 located near the middle of the visible region (17,500 cm-1) is hypersensitive. Its behavior is in sharp contrast to many other typically weak and consistently unvaried, normal 4f-4f transitions. It is overlapped by a less intense transition 2G7/2 4I9/2. The band shapes of the hypersensitive transition show remarkable changes on passing from aqueous solution to various non-aqueous solutions, which is the result of changes in the environment about the Nd(III) ion in the various solutions and suggests coordination of a solvent molecules. Pyridine has been found especially effective in promoting 4f-4f electric-dipole intensity. The DMSO invades the complexes and replaces the water molecules and heterocyclic amines from the coordination sphere. Two DMSO molecules coordinate and the complexes acquire similar structure, [Nd(acac)3(DMSO)2] in solution. The oscillator strength and the band shape of the hypersensitive transition of all the complexes remains the same in this solvent. The IR spectra and the NMR spectra of the complexes have also discussed. - Highlights: → Structurally similar eight-coordinate complexes of neodymium are synthesized. → The 4f-4f absorption spectra are investigated in non-aqueous solvents. → Methanol, isopropanol and acetonitrile are coordinating solvents. → Pyridine and DMSO are coordinating solvents by replacing the ancillary ligands. → Pyridine is most effective in promoting the 4f-4f intensity.

  3. 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 ...

  4. Chemistry of plutonium revealed

    International Nuclear Information System (INIS)

    In 1941 one goal of the Manhattan Project was to unravel the chemistry of the synthetic element plutonium as rapidly as possible. In this paper the work carried out at Berkeley from the spring of 1942 to the summer of 1945 is described briefly. The aqueous chemistry of plutonium is quite remarkable. Important insights were obtained from tracer experiments, but the full complexity was not revealed until macroscopic amounts (milligrams) became available. Because processes for separation from fission products were based on aqueous solutions, such solution chemistry was emphasized, particularly precipitation and oxidation-reduction behavior. The latter turned out to be unusually intricate when it was discovered that two more oxidation states existed in aqueous solution than had previously been suspected. Further, an equilibrium was rapidly established among the four aqueous oxidation states, while at the same time any three were not in equilibrium. These and other observations made while doing a crash study of a previously unknown element are reported

  5. Is food-related lifestyle (FRL) able to reveal food consumption patterns in non-western cultural environments? Its adaptation and application in urban China

    DEFF Research Database (Denmark)

    Grunert, Klaus G.; Perrea, Toula; Zhou, Yanfeng;

    Research related to food-related behaviour in China is still scarce, one reason being the fact that food consumption patterns in East Asia do not appear to be easily analyzed by models originating in Western cultures. The objective of the present work is to examine the ability of the Food Related...... Lifestyle (FRL) instrument to reveal food consumption patterns in a Chinese context. Data were collected from 479 respondents in 6 major Chinese cities using a Chinese version of the FRL instrument. Analysis of reliability and dimensionality of the scales resulted in a revised version of the instrument...... conceptual meaningfulness and applicability of FRL in non-Western food culture environments, when appropriately adapted....

  6. Aqueous medium induced optical transitions in cerium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Inerbaev, Talgat M.; Karakoti, Ajay S.; Kuchibhatla, S. V. N. T.; Kumar, Amit; Masunov, Artem E.; Seal, Sudipta

    2015-03-07

    Experimental and theoretical investigations were performed to investigate the effect of water on optical properties of nanoceria as a function of Ce3+ concentration. Theoretical studies based on density functional plane-wave calculations reveal that the indirect optical transitions in bare ceria nanoparticles are red-shifted with an increase in the concentration of Ce3+. However, ceria nanoparticles model with adsorbed water molecules show a blue shift in the indirect optical spectra under identical conditions. Direct optical transitions are almost independent of Ce3+ concentration but show a pronounced blue shift in the aqueous environment relative to the bare nanoparticles. The theoretical study is consistent with our experimental observation in difference of shift behaviour in bare and aqueous suspended ceria nanoparticles. This change from red- to blue-shift in indirect optical transitions is associated with the polarization effect of water molecules on f-electron states.

  7. Aqueous uranium concentrations in the natural environment

    International Nuclear Information System (INIS)

    Published geochemical data from groundwater and surface water throughout the world has been compiled in order to compare the concentration of naturally occurring dissolved uranium to lithology, sampling depth, pH, Eh, HCO3, SO4 and PO4 concentrations. The sole criterion used for the selection of data from the review articles was that each article contain raw data on naturally occurring uranium concentrations relative to other groundwater chemical components. A total of 1286 chemical data entries were used in the statistical comparisons. Although this database is not exhaustive, it is likely that the ranges of uranium concentrations in the data set are representative of the ranges occurring in nature. Finally, the observed uranium concentration distributions were compared with published results of model calculations and of used nuclear fuel leach tests. Models tend to predict a wider range of concentrations than observed (particularly the high values), and the leach test concentrations tend to fall within the upper half of the observations

  8. Oxide films in high temperature aqueous environments

    International Nuclear Information System (INIS)

    The evaluation of modified water chemistries as well as of the effects of increased power output in nuclear power plants is associated with a need to understand their effect on occupational dose rates and on environmentally assisted cracking as well as other types of corrosion of structural materials. Occupational dose rates are due to activity build-up on the primary circuit components, which in turn depends on the dissolution, transport, deposition and incorporation of the activated corrosion products in the oxide films formed on material surfaces. Accordingly, activity build-up is influenced by the electrochemical and electric properties of the oxide films and by the water chemistry of the coolant. Concerning different types of corrosion, it can with good reason be assumed that both the oxidation reaction related to corrosion (e.g. crack growth) as well as the coupled cathodic reaction involve steps in which charged species are transported through the oxide films formed on material surfaces either within the crack or on surfaces exposed to the bulk coolant. It can also be stated that a sufficient characterisation and a satisfactory model for the electrochemical behaviour and electric properties of the oxide films formed in nuclear power plants are not available. More experimental support is needed concerning especially the preferential paths and driving forces for ion transport as well as the nature of mobile species or defects. The lack of sufficient understanding has complicated the assessment of the applicability and possible side-effects of e.g. noble metal water chemistry and the injection of zinc as a means to prevent the uptake of activated corrosion products into corrosion films. The long-term aim of the work performed within the present research program is to minimise the risk of activity build-up, environmentally assisted cracking (EAC) and other types of corrosion, as well as to be prepared for the evaluation and introduction of modified water chemistries in Finnish power plants. To achieve this, the focus of this project is on understanding the mechanism of the incorporation of radioactive species into the different layers of the oxide film, as well as the transport phenomena contributing to stress corrosion cracking and other corrosion phenomena. This requires modelling the electrochemical behaviour and electrochemical and electric properties of oxide films formed on iron- and nickel-based alloys in relevant conditions. The project is divided into four sub-projects as follows: Behaviour of oxide films in plant conditions; Oxide films in simulated plant conditions; Modelling the processes in oxide films on metal surfaces; and Development of electrochemical measurements techniques for high-temperature measurements. (author)

  9. High-density universal 16S rRNA microarray analysis reveals broader diversity than typical clone library when sampling the environment.

    Science.gov (United States)

    DeSantis, Todd Z; Brodie, Eoin L; Moberg, Jordan P; Zubieta, Ingrid X; Piceno, Yvette M; Andersen, Gary L

    2007-04-01

    Molecular approaches aimed at detection of a broad-range of prokaryotes in the environment routinely rely on classifying heterogeneous 16S rRNA genes amplified by polymerase chain reaction (PCR) using primers with broad specificity. The general method of sampling and categorizing DNA has been to clone then sequence the PCR products. However, the number of clones required to adequately catalog the majority of taxa in a sample is unwieldy. Alternatively, hybridizing target sequences to a universal 16S rRNA gene microarray may provide a more rapid and comprehensive view of prokaryotic community composition. This study investigated the breadth and accuracy of a microarray in detecting diverse 16S rRNA gene sequence types compared to clone-and-sequencing using three environmental samples: urban aerosol, subsurface soil, and subsurface water. PCR products generated from universal 16S rRNA gene-targeted primers were classified by using either the clone-and-sequence method or by hybridization to a novel high-density microarray of 297,851 probes complementary to 842 prokaryotic subfamilies. The three clone libraries comprised 1391 high-quality sequences. Approximately 8% of the clones could not be placed into a known subfamily and were considered novel. The microarray results confirmed the majority of clone-detected subfamilies and additionally demonstrated greater amplicon diversity extending into phyla not observed by the cloning method. Sequences matching operational taxonomic units within the phyla Nitrospira, Planctomycetes, and TM7, which were uniquely detected by the array, were verified with specific primers and subsequent amplicon sequencing. Subfamily richness detected by the array corresponded well with nonparametric richness predictions extrapolated from clone libraries except in the water community where clone-based richness predictions were greatly exceeded. It was concluded that although the microarray is unreliable in identifying novel prokaryotic taxa, it

  10. Revealing the Didactic Character of Imagery in a Virtual World: Virtual Learning in the Three-Dimensional Animated Environment of Second Life

    Science.gov (United States)

    Han, Hsiao-Cheng

    2010-01-01

    Humans rely heavily on their sense of vision and look at images in response to their need for information. People learn from didactic images within environments; for this reason, in traditional educational environments, educators tend to care about visual representation. As today's technology brings images to wider audiences with more diverse…

  11. 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

  12. Impact of the hydropower installations on the environment as revealed in the environmental impact studies of the Institute of Hydroelectric Studies and Design

    International Nuclear Information System (INIS)

    The results of the studies of hydropower installation impact on the environment carried out by ISPH are presented. These studies are based on the recommendations of the UN Program for the Environment, as well as those of the European Community. In the period 1993-1995 more than 15 impact studies have been carried out taking into account aspects related to geology, geomorphology, seismology, hydrology, cultural-historical patrimony archaeology, tourism and aesthetics. Both high water fall and low water fall installations located at different altitudes have been analysed. Consequently, the construction of the dams were different. From the studies, three categories of problems can be reported: 1. specific problems of a certain hydropower installation; 2. specific problems of a certain type of hydropower installation; 3. general problems regardless of the power installation type. (author)

  13. pmoA-based analysis of methanotrophs in a littoral lake sediment reveals a diverse and stable community in a dynamic environment

    OpenAIRE

    Pester, Michael; Friedrich, Michael W.; Schink, Bernhard; Brune, Andreas

    2004-01-01

    Diversity and community structure of aerobic methane-oxidizing bacteria in the littoral sediment of Lake Constance was investigated by cloning analysis and terminal restriction fragment length polymorphism (T-RFLP) fingerprinting of the pmoA gene. Phylogenetic analysis revealed a high diversity of type I and type II methanotrophs in the oxygenated uppermost centimeter of the sediment. T-RFLP profiles indicated a high similarity between the active methanotrophic community in the oxic layer and...

  14. Separation, concentration and determination of chloramphenicol in environment and food using an ionic liquid/salt aqueous two-phase flotation system coupled with high-performance liquid chromatography.

    Science.gov (United States)

    Han, Juan; Wang, Yun; Yu, Cuilan; Li, Chunxiang; Yan, Yongsheng; Liu, Yan; Wang, Liang

    2011-01-31

    Ionic liquid-salt aqueous two-phase flotation (ILATPF) is a novel, green, non-toxic and sensitive samples pretreatment technique. ILATPF coupled with high-performance liquid chromatography (HPLC) was developed for the analysis of chloramphenicol, which combines ionic liquid aqueous two-phase system (ILATPS) based on imidazolium ionic liquid (1-butyl-3-methylimidazolium chloride, [C(4)mim]Cl) and inorganic salt (K(2)HPO(4)) with solvent sublation. In ILATPF systems, phase behaviors of the ILATPF were studied for different types of ionic liquids and salts. The sublation efficiency of chloramphenicol in [C(4)mim]Cl-K(2)HPO(4) ILATPF was influenced by the types of salts, concentration of K(2)HPO(4) in aqueous solution, solution pH, nitrogen flow rate, sublation time and the amount of [C(4)mim]Cl. Under the optimum conditions, the average sublation efficiency is up to 98.5%. The mechanism of ILATPF contains two principal processes. One is the mechanism of IL-salt ILATPS formation, the other is solvent sublation. This method was practical when applied to the analysis of chloramphenicol in lake water, feed water, milk, and honey samples with the linear range of 0.5-500 ng mL(-1). The method yielded limit of detection (LOD) of 0.1 ng mL(-1) and limit of quantification (LOQ) of 0.3 ng mL(-1). The recovery of CAP was 97.1-101.9% from aqueous samples of environmental and food samples by the proposed method. Compared with liquid-liquid extraction, solvent sublation and ionic liquid aqueous two-phase extraction, ILATPF can not only separate and concentrate chloramphenicol with high sublation efficiency, but also efficiently reduce the wastage of IL. This novel technique is much simpler and more environmentally friendly and is suggested to have important applications for the concentration and separation of other small biomolecules. PMID:21168562

  15. Dynamics of a photochromic spiropyran under aqueous conditions

    Directory of Open Access Journals (Sweden)

    Heckel A.

    2013-03-01

    Full Text Available The dynamics of a water soluble spiropyran is investigated by means of femtosecond transient absorption spectroscopy in the visible and infrared spectral range revealing an ultrafast reversible switching behavior under aqueous conditions with a high fatigue resistance.

  16. Thermal noise in aqueous quadrupole micro- and nano-traps

    OpenAIRE

    Park, Jae Hyun; Krstić, Predrag S.

    2012-01-01

    Recent simulations and experiments with aqueous quadrupole micro-traps have confirmed a possibility for control and localization of motion of a charged particle in a water environment, also predicting a possibility of further reduction of the trap size to tens of nano-meters for trapping charged bio-molecules and DNA segments. We study the random thermal noise due to Brownian motion in water which significantly influences the trapping of particles in an aqueous environment. We derive the exac...

  17. Mineralogic controls on aqueous neptunium(V) concentrations in silicate systems

    International Nuclear Information System (INIS)

    The presence of radioactive neptunium in commercially spent nuclear fuel is problematic due to its mobility in environmental systems upon oxidation to the pentavalent state. As uranium is the major component of spent fuel, incorporation of neptunium into resulting U(VI) mineral phases would potentially influence its release into environmental systems. Alternatively, aqueous neptunium concentrations may be buffered by solid phase Np2O5. In this study, we investigate both of these controls on aqueous neptunium(V) concentrations. We synthesize two uranyl silicates, soddyite, (UO2)2SiO4·2H2O, and boltwoodite, (K, Na)(UO2)(SiO3OH)·1.5H2O, each in the presence of two concentrations of aqueous Np(V). Electron microscopy and electron diffraction analyses of the synthesized phases show that while significant neptunyl incorporation occurred into soddyite, the Np(V) in the boltwoodite systems largely precipitated as a secondary phase, Np2O5(s). The release of Np(V) from each system into aqueous solution was measured for several days, until steady-state concentrations were achieved. Using existing solubility constants (Ksp) for pure soddyite and boltwoodite, we compared predicted equilibrium aqueous U(VI) concentrations with the U(VI) concentrations released in the solubility experiments. Our experiments reveal that Np(V) incorporation into soddyite increases the concentration of aqueous U in equilibrium with the solid phase, perhaps via the formation of a metastable phase. In the mixed boltwoodite – Np2O5(s) system, the measured aqueous U(VI) activities are consistent with those predicted to be in equilibrium with boltwoodite under the experimental conditions, a result that is consistent with our conclusion that little Np(V) incorporation occurred into the boltwoodite. In the boltwoodite systems, the measured Np concentrations are likely controlled by the presence of Np2O5 nanoparticles, suggesting an additional potential mobility vector for Np in geologic systems. Our

  18. The Genome Sequence of Methanohalophilus mahii SLPT Reveals Differences in the Energy Metabolism among Members of the Methanosarcinaceae Inhabiting Freshwater and Saline Environments

    Directory of Open Access Journals (Sweden)

    Stefan Spring

    2010-01-01

    Full Text Available Methanohalophilus mahii is the type species of the genus Methanohalophilus, which currently comprises three distinct species with validly published names. Mhp. mahii represents moderately halophilic methanogenic archaea with a strictly methylotrophic metabolism. The type strain SLPT was isolated from hypersaline sediments collected from the southern arm of Great Salt Lake, Utah. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 2,012,424 bp genome is a single replicon with 2032 protein-coding and 63 RNA genes and part of the Genomic Encyclopedia of Bacteria and Archaea project. A comparison of the reconstructed energy metabolism in the halophilic species Mhp. mahii with other representatives of the Methanosarcinaceae reveals some interesting differences to freshwater species.

  19. Is food-related lifestyle (FRL) able to reveal food consumption patterns in non-Western cultural environments? Its adaptation and application in urban China

    DEFF Research Database (Denmark)

    Grunert, Klaus; Perrea, Toula; Zhou, Yanfeng;

    2011-01-01

    Research related to food-related behaviour in China is still scarce, one reason being the fact that food consumption patterns in East Asia do not appear to be easily analyzed by models originating in Western cultures. The objective of the present work is to examine the ability of the food related...... lifestyle (FRL) instrument to reveal food consumption patterns in a Chinese context. Data were collected from 479 respondents in 6 major Chinese cities using a Chinese version of the FRL instrument. Analysis of reliability and dimensionality of the scales resulted in a revised version of the instrument, in...... values, attitudes and purchase behaviour, using frequency of consumption of pork products as an example. Three consumer segments were identified: concerned, uninvolved and traditional. This pattern replicates partly those identified in Western cultures. Moreover, all three segments showed consistent...

  20. Native sulfur, sulfates and sulfides from the active Campi Flegrei volcano (southern Italy): Genetic environments and degassing dynamics revealed by mineralogy and isotope geochemistry

    Science.gov (United States)

    Piochi, Monica; Mormone, Angela; Balassone, Giuseppina; Strauss, Harald; Troise, Claudia; De Natale, Giuseppe

    2015-10-01

    We investigated sulfur-bearing minerals from the Campi Flegrei caldera, southern Italy, in relation to the increase of hydrothermal activity phenomena since 2006, aimed at providing insights into the volcanic system dynamics. Mineral encrustations and muds were sampled between 2013 and 2015 at the long-standing degassing crater of the Solfatara tuff cone and its recently restless north-eastern Pisciarelli slope. Deep-seated sulfides were further separated from two drill cores (AGIP's Mofete boreholes: 1500 m and 2695 m depth). The mineral assemblage and texture of sampled encrustations were determined by X-ray diffraction, optical and scanning electron microscopy and X-ray microanalysis by energy dispersive spectrometry. Native sulfur and alunite dominate among the newly formed mineral phases. Other minerals are mostly alunogen, and locally pickeringite, potassium alum, hematite and pyrite. Mereiterite and amarillite sporadically occur. The mud pools are rich in gypsum, potassium alum and pyrite. Quartz and argillic phases, locally with analcime, are dispersed in the outcropping rocks. δ34S values were determined for shallow subsurface native sulfur (- 5.5 to 0.0‰) and alunite (- 1.7 to - 0.2‰), as well as for the deep-seated pyrite (3.3 to 7.4‰ in the depth range:1500-2695 m). δ18O values were measured for shallow native alunite (4.2 to 7.0‰). Pisciarelli alunite was finally analyzed for its 87Sr/86Sr ratio and 143Nd/144Nd ratios (0.707517 ± 6 and 0.512459 ± 6, respectively). Textural and isotopic data constrain the genesis of alunite at the expense of K-feldspars through rock alteration by hydrothermal fluids. We suggest that the caldera is a low-sulfidation system hosting acid-sulfate deposits in its active degassing area. The acid-sulfate environment developed on an argillitic facies that thins outwards and is characteristic for steam-heated and magmatic-steam environments. These environments developed in relation to the fractured settings that

  1. Why is seed production so variable among individuals? A ten-year study with oaks reveals the importance of soil environment.

    Directory of Open Access Journals (Sweden)

    Ignacio M Pérez-Ramos

    Full Text Available Mast-seeding species exhibit not only a large inter-annual variability in seed production but also considerable variability among individuals within the same year. However, very little is known about the causes and consequences for population dynamics of this potentially large between-individual variability. Here, we quantified seed production over ten consecutive years in two Mediterranean oak species - the deciduous Quercus canariensis and the evergreen Q. suber - that coexist in forests of southern Spain. First, we calibrated likelihood models to identify which abiotic and biotic variables best explain the magnitude (hereafter seed productivity and temporal variation of seed production at the individual level (hereafter CVi, and infer whether reproductive effort results from the available soil resources for the plant or is primarily determined by selectively favoured strategies. Second, we explored the contribution of between-individual variability in seed production as a potential mechanism of satiation for predispersal seed predators. We found that Q. canariensis trees inhabiting moister and more fertile soils were more productive than those growing in more resource-limited sites. Regarding temporal variation, individuals of the two studied oak species inhabiting these resource-rich environments also exhibited larger values of CVi. Interestingly, we detected a satiating effect on granivorous insects at the tree level in Q. suber, which was evident in those years where between-individual variability in acorn production was higher. These findings suggest that individual seed production (both in terms of seed productivity and inter-annual variability is strongly dependent on soil resource heterogeneity (at least for one of the two studied oak species with potential repercussions for recruitment and population dynamics. However, other external factors (such as soil heterogeneity in pathogen abundance or certain inherent characteristics of the

  2. The chemistry of plutonium revealed

    International Nuclear Information System (INIS)

    In 1941 one goal of the Manhattan Project was to unravel the chemistry of the synthetic element plutonium as rapidly as possible. Important insights were obtained from tracer experiments, but the full complexity of plutonium chemistry was not revealed until macroscopic amounts (milligrams) became available. Because processes for separation from fission products were aqueous solution based, such solution chemistry was emphasized, particularly precipitation and oxidation-reduction behavior. The latter turned out to be unusually intricate when it was discovered that two more oxidation states existed in aqueous solution than had previously been suspected. Further, it was found that an equilibrium was rapidly established among the four aqueous oxidation states while at the same time any three were not in equilibrium. These and other observations made while doing a crash study of a previously unknown element will be reported

  3. Aqueous polyethylene oxide solutions

    International Nuclear Information System (INIS)

    A number of aspects concerning the reorientation of polymer, water and ion hydration complexes have been studied in aqueous solution of polyethylene oxide (PEO). The polymer dynamics are investigated by 1H-PEO and 13C-PEO nuclear relaxation experiments. 162 refs.; 30 figs.; 19 tabs

  4. Bioreactor droplets from liposome-stabilized all-aqueous emulsions

    Science.gov (United States)

    Dewey, Daniel C.; Strulson, Christopher A.; Cacace, David N.; Bevilacqua, Philip C.; Keating, Christine D.

    2014-08-01

    Artificial bioreactors are desirable for in vitro biochemical studies and as protocells. A key challenge is maintaining a favourable internal environment while allowing substrate entry and product departure. We show that semipermeable, size-controlled bioreactors with aqueous, macromolecularly crowded interiors can be assembled by liposome stabilization of an all-aqueous emulsion. Dextran-rich aqueous droplets are dispersed in a continuous polyethylene glycol (PEG)-rich aqueous phase, with coalescence inhibited by adsorbed ~130-nm diameter liposomes. Fluorescence recovery after photobleaching and dynamic light scattering data indicate that the liposomes, which are PEGylated and negatively charged, remain intact at the interface for extended time. Inter-droplet repulsion provides electrostatic stabilization of the emulsion, with droplet coalescence prevented even for submonolayer interfacial coatings. RNA and DNA can enter and exit aqueous droplets by diffusion, with final concentrations dictated by partitioning. The capacity to serve as microscale bioreactors is established by demonstrating a ribozyme cleavage reaction within the liposome-coated droplets.

  5. In situ analysis of aqueous structure and adsorption at fluorocarbon, hydrocarbon and mineral surfaces

    Science.gov (United States)

    Hopkins, Adam Justin

    Altering and controlling the properties of solid surfaces in aqueous or other liquid phase environments has been a sought after objective for decades. With the discovery of chemisorbed self-assembled monolayers, this dream has become a reality. Oxide and metal surfaces can now be readily coated with an array of commercially available products to produce a desired fnctionality. The presence of these coatings on solid surfaces affects properties of the interfacial region by altering interfacial electrostatic fields, changing the structure of interfacial water molecules and altering the interactions of adsorbed species. This dissertation reports on in situ studies of adsorption at several solid/aqueous interfaces using vibrational sum-frequency spectroscopy, a surface specific technique. These studies are augmented by the use of atomic force microscopy and contact angle goniometry to characterize the prepared surfaces and their interactions with adsorbates. The studies investigate how changes in the surface structure and chemistry, as well as the bulk aqueous phase, affect interfacial structure. The studies within are primarily focused on the interactions of water with bare and functionalized fused silica and the relationship between the aqueous phase composition and the structure of fluorocarbon and hydrocarbon self-assembled monolayers. The variations in aqueous structure are then examined in detail using ionic strength controlled experiments to understand the direct interactions of water hydrophobically coated silica. This analysis is followed by an investigation of the competitive adsorption of methanol and water at fluorocarbon and hydrocarbon monolayers which show spectroscopic signatures of the interaction strength between fluorocarbons and hydrocarbons. Further studies are performed using butylammonium chloride to verify these spectroscopic signatures and reveal different molecular structures of adsorbed species at chemically different hydrophobic surfaces

  6. The Effect of Microwaves on Aqueous Corrosion of Glass

    OpenAIRE

    Lynch, Matthew Earl

    2006-01-01

    Glass corrodes in aqueous environments. The corrosion process is well-understood for many circumstances involving long periods of time at room temperature as well as processes that involve conventional heating, but the effect of microwave energy on glass corrosion has never been fully investigated. It was suspected that microwaves may alter or accelerate the aqueous corrosion processes that occur in glass which contribute to migration into foods or other materials. Lithium disilicate (Li2O...

  7. Aqueous chemistry of iodine

    International Nuclear Information System (INIS)

    The chemistry of iodine has been examined in aqueous solutions of pH 6 to 10 containing 2500 ppM boron as H3BO3 at temperatures up to 1500C using absorption spectrophotometry to identify and monitor the iodine species present. Kinetic rate constants for the disproportionation of the HOI intermediate, 3HOI= IO3- + 2I- + 3H+, have been measured as a function of pH even though no direct spectral evidence for HOI itself has been observed. An HOI partition coefficient >104 has been estimated; results of ionic strength tests are consistent with HOI being present as an uncharged triatomic species in solution. Redox and radiation effects on the aqueous iodine chemistry have also been described. 11 refs., 2 figs., 3 tabs

  8. The efficiency of magnetic carbon activated by iron oxide nanoparticles in removing of Cu (II from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Salehe Salehnia

    2016-04-01

    Full Text Available Background and Aim: Copper ions, due to forming complexes with organic and mineral compounds, can have worrying effects on health and environment. In the present study, the effect of powdered magnetic carbon activated by iron-oxide nanoparticles in removing of CU (V; II from aqueous solutions was assessed. Materials and Methods: This experimental study aimed at determining the effect of powdered magnetic carbon activated  by iron-oxide nanoparticles  parameters including PH, contact time, absorbing dose, and initial concentration on copper(II removal .from aqueous solutions; through an indirect current. In order to assess the qualities of the synthetized adsorbent, TGA, FT-IR and SEM tests were applied. Residual concentration of copper was measured at 324nm wavelength by means of atomic absorption spectrometry flame. The obtained data was analyzed using Langmuir and Freundlich isotherm model. Result: It was found that synthetic nanoparticles(PH=10, with the adsorbent dosage of 1gr/l, can remove more than 96% of copper ions from aqueous solutions at 2 minutes. Also, the results showed that copper absorption pattern is more in accord with Langmuir model.  Conclusion: Based on the current findings , magnetic synthesized nanoparticles coated with carbon. are in sporadic form in aqueous solutions. and can easily be separated using external magnetic environment. Moreover, because of existant active carbon sites absorption in iron oxide structure suferficial absorbtion capacity increases and and these nanoparticles reveal to have a high performance in the removing process of copper pollutants from aqueous solutions.

  9. Fabrication of novel magnetically separable BiOBr/CoFe2O4 microspheres and its application in the efficient removal of dye from aqueous phase by an environment-friendly and economical approach

    Science.gov (United States)

    Jiang, R.; Zhu, H.-Y.; Li, J.-B.; Fu, F.-Q.; Yao, J.; Jiang, S.-T.; Zeng, G.-M.

    2016-02-01

    Novel magnetically separable BiOBr/CoFe2O4 microspheres assembled from nanoparticles were successfully fabricated by a facile solvothermal method at 160 °C for 12 h. Then, BiOBr/CoFe2O4 microspheres were characterized via XRD, TEM, SEM, EDS and VSM. Congo red (CR) was selected as a pollutant model to evaluate the photocatalytic activities of BiOBr/CoFe2O4 microspheres. The value of coercivity (232 Oe) and the saturation magnetization (33.79 emu g-1) were obtained, which indicated that BiOBr/CoFe2O4 microspheres can be separated and recovered easily from the treated solution. What is more, by calculation, the initial rate constants of BiOBr/CoFe2O4 microspheres is about 1.45 times higher than that of the pure BiOBr, which resulted from superior adsorption and transfer performance to organic contaminants in aqueous systems. Four consecutive regeneration cycles demonstrated that the BiOBr/CoFe2O4 microspheres had high photostability under simulated solar light irradiation. According to the radical trapping experiments, the h+ radicals and O2rad - radicals were the two main active species that drive the photocolorization of CR pollutant by BiOBr/CoFe2O4 microspheres under simulated solar light irradiation. This work suggests that the BiOBr/CoFe2O4 microspheres may be a promising photocatalyst for photodegrading organic pollutants and environmental remediation.

  10. Acute aqueous toxicities of diesel-biodiesel blends

    Energy Technology Data Exchange (ETDEWEB)

    Hollebone, B.P.; Ho, N.; Landriault, M. [Environment Canada, Ottawa, ON (Canada). Emergencies Science and Technology Division, Science and Technology Branch, Environmental Science and Technology Centre; Harrison, S. [Science Applications International Corp., SAIC Canada, Ottawa, ON (Canada); Doe, K.; Jackman, P. [Environment Canada, Moncton, NB (Canada). Toxicology Laboratory, Environmental Science Centre

    2008-07-01

    The renewed interest in biodiesels as a new transportation fuel was discussed. Although there are several advantages to using biodiesels, their environmental behaviours and effects need to be evaluated along with the risks associated with their use, such as accidental releases of these biodiesels to the environment. The wide variability of biodiesels may result in different toxicological impacts, depending on the fuel feedstock. This study evaluated the aqueous effects of biodiesels from several commonly available feedstocks and their blends with petroleum diesel. Since most of the commercial uses of these products are currently focused on road-use, this study focused on the effects of these fuels in fresh-water. Biodiesels derived from soy, canola and waste restaurant oil feedstocks were used in the study. The acute toxicities of these biodiesels and biodiesel/petroleum diesel fuel blends were reported for 3 test species used by Environment Canada for toxicological evaluation, notably rainbow trout, the water flea, and a luminescent bacterium. The correlations between acute toxicity, water accommodated fractions (WAF) concentrations and fuel property data were examined. The study revealed that biodiesel is significantly less acutely toxic than petroleum diesels in potential ecological impacts. However, the biodiesel-diesel blends were found to be more acutely toxic than a linear dilution model predicts. 11 refs., 6 tabs., 3 figs.

  11. Mathematics revealed

    CERN Document Server

    Berman, Elizabeth

    1979-01-01

    Mathematics Revealed focuses on the principles, processes, operations, and exercises in mathematics.The book first offers information on whole numbers, fractions, and decimals and percents. Discussions focus on measuring length, percent, decimals, numbers as products, addition and subtraction of fractions, mixed numbers and ratios, division of fractions, addition, subtraction, multiplication, and division. The text then examines positive and negative numbers and powers and computation. Topics include division and averages, multiplication, ratios, and measurements, scientific notation and estim

  12. Revealed Attention

    OpenAIRE

    Masatlioglu, Yusufcan; NAKAJIMA, Daisuke; Ozbay, Erkut Y

    2012-01-01

    The standard revealed preference argument relies on an implicit assumption that a decision maker considers all feasible alternatives. The marketing and psychology literatures, however, provide wellestablished evidence that consumers do not consider all brands in a given market before making a purchase (Limited Attention). In this paper, we illustrate how one can deduce both the decision maker's preference and the alternatives to which she pays attention and inattention from the observed behav...

  13. Revealed Attention

    OpenAIRE

    Yusufcan Masatlioglu; Daisuke Nakajima; Ozbay, Erkut Y

    2012-01-01

    The standard revealed preference argument relies on an implicit assumption that a decision maker considers all feasible alternatives. The marketing and psychology literatures, however, provide well-established evidence that consumers do not consider all brands in a given market before making a purchase (Limited Attention). In this paper, we illustrate how one can deduce both the decision maker's preference and the alternatives to which she pays attention and inattention from the observed beha...

  14. Aqueous foam surfactants for geothermal drilling fluids: 1. Screening

    Energy Technology Data Exchange (ETDEWEB)

    Rand, P.B.

    1980-01-01

    Aqueous foam is a promising drilling fluid for geothermal wells because it will minimize damage to the producing formation and would eliminate the erosion problems of air drilling. Successful use of aqueous foam will require a high foaming surfactant which will: (1) be chemically stable in the harsh thermal and chemical environment, and (2) form stable foams at high temperatures and pressures. The procedures developed to generate and test aqueous foams and the effects of a 260/sup 0/C temperature cycle on aqueous surfactant solutions are presented. More than fifty selected surfactants were evaluated with representatives from the amphoteric, anionic, cationic, and nonionic classes included. Most surfactants were severely degraded by this temperature cycle; however, some showed excellent retention of their properties. The most promising surfactant types were the alkyl and alkyl aryl sulfonates and the ethoxylated nonionics.

  15. Tunable aqueous polymer-phase impregnated resins-technology-a novel approach to aqueous two-phase extraction.

    Science.gov (United States)

    van Winssen, F A; Merz, J; Schembecker, G

    2014-02-14

    Aqueous Two-Phase Extraction (ATPE) represents a promising unit operation for downstream processing of biotechnological products. The technique provides several advantages such as a biocompatible environment for the extraction of sensitive and biologically active compounds. However, the tendency of some aqueous two-phase systems to form intensive and stable emulsions can lead to long phase separation times causing an increased footprint for the required mixer-settler devices or the need for additional equipment such as centrifuges. In this work, a novel approach to improve ATPE for downstream processing applications called 'Tunable Aqueous Polymer-Phase Impregnated Resins' (TAPPIR(®))-Technology is presented. The technology is based on the immobilization of one aqueous phase inside the pores of a solid support. The second aqueous phase forms the bulk liquid around the impregnated solids. Due to the immobilization of one phase, phase emulsification and phase separation of ATPE are realized in a single step. In this study, a biodegradable and sustainable aqueous two-phase system consisting of aqueous polyethylene glycol/sodiumcitrate solutions was chosen. The impregnation of different macroporous glass and ceramic solids was investigated and could be proven to be stable. Additionally, the separation of the dye Patent blue V was successfully performed with the TAPPIR(®)-Technology. Thus, the "proof of principle" of this technology is presented. PMID:24462465

  16. Hydrophobic effect at aqueous interfaces

    Science.gov (United States)

    Pohorille, Andrew

    2005-01-01

    Conceptual basis for hydrophobic effects in bulk water and at aqueous interfaces have similar conceptual basis but often manifests itself differently. Using a wide range of computer simulations as the basis, I will review different forms of hydrophobic effects at a variety of interfaces starting from simple liquid-vapor and water-oil interfaces and progressing to water-membrane interfaces. I will start with discussing how water is organized at different interfaces, stressing both similarities and differences. The main thread is that, as in the bulk liquid, hydrophobic effects have profound influence on conformational equilibria and organization of both small molecules and macromolecules, but the result of this influence is quite different. Specifically, it will be shown that many small, but not necessarily amphiphilic molecules tend to accumulate at the interface and, and this tendency will be explained. Furthermore, I will show that many short peptides that are disordered in water spontaneously fold into well-defined structures in the interfacial environment. Biological implications of this self-organizing effect will be discussed.

  17. Aqueous Photochemistry of Glyoxylic Acid.

    Science.gov (United States)

    Eugene, Alexis J; Xia, Sha-Sha; Guzman, Marcelo I

    2016-06-01

    Aerosols affect climate change, the energy balance of the atmosphere, and public health due to their variable chemical composition, size, and shape. While the formation of secondary organic aerosols (SOA) from gas phase precursors is relatively well understood, studying aqueous chemical reactions contributing to the total SOA budget is the current focus of major attention. Field measurements have revealed that mono-, di-, and oxo-carboxylic acids are abundant species present in SOA and atmospheric waters. This work explores the fate of one of these 2-oxocarboxylic acids, glyoxylic acid, which can photogenerate reactive species under solar irradiation. Additionally, the dark thermal aging of photoproducts is studied by UV-visible and fluorescence spectroscopies to reveal that the optical properties are altered by the glyoxal produced. The optical properties display periodicity in the time domain of the UV-visible spectrum of chromophores with absorption enhancement (thermochromism) or loss (photobleaching) during nighttime and daytime cycles, respectively. During irradiation, excited state glyoxylic acid can undergo α-cleavage or participate in hydrogen abstractions. The use of (13)C nuclear magnetic resonance spectroscopy (NMR) analysis shows that glyoxal is an important intermediate produced during direct photolysis. Glyoxal quickly reaches a quasi-steady state as confirmed by UHPLC-MS analysis of its corresponding (E) and (Z) 2,4-dinitrophenylhydrazones. The homolytic cleavage of glyoxylic acid is proposed as a fundamental step for the production of glyoxal. Both carbon oxides, CO2(g) and CO(g) evolving to the gas-phase, are quantified by FTIR spectroscopy. Finally, formic acid, oxalic acid, and tartaric acid photoproducts are identified by ion chromatography (IC) with conductivity and electrospray (ESI) mass spectrometry (MS) detection and (1)H NMR spectroscopy. A reaction mechanism is proposed based on all experimental observations. PMID:27192089

  18. Revealing Rembrandt

    Directory of Open Access Journals (Sweden)

    Andrew J Parker

    2014-04-01

    Full Text Available The power and significance of artwork in shaping human cognition is self-evident. The starting point for our empirical investigations is the view that the task of neuroscience is to integrate itself with other forms of knowledge, rather than to seek to supplant them. In our recent work, we examined a particular aspect of the appreciation of artwork using present-day functional magnetic resonance imaging (fMRI. Our results emphasised the continuity between viewing artwork and other human cognitive activities. We also showed that appreciation of a particular aspect of artwork, namely authenticity, depends upon the co-ordinated activity between the brain regions involved in multiple decision making and those responsible for processing visual information. The findings about brain function probably have no specific consequences for understanding how people respond to the art of Rembrandt in comparison with their response to other artworks. However, the use of images of Rembrandt’s portraits, his most intimate and personal works, clearly had a significant impact upon our viewers, even though they have been spatially confined to the interior of an MRI scanner at the time of viewing. Neuroscientific studies of humans viewing artwork have the capacity to reveal the diversity of human cognitive responses that may be induced by external advice or context as people view artwork in a variety of frameworks and settings.

  19. Assembly of DNA Architectures in a Non-Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Thomas J. Proctor

    2012-08-01

    Full Text Available In the present work, the procedures for the creation of self-assembled DNA nanostructures in aqueous and non-aqueous media are described. DNA-Surfactant complex formation renders the DNA soluble in organic solvents offering an exciting way to bridge the transition of DNA origami materials electronics applications. The DNA retains its structural features, and these unique geometries provide an interesting candidate for future electronics and nanofabrication applications with potential for new properties. The DNA architectures were first assembled under aqueous conditions, and then characterized in solution (using circular dichroism (CD spectroscopy and on the surface (using atomic force microscopy (AFM. Following aqueous assembly, the DNA nanostructures were transitioned to a non-aqueous environment, where butanol was chosen for optical compatibility and thermal properties. The retention of DNA hierarchical structure and thermal stability in non-aqueous conditions were confirmed via CD spectroscopy. The formation and characterization of these higher order DNA-surfactant complexes is described in this paper.

  20. Application of Moringa Peregrina seed extract as a natural coagulant for Phenol removal from aqueous solution

    Directory of Open Access Journals (Sweden)

    Edris Bazrafshan

    2013-02-01

    Conclusion: According to the obtained results, Moringa peregrina seed extract, with respect to its high efficacy, can be used as an effective, efficient, and inexpensive coagulant in removing phenol from aqueous environments.

  1. The DEPTHX Project: Pioneering Technologies for Exploration of Extraterrestrial Aqueous Channels

    Science.gov (United States)

    Stone, W. C.; Greenberg, R. J.; Durda, D. D.; Franke, E. A.

    2005-03-01

    This project is developing an autonomous vehicle for underwater exploration of confined channels, with sensors for life detection, in preparation for eventual missions to extraterrestrial aqueous environments, e.g. suboceanic hydrothermal vents or crustal cracks on Europa.

  2. Sulfates on Mars: Indicators of Aqueous Processes

    Science.gov (United States)

    Bishop, Janice L.; Lane, Melissa D.; Dyar, M. Darby; Brown, Adrian J.

    2006-01-01

    Recent analyses by MER instruments at Meridiani Planum and Gusev crater and the OMEGA instrument on Mars Express have provided detailed information about the presence of sulfates on Mars [1,2,3]. We are evaluating these recent data in an integrated multi-disciplinary study of visible-near-infrared, mid-IR and Mossbauer spectra of several sulfate minerals and sulfate-rich analog sites. Our analyses suggest that hydrated iron sulfates may account for features observed in Mossbauer and mid-IR spectra of Martian soils [4]. The sulfate minerals kieserite, gypsum and other hydrated sulfates have been identified in OMEGA spectra in the layered terrains in Valles Marineris and Terra Meridiani [2]. These recent discoveries emphasize the importance of studying sulfate minerals as tracers of aqueous processes. The sulfate-rich rock outcrops observed in Meridiani Planum may have formed in an acidic environment similar to acid rock drainage environments on Earth [5]. Because microorganisms typically are involved in the oxidation of sulfides to sulfates in terrestrial sites, sulfate-rich rock outcrops on Mars may be a good location to search for evidence of past life on that planet. Whether or not life evolved on Mars, following the trail of sulfate minerals will lead to a better understanding of aqueous processes and chemical weathering.

  3. Mars Aqueous Processing System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Mars Aqueous Processing System (MAPS) is an innovative method to produce useful building materials from Martian regolith. Acids and bases produced from the regolith...

  4. Mars Aqueous Processing System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Mars Aqueous Processing System (MAPS) is a novel technology for recovering oxygen, iron, and other constituents from lunar and Mars soils. The closed-loop...

  5. Catalytic Radical Reduction in Aqueous Solution by a Ruthenium Hydride Intermediate.

    Science.gov (United States)

    Htet, Yamin; Tennyson, Andrew G

    2016-07-18

    Some manganese complexes can catalyze both antioxidant and pro-oxidant reactions, whereby the disparate reactivity modes are determined by the catalyst environment and afford distinct therapeutic effects. We recently reported the reduction of radicals in buffered aqueous solution catalyzed by a ruthenium complex with biologically relevant non-tertiary alcohols as terminal reductants. Mechanistic evidence is presented, indicating that this catalytic radical reduction is achieved by a Ru-hydride intermediate formed by β-hydride elimination from a Ru-alkoxide species. A similar mechanism and Ru-hydride intermediate was previously reported to kill cancer cells with catalytic pro-oxidant effects. Therefore, our demonstration of catalytic antioxidant effects by the same type of intermediate reveals new potential therapeutic strategies and applications for catalytic systems that form Ru-hydride intermediates. PMID:27254303

  6. Effect of bentonite on radiation induced dissolution of UO{sub 2} in an aqueous system

    Energy Technology Data Exchange (ETDEWEB)

    Barreiro Fidalgo, Alexandre, E-mail: alebf@kth.se; Sundin, Sara, E-mail: saramara@kth.se; Jonsson, Mats, E-mail: matsj@kth.se

    2014-04-01

    In order to elucidate the impact of bentonite on the process of radiation induced oxidative dissolution of UO{sub 2} in an aqueous system, the dissolution of U(VI) and consumption of H{sub 2}O{sub 2} over time has been studied. In addition, γ-irradiation experiments were performed to study a more relevant and complex system, serving as a comparison with the previously stated system. In both cases, the experiments revealed that the presence of bentonite in water could either delay or prevent in part the release of uranium to the environment. The cause is mainly attributed to the scavenging of radiolytic oxidants rather than to the adsorption of uranium onto bentonite.

  7. Aqueous solubility, dispersibility and toxicity of biodiesels

    Energy Technology Data Exchange (ETDEWEB)

    Hollebone, B.P.; Fieldhouse, B.; Lumley, T.C.; Landriault, M. [Environment Canada, Ottawa, ON (Canada). ; Doe, K.; Jackman, P. [Environment Canada, Moncton, NB (Canada). Toxicology Laboratory, Environmental Science Centre

    2007-07-01

    The renewed interest in the use of biological fuels can be attributed to that fact that feedstocks for fatty-acid ester biodiesels are renewable and can be reclaimed from waste. Although there are significant benefits to using biodiesels, their increased use leaves potential for accidental release to the environment. Therefore, their environmental behaviours and impacts must be evaluated along with the risk associated with their use. Biodiesel fuels may be made from soy oil, canola oil, reclaimed restaurant grease, fish oil and animal fat. The toxicological fate of biofuel depends on the variability of its chemical composition. This study provided an initial assessment of the aqueous fate and effects of biodiesel from a broad range of commonly available feedstocks and their blends with petroleum diesels. The study focused primarily on the fate and impact of these fuels in fresh-water. The use of chemical dispersion as a countermeasure for saltwater was also investigated. The exposure of aquatic ecosystems to biodiesels and petroleum diesel occurs via the transfer of material from the non-aqueous phase liquid (NAPL) into the aqueous phase, as both soluble and dispersed components. The aqueous solubilities of the fuels were determined from the equilibrium water-accommodated fraction concentrations. The acute toxicities of many biodiesels were reported for 3 test species used by Environment Canada for toxicological evaluation, namely rainbow trout, the water flea and a luminescent bacterium. This study also evaluated the natural potential for dispersion of the fuels in the water column in both low and high-energy wave conditions. Chemical dispersion as a potential countermeasure for biodiesel spills was also evaluated using solubility testing, acute toxicity testing, and dispersibility testing. It was shown that biodiesels have much different fates and impacts from petroleum diesels. The compounds partitioning into the water column are also very different for each

  8. Aqueous solubility, dispersibility and toxicity of biodiesels

    International Nuclear Information System (INIS)

    The renewed interest in the use of biological fuels can be attributed to that fact that feedstocks for fatty-acid ester biodiesels are renewable and can be reclaimed from waste. Although there are significant benefits to using biodiesels, their increased use leaves potential for accidental release to the environment. Therefore, their environmental behaviours and impacts must be evaluated along with the risk associated with their use. Biodiesel fuels may be made from soy oil, canola oil, reclaimed restaurant grease, fish oil and animal fat. The toxicological fate of biofuel depends on the variability of its chemical composition. This study provided an initial assessment of the aqueous fate and effects of biodiesel from a broad range of commonly available feedstocks and their blends with petroleum diesels. The study focused primarily on the fate and impact of these fuels in fresh-water. The use of chemical dispersion as a countermeasure for saltwater was also investigated. The exposure of aquatic ecosystems to biodiesels and petroleum diesel occurs via the transfer of material from the non-aqueous phase liquid (NAPL) into the aqueous phase, as both soluble and dispersed components. The aqueous solubilities of the fuels were determined from the equilibrium water-accommodated fraction concentrations. The acute toxicities of many biodiesels were reported for 3 test species used by Environment Canada for toxicological evaluation, namely rainbow trout, the water flea and a luminescent bacterium. This study also evaluated the natural potential for dispersion of the fuels in the water column in both low and high-energy wave conditions. Chemical dispersion as a potential countermeasure for biodiesel spills was also evaluated using solubility testing, acute toxicity testing, and dispersibility testing. It was shown that biodiesels have much different fates and impacts from petroleum diesels. The compounds partitioning into the water column are also very different for each

  9. Radiolysis of aqueous solutions of sodium sulfides. Chapter 8

    International Nuclear Information System (INIS)

    To study the radiolysis of the aqueous solutions of sodium sulphide, use was made of infrared spectroscopy, mass-spectrometry and iodometric titration. During the γ-irradiation of the aqueous solutions of sodium sulphide one can observe the appearance of various stable sulphur-containing products. Data are discussed on the radiolysis in a nitrous environment, on oxygen bubbling, at varying radiation doses, pH and temperature values. Consideration is also given to the low-temperature radiolysis of the aqueous solutions of sodium sulphide by the EPR method. In the radiolysis of both crystalline and glassy solutions of Na2S there appear an ion-radical S- and a radical SO2-

  10. Aqueous chlorination of mefenamic acid: kinetics, transformation by-products and ecotoxicity assessment.

    Science.gov (United States)

    Adira Wan Khalit, Wan Nor; Tay, Kheng Soo

    2016-05-18

    Mefenamic acid (Mfe) is one of the most frequently detected nonsteroidal anti-inflammatory drugs in the environment. This study investigated the kinetics and the transformation by-products of Mfe during aqueous chlorination. The potential ecotoxicity of the transformation by-products was also evaluated. In the kinetic study, the second-order rate constant (kapp) for the reaction between Mfe and free available chlorine (FAC) was determined at 25 ± 0.1 °C. The result indicated that the degradation of Mfe by FAC is highly pH-dependent. When the pH was increased from 6 to 8, it was found that the kapp for the reaction between Mfe and FAC was decreased from 16.44 to 4.4 M(-1) s(-1). Characterization of the transformation by-products formed during the chlorination of Mfe was carried out using liquid chromatography-quadrupole time-of-flight accurate mass spectrometry. Four major transformation by-products were identified. These transformation by-products were mainly formed through hydroxylation, chlorination and oxidation reactions. Ecotoxicity assessment revealed that transformation by-products, particularly monohydroxylated Mfe which is more toxic than Mfe, can be formed during aqueous chlorination. PMID:27062128

  11. Heteroaggregation of engineered nanoparticles and kaolin clays in aqueous environments

    OpenAIRE

    Wang, H.; Dong, YN; Zhu, M.; Li, X.; Keller, AA; Wang, T.; Li, F.

    2015-01-01

    © 2015 Elsevier Ltd. The increasing and wide use of nanoparticles (NPs), including TiO2 and Ag NPs, have raised concerns due to their potential toxicity and environmental impacts. Kaolin is a very common mineral in aquatic systems, and there is a very high probability that nanoparticles (NPs) will interact with these clay minerals. We studied the effect of kaolin particles on the aggregation of NPs under different conditions, including the role of pH, ionic strength (IS), and humic acid (HA)....

  12. Electroanalytical methods in characterization of sulfur species in aqueous environment

    Directory of Open Access Journals (Sweden)

    Irena Ciglenečki

    2014-12-01

    Full Text Available Electroanalytical (voltammetric, polarographic, chronoamperometric methods on an Hg electrode were applied for studying of different sulfur compounds in model and natural water systems (anoxic lakes, waste water, rain precipitation, sea-aerosols. In all investigated samples typical HgS reduction voltammetric peak, characteristic for many different reduced sulfur species (RSS: sulfide, elemental sulfur, polysulfide, labile metal sulfide and organosulfur species was recorded at about -0.6 V vs. Ag/AgCl reference electrode. In addition, in anoxic waters which are enriched with sulfide and iron species, voltammetric peaks characteristic for the presence of free Fe(II and FeS nanoparticles (NPs were recorded at -1.4 V and around -0.45 V, respectively. Depending on the used electroanalytical method and experimental conditions (varying deposition potential, varying time of oxidative and/or reductive accumulation, sample pretreatment i.e. acidification followed by purging it is possible to distinguish between different sulfur species. This work clearly shows a large potential of the electrochemistry as a powerful analytical technique for screening water quality regarding presence of different reduced sulfur species and their speciation between dissolved and colloidal/nanoparticle phases.

  13. 2010 Water & Aqueous Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Dor Ben-Amotz

    2010-08-13

    Water covers more than two thirds of the surface of the Earth and about the same fraction of water forms the total mass of a human body. Since the early days of our civilization water has also been in the focus of technological developments, starting from converting it to wine to more modern achievements. The meeting will focus on recent advances in experimental, theoretical, and computational understanding of the behavior of the most important and fascinating liquid in a variety of situations and applications. The emphasis will be less on water properties per se than on water as a medium in which fundamental dynamic and reactive processes take place. In the following sessions, speakers will discuss the latest breakthroughs in unraveling these processes at the molecular level: Water in Solutions; Water in Motion I and II; Water in Biology I and II; Water in the Environment I and II; Water in Confined Geometries and Water in Discussion (keynote lecture and poster winners presentations).

  14. Non-Aqueous Capillary Electrophoresis

    Science.gov (United States)

    Szumski, Michał; Buszewski, Bogusław

    Non-aqueous capillary electrophoresis and capillary electrochromatography are special variants of these techniques. Here, organic solvents or their mixtures with or without dissolved electrolytes are used as separation buffer or mobile phase, respectively. The most important features of non-aqueous systems are: better solubility of more hydrophobic ionic substances (many natural products) than in water, much less current and Joule heating allows for using highly concentrated buffers and/or larger capillary internal diameters, polar interactions are enhanced in organic solvents which is often highly advantageous in chiral separation systems. This chapter presents most frequently used solvents, their properties, as well as shows pH* scale which is often used in non-aqueous systems.

  15. 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

  16. Aqueous two-phase system based on natural quaternary ammonium compounds for the extraction of proteins.

    Science.gov (United States)

    Zeng, Chao-Xi; Xin, Rui-Pu; Qi, Sui-Jian; Yang, Bo; Wang, Yong-Hua

    2016-02-01

    Aqueous two-phase systems, based on the use of natural quaternary ammonium compounds, were developed to establish a benign biotechnological route for efficient protein separation. In this study, aqueous two-phase systems of two natural resources betaine and choline with polyethyleneglycol (PEG400/600) or inorganic salts (K2 HPO4 /K3 PO4 ) were formed. It was shown that in the K2 HPO4 -containing aqueous two-phase system, hydrophobic interactions were an important driving force of protein partitioning, while protein size played a vital role in aqueous two-phase systems that contained polyethylene glycol. An extraction efficiency of more than 90% for bovine serum albumin in the betaine/K2 HPO4 aqueous two-phase system can be obtained, and this betaine-based aqueous two-phase system provided a gentle and stable environment for the protein. In addition, after investigation of the cluster phenomenon in the betaine/K2 HPO4 aqueous two-phase systems, it was suggested that this phenomenon also played a significant role for protein extraction in this system. The development of aqueous two-phase systems based on natural quaternary ammonium compounds not only provided an effective and greener method of aqueous two-phase system to meet the requirements of green chemistry but also may help to solve the mystery of the compartmentalization of biomolecules in cells. PMID:26447826

  17. Functional Comparison of Bacteria from the Human Gut and Closely Related Non-Gut Bacteria Reveals the Importance of Conjugation and a Paucity of Motility and Chemotaxis Functions in the Gut Environment

    Science.gov (United States)

    Dobrijevic, Dragana; Abraham, Anne-Laure; Jamet, Alexandre; Maguin, Emmanuelle; van de Guchte, Maarten

    2016-01-01

    The human GI tract is a complex and still poorly understood environment, inhabited by one of the densest microbial communities on earth. The gut microbiota is shaped by millennia of evolution to co-exist with the host in commensal or symbiotic relationships. Members of the gut microbiota perform specific molecular functions important in the human gut environment. This can be illustrated by the presence of a highly expanded repertoire of proteins involved in carbohydrate metabolism, in phase with the large diversity of polysaccharides originating from the diet or from the host itself that can be encountered in this environment. In order to identify other bacterial functions that are important in the human gut environment, we investigated the distribution of functional groups of proteins in a group of human gut bacteria and their close non-gut relatives. Complementary to earlier global comparisons between different ecosystems, this approach should allow a closer focus on a group of functions directly related to the gut environment while avoiding functions related to taxonomically divergent microbiota composition, which may or may not be relevant for gut homeostasis. We identified several functions that are overrepresented in the human gut bacteria which had not been recognized in a global approach. The observed under-representation of certain other functions may be equally important for gut homeostasis. Together, these analyses provide us with new information about this environment so critical to our health and well-being. PMID:27416027

  18. Removal of radium from aqueous sulphate solutions

    International Nuclear Information System (INIS)

    Radium is often present in ores and an aqueous solution associated with the ore may consequently contain dissolved radium. It is frequently necessary to remove radium from such solutions to reduce the total radium content to a prescribed low level before the solution can be returned to the environment. The present invention is based on the discovery that the total radium content can be reduced to a satisfactory level within a reasonable time by adding a soluble barium salt to a radium-containing sulphate solution which also contains dissolved magnesium at a pH not greater than about 0 to precipitate radium as barium radium sulphate, raising the pH to at least 11 to precipitate an insoluble magnesium compound which collects the barium radium sulphate precipitate, and separating substantially all of the precipitates from the solution

  19. Thermal noise in aqueous quadrupole micro- and nano-traps.

    Science.gov (United States)

    Park, Jae Hyun; Krstić, Predrag S

    2012-01-01

    Recent simulations and experiments with aqueous quadrupole micro-traps have confirmed a possibility for control and localization of motion of a charged particle in a water environment, also predicting a possibility of further reduction of the trap size to tens of nano-meters for trapping charged bio-molecules and DNA segments. We study the random thermal noise due to Brownian motion in water which significantly influences the trapping of particles in an aqueous environment. We derive the exact, closed-form expressions for the thermal fluctuations of position and velocity of a trapped particle and thoroughly examine the properties of the rms for the fluctuations as functions of the system parameters and time. The instantaneous signal transferring mechanism between the velocity and position fluctuations could not be achieved in the previous phase-average approaches. PMID:22369362

  20. Aqueous coordination complexes of neptunium

    International Nuclear Information System (INIS)

    Thecomplex formation constants, obtained by different methods, for the complexing of neptunium, in different oxidation states, in aqueous solutions, with several organic and inorganic ligands, have been critically reviewed. The values for the thermodynamic parameters associated with the complex formation, wherever available, are also presented. (author)

  1. Aqueous systems and geothermal energy

    International Nuclear Information System (INIS)

    Significant unpublished results reported include: osmotic coefficients of KCl solutions vs. molality at 109 to 2010C; cadmium ion diffusivities in CaCl2 hydrous melts; a x-ray diffraction study of the uranyl complex in water; solubility of amorphous silica in aqueous NaNO3 solutions at 100 to 3000C; and corrosion of carbon steel by geothermal brine

  2. Versatile electrochemical coatings and surface layers from aqueous methanesulfonic acid

    OpenAIRE

    Walsh, F. C.; Ponce De Leon, Carlos

    2014-01-01

    Ever tightening environmental pressure together with the continued need for coatings able to meet challenging service environments have stimulated advances in coating technology. In the case of electrochemical techniques, the classical techniques of electrodeposition and anodising are being upgraded to meet the need for modern surface engineering coatings (including nanostructured films) on metals. A major challenge is to retain conventional processing, including aqueous solutions, simple pow...

  3. Photocatalytic oxidation of fuel oxygenated additives in aqueous solutions

    OpenAIRE

    Krichevskaya, M.; Kachina, A.; T. Malygina; Preis, S.; J. Kallas

    2003-01-01

    Experimental research of photocatalytical oxidation (PCO) of aqueous solutions of de-icing agents (ethylene glycol and ethylene glycol monoethyl ether) and methyl tert-butyl ether (MTBE) was undertaken. These chemicals are water-soluble components of jet and motor fuels accidentally disposed to the environment. Titanium dioxide (Degussa P25) under near-UV irradiation was selected as a photocatalyst. A slightly acidic medium was preferable for the process efficiency for MTBE, whereas a neutral...

  4. Characterizing Fullerene Nanoparticles in Aqueous Suspensions

    Science.gov (United States)

    Studies have indicated that fullerenes can form stable colloidal suspensions in water when introduced to the aqueous phase through solvent exchange, sonication, or extended mixing. The colloidal suspensions created using these techniques have effective aqueous phase concentratio...

  5. The atomic level journey from aqueous polyoxometalate to metal oxide

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Yu; Fast, Dylan B.; Ruther, Rose E.; Amador, Jenn M.; Fullmer, Lauren B.; Decker, Shawn R.; Zakharov, Lev N.; Dolgos, Michelle R., E-mail: Michelle.Dolgos@oregonstate.edu; Nyman, May, E-mail: May.Nyman@oregonstate.edu

    2015-01-15

    Aqueous precursors tailored for the deposition of thin film materials are desirable for sustainable, simple, low energy production of advanced materials. Yet the simple practice of using aqueous precursors is complicated by the multitude of interactions that occur between ions and water during dehydration. Here we use lithium polyoxoniobate salts to investigate the fundamental interactions in the transition from precursor cluster to oxide film. Small-angle X-ray scattering of solutions, total X-ray scattering of intermediate gels, and morphological and structural characterization of the lithium niobate thin films reveal the atomic level transitions between these states. The studies show that (1) lithium–[H{sub 2}Nb{sub 6}O{sub 19}]{sup 6−} has drastically different solution behaviour than lithium–[Nb{sub 6}O{sub 19}]{sup 8−}, linked to the precursor salt structure (2) in both compositions, the intermediate gel preserves the polyoxoniobate clusters and show similar local order and (3) the morphology and phases of deposited films reflect the ions behaviour throughout the journey from cluster solution to metal oxide. - Graphical abstract: Aqueous lithium polyoxoniobate salts were used to prepare lithium niobate (LiNbO{sub 3}) thin films. Fundamental studies were performed to investigate the interactions in the transition from precursor cluster to the oxide film. It was found that acid–base and ion-association chemistries of the aqueous and gel systems significantly affect the key processes in this atom-level journey. - Highlights: • Lithium polyoxoniobate clusters were synthesized with control over Li:Nb ratio as precursors for LiNbO{sub 3} films. • X-ray scattering studies in solution and the solid-state revealed differences controlled by Li:Nb ratio. • Film deposition studies revealed phase, composition and morphology is controlled by Li:Nb ratio. • Cluster to film transformation was revealed using total X-ray scattering and TGA.

  6. Aqueous chloride stress corrosion cracking of titanium - A comparison with environmental hydrogen embrittlement

    Science.gov (United States)

    Nelson, H. G.

    1974-01-01

    The physical characteristics of stress corrosion cracking of titanium in an aqueous chloride environment are compared with those of embrittlement of titanium by a gaseous hydrogen environment in an effort to help contribute to the understanding of the possible role of hydrogen in the complex stress corrosion cracking process. Based on previous studies, the two forms of embrittlement are shown to be similar at low hydrogen pressures (100 N/sq m) but dissimilar at higher hydrogen pressures. In an effort to quantify this comparison, tests were conducted in an aqueous chloride solution using the same material and test techniques as had previously been employed in a gaseous hydrogen environment. The results of these tests strongly support models based on hydrogen as the embrittling species in an aqueous chloride environment.

  7. Microbial communities in acid water environments of two mines, China

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Shengmu; Xie Xuehui [College of Environmental Science and Engineering, Donghua University, Shanghai (China); Liu Jianshe [College of Environmental Science and Engineering, Donghua University, Shanghai (China); School of Resources Processing and Bioengineering, Central South University, Changsha (China)], E-mail: xiaoshengmu@gmail.com

    2009-03-15

    To understand the compositions and structures of microbial communities in different acid-aqueous environments, a PCR-based cloning approach was used. A total of five samples were collected from two mines in China. Two samples, named as G1 and G2, were acid mine drainage (AMD) samples and from Yunfu sulfide mine in Guangdong province, China. The rest of the three samples named as D1, DY and D3, were from three sites undertaking bioleaching in Yinshan lead-zinc mine in Jiangxi province, China. Phylogenetic analysis revealed that bacteria in the five samples fell into six putative divisions, which were {alpha}-Proteobacteria, {beta}-Proteobacteria, {gamma}-Proteobacteria, Firmicutes, Actinobacteria and Nitrospira. Archaea was only detected in the three samples from Yinshan lead-zinc mine, which fell into two phylogenentic divisions, Thermoplsma and Ferroplasma. In addition, the results of principal component analysis (PCA) suggested that more similar the geochemical properties in samples were, more similar microbial community structures in samples were. - Microbial community compositions in acid-aqueous environments from Chinese mines were studied, and the relationship with geochemical properties was obtained.

  8. Microbial communities in acid water environments of two mines, China

    International Nuclear Information System (INIS)

    To understand the compositions and structures of microbial communities in different acid-aqueous environments, a PCR-based cloning approach was used. A total of five samples were collected from two mines in China. Two samples, named as G1 and G2, were acid mine drainage (AMD) samples and from Yunfu sulfide mine in Guangdong province, China. The rest of the three samples named as D1, DY and D3, were from three sites undertaking bioleaching in Yinshan lead-zinc mine in Jiangxi province, China. Phylogenetic analysis revealed that bacteria in the five samples fell into six putative divisions, which were α-Proteobacteria, β-Proteobacteria, γ-Proteobacteria, Firmicutes, Actinobacteria and Nitrospira. Archaea was only detected in the three samples from Yinshan lead-zinc mine, which fell into two phylogenentic divisions, Thermoplsma and Ferroplasma. In addition, the results of principal component analysis (PCA) suggested that more similar the geochemical properties in samples were, more similar microbial community structures in samples were. - Microbial community compositions in acid-aqueous environments from Chinese mines were studied, and the relationship with geochemical properties was obtained

  9. Measurement of Cadmium Ion in the Presence of Metal-Binding Biopolymers in Aqueous Sample

    OpenAIRE

    Jian Pu; Kensuke Fukushi

    2013-01-01

    In aqueous environment, water-soluble polymers are effectively used to separate free metal ions from metal-polymer complexes. The feasibilities of four different analytical techniques, cadmium ion-selective electrode, dialysis sack, chelate disk cartridge, and ultrafiltration, in distinguishing biopolymer-bound and nonbound cadmium in aqueous samples were investigated. And two different biopolymers were used, including bovine serum albumin (BSA) and biopolymer solution extracted from cultivat...

  10. Aqueous Alteration Mineralogy in CM Carbonaceous Chondrites

    Science.gov (United States)

    Chokai, J.; Zolensky, M.; Le, L.; Nakamura, K.; Mikouchi, T.; Monkawa, A.; Koizumi, E.; Miyamoto, M.

    2004-01-01

    Iron-nickel sulfides are found in most or all solar system environments, and are probably the only minerals found in all extraterrestrial materials on hand. Despite the ubiquity, they have not received the attention they deserve. The most common Fe-Ni sulfides in chondrites are troilite (FeS), pyrrhotite (Fe1- XS) and pentlandite (Fe,Ni)9S8. Troilite is believed to have resulted from sulfidation of metal (Fe-Ni) grains in an H2Scontaining environment. Pyrrhotite is produced when friable troilite grains, which are exfoliated from the metal nucleus, are submitted to continued sulfidation [1]. Some asteroids are known to have experienced aqueous alteration, forming products including new generations of sulfides (pyrrhotite and pentlandite). Pentlandite in particular is known to form during such alteration [1]. However, experimental work by Lauretta has indicated that pentlandite may also have been formed during the initial sulfidation process [2], due to the faster diffusion rate of nickel into the forming sulfide, as compared to iron. Finally, there is considerable evidence [1,3&4] for a family of phases intermediate between pyrrhotite and pentlandite, following the trend of the high temperature monosulfide solid solution [5], something not encountered in terrestrial rocks.

  11. An Electrochemical Investigation of the Redox Properties of Murexide in Aqueous and Non-Aqueous Media

    Directory of Open Access Journals (Sweden)

    Hossnia S. Mohran

    2009-01-01

    Full Text Available Knowledge of solvent effects on the redox properties of Murexide (Mu is important for understanding its role as an electron acceptor in analytical and inorganic chemistry. In the present study, an investigation of the electrochemical behavior of the compound by both Cyclic Voltammetry (CV and Electrochemical Impedance Spectroscopy (EIS in both aqueous and non-aqueous solutions was undertaken. It is suggested that, the reaction mechanism proceeds according to an Erev CE-rev-route. This reaction mechanism is confirmed by the CV behavior for barbituric acid, which is essentially represent a main part of murexide, under the same conditions. In DMSO, the one-electron reduction potential peak of murexide was found to shift positively by 223 mV to the value of the corresponding wave obtained in DMF under the same conditions. The shift is most readily explained by the presence of murexide aggregates in DMF. The one-electron oxidation potential position is relatively unaffected by aggregation. The data has also revealed that murexide decomposes in the level of radical anion at the N = C bond into two approximately equal units. In aqueous sodium perchlorate (NaClO4 solutions, it is suggested that the decomposion of murexide is relatively slow, leading to nearly a reversible 1e-transfer process (E-mechanism. In both KNO3 and KCl solutions, the one-electron transfer step of murexide was found to be an adsorption wave. The Electrochemical Impedance (EIS response of murexide is either low-frequency Warburg impedance or a capacitive semicircle behavior at high frequencies, depending on the medium.

  12. Hydrogen Absorption into Austenitic Stainless Steels Under High-Pressure Gaseous Hydrogen and Cathodic Charge in Aqueous Solution

    Science.gov (United States)

    Enomoto, Masato; Cheng, Lin; Mizuno, Hiroyuki; Watanabe, Yoshinori; Omura, Tomohiko; Sakai, Jun'ichi; Yokoyama, Ken'ichi; Suzuki, Hiroshi; Okuma, Ryuji

    2014-12-01

    Type 316L and Type 304 austenitic stainless steels, both deformed and non-deformed, were hydrogen charged cathodically in an aqueous solution as well as by exposure to high-pressure gaseous hydrogen in an attempt to identify suitable conditions of cathodic charge for simulating hydrogen absorption from gaseous hydrogen environments. Thermal desorption analysis (TDA) was conducted, and the amount of absorbed hydrogen and the spectrum shape were compared between the two charging methods. Simulations were performed by means of the McNabb-Foster model to analyze the spectrum shape and peak temperature, and understand the effects of deformation on the spectra. It was revealed that the spectrum shape and peak temperature were dependent directly upon the initial distribution of hydrogen within the specimen, which varied widely according to the hydrogen charge condition. Deformation also had a marked effect on the amount of absorbed hydrogen in Type 304 steel due to the strain-induced martensitic transformation.

  13. Modeling reactive geochemical transport of concentrated aqueous solutions

    Science.gov (United States)

    Zhang, Guoxiang; Zheng, Zuoping; Wan, Jiamin

    2005-02-01

    Aqueous solutions with ionic strength larger than 1 M are usually considered concentrated aqueous solutions. These solutions can be found in some natural systems and are also industrially produced and released into accessible natural environments, and as such, they pose a big environmental problem. Concentrated aqueous solutions have unique thermodynamic and physical properties. They are usually strongly acidic or strongly alkaline, with the ionic strength possibly reaching 30 M or higher. Chemical components in such solutions are incompletely dissociated. The thermodynamic activities of both ionic and molecular species in these solutions are determined by the ionic interactions. In geological media the problem is further complicated by the interactions between the solutions and sediments and rocks. The chemical composition of concentrated aqueous solutions when migrating through the geological media may be drastically altered by these strong fluid-rock interactions. To effectively model reactive transport of concentrated aqueous solutions, we must take into account the ionic interactions. For this purpose we substantially extended an existing reactive transport code, BIO-CORE2D©, by incorporating a Pitzer ion interaction model to calculate the ionic activity. In the present paper, the model and two test cases of the model are briefly introduced. We also simulate a laboratory column experiment in which the leakage of highly alkaline waste fluid stored at Hanford (a U.S. Department of Energy site, located in Washington State) was studied. Our simulation captures the measured pH evolution and indicates that all the reactions controlling the pH evolution, including cation exchanges and mineral dissolution/precipitation, are coupled.

  14. Decision Making and Revealed Preference

    DEFF Research Database (Denmark)

    de la Rosa, Leonidas Enrique

    If our decision-making processes are to some extent shaped by evolutionary pressures and our environment is different from that to which we adapted, some of our choices will not be in our best interest. But revealed preference is the only tool that we have so far to conduct a normative analysis. ....... Given advances in evolutionary psychology and neuroscience, I propose one way to model those evolutionary pressures that will hopefully prove useful in expanding normative economics.......If our decision-making processes are to some extent shaped by evolutionary pressures and our environment is different from that to which we adapted, some of our choices will not be in our best interest. But revealed preference is the only tool that we have so far to conduct a normative analysis...

  15. Photodegradation of Norfloxacin in aqueous solution containing algae

    Institute of Scientific and Technical Information of China (English)

    Junwei Zhang; Dafang Fu; Jilong Wu

    2012-01-01

    Photodegradation of Norfloxacin in aqueous solution containing algae under a medium pressure mercury lamp (15 W,λmax =365 nm) was investigated.Results indicated that the photodegradation of Norfloxacin could be induced by the algae in the heterogeneous algaewater systems.The photodegradation rate of Norfloxacin increased with increasing algae concentration,and was greatly influenced by the temperature and pH of solution.Meanwhile,the cooperation action of algae and Fe(Ⅲ),and the ultrasound were beneficial to photodegradation of Norfloxaciu.The degradation kinetics of Norfloxacin was found to follow the pseudo zero-order reaction in the suspension of algae.In addition,we discussed the photodegradation mechanism of Norfloxacin in the suspension of algae.This work will be helpful for understanding the photochemical degradation of antibiotics in aqueous environment in the presence of algae,for providing a new method to deal with antibiotics pollution.

  16. Interfacial forces in aqueous media

    CERN Document Server

    van Oss, Carel J

    2006-01-01

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

  17. Aqueous photocatalytic oxidation of sulfamethizole.

    Science.gov (United States)

    Klauson, D; Krichevskaya, M; Borissova, M; Preis, S

    2010-12-14

    Aqueous photocatalytic oxidation (PCO) of a non-biodegradable sulphonamide antibiotic sulfamethizole was studied. The impacts of photocatalyst dose, initial pH, and substrate concentration in the range from 1 to 100 mg L(-1) were examined with a number of organic and inorganic by-products determined, suggesting the initial break-up of the SMZ molecule at the sulphonamide bond. The experiments were carried out under artificial near-UV and visible light, and solar radiation using Degussa P25 and less efficient visible light-sensitive C-doped titanium dioxide as photocatalysts. PMID:21275251

  18. Biological activities of aqueous extract from Cinnamomum porrectum

    Science.gov (United States)

    Farah, H. Siti; Nazlina, I.; Yaacob, W. A.

    2013-11-01

    A study was carried out to evaluate biological activities of an extract obtained from Cinnamomum porrectum under reflux using water. Aqueous extract of Cinnamomum porrectum was tested for antibacterial activity against six Gram-positive and eight Gram-negative bacteria as well as MRSA. The results confirmed that the aqueous extract of Cinnamomum porrectum was bactericidal. Cytotoxic tests on Vero cell culture revealed that Cinnamomum porrectum was non-toxic which IC50 value higher than 0.02 mg/mL. Antiviral activity was tested based on the above IC50 values together with the measured EC50 values to obtain Therapeutic Index. The result showed that Cinnamomum porrectum has the ability to inhibit viral replication of HSV-1 in Vero cells.

  19. Nano particles@Calix arenas via aqueous solution

    Directory of Open Access Journals (Sweden)

    Sahar Dehghani

    2016-05-01

    Full Text Available The electronic structure and magnetic properties of Al2O3, GaN and Fe3O4@ Calix (8 COOH have been studied using ONIOM and DFT methods. The studies focus on how to improve the adsorption of some nano particles solution aqueous for achieving good magnetic and functionalized potential performances. The results revealed that the Fe3O4@ Calix (8 COOH and some of its derivations exhibited better thermodynamic stability. Furthermore, the particle size and magnetic property of the GaN@ Calix (8 COOH nano particles can be controlled by the aqueous. The electrical properties such as NMR Shielding, electron densities, energy densities, potential energy densities, ELF, LOL, ellipticity of electron density, eta index and ECP for nano particles@ Calix (8COOH have been calculated.

  20. Laser purification of ultradispersed diamond in aqueous solution

    International Nuclear Information System (INIS)

    The effect of pulsed radiation from a 2.92-μm, 130-ns Cr3+:Yb3+:Ho3+:YSGG holmium laser and a 510-nm, 20-ns copper vapour laser on an aqueous suspension of ultradispersed diamond is studied. X-ray photoelectron spectroscopy and electron energy loss spectroscopy revealed that exposure of the suspension to holmium laser radiation reduces the concentration of nondiamond carbon impurity in it. This is due to the dissolution of carbon impurity in supercritical aqueous solution, caused by radiation absorption. Dissolution of the nondiamond fraction may serve as an indicator of the solution being in the supercritical state as a result of laser irradiation of liquids. This process can be used for efficient purification of ultradispersed diamonds. (laser applications and other topics in quantum electronics)

  1. Development of a Rapid, Nondestructive Method to Measure Aqueous Carbonate in High Salinity Brines Using Raman Spectroscopy

    Science.gov (United States)

    McGraw, L.; Phillips-Lander, C. M.; Elwood Madden, A. S.; Parnell, S.; Elwood Madden, M.

    2015-12-01

    Traditional methods of quantitative analysis are often ill-suited to determining the bulk chemistry of high salinity brines due to their corrosive and clogging properties. Such methods are also often difficult to apply remotely in planetary environments. However, Raman spectroscopy can be used remotely without physical contact with the fluid and is not affected by many ionic brines. Developing methods to study aqueous carbonates is vital to future study of brines on Mars and other planetary bodies, as they can reveal important information about modern and ancient near-surface aqueous processes. Both sodium carbonate standards and unknown samples from carbonate mineral dissolution experiments in high salinity brines were analyzed using a 532 nm laser coupled to an inVia Renishaw spectrometer to collect carbonate spectra from near-saturated sodium chloride and sodium sulfate brines. A calibration curve was determined by collecting spectra from solutions of known carbonate concentrations mixed with a pH 13 buffer and a near-saturated NaCl or Na2SO4 brine matrix. The spectra were processed and curve fitted to determine the height ratio of the carbonate peak at 1066 cm-1 to the 1640 cm-1 water peak. The calibration curve determined using the standards was then applied to the experimental data after accounting for dilutions. Concentrations determined based on Raman spectra were compared against traditional acid titration measurements. We found that the two techniques vary by less than one order of magnitude. Further work is ongoing to verify the method and apply similar techniques to measure aqueous carbonate concentrations in other high salinity brines.Traditional methods of quantitative analysis are often ill-suited to determining the bulk chemistry of high salinity brines due to their corrosive and clogging properties. Such methods are also often difficult to apply remotely in planetary environments. However, Raman spectroscopy can be used remotely without physical

  2. Algicidal effects of aqueous leaf extracts of neem (Azadirachta indica on Scenedesmus quadricauda (Turp. de Brébission

    Directory of Open Access Journals (Sweden)

    Mathias Ahii Chia

    2016-03-01

    Full Text Available The application of synthetic algaecides for the control of algae produces by-products that are sometimes toxic to the environment. There is a need for natural and cheap alternatives to synthetic algaecides. In the present study, we investigated the potential of aqueous crude extract of Azadirachta indica to inhibit the growth of Scenedesmus quadricauda. Phytochemical screening of the extract revealed the presence of groups of bioactive compounds that are capable of inhibiting microalgal growth. Chlorophyll a concentration, dry weight production and cell density of microalga decreased with increasing crude extract concentration. After three days of exposure, the 1000 mg/L extract concentration resulted in complete growth inhibition and cell lysis. Furthermore, the ability of S. quadricauda to form multi-celled coenobial structures was compromised in a concentration dependent manner. In general, catalase and peroxidase activities of the microalga were upregulated with increasing extract concentration. These results imply that aqueous neem extract may provide a cheap and ecofriendly alternative for the control of microalgae in aquatic ecosystems.

  3. Novel magnetic Fe3O4-C nanoparticles as adsorbents for removal of organic dyes from aqueous solution

    International Nuclear Information System (INIS)

    Highlights: → In this work, novel magnetic Fe3O4-C nanoparticles have been synthesized and employed as high efficient adsorbent for removal cationic dyes from polluted water. → While up to now, little study is done on adsorption of dyes by the Fe3O4-C nanoparticles. → Hence, here we provide a simply and environment friendly method for removal of cationic dyes or other pollutants from water. - Abstract: The magnetic Fe3O4/C core-shell nanoparticles have been synthesized by a simple strategy and used as adsorbents for removal of organic dyes from aqueous solution. The resulting products are characterized by scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectra and Fourier transform infrared spectra (FTIR). Adsorption performances of the nanomaterial adsorbents are tested with removal of methylene blue (MB) and cresol red (CR) from aqueous solution. The effects of solution pH value, adsorption time and capacity of the nanocomposites have been fully investigated. The results reveal that the nanospheres can be easily manipulated by an external magnetic field with high separation efficiency. In addition, the process is clean and safe for purifying water pollution. The prepared Fe3O4/C complex nanomaterials could thus be used as promising adsorbents for the remove organic dyes, especially, cationic dye, from polluted water.

  4. Environment, Growth and Value

    OpenAIRE

    Jon Mulberg

    1987-01-01

    The paper presents an impossibility theory, that micro-economics cannot consider environmental factors, and suggests that an analysis of the treatment of environment within economic theory reveals shortcomings in many areas of economics.The essential element in the consideration of environment is the economic evaluation of environmental disruption. The development of new technology or of anti-pollution measures require that resources be correctly allocated. There are several reasons why this ...

  5. THE AQUEOUS AND NON-AQUEOUS ELECTROCHEMISTRY OF POLYACETYLENE : APPLICATION IN HIGH POWER DENSITY RECHARGEABLE BATTERIES

    OpenAIRE

    MacDiarmid, A.; Kaner, R.; Mammone, R.; Heeger, A.

    1983-01-01

    Polyacetylene can be doped either chemically or electrochemically in aqueous solution to the metallic regime. The characteristics of selected rechargeable batteries employing (CH)x, electrodes in non-aqueous electrolytes are described.

  6. Protons and Hydroxide Ions in Aqueous Systems.

    Science.gov (United States)

    Agmon, Noam; Bakker, Huib J; Campen, R Kramer; Henchman, Richard H; Pohl, Peter; Roke, Sylvie; Thämer, Martin; Hassanali, Ali

    2016-07-13

    Understanding the structure and dynamics of water's constituent ions, proton and hydroxide, has been a subject of numerous experimental and theoretical studies over the last century. Besides their obvious importance in acid-base chemistry, these ions play an important role in numerous applications ranging from enzyme catalysis to environmental chemistry. Despite a long history of research, many fundamental issues regarding their properties continue to be an active area of research. Here, we provide a review of the experimental and theoretical advances made in the last several decades in understanding the structure, dynamics, and transport of the proton and hydroxide ions in different aqueous environments, ranging from water clusters to the bulk liquid and its interfaces with hydrophobic surfaces. The propensity of these ions to accumulate at hydrophobic surfaces has been a subject of intense debate, and we highlight the open issues and challenges in this area. Biological applications reviewed include proton transport along the hydration layer of various membranes and through channel proteins, problems that are at the core of cellular bioenergetics. PMID:27314430

  7. Aqueous chloride stress corrosion cracking of titanium: A comparison with environmental hydrogen embrittlement

    Science.gov (United States)

    Nelson, H. G.

    1973-01-01

    The physical characteristics of stress corrosion cracking of titanium in an aqueous chloride environment are compared with those of embrittlement of titanium by a gaseous hydrogen environment in an effort to help contribute to the understanding of the possible role of hydrogen in the complex stress corrosion cracking process. Based on previous studies, the two forms of embrittlement are shown to be similar at low hydrogen pressures (100 N/sqm) but dissimilar at higher hydrogen pressures. In an effort to quantify this comparison, tests were conducted in an aqueous chloride solution using the same material and test techniques as had previously been employed in a gaseous hydrogen environment. The results of these tests strongly support models based on hydrogen as the embrittling species in an aqueous chloride environment. Further, it is shown that if hydrogen is the causal species, the effective hydrogen fugacity at the surface of titanium exposed to an aqueous chloride environment is equivalent to a molecular hydrogen pressure of approximately 10 N/sqm.

  8. Assessing the Nature, Distribution and Duration of Noachian Habitable Environments

    Science.gov (United States)

    Des Marais, D. J.

    2008-12-01

    Life as we know it indicates that habitable environments must simultaneously provide liquid water, conditions favorable for the assembly of complex organic molecules, nutrients for cellular constituents, and sources of energy that can sustain metabolism. These requirements must be met simultaneously and perhaps at least intermittently over geologically long periods. Recent missions indicate that liquid water probably persisted in the shallow subsurface during the Noachian. Surface waters occurred at least locally as indicated by geomorphologic features observed by orbiters and by analyses of Meridiani bedrock by MER Opportunity. Atmospheric precipitation and springs probably sustained surface waters at least intermittently during the Noachian. However whether lakes or a northern ocean persisted for long periods remains controversial. Theoretical models and surface geomorphology indicate that extensive groundwater probably persisted for geologically long times. Observations of spectral features of methane in the atmosphere indicate that groundwater might exist even today. Perhaps most challenging for achieving habitable conditions on Mars has been the requirement that liquid water and biologically useful sources of energy occur simultaneously. Because liquid water has been unstable at the martian surface for most of its history, both solar energy and liquid water have probably not been simultaneously available to sustain photosynthesis for most of Mars' history. Fortunately microorganisms also can obtain energy from iron and sulfur redox reactions in the absence of light. MER Spirit found evidence that iron oxidation might have occurred simultaneously with the aqueous alteration of rocks. MEX, MRO and MER documented extensive sulfates that might have derived at least in part from volcanic sulfur emissions oxidized under aqueous conditions. Perhaps most challenging for Mars exploration will be to visit sites where habitable environments once persisted and where their

  9. Work environment quality

    DEFF Research Database (Denmark)

    Knudsen, Herman; Busck, Ole Gunni; Lind, Jens

    2011-01-01

    The article explores how employee participation influences the quality of the work environment and workers’ well-being at 11 Danish workplaces from within six different industries. Both direct participation and representative forms of participation at the workplace level were studied. Statistical...... as well as qualitative comparative analyses reveal that work environment quality and high levels of participation go hand in hand. Within a typology of participation models the highest level of participation, including strong elements of collective participation, and also the best work environment...

  10. DEHYDRATION CONDENSATION IN AQUEOUS SOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Steinman, Gary; Kenyon, Dean H.; Calvin, Melvin

    1965-04-01

    EARLIER investigations have demonstrated that di-cyandiamide (DCDA), the dimer of cyanamide, can successfully promote the dehydration condensation of: (1) glucose and orthophosphate to give glucose-6-phosphate; (2) adenosine and orthophosphate to give adenosine-5'-monophosphate; (3) orthophosphate to give pyrophosphate; (4) alanine to give alanylalanine and alanylalanylalanine. These reactions were carried out in dilute aqueous solutions in the dark. (It was also demonstrated that the combination of ultra-violet light and dicyandiamide could promote the synthesis of dipeptides. This observation has since been confirmed by other investigators.) These experiments were designed to demonstrate one possible means by which such compounds could have been formed on the prebiotic Earth, thus providing materials needed for the origin of living systems. Dicyandiamide itself could have been, present on the primitive Earth as was demonstrated with the ultra-violet irradiation of cyanide solution.

  11. Aqueous supercapacitors on conductive cotton

    KAUST Repository

    Pasta, Mauro

    2010-06-01

    Wearable electronics offer the combined advantages of both electronics and fabrics. In this article, we report the fabrication of wearable supercapacitors using cotton fabric as an essential component. Carbon nanotubes are conformally coated onto the cotton fibers, leading to a highly electrically conductive interconnecting network. The porous carbon nanotube coating functions as both active material and current collector in the supercapacitor. Aqueous lithium sulfate is used as the electrolyte in the devices, because it presents no safety concerns for human use. The supercapacitor shows high specific capacitance (~70-80 F·g-1 at 0.1 A·g-1) and cycling stability (negligible decay after 35,000 cycles). The extremely simple design and fabrication process make it applicable for providing power in practical electronic devices. © 2010 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

  12. Soft matter at aqueous interfaces

    CERN Document Server

    Liu, Yi

    2016-01-01

    This book covers the science of interfaces between an aqueous phase and a solid, another liquid or a gaseous phase, starting from the basic physical chemistry all the way to state-of-the-art research developments. Both experimental and theoretical methods are treated thanks to the contributions of a distinguished list of authors who are all active researchers in their respective fields. The properties of these interfaces are crucial for a wide variety of processes, products and biological systems and functions, such as the formulation of personal care and food products, paints and coatings, microfluidic and lab-on-a-chip applications, cell membranes, and lung surfactants. Accordingly, research and expertise on the subject are spread over a broad range of academic disciplines and industrial laboratories. This book brings together knowledge from these different places with the aim of fostering education, collaborations and research progress.

  13. Interfacial Thermodynamics of Coexisting Aqueous Polymer Solutions

    NARCIS (Netherlands)

    Vis, M.

    2015-01-01

    Phase separation is commonly observed when two different polymers are present in aqueous solution, forming aqueous two-phase systems which typically consist for 90% of water. It is demonstrated that the presence of charge on one of the polymers results in an electric potential difference between the

  14. Corrosion penetration monitoring of advanced ceramics in hot aqueous fluids

    OpenAIRE

    Nickel, Klaus G; Björn Seipel

    2004-01-01

    Advanced ceramics are considered as components in energy related systems, because they are known to be strong, wear and corrosion resistant in many environments, even at temperatures well exceeding 1000 °C. However, the presence of additives or impurities in important ceramics, for example those based on Silicon Nitride (Si3N4) or Al2O3 makes them vulnerable to the corrosion by hot aqueous fluids. The temperatures in this type of corrosion range from several tens of centigrade to hydrothermal...

  15. Cyanide detection using a benzimidazole derivative in aqueous media

    Science.gov (United States)

    Li, Jian-Bin; Hu, Jing-Han; Chen, Juan-Juan; Qi, Jing

    2014-12-01

    A novel cyanide selective fluorescent chemosensor S1 based on benzimidazole group and naphthalene group as the fluorescence signal group had been designed and synthesized. The receptor could instantly detect CN- anion over other anions such as F-, Cl-, Br-, I-, AcO-, H2PO4-, HSO4-, SCN- and ClO4- by fluorescence spectroscopy changes in aqueous solution (H2O/DMSO, 8:2, v/v) with specific selectivity and high sensitivity. The fluorescence color of the solution containing sensor S1 induced a remarkable color change from pale blue to mazarine only after the addition of CN- in aqueous solution while other anions did not cause obvious color change. Moreover, further study demonstrates the detection limit on fluorescence response of the sensor to CN- is down to 8.8 × 10-8 M, which is far lower than the WHO guideline of 1.9 × 10-6 M. Test strips based on S1 were fabricated, which could act as a convenient and efficient CN- test kit to detect CN- in pure water for “in-the-field” measurement. Thus, the probe should be potential applications in an aqueous environment for the monitoring of cyanide.

  16. Protein denaturation at a single-molecule level: the effect of nonpolar environments and its implications on the unfolding mechanism by proteases

    Science.gov (United States)

    Cheng, Bo; Wu, Shaogui; Liu, Shixin; Rodriguez-Aliaga, Piere; Yu, Jin; Cui, Shuxun

    2015-02-01

    Most proteins are typically folded into predetermined three-dimensional structures in the aqueous cellular environment. However, proteins can be exposed to a nonpolar environment under certain conditions, such as inside the central cavity of chaperones and unfoldases during protein degradation. It remains unclear how folded proteins behave when moved from an aqueous solvent to a nonpolar one. Here, we employed single-molecule atomic force microscopy and molecular dynamics (MD) simulations to investigate the structural and mechanical variations of a polyprotein, I278, during the change from a polar to a nonpolar environment. We found that the polyprotein was unfolded into an unstructured polypeptide spontaneously when pulled into nonpolar solvents. This finding was corroborated by MD simulations where I27 was dragged from water into a nonpolar solvent, revealing details of the unfolding process at the water/nonpolar solvent interface. These results highlight the importance of water in maintaining folding stability, and provide insights into the response of folded proteins to local hydrophobic environments.Most proteins are typically folded into predetermined three-dimensional structures in the aqueous cellular environment. However, proteins can be exposed to a nonpolar environment under certain conditions, such as inside the central cavity of chaperones and unfoldases during protein degradation. It remains unclear how folded proteins behave when moved from an aqueous solvent to a nonpolar one. Here, we employed single-molecule atomic force microscopy and molecular dynamics (MD) simulations to investigate the structural and mechanical variations of a polyprotein, I278, during the change from a polar to a nonpolar environment. We found that the polyprotein was unfolded into an unstructured polypeptide spontaneously when pulled into nonpolar solvents. This finding was corroborated by MD simulations where I27 was dragged from water into a nonpolar solvent, revealing

  17. Metal separations using aqueous biphasic partitioning systems

    International Nuclear Information System (INIS)

    Aqueous biphasic extraction (ABE) processes offer the potential for low-cost, highly selective separations. This countercurrent extraction technique involves selective partitioning of either dissolved solutes or ultrafine particulates between two immiscible aqueous phases. The extraction systems that the authors have studied are generated by combining an aqueous salt solution with an aqueous polymer solution. They have examined a wide range of applications for ABE, including the treatment of solid and liquid nuclear wastes, decontamination of soils, and processing of mineral ores. They have also conducted fundamental studies of solution microstructure using small angle neutron scattering (SANS). In this report they review the physicochemical fundamentals of aqueous biphase formation and discuss the development and scaleup of ABE processes for environmental remediation

  18. Inter-laboratory exercise on steroid estrogens in aqueous samples

    Energy Technology Data Exchange (ETDEWEB)

    Heath, E., E-mail: ester.heath@ijs.s [Department of Environmental Sciences, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Kosjek, T. [Department of Environmental Sciences, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Andersen, H.R.; Holten Luetzhoft, H.-C. [Department of Environmental Engineering, Technical University of Denmark, Miljoevej 113, DK-2800 Kgs. Lyngby (Denmark); Adolfson Erici, M. [Stockholm University, ITM SE-106 91 Stockholm (Sweden); Coquery, M. [Cemagref, U.R. QELY, F-69336 Lyon (France); Duering, R.-A. [Giessen University, Institute of Soil Science and Soil Conservation, Giessen (Germany); Gans, O. [Umweltbundesamt GmbH, Unit Organic Analysis, Spittelauer Laende 5, 1090 Vienna (Austria); Guignard, C. [CRP Gabriel Lippmann, EVA, 41 rue du Brill, L-4422 Belvaux (Luxembourg); Karlsson, P. [Lantmannen Analycen AB, Research and Development, Sjoehagsgatan 3 Box 905, 5319, Lidkoeping (Sweden); Manciot, F. [CAE VEOLIA ENVIRONMENT, 1 Place de Turenne, 94417 Saint Maurice Cedex (France); Moldovan, Z. [National Institute of Research and Development for Isotopic and Molecular Technology, Mass Spectrometry Department, Str. Donath 65-103, 400293 Cluj-Napoca (Romania); Patureau, D. [INRA, UR50, Laboratoire de Biotechnologie de l' Environnemet (LBE), Avenue des etangs, F-11100 Narbonne (France); Cruceru, L. [Pollution Control Department, National Research Institute for Industrial Ecology (ECOIND), Sos.Panduri 90-92, sector 5, Bucharest (Romania); Sacher, F. [DVGW-Technologiezentrum Wasser, Karlsruher Strasse 84, 76139 Karlsruhe (Germany); Ledin, A. [Department of Environmental Engineering, Technical University of Denmark, Miljoevej 113, DK-2800 Kgs. Lyngby (Denmark)

    2010-03-15

    An inter-laboratory comparison exercise was organized among European laboratories, under the aegis of EU COST Action 636: 'Xenobiotics in Urban Water Cycle'. The objective was to evaluate the performance of testing laboratories determining 'Endocrine Disrupting Compounds' (EDC) in various aqueous matrices. As the main task three steroid estrogens: 17alpha-ethinylestradiol, 17beta-estradiol and estrone were determined in four spiked aqueous matrices: tap water, river water and wastewater treatment plant influent and effluent using GC-MS and LC-MS/MS. Results were compared and discussed according to the analytical techniques applied, the accuracy and reproducibility of the analytical methods and the nature of the sample matrices. Overall, the results obtained in this inter-laboratory exercise reveal a high level of competence among the participating laboratories for the detection of steroid estrogens in water samples indicating that GC-MS as well as LC-MS/MS can equally be employed for the analysis of natural and synthetic hormones. - Herein are presented the results of the first international inter-laboratory study on determination of selected steroid hormones in environmental aqueous samples.

  19. Inter-laboratory exercise on steroid estrogens in aqueous samples

    International Nuclear Information System (INIS)

    An inter-laboratory comparison exercise was organized among European laboratories, under the aegis of EU COST Action 636: 'Xenobiotics in Urban Water Cycle'. The objective was to evaluate the performance of testing laboratories determining 'Endocrine Disrupting Compounds' (EDC) in various aqueous matrices. As the main task three steroid estrogens: 17α-ethinylestradiol, 17β-estradiol and estrone were determined in four spiked aqueous matrices: tap water, river water and wastewater treatment plant influent and effluent using GC-MS and LC-MS/MS. Results were compared and discussed according to the analytical techniques applied, the accuracy and reproducibility of the analytical methods and the nature of the sample matrices. Overall, the results obtained in this inter-laboratory exercise reveal a high level of competence among the participating laboratories for the detection of steroid estrogens in water samples indicating that GC-MS as well as LC-MS/MS can equally be employed for the analysis of natural and synthetic hormones. - Herein are presented the results of the first international inter-laboratory study on determination of selected steroid hormones in environmental aqueous samples.

  20. Aqueous proton transfer across single-layer graphene

    Science.gov (United States)

    Achtyl, Jennifer L.; Unocic, Raymond R.; Xu, Lijun; Cai, Yu; Raju, Muralikrishna; Zhang, Weiwei; Sacci, Robert L.; Vlassiouk, Ivan V.; Fulvio, Pasquale F.; Ganesh, Panchapakesan; Wesolowski, David J.; Dai, Sheng; van Duin, Adri C. T.; Neurock, Matthew; Geiger, Franz M.

    2015-03-01

    Proton transfer across single-layer graphene proceeds with large computed energy barriers and is therefore thought to be unfavourable at room temperature unless nanoscale holes or dopants are introduced, or a potential bias is applied. Here we subject single-layer graphene supported on fused silica to cycles of high and low pH, and show that protons transfer reversibly from the aqueous phase through the graphene to the other side where they undergo acid-base chemistry with the silica hydroxyl groups. After ruling out diffusion through macroscopic pinholes, the protons are found to transfer through rare, naturally occurring atomic defects. Computer simulations reveal low energy barriers of 0.61-0.75 eV for aqueous proton transfer across hydroxyl-terminated atomic defects that participate in a Grotthuss-type relay, while pyrylium-like ether terminations shut down proton exchange. Unfavourable energy barriers to helium and hydrogen transfer indicate the process is selective for aqueous protons.

  1. RHEOLOGICAL PROPERTIES OF WHEAT GLIADINS IN AQUEOUS PROPANOL

    Institute of Scientific and Technical Information of China (English)

    Shao-min Sun; Yi-hu Song; Qiang Zheng

    2013-01-01

    Rheological properties of wheat gliadins in 50% (V/V) aqueous propanol were carried out as a function of gliadin concentration c and temperature.The solutions at 20 g L-1 to 200 g L-1 behave as Newtonian fluids with an flow activation energy of 23.5-27.3 kJ mol-1.Intrinsic viscosity [η] and Huggins constant kn are determined according to Huggins plot at c ≤120 gL-1.The results reveal that gliadins are not spherical shaped and the molecular size tends to increase with temperature due to improved solvation.

  2. Nano particles@Calix arenas via aqueous solution

    OpenAIRE

    Sahar Dehghani

    2016-01-01

    The electronic structure and magnetic properties of Al2O3, GaN and Fe3O4@ Calix (8) COOH have been studied using ONIOM and DFT methods. The studies focus on how to improve the adsorption of some nano particles solution aqueous for achieving good magnetic and functionalized potential performances. The results revealed that the Fe3O4@ Calix (8) COOH and some of its derivations exhibited better thermodynamic stability. Furthermore, the particle size and magnetic property of the GaN@ Calix (8) C...

  3. VUV irradiation studies of plasmid DNA in aqueous solution

    Science.gov (United States)

    Śmialek, M. A.; Hoffmann, S. V.; Folkard, M.; Prise, K. M.; Shuker, D. E. G.; Braithwaite, N. S.; Mason, N. J.

    2008-02-01

    Interactions of VUV light and DNA samples in aqueous solutions are reported. The damage induced by such radiation is quantified by monitoring both loss of supercoiled DNA and formation of single and double strand breaks using agarose gel electrophoresis. Irradiations were performed using synchrotron VUV photons of 130, 150, 170 and 190 nm. VUV irradiation experiments revealed enhanced damage upon irradiation with 170 nm photons as compared with irradiations with photons of 150 nm and 130 nm. Irradiations carried at 190 nm caused the least damage.

  4. VUV irradiation studies of plasmid DNA in aqueous solution

    International Nuclear Information System (INIS)

    Interactions of VUV light and DNA samples in aqueous solutions are reported. The damage induced by such radiation is quantified by monitoring both loss of supercoiled DNA and formation of single and double strand breaks using agarose gel electrophoresis. Irradiations were performed using synchrotron VUV photons of 130, 150, 170 and 190 nm. VUV irradiation experiments revealed enhanced damage upon irradiation with 170 nm photons as compared with irradiations with photons of 150 nm and 130 nm. Irradiations carried at 190 nm caused the least damage

  5. Aqueous Geochemistry at High Pressures and High Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Bass, Jay D. [Univ. of Illinois, Urbana-Champaign, IL (United States)

    2015-05-21

    This project is aimed at experimental characterization of the sound velocities, equations of state (EOS), and derived physical and chemical properties of aqueous solutions and carbon dioxide at extreme pressure and temperature conditions relevant to processes occurring in the interior of the Earth. Chemical transport, phase changes (including melting), fluid-solid reactions, and formation of magmatic liquids at convergent plat boundaries are a key motivation for this project. Research in this area has long been limited by the extreme experimental challenges and lack of data under the appropriate pressure-temperature (P-T) conditions. The vast majority of studies of aqueous geochemistry relevant to terrestrial problems of fluid-rock interactions have been conducted at 0.3 GPa or less, and the widely used Helgeson-Kirkham-Flowers equation of state for aqueous species is applicable only at ~ < 0.5 GPa. These limits are unfortunate because fluid flow and reactions plays a central role in many deeper environments. Recent efforts including our own, have resulted in new experimental techniques that now make it possible to investigate properties of homogeneous and heterogeneous equilibria involving aqueous species and minerals over a much broader range of pressure and temperature appropriate for deep crustal and upper mantle processes involving water-rich fluids. We carried out 1) Brillouin scattering measurements of the equations of state and molar volume of water and carbon dioxide to over 10 GPa and 870K using precise resistance heating of samples under pressure in the diamond anvil cell, and 2) the phase diagrams of the water and CO2, and 3) Exploring new experimental approaches, including CO2 laser heating of samples in a diamond cell, to measurements of sound velocities, EOS, and phase relations by Brillouin scattering to far greater pressures and temperatures.

  6. Radiochemical measurement of fast neutrons using a Ca(NO3)2 aqueous solution

    International Nuclear Information System (INIS)

    A radiochemical detector has been built to measure fast neutrons (E>2.5 MeV), using the reaction n + 40 Ca → 37 Ar + 4 He. The target consists in 470 litres of an aqueous solution of calcium nitrate. This detector has been used in the GALLEX environment at the Gran Sasso Underground Laboratory. (authors). 19 refs., 10 figs., 4 tabs

  7. Efficient microwave-assisted synthesis of 5-hydroxymethylfurfural from concentrated aqueous fructose

    DEFF Research Database (Denmark)

    Søndergaard Hansen, Thomas; Woodley, John; Riisager, Anders

    2009-01-01

    Studies on the HCl-catalysed microwave-assisted dehydration of highly concentrated aqueous fructose (27 wt %) to 5-hydroxymethylfurfural (HMF) revealed a significant increase in the fructose conversion rate over the conventional heated systems. Water, being the most benign solvent and therefore...

  8. Solid state and aqueous behavior of uranyl peroxide cage clusters

    Science.gov (United States)

    Pellegrini, Kristi Lynn

    Uranyl peroxide cage clusters include a large family of more than 50 published clusters of a variety of sizes, which can incorporate various ligands including pyrophosphate and oxalate. Previous studies have reported that uranyl clusters can be used as a method to separate uranium from a solid matrix, with potential applications in reprocessing of irradiated nuclear fuel. Because of the potential applications of these novel structures in an advanced nuclear fuel cycle and their likely presence in areas of contamination, it is important to understand their behavior in both solid state and aqueous systems, including complex environments where other ions are present. In this thesis, I examine the aqueous behavior of U24Pp 12, as well as aqueous cluster systems with added mono-, di-, and trivalent cations. The resulting solutions were analyzed using dynamic light scattering and ultra-small angle X-ray scattering to evaluate the species in solution. Precipitates of these systems were analyzed using powder X-ray diffraction, X-ray fluorescence spectrometry, and Raman spectroscopy. The results of these analyses demonstrate the importance of cation size, charge, and concentration of added cations on the aqueous behavior of uranium macroions. Specifically, aggregates of various sizes and shapes form rapidly upon addition of cations, and in some cases these aggregates appear to precipitate into an X-ray amorphous material that still contains U24Pp12 clusters. In addition, I probe aggregation of U24Pp12 and U60, another uranyl peroxide cage cluster, in mixed solvent water-alcohol systems. The aggregation of uranyl clusters in water-alcohol systems is a result of hydrogen bonding with polar organic molecules and the reduction of the dielectric constant of the system. Studies of aggregation of uranyl clusters also allow for comparison between the newer uranyl polyoxometalate family and century-old transition metal polyoxometalates. To complement the solution studies of uranyl

  9. Effect of Aqueous Extracts From Some Plants on Alloxan ­ Diabetic Rats

    Directory of Open Access Journals (Sweden)

    Gehan S. Moram

    2001-06-01

    Full Text Available The present study aims to clarify the effect of aqueous extracts from green tea, sage (Salvia officinalis and ginseng panax (panax quinquefolius L. on the insulin sensitivity in the alloxanized diabetic rats. The experiment included twenty four normal male albino rats and 24 diabetic ones. They were classified into eight groups each of 6 rats. Two groups served as control (one normal and one diabetic rats and the other groups were orally given the doses of aqueous extract for four weeks. The chemical analysis included level of blood glucose, plasma insulin, serum total cholesterol, serum triglycerides, HDL-cholesterol and LDL- cholesterol, in addition to the influence of these aqueous extracts on the liver glycogen and various enzymes of glucose metabolism (Glucose 6-phosphatase, ALT, AST and alkaline phosphatase. The results revealed significant decrease (p<0.05 in blood glucose, and highly significant increase in both liver glycogen content and serum insulin level in the diabetic group treated with aqueous extracts of tested plants in this study when compared with the diabetic untreated group. Serum lipids (triglycerides, total cholesterol, LDL- cholesterol and HDL-cholesterol and various enzymes of glucose metabolism (ALT, AST, ALP and glucose-6-phosphatase showed significant decrease in the diabetic group treated with aqueous extracts of tested plants when compared with the diabetic group. It is clear from the current data in this study that ginseng aqueous extract was the most efficient of the three tested plants.

  10. Aqueous synthesis of CdS and CdSe/CdS tetrapods for photocatalytic hydrogen generation

    OpenAIRE

    A. Vaneski; Schneider, J; Susha, A. S.; Rogach, A. L.

    2014-01-01

    Straightforward, easily upscalable synthesis of monodisperse CdS and CdSe/CdS nanocrystals at room temperature in water/ethylendiamine mixtures is demonstrated, resulting in the formation of high-quality tetrapod-shaped nanoparticles in aqueous environment. It offers advantages for the subsequent direct use of aqueous-based colloidal nanocrystals for photocatalytic hydrogen generation from water, as it avoids any additional phase transfer necessary for any commonly employed nanoparticles synt...

  11. Lyoluminescence of luminol in aqueous ammonia

    International Nuclear Information System (INIS)

    The emission spectrum of lyoluminescence of luminol in aqueous ammonia was recorded on a Fuess spectrograph. A continuous emission band from 370 to 600 nm, on resolution, showed three-banded emission with peaks at 413, 463 and 545 nm. The resolved fluorescence spectrum of luminol in ammonia showed two peaks, at 407 and 446 nm. The fluorescence lifetime of luminol in aqueous ammonia solution is 0.7 ns. The lyoluminescence emission bands are explained on the basis of the reactions of colour centres with luminol during the dissolution of irradiated NaCl crystals in an aqueous ammoniated solution of luminol. (author)

  12. Mercury separation from aqueous wastes

    International Nuclear Information System (INIS)

    This project is providing an assessment of new sorbents for removing mercury from wastes at US Department of Energy sites. Four aqueous wastes were chosen for lab-scale testing; a high-salt, acidic waste currently stored at Idaho National Engineering Laboratory (INEL); a high-salt, alkaline waste stored at the Savannah River Site (SRS); a dilute lithium hydroxide solution stored at the Oak Ridge Y-12 Plant; and a low-salt, neutral groundwater generated at the Y-12 Plant. Eight adsorbents have been identified for testing, covering a wide range of cost and capability. Screening tests have been completed, which identified the most promising adsorbents for each waste stream. Batch isotherm tests have been completed using the most promising adsorbents, and column tests are in progress. Because of the wide range of waste compositions tested, no one adsorbent is effective in all of these waste streams. Based on loading capacity and compatibility with the waste solutions. the most effective adsorbents identified to date are SuperLig 618 for the INEL tank waste stimulant; Mersorb followed by lonac SR-3 for the SRS tank waste stimulant; Durasil 70 and Ionac SR-3) for the LIOH solution; and lonac SR-3 followed by lonac SR-4 and Mersorb for the Y-12 groundwater

  13. Technetium removal from aqueous wastes

    International Nuclear Information System (INIS)

    The research discussed in this report has compared several ''state of the art'' techniques for the removal of traces of the radionuclide, technetium, from aqueous wastes. The techniques investigated were: electrochemical reduction to an insoluble oxide, electrochemical ion exchange, seeded ultrafiltration and chemical reduction followed by filtration. Each technique was examined using a simulant based upon the waste generated by the Enhanced Actinide Removal Plant (EARP) at Sellafield. The technique selected for further investigation was direct electrochemical reduction which offers an ideal route for the removal of technetium from the stream (DFs 10-100) and can be operated continuously with a low power consumption 25 kW for the waste generated by EARP. Cell designs for scale up have been suggested to treat the 1000m3 of waste produced every day. Future work is proposed to investigate the simultaneous removal of other key radionuclides, such as ruthenium, plutonium and cobalt as well as scale up of the resulting process and to investigate the effect of these other radionuclides on the efficiency of the electrochemical reduction technique for the removal of technetium. Total development and full scale plant costs are estimated to be of the order of 5 pounds - 10M, with a time scale of 5 -8 years to realisation. (author)

  14. Radiolysis of Aqueous Toluene Solutions

    International Nuclear Information System (INIS)

    Aqueous toluene solutions have been irradiated with Co γ-rays. In unbuffered solutions the various cresol isomers are formed in a total yield of 0.45, 0.87 and 0.94 molecules/100 eV absorbed energy in argon-, N2O- and air - saturated solutions, respectively. The yields are reduced in acid (pH 3) solutions (G 0.14, 0.14 and 0.52, respectively) but the reduction is compensated by the formation of 1,2-di-phenylethane in yields of 0.49 and 1.60 in argon- and N2O-saturated solutions, respectively. Benzyl radicals are formed through an acid catalysed water elimination reaction from the initially formed hydroxymethylcyclohexadienyl radical. Phenyltolylmethanes, dimethylbiphenyls and partly reduced dimers are also formed during the radiolysis. Hydrogen is formed in the same yield as the molecular yield, g(H2). Xylene isomers and benzene are formed in trace quantities. The most remarkable effects of the addition of Fe(III) ions to deaerated acid toluene solutions are the formation of benzyl alcohol and benzaldehyde and an increase in the yield of 1,2-diphenylethane

  15. The fluorescence quenching mechanism of coumarin 120 with CdS nanoparticles in aqueous suspension

    Energy Technology Data Exchange (ETDEWEB)

    Acar, Murat; Bozkurt, Ebru; Meral, Kadem; Arık, Mustafa; Onganer, Yavuz, E-mail: yonganer@atauni.edu.tr

    2015-01-15

    The interaction of coumarin 120 (C120) with CdS nanoparticles (CdS NPs) in aqueous suspension was examined by using UV–vis absorption, steady-state, time-resolved fluorescence, and electron paramagnetic resonance (EPR) spectroscopy techniques. The fluorescence intensity of C120 was quenched with increasing the amount of CdS NPs in the aqueous suspension. The spectroscopic data revealed that the C120 molecules adsorbed on CdS NPs via electrostatic interactions. The apparent association constant (K{sub app}) and the degree of association (α) for C120/CdS NPs were determined as 130.3 M{sup −1} and 0.51 for 4 nm CdS NPs and 624.3 M{sup −1} and 0.71 for 8 nm CdS NPs, respectively. The photoinduced EPR studies exhibited that no electron transfers between CdS and C120 taking place. The results revealed that the fluorescence quenching of C120 with different CdS NPs is due to the formation of a non-fluorescent complex. - Highlights: • Interaction of C120 with CdS NPs in aqueous solution was spectroscopically examined. • Nonfluorescent C120–CdS NPs complexes in aqueous solution were formed. • In the system, CdS NPs in aqueous solution acted as a fluorescence quencher.

  16. Aerosol plumes in a coastal environment revealed by lidar

    NARCIS (Netherlands)

    Kunz, G.J.; Leeuw, G. de

    2002-01-01

    A scanning backscatter lidar, operating at a wavelength of 1.06 μm, was used to measure the volume backscatter coefficient of coastal aerosol at the Mace Head Research Station on the west coast of Ireland during the PARFORCE experiments in September 1998 and June 1999. Lidar measurements under a fix

  17. Performative Environments

    DEFF Research Database (Denmark)

    Thomsen, Bo Stjerne

    2008-01-01

    The paper explores how performative architecture can act as a collective environment localizing urban flows and establishing public domains through the integration of pervasive computing and animation techniques. The NoRA project introduces the concept of ‘performative environments,' focusing on...

  18. Encapsulated Environment

    NARCIS (Netherlands)

    McLellan, T.M.; Daanen, H.A.M.; Cheung, S.S.

    2013-01-01

    In many occupational settings, clothing must be worn to protect individuals from hazards in their work environment. However, personal protective clothing (PPC) restricts heat exchange with the environment due to high thermal resistance and low water vapor permeability. As a consequence, individuals

  19. Enacting Environments

    DEFF Research Database (Denmark)

    Lippert, Ingmar

    2013-01-01

    are produced and co-configure climate change realities. Ingmar Lippert argues: within capitalism, environment does not exist in the singular but in the plural; and these environments are not existing out there to be read off some anterior Nature but they are brought into social, economic and political...

  20. Zinc chloride aqueous solution as a solvent for starch.

    Science.gov (United States)

    Lin, Meiying; Shang, Xiaoqin; Liu, Peng; Xie, Fengwei; Chen, Xiaodong; Sun, Yongyi; Wan, Junyan

    2016-01-20

    It is important to obtain starch-based homogeneous systems for starch modification. Regarding this, an important key point is to find cheap, low-cost and low-toxicity solvents to allow complete dissolution of starch and its easy regeneration. This study reveals that a ZnCl2 aqueous solution is a good non-derivatizing solvent for starch at 50 °C, and can completely dissolve starch granules. The possible formation of a "zinc-starch complex" might account for the dissolution; and the degradation of starch, which was caused by the H(+) inZnCl2 aqueous solution, could not contribute to full dissolution. From polarized light microscopic observation combined with the solution turbidity results, it was found that the lowest ZnCl2 concentration for full dissolution was 29.6 wt.% at 50 °C, with the dissolving time being 4h. Using Fourier-transform infrared (FTIR), solid state (13)C nuclear magnetic resonance (NMR), and X-ray diffraction (XRD), it was revealed that ZnCl2 solution had no chemical reaction with starch glucosides, but only weakened starch hydrogen bonding and converted the crystalline regions to amorphous regions. In addition, as shown by intrinsic viscosity and thermogravimetric analysis (TGA), ZnCl2 solution caused degradation of starch macromolecules, which was more serious with a higher concentration of ZnCl2 solution. PMID:26572355

  1. Photolysis of difloxacin and sarafloxacin in aqueous systems.

    Science.gov (United States)

    Prabhakaran, Deivasigamani; Sukul, Premasis; Lamshöft, Marc; Maheswari, Mohan Akhila; Zühlke, Sebastian; Spiteller, Michael

    2009-10-01

    The photodegradation of two fluoroquinolone veterinary antibiotics, difloxacin (DIF) and sarafloxacin (SARA) has been explored for the first time in aqueous systems. The study was performed to evaluate the influence of pH, inorganics, humic substances, and other additives. The drugs followed first-order degradation kinetics in matrix free aqueous medium with a rate constant 'k' value of 0.82 and 0.26 h(-1) for DIF and SARA, respectively. Studies performed at various pH revealed that the photolysis rates dropped sharply at pH >7 for DIF, while SARA dissipated faster with increasing pH. Humic substances acted as light barriers by attenuating the light intensity, to retard the drug degradation process. However, rapid drug dissipation was observed in the presence of additives like acetone, hydrogen peroxide, and phosphates, while inorganics such as fluoride, nitrate, and sulfate did not influence the drug photodegradation. Studies on the photolysis of DIF and SARA in river water revealed that both the drugs degraded rapidly under conditions that were relevant to natural systems, following direct photolysis mechanism. It was observed that SARA was the primary photoproduct of DIF and showed relatively a higher persistence than DIF. The findings were also substantiated by the quantum yield (Phi(c)) calculations. The analytical measurements were carried out with LC-MS/MS. PMID:19751946

  2. OSMOTIC COEFFICIENTS, SOLUBILITIES, AND DELIQUESCENCE RELATIONS IN MIXED AQUEOUS SALT SOLUTIONS AT ELEVATED TEMPERATURE

    International Nuclear Information System (INIS)

    While thermodynamic properties of pure aqueous electrolytes are relatively well known at ambient temperature, there are far fewer data for binary systems extending to elevated temperatures and high concentrations. There is no general theoretically sound basis for prediction of the temperature dependence of ionic activities, and consequently temperature extrapolations based on ambient temperature data and empirical equations are uncertain and require empirical verification. Thermodynamic properties of mixed brines in a wide range of concentrations would enhance the understanding and precise modeling of the effects of deliquescence of initially dry solids in humid air in geological environments and in modeling the composition of waters during heating, cooling, evaporation or condensation processes. These conditions are of interest in the analysis of waters on metal surfaces at the proposed radioactive waste repository at Yucca Mountain, Nevada. The results obtained in this project will be useful for modeling the long-term evolution of the chemical environment, and this in turn is useful for the analysis of the corrosion of waste packages. In particular, there are few reliable experimental data available on the relationship between relative humidity and composition that reveals the eutonic points of the mixtures and the mixture deliquescence RH. The deliquescence RH for multicomponent mixtures is lower than that of pure component or binary solutions, but is not easy to predict quantitatively since the solutions are highly nonideal. In this work we used the ORNL low-temperature and high-temperature isopiestic facilities, capable of precise measurements of vapor pressure between ambient temperature and 250 C for determination of not only osmotic coefficients, but also solubilities and deliquescence points of aqueous mixed solutions in a range of temperatures. In addition to standard solutions of CaCl2, LiCl, and NaCl used as references, precise direct

  3. 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...

  4. 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.

  5. Precipitation of neptunium dioxide from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, K E

    1999-12-01

    Tens of thousands of metric tons of highly radioactive, nuclear waste have been generated in the US. Currently, there is no treatment or disposal facility for these wastes. Of the radioactive elements in high-level nuclear waste, neptunium (Np) is of particular concern because it has a long half-life and may potentially be very mobile in groundwaters associated with a proposed underground disposal site at Yucca Mountain, Nevada. Aqueous Np concentrations observed in previous, short-term solubility experiments led to calculated potential doses exceeding proposed long-term regulatory limits. However, thermodynamic data for Np at 25 C showed that these observed aqueous Np concentrations were supersaturated with respect to crystalline NpO{sub 2}. It was hypothesized that NpO{sub 2} is the thermodynamically stable solid phase in aqueous solution, but it is slow to form in an aqueous solution of NpO{sub 2}{sup +} on the time scale of previous experiments. The precipitation of NpO{sub 2} would provide significantly lower aqueous Np concentrations leading to calculated doses below proposed regulatory limits. To test this hypothesis, solubility experiments were performed at elevated temperature to accelerate any slow precipitation kinetics. Ionic NpO{sub 2}{sup +} (aq) was introduced into very dilute aqueous solutions of NaCl with initial pH values ranging from 6 to 10. The reaction vessels were placed in an oven and allowed to react at 200 C until steady-state aqueous Np concentrations were observed. In all cases, aqueous Np concentrations decreased significantly from the initial value of 10{sup {minus}4} M. The solids that formed were analyzed by x-ray powder diffraction, x-ray absorption spectroscopy, and scanning electron microscopy. The solids were determined to be high-purity crystals of NpO{sub 2}. This is the first time that crystalline NpO{sub 2} has been observed to precipitate from NpO{sub 2}{sup +}(aq) in near-neutral aqueous solutions. The results obtained

  6. Mukaiyama Aldol Reactions in Aqueous Media

    OpenAIRE

    Kitanosono, Taku; Kobayashi, Shū

    2013-01-01

    Mukaiyama aldol reactions in aqueous media have been surveyed. While the original Mukaiyama aldol reactions entailed stoichiometric use of Lewis acids in organic solvents under strictly anhydrous conditions, Mukaiyama aldol reactions in aqueous media are not only suitable for green sustainable chemistry but are found to produce singular phenomena. These findings led to the discovery of a series of water-compatible Lewis acids such as lanthanide triflates in 1991. Our understanding on these be...

  7. Interfacial Thermodynamics of Coexisting Aqueous Polymer Solutions

    OpenAIRE

    Vis, M

    2015-01-01

    Phase separation is commonly observed when two different polymers are present in aqueous solution, forming aqueous two-phase systems which typically consist for 90% of water. It is demonstrated that the presence of charge on one of the polymers results in an electric potential difference between the two phases. Upon phase separation, the polyelectrolyte is confined in majority to one of the phases. Although small ions can equilibrate freely between the phases, the restriction of macroscopic c...

  8. Stabilized aqueous gels and uses thereof

    Energy Technology Data Exchange (ETDEWEB)

    Swanson, B.L.

    1978-08-29

    New improved aqueous gels, and methods of using same in contacting subterranean formations, are provided. The gels are prepared by gelling an aqueous brine having incorporated therein a water-soluble cellulose ether such as a carboxymethylcellulose (CMC), and are rendered more stable to decomposition by incorporating a sulfoalkylated tannin stabilizing agent, such as a sulfomethylated quebracho (SMQ), in the gel during the preparation thereof.

  9. 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.

  10. KINETIC AND EQUILIBRIUM STUDIES OF LEAD AND CADMIUM BIOSORPTION FROM AQUEOUS SOLUTIONS BY SARGASSUM SPP. BIOMASS

    OpenAIRE

    R. Nabizadeh, K. Naddafi, R. Saeedi, A. H. Mahvi, F. Vaezi, K. Yaghmaeian and S. Nazmara

    2005-01-01

    Contamination of the aqueous environment by heavy metals is a worldwide environmental problem. Biosorption of lead (II) and cadmium (II) from aqueous solutions by brown algae Sargassum spp.biomass was studied in a batch system. The heavy metals uptake was found to be rapid and reached to 88-96% of equilibrium capacity of biosorption in 15min. The pseudo second-order and saturation rate equations were found in the best fitness with the kinetic data (R2 > 0.99). The data obtained from experimen...

  11. A Novel Aqueous Polyurethane Containing Short Fluoroalkyl Chains:Synthesis and Application on Cotton Fabrics

    Institute of Scientific and Technical Information of China (English)

    ZHU Ming-jie; QING Feng-ling; MENG Wei-dong

    2006-01-01

    As very useful superficial modification agents, the common long perfluoroalkyl - containing agents are facing the ecological problems, such as persistence, bioaccumulation,and/or toxicity in the environment. In order to overcome the problems, we designed and synthesized a polyether diol containing short perfluoroalkyl side chains, which was condensed with diisocyanate to form fluorine-containing aqueous polyurethane. This aqueous polyurethane was applied on cotton fabrics by conventional pad-dry-cure process. The treated cotton fabrics showed good water repellent property with the contact angle reached 131°, and also possessed good washing durability.

  12. Cold aqueous planetary geochemistry with FREZCHEM from modeling to the search for life at the limits

    CERN Document Server

    Marion, Giles M

    2007-01-01

    This book explicitly investigates issues of astrobiological relevance in the context of cold aqueous planetary geochemistry. At the core of the technical chapters is the FREZCHEM model, initially developed over many years by one of the authors to quantify aqueous electrolyte properties and chemical thermodynamics at subzero temperatures. FREZCHEM, of general relevance to biogeochemists and geochemical modelers, cold planetary scientists, physicochemists and chemical engineers, is subsequently applied to the exploration of biogeochemical applications to solar systems bodies in general, and to speculations about the limits for life in cold environments in particular.

  13. Radiolysis of Aqueous Benzene Solutions

    International Nuclear Information System (INIS)

    Aerated and deaerated aqueous solutions of benzene have been irradiated with 60Co γ-rays. The products of radiolysis in deaerated, unbuffered or acid, solutions were phenol, biphenyl, hydrogen and in acid solutions also hydrogen peroxide with the following yields: G(phenol) = 0. 37 (0. 37), G(biphenyl) = 1.3 (1.7), G(H2) = 0.44 (0. 43) and G(H2O2) = 0 (0.60), the figures in brackets giving the results for acid solutions. The results are shown to agree with the conclusion that k(e-aq + H2O2) >> k(H + H2O2). Furthermore, the results indicate that a competition takes place between the reactions: 2 C6H6OH · -> dimer -> biphenyl. C6H7 · + C6H6OH · -> dimer -> biphenyl. The yields in aerated, unbuffered or acid, solutions were: G(phenol) = 2.1 (2.3), G(biphenyl) = 0 (0), and G(H2O2) = 2.2 (3.1), the figures in brackets being valid for acid solutions. The ratio k(H + C6H6)/k(H + O2) was 1.4x10-2. The results indicate that peroxides, or more probably hydroperoxides, take part in the reactions. After the addition of Fe2+ or Fe3+ to aerated acid solutions G(phenol) was increased to 6.6 and 3.4 respectively. Oxygen was consumed more rapidly in the presence of Fe. Reaction mechanisms are discussed

  14. AQUEOUS HOMOGENEOUS REACTORTECHNICAL PANEL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Diamond, D.J.; Bajorek, S.; Bakel, A.; Flanagan, G.; Mubayi, V.; Skarda, R.; Staudenmeier, J.; Taiwo, T.; Tonoike, K.; Tripp, C.; Wei, T.; Yarsky, P.

    2010-12-03

    Considerable interest has been expressed for developing a stable U.S. production capacity for medical isotopes and particularly for molybdenum- 99 (99Mo). This is motivated by recent re-ductions in production and supply worldwide. Consistent with U.S. nonproliferation objectives, any new production capability should not use highly enriched uranium fuel or targets. Conse-quently, Aqueous Homogeneous Reactors (AHRs) are under consideration for potential 99Mo production using low-enriched uranium. Although the Nuclear Regulatory Commission (NRC) has guidance to facilitate the licensing process for non-power reactors, that guidance is focused on reactors with fixed, solid fuel and hence, not applicable to an AHR. A panel was convened to study the technical issues associated with normal operation and potential transients and accidents of an AHR that might be designed for isotope production. The panel has produced the requisite AHR licensing guidance for three chapters that exist now for non-power reactor licensing: Reac-tor Description, Reactor Coolant Systems, and Accident Analysis. The guidance is in two parts for each chapter: 1) standard format and content a licensee would use and 2) the standard review plan the NRC staff would use. This guidance takes into account the unique features of an AHR such as the fuel being in solution; the fission product barriers being the vessel and attached systems; the production and release of radiolytic and fission product gases and their impact on operations and their control by a gas management system; and the movement of fuel into and out of the reactor vessel.

  15. Eco-friendly synthesis of Graphene using the aqueous extract of Amaranthus dubius

    Directory of Open Access Journals (Sweden)

    M. Jannathul Firdhouse

    2013-06-01

    Full Text Available An eco-friendly process of reduction of graphene oxide using aqueous extract of Amaranthus dubius under refluxing method is herein reported. The colour change of the graphene oxide (GO solution from brown to black was noted during the reduction of graphene oxide. UV-Visible spectrophotometer was used to monitor the formation of reduced graphene oxide (AKRGO. The crystallite size of nanographene was confirmed by XRD analysis and Scherrer’s formula. FTIR spectral analysis revealed the reduction of graphene oxide using aqueous extract of Amaranthus dubius. The morphology of the synthesized graphene was examined by SEM analysis.

  16. Observing environments

    DEFF Research Database (Denmark)

    Alrøe, Hugo Fjelsted; Noe, Egon

    2012-01-01

    Context: Society is faced with “wicked” problems of environmental sustainability, which are inherently multiperspectival, and there is a need for explicitly constructivist and perspectivist theories to address them. Problem: However, different constructivist theories construe the environment in...... different ways. The aim of this paper is to clarify the conceptions of environment in constructivist approaches, and thereby to assist the sciences of complex systems and complex environmental problems. Method: We describe the terms used for “the environment” in von Uexküll, Maturana & Varela, and Luhmann......, and analyse how their conceptions of environment are connected to differences of perspective and observation. Results: We show the need to distinguish between inside and outside perspectives on the environment, and identify two very different and complementary logics of observation, the logic of...

  17. MARKETING ENVIRONMENT

    OpenAIRE

    Munaga Ramakrishna Mohan Rao

    2014-01-01

    A firm marketing environment consists of the factors and forces outside marketing that affect marketing management’s ability to develop and maintain successful transactions with the target customers. To be successful, a marketer must develop its marketing mix factors and strategies according to the opportunities and threats existed in the environment. Marketers need to be good at building relationship customers. Others in the company and external partners surround all of these ...

  18. Aqueous compatible boron nitride nanosheets for high-performance hydrogels

    Science.gov (United States)

    Hu, Xiaozhen; Liu, Jiahui; He, Qiuju; Meng, Yuan; Cao, Liu; Sun, Ya-Ping; Chen, Jijie; Lu, Fushen

    2016-02-01

    Hexagonal boron nitride nanosheets (BNNSs) possess ultimate thermal and chemical stabilities and mechanical strengths. However, the unmodified BNNSs are hydrophobic and insoluble in water, which hinders their use in many technological areas requiring aqueous compatibility. In this work, h-BN was treated with molten citric acid to produce aqueous dispersible boron nitride sheets (ca-BNNSs). The resultant ca-BNNSs were used to fabricate ca-BNNS/polyacrylamide (i.e., BNNS2.5/PAAm) nanocomposite hydrogels, targeting high water retentivity and flexibility. The BNNS2.5/PAAm hydrogel (initially swollen in water) largely remained swollen (water content ~94 wt%) even after one-year storage under ambient conditions. Importantly, the swollen BNNS2.5/PAAm hydrogel (water content ~95 wt%) was highly flexible. Its elongation and compressive strength exceeded 10 000% and 8 MPa at 97% strain, respectively. Moreover, the aforementioned hydrogel recovered upon the removal of compression force, without obvious damage. The substantially improved water retentivity and flexibility revealed that BNNSs can serve as a promising new platform in the development of high-performance hydrogels.Hexagonal boron nitride nanosheets (BNNSs) possess ultimate thermal and chemical stabilities and mechanical strengths. However, the unmodified BNNSs are hydrophobic and insoluble in water, which hinders their use in many technological areas requiring aqueous compatibility. In this work, h-BN was treated with molten citric acid to produce aqueous dispersible boron nitride sheets (ca-BNNSs). The resultant ca-BNNSs were used to fabricate ca-BNNS/polyacrylamide (i.e., BNNS2.5/PAAm) nanocomposite hydrogels, targeting high water retentivity and flexibility. The BNNS2.5/PAAm hydrogel (initially swollen in water) largely remained swollen (water content ~94 wt%) even after one-year storage under ambient conditions. Importantly, the swollen BNNS2.5/PAAm hydrogel (water content ~95 wt%) was highly flexible. Its

  19. Analysis of Direct Samples of Early Solar System Aqueous Fluids

    Science.gov (United States)

    Zolensky, Michael E.; Bodnar, R J.; Fedele, L.; Yurimoto,H.; Itoh, S.; Fries, M.; Steele, A.

    2012-01-01

    inclusions of +/- 90 0/00(2 sigma) for delta D, and +/- 29 0/00 (2 sigma) for delta O-18. On the other hand, the reproducibility of Delta O-17 is plus or minus 8 /00 (2 sigma ) because the observed variations of isotope ratios follow a mass dependent fractionation law. Variations of delta D of the aqueous fluids range over sog,a 330(90; 2 sigma ) to +1200(90) 0/00 for Monahans and delta 300(96) 0/00 to +90(98)0/00 for Zag. Delta O-17 of aqueous fluids range over delta 16(22) 0/00 to +18(10) 0/00 for Monahans and +3(10) 0/00 to +27(11) 0/00 for Zag. These variations are larger than the reproducibility of standard analyses and suggest that isotope equilibria were under way in the fluids before trapping into halite. The mean values of delta D and Delta O-17 are +290 0/00 and +9 0/00, respectively. The mean values and the variations of these fluids are different from the representative values of ordinary chondrites, verifying our working hypothesis that the fluid inclusion-bearing halites were not indigenous to the H chondrite parent-asteroid but rather represent exogenous material delivered onto the asteroid from a separate cryovolcanically-active body. This initial isotopic work has demonstrated the feasibility of the measurements, but also revealed sample processing and analytical shortcomings that are now being addressed. Examination of solid mineral inclusions within Monahans and Zag halite grains by confocal Raman spectroscopy at the Carnegie Geophysical Laboratory has revealed them to be metal, magnetite, forsteritic olivine (Fo.98), macromolecular carbon (MMC), pyroxenes, feldspar with Raman spectral affinity to anorthoclase and, probably, fine-grained lepidocrocite (FeO(OH)). In addition, one inclusion features aliphatic material with Raman spectral features consistent with a mixture of short-chain aliphatic compounds. We have initiated analyses of the bulk composition of the fluids within the inclusions in Zag and Monahans halites at Virginia Tech by LA ICPMS using

  20. Synthesis of polyamidoxime-functionalized nanoparticles for uranium(VI) removal from neutral aqueous solutions

    International Nuclear Information System (INIS)

    It is important to separate uranium(VI) from water environment due to its high toxicity and radioactivity. A new kind of polystyrene nanoparticles with polyamidoxime is reported here for removal of uranium(VI) from aqueous solutions. The obtained PSt nanoparticles have a tunable sorption capacity. The sorption process follows pseudo-second-order kinetics, and the equilibrium can be reached within 6 h. Furthermore, the optimal pH value of sorption process is 6.5, and the adsorbents can be recycled well for uranium(VI) sorption from aqueous solution. This work indicates that the polyamidoxime-functionalized PSt nanoparticles may be used as a good adsorbent for the removal of uranium(VI) from neutral aqueous solution. (author)

  1. Uptake of Hg2+ from aqueous solutions by microporous titano- and zircono-silicates

    Directory of Open Access Journals (Sweden)

    Cláudia B. Lopes

    2008-01-01

    Full Text Available Being mercury one of the most toxic heavy metals present in the environment, it is of major concern to develop cleanup technologies to remove it from wastewater and recover mercury polluted ecosystems. In this context, we study the potential of some microporous titanosilicates and zirconosilicates for taking up Hg2+ from aqueous solutions. These materials have unique chemical and physical properties, and here we are able to confirm that they readily remove Hg2+ from aqueous solutions. Moreover, the presence of the competitive Mg2+ and Na+, which are some of the dominant cations in natural waters, does not reduce the uptake capacity of some of these materials. Thus, several inorganic materials reported here may have important environmental applications, efficiently removing Hg2+ from aqueous solutions.

  2. Aqueous Alteration on Mars. Chapter 23

    Science.gov (United States)

    Ming, Douglas W.; Morris, Richard V.; Clark, Benton C.

    2007-01-01

    Aqueous alteration is the change in composition of a rock, produced in response to interactions with H2O-bearing ices, liquids, and vapors by chemical weathering. A variety of mineralogical and geochemical indicators for aqueous alteration on Mars have been identified by a combination of surface and orbital robotic missions, telescopic observations, characterization of Martian meteorites, and laboratory and terrestrial analog studies. Mineralogical indicators for aqueous alteration include goethite (lander), jarosite (lander), kieserite (orbiter), gypsum (orbiter) and other Fe-, Mg-, and Ca-sulfates (landers), halides (meteorites, lander), phyllosilicates (orbiter, meteorites), hematite and nanophase iron oxides (telescopic, orbiter, lander), and Fe-, Mg-, and Ca-carbonates (meteorites). Geochemical indicators (landers only) for aqueous alteration include Mg-, Ca-, and Fe-sulfates, halides, and secondary aluminosilicates such as smectite. Based upon these indicators, several styles of aqueous alteration have been suggested on Mars. Acid-sulfate weathering (e.g., formation of jarosite, gypsum, hematite, and goethite), may occur during (1) the oxidative weathering of ultramafic igneous rocks containing sulfides, (2) sulfuric acid weathering of basaltic materials, and (3) acid fog (i.e., vapors rich in H2SO4) weathering of basaltic or basaltic-derived materials. Near-neutral or alkaline alteration occurs when solutions with pH near or above 7 move through basaltic materials and form phases such as phyllosilicates and carbonates. Very low water:rock ratios appear to have been prominent at most of the sites visited by landed missions because there is very little alteration (leaching) of the original basaltic composition (i.e., the alteration is isochemical or in a closed hydrologic system). Most of the aqueous alteration appears to have occurred early in the history of the planet (3 to 4.5 billion years ago); however, minor aqueous alteration may be occurring at the

  3. Application of Ultrasound and Ozone for the Removal of Aqueous Tannin

    Science.gov (United States)

    Son, Younggyu; Lim, Junghyun; Cui, Mingcan; Lim, Myunghee; Kweon, Bo-Youn; Khim, Jeehyeong

    2009-07-01

    In order to investigate the enhancement of combination of ultrasound process and ozonation for the removal of aqueous tannin, tannin concentration, chemical oxygen demand (COD), and total organic carbon (TOC) were analyzed in ultrasound process, ozonation, and ultrasound/ozone process. Even though ultrasound process was not effective for the removal of aqueous in terms of tannin concentration, COD, and TOC, ultrasound process could enhance the removal efficiency significantly when it was combined with ozonation. It was also revealed that COD removal resulted in partly mineralization due to insufficient oxidation power, which was induced by ultrasound and ozone. However average oxidation state of all organics in the solution was increased cogently and as a result, biodegradability could be increased meaningfully. Therefore ultrasound/ozone process could be effective pre-treatment process to biological process for the removal of aqueous tannin.

  4. Layered Double Hydroxide Nanoclusters: Aqueous, Concentrated, Stable, and Catalytically Active Colloids toward Green Chemistry.

    Science.gov (United States)

    Tokudome, Yasuaki; Morimoto, Tsuyoshi; Tarutani, Naoki; Vaz, Pedro D; Nunes, Carla D; Prevot, Vanessa; Stenning, Gavin B G; Takahashi, Masahide

    2016-05-24

    Increasing attention has been dedicated to the development of nanomaterials rendering green and sustainable processes, which occur in benign aqueous reaction media. Herein, we demonstrate the synthesis of another family of green nanomaterials, layered double hydroxide (LDH) nanoclusters, which are concentrated (98.7 g/L in aqueous solvent), stably dispersed (transparent sol for >2 weeks), and catalytically active colloids of nano LDHs (isotropic shape with the size of 7.8 nm as determined by small-angle X-ray scattering). LDH nanoclusters are available as colloidal building blocks to give access to meso- and macroporous LDH materials. Proof-of-concept applications revealed that the LDH nanocluster works as a solid basic catalyst and is separable from solvents of catalytic reactions, confirming the nature of nanocatalysts. The present work closely investigates the unique physical and chemical features of this colloid, the formation mechanism, and the ability to act as basic nanocatalysts in benign aqueous reaction systems. PMID:27124717

  5. Synthetic environments

    Science.gov (United States)

    Lukes, George E.; Cain, Joel M.

    1996-02-01

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

  6. Aqueous-based thick photoresist removal for bumping applications

    Science.gov (United States)

    Moore, John C.; Brewer, Alex J.; Law, Alman; Pettit, Jared M.

    2015-03-01

    Cleaning processes account for over 25% of processing in microelectronic manufacturing [1], suggesting electronics to be one of the most chemical intensive markets in commerce. Industry roadmaps exist to reduce chemical exposure, usage, and waste [2]. Companies are encouraged to create a safer working environment, or green factory, and ultimately become certified similar to LEED in the building industry [3]. A significant step in this direction is the integration of aqueous-based photoresist (PR) strippers which eliminate regulatory risks and cut costs by over 50%. One of the largest organic solvent usages is based upon thick PR removal during bumping processes [4-6]. Using market projections and the benefits of recycling, it is estimated that over 1,000 metric tons (mt) of residuals originating from bumping processes are incinerated or sent to a landfill. Aqueous-based stripping would eliminate this disposal while also reducing the daily risks to workers and added permitting costs. Positive-tone PR dissolves in aqueous strippers while negative-tone systems are lifted-off from the substrate, bumps, pillars, and redistribution layers (RDL). While the wafers are further processed and rinsed, the lifted-off PR is pumped from the tank, collected onto a filter, and periodically back-flushed to the trash. The PR solids become a non-hazardous plastic waste while the liquids are mixed with the developer stream, neutralized, filtered, and in most cases, disposed to the sewer. Regardless of PR thickness, removal processes may be tuned to perform in <15min, performing at rates nearly 10X faster than solvents with higher bath lives. A balanced formula is safe for metals, dielectrics, and may be customized to any fab.

  7. In vitro Antioxidant and Antibacterial Activity of Aqueous and Methanolic Extract of Mollugo nudicaulis Lam. Leaves

    Institute of Scientific and Technical Information of China (English)

    A Rameshkumar; TSivasudha

    2012-01-01

    Objective: To investigate invitro antioxidant activity, antibacterial activity and phytochemical screening of the aqueous and methanolic extract of Mollugo nudicaulis leaves (MN). Methods:The total phenolic and flavonoids content was quantified by Folin-Ciocalteu and Aluminum chloride method respectively. Invitro antioxidant activity was carried out by DPPH, ABTS and reducing power assays and antimicrobial activity was carried out by disc diffusion method.Results:The phytochemical tests of Mollugo nudicaulis revealed the presence of alkaloid steroids, flavonoids and reducing sugar in the both aqueous and methanolic extracts. Terpenoids were absent in both aqueous and methanolic extract of Mollugo nudicaulis. The total phenolics content of the methanolic and aqueous extract of leaves was 47.01 ± 0.8 and 46.4 ± 0.05 mg/100 g. The total flavonoid content was 41.3 ± 0.04 and 36.2 ± 0.01 mg/100 g respectively. The methanolic and aqueous extract of leaves showed IC50 values of DPPH radical scavenging as 48 and 190 μg/ml respectively. The IC50 values of ABTS radical scavenging for methanolic of aqueous extracts was 83 and 198.3 μg/ml of plant extract respectively. The total phenolics and flavonoids content and invitro antioxidant activity of methanolic extract was higher compared with aqueous extract. The methanolic extract of Mollugo nudicaulis used to determine antibacterial activity against bacterial species namely Pseudomonas aeruginosa, Proteus sp, Streptococcus sp, Entrobacter sp. Conclusion: This investigation suggests that the methanolic extracts of Mollugo nudicaulis possess potential antioxidant and antibacterial compounds.

  8. Alleloppathic effects and insecticidal activity of the aqueous extract of Satureja montana L.

    Directory of Open Access Journals (Sweden)

    Šućur Jovana

    2015-01-01

    Full Text Available Extensive use of synthetic insecticides, herbicides and other pesticides has negative effects on the environment and on human and animal health. Therefore scientists are turning towards natural pesticides such as active components of plant extracts. Effect of two concentrations (0.1% and 0.2% of Satureja montana L. aqueous extract on lipid peroxidation process, as well as the activity of the antioxidant enzymes (SOD, GPX, PPX and CAT in leaves and roots of pepper and black nightshade seedlings were examined 24, 72 and 120h after the treatment. Our results showed that higher concentration of S. montana aqueous extract induced lipid peroxidation in black nightshade roots. Furthermore, significant increases of pyrogallol and guaiacol peroxidase were detected in black nightshade leaves treated with 0.2% S. montana aqueous extract. The second aim was to evaluate effectiveness of aqueous extract as contact toxicant against whitefly. It was observed that aqueous extract with concentration of 0.2% showed toxic effect with 68.33% mortality after 96h.

  9. Humid-air and aqueous corrosion models for corrosion-allowance barrier material

    International Nuclear Information System (INIS)

    Humid-air and aqueous general and pitting corrosion models (including their uncertainties) for the carbon steel outer containment barrier were developed using the corrosion data from literature for a suite of cast irons and carbon steels which have similar corrosion behaviors to the outer barrier material. The corrosion data include the potential effects of various chemical species present in the testing environments. The atmospheric corrosion data also embed any effects of cyclic wetting and drying and salts that may form on the corroding specimen surface. The humid-air and aqueous general corrosion models are consistent in that the predicted humid-air general corrosion rates at relative humidities between 85 and 100% RH are close to the predicted aqueous general corrosion rates. Using the expected values of the model parameters, the model predicts that aqueous pitting corrosion is the most likely failure mode for the carbon steel outer barrier, and an earliest failure (or initial pit penetration) of the 100-mm thick barrier may occur as early as about 500 years if it is exposed continuously to an aqueous condition at between 60 and 70 degrees C

  10. DNA dynamics in aqueous solution: opening the double helix

    Science.gov (United States)

    Pohorille, A.; Ross, W. S.; Tinoco, I. Jr; MacElroy, R. D. (Principal Investigator)

    1990-01-01

    The opening of a DNA base pair is a simple reaction that is a prerequisite for replication, transcription, and other vital biological functions. Understanding the molecular mechanisms of biological reactions is crucial for predicting and, ultimately, controlling them. Realistic computer simulations of the reactions can provide the needed understanding. To model even the simplest reaction in aqueous solution requires hundreds of hours of supercomputing time. We have used molecular dynamics techniques to simulate fraying of the ends of a six base pair double strand of DNA, [TCGCGA]2, where the four bases of DNA are denoted by T (thymine), C (cytosine), G (guanine), and A (adenine), and to estimate the free energy barrier to this process. The calculations, in which the DNA was surrounded by 2,594 water molecules, required 50 hours of CRAY-2 CPU time for every simulated 100 picoseconds. A free energy barrier to fraying, which is mainly characterized by the movement of adenine away from thymine into aqueous environment, was estimated to be 4 kcal/mol. Another fraying pathway, which leads to stacking between terminal adenine and thymine, was also observed. These detailed pictures of the motions and energetics of DNA base pair opening in water are a first step toward understanding how DNA will interact with any molecule.

  11. Plan competitions reveal entrepreneurial talent

    Energy Technology Data Exchange (ETDEWEB)

    Madison, Alison L.

    2011-05-15

    Monthly economic diversity column for Tri-City Herald business section. Excerpt below: There’s something to be said for gaining valuable real-world experience in a structured, nurturing environment. Take for instance learning to scuba dive in the comfort of my resort pool rather than immediately hanging out with sharks while I figure out little things like oxygen tanks and avoiding underwater panic attacks. Likewise, graduate students are getting some excellent, supportive real-world training through university business plan competitions. These competitions are places where smart minds, new technologies, months of preparation and coaching, and some healthy pre-presentation jitters collide to reveal not only solid new business ideas, but also some promising entrepreneurial talent. In fact, professionals from around our region descend upon college campuses every spring to judge these events, which help to bridge the gap between academics and the real technology and business-driven economy.

  12. Diffusion coefficients of paracetamol in aqueous solutions

    International Nuclear Information System (INIS)

    Highlights: ► Mutual diffusion coefficients of paracetamol in aqueous dilute solutions. ► Influence of the thermodynamic factors on the variation of their mutual diffusion coefficients. ► Estimation of the mutual limiting diffusion coefficients of the molecular, Dm0, and ionized forms, D±0, of this drug. - Abstract: Binary mutual diffusion coefficients measured by the Taylor dispersion method, for aqueous solutions of paracetamol (PA) at concentrations from (0.001 to 0.050) mol·dm−3 at T = 298.15 K, are reported. From the Nernst–Hartley equation and our experimental results, the limiting diffusion coefficient of this drug and its thermodynamic factors are estimated, thereby contributing in this way to a better understanding of the structure of such systems and of their thermodynamic behaviour in aqueous solution at different concentrations.

  13. Preparation and Properties of an Aqueous Ferrofluid

    Science.gov (United States)

    Enzel, Patricia; Adelman, Nicholas B.; Beckman, Katie J.; Campbell, Dean J.; Ellis, Arthur B.; Lisensky, George C.

    1999-07-01

    Ferrofluids are colloidal suspensions of surfactant-coated magnetic particles in a liquid medium. This paper describes a simple synthesis of an aqueous-based ferrofluid that may be used in an introductory science or engineering laboratory. Magnetite (Fe3O4) particles are precipitated by combining FeCl3 and FeCl2 in a 2:1 stoichiometric ratio in aqueous ammonia solution. The resulting particles, ~10-20 nm in diameter based on powder X-ray diffraction, are then treated with aqueous tetramethylammonium hydroxide, which acts as a surfactant. When the resulting ferrofluid is placed near a magnet, it forms conical spikes. This paper also describes a method for repelling both oil- and water-based ferrofluid from solid surfaces that would otherwise be stained by the fluid. Finally, a demonstration of the interaction between ferrofluid and magnetic fields, in which ferrofluid is induced to leap upward by a stack of magnets, is described.

  14. Architecture & Environment

    Science.gov (United States)

    Erickson, Mary; Delahunt, Michael

    2010-01-01

    Most art teachers would agree that architecture is an important form of visual art, but they do not always include it in their curriculums. In this article, the authors share core ideas from "Architecture and Environment," a teaching resource that they developed out of a long-term interest in teaching architecture and their fascination with the…

  15. Business environment

    Czech Academy of Sciences Publication Activity Database

    Dušek, Libor; Fungáčová, Zuzana; Hakobyan, Anush; Hanousek, Jan; Ortmann, Andreas; Semerák, V.; Sklenář, P.; Svítková, Katarína; Vychodil, Ondřej; Wertlen, B.; Zemčík, Petr

    Prague : Charles University in Prague, 2005, s. 33-45. ISBN 80-7343-058-4 Institutional research plan: CEZ:AV0Z70850503 Keywords : Czech Republic * business environment Subject RIV: AH - Economics http://www.cerge-ei.cz/pdf/books/CR2005.pdf

  16. Anticonvulsant and antioxidant activity of aqueous leaves extract of Desmodium triflorum in mice against pentylenetetrazole and maximal electroshock induced convulsion

    Directory of Open Access Journals (Sweden)

    Vaibhav Bhosle

    2013-08-01

    Full Text Available The present investigation was aimed to study an anticonvulsant activity of aqueous extract of Desmodium triflorum (L. DC., Fabaceae, in mice. Animal models of epilepsy namely the pentylenetetrazole, and maximal electroshock induced convulsion were used to evaluate the anticonvulsant effects of the extracts. The biochemical estimation was done by measuring the lipid peroxidation and reduced glutathione. In the pentylenetetrazole induced convulsion, aqueous extract of D. triflorum 800 mg/kg significant delayed the onset of convulsion, reduced the duration of convulsion (p<0.05 and reduced mortality. The aqueous extract of D. triflorum 800 mg/kg dose reduced hind limb tonic extension phase of maximal electroshock induced convulsion induced convulsion in mice (p<0.05. The pretreated aqueous extract of D. triflorum showed significant inhibition of lipid peroxidation and increases the reduced glutathione level in mice brain tissue (p<0.001. The results revealed that D. triflorum possesses a significant dose dependent anticonvulsant activity.

  17. Radiation chemistry and the environment

    International Nuclear Information System (INIS)

    The rather strong and many-sided pollution of the environment (atmosphere, water resources, soil) as a consequence of human activities is summarized. The solution of the arised problems by application of radiation chemistry methods and the utilization of modern environmentally ''clean'' and economical technologies, founded on electron beam processing, are mentioned. Some basic environmental problems and their solution are briefly discussed: i) Removal of CO2 from flue gases and its radiation induced utilization. ii) Principals for degradation of aqueous pollutants by electron beam processing in the presence of ozone (synergistic effect). The radiation chemistry as a modern and manifold discipline with very broad applications can also essentially contribute in the conservation of the environment

  18. Preparation of metallic nanoparticles by irradiation in starch aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Nemţanu, Monica R., E-mail: monica.nemtanu@inflpr.ro; Braşoveanu, Mirela, E-mail: monica.nemtanu@inflpr.ro; Iacob, Nicuşor, E-mail: monica.nemtanu@inflpr.ro [National Institute for Lasers, Plasma and Radiation Physics, Electron Accelerators Laboratory, 409 Atomiştilor St., PO Box MG-36, 077125, Bucharest-Măgurele (Romania)

    2014-11-24

    Colloidal silver nanoparticles (AgNPs) were synthesized in a single step by electron beam irradiation reduction of silver ions in aqueous solution containing starch. The nanoparticles were characterized by spectrophotocolorimetry and compared with those obtained by chemical (thermal) reduction method. The results showed that the smaller sizes of AgNPs were prepared with higher yields as the irradiation dose increased. The broadening of particle size distribution occurred by increasing of irradiation dose and dose rate. Chromatic parameters such as b* (yellow-blue coordinate), C* (chroma) and ΔE{sub ab} (total color difference) could characterize the nanoparticles with respect of their concentration. Hue angle h{sup o} was correlated to the particle size distribution. Experimental data of the irradiated samples were also subjected to factor analysis using principal component extraction and varimax rotation in order to reveal the relation between dependent variables and independent variables and to reduce their number. The radiation-based method provided silver nanoparticles with higher concentration and narrower size distribution than those produced by chemical reduction method. Therefore, the electron beam irradiation is effective for preparation of silver nanoparticles using starch aqueous solution as dispersion medium.

  19. An electrochemical treatment for aqueous radioactive solutions using pottery

    International Nuclear Information System (INIS)

    A bench scale electrolytic cell made from plexiglas was used for electrochemical separation of 137Cs and 60Co from simullated aqueous radioactive solutions. In this cell, a stainless steel plate represented the anode. The electrochemical treatment technique used depends on forcing the radioactive cations of the solution (137Cs+ and 60Co++) towards the opposite electrode under the influence of applied electric current, where they highly sorbed in the pottery body. The highest removal for137Cs+ and 60Co was in the alkalina medium, especially at pH>9. The investigated factors affected the electrochemicla processes are, applied voltage, treatment duration, hydrogen ion concentration of the radioactive solution, and the consumed electrical energy . It was found that at pH 11, applied voltage 30V and current 100 mA, the highest removal of 137Cs is 99.8% after 2.5 hours, and 99.3% and 99.3% for 60Co after 1.25 hour.The total consumed energy for 137Cs and 60Co were 33.75 and 16.88 W.h.dm-3, respectively. Comparing with other treatment methods, the electrochemical method revealed three advantages: shorter treatment time, low-cost materials, and low consumed energy. The results obtained showed that the dual application of electric current and sorption on the surface of pottery are feasible for the treatment of aqueous radioactive solutions

  20. Issues in Freeze Drying of Aqueous Solutions

    Institute of Scientific and Technical Information of China (English)

    王维; 陈墨; 陈国华

    2012-01-01

    Freeze drying or lyophilization of aqueous solutions is widely used in pharmaceutical industry. The in-creased importance Of the process is gaining a worldwide interest of research. A growing body of literature has demonstrated that the scientific approach can result in improved product quality with minimum trial and error em-piricism. Formulation and process development need a systematical understanding of the physical chemistry of freezing and freeze drying, material science and mechanisms of heat and mass transfer. This paper presents an overview on freeze ding of aqueous solutions based on publications in the past few decades. The important issuesof the process are analyzed.

  1. Ceres Revealed in a Grain of Salt

    Science.gov (United States)

    Zolensky, M. E.; Bodnar, R. J.; Chan, Q. H.-S.; Hagiya, K.; Komatsu, M.; Steele, A.; Fries, M.; Kebukawa, Y.; Mikouchi, T.; Ohsumi, K.

    2016-01-01

    Introduction: Zag and Monahans (1998) are H chondrite regolith breccias containing 4.5 giga-year-old halite crystals which contain abundant inclusions of aqueous fluids, solids and organics. These all originated on a cryo-volcanically-active C class asteroid, probably 1 Ceres; the halite was transported to the regolith of the H chondrite parent asteroid, potentially 6 Hebe. Detailed analysis of these solids will thus potentially reveal the mineralogy of Ceres. Mineralogy of solids in the Monahans Halite Solid grains are present in the halites, which were entrained within the mother brines during eruption, including material from the interior and surface of the erupting body. The solids include abundant, widely variable organics that could not have been significantly heated (which would have resulted in the loss of fluids from the halite). Our analyses by Raman microprobe, SEM/EDX, synchrotron X-ray diffraction, UPLC-FD/QToF-MS, C-XANES and TEM reveal that these trapped grains include macromolecular carbon (MMC) similar in structure to CV3 chondrite matrix carbon, aliphatic carbon compounds, olivine (Fo99-59), high- and low-Ca pyroxene, feldspars, phyllosilicates, magnetite, sulfides, metal, lepidocrocite, carbonates, diamond, apatite and zeolites. Conclusions: The halite in Monahans and Zag derive from a water and carbon-rich object that was cryo-volcanically active in the early solar system, probably Ceres. The Dawn spacecraft found that Ceres includes C chondrite materials. Our samples include both protolith and aqueously-altered samples of the body, permitting understanding of alteration conditions. Whatever the halite parent body, it was rich in a wide variety of organics and warm, liquid water at the solar system's dawn.

  2. Modeling photoionization of aqueous DNA and its components.

    Science.gov (United States)

    Pluhařová, Eva; Slavíček, Petr; Jungwirth, Pavel

    2015-05-19

    Radiation damage to DNA is usually considered in terms of UVA and UVB radiation. These ultraviolet rays, which are part of the solar spectrum, can indeed cause chemical lesions in DNA, triggered by photoexcitation particularly in the UVB range. Damage can, however, be also caused by higher energy radiation, which can ionize directly the DNA or its immediate surroundings, leading to indirect damage. Thanks to absorption in the atmosphere, the intensity of such ionizing radiation is negligible in the solar spectrum at the surface of Earth. Nevertheless, such an ionizing scenario can become dangerously plausible for astronauts or flight personnel, as well as for persons present at nuclear power plant accidents. On the beneficial side, ionizing radiation is employed as means for destroying the DNA of cancer cells during radiation therapy. Quantitative information about ionization of DNA and its components is important not only for DNA radiation damage, but also for understanding redox properties of DNA in redox sensing or labeling, as well as charge migration along the double helix in nanoelectronics applications. Until recently, the vast majority of experimental and computational data on DNA ionization was pertinent to its components in the gas phase, which is far from its native aqueous environment. The situation has, however, changed for the better due to the advent of photoelectron spectroscopy in liquid microjets and its most recent application to photoionization of aqueous nucleosides, nucleotides, and larger DNA fragments. Here, we present a consistent and efficient computational methodology, which allows to accurately evaluate ionization energies and model photoelectron spectra of aqueous DNA and its individual components. After careful benchmarking, the method based on density functional theory and its time-dependent variant with properly chosen hybrid functionals and polarizable continuum solvent model provides ionization energies with accuracy of 0.2-0.3 e

  3. A NOVEL ENVIRONMENT FRIENDLY METHOD FOR EXPANSION AND MOLDING OF POLYMERIC FOAM

    Science.gov (United States)

    The objective of the project is to develop an environment friendly, novel and efficient alternative process for expansion and molding of polymeric foam. Spherical, expandable polymer beads are prepared from liquid monomer suspended in an aqueous medium, containing an expansion...

  4. Effect of intake of aqueous stem extract of Anisopus mannii on haematological parameters in rats

    Directory of Open Access Journals (Sweden)

    D Sani

    2009-09-01

    Full Text Available Summary: These studies were conducted to investigate changes in haematological parameters of rats fed with prolong graded doses of Anisopus mannii. The limit dose test of Up and Down procedure as revised by Dixon was employed to determine the acute oral toxicity of the plant.  The result revealed that the Median lethal dose of the plant is greater than 3000mg/kg body weight. The repeated administration of graded doses of  the extract showed a  significant (P<0.05 dose dependent increase in the packed cell volume (PCV and red blood cells count on 21st and 28th day post extract treatment. However, there were no significant (P>0.05 difference in the total white blood cells and differential leukocyte count in all the treated groups of rats compared to there respective day zero and control group. These results show that the aqueous stem extract of Anisopus mannii is relatively safe following oral administration and have possible stimulatory effect on red blood cell production.   Industrial relevance: Blood is a good indicator to determine the physiological and pathological status of man and animal. The parameters measured include packed cell volume, haemoglobin, white blood cell count and platelets count. The normal ranges of these parameters can be altered by the ingestion of some toxic plants. The plant Anisopus mannii (Family Asclepiadaceae, is known as ‘Sakayau’ or ‘Kashe zaki’( meaning sweet killer among the Hausas of the northern Nigeria, where a cold decoction of the stem is traditionally used as remedy for hyperglycaemia. Despite the widespread use of this plant in this environment, there is little literature on the scientific evaluation of its haematological effect thus screening of plants for toxicity aiming at ascertaining their safety seems to be promising, as toxicity following overdose or the active principles present in the plant could pose as limitation to their potential usefulness and may even lead to death. This present

  5. Aqueous nitrate flowsheet optimization and enhancement using the ATLAS facility

    International Nuclear Information System (INIS)

    The Advanced Testing Line for Actinide Separations (ATLAS) is a pilot plant of all aqueous nitrate plutonium recovery and purification operations within the Los Alamos Plutonium Facility. The main unit operations include dissolution, anion exchange, precipitations, evaporation, calcination, and waste stream polishing. In the current political environment, the emphasis has been redirected from the traditional goal of recovering a pure plutonium product to that of generating ''clean'' effluents while placing the plutonium into a form suitable for long term storage. The ATLAS facility is uniquely suited to fulfill this new role in the development and demonstration of new or revisited technologies. This report summarizes recent work in equipment improvements to the batch dissolver, an evaluation of homogeneous hydroxide precipitations, a demonstration of nitric acid recycle, and the preparation of neptunium and plutonium standards

  6. Sweet aqueous solution for electrochemical synthesis of polypyrrole

    Energy Technology Data Exchange (ETDEWEB)

    Bazzaoui, M. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal) and Faculdade de Engenharia, Departamento de Electrotecnica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal)]. E-mail: bazzaoui@fe.up.pt; Martins, J.I. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal) and Faculdade de Engenharia, Departamento de Electrotecnica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal)]. E-mail: jipm@fe.up.pt; Costa, S.C. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Bazzaoui, E.A. [Faculte des Sciences, Departement de Chimie, Universite Mohammed Ier, 60 000 Oujda (Morocco); Reis, T.C. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Martins, L. [Faculdade de Engenharia, Departamento de Electrotecnica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal)

    2006-02-25

    The electrosynthesis of polypyrrole (PPy) has been achieved on aluminum electrode in aqueous medium of 0.1 M saccharin sodium salt and 0.5 M pyrrole. Scanning electron microscopy shows that the PPy coating obtained in galvanostatic and potentiostatic modes starts with small islands at weak applied potentials or current densities. Moreover, energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) reveal a good homogeneity of the film achieved in cyclic voltammetry during 10 cycles. The electrochemical impedance spectroscopy (EIS) results show that the coating decreases the polarization resistance of the aluminum electrode. The open circuit potential (OCP) and dc polarization measurements achieved in HCl and NaCl solutions displayed a large positive displacement of corrosion potential and a reduction of corrosion current in the case of PPy coating electrode in comparison with electrode bare.

  7. Hydrophobins as aqueous lubricant additive for a soft sliding contact

    DEFF Research Database (Denmark)

    Lee, Seunghwan; Røn, Troels; Pakkanen, Kirsi I.;

    2015-01-01

    Two type II fungal hydrophobins, HFBI and FpHYD5, have been studied as aqueous lubricant additive at a nonpolar, compliant sliding contact (self-mated poly(dimethylsiloxane) (PDMS) contact) at two different concentrations, 0.1 mg/mL and 1.0 mg/mL. The two hydrophobins are featured as non......-PDMS sliding interface was effectively lubricated by the hydrophobin solutions, and showed a reduction in the coefficient of friction by as much as ca. two orders of magnitude. Higher concentration solution (1.0 mg/mL) provided a superior lubrication, particularly in low-speed regime, where boundary...... lubrication characteristic is dominant via ‘self-healing’ mechanism. FpHYD5 revealed a better lubrication than HFBI presumably due to the presence of glycans and improved hydration of the sliding interface. Two type II hydrophobins function more favorably compared to a synthetic amphiphilic copolymer, PEO...

  8. Factors governing the behaviour of aqueous methane in narrow pores.

    Science.gov (United States)

    Phan, Anh; Cole, David R; Striolo, Alberto

    2016-02-13

    All-atom equilibrium molecular dynamics simulations were employed to investigate the behaviour of aqueous methane confined in 1-nm-wide pores obtained from different materials. Models for silica, alumina and magnesium oxide were used to construct the slit-shaped pores. The results show that methane solubility in confined water strongly depends on the confining material, with silica yielding the highest solubility in the systems considered here. The molecular structure of confined water differs within the three pores, and density fluctuations reveal that the silica pore is effectively less 'hydrophilic' than the other two pores considered. Comparing the water fluctuation autocorrelation function with local diffusion coefficients of methane across the hydrated pores we observed a direct proportional coupling between methane and water dynamics. These simulation results help to understand the behaviour of gas in water confined within narrow subsurface formations, with possible implications for fluid transport. PMID:26712646

  9. Adsorption of basic dye from aqueous solution onto fly ash

    Energy Technology Data Exchange (ETDEWEB)

    J.X. Lin; S.L. Zhan; M.H. Fang; X.Q. Qian; H. Yang [Zhejiang University, Hangzhou (China). College of Civil Engineering and Architecture

    2008-04-15

    The fly ash treated by H{sub 2}SO{sub 4} was used as a low-cost adsorbent for the removal of a typical dye, methylene blue, from aqueous solution. An increase in the specific surface area and dye-adsorption capacity was observed after the acid treatment. The adsorption isotherm and kinetics of the treated fly ash were studied. The experimental results were fitted using Langmuir and Freundlich isotherms. It shows that the Freundlich isotherm is better in describing the adsorption process. Two kinetic models, pseudo-first order and pseudo-second order, were employed to analyze the kinetic data. It was found that the pseudo-second-order model is the better choice to describe the adsorption behavior. The thermodynamic study reveals that the enthalpy ({Delta}H{sup 0}) value is positive (5.63 kJ/mol), suggesting an endothermic nature of the adsorption.

  10. Antimicrobial effect of an aqueous extract of Potentilla erecta rhizome

    Directory of Open Access Journals (Sweden)

    Synowiec Alicja

    2014-10-01

    Full Text Available Potentilla erecta is a therapeutic plant used in folk medicine to treat inflammatory states, wounds and diseases of the alimentary tract. The results of the study reveal the effects of an aqueous extract of P. erecta rhizome on certain microorganisms occurring in food. The main components of the extract were catechins. The extract was shown to display an inhibiting effect against Gram-positive bacteria such as Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 6633, as well as against yeast such as Candida lipolitica KKP 322 and Hansenula anomala R 26. The extract did inhibit the growth of Gram-negative bacteria, however, no inhibiting effects were observed on moulds in the studied range of concentrations, i.e. 0.13 to 64 mg dry matter/ml.

  11. Conversion of phosphogypsum to potassium sulfate and calcium carbonate in aqueous solution

    Directory of Open Access Journals (Sweden)

    Ennaciri Y.

    2013-09-01

    Full Text Available The dissociation of the phosphogysum by the liquid route which is the object of our work, is most appropriate and little expensive. Indeed, it leads to materials of direct application. The present work has for objective to study the decomposition of the phosphogypsum by the soft chemistry into valuable products such as K2SO4 and CaCO3. K2SO4 is a fertilizer which is highly recommended in the field of the agriculture, while CaCO3 can be used in the fields of the industry (cement and the environment. According to the obtained results, we notice that the decomposition of the phosphogypsum in aqueous solution is very workable, reproducible, inexpensive and it is an ecologically interesting reaction. This reaction is made at room temperature and in aqueous environment, by giving two valuable products K2SO4 and CaCO3. The reaction is total after one hour and a half.

  12. 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

  13. Aqueous-Phase Reactions of Isoprene with Sulfoxy Radical Anions as a way of Wet Aerosol Formation in the Atmosphere

    Science.gov (United States)

    Kuznietsova, I.; Rudzinski, K. J.; Szmigielski, R.; Laboratory of the Environmental Chemistry

    2011-12-01

    Atmospheric aerosols exhibit an important role in the environment. They have implications on human health and life, and - in the larger scale - on climate, the Earth's radiative balance and the cloud's formation. Organic matter makes up a significant fraction of atmospheric aerosols (~35% to ~90%) and may originate from direct emissions (primary organic aerosol, POA) or result from complex physico-chemical processes of volatile organic compounds (secondary organic aerosol, SOA). Isoprene (2-methyl-buta-1,3-diene) is one of the relevant volatile precursor of ambient SOA in the atmosphere. It is the most abundant non-methane hydrocarbon emitted to the atmosphere as a result of living vegetation. According to the recent data, the isoprene emission rate is estimated to be at the level of 500 TgC per year. While heterogeneous transformations of isoprene have been well documented, aqueous-phase reactions of this hydrocarbon with radical species that lead to the production of new class of wet SOA components such as polyols and their sulfate esters (organosulfates), are still poorly recognized. The chain reactions of isoprene with sulfoxy radical-anions (SRA) are one of the recently researched route leading to the formation of organosulfates in the aqueous phase. The letter radical species originate from the auto-oxidation of sulfur dioxide in the aqueous phase and are behind the phenomenon of atmospheric acid rain formation. This is a complicated chain reaction that is catalyzed by transition metal ions, such as manganese(II), iron(III) and propagated by sulfoxy radical anions . The presented work addresses the chemical interaction of isoprene with sulfoxy radical-anions in the water solution in the presence of nitrite ions and nitrous acid, which are important trace components of the atmosphere. We showed that nitrite ions and nitrous acid significantly altered the kinetics of the auto-oxidation of SO2 in the presence of isoprene at different solution acidity from 2 to 8

  14. Proverbs Reveal Culture Diversity

    OpenAIRE

    Hou, Rong

    2013-01-01

    Through the analysis of property of culture and proverb, it can be known that proverb can help one to understand a culture. The way proverb reveals culture diversity can be connected with the patterns of value dimension, which conveys the information of a culture’s deep meaning. From the perspective of uncertainty-avoidance, it can be seen that although Ireland and America both are low-uncertainty-avoidance cultures, they mainly have different life attitudes, because that Americans put more e...

  15. Aqueous solutions of ionic liquids: microscopic assembly

    NARCIS (Netherlands)

    J.M. Vicent-Luna; D. Dubbeldam; P. Gómez-Álvarez; S. Calero

    2016-01-01

    Aqueous solutions of ionic liquids are of special interest, due to the distinctive properties of ionic liquids, in particular, their amphiphilic character. A better understanding of the structure-property relationships of such systems is hence desirable. One of the crucial molecular-level interactio

  16. Organic compounds trapped in aqueous fluid inclusions

    Energy Technology Data Exchange (ETDEWEB)

    Ruble, T.E.D.; George, S.C.; Lisk, M.; Quezada, R.A. [CSIRO Div. of Petroleum Resources, North Ryde (Australia)

    1998-12-31

    Fluid inclusion samples from several Australian oil wells have been analysed to document the prevalence and composition of volatile hydrocarbons contained within aqueous inclusions. These results clearly establish that trapped palaeo formation waters can be a source of such compounds, which are frequently predominant in samples with a low content of oil-bearing inclusions. The apparent ``anomalous`` hydrocarbons distributions derived from aqueous inclusions contain abundant water-soluble compounds, such as benzene and toluene, which may originate from interaction of formation waters with subsurface petroleum accumulations. Aqueous inclusions are also often enriched in alkenes and oxygenated species, such as furans, which are minor constituents of petroleum but could form via secondary processes such as anoxic microbial degradation in formation waters. The co-occurrence of aqueous-derived organic compounds within samples containing oil inclusions suggest the need for caution when interpreting volatile hydrocarbon distributions. However, the presence of these components in samples from dry wells could be used as a tool to substantiate the proximity of a petroleum accumulation in an area which would otherwise be considered to have low prospectivity. (author)

  17. Tangential Ultrafiltration of Aqueous "Saccharomyces Cerevisiae" Suspensions

    Science.gov (United States)

    Silva, Carlos M.; Neves, Patricia S.; Da Silva, Francisco A.; Xavier, Ana M. R. B.; Eusebio, M. F. J.

    2008-01-01

    Experimental work on ultrafiltration is presented to illustrate the practical and theoretical principles of this separation technique. The laboratory exercise comprises experiments with pure water and with aqueous "Saccharomyces cerevisiae" (from commercial Baker's yeast) suspensions. With this work students detect the characteristic phenomena…

  18. Poetics of Urban Environment

    Directory of Open Access Journals (Sweden)

    Vyacheslav Glazychev

    2007-07-01

    Full Text Available Environment is assumed as both object-space surroundings in their sensibly given components, and surroundings of a human being in particularly social sense revealed in observed signs of distribution of roles and positions. When focusing on the first interpretation we face mostly the «still life» vision of the city. Here the city is equated to a landscape, for example in English terminology the word 'townscape' has this very fixed meaning. In the traditional art history estimation the townscape is easily analyzed both as a whole and elementarily. When focusing on the second interpretation the surroundings are usually intensively broken down into their constituent parts: Gogol's Nevsky Avenue is a poetically shaped social-psychological «section» of the street, almost absolutely free of its topographic definiteness.The general bivalence of the word 'environment' will not be an obstacle here, but on the contrary we will consider this very bivalence as an essential characteristic of the subject. How to research this subject with indistinct frames and eluding shape, if ambivalence is its essence? This task was perfectly carried out by Italo Calvino, a writer, his «Invisible Cities» are the broadest typology of all conceivable urban environments, a collection of their poetic 'models'. The urban environment – a dense clot of spontaneous impressions and respective mental constructions – cannot be researched in vitro, whereas it could be in the past and it can be now successfully studied by art. This wonderful ability of art, abstractedly from live concreteness of urban environment, may be expressed just by means of free art history interpretation, which is not strictly bounded by the rule of unity of object and language, time and place.When and under which conditions does the urban environment act as an object of aesthetic experience and understanding? What metamorphoses does the aesthetic development of urban environment experience depending

  19. Phytochemical properties and cytotoxicity evaluation of the aqueous extracts from Rafflesia cantleyi

    Science.gov (United States)

    Bakoush, Sumaia Mohamed Mohamed; Yaacob, Wan Ahmad; Adam, Jumaat; Ibrahim, Nazlina

    2015-09-01

    In the present study, phytochemical properties and cytotoxic evaluation of aqueous extract of Rafflesia cantleyi bud parts were done. Three bud parts including disk, bract and perigone tube were extracted in water to produce crude aqueous extract. Cytotoxic activity of R. cantleyi bud parts was assessed by conducting 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against normal cells Vero, 3T3 cell lines and mice peripheral blood mononuclear cells PBMC. Phytochemical analyses revealed the presence of tannins, flavonoids, steroids and alkaloids. The CC50 value against Vero, 3T3 and PBMC cells were equal or more than 125 µg/ml indicating the non-cytotoxic effect of the bud parts extracts. The finding revealed that crude extracts of all the tested bud parts contained potential bioactive compounds which can be used for various biological activities and have no cytotoxicity to selected normal cells.

  20. Photoluminescence intensity enhancement in SWNT aqueous suspensions due to reducing agent doping: Influence of adsorbed biopolymer

    Science.gov (United States)

    Kurnosov, N. V.; Leontiev, V. S.; Linnik, A. S.; Lytvyn, O. S.; Karachevtsev, V. A.

    2014-06-01

    The influence of biopolymer wrapped around nanotube on the enhancement of the semiconducting single-walled carbon nanotube (SWNT) photoluminescence (PL) in aqueous suspension which increases due to the reducing agent dithiothreitol (DTT) doping effect was revealed. The greatest enhancement of PL was observed for SWNTs covered with double- or single stranded DNA (above 170%) and DTT weak influence was revealed for SWNTs:polyC suspension (∼45%). The magnitude of the PL enhancement depends also on nanotube chirality and sample aging. The behavior of PL from SWNTs covered with various polymers is explained by the different biopolymers ordering on the nanotube surface. The ordered polymer conformation on the nanotube weakens the reducing agent doping effect. The method of reducing agent doping of nanotube:biopolymer aqueous suspension can serve as a sensitive luminescent probe of the biopolymer ordering on the carbon nanotube and can be used to increase the sensitivity of luminescent biosensors.

  1. How molecular internal-geometric parameters affect PB-PEO polymersome size in aqueous solution

    DEFF Research Database (Denmark)

    Habel, Joachim Erich Otto; Ogbonna, Anayo; Larsen, Nanna; Schulte, Lars; Almdal, Kristoffer; Hélix-Nielsen, Claus

    2016-01-01

    Amphiphilic polybutadiene polyethylene oxide (PB-PEO) is one of the best known chemistries to form stable vesicular morphologies, stated as polymersomes, in aqueous environment. Mimicking cell membranes, these structures self-assemble in an “amphiphilic window” determined by 0.15 < f < 0.35 where f...... for subsequent tuning of size via extrusion. This can pave the way for cost-effective upscaling of polymersome production for biomedical and biomimetic applications. ©...

  2. Biosorption of malachite green from aqueous solutions by Pleurotus ostreatus using Taguchi method

    OpenAIRE

    Chen, Zhengsuo; Deng, Hongbo; Chen, Can; Yang, Ying; Xu, Heng

    2014-01-01

    Dyes released into the environment have been posing a serious threat to natural ecosystems and aquatic life due to presence of heat, light, chemical and other exposures stable. In this study, the Pleurotus ostreatus (a macro-fungus) was used as a new biosorbent to study the biosorption of hazardous malachite green (MG) from aqueous solutions. The effective disposal of P. ostreatus is a meaningful work for environmental protection and maximum utilization of agricultural residues. The operation...

  3. Comparison efficiency of both sonochemical and sonochemical/hydrogen peroxide processes forcyanide removal from aqueous solutions

    OpenAIRE

    Reza Shokohi; Amir Hossein Mahvi; Ziaeddin Bonyadi

    2009-01-01

    (Received 5 October, 2009 ; Accepted 23 December, 2009)AbstractBackground and purpose: Cyanide is a species of high toxicity that is found mostly in industrial effluents such as electroplating, metal mining, metallurgy and metal cleaning processes. Entrance of it to existing environment contains a hazardous to health. The purpose of this study was to compare efficiency of both sonochemical and sonochemical / hydrogen peroxide processes for cyanide removal from aqueous solutions.Materials and ...

  4. Removal of Reactive Red 120 from aqueous solutions using surface modified natural zeolite

    OpenAIRE

    K Naddafi; M Gholami

    2014-01-01

    Background & objective: Synthetic dyes are extensively used in various industries such as textile, leather tanning, plastic, pulp and paper. Since dyes are toxic and even carcinogenic, discharging dye-containing wastewater into the environment poses serious environmental and health problems. Therefore, the purpose of this paper was to evaluate the removal of Reactive Red 120 from aqueous solutions using surface modified natural zeolite. Materials &Methods: The Semnan zeolite was sieved usi...

  5. Enhanced resistance to oxidative decomposition of aqueous electrolytes for aqueous lithium-ion batteries.

    Science.gov (United States)

    Miyazaki, Kohei; Shimada, Toshiki; Ito, Satomi; Yokoyama, Yuko; Fukutsuka, Tomokazu; Abe, Takeshi

    2016-04-11

    An efficient electrolyte solution containing organic sulfonates for use in aqueous rechargeable lithium-ion batteries (ARLBs) is shown to provide a wide potential window and enable a high operating voltage for ARLBs. PMID:26911197

  6. Mercury removal from aqueous and organo-aqueous solutions by natural Mexican erionite

    International Nuclear Information System (INIS)

    The sorption of Hg(II) from aqueous and organo aqueous solutions was investigated by Mexican natural erionite. The mercury chemical species (anionic, cationic or neutral) were determined by high voltage electrophoresis, and the mercury chemical species present in the aqueous media were simulated by a program MEDUSA. The mercury sorption process was monitored during 48 hours. The mercury content was determined by neutron activation analysis. Mixtures of benzene/water[Hg(II)], toluene/water[Hg(II)] and ethanol/water[Hg(II)] were chosen as organo-aqueous media. It was found that both the mercury chemical species and the dielectric constant of solvents play an important role in the mercury sorption by erionite. (author)

  7. Sorption characteristics of technetium on crosslinked chitosan from aqueous solutions

    International Nuclear Information System (INIS)

    Removal of radioactive ions from the wastewaters is a huge problem because these ions are extremely dangerous for environment and human health by their high toxicity at very low concentrations and long half lives. These pollutants arise into the wastewaters as a result of different industrial activities like: mining, production of nuclear fuels, laboratory investigations, etc. The methods developed for removal of radioisotopes from wastewaters include: chemical precipitation, ion exchange, membrane-related processes, biological processes and electrochemical techniques. The application of polymer such as chitosan is one of the emerging adsorption methods for removal of dyes and heavy metal ions, even at low concentrations. Chitosan is a type of natural polyaminosaccharide, synthesized from deacetylation of chitin. It is composed of β (1→4) linked 2-amino-2-deoxy-D-glucopyranose units. Chitosan is very sensitive to pH as it can either form gel or dissolve depending on the pH values. To improve chitosan's performance as an adsorbent, cross-linking reagents such as glyoxal, formaldehyde, glutaraldehyde, epichlorohydrin have been used. Cross-linking agents do not only stabilize chitosan in acid solutions so that is becomes insoluble but also enhance its mechanical properties and adsorption capacity. Crosslinked chitosan is suitable for the sorption of radionuclides from aqueous solutions, such as cesium, cobalt, europium, uranium, thorium, technetium, plutonium, and americium due to the presence of amino and hydroxyl groups, which are the active sites. Technetium has no stable isotope in nature, it has essentially all been created by human activities. Among radioactive isotopes, 99Tc has a half-life 2.1·105 years sufficiently long enough to warrant concern and it is produced in the fission of 235U and 239Pu with a relatively high yield of about 6 %. The radionuclide, 99Tc, has been released into the environment during nuclear weapons testing. Since discharges

  8. Quasi-Immiscible Spreading of Aqueous Surfactant Solutions on Entangled Aqueous Polymer Solution Subphases

    OpenAIRE

    Sharma, Ramankur; Corcoran, Timothy E.; Garoff, Stephen; Przybycien, Todd M.; Swanson, Ellen R.; Tilton, Robert D.

    2013-01-01

    Motivated by the possibility of enhancing aerosol drug delivery to mucus-obstructed lungs, the spreading of a drop of aqueous surfactant solution on a physically entangled aqueous poly(acrylamide) solution subphase that mimics lung airway surface liquid was investigated. Sodium dodecyl sulfate was used as the surfactant. To visualize spreading of the drop and mimic the inclusion of a drug substance, fluorescein, a hydrophilic and non-surface active dye, was added to the surfactant solution. T...

  9. Colloidal stability of gadolinium-doped ceria powder in aqueous and non-aqueous media

    OpenAIRE

    López-Robledo, M. J.; Silva-Treviño, J.; Molina, Tamara; Moreno, Rodrigo

    2013-01-01

    In this work the colloidal behaviour of Ce0.9Gd0.1O2-δ powder in aqueous and non-aqueous media (ethanol) is studied. Commercial powder was characterised by particle size distribution, specific surface area measurements, X-ray diffraction and scanning electron microscopy. Diluted suspensions were characterised by particle size distribution and zeta potential, using dynamic light scattering and laser Doppler velocimetry principles, respectively. The solubility of the powder in water as a functi...

  10. Dynamic configuration of reduced graphene oxide in aqueous dispersion and its effect on thin film properties.

    Science.gov (United States)

    Wang, Yufei; Zhang, Xuehua; Li, Dan

    2015-12-28

    The dynamic configuration of reduced graphene oxide (rGO) in an aqueous dispersion is revealed by several characterization methods, showing a spontaneous and seemingly irreversible configuration transition from flat to highly corrugated sheets over time. Such dynamic behaviour of rGO leads to a tailored porous structure of graphene-based thin films. This affects their permeation and electrochemical properties, as well as future industry adoption of graphene. PMID:26498678

  11. Electrochemical synthesis of polypyrrole on ferrous and non-ferrous metals from sweet aqueous electrolytic medium

    Energy Technology Data Exchange (ETDEWEB)

    Bazzaoui, M. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal)]. E-mail: bazzaoui@fe.up.pt; Martins, J.I. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Reis, T.C. [Faculdade de Engenharia, Departamento de Engenharia Quimica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Bazzaoui, E.A. [Faculte des Sciences, Departement de Chimie, Universite Mohammed I er, 60 000 Oujda (Morocco); Nunes, M.C. [Faculdade de Engenharia, Departamento de Electrotecnica, Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Martins, L. [Centre de Recherche Public de la Sante, 18 rue Dicks (Luxembourg)

    2005-08-01

    The electrodeposition of polypyrrole (PPy) on oxidizable metals such as aluminum and iron has been achieved in aqueous medium of saccharin and pyrrole. Scanning electron microscopy and X-ray photoelectron spectroscopy analysis reveal a good homogeneity of the obtained PPy film. The electrochemical synthesis of PPy coating has been achieved successfully under potentiodynamic, galvanostatic and potentiostatic techniques. The corrosion experiments performed in HCl show that the PPy coating increases the corrosion potential and decreases the corrosion current density.

  12. Asymmetrical Self-assembly From Fluorinated and Sulfonated Block Copolymers in Aqueous Media

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaojun [ORNL; Hong, Kunlun [ORNL; Baskaran, Durairaj [University of Tennessee, Knoxville (UTK); Goswami, Monojoy [ORNL; Sumpter, Bobby G [ORNL; Mays, Jimmy [ORNL

    2011-01-01

    Block copolymers of fluorinated isoprene and partially sulfonated styrene form novel tapered rods and ribbon-like micelles in aqueous media due to a distribution of sulfonation sites and a large Flory-Huggins interaction parameter. A combination of microscopy, light scattering, and simulation demonstrates the presence of these unique nanostructures. This study sheds light on the micellization behavior of amphiphilic block polymers by revealing a new mechanism of self-assembly.

  13. Removal of dissolved TBP from aqueous streams of reprocessing origin: engineering scale studies

    International Nuclear Information System (INIS)

    Process development for removal of dissolved TBP from acidic solutions has been addressed in the present work using solvent extraction route. Batch studies were followed with continuous runs using combine air lift based mixer-settler units. These studies have revealed that the dissolved TBP in aqueous solutions can be brought down from ∼ 160 ppm to ∼ 15 ppm using dodecane with a maximum loading of ∼ 3.6% TBP. (author)

  14. Anxiolytic, sedative, and hypnotic activities of aqueous extract of Morinda citrifolia fruit

    OpenAIRE

    Sridharan Kannan; Shanti Manickam; Meher Ali RajaMohammed

    2014-01-01

    Morinda citrifolia (Indian mulberry or noni) fruit has been long used as a folk medicine for a wide range of health purposes as it is claimed to have analgesic, antiinflammatory, antioxidant, detoxifier, and cell-rejuvenator properties. A recent study has revealed central nervous system suppressant nature of its extract. Hence, the present study has evaluated the anxiolytic, sedative, and hypnotic effects of the aqueous extracts of Morinda citrifolia in rodents in comparison to diazepam. Anxi...

  15. Nano-structured textiles as high-performance aqueous cathodes for microbial fuel cells

    KAUST Repository

    Xie, Xing

    2011-01-01

    A carbon nanotube (CNT)-textile-Pt cathode for aqueous-cathode microbial fuel cells (MFCs) was prepared by electrochemically depositing Pt nanoparticles on a CNT-textile. An MFC equipped with a CNT-textile-Pt cathode revealed a 2.14-fold maximum power density with only 19.3% Pt loading, compared to that with a commercial Pt coated carbon cloth cathode. © 2011 The Royal Society of Chemistry.

  16. Eco-friendly synthesis of Graphene using the aqueous extract of Amaranthus dubius

    OpenAIRE

    M. Jannathul Firdhouse; Lalitha, P.

    2013-01-01

    An eco-friendly process of reduction of graphene oxide using aqueous extract of Amaranthus dubius under refluxing method is herein reported. The colour change of the graphene oxide (GO) solution from brown to black was noted during the reduction of graphene oxide. UV-Visible spectrophotometer was used to monitor the formation of reduced graphene oxide (AKRGO). The crystallite size of nanographene was confirmed by XRD analysis and Scherrer’s formula. FTIR spectral analysis revealed the reducti...

  17. Application of Neem Gum for Aqueous Film Coating of Ciprofloxacin Tablets

    OpenAIRE

    A P Kulkarni; Y R Shaikh; MH GR Dehghan

    2013-01-01

    Summary. At present the pharmaceutical industry and academia are focusing on the use of natural materials and resources for development of pharmaceutical product. In previous study, neem gum (NG), obtained from Azadirachata indica plant revealed satisfactory film forming ability. The present study evaluates the application potential of neem gum, as an aqueous film coating material, using ciprofloxacin hydrchloride (drug) as a model drug. Initial study of physical mixture indicated absence of ...

  18. Facile stabilization of cyclodextrin metal-organic frameworks under aqueous conditions via the incorporation of C60 in their matrices.

    Science.gov (United States)

    Li, Haiqing; Hill, Matthew R; Huang, Runhong; Doblin, Christian; Lim, Seng; Hill, Anita J; Babarao, Ravichandar; Falcaro, Paolo

    2016-05-21

    A facile method to improve the stability of γ-cyclodextrin metal-organic frameworks (γ-CD-MOFs) in an aqueous environment has been developed through the incorporation of hydrophobic C60 in their matrices, and the resulting hybrid materials were exploited for drug delivery applications. PMID:27055670

  19. Revealing the programming process

    DEFF Research Database (Denmark)

    Bennedsen, Jens; Caspersen, Michael Edelgaard

    2005-01-01

    One of the most important goals of an introductory programming course is that the students learn a systematic approach to the development of computer programs. Revealing the programming process is an important part of this; however, textbooks do not address the issue -- probably because...... the textbook medium is static and therefore ill-suited to expose the process of programming. We have found that process recordings in the form of captured narrated programming sessions are a simple, cheap, and efficient way of providing the revelation.We identify seven different elements of the programming...

  20. TypeScript revealed

    CERN Document Server

    Maharry, Dan

    2013-01-01

    TypeScript Revealed is a quick 100-page guide to Anders Hejlsberg's new take on JavaScript. With this brief, fast-paced introduction to TypeScript, .NET, Web and Windows 8 application developers who are already familiar with JavaScript will easily get up to speed with TypeScript and decide whether or not to start incorporating it into their own development. TypeScript is 'JavaScript for Application-scale development'; a superset of JavaScript that brings to it an additional object-oriented-like syntax familiar to .NET programmers that compiles down into simple, clean JavaScript that any browse

  1. Fetal environment

    International Nuclear Information System (INIS)

    The intrauterine environment has a strong influence on pregnancy outcome. The placenta and the umbilical cord together form the main supply line of the fetus. Amniotic fluid also serves important functions. These three main components decide whether there will be an uneventful pregnancy and the successful birth of a healthy baby. An insult to the intrauterine environment has an impact on the programming of the fetus, which can become evident in later life, mainly in the form of cardiovascular diseases, diabetes, and certain learning disabilities. The past two decades have witnessed major contributions from researchers in this field, who have included ultrasonologists, epidemiologists, neonatologists, and pediatricians. Besides being responsible for these delayed postnatal effects, abnormalities of the placenta, umbilical cord, and amniotic fluid also have associations with structural and chromosomal disorders. Population and race also influence pregnancy outcomes to some extent in certain situations. USG is the most sensitive imaging tool currently available for evaluation of these factors and can offer considerable information in this area. This article aims at reviewing the USG-related developments in this area and the anatomy, physiology, and various pathologies of the placenta, umbilical cord, and the amniotic fluid

  2. Environment surveillance

    International Nuclear Information System (INIS)

    The Cogema group involved in the nuclear fuel cycle from the uranium extraction to the reprocessing of spent fuels and the recycling of re-usable energy materials, performs periodical controls of radioactivity levels in the environment close to its facilities. At Cogema-La Hague, 80000 analyses were performed on 25000 samples taken at 820 different sites in the vicinity of the facility in 1997. These controls concern different elements of the terrestrial and maritime environments (surface and ground waters, rain water, plants, beach sand, marine sediments, marine fauna and flora). After a brief presentation of natural and artificial radioactivity, this brochure presents the results of the measurements performed by Cogema-La Hague (alpha- and beta-activity, tritium, 7Be, 40K, 241Am, 137Cs, 125Sb, 129I, 90Sr, 106Ru, 60Co, 110mAg) in air, surface waters, grass, milk, coastal waters, algae, molluscs and fishes. A special chapter is devoted to the presentation of tritium (origin, metabolism, toxicity, concentration in effluents). (J.S.)

  3. Biosorption of Cd(II) and Pb(II) ions by aqueous solutions of novel alkalophillic Streptomyces VITSVK5 spp. biomass

    Science.gov (United States)

    Saurav, Kumar; Kannabiran, Krishnan

    2011-03-01

    Discharge of heavy metals from metal processing industries is known to have adverse effects on the environment. Biosorption of heavy metals by metabolically inactive biomass of microbial organisms is an innovative and alternative technology for removal of these pollutants from aqueous solution. The search of marine actinobacteria with potential heavy metal biosorption ability resulted in the identification of a novel alkalophilic Streptomyces VITSVK5 species. The biosorption property of Streptomyces VITSVK5 spp. was investigated by absorbing heavy metals Cadmium (Cd) and Lead (Pb). Physiochemical characteristics and trace metal concentration analysis of the backwater showed the concentrations of different metals were lead 13±2.1 μg L-1, cadmium 3.1±0.3μg L-1, zinc 8.4±2.6μg L-1 and copper 0.3±0.1μg L-1, whereas mercury was well below the detection limit. The effect of pH and biomass dosage on removal efficiency of heavy metal ions was also investigated. The optimum pH for maximal biosorption was 4.0 for Cd (II) and 5.0 for Pb (II) with 41% and 84% biosorption respectively. The biosorbent dosage was optimized as 3 g L-1 for both the trace metals. Fourier transform infrared absorption spectrum results indicated the chemical interactions of hydrogen atoms in carboxyl (-COOH), hydroxyl (-CHOH) and amine (-NH2) groups of biomass with the metal ions. This could be mainly involved in the biosorption of Cd (II) and Pb (II) onto Streptomyces VITSVK5 spp. The results of our study revealed Streptomyces metabolites could be used to develop a biosorbent for adsorbing metal ions from aqueous environments.

  4. Biosorption of Cd(Ⅱ)and Pb(Ⅱ)Ions by Aqueous Solutions of Novel Alkalophillic Streptomyces VITSVK5 spp.Biomass

    Institute of Scientific and Technical Information of China (English)

    Kumar Saurav; Krishnan Kannabiran

    2011-01-01

    Discharge of heavy metals from metal processing industries is known to have adverse effects on the environment.Biosorption of heavy metals by metabolically inactive biomass of microbial organisms is an innovative and alternative technology for removal of these pollutants from aqueous solution.The search of marine actinobacteria with potential heavy metal biosorption ability resulted in the identification of a novel alkalophilic Streptomyces VITSVK5 species.The biosorption property of Streptomyces VITSVK5 spp.was investigated by absorbing heavy metals Cadmium(Cd)and Lead(Pb).Physiochemical characteristics and trace metal concentration analysis of the backwater showed the concentrations of different metals were lead 13±2.1 μg L·1,cadmium 3.1±0.3 μg L·1,zinc 8.4±2.6μg L·1 and copper 0.3±0.1μg L·1,whereas mercury was well below the detection limit.The effect of pH and biomass dosage on removal efficiency of heavy metal ions was also investigated.The optimum pH for maximal biosorption was4.0 for Cd(Ⅱ)and 5.0 for Pb(Ⅱ)with 41% and 84% biosorption respectively.The biosorbent dosage was optimized as 3 g L-1 for both the trace metals.Fourier transform infrared absorption spectrum results indicated the chemical interactions of hydrogen atoms in carboxyl(-COOH),hydroxyl(-CHOH)and amine(-NH2)groups of biomass with the metal ions.This could be mainly involved in the biosorption of Cd(Ⅱ)and Pb(Ⅱ)onto Streptomyces VITSVK5 spp.The results of our study revealed Streptomyces metabolites could be used to develop a biosorbent for adsorbing metal ions from aqueous environments.

  5. Synthesis and spectroscopic and structural studies of a new cadmium(II)-citrate aqueous complex. Potential relevance to cadmium(II)-citrate speciation and links to cadmium toxicity.

    Science.gov (United States)

    Dakanali, M; Kefalas, E T; Raptopoulou, C P; Terzis, A; Mavromoustakos, T; Salifoglou, A

    2003-04-21

    The presence of cadmium in the environment undoubtedly contributes to an increased risk of exposure and ultimate toxic influence on humans. In an effort to comprehend the chemical and biological interactions of Cd(II) with physiological ligands, like citric acid, we explored the requisite aqueous chemistry, which afforded the first aqueous Cd(II)-citrate complex [Cd(C(6)H(6)O(7))(H(2)O)](n)() (1). Compound 1 was characterized by elemental analysis, and spectroscopically by FT-IR and (113)Cd MAS NMR. Compound 1 crystallizes in the orthorhombic space group P2(1)2(1)2(1), with a = 6.166(2) A, b = 10.508(3) A, c = 13.599(5) A, V = 881.2(5) A(3), and Z = 4. The X-ray structure of 1 reveals the presence of octahedral Cd(II) ions bound to citrate ligands in a molecular crystal lattice. Citrate acts as a tridentate binder promoting coordination to one Cd(II) through the central alcoholic moiety, one terminal carboxylate group, and the central carboxylate group. In addition, the central carboxylate binds to three Cd(II) ions. Specifically, one of the oxygens of the central carboxylate serves as a bridge to two neighboring Cd(II) ions, while the other oxygen binds to a third Cd(II). A bound water molecule completes the coordination requirements of Cd(II). (113)Cd MAS NMR studies project the spectroscopic signature of the nature of the coordination environment around Cd(II) in 1, thus corroborating the X-ray findings. Collectively, the data at hand are in line with past solution studies. The latter predict that other similar low molecular mass Cd(II)-citrate complexes may exist in the acidic pH region, thus influencing the uptake of cadmium by living (micro)organisms, their ability to metabolize organic substrates, and possibly Cd(II) toxicity. PMID:12691558

  6. The study of furfural removal from aqueous solutions using activated carbon and bentonite modified with cetyltrimethylammonium bromide (CTAB, a cationic surfactant

    Directory of Open Access Journals (Sweden)

    M Leili

    2016-01-01

    Full Text Available Background and Objectives: Furfural is one of the toxic chemical compounds used in many industries such as petrochemical, food, paper products, pharmaceutical, etc., due to having some characteristics. Therefore, furfural could be found at different concentrations in the effluent from these industries and can enter the environment. Hence, the aim of this study was the assessment the efficiency of a low cost bentonite modified with cationic surfactant in the removal of furfural from aqueous solution. Material and Methods: In this experimental study, bentonite was purchased from one of the Mines of Zanjan Province, Iran and then the efficiency of bentonite modified with the cationic surfactant CTAB (CTAB-Bent was assessed in the adsorption of furfural from aqueous solution. Activated carbon (AC was also purchased as commercial grade. Results: Under optimum conditions, the removal efficiency of AC and CTAB-Bent was about 52 and 66%, respectively. For both adsorbents used in this study, the increase of contact time and sorbent dosage resulted in increasing the removal efficiency, but the removal efficiency was decreased with the increase of furfural initial concentrations. Regarding pH, the removal efficiency was the highest in relative acidic and neutral environment, (60 and 69% for AC and CTAB-Bent respectively. The kinetics studies revealed that the highest correlation coefficients were obtained for the pseudo-second order rate kinetic model. Adsorption data from both adsorbents was also fitted with Langmuir isotherm.   Conclusion: It was found that modified bentonite with CTAB as a natural adsorbent could have better efficiencies compared with activated carbon in the furfural removal, although more contact times is needed.

  7. Aqueous synthesis and characterization of bovine hemoglobin-conjugated cadmium sulfide nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Guangrui [Institute of Environmental and Municipal Engineering, North China University of Water Conservancy and Electric Power, Zhengzhou 450011 (China); Qin, Dezhi, E-mail: dezhiqin@163.com [College of Chemistry and Chemical Engineering, Pingdingshan University, Pingdingshan 467000 (China); Du, Xian; Zhang, Li; Zhao, Ganqing; Zhang, Qiuxia; Wu, Jiulin [College of Chemistry and Chemical Engineering, Pingdingshan University, Pingdingshan 467000 (China)

    2014-08-01

    Highlights: • CdS nanocrystals were synthesized by biomimetic method in bovine hemoglobin (BHb) solution. • The study of the interaction between Cd{sup 2+}/CdS and BHb. • The optical properties of BHb-conjugated CdS nanocrystals. • The synthesis process of BHb-conjugated CdS nanocrystals is facile, effective and environment friendly. • The change of secondary structure of BHb after binding to CdS nanocrystals. - Abstract: Cadmium sulfide (CdS) nanocrystals with average diameter about 5.5 nm were synthesized in aqueous solution of bovine hemoglobin (BHb) via simple biomimetic method. Powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) characterizations were used to determine the structure and morphology of CdS nanocrystals. It was revealed that amount of BHb, chelating of Cd{sup 2+} to BHb and reaction temperature were key factors in controlling shape and dispersion of CdS nanocrystals. The binding sites of BHb to CdS nanocrystals and the change of secondary structure of protein have been identified by Fourier transform infrared (FT-IR) and circular dichroism (CD) spectroscopy. It was found that conjugating of BHb with Cd{sup 2+} and CdS could protect nanocrystals from agglomerating. Moreover, the thermostability of BHb enhanced after conjugating with CdS nanocrystals. The interaction mechanism of BHb with Cd{sup 2+}/CdS was also proposed. The quantum-confined effect of CdS nanocrystals was confirmed by ultraviolet–visible (UV–vis) spectrum. The nanocrystals exhibited a well-defined photoluminescence (PL) emission feature at about 510 nm with narrow full width at half maximum (FWHM)

  8. Aqueous synthesis and characterization of bovine hemoglobin-conjugated cadmium sulfide nanocrystals

    International Nuclear Information System (INIS)

    Highlights: • CdS nanocrystals were synthesized by biomimetic method in bovine hemoglobin (BHb) solution. • The study of the interaction between Cd2+/CdS and BHb. • The optical properties of BHb-conjugated CdS nanocrystals. • The synthesis process of BHb-conjugated CdS nanocrystals is facile, effective and environment friendly. • The change of secondary structure of BHb after binding to CdS nanocrystals. - Abstract: Cadmium sulfide (CdS) nanocrystals with average diameter about 5.5 nm were synthesized in aqueous solution of bovine hemoglobin (BHb) via simple biomimetic method. Powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) characterizations were used to determine the structure and morphology of CdS nanocrystals. It was revealed that amount of BHb, chelating of Cd2+ to BHb and reaction temperature were key factors in controlling shape and dispersion of CdS nanocrystals. The binding sites of BHb to CdS nanocrystals and the change of secondary structure of protein have been identified by Fourier transform infrared (FT-IR) and circular dichroism (CD) spectroscopy. It was found that conjugating of BHb with Cd2+ and CdS could protect nanocrystals from agglomerating. Moreover, the thermostability of BHb enhanced after conjugating with CdS nanocrystals. The interaction mechanism of BHb with Cd2+/CdS was also proposed. The quantum-confined effect of CdS nanocrystals was confirmed by ultraviolet–visible (UV–vis) spectrum. The nanocrystals exhibited a well-defined photoluminescence (PL) emission feature at about 510 nm with narrow full width at half maximum (FWHM)

  9. Aqueous Synthesis of PEGylated Quantum Dots with Increased Colloidal Stability and Reduced Cytotoxicity.

    Science.gov (United States)

    Ulusoy, Mehriban; Jonczyk, Rebecca; Walter, Johanna-Gabriela; Springer, Sergej; Lavrentieva, Antonina; Stahl, Frank; Green, Mark; Scheper, Thomas

    2016-02-17

    Ligands used on the surface of colloidal nanoparticles (NPs) have a significant impact on physiochemical properties of NPs and their interaction in biological environments. In this study, we report a one-pot aqueous synthesis of 3-mercaptopropionic acid (MPA)-functionalized CdTe/CdS/ZnS quantum dots (Qdots) in the presence of thiol-terminated methoxy polyethylene glycol (mPEG) molecules as a surface coordinating ligand. The resulting mPEG-Qdots were characterized by using ζ potential, FTIR, thermogravimetric (TG) analysis, and microscale thermophoresis (MST) studies. We investigated the effect of mPEG molecules and their grafting density on the Qdots photophysical properties, colloidal stability, protein binding affinity, and in vitro cellular toxicity. Moreover, cellular binding features of the resulting Qdots were examined by using three-dimensional (3D) tumor-like spheroids, and the results were discussed in detail. Promisingly, mPEG ligands were found to increase colloidal stability of Qdots, reduce adsorption of proteins to the Qdot surface, and mitigate Qdot-induced side effects to a great extent. Flow cytometry and confocal microscopy studies revealed that PEGylated Qdots exhibited distinctive cellular interactions with respect to their mPEG grafting density. As a result, mPEG molecules demonstrated a minimal effect on the ZnS shell deposition and the Qdot fluorescence efficiency at a low mPEG density, whereas they showed pronounced effect on Qdot colloidal stability, protein binding affinity, cytotoxicity, and nonspecific binding at a higher mPEG grafting amount. PMID:26567697

  10. Oral environment and cancer.

    Science.gov (United States)

    Kudo, Yasusei; Tada, Hidesuke; Fujiwara, Natsumi; Tada, Yoshiko; Tsunematsu, Takaaki; Miyake, Yoichiro; Ishimaru, Naozumi

    2016-01-01

    Cancer is now the leading cause of death in Japan. A rapid increase in cancer mortality is expected as Japan is facing a super-aged society. Many causes of cancer are known to be closely linked to life style factors, such as smoking, drinking, and diet. The oral environment is known to be involved in the pathogenesis and development of various diseases such as bronchitis, pneumonia, diabetes, heart disease, and dementia. Because the oral cavity acts as the bodily entrance for air and food, it is constantly exposed to foreign substances, including bacteria and viruses. A large number of bacteria are endemic to the oral cavity, and indigenous oral flora act to prevent the settlement of foreign bacteria. The oral environment is influenced by local factors, including dental plaque, tartar, teeth alignment, occlusion, an incompatible prosthesis, and bad lifestyle habits, and systemic factors, including smoking, consumption of alcohol, irregular lifestyle and eating habits, obesity, stress, hormones, and heredity. It has recently been revealed that the oral environment is associated with cancer. In particular, commensal bacteria in the oral cavity are involved in the development of cancer. Moreover, Candida, human papilloma virus and Epstein-Barr virus as well as commensal bacteria have been reported to be associated with the pathogenesis of cancer. In this review, we introduce recent findings of the correlation between the oral environment and cancer. PMID:27482300

  11. Use of aqueous solutions of two basic dyes for the demonstration of DNA

    International Nuclear Information System (INIS)

    This paper presents informations as to the ability of aqueous solutions of two basic dyes, such as Dahlia and Victoria blue, belonging to aminotriarylmethane group for the staining of DNA-aldehyde molecules as well as DNA-phosphate groups. It has been found that sections of rat tissue stained with aqueous solutions of these dyes after acid hydrolysis followed by drying between folds of filter paper and treatment in n-butanol for a minute and then by a very brief treatment in a mixture consisting of equal parts of n-butanol and absolute ethanol reveal well-stained nuclei. Tissue sections after acid hydrolysis when stained with aqueous solutions of these dyes and then treated with SO2 water do not reveal any colouration of the nuclei. Since both the dyes are without any primary amino group in their molecules, it has been concluded that the imino group of Dahlia and the tertiary amino group of Victoria blue may be involved in the staining of DNA-aldehyde molecules. Sections of tissue when treated with cold concentrated phosphoric acid and then stained with any of these dyes also exhibit well-stained nuclei. The absorption spectra of nuclei stained with these dyes for DNA-aldehyde molecules as well as DNA-phosphate groups reveal positions of the peaks of maximum absorption at the same wavelength, which, however, are different in the case of nuclei stained with the two dyes. The implications of these findings have been discussed. (orig.)

  12. Effects of Metal Ions on Viscosity of Aqueous Sodium Carboxylmethylcellulose Solution and Development of Dropping Ball Method on Viscosity

    Science.gov (United States)

    Set, Seng; Ford, David; Kita, Masakazu

    2015-01-01

    This research revealed that metal ions with different charges could significantly affect the viscosity of aqueous sodium carboxylmethylcellulose (CMC) solution. On the basis of an Ostwald viscometer, an improvised apparatus using a dropping ball for examining the viscosity of liquids/solutions has been developed. The results indicate that the…

  13. ISOLATION OF 12, 13-DIHYDRO-20, 20-DIHYDRO LUPEOL FROM THE AQUEOUS EXTRACT OF AESCULUS HIPPOCASTANUM SEEDS.

    OpenAIRE

    Biradar Sanjivkumar; Gavani Usha; Malipatil Mallikarjun; K Sreenivasa Rao

    2011-01-01

    The present study was undertaken to isolate phytoconstituets of aqueous extract pf Aesculus hippocastanum seeds. One compound was isolated from Aesculus hippocastanum by column chromatography method. The spectral analysis revealed the isolated compound as 12, 13-dihydro-20, 20-dihydro lupeol and is belongs to saponins.

  14. ISOLATION OF 12, 13-DIHYDRO-20, 20-DIHYDRO LUPEOL FROM THE AQUEOUS EXTRACT OF AESCULUS HIPPOCASTANUM SEEDS.

    Directory of Open Access Journals (Sweden)

    Biradar Sanjivkumar

    2011-05-01

    Full Text Available The present study was undertaken to isolate phytoconstituets of aqueous extract pf Aesculus hippocastanum seeds. One compound was isolated from Aesculus hippocastanum by column chromatography method. The spectral analysis revealed the isolated compound as 12, 13-dihydro-20, 20-dihydro lupeol and is belongs to saponins.

  15. Bacterial Motility Reveals Unknown Molecular Organization.

    Science.gov (United States)

    Duchesne, Ismaël; Rainville, Simon; Galstian, Tigran

    2015-11-17

    The water solubility of lyotropic liquid crystals (LCs) makes them very attractive to study the behavior of biological microorganisms in an environment where local symmetry is broken (as often encountered in nature). Several recent studies have shown a dramatic change in the behavior of flagellated bacteria when swimming in solutions of the lyotropic LC disodium cromoglycate (DSCG). In this study, the movements of Escherichia coli bacteria in DSCG-water solutions of different concentrations are observed to improve our understanding of this phenomenon. In addition, the viscosity of DSCG aqueous solutions is measured as a function of concentration at room temperature. We also experimentally identify a previously undescribed isotropic pretransition zone where bacteria start sticking to each other and to surfaces. Simple estimations show that the unbalanced osmotic pressure induced depletion force might be responsible for this sticking phenomenon. An estimate of the bacteria propulsive force and the DSCG aggregates length (versus concentration) are calculated from the measured viscosity of the medium. All these quantities are found to undergo a strong increase in the pretransition zone, starting at a threshold concentration of 6±1 wt % DSCG that is well below the known isotropic-LC transition (∼10 wt %). This study also shines light on the motility of flagellated bacteria in realistic environments, and it opens new avenues for interesting applications such as the use of motile microorganisms to probe the physical properties of their host or smart bandages that could guide bacteria out of wounds. PMID:26588572

  16. Investigation of the Hydrolysis of Perovskite Organometallic Halide CH3NH3PbI3 in Humidity Environment

    Science.gov (United States)

    Zhao, Jiangtao; Cai, Bing; Luo, Zhenlin; Dong, Yongqi; Zhang, Yi; Xu, Han; Hong, Bin; Yang, Yuanjun; Li, Liangbin; Zhang, Wenhua; Gao, Chen

    2016-01-01

    Instability of emerging perovskite organometallic halide in humidity environment is the biggest obstacle for its potential applications in solar energy harvest and electroluminescent display. Understanding the detailed decay mechanism of these materials in moisture is a critical step towards the final appropriate solutions. As a model study presented in this work, in situ synchrotron radiation x-ray diffraction was combined with microscopy and gravimetric analysis to study the degradation process of CH3NH3PbI3 in moisture, and the results reveal that: 1) intermediate monohydrated CH3NH3PbI3·H2O is detected in the degradation process of CH3NH3PbI3 and the final decomposition products are PbI2 and aqueous CH3NH3I; 2) the aqueous CH3NH3I could hardly further decompose into volatile CH3NH2, HI or I2; 3) the moisture disintegrate CH3NH3PbI3 and then alter the distribution of the decomposition products, which leads to an incompletely-reversible reaction of CH3NH3PbI3 hydrolysis and degrades the photoelectric properties. These findings further elucidate the picture of hydrolysis process of perovskite organometallic halide in humidity environment. PMID:26924112

  17. Investigation of the Hydrolysis of Perovskite Organometallic Halide CH3NH3PbI3 in Humidity Environment

    Science.gov (United States)

    Zhao, Jiangtao; Cai, Bing; Luo, Zhenlin; Dong, Yongqi; Zhang, Yi; Xu, Han; Hong, Bin; Yang, Yuanjun; Li, Liangbin; Zhang, Wenhua; Gao, Chen

    2016-02-01

    Instability of emerging perovskite organometallic halide in humidity environment is the biggest obstacle for its potential applications in solar energy harvest and electroluminescent display. Understanding the detailed decay mechanism of these materials in moisture is a critical step towards the final appropriate solutions. As a model study presented in this work, in situ synchrotron radiation x-ray diffraction was combined with microscopy and gravimetric analysis to study the degradation process of CH3NH3PbI3 in moisture, and the results reveal that: 1) intermediate monohydrated CH3NH3PbI3·H2O is detected in the degradation process of CH3NH3PbI3 and the final decomposition products are PbI2 and aqueous CH3NH3I; 2) the aqueous CH3NH3I could hardly further decompose into volatile CH3NH2, HI or I2; 3) the moisture disintegrate CH3NH3PbI3 and then alter the distribution of the decomposition products, which leads to an incompletely-reversible reaction of CH3NH3PbI3 hydrolysis and degrades the photoelectric properties. These findings further elucidate the picture of hydrolysis process of perovskite organometallic halide in humidity environment.

  18. Borate complexes of x-ray iodinated contrast agents: characterization and sorption studies for their removal from aqueous media.

    Science.gov (United States)

    Rustighi, Isabella; Donati, Ivan; Ferluga, Matteo; Campa, Cristiana; Pasqua, Adele E; Rossi, Marco; Paoletti, Sergio

    2012-02-29

    Iodinated contrast media (ICM) are persistent and ubiquitous water pollutants. Because of their high water solubility and biochemical stability, their phase-separation and recovery from the aquatic environment is very difficult. Here, borate was chosen as a complexing agent of the two diagnostic aids iomeprol and iopamidol in order to provide them with a negative charge and to fix the resulting adducts on Dowex 1X4 ion exchangers. A systematic characterization study of the complex by means of capillary zone electrophoresis and 11B NMR revealed that iomeprol and iopamidol interact with borate anions in aqueous solutions giving a 1:1 single-charged adduct and that the association constant at 25 °C for both contrast agents is highest at pH 10.5. These findings allowed the proper calibration of experimental parameters for further batch adsorption-desorption trials, where the two ICM were shown to be almost completely removed from the water phase and released from the solid sorbents in mild conditions, enabling the recovery of functional resin. PMID:22245510

  19. Optimization of the Parameters Affecting the Fenton Process for Decolorization of Reactive Red 198 (RR-198 from the Aqueous Phase

    Directory of Open Access Journals (Sweden)

    Mansooreh Dehghani

    2015-10-01

    Full Text Available Background: Recently, there has been a great concern about the consumption of dyes because of their toxicity, mutagenicity, carcinogenicity, and persistence in the aquatic environment. Reactive dyes are widely used in textile industry. Advanced oxidation processes are one of the cost-effective methods for the removal of these dyes. The main aims of this study were determining the feasibility of using Fenton process in removing Reactive Red 198 (RR-198 dye from aqueous solution and determining the optimal conditions. Methods: This is a cross-sectional study conducted at a laboratory scale. A total of 69 samples were considered and the effect of pH, Fe (II concentration, H2O2 concentration, initial dye concentration and reaction time were investigated. Results: According to the results, a maximum removal efficiency of 92% was obtained at pH of 3 and the reaction time of 90 min; also, the concentration of Fe (II, H2O2, initial dye concentration were 100 mg/L, 50 mg/L, and 100 mg/L, respectively. The results revealed that by increasing the concentration of Fe (II, H2O2 and initial dye, the removal efficiency was increased. Conclusions: The results showed that Fenton process could be used as a cost-effective method for removing RR-198 dye from textile wastewater efficiently.

  20. Reconstructing the aqueous history within the southwestern Melas basin, Mars: Clues from stratigraphic and morphometric analyses of fans

    Science.gov (United States)

    Williams, Rebecca M. E.; Weitz, Catherine M.

    2014-11-01

    New details of the aqueous history in the southwestern Melas Chasma elevated basin have been revealed from analysis of high-resolution image, topographic and spectral datasets. We have identified eleven fan-shaped landforms that reflect various depositional environments. A distinctive marker bed with inferred indurated aeolian bedforms is within the stratigraphic record of presumed lacustrine deposits. This observation, taken together with the stratigraphic succession of fan-shaped deposits indicates fluctuating lake levels with, at a minimum, early and late-stage lake highstands. Tributary drainage pattern in the western valley network changed from a dendritic to a meandering system, recording a shift in fluvial activity that is consistent with fluctuating lake levels. Only a few hydrated minerals have been detected in the study region, the most common being opal which appears to represent younger alteration and deposition within the basin. Landform scale was used to estimate average discharge (∼30 m3/s), formative discharge (200-300 m3/s), and fan formation timescale, which further inform the duration of lacustrine activity within the basin. Warm surface conditions and precipitation recharge of source basins is required to generate and sustain this long-lived lake over periods of at least centuries to millennia during the Late Hesperian to Early Amazonian.

  1. Evaluation of wound healing properties of bioactive aqueous fraction from Moringa oleifera Lam on experimentally induced diabetic animal model

    Science.gov (United States)

    Muhammad, Abubakar Amali; Arulselvan, Palanisamy; Cheah, Pike See; Abas, Farida; Fakurazi, Sharida

    2016-01-01

    Diabetic foot ulcer is a serious complication of diabetes, which affects a significant percentage (15%) of diabetics and up to 15%–24% of those affected may require amputation. Therefore, the economic burden of diabetic foot ulcers is enormous and is associated with high cost of treatment and prolongs hospitalization. The present study was conducted to evaluate antibacterial and in vivo wound healing activities of an aqueous fraction of Moringa oleifera on a diabetic condition. Antibacterial activity testing was carried out using agar well and tube dilution techniques. The in vivo study was conducted using six groups of animals that comprise of one normal and diabetic control group each, three treatment groups of 0.5%, 1%, and 2% w/w aqueous fraction, and a positive control group (1% w/w silver sulfadiazine). Rats were induced with diabetes using a combination of streptozotocin 65 and 150 mg/kg nicotinamide daily for 2 days, and excision wounds were created and treated with various doses (0.5%, 1%, and 2% w/w aqueous fraction) daily for 21 days. Biophysical, histological, and biochemical parameters were investigated. The results of the study revealed that aqueous fraction possessed antibacterial activity through inhibition of growth of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli organisms. The topical application of aqueous fraction revealed enhancement of wound healing under sustained hyperglycemic condition for the duration of the experiment. This enhancement was achieved through decreased wound size, improved wound contraction, and tissue regeneration, as well as downregulation of inflammatory mediators, such as tumor necrosis factor-α, interleukin-1β, interleukin-6, inducible nitric oxide synthase, and cyclooxygenase-2, and upregulation of an angiogenic marker vascular endothelial growth factor in wound tissue treated with various doses of aqueous fraction of M. oleifera. The findings suggest that aqueous fraction of M. oleifera

  2. Evaluation of wound healing properties of bioactive aqueous fraction from Moringa oleifera Lam on experimentally induced diabetic animal model.

    Science.gov (United States)

    Muhammad, Abubakar Amali; Arulselvan, Palanisamy; Cheah, Pike See; Abas, Farida; Fakurazi, Sharida

    2016-01-01

    Diabetic foot ulcer is a serious complication of diabetes, which affects a significant percentage (15%) of diabetics and up to 15%-24% of those affected may require amputation. Therefore, the economic burden of diabetic foot ulcers is enormous and is associated with high cost of treatment and prolongs hospitalization. The present study was conducted to evaluate antibacterial and in vivo wound healing activities of an aqueous fraction of Moringa oleifera on a diabetic condition. Antibacterial activity testing was carried out using agar well and tube dilution techniques. The in vivo study was conducted using six groups of animals that comprise of one normal and diabetic control group each, three treatment groups of 0.5%, 1%, and 2% w/w aqueous fraction, and a positive control group (1% w/w silver sulfadiazine). Rats were induced with diabetes using a combination of streptozotocin 65 and 150 mg/kg nicotinamide daily for 2 days, and excision wounds were created and treated with various doses (0.5%, 1%, and 2% w/w aqueous fraction) daily for 21 days. Biophysical, histological, and biochemical parameters were investigated. The results of the study revealed that aqueous fraction possessed antibacterial activity through inhibition of growth of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli organisms. The topical application of aqueous fraction revealed enhancement of wound healing under sustained hyperglycemic condition for the duration of the experiment. This enhancement was achieved through decreased wound size, improved wound contraction, and tissue regeneration, as well as downregulation of inflammatory mediators, such as tumor necrosis factor-α, interleukin-1β, interleukin-6, inducible nitric oxide synthase, and cyclooxygenase-2, and upregulation of an angiogenic marker vascular endothelial growth factor in wound tissue treated with various doses of aqueous fraction of M. oleifera. The findings suggest that aqueous fraction of M. oleifera

  3. Android Emotions Revealed

    DEFF Research Database (Denmark)

    Vlachos, Evgenios; Schärfe, Henrik

    2012-01-01

    This work presents a method for designing facial interfaces for sociable android robots with respect to the fundamental rules of human affect expression. Extending the work of Paul Ekman towards a robotic direction, we follow the judgment-based approach for evaluating facial expressions to test in...... which case an android robot like the Geminoid|DK –a duplicate of an Original person- reveals emotions convincingly; when following an empirical perspective, or when following a theoretical one. The methodology includes the processes of acquiring the empirical data, and gathering feedback on them. Our...... findings are based on the results derived from a number of judgments, and suggest that before programming the facial expressions of a Geminoid, the Original should pass through the proposed procedure. According to our recommendations, the facial expressions of an android should be tested by judges, even in...

  4. Revealing Cosmic Rotation

    CERN Document Server

    Yadav, Amit P S; Keating, Brian G

    2012-01-01

    Cosmological Birefringence (CB), a rotation of the polarization plane of radiation coming to us from distant astrophysical sources, may reveal parity violation in either the electromagnetic or gravitational sectors of the fundamental interactions in nature. Until only recently this phenomenon could be probed with only radio observations or observations at UV wavelengths. Recently, there is a substantial effort to constrain such non-standard models using observations of the rotation of the polarization plane of cosmic microwave background (CMB) radiation. This can be done via measurements of the $B$-modes of the CMB or by measuring its TB and EB correlations which vanish in the standard model. In this paper we show that $EB$ correlations-based estimator is the best for upcoming polarization experiments. The $EB$ based estimator surpasses other estimators because it has the smallest noise and of all the estimators is least affected by systematics. Current polarimeters are optimized for the detection of $B$-mode...

  5. Aqueous phase chemical properties of transactinides

    International Nuclear Information System (INIS)

    65-s 261Rf and 34-s 262Ha have been produced at the Lawrence Berkeley Laboratory 88-Inch Cyclotron by the 248Cm(18O,5n) and 249Bk(18O,5n) reactions, respectively. These isotopes of element 104 and 105 are produced at a one atom per minute rate, and rapid chemical separations are performed on a one-minute time scale. They are identified by detecting the α- and SF radiations from their decay. First aqueous phase chemical separations of Rf and Ha determined their primary oxidation states in aqueous solution, placing them in the periodic table at the bottom of groups 4 and 5, respectively, and confirming Seaborg's actinide concept. More recently, experiments measuring the chemical properties in more detail have uncovered some interesting and unexpected trends in periodic table properties

  6. Uranyl fluoride luminescence in acidic aqueous solutions

    International Nuclear Information System (INIS)

    Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 ± 0.006 ms, was observed from uranyl in 1 M HF + 1 M HClO4 at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to UO2F2. Studies on the effect of added LiNO3 or Na2WO4·2H2O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF6 content of WF6 gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF6

  7. Zeolites as alcohol adsorbents from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Cekova Blagica

    2006-01-01

    Full Text Available The potential usage of zeolites as adsorbents for the removal of organic molecules from water was investigated in a series of experiments with aqueous solutions of lower alcohols. This could represent a simple solution to the problem of cleaning up industrial wastewater as well as recovering valuable chemicals at relatively low costs. Adsorption isotherms of the Langmuir type were applied, and calculations showed that the amount of propanol adsorbed on silicalite corresponded to approximately 70% of the pore volume. The adsorption process is simple, and recovery of the more concentrated products is easily done by heat treatment and/or at lowered pressures. Adsorption experiments with aqueous acetone showed that silicalite had approximately the same adsorption capacity for acetone as for n-propanol. Heats of adsorption were determined calorimetrically.

  8. Enzymatic Aqueous Extraction of Soybean Oil

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The procedure of enzymatic aqueous extraction of soybean oil was assessed when two-step controlled enzymatic hydrolysis was applied. With aqueous extraction of soybean oil-containing protein, the highest yield of oil was 96.1% at the optimized conditions studied. Soybean oil-containing protein was hydrolyzed and resulted in releasing part of oil. The separated protein that contained 40% oil was enriched due to its adsorption capacity of released oil, the average oil extraction yeild reached 93.5%. Then the high oil content protein was hydrolyzed again to release oil by enzyme, the oil extraction yeild was 80.4%. As a result, high quality of soybean oil was obtained and the content of total oil yield was 74.4%.

  9. Monitoring dynamics of aqueous humor in glaucoma

    International Nuclear Information System (INIS)

    Aqueous humor dynamics was observed in patients treated for glaucoma. Aqueous flow was measured using the radionuclide method of contact application of 22NaCl and the detection of gamma radiation with external detectors. The sample of 184 eyes was divided into three groups: open-angle glaucoma with therapy, open-angle glaucoma without therapy and angle-closure glaucoma 47 eyes were used as controls. Changes were observed in 22Na outflow half-time in dependence on the duration of the disease, therapy, intraocular pressUre and changes in the perimeter. The new technique has been fully proven in practice, is a contribution to the diagnosis of glaucoma and an indicator of the compensation of the disease. (author)

  10. Desalination of aqueous solutions by LTA and MFI zeolite membranes using pervaporation method

    Directory of Open Access Journals (Sweden)

    A. Malekpour

    2011-12-01

    Full Text Available LTA and MFI zeolite membranes were hydrothermally grown on the surface of an α-alumina porous support. The synthesized membranes were used for removal of cationic and anionic species from aqueous solutions by the pervaporation method. The perfection of the membranes was improved by employing the multi-stage synthesis method. The membranes were characterized by XRD, SEM and IR methods. The membranes were initially evaluated by the pervaporation separation of water from aqueous 2-propanol mixtures. The separation factors obtained were 7081 and 105 for NaA and ZSM-5 membranes, respectively. The ability of membranes for desalination of some aqueous solutions containing I-, Cs+ and Sr2+ ions was examined in various conditions. These ionic species were chosen because of their importance in the nuclear sciences. Both membranes effectively removed (more than 99 wt% I-, Cs+ and Sr2+ from their singlesalt solutions (0.001mol dm-3 over a temperature range of 298-338 K. The effects of parameters such as time and temperature on the separation factors and fluxes were investigated. This work shows that, due to their excellent chemical, thermal and mechanical stability, the zeolitic membranes are useful for desalination of aqueous solutions and treating saline wastewaters by pervaporation. Therefore, this method has the ability to desalinate harsh environment solutions involving strong solvent and radioactive components.

  11. Degradation/oxidation susceptibility of organic photovoltaic cells in aqueous solutions

    Science.gov (United States)

    Habib, K.; Husain, A.; Al-Hazza, A.

    2015-12-01

    A criterion of the degradation/oxidation susceptibility of organic photovoltaic (OPV) cells in aqueous solutions was proposed for the first time. The criterion was derived based on calculating the limit of the ratio value of the polarization resistance of an OPV cell in aqueous solution (Rps) to the polarization resistance of the OPV cell in air (Rpair). In other words, the criterion lim(Rps/Rpair) = 1 was applied to determine the degradation/oxidation of the OPV cell in the aqueous solution when Rpair became equal (increased) to Rps as a function of time of the exposure of the OPV cell to the aqueous solution. This criterion was not only used to determine the degradation/oxidation of different OPV cells in a simulated operational environment but also it was used to determine the electrochemical behavior of OPV cells in deionized water and a polluted water with fine particles of sand. The values of Rps were determined by the electrochemical impedance spectroscopy at low frequency. In addition, the criterion can be applied under diverse test conditions with a predetermined period of OPV operations.

  12. Solar Absorption by Aerosol-Bound Nitrophenols Compared to Aqueous and Gaseous Nitrophenols.

    Science.gov (United States)

    Hinrichs, Ryan Z; Buczek, Pawel; Trivedi, Jal J

    2016-06-01

    Nitrophenols are well-known absorbers of near-UV/blue radiation and are considered to be a component of solar-absorbing organic aerosol material commonly labeled brown carbon. Nitrophenols have been identified in a variety of phases in earth's atmosphere, including the gaseous, aqueous, and aerosol bound, and these different environments alter their UV-vis absorption spectra, most dramatically when deprotonated forming nitrophenolates. We quantify the impact of these different absorption profiles by calculating the solar power absorbed per molecule for several nitrophenols. For instance, aqueous 2,4-dinitrophenol absorption varies dramatically over the pH range of cloud droplets with pH = 5.5 solutions absorbing three times the solar power compared to pH = 3.5 solutions. We also measured the UV-vis spectra of 2-nitrophenol adsorbed on several aerosol substrates representative of mineral dust, inorganic salts, and organic aerosol and compare these spectra to gaseous and aqueous 2-nitrophenol. 2-Nitrophenol adsorbed on mineral and chloride aerosol substrates exhibits a red-shifted absorption band (∼450-650 nm) consistent with 2-nitrophenolate and absorbs twice the solar power per molecule compared to gaseous, aqueous, and organic aerosol-bound 2-nitrophenol. We also discuss how different nitrophenol absorption profiles alter important atmospheric photolysis rate constants [e.g., J(NO2) and J(O3)] by attenuating solar flux. PMID:27176618

  13. Bacterial Acclimation Inside an Aqueous Battery

    OpenAIRE

    Dong, Dexian; Chen, Baoling; Chen, P

    2015-01-01

    Specific environmental stresses may lead to induced genomic instability in bacteria, generating beneficial mutants and potentially accelerating the breeding of industrial microorganisms. The environmental stresses inside the aqueous battery may be derived from such conditions as ion shuttle, pH gradient, free radical reaction and electric field. In most industrial and medical applications, electric fields and direct currents are used to kill bacteria and yeast. However, the present study focu...

  14. Does Dimeric Melittin Occur in Aqueous Solutions?

    OpenAIRE

    Schubert, D; Pappert, G.; Boss, K.

    1985-01-01

    Melittin, a peptide from bee venom, is known to undergo a monomer / tetramer conversion in aqueous solutions. We have studied the possible participation of dimers in the association equilibrium of melittin by sedimentation equilibrium experiments in the analytical ultracentrifuge and subsequent mathematical analysis of the concentration distributions obtained. It was found that the dimeric state is not significantly populated, the contribution of dimer to the total peptide weight probably bei...

  15. Aqueous solution dispersement of carbon nanotubes

    Science.gov (United States)

    Kim, Jae-Woo (Inventor); Park, Cheol (Inventor); Choi, Sang H. (Inventor); Lillehei, Peter T. (Inventor); Harrison, Joycelyn S. (Inventor)

    2011-01-01

    Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group.

  16. Aqueous Electrolytes: Model Parameters and Process Simulation

    DEFF Research Database (Denmark)

    Thomsen, Kaj

    This thesis deals with aqueous electrolyte mixtures. The Extended UNIQUAC model is being used to describe the excess Gibbs energy of such solutions. Extended UNIQUAC parameters for the twelve ions Na+, K+, NH4+, H+, Cl-, NO3-, SO42-, HSO4-, OH-, CO32-, HCO3-, and S2O82- are estimated. A computer ...... program including a steady state process simulator for the design, simulation, and optimization of fractional crystallization processes is presented....

  17. Photolysis of imidacloprid in aqueous solution

    International Nuclear Information System (INIS)

    The photolysis of the insecticide imidacloprid in aqueous solution has been examined. Irradiation at 290 nm resulted in 90 % substrate transformation in 4 h. The degradation approximately followed first order kinetics; the rate constant is 1.6 × 10−4s−1 and half-life 1.2 h. 6-Chloronicotinaldehyde, N-methylnicotinacidamide, 1-(6-chloronicotinyl)imidazolidone and 6-chloro-3-pyridyl-methylethylendiamine were the main photoproducts identified by CG-MS analysis. (author)

  18. 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 ...

  19. Characterization of Aqueous Peroxomolybdates with Catalytic Applicability

    OpenAIRE

    Taube, Fabian

    2003-01-01

    Abstract This thesis is a summary of five papers, containing equilibrium and structure studies of aqueous molybdate and peroxomolybdate species. Some of the peroxomolybdate species have also been studied in terms of their dynamic and catalytic properties. The primary objective was to characterize species with potential catalytic activity, with emphasis on thebleach process of kraft pulp. For this, potentiometry, EXAFS and 17O, 31P, 1H and 95 Mo NMR have been used. The molybdate speciation in ...

  20. Aqueous Pu(IV) sorption on brucite

    International Nuclear Information System (INIS)

    The sorption behavior of aqueous Pu(IV) on brucite (Mg(OH)2) in the presence and absence of citrate was investigated by a combination of wet chemical batch sorption experiments and X-ray photoelectron spectroscopy (XPS). Sorption occurs rapidly at near 100% levels from pH 8 to pH 13, and is not affected by the presence of citrate. XPS results indicate that Pu was incorporated in the subsurface in the cases studied. (orig.)

  1. AQUEOUS STABLE FREE RADICAL POLYMERIZATION PROCESSES

    Institute of Scientific and Technical Information of China (English)

    Andrea R. Szkurhan; Michael K. Georges

    2004-01-01

    An overview of aqueous polymerizations, which include emulsion, miniemulsion and suspension polymerizations,under stable free radical polymerization (SFRP) conditions is presented. The success of miniemulsion and suspension SFRP polymerizations is contrasted with the difficulties associated with obtaining a stable emulsion polymerization. A recently developed unique microprecipitation technique is referenced as a means of making submicron sized particles that can be used to achieve a stable emulsion SFRP process.

  2. Simple Molecular Models of Aqueous Solutions

    Czech Academy of Sciences Publication Activity Database

    Jirsák, Jan; Škvor, J.; Nezbeda, Ivo

    - : -, 2013. ISBN N. [EMLG - JMLG Annual Meeting 2013 Global Perspectives in the Structure and Dynamics in Liquids and Mixtures: Experiment and Simulation. Lille (FR), 09.09.2013-13.09.2013] Grant ostatní: GA ČR(CZ) GPP208/12/P710 Institutional support: RVO:67985858 Keywords : aqueous solutions * thermodynamic modeling * simulation data Subject RIV: CF - Physical ; Theoretical Chemistry http://emlg2013.univ-lille1.fr/

  3. Recent results on aqueous electrolyte cells

    KAUST Repository

    Wessells, Colin

    2011-03-01

    The improved safety of aqueous electrolytes makes aqueous lithium-ion batteries an attractive alternative to commercial cells utilizing flammable and expensive organic electrolytes. Two important issues relating to their use have been addressed in this work. One is the extension of the usable voltage range by the incorporation of lithium salts, and the other is the investigation of a useful negative electrode reactant, LiTi 2(PO 4) 3. The electrochemical stability of aqueous lithium salt solutions containing two lithium salts, LiNO 3 and Li 2SO 4, has been characterized using a constant current technique. In both cases, concentrated solutions had effective electrolyte stability windows substantially greater than that of pure water under standard conditions. At an electrolyte leakage current of 10 μA cm -2 between two platinum electrodes in 5 M LiNO 3 the cell voltage can reach 2.0 V, whereas with a leakage current of 50 μA cm -2 it can reach 2.3 V. LiTi 2(PO 4) 3 was synthesized using a Pechini method and cycled in pH-neutral Li 2SO 4. At a reaction potential near the lower limit of electrolyte stability, an initial discharge capacity of 118 mAh g -1 was measured at a C/5 rate, while about 90% of this discharge capacity was retained after 100 cycles. This work demonstrates that it is possible to have useful aqueous electrolyte lithium-ion batteries using the LiTi 2(PO 4) 3 anode with cell voltages of 2 V and above. © 2010 Elsevier B.V. All rights reserved.

  4. Continuous environmental monitoring for aqueous effluents

    Energy Technology Data Exchange (ETDEWEB)

    Pitt, Jr., W. W.; Jones, G. Jr.

    1980-05-01

    An aquatic environmental monitor has been developed that will continuously monitor aqueous waste streams from coal processing plants. The monitor contains three different instruments: a continuous chemical oxygen demand monitor and two continuous-flow fluorometers with different excitation-emission characteristics. A prototype instrument was fabricated and evaluated for several different applications. The details of the instrument design and results of its evaluation are presented in this report.

  5. SEPARATION OF SCANDIUM FROM AQUEOUS SOLUTIONS

    Science.gov (United States)

    Peppard, D.F.; Nachtman, E.S.

    1958-02-25

    This patent relates to a process for the separation of scandium from yttrium, thorium, and trivalent rare earths and with their separation from each other. It has been found that scandium and yttrium can be separated from trivalent rare earths in acidic solution, for example, a solution 6 M in HCl, by contacting with tributyl phosphate, whereupon the scandum is preferentially extracted into the organic phase, leaving the yttrium and trivalent rare earths in the aqueous phase.

  6. Study of aqueous solutions of sodium linoleate

    Energy Technology Data Exchange (ETDEWEB)

    Van der Linde, G.J. (Phosphate Development Corporation, Phalaborwa); Van Berge, P.C. (Rand Afrikaans Univ., Johannesburg (South Africa))

    1983-12-01

    During the development of a technique for measuring fatty acid absorption on finely divided minerals using a radiochemical method, absorption isotherms were obtained which displayed maxima. It was found that these results were due to the presence of stable micelles in the solutions. This has been established by measuring the surface tension, surface film pressure, and specific conductance of dilute aqueous solutions of sodium linoleate.

  7. Aqueous Processing of WC-Co Powders

    OpenAIRE

    Andersson, Karin M.

    2004-01-01

    The object of this work is to obtain a fundamentalunderstanding of the principal issues concerning the handlingof an aqueous WC-Co powder suspension. The WO3 surface layer on the oxidised tungsten carbidepowder dissolves at pH>3 with the tungsten concentrationincreasing linearly with time. Adding cobalt powder to thetungsten carbide suspension resulted in a significant reductionof the dissolution rate at pH<10. Electrokinetic studiesindicated that the reduced dissolution rate may be rel...

  8. Chemiluminogenic properties of 10-methyl-9-(phenoxycarbonyl)acridinium cations in organic environments.

    Science.gov (United States)

    Krzymiński, Karol; Roshal, Alexander D; Zadykowicz, Beata; Białk-Bielińska, Anna; Sieradzan, Andrzej

    2010-10-01

    The chemiluminogenic (CL) properties of aryl esters of 9-carboxy-10-methylacridinium acid and 9-carboxy-2-methoxy-10-methylacridinium acid (AE), variously substituted in the benzene ring (2-H, 2-CH(3), 2-Cl) were investigated in aliphatic alcohols, acetonitrile, and dimethyl sulfoxide in the presence of hydrogen peroxide and different bases-potassium hydroxide, tetra-n-butylammonium hydroxide, and 1,8-diazabicyclo[5.4.0]undec-7-ene. The dependence of their CL properties (decay rate constants (k(CL)) and relative efficiencies (RE)) on solvent parameters, the nature and concentration of base, as well as H(2)O(2) concentration were investigated. Comparison of the various AE revealed that substituents at the benzene ring strongly influence the reaction kinetics, while 2-OCH(3) substitution of the acridine nucleus is manifested, in general, by a red shift in the emission spectrum and slight increase in CL efficiency. The values of k(CL) depend linearly on polarity and acid-base properties of solvents as well as on concentration of bases (over certain concentration ranges) and demonstrate a nonlinear dependence on H(2)O(2) concentration. RE values depend on solvent polarity and nucleophilicity but are rather weakly dependent on base and oxidant concentrations. The CL properties of the above systems are discussed in the context of their physicochemical features gained from fluorescence spectroscopy, spectrophotometric titration, MS, and HPLC. Electronically excited 10-methyl-9-acridinones are the light-emitting entities in both organic and aqueous environments. It was also found that the tendency for an unwanted side-process, the production of a pseudobase form of AE, to take place was similar in alcoholic and aqueous media, although 2-methoxy ring-substituted derivatives seemed to be less susceptible to this dark-type conversion. On the basis of these results new CL systems are postulated that are more efficient than their aqueous counterparts. PMID:20831163

  9. Density of aqueous solutions of CO2

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Julio E.

    2001-10-10

    In this report, we present a numerical representation for the partial molar volume of CO2 in water and the calculation of the corresponding aqueous solution density. The motivation behind this work is related to the importance of having accurate representations for aqueous phase properties in the numerical simulation of carbon dioxide disposal into aquifers as well as in geothermal applications. According to reported experimental data the density of aqueous solutions of CO2 can be as much as 2-3% higher than pure water density. This density variation might produce an influence on the groundwater flow regime. For instance, in geologic sequestration of CO2, convective transport mixing might occur when, several years after injection of carbon dioxide has stopped, the CO2-rich gas phase is concentrated at the top of the formation, just below an overlaying caprock. In this particular case the heavier CO2 saturated water will flow downward and will be replaced by water with a lesser CO2 content.

  10. Spectroscopic studies of solutes in aqueous solution.

    Science.gov (United States)

    Chai, Bing-hua; Zheng, Jian-ming; Zhao, Qing; Pollack, Gerald H

    2008-03-20

    Absorption and fluorescence characteristics of aqueous solutions of salts, sugars, and amino acids were studied using UV-vis spectroscopy and spectrofluorometry. Motivation stemmed from unanticipated absorption spectral and fluorescence features of the "exclusion zone" seen adjacent to various hydrophilic surfaces. Those features implied a structure distinct from that of bulk water (Adv. Colloid Interface Sci. 2006, 127, 19). Absorption peaks at approximately 270 nm similar to those observed in the exclusion zone were seen in solutions of the following substances: salts, Nafion 117 solution/film, l-lysine, d-alanine, d-glucose and sucrose. To determine the fate of the absorbed energy, we studied the fluorescence properties of these solutions. The salts showed fluorescence emission around 480-490 nm under different excitation wavelengths. The fluorescence intensity of LiCl was higher than NaCl, which was in turn higher than KCl-the same ordering as the absorption intensities. Fluorescence of Nafion 117 solution/film, l-lysine, d-alanine, d-glucose and sucrose were observed as well, with multiple excitation wavelengths. Hence, at least some of the absorbed energy is released as fluorescence. The results show features closely similar to those observed in the exclusion zone, implying that the aqueous region around the solutes resembles the aqueous zone adjacent to hydrophilic surfaces. Both may be more extensively ordered than previously thought. PMID:18298105

  11. Photolysis of oxyfluorfen in aqueous methanol.

    Science.gov (United States)

    Chakraborty, Subhasish K; Chakraborty, Savitri; Bhattacharyya, Anjan; Chowdhury, Ashim

    2013-01-01

    Photolysis of oxyfluorfen, an herbicide of the nitrodiphenyl ether class, was studied in aqueous methanol under UV and sunlight. UV irradiation was carried out in a borosilicate glass photoreactor (containing 250 ppm oxyfluorfen in 50% aqueous methanol) equipped with a quartz filter and 125 watt mercury lamp (maximum output 254 nm) at 25 ± 1°C. Sunlight irradiation was conducted at 28 ± 1°C in borosilicate Erlenmeyer flasks containing 250 ppm oxyfluorfen in 50% aqueous methanol. The samples from both the irradiated conditions were withdrawn at a definite time interval and extracted to measure oxyfluorfen content by gas chromatography-flame ionization detector for rate study. The half-life values were 20 hours and 2.7 days under UV and sunlight exposure, respectively. Photolysis of oxyfluorfen yielded 13 photoproducts of which three were characterized by infrared spectrophotometer and (1)H NMR and (13)C NMR spectroscopy. The rest of the photoproducts were identified by gas chromatography-mass spectrometry (GC-MS) and thin layer chromatography (TLC). An ionization potential 70 eV was used for electron impact-mass spectrometry (EI-MS) and methane was used as reagent gas for chemical ionization-mass spectrometry (CI-MS). Two of the photoproducts were also synthesized for comparison. The main phototransformation pathways of oxyfluorfen involved nitro reduction, dechlorination, and hydrolysis as well as nucleophiles displacement reaction. PMID:23998303

  12. Bacterial Acclimation Inside an Aqueous Battery.

    Directory of Open Access Journals (Sweden)

    Dexian Dong

    Full Text Available Specific environmental stresses may lead to induced genomic instability in bacteria, generating beneficial mutants and potentially accelerating the breeding of industrial microorganisms. The environmental stresses inside the aqueous battery may be derived from such conditions as ion shuttle, pH gradient, free radical reaction and electric field. In most industrial and medical applications, electric fields and direct currents are used to kill bacteria and yeast. However, the present study focused on increasing bacterial survival inside an operating battery. Using a bacterial acclimation strategy, both Escherichia coli and Bacillus subtilis were acclimated for 10 battery operation cycles and survived in the battery for over 3 days. The acclimated bacteria changed in cell shape, growth rate and colony color. Further analysis indicated that electrolyte concentration could be one of the major factors determining bacterial survival inside an aqueous battery. The acclimation process significantly improved the viability of both bacteria E. coli and B. subtilis. The viability of acclimated strains was not affected under battery cycle conditions of 0.18-0.80 mA cm(-2 and 1.4-2.1 V. Bacterial addition within 1.0×10(10 cells mL(-1 did not significantly affect battery performance. Because the environmental stress inside the aqueous battery is specific, the use of this battery acclimation strategy may be of great potential for the breeding of industrial microorganisms.

  13. A simple aqueous electrochemical method to synthesize TiO₂ nanoparticles.

    Science.gov (United States)

    Bezares, Ivan; del Campo, Adolfo; Herrasti, Pilar; Muñoz-Bonilla, Alexandra

    2015-11-21

    Here, a simple and rapid electrochemical approach to synthesize TiO2 nanoparticles in aqueous solution is reported. This method consists in the electro-oxidation of titanium foil in a tetrabutylammonium bromide aqueous solution, which acts as both an electrolyte and a surfactant. Amorphous TiO2 particles in the nanoscale (∼5 nm), well dispersed in aqueous solution, were directly formed by applying low current densities in a short reaction time. It was demonstrated that several experimental parameters influence the reaction yield; an increase in the current, temperature and reaction time augments the quantity of the obtained material. Then, the amorphous nanoparticles were completely crystallized into a pure anatase phase by thermal treatment under an air atmosphere as analyzed by X-ray diffraction and Raman spectroscopy. Besides, the size of the nanoparticles increased to approximately 12 nm in the calcination process. The band gap energies of the resulting TiO2 anatase nanoparticles were determined by diffuse reflectance measurements according to the Kubelka Munk theory, revealing low values between 2.95 and 3.10 eV. Therefore, the results indicate the success of this method to create TiO2 nanoparticles in aqueous medium with good optical properties. PMID:26469391

  14. Influence of emulsion nature on radiation response of β-carotene in an aqueous medium

    International Nuclear Information System (INIS)

    The radiation response of β-carotene was followed in lipid solvents and in aqueous preparations. The nature of the solvent was found to have a marked influence on the response of β-carotene to γ-radiation. In aqueous emulsions radiation destruction of β-carotene was far less than that observed in solutions. Oil in water (O/W) emulsions of petroleum ether offered maximum protection to β-carotene against radiation damage. This observation was attributed to the multiphase nature of the emulsion since a transparent aqueous preparation was observed to offer no protection upon irradiation. Solubility of crystalline β-carotene in water was found to increase with the emulsifier concentration. Irradiation revealed that the extent of β-carotene destruction was dose dependent and increased with the solubility of β-carotene in water. In the presence of a free radical scavenger DPPH β-carotene exhibited varied radiation response depending upon the nature of solvents used. Thus, in transparent aqueous preparations the protection afforded by added DPPH to β-carotene was almost complete, while its influence was insignificant in O/W emulsions. The significance of these observations in radiation processing of foods is discussed. (author)

  15. Influence of Emulsion Nature on Radiation Response of β-Carotene in an Aqueous Medium

    International Nuclear Information System (INIS)

    The radiation response of β-carotene was followed in lipid solvents and in aqueous preparations. The nature of the solvent was found to have a marked influence on the response of β-carotene to γ -radiation. In aqueous emulsions radiation destruction of β-carotene was far less than that observed in solutions. Oil in water (O/W) emulsions of petroleum ether offered maximum protection to β-carotene against radiation damage. This observation was attributed to the multiphase nature of the emulsion since a transparent aqueous preparation was observed to offer no protection upon irradiation. Solubility of crystalline β-carotene in water was found to increase with the emulsifier concentration. Irradiation revealed that the extent of β-carotene destruction was dose dependent and increased with the solubility of β-carotene in water. In the presence of a free radical scavenger DPPH β-carotene exhibited varied radiation response depending upon the nature of solvents used. Thus, in transparent aqueous preparations the protection afforded by added DPPH to β-carotene was almost complete, while its influence was insignificant in O/W emulsions. The significance of these observations in radiation processing of foods is discussed. (author)

  16. AQUEOUS BIPHASE EXTRACTION FOR PROCESSING OF FINE COAL

    Energy Technology Data Exchange (ETDEWEB)

    K. Osseo-Asare; X. Zeng

    2002-01-01

    The objective of this research project is to develop an aqueous biphase extraction process for the treatment of fine coals. Aqueous biphase extraction is an advanced separation technology that relies on the ability of an aqueous system consisting of a water-soluble polymer and another component, e.g., another polymer, an inorganic salt, or a nonionic surfactant, to separate into two immiscible aqueous phases. The principle behind the partition of solid particles in aqueous biphase systems is the physicochemical interaction between the solid surface and the surrounding liquid solution. In order to remove sulfur and mineral matter from fine coal with aqueous biphasic extraction, it is necessary to know the partitioning behavior of coal, as well as the inorganic mineral components. Therefore, in this research emphasis was placed on the partitioning behavior of fine coal particles as well as model fine inorganic particles in aqueous biphase systems.

  17. Bioligand-mediated partitioning of radionuclides to the aqueous phase

    International Nuclear Information System (INIS)

    The aqueous-phase partitioning of 59Fe, 147Pm, 234Th and 241Am by complexing compounds from subsurface bacteria has previously been studied in the presence of quartz sand. In this study the aqueous-phase partitioning of pico- to submicromolar amounts of 59Fe, 147Pm, 234Th and 241Am was analyzed in the presence of TiO2 and exudates from three species of subsurface bacteria: Pseudomonas fluorescens, Pseudomonas stutzeri, and Shewanella putrefaciens. All were grown under aerobic conditions and P. stutzeri and S. putrefaciens were grown under anaerobic conditions as well. The supernatants of the aerobic and anaerobic cultures were collected and radionuclide was added. TiO2, with BET surface area of 49.9 m2 x g-1, was added to the supernatant radionuclide mix, and the pH was adjusted to approximately 8. After incubation, the amount of radionuclide in the liquid phase of the samples and controls was analyzed using scintillation method. Two types of values were calculated: solution% = the activity maintained in solution relative to the total activity, and Q-values = the quotient between the activity in samples and the activity in controls. Aerobic supernatants had solution% values between 89% and 100% for 59Fe and between 18 and 43% for 234Th. The solution% values for 241Am and 147Pm were less than 2% overall, but the Q-values were between 34 and 115 times more 241Am in bacterial supernatants than in controls. The corresponding values for 147Pm ranged from 6 to 20 times more than in the control. The solution% values for all elements in the presence of anaerobic supernatants were below 2%, but the Q-values clustered around 7 for 59Fe and ranging from 2 to 29 for 234Th, indicated that anaerobic supernatants partitioned these elements to the aqueous phase. Both aerobic and anaerobic supernatants tested positive for complexing compounds when analyzed, using the Chrome Azurol S assay. Complexation with excreted organic ligands is most likely the reason for the higher amounts

  18. Bitumen immobilization of aqueous radwaste by thin-film evaporation

    International Nuclear Information System (INIS)

    In the early 1980s, AECL built a Waste Treatment Centre (WTC) for managing low-level solid and aqueous liquid wastes for converting CANDU wastes. At present, two liquid waste streams are being treated at the WTC. The liquid waste streams are volume-reduced by a combination of continuous crossflow microfiltration (MF), spiral wound reverse osmosis (SWRO) and tubular reverse osmosis (TRO) membrane technologies. The concentrate produced from the TRO system and the volume-reduced MF backwash solutions are evaporated while simultaneously adding bitumen in a thin-film evaporator. A water-free product of chemical and radiochemical salts and bitumen is removed in 200-L galvanized steel drums for storage. The radiation field of product drums on contact typically has a value of 0.5 to 3 R/h depending upon the feed concentration of radioactivity to the evaporator. The total solids content in the 200-L drum ranges from 25 to 35%. Encapsulated in the bitumen matrix are a variety of nonradiochemical salts, which comprise the bulk of the total solids that are in the product drum. This report discusses the immobilization of the aqueous waste with bitumen in a thin-film evaporator. Simulated bituminized waste forms were leached in accordance with the ANS/ANSI 16.1 leach test. In this test, the waste form is immersed under water for an extended period of time, and the leachate is periodically removed and chemically analysed. The Leachability index varied between 7 and 9 for the emulsified bitumen waste forms produced at the WTC. Bitumen samples were unconfined and subjected to immersion and frequent leachate replenishment. The results of leach tests will be a lower bound for the performance of the bitumen waste product in an unsaturated environment. The Leachability indexes reported exceeds the USNRC minimum requirement for wasteform criteria. Adding protective overcoats of either Portland cement or oxidized bitumen enhanced the Leachability index. 8 refs., 3 tabs., 6 figs

  19. High-conjugation-efficiency aqueous CdSe quantum dots.

    Science.gov (United States)

    Au, Giang H T; Shih, Wan Y; Shih, Wei-Heng

    2013-11-12

    Quantum dots (QDs) are photoluminescent nanoparticles that can be directly or indirectly coupled with a receptor such as an antibody to specifically image a target biomolecule such as an antigen. Recent studies have shown that QDs can be directly made at room temperature and in an aqueous environment (AQDs) with 3-mercaptopropionic acid (MPA) as the capping ligand without solvent and ligand exchange typically required by QDs made by the organic solvent routes (OQDs). In this study, we have synthesized CdSe AQDs and compared their conjugation efficiency and imaging efficacy with commercial carboxylated OQDs in HT29 colon cancer cells using a primary antibody-biotinylated secondary antibody-streptavidin (SA) sandwich. We showed that the best imaging condition for AQDs occurred when one AQD was bound with 3 ± 0.3 SA with a nominal SA/AQD ratio of 4 corresponding to an SA conjugation efficiency of 75 ± 7.5%. In comparison, for commercial CdSe-ZnS OQDs to achieve 2.7 ± 0.4 bound SAs per OQD for comparable imaging efficacy a nominal SA/OQD ratio of 80 was needed corresponding to an SA conjugation efficiency of 3.4 ± 0.5% for CdSe-ZnS OQDs. The more than 10 times better SA conjugation efficiency of the CdSe AQDs as compared to that of the CdSe-ZnS OQDs was attributed to more capping molecules on the AQD surface as a result of the direct aqueous synthesis. More capping molecules on the AQD surface also allowed the SA-AQD conjugate to be stable in cell culture medium for more than three days without losing their staining capability in a flowing cell culture medium. In contrast, SA-OQD conjugates aggregated in cell culture medium and in phosphate buffer saline solution over time. PMID:24151632

  20. Biosorption of strontium from aqueous solutions onto spent coffee grounds

    International Nuclear Information System (INIS)

    A set of experiments was carried out to evaluate the strontium uptake potential of spent coffee grounds (SCG) by batch tests in aqueous medium. Adsorption of Sr2+ as a function of contact time and adsorbent dose, pH, particles size, agitation speed, temperature and co-ions presence was investigated. Obtained results revealed that the maximum adsorption took place at pH range of 5-8 and temperature values between 283 and 333 K. Particles size effect was not very significant and agitation speed influenced on the equilibrium time. Competitive adsorption experiments allowed us to classify the negative effect on the Sr2+ uptake according to this order Al3+ ≫ Co2+ > Mg2+ > Ca2+ ≫ Na+ > K+ > Cs+. Kinetic study indicated that the Sr2+ uptake was fast and it was well fitted by the pseudo second order reaction model. Adsorption isotherm was well interpreted by Langmuir model. The maximum adsorption capacity was found to be 69.01 mg g−1 at pH 7, 293 K, particles sizes = 200-400 μm and agitation speed 250 rpm. The thermodynamic study revealed that the process was spontaneous (ΔG0 0 2+ (ΔG0 0 > 0) and occurred by physical adsorption (Ea = 8.37 kJ mol-1). FTIR analysis showed carboxylic acid and amino group presence on SCG surface playing a vital role in Sr2+ biosorption. (author)

  1. Photocatalytical oxidation of de-icing agents in aqueous solutions and aqueous extract of jet fuel.

    Science.gov (United States)

    Krichevskaya, M; Malygina, T; Preis, S; Kallas, J

    2001-01-01

    Improper handling of jet fuel at abandoned military bases has resulted in heavy pollution of the soil and groundwater. Experimental research of photocatalytical oxidation (PCO) of jet fuel aqueous extract and aqueous solutions of de-icing agents was undertaken. The influence of different parameters - pH, concentration of substances to be oxidised, presence of inorganic admixtures, effect of OH. radical generators--on the PCO of solutions of de-icing agents and jet fuel aqueous extract was determined. The role of OH. radicals was found to be less important in determining the PCO rate. The PCO of organic pollutants was also investigated using a catalyst immobilised onto the surface of buoyant hollow glass microspheres. Attached titanium dioxide (TiO2) showed lower photocatalytical activity than when suspended in slurry, although it allows waters to be treated in simple shallow ponds without intensive stirring. The biodegradability of aqueous solutions of de-icing agents and jet fuel aqueous extract increased as PCO proceeded. PMID:11695445

  2. Thermodynamics of dilute aqueous solutions of imidazolium based ionic liquids

    International Nuclear Information System (INIS)

    Research highlights: → The thermodynamic behaviour of aqueous imidazolium ILs has been investigated. → Volumetric and ultrasonic results indicated the hydrophobic hydration of ILs. → Viscometric studies revealed studied ionic liquids as water-structure makers. → Hydration number increased with increase in alkyl chain length of the cation. - Abstract: Experimental measurements of density ρ, speed of sound u, and viscosity η of aqueous solutions of various 1-alkyl-3-methylimidazolium based ionic liquid (IL) solutions have been performed in dilute concentration regime at 298.15 K to get insight into hydration behaviour of ILs. The investigated ILs are based on 1-alkyl-3-methylimidazolium cation, [Cnmim] having [BF4]-, [Cl]-, [C1OSO3]-, and [C8OSO3]- as anions where n = 4 or 8. Several thermodynamic parameters like apparent molar volume φV, isentropic compressibility βs, and viscosity B-coefficients have been derived from experimental data. Limiting value of apparent molar volume has been discussed in terms of intrinsic molar volume (Vint) molar electrostriction volume (Velec), molar disordered (Vdis), and cage volume (Vcage). Viscosity B-coefficients have been used to quantify the kosmotropic or chaotropic nature of ILs. Hydration number of ILs obtained using elctrostriction volume, isentropic compressibility, viscosity, and differential scanning calorimetry have been found to be comparative within the experimental error. The hydrophobic hydration has found to play an important role in hydration of ILs as compared to hydration due to hydrogen bonding and electrostriction. Limiting molar properties, hydration numbers, and B-coefficients have been discussed in terms of alkyl chain length of cation or nature of anion.

  3. Softness and non-spherical shape define the phase behavior and the structural properties of lysozyme in aqueous solutions

    Science.gov (United States)

    Baumketner, A.; Melnyk, R.; Holovko, M. F.; Cai, W.; Costa, D.; Caccamo, C.

    2016-01-01

    In this study, Boltzmann inversion is applied in conjunction with molecular dynamics simulations to derive inter-molecular potential for protein lysozyme in aqueous solution directly from experimental static structure factor. The potential has a soft repulsion at short distances and an attraction well at intermediate distances that give rise to the liquid-liquid phase separation. Moreover, Gibbs ensemble Monte Carlo simulations demonstrate that a non-spherical description of lysozyme is better suited to correctly reproduce the experimentally observed properties of such a phase separation. Our findings shed new light on the common problem in molecular and cell biology: "How to model proteins in their natural aqueous environments?"

  4. REVEAL: Software Documentation and Platform Migration

    Science.gov (United States)

    Wilson, Michael A.; Veibell, Victoir T.

    2011-01-01

    The Research Environment for Vehicle Embedded Analysis on Linux (REVEAL) is reconfigurable data acquisition software designed for network-distributed test and measurement applications. In development since 2001, it has been successfully demonstrated in support of a number of actual missions within NASA's Suborbital Science Program. Improvements to software configuration control were needed to properly support both an ongoing transition to operational status and continued evolution of REVEAL capabilities. For this reason the project described in this report targets REVEAL software source documentation and deployment of the software on a small set of hardware platforms different from what is currently used in the baseline system implementation. This presentation specifically describes the actions taken over a ten week period by two undergraduate student interns and serves as an overview of the content of the final report for that internship.

  5. Quality assessment of Moringa concanensis seed oil extracted through solvent and aqueous-enzymatic techniques

    OpenAIRE

    Anwar, Farooq; Latif, Sajid

    2008-01-01

    The composition and quality of the M. concanensis seed oil extracted through an aqueous-enzyme-assisted technique, using three commercial enzyme-mixtures (Natuzyme, Kemzyme, and Feedzyme) was compared to those of the control-, (without enzymes) and solvent-extracted oils. Aqueous enzyme-extracted M.concanensis seed oil content ranged from 23.54 to 27.46% and was significantly (P < 0.05) higher than that of the control (15.41%). Analyses of the oilseed residues (meals) revealed no significant ...

  6. Synthesis and Electrochemical Properties of Al doped Lithium Manganate Powders by Spray Pyrolysis Using Carbonate Aqueous Solution

    OpenAIRE

    HIROSE, Shoji; KODERA, Takayuki; Ogihara, Takashi

    2011-01-01

    Al doped LiMn2O4 powders were prepared by spray pyrolysis using the aqueous solution ofmanganese carbonate. The aqueous solution, in which manganese carbonate was uniformly dispersedby a surfactant, was used as the starting solution. Al2O3 nanopowders, Al(OH)3 and Al(NO3)3·9H2Owere used as the doping agent of Al. A scanning electron microscope photograph showed that Aldoped LiMn2O4 powders had spherical morphology with broad particle size distribution. X-raydiffraction revealed that crystal p...

  7. Ion Movement in Polypyrrole/Dodecylbenzenesulphonate Films in aqueous and non-aqueous electrolytes

    DEFF Research Database (Denmark)

    Vidanapathirana, K.; Careem, M.A.; Skaarup, Steen; West, Keld

    The electrochemical characteristics during the redox process of polypyrrole (PPy) films, prepared using dodecylbenzenesulphonate (DBS-) dopant species, have been investigated using a combination of cyclic voltammetry and Electrochemical Quartz Crystal Microbalance (EQCM) measurements. Investigati......The electrochemical characteristics during the redox process of polypyrrole (PPy) films, prepared using dodecylbenzenesulphonate (DBS-) dopant species, have been investigated using a combination of cyclic voltammetry and Electrochemical Quartz Crystal Microbalance (EQCM) measurements....... Investigations were carried out using aqueous and non-aqueous electrolytes to study the effect of solvent on the ion movement during redox processes. When PPy films are cycled in aqueous electrolytes transport of both anion and cation occurs during oxidation and reduction. However, when cycled in the nonaqueous...

  8. Stability of mineral matter in aqueous media of the Chernobyl Unit-4 Shelter: Thermodynamic evaluation

    International Nuclear Information System (INIS)

    A special geochemical environment exists within the Shelter (Sarcophagus) erected in 1986 over the destroyed Unit-4 of Chernobyl nuclear power plant (NPP). Based upon the available in situ and compositional data, thermodynamic models of solid-aqueous interactions were developed to clarify the leaching behavior of various materials within the Shelter. The Selektor-A code, based on a convex programming approach to Gibbs free energy minimization, was used for the calculations. A built-in flexible hybrid thermodynamic database for the system Na-K-Ca-Mg-Cl-S-N-H-O-Si-P-Fe-Al-Sr-Cs was extended with the critically selected and matched parameters for aqueous species and solid phases in the U-Zr-Si-O-H subsystem, secondary U-minerals, mineral phases of fully hydrated Portland cements and U-bearing zircons. Modeling results show that the Shelter Waters can selectively leach a significant quantity of U and Si from the fuel-containing masses, while Zr, Fe, Ca, Mg and some other components are rather insoluble. Serpentinite, assemblages of fully-hydrated phases of Portland cements, and oxidation products of steel structural elements are estimated to be sufficiently stable in the aqueous environment of the Shelter. Calculations also define some feasible pathways for secondary mineral formation from evaporation of Shelter water solutions and interactions between these waters with the mineral matter inside the Shelter

  9. On-chip aqueous two-phase system (ATPS) formation, consequential self-mixing, and their influence on drop-to-drop aqueous two-phase extraction kinetics

    Science.gov (United States)

    Wijethunga, Pavithra A. L.; Moon, Hyejin

    2015-09-01

    Aqueous two-phase systems (ATPSs) allow an advantageous aqueous two-phase extraction process (ATPE), a special type of liquid-liquid extraction. Compared with conventional liquid-liquid extraction using aqueous/organic extraction media, ATPE is known to provide relatively easy mass transfer and a gentle environment for biological separation applications. Considering the recent interest in microscale ATPE, we aimed to study (i) the potential of preparing ATPS droplets on a digital microfluidic device, and (ii) the influence of the fluidic dynamics created during the formation of ATPS, with the goal of enhancing on-chip ATPE process. On-chip ATPS formation was evaluated by preparing a series of ATPSs on electrowetting on dielectric digital microfluidic chips and comparing their characteristics with the same ATPSs prepared at macroscale using conventional procedures. An enhanced on-chip drop-to-drop ATPE process was achieved by incorporating a self-mixing condition created during ATPSformation. Results indicate a successful on-chip ATPS preparation as well as enhanced extraction performance by self-mixing in the absence of forced mixing. Findings of this research suggest an alternative, simple, yet adequate technique to provide mixing for on-chip applications, such as sample preparation in portable microfluidics, for which it is unfavorable to implement complicated mixing sequences or complex device geometries.

  10. Growth kinetics and long-term stability of CdS nanoparticles in aqueous solution under ambient conditions

    International Nuclear Information System (INIS)

    The ubiquity of naturally occurring nanoparticles in the aquatic environment is now widely accepted, but a better understanding of the conditions that promote their formation and persistence is needed. Using cadmium sulfide (CdS) as a model metal sulfide species, thiolate-capped CdS nanoparticles were prepared in the laboratory to evaluate how aquatic conditions influence metal sulfide nanoparticle growth and stability. This work examines CdS nanoparticle growth directly in aqueous solution at room temperature by utilizing the size-dependent spectroscopic properties of semiconductors detectable by UV/vis. CdS nanoparticle growth was governed by oriented attachment, a non-classical mechanism of crystallization in which small precursor nanoparticles coalesce to form larger nanoparticle products. Nanoparticle growth was slowed with increasing capping agent and decreasing ionic strength. In addition to examining the short-term (hours) growth of the nanoparticles, a long-term study was conducted in which cysteine-capped CdS nanoparticles were monitored over 3 weeks in solutions of various ionic strengths. The long-term study revealed an apparent shift from small nanoparticles to nanoparticles twice their original size, suggesting nanoparticle growth may continue through oriented attachment over longer time scales. High-ionic strength solutions resulted in salt-induced aggregation and eventual settling of nanoparticles within days, whereas low-ionic strength solutions were stable against settling over the course of the experiment. Sulfide recovery from cysteine-capped CdS nanoparticles as acid volatile sulfide was nearly quantitative after 2 weeks in fully oxygenated water, demonstrating significantly slowed oxidation of sulfide when complexed to Cd(II) within CdS nanoparticles. The nanoparticles were also shown to be resistant to oxidation by Fe(III) (hydr)oxide. This study illustrates that aggregation, rather than chemical oxidation, is likely more important to the

  11. Recovery of salicylic acid from aqueous solution by solvent extraction and supported liquid membrane using TOMAC as carrier

    International Nuclear Information System (INIS)

    Conventional sewage treatment plants do not fully degrade residues of pharmaceuticals, so that they are introduced into the aquatic environment. On this basis, the demand for the development of efficient systems for removing these compounds from water has assumed a great research interest. Membrane operations are increasingly employed in many industrial sectors as important alternative technologies to the classical processes of separation. Among membrane-based separation processes, the use of supported liquid membranes (SLMs) has received growing attention during recent years. In our work we had tried to recover a pharmaceutical product, salicylic acid (S.A), from an aqueous solution by solvent extraction and supported liquid membrane using an ionic liquid: the tri octylmethylammonium chloride (TOMAC) as carrier. Ionic liquids has been revealed as interesting clean alternatives to classical solvents and their use as a liquid phase results in the stabilization of the SLMs duo to their negligible vapour pressure, the possibility of minimising their solubility in the surrounding phases by adequate selection of the cation and anion, and the greater capillary force associated with their high viscosity. For this reason we had studied the influence of different parameters which could affect the efficiency of the transport: pH of the feed phase, the nature of the strippant, the concentration of the strippant, the nature of the support and the initial concentration of the salicylic acid in the feed phase. We had noticed that the pH of the feed solution had no effect of the percentage extraction and after 24 hours we can extract completely our solute. TOMAC seemed to be a good extractant but we found difficult to strip salicylic acid from the TOMAC phase and this could be related to the formation of water micro environments in the ionic liquid membrane.

  12. Sorption of tetracycline antibiotics on hyper-crosslinked polystyrene from aqueous and aqueous-organic media

    Science.gov (United States)

    Udalova, A. Yu.; Dmitrienko, S. G.; Apyari, V. V.

    2015-06-01

    The sorption of tetracycline, oxytetracycline, chlortetracycline, and doxycycline on hyper-cross-linked polystyrene from aqueous and aqueous-organic solutions is studied under static and dynamic conditions in order to extend the range of the sorbents suitable for sorption isolation and the preconcentration of tetracycline antibiotics. Features of tetracycline sorption depending on the acidity of a solution and the nature and concentration of the compounds are explained. It is shown that hyper-crosslinked polystyrene can be used for the group sorption preconcentration of these compounds.

  13. Intermolecular interactions and 3D structure in cellulose-NaOH-urea aqueous system.

    Science.gov (United States)

    Jiang, Zhiwei; Fang, Yan; Xiang, Junfeng; Ma, Yanping; Lu, Ang; Kang, Hongliang; Huang, Yong; Guo, Hongxia; Liu, Ruigang; Zhang, Lina

    2014-08-28

    The dissolution of cellulose in NaOH/urea aqueous solution at low temperature is a key finding in cellulose science and technology. In this paper, (15)N and (23)Na NMR experiments were carried out to clarify the intermolecular interactions in cellulose/NaOH/urea aqueous solution. It was found that there are direct interactions between OH(-) anions and amino groups of urea through hydrogen bonds and no direct interaction between urea and cellulose. Moreover, Na(+) ions can interact with both cellulose and urea in an aqueous system. These interactions lead to the formation of cellulose-NaOH-urea-H2O inclusion complexes (ICs). (23)Na relaxation results confirmed that the formation of urea-OH(-) clusters can effectively enhance the stability of Na(+) ions that attracted to cellulose chains. Low temperature can enhance the hydrogen bonding interaction between OH(-) ions and urea and improve the binding ability of the NaOH/urea/H2O clusters that attached to cellulose chains. Cryo-TEM observation confirmed the formation of cellulose-NaOH-urea-H2O ICs, which is in extended conformation with mean diameter of about 3.6 nm and mean length of about 300 nm. Possible 3D structure of the ICs was proposed by the M06-2X/6-31+G(d) theoretical calculation, revealing the O3H···O5 intramolecular hydrogen bonds could remain in the ICs. This work clarified the interactions in cellulose/NaOH/urea aqueous solution and the 3D structure of the cellulose chain in dilute cellulose/NaOH/urea aqueous solution. PMID:25111839

  14. Specific staining of nuclei with aqueous solutions of celestin blue B and gallocyanine.

    Science.gov (United States)

    Dutt, M K

    1982-09-01

    This paper presents methods for specific staining of nuclei with aqueous solutions of celestin blue B and gallocyanine in tissue sections from which RNA has been extracted selectively with concentrated phosphoric acid at 5 degrees C for 20 min or by hydrolysis in 6 N HCl at 28 degrees C for 15 min. It has been found that pH of the freshly prepared celestin blue B dye solution is 3.0 and that of an aqueous solution of gallocyanine is 2.8. These pHs can be lowered to 1.5 with concentrated sulphuric or nitric acid and at this pH staining of the nuclei is possible. But with concentrated sulphuric or nitric acid and at this pH staining of the nuclei is possible. But if the pHs are lowered with concentrated hydrochloric or phosphoric acid, effective use of these dyes is not possible. It has been suggested that some dispersion of the two dyes takes place with concentrated sulphuric or nitric acid which are used to lower the pH. Staining of the nuclei is also possible with an aqueous solution of celestin blue B at pH 3.0 but the same is not possible with gallocyanine at pH 2.8. The absorption spectra of nuclei stained with an aqueous solution of celestin blue B at pH 1.5 and 3.0 are fairly identical, the peak of maximum absorption being at 620 nm. Those of nuclei stained with an aqueous solution of gallocyanine reveal irregular peaks. Possible implications of these findings have been discussed. PMID:6183561

  15. Aqueous phase partitioning of hexachlorocyclohexane (HCH) isomers by biosurfactant produced by Pseudomonas aeruginosa WH-2

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Suman; Singh, Partapbir [Department of Microbiology, Guru Nanak Dev University, Amritsar 143005, Punjab (India); Raj, Mayil [MTCC, IMTECH, Sector 39-A, Chandigarh 160036 (India); Chadha, Bhupinder Singh [Department of Microbiology, Guru Nanak Dev University, Amritsar 143005, Punjab (India); Saini, Harvinder Singh, E-mail: sainihs@yahoo.com [Department of Microbiology, Guru Nanak Dev University, Amritsar 143005, Punjab (India)

    2009-11-15

    The different isomers of technical-grade hexachlorocyclohexane (t-HCH) including the insecticidal {gamma}-isomer, commonly known as lindane, have been reported to be toxic, carcinogenic and endocrine disrupters. The spatial arrangements of the chlorine atoms on different isomers and low aqueous phase solubility contribute to their persistence in environment, {beta}-HCH being the most resistance to transformation. The biosurfactant preparation of Pseudomonas aeruginosa isolate WH-2 was evaluated for its ability to improve the aqueous phase partitioning of different isomers of HCH-muck. Further, the ability of biosurfactant preparation to emulsify HCH and n-hexadecane was checked under different conditions, usually characteristic of sites contaminated with pollutants viz. wide range of pH, temperature, and salinity. The data obtained from this study will be helpful in designing suitable bioremediation strategies for huge stock piles of HCH-muck and sites polluted by reckless use/disposal of HCH-isomers.

  16. Aqueous phase partitioning of hexachlorocyclohexane (HCH) isomers by biosurfactant produced by Pseudomonas aeruginosa WH-2

    International Nuclear Information System (INIS)

    The different isomers of technical-grade hexachlorocyclohexane (t-HCH) including the insecticidal γ-isomer, commonly known as lindane, have been reported to be toxic, carcinogenic and endocrine disrupters. The spatial arrangements of the chlorine atoms on different isomers and low aqueous phase solubility contribute to their persistence in environment, β-HCH being the most resistance to transformation. The biosurfactant preparation of Pseudomonas aeruginosa isolate WH-2 was evaluated for its ability to improve the aqueous phase partitioning of different isomers of HCH-muck. Further, the ability of biosurfactant preparation to emulsify HCH and n-hexadecane was checked under different conditions, usually characteristic of sites contaminated with pollutants viz. wide range of pH, temperature, and salinity. The data obtained from this study will be helpful in designing suitable bioremediation strategies for huge stock piles of HCH-muck and sites polluted by reckless use/disposal of HCH-isomers.

  17. Critical issues in the use of metals and alloys in sulphur-containing aqueous systems

    Energy Technology Data Exchange (ETDEWEB)

    Macdonald, D.D.

    1992-12-31

    Sulphur-containing aqueous fluids are amongst the most corrosive environments experienced in industrial and natural systems. The high corrosivity is due principally to the wide range of oxidation states that sulphur may exist in within the thermodynamic stability domain of water, as well as to the high lability of many sulphur species, such as the polythionic acids and polysulfides. Additionally, sulphur, along with arsenic, antimony, and mercury, effectively promotes the entry of hydrogen into metal and alloy matrices, thereby leading to hydrogen damage and hydrogen embrittlement. In this paper, the chemistry of sulphur species in aqueous solutions and of the various iron sulphides is reviewed with emphasis on illustrating the diverse nature of metal/sulphur interactions. Finally, we identify a number of critical issues that need to be resolved to greatly improve our understanding of the chemistry of sulphur-containing systems and to improve our ability to predict the form and extent of corrosion in geochemical and geoenergy systems.

  18. Critical issues in the use of metals and alloys in sulphur-containing aqueous systems

    Energy Technology Data Exchange (ETDEWEB)

    Macdonald, D.D.

    1992-01-01

    Sulphur-containing aqueous fluids are amongst the most corrosive environments experienced in industrial and natural systems. The high corrosivity is due principally to the wide range of oxidation states that sulphur may exist in within the thermodynamic stability domain of water, as well as to the high lability of many sulphur species, such as the polythionic acids and polysulfides. Additionally, sulphur, along with arsenic, antimony, and mercury, effectively promotes the entry of hydrogen into metal and alloy matrices, thereby leading to hydrogen damage and hydrogen embrittlement. In this paper, the chemistry of sulphur species in aqueous solutions and of the various iron sulphides is reviewed with emphasis on illustrating the diverse nature of metal/sulphur interactions. Finally, we identify a number of critical issues that need to be resolved to greatly improve our understanding of the chemistry of sulphur-containing systems and to improve our ability to predict the form and extent of corrosion in geochemical and geoenergy systems.

  19. A combined chemical + enzymatic method to remove selected aromatics from aqueous streams

    International Nuclear Information System (INIS)

    Aromatics are major pollutants found in aqueous environments and in sediments. While there are many chemical and biochemical processes to remove and/or destroy these contaminants, they have to be considered in light of the economics and the time-scales for treatment. We describe our initial work on a hybrid chemical + enzymatic technique to remove aromatics from aqueous stream. The aromatic is first converted to the corresponding phenol through classical Fenton type chemistry involving catalysis by Fe(II). The phenol is subsequently polymerized through an enzymatic mechanism, using horseradish peroxidase as the oxidative enzyme. The polymer is insoluble in water and can be easily recovered. In addition, such phenolic polymers are useful products with varied applications in coatings and resin technologies. Thus, the pollutants can be eventually converted to useful products

  20. Biogenic transformed floating macroporous cryogel for uranium sorption from aqueous medium

    International Nuclear Information System (INIS)

    Radionuclide contamination to the environment affects human health and environmental flora and fauna. A recent study suggests that approximately 9000 tons of uranium is contributed to sea every year by fresh water streams and approximately 4.58 billion tons of uranium is present in the well-mixed upper surface of oceans. However, from this around 2 billion tons is considered for accessible recovery. Considering the requirement of separation approaches, a wide range of methods like solvent extraction, ion exchange, complexation and precipitation have been developed for the removal of hazardous substances from water bodies. The process of adsorption using biomaterials is considered as one of the alternative approach for removal of radionuclides from aqueous streams. Authors interest is to develop a simple and user-friendly technology for the separation of radionuclides from aqueous subsurfaces

  1. Aqueous Corrosion Rates for Waste Package Materials

    Energy Technology Data Exchange (ETDEWEB)

    S. Arthur

    2004-10-08

    The purpose of this analysis, as directed by ''Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]), is to compile applicable corrosion data from the literature (journal articles, engineering documents, materials handbooks, or standards, and national laboratory reports), evaluate the quality of these data, and use these to perform statistical analyses and distributions for aqueous corrosion rates of waste package materials. The purpose of this report is not to describe the performance of engineered barriers for the TSPA-LA. Instead, the analysis provides simple statistics on aqueous corrosion rates of steels and alloys. These rates are limited by various aqueous parameters such as temperature (up to 100 C), water type (i.e., fresh versus saline), and pH. Corrosion data of materials at pH extremes (below 4 and above 9) are not included in this analysis, as materials commonly display different corrosion behaviors under these conditions. The exception is highly corrosion-resistant materials (Inconel Alloys) for which rate data from corrosion tests at a pH of approximately 3 were included. The waste package materials investigated are those from the long and short 5-DHLW waste packages, 2-MCO/2-DHLW waste package, and the 21-PWR commercial waste package. This analysis also contains rate data for some of the materials present inside the fuel canisters for the following fuel types: U-Mo (Fermi U-10%Mo), MOX (FFTF), Thorium Carbide and Th/U Carbide (Fort Saint Vrain [FSVR]), Th/U Oxide (Shippingport LWBR), U-metal (N Reactor), Intact U-Oxide (Shippingport PWR, Commercial), aluminum-based, and U-Zr-H (TRIGA). Analysis of corrosion rates for Alloy 22, spent nuclear fuel, defense high level waste (DHLW) glass, and Titanium Grade 7 can be found in other analysis or model reports.

  2. Aqueous Corrosion Rates for Waste Package Materials

    International Nuclear Information System (INIS)

    The purpose of this analysis, as directed by ''Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]), is to compile applicable corrosion data from the literature (journal articles, engineering documents, materials handbooks, or standards, and national laboratory reports), evaluate the quality of these data, and use these to perform statistical analyses and distributions for aqueous corrosion rates of waste package materials. The purpose of this report is not to describe the performance of engineered barriers for the TSPA-LA. Instead, the analysis provides simple statistics on aqueous corrosion rates of steels and alloys. These rates are limited by various aqueous parameters such as temperature (up to 100 C), water type (i.e., fresh versus saline), and pH. Corrosion data of materials at pH extremes (below 4 and above 9) are not included in this analysis, as materials commonly display different corrosion behaviors under these conditions. The exception is highly corrosion-resistant materials (Inconel Alloys) for which rate data from corrosion tests at a pH of approximately 3 were included. The waste package materials investigated are those from the long and short 5-DHLW waste packages, 2-MCO/2-DHLW waste package, and the 21-PWR commercial waste package. This analysis also contains rate data for some of the materials present inside the fuel canisters for the following fuel types: U-Mo (Fermi U-10%Mo), MOX (FFTF), Thorium Carbide and Th/U Carbide (Fort Saint Vrain [FSVR]), Th/U Oxide (Shippingport LWBR), U-metal (N Reactor), Intact U-Oxide (Shippingport PWR, Commercial), aluminum-based, and U-Zr-H (TRIGA). Analysis of corrosion rates for Alloy 22, spent nuclear fuel, defense high level waste (DHLW) glass, and Titanium Grade 7 can be found in other analysis or model reports

  3. OPTICAL PROPERTIES OF CARBAMIDE AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    E. V. Avramenko

    2016-03-01

    Full Text Available Subject of Research. The paper presents the results of measurements of refractometric properties (refractive index n, its temperature factor dn/dt and the ultraviolet spectral absorption in carbonic acid diamide aqueous solutions (carbamide depending on solid residue mass fraction md = 0-50 % and on temperaturet = 10-70 °C.Method of Research. Laboratory methods ofliquid-phase medium refractometry and ultraviolet spectrophotometry were applied for the research. We carried out computational modeling of electronic states spectrum for the carbonic acid diamide molecule and theoretical calculation of the fundamental electronic absorption of the molecule in the ultraviolet wavelenght region.Main Results. We have established that the solution concentration md has a nonlinear character and may be represented by the quadratic polynomial with the error Δn= ± 0,0005. We have shown the refractive indexdependence on temperature n(t changes in linear fashion att = 10-70 °C.At that, the inclination of lines n(t increases at the increase of md; so, the temperature factor dn/dt may be approximated by the quadratic polynomial. Transmission spectra of solutions in the spectral region λ= 225-760 nm have no special features except for the sharp edge in the short-wavelength region; the fundamental electronic absorptionis responsible for it. We have established that dispersion dependences of the refraction index n(λ;md in aqueous solutions of carbamide at λ= 360-760 nm and at md = 0-50 % may be calculated with the satisfactory error without additional adjustable parameters from the ultraviolet absorption data in terms of the one-dimentional oscillator Lorentz model.PracticalRelevance. Representedmeasurements of carbonic acid diamide aqueous solutions optical properties may be applied for the adjustment and calibration of commercial refractometers at processing lines of the AdBlue reagent manufacture for the selective catalytic reduction (SCR of motor transport

  4. Fullerene C60 in Aqueous Medium

    Czech Academy of Sciences Publication Activity Database

    Kocábová, Jana; Gál, Miroslav; Hromadová, Magdaléna; Kavan, Ladislav; Pospíšil, Lubomír; Sokolová, Romana

    Ústí nad Labem: BEST servis, 2010 - (Navrátil, T.; Barek, J.), s. 15-18 ISBN 978-80-254-6710-7. [Modern Electroanalytical Methods /30./. Jetřichovice (CZ), 24.05.2010-28.05.2010] R&D Projects: GA ČR GA203/09/0705; GA ČR GA203/08/1157; GA ČR GP203/09/P502; GA MŠk LC510; GA MŠk OC 140 Institutional research plan: CEZ:AV0Z40400503 Keywords : fullerene C60 * aqueous solution * electron transfer Subject RIV: CG - Electrochemistry

  5. Non-aqueous Isorefractive Pickering Emulsions

    OpenAIRE

    Thompson, Kate L.; Lane, Jacob A.; Derry, Matthew J.; Armes, Steven P.

    2015-01-01

    Non-aqueous Pickering emulsions of 16–240 μm diameter have been prepared using diblock copolymer worms with ethylene glycol as the droplet phase and an n-alkane as the continuous phase. Initial studies using n-dodecane resulted in stable emulsions that were significantly less turbid than conventional water-in-oil emulsions. This is attributed to the rather similar refractive indices of the latter two phases. By utilizing n-tetradecane as an alternative oil that almost precisely matches the re...

  6. NON-AQUEOUS DISSOLUTION OF MASSIVE PLUTONIUM

    Science.gov (United States)

    Reavis, J.G.; Leary, J.A.; Walsh, K.A.

    1959-05-12

    A method is presented for obtaining non-aqueous solutions or plutonium from massive forms of the metal. In the present invention massive plutonium is added to a salt melt consisting of 10 to 40 weight per cent of sodium chloride and the balance zinc chloride. The plutonium reacts at about 800 deg C with the zinc chloride to form a salt bath of plutonium trichloride, sodium chloride, and metallic zinc. The zinc is separated from the salt melt by forcing the molten mixture through a Pyrex filter.

  7. UV curable aqueous dispersions for wood coatings

    International Nuclear Information System (INIS)

    In this paper the characterisation of aqueous dispersions of UV curable resins is described. Two types of dispersions were used: dispersions that are tacky after water evaporation and tack - free before cure dispersions. The physical and rheological properties of these products have been determined and the performance of these dispersions in various formulations, especially for wood applications has been studied. With these dispersions, it is possible to produce coatings having a good cure speed, good surface hardness and good solvent -, chemical - and water resistance

  8. Radiation protection of vitamins in aqueous systems

    International Nuclear Information System (INIS)

    A study of the radiation induced decomposition of the B-group vitamins has been carried out in aqueous media at room temperature as well as in rigid matrices at low temperature. The detailed results on the effect of glucose and oxygen as protective additives at the different temperatures are presented in the case of Thiamine (Vitamin B1). Comparative data are given on the extent of decomposition of this and other vitamins of the B-group at room temperature and at 193 K. The importance of these results in connection with the radiation sterilization of pharmaceutical preparations is indicated. (author)

  9. Autoxidation of tryptophan in aqueous solutions

    OpenAIRE

    LJUBICA R. JOSIMOVIC; IVANA A. JANKOVIC

    2001-01-01

    Autoxidation of tryptophan was investigated in aqueous solutions by the gamma radiolytic technique. The oxygen uptake and formation of peroxide materials was followed as a function of pH, dose rate and concentration of tryptophan. The results obtained indicate that TrpH(OH)OO. radicals react with tryptophan by adduct formation thus propagating autoxidation. The chain propagation length (CPL) for a 2·102 mol dm3 tryptophan solution at pH 9.5 and a dose rate 0.01 Gy s1 was estimated to be ~ 5.8...

  10. DIURETIC AND ANTI-INFLAMMATORY ACTIVITY OF AQUEOUS EXTRACT OF AERVA SANGUINOLENTA (L. BLUME

    Directory of Open Access Journals (Sweden)

    Srinivas Reddy K

    2011-07-01

    Full Text Available The study was designed to evaluate the diuretic and anti-inflammatory potency of aqueous extract of whole plant of Aerva sanguinolenta in wistar albino rats. Different parameters viz. total urine volume, urine concentration of electrolytes such as sodium; potassium and chloride have been evaluated for assessment of diuretic activity. Anti-inflammatory was performed against carrageenan induced paw oedema method by using indomethacin as standard.The results revealed that the aqueous extract showed significant diuretic activity at a dose of 400 mg/kg body weigh by increasing the total volume of urine and concentration of sodium, potassium and chloride ions in urine and also extract showed significant anti-inflammatory activity.

  11. Removal of lead from aqueous solutions by condensed tannin gel adsorbent

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Lead has caused serious environmental pollution due toits toxicity, accumulation in food chains and persistence innature. In this paper, lead removal from aqueous solutions wasinvestigated using condensed tannin gel adsorbent synthesized froma natural tannin compound. It is found that the adsorption isstrongly affected by pH values of aqueous solutions. Within pHrange of 3.5-6, when initial lead concentration is 100 mg/L,removal efficiency is more than 90%. Adsorption equilibrium isreached within 150 minutes. The adsorption isotherm fits well withthe Langmuir equation, by which the saturated adsorption uptake of190 mg Pb2+/g dry tannin gel adsorbent is obtained. By means of thermodynamics analysis, it is revealed that the process isexothermic and the adsorption heat is up to 38.4 kJ/mol. Withrespect to high efficiency, moderate pH requirement and minimizedsecond pollution, the tannin gel adsorbent exhibits a promisingpotential in the removal of lead from wastewater.

  12. Removal of Cr(VI from aqueous solution using Bacillus subtilis, Pseudomonas aeruginosa and Enterobacter cloacae

    Directory of Open Access Journals (Sweden)

    P. Sethuraman,

    2010-06-01

    Full Text Available The objective of this study is to investigate the removal efficiency of Cr(VI by Bacillus subtilis, Pseudomonas aeruginosa and Enterobacter cloacae from aqueous solution under different process conditions. Batch mode experiments were carried out as a function of solution pH, biosorbent dosage, Cr(VI concentration and contact time.The FT-IR spectra and SEM analysis of the biosorbent were recorded to analyse the number and position of the functional groups available for the binding of Cr(VI ions and to study the morphology of biosorbent. The batch isothermal equilibrium data were analyzed with Freundlich and Langmuir isotherm models. The kinetic models were examined with pseudo first order and pseudo second order kinetics. The results revealed that the Cr(VI is considerably adsorbed on bacterial biomass and it could be an economical method for the removal of Cr(VI from aqueous solution.

  13. EVALUATION OF SEDATIVE ACTIVITY OF AQUEOUS EXTRACT OF VIGNA TRILOBATA (L. VERDC. LEAVES

    Directory of Open Access Journals (Sweden)

    Ahir Chetan D

    2011-04-01

    Full Text Available The aim of present study is to evaluate the sedative activity of aqueous extract of Vigna trilobata (L verdc. Leaves using experimental animal models. In the present study aqueous extract of the Vigna trilobata leaves (AEVTL was used to investigate the sedative activity using Rotarod apparatus and Photoactometer in mice at a dose of 200 and 400 mg/kg of body weight and compared to standard diazepam (5mg/kg, i.p.. The result obtained from this study revealed that AEVTL possessed significant (p<0.05 and p<0.01 sedative activity at a dose of 200 and 400 mg/kg by reducing locomotor activity and fall off time in mice in a dose dependent manner. The results of this study justify the use of the leaves as sedative in traditional medicine. Further studies may be directed at characterizing the bioactive ingredients that are responsible for the observed sedative activity in the plant.

  14. Water rotational jump driven large amplitude molecular motions of nitrate ions in aqueous potassium nitrate solution

    CERN Document Server

    Banerjee, Puja; Bagchi, Biman

    2016-01-01

    Molecular dynamics simulations of aqueous potassium nitrate solution reveal a highly complex rotational dynamics of nitrate ions where, superimposed on the expected continuous Brownian motion, are large amplitude angular jumps that are coupled to and at least partly driven by similar large amplitude jump motions in water molecules which are associated with change in the hydrogen bonded water molecule. These jumps contribute significantly to rotational and translational motions of these ions. We explore the detailed mechanism of these correlated (or, coupled) jumps and introduce a new time correlation function to decompose the coupled orientational- jump dynamics of solvent and solute in the aqueous electrolytic solution. Time correlation function provides for the unequivocal determination of the time constant involved in orientational dynamics originating from making and breaking of hydrogen bonds. We discover two distinct mechanisms-both are coupled to density fluctuation but are of different types.

  15. Puerto Rico Revealed Preference data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Revealed preference models provide insights into recreational angler behavior and the economic value of recreational fishing trips. Revealed preference data is...

  16. Thermoelectric Manipulation of Aqueous Droplets in Microfluidic Devices

    OpenAIRE

    Sgro, Allyson E.; Allen, Peter B.; Chiu, Daniel T.

    2007-01-01

    This paper describes a method for manipulating the temperature inside aqueous droplets, utilizing a thermoelectric cooler to control the temperature of select portions of a microfluidic chip. To illustrate the adaptability of this approach, we have generated an “ice valve” to stop fluid flow in a microchannel. By taking advantage of the vastly different freezing points for aqueous solutions and immiscible oils, we froze a stream of aqueous droplets that were formed on-chip. By integrating thi...

  17. Process for separating cesium ions from aqueous solutions

    International Nuclear Information System (INIS)

    A precipitation agent is added to the aqueous solution and the resulting precipitate containing Cs+ ions is separated from the solution. By this process, caesium is to be separated selectively compared with other alkaline metal ions with great efficiency from aqueous solutions, particularly aqueous MAW (medium activity waste). This is achieved by using a sodium tetraphenyl borate attracting electrons to the phenyl rings and having substitutes. (orig./PW)

  18. Sorption of Hydrophobic Organic Compounds on Natural Sorbents and Organoclays from Aqueous and Non-Aqueous Solutions: A Mini-Review

    Directory of Open Access Journals (Sweden)

    Francis Moyo

    2014-05-01

    Full Text Available Renewed focus on the sorption of hydrophobic organic chemicals (HOCs onto mineral surfaces and soil components is required due to the increased and wider range of organic pollutants being released into the environment. This mini-review examines the possibility of the contribution and mechanism of HOC sorption onto clay mineral sorbents such as kaolinite, and soil organic matter and the possible role of both in the prevention of environmental contamination by HOCs. Literature data indicates that certain siloxane surfaces can be hydrophobic. Therefore soils can retain HOCs even at low soil organic levels and the extent will depend on the structure of the pollutant and the type and concentration of clay minerals in the sorbent. Clay minerals are wettable by nonpolar solvents and so sorption of HOCs onto them from aqueous and non-aqueous solutions is possible. This is important for two reasons: firstly, the movement and remediation of soil environments will be a function of the concentration and type of clay minerals in the soil. Secondly, low-cost sorbents such as kaolinite and expandable clays can be added to soils or contaminated environments as temporary retention barriers for HOCs. Inorganic cations sorbed onto the kaolinite have a strong influence on the rate and extent of sorption of hydrophobic organic pollutants onto kaolinite. Structural sorbate classes that can be retained by the kaolinite matrix are limited by hydrogen bonding between hydroxyl groups of the octahedral alumosilicate sheet and the tetrahedral sheet with silicon. Soil organic carbon plays a key role in the sorption of HOCs onto soils, but the extent will be strongly affected by the structure of the organic soil matter and the presence of soot. Structural characterisation of soil organic matter in a particular soil should be conducted during a particular contamination event. Contamination by mining extractants and antibiotics will require renewed focus on the use of the QSAR

  19. Aqueous enzymatic extraction of Moringa oleifera oil.

    Science.gov (United States)

    Mat Yusoff, Masni; Gordon, Michael H; Ezeh, Onyinye; Niranjan, Keshavan

    2016-11-15

    This paper reports on the extraction of Moringa oleifera (MO) oil by using aqueous enzymatic extraction (AEE) method. The effect of different process parameters on the oil recovery was discovered by using statistical optimization, besides the effect of selected parameters on the formation of its oil-in-water cream emulsions. Within the pre-determined ranges, the use of pH 4.5, moisture/kernel ratio of 8:1 (w/w), and 300stroke/min shaking speed at 40°C for 1h incubation time resulted in highest oil recovery of approximately 70% (goil/g solvent-extracted oil). These optimized parameters also result in a very thin emulsion layer, indicating minute amount of emulsion formed. Zero oil recovery with thick emulsion were observed when the used aqueous phase was re-utilized for another AEE process. The findings suggest that the critical selection of AEE parameters is key to high oil recovery with minimum emulsion formation thereby lowering the load on the de-emulsification step. PMID:27283648

  20. Fluidic Dielectrophoresis of Aqueous Electrical Interfaces

    Science.gov (United States)

    Gagnon, Zachary

    2014-11-01

    To date, alternating current (AC) electric fields have been exploited to dielectrophoretically manipulate bubbles, liquid drops, particles, biomolecules and cells. Research and applications in this area, however, has been primarily limited to the interfaces formed between two immiscible metal-liquid, particle-liquid, or gas-liquid surfaces on particles. The influence of AC electric fields across aqueous liquid-liquid interfaces remains relatively unexplored. Fundamentally, many electrokinetic phenomena arise from discontinuities in ionic flux and charge accumulation at electrical interfaces, and here I explore the influence of AC electric fields on the electrical interface created between two aqueous liquids with disparaging electrical properties Using a microfluidic channel with embedded electrodes, two fluid streams - one with a greater electrical conductivity, the other a greater dielectric constant - were made to flow side-by-side. An AC electric field was applied across the flow channel and fluid was observed to displace across the phase interface. The displacement direction is AC frequency dependent, and is attributed to the Maxwell-Wagner interfacial polarization at the liquid-liquid electrical interface. At low AC frequency, below the interfacial charge relaxation time, the high conductive stream is observed to displace into the high dielectric stream. Above this frequency, the direction of liquid injection reverses, and the high dielectric stream injects into the high conductivity stream. An analytical model is presented for this liquid crossover frequency, and applied towards biosensing applications.

  1. Aqueous Solution Vessel Thermal Model Development II

    Energy Technology Data Exchange (ETDEWEB)

    Buechler, Cynthia Eileen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-10-28

    The work presented in this report is a continuation of the work described in the May 2015 report, “Aqueous Solution Vessel Thermal Model Development”. This computational fluid dynamics (CFD) model aims to predict the temperature and bubble volume fraction in an aqueous solution of uranium. These values affect the reactivity of the fissile solution, so it is important to be able to calculate them and determine their effects on the reaction. Part A of this report describes some of the parameter comparisons performed on the CFD model using Fluent. Part B describes the coupling of the Fluent model with a Monte-Carlo N-Particle (MCNP) neutron transport model. The fuel tank geometry is the same as it was in the May 2015 report, annular with a thickness-to-height ratio of 0.16. An accelerator-driven neutron source provides the excitation for the reaction, and internal and external water cooling channels remove the heat. The model used in this work incorporates the Eulerian multiphase model with lift, wall lubrication, turbulent dispersion and turbulence interaction. The buoyancy-driven flow is modeled using the Boussinesq approximation, and the flow turbulence is determined using the k-ω Shear-Stress-Transport (SST) model. The dispersed turbulence multiphase model is employed to capture the multiphase turbulence effects.

  2. Estimating the Aqueous Solubility of Pharmaceutical Hydrates.

    Science.gov (United States)

    Franklin, Stephen J; Younis, Usir S; Myrdal, Paul B

    2016-06-01

    Estimation of crystalline solute solubility is well documented throughout the literature. However, the anhydrous crystal form is typically considered with these models, which is not always the most stable crystal form in water. In this study, an equation which predicts the aqueous solubility of a hydrate is presented. This research attempts to extend the utility of the ideal solubility equation by incorporating desolvation energetics of the hydrated crystal. Similar to the ideal solubility equation, which accounts for the energetics of melting, this model approximates the energy of dehydration to the entropy of vaporization for water. Aqueous solubilities, dehydration and melting temperatures, and log P values were collected experimentally and from the literature. The data set includes different hydrate types and a range of log P values. Three models are evaluated, the most accurate model approximates the entropy of dehydration (ΔSd) by the entropy of vaporization (ΔSvap) for water, and utilizes onset dehydration and melting temperatures in combination with log P. With this model, the average absolute error for the prediction of solubility of 14 compounds was 0.32 log units. PMID:27238488

  3. Aqueous sodium hydroxide seasonal thermal energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Gantenbein, P.; Daguenet-Frick, X.; Frank, E. [Univ. of Applied Sciences Rapperswil (Switzerland). Inst. for Solar Technologies SPF; Weber, R.; Fumey, B. [EMPA Swiss Federal Laboratories for Materials Science and Technology, Duebendorf (Switzerland); Williamson, T. [Kingspan Renewables Ltd, Portadown, Co. Armagh, Northern Ireland (United Kingdom)

    2012-07-01

    Seasonal storage of sensible thermal energy in materials is a challenge in respect to thermal loss corresponding to low volumetric energy density. In a process involving absorption and desorption lower heat losses and higher energy densities can be reached. The working pair sodium hydroxide (NaOH) and water can be employed to this purpose. A possible application of such a system can be a single family passive energy building that requires a maximum power output of approximately 8 kW. The required absorption/desorption zone can be designed as a falling film tube bundle, using either Hu's or Owens' correlations. To meet the required power the tube bundle can be built of 300 mm long tubes with an outer diameter of 12 mm in a configuration of either 3 rows of 18 tubes or 2 rows of 25 tubes. During desorption one row of 18 tubes or 3 rows of 6 tubes are sufficient. In the absorption or discharging process a mass flow of 2 to 4 kg/h of aqueous NaOH with a concentration of 50 wt% NaOH is required. In the reverse process 18 to 30 kg/h of aqueous NaOH at a concentration of 30 wt% are necessary. The mass transport is performed without recirculation, reducing the parasitic power consumption. Initial experiments conducted with a less reactive substitute liquid showed good homogeneous distribution.

  4. Acidic aqueous uranium electrodeposition for target fabrication

    International Nuclear Information System (INIS)

    Direct irradiation of targets inside nuclear research or multiple purpose reactors is a common route to produce 99Mo-99mTc radioisotopes. The electroplating of low enriched uranium over nickel substrate might be a potential alternative to produce targets of 235U. The electrochemistry of uranium at low temperature might be beneficial for an alternative route to produce 99Mo irradiation LEU targets. Electrodeposition of uranium can be made using ionic and aqueous solutions producing uranium oxide deposits. The performance of uranium electrodeposition is relatively low because a big competition with H2 evolution happens inside the window of electrochemical reduction potential. This work explores possibilities of electroplating uranium as UO22+ (Uranium-VI) in order to achieve electroplating uranium in a sufficient amount to be commercially irradiated in the future Brazilian RMB reactor. Electroplated nickel substrate was followed by cathodic current electrodeposition from aqueous UO2(NO3)2 solution. EIS tests and modeling showed that a film formed differently in the three tested cathodic potentials. At the lower level, (-1.8V) there was an indication of a double film formation, one overlaying the other with ionic mass diffusion impaired at the interface with nickel substrate as showed by the relatively lower admittance of Warburg component. (author)

  5. Corrosion problems with aqueous coolants, final report

    Energy Technology Data Exchange (ETDEWEB)

    Diegle, R B; Beavers, J A; Clifford, J E

    1980-04-11

    The results of a one year program to characterize corrosion of solar collector alloys in aqueous heat-transfer media are summarized. The program involved a literature review and a laboratory investigation of corrosion in uninhibited solutions. It consisted of three separate tasks, as follows: review of the state-of-the-art of solar collector corrosion processes; study of corrosion in multimetallic systems; and determination of interaction between different waters and chemical antifreeze additives. Task 1 involved a comprehensive review of published literature concerning corrosion under solar collector operating conditions. The reivew also incorporated data from related technologies, specifically, from research performed on automotive cooling systems, cooling towers, and heat exchangers. Task 2 consisted of determining the corrosion behavior of candidate alloys of construction for solar collectors in different types of aqueous coolants containing various concentrations of corrosive ionic species. Task 3 involved measuring the degradation rates of glycol-based heat-transfer media, and also evaluating the effects of degradation on the corrosion behavior of metallic collector materials.

  6. Electrostatic interactions and aqueous two-phase separation modes of aqueous mixed oppositely charged surfactants system.

    Science.gov (United States)

    Hao, Li-Sheng; Gui, Yuan-Xiang; Chen, Yan-Mei; He, Shao-Qing; Nan, Yan-Qing; You, Yi-Lan

    2012-08-30

    Electrostatic interactions play an important role in setting the aqueous two-phase separation behaviors of mixtures of oppositely charged surfactants. The aqueous mixture of cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfonate (AS) is actually a five-component system, comprised of CTAB, AS, complex salt (cetyltrimethylammonium dodecylsulfonate, abbreviated as CTA(+)AS(-)), NaBr, and water. In the three-dimensional pyramid phase diagram, the aqueous two-phase region with excess AS or with excess CTAB extends successively from the region very near to the NaBr-H2O line through the CTAB-AS-H2O conventional mixing plane to the CTA(+)AS(-)-AS-H2O side plane or to the CTA(+)AS(-)-CTAB-H2O side plane, respectively. Large or small molar ratios between the counterions and their corresponding surfactant ions for oppositely charged surfactants located in the NaBr side or the CTA(+)AS(-) side of the pyramid imply strong or weak electrostatic screening. Electrostatic screening of counterions alters the electrostatic attractions between the oppositely charged head groups or the electrostatic repulsions between the like-charged head groups in excess, and the electrostatic free energy of aggregation thus affects the aqueous two-phase separation modes. Composition analysis, rheological property investigation, and TEM images suggest that there are two kinds of aqueous two-phase systems (ATPSs). On the basis of these experimental results and Kaler's cell model, two kinds of phase separation modes were proposed. Experimental results also indicate that all of the top phases are surfactant-rich, and all of the bottom phases are surfactant-poor; the density difference between the top phase and the bottom phase in one ATPS is very small; the interfacial tension (σ) of the ATPS is ultralow. PMID:22856887

  7. Aqueous CO2 vs. aqueous extraction of soils as a preparative procedure for acute toxicity testing

    International Nuclear Information System (INIS)

    This study was to determine if contaminated soils extracted with supercritical CO2 (SFE) would yield different results from soils extracted with an aqueous media. Soil samples from an abandoned oil refinery were subjected to aqueous and SFE extraction. Uncontaminated control sites were compared with contaminated sites. Each extract was analyzed for 48 hour acute Ceriodaphnia LC50s and Microtox reg-sign EC50s. Comparisons were then made between the aqueous extracts and the SFE extracts. An additional study was made with HPLC chromatographs of the SFE contaminated site extracts to determine if there was a correlation between LC50 results and peak area of different sections of the chromatograph. The 48 hour Ceriodaphnia LC50 of one contaminated site showed a significant increase in toxicity with the supercritical extract compared to the aqueous extract. All contaminated sites gave toxic responses with the supercritical procedure. The Microtox reg-sign assay showed a toxic response with 2 of the 3 contaminated sites for both aqueous and SFE extracts. Results indicate that the Ceriodaphnia assays were more sensitive than Microtox reg-sign to contaminants found in the refinery soil. SFE controls did not show adverse effects with the Ceriodaphnia, but did have a slight effect with Microtox reg-sign. The best correlation (r2 > 0.90) between the Ceriodaphnia LC50s and the peak areas of the chromatographs was obtained for sections with an estimated log Kow of 1 to 5. SFE extraction provided a fast, efficient and inexpensive method of collecting and testing moderately non-polar to strongly non-polar organic contaminants from contaminated soils

  8. Advanced Aqueous Phase Catalyst Development using Combinatorial Methods Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Combinatorial methods are proposed to develop advanced Aqueous Oxidation Catalysts (AOCs) with the capability to mineralize organic contaminants present in...

  9. Effect of excimer laser (Arf, 193 nm) on aqueous humor during photorefractive keratectomy biophysical and biochemical study

    International Nuclear Information System (INIS)

    Ultraviolet light (193 nm) produced by an excimer laser has been used to produce precise tissue ablation with minimal thermal damage to adjacent tissue. The present study was designed to investigate the effect of excimer laser during photo refractive keratectomy (PRK) on aqueous humor constituents and also the effect of antioxidant enzyme superoxide dismutase (SOD)- applied topically- on these changes if exist. Five groups of schenchilla rabbits were involved in this study, where four groups underwent corneal stromal ablation using argon fluoride excimer laser (Ar F, 193 nm). Two of these four groups were treated with superoxide dismutase intra operatively. The fifth group was used as control one. The obtained results revealed depletion of aqueous humor ascorbate and glutathione contents. Aqueous humor refractive index, cholesterol, phospholipids, malondialdehyde (MDA) and total protein were measured. In conclusion, the excimer laser can induce changes in aqueous humor constituents during PRK. These changes lasted at least for 24 hours and as the time increased to 4 weeks, these changes became limited. The use of exogenous SOD seems to exert beneficial effect on aqueous humor refractive index and total protein

  10. The modern research environment

    DEFF Research Database (Denmark)

    Topsøe, Flemming

    1993-01-01

    Information Technology, research environment, structured documents, networked information retrieval......Information Technology, research environment, structured documents, networked information retrieval...

  11. Structural and Mechanistic Analysis through Electronic Spectra: Aqueous Hyponitrite Radical (N2O2-) and Nitrosyl Hyponitrite Anion (N3O3-)

    Energy Technology Data Exchange (ETDEWEB)

    Valiev, Marat; Lymar, Sergei V.

    2011-11-03

    Aqueous hyponitrite radical (N{sub 2}O{sub 2}{sup -}) and nitrosyl hyponitrite anion (N{sub 3}O{sub 3}{sup -}) species are important intermediates in the reductive chemistry of NO. The structures and absorption spectra of various hydrated isomers of these compounds were investigated in this work using high-level quantum mechanical calculations combined with the explicit classical description of the aqueous environment. For N{sub 2}O{sub 2}{sup -}, comparison of the calculated spectra and energetics with the experimental data reveals that: (1) upon the one-electron oxidation of trans-hyponitrite (ON=NO{sub 2}{sup -}), the trans configuration of the resulting ON=NO{sup -} radical is preserved; (2) although cis- and trans-ON=NO{sup -} are energetically nearly equivalent, the barrier for the trans-cis isomerization is prohibitively high due to the partial double character of the NN bond; (3) the UV spectrum of ON=NO{sup -} was misinterpreted in the earlier pulse radiolysis work and its more recent revision has been justified. For the N{sub 3}O{sub 3}{sup -} ion, the symmetric isomer is the dominant observable species, and the asymmetric isomer contributes little to the experimental spectrum. Coherent analysis of the calculated and experimental data suggests a re-interpretation of the N{sub 2}O{sub 2}{sup -} + NO reaction mechanism, according to which the reaction evenly bifurcates to yield both the symmetric and asymmetric isomers of N{sub 3}O{sub 3}{sup -}. While the latter isomer rapidly decomposes to the final NO{sub 2}{sup -} + N{sub 2}O products, the former isomer is stable toward this decomposition but its formation is reversible with the homolysis equilibrium constant Khom = 2.2 - 10{sup -7} M. Collectively, these results demonstrate that advanced theoretical modeling can be of significant benefit in structural and mechanistic analysis of UV spectra.

  12. Supercritical aqueous fluids in subduction zones carrying carbon and sulfur: oxidants for the mantle wedge?

    Science.gov (United States)

    Sverjensky, Dimitri; Manning, Craig

    2014-05-01

    magnesite, the C/S ratio can vary from 0.2 to 3.5 when temperature varies from 650 to 750 °C at 4 GPa. Fe concentrations remain negligible. These results strongly suggest that aqueous subarc eclogitic fluids that evolve to QFM +3 to +4, perhaps by reaction with metamorphosed Fe-oxide-bearing sediments, could transport significant amounts of C and/or S into the mantle wedge environment depending on the temperature. Hotter subduction should favor high C/S fluids, whereas colder subduction should favor low C/S fluids. Aqueous Fe transport is unlikely to be playing a significant role in oxidizing the mantle wedge. Sverjensky, D. A., Harrison, B., and Azzolini, D., 2014. Water in the deep Earth: the dielectric constant and the solubilities of quartz and corundum to 60 kb and 1,200°C. Geochim. et Cosmochim. Acta (in press).

  13. Aqueous adsorption and removal of organic contaminants by carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Jin-Gang, E-mail: yujg@csu.edu.cn [College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083 (China); College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082 (China); Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, Hunan 410083 (China); Zhao, Xiu-Hui; Yang, Hua [College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083 (China); Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, Hunan 410083 (China); Chen, Xiao-Hong [Collaborative Innovation Center of Resource-conserving and Environment-friendly Society and Ecological Civilization, Changsha, Hunan 410083 (China); Yang, Qiaoqin [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9 (Canada); Yu, Lin-Yan [College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083 (China); Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, Hunan 410083 (China); Jiang, Jian-Hui [College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082 (China); Chen, Xiao-Qing, E-mail: xqchen@csu.edu.cn [College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083 (China); Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, Hunan 410083 (China)

    2014-06-01

    Organic contaminants have become one of the most serious environmental problems, and the removal of organic contaminants (e.g., dyes, pesticides, and pharmaceuticals/drugs) and common industrial organic wastes (e.g., phenols and aromatic amines) from aqueous solutions is of special concern because they are recalcitrant and persistent in the environment. In recent years, carbon nanotubes (CNTs) have been gradually applied to the removal of organic contaminants from wastewater through adsorption processes. This paper reviews recent progress (145 studies published from 2010 to 2013) in the application of CNTs and their composites for the removal of toxic organic pollutants from contaminated water. The paper discusses removal efficiencies and adsorption mechanisms as well as thermodynamics and reaction kinetics. CNTs are predicted to have considerable prospects for wider application to wastewater treatment in the future. - Highlights: • We summarize the most recent research progress of CNTs for removal of organics. • Adsorption mechanisms between CNTs and organics were elucidated in detail. • The developing trends and prospects of CNTs for removal of organics were discussed.

  14. ADSORPTION FROM AQUEOUS SOLUTION ONTO NATURAL AND ACID ACTIVATED BENTONITE

    Directory of Open Access Journals (Sweden)

    Laila Al-Khatib

    2012-01-01

    Full Text Available Dyes have long been used in dyeing, paper and pulp, textiles, plastics, leather, paint, cosmetics and food industries. Nowadays, more than 100,000 commercial dyes are available with a total production of 700,000 tones manufactured all over the world annually. About 10-15% of dyes are being disposed off as a waste into the environment after dyeing process. This poses certain hazards and environmental problems. The objective of this study is to investigate the adsorption behavior of Methylene Blue (MB from aqueous solution onto natural and acid activated Jordanian bentonite. Both bentonites are firstly characterized using XRD, FTIR and SEM techniques. Then batch adsorption experiments were conducted to investigate the effect of initial MB concentration, contact time, pH and temperature. It was found that the percentage of dye removal was improved from 75.8% for natural bentonite to reach 99.6% for acid treated bentonite. The rate of MB removal followed the pseudo second order model with a high correlation factor. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. The Langmuir isotherm model was found more representative. The results indicate that bentonite could be employed as a low cost adsorbent in wastewater treatment for the removal of colour and dyes.

  15. Aqueous adsorption and removal of organic contaminants by carbon nanotubes

    International Nuclear Information System (INIS)

    Organic contaminants have become one of the most serious environmental problems, and the removal of organic contaminants (e.g., dyes, pesticides, and pharmaceuticals/drugs) and common industrial organic wastes (e.g., phenols and aromatic amines) from aqueous solutions is of special concern because they are recalcitrant and persistent in the environment. In recent years, carbon nanotubes (CNTs) have been gradually applied to the removal of organic contaminants from wastewater through adsorption processes. This paper reviews recent progress (145 studies published from 2010 to 2013) in the application of CNTs and their composites for the removal of toxic organic pollutants from contaminated water. The paper discusses removal efficiencies and adsorption mechanisms as well as thermodynamics and reaction kinetics. CNTs are predicted to have considerable prospects for wider application to wastewater treatment in the future. - Highlights: • We summarize the most recent research progress of CNTs for removal of organics. • Adsorption mechanisms between CNTs and organics were elucidated in detail. • The developing trends and prospects of CNTs for removal of organics were discussed

  16. Corrosion penetration monitoring of advanced ceramics in hot aqueous fluids

    Directory of Open Access Journals (Sweden)

    Klaus G. Nickel

    2004-03-01

    Full Text Available Advanced ceramics are considered as components in energy related systems, because they are known to be strong, wear and corrosion resistant in many environments, even at temperatures well exceeding 1000 °C. However, the presence of additives or impurities in important ceramics, for example those based on Silicon Nitride (Si3N4 or Al2O3 makes them vulnerable to the corrosion by hot aqueous fluids. The temperatures in this type of corrosion range from several tens of centigrade to hydrothermal conditions above 100 °C. The corrosion processes in such media depend on both pH and temperature and include often partial leaching of the ceramics, which cannot be monitored easily by classical gravimetric or electrochemical methods. Successful corrosion penetration depth monitoring by polarized reflected light optical microscopy (color changes, Micro Raman Spectroscopy (luminescence changes and SEM (porosity changes will be outlined. The corrosion process and its kinetics are monitored best by microanalysis of cross sections, Raman spectroscopy and eluate chemistry changes in addition to mass changes. Direct cross-calibrations between corrosion penetration and mechanical strength is only possible for severe corrosion. The methods outlined should be applicable to any ceramics corrosion process with partial leaching by fluids, melts or slags.

  17. Rare earths in barites: distribution and effects on aqueous partitioning

    International Nuclear Information System (INIS)

    A large variety of barites collected from marine and continental environments was analyzed by neutron activation for the rare-earth elements (REE) La, Ce, Sm, Eu and Dy. Relative to chondrites all barites show a decrease of the lighter REE from La toward Eu. The abundance and distribution of rare earths in barites show a distinction of barite types. Deep-sea barites have large REE concentrations as do other authigenic deep-sea minerals and display the chondrite normalized Eu minimum, but not the negative Ce anomaly, of sea water. Other barites, mostly on land, some hydrothermal, and others of shallow marine origin, display lower total Ree concentrations. Chondrite normalized positive Eu anomalies are displayed by those varieties of reducing sedimentary and metamorphic origin. Distribution of REE in barite can be attributed both to crystallographic constraints of substitution and to solution complexing of REE in the precipitating medium. Plots of rare earth partitioning versus effective ion size suggest that the decreasing enrichment toward Eu for all barite types is caused by crystallographic constraints due to contraction of the substituting REE ion sizes relative to the size of the host Ba ion. Solution effects on REE substitution in barite can be evaluated. Under normal sea water conditions, solution complexing plays a minor role. However, increased alkalinities of reducing sediments and increased brine chlorinities could cause significant complexing and deplete REE heavier than Eu. Besides Dy in barites, this could be true for aqueous precipitation of REE in general. (author)

  18. Columnar molecular aggregation in the aqueous solutions of disodium cromoglycate

    Science.gov (United States)

    Agra-Kooijman, Dena M.; Singh, Gautam; Lorenz, Alexander; Collings, Peter J.; Kitzerow, Heinz-S.; Kumar, Satyendra

    2014-06-01

    Stack, chimneylike, and threadlike assemblies have previously been proposed for the structure of disodium cromoglycate (DSCG) aggregates in aqueous solutions. The results of the synchrotron x-ray scattering investigations reported here reveal the formation of simple columnar assemblies with π-π stacking at a separation of 3.4 Å between the DSCG molecules. Lateral separation between the assemblies is concentration and temperature dependent, varying from ˜35 to 42 Å in the orientationally ordered nematic (N) phase and from 27 to 32 Å in the columnar or middle (M) phase having long range lateral positional order. The assemblies' length depends on concentration and consists of ˜23 molecules in the N phase, becoming three to ten times larger in the M phase. The scission energy is concentration dependent in the N phase with values ˜7.19 ± 0.14 kBT (15 wt %), 2.73 ± 0.4 kBT (20 wt %), and 3.05 ± 0.2 kBT (25 wt %). Solutions of all concentrations undergo a spinodal decomposition at temperatures above ˜40 °C, resulting in DSCG-rich regions with the M phase and water-rich regions in the N and isotropic phases.

  19. Sorption of 137Cs from Aqueous Waste Solutions using Pottery

    International Nuclear Information System (INIS)

    A simple and inexpensive method for sorption of 137Cs from aqueous solutions using a highly available vase shape pottery material has been investigated. Porosity of the used pottery allowed for the penetration of the radioactive solution through its permeable body. Two routes had been investigated for cesium removal from the radioactive solutions. In the first one, pottery bodies were immersed into the radioactive solutions. In the second method; the radioactive solutions were filled the inner volumes of the pottery bodies. Vase shape pottery showed higher sorption capability for 137Cs much more than its powder forms, especially in the alkaline medium. Pottery bodies showed high potential for 137Cs removal. Adsorption isotherms revealed good lit to the Freundlich and Langumir isotherms. During sorption processes outside and inside the pottery body, 137Cs was well captured inside the amorphous microstructure of the pottery body. In this respect, micro filtration of cesium radionuclides through the used pottery could be postulated. Desorption experiments indicated higher immobilization affinity for radiocesium into pottery bodies, which indicates a high containment for 137Cs with an irreversible fixation mechanism

  20. Aqueous Medium Synthesis Route for Randomly Stacked Molybdenum Disulfide

    Directory of Open Access Journals (Sweden)

    Pravas Kumar Panigrahi

    2013-01-01

    Full Text Available Synthesis of poorly crystalline, randomly oriented rag-like structures of molybdenum disulfide has been reported starting from aqueous solutions of ammonium molybdate, and thioacetamide in presence of sodium dodecyl sulfate via calcination of the amorphous precipitates, obtained through acidification of the in situ generated intermediate of ammonium tetrathiomolybdate. X-ray photoelectron spectroscopy, UV-visible spectroscopy, and X-ray diffraction of the calcined samples reveal the formation of single-phase MoS2, while the amorphous precipitates have been found to be a mixture of Mo2S5, MoS3, and a trace amount of H2MoS4. Highly folded and disordered layers of rag-like MoS2 have been confirmed through high-resolution transmission electron microscopy. The electrical conductivity for the cold pressed pellet of the MoS2 sample is found to be significantly higher than that of 2H-MoS2 and increases further on annealing.