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Sample records for isolated water molecules

  1. Degradation of Bacterial Quorum Sensing Signaling Molecules by the Microscopic Yeast Trichosporon loubieri Isolated from Tropical Wetland Waters

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    Cheng-Siang Wong

    2013-09-01

    Full Text Available Proteobacteria produce N-acylhomoserine lactones as signaling molecules, which will bind to their cognate receptor and activate quorum sensing-mediated phenotypes in a population-dependent manner. Although quorum sensing signaling molecules can be degraded by bacteria or fungi, there is no reported work on the degradation of such molecules by basidiomycetous yeast. By using a minimal growth medium containing N-3-oxohexanoylhomoserine lactone as the sole source of carbon, a wetland water sample from Malaysia was enriched for microbial strains that can degrade N-acylhomoserine lactones, and consequently, a basidiomycetous yeast strain WW1C was isolated. Morphological phenotype and molecular analyses confirmed that WW1C was a strain of Trichosporon loubieri. We showed that WW1C degraded AHLs with N-acyl side chains ranging from 4 to 10 carbons in length, with or without oxo group substitutions at the C3 position. Re-lactonisation bioassays revealed that WW1C degraded AHLs via a lactonase activity. To the best of our knowledge, this is the first report of degradation of N-acyl-homoserine lactones and utilization of N-3-oxohexanoylhomoserine as carbon and nitrogen source for growth by basidiomycetous yeast from tropical wetland water; and the degradation of bacterial quorum sensing molecules by an eukaryotic yeast.

  2. Investigation of N-acyl homoserine lactone (AHL) molecule production in Gram-negative bacteria isolated from cooling tower water and biofilm samples.

    Science.gov (United States)

    Haslan, Ezgi; Kimiran-Erdem, Ayten

    2013-09-01

    In this study, 99 Gram-negative rod bacteria were isolated from cooling tower water, and biofilm samples were examined for cell-to-cell signaling systems, N-acyl homoserine lactone (AHL) signal molecule types, and biofilm formation capacity. Four of 39 (10 %) strains isolated from water samples and 14 of 60 (23 %) strains isolated from biofilm samples were found to be producing a variety of AHL signal molecules. It was determined that the AHL signal molecule production ability and the biofilm formation capacity of sessile bacteria is higher than planktonic bacteria, and there was a statistically significant difference between the AHL signal molecule production of these two groups (p cooling tower water and biofilm samples produced different types of AHL signal molecules and that there were different types of AHL signal molecules in an AHL extract of bacteria. In the present study, it was observed that different isolates of the same strains did not produce the same AHLs or did not produce AHL molecules, and bacteria known as AHL producers did not produce AHL. These findings suggest that detection of signal molecules in bacteria isolated from cooling towers may contribute to prevention of biofilm formation, elimination of communication among bacteria in water systems, and blockage of quorum-sensing controlled virulence of these bacteria.

  3. Electron microscope autoradiography of isolated DNA molecules

    International Nuclear Information System (INIS)

    Delain, Etienne; Bouteille, Michel

    1980-01-01

    Autoradiographs of 3 H-thymidine-labelled DNA molecules were observed with an electron microscope. After ten months of exposure significant labelling was obtained with tritiated T7 DNA molecules which had a specific activity of 630,000 cpm/μg. Although isolated DNA molecules were not stretched out to such an extent that they could be rigorously compared to straight 'hot lines', the resolution was estimated and found to be similar to that obtained by autoradiography on thin plastic sections. The H.D. value was of the order of 1600A. From the known specific activity of the macromolecules, it was possible to compare the expected number of disintegrations from the samples to the number of grains obtained on the autoradiograms. This enabled us to calculate 1/ The absolute autoradiographic efficiency and 2/ The per cent ratio of thymidine residues labelled with tritium. These results throw some light on the resolution and sensitivity of electron microscope autoradiography of shadowed isolated macromolecules as compared to thin plastic sections

  4. Conserved water molecules in bacterial serine hydroxymethyltransferases.

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    Milano, Teresa; Di Salvo, Martino Luigi; Angelaccio, Sebastiana; Pascarella, Stefano

    2015-10-01

    Water molecules occurring in the interior of protein structures often are endowed with key structural and functional roles. We report the results of a systematic analysis of conserved water molecules in bacterial serine hydroxymethyltransferases (SHMTs). SHMTs are an important group of pyridoxal-5'-phosphate-dependent enzymes that catalyze the reversible conversion of l-serine and tetrahydropteroylglutamate to glycine and 5,10-methylenetetrahydropteroylglutamate. The approach utilized in this study relies on two programs, ProACT2 and WatCH. The first software is able to categorize water molecules in a protein crystallographic structure as buried, positioned in clefts or at the surface. The other program finds, in a set of superposed homologous proteins, water molecules that occur approximately in equivalent position in each of the considered structures. These groups of molecules are referred to as 'clusters' and represent structurally conserved water molecules. Several conserved clusters of buried or cleft water molecules were found in the set of 11 bacterial SHMTs we took into account for this work. The majority of these clusters were not described previously. Possible structural and functional roles for the conserved water molecules are envisaged. This work provides a map of the conserved water molecules helpful for deciphering SHMT mechanism and for rational design of molecular engineering experiments. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  5. Multiphoton processes in isolated atoms and molecules

    International Nuclear Information System (INIS)

    Sudbo, A.S.

    1979-11-01

    The theory of coherent excitation of a multilevel quantum mechanical system is developed. Damping of the system is taken into account by the use of a density matrix formalism. General properties of the wave function and/or the density matrix are discussed. The physical implications for the behavior of the system are described, together with possible applications of the formalism, including the infrared multiphoton excitation of molecules, and optical pumping in alkali atoms. Experimental results are presented on the infrared multiphoton dissociation of molecules, followed by a discussion of the general features of this process. The experimental results were obtained using a crossed laser and molecular beam method, and the emphasis is on determining the properties of the dissociating molecule and the dissociation products. The dissociation process is shown to be described very well by the standard statistical theory (RRKM theory) of unimolecular reactions, a brief presentation of which is also included

  6. Quantum Behavior of Water Molecules Confined to Nanocavities in Gemstones.

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    Gorshunov, Boris P; Zhukova, Elena S; Torgashev, Victor I; Lebedev, Vladimir V; Shakurov, Gil'man S; Kremer, Reinhard K; Pestrjakov, Efim V; Thomas, Victor G; Fursenko, Dimitry A; Dressel, Martin

    2013-06-20

    When water is confined to nanocavities, its quantum mechanical behavior can be revealed by terahertz spectroscopy. We place H2O molecules in the nanopores of a beryl crystal lattice and observe a rich and highly anisotropic set of absorption lines in the terahertz spectral range. Two bands can be identified, which originate from translational and librational motions of the water molecule isolated within the cage; they correspond to the analogous broad bands in liquid water and ice. In the present case of well-defined and highly symmetric nanocavities, the observed fine structure can be explained by macroscopic tunneling of the H2O molecules within a six-fold potential caused by the interaction of the molecule with the cavity walls.

  7. Diffractive Imaging of Coherent Nuclear Motion in Isolated Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jie; Guehr, Markus; Shen, Xiaozhe; Li, Renkai; Vecchione, Theodore; Coffee, Ryan; Corbett, Jeff; Fry, Alan; Hartmann, Nick; Hast, Carsten; Hegazy, Kareem; Jobe, Keith; Makasyuk, Igor; Robinson, Joseph; Robinson, Matthew S.; Vetter, Sharon; Weathersby, Stephen; Yoneda, Charles; Wang, Xijie; Centurion, Martin

    2016-10-03

    Observing the motion of the nuclear wave packets during a molecular reaction, in both space and time, is crucial for understanding and controlling the outcome of photoinduced chemical reactions. We have imaged the motion of a vibrational wave packet in isolated iodine molecules using ultrafast electron diffraction with relativistic electrons. The time-varying interatomic distance was measured with a precision 0.07 Å and temporal resolution of 230 fs full width at half maximum. The method is not only sensitive to the position but also the shape of the nuclear wave packet.

  8. Isolation and Characterisation of Some Microalgae Bioactive Molecules

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    Emeka Ugoala

    2016-12-01

    Full Text Available This study involved the isolation, structure elucidation, and biological screening of secondary metabolites in freshwater microalgae for bioactive and chemically novel compounds. Isolates were fractionated and purified from the methanol, ethyl acetate, dichloromethane, petroleum ether and aqueous extracts of microalgae via column chromatography technique over silica gel using a gradient mixture of solvents. The chemical structures of isolated compounds have been elucidated using Solid-state cross polarization (CP and magic angle spinning (MAS 13C-NMR spectroscopic technique at spectrometer frequency at a field strength corresponding to 91.3695 MHz for 13C and 363.331 MHz for 1H. Of the nine compounds isolated, eight have a glycan skeleton with attached amino acids units. Two of the eight contain beta amino acids units. These are not very common metabolites but hold promise as drug leads. The elements of diversity in the isolates were the gluco and manno configurations of the pyranose ring, the α-configurations at the anomeric centre, and the positions of the carbohydrate and amino acid sectors in the ring. These molecules are not easily available through gene technology since they are post translational products resulting from the activity of glycosyl hydrolases and transferases. The chemical shifts were rationalized in terms of the number of sugar residues, the sugar ring structures, the positions and anomeric configurations of the inter-sugar linkages. Considering all the NMR data, it was concluded that the compounds were glycylglycylglycylglycine, α-D-glucopyranosyl-2-amino-4-methylpentanoic acid, α-D-glucopyranosyl-2-methylamino-4-methylpentanoic acid, α-D-glucopyranosyl-2-amino-4-methylpentanoate, α-D-glucopyranosyl-glycylglycine, α-D-glucopyranosyl-3-aminobutanoic acid, α-D-glucopyranosyl-2,4,7-triaminooctantrioic acid, α-D-mannopyranosyl-2-amino-3-methylbutanoic acid and α-D-mannopyranosyl-3-aminobutanoic acid.

  9. Autodissociation of a water molecule in liquid water

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    Geissler, Phillip L.; Dellago, Christoph; Chandler, David; Hutter, Jurg; Parrinello, Michele

    2000-04-01

    The dissociation of a water molecule in liquid water is the fundamental event in acid-base chemistry, determining the pH of water.Because the microscopic dynamics of this autodissociation are difficult to probe, both by experiment and by computer simulation, its mechanism has been unknown. Here we report several autodissociation trajectories generated by ab initio molecular dynamics [1]. These trajectories, which were harvested using transition path sampling [2-4], reveal the mechanism for the first time. Rare fluctuations in solvation energies destabilize an oxygen-hydrogen bond. Through the transfer of one or more protons along a hydrogen bond.

  10. Slow neutron scattering by water molecules

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    Stancic, V [Boris Kidric Institute of Nuclear Sciences Vinca, Beograd (Yugoslavia)

    1970-07-01

    In this work some new, preliminary formulae for slow neutron scattering cross section calculation by heavy and light water molecules have been done. The idea was to find, from the sum which exists in well known Nelkin model, other cross sections in a more simple analytical form, so that next approximations may be possible. In order to sum a series it was starting from Euler-Mclaurin formula. Some new summation formulae have been derived there, and defined in two theorems. Extensive calculations, especially during the evaluation of residues, have been made at the CDC 3600 computer. validation of derived formulae was done by comparison with the BNL-325 results. Good agreement is shown. (author)

  11. Slow neutron scattering by water molecules

    International Nuclear Information System (INIS)

    Stancic, V.

    1970-01-01

    In this work some new, preliminary formulae for slow neutron scattering cross section calculation by heavy and light water molecules have been done. The idea was to find, from the sum which exists in well known Nelkin model, other cross sections in a more simple analytical form, so that next approximations may be possible. In order to sum a series it was starting from Euler-Mclaurin formula. Some new summation formulae have been derived there, and defined in two theorems. Extensive calculations, especially during the evaluation of residues, have been made at the CDC 3600 computer. validation of derived formulae was done by comparison with the BNL-325 results. Good agreement is shown. (author)

  12. Chemical reactions of water molecules on Ru(0001) induced by selective excitation of vibrational modes

    Energy Technology Data Exchange (ETDEWEB)

    Mugarza, Aitor; Shimizu, Tomoko K.; Ogletree, D. Frank; Salmeron, Miquel

    2009-05-07

    Tunneling electrons in a scanning tunneling microscope were used to excite specific vibrational quantum states of adsorbed water and hydroxyl molecules on a Ru(0 0 0 1) surface. The excited molecules relaxed by transfer of energy to lower energy modes, resulting in diffusion, dissociation, desorption, and surface-tip transfer processes. Diffusion of H{sub 2}O molecules could be induced by excitation of the O-H stretch vibration mode at 445 meV. Isolated molecules required excitation of one single quantum while molecules bonded to a C atom required at least two quanta. Dissociation of single H{sub 2}O molecules into H and OH required electron energies of 1 eV or higher while dissociation of OH required at least 2 eV electrons. In contrast, water molecules forming part of a cluster could be dissociated with electron energies of 0.5 eV.

  13. Molecular multipole moments of water molecules in ice Ih

    International Nuclear Information System (INIS)

    Batista, E.R.; Xantheas, S.S.; Jonsson, H.

    1998-01-01

    We have used an induction model including dipole, dipole endash quadrupole, quadrupole endash quadrupole polarizability and first hyperpolarizability as well as fixed octopole and hexadecapole moments to study the electric field in ice. The self-consistent induction calculations gave an average total dipole moment of 3.09 D, a 67% increase over the dipole moment of an isolated water molecule. A previous, more approximate induction model study by Coulson and Eisenberg [Proc. R. Soc. Lond. A 291, 445 (1966)] suggested a significantly smaller average value of 2.6 D. This value has been used extensively in recent years as a reference point in the development of various polarizable interaction potentials for water as well as for assessment of the convergence of water cluster properties to those of bulk. The reason for this difference is not due to approximations made in the computational scheme of Coulson and Eisenberg but rather due to the use of less accurate values for the molecular multipoles in these earlier calculations. copyright 1998 American Institute of Physics

  14. Theoretical investigation of the ultrafast dissociation of core-ionized water and uracil molecules immersed in liquid water

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    Stia, C.R.; Fojon, O.A. [Instituto de Fisica Rosario - CONICET-Universidad Nacional de Rosario, Rosario (Argentina); Gaigeot, M.P. [Laboratoire Analyse et Modelisation pour la Biologie et l' Environnement, LAMBE, UMR-CNRS 8587, Universite d' Evry-Val-d' Essonne, 91 - Evry (France); Institut Universitaire de France, 75 - Paris (France); Vuilleumier, R. [Departement de chimie, Ecole Normale Superieure, 75 - Paris (France); Herve du Penhoat, M.A.; Politis, M.F. [Institut de Mineralogie et de Physique des Milieux Condenses, IMPMC, UMR-CNRS 7590, Universite Pierre et Marie Curie, 75 - Paris (France)

    2010-10-15

    We present a series of ab initio density functional based calculations of the fragmentation dynamics of core-ionized biomolecules. The computations are performed for pure liquid water, aqueous and isolated Uracil. Core ionization is described by replacing the 1s{sup 2} pseudopotential of one atom of the target molecule (C, N or O) with a pseudopotential for a 1s{sup 1} core-hole state. Our results predict that the dissociation of core-ionized water molecules may be reached during the lifetime of inner-shell vacancy (less than 10 fs), leading to OH bond breakage as a primary outcome. We also observe a second fragmentation channel in which total Coulomb explosion of the ionized water molecule occurs. Fragmentation pathways are found similar for pure water or when the water molecule is in the primary hydration shell of the uracil molecule. In the latter case, the proton may be transferred towards the uracil oxygen atoms. When the core hole is located on the uracil molecule, ultrafast dissociation is only observed in the aqueous environment and for nitrogen-K vacancies, resulting in proton transfers towards the hydrogen-bonded water molecule. (authors)

  15. Isolated single-molecule magnets on native gold.

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    Zobbi, Laura; Mannini, Matteo; Pacchioni, Mirko; Chastanet, Guillaume; Bonacchi, Daniele; Zanardi, Chiara; Biagi, Roberto; Del Pennino, Umberto; Gatteschi, Dante; Cornia, Andrea; Sessoli, Roberta

    2005-03-28

    The incorporation of thioether groups in the structure of a Mn12 single-molecule magnet, [Mn12(O12)(L)16(H2O)4] with L = 4-(methylthio)benzoate, is a successful route to the deposition of well-separated clusters on native gold surfaces and to the addressing of individual molecules by scanning tunnelling microscopy.

  16. On the Several Molecules and Nanostructures of Water

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    Cynthia Kolb Whitney

    2012-01-01

    Full Text Available This paper investigates the water molecule from a variety of viewpoints. Water can involve different isotopes of Hydrogen and Oxygen, it can form differently shaped isomer molecules, and, when frozen, it occupies space differently than most other substances do. The tool for conducting the investigation of all this is called ‘Algebraic Chemistry’. This tool is a quantitative model for predicting the energy budget for all sorts of changes between different ionization states of atoms that are involved in chemical reactions and in changes of physical state. The model is based on consistent patterns seen in empirical data about ionization potentials, together with rational scaling laws that can interpolate and extrapolate for situations where no data are available. The results of the investigation of the water molecule include comments, both positive and negative, about technologies involving heavy water, poly water, Brown’s gas, and cold fusion.

  17. Towards ligand docking including explicit interface water molecules.

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    Gordon Lemmon

    Full Text Available Small molecule docking predicts the interaction of a small molecule ligand with a protein at atomic-detail accuracy including position and conformation the ligand but also conformational changes of the protein upon ligand binding. While successful in the majority of cases, docking algorithms including RosettaLigand fail in some cases to predict the correct protein/ligand complex structure. In this study we show that simultaneous docking of explicit interface water molecules greatly improves Rosetta's ability to distinguish correct from incorrect ligand poses. This result holds true for both protein-centric water docking wherein waters are located relative to the protein binding site and ligand-centric water docking wherein waters move with the ligand during docking. Protein-centric docking is used to model 99 HIV-1 protease/protease inhibitor structures. We find protease inhibitor placement improving at a ratio of 9:1 when one critical interface water molecule is included in the docking simulation. Ligand-centric docking is applied to 341 structures from the CSAR benchmark of diverse protein/ligand complexes [1]. Across this diverse dataset we see up to 56% recovery of failed docking studies, when waters are included in the docking simulation.

  18. Matrix isolation sublimation: An apparatus for producing cryogenic beams of atoms and molecules

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    Sacramento, R. L.; Alves, B. X.; Silva, B. A.; Wolff, W.; Cesar, C. L. [Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972 Rio de Janeiro, RJ (Brazil); Oliveira, A. N. [Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, 21941-972 Rio de Janeiro, RJ (Brazil); INMETRO, Av. Nossa Senhora das Graças, 50 25250-020 Duque de Caxias, RJ (Brazil); Li, M. S. [Instituto de Física de São Carlos, Universidade de São Paulo, Ave. Trabalhador São Carlense, 400, 13565-590 São Carlos, SP (Brazil)

    2015-07-15

    We describe the apparatus to generate cryogenic beams of atoms and molecules based on matrix isolation sublimation. Isolation matrices of Ne and H{sub 2} are hosts for atomic and molecular species which are sublimated into vacuum at cryogenic temperatures. The resulting cryogenic beams are used for high-resolution laser spectroscopy. The technique also aims at loading atomic and molecular traps.

  19. Radiation-induced transformations of isolated organic molecules in solid rare gas matrices

    International Nuclear Information System (INIS)

    Feldman, V.I.

    1998-01-01

    Complete text of publication follows. The studies of radiation-chemical behaviour of isolated organic molecules in rigid inert media are of considerable interest for radiation chemistry and general structural chemistry. Previous efforts were limited to the ESR studies of radicals resulting from some small hydrocarbon molecules in frozen rare gas solutions. Recently, we developed an approach to the radiation chemistry of isolated organic molecules using classic matrix isolation procedure for sample preparation and a combination of ESR and IR spectroscopy for characterization of paramagnetic and diamagnetic species resulting form electron irradiation or organic molecules in solid rare gas matrices at 10-15 K. The results obtained reveal high efficiency of energy transfer from rare gas matrix to organic molecules. The total radiation-chemical yields of degradation of organic molecules in argon and xenon matrices were measured directly by IR spectroscopy. The studies of the effect of electron scavengers on the radiolysis of organic molecules in solid rare gases show that the main primary process is positive hole transfer from matrix to additive molecule. ESR spectra of a number of radical cations (alkanes, ethers, arenes) were first characterized in a low-disturbing environment. It was found that the electronic characteristics (IP, polarizability) of the matrix used had crucial effect on trapping and degradation of primary organic radical cations. Using matrices with various IP provides an unique possibility to examine the chemical meaning of excess energy resulting from exothermic positive hole transfer, that is, to follow the fate of excited cations in condensed phase

  20. Transport behavior of water molecules through two-dimensional nanopores

    International Nuclear Information System (INIS)

    Zhu, Chongqin; Li, Hui; Meng, Sheng

    2014-01-01

    Water transport through a two-dimensional nanoporous membrane has attracted increasing attention in recent years thanks to great demands in water purification and desalination applications. However, few studies have been reported on the microscopic mechanisms of water transport through structured nanopores, especially at the atomistic scale. Here we investigate the microstructure of water flow through two-dimensional model graphene membrane containing a variety of nanopores of different size by using molecular dynamics simulations. Our results clearly indicate that the continuum flow transits to discrete molecular flow patterns with decreasing pore sizes. While for pores with a diameter ≥15 Å water flux exhibits a linear dependence on the pore area, a nonlinear relationship between water flux and pore area has been identified for smaller pores. We attribute this deviation from linear behavior to the presence of discrete water flow, which is strongly influenced by the water-membrane interaction and hydrogen bonding between water molecules

  1. Structures of water molecules in carbon nanotubes under electric fields

    International Nuclear Information System (INIS)

    Winarto,; Takaiwa, Daisuke; Yamamoto, Eiji; Yasuoka, Kenji

    2015-01-01

    Carbon nanotubes (CNTs) are promising for water transport through membranes and for use as nano-pumps. The development of CNT-based nanofluidic devices, however, requires a better understanding of the properties of water molecules in CNTs because they can be very different from those in the bulk. Using all-atom molecular dynamics simulations, we investigate the effect of axial electric fields on the structure of water molecules in CNTs having diameters ranging from (7,7) to (10,10). The water dipole moments were aligned parallel to the electric field, which increases the density of water inside the CNTs and forms ordered ice-like structures. The electric field induces the transition from liquid to ice nanotubes in a wide range of CNT diameters. Moreover, we found an increase in the lifetime of hydrogen bonds for water structures in the CNTs. Fast librational motion breaks some hydrogen bonds, but the molecular pairs do not separate and the hydrogen bonds reform. Thus, hydrogen bonds maintain the water structure in the CNTs, and the water molecules move collectively, decreasing the axial diffusion coefficient and permeation rate

  2. The role of water molecules in computational drug design.

    Science.gov (United States)

    de Beer, Stephanie B A; Vermeulen, Nico P E; Oostenbrink, Chris

    2010-01-01

    Although water molecules are small and only consist of two different atom types, they play various roles in cellular systems. This review discusses their influence on the binding process between biomacromolecular targets and small molecule ligands and how this influence can be modeled in computational drug design approaches. Both the structure and the thermodynamics of active site waters will be discussed as these influence the binding process significantly. Structurally conserved waters cannot always be determined experimentally and if observed, it is not clear if they will be replaced upon ligand binding, even if sufficient space is available. Methods to predict the presence of water in protein-ligand complexes will be reviewed. Subsequently, we will discuss methods to include water in computational drug research. Either as an additional factor in automated docking experiments, or explicitly in detailed molecular dynamics simulations, the effect of water on the quality of the simulations is significant, but not easily predicted. The most detailed calculations involve estimates of the free energy contribution of water molecules to protein-ligand complexes. These calculations are computationally demanding, but give insight in the versatility and importance of water in ligand binding.

  3. Water-assisted dehalogenation of thionyl chloride in the presence of water molecules.

    Science.gov (United States)

    Yeung, Chi Shun; Ng, Ping Leung; Guan, Xiangguo; Phillips, David Lee

    2010-04-01

    A second-order Møller-Plesset perturbation theory (MP2) and density functional theory (DFT) investigation of the dehalogenation reactions of thionyl chloride is reported, in which water molecules (up to seven) were explicitly involved in the reaction complex. The dehalogenation processes of thionyl chloride were found to be dramatically catalyzed by water molecules. The reaction rate became significantly faster as more water molecules became involved in the reaction complex. The dehalogenation processes can be reasonably simulated by the gas-phase water cluster models, which reveals that water molecules can help to solvate the thionyl chloride molecules and activate the release of the Cl(-) leaving group. The computed activation energies were used to compare the calculations to available experimental data.

  4. Water splitting: Taking cobalt in isolation

    Science.gov (United States)

    Wang, Aiqin; Zhang, Tao

    2016-01-01

    The sustainable production of hydrogen is key to the delivery of clean energy in a hydrogen economy; however, lower-cost alternatives to platinum electrocatalysts are needed. Now, isolated, earth-abundant cobalt atoms dispersed over nitrogen-doped graphene are shown to efficiently electrolyse water to generate hydrogen.

  5. Theoretical study on magnetism induced by H vacancy in isolated Alq3 and Gaq3 molecules

    Science.gov (United States)

    Ju, Lin; Xu, Tongshuai; Zhang, Yongjia; Sun, Li

    2017-10-01

    The magnetism induced by H vacancy in isolated Alq3 and Gaq3 molecules has been studied based on density functional theory. The isolated stoichiometric Alq3 and Gaq3 molecules are non-magnetic. With an H vacancy, both Alq3 and Gaq3 molecules could show magnetism, which are mainly due to the polarization of the C 2p electrons and the magnetic moments are mainly distributed at most nearby C atoms of H vacancies. This is because the unpaired electron on the C atom appears, when the H atom nearby is removed. Six cases of the H vacancy introduced in the Alq3 and Gaq3 molecules are considered, respectively. By comparing the relative defect formation energy, the V H3 vacancy is most likely to appear in the two kinds of molecules. In addition, for the ground state configuration of isolated Alq3 and Gaq3 molecules with two H vacancies, the energy of the ferromagnetic state is lower than that of the antiferromagnetic state, which means that the ferromagnetic state is stable. The ferromagnetic mechanism can be explained by the Heisenberg direct exchange interaction between two the polarized C atoms. Our work opens a new way to synthesize organic magnetic materials and perfects the theory of organic ferromagnetism by introducing the d 0 ferromagnetism.

  6. Vibrational properties of water molecules adsorbed in different zeolitic frameworks

    International Nuclear Information System (INIS)

    Crupi, V; Longo, F; Majolino, D; Venuti, V

    2006-01-01

    The perturbation of water 'sorbed' in samples of zeolites of different structural type, genesis, and cation composition (K-, Na-, Mg- and Ca-rich zeolites), namely the CHA framework of a synthetic K-chabazite, the LTA framework of synthetic Na-A and Mg50-A zeolites, and the NAT framework of a natural scolecite, has been studied by FTIR-ATR spectroscopy, in the -10 to +80 o C temperature range. The aim was to show how differences in the chemical composition and/or in the topology of the zeolite framework and, in particular, the possibility for the guest water molecules to develop guest-guest and/or host-guest interactions, lead to substantial differences in their vibrational dynamical properties. The spectra, collected in the O-H stretching and H 2 O bending mode regions, are complex, with multiple bands being observed. As far as water in the CHA and LTA frameworks is concerned, whose behaviour is governed by the balance of water-water, water-framework and water-extra-framework cations interactions, the assignment of the resolved components of the O-H stretching band has been discussed by fitting the band shapes into individual components attributed to H 2 O molecules engaged in different degrees of hydrogen bonding. A detailed quantitative picture of the connectivity pattern of water, as a function of temperature and according to the chemical and topological properties of the environment, is furnished. The H 2 O bending vibrational bands give additional information that perfectly agrees with the results obtained from the analysis of the O-H stretching spectral region. In the case of scolecite, a small-pored zeolite where water-water interactions are eliminated, the increased complexity observed in the infrared spectra in the O-H stretching and H 2 O bending regions was explained as due to the hydrogen bonding between the water molecules and the network, and also with the extra-framework cation. Furthermore, these observations have been correlated with the different

  7. Water feeding method upon reactor isolation

    International Nuclear Information System (INIS)

    Sasaki, Koichi; Takahara, Kuniaki; Hamamura, Kenji; Arakawa, Masahiro.

    1990-01-01

    The present invention concerns a method of feeding water upon reactor isolation in a plural loop type reactor having a plurality of reactor cooling systems. Water can be injected to a plurality of pools even if the pressure between the pools is not balanced and the water level in the reactor cooling system is optimally controlled. That is, water can be injected in accordance with the amount required for each of the pools by setting the opening of a turbine inlet steam control valve to somewhat higher than the cooling system pressure of the highest pressure loop. Water feeding devices upon reactor isolation were required by the same number as that for the reactor cooling systems. Whereas since pumps and turbines are used in common without worsening the water injection controllability to each of the loops according to the method of this invention and, accordingly, the cost performance can be improved. Further, since the opening degree of the turbine inlet steam control valve is controlled while making the difference pressure constant between the turbine inlet pressure and the pump exhaust pressure, the amount of the turbine exhausted steams can be reduced and, further, water injection controllability of the flow rate control valve in the injection line is improved. (I.S.)

  8. Photoionization of water molecules by high energy photons

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    Lara Martini

    2017-07-01

    Full Text Available We theoretically study the photoionization of water molecules by high energy photon impact. We develop a model in which the final state wavefunction is given by a Coulomb continuum wavefunction with effective charges and the water molecule bound states are represented using the Moccia's monocentric wavefunctions. We obtain analytical expressions for the transition matrix element that enable the computation of cross sections by numerical quadratures. We compare our predictions for photon energies between 20 and 300 eV with more elaborated theoretical results and experiments. We obtain a very good agreement with experiments, in particular, at enough high energies where there is a lack of elaborated results due to their high computational cost. Received: 15 March 2017, Accepted: 25 June 2017; Edited by: S. Kais; DOI: http://dx.doi.org/10.4279/PIP.090006 Cite as: L Martini, D I R Boll, O A Fojón, Papers in Physics 9, 090006 (2017

  9. Quorum sensing molecules production by nosocomial and soil isolates Acinetobacter baumannii.

    Science.gov (United States)

    Erdönmez, Demet; Rad, Abbas Yousefi; Aksöz, Nilüfer

    2017-12-01

    Acinetobacter species remain alive in hospitals on various surfaces, both dry and moist, forming an important source of hospital infections. These bacteria are naturally resistant to many antibiotic classes. Although the role of the quorum sensing system in regulating the virulence factors of Acinetobacter species has not been fully elucidated, it has been reported that they play a role in bacterial biofilm formation. The biofilm formation helps them to survive under unfavorable growth conditions and antimicrobial treatments. It is based on the accumulation of bacterial communication signal molecules in the area. In this study, we compared the bacterial signal molecules of 50 nosocomial Acinetobacter baumannii strain and 20 A. baumannii strain isolated from soil. The signal molecules were detected by the biosensor bacteria (Chromobacterium violaceum 026, Agrobacterium tumefaciens A136, and Agrobacterium tumefaciens NTL1) and their separation was determined by thin-layer chromatography. As a result, it has been found that soil-borne isolates can produce 3-oxo-C8-AHL and C8-AHL, whereas nosocomial-derived isolates can produce long-chain signals such as C10-AHL, C12-AHL, C14-AHL and C16-AHL. According to these results, it is possible to understand that these signal molecules are found in the infection caused by A. baumannii. The inhibition of this signaling molecules in a communication could use to prevent multiple antibiotic resistance of these bacteria.

  10. Quantification of ion-induced molecular fragmentation of isolated 2-deoxy-D-ribose molecules

    NARCIS (Netherlands)

    Alvarado Chacon, F.; Bari, S.; Hoekstra, R.A.; Schlathölter, T.A.

    2006-01-01

    Recent experiments on low energy ion-induced damage to DNA building blocks indicate that ion induced DNA damage is dominated by deoxyribose disintegration (Phys. Rev. Lett., 2005, 95, 153201). We have studied interactions of keV H+ and Heq+ with isolated deoxyribose molecules by means of high

  11. Scattering of thermal neutron by the water molecule

    International Nuclear Information System (INIS)

    Rosa, L.P.

    The calculation of the differenctial cross section for scattering of thermal neutrons by water, taking into account the translational, rotational and vibrational motions of the water molecule, is presented according to Nelkin' model. Some modifications are presented which have been introduced in the original method to improve the results and an application has been made to reactor physics, by calculating the thermal neutron flux in a homogenous medium containing water and absorver. Thirty thermal energy groups have been used to compute the spectra. Within the limits of error, better agreement has been obtained between theory and experiments by using a modified Nelkin kernel consisting of substituting the asymptotic formulae for the rotational and vibrational motions by more exact expressions, similar to the Buttler model for heavy water

  12. The T-cell accessory molecule CD4 recognizes a monomorphic determinant on isolated Ia

    DEFF Research Database (Denmark)

    Gay, D; Buus, S; Pasternak, J

    1988-01-01

    The membrane protein CD4 is commonly found on mature T cells specific for antigen in association with class II major histocompatibility complex (MHC; Ia) proteins. This correlation has led to the suggestion that CD4 binds to a monomorphic region of the Ia molecule on the antigen-presenting cell...... proteins into a planar membrane system, we show that different Ia molecules can greatly enhance the ability of a CD4+ but not a CD4- variant of this class I-restricted T hybrid to respond to isolated class I molecules. T-cell responses can be strongly augmented by the concurrent expression of CD4 on the T...... cell and any of four different Ia proteins on planar membranes, thus supporting the idea that CD4 binds to a monomorphic region of the Ia molecule and increases the avidity with which the T cell can interact with its target....

  13. STICKING OF MOLECULES ON NONPOROUS AMORPHOUS WATER ICE

    Energy Technology Data Exchange (ETDEWEB)

    He, Jiao; Vidali, Gianfranco [Physics Department, Syracuse University, Syracuse, NY 13244 (United States); Acharyya, Kinsuk, E-mail: gvidali@syr.edu [Department of Chemistry, University of Virginia, Charlottesville, VA 22904 (United States)

    2016-05-20

    Accurate modeling of physical and chemical processes in the interstellar medium (ISM) requires detailed knowledge of how atoms and molecules adsorb on dust grains. However, the sticking coefficient, a number between 0 and 1 that measures the first step in the interaction of a particle with a surface, is usually assumed in simulations of ISM environments to be either 0.5 or 1. Here we report on the determination of the sticking coefficient of H{sub 2}, D{sub 2}, N{sub 2}, O{sub 2}, CO, CH{sub 4}, and CO{sub 2} on nonporous amorphous solid water. The sticking coefficient was measured over a wide range of surface temperatures using a highly collimated molecular beam. We showed that the standard way of measuring the sticking coefficient—the King–Wells method—leads to the underestimation of trapping events in which there is incomplete energy accommodation of the molecule on the surface. Surface scattering experiments with the use of a pulsed molecular beam are used instead to measure the sticking coefficient. Based on the values of the measured sticking coefficient, we suggest a useful general formula of the sticking coefficient as a function of grain temperature and molecule-surface binding energy. We use this formula in a simulation of ISM gas–grain chemistry to find the effect of sticking on the abundance of key molecules both on grains and in the gas phase.

  14. The spontaneous synchronized dance of pairs of water molecules

    International Nuclear Information System (INIS)

    Roncaratti, Luiz F.; Cappelletti, David; Pirani, Fernando

    2014-01-01

    Molecular beam scattering experiments have been performed to study the effect of long-range anisotropic forces on the collision dynamics of two small polar molecules. The main focus of this paper is on water, but also ammonia and hydrogen sulphide molecules have been investigated, and some results will be anticipated. The intermolecular distances mainly probed are of the order of 1 nm and therefore much larger than the molecular dimensions. In particular, we have found that the natural electric field gradient, generated by different spatial orientations of the permanent electric dipoles, is able to promote the transformation of free rotations into coupled pendular states, letting the molecular partners involved in the collision complex swinging to and fro around the field direction. This long-ranged concerted motion manifested itself as large increases of the magnitude of the total integral cross section. The experimental findings and the theoretical treatment developed to shed light on the details of the process suggest that the transformation from free rotations to pendular states depends on the rotational level of both molecules, on the impact parameter, on the relative collision velocity, on the dipole moment product and occurs in the time scale of picoseconds. The consequences of this intriguing phenomenon may be important for the interpretation and, in perspective, for the control of elementary chemical and biological processes, given by polar molecules, ions, and free radicals, occurring in several environments under various conditions

  15. The spontaneous synchronized dance of pairs of water molecules

    Energy Technology Data Exchange (ETDEWEB)

    Roncaratti, Luiz F. [Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia (Italy); Instituto de Física, Universidade de Brasília, 70910-900 Brasília (Brazil); Cappelletti, David, E-mail: david.cappelletti@unipg.it; Pirani, Fernando [Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia (Italy)

    2014-03-28

    Molecular beam scattering experiments have been performed to study the effect of long-range anisotropic forces on the collision dynamics of two small polar molecules. The main focus of this paper is on water, but also ammonia and hydrogen sulphide molecules have been investigated, and some results will be anticipated. The intermolecular distances mainly probed are of the order of 1 nm and therefore much larger than the molecular dimensions. In particular, we have found that the natural electric field gradient, generated by different spatial orientations of the permanent electric dipoles, is able to promote the transformation of free rotations into coupled pendular states, letting the molecular partners involved in the collision complex swinging to and fro around the field direction. This long-ranged concerted motion manifested itself as large increases of the magnitude of the total integral cross section. The experimental findings and the theoretical treatment developed to shed light on the details of the process suggest that the transformation from free rotations to pendular states depends on the rotational level of both molecules, on the impact parameter, on the relative collision velocity, on the dipole moment product and occurs in the time scale of picoseconds. The consequences of this intriguing phenomenon may be important for the interpretation and, in perspective, for the control of elementary chemical and biological processes, given by polar molecules, ions, and free radicals, occurring in several environments under various conditions.

  16. Electric dipole moments of nanosolvated acid molecules in water clusters.

    Science.gov (United States)

    Guggemos, Nicholas; Slavíček, Petr; Kresin, Vitaly V

    2015-01-30

    The electric dipole moments of (H2O)nDCl (n=3-9) clusters have been measured by the beam-deflection method. Reflecting the (dynamical) charge distribution within the system, the dipole moment contributes information about the microscopic structure of nanoscale solvation. The addition of a DCl molecule to a water cluster results in a strongly enhanced susceptibility. There is evidence for a noticeable rise in the dipole moment occurring at n≈5-6. This size is consistent with predictions for the onset of ionic dissociation. Additionally, a molecular-dynamics model suggests that even with a nominally bound impurity an enhanced dipole moment can arise due to the thermal and zero-point motion of the proton and the water molecules. The experimental measurements and the calculations draw attention to the importance of fluctuations in defining the polarity of water-based nanoclusters and generally to the essential role played by motional effects in determining the response of fluxional nanoscale systems under realistic conditions.

  17. Hydrogen bonding characterization in water and small molecules

    Science.gov (United States)

    Silvestrelli, Pier Luigi

    2017-06-01

    The prototypical hydrogen bond in water dimer and hydrogen bonds in the protonated water dimer, in other small molecules, in water cyclic clusters, and in ice, covering a wide range of bond strengths, are theoretically investigated by first-principles calculations based on density functional theory, considering not only a standard generalized gradient approximation functional but also, for the water dimer, hybrid and van der Waals corrected functionals. We compute structural, energetic, and electrostatic (induced molecular dipole moments) properties. In particular, hydrogen bonds are characterized in terms of differential electron density distributions and profiles, and of the shifts of the centres of maximally localized Wannier functions. The information from the latter quantities can be conveyed to a single geometric bonding parameter that appears to be correlated with the Mayer bond order parameter and can be taken as an estimate of the covalent contribution to the hydrogen bond. By considering the water trimer, the cyclic water hexamer, and the hexagonal phase of ice, we also elucidate the importance of cooperative/anticooperative effects in hydrogen-bonding formation.

  18. Continuum simulations of water flow past fullerene molecules

    DEFF Research Database (Denmark)

    Popadic, A.; Praprotnik, M.; Koumoutsakos, P.

    2015-01-01

    We present continuum simulations of water flow past fullerene molecules. The governing Navier-Stokes equations are complemented with the Navier slip boundary condition with a slip length that is extracted from related molecular dynamics simulations. We find that several quantities of interest...... as computed by the present model are in good agreement with results from atomistic and atomistic-continuum simulations at a fraction of the cost. We simulate the flow past a single fullerene and an array of fullerenes and demonstrate that such nanoscale flows can be computed efficiently by continuum flow...

  19. Selective control of photodissociation in deutereted water molecule HOD

    International Nuclear Information System (INIS)

    Adhikari, S.; Deshpande, Sarin; Sarma, Manabendra; Kurkal, Vandana; Mishra, M.K.

    2006-01-01

    Bond dissociation in the deutereted water molecule HOD has been investigated to explore the possibility of selective control of dissociation of O-H and O-D bonds using simple field profiles and initial states that do not require high overtone excitations. Preliminary results indicate that considerable selectivity in dissociation of O-H and O-D bonds can be achieved using fundamental and first overtone excitations only and use of field optimized initial state (FOIST) based scheme with appropriate choice of field parameters and initial states may enhance both selectivity and yield

  20. Why Do Simple Molecules with "Isolated" Phenyl Rings Emit Visible Light?

    Science.gov (United States)

    Zhang, Haoke; Zheng, Xiaoyan; Xie, Ni; He, Zikai; Liu, Junkai; Leung, Nelson L C; Niu, Yingli; Huang, Xuhui; Wong, Kam Sing; Kwok, Ryan T K; Sung, Herman H Y; Williams, Ian D; Qin, Anjun; Lam, Jacky W Y; Tang, Ben Zhong

    2017-11-15

    π-Bonds connected with aromatic rings were generally believed as the standard structures for constructing highly efficient fluorophores. Materials without these typical structures, however, exhibited only low fluorescence quantum yields and emitted in the ultraviolet spectral region. In this work, three molecules, namely bis(2,4,5-trimethylphenyl)methane, 1,1,2,2-tetrakis(2,4,5-trimethylphenyl)ethane, and 1,1,2,2-tetraphenylethane, with nonconjugated structures and isolated phenyl rings were synthesized and their photophysical properties were systematically investigated. Interestingly, the emission spectra of these three molecules could be well extended to 600 nm with high solid-state quantum yields of up to 70%. Experimental and theoretical analyses proved that intramolecular through-space conjugation between the "isolated" phenyl rings played an important role for this abnormal phenomenon.

  1. Molecular dynamics study of water molecule diffusion in oil-paper insulation materials

    International Nuclear Information System (INIS)

    Liao Ruijin; Zhu Mengzhao; Yang Lijun; Zhou Xin; Gong Chunyan

    2011-01-01

    Moisture is an important factor that influences the safe operation of transformers. In this study, molecular dynamics was employed to investigate the diffusion behavior of water molecules in the oil-paper insulation materials of transformers. Two oil-cellulose models were built. In the first model, water molecules were initially distributed in oil, and in the second model, water molecules were distributed in cellulose. The non-bonding energies of interaction between water molecules and oil, and between water molecules and cellulose, were calculated by the Dreiding force field. The interaction energy was found to play a dominant role in influencing the equilibrium distribution of water molecules. The radial direction functions of water molecules toward oil and cellulose indicate that the hydrogen bonds between water molecules and cellulose are sufficiently strong to withstand the operating temperature of the transformer. Mean-square displacement analysis of water molecules diffusion suggests that water molecules initially distributed in oil showed anisotropic diffusion; they tended to diffuse toward cellulose. Water molecules initially distributed in cellulose diffused isotropically. This study provides a theoretical contribution for improvements in online monitoring of water in transformers, and for subsequent research on new insulation materials.

  2. Molecular dynamics study of water molecule diffusion in oil-paper insulation materials

    Energy Technology Data Exchange (ETDEWEB)

    Liao Ruijin [State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing 400044 (China); Zhu Mengzhao, E-mail: xiaozhupost@163.co [State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing 400044 (China); Yang Lijun; Zhou Xin; Gong Chunyan [State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing 400044 (China)

    2011-03-01

    Moisture is an important factor that influences the safe operation of transformers. In this study, molecular dynamics was employed to investigate the diffusion behavior of water molecules in the oil-paper insulation materials of transformers. Two oil-cellulose models were built. In the first model, water molecules were initially distributed in oil, and in the second model, water molecules were distributed in cellulose. The non-bonding energies of interaction between water molecules and oil, and between water molecules and cellulose, were calculated by the Dreiding force field. The interaction energy was found to play a dominant role in influencing the equilibrium distribution of water molecules. The radial direction functions of water molecules toward oil and cellulose indicate that the hydrogen bonds between water molecules and cellulose are sufficiently strong to withstand the operating temperature of the transformer. Mean-square displacement analysis of water molecules diffusion suggests that water molecules initially distributed in oil showed anisotropic diffusion; they tended to diffuse toward cellulose. Water molecules initially distributed in cellulose diffused isotropically. This study provides a theoretical contribution for improvements in online monitoring of water in transformers, and for subsequent research on new insulation materials.

  3. Water and nonelectrolyte permeability of isolated rat hepatocytes

    International Nuclear Information System (INIS)

    Alpini, G.; Garrick, R.A.; Jones, M.J.; Nunes, R.; Tavoloni, N.

    1986-01-01

    We have measured the diffusive permeability coefficients of isolated rat hepatocytes to 3 H 2 O, [ 14 C]urea, [ 14 C]erythritol, [ 14 C]mannitol, [ 3 H]sucrose, and [ 3 H]inulin, employing a technique previously developed for erythrocytes (Redwood et al., J. Gen. Physiol 64:706-729, 1974). Diffusion coefficients for the tracer molecules were measured in packed hepatocytes, supernatant fluid, and intracellular medium (lysed hepatocytes) and were calculated assuming one-dimensional semi-infinite diffusion through a homogeneous medium. By applying the series-parallel pathway model, the following permeability coefficients (10(-5) cm/sec) for the hepatocyte plasma membrane were obtained. 3 H 2 O, 98.6 +/- 18.4; [ 14 C]urea, 18.2 +/- 5.3; [ 14 C]erythritol, 4.8 +/- 1.6; [ 14 C]mannitol, 3.1 +/- 1.4; [ 3 H]sucrose, 0; [ 3 H]inulin, 0. These results indicate that isolated rat hepatocytes are highly permeable to water and polar nonelectrolytes, when compared with other transporting epithelia. This relatively high cellular permeability is consistent with a model in which nonelectrolyte permeation is via an aqueous pathway of equivalent pore diameter of 8-12 A. The finding that [ 14 C]erythritol and [ 14 C]mannitol cross the hepatocyte plasma membrane indicates that these molecules enter the bile canaliculus through the transcellular route. Conversely, the failure of [ 3 H]sucrose and [ 3 H]inulin to permeate the hepatocyte in the isolated condition supports the concept that biliary entry of these large carbohydrates, at least that fraction which cannot be accounted for by a vesicular mechanism, must occur via the transjunctional shunt pathway

  4. Approximative Krieger-Nelkin orientation averaging and anisotropy of water molecules vibrations

    International Nuclear Information System (INIS)

    Markovic, M.I.

    1974-01-01

    Quantum-mechanics approach of water molecules dynamics should be taken into account for precise theoretical calculation of differential scattering cross sections of neutrons. Krieger and Nelkin have proposed an approximate method for averaging orientation of molecules regarding directions of incoming and scattered neutron. This paper shows that this approach can be successfully applied for general shape of water molecule vibration anisotropy

  5. Identification and Characterization of Yeast Isolates from Pharmaceutical Waste Water

    Directory of Open Access Journals (Sweden)

    Marjeta Recek

    2002-01-01

    Full Text Available In order to develop an efficient an system for waste water pretreatment, the isolation of indigenous population of microorganisms from pharmaceutical waste water was done. We obtained pure cultures of 16 yeast isolates that differed slightly in colony morphology. Ten out of 16 isolates efficiently reduced COD in pharmaceutical waste water. Initial physiological characterization failed to match the 10 yeast isolates to either Pichia anomala or Pichia ciferrii. Restriction analysis of rDNA (rDNA-RFLP using three different restriction enzymes: HaeIII, MspI and CfoI, showed identical patterns of the isolates and Pichia anomala type strain. Separation of chromosomal DNAs of yeast isolates by the pulsed field gel electrophoresis revealed that the 10 isolates could be grouped into 6 karyotypes. Growth characteristics of the 6 isolates with distinct karyotypes were then studied in batch cultivation in pharmaceutical waste water for 80 hours.

  6. Isolation and identification of radiation resistant yeasts from sea water

    International Nuclear Information System (INIS)

    Park, Jong Cheon; Jeong, Yong Uk; Kim, Du Hong; Jo, Eun A

    2011-12-01

    This study was conducted to isolate radiation-resistant yeasts from sea water for development of application technology of radiation-resistant microorganism. · Isolation of 656 yeasts from sea water and selection of 2 radiation-resistant yeasts (D 10 value >3) · Identification of isolated yeasts as Filobasidium elegans sharing 99% sequence similarity · Characterization of isolated yeast with ability to repair of the DNA damage and membrane integrity to irradiation

  7. X-ray Diffraction from Isolated and Strongly Aligned Gas-Phase Molecules with a Free-Electron Laser

    DEFF Research Database (Denmark)

    Küpper, Jochen; Stern, Stephan; Holmegaard, Lotte

    2014-01-01

    We report experimental results on x-ray diffraction of quantum-state-selected and strongly aligned ensembles of the prototypical asymmetric rotor molecule 2,5-diiodobenzonitrile using the Linac Coherent Light Source. The experiments demonstrate first steps toward a new approach to diffractive...... imaging of distinct structures of individual, isolated gas-phase molecules. We confirm several key ingredients of single molecule diffraction experiments: the abilities to detect and count individual scattered x-ray photons in single shot diffraction data, to deliver state-selected, e. g., structural......-isomer-selected, ensembles of molecules to the x-ray interaction volume, and to strongly align the scattering molecules. Our approach, using ultrashort x-ray pulses, is suitable to study ultrafast dynamics of isolated molecules....

  8. Distribution of binding energies of a water molecule in the water liquid-vapor interface

    Energy Technology Data Exchange (ETDEWEB)

    Chempath, Shaji [Los Alamos National Laboratory; Pratt, Lawrence R [TULANE UNIV

    2008-01-01

    Distributions of binding energies of a water molecule in the water liquid-vapor interface are obtained on the basis of molecular simulation with the SPC/E model of water. These binding energies together with the observed interfacial density profile are used to test a minimally conditioned Gaussian quasi-chemical statistical thermodynamic theory. Binding energy distributions for water molecules in that interfacial region clearly exhibit a composite structure. A minimally conditioned Gaussian quasi-chemical model that is accurate for the free energy of bulk liquid water breaks down for water molecules in the liquid-vapor interfacial region. This breakdown is associated with the fact that this minimally conditioned Gaussian model would be inaccurate for the statistical thermodynamics of a dilute gas. Aggressive conditioning greatly improves the performance of that Gaussian quasi-chemical model. The analogy between the Gaussian quasi-chemical model and dielectric models of hydration free energies suggests that naive dielectric models without the conditioning features of quasi-chemical theory will be unreliable for these interfacial problems. Multi-Gaussian models that address the composite nature of the binding energy distributions observed in the interfacial region might provide a mechanism for correcting dielectric models for practical applications.

  9. Genetic Attributes of E. coli Isolates from Chlorinated Drinking Water.

    Science.gov (United States)

    Blyton, Michaela D J; Gordon, David M

    2017-01-01

    Escherichia coli, is intimately associated with both human health and water sanitation. E. coli isolates from water can either be (i) host associated commensals, indicating recent faecal contamination; (ii) diarrheal pathogens or (iii) extra-intestinal pathogens that pose a direct health risk; or (iv) free-living. In this study we genetically characterised 28 E. coli isolates obtained from treated drinking water in south eastern Australia to ascertain their likely source. We used full genome sequencing to assign the isolates to their phylogenetic group and multi-locus sequence type. The isolates were also screened in silico for several virulence genes and genes involved in acquired antibiotic resistance. The genetic characteristics of the isolates indicated that four isolates were likely human pathogens. However, these isolates were not detected in sufficient numbers to present a health risk to the public. An additional isolate was a human associated strain. Nine isolates were water associated free-living strains that were unlikely to pose a health risk. Only 14% of the isolates belonged to the host associated phylogenetic group (B2) and only a single isolate had any antibiotic resistance genes. This suggests that the primary source of the drinking water E. coli isolates may not have been recent human faecal contamination.

  10. Genetic Attributes of E. coli Isolates from Chlorinated Drinking Water.

    Directory of Open Access Journals (Sweden)

    Michaela D J Blyton

    Full Text Available Escherichia coli, is intimately associated with both human health and water sanitation. E. coli isolates from water can either be (i host associated commensals, indicating recent faecal contamination; (ii diarrheal pathogens or (iii extra-intestinal pathogens that pose a direct health risk; or (iv free-living. In this study we genetically characterised 28 E. coli isolates obtained from treated drinking water in south eastern Australia to ascertain their likely source. We used full genome sequencing to assign the isolates to their phylogenetic group and multi-locus sequence type. The isolates were also screened in silico for several virulence genes and genes involved in acquired antibiotic resistance. The genetic characteristics of the isolates indicated that four isolates were likely human pathogens. However, these isolates were not detected in sufficient numbers to present a health risk to the public. An additional isolate was a human associated strain. Nine isolates were water associated free-living strains that were unlikely to pose a health risk. Only 14% of the isolates belonged to the host associated phylogenetic group (B2 and only a single isolate had any antibiotic resistance genes. This suggests that the primary source of the drinking water E. coli isolates may not have been recent human faecal contamination.

  11. Effect of molecular structure on fragmentation of isolated organic molecules in solid rare gas matrices

    International Nuclear Information System (INIS)

    Kobzarenko, A.V.; Sukhov, F.F.; Orlov, A.Yu.; Kovalev, G.V.; Baranova, I.A.; Feldman, V.I.

    2012-01-01

    The effect of excess energy on the primary radical cations of bifunctional carbonyl compounds and aliphatic alkynes was simulated by matrix isolation method using rare gas matrices with various ionization potentials. The formation of fragmentation products was monitored by EPR and FTIR spectroscopy. It was shown that the radical cations of bifunctional compounds (CH 3 OCH 2 COCH 3 and CH 3 COCOCH 3 ) dissociated effectively yielding · CH 3 radicals upon irradiation in solid argon matrix at T≤16 K. In addition to isolated methyl radicals, the radical pairs consisting of two methyl radicals separated by two CO molecules were detected in the case of diacetyl. The probability of fragmentation decreases with the decreasing excess energy by switching from Ar to Xe. In general, bifunctional molecules were found to be less stable to “hot” ionic fragmentation in low-temperature solids in comparison with simple prototype compounds. In the case of alkynes of the R--C≡CH type, a noticeable yield of fragmentation products was observed when R=–C(CH 3 ) 3 , but it was negligible for R=–CH 3 . The mechanisms of “hot” reactions and excess energy relaxation are discussed. - Highlights: ► Radiolysis of bifunctional organic compounds and alkynes. ► Dependence of “hot” fragmentation probability from molecular structure. ► Ions of bifunctional compounds are less stable than those of monofunctional ones. ► Alkynes are rather stable to “hot” fragmentation.

  12. Rapid and accurate prediction and scoring of water molecules in protein binding sites.

    Directory of Open Access Journals (Sweden)

    Gregory A Ross

    Full Text Available Water plays a critical role in ligand-protein interactions. However, it is still challenging to predict accurately not only where water molecules prefer to bind, but also which of those water molecules might be displaceable. The latter is often seen as a route to optimizing affinity of potential drug candidates. Using a protocol we call WaterDock, we show that the freely available AutoDock Vina tool can be used to predict accurately the binding sites of water molecules. WaterDock was validated using data from X-ray crystallography, neutron diffraction and molecular dynamics simulations and correctly predicted 97% of the water molecules in the test set. In addition, we combined data-mining, heuristic and machine learning techniques to develop probabilistic water molecule classifiers. When applied to WaterDock predictions in the Astex Diverse Set of protein ligand complexes, we could identify whether a water molecule was conserved or displaced to an accuracy of 75%. A second model predicted whether water molecules were displaced by polar groups or by non-polar groups to an accuracy of 80%. These results should prove useful for anyone wishing to undertake rational design of new compounds where the displacement of water molecules is being considered as a route to improved affinity.

  13. Fast Rotational Diffusion of Water Molecules in a 2D Hydrogen Bond Network at Cryogenic Temperatures

    Science.gov (United States)

    Prisk, T. R.; Hoffmann, C.; Kolesnikov, A. I.; Mamontov, E.; Podlesnyak, A. A.; Wang, X.; Kent, P. R. C.; Anovitz, L. M.

    2018-05-01

    Individual water molecules or small clusters of water molecules contained within microporous minerals present an extreme case of confinement where the local structure of hydrogen bond networks are dramatically altered from bulk water. In the zinc silicate hemimorphite, the water molecules form a two-dimensional hydrogen bond network with hydroxyl groups in the crystal framework. Here, we present a combined experimental and theoretical study of the structure and dynamics of water molecules within this network. The water molecules undergo a continuous phase transition in their orientational configuration analogous to a two-dimensional Ising model. The incoherent dynamic structure factor reveals two thermally activated relaxation processes, one on a subpicosecond timescale and another on a 10-100 ps timescale, between 70 and 130 K. The slow process is an in-plane reorientation of the water molecule involving the breaking of hydrogen bonds with a framework that, despite the low temperatures involved, is analogous to rotational diffusion of water molecules in the bulk liquid. The fast process is a localized motion of the water molecule with no apparent analogs among known bulk or confined phases of water.

  14. Density, distribution, and orientation of water molecules inside and outside carbon nanotubes.

    Science.gov (United States)

    Thomas, J A; McGaughey, A J H

    2008-02-28

    The behavior of water molecules inside and outside 1.1, 2.8, 6.9, and 10.4 nm diameter armchair carbon nanotubes (CNTs) is predicted using molecular dynamics simulations. The effects of CNT diameter on mass density, molecular distribution, and molecular orientation are identified for both the confined and unconfined fluids. Within 1 nm of the CNT surface, unconfined water molecules assume a spatially varying density profile. The molecules distribute nonuniformly around the carbon surface and have preferred orientations. The behavior of the unconfined water molecules is invariant with CNT diameter. The behavior of the confined water, however, can be correlated to tube diameter. Inside the 10.4 nm CNT, the molecular behavior is indistinguishable from that of the unconfined fluid. Within the smaller CNTs, surface curvature effects reduce the equilibrium water density and force water molecules away from the surface. This effect changes both the molecular distribution and preferred molecular orientations.

  15. Effect of molecular structure on fragmentation of isolated organic molecules in solid rare gas matrices

    International Nuclear Information System (INIS)

    Kobrazenko, A.V.; Sukhov, F.F.; Orlov, A.Yu.; Kovalev, G.V.; Baranova, I.A.; Feldman, V.I.

    2011-01-01

    Complete text of publication follows. Elucidation of high-energy reaction pathways in the condensed phase is an important issue for basic understanding of the radiation stability of complex organic molecules. As was shown previously, organic radical cations (RC) may undergo fragmentation or rearrangement in solid matrices due to excess energy. The probability of this process depends on both ionization potential (IP) of the molecule and molecular structure. In the present work we have studied the role of 'hot' ionic reaction channels for RC of some bifunctional compounds and alkynes. The effect of excess energy was simulated by matrix isolation method as described in detail earlier. The formation of fragmentation products was monitored by EPR and FTIR spectroscopy. In the present work it was shown that the RC of bifunctional compounds (CH 3 OCH 2 COCH 3 , CH 3 CO(CH 2 ) n COCH 3 , n 0/2) dissociated efficiently producing · CH 3 radicals upon irradiation in solid argon matrix at T ≤ 16 K. The probability of fragmentation decreases with decrease of excess energy by switching from Ar to Xe. It is worth noting that acetone RC does not show fragmentation under these conditions. Thus, bifunctional molecules were found to be less stable to 'hot' ionic fragmentation in low-temperature solids in comparison with simple prototype carbonyl compounds. In the case of alkynes of the R-C ≡ CH type, a noticeable yield of fragmentation products was observed when R = -C(CH 3 ) 3 , but it was negligible for R = -CH 3 . It means that the presence of triple bond stabilizes the molecular skeleton of linear alkynes toward 'hot' fragmentation, similarly as it was shown for alkenes. The mechanisms of 'hot' reactions and excess energy relaxation are discussed. This work was supported by the Russian Foundation for Basic Research (project 09-03-00848a).

  16. Genomic and phenotypic characteristics of Swedish C. jejuni water isolates.

    Directory of Open Access Journals (Sweden)

    Anna Nilsson

    Full Text Available Campylobacter jejuni is the most common cause of bacterial gastroenteritis. Major reservoirs are warm-blooded animals, poultry in particular, but Campylobacter can also be transmitted via water. In this paper, we have taken a closer look at the biology and potential virulence of C. jejuni water isolates. Seven C. jejuni isolates from incoming surface water at water plants in Sweden were characterized with whole genome sequencing and phenotypical testing. Multi locus sequence typing analysis revealed that these isolates belonged to groups known to include both common (ST48CC and uncommon (ST1275CC, ST683, ST793 and ST8853 human pathogens. Further genomic characterization revealed that these isolates had potential for arsenic resistance (due to presence of arsB gene in all isolates, an anaerobic dimethyl sulfoxide oxidoreductase (in three isolates and lacked the MarR-type transcriptional regulator gene rrpB (in all but one isolate earlier shown to be involved in better survival under oxidative and aerobic stress. As putative virulence factors were concerned, there were differences between the water isolates in the presence of genes coding for cytolethal distending toxin (cdtABC, Type VI secretion system and sialylated LOS, as well as in biofilm formation. However, all isolates were motile and could adhere to and invade the human HT-29 colon cancer cell line in vitro and induce IL-8 secretion suggesting potential to infect humans. This is, to the best of our knowledge, the first study where C. jejuni water isolates have been characterized using whole genome sequencing and phenotypical assays. We found differences and shared traits among the isolates but also potential to infect humans.

  17. Diversity of Salmonella isolates from central Florida surface waters.

    Science.gov (United States)

    McEgan, Rachel; Chandler, Jeffrey C; Goodridge, Lawrence D; Danyluk, Michelle D

    2014-11-01

    Identification of Salmonella serotypes is important for understanding the environmental diversity of the genus Salmonella. This study evaluates the diversity of Salmonella isolates recovered from 165 of 202 Central Florida surface water samples and investigates whether the serotype of the environmental Salmonella isolates can be predicted by a previously published multiplex PCR assay (S. Kim, J. G. Frye, J. Hu, P. J. Fedorka-Cray, R. Gautom, and D. S. Boyle, J. Clin. Microbiol. 44:3608-3615, 2006, http://dx.doi.org/10.1128/JCM.00701-06). Multiplex PCR was performed on 562 Salmonella isolates (as many as 36 isolates per water sample) to predict serotypes. Kauffmann-White serogrouping was used to confirm multiplex PCR pattern groupings before isolates were serotyped, analyzed by pulsed-field gel electrophoresis, and assayed for antimicrobial susceptibility. In 41.2% of the Salmonella-positive water samples, all Salmonella isolates had identical multiplex PCR patterns; in the remaining 58.8%, two or more multiplex PCR patterns were identified. Within each sample, isolates with matching multiplex PCR patterns had matching serogroups. The multiplex patterns of 495 isolates (88.1%) did not match any previously reported pattern. The remaining 68 isolates matched reported patterns but did not match the serotypes for those patterns. The use of the multiplex PCR allowed the number of isolates requiring further analysis to be reduced to 223. Thirty-three Salmonella enterica serotypes were identified; the most frequent included serotypes Muenchen, Rubislaw, Anatum, Gaminara, and IV_50:z4,z23:-. A majority (141/223) of Salmonella isolates clustered into one genotypic group. Salmonella isolates in Central Florida surface waters are serotypically, genotypically, and phenotypically (in terms of antimicrobial susceptibility) diverse. While isolates could be grouped as different or potentially the same using multiplex PCR, the multiplex PCR pattern did not predict the Salmonella

  18. Influence of orientation averaging on the anisotropy of thermal neutrons scattering on water molecules

    International Nuclear Information System (INIS)

    Markovic, M. I.; Radunovic, J. B.

    1976-01-01

    Determination of spatial distribution of neutron flux in water, most frequently used moderator in thermal reactors, demands microscopic scattering kernels dependence on cosine of thermal neutrons scattering angle when solving the Boltzmann equation. Since spatial orientation of water molecules influences this dependence it is necessary to perform orientation averaging or rotation-vibrational intermediate scattering function for water molecules. The calculations described in this paper and the obtained results showed that methods of orientation averaging do not influence the anisotropy of thermal neutrons scattering on water molecules, but do influence the inelastic scattering

  19. On the trends of Fukui potential and hardness potential derivatives in isolated atoms vs. atoms in molecules.

    Science.gov (United States)

    Bhattacharjee, Rituparna; Roy, Ram Kinkar

    2014-10-28

    In the present study, trends of electronic contribution to molecular electrostatic potential [Vel(r¯)(r=0)], Fukui potential [v(+)f|(r=0) and v(-)f|(r=0)] and hardness potential derivatives [Δ(+)h(k) and Δ(-)h(k)] for isolated atoms as well as atoms in molecules are investigated. The generated numerical values of these three reactivity descriptors in these two electronically different situations are critically analyzed through the relevant formalism. Values of Vel(r¯) (when r → 0, i.e., on the nucleus) are higher for atoms in molecules than that of isolated atoms. In contrast, higher values of v(+)|(r=0) and v(-)|(r=0) are observed for isolated atoms compared to the values for atoms in a molecule. However, no such regular trend is observed for the Δ(+)h(k) and Δ(-)h(k) values, which is attributed to the uncertainty in the Fukui function values of atoms in molecules. The sum of Fukui potential and the sum of hardness potential derivatives in molecules are also critically analyzed, which shows the efficacy of orbital relaxation effects in quantifying the values of these parameters. The chemical consequence of the observed trends of these descriptors in interpreting electron delocalization, electronic relaxation and non-negativity of atomic Fukui function indices is also touched upon. Several commonly used molecules containing carbon as well as heteroatoms are chosen to make the investigation more insightful.

  20. The mechanism of 2-dimensional manipulation of DNA molecules by water and ethanol flows

    International Nuclear Information System (INIS)

    Shen Zigang; Huang Yibo; Li Bin; Zhang Yi

    2007-01-01

    Due to its unique physical and chemical properties, DNA has recently become a promising material for building blocks in nanofabrication. Many researches focus on how to use DNA molecules as a template for nanowires. Molecular Combing technique is one of important methods to manipulate DNA molecules by using a water meniscus and form specific DNA nano-structures on surfaces. In this paper, by employing a modified molecular combing technique, special patterns of DNA molecules was formed, and the interaction between liquid flows or meniscus and DNA molecules was analyzed, and the mechanism of manipulating DNA molecules by liquid was studied. (authors)

  1. Isolation of viruses from drinking water at the Point-Viau water treatment plant

    Energy Technology Data Exchange (ETDEWEB)

    Payment, P.

    1981-04-01

    Viruses were isolated from every sample of raw (100 L) and treated (1000 L) water collected at a water treatment plant drawing sewage-contaminated river water. Few plaque-forming isolates were formed but cytopathogenic viruses were isolated as frequently in drinking water as in raw water. In drinking water some samples contained more than 1 cytopathogenic unit per litre, but most contained 1-10/100 L. These viruses had not been inactivated or removed by prechlorination, flocculation, filtration, ozonation, and postchlorination. There were no coliforms present and a residual chlorine level had been maintained. Poliovirus type 1 was a frequent isolate but many isolates were nonpoliovirus. The presence of these viruses in drinking water raises questions about the efficacy of some water treatment processes to remove viruses from polluted water.

  2. Implication of Crystal Water Molecules in Inhibitor Binding at ALR2 Active Site

    Directory of Open Access Journals (Sweden)

    Hymavati

    2012-01-01

    Full Text Available Water molecules play a crucial role in mediating the interaction between a ligand and a macromolecule. The solvent environment around such biomolecule controls their structure and plays important role in protein-ligand interactions. An understanding of the nature and role of these water molecules in the active site of a protein could greatly increase the efficiency of rational drug design approaches. We have performed the comparative crystal structure analysis of aldose reductase to understand the role of crystal water in protein-ligand interaction. Molecular dynamics simulation has shown the versatile nature of water molecules in bridge H bonding during interaction. Occupancy and life time of water molecules depend on the type of cocrystallized ligand present in the structure. The information may be useful in rational approach to customize the ligand, and thereby longer occupancy and life time for bridge H-bonding.

  3. Isolation and Purification of an Early Pregnancy Factor–Like Molecule from Culture Supernatants Obtained from Lymphocytes of Pregnant Women

    OpenAIRE

    Aranha, Clara; Natraj, Usha; Iyer, K. S.; Shahani, Savitri

    1998-01-01

    Purpose:Our purpose was to determine whether lymphocytes synthesize proteins during pregnancy, to observe whether one of the proteins synthesized has early pregnancy factor (EPF)–like activity and to isolate and purify this molecule from culture supernatants obtained from stimulated lymphocytes of pregnant women.

  4. From isolated light-harvesting complexes to the thylakoid membrane: a single-molecule perspective

    Science.gov (United States)

    Gruber, J. Michael; Malý, Pavel; Krüger, Tjaart P. J.; Grondelle, Rienk van

    2018-01-01

    The conversion of solar radiation to chemical energy in plants and green algae takes place in the thylakoid membrane. This amphiphilic environment hosts a complex arrangement of light-harvesting pigment-protein complexes that absorb light and transfer the excitation energy to photochemically active reaction centers. This efficient light-harvesting capacity is moreover tightly regulated by a photoprotective mechanism called non-photochemical quenching to avoid the stress-induced destruction of the catalytic reaction center. In this review we provide an overview of single-molecule fluorescence measurements on plant light-harvesting complexes (LHCs) of varying sizes with the aim of bridging the gap between the smallest isolated complexes, which have been well-characterized, and the native photosystem. The smallest complexes contain only a small number (10-20) of interacting chlorophylls, while the native photosystem contains dozens of protein subunits and many hundreds of connected pigments. We discuss the functional significance of conformational dynamics, the lipid environment, and the structural arrangement of this fascinating nano-machinery. The described experimental results can be utilized to build mathematical-physical models in a bottom-up approach, which can then be tested on larger in vivo systems. The results also clearly showcase the general property of biological systems to utilize the same system properties for different purposes. In this case it is the regulated conformational flexibility that allows LHCs to switch between efficient light-harvesting and a photoprotective function.

  5. Femtosecond spectroscopic study of the solvation of amphiphilic molecules by water

    NARCIS (Netherlands)

    Rezus, Y.L.A.; Bakker, H.J.

    2008-01-01

    We use polarization-resolved mid-infrared pump-probe spectroscopy to study the aqueous solvation of proline and N-methylacetamide. These molecules serve as models to study the solvation of proteins. We monitor the orientational dynamics of partly deuterated water molecules (HDO) that are present at

  6. Dynamics of water molecules in the active-site cavity of human cytochromes P450

    DEFF Research Database (Denmark)

    Rydberg, Patrik; Rod, Thomas Holm; Olsen, Lars

    2007-01-01

    We have studied the dynamics of water molecules in six crystal structures of four human cytochromes P450, 2A6, 2C8, 2C9, and 3A4, with molecular dynamics simulations. In the crystal structures, only a few water molecules are seen and the reported sizes of the active-site cavity vary a lot....... In the simulations, the cavities are completely filled with water molecules, although with approximately 20% lower density than in bulk water. The 2A6 protein differs from the other three in that it has a very small cavity with only two water molecules and no exchange with the surroundings. The other three proteins...... channels, through which there is a quite frequent exchange of water molecules (one molecule is exchanged every 30-200 ps), except in 2A6. Most of the channels are observed also in the crystal structures, but two to three channels in each protein open only during the simulations. There are no water...

  7. Algoriphagus shivajiensis sp. nov., isolated from Cochin back water, India

    Digital Repository Service at National Institute of Oceanography (India)

    AnilKumar, P.; Bhumika, V.; Ritika, C; VijayaBhaskar, Y.; Priyashanth, P.; Aravind, R.; Bindu, E.; Srinivas, T.N.R.

    Novel orange-pigmented, Gram-negative, rod-shaped, non-motile bacteria, designated strains NIO-S3 sup(T) and NIO-S4, were isolated from a water sample collected from Cochin back waters, Thanneermukkom and Arookutty, Kerala, India. Both strains were...

  8. Structural Arrangement of Water Molecules around Highly Charged Nanoparticles: Molecular Dynamics Simulation

    International Nuclear Information System (INIS)

    Kim, Eunae; Yeom, Min Sun

    2014-01-01

    Molecular dynamics simulations were performed to understand the structural arrangement of water molecules around highly charged nanoparticles under aqueous conditions. The effect of two highly charged nanoparticles on the solvation charge asymmetry has been examined. We calculated the radial distribution functions of the components of water molecules around nanoparticles which have four charge types at two different salt concentrations. Even though the distributions of water molecules surrounding a sodium ion and a chloride ion are hardly affected by the charges of nanoparticles and the salt concentrations, those around highly charged nanoparticles are strongly influenced by the charges of nanoparticles, but hardly by the charges of nanoparticles and salt concentrations. We find that the distributions of hydrogen atoms in water molecules around one highly charged nanoparticle are dependent on the magnitude of the nanoparticle charge

  9. Quantum Electric Dipole Lattice - Water Molecules Confined to Nanocavities in Beryl

    Science.gov (United States)

    Dressel, Martin; Zhukova, Elena S.; Thomas, Victor G.; Gorshunov, Boris P.

    2018-02-01

    Water is subject to intense investigations due to its importance in biological matter but keeps many of its secrets. Here, we unveil an even other aspect by confining H2O molecules to nanosize cages. Our THz and infrared spectra of water in the gemstone beryl evidence quantum tunneling of H2O molecules in the crystal lattice. The water molecules are spread out when confined in a nanocage. In combination with low-frequency dielectric measurements, we were also able to show that dipolar coupling among the H2O molecules leads towards a ferroelectric state at low temperatures. Upon cooling, a ferroelectric soft mode shifts through the THz range. Only quantum fluctuations prevent perfect macroscopic order to be fully achieved. Beside the significance to life science and possible application, nanoconfined water may become the prime example of a quantum electric dipolar lattice.

  10. Identification of intrinsic catalytic activity for electrochemical reduction of water molecules to generate hydrogen

    KAUST Repository

    Shinagawa, Tatsuya; Takanabe, Kazuhiro

    2015-01-01

    Insufficient hydronium ion activities at near-neutral pH and under unbuffered conditions induce diffusion-limited currents for hydrogen evolution, followed by a reaction with water molecules to generate hydrogen at elevated potentials. The observed

  11. Diverse bacteria isolated from microtherm oil-production water.

    Science.gov (United States)

    Sun, Ji-Quan; Xu, Lian; Zhang, Zhao; Li, Yan; Tang, Yue-Qin; Wu, Xiao-Lei

    2014-02-01

    In total, 435 pure bacterial strains were isolated from microtherm oil-production water from the Karamay Oilfield, Xinjiang, China, by using four media: oil-production water medium (Cai medium), oil-production water supplemented with mineral salt medium (CW medium), oil-production water supplemented with yeast extract medium (CY medium), and blood agar medium (X medium). The bacterial isolates were affiliated with 61 phylogenetic groups that belong to 32 genera in the phyla Actinobacteria, Firmicutes, and Proteobacteria. Except for the Rhizobium, Dietzia, and Pseudomonas strains that were isolated using all the four media, using different media led to the isolation of bacteria with different functions. Similarly, nonheme diiron alkane monooxygenase genes (alkB/alkM) also clustered according to the isolation medium. Among the bacterial strains, more than 24 % of the isolates could use n-hexadecane as the sole carbon source for growth. For the first time, the alkane-degrading ability and alkB/alkM were detected in Rhizobium, Rhodobacter, Trichococcus, Micrococcus, Enterococcus, and Bavariicoccus strains, and the alkM gene was detected in Firmicutes strains.

  12. Effects of 31 FDA approved small-molecule kinase inhibitors on isolated rat liver mitochondria.

    Science.gov (United States)

    Zhang, Jun; Salminen, Alec; Yang, Xi; Luo, Yong; Wu, Qiangen; White, Matthew; Greenhaw, James; Ren, Lijun; Bryant, Matthew; Salminen, William; Papoian, Thomas; Mattes, William; Shi, Qiang

    2017-08-01

    The FDA has approved 31 small-molecule kinase inhibitors (KIs) for human use as of November 2016, with six having black box warnings for hepatotoxicity (BBW-H) in product labeling. The precise mechanisms and risk factors for KI-induced hepatotoxicity are poorly understood. Here, the 31 KIs were tested in isolated rat liver mitochondria, an in vitro system recently proposed to be a useful tool to predict drug-induced hepatotoxicity in humans. The KIs were incubated with mitochondria or submitochondrial particles at concentrations ranging from therapeutic maximal blood concentrations (Cmax) levels to 100-fold Cmax levels. Ten endpoints were measured, including oxygen consumption rate, inner membrane potential, cytochrome c release, swelling, reactive oxygen species, and individual respiratory chain complex (I-V) activities. Of the 31 KIs examined only three including sorafenib, regorafenib and pazopanib, all of which are hepatotoxic, caused significant mitochondrial toxicity at concentrations equal to the Cmax, indicating that mitochondrial toxicity likely contributes to the pathogenesis of hepatotoxicity associated with these KIs. At concentrations equal to 100-fold Cmax, 18 KIs were found to be toxic to mitochondria, and among six KIs with BBW-H, mitochondrial injury was induced by regorafenib, lapatinib, idelalisib, and pazopanib, but not ponatinib, or sunitinib. Mitochondrial liability at 100-fold Cmax had a positive predictive power (PPV) of 72% and negative predictive power (NPV) of 33% in predicting human KI hepatotoxicity as defined by product labeling, with the sensitivity and specificity being 62% and 44%, respectively. Similar predictive power was obtained using the criterion of Cmax ≥1.1 µM or daily dose ≥100 mg. Mitochondrial liability at 1-2.5-fold Cmax showed a 100% PPV and specificity, though the NPV and sensitivity were 32% and 14%, respectively. These data provide novel mechanistic insights into KI hepatotoxicity and indicate that

  13. Adsorptionof polar organic molecules at oil/water interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Aveyard, R; Chapman, J

    1975-03-15

    A study has been made of the adsorption of several esters of dicarboxylic acids at the alkane/water and the air/water interface. The adsorption of n-butanol and n-heptanol at the air/water surface also has been investigated. The surface pressure (pi) -surface area (A) isotherms are compared for the various films, and standard free energies of adsorption have been determined. Attempts have been made to fit the pi, A isotherms using surface equations of state based on the models, of both a 2-dimensional gas and a 2-dimensional solution. The solution model has proved reasonably successful for fairly dilute films at the air/water surface. At higher coverages, an equation derived by Smith for liquid expanded monolayers gives a moderately good description of films of heptanol on water. A simple application of the solution model on adsorbed monolayers at the liquid; liquid interface met with little success. However, it is found that 2-dimensional gas equations describe such systems surprisingly well for fairly low surface concentrations. (20 refs.)

  14. Roles of water molecules in bacteria and viruses

    Science.gov (United States)

    Cox, C. S.

    1993-02-01

    In addition to water, microbes mainly comprise lipids, carbohydrates, proteins and nucleic acids. Their structure and function singularly and conjointly is affected by water activity. Desiccation leads to dramatic lipid phase changes whereas carbohydrates, proteins and nucleic acids initially suffer spontaneous, reversible low activation energy Maillard reactions forming products that more slowly re-arrange, cross-link etc. to give non-native states. While initial products spontaneously may reverse to native states by raising water activity, later products only do so through energy consumption and enzymatic activity eg. repair. Yet, native states of lipid membranes and associated enzymes are required to generate energy. Consequently, good reserves of high energy compounds (e.g. ATP) and of membrane stabilisers (e.g. trehalose) may be expected to enhance survival following drying and rehydration (e.g. anhydrobiotic organisms).

  15. Putative radioresistant bacterial isolate from sewage water

    International Nuclear Information System (INIS)

    Ang, April; Chua, Patricia; Perez, Kristine; Rey, April; Rivor Kristel; San Pablo, Czarina; Santos, Ernestine

    2001-01-01

    Sewage water was collected from a stagnant body of water in Balara, Quezon City. approximately 150 ml was aseptically transferred into eight Erlenmeyer flasks. Seven flasks were then subjected to different doses of radiation at the 60 Co irradiation facility, PNRI (Philippine Nuclear Research Institute) which are as follows: 0.01 kGy, 0.1 kGy, 0.5 kGy, 1 kGy, 5 kGy, 10 kGy, and 15 kGy. The remaining flask was used as the control. After irradiation, all the different treatments were subjected to colony count at the culture collection laboratory, NSRI. Results showed that the colonies from sewage water treatments irradiated at 0.01 kGy (treatment A), 0.10 kGy (treatment B), and 0.50 kGy (treatment C) exhibited a decreasing trend with colony counts 4.60 x 10 3 CFU/ml, and 1.30 x 10 3 CFU/ml, and 26 CFU/ml, respectively. Contrastingly, at 1 kGy (treatment D), high colony count of 2.95 x 10 3 CFU/ml was observed which is even higher compared to the control (1.02 x 10 3 CFU/ml). Treatment E that was irradiated at 5 kGy manifested low survival rate (25 CFU/ml) indicating the presence of few putative intermediate radioresistant bacteria. Radiation dose treatments higher than 5 kGy (i.e., 10 kGy and 15 kGy) exhibited no bacterial survival. (Author)

  16. Putative radioresistant bacterial isolate from sewage water

    Energy Technology Data Exchange (ETDEWEB)

    Ang, April; Chua, Patricia; Perez, Kristine; Rey, April; Kristel, Rivor; San Pablo, Czarina; Santos, Ernestine

    2001-01-29

    Sewage water was collected from a stagnant body of water in Balara, Quezon City. approximately 150 ml was aseptically transferred into eight Erlenmeyer flasks. Seven flasks were then subjected to different doses of radiation at the {sup 60}Co irradiation facility, PNRI (Philippine Nuclear Research Institute) which are as follows: 0.01 kGy, 0.1 kGy, 0.5 kGy, 1 kGy, 5 kGy, 10 kGy, and 15 kGy. The remaining flask was used as the control. After irradiation, all the different treatments were subjected to colony count at the culture collection laboratory, NSRI. Results showed that the colonies from sewage water treatments irradiated at 0.01 kGy (treatment A), 0.10 kGy (treatment B), and 0.50 kGy (treatment C) exhibited a decreasing trend with colony counts 4.60 x 10{sup 3} CFU/ml, and 1.30 x 10{sup 3} CFU/ml, and 26 CFU/ml, respectively. Contrastingly, at 1 kGy (treatment D), high colony count of 2.95 x 10{sup 3} CFU/ml was observed which is even higher compared to the control (1.02 x 10{sup 3} CFU/ml). Treatment E that was irradiated at 5 kGy manifested low survival rate (25 CFU/ml) indicating the presence of few putative intermediate radioresistant bacteria. Radiation dose treatments higher than 5 kGy (i.e., 10 kGy and 15 kGy) exhibited no bacterial survival. (Author)

  17. Contamination of boreholes water by 76 pesticides molecules in the ...

    African Journals Online (AJOL)

    user2

    to be the cause of the degradation of the quality of sur- face and ground waters ... network and the nature of the soil generally clay lateritic with high permeability. .... 0.006 0.008 0.004 0.004 0.004 0.007 0.008 0.004 0.004 0.004 Malathion.

  18. Antibiofilm and antibacterial effects of specific chitosan molecules on Staphylococcus aureus isolates associated with bovine mastitis

    Science.gov (United States)

    Asli, Abdelhamid; Brouillette, Eric; Ster, Céline; Ghinet, Mariana Gabriela; Brzezinski, Ryszard; Lacasse, Pierre; Jacques, Mario

    2017-01-01

    Staphylococcus aureus is one of the major pathogens causing bovine intramammary infections (IMIs) and mastitis. Mastitis is the primary cause for the use of antibiotics in dairy farms but therapeutic failure is often observed. One of the reasons for the lack of effectiveness of antibiotic therapy despite the observed susceptibility of bacterial isolates in vitro are bacterial biofilms. In this study, we used chitosan of well-defined molecular weight (0.4–0.6, 1.3, 2.6 and 4.0 kDa) and investigated their antibiofilm and antibacterial activities in in vitro and in vivo models related to S. aureus IMIs. A chitosan of at least 6 units of glucosamine was necessary for maximum antibacterial activity. The 2.6 and 4.0 kDa forms were able to prevent biofilm production by the biofilm hyperproducer strain S. aureus 2117 and a bovine MRSA (methicillin-resistant S. aureus). The intramammary administration of the 2.6 kDa chitosan showed no adverse effects in mice or in cows, as opposed to the slight inflammatory effect observed in mammary glands with the 4.0 kDa derivative. The 2.6 kDa chitosan killed bacteria embedded in pre-established biofilms in a dose-dependent manner with a >3 log10 reduction in CFU at 4 mg/ml. Also, the 2.6 kDa chitosan could prevent the persistence of the internalized MRSA into the mammary epithelial cell line MAC-T. An in vitro checkerboard assay showed that the 2.6 kDa chitosan produced a synergy with the macrolide class of antibiotics (e.g., tilmicosin) and reduced the MIC of both molecules by 2–8 times. Finally, the intramammary administration of the 2.6 kDa chitosan alone (P<0.01) or in combination with tilmicosin (P<0.0001) reduced the colonization of mammary glands in a murine IMI model. Our results suggest that the use of chitosan alone or in combination with a low dose of a macrolide could help reduce antibiotic use in dairy farms. PMID:28486482

  19. Antibiofilm and antibacterial effects of specific chitosan molecules on Staphylococcus aureus isolates associated with bovine mastitis.

    Directory of Open Access Journals (Sweden)

    Abdelhamid Asli

    Full Text Available Staphylococcus aureus is one of the major pathogens causing bovine intramammary infections (IMIs and mastitis. Mastitis is the primary cause for the use of antibiotics in dairy farms but therapeutic failure is often observed. One of the reasons for the lack of effectiveness of antibiotic therapy despite the observed susceptibility of bacterial isolates in vitro are bacterial biofilms. In this study, we used chitosan of well-defined molecular weight (0.4-0.6, 1.3, 2.6 and 4.0 kDa and investigated their antibiofilm and antibacterial activities in in vitro and in vivo models related to S. aureus IMIs. A chitosan of at least 6 units of glucosamine was necessary for maximum antibacterial activity. The 2.6 and 4.0 kDa forms were able to prevent biofilm production by the biofilm hyperproducer strain S. aureus 2117 and a bovine MRSA (methicillin-resistant S. aureus. The intramammary administration of the 2.6 kDa chitosan showed no adverse effects in mice or in cows, as opposed to the slight inflammatory effect observed in mammary glands with the 4.0 kDa derivative. The 2.6 kDa chitosan killed bacteria embedded in pre-established biofilms in a dose-dependent manner with a >3 log10 reduction in CFU at 4 mg/ml. Also, the 2.6 kDa chitosan could prevent the persistence of the internalized MRSA into the mammary epithelial cell line MAC-T. An in vitro checkerboard assay showed that the 2.6 kDa chitosan produced a synergy with the macrolide class of antibiotics (e.g., tilmicosin and reduced the MIC of both molecules by 2-8 times. Finally, the intramammary administration of the 2.6 kDa chitosan alone (P<0.01 or in combination with tilmicosin (P<0.0001 reduced the colonization of mammary glands in a murine IMI model. Our results suggest that the use of chitosan alone or in combination with a low dose of a macrolide could help reduce antibiotic use in dairy farms.

  20. Tigecycline Resistant Klebsiella pneumoniae Isolated from Austrian River Water

    Directory of Open Access Journals (Sweden)

    Alexander Hladicz

    2017-10-01

    Full Text Available Abstract: Antibiotic-resistant bacteria are spreading worldwide in medical settings but also in the environment. These resistant bacteria illustrate a major health problem in our times, and last-line antibiotics such as tigecycline represent an ultimate therapy option. Reports on tigecycline non-susceptible Enterobacteriaceae are presented with regard to medical settings but are rare with that for the environment. The aim of this study was to characterize two tigecycline non-susceptible Klebsiella pneumoniae isolates from the river Mur, and to question the resistance mechanism. The screening for chromosomal mutations revealed a deletion and a silent point mutation in one isolate and a point mutation in the other isolate all within the ramR allele. RamR acts as repressor and prevents overexpression of ramA. These mutations are likely to cause a resistant phenotype due to the overexpression of AcrAB-TolC. MLST revealed that the isolates belonged to two unrelated MLST types (ST2392 and ST2394. Both isolates only revealed resistance to tigecycline and tetracycline. This is one of the rare reports of tigecycline-resistant Klebsiella pneumoniae from surface water. The presence of two genetically different isolates suggests that the river water may bear substances that favor mutations that can lead to this efflux pump-driven resistance.

  1. Hydroxyl and water molecule orientations in trypsin: Comparison to molecular dynamics structures

    Energy Technology Data Exchange (ETDEWEB)

    McDowell, R.S.; Kossiakoff, A.A. [Genentech, Inc., South San Francisco, CA (United States)

    1994-12-31

    A comparison is presented of experimentally observed hydroxyl and water hydrogens in trypsin determined from neutron density maps with the results of a 140ps molecular dynamics (MD) simulation. Experimental determination of hydrogen and deuterium atom positions in molecules as large as proteins is a unique capability of neutron diffraction. The comparison addresses the degree to which a standard force-field approach can adequately describe the local electrostatic and van der Waals forces that determine the orientations of these hydrogens. Neutron densities, derived from 2.1{Angstrom} D{sub 2}O-H{sub 2}O difference Fourier maps, provide a database of 27 well-ordered hydroxyl hydrogens. Most of the simulated hydroxyl orientations are within a standard deviation of the experimentally-observed positions, including several examples in which both the simulation and the neutron density indicate that a hydroxyl group is shifted from a {open_quote}standard{close_quote} rotamer. For the most highly ordered water molecules, the hydrogen distributions calculated from the trajectory were in good agreement with neutron density; simulated water molecules that displayed multiple hydrogen bonding networks had correspondingly broadened neutron density profiles. This comparison was facilitated by development of a method to construct a pseudo 2{Angstrom} density map based on the hydrogen atom distributions from the simulation. The degree of disorder of internal water molecules is shown to result primarily from the electrostatic environment surrounding that water molecule as opposed to the cavity size available to the molecule. A method is presented for comparing the discrete observations sampled in a dynamics trajectory with the time- averaged data obtained from X-ray or neutron diffraction studies. This method is particularly useful for statically-disordered water molecules, in which the average location assigned from a trajectory may represent a site of relatively low occupancy.

  2. Physiological characteristics of bacteria isolated from water brines within permafrost

    Science.gov (United States)

    Shcherbakova, V.; Rivkina, E.; Laurinavichuis, K.; Pecheritsina, S.; Gilichinsky, D.

    2004-01-01

    In the Arctic there are lenses of overcooled water brines (cryopegs) sandwiched within permafrost marine sediments 100 120 thousand years old. We have investigated the physiological properties of the pure cultures of anaerobic Clostridium sp. strain 14D1 and two strains of aerobic bacteria Psychrobacter sp. isolated from these cryopegs. The structural and physiological characteristics of new bacteria from water brines have shown their ability to survive and develop under harsh conditions, such as subzero temperatures and high salinity.

  3. [The isolation and differentiation of leptospires from cattle drinking water].

    Science.gov (United States)

    Luyven, G; Schönberg, A

    1989-08-01

    The cultural isolation and identification of leptospires from three water samples of farm wells were described. All three strains isolated belong to the apathogenic species L. biflexa. The cattle stock of these farms (A, B, C) had reacted serologically to serovars hardjo and grippotyphosa. The strain isolated from farm A is a new serovar called krefeldi and belongs to serogroup Doberdo. The strain isolated from farm B belongs to serovar montefiascone of serogroup Botanica and the strain from farm C to serovar bessemans of serogroup Bessemans. It is remarkable that serovar krefeldi with all the sera of farm A (titre up to 1:40) and only with part of the sera of farm B reacted.

  4. Water-mediated influence of a crowded environment on internal vibrations of a protein molecule.

    Science.gov (United States)

    Kuffel, Anna; Zielkiewicz, Jan

    2016-02-14

    The influence of crowding on the protein inner dynamics is examined by putting a single protein molecule close to one or two neighboring protein molecules. The presence of additional molecules influences the amplitudes of protein fluctuations. Also, a weak dynamical coupling of collective velocities of surface atoms of proteins separated by a layer of water is detected. The possible mechanisms of these phenomena are described. The cross-correlation function of the collective velocities of surface atoms of two proteins was decomposed into the Fourier series. The amplitude spectrum displays a peak at low frequencies. Also, the results of principal component analysis suggest that the close presence of an additional protein molecule influences the high-amplitude, low-frequency modes in the most prominent way. This part of the spectrum covers biologically important protein motions. The neighbor-induced changes in the inner dynamics of the protein may be connected with the changes in the velocity power spectrum of interfacial water. The additional protein molecule changes the properties of solvation water and in this way it can influence the dynamics of the second protein. It is suggested that this phenomenon may be described, at first approximation, by a damped oscillator driven by an external random force. This model was successfully applied to conformationally rigid Choristoneura fumiferana antifreeze protein molecules.

  5. FORMATION OF ORGANIC MOLECULES AND WATER IN WARM DISK ATMOSPHERES

    Energy Technology Data Exchange (ETDEWEB)

    Najita, Joan R. [National Optical Astronomy Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719 (United States); Adamkovics, Mate; Glassgold, Alfred E. [Astronomy Department, University of California, Berkeley, CA 94720 (United States)

    2011-12-20

    Observations from Spitzer and ground-based infrared spectroscopy reveal significant diversity in the molecular emission from the inner few AU of T Tauri disks. We explore theoretically the possible origin of this diversity by expanding on our earlier thermal-chemical model of disk atmospheres. We consider how variations in grain settling, X-ray irradiation, accretion-related mechanical heating, and the oxygen-to-carbon ratio can affect the thermal and chemical properties of the atmosphere at 0.25-40 AU. We find that these model parameters can account for many properties of the detected molecular emission. The column density of the warm (200-2000 K) molecular atmosphere is sensitive to grain settling and the efficiency of accretion-related heating, which may account, at least in part, for the large range in molecular emission fluxes that have been observed. The dependence of the atmospheric properties on the model parameters may also help to explain trends that have been reported in the literature between molecular emission strength and mid-infrared color, stellar accretion rate, and disk mass. We discuss whether some of the differences between our model results and the observations (e.g., for water) indicate a role for vertical transport and freezeout in the disk midplane. We also discuss how planetesimal formation in the outer disk (beyond the snowline) may imprint a chemical signature on the inner few AU of the disk and speculate on possible observational tracers of this process.

  6. FORMATION OF ORGANIC MOLECULES AND WATER IN WARM DISK ATMOSPHERES

    International Nuclear Information System (INIS)

    Najita, Joan R.; Ádámkovics, Máté; Glassgold, Alfred E.

    2011-01-01

    Observations from Spitzer and ground-based infrared spectroscopy reveal significant diversity in the molecular emission from the inner few AU of T Tauri disks. We explore theoretically the possible origin of this diversity by expanding on our earlier thermal-chemical model of disk atmospheres. We consider how variations in grain settling, X-ray irradiation, accretion-related mechanical heating, and the oxygen-to-carbon ratio can affect the thermal and chemical properties of the atmosphere at 0.25-40 AU. We find that these model parameters can account for many properties of the detected molecular emission. The column density of the warm (200-2000 K) molecular atmosphere is sensitive to grain settling and the efficiency of accretion-related heating, which may account, at least in part, for the large range in molecular emission fluxes that have been observed. The dependence of the atmospheric properties on the model parameters may also help to explain trends that have been reported in the literature between molecular emission strength and mid-infrared color, stellar accretion rate, and disk mass. We discuss whether some of the differences between our model results and the observations (e.g., for water) indicate a role for vertical transport and freezeout in the disk midplane. We also discuss how planetesimal formation in the outer disk (beyond the snowline) may imprint a chemical signature on the inner few AU of the disk and speculate on possible observational tracers of this process.

  7. Influence of the effective mass of water molecule on thermal neutron scattering

    International Nuclear Information System (INIS)

    Markovic, M.

    1981-01-01

    The influence of the effective water molecule mass on the thermal neutron scattering on the nucleus of the hydrogen atom has been investigated. Besides the actual water molecule mass (M = 18) the investigations have been carried out with its two effective values (M1 = 16 and M2 = 20). The differential and total cross sections have been calculated for the incident thermal neutron energy E o = 1 eV. Investigation results show different prominence of the quantum effects and for M2 the appearance of peaks in the quasielastic scattering. (author)

  8. Prevalence and Genetic Diversity of Enterococcus faecalis Isolates from Mineral Water and Spring Water in China

    Directory of Open Access Journals (Sweden)

    Lei Wei

    2017-06-01

    Full Text Available Enterococcus faecalis is an important opportunistic pathogen which is frequently detected in mineral water and spring water for human consumption and causes human urinary tract infections, endocarditis and neonatal sepsis. The aim of this study was to determine the prevalence, virulence genes, antimicrobial resistance and genetic diversity of E. faecalis from mineral water and spring water in China. Of 314 water samples collected from January 2013 to January 2014, 48 samples (15.3% were contaminated E. faecalis. The highest contamination rate occurred in activated carbon filtered water of spring water (34.5%, followed by source water of spring water (32.3% and source water of mineral water (6.4%. The virulence gene test of 58 E. faecalis isolates showed that the detection rates of asa1, ace, cylA, gelE and hyl were 79.3, 39.7, 0, 100, 0%, respectively. All 58 E. faecalis isolates were not resistant to 12 kinds of antibiotics (penicillin, ampicillin, linezolid, quinupristin/dalfopristin, vancomycin, gentamicin, streptomycin, ciprofloxacin, levofloxacin, norfloxacin, nitrofurantoin, and tetracycline. Enterobacterial repetitive intergenic consensus-PCR classified 58 isolates and three reference strains into nine clusters with a similarity of 75%. This study is the first to investigate the prevalence of E. faecalis in mineral water and spring water in China. The results of this study suggested that spring water could be potential vehicles for transmission of E. faecalis.

  9. Antibiotic resistance and virulence genes in coliform water isolates.

    Science.gov (United States)

    Stange, C; Sidhu, J P S; Tiehm, A; Toze, S

    2016-11-01

    Widespread fecal pollution of surface water may present a major health risk and a significant pathway for dissemination of antibiotic resistance bacteria. The River Rhine is one of the longest and most important rivers in Europe and an important raw water source for drinking water production. A total of 100 coliform isolates obtained from River Rhine (Germany) were examined for their susceptibility to seven antimicrobial agents. Resistances against amoxicillin, trimethoprim/sulfamethoxazole and tetracycline were detected in 48%, 11% and 9% of isolates respectively. The antibiotic resistance could be traced back to the resistance genes bla TEM , bla SHV , ampC, sul1, sul2, dfrA1, tet(A) and tet(B). Whereby, the ampC gene represents a special case, because its presence is not inevitably linked to a phenotypic antibiotic resistance. Multiple antibiotics resistance was often accompanied by the occurrence of class 1 or 2 integrons. E. coli isolates belonging to phylogenetic groups A and B1 (commensal) were more predominant (57%) compared to B2 and D groups (43%) which are known to carry virulent genes. Additionally, six E. coli virulence genes were also detected. However, the prevalence of virulence genes in the E. coli isolates was low (not exceeding 4.3% per gene) and no diarrheagenic E. coli pathotypes were detected. This study demonstrates that surface water is an important reservoir of ARGs for a number of antibiotic classes such as sulfonamide, trimethoprim, beta-lactam-antibiotics and tetracycline. The occurrence of antibiotic resistance in coliform bacteria isolated from River Rhine provides evidence for the need to develop management strategies to limit the spread of antibiotic resistant bacteria in aquatic environment. Copyright © 2016 Elsevier GmbH. All rights reserved.

  10. Shear-stress-induced structural arrangement of water molecules in nanoscale Couette flow with slipping at wall boundary

    International Nuclear Information System (INIS)

    Lin, Jau-Wen

    2014-01-01

    This study investigated the structuring of water molecules in a nanoscale Couette flow with the upper plate subjected to lateral forces with various magnitudes and water slipping against a metal wall. It was found that when the upper plate is subjected to a force, the water body deforms into a parallelepiped. Water molecules in the channel are then gradually arranged into lattice positions, creating a layered structure. The structural arrangement of water molecules is caused by the water molecules accommodating themselves to the increase in energy under the application of a lateral force on the moving plate. The ordering arrangement of water molecules increases the rotational degree of freedom, allowing the molecules to increase their Coulomb potential energy through polar rotation that accounts for the energy input through the upper plate. With a force continuously applied to the upper plate, the water molecules in contact with the upper plate move forward until slip between the water and upper plate occurs. The relation between the structural arrangement of water molecules, slip at the wall, and the shear force is studied. The relation between the slip and the locking/unlocking of water molecules to metal atoms is also studied

  11. Characterization of N-Acylhomoserine Lactones Produced by Bacteria Isolated from Industrial Cooling Water Systems

    Directory of Open Access Journals (Sweden)

    Noriya Okutsu

    2015-12-01

    Full Text Available The cooling water systems are used to remove heat generated in the various industries. Biofouling of the cooling water systems causes blocking of condenser pipes and the heat exchanger tubes. In many Gram-negative bacteria, N-acylhomoserine lactone (AHL are used as quorum-sensing signal molecule and associated with biofilm formation. To investigate the relationship between quorum sensing and biofouling in the cooling water system, we isolated a total of 192 bacterial strains from the five cooling water systems, and screened for AHL production. Seven isolates stimulated AHL-mediated purple pigment production in AHL reporter strain Chromobacterium violaceum CV026 or VIR07. Based on their 16S rRNA gene sequences, AHL-producing isolates were assigned to Aeromonas hydrophila, Lysobacter sp., Methylobacterium oryzae, and Bosea massiliensis. To the best of our knowledge, B. massiliensis and Lysobacter sp. have not been reported as AHL-producing species in the previous researches. AHLs extracted from the culture supernatants of B. massiliensis and Lysobacter sp. were identified by liquid chromatography-mass spectrometry. AHLs produced by B. massiliensis were assigned as N-hexanoyl-l-homoserine lactone (C6-HSL, N-(3-oxohexanoyl-l-homoserine lactone (3-oxo-C6-HSL, and N-(3-oxooctanoyl-l-homoserine lactone (3-oxo-C8-HSL. AHLs produced by Lysobacter sp. were assigned as N-decanoyl-l-homoserine lactone (C10-HSL and N-(3-oxodecanoyl-l-homoserine lactone (3-oxo-C10-HSL. This is the first report of identification of AHLs produced by B. massiliensis and Lysobacter sp. isolated from the cooling water system.

  12. Transport of water molecules through noncylindrical pores in multilayer nanoporous graphene.

    Science.gov (United States)

    Shahbabaei, Majid; Kim, Daejoong

    2017-08-09

    In this study, molecular dynamics (MD) simulations are used to examine the water transport properties through asymmetric hourglass-shaped pores in multilayer nanoporous graphene with a constant interlayer separation of 6 Å. The properties of the tested asymmetric hourglass-shaped pores [with the models having long cone (l 1 , -P) and short cone (l 2 , +P) entrances] are compared to a symmetric pore model. The study findings indicate that the water occupancy increases across the asymmetric pore (l 1 , -P) compared to (l 2 , +P), because of the length effect. The asymmetric pore, (l 1 , -P), yields higher flux compared to (l 2 , +P) and even the symmetric model, which can be attributed to the increase in the hydrogen bonds. In addition, the single-file water molecules across the narrowest pore diameter inside the (l 2 , +P) pore exhibit higher viscosity compared to those in the (l 1 , -P) pore because of the increase in the water layering effect. Moreover, it is found that the permeability inside the multilayer hourglass-shaped pore depends on the length of the flow path of the water molecules before approaching the layer with the smallest pore diameter. The probability of dipole orientation exhibits wider distribution inside the (l 1 , -P) system compared to (l 2 , +P), implying an enhanced formation of hydrogen bonding of water molecules. This results in the fast flow of water molecules. The MD trajectory shows that the dipole orientation across the single-layer graphene has frequently flipped compared to the dipole orientation across the pores in multilayer graphene, which is maintained during the whole simulation time (although the dipole orientation has flipped for a few picoseconds at the beginning of the simulation). This can be attributed to the energy barrier induced by the individual layer. The diffusion coefficient of water molecules inside the (l 2 , +P) system increases with pressure difference, however, it decreases inside the (l 1 , -P) system because

  13. Toward atomic resolution diffractive imaging of isolated molecules with x-ray free-electron lasers

    DEFF Research Database (Denmark)

    Stern, Stephan; Holmegaard, Lotte; Filsinger, Frank

    2014-01-01

    We give a detailed account of the theoretical analysis and the experimental results of an x-ray-diffraction experiment on quantum-state selected and strongly laser-aligned gas-phase ensembles of the prototypical large asymmetric rotor molecule 2,5-diiodobenzonitrile, performed at the Linac Cohere...

  14. Identification of intrinsic catalytic activity for electrochemical reduction of water molecules to generate hydrogen

    KAUST Repository

    Shinagawa, Tatsuya

    2015-01-01

    Insufficient hydronium ion activities at near-neutral pH and under unbuffered conditions induce diffusion-limited currents for hydrogen evolution, followed by a reaction with water molecules to generate hydrogen at elevated potentials. The observed constant current behaviors at near neutral pH reflect the intrinsic electrocatalytic reactivity of the metal electrodes for water reduction. This journal is © the Owner Societies.

  15. STABILIZATION OF THE NEUTRAL PROTEASE OF BACILLUS-STEAROTHERMOPHILUS BY REMOVAL OF A BURIED WATER MOLECULE

    NARCIS (Netherlands)

    VRIEND, G; BERENDSEN, HJC; VANDERZEE, [No Value; VANDENBURG, B; VENEMA, G; EIJSINK, VGH

    1991-01-01

    Using site-directed mutagenesis, Ala166 in the neutral protease of Bacillus stearothermophilus was changed into Ser. Model building and molecular dynamics simulations of the mutant enzyme indicated that the Ser hydroxyl group fits well in a cavity which contains a water molecule in the wild-type

  16. Practical isolation of methyl mercury in natural waters

    International Nuclear Information System (INIS)

    Schintu, M.; Kauri, T.; Contu, A.; Kudo, A.

    1987-01-01

    A simple method to isolate both organic and inorganic mercury in natural waters is described. The mercuric compounds were quantitatively extracted with dithizone from six different kinds of water spiked at nanogram levels with radioactive mercuric chloride and methylmercuric chloride. After the separation from the inorganic mercury with sodium nitrite, methyl mercury was transferred to aqueous medium with sodium thiosulfate. The method provides a high recovery of organic as well as inorganic mercury to an aqueous medium, prior to their determination by gold-trap cold vapor atomic absorption spectrophotometry. This method is easy, rapid, and inexpensive. Furthermore, the limited number of analytical steps should reduce loss and contamination

  17. Effects of Water Molecule on CO Oxidation by OH: Reaction Pathways, Kinetic Barriers, and Rate Constants.

    Science.gov (United States)

    Zhang, Linyao; Yang, Li; Zhao, Yijun; Zhang, Jiaxu; Feng, Dongdong; Sun, Shaozeng

    2017-07-06

    The water dilute oxy-fuel combustion is a clean combustion technology for near-zero emission power; and the presence of water molecule could have both kinetic and dynamic effects on combustion reactions. The reaction OH + CO → CO 2 + H, one of the most important elementary reactions, has been investigated by extensive electronic structure calculations. And the effects of a single water molecule on CO oxidation have been studied by considering the preformed OH(H 2 O) complex reacts with CO. The results show little change in the reaction pathways, but the additional water molecule actually increases the vibrationally adiabatic energy barriers (V a G ). Further thermal rate constant calculations in the temperature range of 200 to 2000 K demonstrate that the total low-pressure limit rate constant for the water assisted OH(H 2 O) + CO → CO 2 + H 2 O + H reaction is 1-2 orders lower than that of the water unassisted one, which is consistent with the change of V a G . Therefore, the hydrated radical OH(H 2 O) would actually slow down the oxidation of CO. Meanwhile, comparisons show that the M06-2X/aug-cc-pVDZ method gives a much better estimation in energy and thus is recommended to be employed for direct dynamics simulations.

  18. Integration or segregation: how do molecules behave at oil/water interfaces?

    Science.gov (United States)

    Moore, F G; Richmond, G L

    2008-06-01

    It has been over 250 years since Benjamin Franklin, fascinated with the wave-stilling effect of oil on water, performed his famous oil-drop experiments; nevertheless, the behavior of water molecules adjacent to hydrophobic surfaces continues to fascinate today. In the 18th century, the calming of the seas seemed the most pertinent application of such knowledge; today, we understand that oil-on-water phenomena underlie a range of important chemical, physical, and biological processes, including micelle and membrane formation, protein folding, chemical separation, oil extraction, nanoparticle formation, and interfacial polymerization. Beyond classical experiments of the oil-water interface, recent interest has focused on deriving a molecular-level picture of this interface or, more generally, of water molecules positioned next to any hydrophobic surface. This Account summarizes more than a decade's work from our laboratories aimed at understanding the nature of the hydrogen bonding occurring between water and a series of organic liquids in contact. Although the common perception is that water molecules and oil molecules positioned at the interface between the immiscible liquids want nothing to do with one another, we have found that weak interactions between these hydrophilic and hydrophobic molecules lead to interesting interfacial behavior, including highly oriented water molecules and layering of the organic medium that extends several molecular layers deep into the bulk organic liquid. For some organic liquids, penetration of oriented water into the organic layer is also apparent, facilitated by molecular interactions established at the molecularly thin region of first contact between the two liquids. The studies involve a combined experimental and computational approach. The primary experimental tool that we have used is vibrational sum frequency spectroscopy (VSFS), a powerful surface-specific vibrational spectroscopic method for measuring the molecular

  19. The significant surface-water connectivity of "geographically isolated wetlands"

    Science.gov (United States)

    Calhoun, Aram J.K.; Mushet, David M.; Alexander, Laurie C.; DeKeyser, Edward S.; Fowler, Laurie; Lane, Charles R.; Lang, Megan W.; Rains, Mark C.; Richter, Stephen; Walls, Susan

    2017-01-01

    We evaluated the current literature, coupled with our collective research expertise, on surface-water connectivity of wetlands considered to be “geographically isolated” (sensu Tiner Wetlands 23:494–516, 2003a) to critically assess the scientific foundation of grouping wetlands based on the singular condition of being surrounded by uplands. The most recent research on wetlands considered to be “geographically isolated” shows the difficulties in grouping an ecological resource that does not reliably indicate lack of surface water connectivity in order to meet legal, regulatory, or scientific needs. Additionally, the practice of identifying “geographically isolated wetlands” based on distance from a stream can result in gross overestimates of the number of wetlands lacking ecologically important surface-water connections. Our findings do not support use of the overly simplistic label of “geographically isolated wetlands”. Wetlands surrounded by uplands vary in function and surface-water connections based on wetland landscape setting, context, climate, and geographic region and should be evaluated as such. We found that the “geographically isolated” grouping does not reflect our understanding of the hydrologic variability of these wetlands and hence does not benefit conservation of the Nation’s diverse wetland resources. Therefore, we strongly discourage use of categorizations that provide overly simplistic views of surface-water connectivity of wetlands fully embedded in upland landscapes.

  20. Method for strontium isolation from high-mineralized water

    International Nuclear Information System (INIS)

    Evzhanov, Kh.; Andriyasova, G.M.

    1983-01-01

    A method to isolate strontium from high-mineralized waters containing sodium, magnesium, calcium and strontium chlorides, which differ from the prototype method in a considerable decrease in energy consumption with the preservation of a high degree of Sr, Mg and Ca isolation selectivity, has been suggested. According to the method suggested mineralized waters are treated with alkali (NaOH) in the amount of 95-97% of stoichiometry by magnesium, then after separation of magnesium hydroxide precipitate mother liquor is treated with sodium carbonate in the amount of 50-60% of stoichiometry by calcium. After separation of calcium carbonate precipitate mother liquor is treated with NaOH in the amount of 130-135% of stoichiometry by calcium. After separation of calcium hydroxide precipitate from mother liquor by means of sodium carbonate introduction strontium carbonate is isolated. The degree of strontium extraction in the form of SrCO 3 constitutes 90.5% of its content in the initial solution. The method presented can be used for strontium separation from natural and waste waters

  1. Fractionation of hydrogen and oxygen isotopes between hydrated and free water molecules in aqueous urea solution

    International Nuclear Information System (INIS)

    Kakiuchi, M.; Matsuo, S.

    1985-01-01

    Ratios of D/H and 18 O/ 16 O in the vapor phase in equilibrium with aqueous urea solution with different urea molalities were measured at 15 and 25 0 C. Under the assumption that urea solutions consist of two species, i.e., the urea-water cluster and free water, the results are interpreted to give the average hydration number, i.e., the number of water molecules per urea molecule in the urea-water cluster. Good agreement was obtained for the hydration number estimated independently from hydrogen and oxygen isotopic fractions. On the basis of hydrogen isotopic data at 25 0 C, the average hydration number of urea in the cluster is 6.3 +/- 0.8 at 2.1 m and 2.75 +/- 0.08 at saturation (20.15 m). The corresponding average hydration numbers based on oxygen isotopic data were calculated to be 6.7 +/- 2.4 at 2.1 m and 2.75 +/- 0.25 at urea saturation. HD 16 O is enriched in the urea-water cluster and H 2 18 O is enriched in free water. Isotopic partitioning between the cluster and free water is markedly different from those between hydration spheres and free water in aqueous electrolyte solutions. 29 references, 6 figures, 5 tables

  2. Structure and dynamics of water and lipid molecules in charged anionic DMPG lipid bilayer membranes

    DEFF Research Database (Denmark)

    Rønnest, A. K.; Peters, Günther H.J.; Hansen, Flemming Yssing

    2016-01-01

    Molecular dynamics simulations have been used to investigate the influence of the valency of counter-ions on the structure of freestanding bilayer membranes of the anionic 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) lipid at 310 K and 1 atm. At this temperature, the membrane is in the fluid...... compared to experimental results and used to determine an average diffusion constant for all water molecules in the system. On extrapolating the diffusion constants inferred experimentally to a temperature of 310 K, reasonable agreement with the simulations is obtained. However, the experiments do not have...... the sensitivity to confirm the diffusion of a small component of water bound to the lipids as found in the simulations. In addition, the orientation of the dipole moment of the water molecules has been determined as a function of their depth in the membrane. Previous indirect estimates of the electrostatic...

  3. Partition Coefficients of Organic Molecules in Squalane and Water/Ethanol Mixtures by Molecular Dynamics Simulations

    DEFF Research Database (Denmark)

    Lundsgaard, Rasmus; Kontogeorgis, Georgios; Economou, Ioannis G.

    2011-01-01

    coefficient can be estimated for both a small hydrophilic and a hydrophobic organic molecules between squalane (used here to mimic low density poly ethylene) and water/ethanol solutes using thermodynamic integration to calculate the free energy of solvation. Molecular dynamics simulations are performed, using...... the GROMACS software, by slowly decoupling of firstly the electrostatic and then the Lennard–Jones interactions between molecules in the simulation box. These calculations depend very much on the choice of force field. Two force fields have been tested in this work, the TraPPE-UA (united-atom) and the OPLS...

  4. Measurements of water molecule density by tunable diode laser absorption spectroscopy in dielectric barrier discharges with gas-water interface

    Science.gov (United States)

    Tachibana, Kunihide; Nakamura, Toshihiro; Kawasaki, Mitsuo; Morita, Tatsuo; Umekawa, Toyofumi; Kawasaki, Masahiro

    2018-01-01

    We measured water molecule (H2O) density by tunable diode-laser absorption spectroscopy (TDLAS) for applications in dielectric barrier discharges (DBDs) with a gas-water interface. First, the effects of water temperature and presence of gas flow were tested using a Petri dish filled with water and a gas injection nozzle. Second, the TDLAS system was applied to the measurements of H2O density in two types of DBDs; one was a normal (non-inverted) type with a dielectric-covered electrode above a water-filled counter electrode and the other was an inverted type with a water-suspending mesh electrode above a dielectric-covered counter electrode. The H2O density in the normal DBD was close to the density estimated from the saturated vapor pressure, whereas the density in the inverted DBD was about half of that in the former type. The difference is attributed to the upward gas flow in the latter type, that pushes the water molecules up towards the gas-water interface.

  5. Characterization of Sphingomonas isolates from Finnish and Swedish drinking water distribution systems.

    Science.gov (United States)

    Koskinen, R; Ali-Vehmas, T; Kämpfer, P; Laurikkala, M; Tsitko, I; Kostyal, E; Atroshi, F; Salkinoja-Salonen, M

    2000-10-01

    Sphingomonas species were commonly isolated from biofilms in drinking water distribution systems in Finland (three water meters) and Sweden (five water taps in different buildings). The Sphingomonas isolates (n = 38) were characterized by chemotaxonomic, physiological and phylogenetic methods. Fifteen isolates were designated to species Sphingomonas aromaticivorans, seven isolates to S. subterranea, two isolates to S. xenophaga and one isolate to S. stygia. Thirteen isolates represented one or more new species of Sphingomonas. Thirty-three isolates out of 38 grew at 5 degrees C on trypticase soy broth agar (TSBA) and may therefore proliferate in the Nordic drinking water pipeline where the temperature typically ranges from 2 to 12 degrees C. Thirty-three isolates out of 38 grew at 37 degrees C on TSBA and 15 isolates also grew on blood agar at 37 degrees C. Considering the potentially pathogenic features of sphingomonas, their presence in drinking water distribution systems may not be desirable.

  6. First report of isolation of Nocardia otitidiscaviarum from hospital water

    Directory of Open Access Journals (Sweden)

    Shojaei Hasan

    2016-07-01

    Full Text Available Nocardia otitidiscaviarum DSM43242 was first isolated as a novel species in 1924 from infected middle ear of guinea pig. Since then, there have only been a lot number additional reports for example from Spain, the USA, French and Japan, on the isolation of this species from clinical specimens such as pulmonary infection, disseminated infection, cutaneous infection and primary brain abscess. Nocardia infection is mainly associated with immunocompromised patients, but sometimes may appear in healthy humans. We herein present the first report on isolation of this organism from hospital water, which represents the environmental resources as a source of risk for people especially the hospital environment. The isolate NR4 was subjected to identification by conventional phenotypic tests such as resistance to lysozyme and molecular tests including genusspecific PCR for Nocardia based on partial 16S rDNA gene and sequencing analysis of 16S rDNA. Our finding of 16S rDNA gene sequence of the studied strain were identical and showed 100% similarties with those of Nocardia otitidiscaviarum.

  7. Sequential water molecule binding enthalpies for aqueous nanodrops containing a mono-, di- or trivalent ion and between 20 and 500 water molecules† †Electronic supplementary information (ESI) available: Detailed description of the experimental and computational modeling methods. Isolation, BIRD and UVPD sequence for [Ru(NH3)6]3+·(H2O)169–171, nanoESI spectra for 2+ and 3+ ions. Detailed description of the isotope distribution simulation program. Comparison between experimental and simulated 1+, 2+ and 3+ ion isotope distributions. Wavelength dependence of the deduced sequential binding enthalpies. Comparison of experimental UVPD binding enthalpies to the liquid drop model at different temperatures. Complete list of binding enthalpies and average number of water molecules lost upon UVPD. See DOI: 10.1039/c6sc04957e Click here for additional data file.

    Science.gov (United States)

    Heiles, Sven; Cooper, Richard J.; DiTucci, Matthew J.

    2017-01-01

    Sequential water molecule binding enthalpies, ΔH n,n–1, are important for a detailed understanding of competitive interactions between ions, water and solute molecules, and how these interactions affect physical properties of ion-containing nanodrops that are important in aerosol chemistry. Water molecule binding enthalpies have been measured for small clusters of many different ions, but these values for ion-containing nanodrops containing more than 20 water molecules are scarce. Here, ΔH n,n–1 values are deduced from high-precision ultraviolet photodissociation (UVPD) measurements as a function of ion identity, charge state and cluster size between 20–500 water molecules and for ions with +1, +2 and +3 charges. The ΔH n,n–1 values are obtained from the number of water molecules lost upon photoexcitation at a known wavelength, and modeling of the release of energy into the translational, rotational and vibrational motions of the products. The ΔH n,n–1 values range from 36.82 to 50.21 kJ mol–1. For clusters containing more than ∼250 water molecules, the binding enthalpies are between the bulk heat of vaporization (44.8 kJ mol–1) and the sublimation enthalpy of bulk ice (51.0 kJ mol–1). These values depend on ion charge state for clusters with fewer than 150 water molecules, but there is a negligible dependence at larger size. There is a minimum in the ΔH n,n–1 values that depends on the cluster size and ion charge state, which can be attributed to the competing effects of ion solvation and surface energy. The experimental ΔH n,n–1 values can be fit to the Thomson liquid drop model (TLDM) using bulk ice parameters. By optimizing the surface tension and temperature change of the logarithmic partial pressure for the TLDM, the experimental sequential water molecule binding enthalpies can be fit with an accuracy of ±3.3 kJ mol–1 over the entire range of cluster sizes. PMID:28451364

  8. Snake Venom PLA2s Inhibitors Isolated from Brazilian Plants: Synthetic and Natural Molecules

    Science.gov (United States)

    Carvalho, B. M. A.; Santos, J. D. L.; Xavier, B. M.; Almeida, J. R.; Resende, L. M.; Martins, W.; Marcussi, S.; Marangoni, S.; Stábeli, R. G.; Calderon, L. A.; Soares, A. M.; Da Silva, S. L.; Marchi-Salvador, D. P.

    2013-01-01

    Ophidian envenomation is an important health problem in Brazil and other South American countries. In folk medicine, especially in developing countries, several vegetal species are employed for the treatment of snakebites in communities that lack prompt access to serum therapy. However, the identification and characterization of the effects of several new plants or their isolated compounds, which are able to inhibit the activities of snake venom, are extremely important and such studies are imperative. Snake venom contains several organic and inorganic compounds; phospholipases A2 (PLA2s) are one of the principal toxic components of venom. PLA2s display a wide variety of pharmacological activities, such as neurotoxicity, myotoxicity, cardiotoxicity, anticoagulant, hemorrhagic, and edema-inducing effects. PLA2 inhibition is of pharmacological and therapeutic interests as these enzymes are involved in several inflammatory diseases. This review describes the results of several studies of plant extracts and their isolated active principles, when used against crude snake venoms or their toxic fractions. Isolated inhibitors, such as steroids, terpenoids, and phenolic compounds, are able to inhibit PLA2s from different snake venoms. The design of specific inhibitors of PLA2s might help in the development of new pharmaceutical drugs, more specific antivenom, or even as alternative approaches for treating snakebites. PMID:24171158

  9. Snake Venom PLA2s Inhibitors Isolated from Brazilian Plants: Synthetic and Natural Molecules

    Directory of Open Access Journals (Sweden)

    B. M. A. Carvalho

    2013-01-01

    Full Text Available Ophidian envenomation is an important health problem in Brazil and other South American countries. In folk medicine, especially in developing countries, several vegetal species are employed for the treatment of snakebites in communities that lack prompt access to serum therapy. However, the identification and characterization of the effects of several new plants or their isolated compounds, which are able to inhibit the activities of snake venom, are extremely important and such studies are imperative. Snake venom contains several organic and inorganic compounds; phospholipases A2 (PLA2s are one of the principal toxic components of venom. PLA2s display a wide variety of pharmacological activities, such as neurotoxicity, myotoxicity, cardiotoxicity, anticoagulant, hemorrhagic, and edema-inducing effects. PLA2 inhibition is of pharmacological and therapeutic interests as these enzymes are involved in several inflammatory diseases. This review describes the results of several studies of plant extracts and their isolated active principles, when used against crude snake venoms or their toxic fractions. Isolated inhibitors, such as steroids, terpenoids, and phenolic compounds, are able to inhibit PLA2s from different snake venoms. The design of specific inhibitors of PLA2s might help in the development of new pharmaceutical drugs, more specific antivenom, or even as alternative approaches for treating snakebites.

  10. QSPR Study of the Retention/release Property of Odorant Molecules in Water Using Statistical Methods

    Directory of Open Access Journals (Sweden)

    Assia Belhassan

    2017-10-01

    Full Text Available An integrated approach physicochemistry and structures property relationships has been carried out to study the odorant molecules retention/release phenomenon in the water. This study aimed to identify the molecular properties (molecular descriptors that govern this phenomenon assuming that modifying the structure leads automatically to a change in the retention/release property of odorant molecules. ACD/ChemSketch, MarvinSketch, and ChemOffice programs were used to calculate several molecular descriptors of 51 odorant molecules (15 alcohols, 11 aldehydes, 9 ketones and 16 esters. A total of 37 molecules (2/3 of the data set were placed in the training set to build the QSPR models, whereas the remaining, 14 molecules (1/3 of the data set constitute the test set. The best descriptors were selected to establish the quantitative structure property relationship (QSPR of the retention/release property of odorant molecules in water using multiple linear regression (MLR, multiple non-linear regression (MNLR and an artificial neural network (ANN methods. We propose a quantitative model according to these analyses. The models were used to predict the retention/release property of the test set compounds, and agreement between the experimental and predicted values was verified. The descriptors showed by QSPR study are used for study and designing of new compounds. The statistical results indicate that the predicted values are in good agreement with the experimental results. To validate the predictive power of the resulting models, external validation multiple correlation coefficient was calculated and has both in addition to a performant prediction power, a favorable estimation of stability. DOI: http://dx.doi.org/10.17807/orbital.v9i4.978 

  11. Molecular Dynamics Study of Water Molecules in Interlayer of 14 ^|^Aring; Tobermorite

    KAUST Repository

    Yoon, Seyoon

    2013-01-01

    The molecular structure and dynamics of interlayer water of 14 Å tobermorite are investigated based on molecular dynamics (MD) simulations. Calculated structural parameters of the interlayer water configuration are in good agreement with current knowledge of the refined structure. The MD simulations provide detailed information on the position and mobility of the hydrogen and oxygen of interlayer water, as well as its self-diffusion coefficient, through the interlayer of 14 Å tobermorite. Comparison of the MD simulation results at 100 and 300 K demonstrates that water molecules in the interlayer maintain their structure but change their mobility. The dominant configuration and self-diffusion coefficient of interlayer water are obtained in this study. Copyright © 2013 Japan Concrete Institute.

  12. Matrix isolation-infrared and mass spectrometric studies of high-temperature molecules

    International Nuclear Information System (INIS)

    Dickinson, S.

    1987-08-01

    Matrix isolation-infrared spectroscopy and mass spectrometry have been developed at AEE Winfrith to study the high-temperature vapour species which could be generated during a hypothetical severe reactor accident. The principles of the techniques and the instruments are described in detail, and examples of their application to specific systems discussed. Although these examples refer to high-temperature chemical species which are relevant to reactor safety assessments, the techniques are equally applicable to other processes where the characterisation of transient vapour-phase species is required. (author)

  13. Structure and dynamics of water and lipid molecules in charged anionic DMPG lipid bilayer membranes

    International Nuclear Information System (INIS)

    Rønnest, A. K.; Peters, G. H.; Hansen, F. Y.; Taub, H.; Miskowiec, A.

    2016-01-01

    Molecular dynamics simulations have been used to investigate the influence of the valency of counter-ions on the structure of freestanding bilayer membranes of the anionic 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) lipid at 310 K and 1 atm. At this temperature, the membrane is in the fluid phase with a monovalent counter-ion and in the gel phase with a divalent counter-ion. The diffusion constant of water as a function of its depth in the membrane has been determined from mean-square-displacement calculations. Also, calculated incoherent quasielastic neutron scattering functions have been compared to experimental results and used to determine an average diffusion constant for all water molecules in the system. On extrapolating the diffusion constants inferred experimentally to a temperature of 310 K, reasonable agreement with the simulations is obtained. However, the experiments do not have the sensitivity to confirm the diffusion of a small component of water bound to the lipids as found in the simulations. In addition, the orientation of the dipole moment of the water molecules has been determined as a function of their depth in the membrane. Previous indirect estimates of the electrostatic potential within phospholipid membranes imply an enormous electric field of 10 8 –10 9 V m −1 , which is likely to have great significance in controlling the conformation of translocating membrane proteins and in the transfer of ions and molecules across the membrane. We have calculated the membrane potential for DMPG bilayers and found ∼1 V (∼2 ⋅ 10 8 V m −1 ) when in the fluid phase with a monovalent counter-ion and ∼1.4 V (∼2.8 ⋅ 10 8 V m −1 ) when in the gel phase with a divalent counter-ion. The number of water molecules for a fully hydrated DMPG membrane has been estimated to be 9.7 molecules per lipid in the gel phase and 17.5 molecules in the fluid phase, considerably smaller than inferred experimentally for 1,2-dimyristoyl-sn-glycero-3

  14. Structure and dynamics of water and lipid molecules in charged anionic DMPG lipid bilayer membranes

    Energy Technology Data Exchange (ETDEWEB)

    Rønnest, A. K.; Peters, G. H.; Hansen, F. Y., E-mail: flemming@kemi.dtu.dk [Department of Chemistry, Technical University of Denmark, IK 207 DTU, DK-2800 Lyngby (Denmark); Taub, H.; Miskowiec, A. [Department of Physics and Astronomy and the University of Missouri Research Reactor,University of Missouri, Columbia, Missouri 65211 (United States)

    2016-04-14

    Molecular dynamics simulations have been used to investigate the influence of the valency of counter-ions on the structure of freestanding bilayer membranes of the anionic 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) lipid at 310 K and 1 atm. At this temperature, the membrane is in the fluid phase with a monovalent counter-ion and in the gel phase with a divalent counter-ion. The diffusion constant of water as a function of its depth in the membrane has been determined from mean-square-displacement calculations. Also, calculated incoherent quasielastic neutron scattering functions have been compared to experimental results and used to determine an average diffusion constant for all water molecules in the system. On extrapolating the diffusion constants inferred experimentally to a temperature of 310 K, reasonable agreement with the simulations is obtained. However, the experiments do not have the sensitivity to confirm the diffusion of a small component of water bound to the lipids as found in the simulations. In addition, the orientation of the dipole moment of the water molecules has been determined as a function of their depth in the membrane. Previous indirect estimates of the electrostatic potential within phospholipid membranes imply an enormous electric field of 10{sup 8}–10{sup 9} V m{sup −1}, which is likely to have great significance in controlling the conformation of translocating membrane proteins and in the transfer of ions and molecules across the membrane. We have calculated the membrane potential for DMPG bilayers and found ∼1 V (∼2 ⋅ 10{sup 8} V m{sup −1}) when in the fluid phase with a monovalent counter-ion and ∼1.4 V (∼2.8 ⋅ 10{sup 8} V m{sup −1}) when in the gel phase with a divalent counter-ion. The number of water molecules for a fully hydrated DMPG membrane has been estimated to be 9.7 molecules per lipid in the gel phase and 17.5 molecules in the fluid phase, considerably smaller than inferred experimentally for 1

  15. Water molecule-enhanced CO2 insertion in lanthanide coordination polymers

    International Nuclear Information System (INIS)

    Luo Liushan; Huang Xiaoyuan; Wang Ning; Wu Hongyan; Chen Wenbin; Feng Zihao; Zhu Huiping; Peng Xiaoling; Li Yongxian; Huang Ling; Yue Shantang; Liu Yingliang

    2009-01-01

    Two new lanthanide coordination polymers H 2 N(CH 3 ) 2 .[Eu III 2 (L 1 ) 3 (L 2 )] (1, L 1 =isophthalic acid dianion, L 2 =formic acid anion) and [La III (2,5-PDC)(L 2 )](2, 2,5-PDC=2,5-pyridinedicarboxylate dianion) were synthesized under solvothermal conditions. It is of interest that the formic ligand (L 2 ) is not contained in the stating materials, but arises from the water molecule-enhanced CO 2 insertion during the solvothermal process. Both of the two compounds exhibit complicated three dimensional sandwich-like frameworks. - Graphical abstract: Two new lanthanide coordination polymers involving water molecule-enhanced CO 2 insertion resulting in the formation of formic anion and dimethylammonium cation were synthesized under solvothermal conditions.

  16. Investigation of the Hydantoin Monomer and its Interaction with Water Molecules

    Science.gov (United States)

    Gruet, Sébastien; Perez, Cristobal; Schnell, Melanie

    2017-06-01

    Hydantoin (Imidazolidine-2,4-dione, C_3H_4N_2O_2) is a five-membered heterocyclic compound of astrobiological interest. This molecule has been detected in carbonaceous chondrites [1], and its formation can rise from the presence of glycolic acid and urea, two prebiotic molecules [2]. The hydrolysis of hydantoin under acidic conditions can also produce glycine [3], an amino acid actively searched for in the interstellar medium. Spectroscopic data of hydantoin is very limited and mostly dedicated to the solid phase. The high resolution study in gas phase is restricted to the work recently published by Ozeki et al. reporting the pure rotational spectra of the ground state and two vibrational states of the molecule in the millimeter-wave region (90-370 GHz)[4]. Using chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy, we recorded the jet-cooled rotational spectra of hydantoin with water between 2 to 8 GHz. We observed the ground state of hydantoin monomer and several water complexes with one or two water molecules. All the observed species exhibit a hyperfine structure due to the two nitrogen atoms present in the molecule, which were fully resolved and analyzed. Additional experiments with a ^{18}O enriched water sample were realized to determine the oxygen-atom positions of the water monomers. These experiments yielded accurate structural information on the preferred water binding sites. The observed complexes and the interactions that hold them together, mainly strong directional hydrogen bonds, will be presented and discussed. [1] Shimoyama, A. and Ogasawara, R., Orig. Life Evol. Biosph., 32, 165-179, 2002. DOI:10.1023/A:1016015319112. [2] Menor-Salván, C. and Marín-Yaseli, M.R., Chem. Soc. Rev., 41(16), 5404-5415, 2012. DOI:10.1039/c2cs35060b. [3] De Marcellus P., Bertrand M., Nuevo M., Westall F. and Le Sergeant d'Hendecourt L., Astrobiology. 11(9), 847-854, 2011. DOI:10.1089/ast.2011.0677. [4] Ozeki, H., Miyahara R., Ihara H., Todaka S., Kobayashi

  17. Characterization of Listeria monocytogenes isolated from Ganges water, human clinical and milk samples at Varanasi, India.

    Science.gov (United States)

    Soni, Dharmendra K; Singh, Rakesh K; Singh, Durg V; Dubey, Suresh K

    2013-03-01

    Listeria monocytogenes isolated from Ganges water, human clinical and milk samples were characterized by antibiotic susceptibility, serotype identification, detection of virulence genes and ERIC- and REP-PCR fingerprint analyses. All isolates were uniformly resistant to ampicillin, except two isolates, and showed variable resistance to gentamicin, cotrimoxazole, ofloxacin, rifampicin and tetracycline. Of the 20 isolates found positive for pathogens, seven (four human and three water isolates) belong to serogroups 4b, 4d and 4e; six (one human and five water isolates) belong to serogroups 1/2c and 3c; four milk isolates belong to serogroups 1/2b and 3b; and three milk isolates belong to serogroups 1/2a and 3a. Two water isolates, all human isolates, except one (Pb1) lacking inlJ gene, and three milk isolates possess inlA, inlC, plcA, prfA, actA, hlyA and iap genes. The remaining water and milk isolates showed variable presence of inlJ, plcA, prfA, and iap genes. ERIC- and REP-PCR based analyses collectively indicated that isolates of human clinical samples belong to identical or similar clone and isolates of water and milk samples belong to different clones. Overall study demonstrates the prevalence of pathogenic L. monocytogenes species in the environmental and clinical samples. Most of the isolates were resistant to commonly used antibiotics. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. A Raman spectroscopy study on the effects of intermolecular hydrogen bonding on water molecules absorbed by borosilicate glass surface

    Science.gov (United States)

    Li, Fabing; Li, Zhanlong; Wang, Ying; Wang, Shenghan; Wang, Xiaojun; Sun, Chenglin; Men, Zhiwei

    2018-05-01

    The structural forms of water/deuterated water molecules located on the surface of borosilicate capillaries have been first investigated in this study on the basis of the Raman spectral data obtained at different temperatures and under atmospheric pressure for molecules in bulk and also for molecules absorbed by borosilicate glass surface. The strongest two fundamental bands locating at 3063 cm-1 (2438 cm-1) in the recorded Raman spectra are assigned here to the Osbnd H (Osbnd D) bond stretching vibrations and they are compared with the corresponding bands observed at 3124 cm-1 (2325 cm-1) in the Raman spectrum of ice Ih. Our spectroscopic observations have indicated that the structure of water and deuterated water molecules on borosilicate surface is similar to that of ice Ih (hexagonal phase of ice). These observations have also indicated that water molecules locate on the borosilicate surface so as to construct a bilayer structure and that strong and weak intermolecular hydrogen bonds are formed between water/deuterated molecules and silanol groups on borosilicate surface. In accordance with these findings, water and deuterated water molecules at the interface of capillary have a higher melting temperature.

  19. Isolation and in silico evaluation of antidiabetic molecules of Cynodon dactylon (L.).

    Science.gov (United States)

    Annapurna, Hasthi V; Apoorva, Babu; Ravichandran, Natesan; Arun, Kallur Purushothaman; Brindha, Pemaiah; Swaminathan, Sethuraman; Vijayalakshmi, Mahadevan; Nagarajan, Arumugam

    2013-02-01

    Cynodon dactylon is a potential source of metabolites such as flavanoids, alkaloids, glycosides and β-sitosterol and has been traditionally employed to treat urinary tract and other microbial infections and dysentery. The present work attempts to evaluate the activity of C. dactylon extracts for glycemic control. Aqueous extracts of C. dactylon analyzed by HPLC-ESI MS have identified the presence of apigenin, luteolin, 6-C-pentosyl-8-C-hexosyl apigenin and 6-C-hexosyl-8-C-pentosyl luteolin. Evaluation of hypoglycemic activity through an extensive in silico docking approach with PPARγ (Peroxisome Proliferator-Activated Receptor), GLUT-4 (glucose transporter-4) and SGLT2 (sodium glucose co-transporter-2) revealed that luteolin, apigenin, 6-C-pentosyl-8-C-hexosyl apigenin, 6-C-hexosyl-8-C-pentosyl luteolin interact with SGLT2. Interactions of these molecules with Gln 295 and Asp 294 residues of SGLT2 have been shown to compare well with that of the phase III drug, dapagliflozin. These residues have been proven to be responsible for sugar sensing and transport. This work establishes C. dactylon extract as a potential SGLT2 inhibitor for diabetic neuropathy thus enabling a possibility of this plant extract as a new alternative to existing diabetic approaches. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Quantification of the Intracellular Life Time of Water Molecules to Measure Transport Rates of Human Aquaglyceroporins.

    Science.gov (United States)

    Palmgren, Madelene; Hernebring, Malin; Eriksson, Stefanie; Elbing, Karin; Geijer, Cecilia; Lasič, Samo; Dahl, Peter; Hansen, Jesper S; Topgaard, Daniel; Lindkvist-Petersson, Karin

    2017-12-01

    Orthodox aquaporins are transmembrane channel proteins that facilitate rapid diffusion of water, while aquaglyceroporins facilitate the diffusion of small uncharged molecules such as glycerol and arsenic trioxide. Aquaglyceroporins play important roles in human physiology, in particular for glycerol metabolism and arsenic detoxification. We have developed a unique system applying the strain of the yeast Pichia pastoris, where the endogenous aquaporins/aquaglyceroporins have been removed and human aquaglyceroporins AQP3, AQP7, and AQP9 are recombinantly expressed enabling comparative permeability measurements between the expressed proteins. Using a newly established Nuclear Magnetic Resonance approach based on measurement of the intracellular life time of water, we propose that human aquaglyceroporins are poor facilitators of water and that the water transport efficiency is similar to that of passive diffusion across native cell membranes. This is distinctly different from glycerol and arsenic trioxide, where high glycerol transport efficiency was recorded.

  1. Isolation of heterotrophic diazotrophic bacteria from estuarine surface waters.

    Science.gov (United States)

    Farnelid, Hanna; Harder, Jens; Bentzon-Tilia, Mikkel; Riemann, Lasse

    2014-10-01

    The wide distribution of diverse nitrogenase (nifH) genes affiliated with those of heterotrophic bacteria in marine and estuarine waters indicates ubiquity and an ecologically relevant role for heterotrophic N2 -fixers (diazotrophs) in aquatic nitrogen (N) cycling. However, the lack of cultivated representatives currently precludes an evaluation of their N2 -fixing capacity. In this study, microoxic or anoxic N-free media were inoculated with estuarine Baltic Sea surface water to select for N2 -fixers. After visible growth and isolation of single colonies on oxic plates or in anoxic agar tubes, nifH gene amplicons were obtained from 64 strains and nitrogenase activity, applying the acetylene reduction assay, was confirmed for 40 strains. Two strains, one Gammaproteobacterium affiliated with Pseudomonas and one Alphaproteobacterium affiliated with Rhodopseudomonas were shown to represent established members of the indigenous diazotrophic community in the Baltic Sea, with abundances of up to 7.9 × 10(4) and 4.7 × 10(4)  nifH copies l(-1) respectively. This study reports media for successful isolation of heterotrophic diazotrophs. The applied methodology and the obtained strains will facilitate future identification of factors controlling heterotrophic diazotrophic activity in aquatic environments, which is a prerequisite for understanding and evaluating their ecology and contribution to N cycling at local and regional scales. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  2. Neutralizing antibody and anti-retroviral drug sensitivities of HIV-1 isolates resistant to small molecule CCR5 inhibitors

    International Nuclear Information System (INIS)

    Pugach, Pavel; Ketas, Thomas J.; Michael, Elizabeth; Moore, John P.

    2008-01-01

    The small molecule CCR5 inhibitors are a new class of drugs for treating infection by human immunodeficiency virus type 1 (HIV-1). They act by binding to the CCR5 co-receptor and preventing its use during HIV-1-cell fusion. Escape mutants can be raised against CCR5 inhibitors in vitro and will arise when these drugs are used clinically. Here, we have assessed the responses of CCR5 inhibitor-resistant viruses to other anti-retroviral drugs that act by different mechanisms, and their sensitivities to neutralizing antibodies (NAbs). The rationale for the latter study is that the resistance pathway for CCR5 inhibitors involves changes in the HIV-1 envelope glycoproteins (Env), which are also targets for NAbs. The escape mutants CC101.19 and D1/85.16 were selected for resistance to AD101 and vicriviroc (VVC), respectively, from the primary R5 HIV-1 isolate CC1/85. Each escape mutant was cross-resistant to other small molecule CCR5 inhibitors (aplaviroc, maraviroc, VVC, AD101 and CMPD 167), but sensitive to protein ligands of CCR5: the modified chemokine PSC-RANTES and the humanized MAb PRO-140. The resistant viruses also retained wild-type sensitivity to the nucleoside reverse transcriptase inhibitor (RTI) zidovudine, the non-nucleoside RTI nevirapine, the protease inhibitor atazanavir and other attachment and fusion inhibitors that act independently of CCR5 (BMS-806, PRO-542 and enfuvirtide). Of note is that the escape mutants were more sensitive than the parental CC1/85 isolate to a subset of neutralizing monoclonal antibodies and to some sera from HIV-1-infected people, implying that sequence changes in Env that confer resistance to CCR5 inhibitors can increase the accessibility of some NAb epitopes. The need to preserve NAb resistance may therefore be a constraint upon how escape from CCR5 inhibitors occurs in vivo

  3. Preparation and isolation of dithiolene thiophosphoryl molecules as stable, protected forms of dithiolene ligands.

    Science.gov (United States)

    Arumugam, Kuppuswamy; Bollinger, James E; Fink, Mark; Donahue, James P

    2007-04-16

    The reaction of P4S10 with acyloins, RC(O)CH(OH)R, in refluxing dioxane, followed by the addition of alkylating agents, forms dithiolene thiophosphoryl thiolate compounds, (R2C2S2)P(S)(SR'), which are readily isolated and purified. The compounds that have been prepared and identified spectroscopically are those with R = p-anisyl, R' = Me (1); R = p-anisyl, R' = Bz (2); R = Ph, R' = Me (4); R = Et, R' = Bz (5). Compounds 1, 2, and 4 were structurally characterized by X-ray crystallography and found to possess a tetrahedral coordination geometry about the phosphorus atom, with overall Cs symmetry. In each case, the mirror plane bisects the dithiolene S-P-S chelate and contains the thiophosphoryl bond, which ranges in length from 1.9241(8) to 1.9361(7) A. The use of 2-(bromomethyl)naphthalene as organic electrophile in the P4S10/acyloin reaction produced bis(2-methylnaphthalenyl) disulfide as the only identifiable product. The substitution of Lawesson's reagent for P4S10 in reactions with acyloins produced deoxy acyloin rather than products resulting from chalcogen exchange. Compounds 1-2 and 4-5 are Group 5 analogues of 1,3-dithiol-2-ones, (R2C2S2)C=O, and undergo a similar hydrolysis in aqueous base to liberate ene-1,2-dithiolate dianions from which corresponding metal dithiolene complexes may be prepared. Deprotection of 1 in MeO-/MeOH, followed by the addition of NiCl2.6H2O and then I2, produces square planar [Ni(S2C2(C6H4-p-OCH3)2)2] (8) in 93% yield. A high-resolution structure of 8 (P) reveals dithiolene C-C and C-S bond lengths that are clearly indicative of the thionyl radical monoanionic nature of the ligand. The use of isolated (R2C2S2)P(S)(SR') compounds as a dithiolene ligand source for the preparation of metal dithiolene complexes offers the advantages of clean reactivity and high yield.

  4. Isolation and molecular characterization of biofouling bacteria and profiling of quorum sensing signal molecules from membrane bioreactor activated sludge.

    Science.gov (United States)

    Lade, Harshad; Paul, Diby; Kweon, Ji Hyang

    2014-02-04

    The formation of biofilm in a membrane bioreactor depends on the production of various signaling molecules like N-acyl homoserine lactones (AHLs). In the present study, a total of 200 bacterial strains were isolated from membrane bioreactor activated sludge and screened for AHLs production using two biosensor systems, Chromobacterium violaceum CV026 and Agrobacterium tumefaciens A136. A correlation between AHLs production and biofilm formation has been made among screened AHLs producing strains. The 16S rRNA gene sequence analysis revealed the dominance of Aeromonas and Enterobacter sp. in AHLs production; however few a species of Serratia, Leclercia, Pseudomonas, Klebsiella, Raoultella and Citrobacter were also identified. The chromatographic characterization of sludge extract showed the presence of a broad range of quorum sensing signal molecules. Further identification of sludge AHLs by thin layer chromatography bioassay and high performance liquid chromatography confirms the presence of C4-HSL, C6-HSL, C8-HSL, 3-oxo-C8-HSL, C10-HSL, C12-HSL, 3-oxo-C12-HSL and C14-HSL. The occurrence of AHLs in sludge extract and dominance of Aeromonas and Enterobacter sp. in activated sludge suggests the key role of these bacterial strains in AHLs production and thereby membrane fouling.

  5. Isolation and Molecular Characterization of Biofouling Bacteria and Profiling of Quorum Sensing Signal Molecules from Membrane Bioreactor Activated Sludge

    Directory of Open Access Journals (Sweden)

    Harshad Lade

    2014-02-01

    Full Text Available The formation of biofilm in a membrane bioreactor depends on the production of various signaling molecules like N-acyl homoserine lactones (AHLs. In the present study, a total of 200 bacterial strains were isolated from membrane bioreactor activated sludge and screened for AHLs production using two biosensor systems, Chromobacterium violaceum CV026 and Agrobacterium tumefaciens A136. A correlation between AHLs production and biofilm formation has been made among screened AHLs producing strains. The 16S rRNA gene sequence analysis revealed the dominance of Aeromonas and Enterobacter sp. in AHLs production; however few a species of Serratia, Leclercia, Pseudomonas, Klebsiella, Raoultella and Citrobacter were also identified. The chromatographic characterization of sludge extract showed the presence of a broad range of quorum sensing signal molecules. Further identification of sludge AHLs by thin layer chromatography bioassay and high performance liquid chromatography confirms the presence of C4-HSL, C6-HSL, C8-HSL, 3-oxo-C8-HSL, C10-HSL, C12-HSL, 3-oxo-C12-HSL and C14-HSL. The occurrence of AHLs in sludge extract and dominance of Aeromonas and Enterobacter sp. in activated sludge suggests the key role of these bacterial strains in AHLs production and thereby membrane fouling.

  6. Single-Molecule Imaging of DNAs with Sticky Ends at Water/Fused Silica Interface

    Energy Technology Data Exchange (ETDEWEB)

    Isailovic, Slavica [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    Total internal reflection fluorescence microscopy (TIRFM) was used to study intermolecular interactions of DNAs with unpaired (sticky) ends of different lengths at water/fused silica interface at the single-molecule level. Evanescent field residence time, linear velocity and adsorption/desorption frequency were measured in a microchannel for individual DNA molecules from T7, Lambda, and PSP3 phages at various pH values. The longest residence times and the highest adsorption/desorption frequencies at the constant flow at pH 5.5 were found for PSP3 DNA, followed by lower values for Lambda DNA, and the lowest values for T7 DNA. Since T7, Lambda, and PSP3 DNA molecules contain none, twelve and nineteen unpaired bases, respectively, it was concluded that the affinity of DNAs for the surface increases with the length of the sticky ends. This confirms that hydrophobic and hydrogen-bonding interactions between sticky ends and fused-silica surface are driving forces for DNA adsorption at the fused-silica surface. Described single-molecule methodology and results therein can be valuable for investigation of interactions in liquid chromatography, as well as for design of DNA hybridization sensors and drug delivery systems.

  7. Modeling the Release Kinetics of Poorly Water-Soluble Drug Molecules from Liposomal Nanocarriers

    Directory of Open Access Journals (Sweden)

    Stephan Loew

    2011-01-01

    Full Text Available Liposomes are frequently used as pharmaceutical nanocarriers to deliver poorly water-soluble drugs such as temoporfin, cyclosporine A, amphotericin B, and paclitaxel to their target site. Optimal drug delivery depends on understanding the release kinetics of the drug molecules from the host liposomes during the journey to the target site and at the target site. Transfer of drugs in model systems consisting of donor liposomes and acceptor liposomes is known from experimental work to typically exhibit a first-order kinetics with a simple exponential behavior. In some cases, a fast component in the initial transfer is present, in other cases the transfer is sigmoidal. We present and analyze a theoretical model for the transfer that accounts for two physical mechanisms, collisions between liposomes and diffusion of the drug molecules through the aqueous phase. Starting with the detailed distribution of drug molecules among the individual liposomes, we specify the conditions that lead to an apparent first-order kinetic behavior. We also discuss possible implications on the transfer kinetics of (1 high drug loading of donor liposomes, (2 attractive interactions between drug molecules within the liposomes, and (3 slow transfer of drugs between the inner and outer leaflets of the liposomes.

  8. Structural analysis on mutation residues and interfacial water molecules for human TIM disease understanding

    Science.gov (United States)

    2013-01-01

    Background Human triosephosphate isomerase (HsTIM) deficiency is a genetic disease caused often by the pathogenic mutation E104D. This mutation, located at the side of an abnormally large cluster of water in the inter-subunit interface, reduces the thermostability of the enzyme. Why and how these water molecules are directly related to the excessive thermolability of the mutant have not been investigated in structural biology. Results This work compares the structure of the E104D mutant with its wild type counterparts. It is found that the water topology in the dimer interface of HsTIM is atypical, having a "wet-core-dry-rim" distribution with 16 water molecules tightly packed in a small deep region surrounded by 22 residues including GLU104. These water molecules are co-conserved with their surrounding residues in non-archaeal TIMs (dimers) but not conserved across archaeal TIMs (tetramers), indicating their importance in preserving the overall quaternary structure. As the structural permutation induced by the mutation is not significant, we hypothesize that the excessive thermolability of the E104D mutant is attributed to the easy propagation of atoms' flexibility from the surface into the core via the large cluster of water. It is indeed found that the B factor increment in the wet region is higher than other regions, and, more importantly, the B factor increment in the wet region is maintained in the deeply buried core. Molecular dynamics simulations revealed that for the mutant structure at normal temperature, a clear increase of the root-mean-square deviation is observed for the wet region contacting with the large cluster of interfacial water. Such increase is not observed for other interfacial regions or the whole protein. This clearly suggests that, in the E104D mutant, the large water cluster is responsible for the subunit interface flexibility and overall thermolability, and it ultimately leads to the deficiency of this enzyme. Conclusions Our study

  9. In vitro characterization of multivalent adhesion molecule 7-based inhibition of multidrug-resistant bacteria isolated from wounded military personnel

    Science.gov (United States)

    Krachler, Anne Marie; Mende, Katrin; Murray, Clinton; Orth, Kim

    2012-01-01

    Treatment of wounded military personnel at military medical centers is often complicated by colonization and infection of wounds with pathogenic bacteria. These include nosocomially transmitted, often multidrug-resistant pathogens such as Acinetobacter baumannii-calcoaceticus complex, Pseudomonas aeruginosa and extended spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae. We analyzed the efficacy of multivalent adhesion molecule (MAM) 7-based anti-adhesion treatment of host cells against aforementioned pathogens in a tissue culture infection model. Herein, we observed that a correlation between two important hallmarks of virulence, attachment and cytotoxicity, could serve as a useful predictor for the success of MAM7-based inhibition against bacterial infections. Initially, we characterized 20 patient isolates (five from each pathogen mentioned above) in terms of genotypic diversity, antimicrobial susceptibility and important hallmarks of pathogenicity (biofilm formation, attachment to and cytotoxicity toward cultured host cells). All isolates displayed a high degree of genotypic diversity, which was also reflected by large strain-to-strain variability in terms of biofilm formation, attachment and cytotoxicity within each group of pathogen. Using non-pathogenic bacteria expressing MAM7 or latex beads coated with recombinant MAM7 for anti-adhesion treatment, we showed a decrease in cytotoxicity, indicating that MAM7 has potential as a prophylactic agent to attenuate infection by multidrug-resistant bacterial pathogens. PMID:22722243

  10. Mixing of alcohol and water molecules studied by neutron probe. Structure and dynamics

    International Nuclear Information System (INIS)

    Yoshida, Koji

    2001-01-01

    Structure of water/alcohol mixing solution was studied by three methods such as an isotope-exchanged neutron scattering method, RISM (Reference Interaction Site Model) integral equation and a neutron spin echo method. The principle of methods, experiments and results were reported. The results of experiments of water/tert-butyl alcohol (TBA) solution by the isotope-exchange neutron scattering method showed TBA molecule associated with each other through end methyl group. Especially this effect was the largest at x TBA = 0.06 and decreased with increasing the concentration of TBA. However, hydrogen bonding of TBA was very rare at x TBA = 0.06. By the partial radial distribution function obtained from RISM integral equation, it indicated that the structure of pure TBA became chain structure by hydrogen bond but changed to the structure contacted directly each hydrophobic group with increasing the concentration of water. Water/2-butoxyethanol (BE) mixing solution was measured by a neutron spin echo method. The activation energy of the diffusion coefficients obtained agreed to the energy of hydrogen bonding. The temperature response of diffusion coefficients showed the inverse of the experimental results obtained by the dynamic light scattering method. The difference between two measurement methods was different time scale and space scale. Namely, the object of the neutron scattering method is nano meter and nano second, but one of light scattering method many times over. It was proved from the above results that there was the cluster consisted of the same kind of molecule in the homogeneous two components solution, but the cluster was not stable and constantly exchanged with molecule, where the production and decay of the cluster is repeated at about nano sec. (S.Y.)

  11. Distinct difference of flaA genotypes of Legionella pneumophila between isolates from bath water and cooling tower water.

    Science.gov (United States)

    Amemura-Maekawa, Junko; Kura, Fumiaki; Chang, Bin; Suzuki-Hashimoto, Atsuko; Ichinose, Masayuki; Endo, Takuro; Watanabe, Haruo

    2008-09-01

    To investigate the genetic difference of Legionella pneumophila in human-made environments, we collected isolates of L. pneumophila from bath water (n = 167) and cooling tower water (n = 128) primarily in the Kanto region in 2001 and 2005. The environmental isolates were serogrouped and sequenced for a target region of flaA. A total of 14 types of flaA genotypes were found: 10 from cooling tower water and nine from bath water. The flaA genotypes of isolates from cooling tower water were quite different from those of bath water.

  12. Influence of the water molecules near surface of viral protein on virus activation process

    Energy Technology Data Exchange (ETDEWEB)

    O, Shepelenko S; S, Salnikov A; V, Rak S; P, Goncharova E; B, Ryzhikov A, E-mail: shep@vector.nsc.r, E-mail: shep@ngs.r [Federal State Research Institution State Research Center of Virology and Biotechnology VECTOR of the Federal Service for Surveillance in Consumer Rights Protection and Human Well-being (FSRI SRC VB VECTOR) Koltsovo, Novosibirsk Region (Russian Federation)

    2009-06-01

    The infection of a cell with influenza virus comprises the stages of receptor binding to the cell membrane, endocytosis of virus particle, and fusion of the virus envelope and cell endosome membrane, which is determined by the conformational changes in hemagglutinin, a virus envelope protein, caused by pH decrease within the endosome. The pH value that induces conformation rearrangements of hemagglutinin molecule considerably varies for different influenza virus strains, first and foremost, due to the differences in amino acid structure of the corresponding proteins. The main goal of this study was to construct a model making it possible to assess the critical pH value characterizing the fusogenic activity of influenza virus hemagglutinin from the data on hemagglutinin structure and experimental verification of this model. Under this model, we assume that when the electrostatic force between interacting hemagglutinin molecules in the virus envelop exceeds a certain value, the hemagglutinin HA1 subunits are arranged so that they form a cavity sufficient for penetration of water molecules. This event leads to an irreversible hydration of the inner fragments of hemagglutinin molecule in a trimer and to the completion of conformational changes. The geometry of electrostatic field in hemagglutinin trimer was calculated taking into account the polarization effects near the interface of two dielectrics, aqueous medium and protein macromolecule. The critical pH values for the conformational changes in hemagglutinin were measured by the erythrocyte hemolysis induced by influenza virus particles when decreasing pH. The critical pH value conditionally separating the pH range into the regions with and without the conformational changes was calculated for several influenza virus H1N1 and H3N2 strains based on the data on the amino acid structure of the corresponding hemagglutinin molecules. Comparison of the theoretical and experimental values of critical pH values for

  13. Ab Initio Density Functional Theory Investigation of the Interaction between Carbon Nanotubes and Water Molecules during Water Desalination Process

    Directory of Open Access Journals (Sweden)

    Loay A. Elalfy

    2013-01-01

    Full Text Available Density functional theory calculations using B3LYP/3-21G level of theory have been implemented on 6 carbon nanotubes (CNTs structures (3 zigzag and 3 armchair CNTs to study the energetics of the reverse osmosis during water desalination process. Calculations of the band gap, interaction energy, highest occupied molecular orbital, lowest unoccupied molecular orbital, electronegativity, hardness, and pressure of the system are discussed. The calculations showed that the water molecule that exists inside the CNT is about 2-3 Å away from its wall. The calculations have proven that the zigzag CNTs are more efficient for reverse osmosis water desalination process than armchair CNTs as the reverse osmosis process requires pressure of approximately 200 MPa for armchair CNTs, which is consistent with the values used in molecular dynamics simulations, while that needed when using zigzag CNTs was in the order of 60 MPa.

  14. The adsorption and dissociation of water molecule on goethite (010) surface: A DFT approach

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Long, E-mail: shuweixia@ouc.edu.cn [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, College of Chemistry and Chemical Engineering (China); Xiu, Fangyuan [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, College of Chemistry and Chemical Engineering (China); Qiu, Meng [Qingdao Institute of Bioenergy and Bioprocess Technology (China); Xia, Shuwei; Yu, Liangmin [Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, College of Chemistry and Chemical Engineering (China)

    2017-01-15

    Graphical abstract: The optimized structure of hydrated goethite (010) surface with medium water coverage (water density about 6.7 H{sub 2}O/nm{sup 2}). - Highlights: • Stable adsorption and dissociation structure of H{sub 2}O on goethite (010) surface was investigated by DFT. • Reasonable path for water dissociation was proposed by transitional state analysis. • The mechanism of water adsorption on goethite and binding nature were revealed by PDOS. - Abstract: Using density functional theory (DFT) calculation, we investigate the configuration, stability and electronic properties of fresh cleaved (010) goethite surface (Pnma) and this surface exposed to water monolayer at low, medium and high coverage. Water is predicted to be chemisorbed to the surface, together with the surface reconstruction. The interaction energy of the most stable configuration of both low and medium coverage per water molecule is almost the same (−1.17 eV), while that of high coverage is much lower (less than 1.03 eV). It indicates that highly hydrated surface is less stable. PDOS analysis reveals the adsorption of H{sub 2}O is due to the formation of Fe−O bond, caused by overlapping of Fe's 3d and O's 2p orbitals. Dissociation processes at low and medium water coverage are non-spontaneous; while at high coverage, it can undertake spontaneously both thermodynamically and dynamically. The dissociation paths of all three water coverage are the similar. The proton from one adsorbed water is likely to dissociate to bind to the vicinal surface μ{sub 3}−O as an intermediate product; the proton belonged to μ{sub 3}−O transferred to the neighbor surface μ{sub 2}−O as the dissociative configuration.

  15. Bifidobacterium aquikefiri sp. nov., isolated from water kefir.

    Science.gov (United States)

    Laureys, David; Cnockaert, Margo; De Vuyst, Luc; Vandamme, Peter

    2016-03-01

    A novel Bifidobacterium , strain LMG 28769 T , was isolated from a household water kefir fermentation process. Cells were Gram-stain-positive, non-motile, non-spore-forming, catalase-negative, oxidase-negative and facultatively anaerobic short rods. Analysis of its 16S rRNA gene sequence revealed Bifidobacterium crudilactis and Bifidobacterium psychraerophilum (97.4 and 97.1 % similarity towards the respective type strain sequences) as nearest phylogenetic neighbours. Its assignment to the genus Bifidobacterium was confirmed by the presence of fructose 6-phosphate phosphoketolase activity. Analysis of the hsp60 gene sequence revealed very low similarity with nucleotide sequences in the NCBI nucleotide database. The genotypic and phenotypic analyses allowed the differentiation of strain LMG 28769 T from all recognized Bifidobacterium species. Strain LMG 28769 T ( = CCUG 67145 T  = R 54638 T ) therefore represents a novel species, for which the name Bifidobacterium aquikefiri sp. nov. is proposed.

  16. Multipole moments of water molecules in clusters and ice Ih from first principles calculations

    International Nuclear Information System (INIS)

    Batista, E.R.; Xantheas, S.S.; Jonsson, H.

    1999-01-01

    We have calculated molecular multipole moments for water molecules in clusters and in ice Ih by partitioning the charge density obtained from first principles calculations. Various schemes for dividing the electronic charge density among the water molecules were used. They include Bader close-quote s zero flux surfaces and Voronoi partitioning schemes. A comparison was also made with an induction model including dipole, dipole-quadrupole, quadrupole-quadrupole polarizability and first hyperpolarizability as well as fixed octopole and hexadecapole moments. We have found that the different density partitioning schemes lead to widely different values for the molecular multipoles, illustrating how poorly defined molecular multipoles are in clusters and condensed environments. For instance, the magnitude of the molecular dipole moment in ice Ih ranges between 2.3 D and 3.1 D depending on the partitioning scheme used. Within each scheme, though, the value for the molecular dipole moment in ice is larger than in the hexamer. The magnitude of the molecular dipole moment in the clusters shows a monotonic increase from the gas phase value to the one in ice Ih, with the molecular dipole moment in the water ring hexamer being smaller than the one in ice Ih for all the partitioning schemes used. copyright 1999 American Institute of Physics

  17. Continuum Navier-Stokes modelling of water ow past fullerene molecules

    DEFF Research Database (Denmark)

    Walther, J. H.; Popadic, A.; Koumoutsakos, P.

    We present continuum simulations of water flow past fullerene molecules. The governing Navier-Stokes equations are complemented with the Navier slip boundary condition with a slip length that is extracted from related molecular dynamics simulations. We find that several quantities of interest...... as computed by the present model are in good agreement with results from atomistic and atomistic-continuum simulations at a fraction of the computational cost. We simulate the flow past a single fullerene and an array of fullerenes and demonstrate that such nanoscale flows can be computed efficiently...

  18. Continuum Navier-Stokes modelling of water flow past fullerene molecules

    DEFF Research Database (Denmark)

    Walther, J. H.; Popadic, A.; Koumoutsakos, P.

    We present continuum simulations of water flow past fullerene molecules. The governing Navier-Stokes equations are complemented with the Navier slip boundary condition with a slip length that is extracted from related molecular dynamics simulations. We find that several quantities of interest...... as computed by the present model are in good agreement with results from atomistic and atomistic-continuum simulations at a fraction of the computational cost. We simulate the flow past a single fullerene and an array of fullerenes and demonstrate that such nanoscale flows can be computed efficiently...

  19. Explicit Consideration of Water Molecules to Study Vibrational Circular DICHROÎSM of Monosaccharide's

    Science.gov (United States)

    Moussi, Sofiane; Ouamerali, Ourida

    2014-06-01

    Carbohydrates have multiples roles in biological systems. It has been found that the glycoside bond is fundamentally important in many aspects of chemistry and biology and forms the basis of carbohydrate chemistry. That means the stereochemical information, namely, glycosidic linkages α or β, gives an significant features of the carbohydrate glycosidation position of the glycosylic acceptor. For these reasons, much effort was made for the synthesis and analysis of the glycoside bond. Vibrational circular dichroism VCD has some advantages over conventional electronic circular dichroism (ECD) due to the applicability to all organic molecules and the reliability of ab initio quantum calculation. However, for a molecule with many chiral centers such as carbohydrates, determination of the absolute configuration tends to be difficult because the information from each stereochemical center is mixed and averaged over the spectrum. In the CH stretching region, only two VCD studies on carbohydrates have been reported and spectra--structure correlation, as determined for the glycoside band, remains to be investigated. T. Taniguchi and collaborators report that methyl glycosides exhibit a characteristic VCD peak, the sign of which solely reflects the C-1 absolute configuration. This work is a theoretical contribution to study the behaviour of VCD spectrum's of the monosaccharides when the water molecules are taken explicitly. This study is focused on six different monosaccharides in theirs absolute configuration R and S. We used the method of density functional theory DFT by means of the B3LYP hybrid functional and 6-31G * basis set.

  20. Isolation of reovirus T3D mutants capable of infecting human tumor cells independent of junction adhesion molecule-A.

    Directory of Open Access Journals (Sweden)

    Diana J M van den Wollenberg

    Full Text Available Mammalian Reovirus is a double-stranded RNA virus with a distinctive preference to replicate in and lyse transformed cells. On that account, Reovirus type 3 Dearing (T3D is clinically evaluated as oncolytic agent. The therapeutic efficacy of this approach depends in part on the accessibility of the reovirus receptor Junction Adhesion Molecule-A (JAM-A on the target cells. Here, we describe the isolation and characterization of reovirus T3D mutants that can infect human tumor cells independent of JAM-A. The JAM-A-independent (jin mutants were isolated on human U118MG glioblastoma cells, which do not express JAM-A. All jin mutants harbour mutations in the S1 segments close to the region that encodes the sialic acid-binding pocket in the shaft of the spike protein. In addition, two of the jin mutants encode spike proteins with a Q336R substitution in their head domain. The jin mutants can productively infect a wide range of cell lines that resist wt reovirus T3D infection, including chicken LMH cells, hamster CHO cells, murine endothelioma cells, human U2OS and STA-ET2.1 cells, but not primary human fibroblasts. The jin-mutants rely on the presence of sialic-acid residues on the cell surface for productive infection, as is evident from wheat germ agglutinin (WGA inhibition experiments, and from the jin-reovirus resistance of CHO-Lec2 cells, which have a deficiency of sialic-acids on their glycoproteins. The jin mutants may be useful as oncolytic agents for use in tumors in which JAM-A is absent or inaccessible.

  1. Water and oxygen induced degradation of small molecule organic solar cells

    DEFF Research Database (Denmark)

    Hermenau, Martin; Riede, Moritz; Leo, Karl

    2011-01-01

    Small molecule organic solar cells were studied with respect to water and oxygen induced degradation by mapping the spatial distribution of reaction products in order to elucidate the degradation patterns and failure mechanisms. The active layers consist of a 30 nm bulk heterojunction formed......,4′-diamine p-doped with C60F36 (MeO-TPD:C60F36), which acted as hole transporting layer. Indium-tin-oxide (ITO) and aluminum served as hole and electron collecting electrode, respectively. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) in conjunction...... of aluminum oxide at the BPhen/Al interface, and diffusion of water into the ZnPc:C60 layer where ZnPc becomes oxidized. Finally, diffusion from the electrodes was found to have no or a negligible effect on the device lifetime....

  2. Conserved hydrogen bonds and water molecules in MDR HIV-1 protease substrate complexes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zhigang [Wayne State Univ., Detroit, MI (United States); Case Western Reserve Univ., Cleveland, OH (United States); Harbor Hospital Baltimore, MD (United States); Wang, Yong [Wayne State Univ., Detroit, MI (United States); Yedidi, Ravikiran S. [Wayne State Univ., Detroit, MI (United States); National Institutes of Health, Bethesda, MD (United States); Dewdney, Tamaria G. [Wayne State Univ., Detroit, MI (United States); Reiter, Samuel J. [Wayne State Univ., Detroit, MI (United States); Brunzelle, Joseph S. [Northwestern Univ. Feinberg School of Medicine, Chicago, IL (United States); Kovari, Iulia A. [Wayne State Univ., Detroit, MI (United States); Kovari, Ladislau C. [Wayne State Univ., Detroit, MI (United States)

    2012-12-19

    Success of highly active antiretroviral therapy (HAART) in anti-HIV therapy is severely compromised by the rapidly developing drug resistance. HIV-1 protease inhibitors, part of HAART, are losing their potency and efficacy in inhibiting the target. Multi-drug resistant (MDR) 769 HIV-1 protease (resistant mutations at residues 10, 36, 46, 54, 62, 63, 71, 82, 84, 90) was selected for the present study to understand the binding to its natural substrates. The nine crystal structures of MDR769 HIV-1 protease substrate hepta-peptide complexes were analyzed in order to reveal the conserved structural elements for the purpose of drug design against MDR HIV-1 protease. Our structural studies demonstrated that highly conserved hydrogen bonds between the protease and substrate peptides, together with the conserved crystallographic water molecules, played a crucial role in the substrate recognition, substrate stabilization and protease stabilization. Additionally, the absence of the key flap-ligand bridging water molecule might imply a different catalytic mechanism of MDR769 HIV-1 protease compared to that of wild type (WT) HIV-1 protease.

  3. Tuning dissociation using isoelectronically doped graphene and hexagonal boron nitride: Water and other small molecules

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hamdani, Yasmine S. [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom); Alfè, Dario [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT (United Kingdom); Lilienfeld, O. Anatole von [Institute of Physical Chemistry and National Center for Computational Design and Discovery of Novel Materials (MARVEL), Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel (Switzerland); Michaelides, Angelos, E-mail: angelos.michaelides@ucl.ac.uk [Thomas Young Centre and London Centre for Nanotechnology, 17–19 Gordon Street, London WC1H 0AH (United Kingdom); Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    2016-04-21

    Novel uses for 2-dimensional materials like graphene and hexagonal boron nitride (h-BN) are being frequently discovered especially for membrane and catalysis applications. Still however, a great deal remains to be understood about the interaction of environmentally and industrially relevant molecules such as water with these materials. Taking inspiration from advances in hybridising graphene and h-BN, we explore using density functional theory, the dissociation of water, hydrogen, methane, and methanol on graphene, h-BN, and their isoelectronic doped counterparts: BN doped graphene and C doped h-BN. We find that doped surfaces are considerably more reactive than their pristine counterparts and by comparing the reactivity of several small molecules, we develop a general framework for dissociative adsorption. From this a particularly attractive consequence of isoelectronic doping emerges: substrates can be doped to enhance their reactivity specifically towards either polar or non-polar adsorbates. As such, these substrates are potentially viable candidates for selective catalysts and membranes, with the implication that a range of tuneable materials can be designed.

  4. Serratia aquatilis sp. nov., isolated from drinking water systems.

    Science.gov (United States)

    Kämpfer, Peter; Glaeser, Stefanie P

    2016-01-01

    A cream-white-pigmented, oxidase-negative bacterium (strain 2015-2462-01T), isolated from a drinking water system, was investigated in detail to determine its taxonomic position. Cells of the isolate were rod-shaped and stained Gram-negative. A comparison of the 16S rRNA gene sequence of strain 2015-2462-01T with sequences of the type strains of closely related species of the genus Serratia revealed highest similarity to Serratia fonticola (98.4 %), Serratia proteamaculans (97.8 %), Serratia liquefaciens and Serratia grimesii (both 97.7 %). 16S rRNA gene sequence similarities to all other Serratia species were below 97.4 %. Multilocus sequence analysis (MLSA) on the basis of concatenated partial gyrB, rpoB, infB and atpD gene sequences showed a clear distinction of strain 2015-2462-01T from the type strains of the closest related Serratia species. The fatty acid profile of the strain consisted of C16 : 1 ω7c, C16 : 0; C14 : 0 and C14 : 0 3-OH/iso-C16 : 1 I as major components. DNA-DNA hybridizations between 2015-2462-01T and S. fonticola ATCC 29844T resulted in a relatedness value of 27 % (reciprocal 20 %). This DNA-DNA hybridization result in combination with the MLSA results and the differential biochemical properties indicated that strain 2015-2462-01T represents a novel species of the genus Serratia, for which the name Serratia aquatilis sp. nov. is proposed. The type strain is 2015-2462-01T ( = LMG 29119T = CCM 8626T).

  5. Identification of Carboxylate, Phosphate, and Phenoxide Functionalities in Deprotonated Molecules Related to Drug Metabolites via Ion-Molecule Reactions with water and Diethylhydroxyborane

    Science.gov (United States)

    Zhu, Hanyu; Ma, Xin; Kong, John Y.; Zhang, Minli; Kenttämaa, Hilkka I.

    2017-10-01

    Tandem mass spectrometry based on ion-molecule reactions has emerged as a powerful tool for structural elucidation of ionized analytes. However, most currently used reagents were designed to react with protonated analytes, making them suboptimal for acidic analytes that are preferentially detected in negative ion mode. In this work we demonstrate that the phenoxide, carboxylate, and phosphate functionalities can be identified in deprotonated molecules by use of a combination of two reagents, diethylmethoxyborane (DEMB) and water. A novel reagent introduction setup that allowed DEMB and water to be separately introduced into the ion trap region of the mass spectrometer was developed to facilitate fundamental studies of this reaction. A new reagent, diethylhydroxyborane (DEHB), was generated inside the ion trap by hydrolysis of DEMB on introduction of water. Most carboxylates and phenoxides formed a DEHB adduct, followed by addition of one water molecule and subsequent ethane elimination (DEHB adduct +H2O - CH3CH3) as the major product ion. Phenoxides with a hydroxy group adjacent to the deprotonation site and phosphates formed a DEHB adduct, followed by ethane elimination (DEHB adduct - CH3CH3). Deprotonated molecules with strong intramolecular hydrogen bonds or without the aforementioned functionalities, including sulfates, were unreactive toward DEHB/H2O. Reaction mechanisms were explored via isotope labeling experiments and quantum chemical calculations. The mass spectrometry method allowed the differentiation of phenoxide-, carboxylate-, phosphate-, and sulfate-containing analytes. Finally, it was successfully coupled with high-performance liquid chromatography for the analysis of a mixture containing hymecromone, a biliary spasm drug, and its three possible metabolites. [Figure not available: see fulltext.

  6. Control of unidirectional transport of single-file water molecules through carbon nanotubes in an electric field.

    Science.gov (United States)

    Su, Jiaye; Guo, Hongxia

    2011-01-25

    The transport of water molecules through nanopores is not only crucial to biological activities but also useful for designing novel nanofluidic devices. Despite considerable effort and progress that has been made, a controllable and unidirectional water flow is still difficult to achieve and the underlying mechanism is far from being understood. In this paper, using molecular dynamics simulations, we systematically investigate the effects of an external electric field on the transport of single-file water molecules through a carbon nanotube (CNT). We find that the orientation of water molecules inside the CNT can be well-tuned by the electric field and is strongly coupled to the water flux. This orientation-induced water flux is energetically due to the asymmetrical water-water interaction along the CNT axis. The wavelike water density profiles are disturbed under strong field strengths. The frequency of flipping for the water dipoles will decrease as the field strength is increased, and the flipping events vanish completely for the relatively large field strengths. Most importantly, a critical field strength E(c) related to the water flux is found. The water flux is increased as E is increased for E ≤ E(c), while it is almost unchanged for E > E(c). Thus, the electric field offers a level of governing for unidirectional water flow, which may have some biological applications and provides a route for designing efficient nanopumps.

  7. [Interactions of DNA bases with individual water molecules. Molecular mechanics and quantum mechanics computation results vs. experimental data].

    Science.gov (United States)

    Gonzalez, E; Lino, J; Deriabina, A; Herrera, J N F; Poltev, V I

    2013-01-01

    To elucidate details of the DNA-water interactions we performed the calculations and systemaitic search for minima of interaction energy of the systems consisting of one of DNA bases and one or two water molecules. The results of calculations using two force fields of molecular mechanics (MM) and correlated ab initio method MP2/6-31G(d, p) of quantum mechanics (QM) have been compared with one another and with experimental data. The calculations demonstrated a qualitative agreement between geometry characteristics of the most of local energy minima obtained via different methods. The deepest minima revealed by MM and QM methods correspond to water molecule position between two neighbor hydrophilic centers of the base and to the formation by water molecule of hydrogen bonds with them. Nevertheless, the relative depth of some minima and peculiarities of mutual water-base positions in' these minima depend on the method used. The analysis revealed insignificance of some differences in the results of calculations performed via different methods and the importance of other ones for the description of DNA hydration. The calculations via MM methods enable us to reproduce quantitatively all the experimental data on the enthalpies of complex formation of single water molecule with the set of mono-, di-, and trimethylated bases, as well as on water molecule locations near base hydrophilic atoms in the crystals of DNA duplex fragments, while some of these data cannot be rationalized by QM calculations.

  8. Finite-bias electronic transport of molecules in a water solution

    KAUST Repository

    Rungger, Ivan; Chen, X.; Sanvito, Stefano; Schwingenschlö gl, Udo

    2010-01-01

    The effects of water wetting conditions on the transport properties of molecular nanojunctions are investigated theoretically by using a combination of empirical-potential molecular-dynamics and first-principles electronic-transport calculations. These are at the level of the nonequilibrium Green’s-function method implemented for self-interaction corrected density-functional theory. We find that water effectively produces electrostatic gating to the molecular junction with a gating potential determined by the time-averaged water dipole field. Such a field is large for the polar benzene-dithiol molecule, resulting in a transmission spectrum shifted by about 0.6 eV with respect to that of the dry junction. The situation is drastically different for carbon nanotubes (CNTs). In fact, because of their hydrophobic nature the gating is almost negligible so that the average transmission spectrum of wet Au/CNT/Au junctions is essentially the same as that in dry conditions. This suggests that CNTs can be used as molecular interconnects also in water-wet situations, for instance, as tips for scanning tunnel microscopy in solution or in biological sensors.

  9. Finite-bias electronic transport of molecules in a water solution

    KAUST Repository

    Rungger, Ivan

    2010-06-04

    The effects of water wetting conditions on the transport properties of molecular nanojunctions are investigated theoretically by using a combination of empirical-potential molecular-dynamics and first-principles electronic-transport calculations. These are at the level of the nonequilibrium Green’s-function method implemented for self-interaction corrected density-functional theory. We find that water effectively produces electrostatic gating to the molecular junction with a gating potential determined by the time-averaged water dipole field. Such a field is large for the polar benzene-dithiol molecule, resulting in a transmission spectrum shifted by about 0.6 eV with respect to that of the dry junction. The situation is drastically different for carbon nanotubes (CNTs). In fact, because of their hydrophobic nature the gating is almost negligible so that the average transmission spectrum of wet Au/CNT/Au junctions is essentially the same as that in dry conditions. This suggests that CNTs can be used as molecular interconnects also in water-wet situations, for instance, as tips for scanning tunnel microscopy in solution or in biological sensors.

  10. Orbiting Water Molecules Dance to Tune Of Galaxy's "Central Engine," Astronomers Say

    Science.gov (United States)

    2000-01-01

    A disk of water molecules orbiting a supermassive black hole at the core of a galaxy 60 million light-years away is "reverberating" in response to variations in the energy output from the galaxy's powerful "central engine" close to the black hole, astronomers say. The team of astronomers used the National Science Foundation's (NSF) Very Large Array (VLA) radio telescope in New Mexico and the 100-meter-diameter radio telescope of the Max Planck Institute for Radio Astronomy at Effelsberg, Germany, to observe the galaxy NGC 1068 in the constellation Cetus. They announced their findings today at the American Astronomical Society's meeting in Atlanta. The water molecules, in a disk some 5 light-years in diameter, are acting as a set of giant cosmic radio-wave amplifiers, called masers. Using energy radiated by the galaxy's "central engine," the molecules strengthen, or brighten, radio emission at a particular frequency as seen from Earth. "We have seen variations in the radio 'brightness' of these cosmic amplifiers that we believe were caused by variations in the energy output of the central engine," said Jack Gallimore, an astronomer at the National Radio Astronomy Observatory (NRAO) in Charlottesville, VA. "This could provide us with a valuable new tool for learning about the central engine itself," he added. Gallimore worked with Stefi Baum of the Space Telescope Science Institute in Baltimore, MD; Christian Henkel of the Max Planck Institute for Radio Astronomy in Bonn, Germany; Ian Glass of the South African Astronomical Observatory; Mark Claussen of the NRAO in Socorro, NM; and Almudena Prieto of the European Southern Observatory in Munich, Germany. "Our observations show that NGC 1068 is the second-known case of a giant disk of water molecules orbiting a supermassive black hole at a galaxy's core," Gallimore said. The first case was the galaxy NGC 4258 (Messier 106), whose disk of radio-amplifying water molecules was measured by the NSF's Very Long Baseline

  11. Alicyclobacillus fodiniaquatilis sp. nov., isolated from acid mine water.

    Science.gov (United States)

    Zhang, Bo; Wu, Yu-Fan; Song, Jin-Long; Huang, Zhong-Sheng; Wang, Bao-Jun; Liu, Shuang-Jiang; Jiang, Cheng-Ying

    2015-12-01

    Two novel, Gram-stain-variable, moderately thermophilic, acidophilic, rod-shaped, endospore-forming bacteria, G45-16T and G45-17, were isolated from acid mine water of Zijin copper mine in Fujian Province, China. Phylogenetic analysis of 16S rRNA gene sequences showed that they were closely related to Alicyclobacillus acidoterrestris ATCC 49025T with sequence similarities of 96.8 %. Cells grew aerobically at 20-45 °C (optimum, 40 °C), at pH 2.5-5.5(optimum, pH 3.5) and in the presence of 0-4.0 % (w/v) NaCl. Strains contained MK-7 as the major menaquinone and the major cellular fatty acids were ω-cyclohexane C19 : 0 and ω-cyclohexane C17 : 0. The DNA G+C content was 51.3 and 49.8 mol% (Tm) for G45-16T and G45-17, respectively. On the basis of phenotypic, chemotaxonomic and phylogenetic comparisons with their relatives and DNA-DNA relatedness values, it is concluded that strains G45-16T and G45-17 represent a novel species within the genus Alicyclobacillus, for which the name Alicyclobacillus fodiniaquatilis sp. nov. is proposed; the type strain is G45-16T(=CGMCC 1.15049T=NBRC 111483T).

  12. Legionella saoudiensis sp. nov., isolated from a sewage water sample.

    Science.gov (United States)

    Bajrai, Leena Hussein; Azhar, Esam Ibraheem; Yasir, Muhammad; Jardot, Priscilla; Barrassi, Lina; Raoult, Didier; La Scola, Bernard; Pagnier, Isabelle

    2016-11-01

    A Gram-stain-negative, bacilli-shaped bacterial strain, LS-1T, was isolated from a sewage water sample collected in Jeddah, Saudi Arabia. The taxonomic position of strain LS-1T was investigated using a polyphasic taxonomic approach. Phylogenetic analysis based on 16S rRNA gene sequences and those of four other genes indicated that strain LS-1T belongs to the genus Legionella in the family Legionellaceae. Regarding the 16S rRNA gene, the most closely related species are Legionella rowbothamii LLAP-6T (98.6 %) and Legionella lytica L2T (98.5 %). The mip gene sequence of strain LS-1T showed 94 % sequence similarity with that of L. lytica L2T and 93 % similarity with that of L. rowbothamii LLAP-6T. Strain LS-1T grew optimally at a temperature of 32 °C on a buffered charcoal yeast extract (BCYE) agar plate in a 5 % CO2 atmosphere and had a flagellum. The combined phylogenetic, phenotypic and genomic sequence data suggest that strain LS-1T represents a novel species of the genus Legionella, for which the name Legionella saoudiensis sp. nov. is proposed. The type strain is LS-1T (=DSM 101682T=CSUR P2101T).

  13. Relationship between diffusivity of water molecules inside hydrating tablets and their drug release behavior elucidated by magnetic resonance imaging.

    Science.gov (United States)

    Kikuchi, Shingo; Onuki, Yoshinori; Kuribayashi, Hideto; Takayama, Kozo

    2012-01-01

    We reported previously that sustained release matrix tablets showed zero-order drug release without being affected by pH change. To understand drug release mechanisms more fully, we monitored the swelling and erosion of hydrating tablets using magnetic resonance imaging (MRI). Three different types of tablets comprised of polyion complex-forming materials and a hydroxypropyl methylcellulose (HPMC) were used. Proton density- and diffusion-weighted images of the hydrating tablets were acquired at intervals. Furthermore, apparent self-diffusion coefficient maps were generated from diffusion-weighted imaging to evaluate the state of hydrating tablets. Our findings indicated that water penetration into polyion complex tablets was faster than that into HPMC matrix tablets. In polyion complex tablets, water molecules were dispersed homogeneously and their diffusivity was relatively high, whereas in HPMC matrix tablets, water molecule movement was tightly restricted within the gel. An optimal tablet formulation determined in a previous study had water molecule penetration and diffusivity properties that appeared intermediate to those of polyion complex and HPMC matrix tablets; water molecules were capable of penetrating throughout the tablets and relatively high diffusivity was similar to that in the polyion complex tablet, whereas like the HPMC matrix tablet, it was well swollen. This study succeeded in characterizing the tablet hydration process. MRI provides profound insight into the state of water molecules in hydrating tablets; thus, it is a useful tool for understanding drug release mechanisms at a molecular level.

  14. Anisotropic conductivity tensor imaging in MREIT using directional diffusion rate of water molecules

    International Nuclear Information System (INIS)

    Kwon, Oh In; Jeong, Woo Chul; Sajib, Saurav Z K; Kim, Hyung Joong; Woo, Eung Je

    2014-01-01

    Magnetic resonance electrical impedance tomography (MREIT) is an emerging method to visualize electrical conductivity and/or current density images at low frequencies (below 1 KHz). Injecting currents into an imaging object, one component of the induced magnetic flux density is acquired using an MRI scanner for isotropic conductivity image reconstructions. Diffusion tensor MRI (DT-MRI) measures the intrinsic three-dimensional diffusion property of water molecules within a tissue. It characterizes the anisotropic water transport by the effective diffusion tensor. Combining the DT-MRI and MREIT techniques, we propose a novel direct method for absolute conductivity tensor image reconstructions based on a linear relationship between the water diffusion tensor and the electrical conductivity tensor. We first recover the projected current density, which is the best approximation of the internal current density one can obtain from the measured single component of the induced magnetic flux density. This enables us to estimate a scale factor between the diffusion tensor and the conductivity tensor. Combining these values at all pixels with the acquired diffusion tensor map, we can quantitatively recover the anisotropic conductivity tensor map. From numerical simulations and experimental verifications using a biological tissue phantom, we found that the new method overcomes the limitations of each method and successfully reconstructs both the direction and magnitude of the conductivity tensor for both the anisotropic and isotropic regions. (paper)

  15. Bond rearrangement caused by sudden single and multiple ionization of water molecules

    International Nuclear Information System (INIS)

    Ben-Itzhak, I.; Sayler, A. Max; Leonard, M.; Maseberg, J.W.; Hathiramani, D.; Wells, E.; Smith, M.A.; Xia, Jiangfan; Wang, Pengqian; Carnes, K.D.; Esry, B.D.

    2005-01-01

    Bond rearrangement, namely the dissociation of water into H 2 + +O q+ following ionization by fast proton and highly charged ion impact, was investigated. Single ionization by fast proton impact exhibits a strong isotopic effect, the dissociation of H 2 O + ->H 2 + +O being about twice as likely as D 2 O + ->D 2 + +O, with HDO + ->HD + +O in between. This suggests that the bond rearrangement does not happen during the slow dissociation, but rather during the very fast ionization, and thus H 2 + should also be produced when the water molecule is multiply ionized. We observed that the H 2 + +O + and H 2 + +O 2+ production in 1MeV/amu F 7+ +H 2 O collisions are 0.209+/-0.006% and 0.0665+/-0.003%, respectively, of the main double-ionization dissociation product, H 2 O 2+ ->H + +OH + . This ratio is similar to the triple to double ionization ratio in similar collisions with atomic targets thus suggesting that the bond-rearrangement fraction out of each ionization level is approximately constant. Similar dissociation channels in the heavier water isotopes, which are expected to be smaller, are under study. Finally, the fragmentation of HDO exhibits very strong isotopic preference for breaking the OH bond over the OD bond

  16. Adsorption of ethyl xanthate on ZnS(110) surface in the presence of water molecules: A DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Long, Xianhao [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Chen, Jianhua, E-mail: jhchen@gxu.edu.cn [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Guangxi Colleges and University Key Laboratory of Minerals Engineering, 530004 (China); Chen, Ye, E-mail: fby18@126.com [College of Resources and Metallurgy, Guangxi University, Nanning 530004 (China)

    2016-05-01

    Graphical abstract: - Highlights: • Adsorption of water molecules decreases the reactivity of surface Zn atom. • Copper impurities decrease the band gap of ZnS surface. • Copper impurities enhance the adsorption of xanthate on the ZnS surface. • Water molecules have little influence on the properties of Cu-substituted ZnS surface. • The xanthate S atom can interact with the surface S atom of Cu-substituted ZnS surface. - Abstracts: The interaction of collector with the mineral surface plays a very important role in the froth flotation of sphalerite. The adsorptions occurred at the interface between the mineral surface and waters; however most of DFT simulations are performed in vacuum, without consideration of water effect. Semiconductor surface has an obvious proximity effect, which will greatly influence the surface reactivity. To understand the mechanism of xanthate interacting with sphalerite surface in the presence of water molecules, the ethyl xanthate molecule adsorption on un-activated and Cu-activated ZnS(110) surface in the absence and presence of water molecules were performed using the density functional theory (DFT) method. The calculated results show that the adsorption of water molecules dramatically changes the properties of ZnS surface, resulting in decreasing the reactivity of surface Zn atoms with xanthate. Copper activation of ZnS surface changes the surface properties, leading to the totally different adsorption behaviors of xanthate. The presence of waters has little influence on the properties of Cu-activated ZnS surface. The xanthate S atom can interact with the surface S atom of Cu-substituted ZnS surface, which would result in the formation of dixanthogen.

  17. Two-dimensional crystallography of amphiphilic molecules at the air-water interface

    DEFF Research Database (Denmark)

    Jacquemain, D.; Grayer Wolf, S.; Leveiller, F.

    1992-01-01

    The advent of well-collimated, high-intensity synchrotron X-ray sources and the consequent development of surface-specific X-ray diffraction and fluorescence techniques have recently revolutionized the study of Langmuir monolayers at the air-liquid interface. These methods allowed for the first......, and review recent results obtained from them for Langmuir films. The methods have been successfully applied in the elucidation of the structure of crystalline aggregates of amphiphilic molecules such as alcohols, carboxylic acids and their salts, alpha-amino acids, and phospholipids at the water surface....... In addition, it became possible to monitor by diffraction the growth and dissolution of the crystalline self-aggregates as well as structural changes occurring by phase transitions. Furthermore, the surface X-ray methods shed new light on the structure of the underlying ionic layer of attached solvent...

  18. Isolation and identification of Legionella pneumophila from drinking water in Basra governorate, Iraq.

    Science.gov (United States)

    Al-Sulami, A A; Al-Taee, A M R; Yehyazarian, A A

    2013-11-01

    This study in Iraq investigated the occurrence of Legionella. pneumophila in different drinking-water sources in Basra governorate as well as the susceptibility of isolates to several antibiotics. A total of 222 water samples were collected in 2008-2009: 49 samples from water purification plants (at entry points, from precipitation tanks, from filtration tanks and at exit points), 127 samples of tap water; and 46 samples from tankers and plants supplying water by reverse osmosis. The findings confirmed the presence of L. pneumophila in sources of crude water, in general drinking water supplies and drinking water tankers. Of 258 isolates 77.1% were serotype 1 and 22.9% serotypes 2-15. All examined isolates displayed drug resistance, particularly to ampicillin, but were 100% susceptible to doxycycline. The prevalence of L. pneumophila, especially serogroup 1, is a strong indicator of unsuitability of drinking water and requires appropriate action.

  19. Approximative Krieger-Nelkin orientation averaging and anisotropy of water molecules vibrations; Aproksimativno Krieger-Nelkinovo orijentacijsko usrednjenje i anozotropija vibracija molekula lake vode

    Energy Technology Data Exchange (ETDEWEB)

    Markovic, M I [Elektrothenicki fakultet, Belgrade (Yugoslavia)

    1974-07-01

    Quantum-mechanics approach of water molecules dynamics should be taken into account for precise theoretical calculation of differential scattering cross sections of neutrons. Krieger and Nelkin have proposed an approximate method for averaging orientation of molecules regarding directions of incoming and scattered neutron. This paper shows that this approach can be successfully applied for general shape of water molecule vibration anisotropy.

  20. Hymenobacter seoulensis sp. nov., isolated from river water.

    Science.gov (United States)

    Lee, Jae-Jin; Lee, Yeon-Hee; Park, Su-Jin; Lee, Seung-Yeol; Park, Sangkyu; Kim, Myung Kyum; Ten, Leonid N; Jung, Hee-Young

    2017-04-01

    A Gram-stain-negative, aerobic, rod-shaped, non-motile and pink-pigmented bacterial strain, designated 16F7GT, was isolated from river water. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 16F7GT belongs to the genus Hymenobacter. The 16S rRNA gene sequence similarity to members of the genus Hymenobacter ranged from 90.5 to 97.4 %, and the most closely related strains were Hymenobacter rigui WPCB131T (97.4 %) and Hymenobacter xinjiangensis X2-1gT (97.3 %). Strain 16F7GT had <70 % DNA-DNA relatedness with H. rigui (32.8±7.8 %) and H. xinjiangensis (30.2±6.2 %), indicating that it represents a novel genospecies. Cells were catalase- and oxidase-positive. The genomic DNA G+C content was 56.6 mol%. The major fatty acids were summed feature 4 (C17 : 1iso I/C17 : 1 anteiso B; 19.8 %), summed feature 3 (C16 : 1ω7c/C16 : 1ω6c; 18.4 %), C15 : 0 iso (17.0 %), C16 : 1ω5c (11.8 %) and C15 : 0 anteiso (9.8 %). The major polar lipid was phosphatidylethanolamine and the predominant respiratory quinone was menaquinone 7 (MK-7). Based on the phylogenetic, phenotypic, genotypic and chemotaxonomic analyses, it is concluded that strain 16F7GT represents a novel species within the genus Hymenobacter, for which the name Hymenobacter seoulensis sp. nov. is proposed. The type strain is 16F7GT (=KCTC 52197T=JCM 31655T).

  1. Antibiotic resistance and biofilm formation of some bacteria isolated from sediment, water and fish farms in Malaysia

    Science.gov (United States)

    Faja, Orooba Meteab; Usup, Gires; Ahmad, Asmat

    2018-04-01

    A total of 90 isolates of bacteria were isolated, from sediment (10) samples, water (10) samples and fish (12) samples (Sea bass, Snapper, Grouper and Tilapia). These include 22 isolates of bacteria from sediment, 28 isolates from water and 40 isolates from fish. All the isolates were tested for sensitivity to 13 antibiotics using disc diffusion method. The isolates showed high resistance to some antibiotics based on samples source. Isolates from sediment showed highest resistance toward novobiocin, kanamycin, ampicillin and streptomycin while isolates from water showed highest resistance against vancomycin, penicillin, streptomycin and tetracycline, in contrast, in fish sample showed highest resistance toward vancomycin, ampicillin, streptomycin and tetracycline. Most of the isolates showed biofilm formation ability with different degrees. Out of 22 bacteria isolates from water, two isolates were weak biofilm formers, six isolates moderate biofilm formers and fourteen isolates strong biofilm formers. While, out of 28 bacteria isolates from water one isolate was weak biofilm former, five isolates moderate biofilm formers and 22 strong biofilm formers Fish isolate showed three isolates (8%) moderate biofilm formers and 27 isolates strong biofilm formers. Biofilm formation was one of the factors that lead to antibiotic resistance of the bacterial isolates from these samples.

  2. Detection of blaCTX-M gene among Pseudomonas aeruginosa isolated from water samples in Baghdad

    Directory of Open Access Journals (Sweden)

    Saba R. Khdair

    2017-11-01

    Full Text Available A total of 50 environmental Pseudomonas aeruginosa isolates were collected from sewage and tap water in Baghdad, Iraq. The MICs of Cefotaxime and Ceftazidime were determined by using agar dilution method, The MIC ranged from 2 to 256 µg/ml.The results of antibiotic sensitivity test showed that among sewage P. aeruginosa isolates, resistance was observed most often to Ticarcillin (92%, Penicillin G (84%, Ceftazidime (12%, (8% for each of Cefotaxime and Ticarcillin. On the other hand, all tap water isolates were sensitive to Ofloxacin and Levofloxacin, Except (5% of isolates were resistant to Cefotaxime (25% to Ceftazidime and (95% to Ticarcillin. All isolates were tested for Extended-Spectrum β-Lactamase (ESBL production. Ten isolates (20% were found to be ESBL producers. All environmental P. aeruginosa isolates were screened for the presence of the blaCTX-M genes by application PCR, Only (30% of them were positive for this test.

  3. Synthesis of ZnO particles using water molecules generated in esterification reaction

    Science.gov (United States)

    Šarić, Ankica; Gotić, Marijan; Štefanić, Goran; Dražić, Goran

    2017-07-01

    Zinc oxide particles were synthesized without the addition of water by autoclaving (anhydrous) zinc acetate/alcohol and zinc acetate/acetic acid/alcohol solutions at 160 °C. The solvothermal synthesis was performed in ethanol or octanol. The structural, optical and morphological characteristics of ZnO particles were investigated by X-ray diffraction (XRD), UV-Vis spectroscopy, FE-SEM and TEM/STEM microscopy. 13C NMR spectroscopy revealed the presence of ester (ethyl- or octyl-acetate) in the supernatants which directly indicate the reaction mechanism. The formation of ester in this esterification reaction generated water molecule in situ, which hydrolyzed anhydrous zinc acetate and initiated nucleation and formation of ZnO. It was found that the size and shape of ZnO particles depend on the type of alcohol used as a solvent and on the presence of acetic acid in solution. The presence of ethanol in the ;pure; system without acetic acid favoured the formation of fine and uniform spherical ZnO nanoparticles (∼20 nm). With the addition of small amount of acetic acid the size of these small nanoparticles increased significantly up to a few hundred nanometers. The addition of small amount of acetic acid in the presence of octanol caused even more radical changes in the shape of ZnO particles, favouring the growth of huge rod-like particles (∼3 μm).

  4. Activation of a water molecule coordinated to manganese: four study cases

    International Nuclear Information System (INIS)

    Lassalle-Kaiser, B.

    2008-10-01

    The daunting energy consumption of western societies calls for the development of renewable energies. Among them, hydrogen stands as a major candidate. The cleanest way of producing hydrogen is water electro- or photolysis. This reaction is carried out in natural photosynthesis by a manganese-oxo cluster, the functioning of which remains unknown. Insight into this mechanism would greatly help the search for low-cost water splitting catalysts. Our contribution to this field is the understanding of the fundamental processes that govern the activation of water by manganese complexes. This manuscript describes our attempts to generate electrochemically mononuclear manganese(IV) complexes bearing a fully deprotonated water molecule (oxo ligand). We have studied four different cases, which reflect different possible coordination spheres capable of stabilizing such species. In the first chapter, we will give a brief overview of the present energetic challenges faced by western societies. In the second chapter, we will present general considerations about manganese chemistry and a description of the structure and functioning of the water oxidizing enzyme. We will also describe the basic requirements for the splitting of water and present the goals of our work. In the third chapter, we will present the synthesis of a new family of tetradentate ligands, together with the synthesis and full characterization of the corresponding nickel(II) complexes. The first results obtained with the manganese analogue will also be shown. Chapter four presents the formation and the full characterization of a mononuclear manganese(IV)-oxo complex, by electrochemical oxidation of a manganese(II)-aqua complex. We will present different pathways to generate this species and show which intermediates are involved in this 2 e - , 2 H + reaction. Chapter five describes the formation of a mononuclear manganese(IV) complex, by electrochemical oxidation of a manganese(III)-hydroxo complex. The

  5. (e,3e) and (e,3-1e) differential cross sections for the double ionization of water molecule

    International Nuclear Information System (INIS)

    Mansouri, A.; Dal Cappello, C.; Kada, I.; Champion, C.; Roy, A.C.

    2009-01-01

    We report new results for differential cross sections for the double ionization of water molecule by 1 keV electron impact. The present calculation is based on the first Born approximation. We describe the water molecule by a single centre wave function of Moccia. For the final state, an approximation of the well-known 3C wave function is used. An extensive study has been made by varying the angles of detection and the energies of each ejected electron. We have investigated the double ionization of each molecular state (1b 1 , 3a 1 , 1b 2 and 2a 1 ) and identified the mechanisms of this process.

  6. Energy-switching potential energy surface for the water molecule revisited: A highly accurate singled-sheeted form.

    Science.gov (United States)

    Galvão, B R L; Rodrigues, S P J; Varandas, A J C

    2008-07-28

    A global ab initio potential energy surface is proposed for the water molecule by energy-switching/merging a highly accurate isotope-dependent local potential function reported by Polyansky et al. [Science 299, 539 (2003)] with a global form of the many-body expansion type suitably adapted to account explicitly for the dynamical correlation and parametrized from extensive accurate multireference configuration interaction energies extrapolated to the complete basis set limit. The new function mimics also the complicated Sigma/Pi crossing that arises at linear geometries of the water molecule.

  7. A comparison of surface water natural organic matter in raw filtered water samples, XAD, and reverse osmosis isolates

    Science.gov (United States)

    Maurice, P.A.; Pullin, M.J.; Cabaniss, S.E.; Zhou, Q.; Namjesnik-Dejanovic, K.; Aiken, G.R.

    2002-01-01

    This research compared raw filtered waters (RFWs), XAD resin isolates (XAD-8 and XAD-4), and reverse osmosis (RO) isolates of several surface water samples from McDonalds Branch, a small freshwater fen in the New Jersey Pine Barrens (USA). RO and XAD-8 are two of the most common techniques used to isolate natural organic matter (NOM) for studies of composition and reactivity; therefore, it is important to understand how the isolates differ from bulk (unisolated) samples and from one another. Although, any comparison between the isolation methods needs to consider that XAD-8 is specifically designed to isolate the humic fraction, whereas RO concentrates a broad range of organic matter and is not specific to humics. The comparison included for all samples: weight average molecular weight (Mw), number average molecular weight (Mn), polydispersity (??), absorbance at 280nm normalized to moles C (??280) (RFW and isolates); and for isolates only: elemental analysis, % carbon distribution by 13C NMR, and aqueous FTIR spectra. As expected, RO isolation gave higher yield of NOM than XAD-8, but also higher ash content, especially Si and S. Mw decreased in the order: RO>XAD-8>RFW>XAD-4. The Mw differences of isolates compared with RFW may be due to selective isolation (fractionation), or possibly in the case of RO to condensation or coagulation during isolation. 13C NMR results were roughly similar for the two methods, but the XAD-8 isolate was slightly higher in 'aromatic' C and the RO isolate was slightly higher in heteroaliphatic and carbonyl C. Infrared spectra indicated a higher carboxyl content for the XAD-8 isolates and a higher ester:carboxyl ratio for the RO isolates. The spectroscopic data thus are consistent with selective isolation of more hydrophobic compounds by XAD-8, and also with potential ester hydrolysis during that process, although further study is needed to determine whether ester hydrolysis does indeed occur. Researchers choosing between XAD and RO

  8. Tapping mode AFM study on the surface dynamics of a single glucose oxidase molecule on a Au(1 1 1) surface in water with implication for a surface-induced unfolding pathway

    International Nuclear Information System (INIS)

    Otsuka, Ichiro; Yaoita, Masashi; Higano, Michi; Nagashima, Seiiichi; Kataoka, Ryoichi

    2004-01-01

    We have investigated a surface-induced unfolding dynamics of a single glucose oxidase (GO) molecule on Au(1 1 1) in air-saturated water, using tapping mode atomic force microscopy (TMAFM). We followed the unfolding process by measuring the maximum height of a well-isolated GO molecule on a terrace near a step-edge of the surface as a function of contact time. We find three linear portions with two intersections in a power-law fit to the selected values of the observed heights. The kinetic TMAFM result implies that there exist at least two distinct dynamic regimes in the unfolding

  9. Cavity mutants of Savinase. Crystal structures and differential scanning calorimetry experiments give hints of the function of the buried water molecules in subtilisins.

    Science.gov (United States)

    Pedersen, J T; Olsen, O H; Betzel, C; Eschenburg, S; Branner, S; Hastrup, S

    1994-09-23

    The subtilisin molecule possesses several internal water molecules, which may be characterised as an integral part of the protein structure. We have introduced specific mutations (T71I, T71S, T71V, T71A and T71G) at position 71 in the subtilisin variant Savinase from Bacillus lentus. This position is involved in a hydrogen bonded network with several internal water molecules, forming a water channel. The water channel and most of the other internal water molecules are positioned in the interface between two half-domains of the subtilisin molecule. The data presented here indicate that the internal water molecules are structural, and may be the result of trapping during the folding process.

  10. Anomalous diffusion of water molecules at grain boundaries in ice Ih.

    Science.gov (United States)

    Moreira, Pedro Augusto Franco Pinheiro; Veiga, Roberto Gomes de Aguiar; Ribeiro, Ingrid de Almeida; Freitas, Rodrigo; Helfferich, Julian; de Koning, Maurice

    2018-05-23

    Using ab initio and classical molecular dynamics simulations, we study pre-melting phenomena in pristine coincident-site-lattice grain boundaries (GBs) in proton-disordered hexagonal ice Ih at temperatures just below the melting point Tm. Concerning pre-melt-layer thicknesses, the results are consistent with the available experimental estimates for low-disorder impurity-free GBs. With regard to molecular mobility, the simulations provide a key new insight: the translational motion of the water molecules is found to be subdiffusive for time scales from ∼10 ns up to at least 0.1 μs. Moreover, the fact that the anomalous diffusion occurs even at temperatures just below Tm where the bulk supercooled liquid still diffuses normally suggests that it is related to the confinement of the GB pre-melt layers by the surrounding crystalline environment. Furthermore, we show that this behavior can be characterized by continuous-time random walk models in which the waiting-time distributions decay according to power-laws that are very similar to those describing dynamics in glass-forming systems.

  11. Intercalated Water and Organic Molecules for Electrode Materials of Rechargeable Batteries.

    Science.gov (United States)

    Lee, Hyeon Jeong; Shin, Jaeho; Choi, Jang Wook

    2018-03-24

    The intrinsic limitations of lithium-ion batteries (LIBs) with regard to safety, cost, and the availability of raw materials have promoted research on so-called "post-LIBs". The recent intense research of post-LIBs provides an invaluable lesson that existing electrode materials used in LIBs may not perform as well in post-LIBs, calling for new material designs compliant with emerging batteries based on new chemistries. One promising approach in this direction is the development of materials with intercalated water or organic molecules, as these materials demonstrate superior electrochemical performance in emerging battery systems. The enlarged ionic channel dimensions and effective shielding of the electrostatic interaction between carrier ions and the lattice host are the origins of the observed electrochemical performance. Moreover, these intercalants serve as interlayer pillars to sustain the framework for prolonged cycles. Representative examples of such intercalated materials applied to batteries based on Li + , Na + , Mg 2+ , and Zn 2+ ions and supercapacitors are considered, along with their impact in materials research. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. NO Exchange for a Water Molecule Favorably Changes Iontophoretic Release of Ruthenium Complexes to the Skin

    Directory of Open Access Journals (Sweden)

    Danielle C. A. S. de Santana

    2017-01-01

    Full Text Available Ruthenium (Ru complexes have been studied as promising anticancer agents. Ru nitrosyl complex (Ru-NO is one which acts as a pro-drug for the release of nitric oxide (NO. The Ru-aqueous complex formed by the exchange of NO for a water molecule after NO release could also possess therapeutic effects. This study evaluates the influence of iontophoresis on enhancing the skin penetration of Ru-NO and Ru-aqueous and assesses its applicability as a tool in treating diverse skin diseases. Passive and iontophoretic (0.5 mA·cm−2 skin permeation of the complexes were performed for 4 h. The amount of Ru and NO in the stratum corneum (SC, viable epidermis (VE, and receptor solution was quantified while the influence of iontophoresis and irradiation on NO release from Ru-NO complex was also evaluated. Iontophoresis increased the amount of Ru-NO and Ru-aqueous recovered from the receptor solution by 15 and 400 times, respectively, as compared to passive permeation. Iontophoresis produced a higher accumulation of Ru-aqueous in the skin layers as compared to Ru-NO. At least 50% of Ru-NO penetrated the SC was stable after 4 h. The presence of Ru-NO in this skin layer suggests that further controlled release of NO can be achieved by photo-stimulation after iontophoresis.

  13. Association of metal tolerance with multiple antibiotic resistance of bacteria isolated from drinking water.

    Science.gov (United States)

    Calomiris, J J; Armstrong, J L; Seidler, R J

    1984-06-01

    Bacterial isolates from the drinking water system of an Oregon coastal community were examined to assess the association of metal tolerance with multiple antibiotic resistance. Positive correlations between tolerance to high levels of Cu2+, Pb2+, and Zn2+ and multiple antibiotic resistance were noted among bacteria from distribution waters but not among bacteria from raw waters. Tolerances to higher levels of Al3+ and Sn2+ were demonstrated more often by raw water isolates which were not typically multiple antibiotic resistant. A similar incidence of tolerance to Cd2+ was demonstrated by isolates of both water types and was not associated with multiple antibiotic resistance. These results suggest that simultaneous selection phenomena occurred in distribution water for bacteria which exhibited unique patterns of tolerance to Cu2+, Pb2+, and Zn2+ and antibiotic resistance.

  14. GC-MS Quantitation and Identification of Bisphenol-A Isolated from Water

    Science.gov (United States)

    Mead, Ralph N.; Seaton, Pamela J.

    2011-01-01

    Isolation and identification of organic compounds is a necessary skill chemistry students must be able to do with proficiency. In this upper-level undergraduate laboratory, students isolate bisphenol-A (BPA; 4-4'-isopropylidenediphenol) from water using solid-phase extraction (SPE) followed by derivatization with analysis by GC-MS. The students…

  15. Observations on biofilm bacteria isolated from aluminium panels immersed in estuarine waters

    Digital Repository Service at National Institute of Oceanography (India)

    Sonak, S.; Bhosle, N.B.

    Microfouling biomass generally increased on aluminium panels immersed in the surface waters of a tropical estuary over a period of 30 d. A hundred bacterial colonies were randomly isolated, purified and morphologically, physiologically...

  16. Isolation, identification, characterization and antibiotic sensitivity profile of pathogenic Legionella pneumophila isolates from different water sources

    Directory of Open Access Journals (Sweden)

    Kannan Subbaram

    2017-05-01

    Conclusions: Serious and fatal L. pneumophila infections may be transmitted through water. Legionella can survive under various conditions in various water sources. L. pneumophila is the important pathogen causing human disease. Great challenge prevails to health care professionals because these Legionellae acquired antibiotic resistance to many routinely prescribed antibiotics.

  17. Isolation of H13N2 influenza A virus from turkeys and surface water.

    Science.gov (United States)

    Sivanandan, V; Halvorson, D A; Laudert, E; Senne, D A; Kumar, M C

    1991-01-01

    This is the first report of the isolation of H13N2 avian influenza virus (AIV) subtype from domestic turkeys. This subtype was also isolated from nearby surface water. The observation of large numbers of gulls in close association with turkeys on range before the virus isolations suggests that this virus subtype was transmitted from gulls to range turkeys. Turkey flocks infected by this virus subtype did not show any clinical signs of the disease, although seroconversion did occur. The H13N2 isolates were found to be non-pathogenic in chickens.

  18. Studing electronic structure of water molecules in aquocomplexes by the method of pions minus capture by hydrogen

    International Nuclear Information System (INIS)

    Dezhi, I.; Krumshtejn, Z.V.; Molnar, B.; Petrukhin, V.I.; Rybakov, V.N.; Suvorov, V.M.; Khorvat, D.; Tsisek, Z.; Yutlandov, I.A.

    1980-01-01

    Using the effect of electron shell state on π-meson capture by chemically bound hydrogen studied has been change of electron density in hydrogen atoms of water molecules bound into aquocomplexes. The fact of depression of π-meson capture probability by hydrogen of water in aquocomplexes has been established. The magnitudes of depression indicate essential decrease of electron density in a hydrogen atom of coordinated water. Interaction of ligands with oxygen-containing anions also essentially contributes to a magnitude of depression

  19. The Identification of Complex Organic Molecules in the Interstellar Medium: Using Lasers and Matrix Isolation Spectroscopy to Simulate the Interstellar Environment

    Science.gov (United States)

    Stone, Bradley M.

    1998-01-01

    The Astrochemistry Group at NASA Ames Research Center is interested in the identification of large organic molecules in the interstellar medium Many smaller organic species (e.g. hydrocarbons, alcohols, etc.) have been previously identified by their radiofrequency signature due to molecular rotations. However, this becomes increasingly difficult to observe as the size of the molecule increases. Our group in interested in the identification of the carriers of the Diffuse Interstellar Bands (absorption features observed throughout the visible and near-infrared in the spectra of stars, due to species in the interstellar medium). Polycyclic Aromatic Hydrocarbons (PAHs) and related molecules are thought to be good candidates for these carriers. Laboratory experiments am performed at Ames to simulate the interstellar environment, and to compare spectra obtained from molecules in the laboratory to those derived astronomically. We are also interested in PAHs with respect to their possible connection to the UIR (Unidentified infrared) and ERE (Extended Red Emission) bands - emission features found to emanate from particular regions of our galaxy (e.g. Orion nebula, Red Rectangle, etc.). An old, "tried and proven spectroscopic technique, matrix isolation spectroscopy creates molecular conditions ideal for performing laboratory astrophysics.

  20. Stroke Status Evoked Adhesion Molecule Genetic Alterations in Astrocytes Isolated from Stroke-Prone Spontaneously Hypertensive Rats and the Apigenin Inhibition of Their Expression

    Directory of Open Access Journals (Sweden)

    Kazuo Yamagata

    2010-01-01

    Full Text Available We examined the possibility that the expression of adhesion molecules is regulated differently in cultured astrocytes from stroke-prone spontaneously hypertensive rats (SHRSP/IZM rats than in those from Wistar Kyoto rats (WKY/IZM by tumor necrosis factor-alpha (TNF- or hypoxia and reoxygenation (H/R and the inhibitory effects of apigenin. It was found that the expression of vascular cell adhesion molecule-1 (VCAM-1 by TNF- in astrocytes isolated from SHRSP/IZM was increased compared with that in WKY/IZM. The expression of monocyte chemotactic protein-1 (MCP-1 mRNA induced by H/R in SHRSP/IZM astrocytes was increased compared with that in normal oxygen concentrations. Apigenin strongly attenuated TNF--induced VCAM-1 mRNA and protein expression and suppressed the adhesion of U937 cells and SHRSP/IZM astrocytes. These results suggest that the expression levels of adhesion molecules during H/R affect disease outcome and can drive SHRSP/IZM to stroke. It is suggested that apigenin regulates adhesion molecule expression in reactive astrocytes during ischemia.

  1. Isolation of plutonium physical--chemical states from natural waters

    International Nuclear Information System (INIS)

    Weimer, W.C.

    1978-08-01

    The purpose of this research program was to evaluate the feasibility, on a bench scale, of methods for preconcentrating selectively individual plutonium forms from very dilute natural water samples, and to apply these results to use with the Battelle large volume water sampler. From the results of the current investigations, several alternative water sampling strategies have been recommended. The preferred water sampling technique has been field tested at several groundwater wells in the 200 East and 200 West areas of the U.S. Department of Energy Hanford Reservation. These laboratory investigations, in combination with field testing of the proposed water sampling techniques, have yielded the following conclusions: (1) The use of polypropylene microporous filters (0.04μ pore size) in conjunction with glass fiber filters (3.0μ pore size) enables the characterization of two size fractions of particulate plutonium forms in groundwater samples. Those species which pass the microporous polypropylene filters are considered to be in solution. (2) The sorption and ion exchange media evaluated do not show the selectivity necessary to allow preconcentration of individual plutonium forms from natural water samples by any of these media beds under the conditions evaluated. (3) Al 2 O 3 is the most effective sorption media that was examined for removing any plutonium species from natural water samples at neutral pH values. On the basis of these investigations, a standard field testing methodology has been proposed for sampling ground waters near nuclear waste management areas. Additional laboratory evaluations of plutonium species interactions with sorption and ion exchange media have also been recommended

  2. Effect of water molecule distribution on the quantitative XRD analysis in the case of Na-montmorillonite exchanged Cu2+

    International Nuclear Information System (INIS)

    Oueslati, W.; Meftah, M.; Ben Rhaiem, H.; Ben Haj Amara, A.

    2010-01-01

    Document available in extended abstract form only. Several theoretical models are proposed to describe hydration process for Wyoming-montmorillonite clay exchanged Na + or Cu 2+ . They propose some theoretical distribution and disposition for water molecule in the inter-lamellar space in the case of homogeneous and inter-stratified hydration states. For example, Ben Brahim et al. (1983a) studied the interlayer structure (atomic positions of interlayer cations) and associated H 2 O molecules of Na-saturated montmorillonite and beidellite samples. Moore and Hower (1986) studied ordered structures composed of mono-hydrated and collapsed interlayers in montmorillonite, and Cuadros (1996) estimated the H 2 O content of smectite as a function of the interlayer cation. Using similar approach, Ferrage et al (2005b) proposed a discreet distribution of water molecule layer in the same z coordinate of the exchangeable cation with inhomogeneous distribution. This heterogeneity was attributed to the surface charge. The main objective of this study is to characterize the structural changes in the theoretical XRD profile, induced by different water molecule distribution, used to simulate experimental XRD patterns in the case of Na-montmorillonite exchanged Cu 2+ . This problem was achieved by quantitative XRD analysis using an indirect method based on the comparison of the experimental 001 reflections obtained from oriented films patterns with those calculated from structural models. The starting materials were Ca-montmorillonite originated from bentonites of Wyoming (USA). The XRD patterns were obtained by reflection setting with a D8 ADVANCE Bruker installation using Cu-Kα radiation and equipped with solid state detector. Intensities were measured at an interval of 2Θ 0.04 deg. and 40-50 s counting time per step. The diffracted intensity was calculated according to the matrix formalism detailed by Drits and Tchoubar, (1990). The fitting strategies was detailed by Ferrage et

  3. Direct numerical solution of the Ornstein-Zernike integral equation and spatial distribution of water around hydrophobic molecules

    Science.gov (United States)

    Ikeguchi, Mitsunori; Doi, Junta

    1995-09-01

    The Ornstein-Zernike integral equation (OZ equation) has been used to evaluate the distribution function of solvents around solutes, but its numerical solution is difficult for molecules with a complicated shape. This paper proposes a numerical method to directly solve the OZ equation by introducing the 3D lattice. The method employs no approximation the reference interaction site model (RISM) equation employed. The method enables one to obtain the spatial distribution of spherical solvents around solutes with an arbitrary shape. Numerical accuracy is sufficient when the grid-spacing is less than 0.5 Å for solvent water. The spatial water distribution around a propane molecule is demonstrated as an example of a nonspherical hydrophobic molecule using iso-value surfaces. The water model proposed by Pratt and Chandler is used. The distribution agrees with the molecular dynamics simulation. The distribution increases offshore molecular concavities. The spatial distribution of water around 5α-cholest-2-ene (C27H46) is visualized using computer graphics techniques and a similar trend is observed.

  4. Diversity and antibiotic resistance patterns of Sphingomonadaceae isolates from drinking water.

    Science.gov (United States)

    Vaz-Moreira, Ivone; Nunes, Olga C; Manaia, Célia M

    2011-08-15

    Sphingomonadaceae (n = 86) were isolated from a drinking water treatment plant (n = 6), tap water (n = 55), cup fillers for dental chairs (n = 21), and a water demineralization filter (n = 4). The bacterial isolates were identified based on analysis of the 16S rRNA gene sequence, and intraspecies variation was assessed on the basis of atpD gene sequence analysis. The isolates were identified as members of the genera Sphingomonas (n = 27), Sphingobium (n = 28), Novosphingobium (n = 12), Sphingopyxis (n = 7), and Blastomonas (n = 12). The patterns of susceptibility to five classes of antibiotics were analyzed and compared for the different sites of isolation and taxonomic groups. Colistin resistance was observed to be intrinsic (92%). The highest antibiotic resistance prevalence values were observed in members of the genera Sphingomonas and Sphingobium and for beta-lactams, ciprofloxacin, and cotrimoxazole. In tap water and in water from dental chairs, antibiotic resistance was more prevalent than in the other samples, mainly due to the predominance of isolates of the genera Sphingomonas and Sphingobium. These two genera presented distinct patterns of association with antibiotic resistance, suggesting different paths of resistance development. Antibiotic resistance patterns were often related to the species rather than to the site or strain, suggesting the importance of vertical resistance transmission in these bacteria. This is the first study demonstrating that members of the family Sphingomonadaceae are potential reservoirs of antibiotic resistance in drinking water.

  5. Bioremediation prospects of fungi isolated from water soluble ...

    African Journals Online (AJOL)

    The fungi associated with water soluble fraction (WSF) of crude oil from two different locations were investigated. The samples were collected from Ezibin oil well (Sample A), Okwagbe village in Ughelli South Local Government Area of Delta State and from NPDC laboratory (Sample B) in Benin City, Oredo Local ...

  6. Comparative Analysis of Leptospira Strains Isolated from Environmental Soil and Water in the Philippines and Japan

    Science.gov (United States)

    Villanueva, Sharon Y. A. M.; Chakraborty, Antara; Miyahara, Satoshi; Segawa, Takaya; Asoh, Tatsuma; Ozuru, Ryo; Gloriani, Nina G.; Yanagihara, Yasutake; Yoshida, Shin-ichi

    2013-01-01

    There have been few reports on the epidemiological analysis of environmental Leptospira isolates. This is probably because the isolation of leptospires from the environment was usually unsuccessful due to the overgrowth of contaminants and the slow growth of Leptospira. In this study, we collected a total of 88 samples of soil and water from three sites: Metro Manila and Nueva Ecija, Philippines (an area where Leptospira is now endemic), and Fukuoka, Japan (an area where Leptospira was once endemic). We succeeded in isolating Leptospira from 37 samples by using the novel combination of five antimicrobial agents reported in 2011. The frequencies of positive isolation of Leptospira in the Philippines and Japan were 40 and 46%, respectively. For Leptospira-positive samples, five colonies from each sample were isolated and analyzed by pulsed-field gel electrophoresis (PFGE). The isolates from each area showed their respective characteristics in phylogenetic trees based on the PFGE patterns. Some isolates were closely related to each other across borders. Based on 16S rRNA gene-based phylogenetic analysis, four isolates in Fukuoka were identified as a pathogenic species, L. alstonii; however, its virulence had been lost. One isolate from Nueva Ecija was identified as the intermediate pathogenic species Leptospira licerasiae. Most of the isolates from the environment belonged to nonpathogenic Leptospira species. We also investigated the strain variation among the isolates in a puddle over 5 months. We demonstrated, using PFGE analysis, that Leptospira survived in the wet soil on dry days and appeared in the surface water on rainy days. These results showed that the soil could be a reservoir of leptospires in the environment. PMID:23144130

  7. Isolation and characterization of humics from natural waters

    International Nuclear Information System (INIS)

    Allard, B.; Arsenie, I.; Boren, H.; Ephraim, J.; Pettersson, C.; Gaardhammar, G.

    1990-05-01

    A method has been developed for quantitative recovery of humic substances from aqueous systems based on ion exchange on DEAE-cellulose. A scheme is suggested for the characterization of dissolved humic substances (UV-, IR- and 1 H NMR-spectroscopy, elemental analysis, molecular weight determination, 14 C-age, functionality, carbohydrate content and acid-base properties) as a routine in the chemical analysis of natural waters. (orig.)

  8. Removal of decay heat by specially designed isolation condensers for advanced heavy water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Dhawan, M L; Bhatia, S K [Reactor Engineering Division, Bhabha Atomic Research Centre, Mumbai (India)

    1994-06-01

    For Advanced Heavy Water Reactor (AHWR), removal of decay heat and containment heat is being considered by passive means. For this, special type of isolation condensers are designed. Isolation condensers when submerged in a pool of water, are the best choice because condensation of high temperature steam is an extremely efficient heat transfer mechanism. By the use of isolation condensers, not only heat is removed but also pressure and temperature of the system are automatically controlled without losing the coolant and without using conventional safety relief valves. In this paper, design optimisation studies of isolation condensers of different types with natural circulation for the removal of core decay heat for AHWR is presented. (author). 8 refs., 2 figs.

  9. Isolation and characterization of new facultative alkaliphilic Bacillus flexus strains from maize processing waste water (nejayote).

    Science.gov (United States)

    Sanchez-Gonzalez, M; Blanco-Gamez, A; Escalante, A; Valladares, A G; Olvera, C; Parra, R

    2011-04-01

    This work describes the isolation and characterization of two new alkaliphilic micro-organisms present in nejayote. Samples of fresh industrial nejayote were plated on nejayote medium and incubated for 4 days at 37 °C. Isolates were identified based on morphological and physiological characteristics, as well as 16S rDNA sequence analysis. Two gram-positive strains, NJY2 and NJY4, able to hydrolyse starch, xylan, and gelatin were isolated from nejayote. Comparative sequence analysis of 16S rDNA and phylogenetic studies indicate that the micro-organisms studied were closely related to members of the Bacillus flexus species. The strains were identified as facultative alkaliphilic salt tolerant bacteria. Isolate NJY2 produced cell associated phenolic acid esterases, able to release ferulic acid from nixtamalised corn bran and ethyl and methyl esters. The isolated strains of B. flexus NJY2 and NJY4 showed important physiological properties to produce high-value molecules from agroindustrial by-products. This is the first report about the isolation of alkaliphilic micro-organisms from nejayote and the first report of phenolic acid esterases synthesised by alkaliphiles. The new alkaliphilic micro-organisms have potential application in the treatment and transformation of tortilla industry residues. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

  10. Short communication: Conservation of Streptococcus uberis adhesion molecule and the sua gene in strains of Streptococcus uberis isolated from geographically diverse areas.

    Science.gov (United States)

    Yuan, Ying; Dego, Oudessa Kerro; Chen, Xueyan; Abadin, Eurife; Chan, Shangfeng; Jory, Lauren; Kovacevic, Steven; Almeida, Raul A; Oliver, Stephen P

    2014-12-01

    The objective was to identify and sequence the sua gene (GenBank no. DQ232760; http://www.ncbi.nlm.nih.gov/genbank/) and detect Streptococcus uberis adhesion molecule (SUAM) expression by Western blot using serum from naturally S. uberis-infected cows in strains of S. uberis isolated in milk from cows with mastitis from geographically diverse areas of the world. All strains evaluated yielded a 4.4-kb sua-containing PCR fragment that was subsequently sequenced. Deduced SUAM AA sequences from those S. uberis strains evaluated shared >97% identity. The pepSUAM sequence located at the N terminus of SUAM was >99% identical among strains of S. uberis. Streptococcus uberis adhesion molecule expression was detected in all strains of S. uberis tested. These results suggest that sua is ubiquitous among strains of S. uberis isolated from diverse geographic locations and that SUAM is immunogenic. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  11. Effect of heavy water on isolated rat liver mitochondria

    International Nuclear Information System (INIS)

    Huebner, G.

    1981-01-01

    The rate of O 2 consumption by isolated rat liver mitochondria was determined polarographically with a Clark electrode at 25 0 C in the active (state 3), strongly coupled (state 4) and decoupled state of the mitochondria in media containing H 2 16 O, D 2 16 O or H 2 18 O. The results confirm the value of the D 2 O isotope effect in the form on an O 2 -consumption inhibition. In H 2 18 O no isotope effect has been detected in the state of controlled respiration. In contrast, a strongly marked inverse isotope effect has been found in the active state after ADP addition and in the decoupled state after DNP addition. This inverse isotope effect occurs in reactions involving a preceding equilibrium. According to the chemiosmotic hypothesis of oxidative phosphorylation the formation of hydronium ions is part of this reaction. The equilibrium constant k 2 = 0.9774 for the hydronium ion in H 2 16 O and H 2 18 O implies that the formation of the hydronium ion in H 2 18 O is preferred to that in H 2 16 O. The high inverse H 2 18 O isotope effect respiration shows that the formation of H 3 O + contributes to the vectorial proton transport, probably as a preceding equilibrium, and that in the active state of the respiratory chain this reaction may be the rate-determining step. (author)

  12. Leak isolation self-repairing tape for a water storage vessel and piping against holes

    International Nuclear Information System (INIS)

    Nagaya, Kosuke; Sekiguchi, Takahiro; Chen, Zhichao; Murakami, Iwanori

    2007-01-01

    A new type taping for a water storage vessel or piping is presented, in which water leakage is isolated automatically by its self-repairing mechanism against holes. The self-repairing unit (sealant layer) is consisting of three pieces of net with polymer particles inside lattices. Polymer particles, which expand their volume with water, is used for having self-repairing forces. In ordinary tapes, water leaks along the boundary between the tape and the vessel. In order to retain the leak isolation force, this article first discusses a method for making the sealant tape, then develops a method for fixing the sealant to the vessel. The portion of water leakage can be checked on this tape, and the method of detecting the hole or crack portion of the vessel is also presented by using the tape. (author)

  13. Isolated Rupture of the Teres Major Muscle When Water Skiing: A Case Report and Literature Review

    Directory of Open Access Journals (Sweden)

    Julien Cousin

    2018-01-01

    Full Text Available Isolated lesions to the teres major muscle are rare. They generally occur in patients participating in sports such as baseball, tennis, or boxing. We report the case of a sports patient who suffered an isolated injury to the teres major while water skiing. The clinical presentation was confirmed by MRI. Conservative treatment was chosen and consisted of brief analgesic immobilization, followed by rehabilitative treatment. The rapid recovery of this patient with normal isokinetic strength evaluation at 6 months was interesting for objectifying full muscle recovery. Our results and the data from the literature suggest that functional rather than surgical treatment is preferable in isolated lesions to the teres major muscle.

  14. Dimorphic transition in Yarrowia lipolytica isolated from oil-polluted sea water

    International Nuclear Information System (INIS)

    Zinjarde, Smita S.; Pant, Aditi; Deshpande, Mukund V.

    1998-01-01

    Fungal cultures from oil-polluted sea water near Mumbai, India have been studies for their capability to degrade crude oil. A yeast isolate identified as Yarrowia lipolytica was further investigated with respect to its dimorphic behaviour and alkane degradation. Y. lipolytica NCIM 3589 in the yeast form degraded the aliphatic fraction of crude oil and also pure alkanes (20-60% within 48h) under aerobic conditions. Unlike most Y. lipolytica strains, our isolate required partial anaerobiosis for mycelium formation. Studies with two isolates suggested that mycelium to yeast transition may be the prerequisite for effective alkane degradation. (author)

  15. Isolation of Crude Oil from Polluted Waters Using Biosurfactants Pseudomonas Bacteria: Assessment of Bacteria Concentration Effects

    Directory of Open Access Journals (Sweden)

    A. Khalifeh

    2013-04-01

    Full Text Available Biological decomposition techniques and isolation of environmental pollutions using biosurfactants bacteria are effective methods of environmental protection. Surfactants are amphiphilic compounds that are produced by local microorganisms and are able to reduce the surface and the stresses between surfaces. As a result, they will increase solubility, biological activity, and environmental decomposition of organic compounds. This study analyzes the effects of biosurfactants on crude oil recovery and its isolation using pseudomonas sea bacteria species. Preparation of biosurfactants was done in glass flasks and laboratory conditions. Experiments were carried out to obtain the best concentration of biosurfactants for isolating oil from water and destroying oil-in-water or water-in-oil emulsions in two pH ranges and four saline solutions of different concentrations. The most effective results were gained when a concentration of 0.1% biosurfactants was applied.

  16. Testing Wallace's intuition: water type, reproductive isolation and divergence in an Amazonian fish.

    Science.gov (United States)

    Pires, Tiago H S; Borghezan, Elio A; Machado, Valeria N; Powell, Daniel L; Röpke, Cristhiana P; Oliveira, Claudio; Zuanon, Jansen; Farias, Izeni P

    2018-06-01

    Alfred Russel Wallace proposed classifying Amazon rivers based on their colour and clarity: white, black and clear water. Wallace also proposed that black waters could mediate diversification and yield distinct fish species. Here, we bring evidence of speciation mediated by water type in the sailfin tetra (Crenuchus spilurus), a fish whose range encompasses rivers of very distinct hydrochemical conditions. Distribution of the two main lineages concords with Wallace's water types: one restricted to the acidic and nutrient-poor waters of the Negro River (herein Rio Negro lineage) and a second widespread throughout the remaining of the species' distribution (herein Amazonas lineage). These lineages occur over a very broad geographical range, suggesting that despite occurring in regions separated by thousands of kilometres, individuals of the distinct lineages fail to occupy each other's habitats, hundreds of metres apart and not separated by physical barrier. Reproductive isolation was assessed in isolated pairs exposed to black-water conditions. All pairs with at least one individual of the lineage not native to black waters showed significantly lower spawning success, suggesting that the water type affected the fitness and contributed to reproductive isolation. Our results endorse Wallace's intuition and highlight the importance of ecological factors in shaping diversity of the Amazon fish fauna. © 2018 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2018 European Society For Evolutionary Biology.

  17. Time-dependent enhancement of lymphocyte activation by mitogens after exposure to isolation or water scheduling.

    Science.gov (United States)

    Jessop, J J; Gale, K; Bayer, B M

    1988-01-01

    The effects of isolation and water scheduling on mitogen induced lymphocyte proliferation were investigated. Isolated rats were animals which had been raised in group-housed conditions and then transferred to individual cages with ad lib access to water for a 1 or 2 week period. Water scheduled rats were maintained in group housing (5 rats per cage) with ad lib access to food but with access to water for a single 30 minute session each day. Responses of these groups were compared to those of animals which had been continuously group-housed with ad lib access to food and water. No differences in lymphocyte responses to phytohemagglutinin (PHA) were found 1 week after exposure to isolation. However, after 2 weeks, splenic and blood T lymphocytes from isolated animals demonstrated an increased proliferative response to suboptimum and maximum concentrations of PHA. Splenic B lymphocyte responses to lipopolysaccharide (LPS) from isolated animals were also increased by 2- to 3-fold compared to group-housed controls. Two weeks of exposure of animals to daily water scheduling similarly increased the splenic lymphocyte proliferation. This increased responsiveness to PHA was not accompanied by a significant change in the sensitivity of the lymphocytes to PHA, in the total number of white blood cells, or the proportion of splenic T or T helper lymphocytes. Our results show that the increase in lymphocyte proliferation is time-dependent, requires greater than 1 week of exposure to isolation and is due to factors other than changes in sensitivity to mitogen or T lymphocyte number.

  18. A theoretical model investigation of peptide bond formation involving two water molecules in ribosome supports the two-step and eight membered ring mechanism

    International Nuclear Information System (INIS)

    Wang, Qiang; Gao, Jun; Zhang, Dongju; Liu, Chengbu

    2015-01-01

    Highlights: • We theoretical studied peptide bond formation reaction mechanism with two water molecules. • The first water molecule can decrease the reaction barriers by forming hydrogen bonds. • The water molecule mediated three-proton transfer mechanism is the favorable mechanism. • Our calculation supports the two-step and eight membered ring mechanism. - Abstract: The ribosome is the macromolecular machine that catalyzes protein synthesis. The kinetic isotope effect analysis reported by Strobel group supports the two-step mechanism. However, the destination of the proton originating from the nucleophilic amine is uncertain. A computational simulation of different mechanisms including water molecules is carried out using the same reaction model and theoretical level. Formation the tetrahedral intermediate with proton transfer from nucleophilic nitrogen, is the rate-limiting step when two water molecules participate in peptide bond formation. The first water molecule forming hydrogen bonds with O9′ and H15′ in the A site can decrease the reaction barriers. Combined with results of the solvent isotope effects analysis, we conclude that the three-proton transfer mechanism in which water molecule mediate the proton shuttle between amino and carbon oxygen in rate-limiting step is the favorable mechanism. Our results will shield light on a better understand the reaction mechanism of ribosome

  19. Molecular Dynamics Study of Water Molecules in Interlayer of 14 ^|^Aring; Tobermorite

    KAUST Repository

    Yoon, Seyoon; Monteiro, Paulo J.M.

    2013-01-01

    The molecular structure and dynamics of interlayer water of 14 Å tobermorite are investigated based on molecular dynamics (MD) simulations. Calculated structural parameters of the interlayer water configuration are in good agreement with current

  20. Thermodynamic analysis of water molecules at the surface of proteins and applications to binding site prediction and characterization.

    Science.gov (United States)

    Beuming, Thijs; Che, Ye; Abel, Robert; Kim, Byungchan; Shanmugasundaram, Veerabahu; Sherman, Woody

    2012-03-01

    Water plays an essential role in determining the structure and function of all biological systems. Recent methodological advances allow for an accurate and efficient estimation of the thermodynamic properties of water molecules at the surface of proteins. In this work, we characterize these thermodynamic properties and relate them to various structural and functional characteristics of the protein. We find that high-energy hydration sites often exist near protein motifs typically characterized as hydrophilic, such as backbone amide groups. We also find that waters around alpha helices and beta sheets tend to be less stable than waters around loops. Furthermore, we find no significant correlation between the hydration site-free energy and the solvent accessible surface area of the site. In addition, we find that the distribution of high-energy hydration sites on the protein surface can be used to identify the location of binding sites and that binding sites of druggable targets tend to have a greater density of thermodynamically unstable hydration sites. Using this information, we characterize the FKBP12 protein and show good agreement between fragment screening hit rates from NMR spectroscopy and hydration site energetics. Finally, we show that water molecules observed in crystal structures are less stable on average than bulk water as a consequence of the high degree of spatial localization, thereby resulting in a significant loss in entropy. These findings should help to better understand the characteristics of waters at the surface of proteins and are expected to lead to insights that can guide structure-based drug design efforts. Copyright © 2011 Wiley Periodicals, Inc.

  1. Light water reactor pressure isolation valve performance testing

    International Nuclear Information System (INIS)

    Neely, H.H.; Jeanmougin, N.M.; Corugedo, J.J.

    1990-07-01

    The Light Water Reactor Valve Performance Testing Program was initiated by the NRC to evaluate leakage as an indication of valve condition, provide input to Section XI of the ASME Code, evaluate emission monitoring for condition and degradation and in-service inspection techniques. Six typical check and gate valves were purchased for testing at typical plant conditions (550F at 2250 psig) for an assumed number of cycles for a 40-year plant lifetime. Tests revealed that there were variances between the test results and the present statement of the Code; however, the testing was not conclusive. The life cycle tests showed that high tech acoustic emission can be utilized to trend small leaks, that specific motor signature measurement on gate valves can trend and indicate potential failure, and that in-service inspection techniques for check valves was shown to be both feasible and an excellent preventive maintenance indicator. Life cycle testing performed here did not cause large valve leakage typical of some plant operation. Other testing is required to fully understand the implication of these results and the required program to fully implement them. (author)

  2. Serine/threonine phosphatase tapp2cs might be served as an early signal molecule for water stress in wheat

    International Nuclear Information System (INIS)

    Song, K. H.; Tian, W. L.; Hou, B. Z.; Guo, J. X.; Mei, X. R.; Li, Y. Z.

    2015-01-01

    Much progress has been made towards understanding the role of serine/threonine phosphatases type 2C (PP2Cs) in abscisic acid (ABA) signaling transduction. However, how the negative regulator, PP2Cs, responds to plant water loss remains unclear. Here, we used a series of relative soil moisture (RSM: 85 percentage (well watered), 65 percentage (moderate stress), 45 percentage (severe stress) potted winter wheat (Triticum aestivum L.) and the detached leaves to detect ABA levels and transcripts of PP2Cs, including PP2C40, PP2C45, PP2C59 and PP2C6 as well as the core downstream signals of ABA, including ABF, SnRK2.4 and SnRK2.5. The results showed that the continual loss of water led to a consistent increase in ABA levels, and that the mRNA expression levels of PP2Cs were dependent on plant water condition. PP2Cs expression could be induced by a slight loss of water, and inhibited under severe loss of water. These results were further confirmed by the transcripts of ABF, SnRK2.4 and SnRK2.5. Furthermore, in slight loss of water, 100 μM exogenous ABA could promote PP2Cs expression; in severe loss of water, it inhibited PP2Cs expression. In conclusion, ABA accumulation is controlled by water condition and the PP2C expression is dependent on plant water condition, suggesting that PP2Cs might be served as an early signal molecule for water stress in wheat. (author)

  3. Differential and total cross sections for the ionization of water molecule by electron impact

    International Nuclear Information System (INIS)

    Houamer, S.; Dal Cappello, C.; Mansouri, A.

    2007-01-01

    A theoretical approach is presented to calculate multiply differential and total cross sections of the ionization of H 2 O molecule in the vapour phase. The wave function of the target is described by molecular orbitals consisting of a linear combination of slater type atomic orbitals centered on the heaviest atom which is the oxygen atom in this case. The calculations are carried out in the first Born approximation where the projectile is described by a plane wave while the ejected electron is described by a coulomb wave taking into account its interaction with the residual ion. The spherical average over the Euler solid angle due to the randomly oriented gaseous target molecule is carried out analytically using the rotation matrix properties. The differential and total cross sections are thus evaluated without any special difficulty and compared with experiments and distorted wave calculations. Fair agreements are observed

  4. Molecular fingerprinting of Cryptosporidium oocysts isolated during water monitoring.

    Science.gov (United States)

    Nichols, Rosely A B; Campbell, Brian M; Smith, Huw V

    2006-08-01

    We developed and validated a PCR-based method for identifying Cryptosporidium species and/or genotypes present on oocyst-positive microscope slides. The method involves removing coverslips and oocysts from previously examined slides followed by DNA extraction. We tested four loci, the 18S rRNA gene (N18SDIAG and N18SXIAO), the Cryptosporidium oocyst wall protein (COWP) gene (STN-COWP), and the dihydrofolate reductase (dhfr) gene (by multiplex allele-specific PCR), for amplifying DNA from low densities of Cryptosporidium parvum oocysts experimentally seeded onto microscope slides. The N18SDIAG locus performed consistently better than the other three tested. Purified oocysts from humans infected with C. felis, C. hominis, and C. parvum and commercially purchased C. muris were used to determine the sensitivities of three loci (N18SDIAG, STN-COWP, and N18SXIAO) to detect low oocyst densities. The N18SDIAG primers provided the greatest number of positive results, followed by the N18SXIAO primers and then the STN-COWP primers. Some oocyst-positive slides failed to generate a PCR product at any of the loci tested, but the limit of sensitivity is not entirely based on oocyst number. Sixteen of 33 environmental water monitoring Cryptosporidium slides tested (oocyst numbers ranging from 1 to 130) contained mixed Cryptosporidium species. The species/genotypes most commonly found were C. muris or C. andersoni, C. hominis or C. parvum, and C. meleagridis or Cryptosporidium sp. cervine, ferret, and mouse genotypes. Oocysts on one slide contained Cryptosporidium muskrat genotype II DNA.

  5. Expressional Changes of Water Transport-related Molecules in the Efferent Ductules and Initial Segment of Mouse Treated with Bisphenol A-Containing Drinking Water for Two Generations.

    Science.gov (United States)

    Han, Su-Yong; Lee, Ki-Ho

    2013-09-01

    Bisphenol A (BPA) is an estrogenic endocrine disrupter. However, depending on a way of treatment, the harmful effects of BPA have not been confirmed. Also, trans-generational effects of BPA on male reproduction are still controversial. Because the reabsorption of testicular fluid in the efferent ductules (ED) and initial segment (IS) is important for sperm maturation, the present study was designed to determine trans-generational effect of BPA administrated orally on expression of water transport-related molecules in the mouse ED and IS. Ethanol-dissolved BPA was diluted in water to be 100 ng (low), 10 μg (medium), and 1 mg/Ml water (high). BPA-containing water was provided for two generations. Expression of ion transporters and water channels in the ED and IS were measured by relative real-time PCR analysis. In the ED, BPA treatment caused expressional increases of carbonic anhydrase II, cystic fibrosis transmembrane regulator, Na(+)/K(+) ATPase α1 subunit, and aquaporin (AQP) 1. No change of Na(+)/H(+) exchange (NHE) 3 expression was detected. BPA treatment at medium dose resulted in an increase of AQP9 expression. In the IS, the highest expressional levels of all molecules tested were observed in medium-dose BPA treatment. Generally, high-dose BPA treatment resulted in a decrease or no change of gene expression. Fluctuation of NHE3 gene expression by BPA treatment at different concentrations was detected. These findings suggest that trans-generational exposure to BPA, even at low dose, could affect gene expression of water-transport related molecules. However, such effects of BPA would be differentially occurred in the ED and IS.

  6. Molecular motion of water molecules in lyotropic mesophases formed from fatty acid soaps

    International Nuclear Information System (INIS)

    Olszewski, K.J.; Pislewski, N.

    1980-01-01

    The results of study of self-diffusion coefficients and relaxation times for the mesophases formed from water mixtures of potassium laurate (denoted by C 12 K), myristate (C 14 K), and palmitate (C 16 K), are presented. The samples containing by weight 70% of soaps and 30% of water as well as samples containing 30% of soaps and 70% of water were examined. It allowed to obtain lamellar and middle phase respectively. (author)

  7. Genetic diversity of Escherichia coli isolates from surface water and groundwater in a rural environment.

    Science.gov (United States)

    Gambero, Maria Laura; Blarasin, Monica; Bettera, Susana; Giuliano Albo, Jesica

    2017-10-01

    The genetic characteristics among Escherichia coli strains can be grouped by origin of isolation. Then, it is possible to use the genotypes as a tool to determine the source of water contamination. The aim of this study was to define water aptitude for human consumption in a rural basin and to assess the diversity of E. coli water populations. Thus, it was possible to identify the main sources of fecal contamination and to explore linkages with the hydrogeological environment and land uses. The bacteriological analysis showed that more than 50% of samples were unfit for human consumption. DNA fingerprinting analysis by BOX-PCR indicated low genotypic diversity of E. coli isolates taken from surface water and groundwater. The results suggested the presence of a dominant source of fecal contamination. The relationship between low genotypic diversity and land use would prove that water contamination comes from livestock. The genetic diversity of E. coli isolated from surface water was less than that identified in groundwater because of the different hydraulic features of both environments. Furthermore, each one of the two big strain groups identified in this basin is located in different sub-basins, showing that hydrological dynamics exerts selective pressure on bacteria DNA.

  8. Rhodotorula portillonensis sp. nov., a basidiomycetous yeast isolated from Antarctic shallow-water marine sediment.

    Science.gov (United States)

    Laich, Federico; Vaca, Inmaculada; Chávez, Renato

    2013-10-01

    During the characterization of the mycobiota associated with shallow-water marine environments from Antarctic sea, a novel pink yeast species was isolated. Sequence analysis of the D1/D2 domain of the LSU rDNA gene and 5.8S-ITS regions revealed that the isolated yeast was closely related to Rhodotorula pallida CBS 320(T) and Rhodotorula benthica CBS 9124(T). On the basis of morphological, biochemical and physiological characterization and phylogenetic analyses, a novel basidiomycetous yeast species, Rhodotorula portillonensis sp. nov., is proposed. The type strain is Pi2(T) ( = CBS 12733(T)  = CECT 13081(T)) which was isolated from shallow-water marine sediment in Fildes Bay, King George Island, Antarctica.

  9. CRISPR Diversity in E. coli Isolates from Australian Animals, Humans and Environmental Waters.

    Directory of Open Access Journals (Sweden)

    Maxim S Sheludchenko

    Full Text Available Seventy four SNP genotypes and 54 E. coli genomes from kangaroo, Tasmanian devil, reptile, cattle, dog, horse, duck, bird, fish, rodent, human and environmental water sources were screened for the presence of the CRISPR 2.1 loci flanked by cas2 and iap genes. CRISPR 2.1 regions were found in 49% of the strains analysed. The majority of human E. coli isolates lacked the CRISPR 2.1 locus. We described 76 CRISPR 2.1 positive isolates originating from Australian animals and humans, which contained a total of 764 spacer sequences. CRISPR arrays demonstrated a long history of phage attacks especially in isolates from birds (up to 40 spacers. The most prevalent spacer (1.6% was an ancient spacer found mainly in human, horse, duck, rodent, reptile and environmental water sources. The sequence of this spacer matched the intestinal P7 phage and the pO111 plasmid of E. coli.

  10. Brevibacterium siliguriense sp nov., a facultatively oligotrophic bacterium isolated from river water

    NARCIS (Netherlands)

    Kumar, A.; Ince, I.A.; Kati, A.; Chakraborty, R.

    2013-01-01

    A Gram-positive-staining, rod-shaped, facultatively oligotrophic bacterial strain, designated MB18(T), was isolated from a water sample collected from the River Mahananda at Siliguri (26 degrees 44' 23.20' N, 88 degrees 25' 22.89' a West-Bengal, India. On the basis of 16S rRNA gene sequence

  11. Imtechella halotolerans gen. nov., sp. nov., a member of the family Flavobacteriaceae isolated from estuarine water

    Digital Repository Service at National Institute of Oceanography (India)

    Surendra, V.; Bhawana, P.; Suresh, K.; Srinivas, T.N.R.; AnilKumar, P.

    A novel Gram-negative, rod-shaped, non-motile, non-sporulating bacterium, designated strain K1 sup(T), was isolated from an estuarine water sample collected from Kochi, Kerala, India. Colonies on marine agar were circular, 2.0-2.5 mm in diameter...

  12. Marinobacter nitratireducens sp. nov., a halophilic and lipolytic bacterium isolated from coastal surface sea water

    Digital Repository Service at National Institute of Oceanography (India)

    Bhumika, V.; Ravinder, K.; Korpole, S.; Srinivas, T.N.R.; AnilKumar, P.

    A novel Gram-stain-negative, rod-shaped, motile bacterium, designated strain AK21T , was isolated from coastal surface sea water at Visakhapatnam, India. The strain was positive for oxidase, catalase, lipase, L-proline arylamidase...

  13. Vitellibacter nionensis sp. nov., isolated from shallow water hydrothermal vent of Espalamaca, Azores.

    Digital Repository Service at National Institute of Oceanography (India)

    Rajasabapathy, R.; Mohandass, C; Yoon, J; Dastager, S.G.; Liu, Q.; Khieu, T.-N.; Son, C; Li, W.-J; Colaco, A.

    A novel, Gram-negative, non-motile, rod-shaped yellow pigmented bacterium, designated VBW088T was isolated from shallow water hydrothermal vent of Espalamaca, Azores. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain VBW088...

  14. Isolation of a sulfide-producing bacterial consortium from cooling-tower water

    NARCIS (Netherlands)

    Ilhan-Sungur, Esra; Ozuolmez, Derya; Çotuk, Ayşın; Cansever, Nurhan; Muyzer, Gerard

    2017-01-01

    Sulfidogenic Clostridia and sulfate reducing bacteria (SRB) often cohabit in nature. The presence of these microorganisms can cause microbially influenced corrosion (MIC) of materials in different ways. To investigate this aspect, bacteria were isolated from cooling tower water and used in

  15. Low-temperature FTIR spectroscopy provides evidence for protein-bound water molecules in eubacterial light-driven ion pumps.

    Science.gov (United States)

    Nomura, Yurika; Ito, Shota; Teranishi, Miwako; Ono, Hikaru; Inoue, Keiichi; Kandori, Hideki

    2018-01-31

    Light-driven H + , Na + and Cl - pumps have been found in eubacteria, which convert light energy into a transmembrane electrochemical potential. A recent mutation study revealed asymmetric functional conversion between the two pumps, where successful functional conversions are achieved exclusively when mutagenesis reverses the evolutionary amino acid sequence changes. Although this fact suggests that the essential structural mechanism of an ancestral function is retained even after gaining a new function, questions regarding the essential structural mechanism remain unanswered. Light-induced difference FTIR spectroscopy was used to monitor the presence of strongly hydrogen-bonded water molecules for all eubacterial H + , Na + and Cl - pumps, including a functionally converted mutant. This fact suggests that the strongly hydrogen-bonded water molecules are maintained for these new functions during evolution, which could be the reason for successful functional conversion from Na + to H + , and from Cl - to H + pumps. This also explains the successful conversion of the Cl - to the H + pump only for eubacteria, but not for archaea. It is concluded that water-containing hydrogen-bonding networks constitute one of the essential structural mechanisms in eubacterial light-driven ion pumps.

  16. Diversity and antimicrobial resistance of Salmonella enterica isolates from surface water in Southeastern United States.

    Science.gov (United States)

    Li, Baoguang; Vellidis, George; Liu, Huanli; Jay-Russell, Michele; Zhao, Shaohua; Hu, Zonglin; Wright, Anita; Elkins, Christopher A

    2014-10-01

    A study of prevalence, diversity, and antimicrobial resistance of Salmonella enterica in surface water in the southeastern United States was conducted. A new scheme was developed for recovery of Salmonella from irrigation pond water and compared with the FDA's Bacteriological Analytical Manual (8th ed., 2014) (BAM) method. Fifty-one isolates were recovered from 10 irrigation ponds in produce farms over a 2-year period; nine Salmonella serovars were identified by pulsed-field gel electrophoresis analysis, and the major serovar was Salmonella enterica serovar Newport (S. Newport, n = 29), followed by S. enterica serovar Enteritidis (n = 6), S. enterica serovar Muenchen (n = 4), S. enterica serovar Javiana (n = 3), S. enterica serovar Thompson (n = 2), and other serovars. It is noteworthy that the PulseNet patterns of some of the isolates were identical to those of the strains that were associated with the S. Thompson outbreaks in 2010, 2012, and 2013, S. Enteritidis outbreaks in 2011 and 2013, and an S. Javiana outbreak in 2012. Antimicrobial susceptibility testing confirmed 16 S. Newport isolates of the multidrug resistant-AmpC (MDR-AmpC) phenotype, which exhibited resistance to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, and tetracycline (ACSSuT), and to the 1st, 2nd, and 3rd generations of cephalosporins (cephalothin, amoxicillin-clavulanic acid, and ceftriaxone). Moreover, the S. Newport MDR-AmpC isolates had a PFGE pattern indistinguishable from the patterns of the isolates from clinical settings. These findings suggest that the irrigation water may be a potential source of contamination of Salmonella in fresh produce. The new Salmonella isolation scheme significantly increased recovery efficiency from 21.2 (36/170) to 29.4% (50/170) (P = 0.0002) and streamlined the turnaround time from 5 to 9 days with the BAM method to 4 days and thus may facilitate microbiological analysis of environmental water. Copyright © 2014, American Society for

  17. A multi purpose source chamber at the PLEIADES beamline at SOLEIL for spectroscopic studies of isolated species: cold molecules, clusters, and nanoparticles.

    Science.gov (United States)

    Lindblad, Andreas; Söderström, Johan; Nicolas, Christophe; Robert, Emmanuel; Miron, Catalin

    2013-11-01

    This paper describes the philosophy and design goals regarding the construction of a versatile sample environment: a source capable of producing beams of atoms, molecules, clusters, and nanoparticles in view of studying their interaction with short wavelength (vacuum ultraviolet and x-ray) synchrotron radiation. In the design, specific care has been taken of (a) the use standard components, (b) ensuring modularity, i.e., that swiftly switching between different experimental configurations was possible. To demonstrate the efficiency of the design, proof-of-principle experiments have been conducted by recording x-ray absorption and photoelectron spectra from isolated nanoparticles (SiO2) and free mixed clusters (Ar/Xe). The results from those experiments are showcased and briefly discussed.

  18. Bibliography of electron and photon cross sections with atoms and molecules published in the 20th century. Water vapour

    International Nuclear Information System (INIS)

    Hayashi, Makoto

    2003-12-01

    Bibliographies of original and review reports of experiments or theories of electron and photon cross sections and also electron swarm data are presented for atomic or molecular species with specified targets. These works covered 17 atoms and 51 molecules. The present bibliography is only for water vapour (H 2 O, D 2 O and HDO). About 1200 papers were compiled. A comprehensive author index is included. The bibliography covers the period 1915 through 2000 for H 2 O. Finally, author's comments for electron collision cross sections and photodissociation processes of H 2 O are given. (author)

  19. Coordination geometries of Zn(II) and Cd(II) in phosphotriesterase: Influence of water molecules in the active site

    DEFF Research Database (Denmark)

    Krauss, M; Olsen, Lars; Antony, J

    2002-01-01

    Models of the metal ion binding sites of native ZnZn and of cadmium-substituted ZnCd and CdCd phosphotriesterase, including full amino acid side chains, were geometry optimized with quantum mechanical methods, with effective fragment potentials (EFP) representing the protein environment surroundi...... to the Od1 of the carboxylate of the first-shell aspartate designated M 1, but the energy difference between Cd1Zn2 and the lowest energy Zn1Cd2 structure is only about 2 kcal/mol and decreasing with the addition of water molecules. The Zn1Cd2 arrangement is found experimentally....

  20. Prototropic tautomerism of 4-Methyl 1,2,4-Triazole-3-Thione molecule in solvent water medium: DFT and Car–Parrinello molecular dynamics study

    International Nuclear Information System (INIS)

    Dutta, Bipan; De, Rina; Chowdhury, Joydeep

    2015-01-01

    Highlights: • The tautomerism of 4-MTTN molecule in solvent water medium has been investigated. • CPMD presage the possibility of PT reactions through the solvent water medium. • Concerted PT processes in 4-MTTN have been estimated from the DFT and NBO analyses. • Percentage evolution and breaking of the concerned bonds are estimated. - Abstract: The ground state prototropic tautomerism of 4-Methyl 1,2,4-Triazole-3-Thione molecule in solvent water medium has been investigated with the aid of DFT and Car–Parrinello molecular dynamics (CPMD) simulation studies. The CPMD simulations envisage the possibility of proton transfer reactions of the molecule through the solvent water medium. Probable proton transfer pathways have been predicted from the DFT calculations which are substantiated by the natural bond orbital analyses. The evolution and breaking of the concerned bonds of the molecule for different proton transfer reaction pathways are also estimated.

  1. Membrane solid-phase extraction: Field application for isolation of polycyclic aromatic hydrocarbons from water samples

    International Nuclear Information System (INIS)

    Furlong, E.T.; Koleis, J.C.; Gates, P.M.

    1995-01-01

    Solid-phase extraction (SPE) membranes (M-SPE) were used to isolate microgram-per-liter to nanogram-per-liter quantities of polycyclic aromatic hydrocarbons (PAH) in 4- to 8-liter ground-water samples from a crude-oil-contaminated ground-water site near Bemidji, Minnesota. The M-SPE method was evaluated (1) under laboratory conditions using reagent water fortified with individual PAH at 1.23 micrograms per liter, and (2) at the Bemidji site. At the site, ground-water samples were processed and PAH isolated using a M-SPE system connected directly to the well pump. Following sample isolation, all M-SPE samples were extracted using dichloromethane and analyzed by gas chromatography-mass spectrometry with selected-ion monitoring. Operationally, the M-SPE method provided a simple means to isolate PAH on site at the wellhead, particularly for anoxic water samples. Acceptable recoveries, ranging from 56 to over 100 percent, were observed for lower molecular weight PAH (naphthalene to pyrene) using the M-SPE method. Recoveries using M-SPE were somewhat lower, but reproducible, for higher molecular weight PAH (chrysene to benzo[ghi]perylene), ranging from 18 to 56 percent. M-SPE provides the capability to collect and field isolate PAH from a sufficiently large number of samples to identify environmental chemical processes occurring at individual compound concentrations of 50 to 1,200 nanograms per liter. Using M-SPE, the potential for facilitated transport of PAH by in situ-derived dissolved organic carbon (DOC) was evaluated at the site. Plots comparing DOC and PAH concentrations indicate that PAH concentrations increase exponentially with linear increases in DOC concentrations

  2. Boltzmann equation analysis of electron-molecule collision cross sections in water vapor and ammonia

    International Nuclear Information System (INIS)

    Yousfi, M.; Benabdessadok, M.D.

    1996-01-01

    Sets of electron-molecule collision cross sections for H 2 O and NH 3 have been determined from a classical technique of electron swarm parameter unfolding. This deconvolution method is based on a simplex algorithm using a powerful multiterm Boltzmann equation analysis established in the framework of the classical hydrodynamic approximation. It is well adapted for the simulation of the different classes of swarm experiments (i.e., time resolved, time of flight, and steady state experiments). The sets of collision cross sections that exist in the literature are reviewed and analyzed. Fitted sets of cross sections are determined for H 2 O and NH 3 which exhibit features characteristic of polar molecules such as high rotational excitation collision cross sections. The hydrodynamic swarm parameters (i.e., drift velocity, longitudinal and transverse diffusion coefficients, ionization and attachment coefficients) calculated from the fitted sets are in excellent agreement with the measured ones. These sets are finally used to calculate the transport and reaction coefficients needed for discharge modeling in two cases of typical gas mixtures for which experimental swarm data are very sparse or nonexistent (i.e., flue gas mixtures and gas mixtures for rf plasma surface treatment). copyright 1996 American Institute of Physics

  3. Photochemistry and reactivity of the phenyl radical-water system: a matrix isolation and computational study.

    Science.gov (United States)

    Mardyukov, Artur; Crespo-Otero, Rachel; Sanchez-Garcia, Elsa; Sander, Wolfram

    2010-08-02

    The reaction of the phenyl radical 1 with water has been investigated by using matrix isolation spectroscopy and quantum chemical calculations. The primary thermal product of the reaction between 1 and water is a weakly bound complex stabilized by an OH...pi interaction. This complex is photolabile, and visible-light irradiation (lambda>420 nm) results in hydrogen atom transfer from water to radical 1 and the formation of a highly labile complex between benzene and the OH radical. This complex is stable under the conditions of matrix isolation, however, continuous irradiation with lambda>420 nm light results in the complete destruction of the aromatic system and formation of an acylic unsaturated ketene. The mechanisms of all reaction steps are discussed in the light of ab initio and DFT calculations.

  4. Theoretical study on microhydration of SeO42-: On the number of water molecules necessary to stabilize the dianion

    Science.gov (United States)

    Pathak, Arup Kumar

    2012-01-01

    Microhydration of SeO42-·nH2O (n = 1-5) clusters are reported at B3LYP/Aug-cc-pvtz level of theory. Lower size hydrated clusters are stabilized by only double-hydrogen-bonding arrangements and the most stable conformer for higher size cluster (n > 3) contains a cyclic water ring. It is observed that at least one water molecule is necessary to stabilize the dianion in the gas phase against spontaneous electron loss. The microscopic theory based expression provides a route to predict the instability of bare SeO42- and to obtain the VDE for a wide range of cluster sizes including the bulk from the knowledge of the same for a few stable hydrated clusters.

  5. Calculating the ecosystem service of water storage in isolated wetlands using LIDAR in north central Florida, USA

    Science.gov (United States)

    This study used remotely-sensed Light Detection and Ranging (LiDAR) data to estimate potential water storage capacity of isolated wetlands in north central Florida. The data were used to calculate the water storage potential of >8500 polygons identified as isolated wetlands. We ...

  6. Calculating the ecosystem service of water storage in isolated wetlands using LiDAR in north central Florida, USA (presentation)

    Science.gov (United States)

    This study used remotely-sensed Light Detection and Ranging (LiDAR) data to estimate potential water storage capacity of isolated wetlands in north central Florida. The data were used to calculate the water storage potential of >8500 polygons identified as isolated wetlands. We f...

  7. Aqueous Solvation of Polyalanine α-Helices with Specific Water Molecules and with the CPCM and SM5.2 Aqueous Continuum Models using Density Functional Theory

    OpenAIRE

    Marianski, Mateusz; Dannenberg, J. J.

    2012-01-01

    We present density functional theory (DFT) calculations at the X3LYP/D95(d,p) level on the solvation of polyalanine α-helices in water. The study includes the effects of discrete water molecules and the CPCM and AMSOL SM5.2 solvent continuum model both separately and in combination. We find that individual water molecules cooperatively hydrogen-bond to both the C- and N-termini of the helix, which results in increases in the dipole moment of the helix/water complex to more than the vector sum...

  8. Isolation of saprophytic Leptospira spp. from a selected environmental water source of Argentina.

    Science.gov (United States)

    Scialfa, Exequiel; Grune, Sylvia; Brihuega, Bibiana; Aguirre, Pablo; Rivero, Marina

    2017-11-29

    Ten Leptospira spp. strains were isolated from water samples from Nievas stream, Olavarría, Buenos Aires province (Argentina). The isolates showed the typical motility and morphology of the genus Leptospira under dark field microscopy, developing in liquid EMJH medium after eight days of incubation at 13°C and 30°C. All isolates were negative by the Multiple Locus Variable Number Tandem Repeat Analysis (MLVA). Molecular identification by 16S rRNA gene sequencing identified all isolates as nonpathogenic leptospires. Four isolates showed a genetic profile identical to that of the reference strain Leptospira biflexa serovar Patoc, and six isolates revealed sequence similarities within the 97-98% range, closely related to Leptospira yanagawae and Leptospira meyeri, respectively. Strains ScialfaASA42, ScialfaASA45, ScialfaASA44, ScialfaASA47, ScialfaASA49, ScialfaASA50 and ScialfaASA51 possibly represent a novel species of the genus Leptospira. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  9. MSINDO quantum chemical modeling study of water molecule adsorption at nano-sized anatase TiO2 surfaces

    International Nuclear Information System (INIS)

    Wahab, Hilal S.; Bredow, Thomas; Aliwi, Salah M.

    2008-01-01

    In this work, we studied the adsorption of water molecule onto the (1 0 0), (0 1 0) and (0 0 1) surfaces of nano-sized anatase TiO 2 with semiempirical SCF MO method, MSINDO. The anatase TiO 2 particles are modeled with free clusters (TiO 2 ) n, where n = 20-80. Whereas, the surfaces have been modeled with two saturated clusters, Ti 21 O 58 H 32 and Ti 36 O 90 H 36 . The surface lattice fivefold coordinated titanium atoms (Ti 5C ), which represent the Lewis acid sites, are selected as adsorption centers. We also investigated the effect of TiO 2 cluster size on the computed band gap energy. Results reveal that the electronic properties of a cluster in the lowest excited state differ from that of the ground state. Furthermore, the MSINDO band gap energies of 3.68-3.77 eV for the anatase TiO 2 are in a fair accordance with other literature data. In agreement with other computational and experimental studies, the dissociated form of water molecule adsorption on anatase TiO 2 surfaces is always more stabilized than the molecular form

  10. Effect of anodizing voltage on the sorption of water molecules on porous alumina

    Energy Technology Data Exchange (ETDEWEB)

    Vrublevsky, I., E-mail: vrublevsky@bsuir.edu.by [Belarusian State University of Informatics and Radioelectronics, Department of Micro and Nanoelectronics, 220013 Minsk (Belarus); Chernyakova, K. [Belarusian State University of Informatics and Radioelectronics, Department of Micro and Nanoelectronics, 220013 Minsk (Belarus); Bund, A.; Ispas, A.; Schmidt, U. [Fachgebiet Elektrochemie und Galvanotechnik, Technische Universitaet Ilmenau, 98693 Ilmenau (Germany)

    2012-05-01

    The amount of water adsorbed on different centers on the surface of oxalic acid alumina films is a function of the anodizing voltage. It is decreased with increasing the anodizing voltage from 20 up to 50 V, came up to maximum value at 20-30 V and slightly increased at voltages above 50 V. Water adsorption by oxide films formed at voltages below 50 V can be due to the negative surface charge that is present on the alumina surface. The negative surface charge disappears in the films formed at voltages higher than 50 V, and thus, the water is adsorbed on aluminum ions in a tetrahedral and octahedral environment. The correlation between anodizing conditions of aluminum in oxalic acid and the structure and composition of anodic alumina was established by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), thermogravimetric and differential thermal analyses (TG/DTA).

  11. Isolation and identification of Salmonella spp. in environmental water by molecular technology in Taiwan

    Science.gov (United States)

    Kuo, Chun Wei; Hao Huang, Kuan; Hsu, Bing Mu; Tsai, Hsien Lung; Tseng, Shao Feng; Shen, Tsung Yu; Kao, Po Min; Shen, Shu Min; Chen, Jung Sheng

    2013-04-01

    Salmonella spp. is one of the most important causal agents of waterborne diseases. The taxonomy of Salmonella is very complicated and its genus comprises more than 2,500 serotypes. The detection of Salmonella in environmental water samples by routines culture methods using selective media and characterization of suspicious colonies based on biochemical tests and serological assay are generally time consuming. To overcome this drawback, it is desirable to use effective method which provides a higher discrimination and more rapid identification about Salmonella in environmental water. The aim of this study is to investigate the occurrence of Salmonella using molecular technology and to identify the serovars of Salmonella isolates from 70 environmental water samples in Taiwan. The analytical procedures include membrane filtration, non-selective pre-enrichment, selective enrichment of Salmonella. After that, we isolated Salmonella strains by selective culture plates. Both selective enrichment and culture plates were detected by Polymerase Chain Reaction (PCR). Finally, the serovars of Salmonella were confirmed by using biochemical tests and serological assay. In this study, 15 water samples (21.4%) were identified as Salmonella by PCR. The positive water samples will further identify their serotypes by culture method. The presence of Salmonella in environmental water indicates the possibility of waterborne transmission in drinking watershed. Consequently, the authorities need to provide sufficient source protection and to maintain the system for disease prevention. Keywords: Salmonella spp., serological assay, PCR

  12. Distinguishing Biologically Relevant Hexoses by Water Adduction to the Lithium-Cationized Molecule.

    Science.gov (United States)

    Campbell, Matthew T; Chen, Dazhe; Wallbillich, Nicholas J; Glish, Gary L

    2017-10-03

    A method to distinguish the four most common biologically relevant underivatized hexoses, d-glucose, d-galactose, d-mannose, and d-fructose, using only mass spectrometry with no prior separation/derivatization step has been developed. Electrospray of a solution containing hexose and a lithium salt generates [Hexose+Li] + . The lithium-cationized hexoses adduct water in a quadrupole ion trap. The rate of this water adduction reaction can be used to distinguish the four hexoses. Additionally, for each hexose, multiple lithiation sites are possible, allowing for multiple structures of [Hexose+Li] + . Electrospray produces at least one structure that reacts with water and at least one that does not. The ratio of unreactive lithium-cationized hexose to total lithium-cationized hexose is unique for the four hexoses studied, providing a second method for distinguishing the isomers. Use of the water adduction reaction rate or the unreactive ratio provides two separate methods for confidently (p ≤ 0.02) distinguishing the most common biologically relevant hexoses using only femtomoles of hexose. Additionally, binary mixtures of glucose and fructose were studied. A calibration curve was created by measuring the reaction rate of various samples with different ratios of fructose and glucose. The calibration curve was used to accurately measure the percentage of fructose in three samples of high fructose corn syrup (<4% error).

  13. Incipient ferroelectricity of water molecules confined to nano-channels of beryl

    Czech Academy of Sciences Publication Activity Database

    Gorshunov, B. P.; Torgashev, V. I.; Zhukova, E.S.; Thomas, V.G.; Belyanchikov, M. A.; Kadlec, Christelle; Kadlec, Filip; Savinov, Maxim; Ostapchuk, Tetyana; Petzelt, Jan; Prokleška, J.; Tomas, P. V.; Pestrjakov, E.V.; Fursenko, D.A.; Shakurov, G.S.; Prokhorov, A. S.; Gorelik, V. S.; Kadyrov, L.S.; Uskov, V.V.; Kremer, R. K.; Dressel, M.

    2016-01-01

    Roč. 7, Sep (2016), 1-10, č. článku 12842. ISSN 2041-1723 R&D Projects: GA ČR(CZ) GA14-25639S Institutional support: RVO:68378271 Keywords : water * beryl * ferroelectricity * quantum fluctuations * Curie–Weiss behaviour Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 12.124, year: 2016

  14. Quorum Sensing Activity of Mesorhizobium sp. F7 Isolated from Potable Water

    Directory of Open Access Journals (Sweden)

    Pei-Ling Yong

    2014-01-01

    Full Text Available We isolated a bacterial isolate (F7 from potable water. The strain was identified as Mesorhizobium sp. by 16S rDNA gene phylogenetic analysis and screened for N-acyl homoserine lactone (AHL production by an AHL biosensor. The AHL profile of the isolate was further analyzed using high resolution triple quadrupole liquid chromatography mass spectrometry (LC/MS which confirmed the production of multiple AHLs, namely, N-3-oxo-octanoyl-L-homoserine lactone (3-oxo-C8-HSL and N-3-oxo-decanoyl-L-homoserine lactone (3-oxo-C10-HSL. These findings will open the perspective to study the function of these AHLs in plant-microbe interactions.

  15. Characterization of OXA-48-like-producing Enterobacteriaceae isolated from river water in Algeria.

    Science.gov (United States)

    Tafoukt, Rima; Touati, Abdelaziz; Leangapichart, Thongpan; Bakour, Sofiane; Rolain, Jean-Marc

    2017-09-01

    The spread of carbapenemase-producing Enterobacteriaceae (CPE) is a significant problem for healthcare worldwide. The prevalence of carbapenem-resistant Enterobacteriaceae (CPE) in water environments in Algeria are unknown. The aim of this study was to screen for the presence of CPE isolates in the Soummam River in Bejaia, Algeria. Isolates of Enterobacteriaceae recovered from twelve samples of river water and showing reduced susceptibility to carbapenems were included in this study. The isolates were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Isolates were subjected to antimicrobial susceptibility testing and the modified Carba NP test. Carbapenemase and extended-spectrum β-lactamase (ESBL) determinants were studied by PCR amplification and sequencing. The clonal relatedness between isolates was studied by Multilocus Sequence Typing (MLST) method. A total of 20 carbapenem-resistant Enterobacteriaceae strains were included in this study, identified as Escherichia coli (n = 12), Klebsiella pneumoniae (n = 3), Raoultella ornithinolytica (n = 3), Citrobacter freundii (n = 1) and Citrobacter braakii (n = 1). Carbapenemase genes identified in this study included bla OXA-48 , observed in 17 isolates (9 E. coli, 3 K. pneumoniae, 3 R. ornithinolytica, 1 C. freundii and 1 C. braakii), and bla OXA-244 , a variant of bla OXA-48 , was found in three E. coli isolates. MLST showed that 12 E. coli strains belonged to six different sequence types (ST559, ST38, ST212, ST3541, 1972 and ST2142), and we identified three different STs in K. pneumoniae isolates, including ST133, ST2055, and a new sequence type: ST2192. This study showed the presence of OXA-48-like-producing Enterobacteriaceae in water environments and highlighted the potential role of aquatic environments as reservoirs of clinically relevant antimicrobial-resistant bacteria, with the potential to spread throughout the community. Copyright

  16. Isolation and characterization of diuron-degrading bacteria from lotic surface water.

    Science.gov (United States)

    Batisson, Isabelle; Pesce, Stéphane; Besse-Hoggan, Pascale; Sancelme, Martine; Bohatier, Jacques

    2007-11-01

    The bacterial community structure of a diuron-degrading enrichment culture from lotic surface water samples was analyzed and the diuron-degrading strains were selected using a series of techniques combining temporal temperature gradient gel electrophoresis (TTGE) of 16 S rDNA gene V1-V3 variable regions, isolation of strains on agar plates, colony hybridization methods, and biodegradation assays. The TTGE fingerprints revealed that diuron had a strong impact on bacterial community structure and highlighted both diuron-sensitive and diuron-adapted bacterial strains. Two bacterial strains, designated IB78 and IB93 and identified as belonging to Pseudomonas sp. and Stenotrophomonas sp., were isolated and shown to degrade diuron in pure resting cells in a first-order kinetic reaction during the first 24 h of incubation with no 3,4-DCA detected. The percentages of degradation varied from 25% to 60% for IB78 and 20% to 65% for IB93 and for a diuron concentration range from 20 mg/L to 2 mg/L, respectively. It is interesting to note that diuron was less degraded by single isolates than by mixed resting cells, thereby underlining a cumulative effect between these two strains. To the best of our knowledge, this is the first report of diuron-degrading strains isolated from lotic surface water.

  17. The isolation of water-soluble radionuclides from deteriorating spent nuclear fuel in zeolite cartridge

    International Nuclear Information System (INIS)

    Hassan, N.M.; Thompson, M.C.

    1996-01-01

    A method of isolating water-soluble radionuclides leaching from deteriorating spent nuclear fuel by ion-exchange in zeolite cartridges has been studied. Design calculations of two zeolite cartridges to be incorporated in typical spent fuel storage bundle have been provided. Equilibrium exchange data obtained at several temperatures have shown that the maximum exchange capacity of total cesium in sodium titanium aluminosilicate was 114 mg/g zeolite and the capacity at 95% exchange for radioactive isotope Cs-137 was calculated as 55.2 mg/g zeolite. The kinetic data suggest that the rate of exchange of Cs + in sodium titanium aluminosilicate zeolite takes place by a fast initial exchange step followed by slow diffusion of cesium cations. Design calculations based on the equilibrium exchange data show that water-soluble radionuclides leaching from Mk 31 slugs can be isolated using two zeolite cartridges, each 3.7 inches in inside diameter and 2.5 inches in length. The cartridges are designed to isolate 95% of the Cs + leaching from the spent fuel storage bundle. The results from the thermal induced convective flow tests indicate that the system will provide necessary cooling to the spent fuel by convective currents while isolating the Cs + leaching from spent fuel storage bundle in the cartridges

  18. Does borazine–water behave like benzene-water? A matrix isolation infrared and ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, P. [Department of Chemistry, Indian Institute of Science Education and Research, Sector 81, Mohali, Punjab 140306 (India); Purdue University, West Lafayette, Indiana 47907 (United States); Verma, K.; Bawari, D.; Viswanathan, K. S., E-mail: vish@iisermohali.ac.in [Department of Chemistry, Indian Institute of Science Education and Research, Sector 81, Mohali, Punjab 140306 (India)

    2016-06-21

    Borazine is isoelectronic with benzene and is popularly referred to as inorganic benzene. The study of non-covalent interactions with borazine and comparison with its organic counterpart promises to show interesting similarities and differences. The motivation of the present study of the borazine-water interaction, for the first time, stems from such interesting possibilities. Hydrogen-bonded complexes of borazine and water were studied using matrix isolation infrared spectroscopy and quantum chemical calculations. Computations were performed at M06-2X and MP2 levels of theory using 6-311++G(d,p) and aug-cc-pVDZ basis sets. At both the levels of theory, the complex involving an N–H⋯O interaction, where the N–H of borazine serves as the proton donor to the oxygen of water was found to be the global minimum, in contrast to the benzene-water system, which showed an H–π interaction. The experimentally observed infrared spectra of the complexes corroborated well with our computations for the complex corresponding to the global minimum. In addition to the global minimum, our computations also located two local minima on the borazine-water potential energy surface. Of the two local minima, one corresponded to a structure where the water was the proton donor to the nitrogen of borazine, approaching the borazine ring from above the plane of the ring; a structure that resembled the global minimum in the benzene-water H–π complex. The second local minimum corresponded to an interaction of the oxygen of water with the boron of borazine, which can be termed as the boron bond. Clearly the borazine-water system presents a richer landscape than the benzene-water system.

  19. Does borazine–water behave like benzene-water? A matrix isolation infrared and ab initio study

    International Nuclear Information System (INIS)

    Mishra, P.; Verma, K.; Bawari, D.; Viswanathan, K. S.

    2016-01-01

    Borazine is isoelectronic with benzene and is popularly referred to as inorganic benzene. The study of non-covalent interactions with borazine and comparison with its organic counterpart promises to show interesting similarities and differences. The motivation of the present study of the borazine-water interaction, for the first time, stems from such interesting possibilities. Hydrogen-bonded complexes of borazine and water were studied using matrix isolation infrared spectroscopy and quantum chemical calculations. Computations were performed at M06-2X and MP2 levels of theory using 6-311++G(d,p) and aug-cc-pVDZ basis sets. At both the levels of theory, the complex involving an N–H⋯O interaction, where the N–H of borazine serves as the proton donor to the oxygen of water was found to be the global minimum, in contrast to the benzene-water system, which showed an H–π interaction. The experimentally observed infrared spectra of the complexes corroborated well with our computations for the complex corresponding to the global minimum. In addition to the global minimum, our computations also located two local minima on the borazine-water potential energy surface. Of the two local minima, one corresponded to a structure where the water was the proton donor to the nitrogen of borazine, approaching the borazine ring from above the plane of the ring; a structure that resembled the global minimum in the benzene-water H–π complex. The second local minimum corresponded to an interaction of the oxygen of water with the boron of borazine, which can be termed as the boron bond. Clearly the borazine-water system presents a richer landscape than the benzene-water system.

  20. Identification and molecular characterization of Chryseobacterium vrystaatense ST1 isolated from oligomineral water of southeast Serbia

    Directory of Open Access Journals (Sweden)

    Kojić M.

    2012-01-01

    Full Text Available The isolation and molecular characterization of bacterial strains isolated from water sources in the Vlasina Mountain in southeast Serbia, confirmed the presence of a new species Chryseobacterium vrystaatense ST1. This Gram- negative species showed an extremely low level of biochemical reactivity in biochemical tests. The gene for 16S rRNA was amplified by PCR using universal primers and sequenced. Comparison of 16S rRNA gene sequence and phenotypic features indicated that the isolate ST belonged to Chryseobacterium vrystaatense. A BLAST search of sequenced 1088 nucleotides of the 16S rRNA gene with all sequences deposited in the NCBI collection showed the highest similarity (98% with the strain Chryseobacterium vrystaatense sp. nov., designated as strain R-23533. The very high homology of these two strains allowed classification of our strain at the species level, but some differences indicate, and indirectly confirm, that the isolate ST is an authentic representative. On the basis of these results, we could conclude that Chryseobacterium vrystaatense ST was for first time isolated in Serbia, which is particularly important when one bears in mind that there are only three sequences of this species deposited in the NCBI collection.

  1. Comparison of Enterococcus faecium and Enterococcus faecalis Strains isolated from water and clinical samples: antimicrobial susceptibility and genetic relationships.

    Science.gov (United States)

    Castillo-Rojas, Gonzalo; Mazari-Hiríart, Marisa; Ponce de León, Sergio; Amieva-Fernández, Rosa I; Agis-Juárez, Raúl A; Huebner, Johannes; López-Vidal, Yolanda

    2013-01-01

    Enterococci are part of the normal intestinal flora in a large number of mammals, and these microbes are currently used as indicators of fecal contamination in water and food for human consumption. These organisms are considered one of the primary causes of nosocomial and environmental infections due to their ability to survive in the environment and to their intrinsic resistance to antimicrobials. The aims of this study were to determine the biochemical patterns and antimicrobial susceptibilities of Enterococcus faecalis and E. faecium isolates from clinical samples and from water (groundwater, water from the Xochimilco wetland, and treated water from the Mexico City Metropolitan Area) and to determine the genetic relationships among these isolates. A total of 121 enterococcus strains were studied; 31 and 90 strains were isolated from clinical samples and water (groundwater, water from the Xochimilco wetland, and water for agricultural irrigation), respectively. Identification to the species level was performed using a multiplex PCR assay, and antimicrobial profiles were obtained using a commercial kit. Twenty-eight strains were analyzed by pulsed-field gel electrophoresis (PFGE). E. faecium strains isolated from water showed an atypical biochemical pattern. The clinical isolates showed higher resistance to antibiotics than those from water. Both the enterococci isolated from humans, and those isolated from water showed high genetic diversity according to the PFGE analysis, although some strains seemed to be closely related. In conclusion, enterococci isolated from humans and water are genetically different. However, water represents a potential route of transmission to the community and a source of antimicrobial resistance genes that may be readily transmitted to other, different bacterial species.

  2. Comparison of Enterococcus faecium and Enterococcus faecalis Strains isolated from water and clinical samples: antimicrobial susceptibility and genetic relationships.

    Directory of Open Access Journals (Sweden)

    Gonzalo Castillo-Rojas

    Full Text Available Enterococci are part of the normal intestinal flora in a large number of mammals, and these microbes are currently used as indicators of fecal contamination in water and food for human consumption. These organisms are considered one of the primary causes of nosocomial and environmental infections due to their ability to survive in the environment and to their intrinsic resistance to antimicrobials. The aims of this study were to determine the biochemical patterns and antimicrobial susceptibilities of Enterococcus faecalis and E. faecium isolates from clinical samples and from water (groundwater, water from the Xochimilco wetland, and treated water from the Mexico City Metropolitan Area and to determine the genetic relationships among these isolates. A total of 121 enterococcus strains were studied; 31 and 90 strains were isolated from clinical samples and water (groundwater, water from the Xochimilco wetland, and water for agricultural irrigation, respectively. Identification to the species level was performed using a multiplex PCR assay, and antimicrobial profiles were obtained using a commercial kit. Twenty-eight strains were analyzed by pulsed-field gel electrophoresis (PFGE. E. faecium strains isolated from water showed an atypical biochemical pattern. The clinical isolates showed higher resistance to antibiotics than those from water. Both the enterococci isolated from humans, and those isolated from water showed high genetic diversity according to the PFGE analysis, although some strains seemed to be closely related. In conclusion, enterococci isolated from humans and water are genetically different. However, water represents a potential route of transmission to the community and a source of antimicrobial resistance genes that may be readily transmitted to other, different bacterial species.

  3. Abnormal quality detection and isolation in water distribution networks using simulation models

    Directory of Open Access Journals (Sweden)

    F. Nejjari

    2012-11-01

    Full Text Available This paper proposes a model based detection and localisation method to deal with abnormal quality levels based on the chlorine measurements and chlorine sensitivity analysis in a water distribution network. A fault isolation algorithm which correlates on line the residuals (generated by comparing the available chlorine measurements with their estimations using a model with the fault sensitivity matrix is used. The proposed methodology has been applied to a District Metered Area (DMA in the Barcelona network.

  4. Isolation and characterization of coliforms from glacial ice and water in Canada's High Arctic.

    Science.gov (United States)

    Dancer, S J; Shears, P; Platt, D J

    1997-05-01

    Ellesmere Island is the northern most member of the Canadian Arctic Archipelago with over one-third of the land mass covered by ice. A joint services expedition to the island's Blue Mountains offered a unique opportunity for microbiological studies of resident bacteria in an environment uninhabited by man. Over 100 samples of water and ice were collected from stream, lake and glacier and the filtrate cultured under canvas. Bacterial growth was harvested onto swabs for transport back to the UK and 50 coliforms chosen at random for identification and antibiotic susceptibility testing. Most of the glacial strains were capsulated, pigmented and some over 2000 years old. Genera such as Serratia, Enterobacter, Klebsiella and Yersinia were found; speciation was inconclusive and some organisms remain unidentified. Ampicillin resistance was evident in 80% of water isolates as opposed to 30% of the glacial organisms, but the isolates were generally exquisitely susceptible to antibiotics. The facility for ampicillin resistance did not appear to be transferable. Plasmid DNA was found in 33% of the glacial organisms and over 50% of the water isolates. Similar profiles were identified within and apparently between species and required plasmid restriction analysis to help establish identity. Plasmid-free Serratia spp. were subjected to genomic fingerprinting. Indistinguishable patterns were found within sets of isolates both widely spaced by distance and collection date and it was postulated that coliforms able to survive an Arctic environment had spread extensively throughout the expedition area. In conclusion, this study contributes towards knowledge of naturally occurring antibiotic resistance, confirms the presence of plasmids and genotypic data provided evidence that potentially ancient organisms from glaciers can be cultured from water samples significantly distant.

  5. Optimal sensor placement for leakage detection and isolation in water distribution networks

    OpenAIRE

    Rosich Oliva, Albert; Sarrate Estruch, Ramon; Nejjari Akhi-Elarab, Fatiha

    2012-01-01

    In this paper, the problem of leakage detection and isolation in water distribution networks is addressed applying an optimal sensor placement methodology. The chosen technique is based on structural models and thus it is suitable to handle non-linear and large scale systems. A drawback of this technique arises when costs are assigned uniformly. A main contribution of this paper is the proposal of an iterative methodology that focuses on identifying essential sensors which ultimately leads to...

  6. Isolation of Arsenic Resistant Escherichia coli from Sewage Water and Its Potential in Arsenic Biotransformation

    Directory of Open Access Journals (Sweden)

    Basanta Bista

    2017-04-01

    Full Text Available Arsenic contamination in drinking water from ground water poses a threat to the health of a large population in developing countries in Asia. This has sparked great interests in the potential of different microbes in arsenic resistance and removal from water. This study involves isolation of arsenic resistant Escherichia coli from sewage water from Kathmandu University and investigation of its attributes. Arsenic resistant E. coli was successfully isolated which could survive in high concentration of arsenic. The maximum tolerance of arsenite was 909.79 mg/L (sodium arsenite and 3120.1 mg/L arsenate (sodium arsenate which is well above most natural concentration of arsenic in ground water. This particular E. coli tolerated multiple heavy metal like silver nitrate, cobalt sulphate, cadmium chloride, nickel chloride, mercury chloride, copper sulphate, and zinc chloride at concentration 20 µM, 1 mM, 0.5mM, 1mM, 0.01 mM, 1 mM, and 1 mM respectively which are concentrations known to be toxic to E. coli. Biotransformation of arsenite to arsenate was also checked for by a qualitative silver nitrate technique. This E. coli was able to transform arsenate to arsenite. It showed some sensitivity to Ciprofloxacin, Gentamicin and Nalidixic Acid. As E. coli and its genome are very widely studied, these particular properties have a lot of potential in microbial remediation or microbial recovery of metals and possible recombination approaches.

  7. Characterization of antibiotic resistant enterococci isolated from untreated waters for human consumption in Portugal.

    Science.gov (United States)

    Macedo, Ana S; Freitas, Ana R; Abreu, Cristina; Machado, Elisabete; Peixe, Luísa; Sousa, João C; Novais, Carla

    2011-01-31

    Untreated drinking water is frequently overlooked as a source of antibiotic resistance in developed countries. To gain further insight on this topic, we isolated the indicator bacteria Enterococcus spp. from water samples collected in wells, fountains and natural springs supplying different communities across Portugal, and characterized their antibiotic resistance profile with both phenotypic and genetic approaches. We found various rates of resistance to seven antibiotic families. Over 50% of the isolates were resistant to at least ciprofloxacin, tetracyclines or quinupristin-dalfopristin and 57% were multidrug resistant to ≥3 antibiotics from different families. Multiple enterococcal species (E. faecalis, E. faecium, E. hirae, E. casseliflavus and other Enterococcus spp) from different water samples harbored genes encoding resistance to tetracyclines, erythromycin or gentamicin [tet(M)-46%, tet(L)-14%, tet(S)-5%, erm(B)-22%, aac(6´)-Ie-aph(2″)-12%] and putative virulence factors [gel-28%, asa1-16%]. The present study positions untreated drinking water within the spectrum of ecological niches that may be reservoirs of or vehicles for antibiotic resistant enterococci/genes. These findings are worthy of attention as spread of antibiotic resistant enterococci to humans and animals through water ingestion cannot be dismissed. Copyright © 2010 Elsevier B.V. All rights reserved.

  8. Aqueous solvation of polyalanine α-helices with specific water molecules and with the CPCM and SM5.2 aqueous continuum models using density functional theory.

    Science.gov (United States)

    Marianski, Mateusz; Dannenberg, J J

    2012-02-02

    We present density functional theory (DFT) calculations at the X3LYP/D95(d,p) level on the solvation of polyalanine α-helices in water. The study includes the effects of discrete water molecules and the CPCM and AMSOL SM5.2 solvent continuum model both separately and in combination. We find that individual water molecules cooperatively hydrogen-bond to both the C- and N-termini of the helix, which results in increases in the dipole moment of the helix/water complex to more than the vector sum of their individual dipole moments. These waters are found to be more stable than in bulk solvent. On the other hand, individual water molecules that interact with the backbone lower the dipole moment of the helix/water complex to below that of the helix itself. Small clusters of waters at the termini increase the dipole moments of the helix/water aggregates, but the effect diminishes as more waters are added. We discuss the somewhat complex behavior of the helix with the discrete waters in the continuum models.

  9. Ubiquitous water-soluble molecules in aquatic plant exudates determine specific insect attraction.

    Science.gov (United States)

    Sérandour, Julien; Reynaud, Stéphane; Willison, John; Patouraux, Joëlle; Gaude, Thierry; Ravanel, Patrick; Lempérière, Guy; Raveton, Muriel

    2008-10-08

    Plants produce semio-chemicals that directly influence insect attraction and/or repulsion. Generally, this attraction is closely associated with herbivory and has been studied mainly under atmospheric conditions. On the other hand, the relationship between aquatic plants and insects has been little studied. To determine whether the roots of aquatic macrophytes release attractive chemical mixtures into the water, we studied the behaviour of mosquito larvae using olfactory experiments with root exudates. After testing the attraction on Culex and Aedes mosquito larvae, we chose to work with Coquillettidia species, which have a complex behaviour in nature and need to be attached to plant roots in order to obtain oxygen. This relationship is non-destructive and can be described as commensal behaviour. Commonly found compounds seemed to be involved in insect attraction since root exudates from different plants were all attractive. Moreover, chemical analysis allowed us to identify a certain number of commonly found, highly water-soluble, low-molecular-weight compounds, several of which (glycerol, uracil, thymine, uridine, thymidine) were able to induce attraction when tested individually but at concentrations substantially higher than those found in nature. However, our principal findings demonstrated that these compounds appeared to act synergistically, since a mixture of these five compounds attracted larvae at natural concentrations (0.7 nM glycerol, insect relationships in aquatic eco-systems.

  10. Open challenges in structure-based virtual screening: Receptor modeling, target flexibility consideration and active site water molecules description.

    Science.gov (United States)

    Spyrakis, Francesca; Cavasotto, Claudio N

    2015-10-01

    Structure-based virtual screening is currently an established tool in drug lead discovery projects. Although in the last years the field saw an impressive progress in terms of algorithm development, computational performance, and retrospective and prospective applications in ligand identification, there are still long-standing challenges where further improvement is needed. In this review, we consider the conceptual frame, state-of-the-art and recent developments of three critical "structural" issues in structure-based drug lead discovery: the use of homology modeling to accurately model the binding site when no experimental structures are available, the necessity of accounting for the dynamics of intrinsically flexible systems as proteins, and the importance of considering active site water molecules in lead identification and optimization campaigns. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Dynamics of water around the complex structures formed between the KH domains of far upstream element binding protein and single-stranded DNA molecules

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Kaushik; Bandyopadhyay, Sanjoy, E-mail: sanjoy@chem.iitkgp.ernet.in [Molecular Modeling Laboratory, Department of Chemistry, Indian Institute of Technology, Kharagpur 721302 (India)

    2015-07-28

    Single-stranded DNA (ss-DNA) binding proteins specifically bind to the single-stranded regions of the DNA and protect it from premature annealing, thereby stabilizing the DNA structure. We have carried out atomistic molecular dynamics simulations of the aqueous solutions of two DNA binding K homology (KH) domains (KH3 and KH4) of the far upstream element binding protein complexed with two short ss-DNA segments. Attempts have been made to explore the influence of the formation of such complex structures on the microscopic dynamics and hydrogen bond properties of the interfacial water molecules. It is found that the water molecules involved in bridging the ss-DNA segments and the protein domains form a highly constrained thin layer with extremely retarded mobility. These water molecules play important roles in freezing the conformational oscillations of the ss-DNA oligomers and thereby forming rigid complex structures. Further, it is demonstrated that the effect of complexation on the slow long-time relaxations of hydrogen bonds at the interface is correlated with hindered motions of the surrounding water molecules. Importantly, it is observed that the highly restricted motions of the water molecules bridging the protein and the DNA components in the complexed forms originate from more frequent hydrogen bond reformations.

  12. Ubiquitous water-soluble molecules in aquatic plant exudates determine specific insect attraction.

    Directory of Open Access Journals (Sweden)

    Julien Sérandour

    Full Text Available Plants produce semio-chemicals that directly influence insect attraction and/or repulsion. Generally, this attraction is closely associated with herbivory and has been studied mainly under atmospheric conditions. On the other hand, the relationship between aquatic plants and insects has been little studied. To determine whether the roots of aquatic macrophytes release attractive chemical mixtures into the water, we studied the behaviour of mosquito larvae using olfactory experiments with root exudates. After testing the attraction on Culex and Aedes mosquito larvae, we chose to work with Coquillettidia species, which have a complex behaviour in nature and need to be attached to plant roots in order to obtain oxygen. This relationship is non-destructive and can be described as commensal behaviour. Commonly found compounds seemed to be involved in insect attraction since root exudates from different plants were all attractive. Moreover, chemical analysis allowed us to identify a certain number of commonly found, highly water-soluble, low-molecular-weight compounds, several of which (glycerol, uracil, thymine, uridine, thymidine were able to induce attraction when tested individually but at concentrations substantially higher than those found in nature. However, our principal findings demonstrated that these compounds appeared to act synergistically, since a mixture of these five compounds attracted larvae at natural concentrations (0.7 nM glycerol, <0.5 nM uracil, 0.6 nM thymine, 2.8 nM uridine, 86 nM thymidine, much lower than those found for each compound tested individually. These results provide strong evidence that a mixture of polyols (glycerol, pyrimidines (uracil, thymine, and nucleosides (uridine, thymidine functions as an efficient attractive signal in nature for Coquillettidia larvae. We therefore show for the first time, that such commonly found compounds may play an important role in plant-insect relationships in aquatic eco-systems.

  13. Identification of pink-pigmented bacteria isolated from environmental water samples and their biofilm formation abilities.

    Science.gov (United States)

    Furuhata, Katsunori; Kato, Yuko; Goto, Keiichi; Saitou, Keiko; Sugiyama, Jun-Ichi; Hara, Motonobu; Fukuyama, Masahumi

    2008-06-01

    Sixty-seven strains of pink-pigmented bacteria, which were isolated from environmental water samples collected nationwide, were identified by partial 16S rDNA sequence analysis. In addition, the biofilm formation ability of the isolates was experimentally investigated. We could identify only 2 strains at the species level: Pedobacter roseus HS-38 and Runella slithyformis HS-77. The results showed that of the strains tested, 22 strains (32.8%) were Pedobacter spp., which was most frequently identified, followed by 19 strains (28.4%) of Arcicella spp., 16 strains (23.9%) of Deinococcus spp., 5 strains (7.5%) of Roseomonas spp., 4 strains (6.0%) of Flectobacillus spp. and 1 strain (1.5%) of Runella sp. Most isolates showed low similarity values to previously known species, and they were found to be novel species. At a result, it was difficult to identify environmental water-derived pink-pigmented bacteria at the species level. On the other hand, when we measured the absorbance by the crystal violet staining to examine the quantities of biofilm formation of these strains, fifty-five (82.0%) of the 67 isolates formed biofilm. The absorbance of Deinococcus sp. HS-75 was the highest (3.56). When comparing the absorbance values among the genera, Roseomonas spp. showed the highest absorbance (mean:1.62), followed by Deinococcus spp. (mean: 1.03), and Arcicella spp. (mean: 1.01). Strains of Flectobacillus spp. (mean: 0.48) and Pedobacter spp. (mean: 0.42) showed lower absorbance values. As above, it was shown that, at the species level, the pink-pigmented bacteria in the water in the Japanese environment had various levels of ability to form biofilm.

  14. Resistance of a human immunodeficiency virus type 1 isolate to a small molecule CCR5 inhibitor can involve sequence changes in both gp120 and gp41

    International Nuclear Information System (INIS)

    Anastassopoulou, Cleo G.; Ketas, Thomas J.; Depetris, Rafael S.; Thomas, Antonia M.; Klasse, Per Johan; Moore, John P.

    2011-01-01

    Here, we describe the genetic pathways taken by a human immunodeficiency virus type 1 (HIV-1) isolate, D101.12, to become resistant to the small molecule CCR5 inhibitor, vicriviroc (VCV), in vitro. Resistant D101.12 variants contained at least one substitution in the gp120 V3 region (H308P), plus one of two patterns of gp41 sequence changes involving the fusion peptide (FP) and a downstream residue: G514V+V535M or M518V+F519L+V535M. Studies of Env-chimeric and point-substituted viruses in peripheral blood mononuclear cells (PBMC) and TZM-bl cells showed that resistance can arise from the cooperative action of gp120 and gp41 changes, while retaining CCR5 usage. Modeling the VCV inhibition data from the two cell types suggests that D101.12 discriminates between high- and low-VCV affinity forms of CCR5 less than D1/85.16, a resistant virus with three FP substitutions.

  15. Phenotypic and Genetic Diversity of Aeromonas Species Isolated from Fresh Water Lakes in Malaysia.

    Directory of Open Access Journals (Sweden)

    Wei Ching Khor

    Full Text Available Gram-negative bacilli of the genus Aeromonas are primarily inhabitants of the aquatic environment. Humans acquire this organism from a wide range of food and water sources as well as during aquatic recreational activities. In the present study, the diversity and distribution of Aeromonas species from freshwater lakes in Malaysia was investigated using glycerophospholipid-cholesterol acyltransferase (GCAT and RNA polymerase sigma-factor (rpoD genes for speciation. A total of 122 possible Aeromonas strains were isolated and confirmed to genus level using the API20E system. The clonality of the isolates was investigated using ERIC-PCR and 20 duplicate isolates were excluded from the study. The specific GCAT-PCR identified all isolates as belonging to the genus Aeromonas, in agreement with the biochemical identification. A phylogenetic tree was constructed using the rpoD gene sequence and all 102 isolates were identified as: A. veronii 43%, A. jandaei 37%, A. hydrophila 6%, A. caviae 4%, A. salmonicida 2%, A. media 2%, A. allosaccharophila 1%, A. dhakensis 1% and Aeromonas spp. 4%. Twelve virulence genes were present in the following proportions--exu 96%, ser 93%, aer 87%, fla 83%, enolase 70%, ela 62%, act 54%, aexT 33%, lip 16%, dam 16%, alt 8% and ast 4%, and at least 2 of these genes were present in all 102 strains. The ascV, aexU and hlyA genes were not detected among the isolates. A. hydrophila was the main species containing virulence genes alt and ast either present alone or in combination. It is possible that different mechanisms may be used by each genospecies to demonstrate virulence. In summary, with the use of GCAT and rpoD genes, unambiguous identification of Aeromonas species is possible and provides valuable data on the phylogenetic diversity of the organism.

  16. Hydrology and water quality of isolated wetlands: Stormflow changes along two episodic flowpaths

    Directory of Open Access Journals (Sweden)

    James B. Deemy

    2017-12-01

    Full Text Available The Dougherty Plain in southwest Georgia is a flat, karstic, depressional-landscape dominated by irrigated and dry-land agriculture devoted to row-crops and pasture with interspersed wetlands and forests. Stormwater runoff rarely discharges into perennial rivers and streams, except during large storms that induce hydrologic connectivity between fields, wetlands, and streams (event return period is less than one per year.We report the hydrologic and water-quality effects of a 173-mm rainfall event that generated three weeks (Feb 15 to Mar 9, 2014 of continuous flows through and between three normally isolated wetlands. A suite of water-quality parameters (physical, nutrients, and pathogen indicators was monitored daily from offsite (agricultural and onsite (forested sources at two sites along one flowpath and five sites along a second at the Joseph W Jones Ecologic Research Center at Ichauway.Decreasing sediment, nutrient, and pathogen concentrations were observed as water moved across the forested landscapes with embedded wetlands. Two physical parameters (specific conductance and turbidity were strongly-to-moderately correlated (r > 0.8, 0.5, respectively with laboratory-measured parameters (e.g., nutrients, suspended solids, pathogens, which suggest their utility for routine stormwater monitoring and prioritizing sample collection for laboratory analyses at this site. Keywords: Longleaf-pine, Isolated wetlands, Stormflow, Agricultural runoff, Water quality, Dougherty plain, Nutrients, Pathogens

  17. Variance in water chemistry parameters in isolated wetlands of Florida, USA, and relationships with macroinvertebrate and diatom community structure

    Science.gov (United States)

    Eighty small isolated wetlands throughout Florida were sampled in 2005 to explore within-site variability of water chemistry parameters and relate water chemistry to macroinvertebrate and diatom community structure. Three samples or measures of water were collected within each si...

  18. Physical capture and release of drug molecules, water and cations by a smectite clay

    DEFF Research Database (Denmark)

    Carvalho dos Santos, Éverton

    -fluorohectorite (LiFh, Li1.2(Mg4.8Li1.2)Si8O20F4), a synthetic clay mineral from the smectite family, have been experimentally analyzed. By means of X-rays powder diffraction (XRD), using both an in-house instrument and synchrotron radiation, UV-Vis spectroscopy, Thermogravimetric Analysis coupled to an Infrared......-analysis and inelastic neutron scattering data we established that the drug presence into the interlayer space of Fh is weakening the water-clay interactions. Furthermore, CIPRO’s release from Fh in synthetic gastric acid juice (SGA) as a function of time and temperature was also carefully followed. Our studies showed...... and toxicological tests, we demonstrated that the effectiveness and toxicity of pure CIPRO is unaffected in the clay-drug complex. To conclude, the high drug adsorption capacity as well as the slow and gradual release from CIPRO when intercalated in Fh adds this synthetic smectite to the list of promising drug...

  19. Characterization of culturable bacteria isolated from the cold-water coral Lophelia pertusa

    Science.gov (United States)

    Galkiewicz, Julia P.; Pratte, Zoe A.; Gray, Michael A.; Kellogg, Christina A.

    2011-01-01

    Microorganisms associated with corals are hypothesized to contribute to the function of the host animal by cycling nutrients, breaking down carbon sources, fixing nitrogen, and producing antibiotics. This is the first study to culture and characterize bacteria from Lophelia pertusa, a cold-water coral found in the deep sea, in an effort to understand the roles that the microorganisms play in the coral microbial community. Two sites in the northern Gulf of Mexico were sampled over 2 years. Bacteria were cultured from coral tissue, skeleton, and mucus, identified by 16S rRNA genes, and subjected to biochemical testing. Most isolates were members of the Gammaproteobacteria, although there was one isolate each from the Betaproteobacteria and Actinobacteria. Phylogenetic results showed that both sampling sites shared closely related isolates (e.g. Pseudoalteromonas spp.), indicating possible temporally and geographically stable bacterial-coral associations. The Kirby-Bauer antibiotic susceptibility test was used to separate bacteria to the strain level, with the results showing that isolates that were phylogenetically tightly grouped had varying responses to antibiotics. These results support the conclusion that phylogenetic placement cannot predict strain-level differences and further highlight the need for culture-based experiments to supplement culture-independent studies.

  20. Detecting Darwinism from Molecules in the Enceladus Plumes, Jupiter's Moons, and Other Planetary Water Lagoons.

    Science.gov (United States)

    Benner, Steven A

    2017-09-01

    To the astrobiologist, Enceladus offers easy access to a potential subsurface biosphere via the intermediacy of a plume of water emerging directly into space. A direct question follows: If we were to collect a sample of this plume, what in that sample, through its presence or its absence, would suggest the presence and/or absence of life in this exotic locale? This question is, of course, relevant for life detection in any aqueous lagoon that we might be able to sample. This manuscript reviews physical chemical constraints that must be met by a genetic polymer for it to support Darwinism, a process believed to be required for a chemical system to generate properties that we value in biology. We propose that the most important of these is a repeating backbone charge; a Darwinian genetic biopolymer must be a "polyelectrolyte." Relevant to mission design, such biopolymers are especially easy to recover and concentrate from aqueous mixtures for detection, simply by washing the aqueous mixtures across a polycharged support. Several device architectures are described to ensure that, once captured, the biopolymer meets two other requirements for Darwinism, homochirality and a small building block "alphabet." This approach is compared and contrasted with alternative biomolecule detection approaches that seek homochirality and constrained alphabets in non-encoded biopolymers. This discussion is set within a model for the history of the terran biosphere, identifying points in that natural history where these alternative approaches would have failed to detect terran life. Key Words: Enceladus-Life detection-Europa-Icy moon-Biosignatures-Polyelectrolyte theory of the gene. Astrobiology 17, 840-851.

  1. Replacement of outboard main steam isolation valves in a boiling water reactor plant

    Energy Technology Data Exchange (ETDEWEB)

    Schlereth, J.R.; Pennington, D.

    1996-12-01

    Most Boiling Water Reactor plants utilize wye pattern globe valves for main steam isolation valves for both inboard and outboard isolation. These valves have required a high degree of maintenance attention in order to pass the plant local leakage rate testing (LLRT) requirements at each outage. Northern States Power made a decision in 1993 to replace the outboard valves at it`s Monticello plant with double disc gate valves. The replacement of the outboard valves was completed during the fall outage in 1994. During the spring outage in April of 1996 the first LLRT testing was performed with excellent results. This presentation will address the decision process, time requirements and planning necessary to accomplish the task as well as the performance results and cost effectiveness of replacing these components.

  2. Phytotoxicity induced in isolated zooxanthellae by herbicides extracted from Great Barrier Reef flood waters.

    Science.gov (United States)

    Shaw, C M; Brodie, J; Mueller, J F

    2012-01-01

    To date there has been limited evidence anthropogenically sourced pollution from catchments reaching corals of the Great Barrier Reef (GBR). In this study, freshly isolated zooxanthellae were exposed to polar chemicals (chiefly herbicides) extracted from water samples collected in a flood plume in the GBR lagoon. Photosynthetic potential of the isolated zooxanthellae declined after exposure to concentrated extracts (10 times) from all but one of the sampling sites. Photosynthetic potential demonstrated a significant positive relationship with the concentration of diuron in the concentrated extracts and a significant inverse relationship with salinity measured at the sampling site. This study demonstrates that runoff from land based application of herbicides may reduce photosynthetic efficiency in corals of inshore reefs in the GBR. The ecological impacts of the chemicals in combination with other potential stressors on corals remain unclear. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. A complex network based model for detecting isolated communities in water distribution networks

    Science.gov (United States)

    Sheng, Nan; Jia, Youwei; Xu, Zhao; Ho, Siu-Lau; Wai Kan, Chi

    2013-12-01

    Water distribution network (WDN) is a typical real-world complex network of major infrastructure that plays an important role in human's daily life. In this paper, we explore the formation of isolated communities in WDN based on complex network theory. A graph-algebraic model is proposed to effectively detect the potential communities due to pipeline failures. This model can properly illustrate the connectivity and evolution of WDN during different stages of contingency events, and identify the emerging isolated communities through spectral analysis on Laplacian matrix. A case study on a practical urban WDN in China is conducted, and the consistency between the simulation results and the historical data are reported to showcase the feasibility and effectiveness of the proposed model.

  4. Replacement of outboard main steam isolation valves in a boiling water reactor plant

    International Nuclear Information System (INIS)

    Schlereth, J.R.; Pennington, D.

    1996-01-01

    Most Boiling Water Reactor plants utilize wye pattern globe valves for main steam isolation valves for both inboard and outboard isolation. These valves have required a high degree of maintenance attention in order to pass the plant local leakage rate testing (LLRT) requirements at each outage. Northern States Power made a decision in 1993 to replace the outboard valves at it's Monticello plant with double disc gate valves. The replacement of the outboard valves was completed during the fall outage in 1994. During the spring outage in April of 1996 the first LLRT testing was performed with excellent results. This presentation will address the decision process, time requirements and planning necessary to accomplish the task as well as the performance results and cost effectiveness of replacing these components

  5. Multidrug-Resistant Bacteria Isolated from Surface Water in Bassaseachic Falls National Park, Mexico

    Directory of Open Access Journals (Sweden)

    Ma. Carmen E. Delgado-Gardea

    2016-06-01

    Full Text Available Bacterial pathogens are a leading cause of waterborne disease, and may result in gastrointestinal outbreaks worldwide. Inhabitants of the Bassaseachic Falls National Park in Chihuahua, Mexico show seasonal gastroenteritis problems. This aim of this study was to detect enteropathogenic microorganisms responsible for diarrheal outbreaks in this area. In 2013, 49 surface water samples from 13 selected sampling sites along the Basaseachi waterfall and its main rivers, were collected during the spring, summer, autumn, and winter seasons. Fecal and total coliform counts were determined using standard methods; the AutoScan-4 system was used for identification of isolates and the antibiotic resistance profile by challenging each organism using 21 antibiotics. Significant differences among seasons were detected, where autumn samples resulted in the highest total (p < 0.05 and fecal (p < 0.001 coliform counts, whereas the lowest total coliform counts were recorded in spring. Significant differences between sampling sites were observed, where samples from sites 6, 8, and 11 had the highest total coliform counts (p < 0.009, whereas samples from site 9 exhibited the lowest one. From the microbiological analysis, 33 bacterial isolates from 13 different sites and four sampling seasons were selected; 53% of isolates were resistant to at least one antibiotic, and 15% exhibited a multidrug resistance (MDB phenotype. MDB were identified as Klebsiella oxytoca (two out of four identified isolates, Escherichia coli (2/7, and Enterobacter cloacae (1/3. In addition, some water-borne microorganisms exhibited resistance to cefazoline, cefuroxime, ampicillin, and ampicillin-sulbactam. The presence of these microorganisms near rural settlements suggests that wastewater is the contamination source, providing one possible transmission mechanism for diarrheal outbreaks.

  6. Influence of the effective mass of water molecule on thermal neutron scattering; Uticaj efektivne mase molekula vode na rasejanje termalnih neutrona

    Energy Technology Data Exchange (ETDEWEB)

    Markovic, M [Belgrade Univ. (Yugoslavia). Elektrotehnicki Fakultet

    1981-07-01

    The influence of the effective water molecule mass on the thermal neutron scattering on the nucleus of the hydrogen atom has been investigated. Besides the actual water molecule mass (M = 18) the investigations have been carried out with its two effective values (M1 = 16 and M2 = 20). The differential and total cross sections have been calculated for the incident thermal neutron energy E{sub o} = 1 eV. Investigation results show different prominence of the quantum effects and for M2 the appearance of peaks in the quasielastic scattering. (author)

  7. Isolation of thermotolerant Vermamoeba vermiformis strains from water sources in Lanzarote Island, Canary Islands, Spain.

    Science.gov (United States)

    Reyes-Batlle, María; Wagner, Carolina; Zamora-Herrera, Jonadab; Vargas-Mesa, Alejandro; Sifaoui, Ines; González, Ana C; López-Arencibia, Atteneri; Valladares, Basilio; Martínez-Carretero, Enrique; Piñero, José E; Lorenzo-Morales, Jacob

    2016-09-01

    In this study, twenty water samples were collected in the island of Lanzarote, Canary Islands, Spain in order to check for the presence of V. vermiformis strains in these samples. Water samples were cultured on 2% Non-Nutrient Agar (NNA) plates covered with a thin layer of heat killed E. coli and checked daily for the presence of Vermamoeba. After a week, V. vermiformis amoebae were observed in 2 of the 20 processed samples (10%) incubated at room temperature and 37°C. Molecular characterization was carried out by amplifying the 18S rDNA gene and DNA sequencing in order to confirm the identity of the isolated amoebic strains. To the best of our knowledge, this is the first report on the presence of FLA in environmental sources in Lanzarote Island and the first report of Vermamoeba vermiformis in water sources in this island. Furthermore, the two strains isolated in this study were collected in recreational areas with close contact with humans and thus awareness should be raised.

  8. Dihydrogen phosphate-water tape and layers vs dihydrogen phosphate layers tuned by hydrophobic isomeric pyridine-diamine functionalized molecules

    Science.gov (United States)

    Huang, Jing; Liu, Tong-Peng; Huo, Li-Hua; Deng, Zhao-Peng; Gao, Shan

    2017-01-01

    Assembly of six isomeric pyridine-diamine-based molecules, N,N‧-bis(pyridin-4-ylmethyl)ethane-1,2-diamine (M1), N,N‧-bis(pyridin-3-ylmethyl)ethane-1,2-diamine (M2), N,N‧-bis(pyridin-2-ylmethyl)ethane-1,2-diamine (M3), N,N‧-bis(pyridin-4-ylmethyl)propane-1,3-diamine (M4), N,N‧-bis(pyridin-3-ylmethyl)propane-1,2-diamine (M5), and N,N‧-bis(pyridin-2-ylmethyl)propane-1,3-diamine (M6), with phosphoric acid (H3PO4) in different ratio (1:2 and 1:4), leads to the formation of nine salts, H2M12+·2H2PO4-·4H2O (1), H2M22+·2H2PO4-·2H2O (2), H2M32+·2H2PO4-·2H2O (3), H4M14+·4H2PO4- (4), H4M24+·4H2PO4- (5), H4M34+·4H2PO4- (6), H2M42+·2H2PO4-·3H2O (7), 2H2M52+·4H2PO4-·2H3PO4 (8), and H2M62+·2H2PO4- (9), which have been characterized by elemental analysis, IR, TG, PL, powder and single-crystal X-ray diffraction. Structural analyses indicate that hydrogen-bonding patterns of H2PO4- anions, conformation of protonated cations can effectively influence the supramolecular architectures through diverse non-covalent interactions. Hydrous salts 1-3 and 7 present 2D and 3D host-guest supramolecular networks, in which the connection of H2PO4- anions and water molecules generates diverse tape and layer motifs. H2PO4- anions in anhydrous salts 4-6 interconnect with each other through hydrogen bonds to form two types of layers, which are joined by discrete H4M4+ cations into 3D inorganic-organic hybrid supramolecular networks. Salts 8-9 also present 2D and 3D host-guest supramolecular networks where the interconnection of H2PO4- anions and its combination with H3PO4 molecules leads to diverse layers. Luminescent analyses indicate that salts 1-9 exhibit violet and blue emission maximum in the range of 390-467 nm at room temperature.

  9. Interaction of legionella pneumophila and helicobacter pylori with bacterial species isolated from drinking water biofilms

    Directory of Open Access Journals (Sweden)

    Azevedo Nuno F

    2011-03-01

    Full Text Available Abstract Background It is well established that Legionella pneumophila is a waterborne pathogen; by contrast, the mode of Helicobacter pylori transmission remains unknown but water seems to play an important role. This work aims to study the influence of five microorganisms isolated from drinking water biofilms on the survival and integration of both of these pathogens into biofilms. Results Firstly, both pathogens were studied for auto- and co-aggregation with the species isolated from drinking water; subsequently the formation of mono and dual-species biofilms by L. pneumophila or H. pylori with the same microorganisms was investigated. Neither auto- nor co-aggregation was observed between the microorganisms tested. For biofilm studies, sessile cells were quantified in terms of total cells by SYTO 9 staining, viable L. pneumophila or H. pylori cells were quantified using 16 S rRNA-specific peptide nucleic acid (PNA probes and cultivable cells by standard culture techniques. Acidovorax sp. and Sphingomonas sp. appeared to have an antagonistic effect on L. pneumophila cultivability but not on the viability (as assessed by rRNA content using the PNA probe, possibly leading to the formation of viable but noncultivable (VBNC cells, whereas Mycobacterium chelonae increased the cultivability of this pathogen. The results obtained for H. pylori showed that M. chelonae and Sphingomonas sp. help this pathogen to maintain cultivability for at least 24 hours. Conclusions It appears that M. chelonae may have an important role in the survival of both pathogens in drinking water. This work also suggests that the presence of some microorganisms can decrease the cultivability of L. pneumophila but not the viability which indicates that the presence of autochthonous microorganisms can lead to misleading results when the safety of water is assessed by cultivable methods alone.

  10. Isolation and determination of cultural characteristics of a new highly CO2 tolerant fresh water microalgae

    International Nuclear Information System (INIS)

    Yue Lihong; Chen Weigong

    2005-01-01

    Fresh water microalgae, which has high CO 2 tolerance, were isolated and its cultural characteristics were investigated. The ZY-1 strain was identified as genus Chlorella. It showed maximum growth at 10% (v/v) CO 2 enriched air flowing condition, and a good growth rate in a broad range of physically controllable conditions, including CO 2 concentration up to 70% (v/v), CO 2 enriched air flow rate, temperature and pH value. The results indicated the feasibility of the ZY-1 strain for fixing CO 2 from stack gases

  11. Design and performance of General Electric boiling water reactor main steam line isolation valves

    International Nuclear Information System (INIS)

    Rockwell, D.A.; van Zylstra, E.H.

    1976-08-01

    An extensive test program has been completed by the General Electric Company in cooperation with the Commonwealth Edison Company on the basic design type of large main steam line isolation valves used on General Electric Boiling Water Reactors. Based on a total of 40 tests under simulated accident conditions covering a wide range of mass flows, mixture qualities, and closing times, it was concluded that the commercially available valves of this basic type will close completely and reliably as required. Analytical methods to predict transient effects in the steam line and valve after postulated breaks were refined and confirmed by the test program

  12. Isolation and identification of a thermophilic strain producing trehalose synthase from geothermal water in China.

    Science.gov (United States)

    Zhu, Yueming; Zhang, Jun; Wei, Dongsheng; Wang, Yufan; Chen, Xiaoyun; Xing, Laijun; Li, Mingchun

    2008-08-01

    A slightly thermophilic strain, CBS-01, producing trehalose synthase (TreS), was isolated from geothermal water in this study. According to the phenotypic characteristics and phylogenetic analysis of the 16s rRNA gene sequence, it was identified as Meiothermus ruber. The trehalose synthase gene of Meiothermus ruber CBS-01 was cloned by polymerase chain reaction and sequenced. The TreS gene consisted of 2,895 nucleotides, which specified a 964-amino-acid protein. This novel TreS catalyzed reversible interconversion of maltose and trehalose.

  13. The effects of aging on Boiling Water Reactor core isolation cooling system

    International Nuclear Information System (INIS)

    Lee, Bom Soon.

    1994-01-01

    A study was performed to assess the effects of aging on the Reactor Core Isolation Cooling system in commercial Boiling Water Reactors. This study is part of the Nuclear Plant Aging Research program sponsored by the US Nuclear Regulatory Commission. The failure data, from national databases, as well as plant specific data were reviewed and analyzed to understand the effects of aging on the RCIC system. This analysis identified important components that should receive the highest priority in terms of aging management. The aging characterization provided information on the effects of aging on component failure frequency, failure modes, and failure causes

  14. Combined quantum mechanics/molecular mechanics (QM/MM) simulations for protein-ligand complexes: free energies of binding of water molecules in influenza neuraminidase.

    Science.gov (United States)

    Woods, Christopher J; Shaw, Katherine E; Mulholland, Adrian J

    2015-01-22

    The applicability of combined quantum mechanics/molecular mechanics (QM/MM) methods for the calculation of absolute binding free energies of conserved water molecules in protein/ligand complexes is demonstrated. Here, we apply QM/MM Monte Carlo simulations to investigate binding of water molecules to influenza neuraminidase. We investigate five different complexes, including those with the drugs oseltamivir and peramivir. We investigate water molecules in two different environments, one more hydrophobic and one hydrophilic. We calculate the free-energy change for perturbation of a QM to MM representation of the bound water molecule. The calculations are performed at the BLYP/aVDZ (QM) and TIP4P (MM) levels of theory, which we have previously demonstrated to be consistent with one another for QM/MM modeling. The results show that the QM to MM perturbation is significant in both environments (greater than 1 kcal mol(-1)) and larger in the more hydrophilic site. Comparison with the same perturbation in bulk water shows that this makes a contribution to binding. The results quantify how electronic polarization differences in different environments affect binding affinity and also demonstrate that extensive, converged QM/MM free-energy simulations, with good levels of QM theory, are now practical for protein/ligand complexes.

  15. Effect of water activity and temperature on the growth of Eurotium species isolated from animal feeds.

    Science.gov (United States)

    Greco, Mariana; Pardo, Alejandro; Pose, Graciela; Patriarca, Andrea

    Xerophilic fungi represent a serious problem due to their ability to grow at low water activities causing the spoiling of low and intermediate moisture foods, stored goods and animal feeds, with the consequent economic losses. The combined effect of water activity and temperature of four Eurotium species isolated from animal feeds was investigated. Eurotium amstelodami, Eurotium chevalieri, Eurotium repens and Eurotium rubrum were grown at 5, 15, 25, 37 and 45°C on malt extract agar adjusted with glycerol in the range 0.710-0.993 of water activities. The cardinal model proposed by Rosso and Robinson (2001) was applied to fit growth data, with the variable water activity at fixed temperatures, obtaining three cardinal water activities (a wmin , a wmax , a wopt ) and the specific growth rate at the optimum a w (μ opt ). A probabilistic model was also applied to define the interface between growth and no-growth. The cardinal model provided an adequate estimation of the optimal a w to grow and the maximum growth rate. The probabilistic model showed a good performance to fit growth/no-growth cases in the predicted range. The results presented here could be applied to predict Eurotium species growth in animal feeds. Copyright © 2017 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

  16. Solvation study of the non-specific lipid transfer protein from wheat by intermolecular NOEs with water and small organic molecules

    International Nuclear Information System (INIS)

    Liepinsh, Edvards; Sodano, Patrick; Tassin, Severine; Marion, Didier; Vovelle, Francoise; Otting, Gottfried

    1999-01-01

    Intermolecular nuclear Overhauser effects (NOEs) were measured between the protons of various small solvent or gas molecules and the non-specific lipid transfer protein (ns-LTP) from wheat. Intermolecular NOEs were observed with the hydrophobic pocket in the interior of wheat ns-LTP, which grew in intensity in the order cyclopropane (saturated solution) < methane (140 bar) < ethane (40 bar) < acetonitrile (5% in water) < cyclohexane (saturated solution) < benzene (saturated solution). No intermolecular NOEs were observed with dioxane (5% in water). The intermolecular NOEs were negative for all of the organic molecules tested. Intermolecular NOEs between wheat ns-LTP and water were weak or could not be distinguished from exchange-relayed NOEs. As illustrated by the NOEs with cyclohexane versus dioxane, the hydrophobic pocket in wheat ns-LTP preferably binds non-polar molecules. Yet, polar molecules like acetonitrile can also be accommodated. The pressure dependence of the NOEs between methane and wheat ns-LTP indicated incomplete occupancy, even at 190 bar methane pressure. In general, NOE intensities increased with the size of the ligand molecule and its vapor pressure. NMR of the vapor phase showed excellent resolution between the signals from the gas phase and those from the liquid phase. The vapor concentration of cyclohexane was fivefold higher than that of the dioxane solution, supporting the binding of cyclohexane versus uptake of dioxane

  17. Docking ligands into flexible and solvated macromolecules. 7. Impact of protein flexibility and water molecules on docking-based virtual screening accuracy.

    Science.gov (United States)

    Therrien, Eric; Weill, Nathanael; Tomberg, Anna; Corbeil, Christopher R; Lee, Devin; Moitessier, Nicolas

    2014-11-24

    The use of predictive computational methods in the drug discovery process is in a state of continual growth. Over the last two decades, an increasingly large number of docking tools have been developed to identify hits or optimize lead molecules through in-silico screening of chemical libraries to proteins. In recent years, the focus has been on implementing protein flexibility and water molecules. Our efforts led to the development of Fitted first reported in 2007 and further developed since then. In this study, we wished to evaluate the impact of protein flexibility and occurrence of water molecules on the accuracy of the Fitted docking program to discriminate active compounds from inactive compounds in virtual screening (VS) campaigns. For this purpose, a total of 171 proteins cocrystallized with small molecules representing 40 unique enzymes and receptors as well as sets of known ligands and decoys were selected from the Protein Data Bank (PDB) and the Directory of Useful Decoys (DUD), respectively. This study revealed that implementing displaceable crystallographic or computationally placed particle water molecules and protein flexibility can improve the enrichment in active compounds. In addition, an informed decision based on library diversity or research objectives (hit discovery vs lead optimization) on which implementation to use may lead to significant improvements.

  18. Multidrug-Resistant Bacteria Isolated from Surface Water in Bassaseachic Falls National Park, Mexico.

    Science.gov (United States)

    Delgado-Gardea, Ma Carmen E; Tamez-Guerra, Patricia; Gomez-Flores, Ricardo; Zavala-Díaz de la Serna, Francisco Javier; Eroza-de la Vega, Gilberto; Nevárez-Moorillón, Guadalupe Virginia; Pérez-Recoder, María Concepción; Sánchez-Ramírez, Blanca; González-Horta, María Del Carmen; Infante-Ramírez, Rocío

    2016-06-16

    Bacterial pathogens are a leading cause of waterborne disease, and may result in gastrointestinal outbreaks worldwide. Inhabitants of the Bassaseachic Falls National Park in Chihuahua, Mexico show seasonal gastroenteritis problems. This aim of this study was to detect enteropathogenic microorganisms responsible for diarrheal outbreaks in this area. In 2013, 49 surface water samples from 13 selected sampling sites along the Basaseachi waterfall and its main rivers, were collected during the spring, summer, autumn, and winter seasons. Fecal and total coliform counts were determined using standard methods; the AutoScan-4 system was used for identification of isolates and the antibiotic resistance profile by challenging each organism using 21 antibiotics. Significant differences among seasons were detected, where autumn samples resulted in the highest total (p water-borne microorganisms exhibited resistance to cefazoline, cefuroxime, ampicillin, and ampicillin-sulbactam. The presence of these microorganisms near rural settlements suggests that wastewater is the contamination source, providing one possible transmission mechanism for diarrheal outbreaks.

  19. Attosecond electron dynamics in molecules and liquids

    Science.gov (United States)

    WöRner, Hans Jakob

    The ultrafast motion of electrons and holes following light-matter interaction is fundamental to a broad range of chemical and biophysical processes. In this lecture, I will discuss some of our recent experiments that measure the atomic-scale motion of charge with attosecond temporal resolution (1 as = 10-18s). The first experiment is carried out on isolated, spatially oriented molecules in the gas phase. Using high-harmonic spectroscopy, we resolve the migration of an electron hole across the molecule with a resolution of 100 as and simultaneously demonstrate extensive control over charge migration. In the second class of experiments, we use an attosecond pulse train synchronized with a near-infrared laser pulse to temporally resolve the process of photoemission from molecules in the gas phase and from a liquid-water microjet, resolving electron transport through liquid water on the attosecond time scale.

  20. Impact of enumeration method on diversity of Escherichia coli genotypes isolated from surface water.

    Science.gov (United States)

    Martin, E C; Gentry, T J

    2016-11-01

    There are numerous regulatory-approved Escherichia coli enumeration methods, but it is not known whether differences in media composition and incubation conditions impact the diversity of E. coli populations detected by these methods. A study was conducted to determine if three standard water quality assessments, Colilert ® , USEPA Method 1603, (modified mTEC) and USEPA Method 1604 (MI), detect different populations of E. coli. Samples were collected from six watersheds and analysed using the three enumeration approaches followed by E. coli isolation and genotyping. Results indicated that the three methods generally produced similar enumeration data across the sites, although there were some differences on a site-by-site basis. The Colilert ® method consistently generated the least diverse collection of E. coli genotypes as compared to modified mTEC and MI, with those two methods being roughly equal to each other. Although the three media assessed in this study were designed to enumerate E. coli, the differences in the media composition, incubation temperature, and growth platform appear to have a strong selective influence on the populations of E. coli isolated. This study suggests that standardized methods of enumeration and isolation may be warranted if researchers intend to obtain individual E. coli isolates for further characterization. This study characterized the impact of three USEPA-approved Escherichia coli enumeration methods on observed E. coli population diversity in surface water samples. Results indicated that these methods produced similar E. coli enumeration data but were more variable in the diversity of E. coli genotypes observed. Although the three methods enumerate the same species, differences in media composition, growth platform, and incubation temperature likely contribute to the selection of different cultivable populations of E. coli, and thus caution should be used when implementing these methods interchangeably for

  1. A natural coagulant protein from Moringa oleifera: isolation, characterization, and potential use for water treatment

    Science.gov (United States)

    Choudhary, Manisha; Neogi, Sudarsan

    2017-10-01

    In developing countries pond water is still widely used for drinking and household purposes, which develops higher turbidity during rainy seasons and requires a large amount of chemical coagulants, and this leads to high cost of treatment. To mitigate this, it is important to find an economical and natural coagulant to treat turbid water. The present study is focused on using a plant based component as a natural coagulant that is sustainable and environment-friendly. This work focuses on the extraction, isolation and purification of a natural coagulant from seed kernels of Moringa oleifera to enhance its turbidity removal efficiency. The determination of themolecular weight of the purified proteins was done using sodium dodecyl sulfate polyacrylamide gel electrophoresis. The active coagulant proteins were isolated using 30-60% and 60-80% saturation of ammonium sulfate. It was observed that proteins with molecular weight less than 36 kDa have superior coagulation activity. Turbidity removal efficiency of these active coagulant proteins was compared with alum. The possibility of using Moringa oleifera seeds as a natural antimicrobial agent was also investigated.

  2. Photoluminescence behaviors of single CdSe/ZnS/TOPO nanocrystals: Adsorption effects of water molecules onto nanocrystal surfaces

    International Nuclear Information System (INIS)

    Oda, Masaru; Hasegawa, Atsushi; Iwami, Noriya; Nishiura, Ken; Ando, Naohisa; Nishiyama, Akira; Horiuchi, Hiromi; Tani, Toshiro

    2007-01-01

    We report here the distinctive modifications of photoluminescence (PL) behaviors in single CdSe/ZnS/TOPO nanocrystals depending on their environments. Long-time traces of PL intensity from single nanocrystals have been obtained in both vacuum and a wet nitrogen atmosphere. While all of the nanocrystals in both environments exhibit PL blinking behaviors, i.e. on-off intermittency of PL intensity, as usual, some of the nanocrystals in the wet nitrogen atmosphere show significant increase in duration time of on-events. As for the duration time of blinking off-events, it is for the moment associated with the occasional events of carrier capturing at trap sites on or near the nanocrystal surfaces. We propose a model in which adsorbed water molecules at the trap sites on the nanocrystal surfaces transform them under light irradiation, which eventually decreases the occurrence of the trapping events due to their inactivation. It in turn increases the PL on-times. In addition to the drastic modification of the blinking profile, we also found that in the PL time traces some kinds of undulated behaviors, i.e. continuous and rather low frequency fluctuation of PL intensity, appear during each on-event in vacuum while they disappear totally in the wet nitrogen atmosphere. These results are also described on the basis of the inactivation model of the trap sites introduced above

  3. Rheological properties of oil-in-water emulsions prepared with oil and protein isolates from sesame (Sesamum Indicum

    Directory of Open Access Journals (Sweden)

    David Ramirez BREWER

    2016-01-01

    Full Text Available In this study, food emulsions of oil in water from sesame (Sesamum indicum protein isolates and their oil were formulated and standardised. The effect of the concentrations of sesame (Sesamum indicum protein isolates and base oil and the speed of the emulsification process for the food emulsion stability was studied. The protein isolates were achieved from the defatted sesame flour (DSF, obtaining a percentage of 80% ± 0.05% of protein. Emulsions were formulated through a factorial design 23. The rheological behaviour of sesame (Sesamum indicum protein isolates-stabilised emulsions and microstructural composition were investigated. Stable emulsions with suitable rheological properties and microstructure were formulated at a concentration of 10% sesame oil and different concentrations of protein isolates, between 1.5% and 2.5%, with the best droplet distribution characteristics being shown for the 2.5% sesame protein isolates. The emulsions showed a non-Newtonian fluid behaviour, adjusting the Sisko model.

  4. Frozen Dynamics and Insulation of Water at the Lipid Interface

    NARCIS (Netherlands)

    Bakulin, A.A.; Cringus, D.; Pshenichnikov, M.S.; Wiersma, D.A.; Corkum, P; DeSilvestri, S; Nelson, KA; Riedle, E

    2009-01-01

    2D IR correlation spectroscopy reveals extremely slow dynamics and splitting of the OH-stretching mode of water in anionic micelles. Water at the lipid interface behaves as if the molecules were isolated in a "frozen" environment.

  5. Molecular and biochemical characterization of Pseudomonas putida isolated from bottled uncarbonated mineral drinking water

    Directory of Open Access Journals (Sweden)

    Tasić S.

    2014-01-01

    Full Text Available Pseudomonas putida belongs to a group of opportunistic pathogens that can cause disease in people with weakened or damaged immune systems. Some strains have medical significance, and for most ingestion is not the primary route of infection. If water used by predisposed subjects is contaminated by P. putida, they may become ill. The aim of this work was the biochemical and molecular characterization of strain ST3 of P. putida isolated from non-carbonated bottled drinking water from Jakov Do 4 on Mt. Vlasina. Characterization of P. putida was performed to assess the risk to human health of the indigenous strains present in the water. Biochemical characterization of strains was performed using the manual identification system ID 32 GN (BioMérieux. Identification was obtained using the database identification software ATB System (Bio-Mérieux. Molecular characterization was performed by PCR amplification and 16S rDNA “thermal cycling sequencing”. Biochemical identification of the strain ST3 was accurate (Id = 99.8%. Comparing the sequences obtained for strain ST3 with NCBI gene bank sequences for 16S rRNA, the highest similarity of our strain (96% identity with a strain of P. putida, designated as biotype A (gi|18076625|emb|AJ308311.1|.PPU308311 isolated in New Zealand, was obtained. While comparison with the NCBI collection of all deposited sequences showed that the 16S rRNA gene sequence of strain ST3 has very high homology, it is not identical, indicating indirectly that strain ST3 is an indigenous strain.

  6. The Effectiveness of Heterotrophic Bacteria Isolated from Dumai Marine Waters of Riau, Used as Antibacterial against Pathogens in Fish Culture

    Science.gov (United States)

    Feliatra, F.; Nursyirwani; Tanjung, A.; Adithiya, DS; Susanna, M.; Lukystyowati, I.

    2018-02-01

    Heterotrophic bacteria have an important role as decomposer of organic compounds (mineralization) derived from industrial waste, decomposition of unconsumed feed, faecal, excretion of fish, and have the ability to inhibit the growth of pathogenic bacteria. We investigated the role of heterotrophic bacteria used as antibacterial against pathogens in fish culture.This research was conducted from January until March 2017. The phylogenitic of the isolated bacterial was determined by 16S rDNA sequences analysis. Antagonism test showed that the bacteria had the ability to inhibit the growth of pathogenic bacteria (Vibrio alginolyticus, Aeromonas hydrophila and Pseudomonas sp.) Three isolates (Dm5, Dm6 and Dm4) indicated high inhibition zones which were classified into strong category with the average from 10.5 to 11.8 mm toward V. alginolitycus. Other isolates were classified into medium and weak category. Based on DNA analysis of heterotrophic bacteria isolated from marine waters of industrial area and low salinity of estuarine waters twelve strains of bacteria were identified, and all had highest level of homology to Bacillus sp.,one isolates has similarity to Enterobacter cloacae, other isolates to Clostridium cetobutylicum. Most of isolated bacteria obtained from the waters of industrial area due to it received much of nutrients that very influenced the growth of bacteria.

  7. Isolation of Environmental Bacteria from Surface and Drinking Water in Mafikeng, South Africa, and Characterization Using Their Antibiotic Resistance Profiles

    Directory of Open Access Journals (Sweden)

    Suma George Mulamattathil

    2014-01-01

    Full Text Available The aim of this study was to isolate and identify environmental bacteria from various raw water sources as well as the drinking water distributions system in Mafikeng, South Africa, and to determine their antibiotic resistance profiles. Water samples from five different sites (raw and drinking water were analysed for the presence of faecal indicator bacteria as well as Aeromonas and Pseudomonas species. Faecal and total coliforms were detected in summer in the treated water samples from the Modimola dam and in the mixed water samples, with Pseudomonas spp. being the most prevalent organism. The most prevalent multiple antibiotic resistance phenotype observed was KF-AP-C-E-OT-K-TM-A. All organisms tested were resistant to erythromycin, trimethoprim, and amoxicillin. All isolates were susceptible to ciprofloxacin and faecal coliforms and Pseudomonas spp. to neomycin and streptomycin. Cluster analysis based on inhibition zone diameter data suggests that the isolates had similar chemical exposure histories. Isolates were identified using gyrB, toxA, ecfX, aerA, and hylH gene fragments and gyrB, ecfX, and hylH fragments were amplified. These results demonstrate that (i the drinking water from Mafikeng contains various bacterial species and at times faecal and total coliforms. (ii The various bacteria are resistant to various classes of antibiotics.

  8. Thermodynamic properties of water molecules in the presence of cosolute depend on DNA structure: a study using grid inhomogeneous solvation theory

    Science.gov (United States)

    Nakano, Miki; Tateishi-Karimata, Hisae; Tanaka, Shigenori; Tama, Florence; Miyashita, Osamu; Nakano, Shu-ichi; Sugimoto, Naoki

    2015-01-01

    In conditions that mimic those of the living cell, where various biomolecules and other components are present, DNA strands can adopt many structures in addition to the canonical B-form duplex. Previous studies in the presence of cosolutes that induce molecular crowding showed that thermal stabilities of DNA structures are associated with the properties of the water molecules around the DNAs. To understand how cosolutes, such as ethylene glycol, affect the thermal stability of DNA structures, we investigated the thermodynamic properties of water molecules around a hairpin duplex and a G-quadruplex using grid inhomogeneous solvation theory (GIST) with or without cosolutes. Our analysis indicated that (i) cosolutes increased the free energy of water molecules around DNA by disrupting water–water interactions, (ii) ethylene glycol more effectively disrupted water–water interactions around Watson–Crick base pairs than those around G-quartets or non-paired bases, (iii) due to the negative electrostatic potential there was a thicker hydration shell around G-quartets than around Watson–Crick-paired bases. Our findings suggest that the thermal stability of the hydration shell around DNAs is one factor that affects the thermal stabilities of DNA structures under the crowding conditions. PMID:26538600

  9. Production of anatoxin-a by cyanobacterial strains isolated from Portuguese fresh water systems.

    Science.gov (United States)

    Osswald, Joana; Rellán, Sandra; Gago-Martinez, Ana; Vasconcelos, Vítor

    2009-11-01

    The occurrence of anatoxin-a in several freshwater systems in Portugal and its production by Portuguese cyanobacterial strains, after cultivation in laboratory, were studied. Surface water samples from 9 water bodies, for recreational and human consumption usage, were surveyed for anatoxin-a presence and for obtaining cultures of pure cyanobacterial strains. Anatoxin-a analysis was performed by high performance liquid chromatography (HPLC) with fluorescence detection (FLD) followed by Mass Spectrometry (MS) confirmation. No anatoxin-a was detected in all the natural water samples (limit of detection (LOD) = 25 ng l(-1)) but among the 22 isolated cyanobacterial strains, 13 could produce anatoxin-a in laboratory conditions (LOD = 3 ng g(-1) dw). This proportion of anatoxin-a producing strains (59.1%) in laboratory is discussed considering the hypothesis that anatoxin-a is a more frequent metabolite in cyanobacteria than it was thought before and making its occurrence in Portuguese freshwaters almost certain. Therefore, health and ecological risks caused by anatoxin-a in Portugal, should be seriously considered.

  10. Antibiotic resistance and enterotoxin genes in Staphylococcus sp. isolates from polluted water in Southern Brazil.

    Science.gov (United States)

    Basso, Ana P; Martins, Paula D; Nachtigall, Gisele; Van Der Sand, Sueli; De Moura, Tiane M; Frazzon, Ana Paula G

    2014-12-01

    The aim of this study was to evaluate the species distribution, antibiotic-resistance profile and presence of enterotoxin (SE) genes in staphylococci isolated from the Dilúvio stream in South Brazil. Eighty-eight staphylococci were identified, 93.18% were identified as coagulase-negative (CNS) and 6.82% coagulase-positive (CPS). Fourteen Staphylococcus species were detected and the most frequently were Staphylococcus cohnii (30.48%) and S. haemolyticus (21.95%). Resistance to erythromycin was verified in 37.50% of the strains, followed by 27.27% to penicillin, 12.50% to clindamycin, 6.81% to trimethoprim-sulfamethoxazole, 5.68% to chloramphenicol and 2.27% to norfloxacin. None of the investigated strains showed gentamicin and ciprofloxacin resistance. The strains were tested for the presence of sea, seb, sec, sed and see genes by PCR and only CNS strains (43.18%) showed positive results to one or more SE genes. The scientific importance of our results is due to the lack of data about these topics in polluted waters in Brazil. In conclusion, polluted waters from the Dilúvio stream may constitute a reservoir for disseminating antibiotic-resistance and enterotoxin into the community. In addition, the detection of staphylococci in the polluted waters of the Dilúvio stream indicated a situation of environmental contamination and poor sanitation conditions.

  11. Antibiotic resistance and enterotoxin genes in Staphylococcus sp. isolates from polluted water in Southern Brazil

    Directory of Open Access Journals (Sweden)

    ANA P. BASSO

    2014-12-01

    Full Text Available The aim of this study was to evaluate the species distribution, antibiotic-resistance profile and presence of enterotoxin (SE genes in staphylococci isolated from the Dilúvio stream in South Brazil. Eighty-eight staphylococci were identified, 93.18% were identified as coagulase-negative (CNS and 6.82% coagulase-positive (CPS. Fourteen Staphylococcus species were detected and the most frequently were Staphylococcus cohnii (30.48% and S. haemolyticus (21.95%. Resistance to erythromycin was verified in 37.50% of the strains, followed by 27.27% to penicillin, 12.50% to clindamycin, 6.81% to trimethoprim-sulfamethoxazole, 5.68% to chloramphenicol and 2.27% to norfloxacin. None of the investigated strains showed gentamicin and ciprofloxacin resistance. The strains were tested for the presence of sea, seb, sec, sed and see genes by PCR and only CNS strains (43.18% showed positive results to one or more SE genes. The scientific importance of our results is due to the lack of data about these topics in polluted waters in Brazil. In conclusion, polluted waters from the Dilúvio stream may constitute a reservoir for disseminating antibiotic-resistance and enterotoxin into the community. In addition, the detection of staphylococci in the polluted waters of the Dilúvio stream indicated a situation of environmental contamination and poor sanitation conditions.

  12. A nonpolar, nonamphiphilic molecule can accelerate adsorption of phospholipids and lower their surface tension at the air/water interface.

    Science.gov (United States)

    Nguyen, Phuc Nghia; Trinh Dang, Thuan Thao; Waton, Gilles; Vandamme, Thierry; Krafft, Marie Pierre

    2011-10-04

    The adsorption dynamics of a series of phospholipids (PLs) at the interface between an aqueous solution or dispersion of the PL and a gas phase containing the nonpolar, nonamphiphilic linear perfluorocarbon perfluorohexane (PFH) was studied by bubble profile analysis tensiometry. The PLs investigated were dioctanoylphosphatidylcholine (DiC(8)-PC), dilaurylphosphatidylcholine, dimyristoylphosphatidylcholine, and dipalmitoylphosphatidylcholine. The gas phase consisted of air or air saturated with PFH. The perfluorocarbon gas was found to have an unexpected, strong effect on both the adsorption rate and the equilibrium interfacial tension (γ(eq)) of the PLs. First, for all of the PLs, and at all concentrations investigated, the γ(eq) values were significantly lower (by up to 10 mN m(-1)) when PFH was present in the gas phase. The efficacy of PFH in decreasing γ(eq) depends on the ability of PLs to form micelles or vesicles in water. For vesicles, it also depends on the gel or fluid state of the membranes. Second, the adsorption rates of all the PLs at the interface (as assessed by the time required for the initial interfacial tension to be reduced by 30%) are significantly accelerated (by up to fivefold) by the presence of PFH for the lower PL concentrations. Both the surface-tension reducing effect and the adsorption rate increasing effect establish that PFH has a strong interaction with the PL monolayer and acts as a cosurfactant at the interface, despite the absence of any amphiphilic character. Fitting the adsorption profiles of DiC(8)-PC at the PFH-saturated air/aqueous solution interface with the modified Frumkin model indicated that the PFH molecule lay horizontally at the interface. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Streptomyces caldifontis sp. nov., isolated from a hot water spring of Tatta Pani, Kotli, Pakistan.

    Science.gov (United States)

    Amin, Arshia; Ahmed, Iftikhar; Khalid, Nauman; Osman, Ghenijan; Khan, Inam Ullah; Xiao, Min; Li, Wen-Jun

    2017-01-01

    A Gram-staining positive, non-motile, rod-shaped, catalase positive and oxidase negative bacterium, designated NCCP-1331 T , was isolated from a hot water spring soil collected from Tatta Pani, Kotli, Azad Jammu and Kashmir, Pakistan. The isolate grew at a temperature range of 18-40 °C (optimum 30 °C), pH 6.0-9.0 (optimum 7.0) and with 0-6 % NaCl (optimum 2 % NaCl (w/v)). The phylogenetic analysis based on 16S rRNA gene sequence revealed that strain NCCP-1331 T belonged to the genus Streptomyces and is closely related to Streptomyces brevispora BK160 T with 97.9 % nucleotide similarity, followed by Streptomyces drosdowiczii NRRL B-24297 T with 97.8 % nucleotide similarity. The DNA-DNA relatedness values of strain NCCP-1331 T with S. brevispora KACC 21093 T and S. drosdowiczii CBMAI 0498 T were 42.7 and 34.7 %, respectively. LL-DAP was detected as diagnostic amino acid along with alanine, glycine, leucine and glutamic acid. The isolate contained MK-9(H 8 ) as the predominant menaquinone. Major polar lipids detected in NCCP-1331 T were phosphatidylethanolamine, phosphatidylinositol and unidentified phospholipids. Major fatty acids were iso-C 16: 0 , summed feature 8 (18:1 ω7c/18:1 ω6c), anteiso-C 15:0 and C 16:0 . The genomic DNA G + C content was 69.8 mol %. On the basis of phylogenetic, phenotypic and chemotaxonomic analysis, it is concluded that strain NCCP-1331 T represents a novel species of the genus Streptomyces, for which the name Streptomyces caldifontis sp. nov. is proposed. The type strain is NCCP-1331 T (=KCTC 39537 T  = CPCC 204147 T ).

  14. Streptomyces kalpinensis sp. nov., an actinomycete isolated from a salt water beach.

    Science.gov (United States)

    Ma, Guo-Quan; Xia, Zhan-Feng; Wan, Chuan-Xing; Zhang, Yao; Luo, Xiao-Xia; Zhang, Li-Li

    2017-12-01

    A novel actinobacterium designated TRM 46509 T was isolated from a salt water beach at Kalpin, Xinjiang, north-west China. The strain was aerobic and Gram-stain-positive, with an optimum NaCl concentration for growth of 1 % (w/v). The isolate formed sparse aerial mycelium and produced spiral spores at the end of the aerial mycelium on Gauze's No. 1 medium. The isolate contained ll-diaminopimelic acid as the diagnostic diamino acid and ribose as the major whole-cell sugar. The polar lipids included diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, phosphatidylinositol mannosides and an unidentified phospholipid. The predominant menaquinones were MK-9(H2), MK-9(H6) and MK-9(H8). The major fatty acids were C16:0, iso-C16 : 0, anteiso-C15 : 0, iso-C15 : 0 and iso-C14 : 0. The G+C content of the DNA was 69.3 mol%. Phylogenetic analysis showed that strain TRM 46509 T shared 16S rRNA gene sequence similarity of 97.6 % with the closest described species Streptomyces tacrolimicus ATCC 55098 T . On the basis of evidence from this polyphasic study, strain TRM 46509 T should be designated as representing a novel species of the genus Streptomyces, for which the name Streptomyces kalpinensis sp. nov. is proposed. The type strain is TRM 46509 T (=CCTCC AA 2015028 T =KCTC 39667 T ).

  15. Inorganics in Organics: Tracking down the Intrinsic Equilibriums between Organic Molecules and Trace Elements in Oceanic Waters

    Science.gov (United States)

    Lechtenfeld, O. J.; Koch, B. P.; Kattner, G.

    2010-12-01

    Recent developments in analytical instrumentation enable to describe biogeochemical processes in oceanic waters on a molecular level. This is the prerequisite to integrate biological and geochemical parameters and to develop chemical cycles on a global perspective. The state-of-the-art Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) applications for dissolved organic matter (DOM) focus mainly on carbon, hydrogen, oxygen and nitrogen isotopes. Implementation of sulfur and especially phosphorus in the molecular formula assignment has been questionable because of ambiguous calculated elemental formulas. On the other hand, many compounds bearing these elements are well known to occur in the dissolved state as part of the permanent recycling processes (e.g. phospholipids, phosphonates) but analytics of dissolved organic phosphorus (DOP) and sulfur (DOS) are often hampered by the large inorganic P and S pools. Even less is known about complexation characteristics of the DOM moieties. Although electrochemical methods provide some information about trace metal speciation, the high amount of organic molecules and its insufficient description as chemical functional classes prevent the assignment of trace metals to ligand classes. Nevertheless, it is undoubtful that a varying but extensive amount of transition metals is bond in form of organic complexes. Hyphenation of reversed phase high performance liquid chromatography (RP-HPLC) with high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) is a valuable tool to study these metal-organic interactions in a qualitative and quantitative approach. We established a desolvation method that allows direct transfer of high organic solvent loads into the plasma. Thus, in combination with internal standardization and external calibration, the investigation of a broad polarity scale was possible. This approach overcomes previous restrictions to non-organic solvent separation techniques like size

  16. Microbial Flora Isolated from Polluted and Non-Polluted Coastal Waters of Karachi

    International Nuclear Information System (INIS)

    Shaheen, A.; Baig, H. S.; Kazmi, S. U.

    2016-01-01

    Marine pollution has now become worldwide environmental concern. Continuous discharge of untreated industrial effluent, municipal and power plant contaminated wastewater has been a serious threat to marine habitat, aesthetic values and interest of visitors to coastal areas. Karachi is the largest city of Pakistan and industrial hub of the Arabian Sea. In this investigation, samples of sediment, water, flora and fauna were taken from nine selected stations on Karachi coast included three stations represented major creeks i.e. Korangi, Gizri and Chinna Creek. These samples were taken during north-east and south-west monsoonal period in 2014. Bacterial flora isolated and identified from samples collected from these sites by conventional method. Among isolated and identified bacteria e.g. Vibrio alginolyticus, Escherichia coli and Streptococuss anginosus were the most dominant species contributing 21.43, 19.64 and 15.18 percent of total assemblage respectively. Among selected sample stations, Korangi creek station was found to be most polluted with coliform and other pathogenic bacteria. These results clearly indicate that threats from these pathogens are not only to marine life but also to the large number of visitors coming to beaches and residents of surrounding area. Moreover; immediate action should be taken to restrict the growth of these pathogens by taking measures to treat the municipal and industrial effluent to avoid outbreak of any disease in future. (author)

  17. Fabibacter misakiensis sp. nov., a marine bacterium isolated from coastal surface water.

    Science.gov (United States)

    Wong, Shu-Kuan; Park, Sanghwa; Lee, Jung-Sook; Lee, Keun Chul; Chiura, Hiroshi Xavier; Kogure, Kazuhiro; Hamasaki, Koji

    2015-10-01

    A slightly curved-rod-shaped, pink-pigmented, Gram-stain-negative, aerobic bacterial strain with gliding motility, designated SK-8T, was isolated from coastal surface water of Misaki, Japan. Phylogenetic trees generated using 16S rRNA gene sequences revealed that strain SK-8T belonged to the genus Fabibacter and showed 96.0 % sequence similarity to the type strain of the most closely related species, Fabibacter pacificus DY53T. The novel isolate was phenotypically and physiologically different from previously described strains. The major cellular fatty acids were iso-C15 : 1 G, iso-C15 : 0 and iso-C17 : 0 3-OH. Major polar lipids were phosphatidylethanolamine, two aminophospholipids and an unidentified phospholipid. The DNA G+C content was 39.1 mol% and MK-7 was the only predominant isoprenoid quinone. On the basis of this taxonomic study employing a polyphasic approach, it was suggested that strain SK-8T represents a novel species of the genus Fabibacter, with the newly proposed name Fabibacter misakiensis sp. nov. The type strain is SK-8T ( = NBRC 110216T = KCTC 32969T).

  18. Crack formation in ferritic screws of main steam isolation valves in German boiling water reactors

    International Nuclear Information System (INIS)

    Steinmill, H.

    1992-01-01

    In connection with crack formations at screws of main steam isolation valves in boiling water reactors, detected for the first time in 1988 in the Federal Republic of Germany, metallographic and fractographic investigations and coating analyses of screw surfaces and crack flanks were performed in order to find out the causes. These and other investigations of damaged screws were accompanied in the years 1989 and 1990 by autoclave tests made in several laboratories. With a view to the mechanical stress of the screws, tightening tests and stress analyses were performed by means of FEM. Repeated autoclave tests were concluded recently by the Stuttgart MPA. Although these tests are not reported here, it can be stated that the results obtained fit in with the overall framework of the results summed up in this report. With regard to the kind of sample stress and the results obtained, two cases have to be distinguished in the autoclave tests discussed in this report. (orig.) [de

  19. Legionella thermalis sp. nov., isolated from hot spring water in Tokyo, Japan.

    Science.gov (United States)

    Ishizaki, Naoto; Sogawa, Kazuyuki; Inoue, Hiroaki; Agata, Kunio; Edagawa, Akiko; Miyamoto, Hiroshi; Fukuyama, Masafumi; Furuhata, Katsunori

    2016-03-01

    Strain L-47(T) of a novel bacterial species belonging to the genus Legionella was isolated from a sample of hot spring water from Tokyo, Japan. The 16S rRNA gene sequences (1477 bp) of this strain (accession number AB899895) had less than 95.0% identity with other Legionella species. The dominant fatty acids of strain L-47(T) were a15:0 (29.6%) and the major ubiquinone was Q-12 (71.1%). It had a guanine-plus-cytosine content of 41.5 mol%. The taxonomic description of Legionella thermalis sp. nov. is proposed to be type strain L-47(T) (JCM 30970(T)  = KCTC 42799(T)). © 2016 The Societies and John Wiley & Sons Australia, Ltd.

  20. Characterization of Francisella species isolated from the cooling water of an air conditioning system.

    Science.gov (United States)

    Gu, Quan; Li, Xunde; Qu, Pinghua; Hou, Shuiping; Li, Juntao; Atwill, Edward R; Chen, Shouyi

    2015-01-01

    Strains of Francisella spp. were isolated from cooling water from an air conditioning system in Guangzhou, China. These strains are Gram negative, coccobacilli, non-motile, oxidase negative, catalase negative, esterase and lipid esterase positive. In addition, these bacteria grow on cysteine-supplemented media at 20 °C to 40 °C with an optimal growth temperature of 30 °C. Analysis of 16S rRNA gene sequences revealed that these strains belong to the genus Francisella. Biochemical tests and phylogenetic and BLAST analyses of 16S rRNA, rpoB and sdhA genes indicated that one strain was very similar to Francisella philomiragia and that the other strains were identical or highly similar to the Francisella guangzhouensis sp. nov. strain 08HL01032 we previously described. Biochemical and molecular characteristics of these strains demonstrated that multiple Francisella species exist in air conditioning systems.

  1. Neopetrosiquinones A and B, sesquiterpene benzoquinones isolated from the deep-water sponge Neopetrosia cf. proxima.

    Science.gov (United States)

    Winder, Priscilla L; Baker, Heather L; Linley, Patricia; Guzmán, Esther A; Pomponi, Shirley A; Diaz, M Cristina; Reed, John K; Wright, Amy E

    2011-11-15

    Two new marine-derived sesquiterpene benzoquinones which we designate as neopetrosiquinones A (1) and B (2), have been isolated from a deep-water sponge of the family Petrosiidae. The structures were elucidated on the basis of their spectroscopic data. Compounds 1 and 2 inhibit the in vitro proliferation of the DLD-1 human colorectal adenocarcinoma cell line with IC(50) values of 3.7 and 9.8 μM, respectively, and the PANC-1 human pancreatic carcinoma cell line with IC(50) values of 6.1 and 13.8 μM, respectively. Neopetrosiquinone A (1) also inhibited the in vitro proliferation of the AsPC-1 human pancreatic carcinoma cell line with an IC(50) value of 6.1 μM. The compounds are structurally related to alisiaquinone A, cyclozonarone, and xestoquinone. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. IncF Plasmids Are Commonly Carried by Antibiotic Resistant Escherichia coli Isolated from Drinking Water Sources in Northern Tanzania

    OpenAIRE

    Lyimo, Beatus; Buza, Joram; Subbiah, Murugan; Temba, Sylivester; Kipasika, Honest; Smith, Woutrina; Call, Douglas R.

    2016-01-01

    The aim of this study was to identify the replicon types of plasmids, conjugation efficiencies, and the complement of antibiotic resistance genes for a panel of multidrug resistant E. coli isolates from surface waters in northern Tanzania. Standard membrane filtration was used to isolate and uidA PCR was used to confirm the identity of strains as E. coli. Antibiotic susceptibility was determined by breakpoint assay and plasmid conjugation was determined by filter-mating experiments. PCR and s...

  3. A hot water extract of Curcuma longa inhibits adhesion molecule protein expression and monocyte adhesion to TNF-α-stimulated human endothelial cells.

    Science.gov (United States)

    Kawasaki, Kengo; Muroyama, Koutarou; Yamamoto, Norio; Murosaki, Shinji

    2015-01-01

    The recruitment of arterial leukocytes to endothelial cells is an important step in the progression of various inflammatory diseases. Therefore, its modulation is thought to be a prospective target for the prevention or treatment of such diseases. Adhesion molecules on endothelial cells are induced by proinflammatory cytokines, including tumor necrosis factor-α (TNF-α), and contribute to the recruitment of leukocytes. In the present study, we investigated the effect of hot water extract of Curcuma longa (WEC) on the protein expression of adhesion molecules, monocyte adhesion induced by TNF-α in human umbilical vascular endothelial cells (HUVECs). Treatment of HUVECs with WEC significantly suppressed both TNF-α-induced protein expression of adhesion molecules and monocyte adhesion. WEC also suppressed phosphorylation and degradation of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) induced by TNF-α in HUVECs, suggesting that WEC inhibits the NF-κB signaling pathway.

  4. Comparative Analysis of Milled Wood Lignins (MWLs Isolated from Sugar Maple (SM and Hot-Water Extracted Sugar Maple (ESM

    Directory of Open Access Journals (Sweden)

    Mangesh J. Goundalkar

    2014-03-01

    Full Text Available To further elucidate the advantageous effects of hot-water extraction (HWE on delignification, milled wood lignin (MWL was isolated from sugar maple (SM and from hot-water extracted sugar maple (ESM. Ball-milled wood was analyzed for particle size distribution (PSD before and after dioxane:water (DW extraction. The MWL samples were analyzed by analytical and spectral methods. The results indicated that the MWL isolated from SM and ESM was mainly released from the middle lamella (ML and the secondary wall (SW, respectively. The cleavage of dibenzodioxocin (DB and spirodienone (SD lignin substructures during HWE is suggested. The removal of lignin during acetone:water (AW extraction of hot-water extracted wood indicates that including an additional operation in a hardwood HWE-based biorefinery would be beneficial for processing of wood.

  5. Optical coherent tomography measurements of the diffusion rate of water and drugs in an isolated and whole cornea

    International Nuclear Information System (INIS)

    Larin, Kirill V; Ghosn, M G

    2006-01-01

    The passive diffusion of drugs through the epithelial surfaces of an eye (the most widespread method for medical treatment of various diseases) is considered. The permeability of water and drugs through rabbit cornea was measured in the isolated cornea (separate from an eye) and in the whole cornea. The permeability coefficients of water and dexamethasone were estimated by the method of optical coherence tomography (OCT). Because multiple photon scattering introduces noise and distortions to the OCT signal, measurements were performed at depths up to 500 μm where most likely single scattering of light occurs in cornea. It is shown that the permeability coefficients in the isolated and whole cornea strongly differ from each other. For example, the water permeability in the isolated and whole cornea is (7.09±0.12)x10 -5 and (1.71±0.51)x10 -5 cm s -1 , respectively. (special issue devoted to multiple radiation scattering in random media)

  6. Identifying factors linked to the occurrence of alien gastropods in isolated woodland water bodies

    Science.gov (United States)

    Spyra, Aneta; Strzelec, Małgorzata

    2014-03-01

    Biological invasions are a significant component of human-caused global change and is widely regarded as one of the main threats to natural biodiversity. Isolated anthropogenic water bodies created in the areas that are deprived of natural freshwater habitats allow the survival and reproduction of alien species on newly settled sites. They are often small with water level fluctuations causing frequent environmental disturbances. The colonisation success may be the result of the rate of their degradation. The aims of the study were to determine the environmental conditions that affect the existence of alien species of gastropods in this type of aquatic environment and to examine whether the occurrence of non-native species affects the community structure of the native species. This study made it possible to group woodland ponds according to the occurrence of the three invasive species in snail communities and discuss the environmental conditions present in these pond types. Analysis of water properties emphasised the distinctiveness of the selected pond types. In ponds of the Potamopyrgus antipodarum type, we found the highest values of some parameters mainly hardness, conductivity, and content of calcium and chlorides, in contrast with the Physella acuta type, which were characterised by the lowest values except for phosphates and nitrites. In the Ferrissia fragilis type, we found the highest nitrate content. Data on the occurrence of alien species in different water environments play an important role in actions which are taken to prevent new invasions and spread of non-native species as well as to reduce future impacts of invaders.

  7. Action of an aerobic hydrogenotroph bacteria isolated from ultrapure water systems on AISI 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Gales, Gregoire [DTN/SMTM/LMTE, CEA Cadarache, F-13108 Saint-Paul-lez-Durance (France)]|[DSV/DEVM/LEMIR, UMR 6191 CNRS-CEA-Universite Aix-Marseille II, CEA Cadarache, F- 13108 Saint-Paul-lez-Durance (France); Roy, Marc; Feron, Damien [DEN/DPC/SCCME/LECA, Bat 458, CEA Saclay F- 91191 Gif sur Yvette (France); Libert, Marie-Francoise; Sellier, Regine [DTN/SMTM/LMTE, CEA Cadarache, F-13108 Saint-Paul-lez-Durance (France); Cournac, Laurent [DSV/DEVM/LEP, UMR 6191 CNRS-CEA-Universite Aix-Marseille II, CEA Cadarache, F- 13108 Saint-Paul-lez-Durance (France); Heulin, Thierry [DSV/DEVM/LEMIR, UMR 6191 CNRS-CEA-Universite Aix-Marseille II, CEA Cadarache, F- 13108 Saint-Paul-lez-Durance (France)

    2004-07-01

    Several microbial studies have been recently performed in nuclear power stations. These studies concerned essentially the formation of bio-films on submerged metal coupons. Heterotrophic micro-organisms have been found in bulk water of nuclear fuel storage basins but the in situ nutrient sources for bacterial development in such highly oligo-trophic water was unknown. In nuclear environments, radiations lead to the production of molecular hydrogen, hydrogen peroxide and some radicals (OH, O{sub 2}{sup -}) by radiolysis of water or embedding matrices. Bacterial oxidation of molecular H{sub 2} commonly occurs in nature, as molecular hydrogen represents a high-energy reductant. We investigated the microbiology of a ultra-pure water basin containing irradiating waste. The initial aim of this study was to determine if autotrophic bacterial growth was possible in this basin. A major bacteria was isolated (Ralstonia sp. GGLH002) which was able to grow autotrophically with hydrogen as the electron donor and oxygen as the electron acceptor, and heterotrophically with organic nutrients. Its hydrogenase activity has been characterized. We focused then our study on the effects of this strain on 304L AISI stainless steel depending on the nutrient source used for bacterial development, e.g hydrogen or organics. In conclusion, the mechanism of passivation enhanced by Ralstonia sp. GGLH002 on AISI 304L SS still remains unknown. Several techniques could give substantial information, including XPS and polarization curves. It seems for the moment that the major bacteria inhabiting an oxic environment containing hydrogen due to radiolysis is not aggressive to stainless steel in conditions near from its environment. Further investigations are needed to test this hypothesis, including a study of the molecular diversity of the bacteria using culture-independent techniques, as cultivatable bacterial populations represent in general only a fraction of the total bacteria. (authors)

  8. Action of an aerobic hydrogenotroph bacteria isolated from ultrapure water systems on AISI 304 stainless steel

    International Nuclear Information System (INIS)

    Gales, Gregoire; Roy, Marc; Feron, Damien; Libert, Marie-Francoise; Sellier, Regine; Cournac, Laurent; Heulin, Thierry

    2004-01-01

    Several microbial studies have been recently performed in nuclear power stations. These studies concerned essentially the formation of bio-films on submerged metal coupons. Heterotrophic micro-organisms have been found in bulk water of nuclear fuel storage basins but the in situ nutrient sources for bacterial development in such highly oligo-trophic water was unknown. In nuclear environments, radiations lead to the production of molecular hydrogen, hydrogen peroxide and some radicals (OH, O 2 - ) by radiolysis of water or embedding matrices. Bacterial oxidation of molecular H 2 commonly occurs in nature, as molecular hydrogen represents a high-energy reductant. We investigated the microbiology of a ultra-pure water basin containing irradiating waste. The initial aim of this study was to determine if autotrophic bacterial growth was possible in this basin. A major bacteria was isolated (Ralstonia sp. GGLH002) which was able to grow autotrophically with hydrogen as the electron donor and oxygen as the electron acceptor, and heterotrophically with organic nutrients. Its hydrogenase activity has been characterized. We focused then our study on the effects of this strain on 304L AISI stainless steel depending on the nutrient source used for bacterial development, e.g hydrogen or organics. In conclusion, the mechanism of passivation enhanced by Ralstonia sp. GGLH002 on AISI 304L SS still remains unknown. Several techniques could give substantial information, including XPS and polarization curves. It seems for the moment that the major bacteria inhabiting an oxic environment containing hydrogen due to radiolysis is not aggressive to stainless steel in conditions near from its environment. Further investigations are needed to test this hypothesis, including a study of the molecular diversity of the bacteria using culture-independent techniques, as cultivatable bacterial populations represent in general only a fraction of the total bacteria. (authors)

  9. Prevalence and Antibiogram Profiling of Escherichia coli Pathotypes Isolated from the Kat River and the Fort Beaufort Abstraction Water

    Science.gov (United States)

    Nontongana, Nolonwabo; Sibanda, Timothy; Ngwenya, Elvis; Okoh, Anthony I.

    2014-01-01

    Escherichia coli is a widespread bacterium encompassing a variety of strains, ranging from highly pathogenic strains, causing worldwide outbreaks of severe diseases to avirulent, well characterized safe laboratory strains. This study evaluated the prevalence and antibiogram profiles of E. coli pathotypes isolated from the Kat River and Fort Beaufort abstraction water. A total of 171 out of 278 confirmed E. coli isolates were positive for at least one pathogenic determinant and these included enteropathogenic E. coli (6%), enterotoxigenic E. coli (47%), uropathogenic E. coli (2%), neonatal meningitis E. coli (5%), diffusely adherent E. coli (1%) and enterohaemorrhagic E. coli (1%). Interestingly, enteroinvasive and enteroaggregative E. coli were not detected. The phenotypic antibiogram profiles of the isolates revealed that all were resistant to penicillin G, while 98% and 38% of the pathotypes were resistant to ampicillin and trimethoprim-sulphamethoxazole, respectively. About 8% of the isolates were resistant to streptomycin. More than half of the isolates exhibited multiple antibiotic resistance with 44% being resistant to three antibiotics and 8% resistant to four antibiotics. We conclude that the Kat River is a reservoir of potentially virulent antibiotic resistant E. coli strains that can cause serious health risks to humans who drink raw water from this river, or in the case that consumption of treated drinking water coincides with failed drinking water processes. PMID:25119699

  10. Prevalence and Antibiogram Profiling of Escherichia coli Pathotypes Isolated from the Kat River and the Fort Beaufort Abstraction Water

    Directory of Open Access Journals (Sweden)

    Nolonwabo Nontongana

    2014-08-01

    Full Text Available Escherichia coli is a widespread bacterium encompassing a variety of strains, ranging from highly pathogenic strains, causing worldwide outbreaks of severe diseases to avirulent, well characterized safe laboratory strains. This study evaluated the prevalence and antibiogram profiles of E. coli pathotypes isolated from the Kat River and Fort Beaufort abstraction water. A total of 171 out of 278 confirmed E. coli isolates were positive for at least one pathogenic determinant and these included enteropathogenic E. coli (6%, enterotoxigenic E. coli (47%, uropathogenic E. coli (2%, neonatal meningitis E. coli (5%, diffusely adherent E. coli (1% and enterohaemorrhagic E. coli (1%. Interestingly, enteroinvasive and enteroaggregative E. coli were not detected. The phenotypic antibiogram profiles of the isolates revealed that all were resistant to penicillin G, while 98% and 38% of the pathotypes were resistant to ampicillin and trimethoprim-sulphamethoxazole, respectively. About 8% of the isolates were resistant to streptomycin. More than half of the isolates exhibited multiple antibiotic resistance with 44% being resistant to three antibiotics and 8% resistant to four antibiotics. We conclude that the Kat River is a reservoir of potentially virulent antibiotic resistant E. coli strains that can cause serious health risks to humans who drink raw water from this river, or in the case that consumption of treated drinking water coincides with failed drinking water processes.

  11. Molecule nanoweaver

    Science.gov (United States)

    Gerald, II; Rex, E [Brookfield, IL; Klingler, Robert J [Glenview, IL; Rathke, Jerome W [Homer Glen, IL; Diaz, Rocio [Chicago, IL; Vukovic, Lela [Westchester, IL

    2009-03-10

    A method, apparatus, and system for constructing uniform macroscopic films with tailored geometric assemblies of molecules on the nanometer scale. The method, apparatus, and system include providing starting molecules of selected character, applying one or more force fields to the molecules to cause them to order and condense with NMR spectra and images being used to monitor progress in creating the desired geometrical assembly and functionality of molecules that comprise the films.

  12. Removal Capacities of Polycyclic Aromatic Hydrocarbons (PAHs by a Newly Isolated Strain from Oilfield Produced Water

    Directory of Open Access Journals (Sweden)

    Yi-Bin Qi

    2017-02-01

    Full Text Available The polycyclic aromatic hydrocarbon (PAH-degrading strain Q8 was isolated from oilfield produced water. According to the analysis of a biochemical test, 16S rRNA gene, house-keeping genes and DNA–DNA hybridization, strain Q8 was assigned to a novel species of the genus Gordonia. The strain could not only grow in mineral salt medium (MM and utilize naphthalene and pyrene as its sole carbon source, but also degraded mixed naphthalene, phenanthrene, anthracene and pyrene. The degradation ratio of these four PAHs reached 100%, 95.4%, 73.8% and 53.4% respectively after being degraded by Q8 for seven days. A comparative experiment found that the PAHs degradation efficiency of Q8 is higher than that of Gordonia alkaliphila and Gordonia paraffinivorans, which have the capacities to remove PAHs. Fourier transform infrared spectra, saturate, aromatic, resin and asphaltene (SARA and gas chromatography–mass spectrometry (GC–MS analysis of crude oil degraded by Q8 were also studied. The results showed that Q8 could utilize n-alkanes and PAHs in crude oil. The relative proportions of the naphthalene series, phenanthrene series, thiophene series, fluorene series, chrysene series, C21-triaromatic steroid, pyrene, and benz(apyrene were reduced after being degraded by Q8. Gordonia sp. nov. Q8 had the capacity to remediate water and soil environments contaminated by PAHs or crude oil, and provided a feasible way for the bioremediation of PAHs and oil pollution.

  13. Notice of intent to discharge water contaminants. Waste Isolation Pilot Plant, Eddy County, NM

    International Nuclear Information System (INIS)

    Hart, J.S.; Porter, K.R.; Register, J.K.

    1983-04-01

    This report provides information in support of a ''Notice of Intent to Discharge Water Contaminants,'' pursuant to Section 1-201 of the New Mexico Water Quality Control Commission Regulations. The anticipated discharges are not expected to move directly or indirectly into groundwater. These discharges will be caused by activities related to the construction of the Waste Isolation Pilot Plant (WIPP), a US Department of Energy (DOE) research and development program to demonstrate the safe disposal of radioactive wastes resulting from defense activities and programs of the United States. The facility is to be developed in deep layers of bedded salt. The WIPP site is located in Eddy County, New Mexico, about 26 miles east of Carlsbad. The US Department of Energy, WIPP Project Office, Albuquerque, New Mexico, as the sponsor of the project, is responsible for any discharges from the site. The following sections describe generally the WIPP construction activities. Pertinent site conditions, potential sources of discharges and their expected effects, and proposed groundwater monitoring efforts are also described

  14. Preferential feeding in Naegleria fowleri; intracellular bacteria isolated from amoebae in operational drinking water distribution systems.

    Science.gov (United States)

    Miller, Haylea C; Morgan, Matthew J; Walsh, Tom; Wylie, Jason T; Kaksonen, Anna H; Puzon, Geoffrey J

    2018-05-06

    The amoeba Naegleria fowleri is the causative agent of the highly fatal disease, primary amoebic meningoencephalitis, and estimated to cause 16 deaths per year in the United States alone. Colonisation of drinking water distribution systems (DWDSs) by the N. fowleri is a significant public health issue. Understanding the factors which enable this pathogen to colonise and thrive in DWDSs is critical for proper management. The microbial ecology within DWDSs may influence the ability of N. fowleri to colonise DWDSs by facilitating the availability of an appropriate food source. Using biofilm samples obtained from operational DWDSs, 16S rRNA amplicon metabarcoding was combined with genus-specific PCR and Sanger sequencing of intracellular associated bacteria from isolated amoeba and their parental biofilms to identify Meiothermus chliarophilus as a potential food source for N. fowleri. Meiothermus was confirmed as a food source for N. fowleri following successful serial culturing of axenic N. fowleri with M. chliarophilus or M. ruber as the sole food source. The ability to identify environmental and ecological conditions favourable to N. fowleri colonisation, including the detection of appropriate food sources such as Meiothermus, could provide water utilities with a predictive tool for managing N. fowleri colonisation within the DWDS. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Mineralization of a Malaysian crude oil by Pseudomonas sp. and Achromabacter sp. isolated from coastal waters

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, J.; Ahmad, M.F.

    1995-12-31

    Regarded as being a potentially effective tool to combat oil pollution, bioremediation involves mineralization, i.e., the conversion of complex hydrocarbons into harmless CO{sub 2} and water by action of microorganisms. Therefore, in achieving optimum effectiveness from the application of these products on crude oil in local environments, the capability of the bacteria to mineralize hydrocarbons was evaluated. The microbial laboratory testing of mineralization on local oil degraders involved, first, isolation of bacteria found at a port located on the west coast of Peninsular Malaysia. Subsequently, these bacteria were identified by means of Biomereux`s API 20E and 20 NE systems and later screened by their growth on a Malaysian crude oil. Selected strains of Pseudomonas sp. and Achromabacter sp. were then exposed individually to a similar crude oil in a mineralization unit and monitored for 16 days for release of CO{sub 2}. Pseudomonas paucimobilis was found to produce more CO{sub 2} than Achromobacter sp. When tested under similar conditions, mixed populations of these two taxa produced more CO{sub 2} than that produced by any individual strain. Effective bioremediation of local crude in Malaysian waters can therefore be achieved from biochemically developed Pseudomonas sp. strains.

  16. The effect of water molecules on the thiol collector interaction on the galena (PbS) and sphalerite (ZnS) surfaces: A DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Long, Xianhao [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Chen, Ye, E-mail: fby18@126.com [College of Resources and Metallurgy, Guangxi University, Nanning 530004 (China); Chen, Jianhua, E-mail: jhchen@gxu.edu.cn [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); College of Resources and Metallurgy, Guangxi University, Nanning 530004 (China); Xu, Zhenghe; Liu, Qingxia [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 2V4 (Canada); Du, Zheng [National Supercomputing Center in Shenzhen, Shenzhen 518055 (China)

    2016-12-15

    Highlights: • Water adsorption has a greater effect on the electron distribution of ZnS surface than PbS surface. • Water adsorption decreases the reactivity of ZnS surface atoms but improves that of PbS. • Thiol collectors cannot interact with the hydrated ZnS surface. • The hydration has little influence on the interaction of thiol collectors with PbS surface. - Abstracts: In froth flotation the molecular interaction between reagents and mineral surfaces take place at the solid liquid interface. In this paper, the effect of water molecule on the three typical thiol collectors (xanthate, dithiocarbomate and dithiophosphate) interactions at the galena (PbS) and sphalerite (ZnS) surfaces has been studied adopting density functional theory (DFT). The results suggests that the presence of water molecule shows a greater influence on the electron distribution of ZnS surface than PbS surface, and reduce the reactivity of ZnS surface atoms but improves the reactivity of PbS surface atoms during the reaction with xanthate. Water adsorption could also reduce the covalent binding between Zn and S atoms but have little influence on Pb-S bond. In the presence of water, xanthate, dithiocarbomate (DTC) and dithiophosphate (DTP) could not adsorb on the sphalerite surface. And for galena (PbS) surface, the interaction of DTP is the strongest, then the DTC and the interaction of xanthate is the weakest. These results agree well with the flotation practice.

  17. Biofilm forming ability of Sphingomonas paucimobilis isolated from community drinking water systems on plumbing materials used in water distribution.

    Science.gov (United States)

    Gulati, Parul; Ghosh, Moushumi

    2017-10-01

    Sphingomonas paucimobilis, an oligotroph, is well recognized for its potential for biofilm formation. The present study explored the biofilm forming ability of a strain isolated from municipal drinking water on plumbing materials. The intensity of biofilm formation of this strain on different plumbing materials was examined by using 1 × 1 cm 2 pieces of six different pipe materials, i.e. polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), aluminium (Al), copper (Cu) and rubber (R) and observing by staining with the chemical chromophore, Calcofluor. To understand whether biofilm formation occurs under flow through conditions, a laboratory-scale simulated distribution system, comprised of the above materials was fabricated. Biofilm samples were collected from the designed system at different biofilm ages (10, 40 and 90 hours old) and enumerated. The results indicated that the biofilm formation occurred on all plumbing materials with Cu and R as exceptions. The intensity of biofilm formation was found to be maximum on PVC followed by PP and PE. We also demonstrated the chemical chromophore (Calcofluor) successfully for rapid and easy visual detection of biofilms, validated by scanning electron microscope (SEM) analysis of the plumbing materials. Chlorination has little effect in preventing biofilm development.

  18. The Comparative Study of the Effects of Extremely Low Frequency Electromagnetic Fields and Infrasound on Water Molecule Dissociation and Generation of Reactive Oxygen Species

    Science.gov (United States)

    2008-11-01

    ISTC Project No. #1592P The Comparative Study of The Effects of Extremely Low Frequency Electromagnetic Fields and Infrasound on Water Molecule...performed under the agreement with the International Science and Technology Center ( ISTC ), Moscow. REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704...dissociation and generation of reactive oxygen spaces. 5a. CONTRACT NUMBER ISTC Registration No: A-1592p 5b. GRANT NUMBER 5c. PROGRAM ELEMENT

  19. Site-specific binding of a water molecule to the sulfa drugs sulfamethoxazole and sulfisoxazole: a laser-desorption isomer-specific UV and IR study.

    Science.gov (United States)

    Uhlemann, Thomas; Seidel, Sebastian; Müller, Christian W

    2018-03-07

    To determine the preferred water molecule binding sites of the polybasic sulfa drugs sulfamethoxazole (SMX) and sulfisoxazole (SIX), we have studied their monomers and monohydrated complexes through laser-desorption conformer-specific UV and IR spectroscopy. Both the SMX and SIX monomer adopt a single conformer in the molecular beam. On the basis of their conformer-specific IR spectra in the NH stretch region, these conformers were assigned to the SMX and SIX global minimum structures, both exhibiting a staggered sulfonamide group and an intramolecular C-HO[double bond, length as m-dash]S hydrogen bond. The SMX-H 2 O and SIX-H 2 O complexes each adopt a single isomer in the molecular beam. Their isomeric structures were determined based on their isomer-specific IR spectra in the NH/OH stretch region. Quantum Theory of Atoms in Molecules analysis of the calculated electron densities revealed that in the SMX-H 2 O complex the water molecule donates an O-HN hydrogen bond to the heterocycle nitrogen atom and accepts an N-HO hydrogen bond from the sulfonamide NH group. In the SIX-H 2 O complex, however, the water molecule does not bind to the heterocycle but instead donates an O-HO[double bond, length as m-dash]S hydrogen bond to the sulfonamide group and accepts an N-HO hydrogen bond from the sulfonamide NH group. Both water complexes are additionally stabilized by a C ph -HOH 2 hydrogen bond. Interacting Quantum Atoms analysis suggests that all intermolecular hydrogen bonds are dominated by the short-range exchange-correlation contribution.

  20. Biochemical characteristics, serogroups, and virulence factors of aeromonas species isolated from cases of diarrhoea and domestic water samples in Chennai

    Directory of Open Access Journals (Sweden)

    Alavandi S

    2003-01-01

    Full Text Available PURPOSE: The objective of the present study was to delineate the differences between the clinical and environmental Aeromonas species with respect to their biochemical characteristics, serogrouping and virulence factors, in order to find a phenotypic marker of enteropathogenicity. METHODS: A total of 55 Aeromonas spp. inclusive of 19 isolates from cases of diarrhoea, and 36 from water samples comprising, 10 isolates of A. hydrophila, 21 isolates each of A. sobria, and A. caviae, two isolates of A. jandaei and one isolate of A. veronii were subjected to analysis of their biochemical characteristics, serogrouping, and virulence factors. RESULTS: Among the differences recorded in the biochemical characteristics in the three major species, the most striking characteristic was fermentation of lactose, which was observed in all the 11 A. caviae isolates recovered from water samples. None of the 10 clinical isolates of A. caviae tested fermented lactose. The clinical Aeromonas isolates belonged to seven typable serogroups, O:13, O:14, O:16, O:21, O:27, O:32 and O:35. The environmental isolates belonged to eight different serogroups, such as, O:3, O:11, O:14, O:16, O:18, O:28, O:64 and O:78 and were predominated by serotypes O:18 and O:64. Among the virulence factors tested, 89% of the environmental isolates produced b haemolysin, while only 62.3% of clinical isolates were able to do so. There was no significant difference between the clinical and environmental aeromonads with respect to their enterotoxigenicity in suckling mice in vivo, cytotoxicity in vitro in Vero cell monolayers, and ability to produce siderophores. CONCLUSION: Efforts to delineate the differences between the clinical and environmental Aeromonas spp. did not reveal significant difference between them. However, difference was observed with respect to their ability to produce b haemolysin, wherein, higher percentage of environmental isolates was haemolytic. The results also suggest

  1. Ice-nucleation negative fluorescent pseudomonads isolated from Hebridean cloud and rain water produce biosurfactants

    Science.gov (United States)

    Ahern, H. E.; Walsh, K. A.; Hill, T. C. J.; Moffett, B. F.

    2006-10-01

    Microorganisms were discovered in clouds over 100 years ago but information on bacterial community structure and function is limited. Clouds may not only be a niche within which bacteria could thrive but they might also influence dynamic processes using ice nucleating and cloud condensing abilities. Cloud and rain samples were collected from two mountains in the Outer Hebrides, NW Scotland, UK. Community composition was determined using a combination of amplified 16S ribosomal DNA restriction analysis and sequencing. 256 clones yielded 100 operational taxonomic units (OTUs) of which half were related to bacteria from terrestrial psychrophilic environments. Cloud samples were dominated by a mixture of fluorescent Pseudomonas spp., some of which have been reported to be ice nucleators. It was therefore possible that these bacteria were using the ice nucleation (IN) gene to trigger the Bergeron-Findeisen process of raindrop formation as a mechanism for dispersal. In this study the IN gene was not detected in any of the isolates using both polymerase chain reaction (PCR) and differential scanning calorimetry (DSC). Instead 55% of the total isolates from both cloud and rain samples displayed significant biosurfactant activity when analyzed using the drop-collapse technique. All were characterised as fluorescent pseudomonads. Surfactants have been found to be very important in lowering atmospheric critical supersaturations required for the activation of aerosols into cloud condensation nuclei (CCN). It is also known that surfactants influence cloud droplet size and increase cloud lifetime and albedo. Some bacteria are known to act as CCN and so it is conceivable that these fluorescent pseudomonads are using surfactants to facilitate their activation from aerosols into CCN. This would allow water scavenging, countering desiccation, and assist in their widespread dispersal.

  2. Nocardiopsis akesuensis sp. nov., an actinomycete isolated from a salt water beach.

    Science.gov (United States)

    Gao, Guang-Bin; Luo, Xiao-Xia; Xia, Zhan-Feng; Zhang, Yao; Wan, Chuan-Xing; Zhang, Li-Li

    2016-12-01

    The taxonomic position of a novel actinomycete, strain TRM 46250T, isolated from the sediment of a salt water beach at Baicheng, Xinjiang, China, was determined by a polyphasic approach. Strain TRM 46250T grew optimally in the presence of 2 % (w/v) NaCl and an optimum temperature range for growth of 28-37 °C. The whole-cell sugars of strain TRM 46250T were ribose, xylose, mannose and galactose. The diagnostic diamino acid was meso-diaminopimelic acid. The polar lipids were phosphatidylinositol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylmethyl ethanolamine and six unidentified phospholipids. The predominant menaquinones were MK-10, MK-10(H6) and MK-10(H8). The major fatty acids were 10-methyl C18 : 0, iso-C16 : 0, C16 : 0, iso-G C16 : 1 and C18 : 1ω9c. Based on morphological and chemotaxonomic characteristics the isolate was determined to belong to the genus Nocardiopsis. The phylogenetic tree based on its nearly complete 16S rRNA gene sequence (1493 nt) with those of representative strains showed that the strain consistently falls into a distinct phyletic line together with Nocardiopsis gilva YIM 90087T (97.68 % similarity) and a subclade consisting of Nocardiopsis composta KS9T (97.52 %), Nocardiopsis rosea YIM 90094T (97.44 %) and Nocardiopsis rhodophaea YIM 90096T (97.16 %). However, DNA-DNA hybridization studies between strain TRM 46250T and N. gilva YIM 90087T showed only 36.94 % relatedness. On the basis of these data, strain TRM 46250T should be designated as a representative of a novel species of the genus Nocardiopsis, for which the name Nocardiopsis akesuensis sp. nov. is proposed. The type strain is TRM 46250T (=CCTCC AA 2015027T=KCTC 39725T).

  3. The effect of isolation on reproduction and growth of Pseudosuccinea columella (Pulmonata: Lymnaeidae: a snail-conditioned water experiment

    Directory of Open Access Journals (Sweden)

    Gutiérrez Alfredo

    2002-01-01

    Full Text Available A snail-conditioned water experiment was conducted in Pseudosuccinea columella to test the possible role of a chemical interaction between snails on the diminished growth and fecundity rates found for snails raised in pairs compared to those raised in complete isolation. The results permit to discard the hypothesis of an inhibition of growth and reproduction between snails due to factors released into the water.

  4. Water adsorption on TiO2 surfaces probed by soft X-ray spectroscopies: bulk materials vs. isolated nanoparticles

    Science.gov (United States)

    Benkoula, Safia; Sublemontier, Olivier; Patanen, Minna; Nicolas, Christophe; Sirotti, Fausto; Naitabdi, Ahmed; Gaie-Levrel, François; Antonsson, Egill; Aureau, Damien; Ouf, François-Xavier; Wada, Shin-Ichi; Etcheberry, Arnaud; Ueda, Kiyoshi; Miron, Catalin

    2015-01-01

    We describe an experimental method to probe the adsorption of water at the surface of isolated, substrate-free TiO2 nanoparticles (NPs) based on soft X-ray spectroscopy in the gas phase using synchrotron radiation. To understand the interfacial properties between water and TiO2 surface, a water shell was adsorbed at the surface of TiO2 NPs. We used two different ways to control the hydration level of the NPs: in the first scheme, initially solvated NPs were dried and in the second one, dry NPs generated thanks to a commercial aerosol generator were exposed to water vapor. XPS was used to identify the signature of the water layer shell on the surface of the free TiO2 NPs and made it possible to follow the evolution of their hydration state. The results obtained allow the establishment of a qualitative determination of isolated NPs’ surface states, as well as to unravel water adsorption mechanisms. This method appears to be a unique approach to investigate the interface between an isolated nano-object and a solvent over-layer, paving the way towards new investigation methods in heterogeneous catalysis on nanomaterials. PMID:26462615

  5. Albirhodobacter marinus gen. nov., sp. nov., a member of the family Rhodobacteraceae isolated from sea shore water of Visakhapatnam, India

    Digital Repository Service at National Institute of Oceanography (India)

    Nupur; Bhumika, V.; Srinivas, T.N.R.; AnilKumar, P.

    A novel marine, Gram-negative, rod-shaped bacterium, designated strain N9 sup(T), was isolated from a water sample of the sea shore at Visakhapatnam, Andhra Pradesh (India). Strain N9 sup(T) was found to be positive for oxidase and catalase...

  6. Citreicella manganoxidans sp. nov., a novel manganese oxidizing bacterium isolated from a shallow water hydrothermal vent in Espalamaca (Azores)

    Digital Repository Service at National Institute of Oceanography (India)

    Rajasabapathy, R.; Mohandass, C; Dastager, S.G.; Liu, Q.; Li, W.-J; Colaco, A.

    A Gram-stain negative, non-motile, non-spore forming, aerobic and rod or narrow lemon-shaped bacterial strain, VSW210T, was isolated from surface seawater in a shallow water hydrothermal vent region in Espalamaca (Azores). Strain VSW210...

  7. Aliiglaciecola coringensis sp. nov., isolated from a water sample collected from mangrove forest in Coringa, Andhra Pradesh, India

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, V.; Sharma, G.; Srinivas, T.N.R.; AnilKumar, P.

    A Gram-negative, rod shaped, motile, aerobic bacterium, designated as strain AK49(T) was isolated from a water sample from a mangrove forest in Coringa village, Andhra Pradesh, India. Strain AK49(T) was observed to form yellow coloured, smooth...

  8. Isolation of Bacillus subtilis as indicator in the disinfection of residual water by means of gamma radiation

    International Nuclear Information System (INIS)

    Mata J, M.; Colin C, A.; Lopez V, H.; Brena V, M.; Carrasco A, H.; Pavon R, S.

    2002-01-01

    In the attempt to get more alternatives of disinfection of residual water, the Bacillus subtilis was isolated by means of gamma radiation as a bio indicator of disinfection since it turned out to be resistant to the 5 KGy dose, comparing this one with other usual microorganisms as biondicators like E. coli and S typhimurium which turn out more sensitive to such dose. (Author)

  9. Peculiarities of S.Typhi isolation from the river water polluted with radionuclides at different times of the year

    Energy Technology Data Exchange (ETDEWEB)

    Toichuev, R. M. [Institute of Medical Problems of the Southern Branch, Osh(Kyrgyzstan)

    2012-09-15

    Full text:Objective: to assess the effect of radionuclide pollution of river water on the isolation rate of S. Tuphi at different times of the year. Materials and methods: Since the number of typhoid fever cases reported in the Mayluusuu Valley (23 tailing pits and 16 tailing dumps are located in the area) tends to increase after the mudslides we collected river water specimens considering all these factors. Water specimens were collected from the Mayluusuu River, Shaidan-sai River, Kara-Unkur River and Ak-Buura River. Bacterial inoculation was performed in accordance with standard procedures. Concentration levels of pesticides (DDT, DDE, DDD, GCCG {alpha}, {beta}, {gamma} Aldrin and Dieldrin) were measured with a spectrograph. The present work was done in the framework of the ISTC Project KR-1516. Results and discussion: Out of the total of 2360 water specimens collected from the Shaidan-Sai River, S. Typhi was isolated from one (0.04%) water specimen. No cases of S. Typhi isolation from the water specimens collected from the Kara-Unkur River were reported for the past 10 years. Out of the total of 8969 water specimens collected from the Ak-Buura River, isolation of S. Typhi was reported in 4 (0.044%) cases. Starting from 2006 typhoid fever cases have been reported in the winter and spring times among the residents of the Mayluusuu Valley. A total of 1200 patients with a presumptive diagnosis of typhoid fever were admitted to the hospitals during the period. S. Typhi was isolated from 2 out of the total of 51 (3.9%) water specimens collected from the Mayluusuu River in the winter time, 4 (2.4%) out of the total 164 - in the spring time, 3.4% and 4.5% in the summer and autumn, respectively. Concentration levels of thorium (Th) and uranium (U) were 0.025-0.045 mg/l and 0.35-15.0 mg/l. No traces of the pesticides were found in water specimens. DDE at concentration of 0.024 mg/l and GCCG {alpha} (0.06 mg/l) were found in silt specimens collected downstream the Ak

  10. Electronic Spectroscopy of B Atoms and B2 Molecules Isolated in Para-H2, Normal-D2, Ne, Ar, Kr, and Xe Matrices

    National Research Council Canada - National Science Library

    Tam, Simon

    2000-01-01

    ...), Ne, Ar, Kr, and Xe matrices, and of B2 molecules in Ne, Ar, Kr, and Xe matrices. The 2s(sup 2)3s((sup 2)S) left arrow 2s(sup 2)2p((sup 2)P) B atom Rydberg absorption suffers large gas-to-matrix blue shifts, increasing...

  11. Evolution of trimethylarsine by a Penicillium sp. isolated from agricultural evaporation pond water.

    Science.gov (United States)

    Huysmans, K D; Frankenberger, W T

    1991-06-01

    Arsenicals are used in agriculture as pesticides and defoliants. In the Central Valley of California, arsenic is present in soil at naturally high concentrations, being derived from marine sedimentary parent material of the Coastal Range. Due to intense agricultural irrigation, soluble arsenic is leached from the soil and accumulates in evaporation ponds where it may pose an environmental threat to the waterfowl and wildlife. A Penicillium sp. isolated from evaporation pond water was found to be capable of methylating and subsequently volatilizing organic arsenic. The major focus of this study was to characterize the environmental conditions, including culture media, arsenic substrates, pH, temperature, and the presence of phosphates, carbohydrates and amino acids on the methylation of arsenic. Trimethylarsine was monitored by gas chromatography (GC)-flame ionization detection and identified by GC-mass spectrometry. The conditions or additions for optimum trimethylarsine production were: a minimal medium in which 100 mgl-1 methylarsonic acid served as the arsenic source, pH 5-6, temperature of incubation 20 degrees C, and phosphate concentration of 0.1-50 mM (KH2PO4). The addition of carbohydrates and sugar acids to the minimal medium suppressed trimethylarsine production. The amino acids phenylalanine, isoleucine, and glutamine promoted trimethylarsine production with an enhancement ranging from 10.2- to 11.6-fold over the control without amino acid supplementation. The information obtained from this study may be useful in developing a bioremediation approach in trapping the arsenic gas evolved from soil or water as a mitigation alternative in the cleanup of arsenic contamination.

  12. Optimization of biosurfactant production from Vibrio sp. BSM-30 isolated in tropical waters

    Science.gov (United States)

    Su, Zengjian; Li, Min; Zhang, Yuxiu

    2017-01-01

    The strain BSM-30 (Vibrio sp.), isolated from Chinese tropical waters, could be a biosurfactant producing bacteria according with results obtained by the oil spreading method. The culture conditions for biosurfactant production were tested respectively such as inoculation (2%,6%,10%,14% as setting), shaking speed(120 r/min,150 r/min,180 r/min as setting), temperature (25°C,30°C,35°C as setting), pH (7,8,9 as setting), salinity (1.5%, 2.5%, 3.0%, 4.5%, 5.5% as setting), which results showed that the best culture conditions for BS production were 10% inoculation quantity, 180 r/min, 25°C, pH 8, and 3.5% salinity. The optimization of carbon sources (20g/ of glucose, 20g/L of starch, 20g/L of paraffin oil 20g/L of diesel, 20g/L of oil as setting) and nitrogen sources (6g/L of NaNO3,7.1g/L of KNO3,5.6g/L of NH4NO3,9.3g/L of (NH4)2SO4, 4.2g/L of CO(NH2)2 as setting) were also tested, which results showed that the best nitrogen source and carbon source were (NH4) 2SO4 and soluble starch.

  13. Infrared spectroscopy of water clusters isolated in methane matrices: Effects of isotope substitution and annealing

    International Nuclear Information System (INIS)

    Yamakawa, Koichiro; Ehara, Namika; Ozawa, Nozomi; Arakawa, Ichiro

    2016-01-01

    Using infrared-active solvents of CH_4 and CD_4 for matrix isolation, we measured infrared spectra of H_2O and D_2O clusters at 7 K. The solute-concentration dependence of the spectrum of H_2O clusters in a CH_4 matrix was investigated and was used for the peak assignment. Annealing procedures were found to promote the size growth of water clusters in methane matrices for all the combinations of (H_2O, CH_4), (H_2O, CD_4), (D_2O, CH_4), and (D_2O, CD_4). We also monitored the ν_3 absorption due to methane to find the annealing-induced structural change only of solid CH_4. The matrix effects on the vibrations of the clusters are discussed on the basis of “T_c plots”, where their frequencies are plotted as a function of the square root of the matrix critical temperature, T_c. The obtained plots assure the validity of the assignment of the cluster peaks.

  14. Characterization of dextransucrase from Leuconostoc mesenteroides T3, water kefir grains isolate

    Directory of Open Access Journals (Sweden)

    Miljković Miona G.

    2017-01-01

    Full Text Available The production of dextransucrase (DS by Leuconostoc mesenteroides T3, novel isolate from water kefir grain, was studied and optimized. Bacterial supernatant reached activity of 3.1 U/ml when the culture was grown at 23 C and under static culture condition using classical Tsuchiya medium for DS production. The increase of sucrose concentration to 7% led to an increase of DS activity by 52% compared to the control. Medium with 2% beef extract and 1% yeast extract resulted in 4.52 U/ml, which was 47% higher than in the control (with 2% yeast extract. Finally, the increase of K2HPO4 concentration from 2 to 3% resulted in the increased enzyme activity by 28%. Enzyme purified by polyethylene glycol 400 fractionation displayed maximum activity at 30°C and pH 5.4. Zymogram analysis confirmed the presence of DS of approximately 180 kDa. The addition of divalent cations Ca2+, Mg2+, Fe2+ and Co2+ led to a minor increase of DS activity, while the addition of Mn2+ was the most prominent with 73% increase. These findings classify dextransucrase from Leuconostoc mesenteroides T3 as promising candidate for production of dextran, which has numerous applications in various industries. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR 31035

  15. A support system for water system isolation task in NPP by using augmented reality and RFID

    Energy Technology Data Exchange (ETDEWEB)

    Shimoda, Hiroshi; Ishii, Hirotake; Yamazaki, Yuichiro [Kyoto Univ., Uji (Japan). Graduate School of Energy Science; Wu, Wei [Mitsubishi Electric Corp., Amagasaki, Hyogo (Japan); Yoshikawa, Hidekazu [Kyoto Univ., Kyoto (Japan). Graduate School of Energy Science

    2004-07-01

    Aiming at improvement of task performance and reduction of human error of water system isolation task in NPP periodic maintenance, a support system using state-of-art information technology, Augmented Reality (AR) and Radio Frequency Identification (RFID) has been proposed, and a prototype system has been developed. The system has navigation function of which an indication is superimposed directly on the user's view to help to find the designated valves by AR. It also has valve confirmation function by scanning RFID tag attached on the valve. In case of applying it to practical use, its information presentation device is important because it affects the task performance. In this study, therefore, a suitable information presentation device has been pursued by conducting subject experiments employing psychological experimental technique. The candidates of the devices are one-eye video see-through HMD (SCOPO) and both-eye video see-through HMD (Glasstron) as wearable system configuration, and tablet PC and compact TV as handheld system configuration. In the experiment, task completion time, number of errors, NASA-TLX score as subjects' mental workload and subjective usability questionnaire were measured when using the above devices. As the results, it was found that one-eye video see-through head mounted display, SCOPO was suitable device as wearable system configuration, and compact TV was suitable device as handheld system configuration. (author)

  16. Description of Alteromonas abrolhosensis sp. nov., isolated from sea water of Abrolhos Bank, Brazil.

    Science.gov (United States)

    Nóbrega, Maria S; Silva, Bruno S; Leomil, Luciana; Tschoeke, Diogo Antonio; Campeão, Mariana E; Garcia, Gizele D; Dias, Graciela A; Vieira, Verônica V; Thompson, Cristiane C; Thompson, Fabiano L

    2018-01-18

    Two Gram-negative, motile, aerobic bacteria isolated from waters of the Abrolhos Bank were classified through a whole genome-based taxonomy. Strains PEL67E T and PEL68C shared 99% 16S rRNA and dnaK sequence identity with Alteromonas marina SW-47 T and Alteromonas macleodii ATCC 27126 T . In silico DNA-DNA Hybridization, i.e. genome-to-genome distance (GGD), average amino acid identity (AAI) and average nucleotide identity (ANI) showed that PEL67E T and PEL68C had identity values between 33-36, 86-88 and 83-84%, and 85-86 and 83%, respectively, towards their close neighbors A. macleodii ATCC 27126 T and A. marina SW-47 T . The DNA G + C contents of PEL67E T and PEL68C were 44.5%. The phenotypic features that differentiate PEL67E T and PEL68C strains from their close neighbors were assimilation of galactose and activity of phosphatase, and lack of mannitol, maltose, acetate, xylose and glycerol assimilation and lack of lipase, α and β-glucosidase activity. The new species Alteromonas abrolhosensis is proposed. The type strain is PEL67E T (= CBAS 610 T  = CAIM 1925 T ).

  17. Tsukamurella spongiae sp. nov., a novel actinomycete isolated from a deep-water marine sponge.

    Science.gov (United States)

    Olson, Julie B; Harmody, Dedra K; Bej, Asim K; McCarthy, Peter J

    2007-07-01

    A Gram-positive, rod-shaped, non-spore-forming bacterium (strain K362(T)) was isolated from a deep-water marine sponge collected off the coast of Curaçao in the Netherlands Antilles. On the basis of 16S rRNA gene sequence similarities, strain K362(T) was shown to belong to the genus Tsukamurella, being most closely related to Tsukamurella pulmonis (99.2 %), Tsukamurella tyrosinosolvens (98.9 %), Tsukamurella strandjordii (98.8 %), Tsukamurella pseudospumae (98.8 %) and Tsukamurella spumae (98.8 %). A combination of the substrate utilization patterns, the fatty acid and mycolic acid profiles and the DNA-DNA hybridization results supported the affiliation of strain K362(T) to the genus Tsukamurella and enabled the genotypic and phenotypic differentiation of strain K362(T) from the seven recognized Tsukamurella species. Strain K362(T) therefore represents a novel species of the genus Tsukamurella, for which the name Tsukamurella spongiae sp. nov. is proposed. The type strain is K362(T) (=DSM 44990(T)=NRRL B-24467(T)).

  18. Mycobacterium aquaticum sp. nov., a rapidly growing species isolated from haemodialysis water.

    Science.gov (United States)

    Hashemi Shahraki, Abdolrazagh; Trovato, Alberto; Droz, Sara; Haidarieh, Parvin; Borroni, Emanuele; Mirsaeidi, Mehdi; Mannino, Roberta; Hashemzadeh, Mohamad; Mariottini, Alessandro; Cirillo, Daniela Maria; Tortoli, Enrico

    2017-09-01

    The characterization of five Iranian isolates, four from hospital haemodialysis water and one from the sputum of a patient, led to the detection of a novel mycobacterium species. The strains were characterized by mucoid colonies developing in 3-5 days at temperatures ranging from 25 to 37 °C. The biochemical test pattern was unremarkable while the HPLC profile of mycolic acids resembled that of Mycobacterium fortuitum. The sequences of three major housekeeping genes (16S rRNA, hsp65 and rpoB) were unique and differed from those of any other mycobacterium. Mycobacterium brisbanense, which is the species that shared the highest 16S rRNA gene sequence similarity (99.03 %), was distinct, as shown by the average nucleotide identity and by the genome to genome distance values (91.05 and 43.10 %, respectively). The strains are thus considered to represent a novel species of the genus Mycobacterium, for which the name Mycobacterium aquaticum sp. nov. is proposed. The type strain is RW6T (=DSM 104277T=CIP111198T).

  19. Genomics and ecophysiology of heterotrophic nitrogen fixing bacteria isolated from estuarine surface water

    DEFF Research Database (Denmark)

    Bentzon-Tilia, Mikkel; Severin, Ina; Hansen, Lars H.

    2015-01-01

    The ability to reduce atmospheric nitrogen (N2) to ammonia, known as N2 fixation, is a widely distributed trait among prokaryotes that accounts for an essential input of new N to a multitude of environments. Nitrogenase reductase gene (nifH) composition suggests that putative N2-fixing heterotrop......The ability to reduce atmospheric nitrogen (N2) to ammonia, known as N2 fixation, is a widely distributed trait among prokaryotes that accounts for an essential input of new N to a multitude of environments. Nitrogenase reductase gene (nifH) composition suggests that putative N2-fixing...... heterotrophic organisms are widespread in marine bacterioplankton, but their autecology and ecological significance are unknown. Here, we report genomic and ecophysiology data in relation to N2 fixation by three environmentally relevant heterotrophic bacteria isolated from Baltic Sea surface water: Pseudomonas...... liter-1, presumably accommodated through aggregate formation. Glucose stimulated N2 fixation in general, and reactive N repressed N2 fixation, except that ammonium (NH4 ) stimulated N2 fixation in R. palustris BAL398, indicating the use of nitrogenase as an electron sink. The lack of correlations...

  20. A support system for water system isolation task in NPP by using augmented reality and RFID

    International Nuclear Information System (INIS)

    Shimoda, Hiroshi; Ishii, Hirotake; Yamazaki, Yuichiro; Yoshikawa, Hidekazu

    2004-01-01

    Aiming at improvement of task performance and reduction of human error of water system isolation task in NPP periodic maintenance, a support system using state-of-art information technology, Augmented Reality (AR) and Radio Frequency Identification (RFID) has been proposed, and a prototype system has been developed. The system has navigation function of which an indication is superimposed directly on the user's view to help to find the designated valves by AR. It also has valve confirmation function by scanning RFID tag attached on the valve. In case of applying it to practical use, its information presentation device is important because it affects the task performance. In this study, therefore, a suitable information presentation device has been pursued by conducting subject experiments employing psychological experimental technique. The candidates of the devices are one-eye video see-through HMD (SCOPO) and both-eye video see-through HMD (Glasstron) as wearable system configuration, and tablet PC and compact TV as handheld system configuration. In the experiment, task completion time, number of errors, NASA-TLX score as subjects' mental workload and subjective usability questionnaire were measured when using the above devices. As the results, it was found that one-eye video see-through head mounted display, SCOPO was suitable device as wearable system configuration, and compact TV was suitable device as handheld system configuration. (author)

  1. A simple cleanup method for the isolation of nitrate from natural water samples for O isotopes analysis

    International Nuclear Information System (INIS)

    Haberhauer, G.; Blochberger, K.

    1999-09-01

    The analysis of O-isotopic composition of nitrate has many potential applications in studies of environmental processes. O-isotope nitrate analysis require sample free of other oxygen-containing compounds. More than 100 % of non-NO 3 - oxygen relative to NO 3 - oxygen can still be found in forest soil water samples after cleanup if improper cleanup strategies, e.g., adsorption onto activated carbon, are used. Such non-NO 3 - oxygen compounds will bias O-isotropic data. Therefore, an efficient cleanup method was developed to isolate nitrate from natural water samples. In a multistep cleanup procedure using adsorption onto water-insoluble poly(vinylpyrrolidone), removal of almost all other oxygen-containing compounds, such as fulvic acids, and isolation of nitrate was achieved. The method supplied samples free of non-NO 3 - oxygen which can be directly combusted to CO 2 for subsequent O-isotope analysis. (author)

  2. Isolate-specific effects of patulin, penicillic Acid and EDTA on biofilm formation and growth of dental unit water line biofilm isolates.

    Science.gov (United States)

    Liaqat, Iram; Bachmann, Robert Thomas; Sabri, Anjum Nasim; Edyvean, Robert G J

    2010-08-01

    Dental unit water line (DUWL) contamination by opportunistic pathogens has its significance in nosocomial infection of patients, health care workers, and life-threatening infections to immunocompromized persons. Recently, the quorum sensing (QS) system of DUWL isolates has been found to affect their biofilm-forming ability, making it an attractive target for antimicrobial therapy. In this study, the effect of two quorum-sensing inhibitory compounds (patulin; PAT, penicillic acid; PA) and EDTA on planktonic growth, AI-2 signalling and in vitro biofilm formation of Pseudomonas aeruginosa, Achromobacter xylosoxidans and Achromobacter sp. was monitored. Vibrio harveyi BB170 bioassay and crystal violet staining methods were used to detect the AI-2 monitoring and biofilm formation in DUWL isolates, respectively. The V. harveyi BB170 bioassay failed to induce bioluminescence in A. xylosoxidans and Achromobacter sp., while P. aeruginosa showed AI-2 like activity suggesting the need of some pretreatments prior to bioassay. All strains were found to form biofilms within 72 h of incubation. The QSIs/EDTA combination have isolate-specific effects on biofilm formation and in some cases it stimulated biofilm formation as often as it was inhibited. However, detailed information about the anti-biofilm effect of these compounds is still lacking.

  3. Gibbs Free Energy of Hydrolytic Water Molecule in Acyl-Enzyme Intermediates of a Serine Protease: A Potential Application for Computer-Aided Discovery of Mechanism-Based Reversible Covalent Inhibitors.

    Science.gov (United States)

    Masuda, Yosuke; Yamaotsu, Noriyuki; Hirono, Shuichi

    2017-01-01

    In order to predict the potencies of mechanism-based reversible covalent inhibitors, the relationships between calculated Gibbs free energy of hydrolytic water molecule in acyl-trypsin intermediates and experimentally measured catalytic rate constants (k cat ) were investigated. After obtaining representative solution structures by molecular dynamics (MD) simulations, hydration thermodynamics analyses using WaterMap™ were conducted. Consequently, we found for the first time that when Gibbs free energy of the hydrolytic water molecule was lower, logarithms of k cat were also lower. The hydrolytic water molecule with favorable Gibbs free energy may hydrolyze acylated serine slowly. Gibbs free energy of hydrolytic water molecule might be a useful descriptor for computer-aided discovery of mechanism-based reversible covalent inhibitors of hydrolytic enzymes.

  4. Geographical Variation in Antibiotic-Resistant Escherichia coli Isolates from Stool, Cow-Dung and Drinking Water

    Science.gov (United States)

    Sahoo, Krushna Chandra; Tamhankar, Ashok J.; Sahoo, Soumyakanta; Sahu, Priyadarshi Soumyaranjan; Klintz, Senia Rosales; Lundborg, Cecilia Stålsby

    2012-01-01

    Little information is available on relationships between the biophysical environment and antibiotic resistance. This study was conducted to investigate the antibiotic resistance pattern of Escherichia coli isolated from child stool samples, cow-dung and drinking water from the non-coastal (230 households) and coastal (187 households) regions of Odisha, India. Susceptibility testing of E. coli isolates (n = 696) to the following antibiotics: tetracycline, ampicillin/sulbactam, cefuroxime, cefotaxime, cefixime, cotrimoxazole, amikacin, ciprofloxacin, norfloxacin and nalidixic acid was performed by the disk diffusion method. Ciprofloxacin minimum inhibitory concentration (MIC) values were determined for ciprofloxacin-resistant isolates (n = 83). Resistance to at least one antibiotic was detected in 90% or more of the E. coli isolates. Ciprofloxacin MIC values ranged from 8 to 32 µg/mL. The odds ratio (OR) of resistance in E. coli isolates from children’s stool (OR = 3.1, 95% CI 1.18–8.01), cow-dung (OR = 3.6, 95% CI 1.59–8.03, P = 0.002) and drinking water (OR = 3.8, 95% CI 1.00–14.44, P = 0.049) were higher in non-coastal compared to coastal region. Similarly, the co-resistance in cow-dung (OR = 2.5, 95% CI 1.39–4.37, P = 0.002) and drinking water (OR = 3.2, 95% CI 1.36–7.41, P = 0.008) as well as the multi-resistance in cow-dung (OR = 2.2, 95% CI 1.12–4.34, P = 0.022) and drinking water (OR = 2.7, 95% CI 1.06–7.07, P = 0.036) were also higher in the non-coastal compared to the coastal region. PMID:22690160

  5. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 4. Molecule Matters – van der Waals Molecules - History and Some Perspectives on Intermolecular Forces. E Arunan. Feature Article Volume 14 Issue 4 April 2009 pp 346-356 ...

  6. Phase-Transfer Energetics of Small-Molecule Alcohols Across the Water-Hexane Interface: Molecular Dynamics Simulation Using Charge Equilibration Models

    Science.gov (United States)

    Bauer, Brad A.; Zhong, Yang; Meninger, David J.; Davis, Joseph E.; Patel, Sandeep

    2010-01-01

    We study the water-hexane interface using molecular dynamics (MD) and polarizable charge equilibration (CHEQ) force fields. Bulk densities for TIP4P-FQ water and hexane, 1.0086±0.0002 g/cm3 and 0.6378±0.0001 g/cm3, demonstrate excellent agreement with experiment. Interfacial width and interfacial tension are consistent with previously reported values. The in-plane component of the dielectric permittivity (ε∥) for water is shown to decrease from 81.7±0.04 to unity, transitioning longitudinally from bulk water to bulk hexane. ε∥ for hexane reaches a maximum in the interface, but this term represents only a small contribution to the total dielectric constant (as expected for a non-polar species). Structurally, net orientations of the molecules arise in the interfacial region such that hexane lies slightly parallel to the interface and water reorients to maximize hydrogen bonding. Interfacial potentials due to contributions of the water and hexane are calculated to be -567.9±0.13mV and 198.7±0.01mV, respectively, giving rise to a total potential in agreement with the range of values reported from previous simulations of similar systems. Potentials of mean force (PMF) calculated for methanol, ethanol, and 1-propanol for the transfer from water to hexane indicate an interfacial free energy minimum, corresponding to the amphiphilic nature of the molecules. The magnitudes of transfer free energies were further characterized from the solvation free energies of alcohols in water and hexane using thermodynamic integration. This analysis shows that solvation free energies for alcohols in hexane are 0.2-0.3 kcal/mol too unfavorable, whereas solvation of alcohols in water is approximately 1 kcal/mol too favorable. For the pure hexane-water interfacial simulations, we observe a monotonic decrease of the water dipole moment to near-vacuum values. This suggests that the electrostatic component of the desolvation free energy is not as severe for polarizable models than

  7. Microbial quality and molecular identification of cultivable microorganisms isolated from an urban drinking water distribution system (Limassol, Cyprus).

    Science.gov (United States)

    Botsaris, George; Kanetis, Loukas; Slaný, Michal; Parpouna, Christiana; Makris, Konstantinos C

    2015-12-01

    Microorganisms can survive and multiply in aged urban drinking water distribution systems, leading to potential health risks. The objective of this work was to investigate the microbial quality of tap water and molecularly identify its predominant cultivable microorganisms. Tap water samples collected from 24 different households scattered in the urban area of Limassol, Cyprus, were microbiologically tested following standard protocols for coliforms, E. coli, Pseudomonas spp., Enterococcus spp., and total viable count at 22 and 37 °C. Molecular identification was performed on isolated predominant single colonies using 16SrRNA sequencing. Approximately 85% of the household water samples were contaminated with one or more microorganisms belonging to the genera of Pseudomonas, Corynebacterium, Agrobacterium, Staphylococcus, Bacillus, Delftia, Acinetobacter, Enterococcus, Enterobacter, and Aeromonas. However, all samples tested were free from E. coli. This is the first report in Cyprus molecularly confirming specific genera of relevant microbial communities in tap water.

  8. Antibiotic susceptibility profile of bacteria isolated from natural sources of water from rural areas of East Sikkim

    Directory of Open Access Journals (Sweden)

    Shubra Poonia

    2014-01-01

    Full Text Available Background: Contamination of water, food, and environment with antibiotic-resistant bacteria poses a serious public health issue. Objective: The objective was to study the bacterial pollution of the natural sources of water in east Sikkim and to determine the antimicrobial profile of the bacterial isolates. Materials and Methods: A total of 225 samples, 75 each during winter, summer, and monsoon season were collected from the same source in every season for bacteriological analysis by membrane filtration method. Antibiotic susceptibility test was performed using standard disc diffusion method. Results: A total of 19 bacterial species of the genera Escherichia, Klebsiella, Proteus, Salmonella, Shigella, Enterobacter, Citrobacter, Morganella, Pseudomonas, Acinetobacter, Flavobacterium, and Serratia were isolated and their antimicrobial sensitivity tested. Generally, most bacterial isolates except Salmonella and Shigella species were found resistant to commonly used antibiotics such as ampicillin (57.5%, trimethoprim/sulfamethoxaole (39.1%, amoxicillin/clavulanic acid (37.4%, cefixime (34.5%, tetracycline (29.1%, ceftazidime (26.3%, ofloxacin (25.9%, amikacin (8.7%, and gentamicin (2.7% but sensitive to imipenem and piperacillin/tazobactam. Conclusion: Natural sources of water in east Sikkim are grossly contaminated with bacteria including enteropathogens. The consumption of untreated water from these sources might pose health risk to consumers.

  9. Technical support for GEIS: radioactive waste isolation in geologic formations. Volume 21. Ground water movement and nuclide transport

    Energy Technology Data Exchange (ETDEWEB)

    None

    1978-04-01

    This volume, TM-36/21 Ground Water Movement and Nuclide Transport, is one of a 23-volume series, ''Technical Support for GEIS: Radioactive Waste Isolation in Geologic Formations, Y/OWI/TM-36'' which supplements a ''Contribution to Draft Generic Environmental Impact Statement on Commercial Waste Management: Radioactive Waste Isolation in Geologic Formations, Y/OWI/TM-44.'' The series provides a more complete technical basis for the preconceptual designs, resource requirements, and environmental source terms associated with isolating commercial LWR wastes in underground repositories in salt, granite, shale and basalt. Wastes are considered from three fuel cycles: uranium and plutonium recycling of spent fuel and uranium-only recycling. The studies presented in this volume consider the effect of the construction of the repository and the consequent heat generation on the ground water movement. Additionally, the source concentrations and leach rates of selected radionuclides were studied in relation to the estimated ground water inflow rates. Studies were also performed to evaluate the long term migration of radionuclides as affected by the ground water flow. In all these studies, three geologic environments are considered; granite, shale and basalt.

  10. Dual reorientation relaxation routes of water molecules in oxyanion’s hydration shell: A molecular geometry perspective

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Wen Jun; Yang, Yi Isaac; Gao, Yi Qin, E-mail: gaoyq@pku.edu.cn [Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering and Biodynamic Optical Imaging Center, Peking University, Beijing 100871 (China)

    2015-12-14

    In this study, we examine how complex ions such as oxyanions influence the dynamic properties of water and whether differences exist between simple halide anions and oxyanions. Nitrate anion is taken as an example to investigate the hydration properties of oxyanions. Reorientation relaxation of its hydration water can occur through two different routes: water can either break its hydrogen bond with the nitrate to form one with another water or switch between two oxygen atoms of the same nitrate. The latter molecular mechanism increases the residence time of oxyanion’s hydration water and thus nitrate anion slows down the translational motion of neighbouring water. But it is also a “structure breaker” in that it accelerates the reorientation relaxation of hydration water. Such a result illustrates that differences do exist between the hydration of oxyanions and simple halide anions as a result of different molecular geometries. Furthermore, the rotation of the nitrate solute is coupled with the hydrogen bond rearrangement of its hydration water. The nitrate anion can either tilt along the axis perpendicularly to the plane or rotate in the plane. We find that the two reorientation relaxation routes of the hydration water lead to different relaxation dynamics in each of the two above movements of the nitrate solute. The current study suggests that molecular geometry could play an important role in solute hydration and dynamics.

  11. Dual reorientation relaxation routes of water molecules in oxyanion’s hydration shell: A molecular geometry perspective

    International Nuclear Information System (INIS)

    Xie, Wen Jun; Yang, Yi Isaac; Gao, Yi Qin

    2015-01-01

    In this study, we examine how complex ions such as oxyanions influence the dynamic properties of water and whether differences exist between simple halide anions and oxyanions. Nitrate anion is taken as an example to investigate the hydration properties of oxyanions. Reorientation relaxation of its hydration water can occur through two different routes: water can either break its hydrogen bond with the nitrate to form one with another water or switch between two oxygen atoms of the same nitrate. The latter molecular mechanism increases the residence time of oxyanion’s hydration water and thus nitrate anion slows down the translational motion of neighbouring water. But it is also a “structure breaker” in that it accelerates the reorientation relaxation of hydration water. Such a result illustrates that differences do exist between the hydration of oxyanions and simple halide anions as a result of different molecular geometries. Furthermore, the rotation of the nitrate solute is coupled with the hydrogen bond rearrangement of its hydration water. The nitrate anion can either tilt along the axis perpendicularly to the plane or rotate in the plane. We find that the two reorientation relaxation routes of the hydration water lead to different relaxation dynamics in each of the two above movements of the nitrate solute. The current study suggests that molecular geometry could play an important role in solute hydration and dynamics

  12. Genetic relatedness of faecal coliforms and enterococci bacteria isolated from water and sediments of the Apies River, Gauteng, South Africa.

    Science.gov (United States)

    Ekwanzala, Mutshiene Deogratias; Abia, Akebe Luther King; Ubomba-Jaswa, Eunice; Keshri, Jitendra; Momba, Ndombo Benteke Maggy

    2017-12-01

    To date, the microbiological quality of river sediments and its impact on water resources are not included in the water quality monitoring assessment. Therefore, the aim of this study was to establish genetic relatedness between faecal coliforms and enterococci isolated from the river water and riverbed sediments of Apies River to better understand the genetic similarity of microorganisms between the sediment and water phases. Indicator bacteria were subjected to a molecular study, which consisted of PCR amplification and sequence analysis of the 16S rRNA and 23S rRNA gene using specific primers for faecal coliforms and enterococci, respectively. Results revealed that the Apies River had high faecal pollution levels with enterococci showing low to moderate correlation coefficient (r 2 values ranged from 0.2605 to 0.7499) compared to the faecal coliforms which showed zero to low correlation (r 2 values ranged from 0.0027 to 0.1407) indicating that enterococci may be better indicator than faecal coliforms for detecting faecal contamination in riverbed sediments. The phylogenetic tree of faecal coliforms revealed a 98% homology among their nucleotide sequences confirming the close genetic relatedness between river water and riverbed sediment isolates. The phylogenetic tree of the enterococci showed that Enterococcus faecalis and Enterococcus faecium are the predominant species found in both river water and riverbed sediments with bootstrap values of ≥99%. A high degree of genetic relatedness between sediment and water isolates indicated a possible common ancestry and transmission pathway. We recommend the microbial monitoring of riverbed sediments as it harbours more diverse microbial community and once resuspended may cause health and environmental problems.

  13. Aspects of constitutive and acquired antibioresistance in Aeromonas hydrophila strains isolated from water sources.

    Science.gov (United States)

    Balotescu, Carmen; Israil, Anca; Radu, Roxana; Alexandru, Ionela; Dobre, Georgeta

    2003-01-01

    without a direct medical impact, however they could play an indirect one remaining permanent sources of R genes for bacterial strains with pathogenic abilities implicated in human pathology (i.e. Aeromonas infections in man related to different professional activities such as fishing, surfing, swimming, diving, etc.). The purpose of this work was to determine the aspects related to constitutive and acquired antibioresistance in 35 A. hydrophila strains isolated in aquatic environment of Danube Delta (10 salmaster waters, 5 aquatic plants, 5 fish intestinal content, 5 fish sapling, 5 snake and oyster shells). The strains were biochemically identified by using API20E and API20NE kits. The antibioresistance spectrum was determined by disk diffusion method following NCCLS 2000 recommendations. The choice and disposal of antibiotics on the Mueller Hinton plate was done to allow the interpretive reading and the phenotypic detection of different antibioresistance mechanisms, as follows: beta-lactamases (PEN, ME, AMX, AMC, CAZ) and carbapenemase (IMP) production; porin deficiency (FOX); efflux mechanism (C, TE, NOR). All tested strains exhibited high resistance to penicillin, aspect pleading for constitutive penicillinase production in Aeromonas strains. With reference to other penicillins (ME, AMX, AMC) and cephalosporins (CAZ, FOX) the tested strains exhibited 2 different antibioresistance patterns: AMX-R, AMC-S, CAZ-S (65%) indicating the presence of beta-lactamase sensitive to inhibitors and AMX-R, AMC-R, CAZ-S (22%) indicating the presence of beta-lactamase resistant to inhibitors. Resistance to FOX in 8% of strains signifies a phenotypical marker for the presence of porin deficiency. Only one Aeromonas strain (2.8%) was resistant to IMP. Three strains (8%) were simultaneous resistant to TE and TMP/SMX, NOR and CHL probably due to the presence of a resistance plasmid (codifying an efflux/ enzymatic mechanism). These aspects are pleading for the necessity to investigate the

  14. Streptomyces lonarensis sp. nov., isolated from Lonar Lake, a meteorite salt water lake in India.

    Science.gov (United States)

    Sharma, Trupti K; Mawlankar, Rahul; Sonalkar, Vidya V; Shinde, Vidhya K; Zhan, Jing; Li, Wen-Jun; Rele, Meenakshi V; Dastager, Syed G; Kumar, Lalitha Sunil

    2016-02-01

    A novel alkaliphilic actinomycete, strain NCL716(T), was isolated from a soil sample collected from the vicinity of Lonar Lake, an alkaline salt water meteorite lake in Buldhana district of Maharashtra State in India. The strain was characterised using a polyphasic taxonomic approach which confirmed that it belongs to the genus Streptomyces. Growth was observed over a pH range of 7-11 at 28 °C. The cell wall was found to contain LL-diaminopimelic acid and traces of meso-diaminopimelic acid. The major fatty acid components were identified as iso-C16:0 (46.8 %), C17:1 (12.4 %), anteiso-C15:0 (5.1 %) and anteiso-C17:1 (4.8 %). The major polar lipids were identified as diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol. The major menaquinones were determined to be MK-9 (H6) (70.3 %), MK-9 (H4) (15.5 %) and MK-9 (H8) (7.2 %). The G+C content of the DNA of the type strain was determined to be 71.4 mol %. The 16S rRNA gene sequence has been deposited in GenBank with accession number FJ919811. Although the 16S rRNA gene sequence analysis revealed that strain NCL716(T) shares >99 % similarity with that of Streptomyces bohaiensis strain 11A07(T), DNA-DNA hybridization revealed only 33.2 ± 3.0 % relatedness between them. Moreover, these two strains can be readily distinguished by some distinct phenotypic characteristics. Hence, on the basis of phenotypic and genetic analyses, it is proposed that strain NCL716(T) represents a novel species of the genus Streptomyces, for which the name Streptomyces lonarensis sp. nov., is proposed. The type strain is NCL 716(T) (=DSM 42084(T) = MTCC 11708(T) = KCTC 39684(T)).

  15. Solid state {sup 1}H spin-lattice relaxation and isolated-molecule and cluster electronic structure calculations in organic molecular solids: The relationship between structure and methyl group and t-butyl group rotation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xianlong, E-mail: WangXianlong@uestc.edu.cn, E-mail: pbeckman@brynmawr.edu [Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, 4 North Jianshe Rd., 2nd Section, Chengdu 610054 (China); Mallory, Frank B. [Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Mallory, Clelia W. [Department of Chemistry, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States); Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 (United States); Odhner, Hosanna R.; Beckmann, Peter A., E-mail: WangXianlong@uestc.edu.cn, E-mail: pbeckman@brynmawr.edu [Department of Physics, Bryn Mawr College, 101 North Merion Ave., Bryn Mawr, Pennsylvania 19010-2899 (United States)

    2014-05-21

    We report ab initio density functional theory electronic structure calculations of rotational barriers for t-butyl groups and their constituent methyl groups both in the isolated molecules and in central molecules in clusters built from the X-ray structure in four t-butyl aromatic compounds. The X-ray structures have been reported previously. We also report and interpret the temperature dependence of the solid state {sup 1}H nuclear magnetic resonance spin-lattice relaxation rate at 8.50, 22.5, and 53.0 MHz in one of the four compounds. Such experiments for the other three have been reported previously. We compare the computed barriers for methyl group and t-butyl group rotation in a central target molecule in the cluster with the activation energies determined from fitting the {sup 1}H NMR spin-lattice relaxation data. We formulate a dynamical model for the superposition of t-butyl group rotation and the rotation of the t-butyl group's constituent methyl groups. The four compounds are 2,7-di-t-butylpyrene, 1,4-di-t-butylbenzene, 2,6-di-t-butylnaphthalene, and 3-t-butylchrysene. We comment on the unusual ground state orientation of the t-butyl groups in the crystal of the pyrene and we comment on the unusually high rotational barrier of these t-butyl groups.

  16. Consistent force field modeling of matrix isolated molecules. V. Minimum energy path potential to the conformer conversion of 1,2-difluoroethane: Ar 364, ab initio calculation of electric multipole moments and electric polarization contribution to the conversion barrier

    Science.gov (United States)

    Gunde, R.; Ha, T.-K.; Günthard, H. H.

    1990-08-01

    In this paper results of consistent force field modeling (CFF) of the potential function to conversion of the gauche (g) to the trans (t) conformer of 1,2-difluoroethane (DFE) isolated in an argon matrix will be reported. Starting point are locally stable configurations gDFE:Ar 364 (defect GH1) and tDFE:Ar 364 (TH1) obtained in previous work from CFF modeling of a cube shaped Ar 364 fragment containing one DFE molecule in its center. Using the dihedral angle of DFE as an independent parameter the minimum energy path of the conversion process gDFE:Ar 364→tDFE:Ar 364 will be determined by CFF energy minimization. Determination of the minimum energy path is found to require large numbers of energy minimization steps and to lead to a rather complicated motion of the molecule with respect to the crystal fragment. Surprisingly the molecule-matrix interactions lead to a reduction of the g-t barrier by ≈500 cal/mol and to a stabilization of the trans species by ≈500 cal/mol. This finding is a consequence of a delicate interplay of matrix-molecule and matrix-matrix interactions. Calculation of the electric polarization energy (induced dipole-first-order polarization approximation) is based on extended ab initio calculations of dipole and quadrupole moments and a bond polarizability estimate of the first-order polarizability of DFE as a function of the internal rotation angle, on Fourier expansion of multipole components and use of symmetry for reduction of the order of the linear system defining the (self-consistent) induced dipole moments of all Ar atoms. Electric polarization is found to alter the potential function of the conversion process in a profound way: the g-t barrier and the t-g energy difference are increased to ≈3000 cal/mol and to ≈1500 cal/mol respectively (≈2500 and ≈530 cal/mol respectively for free DFE). Further applications of the technique developed in this work to related problems of matrix isolated molecules, e.g., vibrational matrix

  17. Carbonic anhydrase inhibitors. Comparison of chlorthalidone, indapamide, trichloromethiazide, and furosemide X-ray crystal structures in adducts with isozyme II, when several water molecules make the difference.

    Science.gov (United States)

    Temperini, Claudia; Cecchi, Alessandro; Scozzafava, Andrea; Supuran, Claudiu T

    2009-02-01

    Thiazide and high ceiling diuretics were recently shown to inhibit all mammalian isoforms of carbonic anhydrase (CA, EC 4.2.1.1) with a very different profile as compared to classical inhibitors, such as acetazolamide, methazolamide, and ethoxzolamide. Some of these structurally related compounds have a very different behavior against the widespread isozyme CA II, with chlorthalidone, trichloromethiazide, and furosemide being efficient inhibitors against CA II (K(I)s of 65-138 nM), whereas indapamide is a much weaker one (K(I) of 2520 nM). Furthermore, some of these diuretics are quite efficient (low nanomolar) inhibitors of other isoforms, for example, chlorthalidone against hCA VB, VII, IX, and XIII; indapamide against CA VII, IX, XII, and XIII, trichloromethiazide against CA VII and IX, and furosemide against CA I and XIV. Examining the four X-ray crystal structures of their CA II adducts, we observed several (2-3) active site water molecules interacting with the chlorthalidone, trichloromethiazide, and furosemide scaffolds which may be responsible for this important difference of activity. Indeed, indapamide bound to CA II has no interactions with active site water molecules. Chlorthalidone bound within the CA II active site is in an enolic (lactimic) tautomeric form, with the enolic OH also participating in two strong hydrogen bonds with Asn67 and a water molecule. The newly evidenced binding modes of these diuretics may be exploited for designing better CA II inhibitors as well as compounds with selectivity/affinity for various isoforms with medicinal chemistry applications.

  18. The effect of micro-environment on luminescence of aequorin: the role of amino acids and explicit water molecules on spectroscopic properties of coelenteramide.

    Science.gov (United States)

    Li, Zuo-Sheng; Zou, Lu-Yi; Min, Chun-Gang; Ren, Ai-Min

    2013-10-05

    Despite the fact that the luminescence reaction mechanism of aequorin has been intensively investigated, details in luminescence such as the effect of important amino acids residues and explicit water molecules on spectroscopic properties of coelenteramide remain unclear. In this work, the effect of amino acids residues His16, Tyr82, Trp86, Phe113, Trp129, Tyr132, explicit water molecules Wat505 and Wat405 on the spectral properties of CLM(-) has been studied by CAM-B3LYP, TD M06L and TD CAM-B3LYP methods in hydrophobic environment and aqueous solution. In hydrophobic environment, the amino acids or water molecules have no significant effect on the absorption. Tyr82 and Trp86 move close to CLM(-) changes the hydrogen bond network, and thus, the spectral properties is significantly affected by the hydrogen bonds between His16H(+)+Tyr82+Trp86 and CLM(-). Tyr82, Trp86 hydrogen bonding to CLM(-) upshifts the excited energy and helps emission spectra shift to blue region. Therefore, it is concluded that His16H(+)+Tyr82+Trp86 modify the emission spectra. The molecular electrostatic potential indicated that the greater electron density is located at the oxygen atom of 6-p-hydroxyphenyl group of CLM(-), and it facilitates the formation of hydrogen bond with His16H(+)+Tyr82+Trp86. It is a critical condition for the modification of emission spectra. It is expected to help to understand the interactions between emitter and amino acids in the micro environment. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Complete Isolation and Characterization of Polar Portion of Mentha dumetorum Water Extract

    Directory of Open Access Journals (Sweden)

    Hüseyin Akşit

    2014-05-01

    Full Text Available Four flavon glycosides, eriocitrin (1, luteolin-7-O-rutinoside (2, hesperidin (3, apigenin-7-O-rutinoside (4 and rosmarinic acid (5 were isolated from the aerial parts of Mentha dumetorum (Lamiaceae for the first time. The structural elucidations of isolated compounds were achieved using spectral methods (1D- and 2D-NMR, and LC-TOF-HRMS.

  20. High Manganese Tolerance and Biooxidation Ability of Serratia marcescens Isolated from Manganese Mine Water in Minas Gerais, Brazil

    Directory of Open Access Journals (Sweden)

    Natália R. Barboza

    2017-10-01

    Full Text Available Manganese is an important metal for the maintenance of several biological functions, but it can be toxic in high concentrations. One of the main forms of human exposure to metals, such as manganese (Mn, is the consumption of solar salt contaminated. Mn-tolerant bacteria could be used to decrease the concentration of this metal from contaminated sites through safer environmental-friendly alternative technology in the future. Therefore, this study was undertaken to isolate and identify Mn resistant bacteria from water samples collected from a Mn mine in the Iron Quadrangle region (Minas Gerais, Brazil. Two bacterial isolates were identified as Serratia marcescens based on morphological, biochemical, 16S rDNA gene sequencing and phylogeny analysis. Maximum resistance of the selected isolates against increasing concentrations of Mn(II, up to 1200 mg L-1 was determined in solid media. A batch assay was developed to analyze and quantify the Mn removal capacities of the isolates. Biological Mn removal capacities of over 55% were detected for both isolates. Whereas that mechanism like biosorption, precipitation and oxidation could be explaining the Mn removal, we seek to give an insight into some of the molecular mechanisms adopted by S. marcescens isolates. For this purpose, the following approaches were adopted: leucoberbelin blue I assay, Mn(II oxidation by cell-free filtrate and electron microscopy and energy-dispersive X-ray spectroscopy analyses. Overall, these results indicate that S. marcescens promotes Mn removal in an indirect mechanism by the formation of Mn oxides precipitates around the cells, which should be further explored for potential biotechnological applications for water recycling both in hydrometallurgical and mineral processing operations.

  1. [Dynamics of Irreversible Evaporation of a Water-Protein Droplet and a Problem of Structural and Dynamical Experiments with Single Molecules].

    Science.gov (United States)

    Shaitan, K V; Armeev, G A; Shaytan, A K

    2016-01-01

    We discuss the effect of isothermal and adiabatic evaporation of water on the state of a water-protein droplet. The discussed problem is of current importance due to development of techniques to perform single molecule experiments using free electron lasers. In such structure-dynamic experiments the delivery of a sample into the X-ray beam is performed using the microdroplet injector. The time between the injection and delivery is in the order of microseconds. In this paper we developed a specialized variant of all-atom molecular dynamics simulations for the study of irreversible isothermal evaporation of the droplet. Using in silico experiments we determined the parameters of isothermal evaporation of the water-protein droplet with the sodium and chloride ions in the concentration range of 0.3 M at different temperatures. The energy of irreversible evaporation determined from in silico experiments at the initial stages of evaporation virtually coincides with the specific heat of evaporation for water. For the kinetics of irreversible adiabatic evaporation an exact analytical solution was obtained in the limit of high thermal conductivity of the droplet (or up to the droplet size of -100 Å). This analytical solution incorporates parameters that are determined using in silico. experiments on isothermal droplet evaporation. We show that the kinetics of adiabatic evaporation and cooling of the droplet scales with the droplet size. Our estimates of the water-protemi droplet. freezing rate in the adiabatic regime in a vacuum chamber show that additional techniques for stabilizing the temperature inside the droplet should be used in order to study the conformational transitions of the protein in single molecules. Isothermal and quasi-isothermal conditions are most suitable for studying the conformational transitions upon object functioning. However, in this case it is necessary to take into account the effects of dehydration and rapid increase of ionic strength in an

  2. Isolation and analysis of bacteria with antimicrobial activities from the marine sponge Haliclona simulans collected from Irish waters.

    Science.gov (United States)

    Kennedy, Jonathan; Baker, Paul; Piper, Clare; Cotter, Paul D; Walsh, Marcella; Mooij, Marlies J; Bourke, Marie B; Rea, Mary C; O'Connor, Paula M; Ross, R Paul; Hill, Colin; O'Gara, Fergal; Marchesi, Julian R; Dobson, Alan D W

    2009-01-01

    Samples of the marine sponge Haliclona simulans were collected from Irish coastal waters, and bacteria were isolated from these samples. Phylogenetic analyses of the cultured isolates showed that four different bacterial phyla were represented; Bacteriodetes, Actinobacteria, Proteobacteria, and Firmicutes. The sponge bacterial isolates were assayed for the production of antimicrobial substances, and biological activities against Gram-positive and Gram-negative bacteria and fungi were demonstrated, with 50% of isolates showing antimicrobial activity against at least one of the test strains. Further testing showed that the antimicrobial activities extended to the important pathogens Pseudomonas aeruginosa, Clostridium difficile, multi-drug-resistant Staphylococcus aureus, and pathogenic yeast strains. The Actinomycetes were numerically the most abundant producers of antimicrobial activities, although activities were also noted from Bacilli and Pseudovibrio isolates. Surveys for the presence of potential antibiotic encoding polyketide synthase and nonribosomal peptide synthetase genes also revealed that genes for the biosynthesis of these secondary metabolites were present in most bacterial phyla but were particularly prevalent among the Actinobacteria and Proteobacteria. This study demonstrates that the culturable fraction of bacteria from the sponge H. simulans is diverse and appears to possess much potential as a source for the discovery of new medically relevant biological active agents.

  3. Photoproduction of hydrogen by a non-sulphur bacterium isolated from root zones of water fern Azolla pinnata

    Energy Technology Data Exchange (ETDEWEB)

    Singh, S.P.; Srivastava, S.C.; Pandey, K.D. (Banaras Hindu Univ., Varanasi (IN). Centre of Advanced Study in Botany)

    1990-01-01

    A photosynthetic bacterium Rhodopseudomonas sp. BHU strain 1 was isolated from the root zone of water fern Azolla pinnata. The bacterium was found to produce hydrogen with potato starch under phototrophic conditions. The immobilized bacterial cells showed sustained hydrogen production with a more than 4-fold difference over free cell suspensions. The data have been discussed in the light of possible utilization of relatively cheaper raw materials by non-sulphur bacteria to evolve hydrogen. (author).

  4. Analysis of a main steam isolation valve closure anticipated transient without scram in a boiling water reactor

    International Nuclear Information System (INIS)

    Liaw, T.J.; Pan, C.; Chen, G.S.

    1989-01-01

    Anticipated transient without scram (ATWS) could be a major accident sequence with possible core melt and containment damage in a boiling water reactor (BWR). The behavior of a BWR/6 during a main stream isolation valve closure ATWS is investigated using the best-estimate computer program, RETRAN-02. The effects of both makeup coolant and boron injection on the reactor behavior are studied. It is found that the BWR/6 behaves similarly to the BWR/2 and BWR/4

  5. Antibiotic resistance patterns of Escherichia coli strains isolated from surface water and groundwater samples in a pig production area

    OpenAIRE

    Roger Neto Schneider; André Nadvorny; Verônica Schmidt

    2009-01-01

    The use of antibiotics, so excessive and indiscriminate in intensive animal production, has triggered an increase in the number of resistant microorganisms which can be transported to aquatic environments. The aim of this study was to determine the profile of the antimicrobial resistance of samples of Escherichia coli isolated from groundwater and surface water in a region of pig breeding. Through the test of antimicrobial susceptibility, we analyzed 205 strains of E. coli. A high rate of res...

  6. Atkins' molecules

    CERN Document Server

    Atkins, Peters

    2003-01-01

    Originally published in 2003, this is the second edition of a title that was called 'the most beautiful chemistry book ever written'. In it, we see the molecules responsible for the experiences of our everyday life - including fabrics, drugs, plastics, explosives, detergents, fragrances, tastes, and sex. With engaging prose Peter Atkins gives a non-technical account of an incredible range of aspects of the world around us, showing unexpected connections, and giving an insight into how this amazing world can be understood in terms of the atoms and molecules from which it is built. The second edition includes dozens of extra molecules, graphical presentation, and an even more accessible and enthralling account of the molecules themselves.

  7. Interstellar Molecules

    Science.gov (United States)

    Solomon, Philip M.

    1973-01-01

    Radioastronomy reveals that clouds between the stars, once believed to consist of simple atoms, contain molecules as complex as seven atoms and may be the most massive objects in our Galaxy. (Author/DF)

  8. Distribution of sequence-based types of legionella pneumophila serogroup 1 strains isolated from cooling towers, hot springs, and potable water systems in China.

    Science.gov (United States)

    Qin, Tian; Zhou, Haijian; Ren, Hongyu; Guan, Hong; Li, Machao; Zhu, Bingqing; Shao, Zhujun

    2014-04-01

    Legionella pneumophila serogroup 1 causes Legionnaires' disease. Water systems contaminated with Legionella are the implicated sources of Legionnaires' disease. This study analyzed L. pneumophila serogroup 1 strains in China using sequence-based typing. Strains were isolated from cooling towers (n = 96), hot springs (n = 42), and potable water systems (n = 26). Isolates from cooling towers, hot springs, and potable water systems were divided into 25 sequence types (STs; index of discrimination [IOD], 0.711), 19 STs (IOD, 0.934), and 3 STs (IOD, 0.151), respectively. The genetic variation among the potable water isolates was lower than that among cooling tower and hot spring isolates. ST1 was the predominant type, accounting for 49.4% of analyzed strains (n = 81), followed by ST154. With the exception of two strains, all potable water isolates (92.3%) belonged to ST1. In contrast, 53.1% (51/96) and only 14.3% (6/42) of cooling tower and hot spring, respectively, isolates belonged to ST1. There were differences in the distributions of clone groups among the water sources. The comparisons among L. pneumophila strains isolated in China, Japan, and South Korea revealed that similar clones (ST1 complex and ST154 complex) exist in these countries. In conclusion, in China, STs had several unique allelic profiles, and ST1 was the most prevalent sequence type of environmental L. pneumophila serogroup 1 isolates, similar to its prevalence in Japan and South Korea.

  9. Antibiotic resistance patterns of Escherichia coli strains isolated from surface water and groundwater samples in a pig production area

    Directory of Open Access Journals (Sweden)

    Roger Neto Schneider

    2009-09-01

    Full Text Available The use of antibiotics, so excessive and indiscriminate in intensive animal production, has triggered an increase in the number of resistant microorganisms which can be transported to aquatic environments. The aim of this study was to determine the profile of the antimicrobial resistance of samples of Escherichia coli isolated from groundwater and surface water in a region of pig breeding. Through the test of antimicrobial susceptibility, we analyzed 205 strains of E. coli. A high rate of resistance to cefaclor was observed, both in surface water (51.9% and groundwater (62.9%, while all samples were sensitive to amikacin. The percentages of multi-resistant samples were 25.96% and 26.73% in surface water and groundwater, respectively, while 19.23% and 13.86% were sensitive to all antibiotics tested. It was determined that the rate of multiple antibiotic resistance (MAR was 0.164 for surface water and 0.184 for groundwater. No significant differences were found in the profile of the antimicrobial resistance in strains of E. coli isolated in surface water and groundwater, but the index MAR calculated in certain points of groundwater may offer a potential risk of transmission of resistant genes.

  10. Hydrophobic fluorine mediated switching of the hydrogen bonding site as well as orientation of water molecules in the aqueous mixture of monofluoroethanol: IR, molecular dynamics and quantum chemical studies.

    Science.gov (United States)

    Mondal, Saptarsi; Biswas, Biswajit; Nandy, Tonima; Singh, Prashant Chandra

    2017-09-20

    The local structures between water-water, alcohol-water and alcohol-alcohol have been investigated for aqueous mixtures of ethanol (ETH) and monofluoroethanol (MFE) by the deconvolution of IR bands in the OH stretching region, molecular dynamics simulation and quantum chemical calculations. It has been found that the addition of a small amount of ETH into the aqueous medium increases the strength of the hydrogen bonds between water molecules. In an aqueous mixture of MFE, the substitution of a single fluorine induces a change in the orientation as well as the hydrogen bonding site of water molecules from the oxygen to the fluorine terminal of MFE. The switching of the hydrogen bonding site of water in the aqueous mixture of MFE results in comparatively strong hydrogen bonds between MFE and water molecules as well as less clustering of water molecules, unlike the case of the aqueous mixture of ETH. These findings about the modification of a hydrogen bond network by the hydrophobic fluorine group probably make fluorinated molecules useful for pharmaceutical as well as biological applications.

  11. Symposium report: the Waters Bioanalysis World Tour: the broadening impact and future of the DMPK laboratory--addressing large-molecule therapeutics.

    Science.gov (United States)

    De Vooght-Johnson, Ryan

    2011-03-01

    An evening symposium was held at the Museu de Historia de Catalunya (Barcelona, Spain) as a precursor to the European Bioanalysis Forum meeting, as part of the Waters Corporation Bioanalysis World Tour. The symposium was chaired by Robert Plumb and Jing Lin (Waters Corporation, MA, USA) with a focus on the future of the DMPK laboratory and its role in addressing large-molecule therapeutics and biomarkers. Lieve Dillen (Johnson and Johnson, Belgium) spoke on ultra-sensitive peptide quantification, Richard Kay (Quotient Bioresearch, UK) discussed quantifying proteins and peptides in plasma, Ian Wilson (AstraZeneca, UK) covered metabolic biomarkers and Robert Plumb concluded the evening with a presentation on the future of MS in DMPK studies. Following the presentations, all the speakers took questions from the audience and continued lively discussion over a cocktails and canapés reception.

  12. In-situ X-ray diffraction reveals the degradation of crystalline CH3NH3PbI3 by water-molecule collisions at room temperature

    Science.gov (United States)

    Hada, Masaki; Hasegawa, Yoichi; Nagaoka, Ryota; Miyake, Tomoya; Abdullaev, Ulugbek; Ota, Hiromi; Nishikawa, Takeshi; Yamashita, Yoshifumi; Hayashi, Yasuhiko

    2018-02-01

    We have developed a vacuum-compatible chamber for in-situ X-ray diffraction (XRD) studies and have used it to characterize the changing crystal structure of an inorganic-organic hybrid perovskite material, CH3NH3PbI3 (MAPbI3), during interactions with water vapor at room temperature. In the XRD spectra, we have observed the degradation of MAPbI3 and the creation of MAPbI3 hydrates, which follow simple rate equations. The time constant for the degradation of MAPbI3 during accelerated aging suggests that multiple collisions of water molecules with the MAPbI3 crystal trigger the degradation of the crystal.

  13. Echinicola shivajiensis sp. nov., a novel bacterium of the family "Cyclobacteriaceae" isolated from brackish water pond

    Digital Repository Service at National Institute of Oceanography (India)

    Srinivas, T.N.R.; Tryambak, B.K.; AnilKumar, P.

    Strain AK12 sup(T), an orange pigmented Gramnegative, rod shaped, non-motile bacterium, was isolated fromamud sample collected froma brackishwater pond at Rampur of West Bengal, India. The strain was positive for oxidase, catalase and phosphatase...

  14. Recovery of a Burkholderia thailandensis-like isolate from an Australian water source

    Directory of Open Access Journals (Sweden)

    Wilkins Patricia P

    2008-04-01

    Full Text Available Abstract Background Burkholderia thailandensis, a close relative of Burkholderia pseudomallei, has previously been reported only from Southeast Asia and North America. It is biochemically differentiated from B. pseudomallei by the ability to utilize arabinose. During the course of environmental sampling for B. pseudomallei in the Northern Territory of Australia, an isolate, MSMB 43, was recovered that is arabinose positive. Results Genetic analysis using 16S rDNA sequencing and DNA/DNA hybridization indicates that MSMB 43 is most similar to B. thailandensis although multi-locus sequence typing indicates that this isolate is divergent from both B. pseudomallei and other described B. thailandensis. Conclusion We report the isolation and initial characterization of strain MSMB 43, which is a B. thailandensis-like isolate recovered in Australia.

  15. Isolation of rapid growing mycobacteria from soil and water in Iran

    African Journals Online (AJOL)

    USER

    2010-06-14

    Jun 14, 2010 ... an abundant occurrence of mycobacteria in low pH (P value = 0001). We also ..... between large numbers of mycobacterial and high soil acidity as ... (2002). Chlorine disinfection of atypical mycobacteria isolated from a.

  16. Effect of Topical Administration of Fractions and Isolated Molecules from Plant Extracts on Skin Wound Healing: A Systematic Review of Murine Experimental Models

    Directory of Open Access Journals (Sweden)

    Mariáurea Matias Sarandy

    2016-01-01

    Full Text Available Background and Purpose. Skin wound healing is a dynamic process driven by molecular events responsible for the morphofunctional repair of the injured tissue. In a systematic review, we analyzed the relevance of plant fractions and isolates on skin wound healing. By revising preclinical investigations with murine models, we investigated if the current evidence could support clinical trials. Methods. Studies were selected in the MEDLINE/PubMed and Scopus databases according to the PRISMA statement. All 32 identified studies were submitted to data extraction and the methodological bias was investigated according to ARRIVE strategy. Results. The studies demonstrated that plant fractions and isolates are able to modulate the inflammatory process during skin wound healing, being also effective in attenuating the oxidative tissue damage in the scar tissue and stimulating cell proliferation, neoangiogenesis, collagen synthesis, granulation tissue expansion, reepithelialization, and the wound closure rate. However, we identified serious methodological flaws in all studies, such as the high level of reporting bias and absence of standardized experimental designs, analytical methods, and outcome measures. Conclusion. Considering these limitations, the current evidence generated from flawed methodological animal studies makes it difficult to determine the relevance of herbal medicines to treat skin wounds and derails conducting clinical studies.

  17. Ligand uptake in Mycobacterium tuberculosis truncated hemoglobins is controlled by both internal tunnels and active site water molecules [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Ignacio Boron

    2015-07-01

    Full Text Available Mycobacterium tuberculosis, the causative agent of human tuberculosis, has two proteins belonging to the truncated hemoglobin (trHb family. Mt-trHbN presents well-defined internal hydrophobic tunnels that allow O2 and •ŸNO to migrate easily from the solvent to the active site, whereas Mt-trHbO possesses tunnels interrupted by a few bulky residues, particularly a tryptophan at position G8. Differential ligand migration rates allow Mt-trHbN to detoxify Ÿ•NO, a crucial step for pathogen survival once under attack by the immune system, much more efficiently than Mt-trHbO. In order to investigate the differences between these proteins, we performed experimental kinetic measurements, Ÿ•NO decomposition, as well as molecular dynamics simulations of the wild type Mt-trHbN and two mutants, VG8F and VG8W. These mutations affect both the tunnels accessibility as well as the affinity of distal site water molecules, thus modifying the ligand access to the iron. We found that a single mutation allows Mt-trHbN to acquire ligand migration rates comparable to those observed for Mt-trHbO, confirming that ligand migration is regulated by the internal tunnel architecture as well as by water molecules stabilized in the active site.

  18. Pandemic serotypes of Vibrio cholerae isolated from ships' ballast tanks and coastal waters: assessment of antibiotic resistance and virulence genes (tcpA and ctxA).

    Science.gov (United States)

    Dobbs, Fred C; Goodrich, Amanda L; Thomson, Frank K; Hynes, Wayne

    2013-05-01

    There is concern that ships' ballasting operations may disseminate Vibrio cholerae to ports throughout the world. Given evidence that the bacterium is indeed transported by ships, we isolated pandemic serotypes O1 and O139 from ballast tanks and characterized them with respect to antibiotic resistance and virulence genes ctxA and tcpA. We carried out concurrent studies with V. cholerae isolated from coastal waters. Of 284 isolates, 30 were serotype O1 and 59 were serotype O139. These serotypes were overrepresented in ballast tanks relative to the coastal waters sampled. All locations, whether coastal waters or ballast tanks, yielded samples from which serotype O1, O139, or both were isolated. There were three groups among the 62 isolates for which antibiotic characterization was conclusive: those exhibiting β-lactamase activity and resistance to at least one of the 12 antibiotics tested; those negative for β-lactamase but having antibiotic resistance; those negative for β-lactamase and registering no antibiotic resistance. When present, antibiotic resistance in nearly all cases was to ampicillin; resistance to multiple antibiotics was uncommon. PCR assays revealed that none of the isolates contained the ctxA gene and only two isolates, one O139 and one O1, contained the tcpA gene; both isolates originated from ballast water. These results support the bacteriological regulations proposed by the International Maritime Association for discharged ballast water.

  19. Prevalence of antibiotic resistance in bacteria isolated from drinking well water available in Guinea-Bissau (West Africa).

    Science.gov (United States)

    Machado, A; Bordalo, A A

    2014-08-01

    The dissemination of antibiotic-resistant bacteria and the spread of antibiotic resistance genes are a major public health concern worldwide, being even proposed as emerging contaminants. The aquatic environment is a recognized reservoir of antibiotic resistant bacteria, and antibiotic resistance genes have been recently detected in drinking water. In this study, the water quality and the prevalence of antibiotic resistance of heterotrophic culturable bacteria were characterized seasonally in wells that serve the population of Guinea-Bissau (West Africa) as the sole source of water for drinking and other domestic proposes. The results revealed that well water was unfit for human consumption independently of the season, owing to high acidity and heavy fecal contamination. Moreover, potentially pathogenic bacteria, which showed resistance to the most prescribed antibiotics in Guinea-Bissau, were isolated from well water, posing an additional health risk. Our results suggest that well water not only fosters the transmission of potential pathogenic bacteria, but also represents an important reservoir for the proliferation of antibiotic resistant bacteria, that can aggravate the potential to cause disease in a very vulnerable population that has no other alternative but to consume such water. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Correlation between mechanical behavior of protein films at the air/water interface and intrinsic stability of protein molecules

    NARCIS (Netherlands)

    Martin, A.H.; Cohen Stuart, M.A.; Bos, M.A.; Vliet, T. van

    2005-01-01

    The relation between mechanical film properties of various adsorbed protein layers at the air/water interface and intrinsic stability of the corresponding proteins is discussed. Mechanical film properties were determined by surface deformation in shear and dilation. In shear, fracture stress, σf,

  1. Fault Diagnosis Of A Water For Injection System Using Enhanced Structural Isolation

    DEFF Research Database (Denmark)

    Laursen, Morten; Blanke, Mogens; Düstegör, Dilek

    2008-01-01

    A water for injection system supplies chilled sterile water as solvent to pharmaceutical products. There are ultimate requirements to the quality of the sterile water, and the consequence of a fault in temperature or in flow control within the process may cause loss of one or more batches...

  2. Adhesion molecules

    CERN Document Server

    Preedy, Victor R

    2016-01-01

    This book covers the structure and classification of adhesion molecules in relation to signaling pathways and gene expression. It discusses immunohistochemical localization, neutrophil migration, and junctional, functional, and inflammatory adhesion molecules in pathologies such as leukocyte decompression sickness and ischemia reperfusion injury. Highlighting the medical applications of current research, chapters cover diabetes, obesity, and metabolic syndrome; hypoxia; kidney disease; smoking, atrial fibrillation, and heart disease, the brain and dementia; and tumor proliferation. Finally, it looks at molecular imaging and bioinformatics, high-throughput technologies, and chemotherapy.

  3. Different distribution patterns of ten virulence genes in Legionella reference strains and strains isolated from environmental water and patients.

    Science.gov (United States)

    Zhan, Xiao-Yong; Hu, Chao-Hui; Zhu, Qing-Yi

    2016-04-01

    Virulence genes are distinct regions of DNA which are present in the genome of pathogenic bacteria and absent in nonpathogenic strains of the same or related species. Virulence genes are frequently associated with bacterial pathogenicity in genus Legionella. In the present study, an assay was performed to detect ten virulence genes, including iraA, iraB, lvrA, lvrB, lvhD, cpxR, cpxA, dotA, icmC and icmD in different pathogenicity islands of 47 Legionella reference strains, 235 environmental strains isolated from water, and 4 clinical strains isolated from the lung tissue of pneumonia patients. The distribution frequencies of these genes in reference or/and environmental L. pneumophila strains were much higher than those in reference non-L. pneumophila or/and environmental non-L. pneumophila strains, respectively. L. pneumophila clinical strains also maintained higher frequencies of these genes compared to four other types of Legionella strains. Distribution frequencies of these genes in reference L. pneumophila strains were similar to those in environmental L. pneumophila strains. In contrast, environmental non-L. pneumophila maintained higher frequencies of these genes compared to those found in reference non-L. pneumophila strains. This study illustrates the association of virulence genes with Legionella pathogenicity and reveals the possible virulence evolution of non-L. pneumophia strains isolated from environmental water.

  4. Production and characterization of protonated molecular clusters containing a given number of water molecules with the DIAM set-up

    International Nuclear Information System (INIS)

    Bruny, G.

    2010-01-01

    nano-scale characterization of irradiation in bio-molecular systems requires observation of novel features which are now achievable with the recent technical progress. This work is a central part in the development of DIAM which is a new experimental set-up devoted to irradiation of bio-molecular clusters at the Institut de Physique Nucleaire de Lyon. The development of the cluster source and of a double focusing mass spectrometer leads to the production of intense beams of mass selected protonated molecular clusters. Combined with this mass selected cluster beams an innovative detection technique is demonstrated in collision induced dissociation experiments. The results contribute to the knowledge of the stability and the structure of the small protonated water clusters and mixed clusters of water and pyridine. (author)

  5. Ab initio calculations of dissociative excitation of water and methane molecules upon electron impact at low energies

    International Nuclear Information System (INIS)

    Gil, T.J.; McCurdy, C.W.; Rescigno, T.N.; Lengsfield, B.H. III

    1994-01-01

    The authors are reporting results of ab-initio calculations of electron-impact excitation of water and methane occurring at scattering energies up to 60 eV. The authors consider dissociative excited states of both systems since the understanding of their chemistry has considerable importance in plasma technology and atmospheric research. In the case of methane the authors are dealing with the promotion of a valence electron into Rydberg orbitals, while in water the excited states have one electron in an antibonding unoccupied valence orbital and support Feshbach resonances. The authors discuss issues related to convergence of the close-coupling expansion in the case of Rydberg excitation, where the authors have coupled up to 16 channels. The practical realization of the calculation within the framework of the complex Kohn variational principle represents merging of quantum chemistry and quantum scattering theory and is also discussed

  6. Atoms, Molecules, and Compounds

    CERN Document Server

    Manning, Phillip

    2007-01-01

    Explores the atoms that govern chemical processes. This book shows how the interactions between simple substances such as salt and water are crucial to life on Earth and how those interactions are predestined by the atoms that make up the molecules.

  7. Linear Alkylbenzene Sulfonate tolerance in bacteria isolated from sediment of tropical water bodies polluted with detergents

    Directory of Open Access Journals (Sweden)

    I.T Kehinde

    2008-12-01

    Full Text Available The discharge of untreated detergent-bearing waste introduces linear alkylbenzene sulfonates (LAS to the aquatic environment. The surfactant persists in some streams and rivers in Nigeria, some is adsorbed to suspended materials and end in the sediment of the receiving water bodies. In this study, bacteria isolated from sediments of some tropical detergent-effluent-polluted streams were tested for tolerance to LAS using the media dilution technique. LAS-tolerance was indicated by growth of the bacteria in the presence of the surfactant. The pH, concentrations of surfactant, population of heterotrophic bacteria and population of LAS-tolerant bacteria in the sediments were determined. A direct relationship (r= 0.9124 was found between the alkaline conditions (pH= 8.2-12.0 and high surfactant concentrations (45-132 mg/g in the sediment. The sediments harboured a high population and a wide variety of bacteria; the populations of viable heterotrophic bacteria (vHB: 2.9×10(5 to 1.2×10(7 cfu/g and LAS tolerant bacteria (LTB: 1.5×10(4 to 1.2×10(6 cfu/g had a direct relationship (r= 0.9500. An inverse relationship resulted between each of them and the concentration of surfactant in the sediment, r vHB/ LAS = -0.9303 and rLTB/ LAS = -0.9143, respectively. Twelve bacteria species were isolated from the sediment: Alcaligenes odorans, Bacillus subtilis, Burkholderia cepacia, Citrobacter freundii, Citrobacter diversus, Escherichia coli, Micrococcus luteus, Micrococcus albus, Pseudomonas putida, Pseudomonas stutzeri, Staphylococcus aureus and Streptococcus faecalis. Most of them were adapted to the surfactant with their maximum acceptable concentrations ranging between 0.03 and >1.0% (w/v. The sediments could serve as source of adapted organisms which can be used in bio-treatment of LAS-bearing waste. Rev. Biol. Trop. 56 (4:7-15. Epub 2008 December 12.La descarga de desechos que contienen detergentes liberan sulfonatos de alquibenceno lineal (LAS al

  8. Marinobacter salarius sp. nov. and Marinobacter similis sp. nov., isolated from sea water.

    Directory of Open Access Journals (Sweden)

    Hooi Jun Ng

    Full Text Available Two non-pigmented, motile, Gram-negative marine bacteria designated R9SW1T and A3d10T were isolated from sea water samples collected from Chazhma Bay, Gulf of Peter the Great, Sea of Japan, Pacific Ocean, Russia and St. Kilda Beach, Port Phillip Bay, the Tasman Sea, Pacific Ocean, respectively. Both organisms were found to grow between 4 °C and 40 °C, between pH 6 to 9, and are moderately halophilic, tolerating up to 20% (w/v NaCl. Both strains were found to be able to degrade Tween 40 and 80, but only strain R9SW1T was found to be able to degrade starch. The major fatty acids were characteristic for the genus Marinobacter including C16:0, C16:1ω7c, C18:1ω9c and C18:1ω7c. The G+C content of the DNA for strains R9SW1T and A3d10T were determined to be 57.1 mol% and 57.6 mol%, respectively. The two new strains share 97.6% of their 16S rRNA gene sequences, with 82.3% similarity in the average nucleotide identity (ANI, 19.8% similarity in the in silico genome-to-genome distance (GGD, 68.1% similarity in the average amino acid identity (AAI of all conserved protein-coding genes, and 31 of the Karlin's genomic signature dissimilarity. A phylogenetic analysis showed that R9SW1T clusters with M. algicola DG893T sharing 99.40%, and A3d10T clusters with M. sediminum R65T sharing 99.53% of 16S rRNA gene sequence similarities. The results of the genomic and polyphasic taxonomic study, including genomic, genetic, phenotypic, chemotaxonomic and phylogenetic analyses based on the 16S rRNA, gyrB and rpoD gene sequence similarities, the analysis of the protein profiles generated using MALDI-TOF mass spectrometry, and DNA-DNA relatedness data, indicated that strains R9SW1T and A3d10(T represent two novel species of the genus Marinobacter. The names Marinobacter salarius sp. nov., with the type strain R9SW1(T ( =  LMG 27497(T  =  JCM 19399(T  =  CIP 110588(T  =  KMM 7502(T and Marinobacter similis sp. nov., with the type strain A3d10(T (

  9. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 12. Molecule Matters - Dinitrogen. A G Samuelson J Jabadurai. Volume 16 Issue 12 ... Author Affiliations. A G Samuelson1 J Jabadurai1. Department of Inroganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.

  10. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 9. Molecule Matters - A Chromium Compound with a Quintuple Bond. K C Kumara Swamy. Feature Article Volume 11 Issue 9 September 2006 pp 72-75. Fulltext. Click here to view fulltext PDF. Permanent link:

  11. Degradation of aldrin by bacillus licheniformis, isolated from water and sediment from the Cienaga Grande, Santa Marta, Colombia

    International Nuclear Information System (INIS)

    Sanchez Diazgranados, Jose Gregorio; Henry Lopez, Carlos Andres

    2012-01-01

    The bacterium bacillus licheniformis was isolated from sediment and water samples from estuary lagoon Cienaga Grande de Santa Marta (CGSM), Colombian Caribbean. The aim of the work was to use this microorganism as an alternative in the degradation of organic persistent pollutants. b. licheniformis was able to tolerate aerobic conditions and concentrations of the pesticide organochlorine, aldrin. The test was made during 30 days with 60 ng/l of aldrin in order to evaluate the degradation capacity of this bacterium. Identification and isolation of b. licheniformis was made through morphological (gram test), as well as biochemical characterization (bbl crystal system). Aldrin concentration was determined by gas chromatography. Results show that b. licheniformis had a degradation capacity of 24% from total concentration. Factors like solar light exposition and volatilization had an extra influence of 31% on aldrin degradation.

  12. Draft genome sequence of two Shingopyxis sp. strains H107 and H115 isolated from a chloraminated drinking water distriburion system simulator

    Data.gov (United States)

    U.S. Environmental Protection Agency — Draft genome sequence of two Shingopyxis sp. strains H107 and H115 isolated from a chloraminated drinking water distriburion system simulator. This dataset is...

  13. Hydrologic connectivity between geographically isolated wetlands and surface water systems: A review of select modeling methods

    Science.gov (United States)

    Heather E. Golden; Charles R. Lane; Devendra M. Amatya; Karl W. Bandilla; Hadas Raanan Kiperwas Kiperwas; Christopher D. Knightes; Herbert. Ssegane

    2014-01-01

    Geographically isolated wetlands (GIW), depressional landscape features entirely surrounded by upland areas, provide a wide range of ecological functions and ecosystem services for human well-being. Current and future ecosystem management and decision-making rely on a solid scientific understanding of how hydrologic processes affect these important GIW services and...

  14. Antibiotic susceptibility of Legionella strains isolated from public water sources in Macau and Guangzhou.

    Science.gov (United States)

    Xiong, Lina; Yan, He; Shi, Lei; Mo, Ziyao

    2016-12-01

    The purpose of this study was to investigate the susceptibility of waterborne strains of Legionella to eight antimicrobials commonly used in legionellosis therapy. The minimum inhibitory concentrations (MICs) of 66 environmental Legionella strains, isolated from fountains and cooling towers of public facilities (hotels, schools, and shopping malls) in Macau and Guangzhou, were tested using the microdilution method in buffered yeast extract broth. The MIC 50 /MIC 90 values for erythromycin, cefotaxime (CTX), doxycycline (DOC), minocycline (MIN), azithromycin, ciprofloxacin, levofloxacin (LEV), and moxifloxacin were 0.125/0.5 mg/L, 4/8 mg/L, 8/16 mg/L, 4/8 mg/L, 0.125/0.5 mg/L, 0.031/0.031 mg/L, 0.031/0.031 mg/L, and 0.031/0.062 mg/L, respectively. Legionella isolates were inhibited by either low concentrations of macrolides and fluoroquinolones, or high concentrations of CTX and tetracycline drugs. LEV was the most effective drug against different Legionella species and serogroups of L. pneumophila isolates. The latter were inhibited in decreasing order by MIN > CTX >DOC, while non-L. pneumophila isolates were inhibited by CTX> MIN >DOC. In this study, we evaluated drug resistance of pathogenic bacteria from the environment. This may help predict the emergence of drug resistance, improve patient outcomes, and reduce hospitalization costs.

  15. Indirect Manganese Removal by Stenotrophomonas sp. and Lysinibacillus sp. Isolated from Brazilian Mine Water

    Directory of Open Access Journals (Sweden)

    Natália Rocha Barboza

    2015-01-01

    Full Text Available Manganese is a contaminant in the wastewaters produced by Brazilian mining operations, and the removal of the metal is notoriously difficult because of the high stability of the Mn(II ion in aqueous solutions. To explore a biological approach for removing excessive amounts of aqueous Mn(II, we investigated the potential of Mn(II oxidation by both consortium and bacterial isolates from a Brazilian manganese mine. A bacterial consortium was able to remove 99.7% of the Mn(II. A phylogenetic analysis of isolates demonstrated that the predominant microorganisms were members of Stenotrophomonas, Bacillus, and Lysinibacillus genera. Mn(II removal rates between 58.5% and 70.9% were observed for Bacillus sp. and Stenotrophomonas sp. while the Lysinibacillus isolate 13P removes 82.7%. The catalytic oxidation of Mn(II mediated by multicopper oxidase was not properly detected; however, in all of the experiments, a significant increase in the pH of the culture medium was detected. No aggregates inside the cells grown for a week were found by electronic microscopy. Nevertheless, an energy-dispersive X-ray spectroscopy of the isolates revealed the presence of manganese in Stenotrophomonas sp. and Lysinibacillus sp. grown in K medium. These results suggest that members of Stenotrophomonas and Lysinibacillus genera were able to remove Mn(II by a nonenzymatic pathway.

  16. Putative new heat-stable cytotoxic and enterotoxic factors in culture supernatant of Escherichia coli isolated from drinking water

    Directory of Open Access Journals (Sweden)

    DA Ribeiro

    2011-01-01

    Full Text Available Enteric infections caused by the ingestion of contaminated water, especially by Escherichia coli, are important to define the virulence properties of these bacteria. Due to frequent infantile diarrhea in the city of Ouro Preto, Minas Gerais state, Brazil, the phenotypic and genotypic diarrheagenic properties of E. coli isolated from drinking water were studied. The culture supernatants of 39 (40% among a total of 97 E. coli isolates from drinking water were positive by suckling mouse assay and induced cytotoxic effects on Vero cells. The enterotoxic and cytotoxic activities were present in the fraction with less than 10 kDa and were not lost when heated up to 60°C and 100°C for 30 minutes. PCR assays showed that among these 39 Vero cytotoxigenic E. coli, four (10.2% were positive for ST II (estB and two (5% positive for αHly (hlyA. Gene amplification of SLT (stx 1, stx 2, ST I (estA, LT (eltI, eltII, EAST1 (astA, EHly (enhly and plasmid-encoded enterotoxin (pet were not observed. This heat-stable cytotoxic enterotoxin of E. coli is probably a new putative diarrheagenic virulence factor, as a toxin presenting these characteristics has not yet been described.

  17. Legionella species and serogroups in Malaysian water cooling towers: identification by latex agglutination and PCR-DNA sequencing of isolates.

    Science.gov (United States)

    Yong, Stacey Foong Yee; Goh, Fen-Ning; Ngeow, Yun Fong

    2010-03-01

    In this study, we investigated the distribution of Legionella species in water cooling towers located in different parts of Malaysia to obtain information that may inform public health policies for the prevention of legionellosis. A total of 20 water samples were collected from 11 cooling towers located in three different states in east, west and south Malaysia. The samples were concentrated by filtration and treated with an acid buffer before plating on to BCYE agar. Legionella viable counts in these samples ranged from 100 to 2,000 CFU ml(-1); 28 isolates from the 24 samples were examined by latex agglutination as well as 16S rRNA and rpoB PCR-DNA sequencing. These isolates were identified as Legionella pneumophila serogroup 1 (35.7%), L. pneumophila serogroup 2-14 (39%), L. pneumophila non-groupable (10.7%), L. busanensis, L. gormanii, L. anisa and L. gresilensis. L. pneumophila was clearly the predominant species at all sampling sites. Repeat sampling from the same cooling tower and testing different colonies from the same water sample showed concurrent colonization by different serogroups and different species of Legionella in some of the cooling towers.

  18. A comparison of the mechanisms of photooxidative degradation of organic molecules on irradiated semiconductor powders and in aerated supercritical water

    Energy Technology Data Exchange (ETDEWEB)

    Fox, Marye Anne [Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX (United States)

    1995-08-01

    It is the purpose of this paper to survey evidence that suggests that control of the local environment is important in both heterogeneous TiO{sub 2} photocatalysis and in thermal oxidation reactions taking place in supercritical fluids, i.e. that the expected influences of these very different methods for microcompartmentalization do indeed influence the observed reaction kinetics in an easily observable way. Variations in reaction kinetics and the photophysical properties are described for (1) small semiconductor clusters, including their altered photocatalytic activity in and on inert supports; and (2) molecular probes dispersed within the self-aggregating clusters formed within supercritical water

  19. Matrix isolation study of the interaction between water and the aromatic π-electron system

    International Nuclear Information System (INIS)

    Engdahl, A.; Nelander, B.

    1987-01-01

    The interaction of water (H 2 O, D 2 O, HDO) with toluene, the xylenes, pseudocumene, mesitylene, pentamethylbenzene, and hexamethylbenzene in argon matrices has been studied with infrared spectroscopy. Interaction energy estimates are given. The shapes of the observed absorption bands suggest that water executes a complicated motion relative to the ring plane of the aromatic hydrocarbon. The infrared spectrum of the benzene-water complex has been recorded as a function of temperature in argon, krypton, and nitrogen matrices

  20. Regional water balance for the Waste Isolation Pilot Plant (WIPP) site and surrounding area

    International Nuclear Information System (INIS)

    Hunter, R.L.

    1985-12-01

    The WIPP water-balance study area defined here comprises approx.2000 mi 2 in Eddy and Lea Counties, southeastern New Mexico. Inflows to the study area are precipitation (roughly 1.47 x 10 6 ac-ft/y), surface water (roughly 1.1 x 10 5 ac-ft/y), water imported by municipalities and industries (roughly 3 x 10 4 ac-ft/y), and ground water (volume not estimated). Outflows from the area are evapotranspiration (roughly 1.5 x 10 6 ac-ft/y), surface water (roughly 1.2 x 10 5 ac-ft/y), and possibly some ground water. The volume of surface and ground water in storage in Nash Draw has increased since the beginning of potash refining. Regional ground-water flow in aquifers above the Salado Formation is from the northeast to the southwest, although this pattern is interrupted by Clayton Basin, Nash Draw, and San Simon Swale. The Pecos River is the only important perennial stream. Most of the area has no integrated surface-water drainage. The available data suggest that approx.1600 mi 2 of the study area are hydrologically separate from Nash Draw and the WIPP site. Ground water north of Highway 180 apparently discharges into Clayton Basin and evaporates. Water in San Simon Swale apparently percolates downward and flows to the southeast. Data are inadequate to create a water budget for the Nash Draw-WIPP site hydrologic system alone, although an attempt to do so can provide guidance for further study

  1. Sorption Characteristics of Mixed Molecules of Glutaraldehyde from Water on Mesoporous Acid-Amine Modified Low-Cost Activated Carbon: Mechanism, Isotherm, and Kinetics

    Directory of Open Access Journals (Sweden)

    Mukosha Lloyd

    2015-01-01

    Full Text Available The environmental discharge of inefficiently treated waste solutions of the strong biocide glutaraldehyde (GA from hospitals has potential toxic impact on aquatic organisms. The adsorption characteristics of mixed polarized monomeric and polymeric molecules of GA from water on mesoporous acid-amine modified low-cost activated carbon (AC were investigated. It was found that the adsorption strongly depended on pH and surface chemistry. In acidic pH, the adsorption mechanism was elaborated to involve chemical sorption of mainly hydroxyl GA monomeric molecules on acidic surface groups, while in alkaline pH, the adsorption was elaborated to involve both chemical and physical sorption of GA polymeric forms having mixed functional groups (aldehyde, carboxyl, and hydroxyl on acidic and amine surface groups. The optimum pH of adsorption was about 12 with significant contribution by cooperative adsorption, elucidated in terms of hydrogen bonding and aldol condensation. Freundlich and Dubinin-Radushkevich models were fitted to isotherm data. The adsorption kinetics was dependent on initial concentration and temperature and described by the Elovich model. The adsorption was endothermic, while the intraparticle diffusion model suggested significant contribution by film diffusion. The developed low-cost AC could be used to supplement the GA alkaline deactivation process for efficient removal of residual GA aquatic toxicity.

  2. Water permeability of acinar cell membranes in the isolated perfused rabbit mandibular salivary gland.

    Science.gov (United States)

    Steward, M C; Seo, Y; Rawlings, J M; Case, R M

    1990-01-01

    1. The diffusive water permeability of epithelial cell membranes in the perfused rabbit mandibular salivary gland was measured at 37 degrees C by a 1H nuclear magnetic resonance relaxation method using an extracellular relaxation reagent, gadolinium diethylenetriaminepentaacetic acid (Gd(DTPA)). 2. In glands perfused with a HEPES-buffered solution containing 10 mmol l-1 Gd(DTPA), the spin-lattice (T1) relaxation of the water protons showed two exponential components. The water compartment responsible for the slower component corresponded in magnitude to 71 +/- 5% of the wet weight of the gland, and was attributed to the exchangeable intracellular water of the acinar cells. 3. The rate constant for water efflux from the cells was estimated to be 4.1 +/- 0.1 s-1 which would be consistent with a diffusive membrane permeability (Pd) of approximately 3 x 10(-3) cm s-1. Stimulation with acetylcholine (10(-6) mol l-1) did not cause any detectable change in membrane water permeability. 4. Since the basolateral membrane probably provides the main pathway for water efflux, the osmotic water permeability of this barrier (expressed per gland) was estimated to be less than 6.2 cm3 s-1. This would be insufficient to account for the generation of a near-isosmotic fluid at the flow rates observed during secretion, and suggests that a substantial fraction of the flow of water occurs via a paracellular route. PMID:1966053

  3. Fabrication of PLA/CaCO3 hybrid micro-particles as carriers for water-soluble bioactive molecules.

    Science.gov (United States)

    Kudryavtseva, Valeriya L; Zhao, Li; Tverdokhlebov, Sergei I; Sukhorukov, Gleb B

    2017-09-01

    We propose the use of polylactic acid/calcium carbonate (PLA/CaCO 3 ) hybrid micro-particles for achieving improved encapsulation of water-soluble substances. Biodegradable porous CaCO 3 microparticles can be loaded with wide range of bioactive substance. Thus, the formation of hydrophobic polymeric shell on surface of these loaded microparticles results on encapsulation and, hence, sealing internal cargo and preventing their release in aqueous media. In this study, to encapsulate proteins, we explore the solid-in-oil-in-water emulsion method for fabricating core/shell PLA/CaCO 3 systems. We used CaCO 3 particles as a protective core for encapsulated bovine serum albumin, which served as a model protein system. We prepared a PLA coating using dichloromethane as an organic solvent and polyvinyl alcohol as a surfactant for emulsification; in addition, we varied experimental parameters such as surfactant concentration and polymer-to-CaCO 3 ratio to determine their effect on particle-size distribution, encapsulation efficiency and capsule permeability. The results show that the particle size decreased and the size distribution narrowed as the surfactant concentration increased in the external aqueous phase. In addition, when the CaCO 3 /PLA mass ratio dropped below 0.8, the hybrid micro-particles were more likely to resist treatment by ethylenediaminetetraacetic acid and thus retained their bioactive cargos within the polymer-coated micro-particles. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Formation of the prebiotic molecule NH2CHO on astronomical amorphous solid water surfaces: accurate tunneling rate calculations.

    Science.gov (United States)

    Song, Lei; Kästner, Johannes

    2016-10-26

    Investigating how formamide forms in the interstellar medium is a hot topic in astrochemistry, which can contribute to our understanding of the origin of life on Earth. We have constructed a QM/MM model to simulate the hydrogenation of isocyanic acid on amorphous solid water surfaces to form formamide. The binding energy of HNCO on the ASW surface varies significantly between different binding sites, we found values between ∼0 and 100 kJ mol -1 . The barrier for the hydrogenation reaction is almost independent of the binding energy, though. We calculated tunneling rate constants of H + HNCO → NH 2 CO at temperatures down to 103 K combining QM/MM with instanton theory. Tunneling dominates the reaction at such low temperatures. The tunneling reaction is hardly accelerated by the amorphous solid water surface compared to the gas phase for this system, even though the activation energy of the surface reaction is lower than the one of the gas-phase reaction. Both the height and width of the barrier affect the tunneling rate in practice. Strong kinetic isotope effects were observed by comparing to rate constants of D + HNCO → NHDCO. At 103 K we found a KIE of 231 on the surface and 146 in the gas phase. Furthermore, we investigated the gas-phase reaction NH 2 + H 2 CO → NH 2 CHO + H and found it unlikely to occur at cryogenic temperatures. The data of our tunneling rate constants are expected to significantly influence astrochemical models.

  5. Isolation and identification of the native population bacteria for bioremediation of high levels of arsenic from water resources.

    Science.gov (United States)

    Jebelli, Mohammad Ahmadi; Maleki, Afshin; Amoozegar, Mohammad Ali; Kalantar, Enayatollah; Gharibi, Fardin; Darvish, Neda; Tashayoe, Hamidreza

    2018-04-15

    Health of millions of people is threatened by the risk of drinking arsenic-contaminated water worldwide. Arsenic naturally conflicts with the concept of life, but recent studies showed that some microorganisms use toxic minerals as the source of energy. Hence, the researchers should consider the development of cost-effective and highly productive procedures to remove arsenic. The current study was conducted on a native bacterial population of Seyed-Jalaleddin Spring Kurdistan, Iran. Accordingly, the arsenic amount in water samples was measured >500 μg/L by the two field and in vitro methods. Water samples were transferred to laboratory and cultured on chemically defined medium (CDM) with arsenic salts. A total of 14 native arsenic-resistant bacterial strains were isolated and after providing pure culture and performing biochemical tests, the isolates were identified using polymerase chain reaction (PCR) and 16s rRNA genomic sequencing. The potential of bacterial strains for the biotransformation of arsenic was assessed by the qualitative assessment of AgNO 3 method and efficiency of arsenic speciation was determined for the first time by silver diethyldithiocarbamate (SDDC) method with an error of less than 5%. Among the isolated strains, only strain As-11 and strain As-12 showed arsenic transformation characteristics and were registered in NCBI database by the access numbers KY119262 and KY119261, respectively. Results of the current study indicated that strain As-11 had the potential of biotransformation of As(V) to As(III) and vice versa with the efficiency of 78% and 48%, respectively. On the other hand, strain As-12 had the potential for biotransformation of As(V) to As(III) and vice versa with the efficiency of 28% and 45%, respectively. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Tar removal from biosyngas in the biomass gasification process. (Liquid + liquid) equilibrium {water + solvent (paraxylene and methyl hexadecanoate) + model molecules of tar (benzene, toluene, phenol)}

    International Nuclear Information System (INIS)

    Bassil, Georgio; Mokbel, Ilham; Abou Naccoul, Ramy; Stephan, Juliette; Jose, Jacques; Goutaudier, Christelle

    2012-01-01

    Highlights: ► (Liquid + liquid) equilibria at atmospheric pressure. ► Solubility of benzene (or toluene or phenol) in paraxylene at (303 to 343) K. ► Solubility of benzene (or toluene or phenol) in methyl palmitate or methyl hexadecanoate at (303 to 343) K. ► Correlation of LLE using NRTL model. - Abstract: Tar is generated in the process by the condensation of the gas resulting from biomass gasification. The objective of this work is a contribution to the database on thermodynamic quantity which will be useful at the operation of tar removal from aqueous medium. With this aim, (liquid + liquid) equilibrium of {water + solvent (paraxylene and methyl hexadecanoate) + model molecules of tar (benzene, toluene, phenol)} was studied at temperatures (303.2, 323.2, and 343.2) K. The data obtained were correlated with the non-random two-liquid (NRTL) model.

  7. Emission spectra of the species ablated from a solid target submerged in liquid: vibrational temperature of C2 molecules in water-confined geometry

    International Nuclear Information System (INIS)

    Sakka, Tetsuo; Saito, Kotaro; Ogata, Yukio H.

    2002-01-01

    Emission spectra of C 2 molecules produced at the water-graphite interface by pulsed laser irradiation were obtained at various delay times from the irradiation. Vibrational temperature was determined by the Boltzmann plot based on the vibrational bands in Δν=-1 branch of the Swan system. The results show that it was ca. 5000 K and did not change significantly with the delay time. With increasing the delay time up to ca. 500 ns the signal from the Swan band disappeared before the decrease of the vibrational temperature. The results were explained by the formation of a gas cavity and its collapse at several hundreds of nanoseconds from the laser pulse

  8. Anticipated transient without scram analysis of the simplified boiling water reactor following main steam isolation valve closure with boron injection

    International Nuclear Information System (INIS)

    Khan, H.J.; Cheng, H.S.; Rohatgi, U.S.

    1996-01-01

    The simplified boiling water reactor (SBWR) operating in natural circulation is designed with many passive safety features. An anticipated transient without scram (ATWS) initiated by inadvertent closure of the main steam isolation valve (MSIV) in an SBWR has been analyzed using the RAMONA-4B code of Brookhaven National Laboratory. This analysis demonstrates the predicted performance of the SBWR during an MSIV closure ATWS, followed by shutdown of the reactor through injection of boron into the reactor core from the standby liquid control system

  9. Black yeasts-like fungi isolated from dialysis water in hemodialysis units

    NARCIS (Netherlands)

    Figel, Izabel Cristina; Marangoni, Paulo Roberto Dantas; Tralamazza, Sabina Moser; Vicente, Vânia Aparecida; Dalzoto, Patrícia do Rocio; do Nascimento, Mariana Machado Fidelis; de Hoog, G Sybren; Pimentel, Ida Chapaval

    Hemodialysis in patients with chronic renal failure promotes the removal of toxic substances, water, and minerals from the body and often takes place in specialized clinics. Microbial contamination of dialysis fluid is a serious problem in therapy. One of the sources of contamination is the water

  10. COMPARISON OF MYCOBACTERIUM AVIUM ISOLATES FROM DRINKING WATER AND FROM THE POPULATION SERVED BY THE SYSTEM

    Science.gov (United States)

    Background: Current evidence suggests that drinking water, soil, and produce are potential sources of Mycobacterium avium infections, a pathogen not known to be transmitted person-to-person. Methods: We sampled water during 2000 - 2002 from a large municipal drinking wate...

  11. Sequence Analysis of IncA/C and IncI1 Plasmids Isolated from Multidrug-Resistant Salmonella Newport Using Single-Molecule Real-Time Sequencing.

    Science.gov (United States)

    Cao, Guojie; Allard, Marc; Hoffmann, Maria; Muruvanda, Tim; Luo, Yan; Payne, Justin; Meng, Kevin; Zhao, Shaohua; McDermott, Patrick; Brown, Eric; Meng, Jianghong

    2018-04-05

    Multidrug-resistant (MDR) plasmids play an important role in disseminating antimicrobial resistance genes. To elucidate the antimicrobial resistance gene compositions in A/C incompatibility complex (IncA/C) plasmids carried by animal-derived MDR Salmonella Newport, and to investigate the spread mechanism of IncA/C plasmids, this study characterizes the complete nucleotide sequences of IncA/C plasmids by comparative analysis. Complete nucleotide sequencing of plasmids and chromosomes of six MDR Salmonella Newport strains was performed using PacBio RSII. Open reading frames were assigned using prokaryotic genome annotation pipeline (PGAP). To understand genomic diversity and evolutionary relationships among Salmonella Newport IncA/C plasmids, we included three complete IncA/C plasmid sequences with similar backbones from Salmonella Newport and Escherichia coli: pSN254, pAM04528, and peH4H, and additional 200 draft chromosomes. With the exception of canine isolate CVM22462, which contained an additional IncI1 plasmid, each of the six MDR Salmonella Newport strains contained only the IncA/C plasmid. These IncA/C plasmids (including references) ranged in size from 80.1 (pCVM21538) to 176.5 kb (pSN254) and carried various resistance genes. Resistance genes floR, tetA, tetR, strA, strB, sul, and mer were identified in all IncA/C plasmids. Additionally, bla CMY-2 and sugE were present in all IncA/C plasmids, excepting pCVM21538. Plasmid pCVM22462 was capable of being transferred by conjugation. The IncI1 plasmid pCVM22462b in CVM22462 carried bla CMY-2 and sugE. Our data showed that MDR Salmonella Newport strains carrying similar IncA/C plasmids clustered together in the phylogenetic tree using chromosome sequences and the IncA/C plasmids from animal-derived Salmonella Newport contained diverse resistance genes. In the current study, we analyzed genomic diversities and phylogenetic relationships among MDR Salmonella Newport using complete plasmids and chromosome

  12. Attempts to isolate a horizontal high diameter (300 mm nominal diameter) pipeline with an ice plug at minimum water flow and without water flow

    International Nuclear Information System (INIS)

    Corbescu, B.; Gyongyosi, T.; Puiu, D.; Panaitescu, V. N.

    2016-01-01

    The ice plug isolation technique used for high diameter horizontal pipes is used for repair and maintenance activities on hydraulic installations that use liquid working agents. These techniques do not require shutting down the entire plant. The ice plug development inside the pipe requires using custom specialized equipment for each individual application. This paper briefly describes the experimental technological facilities used for conducting the experiments and highlights the important aspects in an experiment conducted on a horizontal NPS 12 testing section running demineralized water followed by the result analysis and conclusions. The paper is dedicated to specialists working in research and technological engineering. (authors)

  13. Draft genome sequence of Bizionia argentinensis, isolated from antarctic surface water

    OpenAIRE

    Lanzarotti, E.; Pellizza, L.; Bercovich, A.; Foti, M.; Coria, S.H.; Vazquez, S.C.; Ruberto, L.; Hernández, E.A.; Dias, R.L.; Mac Cormack, W.P.; Cicero, D.O.; Smal, C.; Nicolas, M.F.; Vasconcelos, A.T.R.; Marti, M.A.

    2011-01-01

    A psychrotolerant marine bacterial strain, designated JUB59 T, was isolated from Antarctic surface seawater and classified as a new species of the genus Bizionia. Here, we present the first draft genome sequence for this genus, which suggests interesting features such as UV resistance, hydrolytic exoenzymes, and nitrogen metabolism. © 2011, American Society for Microbiology. Fil:Pellizza, L. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Mac Cormac...

  14. Isolation, screening and molecular identification of novel bacterial strain removing methylene blue from water solutions

    Science.gov (United States)

    Kilany, Mona

    2017-11-01

    The potentially deleterious effects of methylene blue (MB) on human health drove the interest in its removal promptly. Bioremediation is an effective and eco friendly for removing MB. Soil bacteria were isolated and examined for their potential to remove MB. The most potent bacterial candidate was characterized and identified using 16S rRNA sequence technique. The evolutionary history of the isolate was conducted by maximum likelihood method. Some physiochemical parameters were optimized for maximum decolorization. Decolorization mechanism and microbial toxicity study of MB (100 mg/l) and by-products were investigated. Participation of heat killed bacteria in color adsorption have been investigated too. The bacterial isolate was identified as Stenotrophomonas maltophilia strain Kilany_MB 16S ribosomal RNA gene with 99% sequence similarity. The sequence was submitted to NCBI (Accession number = KU533726). Phylogeny depicted the phylogenetic relationships between 16S ribosomal RNA gene, partial sequence (1442 bp), of the isolated strain and other strains related to Stenotrophomonas maltophilia in the GenBank database. The optimal conditions were investigated to be pH 5 at 30 °C, after 24 h using 5 mg/l MB showing optimum decolorization percentage (61.3%). Microbial toxicity study demonstrated relative reduction in the toxicity of MB decolorized products on test bacteria. Mechanism of color removal was proved by both biosorption and biodegradation, where heat-killed and live cells showed 43 and 52% of decolorization, respectively, as a maximum value after 24-h incubation. It was demonstrated that the mechanism of color removal is by adsorption. Therefore, good performance of S maltophilia in MB color removal reinforces the exploitation of these bacteria in environmental clean-up and restoration of the ecosystem.

  15. Antibiotic resistance and enterotoxin genes in Staphylococcus sp. isolates from polluted water in Southern Brazil

    OpenAIRE

    BASSO, ANA P.; MARTINS, PAULA D.; NACHTIGALL, GISELE; SAND, SUELI VAN DER; MOURA, TIANE M. DE; FRAZZON, ANA PAULA G.

    2014-01-01

    The aim of this study was to evaluate the species distribution, antibiotic-resistance profile and presence of enterotoxin (SE) genes in staphylococci isolated from the Dilúvio stream in South Brazil. Eighty-eight staphylococci were identified, 93.18% were identified as coagulase-negative (CNS) and 6.82% coagulase-positive (CPS). Fourteen Staphylococcus species were detected and the most frequently were Staphylococcus cohnii (30.48%) and S. haemolyticus (21.95%). Resistance to erythromycin was...

  16. Adipose mesenchymal stem cells isolated after manual or water jet-assisted liposuction display similar properties

    Directory of Open Access Journals (Sweden)

    Claire eBony

    2016-01-01

    Full Text Available Mesenchymal stem or stromal cells (MSC are under investigation in many clinical trials for their therapeutic potential in a variety of diseases, including autoimmune and inflammatory disorders. One of the main sources of MSCs is the adipose tissue, which is mainly obtained by manual liposuction using a cannula linked to a syringe. However, in the last years, a number of devices for fat liposuction intended for clinical use have been commercialized but few papers have compared these procedures in terms of stromal vascular fraction (SVF or adipose stromal cells (ASC. The objective of the present study was to compare and qualify for clinical use the adipose stromal cells (ASC obtained from fat isolated with the manual or the Bodyjet® waterjet-assisted procedure. Although the initial number of cells after collagenase digestion was higher with the manual procedure, both the percentage of dead cells, the number of CFU-F and the phenotype of cells were identical in the SVF at isolation and in the ASC populations at day 14. We also showed that the osteogenic and adipogenic differentiation potentials of ASCs were identical between preparations while a slight but significant higher in vitro immunosuppressive effect was observed with ASCs isolated from fat removed with a cannula. The difference in the immunomodulatory effect between ASC populations was however not observed in vivo using the delayed-type hypersensitivity model. Our data therefore indicate that the procedure for fat liposuction does not impact the characteristics or the therapeutic function of ASCs.

  17. Isolation and evaluation of oil-producing microalgae from subtropical coastal and brackish waters.

    Directory of Open Access Journals (Sweden)

    David K Y Lim

    Full Text Available Microalgae have been widely reported as a promising source of biofuels, mainly based on their high areal productivity of biomass and lipids as triacylglycerides and the possibility for cultivation on non-arable land. The isolation and selection of suitable strains that are robust and display high growth and lipid accumulation rates is an important prerequisite for their successful cultivation as a bioenergy source, a process that can be compared to the initial selection and domestication of agricultural crops. We developed standard protocols for the isolation and cultivation for a range of marine and brackish microalgae. By comparing growth rates and lipid productivity, we assessed the potential of subtropical coastal and brackish microalgae for the production of biodiesel and other oil-based bioproducts. This study identified Nannochloropsis sp., Dunaniella salina and new isolates of Chlorella sp. and Tetraselmis sp. as suitable candidates for a multiple-product algae crop. We conclude that subtropical coastal microalgae display a variety of fatty acid profiles that offer a wide scope for several oil-based bioproducts, including biodiesel and omega-3 fatty acids. A biorefinery approach for microalgae would make economical production more feasible but challenges remain for efficient harvesting and extraction processes for some species.

  18. Antibiotic resistance profiles of Escherichia coli isolated from different water sources in the Mmabatho locality, Northwest Province, South Africa

    Directory of Open Access Journals (Sweden)

    C. Njie Ateba

    2010-03-01

    Full Text Available The antibiotic resistance profiles of Escherichia coli (E. coli, isolated from different water sources in the Mmabatho locality were evaluated. Water samples were collected from the local wastewater- and water-treatment plants, the Modimola Dam and homes in the area, and then analysed for the presence of E. coli, using standard methods. Presumptive isolates obtained were confirmed by the analytical profile index test. Antibiotic susceptibility testing was performed by the disc diffusion method. Of the 230 E. coli isolates tested, marked antibiotic resistances (over 70% were observed for erythromycin, tetracycline, ampicillin, chloramphenicol and norfloxacin. Multiple antibiotic resistance patterns were also compiled. Overall, the phenotype T-Ap-E was frequent for E. coli isolated from the local wastewater and water-treatment plants, Modimola Dam and tap water. Cluster analysis performed showed a unique antibiotic resistance pattern which suggested a link between isolates from all sampling points. The findings indicated that improper wastewater treatment may have a potential impact on the dissemination and survival of E. coli, as well as other pathogenic bacteria in water for human and animal consumption. This may result in water- and food-borne disease outbreaks with a negative effect on antibiotic therapy.

  19. Properties of Halococcus salifodinae, an Isolate from Permian Rock Salt Deposits, Compared with Halococci from Surface Waters

    Directory of Open Access Journals (Sweden)

    Helga Stan-Lotter

    2013-02-01

    Full Text Available Halococcus salifodinae BIpT DSM 8989T, an extremely halophilic archaeal isolate from an Austrian salt deposit (Bad Ischl, whose origin was dated to the Permian period, was described in 1994. Subsequently, several strains of the species have been isolated, some from similar but geographically separated salt deposits. Hcc. salifodinae may be regarded as one of the most ancient culturable species which existed already about 250 million years ago. Since its habitat probably did not change during this long period, its properties were presumably not subjected to the needs of mutational adaptation. Hcc. salifodinae and other isolates from ancient deposits would be suitable candidates for testing hypotheses on prokaryotic evolution, such as the molecular clock concept, or the net-like history of genome evolution. A comparison of available taxonomic characteristics from strains of Hcc. salifodinae and other Halococcus species, most of them originating from surface waters, is presented. The cell wall polymer of Hcc. salifodinae was examined and found to be a heteropolysaccharide, similar to that of Hcc. morrhuae. Polyhydroxyalkanoate granules were present in Hcc. salifodinae, suggesting a possible lateral gene transfer before Permian times.

  20. Characterization and Extracellular Enzyme Activity of Predominant Marine Bacillus spp. Isolated From Sea Water of Orissa Coast, India

    Directory of Open Access Journals (Sweden)

    Bal, S.

    2009-01-01

    Full Text Available Bacillus species are ubiquitous and diverse both in the terrestrial and marine ecosystems. In this investigation, predominant Bacillus species from sea water of three different sites of Orissa Coast were isolated and identified. In total, 16 Bacillus species were identified using morpho-physiological and biochemical characterisation. These identified bacterial strains include B. fastidiosus (CMB1, B. alvei (CMB2, B. coagulans (CMB3, B. marinus (CMB5, B. mycoides (CMB8, B. coagulans (PMB1, B. circulans (PMB2, B. cereus (PMB3, B. subtilis (PMB4, B. alcalophilus (GMB1, B. licheniformics (GMB2, B. polymyxa (GMB3 and B. pumilus (GMB4. The isolates CMB4, CMB6 and CMB7 were identified only up to genus level. These isolates were further screened for their salt tolerance and growth under varied temperature and pH conditions. Ability of these strains to produce extracellular enzymes such as protease, amylase, lipase, gelatinase, casein hydrolase, lecithinase, chitinase and pectinase were also screened and found that most of the Bacillus spp. possess extracellular enzymes.

  1. Serratia sp. ZF03: an efficient radium biosorbent isolated from hot-spring waters in high background radiation areas.

    Science.gov (United States)

    Zakeri, Farideh; Noghabi, Kambiz Akbari; Sadeghizadeh, Majid; Kardan, Mohammad Reza; Masoomi, Fatemeh; Farshidpour, Mohammad Reza; Atarilar, Ali

    2010-12-01

    The aim of this study is to isolate and characterize (226)Ra biosorbing indigenous bacterial strains from soils and hot-springs containing high concentrations of (226)Ra by using biochemical and molecular approaches. Fifteen bacteria were isolated and their phylogenetic affiliations were determined based on their 16S rRNA gene and the two most relevant hypervariable regions of this gene; V3 and V6 analysis. A pigmented Serratia sp. ZF03 strain isolated from the water with (226)Ra content of 50471 mBq l(-1), caused 70% removal of (226)Ra at a radioactivity level of 50 Bq ml(-1), after 5 min and 75-80% in equilibrium time of 1 h, depending on the particular biosorption system and experimental conditions studied. The biosorption equilibrium was described by Langmuir and Freundlich isotherm models. Kinetic studies indicated that the biosorption follows pseudo-second-order kinetics. Effect of different physico-chemical parameters on (226)Ra sorption, FTIR, SEM and TEM analysis were also investigated. 2010 Elsevier Ltd. All rights reserved.

  2. Diffusion-weighted magnetic resonance imaging reveals the effects of different cooling temperatures on the diffusion of water molecules and perfusion within human skeletal muscle

    International Nuclear Information System (INIS)

    Yanagisawa, O.; Fukubayashi, T.

    2010-01-01

    Aim: To evaluate the effect of local cooling on the diffusion of water molecules and perfusion within muscle at different cooling temperatures. Materials and methods: Magnetic resonance diffusion-weighted (DW) images of the leg (seven males) were obtained before and after 30 min cooling (0, 10, and 20 o C), and after a 30 min recovery period. Two types of apparent diffusion coefficient (ADC; ADC1, reflecting both water diffusion and perfusion within muscle, and ADC2, approximating the true water diffusion coefficient) of the ankle dorsiflexors were calculated from DW images. T2-weighted images were also obtained to calculate T2 values of the ankle dorsiflexors. The skin temperature was measured before, during, and after cooling. Results: Both ADC values significantly decreased after cooling under all cooling conditions; the rate of decrease depended on the cooling temperature used (ADC1: -36% at 0 o C, -27.8% at 10 o C, and -22.6% at 20 o C; ADC2: -26% at 0 o C, -21.1% at 10 o C, and -14.6% at 20 o C). These significant decreases were maintained during the recovery period. Conversely, the T2 value showed no significant changes. Under all cooling conditions, skin temperature significantly decreased during cooling; the rate of decrease depended on the cooling temperature used (-74.8% at 0 o C, -51.1% at 10 o C, and -26.8% at 20 o C). Decreased skin temperatures were not restored to pre-cooling values during the recovery period under any cooling conditions. Conclusion: Local cooling decreased the water diffusion and perfusion within muscle with decreased skin temperature; the rates of decrease depended on the cooling temperature used. These decreases were maintained for 30 min after cooling.

  3. A support system for water system isolation task of nuclear power plant by using augmented reality and RFID

    International Nuclear Information System (INIS)

    Shimoda, Hiroshi; Ishii, Hirotake; Yamazaki, Yuichiro; Yoshikawa, Hidekazu

    2004-01-01

    Aiming at improvement of task performance and reduction of human error of water system isolation task in NPP periodic maintenance, a support system using state-of-art information technology. Augmented Reality (AR) and Radio Frequency Identification (RFID) has been proposed under the concept of off-site operation and maintenance support center, and a prototype system has been developed. The system has navigation function of which an indication is superimposed directly on the user's view to help to find the designated valves by AR. It also has valve confirmation function by scanning RFID tag attached on the valve. Using the prototype system, an evaluation experiment has been conducted in order to confirm its effectiveness and to reveal its problems. As the result of the experiment, it was found that the system improved efficiency and reliability of water system isolation task, and it was also found that the visibility of HMD and its troublesome feeling to wear were the problems of the system. (author)

  4. Analysis of a main steam isolation value closure anticipated transient without scram in a boiling water reactor

    International Nuclear Information System (INIS)

    Liaw, T.J.; Pan, C.; Chen, G.S.

    1989-01-01

    Anticipated transient without scram (ATWS) could be a major accident sequence with possible core melt and containment damage in a boiling water reactor (BWR). The behavior of a BWR/6 during a main steam isolation valve closure ATWS is investigated using the best-estimate computer program, RETRAN-02. The effects of both makeup coolant and boron injection on the reactor behavior are studied. It is found that the BWR/6 behaves similarly to the BWR/2 and BWR/4. Without boron injection and makeup coolant, the reactor loses its coolant inventory very quickly and the reactor power drops rapidly to ∼ 16% of rated power due to negative void reactivity. With coolant makeup from the high-pressure core spray and the reactor core isolation cooling systems, the rector reaches a quasi-steady-state condition after an initially rapidly changing transient. The dome pressure, downcomer water level, and core power oscillate around a mean value; the average core power is ∼ 15%, which is approximately equal to the power needed to heat and evaporate the subcooled makeup coolant. Lower boron concentrations in the core tend to complicate reactor behavior due to the combination of two competing phenomena: the negative boron reactivity and the positive reactivity caused by a void collapse

  5. A support system for water system isolation task of nuclear power plant by using augmented reality and RFID

    Energy Technology Data Exchange (ETDEWEB)

    Shimoda, Hiroshi; Ishii, Hirotake; Yamazaki, Yuichiro; Yoshikawa, Hidekazu [Kyoto Univ., Graduate School of Energy Science, Uji, Kyoto (Japan)

    2004-07-15

    Aiming at improvement of task performance and reduction of human error of water system isolation task in NPP periodic maintenance, a support system using state-of-art information technology. Augmented Reality (AR) and Radio Frequency Identification (RFID) has been proposed under the concept of off-site operation and maintenance support center, and a prototype system has been developed. The system has navigation function of which an indication is superimposed directly on the user's view to help to find the designated valves by AR. It also has valve confirmation function by scanning RFID tag attached on the valve. Using the prototype system, an evaluation experiment has been conducted in order to confirm its effectiveness and to reveal its problems. As the result of the experiment, it was found that the system improved efficiency and reliability of water system isolation task, and it was also found that the visibility of HMD and its troublesome feeling to wear were the problems of the system. (author)

  6. Identification and characterization of thermotolerant acetic acid bacteria strains isolated from coconut water vinegar in Sri Lanka.

    Science.gov (United States)

    Perumpuli, P A B N; Watanabe, Taisuke; Toyama, Hirohide

    2014-01-01

    From the pellicle formed on top of brewing coconut water vinegar in Sri Lanka, three Acetobacter strains (SL13E-2, SL13E-3, and SL13E-4) that grow at 42 °C and four Gluconobacter strains (SL13-5, SL13-6, SL13-7, and SL13-8) grow at 37 °C were identified as Acetobacter pasteurianus and Gluconobacter frateurii, respectively. Acetic acid production by the isolated Acetobacter strains was examined. All three strains gave 4% acetic acid from 6% initial ethanol at 37 °C, and 2.5% acetic acid from 4% initial ethanol at 40 °C. Compared with the two other strains, SL13E-4 showed both slower growth and slower acetic acid production. As well as the thermotolerant SKU1108 strain, the activities of the alcohol dehydrogenase and the aldehyde dehydrogenase of SL13E-2 and SL13E-4 were more stable than those of the mesophilic strain. The isolated strains were used to produce coconut water vinegar at higher temperatures than typically used for vinegar production.

  7. Ethanol oxidation reactions catalyzed by water molecules: CH3CH2OH+n H2O→ CH3CHO+ H2+n H2O (n=0,1,2)

    Science.gov (United States)

    Takahashi, H.; Hisaoka, S.; Nitta, T.

    2002-09-01

    Ab initio density functional theory calculations have been performed to investigate the catalytic role of water molecules in the oxidation reaction of ethanol: CH3CH2OH+n H2O→ CH3CHO+ H2+n H2O (n=0,1,2) . The results show that the potential energy barrier for the reaction is 88.0 kcal/mol in case of n=0, while it is reduced by ˜34 kcal/mol when two water molecules are involved ( n=2) in the reaction. As a result, the rate constant increases to 3.31×10 -4 s-1, which shows a significant catalytic role of water molecules in the ethanol oxidation reactions.

  8. PHOTOCHEMISTRY IN THE INNER LAYERS OF CLUMPY CIRCUMSTELLAR ENVELOPES: FORMATION OF WATER IN C-RICH OBJECTS AND OF C-BEARING MOLECULES IN O-RICH OBJECTS

    International Nuclear Information System (INIS)

    Agundez, Marcelino; Cernicharo, Jose; Guelin, Michel

    2010-01-01

    A mechanism based on the penetration of interstellar ultraviolet photons into the inner layers of clumpy circumstellar envelopes (CSEs) around asymptotic giant branch stars is proposed to explain the non-equilibrium chemistry observed in such objects. We show through a simple modeling approach that in CSEs with a certain degree of clumpiness or with moderately low mass loss rates (a few 10 -7 M sun yr -1 ) a photochemistry can take place in the warm and dense inner layers, inducing important changes in the chemical composition. In carbon-rich objects water vapor and ammonia would be formed with abundances of 10 -8 -10 -6 relative to H 2 , while in oxygen-rich envelopes ammonia and carbon-bearing molecules such as HCN and CS would form with abundances of 10 -9 -10 -7 relative to H 2 . The proposed mechanism would explain the recent observation of warm water vapor in the carbon-rich envelope IRC+10216 with the Herschel Space Observatory and predict that H 2 O should be detectable in other carbon-rich objects.

  9. Isolation and characterization of aerobic culturable arsenic resistant bacteria from different water sources such as surface water and ground water in Rautahat, Nepal

    International Nuclear Information System (INIS)

    Shakya, S.; Pradhan, B.; Smth, L.; Shrestha, J.; Tuladhar, S.

    2009-01-01

    Arsenicosis is a problem that is primarily caused by the consumption of arsenic-contaminated water. The different surveys have identified that Terai region in Nepal is at risk of ground water arsenic contamination. With the recent adoption of the 50 part per billion (ppb) of Nepal and 10 ppb by United States Environmental protection agency standard for arsenic in drinking water, it has been estimated that the Rautahat has its share of hotspots that exceeds the level in drinking water. (Author)

  10. Isolation and characterization of aerobic culturable arsenic resistant bacteria from different water sources such as surface water and ground water in Rautahat, Nepal

    Energy Technology Data Exchange (ETDEWEB)

    Shakya, S.; Pradhan, B.; Smth, L.; Shrestha, J.; Tuladhar, S.

    2009-07-01

    Arsenicosis is a problem that is primarily caused by the consumption of arsenic-contaminated water. The different surveys have identified that Terai region in Nepal is at risk of ground water arsenic contamination. With the recent adoption of the 50 part per billion (ppb) of Nepal and 10 ppb by United States Environmental protection agency standard for arsenic in drinking water, it has been estimated that the Rautahat has its share of hotspots that exceeds the level in drinking water. (Author)

  11. Characterization of Escherichia coli Isolates from an Urban Lake Receiving Water from a Wastewater Treatment Plant in Mexico City: Fecal Pollution and Antibiotic Resistance.

    Science.gov (United States)

    Rosas, Irma; Salinas, Eva; Martínez, Leticia; Cruz-Córdova, Ariadnna; González-Pedrajo, Bertha; Espinosa, Norma; Amábile-Cuevas, Carlos F

    2015-10-01

    The presence of enteric bacteria in water bodies is a cause of public health concerns, either by directly causing water- and food-borne diseases, or acting as reservoirs for antibiotic resistance determinants. Water is used for crop irrigation; and sediments and aquatic plants are used as fertilizing supplements and soil conditioners. In this work, the bacterial load of several micro-environments of the urban lake of Xochimilco, in Mexico City, was characterized. We found a differential distribution of enteric bacteria between the water column, sediment, and the rhizoplane of aquatic plants, with human fecal bacteria concentrating in the sediment, pointing to the need to assess such bacterial load for each micro-environment, for regulatory agricultural purposes, instead of only the one of the water, as is currently done. Resistance to tetracycline, ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole was common among Escherichia coli isolates, but was also differentially distributed, being again higher in sediment isolates. A distinct distribution of chloramphenicol minimum inhibitory concentrations (MIC) among these isolates suggests the presence of a local selective pressure favoring lower MICs than those of isolates from treated water. Fecal bacteria of human origin, living in water bodies along with their antibiotic resistance genes, could be much more common than typically considered, and pose a higher health risk, if assessments are only made on the water column of such bodies.

  12. The Significant Surface-Water Connectivity of “Geographically Isolated Wetlands”

    Science.gov (United States)

    We evaluated the current literature, coupled with our collective research expertise, on surface-water connectivity of wetlands considered to be “geographically isolated” (sensu Tiner Wetlands 23:494–516, 2003a) to critically assess the scientific foundation of g...

  13. METAL TOLERANCE ANALYSIS OF MICROFUNGI ISOLATED FROM METAL CONTAMINATED SOIL AND WASTE WATER

    Directory of Open Access Journals (Sweden)

    Mathan Jayaraman

    2014-08-01

    Full Text Available The influence of Cr6+, Pb2+, Cu2+, Ni2+, Zn2+ and Cd2+ on the development of 24 fungi was investigated for Metal Tolerance Index (MTI at 1mg ml-1 Cr6+, Pb2+, Cu2+, Ni2+, Zn2+ and Cd2+ concentrations and also for Minimum Inhibitory Concentration (MIC. The MIC ranged from 0.5 to 1.5 mg ml-1 depending on the isolate Aspergillus, Fusarium and Penicillium sp. were tested for their metal tolerance index. Out of these Aspergillus flavus (ED4 shows a better tolerance index of 0.80 Cr6+, 0.72 for Pb2+ , 0.63 for Cu2+, 0.58 for Ni2+, 0.46 for Zn2+ and 0.60 Cd2+ for MIC value for the removal of heavy metals from contaminated soil and wastewaters.

  14. Attosecond dynamics of electrons in molecules and liquids

    Science.gov (United States)

    Woerner, Hans Jakob

    2016-05-01

    The ultrafast motion of electrons and holes following light-matter interaction is fundamental to a broad range of chemical and biophysical processes. In this lecture, I will discuss two recent experiments carried out in our group that measure the atomic-scale motion of charge with attosecond temporal resolution (1 as = 10-18 s). The first experiment is carried out on isolated, spatially oriented molecules in the gas phase. We advance high-harmonic spectroscopy to resolve spatially and temporally the migration of an electron hole immediately following ionization of iodoacetylene, while simultaneously demonstrating extensive control over the process. A multidimensional approach, based on the measurement of both even and odd harmonic orders, enables us to reconstruct both quantum amplitudes and phases of the electronic states with a resolution of ~ 100 as. We separately reconstruct quasi-field-free and laser-controlled charge migration as a function of the spatial orientation of the molecule and determine the shape of the hole created by ionization. The second experiment is carried out on a free-flowing microjet of liquid water. We use an attosecond pulse train synchronized with a near-infrared laser pulse to temporally resolve the process of photoemission from liquid water using the RABBIT technique. We measure a delay on the order of 50 as between electrons emitted from the HOMO of liquid water compared to that of gas-phase water and a substantially reduced modulation contrast of the corresponding sidebands. Since our measurements on solvated water molecules are referenced to isolated ones, the measured delays reflect (i) the photoionization delays caused by electron transport through the aqueous environment and (ii) the effect of solvation on the parent molecule. The relative modulation contrast, in turn, contains information on (iii) the modification of transition amplitudes and (iv) dephasing processes. These experiments make the liquid phase and its fascinating

  15. Biodegradation of partially hydrolyzed polyacrylamide by bacteria isolated from production water after polymer flooding in an oil field

    International Nuclear Information System (INIS)

    Bao Mutai; Chen Qingguo; Li Yiming; Jiang Guancheng

    2010-01-01

    Partially hydrolyzed polyacrylamide (HPAM) in production water after polymer flooding in oil filed causes environmental problems, such as increases the difficulty in oil-water separation, degrades naturally to produce toxic acrylamide and endanger local ecosystem. Biodegradation of HPAM may be an efficient way to solve these problems. The biodegradability of HPAM in an aerobic environment was studied. Two HPAM-degrading bacterial strains, named PM-2 and PM-3, were isolated from the produced water of polymer flooding. They were subsequently identified as Bacillus cereus and Bacillus sp., respectively. The utilization of HPAM by the two strains was explored. The amide group of HPAM could serve as a nitrogen source for the two microorganisms, the carbon backbone of these polymers could be partly utilized by microorganisms. The HPAM samples before and after bacterial biodegradation were analyzed by the infrared spectrum, high performance liquid chromatography and scanning electronic microscope. The results indicated that the amide group of HPAM in the biodegradation products had been converted to a carboxyl group, and no acrylamide monomer was found. The HPAM carbon backbone was metabolized by the bacteria during the course of its growth. Further more, the hypothesis about the biodegradation of HPAM in aerobic bacterial culture is proposed.

  16. Isolation and identification of Vibrio species in the Rio Bravo/Grande and water bodies from Reynosa, Tamaulipas.

    Science.gov (United States)

    Guardiola-Avila, I; Martínez-Vázquez, V; Requena-Castro, R; Juárez-Rendón, K; Aguilera-Arreola, M G; Rivera, G; Bocanegra-García, V

    2018-05-23

    The Rio Bravo (Rio Grande) adjoins various states in the Mexican region and has a great importance in water distribution in the northeast Tamaulipas (Mexico). In this work 161 strains were isolated, identified and characterized from the water samples taken from the flow of the Rio Bravo and the two inner canals that cover Reynosa city. The strains were identified as V. cholerae (74.5%), Vibrio spp. (1.2%) and V. mimicus (0.6%). Furthermore, the detected virulence genes in the V. cholerae strains, were the hlyA, ompU, tcpA, toxR genes in 78.3%, 62.5%, 15.8% and 90.8%, respectively. Only the ompU and vmh genes were detected in the V. mimicus strain. These results indicate the presence of multi-toxigenic V. cholerae strains in the Rio Bravo/Grande and in the water bodies from Reynosa city, which could represent a risk for the exposed population. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  17. Genome Sequence of Legionella massiliensis, Isolated from a Cooling Tower Water Sample.

    Science.gov (United States)

    Pagnier, Isabelle; Croce, Olivier; Robert, Catherine; Raoult, Didier; La Scola, Bernard

    2014-10-16

    We present the draft genome sequence of Legionella massiliensis strain LegA(T), recovered from a cooling tower water sample, using an amoebal coculture procedure. The strain described here is composed of 4,387,007 bp, with a G+C content of 41.19%, and its genome has 3,767 protein-coding genes and 60 predicted RNA genes. Copyright © 2014 Pagnier et al.

  18. Evaluating the Metal Tolerance Capacity of Microbial Communities Isolated from Alberta Oil Sands Process Water.

    Directory of Open Access Journals (Sweden)

    Mathew L Frankel

    Full Text Available Anthropogenic activities have resulted in the intensified use of water resources. For example, open pit bitumen extraction by Canada's oil sands operations uses an estimated volume of three barrels of water for every barrel of oil produced. The waste tailings-oil sands process water (OSPW-are stored in holding ponds, and present an environmental concern as they are comprised of residual hydrocarbons and metals. Following the hypothesis that endogenous OSPW microbial communities have an enhanced tolerance to heavy metals, we tested the capacity of planktonic and biofilm populations from OSPW to withstand metal ion challenges, using Cupriavidus metallidurans, a known metal-resistant organism, for comparison. The toxicity of the metals toward biofilm and planktonic bacterial populations was determined by measuring the minimum biofilm inhibitory concentrations (MBICs and planktonic minimum inhibitory concentrations (MICs using the MBEC ™ assay. We observed that the OSPW community and C. metallidurans had similar tolerances to 22 different metals. While thiophillic elements (Te, Ag, Cd, Ni were found to be most toxic, the OSPW consortia demonstrated higher tolerance to metals reported in tailings ponds (Al, Fe, Mo, Pb. Metal toxicity correlated with a number of physicochemical characteristics of the metals. Parameters reflecting metal-ligand affinities showed fewer and weaker correlations for the community compared to C. metallidurans, suggesting that the OSPW consortia may have developed tolerance mechanisms toward metals present in their environment.

  19. Isolation and characterization of a water stress-specific genomic gene, pwsi 18, from rice.

    Science.gov (United States)

    Joshee, N; Kisaka, H; Kitagawa, Y

    1998-01-01

    One of the water stress-specific cDNA clones of rice characterised previously, wsi18, was selected for further study. The wsi18 gene can be induced by water stress conditions such as mannitol, NaCl, and dryness, but not by ABA, cold, or heat. A genomic clone for wsi18, pwsi18, contained about 1.7 kbp of the 5' upstream sequence, two introns, and the full coding sequence. The 5'-upstream sequence of pwsi18 contained putative cis-acting elements, namely an ABA-responsive element (ABRE), three G-boxes, three E-boxes, a MEF-2 sequence, four direct and two inverted repeats, and four sequences similar to DRE, which is involved in the dehydration response of Arabidopsis genes. The gusA reporter gene under the control of the pwsi18 promoter showed transient expression in response to water stress. Deletion of the downstream DRE-like sequence between the distal G-boxes-2 and -3 resulted in rather low GUS expression.

  20. Phylogenetic Backgrounds and Virulence-Associated Traits of Escherichia coli Isolates from Surface Waters and Diverse Animals in Minnesota and Wisconsin.

    Science.gov (United States)

    Johnson, James R; Johnston, Brian D; Delavari, Parissa; Thuras, Paul; Clabots, Connie; Sadowsky, Michael J

    2017-12-15

    Possible external reservoirs for extraintestinal pathogenic Escherichia coli (ExPEC) strains that cause infections in humans are poorly defined. Because of the tremendous human health importance of ExPEC infections, we assessed surface waters and domesticated and wild animals in Minnesota and Wisconsin as potential reservoirs of ExPEC of human health relevance. We characterized 595 E. coli isolates (obtained from 1999 to 2002; 280 from seven surface water sites, 315 from feces of 13 wild and domesticated animal species) for phylogroup and virulence genotype, including inferred ExPEC status, by using multiplex PCR-based methods. We also compared the pulsed-field gel electrophoresis (PFGE) profiles of the isolates with a large private PFGE profile library. We found a predominance of non-ExPEC strains (95% and 93% among water and animal isolates, respectively), which were mainly from phylogroups A and B1, plus a minority of ExPEC strains (5% and 7% among water isolates and animal isolates, respectively), predominantly from phylogroup B2. The ExPEC strains, although significantly associated with cats, dogs, and turkeys, occurred in several additional animal species (goat, horse, chicken, pig) and were distributed broadly across all surface water sites. Virulence gene content among the animal source ExPEC isolates segregated significantly in relation to host species, following established patterns. PFGE analysis indicated that 11 study isolates closely matched (94% to 100% profile similarity) reference human clinical and fecal isolates. These findings imply what probably is a low but non-zero risk to humans from environmental and animal source E. coli isolates, especially those from specific human-associated animal species. IMPORTANCE Our detection of potentially pathogenic strains that may pose a health threat to humans among E. coli isolates from surface waters and wild and domesticated animals suggests a need for heightened attention to these reservoirs as possible

  1. Molecule Matters van der Waals Molecules

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 12. Molecule Matters van der Waals Molecules - Noble Gas Clusters are London Molecules! E Arunan. Feature Article Volume 14 Issue 12 December 2009 pp 1210-1222 ...

  2. Fluorescent pseudomonads isolated from Hebridean cloud and rain water produce biosurfactants but do not cause ice nucleation

    Science.gov (United States)

    Ahern, H. E.; Walsh, K. A.; Hill, T. C. J.; Moffett, B. F.

    2007-02-01

    Microorganisms were discovered in clouds over 100 years ago but information on bacterial community structure and function is limited. Clouds may not only be a niche within which bacteria could thrive but they might also influence dynamic processes using ice nucleating and cloud condensing abilities. Cloud and rain samples were collected from two mountains in the Outer Hebrides, NW Scotland, UK. Community composition was determined using a combination of amplified 16S ribosomal DNA restriction analysis and sequencing. 256 clones yielded 100 operational taxonomic units (OTUs) of which half were related to bacteria from terrestrial psychrophilic environments. Cloud samples were dominated by a mixture of fluorescent Pseudomonas spp., some of which have been reported to be ice nucleators. It was therefore possible that these bacteria were using the ice nucleation (IN) gene to trigger the Bergeron-Findeisen process of raindrop formation as a mechanism for dispersal. In this study the IN gene was not detected in any of the isolates using both polymerase chain reaction (PCR) and differential scanning calorimetry (DSC). Instead 55% of the total isolates from both cloud and rain samples displayed significant biosurfactant activity when analyzed using the drop-collapse technique. All isolates were characterised as fluorescent pseudomonads. Surfactants have been found to be very important in lowering atmospheric critical supersaturations required for the activation of aerosols into cloud condensation nuclei (CCN). It is also known that surfactants influence cloud droplet size and increase cloud lifetime and albedo. Some bacteria are known to act as CCN and so it is conceivable that these fluorescent pseudomonads are using surfactants to facilitate their activation from aerosols into CCN. This would allow water scavenging,~countering desiccation, and assist in their widespread dispersal.

  3. Isolation and identification of indigenous prokaryotic bacteria from arsenic-contaminated water resources and their impact on arsenic transformation.

    Science.gov (United States)

    Jebelli, Mohammad Ahmadi; Maleki, Afshin; Amoozegar, Mohammad Ali; Kalantar, Enayatollah; Shahmoradi, Behzad; Gharibi, Fardin

    2017-06-01

    Arsenic is a known human carcinogen. Arsenite [As(III), H 3 AsO 3 ] and arsenate [As(V), H 2 AsO 4 - and HAsO 4 2- ] are the two predominant compounds of As found in surface water and groundwater. The aim of this study was to explore a bioremediation strategy for biotransformation of arsenite to arsenate by microorganisms. In this study, Babagorgor Spring, located west of Iran, was selected as the arsenic-contaminated source and its physicochemical characteristics and in situ microbiological composition were analyzed. Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) analysis indicated that the arsenic level was 614μg/l. Fourteen arsenic tolerant indigenous bacteria were isolated from arsenic-contaminated water using chemically defined medium (CDM), supplemented with 260-3900mg/l arsenite and 1560-21800mg/l arsenate. Among the isolates, a strain As-11 exhibited high ability of arsenic transformation. Biochemical tests were used for bacterial identification and confirmation was conducted by 16S rRNA sequence analysis. Results confirmed that As-11 was related to the genus Pseudomonas. This bacterium showed maximum tolerable concentration to arsenite up to 3250mg/l and arsenate up to 20280mg/l. Under heterotrophic conditions, the bacterium exhibited 48% of As(III) and 78% of As(V) transformation from the medium amended with 130 and 312mg/l of sodium arsenite and sodium arsenate, respectively. Moreover, under chemolithotrophic conditions, bacterium was able to transform 41% of 130mg/l of As(III) from the medium amended with nitrate as the terminal electron acceptor. Pseudomonas strain As-11 was reported as an arsenic transformer, for the first time. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Communication: Toward an improved control of the fixed-node error in quantum Monte Carlo: The case of the water molecule

    International Nuclear Information System (INIS)

    Caffarel, Michel; Applencourt, Thomas; Scemama, Anthony; Giner, Emmanuel

    2016-01-01

    All-electron Fixed-node Diffusion Monte Carlo calculations for the nonrelativistic ground-state energy of the water molecule at equilibrium geometry are presented. The determinantal part of the trial wavefunction is obtained from a selected Configuration Interaction calculation [Configuration Interaction using a Perturbative Selection done Iteratively (CIPSI) method] including up to about 1.4 × 10 6 of determinants. Calculations are made using the cc-pCVnZ family of basis sets, with n = 2 to 5. In contrast with most quantum Monte Carlo works no re-optimization of the determinantal part in presence of a Jastrow is performed. For the largest cc-pCV5Z basis set the lowest upper bound for the ground-state energy reported so far of −76.437 44(18) is obtained. The fixed-node energy is found to decrease regularly as a function of the cardinal number n and the Complete Basis Set limit associated with exact nodes is easily extracted. The resulting energy of −76.438 94(12) — in perfect agreement with the best experimentally derived value — is the most accurate theoretical estimate reported so far. We emphasize that employing selected configuration interaction nodes of increasing quality in a given family of basis sets may represent a simple, deterministic, reproducible, and systematic way of controlling the fixed-node error in diffusion Monte Carlo.

  5. Communication: Toward an improved control of the fixed-node error in quantum Monte Carlo: The case of the water molecule

    Energy Technology Data Exchange (ETDEWEB)

    Caffarel, Michel; Applencourt, Thomas; Scemama, Anthony [Laboratoire de Chimie et Physique Quantique, CNRS-Université de Toulouse, Toulouse (France); Giner, Emmanuel [Dipartimento di Scienze Chimiche e Farmaceutiche, Universit degli Studi di Ferrara, Ferrara (Italy)

    2016-04-21

    All-electron Fixed-node Diffusion Monte Carlo calculations for the nonrelativistic ground-state energy of the water molecule at equilibrium geometry are presented. The determinantal part of the trial wavefunction is obtained from a selected Configuration Interaction calculation [Configuration Interaction using a Perturbative Selection done Iteratively (CIPSI) method] including up to about 1.4 × 10{sup 6} of determinants. Calculations are made using the cc-pCVnZ family of basis sets, with n = 2 to 5. In contrast with most quantum Monte Carlo works no re-optimization of the determinantal part in presence of a Jastrow is performed. For the largest cc-pCV5Z basis set the lowest upper bound for the ground-state energy reported so far of −76.437 44(18) is obtained. The fixed-node energy is found to decrease regularly as a function of the cardinal number n and the Complete Basis Set limit associated with exact nodes is easily extracted. The resulting energy of −76.438 94(12) — in perfect agreement with the best experimentally derived value — is the most accurate theoretical estimate reported so far. We emphasize that employing selected configuration interaction nodes of increasing quality in a given family of basis sets may represent a simple, deterministic, reproducible, and systematic way of controlling the fixed-node error in diffusion Monte Carlo.

  6. Molecular Properties by Quantum Monte Carlo: An Investigation on the Role of the Wave Function Ansatz and the Basis Set in the Water Molecule

    Science.gov (United States)

    Zen, Andrea; Luo, Ye; Sorella, Sandro; Guidoni, Leonardo

    2014-01-01

    Quantum Monte Carlo methods are accurate and promising many body techniques for electronic structure calculations which, in the last years, are encountering a growing interest thanks to their favorable scaling with the system size and their efficient parallelization, particularly suited for the modern high performance computing facilities. The ansatz of the wave function and its variational flexibility are crucial points for both the accurate description of molecular properties and the capabilities of the method to tackle large systems. In this paper, we extensively analyze, using different variational ansatzes, several properties of the water molecule, namely, the total energy, the dipole and quadrupole momenta, the ionization and atomization energies, the equilibrium configuration, and the harmonic and fundamental frequencies of vibration. The investigation mainly focuses on variational Monte Carlo calculations, although several lattice regularized diffusion Monte Carlo calculations are also reported. Through a systematic study, we provide a useful guide to the choice of the wave function, the pseudopotential, and the basis set for QMC calculations. We also introduce a new method for the computation of forces with finite variance on open systems and a new strategy for the definition of the atomic orbitals involved in the Jastrow-Antisymmetrised Geminal power wave function, in order to drastically reduce the number of variational parameters. This scheme significantly improves the efficiency of QMC energy minimization in case of large basis sets. PMID:24526929

  7. Comparison of Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolates from Drinking Well Water and Pit Latrine Wastewater in a Rural Area of China

    Directory of Open Access Journals (Sweden)

    Hongna Zhang

    2016-01-01

    Full Text Available The present study was conducted to gain insights into the occurrence and characteristics of extended-spectrum beta-lactamase- (ESBL- producing Escherichia coli (E. coli from drinking well water in the rural area of Laiwu, China, and to explore the role of the nearby pit latrine as a contamination source. ESBL-producing E. coli from wells were compared with isolates from pit latrines in the vicinity. The results showed that ESBL-producing E. coli isolates, with the same antibiotic resistance profiles, ESBL genes, phylogenetic group, plasmid replicon types, and enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR fingerprints, were isolated from well water and the nearby pit latrine in the same courtyard. Therefore, ESBL-producing E. coli in the pit latrine may be a likely contributor to the presence of ESBL-producing E. coli in rural well water.

  8. Hydrodistillation-adsorption method for the isolation of water-soluble, non-soluble and high volatile compounds from plant materials.

    Science.gov (United States)

    Mastelić, J; Jerković, I; Blazević, I; Radonić, A; Krstulović, L

    2008-08-15

    Proposed method of hydrodistillation-adsorption (HDA) on activated carbon and hydrodistillation (HD) with solvent trap were compared for the isolation of water-soluble, non-soluble and high volatile compounds, such as acids, monoterpenes, isothiocyanates and others from carob (Certonia siliqua L.), rosemary (Rosmarinus officinalis L.) and rocket (Eruca sativa L.). Isolated volatiles were analyzed by GC and GC/MS. The main advantages of HDA method over ubiquitous HD method were higher yields of volatile compounds and their simultaneous separation in three fractions that enabled more detail analyses. This method is particularly suitable for the isolation and analysis of the plant volatiles with high amounts of water-soluble compounds. In distinction from previously published adsorption of remaining volatile compounds from distillation water on activated carbon, this method offers simultaneous hydrodistillation and adsorption in the same apparatus.

  9. Hygroscopic growth of water soluble organic carbon isolated from atmospheric aerosol collected at US national parks and Storm Peak Laboratory

    Science.gov (United States)

    Taylor, Nathan F.; Collins, Don R.; Lowenthal, Douglas H.; McCubbin, Ian B.; Gannet Hallar, A.; Samburova, Vera; Zielinska, Barbara; Kumar, Naresh; Mazzoleni, Lynn R.

    2017-02-01

    Due to the atmospheric abundance and chemical complexity of water soluble organic carbon (WSOC), its contribution to the hydration behavior of atmospheric aerosol is both significant and difficult to assess. For the present study, the hygroscopicity and CCN activity of isolated atmospheric WSOC particulate matter was measured without the compounding effects of common, soluble inorganic aerosol constituents. WSOC was extracted with high purity water from daily high-volume PM2.5 filter samples and separated from water soluble inorganic constituents using solid-phase extraction. The WSOC filter extracts were concentrated and combined to provide sufficient mass for continuous generation of the WSOC-only aerosol over the combined measurement time of the tandem differential mobility analyzer and coupled scanning mobility particle sizer-CCN counter used for the analysis. Aerosol samples were taken at Great Smoky Mountains National Park during the summer of 2006 and fall-winter of 2007-2008; Mount Rainier National Park during the summer of 2009; Storm Peak Laboratory (SPL) near Steamboat Springs, Colorado, during the summer of 2010; and Acadia National Park during the summer of 2011. Across all sampling locations and seasons, the hygroscopic growth of WSOC samples at 90 % RH, expressed in terms of the hygroscopicity parameter, κ, ranged from 0.05 to 0.15. Comparisons between the hygroscopicity of WSOC and that of samples containing all soluble materials extracted from the filters implied a significant modification of the hydration behavior of inorganic components, including decreased hysteresis separating efflorescence and deliquescence and enhanced water uptake between 30 and 70 % RH.

  10. Isolation of Exosome-Like Nanoparticles and Analysis of MicroRNAs Derived from Coconut Water Based on Small RNA High-Throughput Sequencing.

    Science.gov (United States)

    Zhao, Zhehao; Yu, Siran; Li, Min; Gui, Xin; Li, Ping

    2018-03-21

    In this study, the presence of microRNAs in coconut water was identified by real-time polymerase chain reaction (PCR) based on the results of high-throughput small RNA sequencing. In addition, the differences in microRNA content between immature and mature coconut water were compared. A total of 47 known microRNAs belonging to 25 families and 14 new microRNAs were identified in coconut endosperm. Through analysis using a target gene prediction software, potential microRNA target genes were identified in the human genome. Real-time PCR showed that the level of most microRNAs was higher in mature coconut water than in immature coconut water. Then, exosome-like nanoparticles were isolated from coconut water. After ultracentrifugation, some particle structures were seen in coconut water samples using 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate fluorescence staining. Subsequent scanning electron microscopy observation and dynamic light scattering analysis also revealed some exosome-like nanoparticles in coconut water, and the mean diameters of the particles detected by the two methods were 13.16 and 59.72 nm, respectively. In conclusion, there are extracellular microRNAs in coconut water, and their levels are higher in mature coconut water than in immature coconut water. Some exosome-like nanoparticles were isolated from coconut water, and the diameter of these particles was smaller than that of animal-derived exosomes.

  11. Mycobacterium icosiumassiliensis sp. nov., a New Member in the Mycobacterium terrae Complex Isolated from Surface Water in Algeria.

    Science.gov (United States)

    Djouadi, Lydia N; Levasseur, Anthony; Khalil, Jacques Bou; Blanc-Taileur, Caroline; Asmar, Shady; Ghiloubi, Wassila; Natèche, Farida; Drancourt, Michel

    2016-08-01

    An acid-fast, rapidly growing, rod-shaped microorganism designated 8WA6 was isolated from a lake in Algiers, Algeria. The lake water was characterized by a temperature of 18 °C, a pH of 7.82, a copper concentration of 8.6 µg/L, and a cadmium concentration of 0.6 µg/L. First-line molecular identification confirmed the 8WA6 isolate to be a member of the Mycobacterium terrae complex, sharing 99.4 % 16S rRNA gene sequence similarity with M. arupense AR-30097, 98.2 % partial hsp65 gene sequence similarity with M. terrae 28K766, and 97.1 % partial rpoB gene sequence similarity with Mycobacterium sp. FI-05396. Its 4.89-Mb genome exhibits a 66.8 GC % and an average nucleotide identity of 64.5 % with M. tuberculosis, 70.5 % with M. arupense, and 75 % with M. asiaticum. In the M. terrae complex, Mycobacterium 8WA6 was unique in exhibiting growth at 42 °C, negative reaction for nitrate reduction, urease activity and Tween 80 hydrolysis, and a positive reaction for α-glucosidase and β-glucosidase. Its protein profile determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry revealed a unique spectrum similar to M. arupense and M. terrae, exhibiting eleven specific peaks at 3787.791, 4578.019, 6349.630, 6855.638, 7202.310, 8149.608, 8775.257, 10,224.588, 10,484.116, 12,226.379, and 12,636.871 m/z. Minimal inhibitory concentrations (MIC) for antibiotics, determined by microdilution, indicated a broad spectrum resistance, except for rifabutin (MIC, 0.5 g/L) and cefoxitin (MIC, 16 g/L). We concluded that the 8WA6 isolate is a representative isolate of a previously undescribed species in the M. terrae complex, which was named M. icosiumassiliensis sp. nov. with strain 8WA6 (Collection de Souches de l'Unité des Rickettsies, CSUR P1561, Deutsche Sammlung von Mikroorganismen und Zellkulturen, DSM 100711) as the type strain.

  12. Hangman Catalysis for Photo–and Photoelectro–Chemical Activation of Water Proton-Coupled Electron Transfer Mechanisms of Small Molecule Activation

    Energy Technology Data Exchange (ETDEWEB)

    Nocera, Daniel G. [Harvard Univ., Cambridge, MA (United States)

    2013-03-15

    The weakest link for the large-scale deployment of solar energy and for that matter, any renewable energy source, is its storage. The energy needs of future society demands are so large that storage must be in the form of fuels owing to their high energy density. Indeed, society has intuitively understood this disparity in energy density as it has developed over the last century as all large-scale energy storage in our society is in the form of fuels. But these fuels are carbon-based. The imperative for the discipline of chemistry, and more generally science, is to develop fuel storage methods that are easily scalable, carbon-neutral and sustainable. These methods demand the creation of catalysts to manage the multi-electron, multi-proton transformations of the conversion of small molecules into fuels. The splitting of water using solar light is a fuel-forming reaction that meets the imperative of large scale energy storage. As light does not directly act on water to engender its splitting into its elemental components, we have designed “hangman” catalysts to effect the energy conversion processes needed for the fuel forming reactions. The hangman construct utilizes a pendant acid/base functionality within the secondary coordination sphere that is “hung” above the redox platform onto which substrate binds. In this way, we can precisely control the delivery of a proton to the substrate, thus ensuring efficient coupling between the proton and electron. An emphasis was on the coupling of electron and proton in the hydrogen evolution reaction (HER) on Ni, Co and Fe porphyrin platforms. Electrokinetic rate laws were developed to define the proton-coupled electron transfer (PCET) mechanism. The HER of Co and Fe porphyrins was metal-centered. Surprisingly, HER this was not the case for Ni porphyrins. In this system, the PCET occurred at the porphyrin platform to give rise to a phlorin. This is one of the first examples of an HER occurring via ligand non

  13. Determination of iodate in iodized salt and water samples by shell-isolated nanoparticle-enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Zhang, Kaige; Liang, Lizhen; Huang, Meiying; Hu, Yuling; Li, Gongke

    2014-01-01

    We have developed a simple, rapid, and sensitive method for the determination of iodate in iodized salt and water samples. The method is making use of shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) and is based on the oxidation of hydroxylammonium chloride by iodate to produce nitrite which then is used to diazotize with p-nitroaniline. The resulting diazonium ion is then coupled to N-(1-naphthyl) ethylenediamine dihydrochloride to form an azo dye whose concentration is determined by SHINERS. The active substrate used in SHINERS is composed of gold nanoparticles coated with an ultrathin silica shell possessing pinholes on their surface. Various factors that influence the chemical reaction and the intensity of SHINERS were investigated. Under the optimal conditions, the Raman intensity is linearly related to the concentration of iodate in the 7.5–130.0 μg L−1 range, with a correlation coefficient of 0.9920. The limit of detection is 2.0 μg L−1, and the relative standard deviation is 7.5 % (for n = 5) at 1,138 cm−1 without additional sample pre-concentration. The method was successfully applied to the determination of iodate in iodized salt and water samples. The accuracy was assessed through recovery tests and independent analysis by a conventional titrimetric method. (author)

  14. Pathogenic Escherichia coli producing Extended-Spectrum β-Lactamases isolated from surface water and wastewater.

    Science.gov (United States)

    Franz, Eelco; Veenman, Christiaan; van Hoek, Angela H A M; de Roda Husman, Ana; Blaak, Hetty

    2015-09-24

    To assess public health risks from environmental exposure to Extended-Spectrum β-Lactamases (ESBL)-producing bacteria, it is necessary to have insight in the proportion of relative harmless commensal variants and potentially pathogenic ones (which may directly cause disease). In the current study, 170 ESBL-producing E. coli from Dutch wastewater (n = 82) and surface water (n = 88) were characterized with respect to ESBL-genotype, phylogenetic group, resistance phenotype and virulence markers associated with enteroaggregative E. coli (EAEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), extraintesinal E. coli (ExPEC), and Shiga toxin-producing E. coli (STEC). Overall, 17.1% of all ESBL-producing E. coli were suspected pathogenic variants. Suspected ExPECs constituted 8.8% of all ESBL-producing variants and 8.3% were potential gastrointestinal pathogens (4.1% EAEC, 1.8% EPEC, 1.2% EIEC, 1.2% ETEC, no STEC). Suspected pathogens were significantly associated with ESBL-genotype CTX-M-15 (X(2) = 14.7, P antibiotics. In conclusion, this study demonstrates that the aquatic environment is a potential reservoir of E. coli variants that combine ESBL-genes, a high level of multi-drug resistance and virulence factors, and therewith pose a health risk to humans upon exposure.

  15. Molecule-by-Molecule Writing Using a Focused Electron Beam

    DEFF Research Database (Denmark)

    Van Dorp, Willem F.; Zhang, Xiaoyan; Feringa, Ben L.

    2012-01-01

    atoms also be written with an electron beam? We verify this with focused electron-beam-induced deposition (FEBID), a direct-write technique that has the current record for the smallest feature written by (electron) optical lithography. We show that the deposition of an organometallic precursor...... on graphene can be followed molecule-by-molecule with FEBID. The results show that mechanisms that are inherent to the process inhibit a further increase in control over the process. Hence, our results present the resolution limit of (electron) optical lithography techniques. The writing of isolated...

  16. Diversity and antibiograms of bacterial organisms isolated from samples of household drinking-water consumed by HIV-positive individuals in rural settings, South Africa.

    Science.gov (United States)

    Samie, A; Mashao, M B; Bessong, P O; NKgau, T F; Momba, M N B; Obi, C L

    2012-09-01

    Diarrhoea is a hallmark of HIV infections in developing countries, and many diarrhoea-causing agents are often transmitted through water. The objective of the study was to determine the diversity and antibiotic susceptibility profiles of bacterial organisms isolated from samples of household drinking-water consumed by HIV-infected and AIDS patients. In the present study, household water stored for use by HIV-positive patients was tested for microbial quality, and isolated bacterial organisms were analyzed for their susceptibility profiles against 25 different antibiotics. The microbial quality of water was generally poor, and about 58% of water samples (n=270) were contaminated with faecal coliforms, with counts varying from 2 colony-forming unit (CFU)/100 mL to 2.4x10⁴ CFU/100 mL. Values of total coliform counts ranged from 17 CFU/100 mL to 7.9x10⁵/100 mL. In total, 37 different bacterial species were isolated, and the major isolates included Acinetobacter lwoffii (7.5%), Enterobacter cloacae (7.5%), Shigella spp. (14.2%), Yersinia enterocolitica (6.7%), and Pseudomonas spp. (16.3%). No Vibrio cholerae could be isolated; however, V. fluvialis was isolated from three water samples. The isolated organisms were highly resistant to cefazolin (83.5%), cefoxitin (69.2%), ampicillin (66.4%), and cefuroxime (66.2%). Intermediate resistance was observed against gentamicin (10.6%), cefepime (13.4%), ceftriaxone (27.6%), and cefotaxime (29.9%). Levofloxacin (0.7%), ceftazidime (2.2%), meropenem (3%), and ciprofloxacin (3.7%) were the most active antibiotics against all the microorganisms, with all recording less than 5% resistance. Multiple drug resistance was very common, and 78% of the organisms were resistant to three or more antibiotics. Education on treatment of household water is advised for HIV-positive patients, and measures should be taken to improve point-of-use water treatment as immunosuppressed individuals would be more susceptible to opportunistic

  17. Tahibacter aquaticus gen. nov., sp. nov., a new gammaproteobacterium isolated from the drinking water supply system of Budapest (Hungary).

    Science.gov (United States)

    Makk, Judit; Homonnay, Zalán G; Kéki, Zsuzsa; Lejtovicz, Zsuzsanna; Márialigeti, Károly; Spröer, Cathrin; Schumann, Peter; Tóth, Erika M

    2011-04-01

    Three Gram-stain negative, aerobic, non-motile, non-spore-forming, rod-shaped bacterial strains, PYM5-11(T), RaM5-2 and PYM5-8, were isolated from the drinking water supply system of Budapest (Hungary) and their taxonomic positions were investigated by a polyphasic approach. All three strains grew optimally at 20-28°C and pH 5-7 without NaCl. The G+C content of the DNA of the type strain was 65.4mol%. On the basis of 16S rRNA gene sequence analysis, the isolates showed 94.5-94.9% sequence similarity to the type strain of Dokdonella koreensis and a similarity of 93.0-94.1% to the species of the genera Aquimonas and Arenimonas. The major isoprenoid quinone of the strains was ubiquinone Q-8. The predominant fatty acids were iso-C(15:0), iso-C(17:1)ω9c, C(16:1)ω7c, and C(16:0). Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylmonomethylethanolamine, as well as several unidentified aminolipids and phospholipids were present. The 16S rRNA gene sequence analysis, the predominant fatty acids, the polar lipid composition, RiboPrint patterns, physiological and biochemical characteristics showed that the three strains were related but distinct from the type strains of the four recognized species of the genus Dokdonella, and indicated that the strains represented a new genus within the Gammaproteobacteria. The strain PYM5-11 (=DSM 21667(T)=NCAIM B 02337(T)) is proposed as the type strain of a new genus and species, designated as Tahibacter aquaticus gen. nov., sp. nov. Copyright © 2010 Elsevier GmbH. All rights reserved.

  18. Isolation, identification, screening of toxicity and oligopeptides of some marine and brackish cyanobacteria from Norwegian and Pakistani waters, in the search for bioactive natural compounds

    OpenAIRE

    Hameed, Shaista

    2009-01-01

    Cyanobacteria produce a number of bioactive compounds, most of them are oligopeptides. Almost all are known from freshwater species. The aim of this study was to search for marine and brackish water species producing bioactive compounds. To reach this goal, new strains were isolated from Norwegian and Pakistani coastal waters. These and additional strains from NIVA, UiO and UiB culture collections (24 in total), belonging to Chroococcales and Oscillatoriales, were identified based on morpholo...

  19. Antibiotics Susceptibility Profile of Listeria Species Isolated from Poultry Wastes and Fishpond Water from Private and Institutional Farms in Ibadan, Nigeria

    OpenAIRE

    Olutayo Israel Falodun; Moturayo Janet Amusan

    2017-01-01

    Introduction: Untreated waste being discharged into the environment due to proliferation of poultry and fish farms can constitute a public health threat to human. Listeria, an emerging pathogen is commonly associated with food. This study aimed at determining the antibiotic resistant pattern of Listeria species isolated from poultry droppings and fish pond water in Ibadan. Materials and Methods: Poultry waste and fishpond water samples were collected between April and July, 2016. Listeria...

  20. Water sources as reservoirs of Vibrio cholerae O1 and non-O1 strains in Bepanda, Douala (Cameroon): relationship between isolation and physico-chemical factors.

    Science.gov (United States)

    Akoachere, Jane-Francis Tatah Kihla; Mbuntcha, Christelle Kwedjeu Pulcherie

    2014-07-30

    Cholera has been endemic in Douala since 1971. Most outbreaks start from Bepanda, an overcrowded neighbourhood with poor hygiene and sanitary conditions. We investigated water sources in Bepanda as reservoirs of Vibrio cholerae, the causative agent of cholera, determined its antibiotic susceptibility and some physico-chemical characteristics that could maintain the endemicity of this organism in Bepanda. Three hundred and eighteen water samples collected from 45 wells, 8 taps and 1 stream from February to July 2009 were analyzed for V. cholerae using standard methods. Isolates were characterized morphologically, biochemically and serologically. The disc diffusion technique was employed to investigate antibiotic susceptibility. Differences in prevalence of organism between seasons were analysed. Correlation strength and direction of association between physico-chemical parameters and occurrence of V. cholerae was analyzed using the Kendall tau_b non-parametric correlation. This was further confirmed with the forward-stepwise binary logistic regression. Eighty-seven (27.4%) samples were positive for V. cholerae. Isolation was highest from wells. The organism was isolated in the rainy season and dry season but the frequency of isolation was significantly higher (χ2 = 7.009, df = 1, P = 0.008) in the rainy season. Of the 96 confirmed V. cholerae isolates, 32 (33.3%) belonged to serogroup O1 and 64 (66.6%) were serogroup non-O1/non-O139. Isolates from tap (municipal water) were non-O1/non-O139 strains. Salinity had a significant positive correlation with isolation in the dry season (+0.267, P = 0.015) and rainy season (+0.223, P = 0.028). The forward-stepwise method of binary logistic regression indicated that as pH (Wald = 11.753, df = 1), P = 0.001) increased, odds of isolation of V. cholerae also increased (B = 1.297, S.E = 0.378, Exp(B) = 3.657). All isolates were sensitive to ciprofloxacin and ofloxacin. Multi-drug resistance was predominant among the non-O1/non

  1. Variable-Number Tandem-Repeat Analysis of Respiratory and Household Water Biofilm Isolates of “Mycobacterium avium subsp. hominissuis” with Establishment of a PCR Database

    Science.gov (United States)

    Iakhiaeva, Elena; Howard, Susan T.; Brown Elliott, Barbara A.; McNulty, Steven; Newman, Kristopher L.; Falkinham, Joseph O.; Williams, Myra; Kwait, Rebecca; Lande, Leah; Vasireddy, Ravikiran; Turenne, Christine

    2016-01-01

    “Mycobacterium avium subsp. hominissuis” is an important cause of pulmonary disease. It is acquired from environmental sources, but there is no methodology for large population studies. We evaluated the potential of variable-number tandem-repeat (VNTR) analysis. Clinical and household biofilm M. avium isolates underwent molecular identification. Testing for IS901 was done to separate M. avium subsp. avium from M. avium subsp. hominissuis. VNTR types were defined using VNTR loci, and subtyping was performed using 3′ hsp65 and internal transcribed spacer (ITS) sequencing. Forty-nine VNTR types and eight subtypes of M. avium subsp. hominissuis (IS901 negative) were identified among 416 isolates of M. avium from 121 patients and 80 biofilm sites. Of those types, 67% were found only among patient isolates, 11% only among household water isolates, and 23% among both. Of 13 VNTR types that included ≥4 patients, the majority (61.5%) represented geographic clustering (same city). Most VNTR types with multiple patients belonged to the same 3′ hsp65 sequence code (sequevar). A total of 44 isolates belonging to four M. avium subsp. hominissuis VNTR types (8%), including three with the rare Mav-F ITS sequence and 0/8 subspecies, produced amplicons with IS901 PCR primers. By sequencing, all 44 amplicons were not IS901 but ISMav6, which was recently observed in Japan but had not been previously described among U.S. isolates. VNTR analysis of M. avium subsp. hominissuis isolates is easier and faster than pulsed-field gel electrophoresis. Seven VNTR loci separated 417 isolates into 49 types. No isolates of M. avium subsp. avium were identified. The distributions of the VNTR copy numbers, the allelic diversity, and the low prevalence of ISMav6 differed from the findings for respiratory isolates reported from Japan. PMID:26739155

  2. Isolation and Selection of Microalgal Strains from Natural Water Sources in Viet Nam with Potential for Edible Oil Production.

    Science.gov (United States)

    Thao, Tran Yen; Linh, Dinh Thi Nhat; Si, Vo Chi; Carter, Taylor W; Hill, Russell T

    2017-06-23

    Industrial vegetable oil production in Viet Nam depends on oil seeds and crude plant oils that are currently more than 90% imported. As the first step in investigating the feasibility of using microalgae to provide Viet Nam with a domestic source of oil for food and edible oil industries, fifty lipid-producing microalgae were isolated and characterized. The microalgae were isolated from water sources ranging from freshwater to brackish and marine waters from a wide geographic distribution in Viet Nam. Initial analyses showed that 20 of the 50 strains had good growth rates, produced high biomass and had high lipid content, ranging up to 50% of dry weight biomass. 18S rRNA gene sequence analyses of the 50 strains showed a great diversity in this assemblage of microalgae, comprising at least 38 species and representatives of 25 genera : Chlamydomonas , Poterioochromonas , Scenedesmus , Desmodesmus , Chlorella , Bracteacoccus , Monoraphidium , Selenastrum , Acutodesmus , Mychonastes , Ankistrodesmus , Kirchneriella , Raphidocelis , Dictyosphaerium , Coelastrella , Schizochlamydella , Oocystidium , Nannochloris , Auxenochlorella , Chlorosarcinopsis , Stichococcus , Picochlorum , Prasinoderma , Chlorococcum , and Marvania. Some of the species are closely related to well-known lipid producers such as Chlorella sorokiniana , but some other strains are not closely related to the strains found in public sequence databases and likely represent new species. Analysis of oil quality showed that fatty acid profiles of the microalgal strains were very diverse and strain-dependent. Fatty acids in the microalgal oils comprised saturated fatty acids (SFAs), poly-unsaturated fatty acids (PUFAs), and mono-unsaturated fatty acids (MUFAs). The main SFA was palmitic acid. MUFAs and PUFAs were dominated by oleic acid, and linoleic and linolenic acids, respectively. Some strains were especially rich in the essential fatty acid α-linolenic acid (ALA), which comprised more than 20% of the

  3. Characterization of Enterococcus species isolated from marine recreational waters by MALDI-TOF MS and Rapid ID API® 20 Strep system.

    Science.gov (United States)

    Christ, Ana Paula Guarnieri; Ramos, Solange Rodrigues; Cayô, Rodrigo; Gales, Ana Cristina; Hachich, Elayse Maria; Sato, Maria Inês Zanoli

    2017-05-15

    MALDI-TOF Mass Spectrometry Biotyping has proven to be a reliable method for identifying bacteria at the species level based on the analysis of the ribosomal proteins mass fingerprint. We evaluate the usefulness of this method to identify Enterococcus species isolated from marine recreational water at Brazilian beaches. A total of 127 Enterococcus spp. isolates were identified to species level by bioMérieux's API® 20 Strep and MALDI-TOF systems. The biochemical test identified 117/127 isolates (92%), whereas MALDI identified 100% of the isolates, with an agreement of 63% between the methods. The 16S rRNA gene sequencing of isolates with discrepant results showed that MALDI-TOF and API® correctly identified 74% and 11% of these isolates, respectively. This discrepancy probably relies on the bias of the API® has to identify clinical isolates. MALDI-TOF proved to be a feasible approach for identifying Enterococcus from environmental matrices increasing the rapidness and accuracy of results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Mariniradius saccharolyticus gen. nov., sp. nov., a member of the family Cyclobacteriaceae isolated from marine aquaculture pond water, and emended descriptions of the genus Aquiflexum and Aquiflexum balticum

    Digital Repository Service at National Institute of Oceanography (India)

    Bhumika, V.; Srinivas, T.N.R.; Ravinder, K.; AnilKumar, P.

    A novel marine, Gram-stain-negative, oxidase- and catalase- positive, rod-shaped bacterium, designated strain AK6 sup(T), was isolated from marine aquaculture pond water collected in Andhra Pradesh, India. The fatty acids were dominated by iso-C sub...

  5. Determining the potential link between irrigation water quality and the microbiological quality of onions by phenotypic and genotypic characterization of Escherichia coli isolates.

    Science.gov (United States)

    du Plessis, Erika M; Duvenage, Francois; Korsten, Lise

    2015-04-01

    The potential transfer of human pathogenic bacteria present in irrigation water onto fresh produce was investigated, because surface water sources used for irrigation purposes in South Africa have increasingly been reported to be contaminated with enteric bacterial pathogens. A microbiological analysis was performed of a selected river in Limpopo Province, South Africa, that is often contaminated with raw sewage from municipal sewage works and overhead irrigated onions produced on a commercial farm. Counts of Escherichia coli, coliforms, aerobic bacteria, fungi, and yeasts and the prevalence of E. coli O157:H7, Salmonella, and Listeria monocytogenes were determined. Identities of bacterial isolates from irrigation water and onions were confirmed using matrix-assisted laser desorption ionization-time of flight mass spectrometry, PCR, and biochemical tests. To establish a potential link between the microbiological quality of the irrigation source and the onions, the E. coli isolates from both were subjected to antibiotic resistance, virulence gene, and enterobacterial repetitive intergenic consensus PCR analyses. River water E. coli counts exceeded South African Department of Water Affairs and World Health Organization irrigation water guidelines. Counts of aerobic bacteria, coliforms, fungi, and yeasts of onions from the market were acceptable according to Department of Health Directorate, Food Control, South Africa, microbiological guidelines for ready-to-eat fresh fruits and vegetables. E. coli O157:H7, Salmonella, and L. monocytogenes were not detected in onions, whereas only Salmonella was detected in 22% of water samples. Matrix-assisted laser desorption ionization-time of flight mass spectrometry and PCR identification of E. coli isolates from water and onions correlated. Of the 45 E. coli isolates from water and onions, 42.2% were resistant to multiple antibiotics. Virulence genes eae, stx1, and stx2 were detected in 2.2, 6.6, and 2.2% of the E. coli isolates

  6. Coal induced production of a rhamnolipid biosurfactant by Pseudomonas stutzeri, isolated from the formation water of Jharia coalbed.

    Science.gov (United States)

    Singh, Durgesh Narain; Tripathi, Anil Kumar

    2013-01-01

    A strain of Pseudomonas stutzeri was isolated form an enrichment of perchlorate reducing bacteria from the formation water collected from an Indian coalbed which solubilized coal and produced copious amount of biosurfactant when coal was added to the medium. It produced maximum biosurfactant with lignite coal followed by olive oil and soybean oil which was able to emulsify several aromatic hydrocarbons including kerosene oil, diesel oil, hexane, toluene etc. Haemolytic test, growth inhibition of Bacillus subtilis and FTIR analysis showed rhamnolipid nature of the biosurfactant. The stability of the coal induced biosurfactant in pH range of 4-8 and up to 25% NaCl concentration and 100 °C temperature suggests that due to its ability to produce biosurfactant and solubilize coal P. stutzeri may be useful in the coalbed for in situ biotransformation of coal into methane and in the bioremediation of PAHs from oil contaminated sites including marine environments. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Channels with ordered water and bipyridine molecules in the porous coordination polymer {[Cu(SiF6(C10H8N22]·2C10N2H8·5H2O}n

    Directory of Open Access Journals (Sweden)

    Emmanuel Aubert

    2016-11-01

    Full Text Available The coordination polymer {[Cu(SiF6(C10H8N22]·2C10H8N2·5H2O}n, systematic name: poly[[bis(μ2-4,4′-bipyridine(μ2-hexafluoridosilicatocopper(II] 4,4′-bipyridine disolvate pentahydrate], contains pores which are filled with water and 4,4′-bipyridine molecules. As a result of the presence of these ordered species, the framework changes its symmetry from P4/mmm to P21/c. The 4,4′-bipyridine guest molecules form chains inside the 6.5 × 6.9 Å pores parallel to [100] in which the molecules interact through π–π stacking. Ordered water molecules form infinite hydrogen-bonded chains inside a second pore system (1.6 × 5.3 Å free aperture perpendicular to the 4,4′-bipyridine channels.

  8. Molecule Matters van der Waals Molecules

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 7. Molecule Matters van der Waals Molecules - Rg•••HF Complexes are Debye Molecules! E Arunan. Feature Article Volume 15 Issue 7 July 2010 pp 667-674. Fulltext. Click here to view fulltext PDF. Permanent link:

  9. Effects of temperature, water activity and incubation time on fungal growth and aflatoxin B1 production by toxinogenic Aspergillus flavus isolates on sorghum seeds.

    Science.gov (United States)

    Lahouar, Amani; Marin, Sonia; Crespo-Sempere, Ana; Saïd, Salem; Sanchis, Vicente

    2016-01-01

    Sorghum, which is consumed in Tunisia as human food, suffers from severe colonization by several toxigenic fungi and contamination by mycotoxins. The Tunisian climate is characterized by high temperature and humidity that stimulates mold proliferation and mycotoxin accumulation in foodstuffs. This study investigated the effects of temperature (15, 25 and 37°C), water activity (aw, between 0.85 and 0.99) and incubation time (7, 14, 21 and 28 d) on fungal growth and aflatoxin B1 (AFB1) production by three Aspergillus flavus isolates (8, 10 and 14) inoculated on sorghum grains. The Baranyi model was applied to identify the limits of growth and mycotoxin production. Maximum diameter growth rates were observed at 0.99 a(w) at 37°C for two of the isolates. The minimum aw needed for mycelial growth was 0.91 at 25 and 37°C. At 15°C, only isolate 8 grew at 0.99 a(w). Aflatoxin B1 accumulation could be avoided by storing sorghum at low water activity levels (≤0.91 a(w)). Aflatoxin production was not observed at 15°C. This is the first work on the effects of water activity and temperature on A. flavus growth and AFB1 production by A. flavus isolates on sorghum grains. Copyright © 2015 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  10. Isolation of a bacteria of the Bacillus genus as indicator in the disinfection of residual waters by means of the ionizing radiation (e- , γ)

    International Nuclear Information System (INIS)

    Mata J, M.

    2003-01-01

    The pollutants of the water can be chemical, physical and biological. Among those biological we find to the microorganisms: bacterias, virus and protozoa. These cause important infections in many countries, mainly of Latin America. With the advance of the technology and the quick demographic growth, the biological pollution of the water has already become an important topic since it would damage the public health and it causes that their disinfection has greater attention. In the treatment of residual waters three basic treatments exist the one primary, secondary and tertiary; in this last we find the disinfection, which can be taken to end by chemical and physical methods. For this work of investigation it was used the ionizing radiation, because it is an innovative technology that it eliminates microorganisms in residual waters. The investigation consisted on treating, samples of residual water after the biological treatment of the plant RECICLAGUA with ionizing radiation (electrons and gammas), for the case of electrons it was used the dose of 0.5 kGy and for gamma the dose, of 5 kGy, later the survivor bacteria was isolated to these doses in both cases and they were carried out the tests of identification. In accordance with the obtained results can say that it is about a B. subtilis. The isolated B.subtilis was presented as a pollutant of the flora of the residual water, having a greater survival to the dose of 0.5 and 5 kGy with electrons and gammas, respectively that other present polluting microorganisms in the samples of residual water. For it fits signalize that this microorganism shows characteristics as it easy isolation and identification, the presence with pathogen microorganisms and a greater survival when being irradiated, therefore it can use as indicator in the disinfection of residual waters through ionizing radiation (electrons and gammas). (Author)

  11. Energy storage and redistribution in molecules

    International Nuclear Information System (INIS)

    Hinze, J.

    1983-01-01

    This book presents information on the following topics: chemistry and spectroscopy of molecules at high levels of excitation; energy and phase randomization in large molecules as probed by laser spectroscopy; intramolecular processes in isolated polyatomic molecules; pulse-probe measurements in low-temperature, low-pressure SF 6 ; the photodissociation dynamics of H 2 S and CF 3 NO; photofragment spectroscopy of the NO 2 dissociation; preparation, laser spectroscopy and predissociation of alkali dimers in supersonic nozzle beams; excited states of small molecules - collisional quenching and photodissociation; quantum-state-resolved scattering of lithium hydride; and molecular negative ions

  12. Genotypic and phenotypic diversity of Ralstonia pickettii and Ralstonia insidiosa isolates from clinical and environmental sources including High-purity Water.

    LENUS (Irish Health Repository)

    Ryan, Michael P

    2011-08-30

    Abstract Background Ralstonia pickettii is a nosocomial infectious agent and a significant industrial contaminant. It has been found in many different environments including clinical situations, soil and industrial High Purity Water. This study compares the phenotypic and genotypic diversity of a selection of strains of Ralstonia collected from a variety of sources. Results Ralstonia isolates (fifty-nine) from clinical, industrial and environmental origins were compared genotypically using i) Species-specific-PCR, ii) PCR and sequencing of the 16S-23S rRNA Interspatial region (ISR) iii) the fliC gene genes, iv) RAPD and BOX-PCR and v) phenotypically using biochemical testing. The species specific-PCR identified fifteen out of fifty-nine designated R. pickettii isolates as actually being the closely related species R. insidiosa. PCR-ribotyping of the 16S-23S rRNA ISR indicated few major differences between the isolates. Analysis of all isolates demonstrated different banding patterns for both the RAPD and BOX primers however these were found not to vary significantly. Conclusions R. pickettii species isolated from wide geographic and environmental sources appear to be reasonably homogenous based on genotypic and phenotypic characteristics. R. insidiosa can at present only be distinguished from R. pickettii using species specific PCR. R. pickettii and R. insidiosa isolates do not differ significantly phenotypically or genotypically based on environmental or geographical origin.

  13. Prevalence and antibiotic resistance of Pseudomonas aeruginosa in water samples in central Italy and molecular characterization of oprD in imipenem resistant isolates.

    Science.gov (United States)

    Schiavano, Giuditta Fiorella; Carloni, Elisa; Andreoni, Francesca; Magi, Silvia; Chironna, Maria; Brandi, Giorgio; Amagliani, Giulia

    2017-01-01

    This study aimed to analyse the prevalence, antibiotic resistance and genetic relatedness of P. aeruginosa isolates obtained from potable and recreational water samples (n. 8,351) collected from different settings (swimming pools, n. 207; healthcare facilities, n 1,684; accommodation facilities, n. 1,518; municipal waterworks, n. 4,500; residential buildings, n. 235). Possible mechanisms underlying resistance to imipenem, with particular focus on those involving oprD-based uptake, were also explored. Isolation and identification of Pseudomonas aeruginosa was performed according to the standardized procedure UNI EN ISO 16266:2008 followed by PCR confirmation. Antibiotic Susceptibility testing was conducted according to EUCAST standardized disk diffusion method. Genetic relatedness of strains was carried out by RAPD. The sequence of the oprD gene was analyzed by standard method. Fifty-three samples (0.63%) were positive for P. aeruginosa, of which 10/207 (4.83%) were from swimming pools. Five isolates (9.43%) were resistant to imipenem, one to Ticarcillin + Clavulanate, one to both Piperacillin and Ticarcillin + Clavulanate. The highest isolation rate of imipenem resistant P. aeruginosa was observed in swimming pool water. Identical RAPD profiles were found in isolates from the same location in the same year or even in different years. Imipenem resistant strains were identified as carbapenemase-negative and resistance has been associated with inactivating mutations within the oprD gene, with a concomitant loss of porin. RAPD results proved that a water system can remain colonized by one strain for long periods and the contamination may be difficult to eradicate. This study has revealed the presence of P. aeruginosa in different water samples, including resistant strains, especially in swimming pools, and confirmed the role of porins as a contributing factor in carbapenem resistance in Gram-negative bacteria.

  14. Small molecule fluoride toxicity agonists.

    Science.gov (United States)

    Nelson, James W; Plummer, Mark S; Blount, Kenneth F; Ames, Tyler D; Breaker, Ronald R

    2015-04-23

    Fluoride is a ubiquitous anion that inhibits a wide variety of metabolic processes. Here, we report the identification of a series of compounds that enhance fluoride toxicity in Escherichia coli and Streptococcus mutans. These molecules were isolated by using a high-throughput screen (HTS) for compounds that increase intracellular fluoride levels as determined via a fluoride riboswitch reporter fusion construct. A series of derivatives were synthesized to examine structure-activity relationships, leading to the identification of compounds with improved activity. Thus, we demonstrate that small molecule fluoride toxicity agonists can be identified by HTS from existing chemical libraries by exploiting a natural fluoride riboswitch. In addition, our findings suggest that some molecules might be further optimized to function as binary antibacterial agents when combined with fluoride. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Cadmium and zinc response of the fungi Heliscus lugdunensis and Verticillium cf. alboatrum isolated from highly polluted water

    International Nuclear Information System (INIS)

    Jaeckel, Petra; Krauss, Gerd-Joachim; Krauss, Gudrun

    2005-01-01

    The aquatic hyphomycete Heliscus lugdunensis and the terrestrial fungus Verticillium cf. alboatrum, both isolated from a highly polluted surface water, were investigated for their tolerance against Cd and Zn. Hl-H4 showed a 50% growth inhibition at 0.1 mM Cd, whereas at 0.7 mM Cd the growth of Va-H4 was only reduced by 30%. The fungi also showed a remarkable difference in their Zn-tolerance. The growth of Va-H4 was not inhibited at 1 mM Zn, whereas for Hl-H4 no growth occurred above 0.3 mM Zn. The biosorption and accumulation capacities for Cd or Zn of both fungi differed between the fungal species. In a 0.1 mM Cd-medium Hl-H4 biosorbed 15-fold and accumulated 39-fold more Cd than Va-H4. Exposure to 0.3 mM Zn resulted in a 13-fold higher biosorption and 11-fold higher accumulation for Hl-H4 than Va-H4. As glutathione (GSH) is known to be involved in the phytochelatin synthesis and other stress related processes we investigated its synthesis. Both fungi increased their synthesis of GSH in response to Cd. For Hl-H4 a concentration of 0.0125 mM Cd, corresponding to an intracellular Cd content of 2.1 nmol Cd mg -1 dw, increased the GSH content, whereas Va-H4 only responded with a higher production of GSH at 1 mM Cd and a concomitant intracellular Cd content of 22.5 nmol Cd mg -1 dw. An increased GSH synthesis under Zn-stress was only detectable for Va-H4 (20 mM)

  16. Isolation By Distance (IBD) signals in the deep-water rose shrimp Parapenaeus longirostris (Lucas, 1846) (Decapoda, Panaeidae) in the Mediterranean Sea.

    Science.gov (United States)

    Lo Brutto, S; Maggio, T; Arculeo, M

    2013-09-01

    The identification of boundaries of genetic demes is one of the major goals for fishery management, and few Mediterranean commercial species have not been studied from a genetic point of view yet. The deep-water rose shrimp Parapenaeus longirostris (Lucas, 1846) is one of the most important components of commercial landings in Mediterranean, its fishery aspects have received much attention, regrettably without any concern for the genetic architecture of its populations. The population structure in the central and eastern Mediterranean Sea (captures from six Italian and two Greek landings) has been analysed on the basis of surveys carried out with mitochondrial and AFLP markers. Data revealed the presence of a gradual discrepancy along a west-east axis. This species, occurring mainly at a depth of between 100 and 400 m, is not strongly confined in isolated demes, but it demonstrates an 'Isolation By Distance' model, within the Mediterranean Sea, which includes geographical areas with a some degree of isolation. The role of hydrodynamic forces, such as currents, water fronts, is discussed; and a further evidence of the 'Levantine isolation' within Mediterranean basin is shown. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Distribution of monoclonal antibody subgroups and sequence-based types among Legionella pneumophila serogroup 1 isolates derived from cooling tower water, bathwater, and soil in Japan.

    Science.gov (United States)

    Amemura-Maekawa, Junko; Kikukawa, Kiyomi; Helbig, Jürgen H; Kaneko, Satoko; Suzuki-Hashimoto, Atsuko; Furuhata, Katsunori; Chang, Bin; Murai, Miyo; Ichinose, Masayuki; Ohnishi, Makoto; Kura, Fumiaki

    2012-06-01

    Legionella pneumophila serogroup (SG) 1 is the most frequent cause of legionellosis. This study analyzed environmental isolates of L. pneumophila SG 1 in Japan using monoclonal antibody (MAb) typing and sequence-based typing (SBT). Samples were analyzed from bathwater (BW; n = 50), cooling tower water (CT; n = 50), and soil (SO; n = 35). The distribution of MAb types varied by source, with the most prevalent types being Bellingham (42%), Oxford (72%), and OLDA (51%) in BW, CT, and SO, respectively. The ratios of MAb 3/1 positive isolates were 26, 2, and 14% from BW, CT, and SO, respectively. The environmental isolates from BW, CT, and SO were divided into 34 sequence types (STs; index of discrimination [IOD] = 0.973), 8 STs (IOD = 0.448), and 11 STs (IOD = 0.879), respectively. Genetic variation among CT isolates was smaller than seen in BW and SO. ST1 accounted for 74% of the CT isolates. The only common STs between (i) BW and CT, (ii) BW and SO, and (iii) CT and SO were ST1, ST129, and ST48, respectively, suggesting that each environment constitutes an independent habitat.

  18. Draft Genome Sequence of Sphingomonas sp. Strain Sph1(2015), Isolated from a Fouled Membrane Filter Used To Produce Drinking Water.

    Science.gov (United States)

    de Vries, Hendrik J; Marshall, Ian P G; Schreiber, Lars; Plugge, Caroline M

    2017-06-15

    We report here the high-quality draft genome sequence of Sphingomonas sp. strain Sph1(2015), isolated from a fouled reverse osmosis membrane used for the production of high-quality drinking water. The draft sequence provides insights into the modus operandi of this strain to form biofilms on membrane surfaces. This knowledge offers tools to develop novel antifouling strategies. Copyright © 2017 de Vries et al.

  19. Draft Genome Sequence of a Clostridium botulinum Isolate from Water Used for Cooling at a Plant Producing Low-Acid Canned Foods.

    Science.gov (United States)

    Basavanna, Uma; Gonzalez-Escalona, Narjol; Timme, Ruth; Datta, Shomik; Schoen, Brianna; Brown, Eric W; Zink, Donald; Sharma, Shashi K

    2013-01-01

    Clostridium botulinum is a pathogen of concern for low-acid canned foods. Here we report draft genomes of a neurotoxin-producing C. botulinum strain isolated from water samples used for cooling low-acid canned foods at a canning facility. The genome sequence confirmed that this strain belonged to C. botulinum serotype B1, albeit with major differences, including thousands of unique single nucleotide polymorphisms (SNPs) compared to other genomes of the same serotype.

  20. Draft Genome Sequence of a Clostridium botulinum Isolate from Water Used for Cooling at a Plant Producing Low-Acid Canned Foods

    OpenAIRE

    Basavanna, Uma; Gonzalez-Escalona, Narjol; Timme, Ruth; Datta, Shomik; Schoen, Brianna; Brown, Eric W.; Zink, Donald; Sharma, Shashi K.

    2013-01-01

    Clostridium botulinum is a pathogen of concern for low-acid canned foods. Here we report draft genomes of a neurotoxin-producing C.?botulinum strain isolated from water samples used for cooling low-acid canned foods at a canning facility. The genome sequence confirmed that this strain belonged to C.?botulinum serotype B1, albeit with major differences, including thousands of unique single nucleotide polymorphisms (SNPs) compared to other genomes of the same serotype.

  1. Serotyping, PCR, phage-typing and antibiotic sensitivity testing of Salmonella serovars isolated from urban drinking water supply systems of Nepal

    DEFF Research Database (Denmark)

    Bhatta, D.R.; Bangtrakulnonth, A.; Tishyadhigama, P.

    2007-01-01

    Aims: To study the occurrence and diversity of Salmonella serovars in urban water supply systems of Nepal. Methods and Results: Occurrence of Salmonella was detected in 42 out of 300 water samples by enrichment culture technique in selenite F broth followed by plating on Salmonella Shigella agar...... isolates of Salm. Enteritidis indicated the presence of one of the ESBL genes, blaSHV, whereas the genes blaTEM and blaCTX were absent. Conclusions: The microbiological quality of the urban water supply is poor and indicates possibility of fatal outbreaks of enteric fever and related infections in Nepal....... Significance and Impact of the Study: The present study will be useful in water borne disease control and prevention strategy formulation in Nepal and in the global context....

  2. Pheno- and genotyping of Brucella abortus biovar 5 isolated from a water buffalo (Bubalus bubalis) fetus: First case reported in the Americas.

    Science.gov (United States)

    Martínez, Diana; Thompson, Carolina; Draghi, Graciela; Canavesio, Vilma; Jacobo, Roberto; Zimmer, Patricia; Elena, Sebastián; Nicola, Ana M; de Echaide, Susana Torioni

    2014-09-17

    An isolate of Brucella spp. from an aborted water buffalo (Bubalus bubalis) fetus was characterized based on its pheno- and genotype. The phenotype was defined by carbon dioxide requirement, hydrogen sulfide production, sensitivity to thionin and basic fuchsin and agglutination with Brucella A and M monospecific antisera. The genotype was based on the amplification of the following genes: bcsp31, omp2ab, and eri and the species-specific localization of the insertion sequence IS711 in the Brucella chromosome via B. abortus-B. melitensis-B. ovis-B. suis (AMOS)-PCR. Unexpectedly, the isolate showed a phenotype different from B. abortus bv 1, the most prevalent strain in cattle in Argentina, and from vaccine strain 19, currently used in bovines and water buffaloes. Genotyping supported the phenotypic results, as the analysis of the omp2ab gene sequence showed an identical pattern to either B. abortus bv 5 or B. melitensis. Finally, the AMOS PCR generated a 1700-bp fragment from the isolate, different than those amplified from B. abortus bv 1 (498bp) and B. melitensis (731bp), confirming the presence of B. abortus bv 5. The OIE/FAO Reference Laboratory for Brucellosis confirmed this typing. This is the first report of B. abortus bv 5 from a water buffalo in the Americas. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Detection of Class I and II integrons for the assessment of antibiotic and multidrug resistance among Escherichia coli isolates from agricultural irrigation waters in Bulacan, Philippines.

    Science.gov (United States)

    Paraoan, Cielo Emar M; Rivera, Windell L; Vital, Pierangeli G

    2017-05-04

    Contaminated irrigation water may greatly affect not only the quality of produce but also the people exposed to it. In this study, agricultural irrigation waters in Bulacan, Philippines were assessed and found to be contaminated with Escherichia coli (E. coli) ranging from 0.58 to 4.51 log 10 CFU/mL. A total of 79 isolates of E. coli were confirmed through polymerase chain reaction (PCR) amplifying the uidA gene and were tested for phenotypic resistance using 10 antimicrobials through the Kirby-Bauer disc diffusion method. Forty-six isolates (58.22%) were noted to be multidrug resistant (MDR) with high resistance rate to cephalothin, tetracycline, streptomycin, ampicillin, trimethoprim, nalidixic acid, and chloramphenicol. Moreover, this study also examined the prevalence of Class I and II integrons accounting to 67.39% and 17.39%, respectively, of the MDR E. coli strains using multiplex PCR. The results imply that the agricultural water used in Bulacan is contaminated with the fecal material of man or other animals present in the area, and the presence of MDR bacteria, which pose a potential threat to individuals in these areas, is alarming. In addition, detection of integrons could be a good marker for the identification of MDR isolates. Lastly, this study could develop strategies for the proper management of farming sites leading to the detection of food-borne pathogens and prevention of infectious diseases.

  4. MOLECULAR COMPARISON OF MYCOBACTERIUM AVIUM ISOLATED FROM A FRINKING WATER DISTRIBUTION SYSTEM AND FROM THE POPULATION SERVED BY THE SYSTEM

    Science.gov (United States)

    There is evidence that drinking water, soil, and produce may be sources of Mycobacterium avium infections, a pathogen not known to be transmitted person-to-person. We sampled water from a large municipal drinking water distribution system in which surface source water is used. M...

  5. Statistical survey of the buried waters in the Protein Data Bank.

    Science.gov (United States)

    Carugo, Oliviero

    2016-01-01

    The structures of buried water molecules were studied in an ensemble of high-quality and non-redundant protein crystal structures. Buried water molecules were clustered and classified in lake-like clusters, which are completely isolated from the bulk solvent, and bay-like clusters, which are in contact with the bulk solvent through a surface water molecule. Buried water molecules are extremely common: lake-like clusters are found in 89 % of the protein crystal structures and bay-like clusters in 93 %. Clusters with only one water molecule are much more common than larger clusters. Both cluster types incline to be surrounded by loop residues, and to a minor extent by residues in extended secondary structure. Helical residues on the contrary do not tend to surround clusters of buried water molecules. One buried water molecule is found every 30-50 amino acid residues, depending on the secondary structures that are more abundant in the protein. Both main- and side-chain atoms are in contact with buried waters; they form four hydrogen bonds with the first water and 1-1.5 additional hydrogen bond for each additional water in the cluster. Consequently, buried water molecules appear to be firmly packed and rigid like the protein atoms. In this regard, it is remarkable to observe that prolines often surround water molecules buried in the protein interior. Interestingly, clusters of buried water molecules tend to be just beneath the protein surface. Moreover, water molecules tend to form a one-dimensional wire rather than more compact arrangements. This agrees with recent evidence of the mechanisms of solvent exchange between internal cavities and bulk solvent.

  6. Osmotically and thermally isolated forward osmosis-membrane distillation (fo-md) integrated module for water treatment applications

    KAUST Repository

    Ghaffour, Noreddine

    2016-09-01

    An integrated forward osmosis-membrane distillation (FO-MD) module and systems and methods incorporating the module is disclosed providing higher efficiencies and using less energy. The FO-MD module is osmotically and thermally isolated. The isolation can prevent mixing of FO draw solution/FO permeate and MD feed, and minimize dilution of FO draw solution and cooling of MD feed. The module provides MD feed solution and FO draw solution streams that flow in the same module but are separated by an isolation barrier. The osmotically and thermally isolated FO-MD integrated module, systems and methods offer higher driving forces of both FO and MD processes, higher recovery, and wider application than previously proposed hybrid FO- MD systems.

  7. Osmotically and thermally isolated forward osmosis-membrane distillation (fo-md) integrated module for water treatment applications

    KAUST Repository

    Ghaffour, NorEddine; Francis, Lijo; Li, Zhenyu; Valladares, Rodrigo; Alsaadi, Ahmad S.; Ghdaib, Muhannad Abu; Amy, Gary L.

    2016-01-01

    An integrated forward osmosis-membrane distillation (FO-MD) module and systems and methods incorporating the module is disclosed providing higher efficiencies and using less energy. The FO-MD module is osmotically and thermally isolated. The isolation can prevent mixing of FO draw solution/FO permeate and MD feed, and minimize dilution of FO draw solution and cooling of MD feed. The module provides MD feed solution and FO draw solution streams that flow in the same module but are separated by an isolation barrier. The osmotically and thermally isolated FO-MD integrated module, systems and methods offer higher driving forces of both FO and MD processes, higher recovery, and wider application than previously proposed hybrid FO- MD systems.

  8. Physical state of poorly water soluble therapeutic molecules loaded into SBA-15 ordered mesoporous silica carriers: a case study with itraconazole and ibuprofen.

    Science.gov (United States)

    Mellaerts, Randy; Jammaer, Jasper A G; Van Speybroeck, Michiel; Chen, Hong; Van Humbeeck, Jan; Augustijns, Patrick; Van den Mooter, Guy; Martens, Johan A

    2008-08-19

    The ordered mesoporous silica material SBA-15 was loaded with the model drugs itraconazole and ibuprofen using three different procedures: (i) adsorption from solution, (ii) incipient wetness impregnation, and (iii) heating of a mixture of drug and SBA-15 powder. The location of the drug molecules in the SBA-15 particles and molecular interactions were investigated using nitrogen adsorption, TGA, DSC, DRS UV-vis, and XPS. The in vitro release of hydrophobic model drugs was evaluated in an aqueous environment simulating gastric fluid. The effectiveness of the loading method was found to be strongly compound dependent. Incipient wetness impregnation using a concentrated itraconazole solution in dichloromethane followed by solvent evaporation was most efficient for dispersing itraconazole in SBA-15. The itraconazole molecules were located on the mesopore walls and inside micropores of the mesopore walls. When SBA-15 was loaded by slurrying it in a diluted itraconazole solution from which the solvent was evaporated, the itraconazole molecules ended up in the mesopores that they plugged locally. At a loading of 30 wt %, itraconazole exhibited intermolecular interactions inside the mesopores revealed by UV spectroscopy and endothermic events traced with DSC. The physical mixing of itraconazole and SBA-15 powder followed by heating above the itraconazole melting temperature resulted in formulations in which glassy itraconazole particles were deposited externally on the SBA-15 particles. Loading with ibuprofen was successful with each of the three loading procedures. Ibuprofen preferably is positioned inside the micropores. In vitro release experiments showed fast release kinetics provided the drug molecules were evenly deposited over the mesoporous surface.

  9. Study of the Mechanical Properties and Vibration Isolation Performance of a Molecular Spring Isolator

    Directory of Open Access Journals (Sweden)

    Muchun Yu

    2016-01-01

    Full Text Available Molecular Spring Isolator (MSI is a novel passive vibration isolation technique, providing High-Static-Low-Dynamic (HSLD stiffness based on the use of molecular spring material. The molecular spring material is a solid-liquid mixture consisting of water and hydrophobic nanoporous materials. Under a certain level of external pressure, water molecules can intrude into the hydrophobic pores of nanoporous materials, developing an additional solid-liquid interface. Such interfaces are able to store, release, and transform mechanical energy, providing properties like mechanical spring. Having been only recently developed, the basic mechanic properties of a MSI have not been studied in depth. This paper focuses on the stiffness influence factors, the dynamic frequency response, and the vibration isolation performance of a MSI; these properties help engineers to design MSIs for different engineering applications. First, the working mechanism of a MSI is introduced from a three-dimensional general view of the water infiltration massive hydrophobic nanoporous pores. Next, a wide range of influence factors on the stiffness properties of MSI are studied. In addition, the frequency response functions (FRFs of the MSI vi